作　　者： ; ; (等）;

机构地区： 兰州理工大学基础科学系

出　　处： 《低温物理学报》 2000年第5期321-339,共19页

摘　　要： 用变温X 射线衍射 ,扫描量热分析 ,热重分析对精心制作的Bi1 .7Pb0 .3Sr2 Ca2 Cu3Ox 超导样品在后处理前和后处理后从液氮温度到熔点温度进行了分析 ,并对样品进行了XPS分析 ,载流子浓度和超导电性测量 .实验发现 ,样品沿C方向的膨胀系数在低温区有两个反常 ,在高温区有两个热量和重量反常 .结果分析表明 ,这两个反常与晶体结构中两个不同的结构块有关 ,即钙钛矿和盐岩结构块 .实验发现 ,这两个结构块之间的失配 ,超导临界温度 ,样品中的氧含量 ,以及膨胀系数的变化之间有密切的关联 .实验结果表明 ,了解两个不同结构块之间的相互作用对认识高温超导电性有重要作用 . The elaborated and well characterized Bi\-\{1.7\}Pb\-\{0.3\}Sr\-2Ca\-2Cu\-3O\- x samples, as prepared and annealed in different conditions, were studied by temperature dependent X ray diffraction from liquid nitrogen temperature to melting point, differential scanning calorimetry, thermogravimetry, X ray photoelectron spectroscopy, carrier concentration, and superconductivity measurements. Two changes of thermal expansion coefficient along the c direction in low temperature range and two thermal instabilities in high temperature range are observed, which suggests that the structure changes in this system is associated with two different blocks, i.e., perovskite and rock salt blocks, of the unit cell. The changes in structure and in electronic properties related to these blocks are also observed. It is found that there is a close correlation among the mismatch between the two different blocks, value of T\-c , oxygen content, and thermal expansion coefficient, and a roughly quantitative relationship is also obtained. The experimental results suppose that the interaction between different layers especially two different blocks, is of importance to understand the superconductivity in oxide superconductors.

关 键 词： 超导体 晶体结构 电子性能 结构块 超导电性

领　　域： [理学] [理学] [电气工程] [一般工业技术]