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 int o a two-phase structure. The model is applicable to those microstructures i n which the second phase grows as a discontinuous dispersion without affect ing the diffusion properties of the glassy matrix. The validity of the mode l is demonstrated by the measurement of ionic conductivity and of diffusion -induced Li-7 nuclear spin relaxation during the devitrification of Li-disi licate, containing 0 and 1 mol% P2O5, respectively. Evaluation of the data yields the basic parameters of devitrification. (C) 2000 Elsevier Science B .V. All rights reserved.