Effect of local environment on stretching parameter in the mixed alkali oxyfluoro vanadate glasses: electrical modulus and structural analysis

Abstract

A structural and electrical modulus study on the mixed alkali glass samples having general formula (in mol%) 40V2O5 − 30BaF2 − (30 − x) LiF – xRbF, where x = 0 – 30, in steps of 5 mol% is presented in this communication. Various vibrational bands were identified in the infrared spectra spanning 400–1200 cm−1. On the basis of shift in these bands, it was inferred that the glass network undergoes a noticeable change after 50 mol% of rubidium content. The analysis of the electrical modulus data is carried out using Kohlrausch-Williams-Watts (KWW) equation which describes the relaxation behavior of the mobile species. The variation of stretching parameter β with respect to alkali element concentration is analyzed on the basis of a combined effect of alkali ion distance and molar volume. It is found that the coupling between the mobile ions is better at 50 mol% of the alkali mixture when compared with single alkali concentrations. The contributions from fast and slow types of relaxation mechanisms were determined.