Simulations were made of a fast ion conductor having the pyrochlore structure. Calculations of the mean temperature-dependent diffusion coefficients were used to obtain activation energies for diffusion which were compared with values obtained from static lattice calculations and from conductivity measurements. Simulations of yttrium and gadolinium doped zirconia were performed as a test of the potential parameters and the results compared well with experiment. The gadolinium zirconate simulations showed no diffusion, for the ordered material, which was consistent with static lattice calculations. Appreciable diffusion was predicted for simulations which incorporated cation disorder or doping with calcium, where the present results agreed well with those resulting from static lattice simulations and from experimental observations. It was found that diffusion occurred only via the 48f sites, in line with previous computational and experimental studies. An increase in the activation energy for diffusion with doping level suggested that dopant/vacancy and defect-defect interactions became significant at the higher level of doping.

Molecular Dynamics Study of the Effect of Doping and Disorder on Diffusion in Gadolinium Zirconate. Wilde, P.J., Catlow, C.R.A.: Solid State Ionics, 1998, 112[3-4], 185-95