Hydrogen absorption in beryllium substituted Mg2Ni

The alloys Mg₂Ni_1–xBe_x (x = 0.15 and 0.25) retain the Mg₂Ni structure showing a lattice dilation proportional to the beryllium content. The pressure-composition isotherms are reported for the dissociation of hydrided samples. The results suggest that there are two type of interstices able to absorb up to 4 H atoms per formula unit. The heats of formation obtained from the van't Hoff relationship show an increased stability for the hydrides of the beryllium substituted alloys compared to the pure Mg₂Ni. The results suggest that the electronic factors are more important for hydride stability than variations in the unit cell volume.