1 research outputs found
Signature of a polyamorphic transition in the THz spectrum of vitreous GeO2
The THz spectrum of density fluctuations, , of vitreous GeO
at ambient temperature was measured by inelastic x-ray scattering from ambient
pressure up to pressures well beyond that of the known -quartz to
rutile polyamorphic (PA) transition. We observe significant differences in the
spectral 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 phonon dispersion as the evolution from a
quartz-like to a rutile-like coordination. Notably, such a crossover is
accompanied by a cusp-like behavior in the pressure dependence of the elastic
response of the system. Overall, the presented results highlight the complex
fingerprint of PA phenomena on the high-frequency phonon dispersion.Comment: 18 pages, 5 figure