Ordered and Disordered Defects in Perovskite Related Structures With An Emphasis on Superconducting Oxides

本研究是钙钛矿相关氧化物陶瓷缺陷结构和电学性能研究的延续。在此资助期间，将对镧-铜氧化物系统中的材料进行研究。实验技术，如恒定氧活度和恒定化学成分下的平衡电导率、库仑滴定法、电子显微镜（包括选定区域衍射、暗场成像和点阵），将用于提供缺陷浓度、传导机制、以及在某些材料中出现的缺陷排序。在纳米结构水平上提出了一个域模型来解释部分氧化，受体掺杂的相关锶-铁-氧化钛体系成员的观察行为。这些材料在成分和结构类型上都与超导氧化物非常相似。对缺陷结构的性质及其与这些材料电性能的关系的进一步了解将有助于对超导机制的进一步了解。

This research is a continuation of ongoing investigation of the defect structure and electrical properties of the perovskite- related oxide ceramics. Materials in the lanthanum-copper oxide system will be investigated during this grant period. Experimental techniques, such as equilibrium electrical conductivity at constant oxygen activity and constant chemical composition, coulombic titration, electron microscopy (including selected area diffraction, dark field imaging, and latticing, will be used to give quantitative information on defect concentrations, conduction mechanisms, and on the defect ordering that occurs in some of these materials. A domain model at the nanostructure level has been proposed to explain the observed behavior of partially-oxidized, acceptor-doped, members of the related strontium-iron-titanium oxide system. These materials are remarkably similar to the superconducting oxides in both compositional and structural type. An improved understanding of the nature of the defect structure and its relation to electrical properties of these materials will lead to an improved understanding of the mechanisms of superconductivity.