The Mechanism Elucidation of Oxide Ion Conduction in the Perovskite-Type Iron Oxide of SrFeO3

The mechanism of the oxide ion conduction in the perovskite-type iron oxide of SrFeO3 was investigated by the quantum chemical calculation based on hybrid-density functional theory. It is known that the existence of oxygen vacancy is responsible for the oxide ion conduction. The oxygen vacancy doped cluster model such as Fe4O3 model was constructed for the investigation. It was found that the oxygen vacancy induces the spin on oxygens around oxygen vacancy. When the oxide ion percolated on the FeO2 layer of SrFeO3, the path of the sigma-type antiferromagnetic superexchange interactions between 3d(x)(-y)(2)(2) orbitals of irons via 2p orbital of oxygen varied. In the obtained potential energy curve displacing the oxide ion, the local maximum point was given, due to the ionic repulsion between the conductive oxide ion and other oxygens. The activation energy for the oxide ion conduction was estimated to be 2.05eV.