Two approaches to studying diffusion and segregation at the surfaces of oxides and ceramics were demonstrated. When simulating surface diffusion, the activation barriers were often so high that the timescales required for direct simulation by molecular dynamics were too long. It was shown that a combination of temperature-accelerated dynamics and kinetic Monte Carlo methods, could access the required time-scales without having to guess which was the predominant process. It was shown that exchange mechanisms and correlated ion motions were surprisingly important to surface and near-surface diffusion in these ionic systems. Another, exchange Monte Carlo, approach was used to study equilibrium segregation in thin ceramic films; with application to MgO/MnO. The surface concentrations, as a function of temperature and film composition, were determined directly from the simulations. For all of the compositions studied, the {001} surface was Mn2+-rich and the occupancy of sites by Mn2+ decreased rapidly with depth.

Atomistic Simulations of Surface Diffusion and Segregation in Ceramics. M.Y.Lavrentiev, N.L.Allan, J.H.Harding, D.J.Harris, J.A.Purton: Computational Materials Science, 2006, 36[1-2], 54-9