Percolation model for the anomalous conductivity of fluorite-related oxides

The Monte Carlo simulation technique has been used to study the anomalous conductivity of aliovalently doped fluorite-related oxides. In order to investigate the effect of the interaction between the dopants and the oxygen vacancies on the transport behavior, three simple model interactions have been tested: Nearest-neighbor attraction, nearest-neighbor repulsion, and a barrier model, which is based on the assumption of a reduced oxygen mobility in the neighborhood of the dopants. We find that percolation theory is essential to correlate the local interactions and the long-range mobility of the ions. Our numerical results show that satisfactory agreement with experiment can be obtained only for the barrier model.