Evolution of electrical conductivity and semiconductor to metal transition of iron oxides at extreme conditions

• Published in: Chinese physics B Vol. 31; no. 8; pp. 89101 - 108
• Main Authors: Zhuang, Yukai, Hu, Qingyang
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.08.2022; Institute of Atomic and Molecular Physics,Sichuan University,Chengdu 610065,China%Center for High Pressure Science and Technology Advanced Research(HPSTAR),Beijing 100094,China
• Subjects: electrical conductivity; high pressure; iron oxides; metallization; metallization; electrical conductivity; iron oxides; high pressure
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/ac7557

Iron oxides are widely found as ores in Earth’s crust and are also important constituents of its interiors. Their polymorphism, composition changes, and electronic structures play essential roles in controlling the structure and geodynamic properties of the solid Earth. While all-natural occurring iron oxides are semiconductors or insulators at ambient pressure, they start to metalize under pressure. Here in this work, we review the electronic conductivity and metallization of iron oxides under high-pressure conditions found in Earth’s lower mantle. We summarize that the metallization of iron oxides is generally controlled by the pressure-induced bandgap closure near the Fermi level. After metallization, they possess much higher electrical and thermal conductivity, which will facilitate the thermal convection, support a more stable and thicker D″ layer, and formulate Earth’s magnetic field, all of which will constrain the large-scale dynamos of the mantle and core.