Molecular dynamics simulations of the oxygen ion diffusion in samaria-stabilized zirconia

Oxygen ion diffusion in 10 mol% samaria-stabilized zirconia (SmSZ) at different temperatures is studied employing molecular dynamics simulations. The diffusion and superionic conduction in SmSZ takes place due to the discrete hopping process of oxygen ions. Even though discrete hopping of one or two oxygen ions starts at about 850 K, onset of superionic conduction occurs at about 1400 K when almost all the oxygen ions participate in the hopping process. The activation energy for oxygen ion diffusion is found to be 67.23 kJ mol-1. Radial distribution functions, g(r) show that the reduction in, broadening and shifting of the peaks in g(r) for all ionic pairs, at higher temperatures, indicate a volume expansion of the crystal. (author)