Structure Defects and Chemical Reaction in the Solid State: High-Resolution Transmission Electron Microscopy and Micro- analysis

本研究的目的是在原子水平上探讨固态化学反应的机理。这样的描述是罕见的，但它们对自然的科学理解和材料的有效设计至关重要。完成这样一项研究的手段现在已经成为高分辨率电子显微镜（HREM）、分析电子显微镜（AEM）和相关技术的通用标签，这些技术现在具有必要的横向分辨率。此外，低光电视技术与高速图像处理相结合，还可以实现高时间分辨率。这些研究还将得到独特的新型超高真空显微镜的帮助，这种显微镜可以有效地消除薄膜研究中不必要的化学干扰。将使用这些HREM技术研究各种一般类型的原位化学反应和提出的反应机制。将使用的样品配置包括两种真空沉积物质（Au-Si， Au-Al等）在薄膜中的扩散和反应，显微镜下残留气体中可能发生的气固反应（活性金属的氧化），热或辐射诱导的化合物分解以及材料表面结构动态变化的研究。在显微镜外反应的样品的微观表征也将被研究。此外，与CaF2结构相关的二元和三元材料（如二元稀土氧化物和钙稳定氧化锆）也有待进一步研究。特别是制备和结构包括缺陷将被强调。这些缺乏阴离子的材料在科学上引起了极大的兴趣，因为它们有几种固态行为需要澄清，并且在技术上很重要，如反应堆燃料、高温高强度陶瓷、快离子固体电解质和特定离子电极传感器。

The purpose of this research is to investigate the mechanisms of solid state chemical reactions at the atomic level. Such descriptions are rare yet they are important to the scientific understanding of nature and vital to the efficient design of materials. The means for accomplishing such a study have now become available under the general label of high-resolution electron microscopy (HREM), analytical electron microscopy (AEM) and associated techniques which now have the requisite lateral resolution. Furthermore, with the union of low-light TV techniques and high-speed image processing, high temporal resolution is available as well. These studies will also be aided by the availability of unique new ultra-high vacuum microscopes that can effectively eliminate unwanted chemical interference in thin film research. In situ chemical reactions of various generic kinds will be studied using these HREM techniques and the mechanisms of reactions proposed. Configurations of specimens that will be used include diffusion and reaction of two vacuum deposited substances (Au-Si, Au-Al, etc.) in thin films, gas-solid reactions that can occur in the residual gases of the microscope (the oxidation of a reactive metal), thermal or radiation-induced decomposition of compounds and the study of dynamic changes in the surface structures of materials. Microscopic characterization of specimens reacted outside the microscope will also be studied. In addition, the class of binary and ternary materials with a structure related to that of CaF2 are to be further studied (e.g. the binary rare earth oxides and calcia-stabilized zirconia). In particular preparation and structure including defects will be emphasized. These anion-deficient materials are of great interest scientifically because of several types of solid state behavior requiring clarification and technically important as reactor fuels, high-temperature and high-strength ceramics, fast- ion solid electrolytes, and specific ion electrode sensors.