Anharmonic versus relaxational sound damping in glasses. II. Vitreous silica | |
Article | |
关键词: TEMPERATURE-DEPENDENCE; ULTRASONIC-ATTENUATION; STRUCTURAL RELAXATION; BRILLOUIN-SCATTERING; THERMAL-CONDUCTIVITY; ELASTIC PROPERTIES; ACOUSTIC MODES; FUSED-SILICA; QUARTZ; HEAT; | |
DOI : 10.1103/PhysRevB.72.214205 | |
来源: SCIE |
【 摘 要 】
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.
【 授权许可】
Free