7 December 2015, 11:00, FLNR Conference hall (3rd floor)

Tomoyuki Yamamoto, director of the Institute of Condensed-Matter Science, Waseda University, Head Professor of the Department of Electronic and Physical Systems, Faculty of Science and Engineering, Waseda University, Okubo, Shinjuku, Tokyo.

X-ray Absorption Near-Edge Structure Analysis for Functional Materials with the Aid of the First-Principles Calculations

Doping technique, i.e., incorporation of dilute amount of additional elements, has been widely applied to add new functions for various kinds of materials. Appropriate doping can change their specific properties drastically, e.g., electric, magnetic, optical, mechanical and chemical properties, etc. It is, of course, fundamental to know the crystal and electronic structures of such materials. In addition to such studies, it is mandatory to investigate the local environment of dopants on an atomic scale to understand the mechanism of appearance of new properties by doping and to design new materials with desired properties by such doping technique. Although crystal structure analysis has been widely carried out by the X-ray diffraction (XRD) technique, it is very difficult to determine the local environment of dilute dopants only by XRD. There are some experimental methods to investigate such local environment of dilute dopants. Among these methods, X-ray absorption near-edge structure (XANES) analysis by using the synchrotron radiations is one of the most powerful methods, which enables us to determine the local environment of dopant at an ultra-dilute concentration level, such as atomic ppm level of concentration [1]. We have reported quantitative analysis of XANES from many different kinds of functional materials [2, 3] with the aid of the first-principles calculations within the density functional theory (DFT).

In the current talk, the overview of our strategy to investigate the local environment of dilute dopants in the functional materials and some of the recent results will be presented.