Drastic changes of electronic, magnetic, mechanical and bonding properties in Zr2Co by hydrogenation

Hydrogen insertion into Zr2Co intermetallic leading to Zr2CoH5, is shown to bring large effects in the electronic and magnetic structure and chemical bonding properties besides the experimentally evidenced crystal symmetry changes due to hydrogen ordering. From energy–volume equation of state and elastic constants, Zr2CoH5 is identified more cohesive, harder and less ductile than Zr2Co due to the Zr/Co–H interaction. Hydrogen at two sites is contained into Zr4 and Zr3Co tetrahedra and binds with Zr and Co with dominant covalent Co–H. Within square pyramidal CoH4 motifs non bonding Co- d z 2 polarize magnetically leading to ferromagnetic ground state contrary to non-magnetic binary intermetallic.