Superabundant vacancies and enhanced diffusion in Pd-Rh alloys under high hydrogen pressures

Abstract

In the authors` recent experiments on a number of metal-hydrogen systems, they discovered that the equilibrium concentration of metal-atom vacancies is greatly enhanced under high hydrogen pressures. They suggested that this phenomenon of superabundant vacancy formation should be the cause of the hydrogen-induced migration of metal atoms reported for some Pd alloys. The purpose of this paper is to provide detailed structural information on the formation of superabundant vacancies and its effects on the phase separation process in Pd{sub 0.8}Rh{sub 0.2} alloys by performing in situ X-ray diffraction at high temperatures and high hydrogen pressures.