Effect of Heat Treatment on the Na ⁺ Resistivity of Vitreous Silica

Abstract

The dc resistivity of fused quartz with respect to Na + ions was measured at temperatures up to 750°C, using β‐alumina as the sodium source. Heat treatment in air at 1100°C gave minima in resistivity at times which depended on the choice of either a high‐OH or a low‐OH glass. The initial fall in resistivity is explained by the stabilization of the glass to a more open structure and the later increase is attributed to a blocking effect of “permanent” hydroxyl groups, which slowly enter the glass as atmospheric water.