The effect of molecular water on proton conduction was quantitatively analyzed from conductivity measurements of silica glasses with and without water molecules. The activation energy for conduction linearly decreased with increasing logarithm of proton concentration for glasses containing only protons as charge carriers and as the logarithm of the product of proton and water concentration for glasses containing both proton and water. Electrical conduction in glasses containing both protons and water molecules is associated with proton hopping between hydroxyl and water molecules and its activation energy is related to the energy necessary for the dissociation of the proton from OH and ${\mathrm{H}}_2$O.

• Received 21 November 1996

DOI:https://doi.org/10.1103/PhysRevB.55.12108