Ultrasonic Relaxation Loss in SiO2, GeO2, B2O3, and As2O3 Glass

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Abstract
Measurements of the temperature dependence of the longitudinal and shear ultrasonic attenuation from 5 to 50 Mc/sec were made in SiO2, GeO2, B2O3, and As2O3 glass. In each case a relaxation loss with a distribution of relaxation times was found. The median activation energy of the relaxation process is about 500 cal/mole in SiO2, 2500 cal/mole in GeO2, 5400 cal/mole in As2O3, and 6300 cal/mole in B2O3. The results are interpreted in terms of a two-bond-length model of glass where the relaxation loss is associated with bridging oxygen atoms which have two stress-sensitive equivalent equilibrium positions. A relationship between the relaxation loss mechanism and the viscosity of these glasses is assumed in this study. A calculation of the activation energies based upon this assumption agrees well with the values determined experimentally.