Mixed alkali effects in ionic conductors: a new model and computer simulations

A new model theory of the mixed alkali effect that is consistent with the most recent EXAFS data of cation environments in mixed alkali silicate glass is presented. The dynamics of ion transport and the memory effects of site occupancy are brought out by computer simulations based on the model in an infinite percolation cluster. The salient features of the mixed alkali effect in the diffusion coefficients of the two cations are reproduced in the results of computer simulations.