PHYSICAL REVIEW 8 VOLUME 38, NUMBER 10

B48r3Ca3Cu4016 glaSS and SuperCOnduCting glaSS CerasssICS

1 OCTOBER 1988

Haixing Zhegg and J. D. MackenzieDepartment of Materials Science and Engineering, University of California, Los Angeles, California 90024

A Bi4Sr3Ca3Cu40&& glass has been successfully fabricated by the melting process. Glass transi-tion temperature, crystallization temperature, and liquid temperature of the glass are 434, 478,and 833 C, respectively. After the glass is heat treated at 800'C, a glass ceramic is formed. Acomparison of the x-ray-diffraction pattern of the superconducting Bi&Sr3Ca3Cu40$$+ ceramic tothe Bi&Sr3Ca3Cu40&6, glass ceramic revealed preferred orientation in the glass-ceramic crystals.The superconducting transition temperatures T,~„t~ and T,~~~ of the glass ceramics are 100and 45 K, respectively.

I. INTRODUCTION

The discovery of the high-temperature superconductingLa-Ba-Cu-0 system' has led to the subsequent discoveryof a series of other superconducting systems: Y-Ba-Cu-O,Bi-Sr-Ca-Cu-O, and Tl-Ba-Ca-Cu-0. 2 The Bi-Sr-Ca-Cu-0 system generally consists of a few superconductingphases with different T, and the formation of these phasesis process dependent. s One phase for superconductivity inthe Bi-Sr-Ca-Cu-0 system is considered to be B4Sr3-Ca3Cu40ts with T, 85 K.

The practical applications of high-T, superconductingmaterials require (a) the ability to be fabricated intospeci6c shapes such as 6bers, wires, tapes, or 6lms, and(b) the ability to carry high current. Many ceramic pro-cesses have been applied to fabricate YBa2Cu307, ma-terials. ' Here we report a new way of fabricating Bi-Sr-Ca-Cu-0 materials: the glass-ceramics process.

II. EXPERIMENTAL RESULTS AND DISCUSSIONA. B4Sr3Ca3C~Oig glass

Bismuth oxide, strontium carbonate, calcium carbon-ate, and copper oxide were mixed with the ratioBi:Sr:Ca:Cu 4:3:3:4.A 5-g batch was melted at 950'Cfor 2 h in air in alumina crucibles, and then the melt wasquenched by pressing the cast liquid between two brassplates. The 1-mm-thick glass formed was dark red. Theglass was electrically insulating and its density was 5.73g/cm'.

Figure 1(a) is the x-ray-diffraction pattern (obtainedusing Cu Ka radiation) of the resulting material. It showsthat the material was glassy. The differential thermalanalysis (DTA) curve (Fig. 2) of the material showed thatthe glass transition temperature was about 434'C, andthe crystallization temperature was 478'C. The liquidtemperature of the glass is about 833'C. Table I lists the

3

2-

CO

XOO

O0—

Q.4

20I

404

50I

60 70

4NGLE 28 (deg)

FIG. 1. X-ray-diffraction patterns of (a) Bi4Sr3Ca3Cu40&4 glass, (b) glasswramics powder, and (c) glass-ceramic bulk. The as-signment of the Miller indices noted above each peak in (c) is based on Ref. 10.

7166 @1988The American Physical Society

8&r3ca3cu40i6 GLASS AND SUPERCONDUCUCTING GLASS CERAMICS 7167

OOXLLJ

Tc

160 340 520 700

Temperature ('C)

880 FIG. 3. Scanning electronicBi4Sr Ca

ic micrograph of superconducting14 r3Ca3Cu40'6 glass ceramic (length of the bar. 2 pm

FIG. 2. Diff'fferential thermal analysis of Bi4Sr3Ca3Cu 0glass (heating rate: 10'C™nl

i4 r3 a3 u40/6

properties ofthis glass.

known that wh3 y' self does not form glass easily 't'Although Bi 0 b it

k when melted with mixture of other dS1 $, 1 1S

glass is formed' Mosto er ox' es,

e . ost ~&own glasses containing asigniicantly high concentration of Bi203 have relative

p ese t glass h G

w ich is somewhat surprising.

B. B'SrC~ 4 3Ca3Cu40&&+, glass ceramics

3 4 ]$ glass was annealed atWhen the Bi4Sr3Ca Cu'C in air, it crystallized [Figs. 1(b) and l(c)]. X-ray

diffraction of the bulk [Fig. 1(c)) and powder [Fig. 1(b)]a t e crystalline phaseground from the bulk) showed that the

is superconducting Bi4Sr3Ca3Cu40iq+„. As shx-ray-diffraction37 47 54 56 58

y-'

ion peaks of the bulk solid at 28: 25' 33',, and 70' were enhanced espec' I-

y r"or the 33 0ia-

Cu40is+„cr stals wy i 33 and 37 peaks since the B' S Ce i4 r3 a3-

«+„gstals were strongly anisotopic (a 3.817 A.,

atom lanesthese enhanced peaks came f th

p es nearly parallel and parallel to c axis. '

Therefore, this enhancement of the d'ffo e i raction peaks indi-c-axis preferred orientation of the Bi4Sr3-

Ca3Cu4 i&+„crystals in the bulk sample. F' 3 harming electronic micrograph (SEM) of the

a e i e an had preferred orientation while the crystal

TABLE I. Bi4Sr3Ca3Cu40~6 lass.3 4 f6 g ass. Glass transition tempera-ure, C. Crystallization temperature, 478 'C. Densit 5.7

g/cm3. Infrared cutoff, 5.5 pm.ensity, 5.73

size was uniform. SEM also showed that th 1

was almost dense. This agrees with the density results.According to the calculation" th d

i2 r2s ap5Cu20s+& single crystal was 6.70 g/cm. Sothe calculated density of the Bi4Sr Ca C 0u4 is crystal

a or Sr. The observed density of the Bi4Sr3Ca3Cu40

lasscm . is indicated that the

g ass ceramic was about 98.5% ( 6.25/6. 35) dense.

dThe Bi4Sr3Ca3Cu 0

enser than the las4 iq g'ass ceramics are signficantl

1 lar eg s.

Thedifference�in

densit wo ld'wou im-

py g shrinkage during the cryst ll' t' fa izaion o thea3 u4 iq glass. The electrical resistivity of the

glass and glass ceramic are about 10 Ocmrespectively.

cm an 1 Ocm,

C. Superconloctiag properties

four- rElectrtca resistivity was measured b th

-probe method for the bar shape of 0.5X I &6 mmy e stan ard

"40,

220

200

180-

'160 ~

Cg

140E

c 120CP

a&00-

th

K 80

60-

40 ~

Bi203SrOCaoCuO

mol%

16.725.025.033.3

wt. Vo

54.018.09.7

18.3

020 60 100 140 180 220 260

Temperature (K)

Bi SFI . 4. Temperature deependence of resistance for

i4 r3 a3Cu40]6 glass ceramic.

7168 HAIXING ZHENG AND J.D. MACKENZIE

with silver paste electrical contacts. Figure 4 showed theresistivity of the 84Sr3Ca3Cu401s glass ceramic as afunction of temperature. At room temperature, the resis-tance of the specimen ~as about 0.23 Q. The resistivitydecreases linearly from room temperature down to 105 K.Then it derived from linearity to the superconducting on-set 100 K. The first sharp resistivity drop ended at 75 K.Then the second drop began, and reached zero resistanceat 45 K.

The T,&««) of the Bi-Sr-Ca-Cu-0 system is dependenton the process conditions. 3 s The annealing temperatureis an important factor. The closer to the melting point ofthe annealing temperature, the higher the T,&««& of thematerials. 3 5 It also has been observed that the materialsexhibiting a sharp resistance drop near 110 K possessT,&,«,) lower than 80 K. The lower T,(,«, & of theBi4Sr3Ca3Cu40&s glass ceramic may be due to nonidealprocessing. Further investigation is being carried out tooptimize the glass ceramics process to obtain higherTc(zero)

are random distribution of the crystals and the relativelyhigh porosity of these ceramics. The preferred orientationand almost pore-free structure of the present supercon-ducting Bi4Sr3CasCu40~s+„materials implies that theglass-ceramics process is a most promising technique forthe fabrication of the high-T, superconducting Bi-Sr-Ca-Cu-0 materials. The glass route is also of practical im-portance in the fabrication of specific shapes (fibers,wires, and tapes). '

In conclusion, a Bi4SrsCa3Cu40~s glass has been suc-cessfully fabricated. Glass transition, crystallization, andliquid temperatures of the glass are 434, 478, and 833'C,respectively. After annealing at 800'C, the glass crystal-lizes, and the resulting glass ceramic is superconductingwith T,«, «& 100 K, and T,(««) 45 K. Further effortson optimizing the process, and the formation of glassfibers, are needed.

ACKNOWLEDGMENTS

D. Summary and conclusions

It is well known that two main reasons for low-criticalcurrent density J, of high-T, superconducting ceramics

We wish to thank Xin gin, C. T. Chu, and Mary Colbyfor assistance. The financial support of the Strategic De-fense Initiative Organization and the Air Force Office ofScientific Research, Directorate of Chemical and Atmo-sphere Science are also greatly appreciated.

'J. G. Bednorz and K. A. Miiller, Z. Phys. B 64, 189 (1986).zM. K. Wu et al. , Phys. Rev. Lett. 5$, 908 (1987).3H. Maeda, Y. Tanaka, M. Fukutomi, and T. Asano, Jpn. J.

AppL Phys. Lett. 27, L129 (1988).4Z. Z. Sheng and A. M. Hermann, Nature 332, 138 (1988).SJ. M. Tarascon et al. , Phys. Rev. B 37, 9382 (1988).Paixing Zheng, K. C. Chen, and J. D. Mackenzie, in Extend-

ed Abstracts: High-Temperature Superconductors II, editedby D. %.Capone II, %'. H. Butler, B.Batlogg, and C. %.Chu(Materials Research Society, Pittsburgh, 1988), Vol. EA-14,p. 93.

7R. Pool, Science 240, 25 (1988).SH. Rawson, Inorganic Glass Forming -Systems (Academic,

London, 1967).9W. H. Dumbaugh, Phys. Chem. Glasses 19, 121 (1978); 27,

119 (1986).'oR. M. Hazen et al. , Phys. Rev. Lett. 60, 1174 (1988)."M.A. Subramanlan, et al. , Science 239, 1015 (1988).'zP. W. McMillan, Glass Ceramics, 2nd ed. (Academic, London

1979).