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Titolo:
ELASTIC PROPERTIES OF XEROGELS AND SINTERED AEROGELS PROBED BY INELASTIC LIGHT-SCATTERING
Autore:
TERKI F; PELOUS J; DIEUDONNE P; WOIGNIER T;
Indirizzi:
UNIV MONTPELLIER 2,LAB VERRES,UMR 5587,PL E BATAILLON,CASE 069 F-34095 MONTPELLIER FRANCE
Titolo Testata:
Journal of non-crystalline solids
fascicolo: 1, volume: 225, anno: 1998,
pagine: 277 - 281
SICI:
0022-3093(1998)225:1<277:EPOXAS>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Keywords:
XEROGELS; SINTERED AEROGELS; INELASTIC LIGHT SCATTERING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
11
Recensione:
Indirizzi per estratti:
Citazione:
F. Terki et al., "ELASTIC PROPERTIES OF XEROGELS AND SINTERED AEROGELS PROBED BY INELASTIC LIGHT-SCATTERING", Journal of non-crystalline solids, 225(1), 1998, pp. 277-281

Abstract

Elastic properties of silica xerogels and sintered aerogels of densities from rho = 0.5 g/cm(3) to 2.2 g/cm(3) were investigated by Brillouin light scattering. Sound velocities and acoustic attenuation at hypersonic frequencies was measured as a function of density. The elastic modulus C follows a scaling power law C = rho(alpha) with alpha = 3.3 /- 0.1 and confirms previous data at low frequencies. For xerogels, the comparison between as prepared and oxidized samples after heat treatments, shows an increase of the elastic constant greater than 50% without significant change of the alpha exponent. This alpha value is close to that observed for densified aerogels emphasizing that this exponent seems to be independent on the sample treatment and preparation. Therefore, the fractal behavior of the material is not essential to explain power-law dependence. The acoustic attenuation has also been determined as a function of the density. A relaxational process coupled toacoustic vibrations disappears after heat treatment. This effect is also related to large inelastic light contribution in the very low-frequency part of the Raman spectra. (C) 1998 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 02/12/20 alle ore 16:45:31