Volume 78, Number 3, May 2007
|Number of page(s)||6|
|Section||Condensed Matter: Structural, Mechanical and Thermal Properties|
|Published online||16 April 2007|
Dynamic-to-static crossover in the acoustic attenuation of
Dipartimento di Fisica, Università di Trento - 38050 Povo, Trento, Italy
2 Research Center SOFT INFM-CNR, c/o Università di Roma “La Sapienza” - 00185 Roma, Italy
3 Dipartimento di Fisica, Università di L'Aquila - 67010 Coppito, L'Aquila, Italy
4 Departement Physique des Milieux Denses CNRS-IMPMC, Universitè Paris 6 - F-75015 Paris, France
5 Universitè Joseph Fourier c/o Institut de Biologie Structurale and CRG-IN13 at Institut Laue-Langevin (ILL) - B.P. 156 Grenoble Cedex 9, France
6 Dipartimento di Fisica, Università di Perugia - 06123 Perugia, Italy
7 Dipartimento di Energetica, Università di Firenze - 50139 Firenze, Italy
Accepted: 15 March 2007
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 (1550 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.
PACS: 63.50.+x – Vibrational states in disordered systems / 78.35.+c – Brillouin and Rayleigh scattering; other light scattering / 61.12.Ex – Neutron scattering (including small-angle scattering)
© Europhysics Letters Association, 2007
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