ABSTRACT
A molecular dynamics simulation was used to investigate the structural and transport properties of a (Ba0.5-xSrx)La0.5InO3-δ (x = 0, 0.1, 0.2) oxygen ion conductor. Previous studies reported that the ionic conductivity of Ba-doped LaInO3 decreases because Ba dopant forms a narrow oxygen path in the lattice, which could hinder the diffusion of oxygen ions. In this study, we reveal the mechanism to improve ionic conductivity by Ba and Sr co-doping on an La site in LaInO3 perovskite oxide. The results show that the ionic conductivity of (Ba0.5-xSrx)La0.5InO3-δ increases with an increasing number of Sr ions because oxygen diffusion paths which contain Sr ions have a larger critical radius than those containing Ba ions. The radial distribution function (RDF) calculations show that the peak heights in compositions including Sr ions were lower and broadened, meaning that the oxygen ions moved easily into other oxygen sites.
ABSTRACT
The oxygen ion conduction behavior of an orthorhombic perovskite oxide Ba-doped LaInO3 was evaluated by molecular dynamics simulation. Comparative calculations for cubic and the orthorhombic models show that the orthorhombic model was in better agreement with the experimental results with respect to both ionic conductivity and activation energy. The results of the radial distribution function for O-O pair provided and explanation for why the ionic conductivity of cubic perovskite is higher than that of orthorhombic perovskite. The orthorhombic model has a higher peak intensity of O-O pair than the cubic model, it means that the orthorhombic model has a smaller number of oxygen-vacancy pairs in the lattice structure. Consequently, the ionic conductivity of orthorhombic perovskite is lower than that of cubic perovskite due to less conduction path.
