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Article Dans Une Revue Journal of Chemical Physics Année : 2013

Poisson ratio and excess low-frequency vibrational states in glasses

Résumé

In glass, starting from a dependence of the Angell's fragility on the Poisson ratio [V. N. Novikov and A. P. Sokolov, Nature 431, 961 (2004)], and a dependence of the Poisson ratio on the atomic packing density [G. N. Greaves et al., Nat. Mater. 10, 823 (2011)], we propose that the heterogeneities are predominantly density fluctuations in strong glasses (lower Poisson ratio) and shear elasticity fluctuations in fragile glasses (higher Poisson ratio). Because the excess of low-frequency vibration modes in comparison with the Debye regime (boson peak) is strongly connected to these fluctuations, we propose that they are breathing-like (with change of volume) in strong glasses and shear-like (without change of volume) in fragile glasses. As a verification, it is confirmed that the excess modes in the strong silica glass are predominantly breathing-like. Moreover, it is shown that the excess breathing-like modes in a strong polymeric glass are replaced by shear-like modes under hydrostatic pressure as the glass becomes more compact.
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Dates et versions

hal-00852203 , version 1 (20-08-2013)

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Eugène Duval, Thierry Deschamps, Lucien Saviot. Poisson ratio and excess low-frequency vibrational states in glasses. Journal of Chemical Physics, 2013, 139, pp.064506. ⟨10.1063/1.4817778⟩. ⟨hal-00852203⟩
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