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Pressure-induced densification of vitreous silica: Insight from elastic properties

2019; American Physical Society; Volume: 100; Issue: 9 Linguagem: Inglês

10.1103/physrevb.100.094102

2469-9977

Coralie Weigel, Marouane Mebarki, Sébastien Clément, René Vacher, Marie Foret, Benoît Rufflé,

Geological and Geochemical Analysis

\textit{In situ} high-pressure Brillouin light scattering experiments along loading-unloading paths are used to investigate the compressibility of vitreous silica. An accurate equation of state is obtained below \SI{9}{GPa} using sound velocities corrected for dispersion. Conversely, huge inelastic effects are observed in the range \SIrange{10}{60}{GPa}, unveiling the reversible transformation from the fourfold-coordinated structure to the sixfold one. We find that the associated density changes fully correlate with the average Si coordination number. Decompression curves from above \SI{20}{GPa} reveal abrupt backward coordination changes around \SIrange{10}{15}{GPa} and significant hysteresis. Further, contrary to common wisdom, the residual densification of recovered silica samples can be figured out from the pressure cycles.