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Title: Ferrous Iron Under Oxygen-Rich Conditions in the Deep Mantle

Abstract

Recent experiments have demonstrated the existence of previously unknown iron oxides at high pressure and temperature including newly discovered pyrite-type FeO 2 and FeO 2H x phases stable at deep terrestrial lower mantle pressures and temperatures. In the present study, we probed the iron oxidation state in high-pressure transformation products of Fe 3+OOH goethite by in situ X-ray absorption spectroscopy in laser-heated diamond-anvil cell. At pressures and temperatures of ~91 GPa and 1,500–2,350 K, respectively, that is, in the previously reported stability field of FeO 2H x, a measured shift of -3.3 ± 0.1 eV of the Fe K-edge demonstrates that iron has turned from Fe 3+ to Fe 2+. We interpret this reductive valence change of iron by a concomitant oxidation of oxygen atoms from O 2- to O -, in agreement with previous suggestions based on the structures of pyrite-type FeO 2 and FeO 2H x phases. Such peculiar chemistry could drastically change our view of crystal chemistry in deep planetary interiors.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1];  [1]; ORCiD logo [1];  [1]; ORCiD logo [2];  [2]; ORCiD logo [2];  [2];  [1]
  1. Sorbonne Univ., Paris (France)
  2. European Synchrotron Radiation Facility (ESRF), Grenoble (France)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1494842
Alternate Identifier(s):
OSTI ID: 1494843; OSTI ID: 1497938
Report Number(s):
LLNL-JRNL-758622
Journal ID: ISSN 0094-8276; 943118
Grant/Contract Number:  
AC52-07NA27344; AC52‐07NA27344
Resource Type:
Journal Article: Published Article
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 46; Journal Issue: 3; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES

Citation Formats

Boulard, E., Harmand, M., Guyot, F., Lelong, G., Morard, G., Cabaret, D., Boccato, S., Rosa, A. D., Briggs, R., Pascarelli, S., and Fiquet, G. Ferrous Iron Under Oxygen-Rich Conditions in the Deep Mantle. United States: N. p., 2019. Web. doi:10.1029/2019GL081922.
Boulard, E., Harmand, M., Guyot, F., Lelong, G., Morard, G., Cabaret, D., Boccato, S., Rosa, A. D., Briggs, R., Pascarelli, S., & Fiquet, G. Ferrous Iron Under Oxygen-Rich Conditions in the Deep Mantle. United States. doi:10.1029/2019GL081922.
Boulard, E., Harmand, M., Guyot, F., Lelong, G., Morard, G., Cabaret, D., Boccato, S., Rosa, A. D., Briggs, R., Pascarelli, S., and Fiquet, G. Mon . "Ferrous Iron Under Oxygen-Rich Conditions in the Deep Mantle". United States. doi:10.1029/2019GL081922.
@article{osti_1494842,
title = {Ferrous Iron Under Oxygen-Rich Conditions in the Deep Mantle},
author = {Boulard, E. and Harmand, M. and Guyot, F. and Lelong, G. and Morard, G. and Cabaret, D. and Boccato, S. and Rosa, A. D. and Briggs, R. and Pascarelli, S. and Fiquet, G.},
abstractNote = {Recent experiments have demonstrated the existence of previously unknown iron oxides at high pressure and temperature including newly discovered pyrite-type FeO2 and FeO2Hx phases stable at deep terrestrial lower mantle pressures and temperatures. In the present study, we probed the iron oxidation state in high-pressure transformation products of Fe3+OOH goethite by in situ X-ray absorption spectroscopy in laser-heated diamond-anvil cell. At pressures and temperatures of ~91 GPa and 1,500–2,350 K, respectively, that is, in the previously reported stability field of FeO2Hx, a measured shift of -3.3 ± 0.1 eV of the Fe K-edge demonstrates that iron has turned from Fe3+ to Fe2+. We interpret this reductive valence change of iron by a concomitant oxidation of oxygen atoms from O2- to O-, in agreement with previous suggestions based on the structures of pyrite-type FeO2 and FeO2Hx phases. Such peculiar chemistry could drastically change our view of crystal chemistry in deep planetary interiors.},
doi = {10.1029/2019GL081922},
journal = {Geophysical Research Letters},
issn = {0094-8276},
number = 3,
volume = 46,
place = {United States},
year = {2019},
month = {1}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1029/2019GL081922

Citation Metrics:
Cited by: 2 works
Citation information provided by
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Figures / Tables:

Figure 1 Figure 1: Normalized Fe-K edge XANES spectra collected upon compression up to 64 GPa at ambient temperature of FeOOH loaded into Neon. Inset: pre-edge area of the spectra.

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Works referenced in this record:

High pressure–high temperature equations of state of neon and diamond
journal, March 2008

  • Dewaele, Agnès; Datchi, Frédéric; Loubeyre, Paul
  • Physical Review B, Vol. 77, Issue 9, Article No. 094106
  • DOI: 10.1103/PhysRevB.77.094106

Unraveling the complexity of iron oxides at high pressure and temperature: Synthesis of Fe5O6
journal, June 2015

  • Lavina, Barbara; Meng, Yue
  • Science Advances, Vol. 1, Issue 5, Article No. e1400260
  • DOI: 10.1126/sciadv.1400260

    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.