Structural investigation and hydrogen storage capacity of LaMg2Ni9 and (La0.65Ca0.35)(Mg1.32Ca0.68)Ni9 of the AB2C9 type structure

A new quaternary magnesium based alloy (La0.65Ca0.35)(Mg1.32Ca0.68)Ni-9 and its hydride have been synthesized and their crystal structures were determined by Guinier-Hagg X-ray powder diffraction. The compound has a hexagonal structure and is isostructural with LaMg2Ni9 (AB(2)C(9) type), in which Ca partially occupies both A and B sites. The hydrogen absorption/desorption properties were determined by pressure-composition isotherms and compared with LaMg2Ni9. (La0.65Ca0.35)(Mg1.32Ca0.68)Ni-9 absorbs similar to 1.87 wt.% H-2 at similar to 3.3 MPa H-2 and 283 K. (C) 2000 Elsevier Science S.A. All rights reserved.