In situ electrical resistivity and viscosity measurements of iron alloys under pressure using synchrotron X-ray radiography

Pommier, Anne; Leinenweber, Kurt; Pirotte, Hadrien; Yu, Tony; Wang, Y.

doi:10.1080/08957959.2020.1865343

Cited by 5 publications

(6 citation statements)

References 25 publications

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“…SEM analyses on the retrieved samples indicate that the sample geometry did not change during the experiment, consistent with other experiments employing the same electrical cell (Pommier et al., 2020). As a consequence, the geometric factor G in Equation 1 can be considered constant over the entire temperature range.…”

Section: Resultssupporting

confidence: 87%

Iron Sulfides and Anomalous Electrical Resistivity in Cratonic Environments

2021

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The interpretation of low‐resistivity anomalies in the lithospheric mantle of several cratonic regions has invoked hydrogen, or connected networks of graphite with iron‐rich silicates, and/or metal sulfides. Electrical laboratory measurements are a powerful approach for exploring these alternatives. We report electrical measurements of two xenoliths (pyroxenite and dunite) from Tanzania; two metal sulfides (FeS and Fe‐S‐Ni); and several mixtures of metal sulfides (3.4–18.2 vol.%) with xenolith. A multi‐anvil press was employed to maintain a 2 GPa pressure and temperatures up to 1,627 K. The addition of 3.4 vol.% FeS to the pyroxenite or dunite matrix has little effect on bulk resistivity, particularly for T > 800 K. However, the resistivity drops dramatically–by factors of up to 1,000, depending on temperature–upon addition of 6.5 vol.% FeS in the dunite. Addition of 18.2% FeS causes a further decrease of the same magnitude relative to the 6.5% sample. Scanning electron microscope images do not reveal the formation of a connected FeS network as part of the decreased resistivity. Possible explanations for the apparently conflicting results include connections of the sulfide that are not imaged in the back‐scattered images, either because of limited resolution, or perhaps the inherent limitations of the 2‐D perspective. The complete data set (xenoliths, metal sulfides, and mixtures) was modeled with a modified version of Archie's law, and we find satisfactory agreement over a truncated temperature range. We conclude that the low‐resistivity anomalies in Tanzania, Kaapvaal, and Gawler cratons can be explained by the presence of a few vol.% of solid sulfide.

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Section: Resultssupporting

confidence: 87%

Iron Sulfides and Anomalous Electrical Resistivity in Cratonic Environments

2021

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“…The Wiedemann–Franz law (K e = LT/ρ) allows for the electronic component of thermal conductivity, which is the dominant component in metals, to be calculated from the measured electrical resistivity (ρ) and temperature (T). This approach has been adopted by numerous studies (e.g., 18, [ 37 , 38 , 39 , 40 , 41 , 42 ]). Using the L 0 value in the Wiedemann–Franz law, our calculated electronic thermal conductivity of Cu and Au at each fixed pressure was plotted as a function of temperature and compared with the calculated values from the 1 atm electrical resistivity data [ 21 ] and those measured at relatively lower pressure conditions for Cu [ 11 ] and Au [ 13 ].…”

Section: Resultsmentioning

confidence: 99%

Electrical Resistivity of Cu and Au at High Pressure above 5 GPa: Implications for the Constant Electrical Resistivity Theory along the Melting Curve of the Simple Metals

Ezenwa

Yoshino

2021

Materials

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The electrical resistivity of solid and liquid Cu and Au were measured at high pressures from 6 up to 12 GPa and temperatures ∼150 K above melting. The resistivity of the metals was also measured as a function of pressure at room temperature. Their resistivity decreased and increased with increasing pressure and temperature, respectively. With increasing pressure at room temperature, we observed a sharp reduction in the magnitude of resistivity at ∼4 GPa in both metals. In comparison with 1 atm data and relatively lower pressure data from previous studies, our measured temperature-dependent resistivity in the solid and liquid states show a similar trend. The observed melting temperatures at various fixed pressure are in reasonable agreement with previous experimental and theoretical studies. Along the melting curve, the present study found the resistivity to be constant within the range of our investigated pressure (6–12 GPa) in agreement with the theoretical prediction. Our results indicate that the invariant resistivity theory could apply to the simple metals but at higher pressure above 5 GPa. These results were discussed in terms of the saturation of the dominant nuclear screening effect caused by the increasing difference in energy level between the Fermi level and the d-band with increasing pressure.

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“…The effect of S on the viscosity of the outer core has been extensively studied but with conflicting results. For instance, Dobson et al (2000) and Pommier et al (2021) observed an increase of viscosity with increasing S content, while Terasaki et al (2001) observed an opposite trend. Ab initio calculations seem to suggest no strong effect of S on viscosity of Fe Vočadlo et al, 2000).…”

Section: Introductionmentioning

confidence: 94%