Highly conductive iron-rich (Mg,Fe)O magnesiowüstite and its stability in the Earth's lower mantle
| Autor: | Tadashi Kondo, Kenji Ohta, Kiyoshi Fujino, Yasuo Ohishi, Katsuya Shimizu, Yasuhiro Kuwayama |
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| Rok vydání: | 2014 |
| Předmět: |
Materials science
Analytical chemistry Oxide Mineralogy Decomposition chemistry.chemical_compound Geophysics Thermal conductivity chemistry Space and Planetary Science Geochemistry and Petrology Transmission electron microscopy Electrical resistivity and conductivity Phase (matter) Earth and Planetary Sciences (miscellaneous) Electrical conductor Earth (classical element) |
| Zdroj: | Journal of Geophysical Research: Solid Earth. 119:4656-4665 |
| ISSN: | 2169-9313 |
| DOI: | 10.1002/2014jb010972 |
| Popis: | It has been repeatedly suggested that an iron-rich oxide might accumulate on the Earth's core-mantle boundary by various processes. Recent studies showed that FeO with a rock salt (B1)-type structure undergoes pressure- and temperature-induced metallization at the Earth's lower mantle conditions. This implies similar metallization or decomposition of the lower mantle phase, (Mg,Fe)O, under high pressure-temperature conditions. We performed simultaneous X-ray diffraction and electrical conductivity measurements on (Mg0.20Fe0.80)O and (Mg0.05Fe0.95)O magnesiowustites up to 140 GPa and 2100 K, and we examined recovered samples by means of an analytical transmission electron microscope. The experiments revealed very high electrical conductivity of the magnesiowustite samples and their minimal temperature dependence above 85 GPa and 1300 K, yet the samples remained insulators. We also found decomposition of (Mg0.05Fe0.95)O into almost pure FeO and iron-rich (Mg,Fe)O due to metallization of the FeO component, while such a reaction was not observed in (Mg0.20Fe0.80)O. The observed high electrical conductivity and decomposition of iron-rich (Mg,Fe)O magnesiowustite could enhance the heterogeneities in the electrical and thermal conductivity at the Earth's core-mantle boundary region. |
| Databáze: | OpenAIRE |
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