Internal Friction of (SiO₂)_1-x (GeO₂)_x Glasses

Abstract
Internal friction of (SiO₂)_1-x (GeO₂)_x glasses (x = 0, 5, 10, 24 and 100 mole%) is measured at temperatures between 1.6 and 280 K. The data are filted with the equations for thermally activated relaxation with distributing activation energies in symmetrical double-well potentials. From the determined relaxation strength spectra for each sample, the contributions from each type of microscopic structural units are calculated assuming that transverse motion of the bridging O atom in Si-O-Si, Si-O-Ge or Ge-O-Ge bridge (T model) is the microscopic unit responsible for relaxation. For instance, the magnitude of internal friction for SiO₂-5% GeO₂ or 24% GeO₂ is calculated from the data of pure SiO₂, SiO₂-10% GeO₂ and pure GeO₂. The calculated results agree well with the measurements of SiO₂-5% GeO₂ and SiO₂-24% GeO₂. Thus T model is shown to be quantitalively consistent with internal friction of SiO₂-GeO₂ binary glasses.