KENBIKYO Vol.50▶No.2 2015
â– Reviews

Local Structure Analysis of Amorphous Materials Using a STEM Diffraction Method

Akihiko Hirata and Mingwei Chen

Advanced Institute for Materials Research, Tohoku University

Abstract: Local atomic configurations of amorphous materials are one of the long-standing problems in materials science. The local atomic configurations have been determined experimentally using average structural information from large volumes using conventional diffraction and spectroscopic methods. Three-dimensional atomic positions have been achieved only by using simulation methods such as reverse Monte Carlo and molecular dynamics simulations. Therefore direct experimental evidence of local structural order in amorphous alloys is much needed. For this purpose we have developed sub-nanometer scale electron diffraction technique using a scanning transmission electron microscope. The obtained results were interpreted through structural models calculated using an ab-initio molecular dynamics simulation. We further extend this technique to the observation of medium-range order where a similar diffraction vector is hold beyond 1 nm.

Key words: Amorphous structure, Electron diffraction, STEM, Local structural order