Estimation of the free-charge-carrier concentration in fast-ion conducting Na2S-B2S3 glasses from an analysis of the frequency-dependent conductivity

Abstract

Ac and dc conductivities of fast-ion conducting x${\mathrm{Na}}_2$S+(1-x)${\mathrm{B}}_2$ ${\mathrm{S}}_3$ glasses in the composition range 0.001≤x≤0.1 were analyzed using the Almond-West formula σ(ν)=${\mathrm{\sigma }}_{\mathrm{dc}}$[1+(ν/${\nu }_{\mathit{H}}$ ${)}^{\mathrm{\alpha }}$]. The hopping frequency for free charge carriers ${\nu }_{\mathit{H}}$, the dc conductivity ${\mathrm{\sigma }}_{\mathrm{dc}}$, and their respective activation energies were determined. The concentration of free charge carriers evaluated from the conductivities and estimated mobilities is in good agreement with the overall content of sodium cations in the glasses and it is proposed that this supports the concept of a strong and not weak electrolyte model for these fast-ion conducting glasses.