Ionic Mobility and Dielectric Relaxation in Glass-Forming Mixtures of Sodium Chloride and Glycerol

Abstract

Measurements of electrical conductivities of liquid and supercooled liquid NaCl–glycerol solutions were carried out between +42° and −87°C. Time-domain measurements of dielectric relaxation in pure glycerol and in NaCl–glycerol solutions between −78 and −89.9°C are described. The transient response data were fitted to the empirical Davidson–Cole response model. The specific conductivity data show a non-Arrhenius behavior near the glass-transition temperature and is well described by the Vogel–Tammann–Fulcher (VTF) law, which also fits the dielectric relaxation time data. The Vogel–Fulcher divergence temperature is consistent with the Kauzmann temperature. The dielectric relaxation time is increased significantly by the addition of sodium chloride, whereas the static relative permittivity decreases linearly with concentration, indicating that NaCl has a “structure-making” effect on the structure of glycerol.