Incorporation of water into glasses and its influence on the diffusion of cations, including the creation of diffusion barriers

When heated to elevated temperatures, many glasses take up water from moisture-containing environments. This leads not only to changes in local water concentrations, but also to non-uniform structural changes within the glass. These structural changes impact many structure-sensitive properties, including the diffusivity of ions. Experimental data for the uptake of water by a Type I silica glass, Infrasil 302, and by an alkaline-earth boroaluminosilicate glass, Corning Code 1737, are discussed as well as the influence of the incorporation of water into these glasses on the diffusion of sodium. Furthermore, the modification of glass near the surface by the uptake of water, leading in the case of the alkaline-earth boroaluminosilicate glass to the creation of a very effective barrier layer against the diffusion of sodium, is addressed.