Characterization of High-Temperature Superconducting Materials in Y-Ba-Cu-0 Systems
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CHARACTERIZATION OF HIGH-TEMPERATURE SUPERCONDUCTING MATERIALS IN Y-Ba-Cu-O SYSTEMS HIROSHI KEZUKA* AND TOMOMI MASAKI** *Department of Electronics,Tokyo Engineering University,1404-1 Katakura,Hachioji,Tokyo 192 Japan **Electronics,Engineering College,1404-1 Katakura,Hachioji, Tokyo 192,Japan
ABSTRACT The Y-Ba-Cu-O systems have been reported to be a high temprature superconductor with above 90K. Optical Study would give us useful informations as a characterization for Y-Ba-Cu-O systems with an analysis of energy dispersive X-ray system EDS . 0ptical constants of superconducting Y-Ba-Cu-O systems are n*=l.6 92-jO.403 for 99.99%(4N) with Y1.O0 Bal.90 Cu2.87 and n*=l.604-j 0.441 for 99.99%+(4N+) with Y1.O0 Ba2.18 Cu3.12. INTRODUCTION The Y-Ba-Cu-O systems have been widely reported with superconducting transition tempetature(Tc) over 90K for obtaining higher quality systems[l]-[3]. In order to investigate the material characterization in Y-Ba-Cu-O systems, optical study would give us useful information for the films (4) and bulk materials. The purpose of this work is to obtain the optical properties of Y-B a-Cu-O systems as a surface impedance with the analysis of(EDS). Y-Ba-Cu-O superconductor has many grain boundaries and voids which are mainly due to the effect of moisture on the surface[6]. Recently our reports showed that we obtained higher quality superconductor with higher purity of the starting materialls of YB-
Cu[5]. EXPERIMENTAL Specimens were prepared by mixing and annealing the starting materials of Y203,BaCO3 and CuO for 99.9%(3N),99.99%(4N) and 99.99%+(4N+). Mixtures are ground with an alumina mortar and pestle for 2 hr. The mixtures were prefired at 880 C for 3hr and then, after grinding, annealed at 900 C for 5hr in air and cooled to room temperaturein the furnace. Powders are ground and pressed into pell ets,sintered at 930 C in 02 for 5hr. We inverstigated characterizations of the mixed and annealed Y-Ba-Cu-O superconductors with a superconducting transition temperature(Tc) by X-ray diffraction and scanning electron micrMat. Res. Soc. SyMp. Proc. Vol. 169. 01990 Materials Research Society
1030
oscopy(SEM) with an energy dispersive optical measurements were examined by the surface ofYBCuO-pellets pollished amond spray in order to obtain optical
X-ray system(EDS). Also, ellipsometry (Gaetner) on with a grinder using a di-constants (n*= n-jk).
RESULTS AND DISCUSSIONS Chemical composition was analysed by Inductively Coupled Plasma emission Spectroscopy(ICP) as shown in Table I.
Table I.
Results of chemical by ICP(ppm).
Analysis of starting materials
3N/4N
Ag
Al
Ca
Cr
Cu
Fe
Pb
Si
Sr
CuO(3N) CuO(4N) CuO(4N+) BaCO3(3N) BaC03(43N) BaCO3(4N+)
16 0 0 0 0 0
10 0 0 0 0 0
31 5 0 13 7 5
16 0 0 0 0 0
0 0 0
280 2 3 0 0 0
300 0 0 0 0 0
21 6 6 0 0 0
0 0 0 950 87 40
360 0 0 0 0 0
Y203(3N) Y203(4N)
0
0
0
0
0
0
0
0
0
0
58
0
0
0
0
0
0
59
0
Y203(4N+)
0
0
0
0
0
0
0
0
60
0
0
Zn
Characterization of YBCO superconductor prepared by mixing and heat treatment at 930
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