2009 Volume 44 Issue 1 Pages 65-68
Interfaces and surfaces of crystals have peculiar electronic structures, caused by the disorder in periodicity, providing the functional properties, which cannot be observed in a perfect crystal. In the vicinity of the interfaces/surfaces, dopants or impurities are often segregated, and they play a crucial role in the material properties. We call these dopants “function providing elements”, which have the characteristics to change the macroscopic properties of the materials drastically. To obtain a guideline for designing material by the atomic scale modification, an understanding of the atomistic mechanism for the functional properties is required as well as precise measurement of the present state of trace elements segregated in the nanoscale region. In recent nano-characterization technologies, there has been remarkable progress by Scanning Transmission Electron Microscopy (STEM) utilizing the spherical aberration (Cs) corrector. The technique enables us not only to identify the location of the dopants but also to analyze the local electronic state for the single atomic column on grain boundaries and interfaces. In this paper, we focus on grain boundaries and interfaces of various ceramics, to which “function providing elements” are doped, and introduce the latest results of the microstructure analyzed in detail by STEM.