Hydriding properties of LaNi3 and CaNi3 and their substitutes with PuNi3-type structure

The PuNi3-type intermetallic compounds LaNi3, CaNi3, La0.5Ca0.5Ni3, LaCaMgNi9, La0.5Ca1.5MgNi9, CaTiMgNi9, LaCaMgNi6Al3 and LaCaMgNi6Mn3 have been prepared using a powder-metallurgy-sintering method. The hydrogenation behaviour of these materials has been studied through the gas-solid reaction. The as-prepared compounds were easily activated at room temperature under a hydrogen pressure of 3.3 MPa. The pressure-composition-temperature (P-C-T) curves show a single plateau region with the exception of LaNi3-H, which shows no plateau, and La0.5Ca1.5MgNi9-H, which shows two plateaus. All of these alloys can absorb/desorb hydrogen by 1.8 wt.% under the conditions studied. X-ray diffraction (XRD) analysis reveals that LaNi3H4.5 is in the amorphous state, and the other hydrides are accompanied by different expansions of the unit cell volume of the host alloy. (C) 2000 Elsevier Science S.A. All rights reserved.