Signature of a polyamorphic transition in the THz spectrum of vitreous GeO₂

Journal Article · 12 October 2015 · Scientific Reports

DOI: https://doi.org/10.1038/srep14996 · OSTI ID:1258790

Cunsolo, Alessandro ^[1]; Li, Yan ^[2]; Kodituwakku, Chaminda N. ^[1]; Wang, Shibing ^[3]; Antonangeli, Daniele ^[4]; Bencivenga, Filippo ^[5]; Battistoni, Andrea ^[6]; Verbeni, Roberto ^[7]; Tsutsui, Satoshi ^[8]; Baron, Alfred Q. R. ^[9]; Mao, Ho -Kwang ^[10]; Bolmatov, Dima ^[1]; Cai, Yong Q. ^[1]

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1. Brookhaven National Lab. (BNL), Upton, NY (United States)
2. American Physical Society, Ridge, NY (United States)
3. Stanford Univ., Stanford, CA (United States)
4. Institut de Mineralogie, de Physique des Materiaux et de Cosmochimie, Sorbonne Univ. - UPMC, Museum National d'Historie Naturelle, Paris (France)
5. Sincrotrone Trieste, Trieste (Italy)
6. Sincrotrone Trieste, Trieste (Italy); Univ. degli Studi di Trieste, Trieste (Italy)
7. European Synchrotron Radiation Facility, Grenoble (France)
8. Japan Synchrotron Radiation Research Institute, Hyogo (Japan)
9. Japan Synchrotron Radiation Research Institute, Hyogo (Japan); SPring-8/RIKEN, Hyogo (Japan)
10. Geophysical Lab. Carnegie Institution of Washington, D.C. (United States); Center for High Pressure Science & Technology Advanced Research, Shanghai (China)

The THz spectrum of density fluctuations, S(Q, ω), of vitreous GeO₂ at ambient temperature was measured by inelastic x-ray scattering from ambient pressure up to pressures well beyond that of the known α-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. Altogether, the presented results highlight the complex fingerprint of PA phenomena on the high-frequency phonon dispersion.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0012704
• OSTI ID: 1258790
• Journal Information: Scientific Reports, Journal Name: Scientific Reports Vol. 5; ISSN 2045-2322
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United States
• Language: English