ULTRASONIC INVESTIGATIONS OF CUO-P2O5 GLASS

The ultrasonic velocity and attenuation in four different samples of t he (CuO)(x)-(P2O5)(1-x) glass system (x = 0.1500, 0.3030, 0.3768, 0.51 06) have been measured at temperatures between 80 and 300 K using the ultrasonic pulse echo overlap technique at 10 MHz. The samples were pr epared by the melt-quench method. The velocity data have been used to find the elastic moduli and Debye temperature for each composition. Th e results indicate that, for each composition, the velocities decrease slowly and steadily with increasing temperature and there is no indic ation of a minimum in the variation of velocity with temperature unlik e many other glasses. The dependence of ultrasonic velocity and attenu ation with temperature has been interpreted in terms of a thermally ac tivated relaxation process. The model is based on an asymmetric double -well potential having distribution of both the barrier height and the asymmetry between the two wells. Attempts have been made to explain t he apparent discrepancy found in the velocity variation between the th eory and experiment.