Advanced Instrumentations for Interface Studies by Electron Energyloss Spectroscopy (EELS, ELNES and ESI)

Abstract

Most materials used in technology are polycrystalline. Therefore, the properties of the internal interfaces often control the properties of the materials (interface-controlled materials). In single phase polycrystalline materials, grain boundaries are the internal interfaces (homophase boundaries) of interest, whereas in composites interfaces between different components (heterophase boundaries) play a crucial role. It is of great importance to investigate the structure, composition and bonding of the different interfaces. The atomistic structure of specific interfaces is obtained by high-resolution transmission electron microscopy studies, whereas analytical electron microscopy (AEM) investigations produce information on the composition of interfaces. AEM studies include energy-dispersive X-ray spectroscopy (EDX) as well as electron energy-loss spectroscopy (EELS). From the energy-loss near-edge structure (ELNES) of ionization edges measured by EELS, information on the local electronic structure at interfaces can be obtained. Information on bonding and its modifications by segregated atoms can be extracted from the ELNES studies.