EFFECT OF THERMAL TREATMENTS ON THE SUPERCONDUCTIVITY OF UNDOPED AND WO3 DOPED Y-Ba-Cu-O SYSTEM
SHI LEI (石磊)a, FENG YONG (冯勇)b, PANG WEN-HUA (庞文华)a, DU SHE-JUN (杜社军)b, ZHOU LIAN (周廉)b, LI XIAO-GUANG (李晓光)a, ZHOU GUI-EN (周贵恩)a, ZHANG YU-HENGac
a Laboratory of Structure Analysis Research, University of Science and Technology of China, Academia Sinica, Hefei 230026,China; b Northwest Institute for Nonferrous Metal Research, Baoji 721014,China; c CCAST,World Laboratory, Beijing 100080,China
Abstract Undoped and WO3-doped Y-Ba-Cu-O ceramics have been slowly cooled in flowing oxygen or quenched in air from 900℃ to room temperature, after sintering at 900℃ for 3Oh in flowing oxygen. The ac susceptibility measurements show that the Tc of the quenched WO3-doped Y-Ba-Gu-O superconductor can reach 88K, while the undoped Y-Ba-Cu-O ceramic quenched in air is a non-superconductor. X-ray diffraction data show that WO3 does not enter into the YBa2Cu3O7-x lattice but forms all impurity phase. The WO3-doped YBCO specimens quenched in air consist of orthorhombic YBa2Cu3O7-x phase and an impurity phase which increases with increasing WO3 content. Raman spectra chow that oxygen contents are different for undoped and WO3-doped samples. It la suggested that suitable doping with WO3 can change the oxygen content and reduce the effect of thermal treatments on the superconductivity of Y-Ba-Cu-O system.
Received: 05 February 1997
Accepted manuscript online:
(Effects of crystal defects, doping and substitution)
Fund: Project supported by the Youth Science Foundation of the University of Science and Technology of China, the National Ceter for Research and Development on Superconductivity, and the National Natural Science Foundation of China.
Cite this article:
SHI LEI (石磊), FENG YONG (冯勇), PANG WEN-HUA (庞文华), DU SHE-JUN (杜社军), ZHOU LIAN (周廉), LI XIAO-GUANG (李晓光), ZHOU GUI-EN (周贵恩), ZHANG YU-HENG (张裕恒) EFFECT OF THERMAL TREATMENTS ON THE SUPERCONDUCTIVITY OF UNDOPED AND WO3 DOPED Y-Ba-Cu-O SYSTEM 1997 Acta Physica Sinica (Overseas Edition) 6 614
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