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(165) Production(s) de RUFFLE B.
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Elasticité des verres et des liquides surfondus 
Auteur(s): Ruffle B.
Conférence invité: Atelier GDR-Verres et USTV : Propriétés vs structure des verres et liquides à haute température (Paris, FR, 2014-05-26)
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Développements récents en spectroscopie Brillouin : applications en science des matériaux
Auteur(s): Ruffle B.
Conférence invité: XXèmes journées du Groupe Français de Spectroscopie Vibrationnelle (Paris, FR, 2014-05-21)
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Revealing the fast atomic motion of network glasses
Auteur(s): Ruta B., Baldi G., Chushkin Y., Ruffle B., Cristofolini L., Fontana A., Zanatta M., Nazzani F.
(Article) Publié:
Nature Communications, vol. 5 p.3939 (2014)
Texte intégral en Openaccess : 
Ref HAL: hal-00993301_v1
DOI: 10.1038/ncomms4939
WoS: 000337505200004
Exporter : BibTex | endNote
83 Citations
Résumé: Still very little is known on the relaxation dynamics of glasses at the microscopic level due to the lack of experiments and theories. It is commonly believed that glasses are in a dynamical arrested state, with relaxation times too large to be observed on human time scales. Here we provide the experimental evidence that glasses display fast atomic rearrangements within a few minutes, even in the deep glassy state. Following the evolution of the structural relaxation in a sodium silicate glass, we find that this fast dynamics is accompanied by the absence of any detectable aging, suggesting a decoupling of the relaxation time and the viscosity in the glass. The relaxation time is strongly affected by the network structure with a marked increase at the mesoscopic scale associated with the ion-conducting pathways. Our results modify the conception of the glassy state and asks for a new microscopic theory.
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Vitreous silica distends in helium gas: acoustic versus static compressibilities
Auteur(s): Weigel C. , Foret M., Ruffle B., Polian Alain, Vacher R.
Conference: European High Pressure Research Group International Meeting (EHPRG 51) (London, GB, 2013-09-01)
Ref HAL: hal-01940341_v1
Exporter : BibTex | endNote
Résumé: Vitreous silica v-SiO2 has been extensively studied over large pressure (P) and temperature (T) ranges. Several anomalous physical properties were discovered. In particular, the compressibility $\chi$ does not show the P and T dependencies observed in most solids. Several models, supported by numerical simulations, have been proposed which rely on the intertetrahedral flexibility of the silica network allowing strong structural modifications with T and P. Recent publications revealed that v-SiO2 submitted to high P in a He atmosphere exhibits a surprisingly small change in volume. This was interpreted as a considerable reduction of compressibility, leading to an apparent bulk modulus B around 110 GPa near ambient P. However, another value of B = 36.5 GPa can be calculated from the longitudinal (vL) and transverse (vT) sound velocities and the density, all known at ambient P. Here we show that this large difference in compressibilities must relate to the open structure of v-SiO2 allowing He to penetrate the network in the static limit. In an open system, the static measurement underestimates the compressibility by a term due to the gas charging. We will present volume changes measurements and Brillouin light-scattering (BLS) measurements of the sound velocity for the longitudinal and transverse acoustic modes as a function of P up to 6 GPa in He atmosphere. It is found that the anomalous B minimum in the acoustic bulk modulus is to a large extent hindered by the penetration of helium atoms into the silica network. The acoustic bulk modulus is found almost less than half the static one demonstrating that He continues penetrating v-SiO2 up to our highest investigated P. An estimate of the amount of He entering v-SiO2 is derived from the measured refractive index, leading to the unexpected value of more than 1 mole of He per mole of SiO2 at 6 GPa.
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High-temperature Elastic moduli of Flux-grown alpha-GeO2 Single Crystal
Auteur(s): Lignie Adrien, Zhou W., Armand Pascale, Ruffle B., Mayet Richard, Debray Jérôme, Hermet P., Ménaert Bertrand, Thomas Philippe, Papet Philippe
(Article) Publié:
Chemphyschem, vol. 15 p.118-125 (2014)
Texte intégral en Openaccess : 
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Sound attenuation mechanisms in glasses
Auteur(s): Ruffle B.
Conférence invité: New directions in Resonant Ultrasound Spectroscopy (Santigo du Chili, CL, 2013-08-21)
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