Silica under hydrostatic pressure: A non continuous medium behavior

Journal of Non-Crystalline Solids (Impact Factor: 1.6). 10/2009; 4340. DOI:10.1016/j.jnoncrysol.2009.08.031

ABSTRACT a b s t r a c t The homogeneous/inhomogeneous structure of glasses is still a debated question. Hydrostatic high pres-sure experiments allow us to determine if a glass behaves as an elastic continuous random network or if a nanometer scale heterogeneity has to be taken into account. In order to get information on the homoge-neous/inhomogeneous structure of glasses, in situ high pressure Raman experiments are performed on silica in the elastic domain up to 4.7 GPa. A strong decrease of the Boson peak intensity is observed between 1 bar and 3 GPa. We show that this decrease does not correspond quantitatively to the effect of pressure on a homogeneous elastic medium. From the interpretation of the narrowing of the main Raman band width under pressure as a narrowing of the h inter-tetrahedral Si–O–Si angle distribution it is shown that the decrease of the Boson peak intensity is correlated to the decrease of the intrinsic inho-mogeneity of the silica glass. These results confirm the occurrence of an intrinsic inhomogeneity at a nanometer scale even in a single component glass like SiO 2 which is very important for the interpretation of the optical or mechanical properties of the glasses.

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Jun 30, 2012