Ion relaxation dynamics in 0.5Li2O-0.5Na2O-2B2O3 (LiNaB4O7) glasses

TL;DR

This study investigates the dielectric and electrical relaxation properties of LNBO glasses, revealing temperature-dependent anomalies and deviations from universal conductivity scaling due to mixed alkali effects.

Contribution

It provides a detailed analysis of ion relaxation dynamics and dielectric behavior in LNBO glasses, highlighting the impact of mixed alkali effects on conductivity scaling.

Findings

Dielectric constant and loss increase with temperature, showing anomalies near glass transition.

Electrical conductivity obeys Jonscher's law and deviates from Summerfield scaling.

Electric modulus spectra fit Kohlrausch-Williams-Watts model with a temperature-independent exponent.

Abstract

The frequency and temperature dependence of the dielectric constant, electric modulus and electrical conductivity of the transparent glasses in the composition 0.5Li2O-0.5Na2O-2B2O3 (LNBO) were investigated in the 100 Hz - 10 MHz frequency range. The dielectric data have been analyzed using Cole-Cole equation with an addition of the conductivity term. The electrical conductivity was found to be obeying Jonscher's universal law. The dielectric constant and the loss for the as-quenched glasses increased with increasing temperature, exhibiting anomalies in the vicinity of the glass transition and crystallization temperatures. The bulk DC conductivity at various temperatures was extracted from the electrical relaxation data. Conductivity plots were not found to follow Summerfield scaling due to mixed alkali effect. The imaginary part of electric modulus spectra was modeled using an approximate solution of Kohlrausch-Williams-Watts (KWW) relation. The stretching exponent, {\beta}, was found to be 0.56 and temperature independent.