Ionic conductivity and relaxation dynamics in lithium tellurite glasses

Abstract

The ionic conductivity and relaxation in the lithium tellurite glasses with varying ${\mathrm{Li}}_2\mathrm{O}$ content have been investigated in the frequency range 10 Hz to 2 MHz and in the temperature range from 373 K to just below the glass transition temperature. The composition dependences of the dc conductivity and the activation energy of these glasses have been compared with those of other glasses formed with traditional network formers such as ${\mathrm{B}}_2{\mathrm{O}}_3$, ${\mathrm{P}}_2{\mathrm{O}}_5,$ and ${\mathrm{SiO}}_2$ containing the same ${\mathrm{Li}}^{+}$ ions as modifiers and explained in terms of composition dependent network structure of these glasses. The frequency-dependent electrical data have been analyzed in the framework of the conductivity and modulus formalisms. Both these formalisms have provided for qualitative similarities in the compositional variation of the relaxation times, interaction between the cations, and the dc conductivity. The finite frequency window has been suggested as the reason for the difference between the numerical values of the stretched exponent β obtained from the modulus formalism and the values of $\left(1\mathrm{}-n\right)$ obtained from the conductivity formalism.