Surface analysis of an amorphous MgNi alloy prepared by mechanical alloying for use in nickel–metal hydride batteries

Abstract

An amorphous MgNi alloy prepared by mechanical alloying has been investigated by means of X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) in combination with an Ar + sputtering technology. At the top surface (ca. 30 Å), Mg was dominant and existed in oxide forms while Ni mainly existed in the metallic state. Underneath the top surface, there was a layer enriched with metallic Ni which penetrates to more than 150 Å. Such a distribution of Mg and Ni at the surface layer tightly correlates to the unique hydriding and dehydriding properties of the amorphous MgNi alloy.