Local structure analysis on (La,Ba)(Ga,Mg)O3−δ by the pair distribution function method using a neutron source and density functional theory calculations

In this work, we focused on La0.95Ba0.05Ga0.8Mg0.2O3−δ with the perovskite structure, and investigated the local structure around the oxygen vacancy by pair distribution function (PDF) method and density functional theory (DFT) calculation. By comparing the G(r) simulated based on the DFT calculation and the experimentally-observed G(r), it was suggested that the oxygen vacancy was trapped by Ba2+ at the La3+ site at least at room temperature. Such a defect association may be one of the reasons why the La0.95Ba0.05Ga0.8Mg0.2O3-δ showed lower oxide-ion conductivity than (La,Sr)(Ga,Mg)O3−δ which was widely-used as an electrolyte of the solid oxide fuel cell.