Drastic changes in the electronic and magnetic structures of hydrogenated U2Ti intermetallic from first principles

Based on DFT calculations, hydrogen insertion in U2Ti intermetallic with AlB2-type structure leading to U2TiH3 with sites identified from energy discrimination between different hypotheses is found to decrease the cohesive energy through weakening of the Ti-U bonds, to expand the lattice along c hexagonal axis due to strong U-U in-plane bonding and to induce iono-covalent character with H−0.65. The anisotropic volume expansion involves a strong localization of out-of-plane uranium fz3-3zr2 orbitals leading to developing a magnetic moment on uranium in a predicted ferromagnetic ground state, opposite to non-magnetic intermetallic.