A DFT study of hydrogen storage in Zr(Cr0.5Ni0.5)2 Laves phase

Abstract

Theoretical studies on the total energy, electronic structure and bond of Zr(Cr0.5Ni0.5) 2 intermetallic compound and its hydrides were performed using density functional calculations. The optimized c/a ratio was found in good agreement with experimental data of the C14 Laves phase. When hydrogen is introduced in the AB2 matrix (A = Zr; B = Ni, Cr) the A2B2 sites are preferentially occupied in the structure, followed by the AB3 while B4 remains empty. The volume of the intermetallic increases up to 52.19% when 28H are absorbed in the unit cell, whereas the binding energy remains practically the same up to −6.76 eV/H, indicating little interaction. Among hydrogenations the main contribution to density of states is due to d electrons of all components of the structure. H-metal bonding is detected in the range −8 to −6 eV. Above 8H the magnetic moment increases with respect to the pure Laves phase.