Melting experiments on Fe–Fe 3 S system to 254 GPa

Mori, Yuko; Ozawa, Haruka; Hirose, Kei; Sinmyo, Ryosuke; Tateno, Shigehiko; Morard, Guillaume; Ohishi, Yasuo

doi:10.1016/j.epsl.2017.02.021

Cited by 82 publications

(176 citation statements)

References 40 publications

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“…% of S matched the observed density of the outer core [Morard et al, 2013]. %, which is the eutectic composition of an Fe-FeS system at core conditions [Mori et al, 2017]. However, its bulk sound velocity is much higher than the seismic observation in particular in deep outer core, suggesting other light elements on top of S [Umemoto et al, 2014].…”

Section: Resultssupporting

confidence: 63%

“…S is also a major light element(s) candidate in the Earth's core because of its depletion in the crust and mantle relative to elements with similar volatilities [Rama Murthy and Hall, 1970;Poirier, 1994]. Still, there is no report of the electrical resistivity of iron-sulfur (Fe-S) alloy at high pressures mainly because the solubility of S in solid Fe is very low even at high pressure, and thus, it is difficult to synthesize a single phase of Fe-S alloy [Li et al, 2001;Stewart et al, 2007;Kamada et al, 2012;Mori et al, 2017]. In addition, S may be an important light element in the Martian core [Wanke and Dreibus, 1988;Lodders and Fegley, 1997], and the influence of S on the conductivity of Fe alloy may have important implications for the ancient dynamo action and thermal evolution of the Martian core.…”

Section: Introductionmentioning

confidence: 99%

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The influence of sulfur on the electrical resistivity of hcp iron: Implications for the core conductivity of Mars and Earth

Sugitani

Ohta

Hirose

et al. 2017

Geophysical Research Letters

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Cosmochemical and geochemical studies suggest sulfur (S) as a light alloying element in the iron‐rich cores of telluric planets, but there is no report of sulfur's alloying effect on the electrical and thermal transport properties of iron (Fe); a subject that is closely related to the dynamo action and thermal evolution of planetary cores. We measured the electrical resistivity of hexagonal‐closed‐packed (hcp) structured Fe alloy containing 3 wt. % silicon (Si) and 3 wt. % S up to 110 GPa at 300 K. Combined with the reported resistivities of hcp Fe and hcp Fe‐Si alloy, we determined the impurity resistivity of S in a hcp Fe matrix at high pressures. The obtained impurity resistivity of S is found to be smaller than that of Si. Therefore, S is a weaker influence on the conductivity of Fe alloy, even if S is a major light element in the planetary cores.

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Section: Resultssupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

The influence of sulfur on the electrical resistivity of hcp iron: Implications for the core conductivity of Mars and Earth

Sugitani

Ohta

Hirose

et al. 2017

Geophysical Research Letters

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“…Indeed, seismic data indicate that the core is well mixed (Davies et al, ; Labrosse, ; Nimmo, ). However, compositional convection is still not fully resolved as there is significant uncertainty in terms of light element composition in the core (Morard et al, ; Mori et al, ; Ozawa et al, ; Shibazaki & Kono, ; Suehiro et al, ; Suer et al, ; Tateno et al, ). For example, it was recently proposed that the exsolution of Mg at the CMB is sufficient to drive compositional convection (O'Rourke et al, ; O'Rourke & Stevenson, ) from the top down.…”

Section: Discussionmentioning

confidence: 99%

“…A variety of light elements, such as S, C, and O, is expected to be in the liquid OC in relatively small quantities of a few percent (e.g., McDonough, ; Morard et al, ; Tateno et al, ; Zhang, Sekine, et al, ). It was established recently (e.g., Zhang, Sekine, et al, ) that the OC is unlikely to contain just a single light element, since it has been demonstrated that no one light element can satisfy the combined compositional, cosmochemical, and geophysical constraints in the OC near ICB (Morard et al, ; Mori et al, ; Ozawa et al, ; Shibazaki & Kono, ; Suehiro et al, ; Suer et al, ; Tateno et al, ). Even with the unknown compositional makeup of the light elements in the core, our study leads to the conclusion that the electrical resistivity and thermal conductivity of liquid Fe alloy will remain the same at ICB and likely at CMB, regardless of the light element identity for small contents.…”

Section: Discussionmentioning

confidence: 99%

Heat Flow in Earth's Core From Invariant Electrical Resistivity of Fe‐Si on the Melting Boundary to 9 GPa: Do Light Elements Matter?

et al. 2019

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The electrical resistivity and thermal conductivity of liquid Fe alloys are the least constrained parameters in Earth's outer core (OC). These parameters are important as they modulate energy budget available for the geodynamo and affect the spatiotemporal evolution of the core. We report results of electrical resistivity measurements on solid and liquid Fe‐4.5 wt%Si from 3–9 GPa using a large volume multianvil press. The internally modified 18/11 octahedron cell was used to maintain the geometry of the liquid sample and to delay the onset of contamination. Electrical resistivity of solid Fe‐4.5Si decreases steadily with pressure and is very sensitive to increasing temperature‐driven onset of phase transitions. Along the melting boundary and within error, electrical resistivity remains constant and assumes the same value of 120 μΩcm as observed in pure liquid Fe. The results are interpreted in the context of icosahedral short‐range order (ISRO) structures that exhibit higher concentration with increasing pressure. Along the melting line, the increasing concentration of ISROs reduces charge carrier mean free path and prevents decrease of electrical resistivity with increasing pressure as seen in liquid metals, Cu, Ag, and Au, which do not have ISROs. In light of recent developments in understanding of the structure and dynamics of liquid transition metals and alloys, we postulate that our findings are applicable to other Fe alloys in the OC with small light element (C, S, and O) content. We calculated an adiabatic heat flow of 9.4–12 TW at the OC‐CMB interface, which admits thermal convection.

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“…Researchers could utilize various methods to measure the melting temperature up to hundreds of GPa [1]. However, up to now, the prediction of high-pressure melting curves of transition metals has been under debate and disagreement among different methods such as diamond-anvil cell experiments [2], X-ray diffraction measurements (XRD) [3], shock-wave experiments [4], computer simulations [5] and theoretical approaches [6].…”

mentioning

confidence: 99%

Melting temperature of iron at high pressure: statistical moment method approach

Hai

2017

MaP

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Abstract:The pressure effects on melting temperatures of iron have been studied based on the combination of the modified Lindemann criterion with statistical moment method in quantum statistical mechanics. Numerical calculations have been performed up to pressure 150 GPa. Our results are in good and reasonable agreements with available experimental data. This approach gives us a relatively simple method for qualitatively calculating high-pressure melting temperature. Moreover, it can be used to verify future experimental and theoretical works. This research proposes the potential of the combination of statistical moment method and the modified Lindemann criterion on predicting high-pressure melting of materials.

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Melting experiments on Fe–Fe 3 S system to 254 GPa

Cited by 82 publications

References 40 publications

The influence of sulfur on the electrical resistivity of hcp iron: Implications for the core conductivity of Mars and Earth

The influence of sulfur on the electrical resistivity of hcp iron: Implications for the core conductivity of Mars and Earth

Heat Flow in Earth's Core From Invariant Electrical Resistivity of Fe‐Si on the Melting Boundary to 9 GPa: Do Light Elements Matter?

Melting temperature of iron at high pressure: statistical moment method approach

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