A model of diffusion accounting for a distribution of barriers heights was developed. It was demonstrated that activation energy of diffusion depended on the maximal height of barrier that was to be overcome, not on the average height of barriers. The temperature dependence of diffusivity (respectively of ion conductivity) declines from strict Arrhenius behaviour, although the declination was not as strong as in the case of shear viscosity. As the determination of the maximal height of the barriers that must be overcome was a percolation problem, diffusion to short (in molecular scale) distances was at ease as compared to diffusion to macroscopic distances.

Diffusion Coefficient of Foreign Particles in Glass-Forming Melts. I.Avramov: Journal of Non-Crystalline Solids, 2008, 354[14], 1537-40