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IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 

In re Patent Application of Date: May 15, 2008 

Applicants: Bednorz et al. Docket: YO987-074BZ 

Serial No.: 08/479,810 Group Art Unit: 1751 

Filed: June 7, 1995 Examiner: M. Kopec 

For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 

United States Patent and Trademark Office 

P.O. Box 1450 

Alexandria, VA 22313-1450 

APPEAL BRIEF 
PART IX 

CFR 37 §41 .37(c) (1) (ix) 

SECTION 1 



VOLUME 5 
Parti 

BRIEF ATTACHMENTS AA TO AL 

Respectfully submitted, 



IBM CORPORATION 
Intellectual Property Law Dept. 
P.O. Box 218 

Yorktown Heights, New York 1( 



/Daniel P Morris/ 

Dr. Daniel P. Morris, Esq. 
Reg. No. 32,053 
(914) 945-3217 



BRIEF ATTACHMENT AA 





IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 1, 2005 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



In response to the Office Action dated July 28, 2004, please consider the 
following: 



FIRST SUPPLEMENTAL AMENDMENT 



Sir: 



ATTACHMENT AA 



Serial No.: 08/479,810 



Page 1 of 5 



Docket: YO987-074BZ 



Powder Diffraction File 



Inorganic Phases 

Alphabetical Index (Chemical and Mineral Name) 




INTERNATIONAL CENTRE FOR DIFFRACTION 



Powder Diffraction File 



Alphabetical Index 
Inorganic Phases 
1989 



ciation, American Society fo r les ^ Association, The Clay Mm- 

Analytical Assoaatoon British CrystaDo^pn^ rf physics 

erals Society, Deutsche ^^^^^,0^ Society of 
The Mineralogical ^^^^^ an d Ireland, National As»- 

«sp^^s^ ™ de Min6ralogie et de 



Cristallographie. 



Published by the 

INTERNATIONAL CENTRE FOR DIFFRACTION DATA 

,601 PARK LANE • SWARTHMORE, PA 19061-2389 • U.S.A. 



Copyright • JCPDS International Centre for Diffraction Data 1989 

formerly the 
Joint Committee or, Powder Diffraction Standards 

All riBhts reserved. No part of this publication may be reproduced or transmitted in 
t y X Z„y m ea P ns,electronicormechanical>cluding P ho,oco P y,record.ng^ 
or anyTn'formation storage and retrieva. system, without pernuss.on « wntmg from 
the publisher. 



Printed in U.S.A. 
1989 



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BRIEF ATTACHMENT AB 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 

In re Patent Application of Date: March 14, 2005 

Applicants: Bednorz et al. Docket: YO987-074BZ 

Serial No.: 08/479,810 Group Art Unit: 1751 

Filed: June 7, 1995 Examiner: M. Kopec 

For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 

THIRD SUPPLEMENTAL AMENDMENT 

Sir 

In response to the Office Action dated July 28, 2004, please consider the 
following: 



The attachments referred to herein A to Z and AA are in the FIRST 
SUPPLEMENTAL AMENDMENT. The Attachments AB to AG are attached herein. 



Please charge any fee necessary to enter this paper and any previous paper to 
deposit account 09-0468. 




(914) 945-3217 

IBM CORPORATION 
Intellectual Property Law Depi. 
P.O. Box 218 

Yorktown Heights, New York 10598 



ATTACHMENT AB 




Synthesis of cuprate superconductors* 



CNR Rao, R Nagarajan and R Vljayaraghavan 

Solid State and Structural Chemistry Unit and CSIR Centre ot Excellence in 

Chemistry, fndian Institute of Science, Bangalore 560012, India 

Received 28 August 1992, in final form 19 October 1992 



Abstract There has been vmprecederrted activity perlalnlno to tr» synthesis and 
characterttafion oi superconducting cuprates in the last tew year*. A variety of 
synthetic strategies has been employed to prepare pure monophasic cuprates of 
different families with good superconducting properties. Besides the traditional 
ceramic method, other methods such as eopredpitatton and precursor methods, the 
setMral rsethc^ tt»e alKati ffcm 

employed for the synthesis of cuprates^ Oependir^ on the re^rui^^ 
conditions such as high oxygen or hydrostatic pressure and tow oxygen fuoaclty are 
employed in the synthesis. In this review, we discuss the *yn«heste ct the various 
types of cuprate supercor«do<aore ar^ 

of fh» dWerant methods. We have provided ihe necessary prepaistrw details, 
presenting the crucial information in tabular form wherever necessary. 



1. tntarodueJiOn 

Since the discovery of high-T e superconductivity in the 
La-Ban-Cu-O system [I], a variety of cujaate super- 
conductors with T> going Dp to 128 K have been syn- 
thesized and characterized [2, 33- No otbcr <* 
materials has been worked on so widely and intensely in 
recent years as have the cuprate superconductors. 
Several methods of synthesis nave been employed for 
preparing the cuprates, with the objective of obtaining 
pure roonophastc products with good sufjercoodiicting 
characteristics £3, 4]. the most common method of syn- 
. thesis of cuprate superconductors is the traditional 
ceramic method which has been employed for the prcp- 
ararJon of a large variety of oxide materials [5]. 
Although the csSK^ie method has yielded many of the 
cuprates «^t;if^^ctpry cbafacteristks, different syn- 
thctie sitt&0&%fa*t become necessary in order to 
amt^l^^^^l^bt as the cation composition, oxygen 
5tote%sg^^^afeBa oxidation states and carrier con- 
cehtraSc^^^^SiSRy noteworthy amongst these 
n«ahe* ^^eiflical or solution routes which permit 
better mixing «f the constituent cations in order to 
reduce the diftesion distances in the sohd state [3, rTJ. 
Sach methods include coprctipitation, use of precur- 
sors, the sol-gel method and the use of alkali fluxes. The 
combustion method or self-propagating high- 
tempcrarore synthesis (shs) has also been employed. In 
this review, we will discuss the preparation of cuprate 
superconductors by the i different methods, mentioning 
^Contribution No 874 from the Solid Slate and Structural Chemistry 



the special features of each method and rhe conditions 
employed for the synthesis. In laMe 1+ we give a Ss* of 
the eaprate superwrjdHictors dismissed in tiris review 
along with their structural parameters and ipproxheate 
T c values. Preparative conditioas sod) as reaction tem- 
perature, oxygen jaessare, hydrostatic pressure and 
anm^ing condidona are specified m the discussion and 
given in tabular form where necessary. It k hoped that 
this review will be found useful by practitioners of the 
subject as well as those freshly e»bat*thg on the syn- 
thesis of these materials. 



2. Ceramic method 

The most common method of t^thesaiBg inorganic 
solids is by the reaction of the component materials at 
elevated temperatures. If all fl» «©a$o«*its a» solids, 
the method is called the ceramic method if ©a* of 
the constituents is volatile or sensitive to the atmo- 
sphere, the reaction is carried out in sealed evacuated 
capsules. Platinum, silica or alun^ containers are gen- 
erally used for the synthesis of metal ooides. The start- 
ing ihateriab are metal oxides, cartJpnates, or other salts, 
which are mixed, homogenised a»d heated at a given 
temperature sufficiently long for the reaction to be 
completed. A knowledge of tb* phase diagram is useful 
in fixing the ccrop^sirion and conditions m such a syn- 
thesis. 

The ceramic method generally requires relatively high 
temperatures (up to 2300 K) which are gctwraOy 
attained by resistance heating. Electric arc and skull 



0953-2O48/93/D100O1 + 22 SO7.S0 © 1893 IOP Publishing tld 



1 



truc^fe 



ameters and approximate T c values of 



cupr^ ... 



Cuprate 

LaaCuO,^ 

La a _.Sr.<BajCu0 4 

La a Ca,_,Sr,Cu,0 8 

YBa 9 Cu 3 0 7 

YBa,Cu 4 O e 

BiaSrjCuO. 
BijCa&iCUjOe 
Bl a Ca,Sr,Cu,0, 0 
BijSr^Ln, . .CeJ^CujO^ 
TIjBajCoOs 

TtjCaBa 2 Cu,0, 

Tt.CajBajCUjO.o 

TI(Bal_a)CuO s 

TI(SrLa>CuO $ 

(T'o.»Pb».»)SraCu0 5 

"nCaBa 2 Cu a 0 7 

(TI 0e Pb os )CaSrjCu 3 O 7 

"nSr2Y o .,Ga 0; ,Cu a O, 

TJCajSaaCujO, 

<n«. s P* o . s )Sr,Ca 2 C«i,0 9 

T1Ba 2 (Ln, ..CeJ^CUjO, 

Pb 3t Sr,Ln 0 s Ca<> s Cu,O s 

Pb,(Sr. La),Cu 3 O e 

(Pb. Cu)Sr^Ln. Ca)Cu a 0 7 

{Pb. Cu){Sr, EoKEu, GeJCu^O, 

Sr,./ldjCuG. 



Structure 

Bmafi; a = 5.355, /> = 5.401. c - 13.15 A 
M/romm; a = 3-779. c = 13.23 A 
M/mmm; a = 3.825. c =» 19.42 A 
Pmmm; a = 3.821. b = 3.885. c = 11.676 A 
Ammrrt; * = 3.84. b = 3.87. c = 27.24 A ^ 
Ammm;a = 3J51, 6 = 3.869. c «=■ 5fX29 A 
Amaa ; a = 5.362, * = 5.374, c = 24JS22 A 
A2aa ; a = 5.409. b = 5.420. c = 30.93 A 
A2as; a ~ 5J9. 6 ~ 5 40, c ~ 37 A 
P4/mmm; a == 3.88a c = 17.26 A 
A2aa ; a = 5.468. b = 5.472. 

c = 23.238 A; 14/rnmm; a ■= 3.866. c « 23.239 A 
M/mmm ; a - 3.856. a - 29518 A 
M/mmm: a = 3.85. c » 35.9 A 
P4/mmm: a = 383. c = 9.55 A 
P4/mmm; a ~ 3.7, c ~ 9 A 
P4/mmm ; a =» a 738, c » 9.01 A 
P4/mmm ; a = 3.856, c » 12.754 A 
P4/mmm; a « 3.80. c - 12.05 A 
P4/mmm; a = 3.80, c = 12.10 A 
P4/mmm ; a =» 1853, c' « 15513 A 
P4/mmm : a = 3.81. c = 15.23 A 
M/mmm; a - 3.8, c ~ 29.5 A 
Cmmm; a = 5.435. * = 5.463. c = 15.817 A 
P22,2; a - 5.333. b = 5.421. c = 12.609 A 
P4ymmm;* ~ 3.820. c = 11.826 A 
M/mmm; a = 3.837. c =» 29.01 A 
MAfnmm;a>-3^c »12.07 A 
P4/mmm; a = 3.902. c=* 3.35 A | 
P4/mmm;« =3^42. c = 3393 A 



r e (K) 

(max. value) 



techniques give temperatures up to 3300 K while high- 
power CO, lasers give temperatures up to 4300 K. The 
main disadvantages of the ceramic method are the 
following: 

0) The starting mixtures are tahomogeneous at the 
atomic kvei 

{h> When no melt is formed during the reaction, the 
entire reaction has to occur in the soBd state, first by a 
phase boundary reaction at the points of contact 
between the components and later by the diffusion of 
the constituents through the product phase. With the 
progress of the reaction, diffusion paths become longer 
and the reaction rate slower; the reaction can be 
speeded up to some extent by intermittent grinding 
between heating cydes. 

(m) There is no simple way of monitoring the 
progress of the reaction. It is by trial and error that one 
decides on the appropriate conditions required for the 
completion of the reaction. Because of this difficulty, 
with the ceramic method one often ends up with mix- 
tures of reactants and products. Separation of the 
desired products from such mixtures is difficult, if not 
impossible. 

ftv) Frequently it becomes difficult to obtain a com- 
posirionalry homogeneous product even where the reac- 
tion proceeds nearly to completion. 

Despite the above limitations, the ceramic method is 
widely used for the synthesis of a large variety of inor- 
ganic solids. la the case of the cuprate superconductors. 



the ceramic method mvofm mixing and grinding th< 
component oxides, carbonates or other salts, and 
heating the mixture, generally in pellet form, at tb* 
desired temperature. A common variation of Uk 
method is to heat a mixture of nitrates obtained 05 
digesting the metal ex&es/esjtemxte in concentrated 
HNOj and evaporating the solution to dryness 
Heating is carried oat ra asr ffcr m an appropriate atmo 
sphere, controlling tl« oartiaj r^ressurc of oxygen when 
necessary. In the case cf ttaflram cupratcs, because o 
the volatility and poisonous nature of the thaffitm 
oxide vapour, reactions are carried out in sealed tubes 
In come of the earlier r^reparatkms, the thaffium cup 
rates were synthesized In open furnaces. This is 
however, not recommended. A successful synthesis bj 
the ceramic method depends on several factors whSd 
indude the nature of the starting naterials (the choia 
of oxides, carbonates), the homogeneity of the mixturt 
of powders, the rate of heating as well as the reactfe* 
temperature and duration. 



11. La 3 Cu0 4 ^e!ated 214 canrates 

Synthesis of idkajme-<artfc-*>ped Uj.,M,Cu0 4 
(M = Ca, Sr and Ba) of iCjlW* structure with super- 
conducting transition temperatures up to 35 K k 
readily achieved by the ceramic method. TypMly, the 
synthesis is carried oat by reacting stoichiometric quan- 
tities of the oxides and/or carbonates around 1 300 K in 



oxyge n aunospncre at 01* k alter tn^~ >t«nng step 
(TlOj. taw 41so use^P starting 

^teriak for the synthesis [11-13]. By starting with 
metal nitrates, one obtains a more homogeneous start- 
ing mixture, since the hydrated metal nitrates have low 
melting points leading to a uniform melt in the initial 
stage of the reaction. Furthermore, nitrates provide an 
oxidative atmosphere, which is required to obtain the 
necessary oxygen content. 

Stoichiometric La 2 Cu0 4 is an antiferromagnetic 
insulator. La 2 Cu0 4 prepared under high oxygen pres- 
sures, however, shows superconductivity (T t ~ 35 K) 
since the oxygen excess introduces holes just as the alk- 
aline earth dopants [14-16]. La 2 Cu0 4+ , (6 up to 0.05) 
has been synthesized by annealing La 2 Cu0 4 under an 
oxygen pressure of 3 kbar at 870 K [14, 15] or 23 kbar 
at 1070 K [16]- Oxygen plasma has also been used to 
increase the oxygen content 

The next homologuc of La 2 Cu0 4 containing two 
Cu-O layers, L&^T^OtCujO^ (T c ~ 60 K), has been 
syMfeesEsed by using high oxygen pressures [17]. The 
synthesis involves heating the sample at an oxygen pres- 
sure of around 20 bar at 1240 K. The material prepared 
at ambient oxygen pressures (in air) is an insulator. 
Several other high-oxygen-pressure preparations have 
been reported on the n - 2 member of the 
La i+ jCu 2 ,0 4l » 3 homologous series by making use of 
commercialry available high-pressure furnaces [18, 19}. 
In tabled we have summarized the preparative condi- 
tions for 214 and related cuprate superconductors. 

22. YBa a Ca 3 0 T and other 123 cuprates 

Superconducting YBa 2 Cu 3 0 7 - 3 with the orthorhombic 
structure can be easily prepared by the ceramic method. 
Most of the investigations of the 123 compound, 
YBajCujO^ have been carried out on the materials 
prepared by reacting Y 2 Oj and CuO with BaC0 3 [20* 
21]. It is noteworthy that Rao et at [21] obtained 
monophasic YBa 2 Cu 3 0 7 as the x =1.0 member of the 
Y 3 _,Ba3 +x Gu 6 O l4 series. In the method employed for 
preparing YBa 2 Cuj0 7 , stoichiometric quantities of 
high-purity Y 2 0,, BaC0 3 and CuO are ground thor- 
oughly and heated initially in powder form around 
1223 K for a period of 24 h. Following the calcination 
step, the powder is ground, pelletized and sintered at 
the same temperature for another 24 h. Finally, anneal- 
ing is carried out in an atmosphere of oxygen around 
773 K for 24 h to obtain the orthorhombk 
YBa 2 Cuj0 7 _, phase showing 90 K superconductivity. 
Oxygen annealing has to be carried out below the 
onhorhombic tetragonal transition temperature (~960 
K); tetragonal YBa 2 Cu,0 7 _, (0.6 < h < 1.0) is not 
^reconducting. Intermittent grinding is necessary to 
obtain monophasic, homogeneous powders. This kind 
of complex heating schedule often gives rise to micro- 
scopic compositional inhomogeneities. Furthermore* 
C0 2 released from the decomposition of BaCOj can 
react with YBajCu 3 0,_ a to form non-superconducting 



W eyoiupon <a tv a d ■ * me jgggJ[I£&$Hb use 

Bao 2 is^&W&jQ Vteta* & mm- 

rities or side products in tiSpi operation of YBa 4 Eu,#» 7 
are BaCuO,. Y 2 BaCuO, and Y 2 Cu 2 0 3 [24]. The 
ternary phase diagram given in figure 1 illustrates the 
complexites of this cuprate system. 

Using BaOj as the starting material has two advan- 
tages. It has a lower decomposition temperature than 
BaCOj and the 123 compound is therefore formed at 
relatively low temperatures. Ba0 3 acts as an internal 
oxygen source and the duration of annealing in an 
oxygen atmosphere is reduced to a considerable extent 
Sharp superconducting transitions are observed in 
samples of YBa 2 Cu 3 0 7 _, made using BaQ 2 . Slight 
excess of copper in the ceramic method is reported to 
give cuprates with sharper transitions [25]. Preparation 
of YBa 2 Cu 3 0 7 _, is accomplished in a shorter period 
if one employs metal nitrates as the starting materials 
[13, 23]. In table 2, we present the conditions employed 
for preparing 123 cuprates by the ceramic method. 

Other rarereartb cuprates of the 123 type, 
LnBa 2 Cu 3 0 7 . 4 where Ln - La, Nd, Srn, Eu, Gd, Dy, 
Ho, Er and Tm (all with T c values around 90 K) have 
also been prepared by the ceramic method [26, 27]. 
Oxygen annealing of these cuprates should also be 
carried out below the orthorhomic-tetragonal tran* 
sition temperature [3]: La, 754 K; Nd, 837 K; Gd, 
915 K; Er, 973 K; Yb, 976 K etc Nearly 30% ofY can 
be substituted by Ca in YBa 2 Cu,0 7 _ t , retaining the 
basic crystal structure [28]; the T e deereases with the 
increase in calcium content Both La and Sr can be sub- 
stituted at the Ba site in YBa 2 Cu 3 0 7 _i [29-31], W?ft& 
La, monophasic products are obtained for 0 « x « 1.0 
in YBa 2 ^ I La i CujQ 7 -*, the T e decreasing with increase 
in x. In the case of Sr substitution, monophasic 
products are obtained for 0 «S x < 1.25 in 
YBaj.^Sr^CUjOT-,; high T t is retained up to x = 1.0. 
Ceramic methods have also been used to prepare 
YBa 2 Cu 3 -,M,0 1 -4 solid solutions, where M generally 
stands for a transition demeri t of the first series. In most 




Figure 1. Phase diagram of the Y 3 0 3 tBsO-Cu6 system at 
1220 K (from [24]). 



3 



rapwiy witn mcreasmgievei 01 suost^^ *» ISAM}- 

23. YB*jCu 4 0, (124), Y 2 Ba 4 Cu 7 0 I5 (247) and related 
cuprites 

The first bulk synthesis of YBa 2 Cu 4 O g was reported by 
Karpinski et al [34] who heated the mixture of oxides 
at 1313 K, under an oxygen pressure of 400 bar. Synr 
thesis of YBa 2 Cu 4 0 8 by the conventional ceramic 
method without the use of high oxygen pressure suf- 
fered from some limitations due to kinetic factors. Cava 
et of [35} found that additives such as alkali carbonates 
enhance the reaction rate. The procedure involves two 
steps. In the first step Y 2 Oj , Ba(NOj) 2 and CuO are 
mixed in the stoichiometric ratio and heated at 1023 K 
for 16—24 h in an oxygen atmosphere. In the second 
step, the pre-reacted powder is ground with an approx- 
imately equal volume of either Na^CO, or K 2 C0 3 
powder and pellets of the resulting mixture are heated 
at 1073 K in flowing oxygen for 3 days. After the reac- 
tion, the product is washed with water to remove the 
excess alkali carbonate and dried by gentle heating in 
air. The product after the step has YBa 2 Cu 4 0 8 as the 
majority phase (T c , 77 K) with little BaCu0 2 impurity. 
Other reaction rate enhancers such as NaN0 3 , KN0 3 , 
dilute BNGj and Na 2 0 2 have also been used suc- 
cessfully (in small quantities) to prepare YBa 2 Cu 4 O s 
[36-38]. The 124 cuprate can also be prepared without 
the addition of a rate enhancer by the solid state reac- 
tion of Y 2 0,, BaCuOj and CuO at 1088 K in flowing 
oxggen tpfe Synthesis of YBa 2 Cu 4 0, from the solid 
state reaction between YBa 2 Cu,0 7 and CuO in flowing 
oxygen has also been reported [39]. The synthesis of 
YBajCu^O, by the ceramic method generally takes a 
long time and requires repeated grinding and pellet- 
izing. 

Other rare-earth 124 cuprates, LnBa 2 Cu 4 O s with 
Ln ~ Eu, Gd, Dy, Ho and Er have been prepared by 
the ceramic method under an oxygen pressure of 1 atm 
[36, 40}. The 7~ of these cuprates decreases with the 
increasing ionic radius of the rare earth. Calcium can be 
substituted at the Y site up to 10% in YBa 2 Cu 4 0 8 , and 
tb* T, increases from 79 K to 87 K in such substituted 
YBa 2 Cu 4 0, [41]. Lanthanum can be substituted for 
barium m YBa 2 Cu 4 0 8 [42]. Single phases of 
YBa 2 _ JLa,Cu 4 0 8 have been obtained for 0 «s * «* 0.4 
wife the T t decreasing with increase in x. 

Extensive studies have been carried out on the syn- 
thesis of YBa 2 Cu 4 O s under high oxygen pressures [43, 
44]. The P-T phase diagram of 124, 123 and 247 cup- 
rates is shown in figure 2. High-oxygen pressure synthe- 
sis essentially involves the solid state reaction followed 
by sintering under high oxygen pressures. The typical 
sm tering teiqperature and. the pressure at which synthe- 
sis 0fYBa 2 Gu 4 O 8 has been carried out are 1200 K and 
120 atm of oxygen (for 8 hi By the use of high oxygen 
Pressures [45], it is possible to prepare 124 compounds 
other rare earths such as Nd and Sm, which is 
0( nerwisc not possible under ambient pressures. 




Flgur* 2. Ptiase diagram of the 1 24, 247 and 123 cuprates 
(trom[433). 



A variety of substitutions has been carried out at 
the Y, Ba and Cu sites in YBa^C^Oa under hjgh 
oxygen pressures. Yttrium can substitated up to 10% 
by Ca in YBa 2 Cu 4 0 8 giving a T, of ~9Q K [461; 20% 
Ba has been substituted by Sf without affecting tb* T. 
[47]. Single-phase iron-substituted VBa 3 Cu 4 _ ,Fe^O, 
(0 ^ x < 0.05) has been prepared at an oxygen pressure 
of 200 bar [48]; the 7; falls monotonfeaBy with increas- 
ing iron concentration. 

Bordet et al [49] first reported the preparation of 
Y 2 Ba 4 Cii 7 0,5 under oxygen pressures of 100-200 bar. 
It was soon realized that Y i Ba 4 Cu 7 0, J can be synthe- 
sized by the ceramic method under an caygen r^essure 
of I atm by a procedure similar to that employed for 
YBa 2 Cu 4 0 8 , except for the difference in the sidteriog 
temperature [36]. There s a narrow stability region 
between 1123 K and 1143 K for t}ie 247 oiprate to ee 
synthesized under 1 atm oxygen pressure. The best 
sintering temperature at which the 247 cuprate is 
formed is 1 133 K. Other rare-earth 247 cuprates, 
Ln 2 Ba 4 Cu 7 0, s (Ln = Dy, Er), can also be prepared by 
this method [36, 38J. About 5% of Y can be replaced by 
Ca in Y 2 Ba 4 Cu 7 0, , and the 7; increases to 94 K [42]. 
Substitution of La at the Ba site is limited to -^10% in 
Y 2 Ba 4 Ca 7 0,, where the T t decreases continuously with 
increasing lanthanum content [42]. 

Synthesis of 247 cuprates by the high-pressure 
oxygen method is generally carried out at 1203 K at an 
oxygen pressure of around 19 bar (for 8 h). This step is 
followed by slow cooling (typically 5 °C min -1 ) to room 
temperature at the same pressure [50]. Other rare-esifth 
247 compounds, Lo 2 Ba 4 Cu 7 0, 5 (Ln = Eu, Gd, Dy, Ho 



5 




and Er), have been prepared in the oxygen pressure 
range of 14-35 bar [50). Preparative conditions for the 
124 and 247 cu prates are given in table 2. 

2.4. Bisnrath copra tes 

Although the ceramic method is widely employed for 
the synthesis of superconducting bismuth cuprales of 
the type Bi,(Ca. Sr)„ +l Cu,Oj. +4t ,, it is generally diffi- 
cult to obtain roooophasic compositions, due to various 
factors [51, 52]. Both thermodynamic and kinetic 
factors arc clearly involved in determining the ease of 
formation as well as phasic purity of these cu prates. The 
n = 1 member (2201) of the formula Bi 2 Sr,CuO A 
appears to be stable around 1083 K and the n — 2 
member, BMCa, S^,Cu,0 8 (2122) around 1113 K. The 
n = 3 member, Bi^Ca, Sr) 4 Cu 3 O, 0 (2223), can be 
obtained dose to the melting point (1 123 K) after 
healing for several day* or even weeks. Of all the 
members of the Bi^Ca, Stl + ,Ca m O u ***t tumly, the 
n = 2 member (2122) seems to be most stabfcs. Bi 2 0,, 
which is often used as one of the starting materials, 
melts at around 1103 K. Increasing the reaction tem- 
perature therefore leads to preferential loss of volatile 
Bi 2 Oj. This results in micro-inhoroogeneitics and the 
presence of the unreacted oxides in the final product 
Since these materials contain so many cations, partial 
reaction between various pairs of oxides leading to the 
formation of impurity phases in the final product 
cannot easily be avoided. A noteworthy structural 
feature of aO these bismuth cuprates is the presence of 
superiatrJce modulation; the modulation has nothing to 
do with supercondactiviry. 

Most of the above problems have been overcome by 
employing the matrix reaction method [53, 54]. This 
method reduces the number of reacting components 
and gives better products. In this method, synthesis is 
carried out by reacting the oxide matrix made from 
CaCO,, SrCO s and CuO with BijO, in the tem- 
perature range of 1083-1123 K in air for a miniraum 
period of 48 h. Ouenching the samples in air from the 
sintering temperature or heating in a nitrogen atmo- 
sphere improves the superconducting properties of 
bismuth cuprates. The matrix reaction method yields 
monophasic » = 2 (2122) and » = 3 (2223) compositions 
showing T t values of 85 K and 1 10 K respectively [35, 
561. Partial melting for a short period (~5 min) also 
favours the rapid formation of the * => 2 (2122) and the 
n = 3 (2223) members. 

The n = 1 member, Br J Sr J CuO lS , showing T, in the 
range 7-22 K is a rather complicated system and has 
two structurally different phases near the stoichiometric 
composition [51, 57-60]. Many workers have varied 
the Bi/Sr ratio and obtained single-phase materials wkh 
a 7; of 10 K at a composition which is strontium defi- 
cient, K 4 .,Sr 1 .,CnP, [60, 61]. This cuprate is best pre- 
pared by reacting the oxides and/or carbonates of the 
constituent metals at 1123 K. in air for extended periods 
of time. In figure 3 we show the phase diagram of the 
Bi-Sr-Cu-O system. The phase diagram of the 




Figure 3. Phase diagram of the 8i-€r-Cu-b system at 
1 1 to K m air (from [COB. 

Bi 2 Oj-SrO-CaO-CttG system at a constant Ct 
content is shown in figure 4. 

Substitution of * small amount of lead for htsrat 
results to food sur^crcondocting samples of n = 2 (21: 
and ii = 3 (2223) members. A norober of workers ha 
therefore preferred to synthesize both n — 2 (2122) a 
n = 3 (2223) members with substitution of lead up 
25% m place of bismotb [58, 63-663- They are obtain 
either by direct reaction of oxides and/or carbonates 
the cations or by the matrix reaction method. 

Other than &e matrix reaction method, melt que 
ching (glass route) {67. 68] and a semi-wet method [6 
have been employed for the synthesis of s up ct t o adu t 
irig bismuth cuprates. In the inert queriCfiing metho 
the mixture of starting materials fm the form of ocrid 
and/or carbonates) is melted in a platinum or aluraii 
crucible around 1473 K for a short period in air ar. 
then quenched in liquid nitrogen. The qoendK 
speciroens are given an annealing treatment aroun 
1 103 K in air to obtain the soperoOTducting crystalfn 
cuprates. This method has been shown to produt 
both n = 2 (2122) and lead-doped m « 3 (2223) roembo 



CaO 




SrO B»0, s 
R9or»4. Section trwouoho»©ptesedlan»am o»«» 
BJjOj-SrO-CaO-CuO system at a constant CuO content ot 
S&.6 mol% (from [62]). 



sggu^wci meinoa involves lac nc reaction 

between two piecuisoirs which ^ .Tjcipltatfed 
scparatcty. For example, in the pieparation of 
Bi,.«Pbo, 4 Sr 2 Ca 2 Cu 3 0 10 , a precipitate of Pb, Sr and 
Ca (as carbonates) and one of Bi and Cu (as oxalates) 
are reacted at 1138 K in air for a minimum period of 
72 h. The duration of the reaction for the formation of 
2223 phase is drastically reduced by this method. 

The starting composition of the reactant materials 
plays an important role in the synthesis of these cup- 
rates. For example, strontium deficiency in the n = 1 
(2201) member favours monophasic compositions [59, 
61). Strontium deficiency also helps in obtaining a 
phaserpure n * 2 (2122) member [70]. Starting with a 
4:3:3:4 stoichiometry of Bi:Ca:Sr:Cu, it has been 
possible to obtain a monophasic 2122 member [54, 71]. 
The n *> 3 (2223) phase, oil the other hand, is either 
obtained through the substitution of Bi by Pb (up to 
25%) or by taking an excess of Ca and/or Cu [63-66, 
72]. The problem of balancing between phasic purity 
and high % of the cuprate gives rise to some difficulty in 
the synthesis of these euprates. The coexistence of some 
of the members of the homologous series, especially in 
the form of polytypic intergrowths of different layered 
sequences, is also a problem. This problem is also 
encountered with thallium euprates £73, 74]. 

The /> = 4 phase, Bi 1 .jPbo. J Ca 3 Sr 2 Cu 4 0, 2 , which 
was observed in an electron micrograph along with 
n - 3 phase as an intergrowth, was synthesized in bulk 
by Rao et cd [75] (with a small proportion of the n = 3 
phase) by the ceramic method. The » = 4 phase has a 
slightly lower T e (103 K\ than the n = 3 phase. This 
cuprate has also been prepared by Losch et al [75]. 

A variety of substitutions has been carried out in 
superconducting bismuth euprates employing the 
oefsunic method [58, 76-79]; some of them are note- 
worthy. For example, the simultaneous substitution oT 
Bi by Pb and Sr by La in Bi 2 Sr 2 Cu0 6 results in a 
modulation-free superconductor of the formula 
Ba^STj^Laj ..CuO^ with T t increased to 24 K [77]. 
SfajMy. co-substitutiOn of Bi by Pb and Ca by V in 

n « 2 member (2122) gives a modulation-free SUper- 
Wuctor, BjPbY 0>> Ca 0 9 Sr 2 Cu a O, with a T t of 85 K 
C^j. Rare-earth substitution for Ca in BijCaSrjCujOs 
eauses the T t to go up to 100 K without the intro- 
duction of the n = 3 phase [58, 78]. As mentioned 
earlier, the n » 3 phase is stabilized by the partial sub- 
stitution of lead in place of bismuth [63-65]. Another 
*8?«fr»Dt discovery is the iodine intercalation of the 

2,22 superconductor [80]. Intercalation does not 
greatly affect the superconducting properties of the 
^'wjal; clearly, superconductivity is confined to the 

°^ancnsional Cu0 2 sheets in these materials, 
rat y " f thcsis of a ncw series of superconducting cup- 
(bS^,* 0 Bcneral formula BijSr 2 (Ln, ..Ce^CujO.o 
fluori Pl,aSC with Ln=:Sm . Eu - Gd) containing a 
c "0 w (Ln * -' Ce ^°J u y tr between the two 
[8 II J p R as been possible by the ceramic method 
artial substitution of bismuth by lead increases 



sjs at osi aim oi Mi sege stabilize *ne Structure 
with othfcf rareeafthi^P 

As mentioned earlier, one does not start with an 
exact stoichiometric composition to obtain the desired 
final product in the case of superconducting bismuth 
euprates. Although structural studies (see for example 
[84]) indicate the presence of bismuth atoms over stron- 
tium and calcium sites as well, it is not possible to pre- 
scribe an exact initial composition to obtain the desired 
final stoichiometry. For example, starting from a 
nominal composition of (Bio.TPbojJSreaCuaQ, , one 
ends up with the formation of the » ■= 3 (2223) member 
[65]. Therefore, for the purpose of characterizing the 
various members of the superconducting bismuth cupr 
rates, one starts with some arbitrary composition and 
varies the synthetic conditions suitably to obtain the 
desired final product in pure form. The actual composi- 
tions of the final cuprate are quite unexpected (eg. 
Bii^ 3 Pbp., 0 Sr 2 W Ca,. 6e Cu 3 0^ as found froth analyti- 
cal electron microscopy [85]. In table 3 we have sum- 
marized the preparative conditions of all the members 
of Bi 2 (Ca, Sri, >1 Cu 1 ,p 2)lt4+ , family. 



25. Thallium euprates 

The conventional ceramic method employed for the 
synthesis of 214, 123 and bismuth euprates has to be 
modified in the case of thallium euprates of the 
TI 2 Ca..,Ba 2 Cu.Oj i ,* 4 , TlCa,. 1 Ba 2 Cu,0 2llt3 and 
TlCa,.,Sr 2 Cu,0 2 . >3 families due to the toxicity and 
volatility of thallium oxide. In the early days; the reac- 
tion was carried out in an open furnace in air or oxygen 
atmosphere at high temperatures <1 150-1 189 K) for 
5-10 thin [86, 87]. In a typical procedure, the mixture 
of reactants in the form of a pellet was quickly intro- 
duced into the furnace maintained at the desired tem- 
perature. Since melt-solid reactions take place faster 
than solid-solid reactions, the product was formed 
quickly by this method [87]. Although this method 
requires a very short duration of heating, it results in 
the loss of thallium, leading to the danger of inhaling 
thallium oxide vapour. Some workers have taken 
certain precautions not to release the Tt 2 O s vapour into 
the open laboratory, but the method is. still hot recom- 
mended. Furthermore,' the formation of the desired 
phase is not ensured under the open reaction condi- 
tions. Synthesis of thallium euprates has therefore been 
carried out in closed containers (sealed tubes) by most 
workers. By this method, both porycrystallin* samples 
and single crystals can be prepared, since the reaction is 
carried out over longer periods. Better control of stoi- 
chiometry, homogeneity of phases and the total avoid- 
ance of the inhalation of toxic thallium oxide vapours 
are some of the advantages of carrying out sealed tube 
reactions. 

Closed reaction conditions have been achieved in 
different ways. The reactant mixture is sealed in gold 
[88] or silver tubes [89] or in a platinum [90] or nickel 



7 



u n h Hao et at ^ ^ 

Table 3. Preparative conditions lor the synthesis ol bismuth cuprates by the ceramic method. 





Conditio 










Starting composition 


Temp. (K) 


Time 


Product 


7 t (K) 


Ref. 








2201 major phase 




[61J 


Bi a Sr,C«0 6 


1123 




2201 major phase 


8 


[57] 


Bi a .,Sr,^CwO, 


1123 




Single phase 


10 


[59. 61] 


8iPt>Sr,.. i La,_,CuO < 
BijCaSr^CujO. 


1150 




Single phase 




[773 


1103 


5d 


Single phase 


ftR 


[313 


B«»C«t.»Sr».8C«»i 0 » " 






2122 major phase 


an 


{$33 


Bi 4 Ca 3 Sr s Cu 4 0, 


1106 


2d 


2122 single phase 




P13 


Bi 2 Sr, ,CaCu 3 0, 


1113 




2122 single phase 


85 


[70] 


BiPbSr :l Y 0 . 9 Ca< > 5 CUjO s 
W, V*tt.«Ca a Sr 3 CojO, • 


1200 


1 d 


2122 single phase 


65 


C77] 


1140 


Sd 


2223 major phase 


120 
105 




B»» .»Pt»aLsCa 2 . 8 Sr,. s eu,0, " 


1100 


4d 


2223 major phase 


t«43 


Bi, yPb 0 ,Srj,Ca,Cu 4 0, 


1153 


10 d 


2223 single phase 


110 


[72] 


B^.Ptv.SrCaCu, s O, 


1153 


Sd 


2223 major phase 


105 


[653 


BiCaSrCUjO, 


1143 


Sd 


2223 major phase 


120 




Bi, I Pb a «Ca s Sr«Cu70 i 


1133 


5d 


2223 major phase 


108 


£643 




1273 


10 h 


2222 single phase 


30 


C813 



* Obtained by matrix reaction method. 



alloy (Incond) container [91] closed tightly with a silver 
lid. Alternatively, the reactant mixture is taken in the 
form of a pellet, wrapped in a platinum [92] or gold 
£93] foil and then sealed in a quartz tube, this method 
has the advantage of carrying out the reaction under a 
vacuum. Some workers place the reactant pellet in an 
ahnniria cruciWe [94] which is then sealed in a quartz 
ampoule. Thallium-excess starting compositions have 
been employed by a few workers to compensate for the 
thallium loss during the reaction [95]. 

In the preparation of the thallium cuprates, the 
matrix reaction method is often employed. Here, a 
mixed oxide containing aB the metal tons other than the 
volatile thalium oxide is first prepared by reacting the 
corresponding oxides and/or carbonates around 1200 K 
lor.24h m air [89,96]. The freshly prepared mixed 
oxide is then taken with a calculated quantity of TI^O, 
and heated at appropriate temperatures in a seated 
tube. This method is desirable when a carbonate is used 
as the starting material. Some of the thallium cuprates 
nave been prepared by a modified matrix method [97] 
wherein a tliaffionwxsntaming precursor such as 
Ba 2 Tt,0 } is prepared first and then reacted with other 
component* under closed conditions. ThaBium- 
containing precursors are less volatik than f1,0, 
so that the loss of thaBinm is minimized during the 
preparatiott. 

Thennotrynarnic and kinetic factors associated with 
the synthesis of thallium cuprates are complex due to 
the existence of various phases which are structurally 
related and which can therefore intergrow with one 
another, la feet, one of the common defects that occurs 
in the tnaffimn cuprates is the presence of random inter- 
growths between the various layered phases [983. Fur- 
thermore, many of the thallium, lead and bismuth 
superconductors are metastabk phases which are 
entropy stabilized [99]. The temperature of the reac- 



tion, the sintering time and the starting composition arc 
therefore all crucial to obtaining monophasie products 
(table 4X 

The effect of the starting composition is best illus- 
trated by the formation of the a = 3 phase of the bilayer 
thallium cuprates (n 2 €a z Ba,aifO,o). Synthesis of this 
compound starting from the stoichiometric mixture of 
the oxides corresponding to Ac ideal composition often 
yields the « = 2 member of the feraay. U was feBftd that 
starting with compositions rich m Ca and/or Co 
(namely TTCa,BaCu,0,, TljCa^BajCwjO,) yielded a 
nearly pure n - 3 phase [90. 98, VXfi- TJ* actual com- 
position is, however, close to Tl, .tBaiG^jCujOj. In 
the case of TICaBa 2 Cu 2 0 7 (1122) starting front a st©*> 
diiometric mixture of oxides corresponding to the ideal 
stoichtornetry always yielded a mixture of 1122 and 
2122 phases, the relative proportion of the two being 
dependent on the conditions. It has been demonstrated , 
recently [101] that ttaBium^steiWtt compositions cor- j 
responding to Tlj _,CaBa z Cu,0, = <M> to 03) yield 
better monophasie 1 122 materials. 

The thallium content of the rraterial not only <fefe* 
mines the number of Tl-O layers but controls the hofc ! 
concentration. As mentioned earlier, one of the good I 
starting compositions to obtain T^O^BSi©^^ 
(2223) is TTCa,BaCujO, (1313) which heats fittle rela- 
tion to the composition of the final product Another 
example is the formation of the » = 4 phase, 
TJGajBa.CtuO, (1324). Detailed studies [HEQ have 
shown that the 2223 phase formed initially transforms 
to the 1223 phase with an increase to the dwatioo «f 
beating. After prolonged sintering, the 1354 phase » 
formed at the expense of the 1223 phase. Simitar trad* 
formations have also been observed in the formation | 
process of TICa^BaiCujQ, with five Cu-O rayer* £103]. 

The Sr analogue of TlCa - _ 1 BaaCu J ,Oj j( *j cannot be 
prepared in pure form. However, they are stabilized by 



Starting composition Temp. (K^^ .•. .a Gas Product T e (K) Bel. 





1148 




Id tubes 


2201 sinoie chase 


84 


r 

188J 


TIjCaBaaGujO, 


11S 




. , . . . 
SOftled QOK!1UDd$ 


2122 slnole Dhase 


98 


[88] 








2122 single phase 


95 


[98] 


TIjCa^BajCUjO, 


1150 


05 h 




2122 single phase 


95 


[98] 


TI 4 Ca 3 Ba 4 Co s O, 


1150 




Seated silica ampoule 


2122 single phase 


95 


[98] 


T^Ca^&a^C^OjQ 


1173 




Sealed gold tubes 


2??3 major phase 


105 


[88] 


1123 


20 

ic> h 1 '" 


Sealed silica ampoule 


*yyx\ fns|or phase 


106 


[95] 




11 M 












TICa^BaGuaO, 


1153 


3h 


Sealed silica ampoules 


??23 major phase 


125 


[100] 


T) a CaBa a Cu 3 0, 


1153 


3h 


Sealed sIKca amooules 


222fl major phase 


108 


[100] 


TIBa t _ a La 0 B CuO s 






of u!a air ^^°i*nt 


1021 single phase 






TISrLaCu0 5 




9 h 




1021 single phase 


40 


[109] 


TK»r 2 . e Nd 0 ^Cu^O, 


1170 




_ a ... J*™. 


1122 major phase 


80 


[110] 


7ICaBa 2 CtJj0 7 


1170 


3 h 


Se led T ^les 
a st ica ampou 


1122 major phase 4* 


90 


[101] 








2122 impurity 






Tlj s GaBa a Cu 2 u 7 


1170 


3h 


Sealed sliver tubes 


1 122 major phase 


90 


[101] 


nV 9 Pt>o 5)CaSrsCo a 0 7 


1170 


3h 


Sealed silica ampoules 


1122 single phase 


90 


[104] 




1170 


3h 


Sealed silver tubes 


1122 single phase 




[92] 


TtCajBaiCuaOj 


1163 


6h 


Sealed silica ampoules 


1223 single phase 


115 


[94] 




1198 


3-12 h 


Sealed gold tubes 


1223 single phase 


122 


[105] 


Tio.sPbo.sS^s 0 . 


1170 


2h 


Sealed silica ampoules 


1223 major phase 


60 


£110] 



partly substituting Tl by Pb (or Bi) or Ca by yttrium or 
a frivatent rare earth [92, 104-107]. Thus, 
11 <)4 Pb 0 ,Ca..,SF I Cu,0 3j , + j shows a T c of ~90K for 
n = 2 and -120* for n = 3. TlCao/jY^SriCujO, 
also shows a T t of 90 K. These cuprates in the TtyPb- 
Ca/Ln-Sr-Cu-O systems are prepared in a manner 
similar to the Tl-Ca-Ba-Cu-O system except that 
SrC0 3 is used in place of BaC0 3 or Ba0 2 . Sr 4 Tl 2 0 7 
has also been used as a starting, material in some 
instances [97]. The n = 1 member, nM 2 CuO s (M = Sr 
or Ba) is also stabilized by the substitution of Pb or Bi 
for Tl or a trivalent rare earth for Sr or Ba [108-11 1]. 
AH these compounds showing a 7; of 40 K have been 
prepared by the matrix reaction method. 

Single thallium layer cuprates of the general formula 
Tl 1+JI A I _ x LnjCu l 0 9 with A = Sr, Ba; Ln = Pr (Nd, 
€e) as well as T1 0 . 3 Pb o .j(Ln l _ x Ce Jl ) 2 ST I Cu 2 O s> 
(Ln = Pr, Gd) with a fluorite-type Ln 2 0 2 layer have 
been prepared by the ceramic method [112, 1 13]. The 
as-prepared materials are semiconductors. It has been 
shown by Liu « <d £114] that annealing TlBa 2 (Eu, 
Ce) 2 Cu 2 0, (1222 phase) under an oxygen pressure of 
LOO bar induces superconductivity with a T t of ~40 K. 

As in the case of bismuth cuprates, the final com- 
position of thallium cuprates is unlikely to reflect the 
composition of the starting mixture. Structural studies 
C9v, 115] have shown that there is cation disorder 
between Tl and Ca/Sr sites. Therefore, in order to 
obtain a superconducting composition corresponding to 
a particular copper content, one has to start with 
various arbitrary compositions and vary the synthesis 
conditions. The actual composition of the final product 
^ quite unexpected (e.g. Tl,. B3 Ba 2 Ca, , 4 Cu 3 O r or 
.'••**Ba 2 . 01 Gu6,> as shown by analytical electron 
^croscopy [85]. In table 4 we have listed the pre- 



parative conditions employed for the synthesis of thal- 
lium cuprates by the ceramic method. 

2.6. Lead cuprates 

The conditions for the synthesis of superconducting 
lead cuprates arc more stringent than for the other 
copper oxide superconductors. Direct synthesis of 
members of the Pb 2 Sfj(Ln, GOCu,©,*, (Ln = Y or 
rare earth) ramily by the reaction of the component 
metal oxides or carbonates, in air or oxygen at tem- 
peratures below 1173 K is not possible because of the 
high stability of SrPb0 3 -related perovskite oxides. Pref- 
erential loss of the more volatile PbO leads to raiero- 
inhomogeneities. Furthermore, Pb in these compounds 
is in the 2+ state while part of the Gu is in the 1 + 
state. Synthesis has therefore to be carried out under 
mildly reducing conditions, typically in an atmosphere 
of N 2 containing "1% C> 2 . The most common method 
that has been employed for the synthesis of these lead 
cuprates is the matrix reaction method £116]. For 
Pb 2 Sr 2 (Ln, CaJCujO,*, (Ln = Y or rare earth), a 
mixed oxide containing all the metal ions except Pb is 
made by reacting SrCOj, Ln 2 O y or Y 2 0 3 , CaCOj and 
CuO in the appropriate ratios around 1223 K in air for 
16 h. The mixed oxide is then taken with an appropri- 
ate amount of PbO, ground thoroughly, peltetizied and 
heated iri the 1 133-1 198 K range in a flowing stream of 
nitrogen containing 1% 0 2 for periods between 1 and 
16 h. Generally, short reaction times and quenching the 
product from the sintering temperatures into liquid 
nitrogen in the same atmosphere gives better-duality 
samples. Evert though this is the common method for 
preparing Pb 2 Sr 2 (Ln, Ca)Cu 3 0 8t „ it is not always 
easy to obtain samples exhibiting good, reproducible 



9 



superconducting properties. The lead cuprates from Ihe 
method described above generally show broad tran- 
sitions in the R-T curves with negative temperature 
coefficients of resistance above T t . 

Studies of ihe dependence of T c on the calcium con- 
centration in the Pb 2 Sr J Y,. ;i Ca )[ CujO s + a system [1 17] 
have shown that heating the samples near the melting 
point between 1198 and 1228 K for 2 h and post- 
annealing in flowing nitrogen gas at a temperature 
between 673 and 773 K improves the superconducting 
properties of the samples dramatically. Direct one-step 
synthesis has been achieved [1 18] by reacting the metal 
oxides in sealed gold lubes around 1223 K. An alterna- 
tive route to the direct synthesis from metal oxides 
and/or carbonates has also been demonstrated [119]. 
Superconductivity near 70 K has been reported in 
Ca-frec Pb I SriLnCu 3 O g+4 (Ln = Y or rare earth) 
employing the vacuum annealing procedure [120]. Sub- 
stitution of Pb by K in Pb^YojCaa^CujO,*, has 
also been Carried out by the ceramic method [121]. 
About 30% of Pb can be substituted by Bi, and such a 
substitution increases the 7; up to 100 K. The n = 0 
member of the PbjSr^Ca , -,Ln J,Cu a ♦ ,0 6 + , series 
(namely PbjfSrLaJCujO*.,,) has been prepared 
successfully by this matrix reaction method [122]. 

UnHke the 221 3-type lead cuprates, superconducting 
1212-type lead cuprates of the formula 
(PTjo jQi^J&jCyfl.jCaejJCUjO,-, are synthesized in 
an oxidizing atmosphere. Several authors have reported 
direct synthesis as well as reactions under closed con- 
ditions [123-127]. In the direct synthesis of these cup- 
rates, care is taken to prevent the Joss of Pb by 
wrapping pellets in gold or platinum foil [127]. Rotat- 
ion et oi [125, 126] nave reported the synthesis of 1212 
lead cuprates by the direct reaction of the component 
oxides in evacuated stbca ampoules. This method has 



the advantage of adjusting the oxygen partial pressure 
required for the synthesis. Both 221 3-type and 1212- 
type lead cuprates have been prepared using the nitrates 
of the metal ions as the starting materials [128J. 
Although this procedure yields 2213 or 1212 phases in a 
single step, the product obtained always has imparities 
such as YjO, , CuO etc 

A superconducting lead cuprate of the formula (Pb, 
CuXEu, Ce),(Sr, Eu),Cu 2 0, (1222 phase) containing a 
fluoritc layer has been prepared by the direct reaction of 
ihe component metal oxides at 1273 K in oxygen atmo- 
sphere [129]. 

High-pressure ceramic synthesis has been employed 
to prepare lead cuprates of the 1212 type [130. 131]. In 
order to prepare PbojCuo.jSrjY^sOaojCniOT-,, 
sintering is carried out at 1213 K for 15 h under an 
oxygen pressure of 100 bar followed by East cooling to 
373 K_ The samples obtained from high-pressure 
oxygen treatment show bitter T t s than those processed 
at 1 bar ptesstire of oxygen Substitution of Y by other 
rare earths has been possible by Uus hjgh^xygen-pres- 
sure method [131]. Ail the rareorth substituted [ com- 
pounds -are superconducting with %s in the 50-70 K 
range, the 7; decreases with increase in the size of the 
rare earth. In table 5 we summarize the conditions for 
the synthesis of the various lead cuprates by tfcft ceramic 



2.7 

All the cuprates discussed till new are hole s 
ductors. Synthesis of electron-doped cuprate supercon- 
ductors of the type tit,-- J*,CuQ*^, ffca » Nd, Pr, 
Sin, Eu: M»Ge, ThX possessing die T* structure, is 
generally achieved by the ceramic method [132*134]. 
The conditions of synthesis are more stringent since the 



Table S, Conditions tor the synthesis ol lead cuprales by the ceramic method. 



Starting materials 



Temp. 00 Time Gas 



(Pb D5 Cu ai )SftaCoO, 



P*ei*wl)9r» 

(V as 0a M }Cu 3 0, 
f p W*o.»><Sr,.-,»E"o.») 
(Bi^CBajlCaaO. 



Cw,0, matrix 
PbO.PbOj.CoO,. 

SfO,.Y a O,.CwO 
f>bO.STCO s ,Y a O > - 

C*CO,.CuO 

PbO.UjO,. 

Sr a CuO,.CuO 
PbO. SfCO^. la^O,. 

CuO 

PbO. SfCOj.YjO,. 
CaCO„CoO 



1273 



PbO + SfjY^Ca^ 

Cui^p, matrix 
PbO.PbO^.SfjGuO,. 

YjOj.CaOa.CuaO.CuO 
PbO, . PbO. SaO, , 1106-1223 

SrpgO*.Y,O,.C«0.CuO 
PDO.SrCO^.EtijO,. ttM 

CeO a .CuO tats 



1106-1223 1-18 h 



Seeled qoM tabes 



1212 major phase* 
Sr s Pto^5uO„Imp 
1212 ma|ar phase + 

SfaPB/^fO,, Imp 



(116) 



[123] 
[124) 
ft27) 

(lag 

II2S3 



10 



P&#®k..H »xtra electron 

donated >by Cc* + Or ffi** does nV ,se the oxygen 
contest of the cupaatc. f 6r this reason, samples after 
cakanatiOB and sintering at 1323 K in air (for 24 h) are 
annealed in a reducing atmosphere (typically Ar, N, or 
dilute Hj) at 1173 K to achieve superconductivity. 
Samples prepared in this manner show a negative tem- 
perature coefficient of resistance above T t in the R-T 
curves; the resistivity drop at 7 e is also not sharp. An 
alternative synthetic route involves the reaction of 
pre- reacted NdCeO a , material with the required 
amounts of Nd 2 0 s and CuO at 1253 K for a minimum 
period of 48 h in flowing oxygen [135]. The samples are 
then rapidly quenched from 1253 K in an argon atmo- 
sphere to achieve superconductivity. This procedure 
eliminates the slow diffusion of Ge throughout the 
Nd,Cu0 4 -, host and gives uniform concentrations of 
cerium and oxygen. Samples obtained from this route 
show a sharp transition at 21 K. 

Superconductivity with a 7; of 25 K is induced by 
doping fluorine for oxygen in Nd 2 Cu0 4 . This has been 
accomplished by taking NdF, as one of the initial reac- 
tants [136]. Substitution of either <3a or In for copper 
in non-superconducting Nd 2 _/^Cu0 4 _, also induces 
superconductivity [137, 138]. 

2JL Infinite-layer cuprates 

Discovery of superconductivity in cuprates containing 
infinite CuOj layers has been of great importance in 
understanding the phenomenon. Very high pressures 
have been employed for obtaining the infinite-layer cup- 
rates. Both hole-doped (eg. Ca 1 _; x Sr,CuO I ) and 
electron-doped (Sr, .^Nd^CuOj) infinite-layer cuprate 
superconductors with a maximum 7; of 110 K have 
been reported [139-142]. Infinite-layered cuprates of 
the type (Ba, SrKTuOj, (Ca, Sr)CuO, are synthesized in 
an oxidizing atmosphere under high hydrostatic pres- 
sure [13?, 140, 142]. Electron-doped Sr 0 . 8S Nd 0J4 CuO 2 
is also prepared under high hydrostatic pressures [141]. 
Metal nitrates are generally used as the starting 
materials since carbonates of Ba, Sr and Ca have high 
decomposition temperatures. After decomposing the 
racial nitrates at around 873-1 123 K in air, the product 
is subjected to high pressure to obtain the supercon- 
ducting phases. Sr 0 ., 6 Nd 0 . M CuO 2 , which superconduc- 
at 40 K, is made under a hydrostatic pressure of 
25 kbar at 1273 K. Superconducting (Ca, SrJCuO, is 
Prepared at 1273 K under6GPa pressure. Deficteney of 
Sr and Ga as well as the oxidizing atmosphere make 
this phase superconducting, and the oxidizing atmo- 
sphere is provided by heating a capsule containing 
KC10 4 along with the sample. This cuprate has a T c 
{onset) of HO K. 

3 - CoprecipltaHon and precursor methods 

^Precipitation involves the separation of a solid con- 
ning various ionic species chemically bound to one 



wdl defined stoichiometry with respect to the metal 
ions is obtained only when the following conditions are 
satisfied. 

(i) The precipitating agent is a multivalent organic 
compound which can coordinate with more than one 
metal ion, and the precipitation rate is fast 

(ii) The solid precipitating out of the solution should 
be really insoluble in the mother liquor. 

The anions generally preferred for coprecipitation of 
oxidic materials are carbonates* oxalates, citrates etc. 
The same is true of high- T t cuprates. The precipitates in 
some instances could be genuine precursors or solid 
solutions [5, 6]. It is well known that precursor solid 
solutions drastically bring down diffusion distances for 
the cations and facilitate reactions in the soCd state. We 
shall not distinguish precursor solid solutions, precipi- 
tated from solutions from other precursors in this 
discussion. 

The precipitates (carbonate, oxalate etc) are heated 
at appropriate temperatures in a suitable atmosphere to 
obtain the desired cuprate. Some of the advantages of 
the coprecipitation technique over the ceramic method 
are an homogeneous distribution of components, a 
decrease in the reaction temperatures and of the dura- 
tion of annealing, a higher density and a lower partide 
size of the final product. The major drawback of ibis 
route is the control over the stoichiometry of the final 
product. 

3.1. La,_ x &r i Cn0 4 

la, Sr and Cii in L* 2 _^Cu0 4 are readily coprccipi- 
tated as carbonates [11, 12, 143]. For this purpose the 
required quantities of the various metal, nitrates are dis- 
solved together in distilled water; Alternatively, the cor- 
responding oxides are dissolved in nitric acid to give a 
nitrate solution and the pH of the solution is adjusted 
to 7-8 by the addition of KOH solution. A solution of 
K 2 COj of appropriate strength is then slowly added 
under stirring to give a light blue precipitate which is 
thoroughly washed. The precipitate is dried at 42& K 
and calcined at 1070 K for 8 h in air. The resulting 
Mack powder is ground and pelletjzed and sintered at 
1270 K for 16 h in air to obtain monophasic 
l^i.«sSro.i$Cu0 4 , superconducting at 35 K. 

Instead of as carbonate, the metal ions are also 
readily precipitated as oxalate by the addition of either 
oxalic acid or potassium oxalate to the solution of 
metal nitrates [11, 12, 144, 145]. The precipitated 
oxalate is then decomposed to obtain the cuprate. This 
method has certain disadvantages: 

(i) La 3 + in the presence of an alkali metal oxalate 
first yields lanthanum oxalate which further reacts with 
the precipitating agent to give a double salt. Control of 
stoichiometry therefore becomes difficult, leading to 
multiphasic products. 

11 



(ii) The relative solubilities of some of the oxalates 
also pose difficulties. For example, SrCj0 4 is nearly 
four times more soluble than SrCOj. 

3.2. YBa,Cu 3 0, 

YBa 2 Cu,0, and related 123 compounds can be 
obtained via coprecipitation of the component metals 
(from a nitrate solution) as a formate [146, 147], acetate 
[148], oxalate [12, 149-156], hyponitrite [157] or 
hydroxycarbonate [158, 159]. Some of these precipi- 
tates eould be genuine precursor compounds as is 
indeed the case with the hyponitrite. 

In oxalate coprecipitation [12, 149-152], oxalic acid 
solution of appropriate concentration is added to an 
aqueous solution of mixture of nitrates of Y, Ba and Cu 
and the pH of the solution is adjusted to 7.5 (by dilute 
NHj). The pale green slurry thus formed is digested for 
1 h, filtered and dried. The oxalate is converted to 
orthorhombic YBajCujO,-, by heating at 1053 K in 
air for 5 days followed by oxygenation at 723 K. This 
procedure, even though successful in making supercon- 
ducting YBa 3 Cu,0 7 -, in small particulate form, often 
results in undesirable stbichiometry because of the mod- 
erate solubility ©f barium oxalate. Furthermore, rare- 
earth ions in the presence of ammonium oxalate give a 
double salt with the excess oxalate which competes with 
the precipitation of copper and barium oxalates. These 
difficulties can be overcome either by taking a known 
excess (wt%) of barium and copper or by using tri- 
ethylammpnium oxalate as the precipitant in aqeuous 
ethahol medium [153-135]. The alcoholic medium 
decreases the solubility of barium oxalate and the pH of 
the solution is controlled in situ. 

A better method of homogeneous coprecipitation of 
oxalates is that of Liu el ai [1561 using urea and oxalic 
acid. Urea, on heating, is hydrolysed liberating C0 2 
and NH 3i and thus gradually adjusting the pH 
throughout the solution. The C0 2 liberated controls the 
bumping of the solution during digestion. The oxalate 
coprecipitation route is widely described in the liter- 
ature. The reactive powders obtained by the oxalate 
coprecipitation method decrease the sintering tem- 
perature. The formation of BaCO, in the intermediate 
calcinating step makes it difficult to obtain 
YBa^QijO, _ t in pure form. 

Complete avoidance of the formation of BaC0 3 
during the synthesis is possible using the hyponitrite 
precaisoF [157]. The hyponitrite precursor is obtained 
froim a nitrate solution of Y, Ba and Cu ions by the 
addition of an aqueous Na,M 2 O a solution. The precipi- 
tate is converted Into superconducting YBajCujO,-, 
by heating at around 973 K in an argon atmosphere, 
followed by oxygen annealing at 673 1C Although this 
route provides a convenient means of obtaining the 123 
cuprate at much lower temperatures than with other 
methods, there is a possibility of contamination of alkali 
metal ions during the course of the precipitatioa 

YBa 2 Cu 3 0 7 can also be prepared by the hydroxy- 
carbonate method [158, 159]. Here, KOH and K,C0 3 



are employed to precipitate copper as the hydroxide 
and Y and Ba as the carbonates in the pH range of 7-8. 
By employing NaOH and NajCOj, complete precipi- 
tation as hydroxycarbonate is attained at a pH of ~ 13. 
The product from the above two procedures is homo- 
geneous, showing sharp onset of superconductivity at 
92 K. The possibility of contamination by alkali metal 
ions cannot, however, be avoided. 



3 J. YBa»Cu 4 0, 

YBa 2 Cu 4 O e can be prepared by the oxalate route [160] 
wherein the solution of Y, Ba and Cu nitrates in water 
is added dropwise into oxalic acid-triethylamine solu- 
tion under stirring. Complete precipitation of Y, Ba and 
Cu with the desired sloichiometry of 1 :2:4 is achieved 
in the pH range of 9.3^113. The precipitated oxalates 
are filtered and dried in air at 393 K. the solid obtained 
is then heated in the form of pellets at 1078 K in 
flowing oxygen for 2-4 days. The product after quen- 
ching in air shows the 124 phase as the major product 
with a T t of 79 K. 

An alternative coprecipitation route for the synthesis 
of YBa z Cu 4 6 3 is the method of Chen et a\ [161] i» 
which the aqueous nitrate solution of the constituent 
metal ions is mixed with 8-hydroxyqwnplirie4ri- 
ethylamine solution. The precipitated oxine is filtered, 
washed, dried and sintered at 1088 K in oxygen for 3 
days to yield phase-pure YBa,Cu 4 Q 8 showing a T t of 
80 K. Ethylenediaminetetraaceticacid [161] as well as 
carbonate routes [162] have also been employed for the 
preparation of YBa 2 Cu 4 0 8 . Coprecipitation using tri- 
ethylammonium oxalate has been exploited for substi- 
tuting Sr in place of Ba in YBa 2 Cn 4 O s [163]. 



3.4. Bismuth cuprates 

Very few coprecipitation studies have be$n carried out 
on the preparation of bismuth cuprates. One reason 
may be that despite the good sample homogeneity gen- 
erally obtained through solution metfcods, the chemistry 
of bismuth cuprates is rather complex; It is not that 
easy to firal compounds of aB the constituent metal tons 
soluble in a common solvent; controlling the stoiehiom- 
etry in these cuprates is also difficult in the coprecipita- 
tion procedure. Furthermore, bismuth nitrate, which is 
often used as one of Use starting materiafe, decomposes 
in cold water to a bask nitrate precipitate as given by 
Bi(N0 3 )j(s)-*Bi** +3NOj" 

Bi 3 * + 3N03" + 2H 2 0 Bi(OH) 2 NG 3 (s) + 2H + . 
This problem can be overcome to some extent by pre- 
paring the nitrate solution of bismuth in nitric acid or 
by starting with bismuth acetate instead of the nitrate. 

Bidentate Uganda such as the oxalate are found to 
react more rapidly than multidentate ligands such as 
citric acid [164-174] in the coprecipitation process. 
Complexes of oxalic acid are also more stable than 




the sto&iameuy because of the rdafc^,solubiIity of 
BiC,0 4 orSrC,0 4 . 



A straightforward oxalate coprecipitation is 
achieved by dissolving the acetates of Bi, Ca, Sr and Cu 
m facial acetic acid and then adding excess oxalk acid 
to the solution [164]. The oxalate precipitate is dried 
and decomposed at around 1073 K in air and processed 
in the 1 103-11 23 K range Tor periods ranging from 24 h 
to 4 days, depending on the starting composition. The 
n = 2 (2122) member obtained by this procedure shows 
zero resistance at 83 H. In another procedure reported 
by Zhang et al [165], first the Sr/Ga/Cu nitrate solu- 
tions are mixed in the required molar ratio. Into this 
solution is poured a solution of bismuth nitrate pre- 
pared in nitric acid along with oxalic acid. The com- 
plete precipitation occurs at a pH of around 5 (attained 
by the addition of aqueous NaOH). This process 
involves the possibility of contamination of sodium 
ions; this has been circumvented by using N(CHj)«OH 
to adjust the pH of the solution [166] and complete 
precipitation of the oxalates occurs at a pH of 12. All 
these procedures, however, produce mixed-phase 
samples. 

For the preparation of the monophasic lead-doped 
n-3 member (2223), oxalate coprecipitation has been 
found effective [167-174], In the procedure reported by 
Chiang et al [171], the molar ratio of the chelating 
agent (oxalic add) and the nitrate anions (from the 
metal nitrate solutions) is fixed at 0.5 and the pH, 
adjusted by NH 4 OH solution, at which complete pre- 
cipitation occurs is 6.7. The product from the method, 
Bi t ■»**<> sSfjCajCujO,, after sintering at 1 1 33 K in air 
lor 72 h, shows a T t of 1 10 K. 

Coprecipitation as oxalates to prepare the lead- 
doped n = 3 member (2223) has been achieved from an 
ethylene glycol medium using triethylammonium 
oxalate and oxalic acid [172]. A more easily controlled 
and reproducible oxalate coprecipitation procedure 
appears to be that of Sbd et al [173] where in a mixture 
of trfethylamine and oxalic acid is employed. The 
advantage of using triethylamine is that it has a higher 
basicity and a lower compkxing ability towards Cuffl) 
than has ammonia. Control of the stokhioroetry of 
the final product is therefore belter obtained with this 
procedure; precipitation occurs in the pH range 1-5-2.2. 
The coprecjpitaied oxalates sintered at 1 133 K in air for 
a minimum period of 72 h give monophasic 
Ki^PtVwSrtCajCujQm with a T t of 1 10 It. It is pos- 
sible to avoid adjusting the pH in the coprecipitation of 
oxalates [174]. The procedure involves coprecipitating 
the oxalates from dilute acetate solutions instead of 
from nitrate solutions. The oxalates are then converted 
to nearly phase-pure Bi 14 Pb 6 . 4 Sr 1 Ca J Cujo l0 {T t of 
106 K) by sintering at 1 123 K m air for 160 h. 

Carbonate corprecipitation has also been carried 
out for the synthesis of superconducting bismuth cup- 
rates [175, 176], but the meihod does not yield mono- 
phasic products. 




U>prccrpttatH>n of tt fm^m coptajes tram 
aqueous solutions as' oxWcs is Imjdejried by (he solu- 
bility of thallium oxalate. However, Bernhard and 
Gritzner [177] have found that complete coprecipita- 
tion as oxalates can be achieved by starting with thal- 
lium acetate in glacial acetic add medium. Ia the 
procedure reported for the preparation of the n = 3 
member (2223X rtokiuometric amounts of thallium 
acetate, CaCOj, BaCOj and copper acetate are dis- 
solved in water containing glacial acetic add. The solu- 
tion containing aB the cations » then added to a 
solution of oxalic add (excess) under stirring. The pre- 
cipitate, after digestion for I h, is filtered, washed and 
dried. The oxalates are heated in the form of pellets 
(wrapped in gold foil) at around 1 173 K for 6 min m an 
oxygen atmosphere. The product after annealing in the 
same atmosphere shows 2223 as the major phase with a 
T c of 118K- 



3& Lead cuprites 

Carbonate coptecrpitation is found to be satisfactory 
for the synthesis of representative members of super- 
conducting lead cuprates [128] of 2213 and 1212 
types, namely PbjSrjY^jCaojCUjO,*, and 
Pb<i(.sSro.» s 'a Y e.sC»«.s Cu iC>7-»- Gopredpitarioa as 
carbonates has been achieved by adding the nitrate 
solution of the constituent metal ions to an aqueous 
solution of sodium carbonate (in excess) under constant 
stirring. The carbonate precipitate thus obtained is 
washed and dried. The decomposed powder is heated in 
the form of pellets around 1153 K. in a suitable atmo- 
sphere. Pb I Sr J Ca 0 .jY os Cn,0 8+ , obtained by this 
method after heating for 4 h in nitrogen cowaiumg 1% 
O t showed 2213 as the major phase (T e ~ 74 K) with 
impurities such as Y a O*. CuO- The 1212 phase 
obtained after heating in oxygen at 1 153 K for 12 h 
showed a broad transition wfth a T. (onset) ot 1G0 K. 
This method has the advantage of single heating rather 
than the maltistep procedures required to the other 
methods. 



4. So»~oe* process • 

The sol-gel process is employed in order to get homo- 
geneous mixing of cations on an atomic scale so that 
the sofid state reaction occurs to completion ia a short 
time and at the lowest possible temperature, the term 
sol often refers to a suspension or dispersion of discrete 
colloidal particles, while a gd represents a cofloidal or 
polymeric sofid containing a fluid component wnkfc has 
the internal network structure wherein both the solid 
and the fluid components are highly dispersed. In the 
sol-gel process a concentrated sol of the reactant oxides 
or hydroxides is converted to a semi-rigid gd by remo- 
ving the solvent The dry gel is heated at an appropriate 




c N h Rao era/ 

temperature to obtain the product Most of the reac- 
tions in the soj-gd process occur via hydrolysis and 
polycondensation. 

Two different routes for the sol-gel process are 
usually described in the literature for the synthesis of 
high- T e cuprate superconductors: 

(i) Via molecular precursors (eg. metal alk oxides) in 
organic medium; 

(ii) Via ionic precursors in aqueous medium (citrate 
gel process). 

The purity, microstructure and physical properties 
of the product are controlled by varying the precursor, 
solvent, pH, firing temperatures and atmosphere of heat 
treatment. 

4.1. 214 Cuprates 

Superconducting 214 compounds are prepared both 
by means of organometaUic precursor [178] and by the 
citrate gel process [I!]. Lanthanum 2,4-pentane 
dionatc, barium 2,4-pentane dionate and copper (II) 
ethyl bexanoate are mixed at room temperature in the 
appropriate ratios in methoxyethanol medrmn to obtain 
the organometallk precursor. After vigorous stirring at 
room temperature, the precursor get is converted to 
monophase La 1 . s ,Bg 0 .,CuO» (T t 23 K) by firing at 
573 K in oxygen. 

In the citrate gel process, a mixture of citric acid and 
ethylene glycol is added to the solution containing the 
required quantities of metal nitrates. The resulting solu- 
tion is vigorously stirred and heated around 393 K. 
During this process, oxides of nitrogen evolve, resulting 
in a viscous geL The gel is decomposed at 673 K in air 
and the resulting black powder fa then given the neces- 
sary heat treatment to obtain the superconducting 
oxide. 

4X YBa,CB,0 7 

In the case of YBa 2 Oi a O T the alkoxide precursors 
are both very expensive arai difficult to obtain. In addi- 
tion, the solubaity of copper alkoxides is very low in 
organic solvents and yttrium aftoxides are readily 
bydrorysed even by a trace of water. Despite these diffi- 
culties, superconducting YBa 3 Cuj0 7 _j has been pre- 
pared using alkoxides [157, 179-181 J A simple reaction 
involving Y(OGHMej),, B^OCHMc,), and CufNBu,) 
in THF in an argon atmosphere gives the 
organometalhc precursor £157]. The p rec urso r powder, 
after removal of the solvent, is sintered at 973 K in 
flowing argon to obtain tetragonal YBa,Ctt»0 T _, . Fol- 
lowing oxygenation at 673 K, the product shows a % of 
83 K. Superconducting properties have been improved 
by using w-butoxides of Y, Ba and Cu in butanol 
solvent £179]. 

Alternatively, methoxyetboxides of yttrium, barium 
and copper have been used as precursors in 
mtfhoxyetlianol-iiie^^ solvent 
mixture to prepare YBajQijO,., £18©]. In some of the 
preparations, CutNO^ (soluble in ethanol) or copper 




acetylacetonate (soluble in toluene) is used along with 
the alkoxides of yttrium and barium to overcome the 
problem of low solubility of copper alkoxides [182, 
183]. Organometalhc precursors involving propionates 
[153] and neodeconates [184] have also been used for 
preparing YBajOijO, _ » . 

Modified sol-gel methods which do not involve the 
metal alkoxide precursors have been employed by many 
workers. Thus, Nagano and Green Walt [185] have 
employed metal nitrates dissolved in ethylene glycoL 
After reflu xing around 353 K under vigorous stirring, a 
bluish green colloidal gel is obtained. The gel is con- 
verted into orthorhombk YBajCujO,., by heating to 
1223 K in Bowing oxygen. Precipitatmg all the three 
ions as hydroxides also results ia fine colloidal particles 
ofthe starting materials £186-188]. The precipitation is 
generally carried out by the addition of NH 4 OH £186], 
N(CH,).OH [187] or BafPHfe [188] to a solution of 
metal nitrates (pH range 7-8). These hydroxides arc 
decomposed around 1223 K in oxygen to give 
YBajCujO? showing a T 9 of 93 K. 

YBaiCu 3 0 T _, has been prepared by the citrate gel 
process £189-193]. In this method 1 g equivalent of 
citric acid is added to each gram equivalent of the 
metal The pH of the solution is adjusted to around 6 
(either by NH 4 OH or by cthytenediarains). Evaporation 
of the solvent (water) around 353 K, results in a viscous 
dark blue gel. The gd is decomposed and the powder 
sintered in the form of pcflets at 1 173 K in oxygen to 
obtain orthorhombic YBa a Cu s O,_, (T t = 93 K> By 
this method, ultrafioe homogeneous powders (particle 
size ~0.3 fan) sat obtained. The crucial step in this 
process is the adjustment of the pH which controls the 
stoichioroetry of the final product This timitarioa has 
been overcome by dispersing the citrate metal ion com- 
plexes in a solvent mixture of ethylene g&col and water 
£194.195]. 

Problems such as the formation of BaCO, during 
the calcination step, nitration and contammation of 
alkali metal ions in the final product are avoided in the 
sol-gel process. Ftn-thetmore, perfect bonrogeoeity is 
obtained before calcination, the sol-gel process (eg. 
citrate process) has the advantage over the other 
methods in that the gel can be used for making thick 
and thin superconducting films, fibres etc which have 
technological importance [179, 185. 186, 196-198]. 

43. YBajCojO, 

The sol-gel method oflers a good alternative to the 
ceramic method for the synthesis, of superconducting 
YBa 2 Cu 4 O a . The fbttawog- procedure has been used 
to prepare YBa 2 CtuO, at 1 atm oxygen pressure 
£199]. Appropriate quantities of Y^ -OC^H,^, 
Ba(j - OC 4 H^, and Cu(s - OBu), in butanol-xylenc 
mixture are remixed in an argon atmosphere at 343 K 
for a period of 30 h. The fine powder after the vigorous 
reaction is freed from the solvent and dried. The powder 
is heated in the form of pellets at 1033 K in flowing 
oxygen to obtain superconducting YBajCu^O,, 



ased as the source of copper in this pr<jt 

In the modified citrate gel procw prepare 
VBa 2 Cu»0» [201, 202], 1 g equivalent of citric acid is 
added for each gram equivalent of the metal and the pH 
of the solution is adjusted to ~5.5 by the addition of 
ethytenediamine. The resulting clear solution is evapo- 
rated to yield a viscous purple gel. The decomposed gel 
is sintered in Bowing oxygen for 3-5 days at 1088 K to 
obtain nearly monophase YBa,Cu*0 8 (T £ ==66K). 
Kakibana et al [203] have reported the preparation of 
YBa 2 Cu*O a using a precursor obtained from citrate 
metal ion complexes uniformly dispersed in a solvent 
mixture or ethylene glycol and water. This method 
yields phase-pure YBajCu 4 O a (T t ~ 79 K) and elimi- 
nates the need to adjust the pH. 

4.4. Bismntfc cuprates 

There have been very few reports of the preparation of 
bismuth-based cuprate superconductors by the alkoxy 
sol-gel method [2041 Some of the difficulties arise 
because the relevant bismuth/lead alkoxides are not 
readily available; it is abo not easy to get a common 
organic solvent to dissolve the various metal alkoxides 
simultaneously. Dhalk et al [204] have, however, 
attempted to synthesize the lead-doped n = 3 member 
(2223) using organometallic precursors involving propi- 
onates. The starting materials were taken in the form of 
nitrates and converted into propionates by the addition 
of an excess of 100% propyl alcohol. This step was fol- 
lowed by the addition of ammonium hydroxide and eth- 
ylene glycol to increase the alkoxy anion concentration, 
thus in turn increasing the viscosity of the solution. All 
the solutions were mixed together and dried at 353 K. 
The resin after calcination at 1123 K in air and sinter- 
ing at 1118 K gave a mixture of the n « 3 and n = 2 
members. . . 

A simple sol-gel method involving the addition .of 
dilute ammonia to an aqueous solution containing 
nitrates of Bi, Sr and acetates of Ca, Cu and Pb (until 
the pH of the solution reached around 5.5) has also 
been employed to prepare bismuth cuprates [205, 206} 
The Hue solution after concentrating at around 343 K 
gives a viscous gel. The gel « decomposed and the 
powder sintered at around 1128 K in air. The product 
from this procedure is multiphasic showing a T, of 
104 K. The simplicity of the method and the formation 
of the n = 3 phase in a short time makes it somewhat 
superior to the conventional ceramic route. The modi- 
fied citrate gel process has been employed to prepare 
the a « 2 member (2212) in pure form with a T c of 78 K 
[193]. 

4.5. Lead cuprates 

The modified citrate gel process has been successfully 
employed by Mahesh et al [207] for the synthesis of 
lead cuprates of the 2213 or 1212 type. In a typical pro- 
cedure, a mixture of citric acid and ethylene glycol in 



m K ^r - - « 

The gel after decomposrW «ated in the form of 
pellets in the temperature range of 1073-1173 K either 
in Nj containing 1% 0 2 or in an oxygen atmosphere. 
Pb i Sr 2 Y 0J Ca < ,3Cu 3 O 8+ , obtained from this process 
shows a sharp superconducting transition at 70 K. The 
1212 cuprate also shows a sharp transition at 60 K. 
This process is superior to the ceramic procedure for 
synthesizing superconducting lead cuprates. 

5. Alkali flux method 

Strong alkaline media, either in the form of solid car- 
bonate fluxes, molten hydroxides or highly concentrated 
alkali solutions can be employed for the synthesis of 
high-7; cuprate superconductors. The alkali flux 
method takes advantage of both the moderate tem- 
peratures of the molten media (453-673 X) as well as of 
the acid-base characteristics of molten hydroxides to 
simultaneously precipitate oxides or oxide precursors 
such as hydroxides or peroxides of the constituent 
metals. The method stabilizes higher oxidation states of 
the metal by providing an oxidizing atmosphere. 

Employing fused alkali hydroxides, Ham et al [208] 
have synthesized superconducting La 2 _,M Jr Cu0 4 
(M = K or Na or vacancy) at relatively low tem- 
peratures (470-570 K). In this method, stoiehioinetric 
quantities of UjO, and CuO are added to a molten 
mixture containing KOH and NaOH fm an approx- 
imately 1 : 1 ratio) in a Teflon crucible and heated at 
around 570 K in air for 100 h. The 1:1 mixture of 
KOH and NaOH melts at 440 K and ance the attah 
hydroxides generally contain some water, the melt is 
acidic and can readily dissolve oxides such as La,©, 
and CuO. The black crystals obtained from the reaction 
(after washing away the excess hydroxide wrth water) 
show a T t of 35 K. Sine* the reaction is carrwd out in 
alkali hydroxides, incorporation of Na* or K ions for 
La'* in the lattice of La 2 CuO* cannot be ruled outlt 
should be noted that supercttfidUCting alkali-doped 
La 2 Cu0 4 is normally prepared at higher tewpetaturcs 
in sealed gold tubes [209]. Recently, alkaline hypo- 
bromite oxidation has been employed to ebtam 
La 2 Cu0 4+ , with a T, Of 44 K [210]. 

Superconducting YBa^O, (% ~ 88 K) has alSp 
been prepared using the fused eutectic of sodi&m and 
potassium hydroxides in a similar manner to that 
described above [211]. The problem of contammahon 
of alkali metals in the preparation <* YjtejCUiO, has 
been overcome by using the BafpH), flux pil} The 
procedure involves heating a mixture^ntaming stoi- 
chiometric amounts of Y(N0 3 ),.6H J 0, Ba(OH) 2 and 
CrfNOJ: - 3H,0 in an open ceramic crucible at around 
1023 K in air for a short time (about 10 min) and then 
slowly coohng the melt to room temperature. Since 
BafOH), has two hydration states, one melting at 
351 K and the other at 681 K, the lower-melting 
hydrate acts as the solvent for the nitrates of copper 




CNR Rao et al 

and yttrium while the high-melung hydrate serves as the 
medium for intimate mixing of the reacts Ms. The pre- 
cipitate obtained from the melt, after washing with 
water, is sintered m air at around 1 173 K followed by 
oxygenation at 773 K. This method yields an orthor- 
hombic YBa 2 Cu,0 7 phase (with little CuO impurity) 
showing a T t of 92 K. 

The flux method eliminates the need for mechanical 
grinding and introduction of carbon-containing anions, 
which is often encountered in the solution routes. Fur- 
thermore, the method is efficient and cost-effective. 

6. Combustion method 

Although many of the solution routes discussed earlier 
yield homogeneous products, the processes involved are 
quite complex. Combustion synthesis or setf- 
propa gating high-temperature synthesis (shs), first 
developed by Merxhanov and Borovinskaya [2123, pro- 
vides a simple and rapid means of preparing inorganic 
materials, many of which are technologically important. 
Combustion synthesis is based on the principle that the 
heat energy liberated by many exothermic non-catalytic 
solid-solid or solid-gas reactions can self-propagate 
throughout the sample at a certain rate. This process 
can therefore occur in a narrow zone which separates 
the starting substances and reaction products. 

Self-propagating combustion has been employed 
recently in this laboratory to synthesize members of 
almost all families of cuprate superconductors (except 
for the thalbum cupratcs) [213}. The method involves 
the addition of an appropriate fuel to a solution con- 
taining the metal nitrates in the proper stoichiometry. 
The ratio of the metal nitrates to the fuel is such that 
when the solution is dried at around 423 K, the solid 
residue undergoes flash combustion, giving an ash con- 
taining the mixture of oxides in the form of very fine 
particles (particle size 03-0.5 jim). The ash b then given 
proper beat treatment under the desired atmosphere to 
obtain the cuprate. the small particle size of the ash 
facilitates the reaction between the metal oxides due to 
smaller diffusion distances between the cations. Fuels 
such as urea [213, 214}, glycine [213, 215] sod tetra- 
formal triazine (TFTA) [2163 are generally employed 
for synthesizing cuprate superconductors. Ultrafine par- 
ticles of copper metal can also act as an internal rod 
wherein the combustion is initiated by Sashing a laser 
beam for a short time [2173- Some of the cuprate super- 
conductors which have been p tc paie d £2.13} by this 
route include La a _JStJOaQt (T. = 35 K% YBa,Cu,0 7 
(T c = 90 K), YBajfXO, i% = » KX MiCiSriCUjO, 
(T e = 85K), Pb,Sr 1 Y 0 ,Ca.^Co 3 O i (T e = 60K) and 
Nd 3 _,Ce,Cu0 4 (T« ~ 30 K)i 

7. Other methods 

In addition to the various synthetic methods discussed 
hitherto, a few other methods such as spray drying 
[218-2213, freeze drying [186. 222, 2233, use of metallic 
precursors [224. 225] and electrochemical methods 




[226, 227] have also been employed for the preparation 
of cuprate superconductors in bulk form. In spray 
drying, a solution containing the metallic constituents, 
usually in the form of nitrates, is sprayed in the form 
of fine droplets into a hot chamber. The solvent 
evaporates instantaneously, leaving behind an 
intimate mixture of the reactants which on heating at 
the desired temperature in a suitable atmosphere yields 
the cuprate. Some of the superconducting cupratcs pre- 
pared by this method include YBa,Cuj0 7 (T c = 91 K) 
[218]. YBa,Cu 4 O g (T t = 81K) [219] and 
Bi 1 . 6 Pb 0 . 4 Sr 2 Ca J Cu,O 10 (T t = 101 K) [220, 221]. In 
freeze drying, the reactants (in a common solvent) are 
frozen by immersing in liquid nitrogen. The solvent is 
removed at low pressures to obtain the initial reactants 
in fine powder form, and these are then processed at an 
appropriate temperature, For example. YBa 2 Q»jO T 
(i; - 87 K) [1863. Yfia,OuO» (T, = 79 K) [222] and 
Bii.«Pbo^Sri.«Ca z Co,0 F (r t = 101 K) C223] have been 
prepared by this method. 

Metallic precursors have been used in the prep- 
aration of 123 and 247 cupratcs [224. 2253- For 
example, oxidizing an Er-Ba-Cu alloy around 1170 K 
gives superconducting ErBa,Co.jO ? with a T, of 87 K 
[2241. Similarly YbjBa^Cu.O,, has been obtained by 
heating an afloy composition of Yb8a 2 Cuj (with 33 
wt% of silver) under 1 arm oxygen at 1173 K [225}. 

Making use of electrochemical oxidation, 
La,CuO <+ , with a 7; of 44 K has bee* prepared at 
room temperature, which is other w ise possible only by 
use of high oxygen pressures [226, 227]. 



8. Oxygen rtoo-stotchlometry 

Oxygen stoichiometry plays a crucial role in determin- 
ing the superconducting properties of many of the cup- 
rates. Thus, stoichiometric La,CuO A is an insulator, 
while an oxygen-excess material prepared under high 
pxygen pressures shows superconductivity with a T t of 
35 K [153. The same holds lor the next member of the 
homologous fam3y, La^.jSrjCaCajOf, which is super- 
conducting only when there is an oxygen excess {173- 
Tbe excess oxygen donates holes in these two systems. 
In the case of YBa»Cu 3 0 7 _^ oxygen can be easily 
removed giving rise to tetragonal m»-supcrcond«ttng 
YBajCu,O s , The YBa,Cu,0 6 material can be pre- 
pared by heating YBa 2 Cu 3 O t in as argon atmosphere 
at 973 K for extended periods of time [2283. The varia- 
tion of T 9 with oxygen stofehi oat c t ry, 3, is well known 
[229, 2303. When i reaches 03, there is an intergrowth 
of YBa 2 Co 3 0« and YBa 2 Cu,0 7 and at this composi- 
tion, the material shows a T t of 45 K. The * « 03 corn- 
posiDon is c*tained by quenching £s*0 material, 
heated in a nitrogen atmosphere at 743 K [23 1], Simi- 
larly, by quenching YBajCujO, at 783 K in air, 
YBajCuaOi.7 Showing a T t of ~60 K.) is prepared 
[2313. The 7; of 90 K is found only when & <0J. 
YBa 2 Cu 3 0 6 is readily oxidized back to YBa 3 CUj0 7 . It 
may be noted that this oxidation-reduction process in 



Laj.jSr.fBaJCuO,, 
U a Ca 1 _,Sr,eu 2 O e 

YBa a Cu„0 8 * 
BljCaSfiCujO, 

TljBajCuO,, * 

TljCaSajCiijO, 

TljCajBajCo,©^ 

Pb a Sf 1 Ca,_,Y,Cu^) 8 



Pt>wGu 0 .«Sr 1 Y 0w ,Ca o . 8 C« J O, 
Nd,_,Ce.CuO« 



Ca,_.Sr,CuO, 



35 


Ceramic*, sol-gel. combustion, coprecipitatlon 


60 


Ceramic (high 6, pressure)* 


40 


Ceramic (high O, pressure)* alkali-flux, hypobromtte* 


90 


Ceramic (annealing in OJ*. sct-eef*. copredpttaBon*. 


80 


combustion 

Ceramic (high O a pressure), ceramic (with MaaO,)* 




eol-gel*. copreclpHatton* 


90 


Ceramic (air-quench)* sot-gel*, combustion, 


110 


melt (glass) route* 
Ceramic*, aoi-get. met route 


90 


Ceramic (sealed Ag/Au tube)* 


115 


Ceramic (sealed Ag/Au tuba)* 


90 


Ceramic (sealed Ag/Au tube)* 


110 


Ceramic (seated Ag/Au tube)* 


125 


Ceramic (seated Ag/Au tube)* 


90 


Ceramic (sealed Ag/Au tube)* 


70 


Ceramic (low O, partial pressure).* 




sot-gel* (tow Oj partial 




pressure) 


45 


Ceramic (Bowing G,)* 


30 


Ceramic (low O, partial pressure)* 




Coprecipitation (tow O, partial pressure)* 


4O-110 


Ceramic (hioh pressures)* 


40-110 


Ceramic (high pressures)* 



* Other rare-earth compounds erf Ws type are 
ortwmomWc^tetr 
c Sr analogues or 



prepared by similar methods. Oxygen annealing is done below Bte 
sobsttutofts at Ca *wl Tl sites are prepared by a similar procedure. 



YBa ? Cu 3 0 7 _* is of topochemkal character. The other 
analogous rare-earth 123 cupratcs ajso behave in a 
siraflar way with respect to the variation of S with % 

urn- 

Wh§e YBa 2 Cu*0 8 has high oxygen stability. 
YjBauCthOjs-, shows a wide range of oxygen stokhi- 
omerry (0<£< 1) [233]. The maximum T, of 90 1C is 
achieved when i is close to zero, and when & reaches 
unity the material shows a T e of 30 K ; there is no struc- 
tural phase transition accompanying the variation in 
oxygen stoiehiometry. Usually, both yttrium 124 and 
247 cupratcs and their rare-earth analogues, prepared 
by the ceramic method under 1 aim oxygen pressure, 
show £ close to zero. 

Bismuth cupratcs of the type BMCa, Sri,., 
Cu,O k *«»» we best prepared by quenching the 
samples in air or by annealing in a nitrogen atmosphere 
at appropriate tmperatures £53, 234]. Heating the 
samples in an oxygen atmosphere is no good, possibly 
because the extra oxygen may add on to the Bk-O 
layers. In the case of the lead-doped « = 3 member 
(2223X preparing the samples under low partial pres- 
sures of oxygen is found to increase the volume traction 
of the superconducting phase [235, 2363- The n = I 
member, Bi J Sr 3 Cu0 6+ » shows metallic behaviour when 
there b excess oxygen [237], By anneafing in a reducing 
atmosphere {Ax or N,), the excess oxygen can be 
removed to induce superconductivity. 

Oxygen stoiehiometry has a dramatic influence on 
the superconducting properties of thallium cupratcs [94. 
108, 109. 238-2461 For example. tbaHimn cupratcs of 
tne TiCa,. l BajCu 1 ,0 J . < ., family, derivatives of the 



TlCa.. l Sr 2 Cu,0 Ij , + j fcm'dy and TltBajCttO* often 
have excess oxygen when prepared in sealed tubes. By 
annealing these samples in a reducing atmosphere <Ar, 
dilute H 2 , Nj or vacuum} at appropriate t e m pera tu r e s, 
the excess oxygen is removed to induce superconduc- 
tivity in some cases [108, 109, 2351 Anowling at low 
oxygen partial pressures or to a reducing atmcspftere 
a lso increases the T e of some of the s^ewspndttc&g 
thallium cuprates to higher values by decreasing the 
Oxygen content [94, 239-246]. These variations are 
cleady related to the bole coaoiatratjon where the 
number of holes decreases by removing excess oxygen, 
thereby giving the optimal concentration required for 
maximal T c [247]. 

In lead cuprates of the M>,Sr 1 {LB,Ca)Cuj0 84 , 
(2213) type, mcreasing the oxygen content of the 
material by annealing in an oxygen atroosplttre oxidizes 
the Pb J * and Cu 1 * without affecting the CuO, steels, 
which governs the supercowructivity in this materia}; 
[248]. Though this system shows a wide range of 
oxygen stoiehiometry (associated with a strocterai 
phase irartsstioo from orthornooibk to tetragonal 
symmetry), maximum T< is observed lor any gwen com- 
position where in S is dose to zero [249]. Samples with 
6 = 0 are therefore prepared by annealing in a nitrogen 
atmosphere containing bilk oxygen. The lead 1212 cup- 
rales, on the other hand, art best prepared in a Sowing 
oxygen atmosphere. The samples obtained after the 
oxygen treatment are often rtot superconducting since 
there is an oxygen excess. The samples are quenched in 
air at around 1073 K in order to achieve superconduc- 
tivity [250]. 



17 



CNR Rao ef al 



Superconducting properties of the electron-doped 
superconductors, Ndj.^Ce^CuO..,. arc sensitive to 
the oxygen content. The as-prepared samples which are 
semiconducting have oxygen content greater than four. 
Samples with oxygen content less than four are 
obtained by annealing in a reducing atmosphere fN,. 
Ar or dilute H 2 ) at around 1173 K. Maintaining the 
oxygen stoichiometry al less than four is essential for 
having an oxidation stale of Cu less than 2+ in this 
material p-SI]. 

9. ConctudJng remarks 

In the earlier sections we presented details of the pre- 
parative methods for the synthesis of various families of 
cuprate superconductors. In addition, we also examined 
the advantages and disadvantages of the different 
methods. Since more than one method of synthesis has 
been employed for preparing any given cuprate, it 
becomes necessary to make the right choice of method 
jo any given situation. In order to assist in making such 
a choice, we have tabulated in tabk 6 the important 
preparative methods employed to synthesize some of 
the representative cuprates, where the recommended 
methods are also indicated. 



The authors thank the various agencies, expedally the 
National Superconductivity Research Board, University 
Grants Commission and the US National Science 
Foundation for support of the research related to 
cuprate superconductors. 



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21 



BRIEF ATTACHMENT AC 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 14, 2005 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 

P.O. Box 1450 

Alexandria, VA 22313-1450 



In response to the Office Action dated July 28, 2004, please consider the 



The attachments referred to herein A to Z and AA are in the FIRST 
SUPPLEMENTAL AMENDMENT. The Attachments AB to AG are attached herein. 

Please charge any fee necessary to enter this paper and any previous paper to 
deposit account 09-0468. 



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Sir 



following: 




Dr. Daniel P. MorrisTtsq. 
Reg. No. 32,053 
(914) 945-3217 



IBM CORPORATION 
Intellectual Property Law Dept. 
P.O. Box 218 

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ATTACHMENT AC 



HIGH TEMPERATURE SUPERCONDUCTORS 
C. N. R. Rao and A. K. Raychaudhuri 



The following tables give properties of a number of high temperature superconductors. Table 1 lists the crystal structure (space group and lattice 
constants) and the critical transition temperature T c for the more important high temperature superconductors so far studied. Table 2 gives energy gap, 
critical current density, and penetration depth in the superconducting state. Table 3 gives electrical and thermal properties of some of these materials 
in the normal state. The tables were prepared in November 1992 and updated in November 1994. 

REFERENCES 

1. Ginsburg, D.M., Ed., Physical Properties of High-Temperature Superconductors, Vols. I — III, World Scientific, Singapore, 1989—1992. 

2. Rao, C.N.R., Ed., Chemistry of High-Temperature Superconductors, World Scientific, Singapore, 1991. 

3. Shackelford, J.F., The CRC Materials Science and Engineering Handbook, CRC Press, Boca Raton, 1 992, 98—99 and 122—123. 

4. KMs,E.,Ed.,MaIeriabandCrystaUographicAspectsofHT c -Supercondw^ 

5. Malik, S.K. and Shah, S.S., Ed., Physical and Material Properties of High Temperature Superconductors, Nova Science Publ., Commack, 
N.Y., 1994. 

6. Chmaissem, O. et al., Physica, C230, 23 1—238, 1994. 

7. Antipov, E.V. et al., Physica, C2I5, 1— 10, 1993. 

Table 1 

Structural Parameters and Approximate T c Values of High-Temperature Superconductors 



Material 


Structure 


TJK (maximu 


La 2 Cu0 4 ^ 


Bmab; a = 5.355, b = 5.401, c= 13.15 A 


39 


La 2 jSr^BajvCuO* 


I4/mmm; a - 3.779, c = 13.23 A 


35 


La 2 Ca,. x Sr,Cu 2 0 6 


I4/mmm; a = 3.825, c = 19.42 A 


60 


YBa 2 Cu,0 7 


Pmmm; a = 3.821 , b = 3.885, c = 1 1 .676 A 


93 


YBa 2 Cu,0 8 


Ammm; a = 3.84, b = 3.87, c = 27.24 A 


80 


YzBa^uAj 


Aramm; a = 3.851, b = 3.869, c = 50.29 A 


93 




Amaa; a = 5.362, b = 5.374, c = 24.622 A 


10 


Bi 2 CaSr 2 Cu 2 0, 


A 2 aa; a = 5.409, b = 5.420, c = 30.93 A 


92 


BijCajSr^UjOio 


A^; a = 5.39, b = 5.40, c = 37 A 


110 


Bi 2 Sr 2 (Ln|. x Ce x ) 2 Cu 2 O| 0 


P4/mmm; a = 3.888, c = 17.28 A 


25 


TljBa^uOj 


A2aa; a = 5.468, b = 5.472, c = 23.238 A; 






14/mmm; a = 3.866, c= 23.239 A 


92 


T\ 2 CaBajC\i]O g 


14/mmm; a = 3.855, c = 29.3 18 A 


119 


Tl 2 Ca 2 Ba 2 Cu,O,0 


14/mmm; a = 3.85, c = 35.9 A 


128 


TI(BaLa)CuO s 


P4/mmm;a = 3.83,c = 9.55 A 


40 


Tl(SrLa)Cu0 5 


P4/mmm;a = 3.7,c = 9A 


40 


(TlajPboJS^CuOj 


P4/mmm; a = 3.738, c = 9.01 A 


40 


TlCaBa 2 Cu 2 0 7 


P4/mmm; a = 3.856, c = 12.754 A 


103 


(nojPbojJCaSrzCuA 


P4/mmm; a = 3.80, c = 12.05 A 


90 


TlSr 2 Y 0 jCao.5Cu 2 0 7 


P4/mmm;a = 3.80,c=12.10A 


90 


TlCa 2 Ba 2 Cu,0 8 


P4/mmm;a = 3.853,c= 15.913 A 


110 


CnojPMSr 2 Ca 2 Cu,0 9 


P4/mmm;a = 3.81,c= 15.23 A 


120 


TlBa 2 (La 1 . jr Ce l ) 2 Cu 2 0, 


14/mmm; a = 3.8, c = 29.5 A 


40 


PbjS^LaojCaa^CujOg 


Cmmm; a = 5.435, b = 5.463, c = 1 5.817 A 


70 


Pb^Sr.LahCujC^ 


P22,2;a = 5.333,6 = 5.421,c= 12.609 A 


32 


(Pb,Cu)Sr 2 (La,Ca)Cu 2 0 7 


P4/mmm; a = 3.820, c = 1 1 .826 A 


50 


(Pb,Cu)(Sr,Eu)(Eu,Ce)Cu 2 0, 


14/mmm; a = 3.837, c = 29.01 A 


25 


Nd 2 .,Ce r Cu0 4 


14/mmm; a = 3.95, c= 12.07 A 


30 


Ca.^CuOj 


P4/mmm; a = 3.902, c = 3.35 A 


110 


Sr.^Nd.CuO, 


P4/mmm; a = 3.942, c = 3.393 A 


40 


Bao. 6 Ko. 4 BiO, 


Pm3m;a = 4.287A 


31 


RbjCsCjo 


a =14.493 A 


31 


NdBa 2 Cu,0 7 


Pmmm; a = 3.878, b = 3.913, c = 1 1 .753 


58 



12-87 



BRIEF ATTACHMENT AD 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 14, 2005 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 

P.O. Box 1450 

Alexandria, VA 22313-1450 



In response to the Office Action dated July 28, 2004, please consider the 



The attachments referred to herein A to Z and AA are in the FIRST 
SUPPLEMENTAL AMENDMENT. The Attachments AB to AG are attached herein. 

Please charge any fee necessary to enter this paper and any previous paper to 
deposit account 09-0468. 



THIRD SUPPLEMENTAL AMENDMENT 



Sir 



following: 




Dr. Daniel P. Morris, Esq. 
Reg. No. 32,053 
(914) 945-3217 



IBM CORPORATION 
Intellectual Property Law Dept. 
P.O. Box 218 

Yorktown Heights, New York 10598 



ATTACHMENT AD 



Theory of 
Superconductivity 



By 

M. von LAUE 

Kaiser- Wilhelm-Institut fur physikalische ond Elektro-Chemie 
Berlin — DalUem ' 



Translated by 

LOTHAR MEYER 

University of Chicago. Chicago, Illinois 



WILLIAM BAUD 

The State College of Washington, Pullman, Washington 




ACADEMIC PRESS INC., PUBLISHERS 
New York, 1952 




R t -SOQ 



Fundamental Facts 
(a) Superconductivity was discovered in 1911 by Kamerlingh-Onnes.* 
He was the first to liquefy helium and so to produce temperatures below 
10° K. With this new technique he was able to observe the continued 
decrease of the electrical resistance of metals with decreasing temperature. 
With mercury, in contrast to other metals, he was astonished to find that 
the resistance completely vanished, almost discontinuously, at about 4.2° K 
(Fig. 1-1)- Today superconductivity is 
known in 18 other metals (see Table 
1-i) whereas in others, e. g., gold and 
bismuth, the conductivity remains nor- 
mal far below even 1° K. Many alloys 

/ ; arid compounds ' can also become super- 
conducting, in particular the frequently 

v used niobium nitride which has a tran- 
sition temperature as high as 20° K. 
However, among these latter substances 
hysteresis phenomena mentioned in the 

■^"Introduction" are so much more strongly 
evident that in testing the present theory 

- we prefer to employ only the "good" 

. superconductors, i. e., the pure elements. 

}■ ky ^ . In the ideal case the resistance vanishes 

^ completely and discontinuously at a tran- 
sition temperature T,. Actually the resi- 
stance-temperature curve does fall more 
sharply the more the specimen is like a 
single crystal and the smaller the mea- 
suring current used. ' Because the drop 

t . always occurs in a measurable tempera- 

••^ture* range, the experimental definition 

. - of -the transition temperature is to some 

4sextent arbitrary. The temperature at : . 

3- which the direct-current resistance reaches one half of the value; it had 
"" just before the drop is generally given as the transition temperature, because 
this -can be measured accurately. However, a high-frequency investigation 
to be described in Chap. 16 (f) indicates that the foot of the curve where 



absoluk ttmptrahre 

Fig. 1 — 1. Appearance of supercon- 
ductivity in mercury according to 
H. Kamerlingh-Onnes (1911). The 
ordinate is the resistance Jt; 
the resistance of solid mercury 
extrapolated to 0* C, is 60 ohms. 



l H. Kamerlingh-Onncs, Commtn 



Leiden. 120b, 



BRIEF ATTACHMENT AE 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 14, 2005 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



In response to the Office Action dated July 28, 2004, please consider the 



The attachments referred to herein A to Z and AA are in the FIRST 
SUPPLEMENTAL AMENDMENT. The Attachments AB to AG are attached herein. 

Please charge any fee necessary to enter this paper and any previous paper to 
deposit account 09-0468. 



THIRD SUPPLEMENTAL AMENDMENT 



Sin 



following: 




Dr. Daniel P. Morris, Esq. 
Reg. No. 32,053 
(914) 945-3217 



IBM CORPORATION 
Intellectual Property Law Dept. 
P.O. Box 218 

Yorktown Heights, New York 10598 



ATTACHMENT AE 



J 



Europalsches Patentamt 
European Patent Office 
Office europeen des brevets 



© Publication number: 



0 275 343 

A1 



© EUROPEAN PATENT APPLICATION 

© Application number: 87100961.9 © |„t CI. 4 : H01L 39/12 

© Oate of filing: 23.01.87 



© Date of publication of application: 
27.07.88 Bulletin 88/30 

© Designated Contracting States: 

AT BE CH DE ES FR 6B OR IT U LU NL SE 



© Applicant: International Business Machines 
Corporation 
Old Orchard Road 
Armonk, N.Y. 10504(US) 

© Inventor: Bednorz, Johannes Georg, Dr. 
Sonnenbergstrasse 47 
CH-8134 Adllswii(CH) 
Inventor: MUller, Carl Alexander, Prof. Dr.. 
Haldenstrasse 54 
CH-8908 Hedingen(CH) 



Rotfarbweg 1 

CH-8803 Ruschllkon(CH) 

© Representative: Rudack, QUnter O.. DIpL-lng. 
IBM Corporation SMumerstrasse 4 
CH-8803 RUschlikon(CH) 



© New superconductive compounds of the K2NIF4 structural type having a high transition 
temperature, and method to* fabricating same. 

© The superconductive compounds are oxides of 

the general formula REj.,«AE»TM.O«^ . wherein RE is 

a rare earth. AE is a member of the group of alkaline 

earths or a combination of at least two member of 

that group, and TM is a transition metal, and wherein 

x < 0.3 and 0.1 i y S0.5. The method for making 

these compounds involves the steps of coprecipitat- 

ing aqueous solutions of the respective nitrates of 

the constituents and adding the coprecipitate to ox- 
alic acid, decomposing the precipitate and causing a 
J! solid-state reaction at a temperature between 500 
^and 1200°C for between one and eight hours, for- 
COming pellets of the powdered product at high pres- 
sure, sintering the pellets at a temperature between 
"500 and lOOO'C for between one half and three 
Ift hours, and subjecting the pellets to an additional 

annealing treatment at a temperature between 500 

and 1200"C for between one half and five hours in a 
© protected atmosphere permitting the adjustment of 
j^the oxygen content of the final product. 
1U 



0 275 343 ™ 2 



SUPERCONDUCTIVE COMPOUNDS OF THE fcNIF, STRUCTURAL TYPE HAVING A HIGH TRANSITION 
TEMPERATURE, AND METHOD FOR FABRICATING SAME 



Field of the Invention 

The invention relates to a new class of super- 
conductors, in particular to components of the 
KjNiFi type of structure having superconductor 
properties below a relatively high transition tem- 
perature, and to a method for manufacturing those 
compounds. 



Background of the Invention 

Superconductivity is usually defined as the 
complete loss of electrical resistance of a material 
at a well-defined temperature. It is known to occur 
in many materials: About a quarter of the elements 
and over 1000 alloys and components have been 
found to be superconductors. Superconductivity is 
considered a property of the metallic state of the 
material, in that all known superconductors are 
metallic under the conditions that cause them to 
superconduct. A few normally non-metallic materi- 
als, for example, become superconductive under 
very high pressure, the pressure converting them 
to metals before they become superconductors. 

Superconductors are very attractive for the 
generation and energy-saving transport of electrical 
power over long distances, as materials for forming 
the coils of strong magnets for use in plasma and 
nuclear physics, in nuclear resonance medical di- 
agnosis, and in connection with the magnetic levita- 
tion of fast trains. Power generation by thermonu- 
clear fusion, for example, will require very large 
magnetic fields which can only be provided by 
superconducting magnets. Certainly, superconduc- 
tors will also find application in computers and 
high-speed signal processing and data communica- 
tion. 

While the advantages of superconductors are 
quite obvious, the common disadvantage of all 
superconductive materials so far known lies in their 
very low transition temperature (usually called the 
critical temperature TJ which is typically on the 
order of a few degrees Kelvin. The element with 
the highest Tjs niobium (9.2 K). and the highest 
known T c is about 23 K for NBjGe at ambient 
pressure. 

Accordingly, most known superconductors re- 
quire liquid helium for cooling and this, in turn, 
requires an elaborate technology and as a matter 
of principle involves a considerable investment in 
cost and energy. 

It is. therefore, an object of the present inven- 



tion to propose compositions for high-T e supercon- 
ductors and a manufacturing method for producing 
compounds which exhibit such a high critical tem- 
perature that cooling with liquid helium is obviated 

s so as to considerably reduce the cost involved and 
to save energy. 

The present invention proposes to use com- 
pounds having a layer-type structure of the kind 
known from potassium nickel fluoride KjNiFi. This 

io structure is in particular present in oxides of the 
general composition R&TM.Oi. wherein RE stands 
for the rare earths (lanthanides) and TM stands for 
the so-called transition metals. It is a characteristic 
of the present invention that in the compounds in 

;s question the RE portion is partially substituted by 
one member of the alkaline earth group of metals, 
or by a combination of the members of this alkaline 
earth group, and that the oxygen content is at a 
deficit 

20 For example, one such compound that meets 
the description given above is lanthanum copper 
oxide lACuOi in which the lanthanum -which be- 
longs to the IIIB group of elements-is in part substi- 
tuted by one member of the neighboring IIA group 
25 of elements, viz. by one of the alkaline earth metals 
(or by a combination of the members of the IIA 
group), e.g., by barium. Also, the oxygen content of 
the compound is incomplete such that the com- 
pound will have the general composition La 2 . 
ao *Ba x Cu04^ . wherein x S 0.3 and y < 0.5. 

Another example for a compound meeting the 
general formula given above is lanthanum nickel 
oxide wherein the lanthanum is partially substituted 
by strontium, yielding the general formula La 2 . 
as ..SrxNiO^ . Still another example is cerium nickel 
oxide wherein the cerium is partially substituted by 
calcium, resulting in Ce 2 .«Ca x Ni04^. 

The following description will mainly refer to 
barium as a partial replacement for the lanthanum 
40 in a LasCuOi compound because it is the Ba-La- 
Cu-0 system which is. at least at present, the best 
understood system of all possible. Some com- 
pounds of the Ba-La-Cu-0 system have been de- 
scribed by C. Michel and B. Raveau in Rev. Chim. 
as Min. 21 (1984) 407. and by C. Michel. L Er-Rakho 
and B. Raveau in Mat. Res. Bull.. Vol. 20. (1985) 
667-671. They did. however, not find nor try to find, 
superconductivity. 

Experiments conducted in connection with the 
so present invention have revealed that high-T c super- 
conductivity is present in compounds where the 
rare earth is partially replaced by any one or more 
of the other members of the same IIA group of 
elements, i.e. the other alkaline earth metals. Ac- 



2 



0 275 343 W 4 



tually, the T c of LazCuO^ with Sr 2 is higher and is 
superconductivity-induced diamagnetism larger 
than that found with Ba 2 and Ca 2 . 

As a matter of fact, only a small number of 
oxides is known to exhibit superconductivity, 
among them the U-Ti-0 system with onsets of 
superconductivity as high as 13.7 K, as reported by 
D.C. Johnston. H. Prakash. W.H. Zachariasen and 
R. Visvanathan in Mat. Res. Bull. 8 (1973) 777. 
Other known superconductive oxides include Nb- 
doped SrTiOs and BaPb,.„Bi x Oj . reported respec- 
tively by A. Baratoff and G. Binnig in Physics 108B 
(1981) 1335. and by A.W. Sleight JL Gillson and 
F.E. Bierstedt in Solid State Commun. 17 (1975) 
27. 

The X-ray analysis conducted by Johnston et 
al. revealed the presence in their U-Ti-0 system of 
three different crystallographic phases, one of 
them, with a spinel structure, showing the high 
critical temperature. The Ba-La-Cu-0 system, too. 
exhibits a number of crystallographic phases, 
namely with mixed-valent copper constituents 
which have itinerant electronic states between non- 
Jahn-Teller Cu 3 and Jahn-Teller Cu 2 ions. 

This applies likewise to systems where nickel 
is used in place of copper, with being the 
Jahn-Teller constituent and Ni 2 being the non- 
Jahn-Teller constituent 

The existence of Jahn-Teller polarons is con- 
ducting crystals was postulated theoretically by 
K.H. Hoeck. H. Nickisch and H. Thomas in Helv. 
Phys. Acta 56 (1983) 237. Polarons have large 
electron-phonon interactions and. therefore, are fa- 
vorable to the occurrance of superconductivity at 
high critical temperatures. 

Generally, the Ba-La-Cu-O system, when sub- 
jected to X-ray analysis reveales three individual 
crystallographic phases, viz. 

- a first layer-type perovskite-like phase, related to 
the K2NiFi structure, with the general composition 
La2.,Ba,CuO^, with X«1 and y*0; 

- a second, non-conducting CuO phase; and 

- a third, nearly cubic perovskite phase of the 
general composition Ui.«Ba x CuO> y which appears 
to be independent of the exact starting composi- 
tion, 

as has been reported in the paper by J.G. Bednorz 
and K.A. MOIIer in Z. Phys. B - Condensed Matter 
64 (1986) 189-193. Of these three phases the first 
one appears to be responsible for the high-T e 
superconductivity, the critical temperature showing 
a dependence on the barium concentration in that 
phase. Obviously, the Ba 2 substitution causes a 
mixed-valent state of Cu 2 and Cu» to preserve 
charge neutrality. It is assumed that the oxygen 
deficiency, y, is the same in the doped and un- 
doped crystallites. 

Both LajCuO* and LaCuO] are metallic conduc- 



tors at high temperatures in the absence of barium. 
Actually, both are metals like LaNiO). Despite their 
metallic character, the Ba-La-Cu-0 type materials 
are ceramics, as are the other compounds of the 

s R&TM.O* type, and their manufacture more or less 
follows the known principles of ceramic fabrication. 
The preparation of a Ba-La-Cu-0 compound, for 
example, in accordance with the present invention 
typically involves the following manufacturing 

io steps: 

• Preparing aqueous solutions of the respective 
nitrates of barium, lanthanum and copper and 
coprecipitation therof in their appropriate ratios. 

- Adding the coprecipitate to oxalic acid and for- 
(5 ming an intimate mixture of the respective oxalates. 

- Decomposing the precipitate and causing a solid- 
state reaction by heating the precipitate to a tem- 
perature between 500 and 1200°C for one to eight 
hours. 

20 - Pressing the resulting product at a pressure of 
about 4 kbar to form pellets. 

- Re-heating the pellets to a temperature between 
500 and 900 8 C for one half to three hours for 
sintering. 

25 It will be evident to those skilled in the art that 
if the partial substitution of the lanthanum by stron- 
tium or calcium is desired, the particular nitrate 
thereof will have to be used in place of the barium 
nitrate of the example described above. Also, if the 

30 copper of this example is to be replaced by an- 
other transition metal, the nitrate thereof will obvi- 
ously have to be employed. 

Experiments have shown that the partial con- 
tents of the individual compounds in the starting 

35 composition play an important role in the formation 
of the phases present in the final product. While, as 
mentioned above, the final Ba-La-Cu-0 system ob- 
tained generally contains the said three phases, 
with the second phase being present only to a very 

4d small amount, the partial substitution of lanthanum 
by strontium or calcium (and perhaps beryllium) 
will result in only one phase existing in the final 
Ui-xSr.CuO^ or Laa-xCaxCuO^. respectively, pro- 
vided x < 0.3. 

45 With a ratio of 1:1 for the respective (Ba. La) 
and Cu contents, one may expect the said three 
phases to occur in the final product. Setting aside 
the said second phase, i.e. the CuO phase, whose 
amount is negligible, the relative volume amounts 

so of the other two phases are dependent on the 
barium contents in the La 2 . x BaxCu04^ complex. At 
the 1:1 ratio and with an x * 0.02. the onset of a 
localization transition is observed, i.e., the resistiv- 
ity increases with decreasing temperature, and 

55 there is no superconductivity. i 

With x = 0.1 at the same 1:1 ratio, there is a 
resistivity drop at the very high critical temperature 
Of 35 K. 



3 



0 275 343 w 6 



With a (Ba.La) versus Cu ratio of 2:1 in trie 
starting composition, the composition of the 
La2CuOi:Ba phase, which was assumed to be re- 
sponsible for the serconductivity. is imitated, with 
the result that now only two phases are present, 
the CuO phase not existing. With a barium content 
of x = 0.15, the resistivity drop occurs at T c = 26 
K. 

The method for preparing the Ba-La-Cu-0 
complex involves two heat treatments for the 
precipitate at an elevated temperature for several 
hours. In the experiments carried out in connection 
with the present invention it was found that best 
results were obtained at 900°C for a decomposition 
and reaction period of 5 hours, and again at 900 °C 
for a sintering period of one hour. These values 
apply to a ratio 1:1 composition as well as to a 2:1 
composition. 

For the ratio 2:1 composition, a somewhat 
higher temperature is permissible owing to the 
melting point of the composition being higher in the 
absence of excess copper oxide. Yet it is not 
possible by high-temperature treatment to obtain a 
one-phase compound. 

Measurements of the dc conductivity were con- 
ducted between 300 and 4.2 K. For barium-doped 
samples, for example, with x < 0.3. at current 
densities of 0.5 A/cm 2 , a high-temperature metallic 
behavior with an increase in resistivity at low tem- 
peratures was found. At still lower temperatures, a 
sharp drop in resistivity (>90%) occurred which for 
higher current densities became partially sup- 
pressed. This characteristic drop was studied as a 
function of the annealing conditions, i.e. tempera- 
ture and oxygen partial pressure. For samples an- 
nealed in air. the transition from itinerant to lo- 
calized behavior was not found to be very pro- 
nounced, annealing in a slightly reducing atmo- 
sphere, however, led to an increase in resistivity 
and a more pronounced localization effect At the 
same time, the onset of the resistivity drop was 
shifted towards higher values of the critical tem- 
perature. Longer annealing times, however, com- 
pletely destroy the superconductivity. 

Cooling the samples from room temperature, 
the resistivity data first show a metal-like decrease. 
At low temperatures, a change to an increase oc- 
curs in the case of Ca compounds and for the 6a- 
substituted samples. This increase is followed by a 
resistivity drop, showing the onset of superconduc- 
tivity at 22±2 K and 33±2 K for the Ca and Ba 
compounds, respectively. In the Sr compound, the 
resistivity remains metallic down to the resistivity 
drop at 40tl K. The presence of localization ef- 
fects, however, depends strongly on alkaline-earth 
ion concentration and sample preparation, that is to 
say, annealing conditions and also on the density 
which have to be optimized. All samples with low 



concentrations of Ca. Sr, and Ba show a strong 
tendency to localization before the resistivity drop 
occur. 

Apparently, the onset of the superconductivity, 

5 i.e the value of the critical temperature T c , is de- 
pendent among other parameters, on the oxygen 
content of the final compound. It seems that a 
certain oxygen deficiency is necessary for the ma- 
terial to have a high-T c behavior. In accordance 

io with the present invention, the method described 
above for making the LaaCuO^Ba complex is com- 
plemented by an annealing step during which the 
oxygen content of the final product can be ad- 
justed. Of course, what was said in connection with 

is the formation of the LajCuO^Ba compound, like- 
wise applies to other compounds of the general 
formula RE2TM.OME, such as, e.g. NdjNiCkSr. 

In the cases where a heat treatment for de- 
composition and reaction and/or for sintering was 

20 performed at a relatively low temperature, i.e. at no 
more than 950°C, the final product is subjected to 
an annealing step at about 900°C for about one 
hour in a reducing atmosphere, it is assumed that 
the net effect of this annealing step is a removal of 

25 oxygen atoms from certain locations in the matrix 
of the RE2TM.O4 complex, thus creating a distortion 
in its crystalline structure. The O2 partial pressure 
for annealing in this case may be between 10 1 
and 10 5 bar. 

30 In those cases where a relatively high tempera- 
ture (i-e. above 950°C) was employed for the heat 
treatment, it might be advantageous to perform the 
annealing step in a slightly oxidizing atmosphere. 
This would make up for an assumed exaggerated 

35 removal of oxygen atoms from the system owing to 
the high temperature and resulting in a too severe 
distortion of the system's crystalline structure. 

Resistivity and susceptibility measurements, as 
a function of temperature, of Sr 2 and Ca 2 -doped 

40 LajCuO^ ceramics show the same general ten- 
dency as the Ba 2 -doped samples: A drop in re- 
sistivity p(T), and a crossover to diamagnetjsm at a 
slightly lower temperature. The samples containing 
Sr 2 actually yielded a higher onset than those 

45 containing Ba 2 and Ca 2 . Furthermore, the dia- 
magnetic susceptibility is about three times as 
large as for the Ba samples. As the ionic radius of 
Sr 2 nearly matches the one of La 3 . it seems that 
the size effect does not cause the occurrence of 

so superconductivity. On the contrary, it is rather ad- 
verse, as the data on Ba 2 and Ca 2 indicate. 

The highest T c 's for each of the dopant ions 
investigated occur for those concentrations where, 
at room temperature, the Re 2 .,,TM x O< 1r structure is 

55 close to the orthorhombic-tetragonal structural 
phase transition which may be related to the sub- 
stantial electron-phonon interaction enhanced by 
the substitution. The alkaline-earth substitution of 



4 



the rare earth metal is clearly important, and quite 
likely creates TM ions with no e g Jahn-Teller or- 
bitals. Therefore, the absence of these J.-T. or- 
bitals, that is, J.-T. holes near the Fermi energy 
probably plays an important role for the T c en- 
hancement. 



Claims 

1 ) Superconductive compound of the R&TM.O* 
type having a transition temperature above 28 K, 
wherein the rare earth (RE) is partially substituted 
by one or more members of the alkaline earth 
groups of elements (AE), and wherein the oxygen 
content is adjusted such that the resulting crystal 
structure is distorted and comprises a phase of the 
general composition REj-.AE.JM.O^ . wherein TM 
represents a transition metal, and x < 0.3 and y < 
0.5. 

2) Compound in accordance with claim 1, 
wherein the rare earth (RE) is lanthanum and the 
transition metal (TM) is copper. 

3) Compound in accordance with claim 1, 
wherein the rare earth is cerium and the transition 
metal is nickel. 

4) Compound in accordance with claim 1. 
wherein the rare earth is lanthanum and the transi- 
tion metal is nickel. 

5) Compound in accordance with claim 1, 
wherein barium is used as a partial substitute for 
the rare earth, with x < 0.3 and 0.1 S y S 0.5. 

6) Compound in accordance with claim 1. 
wherein calcium is used as a partial substitute for 
the rare earth, with x < 0.3 and 0.1 £ y S 0.5. 

7) Compound in accordance with claim 1. 
wherein strontium is used as a partial substitute for 
the rare earth, with x < 0.3 and 0.1 i y S 0.5. 

8) Compound in accordance with claim 1, 
wherein the rare earth is lanthanum and the transi- 
tion metal is chromium. 

9) Compound is accordance with claim 1. 
wherein the rare earth is neodymium and the tran- 
sition metal is copper. 

10) Method for making superconductive com- 
pounds of the RE2TM.O4 type, with RE being a rare 
earth, TM being a transition metal, the compounds 
having a transition temperature above 26 K, com- 
prising the steps of: 

- preparing aqueous solutions of the nitrates of the 
rare earth and transition metal constituents and of 
one or more of the alkaline earth metals and 
coprecipitation thereof in their appropriate ratios; 

- adding the coprecipitate to oxalic acid and for- 
ming an intimate mixture of the respective oxalates: 
• decomposing the precipitate and causing a solid- 
state reaction by heating the precipitate to a tem- 
perature between 500 and 1200"C for a period of 



time between one and eight hours: 

- allowing the resultant powder product to cool: 

- pressing the powder at a pressure of between 2 
and 10 kbar to form pellets: 

5 - re-adjusting the temperature of the pellets to a 
value between 500 and 10O0°C for a period of time 
between one half and three hours for sintering; 

- subjecting the pellets to an additional annealing 
treatment at a temperature between 500 and 

10 1200°C for a period of time between one half and 
5 hours in a protected atmosphere permitting the 
adjustment of the oxygen content of the final prod- 
uct which has a final composition of the form RE 2 . 
.TM.O*^, wherein x < 0.3 and 0.1 < y < 0.5. 

is 11) Method in accordance with claim 10. 
wherein the protected atmosphere is pure oxygen. 

12) Method in accordance with claim 10. 
wherein the protected atmosphere is a reducing 
atmosphere with an oxygen partial pressure be- 
so tween 10' and 10 s bar. 

13) Method in accordance with claim 10. 
wherein the decomposition step is performed at a 
temperature of 900'' C for 5 hours, and wherein the 
annealing step is performed at a temperature of 

25 900* C for one hour in a reducing atmosphere with 
an oxygen partial pressure between 10 ' and 10 s 
bar. 

14) Method in accordance with claim 10, 
wherein lanthanum is used as the rare earth and 

30 copper is used as the transition metal, and wherein 
barium is used to partially substitute for the lan- 
thanum, with x < 0.2. wherein the decomposition 
step is performed at a temperature of 900°C for 5 
hours, and wherein the annealing step is performed 

35 in a reducing atmosphere with an oxygen partial 
pressure on the order of 10 3 bar and at a tem- 
perature of 900 o C for one hour. 

15) Method in accordance with claim 10, 
wherein lanthanum is used as the rare earth and 

40 nickel is used as the transition metal, and wherein 
barium is used to partially substitute for the lan- 
thanum, with x < 0.2, wherein the decomposition 
step is performed at a temperature of 900 °C for 5 
hours, and wherein the annealing step is performed 

is in a reducing atmosphere with an oxygen partial 
pressure on the order of 10 3 bar and at a tem- 
perature of 900° C for one hour. 

16) Method in accordance with claim 10. 
wherein lanthanum is used as the rare earth and 

so copper is used as the transition metal, and wherein 
calcium is used to partially substitute for the lan- 
thanum, with x < 02. wherein the decomposition 
step is performed at a temperature of 900° C for 5 
hours, and wherein the annealing step is performed 

55 in a reducing atmosphere with an oxygen partial 
pressure on the order of 10 3 bar and at a tem- 
perature of 900°C for one hour. 



5 



0 275 343 



17) Method in accordance with claim 10, 
wherein lanthanum is used as the rare earth and 
copper is used as the transition metal, and wherein 
strontium is used to partially substitute for the 
lanthanum, with x < 0.2. wherein the decomposition s 
step is performed at a temperature of 900°C for 5 
hours, and wherein the annealing step is performed 

in a reducing atmosphere with an oxygen partial 
pressure on the order of 10 3 bar and at a tem- 
perature of 900*0 for one hour. to 

18) Method in accordance with claim 10, 
wherein cerium is used as the rare earth and nickel 
is used as the transition metal, and wherein barium 
is used to partially substitute for the cerium, with x 

< 02. wherein the decomposition step is per- is 
formed at a temperature of 900°C for 5 hours, and 
wherein the annealing step is performed in a re- 
ducing atmosphere with an oxygen partial pressure 
on the order of 10 3 bar and at a temperature of 
900 °C for one hour.. 20 



6 



BRIEF ATTACHMENT AF 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorzetal. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 14, 2005 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



In response to the Office Action dated July 28, 2004, please consider the 
following: 

The attachments referred to herein A to Z and AA are in the FIRST 
SUPPLEMENTAL AMENDMENT. The Attachments AB to AG are attached herein. 

Please charge any fee necessary to enter this paper and any previous paper to 
deposit account 09-0468. 



THIRD SUPPLEMENTAL AMENDMENT 



Sir 




Reg. No. 32,05- 
(914) 945-3217 



IBM CORPORATION 
Intellectual Property Law Dept. 
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ATTACHMENT AF 



COPPER OXIDE 
SUPERCONDUCTORS 



Charles P. Poole, Jr. 
TimirDatta 
Horacio A. Farach 

with help from 

M. M. Rigney 
C. R. Sanders 

Department of Physics and Astronomy 
University of South Carolina 
Columbia. South Carolina 




A Wilejr-Interscience Publication 
JOHN WILEY & SONS 

New York • Chichester • Brisbane • Toronto • Singapore 




METHODS OF PREPARATION 61 



iSrCaCu0 7 - 4 (a) 
luminum-doped 
lple calcined at 
and (g) calcined 



the same tem- 

the early work 
I out with thin 
paration tech- 
ich samples, 
n, and others 
;entative tech- 

■ulk supercon- 
h as thin films 
ys of checking 
or subsolidus 
Fig. V-2 con- 
l-point oxides 
°, (Ba 3 Cu0 4 ), 
> 7 ), along the 
ig green phase 
n the interior 
urth, Kuzzz, 
). Compounds 
workers. The 
so), and then 




Ba 3 Y 4 09 BaY 2 0 4 



Compound 



123- YBazCuaCWj 
143-YBa<Cu30B5»6 
385-Y3Ba8Cu50,7.s t4 
152-YBa 5 Cu 2 0(i5 t6 
211 - YjBaCuOs 
Ba 2 Cu0 3 » 6 



Fig. V-2. Ternary phase diagram of the Y 2 0 3 -BaO-CuO system at 950°C. The green 
phase [Y 2 BaCuO s , (211)] the superconducting phase [YBa 2 Cu 3 07- 4> (123)], and three 
other compounds are shown in the interior of the diagram (DeLee). 



B. METHODS OF PREPARATION 

In this section three methods of preparation will be described, namely, the solid 
state, the coprecipitation, and the sol-gel techniques (Hatfi). The widely used 
solid-state technique permits off-the-shelf chemicals to be directly calcined into 
superconductors, and it requires little familiarity with the subtle physicochemi- 
cal processes involved in the transformation of a mixture of compounds into a 
superconductor. The coprecipitation technique mixes the constituents on an 
atomic scale and forms fine powders, but it requires careful control of the pH 
and some familiarity with analytical chemistry. The sol-gel procedure requires 
more competence in analytical procedures. 

In the solid-state reaction technique one starts with oxygen-rich compounds 
of the desired components such as oxides, nitrates, or carbonates of Ba, Bi, La, 
Sr, Tl, Y, or other elements. Sometimes nitrates are formed first by dissolving 
oxides in nitric acid and decomposing the solution at 500°C before calcination 



I 

8 

I 

! 

3 



62 PREPARATION AND CHARACTERIZATION OF SAMPLES 

are thoroughly mixed andXln , powdered precursor materials 

Sreen Y !B aCuO s phasf ,o Ha rl gr a VBa C» I"** TZT °* 



:ired atomic 
)cess. Then 
xtended pe- 
be repeated 
material at 
The process 
wn to room 
ntering in a 
sss, but for 
erial pellet- 
lid-state re- 
jkl.Hatan, 
>epp, Polle, 
Vuzz3). 
employed a 
the desired 
; extruding, 

calcination 
.ela, Bedno, 
n an atomic 
formity can 
cipitate has 
re. A disad- 
erials scien- 
rocedures. 
;1 technique 
Cu, and Y 
ire gelled by 
:ts the nitric 
is been per- 

ination pro- 
stle or a ball 
or materials 
:. Care must 
chemicals to 

.g., Gran2). 
/gen around 
: lor from the 
d. Then the 
its purity. If 
: is repeated, 
ly it is semi- 



ADDITIONAL COMMENTS ON PREPARATION 63 

conducting or even nonconducting. After peptizing at >10 5 psi the pellet is 
sintered for several hours at =900°C in flowing oxygen and then slowly cooled 
at - 3°C/min down to room temperature. Slow cooling from the elevated tem- 
perature is important for producing the low-temperature orthorhombic super- 
conductor phase. The tetragonal nonsuperconducting phase may be obtained by 
quenching. The pellet may be used as is or it may be cut into suitable sizes by 
sand blasting, with a diamond saw, or with an arc. After vigorous machining 
another oxygen anneal (450°C, 1 hr, slow cool down) is often required to pre- 
serve the superconducting properties. 

An example of preparing a Bi-based superconductor involves mixing gravi- 
metric amounts of high-purity Bi 2 0 3) SrC0 3 , CaC0 3 , and CuO powders, calcin- 
ing them in air at 750-890°C, regrinding them, and then repeating these proce- 
dures several times. Then pellets of the calcined product were sintered at the 
same temperature and quenched to room temperature (Chuz5). Figure V-l 
shows the effect of sample treatment on the resistance versus temperature 
curve. 

WARNING- As was mentioned above, thallium is a toxic material and proper 
precautions must be taken when working with it. It is useful to start by preparing 
the high-quality precursor compound BaCu 3 0< or Ba 2 Cu 3 0 5 by reacting the ox- 
ides in air at 925°C for 24 hr. Then appropriate amounts of Tl£> 3 are added, 
powdered, and peptized. The pellet is then heated to 880-910°Cfor a few min- 
utes inflowing oxygen, and at the onset of melting it is quenched to room tern- 

perature (ShenlJ. . , 

Allen Hermann has suggested consulting the following references for infor- 
mation on thallium poisoning and antidotes thereto: H. Heydlanf Euro. J. 
Pharmacol 6. 340 (1969). which discusses thallium poisoning and describes the 
antidote ferric cyanoferrate. and Int. J. Pharmacol. 10, / (1974). which dis- 
cusses cases of thallium intoxication treated with Prussian Blue. 



C. ADDITIONAL COMMENTS ON PREPARATION 

This section will treat some additional methods which have been employed for 
the preparation of samples. 

In one experiment coprecipitated nitrates of La. Sr, Cu, and Na carbonate 
were calcined for 2 hr at 825°C, pressed into pellets, and then subjected to shock 
compression of = 20 GPa at an estimated peak temperature of =1000 C 
(Graha). The best superconductivity was observed after 1 hr of air exposure at 
1100°C. Shock compression fabrication has also been reported (Murrz, Murrl) 
for YBa* and other rare-earth derivatives. This process produced "monoliths, 
distinct from the usual composites. c r> r 

Another technique involved the formation of a precursor alloy of Eu, Ba, Ui 
or Yb, Ba Cu by rapid solidification, with the superconducting materials ob- 
tained subsequently by oxidation (Halda). A novel method involved preparing 



M 
S 

I 



i 




64 PREPARATION AND CHARACTERIZATION OF SAMPLES 

the superconductors from molten Ba-Cu oxides and solid rare-earth-containing 
materials. In principle this process may be better controlled and complicated 
shapes can be molded or cast (Herma). 

Pulsed current densities of 300-400 A /cm 2 with rise times of 0.6 usee at room 
temperature were used to convert the weakly semiconducting phase of YBaCuO 
to the stable metallic phase (Djure, Djurl). 

A claim was made that thermal cycling from cryogenic temperatures to 240 K 
raised the T c of YBa* and YBaCuO-F (with some F substituting for O) to 159 K. 
Cycling above 140 K lowered T c . This cycling process could possibly change the 
density of twins and thereby enhance T c . 

A freeze-drying technique was reported as producing sintered materials ho- 
mogeneous in composition and small in porosity (Stras). The low-temperature 
firing of oxalates (T < 780°C) has also been reported as producing a homogene- 
ous material of small grain size (Manth). 

Both Bi and Pb act as fluxes during the sintering process (Kilco). Bismuth 
substitution appears to reduce the normal state resistivity by about an order of 
magnitude without affecting the superconducting properties. 

A convenient method of separating the superconducting particles from a pow- 
dered mixture using magnetic levitation has been reported (Barso). This maybe 
used to select the superconducting fraction after each calcination process. 



D. FILMS 

The new ceramic oxide superconductors presently lack mechanical properties 
such as ductility which are needed for high-current applications like magnet wire 
fabrication (Jinzz-Jinz3) and power transmission. To circumvent some of these 
deficiencies for microelectronic applications one can prepare thin films on suit- 
able substrates. Some devices such as Josephson junctions require thin super- 
conducting films. Many workers have discussed the preparation and properties 
of LaSrCuO- (e.g., Adach, Delim, Kawas, Koinu, Matsu, Nagat, Naito, Teral) 
and YBaCuO-(e.g., Burbi, Charz, Evett, Gurvi, Hause, Hongz, Inamz, Kwozz, 
Kwozl, Manki, Scheu, Somek, Wuzz4) type films. 

Almost every conceivable thin-film deposition technique such as electron 
beam evaporation, molecular beam epitaxy, sputtering, magnetron, laser abla- 
tion, screening, and spraying has been tried with the copper oxide system. Some 
of these techniques require expensive, elaborate apparatus, although descrip- 
tions of simple thin-film deposition systems are also available (e.g., see Koinl). 
Some representative examples of deposition procedures will be discussed. 

Epitaxial films of YBa 2 Cu 3 0 7 .i on (100) SrTiOj were produced using three 
separate electron beam sources (e.g., Chaud, Chaul, Laibo). The deposition 
was done in lO^-lO -3 torr 0 2 with a substrate temperature of 400°C. The de- 
posited films were atomically amorphous with a broad X-ray peak. The epitaxial 
ordering was achieved upon annealing in 0 2 at 900°C with the orthorhombic c 
axis essentially perpendicular to the plane. 



High-quality 
beam to evapon 
torr (Hammo, C 
ited film in oxyg 
750°C for 1 hr, 
furnace. 

Superconduc 
rangement (Ma 
was Ar or an Ar 
10 _7 torr and, v 
Zr0 2 -9% Y 2 0 3 
films. The films 
gen annealing. '. 
erties dependec 
conditions, con 
Films of dys] 
beam epitaxy (1 
cess was monitc 
copper was inc< 
amorphous Ba ; 
high-temperati 
Films of Y,. : 
ness of 500 A 
ited on SrTi0 3 
pellet of YBaCi 
The evaporatio 
6 Hz, -30 nse 
heated to 450°' 
they appeared 
oxygen anneak 
hours. Standai 
perconductivit; 
tivity achieved 
LaSr* (Moorj) 
Films were > 
and Cu in lay 
200°C and 10 
layers to diffu: 
ducting compc 
conductivity w 
Y 2 0 3 , and Ba< 
Some 5000- 
vacuum dc-m 
was 0.2 A/se. 
strate distance 



FILMS 65 



rth-containing 
d complicated 

.6 /xsec at room 
iseofYBaCuO 

aturesto240K 
orO)to 159 K. 
ibly change the 

i materials ho- 
iw-temperature 
lg a homogene- 

:ilco). Bismuth 
out an order of 

:les from a pow- 
o). This may be 
m process. 



nical properties 
ike magnet wire 
it some of these 
in films on suit- 
uire thin super- 
i and properties 
t, Naito, Teral) 
Inamz, Kwozz, 

uch as electron 
tron, laser abla- 
ie system. Some 
though descrip- 
; .g., see Koinl). 

discussed, 
iced using three 

The deposition 

400°C. The de- 
lk.The epitaxial 

orthorhombic c 



High-quality superconducting films were obtained using a multiple electron 
beam to evaporate metallic sources in a flow of molecular oxygen at 4-5 X 10 
torr (Hammo, Ohzzz). The deposition rate was 10 A/sec. To anneal the depos- 
ited film in oxygen it was heated for 3-6 hr in a flow of oxygen at 650 C, raised to 
750°C for 1 hr, then to 850°C for 1 hr, and finally slowly cooled down in the 

Superconducting films were prepared using a double ion beam sputtering ar- 
rangement (Madak). The target beam was Ar at 40 mA, and the substrate beam 
was Ar or an Ar-0 2 mixture at 10-500 eV and 2 m A. The base pressure was 5 X 
10- 7 torr and, with the gas, 4 X lO" 4 torr. The best substrate materials such as 
Zr0 2 -9% Y 2 0 3 did not appreciably interact, diffuse, or change the deposited 
films The films were - 1 /xm thick and were rendered superconducting by oxy- 
gen annealing. Zero resistance was attained at 88 K. The superconducting prop- 
erties depended upon the ion beam energy, substrate temperature, annealing 
conditions, composition, and the extent of poisoning from the substrate 

Films of dysprosium barium copper oxide were grown (Webbz) by molecular 
beam epitaxy (MBE) using a Varian 360 MBE system and the nucleation pro- 
cess was monitored by reflection high-energy electron diffraction (RHEED). The 
copper was incompletely oxidized in metallic microcrystals growing in a sea of 
amorphous Ba and Dy . After deposition superconducting films were obtained by 
high-temperature oxygen annealing. m 

Films of Y, ,Ba, 5 Cu 3 0 6 .< approximately 3300 A thick with a surface rough- 
ness of 500 A were prepared (Dijkk, Inamz, Wuzz4). These films were depos- 
ited on SrTi0 3 , sapphire, and vitron carbon by evaporation from a single bulk 
pellet of YBaCuO 1 cm diameter and 0.2 cm thick at a pressure of 5 X 10 torr. 
The evaporation was produced by several thousand pulses of laser irradiation (3- 
6 Hz ~30 nsec width, 1 J/pulse, 2 J/cm 2 ). For best results the substrate was 
heated to 450°C. As deposited thin films were well bonded to the substrate and 
they appeared shiny dark brown and were electrically insulating. The films were 
oxygen annealed at 900°C for 1 hr and then slowly cooled over a period of several 
hours Standard four-probe resistivity measurements indicated the onset of su- 
perconductivity around 95 K and, for a (100) SrTi0 3 substrate, with zero resis- 
tivity achieved near 85 K. The laser ablation technique was also employed for 
LaSr* (Moorj) and YBa* (Naral). _ 

Films were obtained from sandwiched multilayers by depositing Y 2 0 3 , BaU, 
and Cu in layers (Nasta, Tsaur) on Zr0 2 , MgO, and sapphire substrates at 
200°C and 10~ s torr. Oxygen treatment for 1-2 hr at ~850°C permitted the 
layers to diffuse, homogenize, and oxygenate, and thereby form the supercon- 
ducting compound (Baozz). Films on Ni have also been reported in which super- 
conductivity was obtained by a diffusion process involving the Cu substrate, 
Y 2 0 3 , and BaC0 3 composite (Tachi). 

Some 5000- A thick films of YBaCuO have been deposited using an ultrahigh 
vacuum dc-magnetron getter-sputter deposition system. The deposition rate 
was 0.2 A /sec, the substrate temperature was 1050°C, and the target-to-sub- 
strate distance was 12 cm. The scattering was done in an Ar-0 2 atmosphere. 



66 PREPARATION AND CHARACTERIZATION OF SAMPLES 

The X-ray and electron microscope examinations indicated some variation 
among the substrates arranged on the heater. Inhomogeneities were observed 
even within the film made on a single substrate. As deposited the films were 
oxygen deficient, and annealing produced suitable compositions. The reversible 
oxygen incorporation was monitored by the systematic splitting of the strongest 
X-ray peaks. The oxygen diffusion coefficient at 600°C was 10" •* mVsec and the 
activatjon energies for desorption and absorption were 1.1 and 1.7 e V, respec- 
I'mo'/p g ° nSCt tem P erature was 99 K ^th complete superconduction 
at 40 K. Exposure to water inhibited the superconductor (Barns, Kishi, Yanzz) 
A device structure with a Y 2 0 3 barrier has also been studied (Blami) 

Another work showed that films produced by dc magnetron sputtering are 
copper deficient ,f the substrate-to-target distance is large or if the substrate is at 
an elevated temperature (Leez5). 

Superconducting YBaCuO thin films with a large surface area ( = 5 cm X 
5 cm) were grown on A1 2 0 3 , sapphire, and MgO up to a 500°C substrate temper- 
ature by magnetron and diode techniques. Rutherford back scattering (RBS) 
indicated a uniform composition across magnetron-deposited film areas with di- 
ameters up to 5 cm, and the diode film composition homogeneity was even bet- 

Innel^" " Sm T~ ( ~ 2 5 Cm diamCter) - The ^Posited films were 
annealed m oxygen at different temperatures and exposure times. Prolonged 
h gh-temperature annealing (>850°C) increased the impurity phase. The high- 

Sh In Tk t 3 W ', fange ° f com P° sition ' wi *« ^e maximum T c film copper 
rich On the basis of an ,n-situ resistivity study of YBa* thin films a rapid heat- 
mg to about 900°C in flowing helium followed by slow cool down in flowing oxy- 
gen was recommended (David). S y 
The post-deposition anneal cycle was avoided by producing the films in a 
Sr? Ure rr? Ve evaporation process invol ving rapid thermal annealing 
(Lathr). Smooth films were obtained on zirconia and SrTiO, substrates. Screen 
printing of oxide superconducting films is also possible (Budha, Fuzzl) and 
simple spray deposition has been reported (Gupta). Films have also been made 
ZZ <\ ?? mnS ° ff thC S ° ,Uti0nS - A( * ueous and aqueous-alcoholic 

(Rcei trr f ?:r a, f rates(CMp2),metaiacetatesindiiutea -ticacid 

R eel), and sol-gels (Kraml) have all been reported. These processes are poten- 
o„ lr7 . , C ° mmerCial superconducti "8 ratings on silicon (Kraml), 
(Gu^ta r " 1) Z Z ' rCOnia (YSZ) ' °" SrTi ° 3 (C0 ° P2 ' Gupta) ' and on M 80 



E. SINGLE CRYSTALS 



The bulk properties of oxide superconductors are averages over components 

Lmo I! [T to Ca ~° p,an - In add ^n, for orthorZbt 

samples there ,s an averaging over properties that differ for the a and b direc- 
tions in th ,s plan . This in-plane anisotropy is especially pronounced for the 
YBa* 123 structure in wh.ch the Cu-O-Gu-O chains lie along the b axis The 



best way to u 
crystals. Unl 
anisotropy cj 
twinning pro 
gle crystals. 

A numbe 
X-ray diffra< 
(e.g., Crabt, 
and micro- R 
scribe how s 
Crystal Gro\ 
Millimete 
oxide flux ( 
Taka4, Zhoi 
contaminate 
a hot press < 
(Satoz). 

Small sin| 
der which w 
sphere and 1 
ture also pre 
melting a st 
followed by 
A gold cr 
(1X2X0. 
was heated i 
400°C at 25' 
on the surfa 
the crucible 
A detailei 
crystal by th 
1:3 and 2:i 
multistep te 
found at th< 
crucibles. P 
crucibles w< 
ported. A s 
DyBa* as Is 



F. ALIGN] 

Clearly higl 
of supercon 




ALIGNED GRAINS 



some variation 
: were observed 

the films were 
. The reversible 
of the strongest 

mVsec and the 
1.7 eV, respec- 
jperconduction 

Kishi, Yanzz). 
lami). 

i sputtering are 
e substrate is at 

rea ( = 5 cm X 
bstrate temper- 
:attering (RBS) 
m areas with di- 
:y was even bet- 
;ited films were 
mes. Prolonged 
hase. The high- 
1 T c film copper 
ns a rapid heat- 
i in flowing oxy- 

; the films in a 
rmal annealing 
Dstrates. Screen 
ia, Fuzzl), and 
also been made 
leous-alcoholic 
ilute acetic acid 
esses are poten- 
ilicon (Kraml), 
0, and on MgO 



best way to understand these materials is through experiments on perfect single 
crystals. Unfortunately, untwinned YBa* crystals are not available so the a ,b 
anisotropy cannot be resolved. Tetragonal superconductors should not have this 
twinning problem. In this work twinned monocrystals will be referred to as sin- 
gle crystals. 

A number of experiments have been carried out on monocrystals such as 
X-ray diffraction (e.g., Borde, Hazen, Lepag, Siegr, Onoda), magnetic studies 
(e.g., Crabt, Schnl, Worth), mechanical measurements (e.g., Cookz, Dinge), 
and micro-Raman spectroscopy (e.g., Hemle). In this section we will briefly de- 
scribe how such crystals are made. The December 1987 issue of the Journal of 
Crystal Growth was devoted to superconductors. 

Millimeter-size (Lai. Jr Sr J ) 2 Cu04 single crystals were grown in a molten copper 
oxide flux (Kawal). Another basic technique employs other fluxes (Haned, 
Taka4, Zhoul), namely, PbF 2) B 2 0 3 , PbO, Pb0 2 , with the risk of possible Pb 
contamination. LaSr* crystals were also grown by the solid phase reaction using 
a hot press of pellets (Iwazu) and rapid quenching of a nonstoichiometric melt 
(Satoz). 

Small single crystals of YBa 2 Cu 3 0 7 . i have been prepared from a sintered pow- 
der which was formed into a pellet and then heated, first in a reducing atmo- 
sphere and then in an oxidizing one at 925°C. Annealing a stoichiometric mix- 
ture also produced monocrystals (Liuzz). Millimeter-size crystals were grown by 
melting a stoichiometric mixture of YBa 2 Cu 3 0 7 _ 4 plus excess CuO at 1150°C 
followed by holding at 900°C for 4 days (Damen, see also Finel). 

A gold crucible on a gold or alumina sheet was used to obtain free-standing 
(1 X 2 X 0.1 mm) single crystals of YBa* (Kaise, Kaisl, Holtz). A charge of 2 g 
was heated in air at 200°C/hr and held at 975°C for 1 .5 hr, then it was cooled to 
400°C at 25°C/hr. The molten charge creeps and forms single crystals and twins 
on the surfaces. The larger crystals formed in the space between the bottom of 
the crucible and the gold support sheet. 

A detailed account has appeared of the preparation of a 123 compound single 
crystal by the flux method (Zhoul). The flux mole ratio Ba0 2 : CuO was between 
1:3 and 2:5, and the nutrient Y 2 0 3 : Ba0 2 : CuO mole ratios were 0.5:2:3. A 
multistep temperature process was employed. Black single crystals of YBa* were 
found at the bottom and at the edge between the wall and the bottom of the 
crucibles. Platinum crucibles seemed to contaminate the samples so alumina 
crucibles were recommended. Crystals as large as 2 X 2 X 0.3 mm 3 were re- 
ported. A similar technique was used to produce single crystals of YBa* and 
DyBa* as large as 4 mm (Schnl). 



I 

I 
i 
l 



/er components 
or orthorhombic 
; a and b direc- 
lounced for the 
the b axis. The 



F. ALIGNED GRAINS 

Clearly high-quality single crystals are important for understanding the physics 
of superconductors. However, much useful information about anisotropics can 



68 PREPARATION AND CHARACTERIZATION OF SAMPLES 



be obtained by studying the properties of aligned grains, which are much easier 
to fabricate. 

A superconducting sample can be initially a collection of randomly oriented 
grains, but various techniques can be used to partially orient these grains so that 
the c axis lies preferentially in a particular direction. For example uniaxial com- 
pression tends to orient compacted grains, with compressed 90-^m particles ex- 
hibiting more alignment than compressed 10-jtm particles (Glowa). Epoxy- 
embedded grains have been aligned under the influence of an applied magnetic 
field and pressure (Arend). 

X-ray and magnetic measurements have been reported on aligned crystalline 
grains of YBa* (Farrl). Optical studies have also been made on aligned grains. 
The critical current density for samples cut parallel to the compression axis of 
such grains was nearly isotropic with respect to the direction of an applied mag- 
netic field, and it was a factor of 6 smaller than that for the samples cut perpen- 
dicular to this axis (Glowa). 



G. REACTIVITY 

The oxide superconductors are not inert materials, but rather they are sensitive 
to exposure to certain gases and to surface contact with particular materials. 
Great care must be exercised to avoid contamination from water vapor and car- 
bon dioxide in the atmosphere. In addition these materials are catalytic to oxy- 
genation reactions, and these factors result in the occurrence of various chemical 
and other interactions, especially at elevated temperatures. The granular and 
porous nature of the materials has an accelerating effect on such reactions 

Samples of YBaCuO may degrade in a matter of days when exposed to an 
ordinary ambient atmosphere; they react readily with liquid water, acids and 
electrolytes, and moderately with basic solutions. The reaction with water 
(Barns, Kishi, Yanzz) produces nonsuperconducting cuprates. The effects of ac- 
etone and other organics (McAnd) have been determined, and stable carboxyl 
groups have been found in the YBaCuO lattice (Parmi). 

Hydrogen enters the YBaCuO lattice at elevated temperatures and forms a 
solid solution. Low concentrations have very little effect and high concentrations 
degrade the superconducting properties (Berni, Reill, Yang3). The effects of ex- 
posure to oxygen at elevated temperature and oxidation have been discussed sev- 
eral places m this review (e.g., Blend, Engle, Tara3). 

The foregoing evidence for the reactivity of the oxide superconductors makes 
it necessary to consider methods of passivation or protecting them from long- 
term degradation. An epoxy coating was found to provide some protection 
(Barns). Coating the surface with metals can be deleterious since metals such as 
Fe (Gaozl, Hillz, Weave) and Ti (Meyel) react with the surface of LaSrCuO or 
YBaCuO. There is evidence for the passivation of the surface of LaSr* with eold 
(Meyer). 6 



:h easier 

Driented 
s so that 
ial corn- 
icles ex- 
Epoxy- 
nagnetic 

ystalline 
1 grains, 
l axis of 
ed mag- 
perpen- 



sensitive 
laterials. 
and car- 
c to oxy- 
chemical 
ular and 
tions. 
;ed to an 
:ids, and 
th water 
cts of ac- 
carboxyl 

I forms a 
ntrations 
:cts of ex- 
issed sev- 
ers makes 
om long- 
rotection 
Is such as 
SrCuO or 
with gold 



CHECKS ON QUALITY 69 

H. THERMOGRAVIMETRIC ANALYSIS 

Thermographic analysis (TGA) consists of monitoring the weight of a sam- 
ple dunng a heating or cooling cycle. For example, one might determine the 
oxygen content of a superconducting material by measuring its weight change in 
an oxid.z.ng (0 2 or air) or reducing (e.g., 4% H 2 in Ar) atmosphere. Typical 
procedures consist of heating or cooling at 20°C/min. The relative accuracy of 

he method is about 0.005 (Ongzl). Many workers (e.g., Beye3, Hauck, Huanl 
John4, Leez7, Maruc, Ohish, Ongzl, Tara7, Zhuzz) are now using TGA or dif- 
ferential thermal analysis (DTA) routinely during their sample preparation 
procedures. r 



I. CHECKS ON QUALITY 

After a sample has been prepared it is necessary to check its quality as a super- 
conductor Most investigators employ the four-probe resistivity check to deter- 
mme whether .t superconducts, and at what temperature it transforms to the 
superconducting state. A sharp, high T c transition is an indicator of a high-qual- 
ity sample. Another widely used quality control method is the determination of 
the magnet.c susceptibility of the specimen. Good quality is indicated by a 
sharp, high T c transition with both the flux exclusion and flux expulsion close to 
1/4tt. This is, in a sense, a more fundamental check on quality since the value 
of the susceptibility far below the transition temperature is a good indicator of 
the fraction of the sample that is superconducting (see Section III-D) 

In addition to its superconducting properties, it is also of interest to know the 
chem.cal composition and the structure of the specimen. The nominal composi- 
tion is deduced from the relative proportions of the various cations in the starting 
material. Chem.cal analysis and some more sophisticated techniques such as 
XPS, electrospectroscopic chemical analysis (ESCA), and an electron micro- 
probe that 1S favorable for low-atomic-weight elements are applicable here Most 
invest.gators only report the cation concentrations in the specimen. Oxygen con- 
tent is much more difficult to determine, but is important to know. Rutherford 
back-scattering experiments (Johnl, Wuzzl, Wuzz4) can provide oxygen con- 
tents, and metallography characterizes grain sizes. 

The structures of the oxide superconductors described in Chapter VI are eas- 
ily checked by the X-ray powder pattern method. Many articles list the lattice 
constants a, b, c of samples and mention whether they are tetragonal (a = b * c) 
or orthorhombic (a - b * c). Narrow lines and the absence of spurious signals 
or L!r^^ Sing Jt? aSe Samp,e - TyP ' Cal X ray di «™tion Powder patterns 
Z) f ( ° PreSented in RgS - V " 3 and V < respectively may be 

used to compare with patterns obtained from freshly prepared samples. 



M 

I 

I 

I 

I 

3 

5 



70 prepaThi .ON and characterization of sampiS 



r 



1L) 




ANGLE IDEG) 

Fig V-3. Room-temperature (upper curve) and 24-K (lower curve) X-ray diffraction 
powder patterns of (Lao. 92S Bao. 075 ) 2 Cu0 4 (Skelt). 




30 40 50 
2 0 (DEG) 

Fig. V-4 Room-temperature X-ray diffraction powder pattern of YBa 2 Cu 3 0 7 . (Provided 
by C. Almasan, J. Estrada, and W. E. Sharp.) 



RESISTIVITY MEASUREMENT 71 



J. RESISTIVITY MEASUREMENT 

A measurement of the resistance R(T) or resistivity p(D of a material versus the 
temperature is the principal technique employed to determine when a material 
becomes superconducting. The transition temperature manifests itself by a 
sharp drop in resistivity to zero. The simplest way to make this measurement is 
to apply a voltage across the sample and measure the current flow through it, but 
such a two-probe method (Baszy) is not very satisfactory, and is seldom used. 
Most resistivity determinations are made with the four-probe technique to be 
described below, although more sophisticated arrangements such as a six-probe 
method (Kirsc) can also be used. The fabrication of low-resistance contacts by 
silver glazing has been reported (Vand2). These researchers pointed out the im- 
portance of a low-contact resistance (p < 10 /xfi/mm 2 at 77 K) for making trans- 
port Jc measurements. 

The specimen resistance as a function of temperature is generally determined 
in a suitable cryostat by attaching leads or electrodes to it in the standard four- 
probe configuration. Two leads or probes carry a known constant current / into 
and out of the specimen, and the other two leads measure the potential drop 
between two equipotential surfaces resulting from the current flow. For super- 
conducting specimens the leads are often arranged in a linear configuration, 
with the contacts for the input current on the ends, and those for the measure- 
ment voltage near the center. 



BRIEF ATTACHMENT AG 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 14, 2005 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 

Commissioner for Patents 

P.O. Box 1450 

Alexandria, VA 22313-1450 



In response to the Office Action dated July 28, 2004, please consider the 



The attachments referred to herein A to Z and AA are in the FIRST 
SUPPLEMENTAL AMENDMENT. The Attachments AB to AG are attached herein. 

Please charge any fee necessary to enter this paper and any previous paper to 
deposit account 09-0468. 



THIRD SUPPLEMENTAL AMENDMENT 



Sir 



following: 




Dr. Daniel P. Morris, Esq. 
Reg. No. 32,053 
(914)945-3217 



IBM CORPORATION 
Intellectual Property Law Dept. 
P.O. Box 218 

Yorktown Heights, New York 10598 



ATTACHMENT AG 



:ONDUCTIVITY 



ERCONDUCTIVITY 



The New Superconductors 



Frank J. Owens 



Army Armament Research Engineering and Development Center 
Picatinny. New Jersey 

and Hunter College of the City University of New York 
New York New York 



and 

Charles P. Poole, Jr. 

Institute of Superconductivity 
University of South Carolina 
Columbia, South Carolina 



on order will bring delivery of 
d only upon actual shipment. 



Plenum Press • New York and London 



CHAPTER 8 



tftW HlGH-TEMPERAT 



Table 8. 1. Progress in Raising the Superconducting Transition Temperature T c 
Since the Discovery of Cuprates in 1986 



Ba,La5_ x Cu 5 0 9 


30-35 


1986 


(La 09 Ba 0 l ) 2 Cu4O 4 _ I (at I -GPa pressure)" 


52 


1986 


YBa2Cu 3 07_ x 


95 


1987 


Bi 2 Sr 2 Ca 2 Cu 3 O, 0 


110 


1988 


■n 2 Ba 2 Ca 2 Cu 3 O|0 


125 


1988 


Tl 2 Ba 2 Ca 2 Cu 3 O l0 (at 7-CPa pressure) 


131 


1993 


HgBa^CujOg^, 


133 


1993 


HgBa 2 Ca 2 CujO| 0 (at 30-GPa pressure) 


147 


1994 



"A pressure of 1 GPa is about 10.000 arm. 



While this increase in T c itself is an amazing result, a high-transition tempera- 
ture is not the only property required to make new compounds useful for applica- 
tions. For example if materials are to be used as wires in magnets, they must be 
malleable and ductile rather than brittle; in addition they must have high critical 
currents in large magnetic fields. Critical currents as high as those in niobium-tin 
have not yet been achieved in forms of the new materials that can easily be made 
into wires, although there are reports of comparable values in thin films on various 
substrates. 

The Holy Grail that is being sought is a transition temperature much above 
room temperature. We say much above because devices must operate significantly 
below the transition T c so that the critical current J c and critical magnetic field B c 
are sufficiently high. Very close to the transition temperature, the critical magnetic 
field is usually quite small, but we see from Figs. 3.4 and 3.5 that B c and J c 
continuously increase as the temperature is lowered below T c . We need an operating 
temperature far below the critical surface in Fig. 3.15 so that both B c and J c are 
sufficiently large for the desired application. 



8.3. LAYERED STRUCTURE OF THE CUPRATES 

All cuprate superconductors have the layered structure shown in Fig. 8.1: The 
flow of supercurrent takes place in conduction layers, and binding layers support 
and hold together the conduction layers. Conduction layers contain copper-oxide 
(Cu0 2 ) planes of the type shown in Fig. 8.2; each copper ion (Cu 2+ ) is surrounded 
by four oxygen ions (0 2 ~). These planes are held together in the structure by calcium 
(Ca 2+ ) ions located between them, as indicated in Fig. 8.3. An exception to this is 
the yttrium compound in which the intervening ions are the element yttrium (Y ) 
instead of calcium. These Cu0 2 planes are very close to being flat. In the normal 
state above T c , conduction electrons released by copper atoms move about on these 




CHAPTERS 



Transition Temperature T c 
n1986 



t, a high-transition tempera- 
npounds useful for applica- 
s in magnets, they must be 
ley must have high critical 
igh as those in niobium-tin 
als that can easily be made 
ues in thin films on various 

n temperature much above 
: must operate significantly 
d critical magnetic field B c 
•ature, the critical magnetic 
■A and 3.5 that B c and J c 
w T c . We need an operating 
so that both B c and J c are 



ES 

ure shown in Fig. 8.1 : The 
ind binding layers support 
yers contain copper-oxide 
:r ion (Cu 2+ ) is surrounded 
in the structure by calcium 
.3. An exception to this is 
the element yttrium (Y 3 *) 
> being flat. In the normal 
toms move about on these 



HEW HIGH-TEMPERATURE SUPERCONDUCTORS 



BINDING LAYERS 



CONDUCTION LAYERS WITH Cu0 2 



BINDING LAYERS 



CONDUCTION LAYERS with Cu0 2 



BINDING LAYERS 



CONDUCTION LAYERS WITH Cu0 2 



BINDING LAYERS 



Figure 8. 1 . Layering scheme of the cuprate superconductors. Figure 8.3 shows details of the conduction 
layers for different sequences of copper oxide planes, and Fig. 8.4 presents details of the binding layers 
for several cuprates. 



Figure 8.2. Arrangement of copper and oxygen atoms 
in a Cu0 2 plane of the conduction layer. 



• 


o 


• 


o 


• 


o 


• 


o 




o 




o 




o 


• 


o 


• 


o 


• 


o 


• 


o 




o 




o 




o 


• 


0 


• 


o 


• 


o 


• 



Conduction layer with one copper oxide plane 



Conduction layer with two copper oxide planes 



Conduction layer of yttrium compound with two copper oxide planes 



Conduction layer with three copper oxide planes 



Figure 8.3. Conduction layers of the various cuprate superconductors showing sequences of CuC^ and 
Ca (or Y) planes in the conduction layers of Fig. 8.1. 



Cu0 2 planes carrying electric current. In the superconducting state below T c , these 
same electrons form the Cooper pairs that carry the supercurrent in the planes. 

Each particular cuprate compound has its own specific binding layer consisting 
mainly of sublayers of metal oxides MO, where M is a metal atom; Fig. 8.4 gives 
the sequences of these sublayers for the principal cuprate compounds. These 
binding layers are sometimes called charge reservoir layers because they contain 



Figure 8.4. Sequence 
metal ions. The parent! 



CHAPTERS 

of randomly oriented grains. I n 
he current flow capability of 



La,. x) Sr,) 2 Cu0 4 are hole-type 
irium-copper oxide, (Nd u 
irons rather than holes. The 
have trivalent positive ions: 

(8.6) 

(8.7) 

itium (Sr 2 *) and cerium (Ce**), 



iCu0 4 ) 
l 2 Cu0 4 ) 



(8.9) 



one extra electron to form an 
:ontium subtracts one electron, 
iperconductor is hole-like. Any 
int both of these examples of 
lar, but not identical structures; 
:ause most experiments are not 



VCTURES 

ferred to as ceramics, they are 
irovskite refers to the particular 
;ral perovskite, calcium titanate 
:) parts of the lanthanum com- 
perovskite, with Cu present in 
lot shown in Fig. 8.9) positions, 
Similarities between these two 
jail La 2 Cu0 4 a perovskite-type 




^fVV HIGH-TEMPERATURE SUPERCONDUCTORS 
TITANIUM ~ ~ 

OXYGEN— _ 



figure 8.9. Sketch of the cubic unit cell of the mineral Perovskite, CaTi0 3 , showing titanium at the 
vertices and oxygen in the middle of the edges. Calcium, not shown, is in the center of the cube. 



In contrast the ceramic designation is not based on structural grounds but on 
the similarity of the cuprate-superconducting compound and ceramic manufactur- 
ing process. For example La-Sr-Cu-O is made by heating mixtures of lanthanum 
oxide, strontium carbonate, and copper oxide in air at 900-1000 °C for 20 hours. 
Proportions of atoms in the initial mixture should be the same as in the end product, 
and for the compound (Lao 9 Sro.,) 2 Cu0 4 the ratio La:Sr:Cu is 1.8:0.2: 1. Materials 
are usually ground to a fine mixture before heating; after heating in air, they are 
cooled, pressed into pellets, and reheated from 900- 1000 °C for several more hours. 

We see in Fig. 8.10 that the superconductor (La,. x Sr I ) 2 Cu0 4 has only one 
copper oxide plane in its conduction layer and each copper ion is surrounded by 




figure 8. 10. Atom positions in the tetragonal unit cell of the La 2 Cu0 4 compound. When so 
substituted for lanthanum in the superconducting compound (La,_ J( Sr J ) 2 Cu0 4 it replaces lanthanum in 
"Mne of the La sites. 



110 



CHAPTERS 



HEWHIGH-TE/v 



six neighboring oxygen ions; these form an 8-sided figure called an octahedron, as 
shown. The Cu0 6 complex of one copper and six oxygens is present in all cuprate 
superconductors that have a single Cu0 2 plane in their conduction layer. Figure 
8.1 1 shows atom arrangements in the mercury compound HgBa 2 Ca 2 CujO,o, which 
has three such planes in its conduction layer. In the upper and lower planes, copper 
ions have five neighboring oxygens forming a Cu0 5 group with the shape of a 
pyramid, as shown. The middle copper ions have only four nearby oxygens, forming 
what is called a square planar group Cu0 4 . If we consider removing the central 
copper oxide plane and one calcium layer from Fig. 8. 1 1 , we generate the two-plane 
structure in which all copper ions form CuO s pyramids. These structural details 
may somehow constitute important factors in determining why cuprates are such 
good superconductors. 




Figure 8.11. Atom positions in four unit cells of the superconducting compound HgBa 2 Ca 2 Cu 3 0s„ 
which has T c = 133 K. The copper ions of the upper Cu0 2 plane are hidden by the pyramids, and some 
partially occupied oxygen sites in the mercury Hg plane are not shown. 



BRIEF ATTACHMENT AH 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Group Art Unit: 1751 
Examiner: M. Kopec 



Date: March 1, 2004 



Docket: YO987-074BZ 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



FIFTH SUPPLEMENTAL AMENDMENT 



Sir: 



In response to the Office Action dated February 4, 2000: 



ATTACHMENT 16 




IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
J. Bednorz et al. 



Date: December 15, 1998 



Serial No. 08/303,561 



Group Art Unit: 1105 



Filed: September 9, 1994 



Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, AND METHODS FOR THEIR USE AND PREPARATION 



I, David B. Mitzi, being duly sworn, do hereby depose and state: 

That I received a B. S. E. degree in Electrical Engineering/Engineering Physics (1985) from 
Princeton University and a PhD. degree, in Applied Physics (1990) from Stanford University, 
California. 

That I have worked as a research staff member in Solid State Chemistry at the Thomas Watson 
Research Center of the International Business Machines Corporation in Yorktown Heights, NY 
from 1990 to the present. 

That I have worked in the fabrication of and characterization of high temperature superconductor 
and related materials from 1990 to the present. 

That I have reviewed the above-identified patent application and that I have reviewed the 
above-identified patent application and acknowledge that it represents the work of Bednorz and 



AFFIDAVIT UNDER 37 C.F.R. 1132 



Commissioner of Patents and Trademarks 
Washington, D. C. 20231 



Sir: 



YO987-074BY 



• 



Muller, which is generally recognized as the first discovery of superconductivity above 26°K and 
that subsequent developments in this field have been based on this work. 

That all the high temperature superconductors which have been developed based on the work of 
Bednorz and Muller behave in a similar manner, conduct current in a similar manner and have 
similar magnetic properties. 

That once a person of skill in the art knows of a specific transition metal oxide composition which 
is superconducting above 26°K, such a person of skill in the art, using the techniques described in 
the above-identified patent application, which includes all knows principles of ceramic fabrication 
known at the time the application was filed, can make the transition metal oxide compositions 
encomposed by the claims in the above identified application, without undue experimentation or 
without requiring ingenuity beyond that expected of a person of skill in the art. This is why the 
work of Bednorz and Muller was reproduced so quickly after their discovery and why so much 
additional work was done in this field within a short period of their discovery. 

The general principles of ceramic science referred to by Bednorz and Mueller in their patent 
application can be found in many books and articles published before their discovery. An 
exemplary list of books describing the general principles of ceramic fabrication are: 

1) Introduction to Ceramics, Kingery et al., Second Edition, John Wiley & Sons, 
1976, in particular pages 5-20, 269-319, 381-447 and 448-513, a copy of which is with 
the Affidavit of Thomas Shaw submitted December 15, 1998. 

2) Polar Dielectrics and Their Applications, Burfoot et al., University of California Press, 
1979, in particular pages 13-33, a copy of which is with the Affidavit of Thomas Shaw 
submitted December 15, 1998. 

3) Ceramic Processing Before Firing, Onoda et al., John Wiley & Sons, 1978, the entire 
book, a copy of which is with the Affidavit of Thomas Shaw submitted December 15, 

1998. 



YO987-074BY 



4) Structure, Properties and Preparation of Perovskite-Type Compounds, F.S. Glasso, 
Pergamon Press, 1969, in particular pages 159-186, a copy of which is with the Affidavit 
of Thomas Shaw submitted December 15, 1998. 



An exemplary list of articles applying their general principles of ceramic fabrication to the types of 
materials described in applicants' specification are (these references are cited on applicant's 1449 
form submitted August 5, 1987 and in PTO Form 892 in Paper # 20, Examiner's action dated 
August 8, 1990): 



1) Oxygen Defect K 2 NiF 4 - Type Oxides: The Compounds La 2 * Sr x CuO*^., Nguyen et 
al., Journal of Solid State Chemistry 39, 120-127^1981). 

2) The Oxygen Defect Perovskite BaLa, CUsOim, A Metallic Conductor , C. Michel et 
al., Mat. Res. Bull., Vol. 20, pp. 667-671, 1985. 

3) Oxygen intercalation in mixed valence copper oxides related to the perovskite, C. 
Michel et al:, Revue de Chemie minerale, p. 407, 1984. 

4) Thermal Behaviour of Compositions in the Systems x BaTi0 3 + (1-x) Ba(Lno. 5 B 0 5 ) 0 3 , 
V.S. Chincholkar et al. Therm. Anal. 6th, Vol. 2., p. 251-6, 1980. 

David B. Mitzi 




IWJItL Y. MUHHIS 

NOTARY PUBLIC, State of New York 
No. 4668676 

Qualified in Westchester County^^-^ 
Commission Expires March 16, \9Z&r 



YO987-074BY 



BRIEF ATTACHMENT Al 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 1 , 2004 



Docket: YO987-074BZ 



Group Art Unit: 1751 
Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



FIFTH SUPPLEMENTAL AMENDMENT 



Sir: 



In response to the Office Action dated February 4, 2000: 



ATTACHMENT 17 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 

^Z^° n0f : Date:Decemberl5,1998 

Serial No. 08/303,561 ^ 0U P ^ Unit: 1 105 

Filed: September 9, 1994 Examiner: M. Kopec 

For NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, AND METHODS FOR THEIR USE AND PREPARATION 

AFFIDAVIT U NT>FK 37 C.F.R. 1132 

Commissioner of Patents and Trademarks 
Washington, D. C. 20231 

Sir: 

I, Timothy Dinger, being duly sworn, do hereby depose and state: 

That I received a B. S. degree in Ceramic Engineering (1981) from New York State College of 
Ceramics, Alfred University, an M. S. degree (1983) and a PhD. degree (1986), both in Material 
Science from the University of California at Berkley. 

That I have worked as a research staff member in Material Science at the Thomas Watson 
Research Center of the International Business Machines Corporation in Yorktown Heights, NY 
from 1 986 to the present. 

That I have worked in the fabrication of and characterization of high temperature superconductor 
materials from 1987 to 1991. 

That I have reviewed the above-identified patent application and acknowledge that it represents 
the work of Bednorz and Muller, which is generally recognized as the first discovery of 



YO987-074BY 



superconductivity above 26°K and that subsequent developments in this field have been based on 
this work. 

That all the high temperature superconductors which have been developed based on the work of 
Bednorz and Muller behave in a similar way, conduct current in a similar manner and have similar 
magnetic properties. 

That once a person of skill in the art knows of a specific transition metal oxide composition which 
is superconducting above 26°K, such a person of skill in the art, using the techniques described in 
the above-identified patent application, which includes all knows principles of ceramic fabrication 
known at the time the application was filed, can make the transition metal oxide compositions 
encomposed by the claims in the above identified application, without undue experimentation or 
without requiring ingenuity beyond that expected of a person of skill in the art. This is why the 
work of Bednorz and Muller was reproduced so quickly after their discovery and why so much 
additional work was done in this field within a short period of their discovery. 

The general principles of ceramic science referred to by Bednorz and Mueller in their patent 
application can be found in many books and articles published before their discovery. An 
exemplary list of books describing the general principles of ceramic fabrication are: 

1) Introduction to Ceramics, Kingery et al., Second Edition, John Wiley & Sons, 
1976, in particular pages 5-20, 269-319, 381-447 and 448-513, a copy of which is with 
the Affidavit of Thomas Shaw submitted December 15, 1998 

2) Polar Dielectrics and Their Applications, Burfoot et al., University of California Press, 
1979, in particular pages 13-33, a copy of which is with the Affidavit of Thomas Shaw 
submitted December 15, 1998. 

3) Ceramic Processing Before Firing, Onoda et al., John Wiley & Sons, 1978, the entire 
book, a copy of which is with the Affidavit of Thomas Shaw submitted December 15, 
1998' 



YO987-074BY 



4) Structure, Properties and Preparation of Perovskite-Type Compounds, F.S. Glasso, 
Pergamon Press, 1969, in particular pages 159-186, a copy of which is with the Affidavit 
of Thomas Shaw submitted December 15, 1998. 



An exemplary list of articles applying their general principles of ceramic fabrication to the types of 
materials described in applicants' specification are (these references are cited on applicant's 1449 
form submitted August 5, 1987 and in PTO Form 892 in Paper # 20, Examiner's action dated 
August 8, 1990): 



1) Oxygen Defect KzNiE, - Type Oxides: The Compounds La 2 * SrxCuO^., Nguyen et 
al., Journal of Solid State Chemistry 39, 120-127 (1981). 

2) The Oxygen Defect Perovskite BaLa, Cu 5 -0, 3 4, A Metallic Conductor , C. Michel et al., 
Mat. Res. Bull., Vol. 20, pp. 667-671, 1985. 

3) Oxygen intercalation in mixed valence copper oxides related to the perovskite, C. 
Michel et al., Revue de Chemie minerale, p. 407, 1984. 

4) Thermal Behaviour of Compositions in the Systems x BaTi0 3 + (1-x) Ba(Lno, 5 B 0 5 ) 0 3 , 
V.S. Chincholkar et al. Therm. Anal. 6th, Vol. 2., p. 251-6, 1980. 



By: 




Timothy Dinger 



Sworn to before me this 



/{pte* day of j)(b&n(AjH^ 




Notary Public 




YO987-074BY 



BRIEF ATTACHMENT AK 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Group Art Unit: 1751 
Examiner: M. Kopec 



Date: March 1 , 2004 



Docket: YO987-074BZ 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



FIFTH SUPPLEMENTAL AMENDMENT 



Sir: 



In response to the Office Action dated February 4, 2000: 



ATTACHMENT 19 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



Applicants: J. Bednorz et al. 



Date: December 15, 1998 



Serial No. 08/303,561 



Group Art Unit: 1105 



Filed: September 9, 1994 



Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH 
TRANSITION TEMPERATURE, AND METHODS FOR THEIR 
USE AND PREPARATION 



The Commissioner of Patents and Trademarks 
Washington, D.C. 20231 



Sir: 

I, Thomas M. Shaw, being duly sworn, do hereby depose and state: 

I received a B.S. degree in Metallurgy from the University of Liverpool, Liverpool, 
England and a M.S. and PhD. degree in Materials Science (1981) from the University 
of California, Berkeley. 

I have worked as a postdoctoral researcher in the Material Science Department of 
Cornell University from 1981-1982. I worked at Rockwell International Science Center 
in Thousand Oaks, California from 1982-1984 as a ceramic scientist. I have worked as 
a research staff member in Ceramics Science at the Thomas J. Watson Research 

YO987-074BY 1 



AFFIDAVIT UNDER 37 CFR 1.132 



Center of the International Business Machines Corporation in Yorktown Heights, N.Y. 
from 1 984 to the present. 

I have worked in the fabrication of and characterization of ceramic materials of various 
types, including superconductors and related materials from 1 984 to the present. 

Attached is a resume of my publications. I have reviewed the above-identified patent 
application and acknowledge that it represents the work of Bednorz and Mueller, which 
is generally recognized as the first discovery of superconductivity above 26°K and that 
subsequent developments in this field have been based on this work. 

That all the high temperature superconductors which have been developed based on 
the work of Bednorz and Mueller behave in a similar manner, conduct current in a 
similar manner and have similar magnetic properties. 

That once a person of skill in the art knows of a specific transition metal oxide 
composition which is superconducting above 26°K, such a person of skill in the art, 
using the techniques described in the above-identified patent application, which 
includes all known principles of ceramic fabrication known at the time the application 
was filed, can make the transition metal oxide compositions encompassed by the 
claims in the above-identified application, without undue experimentation or without 
requiring ingenuity beyond that expected of a person of skill in the art. This is why the 



YO987-074BY 



2 



work of Bednorz and Mueller was reproduced so quickly after their discovery and why 
so much additional work was done in this field within a short period of their discovery. 

The general principles of ceramic science referred to by Bednorz and Mueller in their 
patent application can be found in many books and articles published before their 
discovery. An exemplary list of books describing the general principles of ceramic 
fabrication are: 

1) Introduction to Ceramics, Kingery et al., Second Edition, John Wiley & Sons, 
1976, in particular pages 5-20, 269-319, 381-447 and 448-513, a copy of 
which is attached herewith. 

2) Polar Dielectrics and Their Applications, Burfoot et al., University of California 
Press, 1979, in particular pages 13-33, a copy of which is attached herewith. 

3) Ceramic Processing Before Firing, Onoda et al., John Wiley & Sons, 1978, 
the entire book, a copy of which is attached herewith. 

4) Structure, Properties and Preparation of Perovskite-Type Compounds, 
F.S. Glasso, Pergamon Press, 1969, in particular pages 159-186, a copy of 
which is attached herewith. 

An exemplary list of articles applying their general principles of ceramic fabrication to 
the types of materials described in applicants' specification are (these references are 
cited on applicant's 1449 form submitted August 5, 1987 and in PTO Form 892 in 
Paper # 20, Examiner's action dated August 8, 1 990): 

1) Oxygen Defect K 2 NiF 4 - Type Oxides: The Compounds La 2 . x S^CuO^+s, Nguyen et 
al., Journal of Solid State Chemistry 39, 120-127 (1981). 

2) The Oxygen Defect Perovskite BaLa 4 Cu 5 -0 13 . 4l A Metallic Conductor , C. Michel et 
al., Mat. Res. Bull., Vol. 20, pp. 667-671, 1985. 



YO987-074BY 



3 



3) Oxygen intercalation in mixed valence copper oxides related to the perovskite, C. 
Michel et al., Revue de Chemie minerale, p. 407, 1984. 

4) Thermal Behaviour of Compositions in the Systems x BaTi0 3 + (1-x) Ba(Ln 05 B 0 s) 0 3 

V.S. Chincholkar et al. Therm. Anal. 6th, Vol. 2., p. 251-6, 1980. 



Thomas M. Shaw 




SANDRA M. EMMA 
Notary Public. State of New York 

NO.01PO493529O 
Qualified in Westchester County 
Commission Expires July S. J.vvt. 



YO987-074BY 



4 



BRIEF ATTACHMENT AJ 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Group Art Unit: 1751 
Examiner: M. Kopec 



Docket: YO987-074BZ 



Date: March 1 , 2004 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 2231 3-1450 



FIFTH SUPPLEMENTAL AMENDMENT 



Sir: 



In response to the Office Action dated February 4, 2000: 



ATTACHMENT 18 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
J. Bednorz et al. 



Date: December 15, 1998 



Serial No. 08/303,561 



Group Art Unit: 1105 



Filed: September 9, 1994 



Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, AND METHODS FOR THEIR USE AND PREPARATION 



I, Chang C. Tsuei, being duly sworn, do hereby depose and state: 

That I received a B. S. degree in Mechanical Engineering from National Taiwan University (1960) 
and M. S. and PhD. degrees, in Material Science (1963, 1966) respectively from California 
Institute of Technology. 

That I have worked as a research staff member and manager in the physics of superconducting, 
amorphous and structured materials at the Thomas Watson Research Center of the International 
Business Machines Corporation in Yorktown Heights, New York from 1973 to the present. (See 
attached Exhibit A for other professional employment history.) 

That I have worked in the fabrication of and characterization of high temperature superconductor 
and related materials from 1973 to the present. 



AFFIDAVIT UNDER 37 C F R. 1.132 



Commissioner of Patents and Trademarks 
Washington, D. C. 20231 



Sir: 



That I have reviewed the above-identified patent application and acknowledge that it represents 
the work of Bednorz and Muller, which is generally recognized as the first discovery of 
YO987-074BY 



superconductivity above 26°K and that subsequent developments in this field have been based on 
this work. 

That all the high temperature superconductors which have been developed based on the work of 
Bednorz and Muller behave in a similar manner, conduct current in a similar manner and have 
similar magnetic properties. 

That once a person of skill in the art knows of a specific transition metal oxide composition which 
is superconducting above 26°K, such a person of skill in the art, using the techniques described in 
the above-identified patent application, which includes all knows principles of ceramic fabrication 
known at the time the application was filed, can make the transition metal oxide compositions 
encomposed by the claims in the above identified application, without undue experimentation or 
without requiring ingenuity beyond that expected of a person of skill in the art. This is why the 
work of Bednorz and Muller was reproduced so quickly after their discovery and why so much 
additional work was done in this field within a short period of their discovery. 

The general principles of ceramic science referred to by Bednorz and Mueller in their patent 
application can be found in many books and articles published before their discovery. An 
exemplary list of books describing the general principles of ceramic fabrication are: 

1) Introduction to Ceramics, Kingery et al., Second Edition, John Wiley & Sons, 
1976, in particular pages 5-20, 269-319, 381-447 and 448-513, a copy of which is with 
the Affidavit of Thomas Shaw submitted December 15, 1998. 

2) Polar Dielectrics and Their Applications, Burfoot et al., University of California Press, 
1979, in particular pages 13-33, a copy of which is with the Affidavit of Thomas Shaw 
submitted December 15, 1998. 

3) Ceramic Processing Before Firing, Onoda et al., John Wiley & Sons, 1978, the entire 
book, a copy of which is with the Affidavit of Thomas Shaw submitted December 15, 
1998. 



YO987-074BY 



4) Structure, Properties and Preparation of Perovskite-Type Compounds, F.S. Glasso, 
Pergamon Press, 1969, in particular pages 159-186, a copy of which is with the Affidavit 
of Thomas Shaw submitted December 15, 1998. 



An exemplary list of articles applying their general principles of ceramic fabrication to the types of 
materials described in applicants' specification are (these references are cited on applicant's 1449 
form submitted August 5, 1987 and in PTO Form 892 in Paper # 20, Examiner's action dated 
August 8, 1990): 



1) Oxygen Defect K 2 NiF 4 - Type Oxides: The Compounds La 2 . x Sr,Cu04«of, Nguyen et 
al., Journal of Solid State Chemistry 39, 120-127 (1981). 

2) The Oxygen Defect Perovskite BaLa* Cu 5 -0, 3 .4, A Metallic Conductor , C. Michel et al., 
Mat. Res. Bull., Vol. 20, pp. 667-671, 1985. 

3) Oxygen intercalation in mixed valence copper oxides related to the perovskite, C. 
Michel et al., Revue de Chemie minerale, p. 407, 1984. 

4) Thermal Behaviour of Compositions in the Systems x BaTi0 3 + (1-x) Ba(Lno. 5 B 0 5 ) 
0 3 ,V.S. Chincholkar et al. Therm. Anal. 6th, Vol. 2., p. 251-6, 1980. 



Bv: a — ^ c 1 — 

Chang C. Tsuei 



Sworn to before me this _ 



this j&fe day of OnMndhVU _B±^ 



Notary Public 

SANDRA M. EMMA 
Notary Public. State of New York 

No.01PO4935290 
Qualified in Westchester Co 
Commission Expires July 5, c 



YO987-074BY 



CHANG C. TSUEI 
Education 

California Institute of Technology, M.S. (1963), Ph.D. (1966) 
National Taiwan University, B.S. (1960) 

Professional Employment 

1993 - present - Research Staff Member 
1983 - 1993 - Manager, Physics of Structured Materials 
1979 - 1983 - Manager, Physics of Amorphous Materials 
1974 - 1975 - Acting Manager, Superconductivity 
1973 - 1979 - Research StaffMember 

Harvard University. 1980 (Summer) 

Visiting Scholar in Applied Physics 

Stanford University: 1982 (Sept.) - 1983 (April) 
Visiting Scholar in Applied Physics 

California Institute of Technology 

1972 - 1973 - Senior Research Associate in Applied Physics 
1969 - 1972 - Senior Research Fellow in Materials Science 
1966 - 1969 - Research Fellow in Materials Science 



Exhibit A 



YO987-074BY 



BRIEF ATTACHMENT AK 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Group Art Unit: 1751 
Examiner: M. Kopec 



Date: March 1 , 2004 



Docket: YO987-074BZ 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



FIFTH SUPPLEMENTAL AMENDMENT 



Sir: 



In response to the Office Action dated February 4, 2000: 



ATTACHMENT 19 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



Applicants: J. Bednorz et al. 



Date: December 1 5, 1 998 



Serial No. 08/303,561 



Group Art Unit: 1105 



Filed: September 9, 1 994 



Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH 
TRANSITION TEMPERATURE, AND METHODS FOR THEIR 
USE AND PREPARATION 



The Commissioner of Patents and Trademarks 
Washington, D.C. 20231 



Sir: 

I, Thomas M. Shaw, being duly sworn, do hereby depose and state: 

I received a B.S. degree in Metallurgy from the University of Liverpool, Liverpool, 
England and a M.S. and PhD. degree in Materials Science (1981) from the University 
of California, Berkeley. 

I have worked as a postdoctoral researcher in the Material Science Department of 
Cornell University from 1981-1982. I worked at Rockwell International Science Center 
in Thousand Oaks, California from 1982-1984 as a ceramic scientist. I have worked as 
a research staff member in Ceramics Science at the Thomas J. Watson Research 



AFFIDAVIT UNDER 37 CFR 1.132 



YO987-074BY 



Center of the International Business Machines Corporation in Yorktown Heights, N.Y. 
from 1 984 to the present. 

I have worked in the fabrication of and characterization of ceramic materials of various 
types, including superconductors and related materials from 1984 to the present. 

Attached is a resume of my publications. I have reviewed the above-identified patent 
application and acknowledge that it represents the work of Bednorz and Mueller, which 
is generally recognized as the first discovery of superconductivity above 26°K and that 
subsequent developments in this field have been based on this work. 

That all the high temperature superconductors which have been developed based on 
the work of Bednorz and Mueller behave in a similar manner, conduct current in a 
similar manner and have similar magnetic properties. 

That once a person of skill in the art knows of a specific transition metal oxide 
composition which is superconducting above 26°K, such a person of skill in the art, 
using the techniques described in the above-identified patent application, which 
includes all known principles of ceramic fabrication known at the time the application 
was filed, can make the transition metal oxide compositions encompassed by the 
claims in the above-identified application, without undue experimentation or without 
requiring ingenuity beyond that expected of a person of skill in the art. This is why the 



YO987-074BY 



2 



work of Bednorz and Mueller was reproduced so quickly after their discovery and why 
so much additional work was done in this field within a short period of their discovery. 

The general principles of ceramic science referred to by Bednorz and Mueller in their 
patent application can be found in many books and articles published before their 
discovery. An exemplary list of books describing the general principles of ceramic 
fabrication are: 

1) Introduction to Ceramics, Kingery et al., Second Edition, John Wiley & Sons, 
1976, in particular pages 5-20, 269-319, 381-447 and 448-513, a copy of 
which is attached herewith. 

2) Polar Dielectrics and Their Applications, Burfoot et al., University of California 
Press, 1979, in particular pages 13-33, a copy of which is attached herewith. 

3) Ceramic Processing Before Firing, Onoda et al., John Wiley & Sons, 1978, 
the entire book, a copy of which is attached herewith. 

4) Structure, Properties and Preparation of Perovskite-Type Compounds, 
F.S. Glasso, Pergamon Press, 1969, in particular pages 159-186, a copy of 
which is attached herewith. 

An exemplary list of articles applying their general principles of ceramic fabrication to 
the types of materials described in applicants' specification are (these references are 
cited on applicant's 1449 form submitted August 5, 1987 and in PTO Form 892 in 
Paper # 20, Examiner's action dated August 8, 1 990): 

1) Oxygen Defect K 2 NiF 4 - Type Oxides: The Compounds La 2 . x Sr x Cu0 4 .x/2+6, Nguyen et 
al., Journal of Solid State Chemistry 39, 120-127 (1981). 

2) The Oxygen Defect Perovskite BaLa 4 Cus-0,3.4, A Metallic Conductor , C. Michel et 
al., Mat. Res. Bull., Vol. 20, pp. 667-671, 1985. 



YO987-074BY 



3 



3) Oxygen intercalation in mixed valence copper oxides related to the perovskite C 
Michel et al., Revue de Chemie minerale, p. 407, 1984. 

4) Thermal Behaviour of Compositions in the Systems x BaTi0 3 + (1-x) Ba(Ln 05 B 05 ) 0 3 

V.S. Chincholkar et al. Therm. Anal. 6th, Vol. 2., p. 251-6, 1980. 



Notary Public 



SANDRA M. EMMA 
Notary Public. State of New York 

No. 01PO4935290 
Qualified in Westchester County 
Commission Expires July 5.<i? ffl/l '. 




Thomas M. Shaw 



Sworn to before me this 




19?£ 




YO987-074BY 



4 



BRIEF ATTACHMENT AL 



IN THE UNITED STATES PATENT AND TRADEMARK OFFICE 



In re Patent Application of 
Applicants: Bednorz et al. 
Serial No.: 08/479,810 
Filed: June 7, 1995 



Date: March 1,2004 
Docket: YO987-074BZ 
Group Art Unit: 1751 
Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH TRANSITION 
TEMPERATURE, METHODS FOR THEIR USE AND PREPARATION 



Commissioner for Patents 
P.O. Box 1450 
Alexandria, VA 22313-1450 



FIFTH SUPPLEMENTAL AMENDMENT 



Sir: 



In response to the Office Action dated February 4, 2000: 



ATTACHMENT 20 




IN THE UNITED STATES PATENT AND TRADEMARK OFFICF 



Applicants: J. Bednorz et al. 



Date. December 18, 1998 



Serial No. 08/303,561 



Group Art Unit: 1105 



Filed: September 9, 1994 



Examiner: M. Kopec 



For: NEW SUPERCONDUCTIVE COMPOUNDS HAVING HIGH 
TRANSITION TEMPERATURE, AND METHODS FOR THEIR 
USE AND PREPARATION 



The Commissioner of Patents and Trademarks 
Washington, D C. 20231 



I, Peter R. Duncombe, being duly sworn, do hereby depose and state: 

I received a B.A. degree in Chemistry from the State University of New York at New 
Paltz, New Paltz, N.Y. and a M.S. degree in Chemical Engineering (1983) from the 
State University of New York at Buffalo, Buffalo, N.Y. 

I have worked as a graduate research assistant in the Chemical Engineering 
Department of SUNY at Buffalo from 1980-1983. I have worked as a chemical 
engineer in Ceramics Science at the Thomas J. Watson Research Center of the 
International Business Machines Corporation in Yorktown Heights, N.Y. from 1984 to 
the present. 

YO987-074BY 1 



AFFIDAVIT UNDER 37 CFR 1.132 



Sir: 



I have worked in the fabrication of and characterization of ceramic materials of various 
types, including superconductors and related materials from 1984 to the present. 

Attached is a resume of my publications (Attachment A). 

I have reviewed the above-identified patent application and acknowledge that it 
represents the work of Bednorz and Mueller, which is generally recognized as the first 
discovery of superconductivity above 26°K and that subsequent developments in this 
field have been based on this work. 

That all the high temperature superconductors which have been developed based on 
the work of Bednorz and Mueller behave in a similar manner, conduct current in a 
similar manner and have similar magnetic properties. 

That once a person of skill in the art knows of a specific transition metal oxide 
composition which is superconducting above 26°K, such a person of skill in the art, 
using the techniques described in the above-identified patent application, which 
includes all known principles of ceramic fabrication known at the time the application 
was filed, can make the transition metal oxide compositions encompassed by the 
claims in the above-identified application, without undue experimentation or without 
requiring ingenuity beyond that expected of a person of skill in the art. This is why the 



YO987-074BY 



2 



work of Bednorz and Mueller was reproduced so quickly after their discovery and why 
so much additional work was done in this field within a short period of their discovery. 

The general principles of ceramic science referred to by Bednorz and Mueller in their 
patent application can be found in many books and articles published before their 
discovery. An exemplary list of books describing the general principles of ceramic 
fabrication are: 

1) Introduction to Ceramics, Kingery et al., Second Edition, John Wiley & Sons, 
1976, in particular pages 5-20, 269-319, 381-447 and 448-513, a copy of 
which is attached herewith. 

2) Polar Dielectrics and Their Applications, Burfoot et al., University of California 
Press, 1979, in particular pages 13-33, a copy of which is attached herewith. 

3) Ceramic Processing Before Firing, Onoda et al., John Wiley & Sons, 1978, 
the entire book, a copy of which is attached herewith. 

4) Structure, Properties and Preparation of Perovskite-Type Compounds, 
F.S. Glasso, Pergamon Press, 1969, in particular pages 159-181, a copy of 
which is attached herewith. 

An exemplary list of articles applying their general principles of ceramic fabrication to 
the types of materials described in applicants' specification are (these references are 
cited on applicant's 1449 form submitted August 5, 1987 and in PTO Form 892 in 
Paper # 20, Examiner's action dated August 8, 1 990): 

1) Oxygen Defect KzNiF* - Type Oxides: The Compounds La 2 . x Sr x Cu0 4 .^ +6 , Nguyen et 
al., Journal of Solid State Chemistry 39, 120-127 (1981). 

2) The Oxygen Defect Perovskite BaLa< Cu 5 -0 13 .4, A Metallic Conductor , C. Michel et 
al., Mat. Res. Bull., Vol. 20, pp. 667-671, 1985. 



YO987-074BY 



3 



3) Oxygen intercalation in mixed valence copper oxides related to the perovskite, C. 
Michel et al., Revue de Chemie minerale, p. 407, 1984. 

4) Thermal Behaviour of Compositions in the Systems x BaTi0 3 + (1-x) Ba(Lno 5 B 05 ) 0 3 

VS. Chincholkar et al. Therm. Anal. 6th, Vol. 2., p. 251-6, 1980. 

I have recorded research notes relating to superconductor oxide (perovskite) 
compounds in technical notebook IV with entries from November 12, 1987 to June 14, 
1988 and in technical notebook V with entries continuing from June 7, 1 988 to May 2, 
1989. Complete copies of each of these notebooks are attached - Attachment B - Book 
IV and Attachment C - Book V. Below is a listing of some of the compounds I prepared 
and recorded in these notebooks according to the teaching as described in the 
Bednorz and Mueller patent application using the general principles of ceramic science 
as described in the books and articles listed above. 

In Book IV, YiBa 2 Cu 3 O x batch C1 pellet pressing, sintering notes and powder 
processing specifications start on page 2 and continue intermittently to pg. 40 (pg. 13 
has superconductive susceptibility curves for pellet 9). Batch C2 YiBa 2 Cu 3 0 3 detailed 
from pages 14 to 47. 

In Book V green phase (Y 2 BaCuO x ) microstructural photomicrographs are logged on 
pages 15-17 with notes continuing to pg. 19. The perovskite superconductor BiSrCaCu 
oxide (Bi 2 .i5Sr 1 .68Cat.7Cu208 +5 ) and related perovskites Ca (2 . x) Sr x CuOx and Bi 2 Sr 2 CuO x 
synthesis notations start and continue through pg. 61 with microstructural 
photomicrographs. 



YO987-074BY 



4 




A series of YiBaaCifeO* stoichiometric perturbations to study compositional effects on 
2nd phase or grain boundary phases and their effect on conductivity (resistivity), 
sintering behavior etc., continue until the end of the book notes on the page dated May 
2, 1989 (page not numbered). These are typical perovskite synthetic procedures, 
microstructural photomicrographs, powder processing methods, characteristic 
susceptibility curve(s), sintering behavior and the like. Additional notes may be 
available in later notebooks. 



The undersigned affiant swears further that all statements made herein of his own 
knowledge are true and that all statements made on information and belief are believed 
to be true; and further that these statements were made with the knowledge that willful 
false statements and the like so made are punishable by fine or imprisonment, or both, 
under Section 1001 of Title 18 of the United States Code and that such willful false 
statements may jeopardize the validity of the application or patent issuing thereon. 



By: — ^-»^ 



Peter R. Duncombe 



Swornlo before me this 




j£^day of l)fbdQ wJaJA, 



Notary Public 



SANDRA M. EMMA 
Notary Public. State of New York 

No.01PO4935290 
Qualified in Westchester County 
Commission Expires July R c*Ovt> 



YO987-074BY 



5 




ATTACHMENT A 



1. Compensation doping of BaO. /Sr0.3TiO3 thin films 
Copel, M Baniecki, JD Duncombe, PR Kotecki, D 
Laibowitz, R Neumayer, DA Shaw, TM 

APPLIED PHYSICS LETTERS V73 NI3 SEP 28 1998 PI 832- 1834 

2. Method for Forming Noble Metal Oxides and Structures Formed Thereof June 
Duncombe, P. R. Hummel, J. P. Laibowitz, R. B. 

Neumayer, D. A. Saenger, K. L. Schrott, A. G. 
RC 98 A 41575 



3. Growth of Bismuth Titanate Films By Chemical Vapor Deposition and Chemical Solution 
Deposition. March 1 998. RC-2 1 1 24 """ion 

Neumayer, D. A. Duncombe, P. R. Laibowitz, R. B. 
Shaw, T. Purtell, R. Grill, A. 

4. Dielectric relaxation of Ba0.7Sr0.3TiO3 thin films from 1 mHz to 20 GHz Baniecki JD 
Laibowitz, RB Shaw,TM Duncombe, PR 

Neumayer, DA Kotecki, DE Shen, H Ma, QY 
APPLIED PHYSICS LETTERS V72 N4 JAN 26 1998 P498-500 

5. Contrasting magnetic and structural properties of two La manganites with the same 
doping levels 

McGuire, T.R. Duncombe, P.R. Gong, G.Q. Gupta, A. Li, X.W. Pickart S J Crow M L 
J. Appl. Phys. (USA) Vol.83, No. 1 1 1 June 1998 P7076-8 ' ' 

6. Effects of Annealing Conditions on Charge Loss Mechanisms in MOCVD (Ba0.7 SrO 3)Ti03 
Thin Film Capacitors. ' 
Baniecki, ID,, Laibowitz, RB Shaw, TM Duncombe, PR Saenger KL Cabral C 
Kotecki, DE , Shen, H , Lian, J., Ma, QY 

7. Low Operating Voltage and High Mobility Field Effect Transistors Comproising Pentacene 
and Relatively High Dielectric Constant Insulators RC2 1 233(94806) 7/1 7/98 
Dimitrakopoulos, CD Purushothaman S , Kymissis J. Callegari A. , Neumayer DA 
Duncombe PR, Laibowitz RB, Shaw JM ' 

8. Maximum Magnetorsistance in Granular Manganite/Insulator System close to Percolation 
Threshold PACS 10/06/98 

DK Petrov, L Krusin-Elbaum, JZ Sun, C Feild, & PR Duncombe 

9. Magnetorsistance and Hall Effect of Chromium Dioxide Epitaxial Thin Films 
X.W. Li, A. Gupta, T.R. McGuire, P.R. Duncombe, Gang Xiao 

10. Progress Report on High-k dielectric material: amorphous BST from solgel (09/98) 

P. Andry, D. Neumayer, P. Duncombe, C. Dimitrakopoulos, F. Libsch, A. Grill, R. Wisnieff 



I l n f oWt i from The IBM Total Information fl 



Personal Inventor History 



Name:Duncombe, P.R. Serial : 155139 Loc:RES YORKTOWN 

Patent Pts:36 TDB Pts : 1 Total Pts:37 Plateau Lvl : 3 

Plateau Date: 10/24/98 File Update: 11/02/98 

Awards Due: None 

Title: NOVEL METAL ALKOXYALKOXIDECARBOXYLATES AND USE TO FORM FILMS 

06/17/98 Opene d as Disci Y O89802 31 Status: Filed 

06/22/98"Discl Review " ~ — Action: File ' 

(Jj 09/04/98 Filed as Docket Y0998254 in US Rating: 2 Pts: 3 

Co- inventors : Neumayer, D.A. 

Title: SELECTIVE GROWTH OF FERROMAGNETIC FILMS FOR MAGNETIC MEMORY, STORAGE - BASED 
DEVICES , AND OTHER DEVICES 

06/17/98 Opened as Disci YO8980225 Status: Filed _ 

©06/29/98 Disci Review Action: File " ~ 

10/15/98 Filed as Docket Y0998268 in US Rating: 2 Pts: 3 

Co-inventors: Guha, S. • Gupta, A. Bojarczuk, N.A. Karasinski, J.M. 

Title: BEOL DECOUPLING CAPACITOR MATERIALS 

01/28/98 Opened as Disci Y089 80024 in US Status : Opened 

. 06/24/98 Disci Review Action: File 

Co-inventors: Rosenberg, R. Ning, T.H. Shaw, T.M. Edelstein, D.C. Neumayer, D.A 

Laibowitz, R.B. ' & 

10/01/97 Opened as Disci YO8970512 in US Status : Opened 

09/16/98 Disci Review Action- File 

2) \Q/^m^ : ^ ha &^LCt e ^) ° A - Laibowitz < R B -' 

Title: CAPACITORS WITH AMORPHOUS DIELECTRICS AND IMPROVED DIELECTRIC PROPERTIES MADE 
USING SILICON SURFACES AS ELECTRODES 

06/06/97 Opened as Disci YO8970261 in US Status:Opened 
Co-inventors: Shaw, T.M. Neumayer, D.A. Laibowitz, R.B. 

Title: FABRICATION OF THIN FILM FIELD EFFECT TRANSISTOR COMPRISING AN ORGANIC 
SEMICONDUCTOR AND CHEMICAL SOLUTION DEPOSITED METAL OXIDE 
03/25/97 Opened as Disci YO8970113 Status: Filed 

03/25/97 Disci Review Action: File * 

03/25/97 Filed as Docket YO997083 in US Rating: 2 Pts-3 

^S. .03/24/98 Filed as Docket YO997083 in JA Rating: 2 

\Q 03/16/98 Filed as Docket YO997083 in TA Rating: 2 

"03/12/98 Filed as Docket YO997083 in KO ' Rating: 2 

04/24/98 Last Office Action 

Co-inventors: Purushothaman, S. Dimitrakopoulos, CD. Furman, B.K. Neumayer, D.A. 
Laibowitz, R.B. 

Title: NOVEL ALKOXYALKOXIDES AND USE TO FORM FILMS 
10/30/96 Opened as Disci YO8960411 Status: Filed 

03/10/97 Disci Review Action: File 

(5j 01/30/98 Filed as Docket YO997069 in US Rating: 2 Pts:3 

Co-inventors : Neumayer, D.A. — 



I of 3 



1 1/3/98 2:40 PM 



Title: THIN- FILM FIELD -EFFECT TRANSISTOR WITH ORGANIC SEMICONDUCTOR REOUIRTmo t™, 
OPERATING VOLTAGES V ANCj L0W 

09/11/96 Opened as Disci YO8960358 Status: Filed 

03/04/97 Disci Review Action: File 

03/25/97 Filed as Docket YO997057 in US Rating: 2 Pts-3 

03/12/98 Filed as Docket YO997057 in KO. Rating: 2 

04/10/98 Last Office Action 

Co-inventors: Purushothaman, S. Dimitrakopoulos, CD. Furman, B.K. Neumaver n a 
Laibowitz, R.B. ' ' 

^ RANDOM ACCESS IELECTRIC C ° NSTANT ' BARIUM LANTHANUM TITANATE THIN FILM CAPACITORS FOR 
06/20/96 Opened as Disci YO8960255 in US Status: Opened 

Co-inventors: Gupta, A. Shaw, T.M. Laibowitz, R.B. 

Title: METHOD FOR FORMING NOBLE METAL OXIDES AND STRUCTURES FORMED THEREOF 
10/30/95 Opened as Disci YO8950450 Status:Filed 
11/12/96 Disci Review Action: File 

11/05/97 Filed as Docket Y0996239 in US Rating: 2 Pts-3 

\ 10/20/98 Filed as Docket Y0996239 in JA Rating: 2 

' 07/30/98 Filed as Docket Y099 6239 in TA Rating: 2 

Co-inventors: Schrott, A.G. Saenger, K.L. Hummel, J. p. Neumayer, D.A. 
Laibowitz, R.B. 

Title: PEROXIDE ETCHANT PROCESS FOR PEROVSKITE-TYPE OXIDES 
10/23/95 Opened as Disci YO8950434 Status: Filed 

08/08/97 Disci Review Action: File 

) 04/08/98 Filed as Docket Y0997256 in US Rating: 2 Pts:3 

Co-inventors: Rosenberg, R. Cooper, E.I. Laibowitz, R.B. 

Title: RF TRANSPONDER FOR METALLIC SURFACES 

08/02/95 Opened as Disci YO8950329 in US Status : Opened 

Co-inventors: Af zali -ardakani , A. Feild, C.A. Duan, D.W. Brady, M.J. 
Moskowitz, P. A. 

Title: METHOD FOR CLEANING THE SURFACE OF A DIELETRIC 

09/06/95 Opened as Disci FI8950292 Status: Filed 

09/06/95 Sent to Evaluator 

02/05/96 Evaluated Action : Search 

04/19/96 Disci Review Action: File 

12/06/96 Filed as Docket FI996047 in US Rating: 2 Pts-3 

11/29/97 Filed as Docket FI996047 in KO Rating: 2 

05/26/97 Filed as Docket FI996047 in TA Rating: 2 

06/11/98 Last Office Action 

Co-inventors: Kotecki. D.E. Wildman, H.S. Yu, C. Natzle, W. Laibowitz, R.B. 

Title: NANO PHASE FABRICATION OF COPPER - GLASS CERAMIC COMPOSITE VIAS IN CORDIERITE 
SUBSTRATES 

10/05/92 Opened as Disci YO8920907 in US Status: Published 

10/08/92 Sent to Evaluator 

12/17/92 Disci Review Action: Publish 

01/06/93 Mailed to Tech Disci Bulletin 09/02/93 Published Pts-1 

Co-inventors: Kang, S.K. Shaw, T.M. Brady, M.J. 

Title: METHOD OF SINTERING ALUMINUM NITRODE 

11/06/92 Opened as Disci FI8920668 in US Status : Closed 

11/06/92 Sent to Evaluator 
12/18/92 Closed 

Co -inventors: Takamori, T. Shinde, S.L. 
Title: METHOD OF SINTERING ALUMINUM NITRIDE 



2 of 3 



1 1/3/98 2:40 PN 



11/06/92 Opened as ^fc=-> 
11/06/92 Sent to EvaWato 
12/18/92 Closed 
Co- inventors : Takamori, 



18920667 in US 



Shinde, S.L. 



08/13/92 Opened as Disci FI8920525 
08/17/92 Sent to Evaluator 
09/29/92 Evaluated 
12/23/92 Disci Review 

05/10/95 Filed as Docket FI992168B in US 
05/28/96 Issued as Patent 5520878 in US 
Co -inventors: Takamori, T. Shinde, S.L. 

Title: ALUMINUM NITRIDE BODY AND METHOD FOR FORMING SAID BODY UTILIZING A VITRFnri^ 
SINTERING ADDITIVE U5 



Status: Filed 

Action: Search 

Action: File 
Rating: 2 



Status: Filed 

Action: Search 

Action: File 
Rating: 2 



08/13/92 Opened as Disci FI8920525 
08/17/92 Sent to Evaluator 
09/29/92 Evaluated 
12/23/92 Disci Review 

12/22/93 Filed as Docket FI992168A in US 
01/09/96 Issued as Patent 5482903 in US 
Co-inventors: Takamori, T. Shinde, S.L. 

Title: GOLD DOPING OF YBA2CU307 - 8 AS A MEANS OF INCREASING TRANSPORT CRITICAL 
CURRENT DENSITY 

02/12/92 Opened as Disci YO8920161 in US Status:Closed 
02/14/92 Sent to Evaluator 
05/15/92 Closed 

Co-inventors: Daeumling, M. Shaw, T.M. 

Title: PROCESS FOR PRODUCING CERAMIC CIRCUIT STRUCTURES HAVING CONDUCTIVE VIAS 



07/19/89 Opened as Disci YO8890552 
07/25/89 Sent to Evaluator 
08/10/89 Evaluated 
07/30/90 Disci Review 

12/17/92 Filed as Docket YO990091B in US 
08/16/94 Issued as Patent 5337475 in US 
Co-inventors: Vallabhaneni, R.V. Giess, 
Vanhise, J. A. Aoude, F.Y. Muller- landau. 



Status: Filed 

Action: Search 

Action: File 
Rating: 2 



Farooq, 
Shaw, R.R. 



Cooper, E.I. Kim, Y.H. 
Walker, G.F. Rita, R.A. 



Neisser, M.O. Park, J.M. Shaw, T.M. Brownlow, J.M. Kim, J. Knickerbocker ', S.H. 

Title: VIA PASTE COMPOSITIONS AND USE THEREOF TO FORM CONDUCTIVE VIAS IN CIRCUTTT7Pn 
CERAMIC SUBSTRATES 



07/19/89 Opened as Disci YO8890552 
07/25/89 Sent to Evaluator 
08/10/89 Evaluated 
07/30/90 Disci Review 

03/20/91 Filed as Docket YO990091A in US 
02/01/94 Issued as Patent 5283104 in US 
Co-inventors: Vallabhaneni, R.V. Giess 
Vanhise, J. A. Aoude, F.Y. Muller - landau, 



Status: Filed 

Action: Search 

Action: File 
Rating: 2 



E.A. Farooq, 

Shaw, R.R. 



Cooper, E.I. 
Walker, G.F. 



Neisser, M.O. Park, J.M. Shaw, T.M. Brownlow, J.M. Kim, J. Knickerbocker ', 

Call your award coordinator, IPL department, or T/L 826-2680 for help. 



Kim, Y.H. 
Rita, R.A. 



3 of 3 



1 1/3/98 2:40 P 



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Manganatc Perovskites" to appear Appl. Phys. Lett. Pe T*nd,cular Transport Devices Made Using Doped 

• T.R. McGuire, P.R. Duncombe, C.Q. Gong, A. Gupta, XWLiAfi y» , 

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