Structure and stability of iron fluoride at high pressure–temperature and implication for a new reservoir of fluorine in the deep earth

Y. Lin, Q. Hu, L. Zhu, Y. Meng

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

© 2020 by the authors. Licensee MDPI, Basel, Switzerland.Fluorine (F) is the most abundant halogen in the bulk silicate Earth. F plays an important role in geochemical and biological systems, but its abundance and distribution in the terrestrial mantle are still unclear. Recent studies suggested that F reservoirs in the deep mantle are potentially hosted in terrestrial oxide minerals, especially in aluminous bridgmanite. However, the knowledge about the formation and stability field of fluoride in the Earth’s interior is rare. In this study, we combine in situ laser-heated diamond anvil cell, synchrotron X-ray diffraction, and first-principles structure search to show that a new tetragonal structure of FeF3 is stable at pressures of 78–130 GPa and temperatures up to ~1900 K. Simulation predicted the tetragonal phase takes a much denser structure due to the rotation of FeF6 octahedral units. The equations of states of tetragonal FeF3 are determined by experiment and verified by simulation. Our results indicate that FeF3 can be a potential key phase for storing F in the Earth’s lower mantle and may explain some mantle-derived magma with high F concentration.
Original languageEnglish
Article number783
Pages (from-to)1-7
JournalMinerals
Volume10
Issue number9
DOIs
Publication statusPublished - 1 Sept 2020
Externally publishedYes

Funding

Y.L. is supported by NSF Grants EAR-1722515. Q.H. is supported by NSFC (No.17N1051-0213). HPCAT operations are supported by DOE-NNSA’s Office of Experimental Sciences. APS is supported by DOE-BES, under contract no. DE-AC02-06CH11357. Computations were supported by Carnegie computational resources. The Center for High Pressure Science and Technology Advanced Research is supported by NSAF (Grants U1530402 and U1930401). Acknowledgments: This work was performed at HPCAT (Sector 16), Advanced Photon Source (APS), Argonne National Laboratory. HPCAT operations are supported by DOE-NNSA’s Office of Experimental Sciences. The Advanced Photon Source is a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory. Funding: Y.L. is supported by NSF Grants EAR-1722515. Q.H. is supported by NSFC (No.17N1051-0213). HPCAT operations are supported by DOE-NNSA’s Office of Experimental Sciences. APS is supported by DOE-BES, under contract no. DE-AC02-06CH11357. Computations were supported by Carnegie computational resources. The Center for High Pressure Science and Technology Advanced Research is supported by NSAF (Grants U1530402 and U1930401).

FundersFunder number
DOE-NNSA’s Office of Experimental Sciences
National Science FoundationEAR-1722515
U.S. Department of Energy
Office of Science
Basic Energy SciencesDE-AC02-06CH11357
Argonne National Laboratory
National Natural Science Foundation of China
National Safety Academic FundU1930401, U1530402

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