Signature of a polyamorphic transition in the THz spectrum of vitreous GeO2
Résumé
The THz spectrum of density fluctuations, S(Q, ω), of vitreous GeO2 at ambient temperature wasmeasured by inelastic x-ray scattering from ambient pressure up to pressures well beyond that ofthe known α-quartz to rutile polyamorphic (PA) transition. We observe significant differences in thespectral shape measured below and above the PA transition, in particular, in the 30–80 meV range.Guided by first-principle lattice dynamics calculations, we interpret the changes in the phonondispersion as the evolution from a quartz-like to a rutile-like coordination. Notably, such a crossoveris accompanied by a cusp-like behavior in the pressure dependence of the elastic response of thesystem. Overall, the presented results highlight the complex fingerprint of PA phenomena on thehigh-frequency phonon dispersion.
Domaines
Planète et Univers [physics]Origine | Publication financée par une institution |
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