High resolution interface analysis

The structure and composition of interfaces in composites and other structural solids has important effects on their properties and is therefore of great interest. HREM and microspectroscopy are two of the most useful methods for examination of interfaces. HREM methods are the most advanced, and microspectroscopy methods are improving rapidly. The current image resolution limit is ∼ 1.6 Å which is sufficient for most interface analysis purposes. The corresponding spatial resolution limit for microspectroscopy is determined by the current in small probes and temporal stability of the probe/specimen. Calculations of probe current vs. size are given and it is shown that current spatial resolution for EELS, for edges containing several thousand counts, is about 5 nm. The effect of chemical bonding on electron energy loss absorption edges of silicon in its important ceramic compounds is presented and briefly discussed. Examples of high resolution analysis in several composites and a multiphase ceramic are presented.