Hydrogenation process of the Gd3M (M = Ni or Co) intermetallics compound

It is known that rare earth elements and also many rare earth intermetallic compounds absorb large amounts of hydrogen. The reaction of the intermetallic Gd3M (M = Co Or Ni) compounds with hydrogen was studied. The transformation of the crystal structure of the parent Gd3M sample after subsequent stages of the hydrogenation was investigated by X-ray diffraction. It was found that both intermetallic compounds (Gd3Ni and Gd3Co) are thermodynamically unstable during hydrogenation decomposing into the gadolinium hydrides and the transition metal. It is very probable that, in the case of Gd3Ni, nickel plays the role of a catalyst in the formation of GdH3 in the low temperature range, whereas in the case of Gd3Co the transition metal (Co) is rather inactive.