Chemical and Valence Structure Analysis of Functional Materials

Abstract

Chemical microanalysis is an important aspect of structural characterization. In functional materials, nonstoichiometry plays a key role in determining their properties. A change in oxygen stoichiometry or a substitution of cations by dopants, for example, may result in a structural evolution. More importantly, the structure transformation may occur in a small region, where only the analytical techniques with high spatial resolution can be used to determine the local structure. Energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) in TEM have been demonstrated as powerful techniques for performing microanalysis and studying the electronic structure of materials. The analysis of energy loss near edges allows the determination of valence states of atoms, which is unique for studying functional materials with mixed valences.