Structure and Stability of Iron Fluoride at High Pressure–Temperature and Implication for a New Reservoir of Fluorine in the Deep Earth
1
Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China
2
Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
3
HPCAT, X-ray Science Division, Argonne National Laboratory, Lemont, IL 60439, USA
*
Authors to whom correspondence should be addressed.
Minerals 2020, 10(9), 783; https://doi.org/10.3390/min10090783
Received: 16 August 2020 / Revised: 1 September 2020 / Accepted: 4 September 2020 / Published: 5 September 2020
(This article belongs to the Special Issue Minerals under Extreme Conditions)
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.
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Keywords:
iron fluoride; Earth’s lower mantle; laser-heated diamond anvil cell; high pressure–temperature
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MDPI and ACS Style
Lin, Y.; Hu, Q.; Zhu, L.; Meng, Y. Structure and Stability of Iron Fluoride at High Pressure–Temperature and Implication for a New Reservoir of Fluorine in the Deep Earth. Minerals 2020, 10, 783. https://doi.org/10.3390/min10090783
AMA Style
Lin Y, Hu Q, Zhu L, Meng Y. Structure and Stability of Iron Fluoride at High Pressure–Temperature and Implication for a New Reservoir of Fluorine in the Deep Earth. Minerals. 2020; 10(9):783. https://doi.org/10.3390/min10090783
Chicago/Turabian StyleLin, Yanhao, Qingyang Hu, Li Zhu, and Yue Meng. 2020. "Structure and Stability of Iron Fluoride at High Pressure–Temperature and Implication for a New Reservoir of Fluorine in the Deep Earth" Minerals 10, no. 9: 783. https://doi.org/10.3390/min10090783
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