高臨界電流密度釔鋇銅氧高溫超導體之微結構分析

Microstructure of a Textured YBa_2Cu_3O_x superconductor with High Critical Current Density

王麗萍(L. P. Wang) ； 陳國鋕(K. Chen) ； 林志隆(C. L. Lin) ； 朱兆杰(J. J. Chu)

《化學》 50卷2期 (1992/06) Pp. 175-180

https://doi.org/10.6623/chem.1992020

摘要

為了探討由熔融組織法(melt-textured process)製作之釔鋇銅氧YBa_2Cu_3O_x (123)高溫超導體為何具有如此高的臨界電流密度。(J_c ＞ 37,300 A/cm^2，77 K)，吾人利用X光繞射、偏光顯微鏡、掃描電子顯微鏡及掃描穿透電子顯微鏡來研究此高溫超導體之微結構。發現此結構具有相當高的優選方向(referential orientation)，123晶粒互相以a-b平面平行排列。大量的Y_2BaCuO_s及少量微細CuO析出物散佈在123基地中，在123晶界處發現有BaCuO_2及CuO交錯形成不規則狀的聚集(cluster)。此外，高密度的雙晶(twin)(200~1000Å)佈滿整個超導基地，亦觀察到差排(dislocation)及差排網路(dislocation network)。123晶粒良好的方向性排列及基地中的微觀缺陷對高電流密度均有所貢獻。

並列摘要

The microstructure of a: highly textured bulk YBa_2Cu_30_x (123) superconductor, with the critical current density J_c higher than 37300 A/cm^2 at 77 K, were investigated by X-ray diffraction, polarized optical microscopy, scanning electron microscopy and scanning transmission electron microscopy. It was found that the grains of the 123 superconductor were preferentially oriented along the a-b plane of the 123 phase. The Y_2BaCuO_5 and small CUO particles were dispersed in the 123 matrix and the highly dense twins ran through the matrix everywhere with a twin spacing of 200-1000 Å. Some irregularshaped BaCuO_2-CuO mixture clustered in the 123 grain boundaries. Dislocations were also observed. The aligned 123 crystals and microstructural defects in the 123 matrix were considered to be responsible for the high J_c value.