The Nature of the High-Pressure Iron Oxides and its Implications for the Earth and Planetary Sciences

Abstract

Recent studies revealed that iron-oxides exhibit various stoichiometry under high pressure and temperature conditions corresponding to the Earth’s mantle. The stability and the physical properties of the high-pressure iron oxides have important implications for the structure and evolution of the Earth’s deep mantle. The iron-oxides are likely stable above approximately 10 GPa with considerably high solubility of the divalent and trivalent cations such as Mg²⁺ and Al³⁺. Some iron-oxides can be stable under relatively low oxygen fugacity, in which the diamond is stable. The phases show characteristic physical properties, such as electrical conductivity, due to the mixed valence states of iron. We summarize the recent findings on high-pressure iron oxides and their implications for the Earth and planetary sciences.