Angstrom-Beam Electron Diffraction Technique for Amorphous Materials

This chapter describes a direct measurement method called angstrom-beam electron diffraction that detects the local atomic arrangements of amorphous materials using sub-nanometre-sized electron probes. The purpose of this method is to provide additional structural information to global diffraction experiments, such as X-ray or neutron diffraction methods, by taking electron diffraction from local regions. The chapter first provides a brief background on this method, including diffraction from small volumes, as well as the effects of specimen thickness. Subsequently, it summarizes a few applications of this method to local atomic arrangements of structural and functional amorphous materials, such as metallic glasses, oxide electrode materials, and phase-change Materials. This method reveals the distortion of icosahedral atomic clusters in metallic glasses, nanoscale inhomogeneity of silicon monoxide, and structural similarity between amorphous and crystal chalcogenide structures in these applications. Lastly, this chapter presents related analysis techniques, including angstrom-beam electron diffraction mapping, local reverse Monte Carlo simulation, and virtual angstrom-beam electron diffraction method. These techniques seek a deeper understanding of the relationship between diffraction patterns and local atomic arrangements. These facts demonstrate that this method could be a powerful analytical tool to reveal the hyperordered structures between order and disorder.