Dielectric Relaxation in High-Silica Borosilicate Glasses

Borosilicate glasses with high silica and varying water content were made by a process similar to that of Vycor. Dielectric relaxation measurements show a de-conduction activation energy equal to that of fused silica, no apparent dependence of the dc conductivity on water content, and an unexpectedly narrow relaxation-time distribution equivalent to a simple RC circuit element. A single relaxation process is observed in all samples regardless of water content and neither the conductivity nor the activation energy are significantly altered by a 50-fold change in water content.