Accueil >
Production scientifique
Structure, vibration, relaxations dans les systèmes désordonnés
(39) Production(s) de l'année 2018
|
|
Structure and dynamics of a polymer-nanoparticle composite 
Auteur(s): Sorichetti V., Hugouvieux Virginie, Kob W.
Conference: Italian Soft Days (Padova, IT, 2018-09-13)
|
|
|
|
Stretched and compressed exponentials in the relaxation dynamics of a metallic glass- forming melt
Auteur(s): Wu Zhen wei, Kob W. , Wang Wei-hua, Xu Limei
(Article) Publié:
Nature Communications, vol. 9 p.5334 (2018)
Texte intégral en Openaccess : 
Ref HAL: hal-01981718_v1
DOI: 10.1038/s41467-018-07759-w
WoS: WOS:000453441300002
Exporter : BibTex | endNote
14 Citations
Résumé: The dynamics of glass-forming systems shows a multitude of features that are absent innormal liquids, such as non-exponential relaxation and a strong temperature-dependence ofthe relaxation time. Connecting these dynamic properties to the microscopic structure of thesystem is challenging because of the presence of the structural disorder. Here we usecomputer simulations of a metallic glass-former to establish such a connection. By probingthe temperature and wave-vector dependence of the intermediate scattering function wefindthat the relaxation dynamics of the glassy melt is directly related to the local arrangement oficosahedral structures: Isolated icosahedra give rise to a liquid-like stretched exponentialrelaxation whereas clusters of icosahedra lead to a compressed exponential relaxation that isreminiscent to the one found in a solid. Our results show that in metallic glass-formers thesetwo types of relaxation processes can coexist and give rise to a dynamics that is surprisinglycomple
|
|
|
|
Structuring and degrading polymer gels via catalytic reactions
Auteur(s): Hugouvieux Virginie, Kob W.
Conférence invité: Réunion plénière du GDR SLAMM (Solliciter LA Matière Molle) (Hyères, FR, 2018-11-12)
|
|
|
|
Temperature dependence of hypersound attenuation in silica films via picosecond acoustics
Auteur(s): Foret M., Huynh A., Peronne E., Ruffle B., Perrin B., Lafosse X., Lemaitre A., Vacher R.
Conference: 16th International Conference on Phonon Scattering in Condensed Matter (Phonons 2018) (Nanjing, CN, 2018-05-30)
Ref HAL: hal-01940549_v1
Exporter : BibTex | endNote
Résumé: We reinvestigate sound dispersion and attenuation in a SiO2 layer as a function of temperature over the range 20–300 K by picosecond acoustics [1]. A pulse-echo scheme is used, where a broadband strain-pulse (centered at 120 GHz) is detected in an Al transducer after propagating back and forth through the SiO2 layer. The acoustic attenuation coefficient α within the SiO2 layer is evaluated by fitting the echoes to a mismatch model including an effective local law for the frequency dependence of attenuation over the band of the pulse. In this way, the T dependence of α in SiO2 layers could be extracted in this work for the first time. Results are found to follow rather well a model combining coupling to thermally activated relaxation mechanisms and interactions with thermal vibrations. This leads to a non-trivial variation of the attenuation coefficient with frequency and temperature. The number density of relaxing defects in the SiO2 layer is found to be slightly higher than that in bulk v-SiO2. In contrast, similar anharmonic contribution to acoustic absorption is observed in both systems. The velocity variations are also measured and are compared to the dynamical velocity changes deduced from the sound attenuation.
|
|
|
|
Elastic and plastic transformations of vitreous silica underpressure
Auteur(s): Foret M., Ruffle B., Weigel C., Vacher R.
Conférence invité: Journées de la Matière Condensée, 2018 (Grenoble, FR, 2018-08-27)
Ref HAL: hal-01940534_v1
Exporter : BibTex | endNote
Résumé: The talk focuses on the thermodynamical properties of vitreous silica submitted to high pressures in a diamond anvil cell as obtained directly from Brillouin Light Scattering experiments or indirectly from standard relations. The analysis reveals non-negligible differences between static and dynamic compressibilities which are mostly related to the existence of thermally activated relaxational processes. Estimate of the residual densifications after complete cycles of compression/decompression is discussed.
|
