Polarized Raman spectroscopy of v-SiO2 under rare gas compression

Coralie Weigel (1) , Marie Foret (1)

1 L2C - Laboratoire Charles Coulomb

High-pressure polarized Raman spectra of vitreous silica are measured up to 8 GPa in a diamond-anvil cell at room 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.

Domaines: Autre [cond-mat.other]; Vibrations [physics.class-ph]; Vibrations [physics.class-ph]

Coralie Weigel, Marie Foret. Polarized Raman spectroscopy of v-SiO2 under rare gas compression. 54th European High Pressure Research Group Meeting (EHPRG 2016), Sep 2016, Bayreuth, Germany. ⟨hal-01909031⟩