摘要
水文研究了Bi_(0.92)Pb_(0.17)Sr Ca Cu_(1.5)O_y样品的物相结构、物相转变和超导电性与热处理过程的关系。实验结果表明,经过830℃/32hrs预烧的粉料中已经有2212相形成。尽管样品的电阻在低温下(60K)仍未到零,但磁化率转变曲线却相当陡。找不出其它超导相存在的证据。经过850℃/72hrs的高温烧结后,根据X—T曲线和X—T曲线可知,超导转变都是单一行为的,转变宽度很窄,临界温度较高,说明样品结构以2223相为主。值得一提的是,在烧结时间居中的样品中,电阻转变曲线出现了三个台阶,磁化率转变曲线也明显加宽,证明有第三个相存在的可能性。我们倾向于该相产生在两个超导相的界面上,而2223相很可能是从2212相产生出来的。
The relation between the heating process and the phase structure , phase transformation and superconductivity of Bi0.92Pb0. 1 7SrCaCu1 .5Oy lias been studied in this paper.The experiments showed that the 2212 P-hase has already formed in pellets of the oxide powder calcined at 830℃ for 32 hrs. Although the resistance did not vanish even at the temperature of 60K,the susceptibility transition was rather sharp, and there was no evidence for other superconducting phase. According to R-T and X-T curves of the sample sintered at850℃ for 72hrs,the superconducting transition was all single behavior, the transition width was very narrow, and the Tc was rather high.This indicates that the main phase in the sample is 2223 structure. It is interesting that three steps appear on the R-T curves and the X-T curves are also broadened in samples sintered for some moderate times .This infers the possibility of the third superconducting phase. We suggest that this phase exists on the boundaries between the 2212 and the 2223 phase, while the 2223 phase is likely to grow from the 2212 phase,
出处
《低温与超导》
CAS
CSCD
北大核心
1990年第1期61-64,共4页
Cryogenics and Superconductivity
基金
化工部新材料局重点科研项目
