Structure-Controlled Oxygen Concentration in Fe2O3 and FeO2
[1];
[3];
- Univ. of Nevada, Las Vegas, NV (United States); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China)
- Stanford Univ., CA (United States)
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China)
- Argonne National Lab. (ANL), Lemont, IL (United States)
- Univ. of Hawaii, Honolulu, HI (United States)
- Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai (China); Carnegie Inst. of Washington, Washington, DC (United States). Geophysical Lab.
- Univ. of Nevada, Las Vegas, NV (United States)
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.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-06CH11357; NA0001982; NA0001974; FG02-94ER14466; FG02-99ER45775; EAR-1661511; EAR-1345112; EAR-1722515; EAR-1447438
- OSTI ID:
- 1530397
- Journal Information:
- Inorganic Chemistry, Vol. 58, Issue 9; ISSN 0020-1669
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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