CALCULATION OF THE ACTIVATION-ENERGY FOR IONIC-CONDUCTION IN GLASSES

A simple, classical method is described to calculate the ionic conductivity activation energies for glasses, superceding the approach of Anderson and Stuart. Coulombic, polarization, repulsion and strain-energy terms in the interaction potential are taken into account: it is found that, at very low ion concentrations, the Coulombic term predominates, and the activation energy is high, while at high ion contents the polarization term is dominant and the activation energy is much lower. Thus the decrease of the conductivity activation energy with increasing ion content is naturally explained by the model, as is the decrease in activation energy for sulphide-based glasses compared with oxides.