掺Ba的2201相的结构与性能的关系

利用电子衍射方法发现Ｂａ的掺杂增强了Ｂｉ系２２０１相的非公度调制，即沿ｂ，ｃ方向的调制周期都明显下降。超导电性研究发现适量Ｂａ的掺杂（ｘ≤０．２）可提高２２０１相的T_c，但当ｘ≥０．３时，其T_c迅速下降，同时伴随超导相－绝缘相的转变。还利用Ｘ射线和紫外光电子能谱系统地分析了此体系的电子结构的特征，在此基础上综合地分析了该体系的非公度调制结构、电子结构与超导电性的相互关系，指出这种Ｂａ^２＋对Ｓｒ^２＋的同价元素的替代加剧了 关键词：

CORRELATION OF STRUCTURE AND PROPERTIES IN Ba-DOPED Bi-2201 PHASE

In this article, it is revealed that the Ba substitution intensifies the incommens-urate modulation of the Bi-2201 phase, namely the wavelengths of the modulation along b and c directions show obvious decrease. The study of superconductivity of the Ba-doped 2201 shows that the appropriate substitution of Ba for Sr (x≤0.2) can raise the T_c of 2201 phase, but as x exceeds 0.3, T_c decreases sharply, simult-aneously accompanied with the superconductor-insulator. transition In addition, the characteristic feature of electronic structure of the Ba-doped 2201 phase is also stu-died by use of the XPS and UPS spectra. Based on all these experimental resuits, the relation between incommensurate modulation structure, electronic structure and superconductivity for the Bi-2201 phase are discussed comprehensively, indicating that the replacement of Ba^２＋ for Sr^２＋ intensifies the mismatch between Bi-O layers and perovskite blocks. and the enhancement of this mismatch influences the symme-try of Cu-O₂ planes seriously, just for this reason the variation of electronic state of Cu3d takes place (i.e. the degree of the coulomb correlation of the Cu3d electr-ons tends to be intensifled). In the process of Ba-doping, just due to the variation of Cu3d electrons, the 2201 phase undergoes a superconducting-insulating phase tran-sition.