Distinct vibrational signatures and complex phase behavior in metallic oxygen

Year: 2024

Authors: Dalladay-Simpson P., Monserrat B., Zhang L., Gorelli F.

Autors Affiliation: Ctr High Pressure Sci Technol Adv Res, 1690 Cailun Rd, Shanghai 201203, Peoples R China; Univ Cambridge, Dept Mat Sci & Met, 27 Charles Babbage Rd, Cambridge CB3 0FS, England; Univ Cambridge, Cavendish Lab, JJ Thomson Ave, Cambridge CB3 0HE, England; Consiglio Nazl Ric CNR INO, Ist Nazl Ott, I-50125 Florence, Italy; Shanghai Adv Res Phys Sci SHARPS, Shanghai, Peoples R China.

Abstract: Evidence for metallization in dense oxygen has been reported for over 30 years [Desgreniers et al., J. Phys. Chem. 94, 1117 (1990)] at a now routinely accessible 95 GPa [Shimizu et al., Nature 393, 767 (1998)]. However, despite the longevity of this result and the technological advances since, the nature of the metallic phase remains poorly constrained [Akahama et al., Phys. Rev. Lett. 74, 4690 (1995); Goncharov et al., Phys. Rev. B 68, 224108 (2003); Ma, Phys. Rev. B 76, 064101 (2007); and Weck et al., Phys. Rev. Lett. 102, 255503 (2009)]. In this work, through Raman spectroscopy, we report the distinct vibrational characteristics of metallic zeta-O2 from 85 to 225 GPa. In comparison with numerical simulations, we find reasonable agreement with the C2/m candidate structure up to about 150 GPa. At higher pressures, the C2/m structure is found to be unstable and incompatible with experimental observations. Alternative candidate structures, C2/c and Ci, with only two molecules in the primitive unit cell, are found to be stable and more compatible with measurements above 175 GPa, indicative of the dissociation of (O2)4 units. Further, we report and discuss a strong hysteresis and metastability with the precursory phase & varepsilon;-O2. These findings will reinvigorate experimental and theoretical work into the dense oxygen system, which will have importance for oxygen-bearing chemistry, prevalent in the deep Earth, as well as fundamental physics.(c) 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). https://doi.org/10.1063/5.0160060

Journal/Review: MATTER AND RADIATION AT EXTREMES

Volume: 9 (2)      Pages from: 28401-1  to: 28401-8

More Information: We would like to thank Huichao Zhang, Huixin Hu, and Yuchen Yu for their assistance in the laboratory and during sample loadings, as well as Eugene Gregoryanz for useful discussions. Bartomeu Monserrat acknowledges support from a UKRI Future Leaders Fellowship (Grant No. MR/V023926/1), from the Gianna Angelopoulos Programme for Science, Technology, and Innovation, and from the Winton Programme for the Physics of Sustainability. Federico Gorelli acknowledges support from the Shanghai Science and Technology Committee, China (Grant No. 22JC1410300) and the Shanghai Key Laboratory of Novel Extreme Condition Materials, China (Grant No. 22dz2260800). Portions of this work were performed on beamline ID27 at the European Synchrotron Radiation Facility (ESRF) (Proposal Nos. CH6636 and CH6300), Grenoble, France as well as preliminary investigations on beamline 15U1 at the Shanghai Synchrotron Radiation Facility (SSRF), Shanghai, People’s Republic of China. We would like to thank our beamline contacts Mohamed Mezouar and Gaston Garbarino for their assistance during the course of the x-ray diffraction data collection. The computational resources were provided by the Cambridge Tier-2 system operated by the University of Cambridge Research Computing Service and funded by the UK EPSRC (Grant No. EP/P020259/1).
KeyWords: High-pressure; Raman-scattering; Solid Oxygen; Intensity; Iodine; Gpa
DOI: 10.1063/5.0160060

Citations: 2
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