Theoretical Study of the Atomic and Electronic Structures of Grain Boundaries

First-principles calculations based on density-functional theory have been applied to the energies and atomic and electronic structures of various metal/inorganic material interfaces such as metal/Al 2 O 3 , Au/TiO 2 and metal/SiC interfaces used in thermal barrier coatings, gold catalysts, and high-power electronic devices, respectively, in collaboration with electron microscopy observations. In each system, it has been shown that the interface stoichiometry, namely the features of interfacial termination species of inorganic materials, as well as the metal species, is one of the most important factors to design the interfacial structure and the adhesive, mechanical, chemical and electronic properties. Recent electron microscopy observations of peculiar dynamical structural changes in Au/CeO 2 systems are discussed from this view point