Conductivity spectra of sodium fluorozirconate glasses

Abstract

We have reported conductivity spectra at different temperatures for fluoride glasses of compositions 0.50ZrF₄-(0.40-x)BaF₂-0.10YF₃-xNaF in the frequency range from 10 Hz to 2 MHz. We have analyzed the spectra using conductivity formalism and obtained the frequency exponent, concentration, and hopping frequency of charge carriers (F^- ions) from the analysis. We have observed that the concentration of charge carriers is almost independent of temperature, but weakly dependent on composition, and the conductivity is essentially determined by the hopping frequency, i.e., the mobility. The frequency exponent is independent of temperature, but it shows very weak composition dependence. We have also presented a scaling of the conductivity spectra, which implies that the relaxation dynamics of charge carriers in fluoride glasses is independent of temperature and composition.