Polarized Raman spectroscopy of v-SiO2 under rare-gas compression Auteur(s): Weigel C., Foret M., Hehlen B., Kint M., Clement S., Polian Alain, Vacher R., Ruffle B. (Article) Publié: Physical Review B, vol. 93 p.224303 (2016) Ref HAL: hal-01337959_v1 DOI: 10.1103/PhysRevB.93.224303 WoS: 000378104200007 Exporter : BibTex | endNote 13 Citations Résumé: High-pressure polarized Raman spectra of vitreous silica are measured up to 8 GPa in a diamond-anvil cell atroom temperature. The combined use of either a nonpenetrating pressurizing medium—argon—or a penetrating one—helium, allows one to separate density from stress effects on the Raman frequencies. In the framework of a simple central force model, the results emphasize the distinct role played by the shrinkage of the intertetrahedral angle Si-O-Si and the force-constant stiffening during the compression. The polarization analysis further reveals the existence of an additional isotropic component in the high-frequency wing of the boson peak. The pressure dependence of the genuine boson peak frequency is found to be much weaker than previously reported and even goes through a minimum around 2 GPa in remarkable coincidence with the anomalous compressibility maximum of silica. |