ULTRASONIC INVESTIGATIONS OF PBO-V2O5-P2O5 GLASS

The velocity and attenuation of longitudinal and transverse ultrasonic waves in (PbO)(x)- (V2O5)y-(P2O5)(1-x-y) glass systems of different c ompositions have been measured at temperatures between 80 and 300 K us ing the ultrasonic pulse echo overlap technique at 10 MHz. For each sa mple the velocity data have been used to find the elastic moduli and D ebye temperature at different temperatures. The results indicate that for each sample, the velocities decrease slowly and steadily with incr easing temperature. The temperature dependence of ultrasonic attenuati on has been explained in terms of a thermally activated relaxation pro cess. On the ether hand, the combined effect of relaxation, anharmonic ity, and the effect due to frozen-in fluctuation is taken into conside ration to explain the variation of velocity with temperature. (C) 1998 American Institute of Physics. [S0021-8979(98)05416-4].