Electronic structure and bonding of the hydrides Mg3TH7 (T = Mn, Re) from first principles

Samir F. Matar (1) , Michel Nakhl (2) , Mirvat Zakhour (2)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 LCPM - Laboratoire de Chimie Physique des Matériaux

From pseudo-potentials and all-electrons computations within density functional theory, desorption energies within range of MgH2 and covalent like hydrogenated intermetallic compounds are identified for hydrogen rich Mg3TH7, (T = Mn, Re). The rhenium based compound is found with a lower desorption energy which has been quantified from the analysis of the Bader charges within the {TH6}5- complex anion as related with a decreasingly ionic charge on hydrogen from Mn to Re. The electronic densities of states show insulating compounds in agreement with literature relevant to this class of salt-like hydrides with a larger band gap for the Re compound. From chemical bonding analyses stronger Mn-H bonding versus Re-H is identified in agreement with desorption energies magnitudes favoring Mg3ReH7.

Mots clés: Hydrogen; Salt-like hydrides; DFT; Chemical bonding; Electronicstructures; Bader charge

Domaines: Matériaux

Samir F. Matar, Michel Nakhl, Mirvat Zakhour. Electronic structure and bonding of the hydrides Mg3TH7 (T = Mn, Re) from first principles. Solid State Sciences, 2012, 14 (5), pp.639-643. ⟨10.1016/j.solidstatesciences.2012.03.001⟩. ⟨hal-00688044⟩