Structure investigation of TeO_2-BaO glass employing ultrasonic study

摘要

Tellurite glasses of the system (100-x)TeO_2-xBaO for different compositions of BaO (x=9, 12, 15, 18, 20 and 22 wt.%) have been prepared by rapid quenching method. A decrease in ultrasonic velocities and density, which is followed by an increase in attenuation with a progressive increase in BaO content has been observed at room temperature and also over a wide range of temperatures. The above results reveal the softening of the glass network due to the progressive transformation of the rigid framework characteristics of TeO_2 resulting in the formation of distorted TeO_(3+1) units followed by the creation of regular TeO_2 (4 → 3 +1 → 3) sites and the formation of ionic character bond (NBO).