Industry-University Cooperative Research Activity: Off-Center Paraelectric Systems and the Transition from Off-Center to On-Center Behavior (Materials Research)

本课题将研究绝缘晶体中缺陷离子和原子的位移。利用静水压力的对电共振实验，将研究几个系统的中心到中心的转变。EXAFS（扩展x射线吸收精细结构）将直接测量离子或原子（如Ag）的偏心位移，而不依赖于电荷状态；s +铜;s + Co, s2;s + Ag);so和Cu；so。在某些情况下，它将首次测量晶格偏离中心缺陷的畸变。数据也将获得在几个系列的缺陷系统中，其中的缺陷的位置从偏离中心到正中心变化的正阴离子距离。其中一些数据将在离子半径有很大差异的系统中检验维加德定律。这些实验将提供有关偏离中心行为所需条件的必要信息。

In this project, the displacement of defect ions and atoms in insulating crystals will be studied. Paraelectric resonance experiments, using hydrostatic pressure, will investigate the on- to off-center transitions in several systems. EXAFS (extended x-ray absorption Fine Structure) will measure directly, independent of the charge state, the off-center displacement of ions or atoms such as Ag;s+, Cu;s+, Co;s2;s+, Ag;so and Cu;so. In some cases, it will measure for the first time, the distortion of the lattice about an off-center defect. Data will also be obtained for the cation - anion distances in several series of defect systems in which the position of the defect varies from off-center to on-center. Some of these data will test Vegard's Law in systems for which there is a large difference in ionic radii. These experiments will provide needed information about the conditions required for off-center behavior.