Three coupled rate equations of mismatch-generated relaxation were presented for the accommodation and transport of ions concept that described the ion dynamics in ion-conducting glasses. This simultaneously yielded scaled conductivity and permittivity spectra. The model spectra were compared with experimental spectra for xNa2O(1-x)GeO2 glasses; with x = 0.0513, 0.0902 or 0.213. This permitted an estimation of the long-term limit of the localized rms displacement; roughly interpreted as being the average size of the ion cage before the dynamics became diffusive. An approximate x−1/3 dependence of this quantity was obtained for the 3 compositions considered. This implied that the ion dynamics were governed largely by Coulomb interactions between the mobile ions.

Dielectric Function and Localized Diffusion in Ion Conducting Glasses. R.D.Banhatti, K.Funke: Solid State Ionics, 2004, 175[1-4], 661-3