Correlation between conductivity and free volume in rubidium and cesium silicate glasses

Abstract

Following recent finding published in this journal it is shown that using conductivity and molar volume in binary rubidium and cesium silicate glasses, both measured at room temperature, a common cubic scaling relation was found between them due to increase in alkali content. The drastic drop in conductivity up to 15 orders of magnitude for so many ion-conducting binary alkali silicate glasses (and in wide composition range) is then mainly caused by the structure and the ion content. In particular, it is suggested that the glass network expansion, which is related to the available free volume, is a parameter that could explain the increase in ionic conductivity for these binary systems.