Characterisation of semiconducting V 2O 5–Bi 2O 3–TeO 2 glasses through ultrasonic measurements

Abstract

Tellurite containing vanadate (50− x)V 2O 5– xBi 2O 3–50TeO 2 glasses with different bismuth ( x=0, 5, 10, 15, 20 and 25 wt%) contents have been prepared by rapid quenching method. Ultrasonic velocities (both longitudinal and shear) and attenuation (for longitudinal waves only) measurements have been made using a transducer operated at the fundamental frequency of 5 MHz in the temperature range from 150 to 480 K. The elastic moduli, Debye temperature, and Poisson’s ratio have been obtained both as a function of temperature and Bi 2O 3 content. The room temperature study on ultrasonic velocities, attenuation, elastic moduli, Poisson’s ratio, Debye temperature and glass transition temperature show the absence of any anomalies with addition of Bi 2O 3 content. The observed results confirm that the addition of Bi 2O 3 modifier changes the rigid formula character of TeO 2 to a matrix of regular TeO 3 and ionic behaviour bonds (NBOs). A monotonic decrease in velocities and elastic moduli, and an increase in attenuation and acoustic loss as a function of temperature in all the glass samples reveal the loose packing structure, which is attributed to the instability of TeO 4 trigonal bipyramid units in the network as temperature increases. It is also inferred that the glasses with low Bi 2O 3 content are more stable than with high Bi 2O 3 content.