Low-Temperature Depolarization Peaks in Alkali Silicate Glass

Abstract

Thermally-stimulated depolarization current measurements were carried out on Li2O·2SiO2 and (Li2O·Na2O)1/2·2SiO2 glasses. In lithium disilicate glass, the low-temperature peak, which previously was considered to be single, was shown to be a composite of two overlapping peaks; one, the 210-214 K peak, being due to conduction polarization and the other, of unknown origin, being dominant at higher polarization temperatures. It was found that the low-temperature (180 K) peak in lithium-sodium disilicate glass is not due to conduction polarization and that, even when alkali-nonbridging oxygen or impurity-related dipoles are responsible for the peak, those dipoles are not free to rotate, but move in a restricted fashion.