A consistent set of pair potentials has been derived empirically by fitting to the experimentally measured lattice properties of a series of binary metal oxides. In contrast to previous strategies, the potential parameters required to reproduce the experimental lattice properties of all the chosen compounds were optimised concurrently, utilising residuals from all structures in the series, each calculated from the energy-minimised geometry. A more reliable determination of ion polarisabilities can thus be made.

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Computer simulation techniques have been used to model cubic CeO2−ZrO2 solid solutions in the whole composition range. Aspects related with the oxygen storage capacity of these materials are emphasized. The energetics of the Ce4+/Ce3+ bulk reduction reaction as well as the activation energy for oxygen migration in the lattice are investigated and compared with the corresponding quantities in pure CeO2. It is found that even small additions of ZrO2 decrease the bulk reduction energy of Ce4+ to values comparable to those reported for surface reduction in pure CeO2. Activation energy calculations indicate an almost monotonic increase of oxygen mobility with increasing zirconia content.

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Quantum mechanical techniques based on density functional theory have been used to investigate the mechanism and energetics of proton transport in the perovskite-structured CaZrO3. The calculations demonstrate that the observed orthorhombic crystal structure (comprised of tilting [ZrO6] octahedra) is reproduced accurately. Quantum mechanical molecular dynamics simulations confirm that the diffusion mechanism involves proton transfer from one oxygen ion to the next (Grötthuss-type mechanism) and also indicate the importance of the vibrational dynamics of the oxygen sublattice. For each hopping event, the oxygen−oxygen distance contracts to about 2.4−2.5 Å so as to assist proton transfer. By exploration of the energy profiles for proton transfer, a very low energy barrier is found for the O(1)−O(1) interoctahedra path. However, long-range proton conduction may involve O(1)−O(2) proton transfer as the rate-limiting step with a calculated energy barrier of 0.74 eV. Binding energies for hydroxyl−dopant pairs involving Ga3+, Sc3+, and In3+ dopant ions are predicted to be favorable and are compatible with observed proton “trapping” energies from previous muon spin relaxation and quasi-elastic neutron scattering experiments.