Effect of ionic polarizability on oxygen diffusion in δ-Bi2O3 from atomistic simulation

The effect of polarizability of cation dopants on oxygen diffusion in delta-Bi2O3 is determined using molecular-dynamics simulation in which the polarizability of the ions is treated within the shell model. It is found that the magnitude of the oxygen polarizability has no affect on diffusion. However, the high cation polarizability, associated with the lone pair of electrons in Bi, is found to be the key to achieving sustained oxygen diffusion. Consistent with earlier experimental results, the oxygen diffusion path is found to be between oxygen equilibrium sites, which are displaced from the 8c oxygen sites of the fluorite lattice.