摘要
研究确认,在Bi-Sr-Ca-Cu-O系统固相反应中,T_c为85K的Bi_2Sr_2Ca_1Cu_2O_(8+δ)超导相(即2212相)是经由一个Bi-Sr-Ca-O四元中间相与CuO等反应生成的。应用DTA、XRD、SEM等手段详细研究了此中间相形成条件及其成分和晶体结构。确定该中间相系组成为BiSryCa_(1-y)O_(2.5)的Bi-Ca-O和Bi-Sr-O固溶体(式中y=0-0.75)。y=0时的结构属单斜晶系,其a=23.083A、b=5.409A、c=21.132A,β=110.688°。y值增大,其结构不变,d值有规律地稍有增加。但当y>0.5后,晶体结构畸变加剧,中间相成分及Sr固溶量对超导相形成及其结构和性能有重要影响;对确定单相性好的高品质高温超导体合理制备工艺有重要意义。
Through the study of the solid phase reaction of Bi-Sr-Ca-Cu-O system,it was confirmed that the superconductive phase Bi_2Sr_2Ca_1Cu_2O_(?) (T_c=85K), namely 2212 phase,is formed by the reaction of a Bi-Sr-Ca-O quaternary interphase and CuO. The formation conditions, the composition and the crystal structure of the interphase were studied by DTA, XRD and SEM. The study results reveal that this interphase is the solid solution of Bi-Ca-O and Bi-Sr-O, the composition of which is BiSr_yCa_(1-y)O_(2,5) (y=0-0.75). When y=0, the crystal structure belongs to monoclinic system, in which a=23.083A, b=5.409(?), c=21.132(?), β=110.688°. With the increase of the value y, its structure remains the same, while the value of d increases regularly and slightly. But if y>0.5, its crystal structure will be distorted greatly. The composition of the interphnse and the solid solubility of Sr have great influence over the formation, the structure and the property of the superconductive phase, and they are of great significance to the determination of the reasonable preparation technology of high quality and high temperature superconductor with fine monophase.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
1992年第1期29-34,共6页
Journal of The Chinese Ceramic Society
基金
浙江大学科学基金
关键词
中间相
陶瓷
超导体
铋
interphase
bismuth system ceramics
high critical temperature
superconductor
