Computer simulation was used to investigate the defect and transport properties of the oxygen-ion conductor. A wide variety of low-valence metal ions were substituted into zirconia, and the solution energetics were investigated. Favourable dopants were predicted on energetic grounds, and included CaO, Y2O3, Gd2O3 and Sc2O3; in agreement with observation. Dopant-vacancy clusters were examined, and the results revealed trends in dopant ion size plus significant local atomic relaxation. The simulations were extended to Nb/Y co-doping. Oxygen ion diffusion in yttria-stabilised zirconia was studied using molecular dynamics techniques. The results supported models in which diffusion was mediated by oxygen vacancies, with the calculated diffusion coefficients and activation energies being in accord with tracer diffusion studies.

Cation Doping and Oxygen Diffusion in Zirconia: a Combined Atomistic Simulation and Molecular Dynamics Study. Khan, M.S., Islam, M.S., Bates, D.R.: Journal of Materials Chemistry, 1998, 8[10], 2299-307