Local Chemistry at Interfaces and Boundaries: Ceramic and Electronic Composite Materials

\nThe spatial extent of chemical solute distributions that formed\nin interfaces between platinum or silicon nitride and silicon\ncarbide or in silicon nitride grain boundaries during high\ntemperature processing of these composites has been investigated\nby position resolved nanospectroscopy, Z-contrast imaging and\nenergy selected imaging. The solute distributions resulted from\nintentional sintering aid additions or interfacial reaction.\nThe distribution widths normal to the nominal interface/boundary\nplanes, called chemical interface/boundary widths, were much\nlarger than the corresponding structural widths of the same\nboundaries and interfaces, determined by HREM imaging.\nQualitative agreement between the three methods used to\ndetermine chemical widths was excellent. Differences in count\nrate resulting from beam current differences among the methods\nresulted is some predictable quantitative disagreements in\nabsolute chemical widths. Energy selected imaging proved to be\na very fast, efficient method for examination of chemical\ndistributions over large specimen areas.\n