Diffusion and Ionic Conduction in Soda-Lime Silicate Glasses and in Alkali Borate Glasses

This paper reviews typical results of tracer diffusion and ionic conduction in soda-lime silicate glass and in single-alkali and mixed-alkali borate glass obtained in our laboratory and published in detail elsewhere. We have studied tracer diffusion of modifier cations and ionic conduction as functions of composition, temperature and, in the case of borate glass, also as function of pressure. We compare tracer diffusion with charge diffusion and in the case of soda-lime glass also with viscosity diffusion. The Haven ratios for soda-lime glass are temperature independent. For sodium borate glass the Haven ratio is almost temperature- and pressure-independent, whereas it decreases significantly with decreasing temperature and increasing pressure for rubidium borate glass. It also decreases with increasing alkali content. We attribute these facts to collective atomic jump events, in which several ions move simultaneously in a string-like or chain-like fashion. We also illustrate the mixed-alkali effect, which was studied by conductivity measurements and by tracer diffusion for mixed sodium-rubidium borate glasses.