Effect of Water Content on the Electrical Conductivity of Na ₂ O≅3SiO ₂ Glass

Abstract

Na 2 O–3SiO 2 glasses with up to ≅12 wt% water were prepared under high‐pressure, hydrothermal conditions and their electrical conductivities were measured. The conductivity (σ) was found to depend on H 2 O content in a manner similar to the “mixed‐alkali” effect. At constant temperature, σ decreased initially with increasing H 2 O content to a minimum at 3≅4 wt% H 2 O and increased with further increase in water content. Infrared spectroanalysis of these glasses was made to determine the type of water present in the glass and the results were interpreted in the context of the measured activation energy and preexponential factor of dc conductivity. The sodium ion diffusion coefficient for a glass containing 0.76 wt% H 2 O was less than that of water‐free glass and in agreement with the electrical conductivity results.