INTERNAL-FRICTION OF (SIO2)(1-X)(GEO2)(X) GLASSES

Internal friction of (SiO2)(1-x) (GeO2)(x) glasses (x = 0, 5, 10, 24 a nd 100 mole% is measured at temperatures between 1.6 and 280 K. The da ta are fitted with the equations for thermally activated relaxation wi th distributing activation energies in symmetrical double-well potenti als. From the determined relaxation strength spectra for each sample, the contributions from each type of microscopic structural units are c alculated assuming that transverse motion of the bridging 0 atom in Si -O-Si, Si-O-Ge or Ge-O-Ge bridge CT model) is the microscopic unit res ponsible for relaxation. For instance, the magnitude of internal frict ion for SiO2-5% GeO2 or 24% GeO2 is calculated from the data of pure S iO2, SiO2-10% GeO2 and pure GeO2. The calculated results agree well wi th the measurements of SiO2-5% GeO2 and SiO2-44% GdO2. Thus T model is shown to be quantitatively consistent with internal friction of SiO2- GeO2 binary glasses.