title: Hexafluorobenzene under Extreme Conditions.
abstract: We report the results from three high pressure experiments on hexafluorobenzene (C6F6). In the first experiment, Raman spectra were recorded up to 34.4 GPa. A phase transition from I → II was observed near 2 GPa. Near 8.8 GPa, a phase transition to an unreported phase (III) commenced. Above 20.6 GPa, yet another phase was observed (IV). Pressure cycling was employed to determine that, below 25.6 GPa, all pressure-induced alterations were reversible. However, at pressures above 20 GPa, dramatic spectral changes and broadening were observed at 25.6 and 34.4 GPa. The sample irreversibly changed into a soft solid with waxlike consistency when pressure was reduced to ambient and was recoverable. In the second experiment, IR spectra were collected up to 14.6 GPa. The phase transition (II → III) near 8.8 GPa was confirmed. An angular dispersive X-ray diffraction experiment was conducted to 25.6 GPa. Phase transitions above 1.4 GPa (I → II), above 5.5 GPa (II → III), above 10 GPa (III → IV), and above 15.5 GPa (IV → V) were observed. Near 25.6 GPa, long-range crystalline order was lost as the X-ray diffraction spectrum presented evidence of an amorphous solid.
authors.affiliation: High Pressure Science and Engineering Center and Department of Physics, University of Nevada Las Vegas , Las Vegas, Nevada 89154-4002, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Pravica
authors.affiliation: High Pressure Science and Engineering Center and Department of Physics, University of Nevada Las Vegas , Las Vegas, Nevada 89154-4002, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sneed
authors.affiliation: High Pressure Science and Engineering Center and Department of Physics, University of Nevada Las Vegas , Las Vegas, Nevada 89154-4002, United States.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: High Pressure Science and Engineering Center and Department of Physics, University of Nevada Las Vegas , Las Vegas, Nevada 89154-4002, United States.
authors.forename: Quinlan
authors.initials: Q
authors.lastname: Smith
authors.affiliation: High Pressure Science and Engineering Center and Department of Physics, University of Nevada Las Vegas , Las Vegas, Nevada 89154-4002, United States.
authors.forename: Melanie
authors.initials: M
authors.lastname: White
mesh_terms: D005466:Fluorocarbons / Q000737:chemistry*; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry; D011312:Pressure; D013059:Spectrum Analysis, Raman
chemical_list: D005466:Fluorocarbons; D011108:Polymers; C003005:hexafluorobenzene