DFT+U study of the oxide-ion conductor pentalanthanum hexamolybdenum henicosaoxide

By means of first-principles calculations, the structural, elastic, electronic, magnetic and optical properties of pentalanthanum hexamolybdenum henicosaoxide (La5Mo6O21) were studied in detail. No experimental or theoretical investigations of its physical properties have previously been reported in the literature. Our results reveal that La5Mo6O21 is metallic with high ionic character due to the oxygen composition. The bonding characterization was achieved by analysis of valence charge density and the electronic localized functions. Flexibility and ease of deformation of the tetrahedral units appears to be important for the ion conduction mechanisms. The magnetic moment was evaluated to be 8.03 μB, principally induced by Mo d-orbitals and La f-orbitals and the polarization of the oxygen by molybdenum. The optical spectra were analyzed by means of the electronic structure. The future advances will depend on achieving a fundamental understanding of the structural, defect and mechanistic features of ion conducting materials.