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.
