Viscosity of Earth's inner core constrained by Fe-Ni interdiffusion in Fe-Si alloy in an internal-resistive-heated diamond anvil cell

Diffusivity in iron (Fe) alloys at high pressures and temperatures imposes constraints on the transport properties of the inner core, such as viscosity. Because silicon (Si) is among the most likely candidates for light elements in the inner core, the presence of Si must be considered when studying...

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Bibliographic Details
Published inThe American mineralogist Vol. 108; no. 6; pp. 1064 - 1071
Main Authors Park, Yohan, Yonemitsu, Kyoko, Hirose, Kei, Kuwayama, Yasuhiro, Azuma, Shintaro, Ohta, Kenji
Format Journal Article
LanguageEnglish
Published Washington Mineralogical Society of America 01.06.2023
Walter de Gruyter GmbH
Subjects
Alloys
anvil cells
Anvils
Constraints
core
Diamond anvil cells
Diamonds
diffusion
diffusion coefficients
diffusivity
Earth core
Earth’s inner core
Ferrous alloys
Geophysics
grain boundaries
High pressure
high temperature
inner core
Interdiffusion
Iron
Laser beam heating
Light elements
Lorentz force
metals
Nickel
P-T conditions
phase transitions
pressure
related to mantle
silica
Silicon
temperature
Transport properties
Viscosity
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Summary:Diffusivity in iron (Fe) alloys at high pressures and temperatures imposes constraints on the transport properties of the inner core, such as viscosity. Because silicon (Si) is among the most likely candidates for light elements in the inner core, the presence of Si must be considered when studying diffusivity in the Earth's inner core. In this study, we conducted diffusion experiments under pressures up to about 50 GPa using an internal-resistive-heated diamond-anvil cell (DAC) that ensures stable and homogeneous heating compared with a conventional laser-heated DAC and thus allows us to conduct more reliable diffusion experiments under high pressure. We determined the coefficients of Fe-nickel (Ni) interdiffusion in the Fe-Si 2 wt% alloy. The obtained diffusion coefficients follow a homologous temperature relationship derived from previous studies without considering Si. This indicates that the effect of Si on Fe-Ni interdiffusion is not significant. The upper limit of the viscosity of the inner core inferred from our results is low, indicating that the Lorentz force is a plausible mechanism to deform the inner core.
ISSN:0003-004X
1945-3027
DOI:10.2138/am-2022-8541