Surface states of hydrogen storage alloy TiVCr

Haruyama, Yuichi*; Teraoka, Yuden; Matsui, Shinji*

An alloy of TiVCr system is a solid-sulution type three elements alloy with a BCC crystal structure. It is known as a hydrogen storage material. The amount of hydrogen storage is about 2.3w%. It is relatively larger comparing to that of other hydrogen storage metals. Prior to hydrogen storage, an initial activation process is needed to change its surface atomic structure. We performed inner-shell photoemission spectroscopy, balence band photoemission spectroscopy, and X-ray absorption near-edge spectroscopy measurements to study an electronic structure and effects of hydrogen absorption in a hydrogen storage alloy such as the TiVCr. Furthermore, thermal annealing effects of them were investigated. With increasing thermal anneal temperature, photoemission intensity of Ti increased comparing to V and Cr. This fact implies that Ti segregates near surface by thermal annealing.