Volume 80, Number 5, December 2007
|Number of page(s)||5|
|Published online||31 October 2007|
Low-frequency internal friction in silica glass
Dipartimento di Fisica, Università di Perugia - I-06123 Perugia, Italy
2 Istituto Nazionale di Fisica Nucleare, VIRGO Project Sezione di Perugia - I-06123 Perugia, Italy
3 Dipartimento di Fisica, Università di Camerino - I-62032 Camerino, Italy
4 Michigan Center for Theoretical Physics, The University of Michigan - Ann Arbor, MI 48109-1120, USA
Accepted: 9 October 2007
Precise low-frequency internal friction measurements on vitreous silica, taken over a wide temperature (4 K < T < 300 K) and frequency range (40 Hz < ν < 14 kHz), show remarkable similarities, but also suggestive differences with recent light scattering experiments. In the interval 30 K < T < 110 K, the exponent α of the power law relaxational spectrum turns out to be proportional to , with a minimum at around Tk = 13 K. This phenomenon is interpreted as a manifestation of thermal activation in an asymmetric double well system, the asymmetry being associated to quenched spatial disorder. For T > 160 K the loss angle develops a distinct step-like structure followed by a plateau, both independent of ν, thus signalling the onset of a competing relaxation mechanism with much higher an activation energy.
PACS: 04.80.Nn – Gravitational wave detectors and experiments / 61.43.Fs – Glasses / 62.40.+i – Anelasticity, internal friction, stress relaxation, and mechanical resonances
© Europhysics Letters Association, 2007
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