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Title: Structure-Controlled Oxygen Concentration in Fe 2O 3 and FeO 2

Abstract

Solid-solid reaction, particularly in the Fe-O binary system, has been extensively studied in the past decades because of its various applications in chemistry and materials and earth sciences. The recently synthesized pyrite-FeO 2 at high pressure suggested a novel oxygen-rich stoichiometry that extends the achievable O-Fe ratio in iron oxides by 33%. Although FeO 2 was synthesized from Fe 2O 3 and O 2, the underlying solid reaction mechanism remains unclear. Herein, combining in situ X-ray diffraction experiments and first-principles calculations, we identified that two competing phase transitions starting from Fe 2O 3: (1) without O 2, perovskite-Fe2O3 transits to the post-perovskite structure above 50 GPa; (2) if free oxygen is present, O diffuses into the perovskite-type lattice of Fe 2O 3 leading to the pyritetype FeO 2 phase. We found the O-O bonds in FeO 2 are formed by the insertion of oxygen into the Pv lattice via the external stress and such O-O bonding is only kinetically stable under high pressure. This may provide a general mechanism of adding extra oxygen to previous known O saturated oxides to produce unconventional stoichiometries. Our results also shed light on how O is enriched in mantle minerals under pressure.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [2];  [4];  [5];  [6];  [7]
  1. Univ. of Nevada, Las Vegas, NV (United States); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China)
  2. Stanford Univ., CA (United States)
  3. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China)
  4. Argonne National Lab. (ANL), Lemont, IL (United States)
  5. Univ. of Hawaii, Honolulu, HI (United States)
  6. Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China); Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.
  7. Univ. of Nevada, Las Vegas, NV (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
OSTI Identifier:
1530397
Grant/Contract Number:  
AC02-06CH11357; NA0001982; NA0001974; FG02-94ER14466; FG02-99ER45775; EAR-1661511; EAR-1345112; EAR-1722515; EAR-1447438
Resource Type:
Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 58; Journal Issue: 9; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Zhu, Sheng-cai, Liu, Jin, Hu, Qingyang, Mao, Wendy L., Meng, Yue, Zhang, Dongzhou, Mao, Ho-kwang, and Zhu, Qiang. Structure-Controlled Oxygen Concentration in Fe2O3 and FeO2. United States: N. p., 2018. Web. doi:10.1021/acs.inorgchem.8b02764.
Zhu, Sheng-cai, Liu, Jin, Hu, Qingyang, Mao, Wendy L., Meng, Yue, Zhang, Dongzhou, Mao, Ho-kwang, & Zhu, Qiang. Structure-Controlled Oxygen Concentration in Fe2O3 and FeO2. United States. doi:10.1021/acs.inorgchem.8b02764.
Zhu, Sheng-cai, Liu, Jin, Hu, Qingyang, Mao, Wendy L., Meng, Yue, Zhang, Dongzhou, Mao, Ho-kwang, and Zhu, Qiang. Mon . "Structure-Controlled Oxygen Concentration in Fe2O3 and FeO2". United States. doi:10.1021/acs.inorgchem.8b02764.
@article{osti_1530397,
title = {Structure-Controlled Oxygen Concentration in Fe2O3 and FeO2},
author = {Zhu, Sheng-cai and Liu, Jin and Hu, Qingyang and Mao, Wendy L. and Meng, Yue and Zhang, Dongzhou and Mao, Ho-kwang and Zhu, Qiang},
abstractNote = {Solid-solid reaction, particularly in the Fe-O binary system, has been extensively studied in the past decades because of its various applications in chemistry and materials and earth sciences. The recently synthesized pyrite-FeO2 at high pressure suggested a novel oxygen-rich stoichiometry that extends the achievable O-Fe ratio in iron oxides by 33%. Although FeO2 was synthesized from Fe2O3 and O2, the underlying solid reaction mechanism remains unclear. Herein, combining in situ X-ray diffraction experiments and first-principles calculations, we identified that two competing phase transitions starting from Fe2O3: (1) without O2, perovskite-Fe2O3 transits to the post-perovskite structure above 50 GPa; (2) if free oxygen is present, O diffuses into the perovskite-type lattice of Fe2O3 leading to the pyritetype FeO2 phase. We found the O-O bonds in FeO2 are formed by the insertion of oxygen into the Pv lattice via the external stress and such O-O bonding is only kinetically stable under high pressure. This may provide a general mechanism of adding extra oxygen to previous known O saturated oxides to produce unconventional stoichiometries. Our results also shed light on how O is enriched in mantle minerals under pressure.},
doi = {10.1021/acs.inorgchem.8b02764},
journal = {Inorganic Chemistry},
number = 9,
volume = 58,
place = {United States},
year = {2018},
month = {12}
}

Journal Article:
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This content will become publicly available on December 17, 2019
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