It was recalled that mixed ß/ß"-alumina crystals were 2-dimensional ion conductors whose conductivities varied markedly upon mixing 2 types of mobile ion. A theoretical model was described which could explain the conductivity variations in a quantitative manner. According to this model, percolation effects were expected to occur at intermediate mixing ratios and low temperatures. It was suggested that detailed measurements might detect these effects and thus permit measurement of the critical transport exponents which were predicted by percolation theory.

Percolation Effects in Mixed Alumina Crystals. P.Maass, M.Meyer, A.Bunde: Physica A, 1999, 266[1-4], 197-202