AMoO₄ (A = Mg, Ni) molybdates: Phase stabilities, electronic structures and chemical bonding properties from first principles

Samir F. Matar (1) , Alain Largeteau (1) , Gérard Demazeau (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

Stability of different phases of AMoO₄ (A = Mg, Ni) molybdates versus A–O bonding and the corresponding electronic structures are examined from first principles. The energy-volume equations of state for three forms (β, α, ω), characterized by decreasing volumes in the sequence of Mg and Ni molybdates are established. While NiMoO₄ is energy stabilized in the sequence β → α → ω, an opposite behavior is identified for the Mg molybdate. Charge analysis characterizing ionic Mg²⁺ versus covalent Ni^+1.2 behaviors can explain the trend. Electronic band structure also shows large differences: MgMoO₄ is insulating with a 2 eV band gap while in a magnetic state, NiMoO₄ is a small gap (0.2 eV) semi-conductor. Chemical bonding properties show weak Mg and strong Ni bonding with oxygen, while identifying the Mo–O interaction as prevailing.

Mots clés: Molybdates; DFT; GGA; VASP; ASW

Domaines: Matériaux

Samir F. Matar, Alain Largeteau, Gérard Demazeau. AMoO₄ (A = Mg, Ni) molybdates: Phase stabilities, electronic structures and chemical bonding properties from first principles. Solid State Sciences, 2010, 12 (10), pp.1779-1785. ⟨10.1016/j.solidstatesciences.2010.07.030⟩. ⟨hal-00530392⟩