Phase relations and physical properties of iron-oxygen compounds at multimegabar pressures and high temperatures

• Applicant: Professorin Dr. Elena Bykova
• Subject Area: Mineralogy, Petrology and Geochemistry ; Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 406616493

• Final Report Year: 2022

Final Report Abstract

The structures, properties and high-pressure and high-temperature behavior of compounds in the Fe–O system remain controversial and full of surprises despite a long history of research. Over the last decade several high-pressure iron oxides with hitherto unknown stoichiometries were discovered. These materials are very important for the geosciences (and planetary sciences) as potential phases during the Earth’s accretion, as possible components of present day mantle, and for controlling oxygen fugacity in the mantle, core mantle boundary, and in the core. Moreover, novel iron oxides, their electronic and magnetic properties are of great interest for modern solid state physics, chemistry, material sciences, and even for in the industry (as elements in switching electronics and memories). Iron oxides will be synthesized at pressures over 200 GPa and temperatures up to 3500 K and studied in situ in laser-heated diamond anvil cells (DACs) employing a range of advanced complementary techniques: X-ray diffraction (XRD), Mössbauer and Raman spectroscopy (and when applicable X-ray absorption spectroscopy and electrical resistivity measurements) and theoretical calculations. Methodological aim of the project is to extend single-crystal diffraction studies to over 200 GPa. Particular attention will be paid on studies of FeO, Fe3O4, Fe2O3, Fe4O5, Fe5O6, Fe5O7, Fe7O9, and FeO2. The ultimate goals of the project are to construct pressure-temperature-composition (P–T–X) phase diagram of Fe–O system at conditions covering entire Earth mantle and significant part of the core; analyze how pressuretemperature induced transformations in Fe–O compounds may affect geochemical processes in the Earth’s interior; reveal relations between structure, chemical bonding, and properties of different iron oxides; and formulate crystal chemical principals governing behavior of transition metal oxides at extreme conditions.

Publications

• Interaction Between FeOOH and NaCl at Extreme Conditions: Synthesis of Novel Na2FeCl4OHx Compound. Minerals, 10(1), 51.
  Koemets, Egor; Yuan, Liang; Bykova, Elena; Glazyrin, Konstantin; Ohtani, Eiji & Dubrovinsky, Leonid
  
• Chemical Stability of FeOOH at High Pressure and Temperature, and Oxygen Recycling in Early Earth History**. European Journal of Inorganic Chemistry, 2021(30), 3048-3053.
  Koemets, Egor; Fedotenko, Timofey; Khandarkhaeva, Saiana; Bykov, Maxim; Bykova, Elena; Thielmann, Marcel; Chariton, Stella; Aprilis, Georgios; Koemets, Iuliia; Glazyrin, Konstantin; Liermann, Hanns‐Peter; Hanfland, Michael; Ohtani, Eiji; Dubrovinskaia, Natalia; McCammon, Catherine & Dubrovinsky, Leonid
  
• Revealing the Complex Nature of Bonding in the Binary High-Pressure Compound FeO2. Physical Review Letters, 126(10).
  Koemets, E.; Leonov, I.; Bykov, M.; Bykova, E.; Chariton, S.; Aprilis, G.; Fedotenko, T.; Clément, S.; Rouquette, J.; Haines, J.; Cerantola, V.; Glazyrin, K.; McCammon, C.; Prakapenka, V. B.; Hanfland, M.; Liermann, H.-P.; Svitlyk, V.; Torchio, R.; Rosa, A. D. ... & Dubrovinsky, L.
  
• Structural Diversity of Magnetite and Products of Its Decomposition at Extreme Conditions. Inorganic Chemistry, 61(2), 1091-1101.
  Khandarkhaeva, Saiana; Fedotenko, Timofey; Chariton, Stella; Bykova, Elena; Ovsyannikov, Sergey V.; Glazyrin, Konstantin; Liermann, Hanns-Peter; Prakapenka, Vitali; Dubrovinskaia, Natalia & Dubrovinsky, Leonid