The Monte Carlo simulation technique was used to study the anomalous conductivity of aliovalently doped fluorite-related oxides. In order to investigate the effect of interactions between dopants and O vacancies, 3 simple model interactions were tested. These were: nearest-neighbor attraction, nearest-neighbor repulsion, and a barrier model which was based upon the assumption of a reduced O mobility in the neighborhood of the dopants. It was found that percolation theory was essential for correlating local interactions and long-range mobilities of the ions. Numerical results showed that satisfactory agreement with experiment could be obtained only in the case of the barrier model.

M.Meyer, N.Nicoloso, V.Jaenisch: Physical Review B, 1997, 56[10], 5961-6