Anharmonic versus relaxational sound damping in glasses. II. Vitreous silica
Abstract
The temperature dependence of the frequency dispersion in the sound velocity and damping of vitreous silica is reanalyzed. Thermally activated relaxation accounts for the sound attenuation observed above 10 K at sonic and ultrasonic frequencies. Its extrapolation to the hypersonic regime reveals that the anharmonic coupling to the thermal bath becomes important in Brillouin-scattering measurements. At 35 GHz and room temperature, the damping due to this anharmonicity is found to be nearly twice that produced by thermally activated relaxation. The analysis also reveals a sizeable velocity increase with temperature which is not related with sound dispersion. A possible explanation is that silica experiences a gradual structural change that already starts well below room temperature.
- Publication:
-
Physical Review B
- Pub Date:
- December 2005
- DOI:
- 10.1103/PhysRevB.72.214205
- arXiv:
- arXiv:cond-mat/0505560
- Bibcode:
- 2005PhRvB..72u4205V
- Keywords:
-
- 63.50.+x;
- 78.40.Pg;
- 62.80.+f;
- 78.35.+c;
- Vibrational states in disordered systems;
- Disordered solids;
- Ultrasonic relaxation;
- Brillouin and Rayleigh scattering;
- other light scattering;
- Condensed Matter - Disordered Systems and Neural Networks;
- Condensed Matter - Materials Science
- E-Print:
- 13 pages with 8 figures