Effect of devitrification on the ionic diffusion of Li-disilicate

A simple theoretical model has been developed for describing the variation of diffusion of ions in an initially homogeneous glass as it transforms into a two-phase structure. The model is applicable to those microstructures in which the second phase grows as a discontinuous dispersion without affecting the diffusion properties of the glassy matrix. The validity of the model is demonstrated by the measurement of ionic conductivity and of diffusion-induced 7Li nuclear spin relaxation during the devitrification of Li-disilicate, containing 0 and 1 mol% P2O5, respectively. Evaluation of the data yields the basic parameters of devitrification.