Molecular dynamics simulation of the effect of size, crystallite shape, and defect on oxygen diffusion in SrTiO3

In this work, the influence of oxygen vacancy defects, crystallite shape and size on oxygen diffusion in SrTiO3 nanocubes and nanowires has been studied by molecular dynamics simulation method. The SrTiO3 nanocubes with different sizes and nanowires with different lengths and axial direction of [001], were considered for this purpose. The oxygen vacancies ranging from 0 to 5% were created by random deletion of oxygen atoms from perfect SrTiO3 structure. All of the simulations have been performed at 1000K and atmospheric pressure by using Buckingham + columbic potential. The diffusion process of oxygen atoms was investigated by analyzing the mean square displacement curves. The achieved oxygen diffusion coefficients have a good agreement with experimental reports. In addition the results show that diffusion constant of oxygen atoms in individual nanocubes are increased by decreasing the size of nanocubes. The results also show that in individual SrTiO3 nanowires, the oxygen diffusion process is increased by increasing the length of the nanowires.