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Ohta K, Suehiro S, Kawaguchi SI, Okuda Y, Wakamatsu T, Hirose K, Ohishi Y, Kodama M, Hirai S, Azuma S. Measuring the Electrical Resistivity of Liquid Iron to 1.4 Mbar. PHYSICAL REVIEW LETTERS 2023; 130:266301. [PMID: 37450814 DOI: 10.1103/physrevlett.130.266301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 05/04/2023] [Indexed: 07/18/2023]
Abstract
We determined the electrical resistivity of liquid Fe to 135 GPa and 6680 K using a four-probe method in a diamond-anvil cell combined with two novel techniques: (i) enclosing a molten Fe in a sapphire capsule, and (ii) millisecond time-resolved simultaneous measurements of the resistance, x-ray diffraction, and temperature of instantaneously melted Fe. Our results show the minimal temperature dependence of the resistivity of liquid Fe and its anomalous resistivity decrease around 50 GPa, likely associated with a gradual magnetic transition, both in agreement with previous ab initio calculations.
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Affiliation(s)
- Kenji Ohta
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Sho Suehiro
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Saori I Kawaguchi
- Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198, Japan
| | - Yoshiyuki Okuda
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tatsuya Wakamatsu
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Kei Hirose
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo 113-0033, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Yasuo Ohishi
- Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198, Japan
| | - Manabu Kodama
- Department of Mechanical Engineering, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Shuichiro Hirai
- Department of Mechanical Engineering, Tokyo Institute of Technology, Tokyo 152-8551, Japan
| | - Shintaro Azuma
- Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551, Japan
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Electrical resistivity of the Fe–Si–S ternary system: implications for timing of thermal convection shutdown in the lunar core. Sci Rep 2022; 12:19031. [PMID: 36347909 PMCID: PMC9643352 DOI: 10.1038/s41598-022-21904-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 10/04/2022] [Indexed: 11/11/2022] Open
Abstract
The composition of the lunar core has been suggested to be Fe-rich with varying amounts of lighter elements, such as Si and S. Presence of Si and S affects electrical and thermal transport properties and thus influences core thermal processes and evolution. Paleomagnetic observations constrain a high intensity magnetic field that ceases shortly after formation of the moon (~ 3.5–4.2 Ga year ago), and thermal convection in the core may contribute to generation of this field. In this study, the electrical resistivity of Fe-14 wt% Si-3 wt% S was measured in both solid and molten states at pressures up to 5 GPa and thermal conductivity was calculated via the Wiedemann–Franz Law from the electrical measurements. The results were used to estimate the adiabatic conductive heat flux of a molten Fe-14 wt% Si-3 wt% S lunar core and compared to a Fe-2-17 wt% Si lunar core, which showed that thermal convection of either core composition shuts down within the duration of the high intensity magnetic field: (1) 3.17–3.72 Ga year ago for a Fe-14 wt% Si-3 wt% S core; and (ii) 3.38–3.86 Ga years ago for a Fe-2-17 wt% Si core. Results favouring compatibility of these core compositions with paleomagnetic observations are strongly dependent on the temperature of the core-mantle boundary and time-dependent mantle-side heat flux.
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Resistivity of solid and liquid Fe-Ni-Si with applications to the cores of Earth, Mercury and Venus. Sci Rep 2022; 12:9941. [PMID: 35705611 PMCID: PMC9200758 DOI: 10.1038/s41598-022-14130-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Accepted: 06/01/2022] [Indexed: 11/24/2022] Open
Abstract
Electrical resistivity measurements of Fe–10wt%Ni–10wt%Si have been performed in a multi-anvil press from 3 to 20 GPa up to 2200 K. The temperature and pressure dependences of electrical resistivity are analyzed in term of changes in the electron mean free path. Similarities in the thermal properties of Fe–Si and Fe–Ni–Si alloys suggest the effect of Ni is negligible. Electrical resistivity is used to calculate thermal conductivity via the Wiedemann–Franz law, which is then used to estimate the adiabatic heat flow. The adiabatic heat flow at the top of Earth’s core is estimated to be 14 TW from the pressure and temperature dependences of thermal conductivity in the liquid state from this study, suggesting thermal convection may still be an active source to power the dynamo depending on the estimated value taken for the heat flow through the core mantle boundary. The calculated adiabatic heat flux density of 22.7–32.1 mW/m2 at the top of Mercury’s core suggests a chemically driven magnetic field from 0.02 to 0.21 Gyr after formation. A thermal conductivity of 140–148 Wm−1 K−1 is estimated at the center of a Fe–10wt%Ni–10wt%Si Venusian core, suggesting the presence of a solid inner core and an outer core that is at least partially liquid.
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Yang F, Hu X, Fei Y. In situ measurements of electrical resistivity of metals in a cubic multi-anvil apparatus by van der Pauw method. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:053902. [PMID: 35649814 DOI: 10.1063/5.0082207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/08/2022] [Indexed: 06/15/2023]
Abstract
On the basis of the van der Pauw method, we developed a new technique for measuring the electrical resistivity of metals in a cubic multi-anvil high-pressure apparatus. Four electrode wires were introduced into the sample chamber and in contact with the pre-pressed metal disk on the periphery. The sample temperature was measured with a NiCr-NiSi (K-type) thermocouple, which was separated from the sample by a thin hexagonal boron nitride layer. The electrodes and thermocouple were electrically insulated from each other and from the heater by an alumina tube as well. Their leads were in connection with cables through the gap between the tungsten carbide anvils. We performed experiments to determine the temperature dependence of electrical resistivity of pure iron at 3 and 5 GPa. The experiments produce reproducible measurements and the results provide an independent check on electrical resistivity data produced by other methods. The new technique provides reliable electrical resistivity measurements of metallic alloys and compounds at high pressure and temperature.
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Affiliation(s)
- Fan Yang
- School of Science, Wuhan University of Technology, Wuhan, Hubei 430070, China
| | - Xiaojun Hu
- School of Science, Wuhan University of Technology, Wuhan, Hubei 430070, China
| | - Yingwei Fei
- Earth and Planets Laboratory, Carnegie Institution of Washington, Washington, District of Columbia 20015, USA
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