The acoustic attenuation of vitreous germania (v-GeO2) has been measured over more than three decades in frequency, by means of neutron scattering at high-frequency (THz), visible light scattering and the newly developed technique of Brillouin ultraviolet scattering at lower frequencies (15-50 GHz). The experiments are supported by a molecular dynamics study of a simulated sample of v-GeO2. The temperature dependence, from 80 K up to the glass transition temperature, shows a persistence of the dynamical nature of the attenuation in the GHz range and a simultaneous increase of the contribution coming from the structural disorder. At higher frequencies clear evidences of a crossover to a region where the attenuation is induced only by the topological disorder are found.

Dynamic-to-static crossover in the acoustic attenuation of v-GeO 2 / G. Baldi, P. Benassi, L.E. Bove, S. Caponi, E. Fabiani, D. Fioretto, A. Fontana, A. Giugni, M. Nardone, M. Sampoli, F. Scarponi. - In: EUROPHYSICS LETTERS. - ISSN 0295-5075. - 78:3(2007), pp. 36001.1-36001.7. [10.1209/0295-5075/78/36001]

Dynamic-to-static crossover in the acoustic attenuation of v-GeO 2

A. Giugni;
2007

Abstract

The acoustic attenuation of vitreous germania (v-GeO2) has been measured over more than three decades in frequency, by means of neutron scattering at high-frequency (THz), visible light scattering and the newly developed technique of Brillouin ultraviolet scattering at lower frequencies (15-50 GHz). The experiments are supported by a molecular dynamics study of a simulated sample of v-GeO2. The temperature dependence, from 80 K up to the glass transition temperature, shows a persistence of the dynamical nature of the attenuation in the GHz range and a simultaneous increase of the contribution coming from the structural disorder. At higher frequencies clear evidences of a crossover to a region where the attenuation is induced only by the topological disorder are found.
Vibrational excitations; thermal-conductivity; brillouin-scattering; relaxation processes; neutron-scattering; vitreous Germania; sound-attenuation; glasses; waves; origin
Settore FIS/03 - Fisica della Materia
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/827925
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