Rare helium-bearing compound FeO2He stabilized at deep-earth conditions

Zhang, Jurong and Lv, Jian and Li, Hefei and Feng, Xiaolei and Lu, Cheng and Redfern, Simon A. T. and Liu, Hanyu and Chen, Changfeng and Ma, Yanming (2018) Rare helium-bearing compound FeO2He stabilized at deep-earth conditions. Physical Review Letters. ISSN 0031-9007 ESSN: 1079-7114 DOI https://doi.org/10.1103/PhysRevLett.121.255703

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Abstract

There is compelling geochemical evidence for primordial helium trapped in Earth’s lower mantle, but the origin and nature of the helium source remain elusive due to scarce knowledge on viable helium-bearing compounds that are extremely rare. Here we explore materials physics underlying this prominent challenge. Our structure searches in conjunction with first-principles energetic and thermodynamic calculations uncover a remarkable helium-bearing compound FeO2He at high pressure-temperature conditions relevant to the core-mantle boundary. Calculated sound velocities consistent with seismic data validate FeO2He as a feasible constituent in ultralow velocity zones at the lowermost mantle. These mutually corroborating findings establish the first and hitherto only helium-bearing compound viable at pertinent geophysical conditions, thus providing vital physics mechanisms and materials insights for elucidating the enigmatic helium reservoir in deep Earth.

Item Type:	Article
Uncontrolled Keywords:	2018AREP; IA73
Subjects:	03 - Mineral Sciences
Divisions:	03 - Mineral Sciences 08 - Green Open Access
Journal or Publication Title:	Physical Review Letters
Identification Number:	https://doi.org/10.1103/PhysRevLett.121.255703
Depositing User:	Sarah Humbert
Date Deposited:	15 Nov 2018 18:31
Last Modified:	10 Mar 2021 23:38
URI:	http://eprints.esc.cam.ac.uk/id/eprint/4352

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