Diffusion in the System K2O‐SrO‐SiO2: II, Cation Self‐Diffusion Coefficients*

Abstract

Cation self‐diffusion coefficients were measured in the system 0.2K2O‐0.2SrO‐0.6SiO2 (wt fraction) by introducing a slab of glass previously irradiated in a reactor between two slabs of unirradiated glass. By heating the specimens for various times at temperatures above Tg, etching them sequentially, and counting the β‐ and γ‐activity, self‐diffusion coefficients for K and Sr were measured, and an upper limit for that of Si was estimated. At 530°C<T<830°C, DK≅36.5 exp (‐40,800/RT) and DSr≅0.17 exp (‐42,700/RT), although the fit to Arrhenius behavior was poor. At 750°C, the self‐diffusion coefficient for the Na impurity was almost the same as that for K, whereas that of Si was less than that of Sr.