Electronic structures of trivalent cations doped bulk and cubic La2Mo2O9 oxide ion conductors

Abstract

Effect of intrinsic oxygen vacancies and different dopants such as Bi, Er and Y on the electronic structure of La2Mo2O9 have been studied in the framework of density functional theory using plane-wave pseudopotential method. First principles electronic structure calculations are performed using GGA exchange correlation functional to estimate the density of states and bands structures. Our calculated electronic density of states and band structures show that these systems are semiconductors with an indirect band gap ~ 2 ​eV. Electronic band gap increases with the increasing concentration of Bi, unlikely with that of Er and Y. O-2p and Mo-4d orbitals are mainly responsible for tuning the band gap. Bi remains the most electron donating character, whereas both Er and Y play the role of electron acceptors as evident from partial charge distribution plots and Bader charge analyses. Ionic bonds are observed for La, Bi, Er, and Y with O, but the bonds between Mo and O are covalent in nature for all these compounds.