Quantitative transmission electron microscopy in substitutionally disordered alloys.

Abstract

High resolution electron microscopy (HREM) is an invaluable tool to analyze crystalline structures, but several difficulties arise when trying to make it quantitative. Some of them are related to the experimental conditions: nature of the samples, optical aberrations, etc. At a more fundamental level, the strong interactions of electrons with matter prevents one from using the simple first order Born approximation (or kinematical theory) which is generally sufficient for treating neutron or x-ray diffraction [1]. Several different but equivalent theoretical and numerical methods have been devised to take into account multiple scattering of electrons. In the case of simple crystals, i.e., of elemental solids or of completely ordered compounds, Bloch theory can be used, and this basically reduces the problem to one similar to that treated in electron band theory. In practice, efficient numerical codes using so-called multislice techniques have been developed and are widely