STRUCTURAL AND HYDRIDING PROPERTIES OF AMORPHOUS MGNI WITH INTERSTITIALLY DISSOLVED CARBON

MgNiCx with an amorphous structure were synthesized up to x=1.31 by me chanical alloying of amorphous (a-)MgNi and graphite as starting mater ials. The core-level X-ray photoelectron spectroscopy revealed that th e original bonding states with metallic character of a-MgNi remained e ven in the sample with high carbon content although the graphite disso lved as interstitial carbon and it mainly bounded with Mg in a-MgNi. T he crystallization temperature of MgNiCx increased with increasing car bon content up to x=0.85, which was accompanied by a drastic change in the crystallization processes. Upon hydrogenation of MgNiCx, the atom ic ratio of hydrogen plus carbon to metal (H+C)/M remained a constant value of =0.9 through the whole system, indicating that carbon atoms d issolved into the sites that otherwise would have been occupied by hyd rogen atoms. (C) 1998 Elsevier Science S.A.