关键词: Mg2Ni合金, 储氢合金, 取代, 第一性原理, 密度泛函理论

Abstract: The crystal and electronic structures of magnesium-based hydrogen storage alloy Mg2Ni, palladium substituted alloys Mg12Ni6-xPdx(x=1, 2, 3), and their hydrides H2-Mg12Ni6-xPdx (x=0, 1, 2, 3) have been calculated from first-principles density functional theory. Results show that the sizes of primitive cell of the intermetallic alloys and hydrides were increased by substitution of Ni with Pd. Also, the interactions of Mg-Ni and Ni-Ni were affected by the substitution, but the influence is not so much. There are greater deformation and volume increase of the crystal cell after the alloy hydrogenation, which favor the hydrogen diffusion in the bulk. The substitution of Ni located in 3d with Pd atom leads Pd-H bonding interaction to be weaker than the original Ni-H bond, and also leads to the weakening of the neighboring Ni-H bond located in 3b. So the substitution can make hydrogen release more easily and reduce the dehydrogenation temperature.

Key words: Mg2Ni alloy, Hydrogen storage alloy, Substitution, First-principle, Density functional theory