Ultrasonic attenuation at low temperature of TeO2-V2O5 glasses

Investigations are reported on the dependence of longitudinal ultrasonic attenuation on temperature in tellurite glasses containing vanadium pentoxide with different concentrations. The pulse echo technique was applied at ultrasonic frequencies 2, 4, 6, and 8 MHz, in the temperature range between 100 and 300 K. The results showed well-defined peak whose position shifts towards higher temperature with increasing frequency. The mean activation energy is strongly composition sensitive. The position and overall shape of the loss peaks in dependence on composition were analysed in terms of an assumed loss of standard linear solid type with low dispersion, and a broad distribution of Arrhenius-type relaxation with temperature independent relaxation strength. The dependence of ultrasonic attenuation on temperature has been interpreted in terms of a thermally activated relaxation process which arises when ultrasonic waves disturb the equilibrium of an atom moving in a double-well potential in the glass network. The dependence of activation energy on composition suggests that the structure of these glasses changes at 20 mol\% V2O5 concentration.