Brillouin scattering of vitreous silica under high pressure |
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Authors: | S Rau S Baeßler G Kasper G Weiss S Hunklinger |
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Abstract: | The pressure dependence of Brillouin spectra of vitreous silica exhibits a maximum in the hypersonic absorption and a minimum in the sound velocity at about 2 GPa almost independent of temperature. The results are discussed on the basis of relaxing defects residing in double-well potentials with a Gaussian distribution of barrier heights and a Lorentzian distribution in the asymmetry. Our analysis suggests that both the distribution functions are strongly changed at higher pressures. It is striking that a phase boundary between α-quartz and coesite exists just at the pressure where absorption and sound velocity of vitreous silica pass their extremum. This might be a hint that a corresponding structural change also occurs in the glass. |
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Keywords: | Structural relaxation Polymorphism in glasses Sound velocity Hypersound absorption High pressure |
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