Structure and Density of Fe‐C Liquid Alloys Under High Pressure

Morard, Guillaume; Nakajima, Yoichi; Andrault, Denis; Antonangeli, Daniele; Auzende, Anne-Line; Boulard, E.; Cervera, S.; Clark, A. N.; Lord, O. T.; Siebert, J.; Svitlyk, Volodymyr; Garbarino, Gastón; Mézouar, M.

doi:10.1002/2017jb014779

Cited by 32 publications

(30 citation statements)

References 56 publications

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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%

“…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, 2003;Morard et al, 2017;Tateno et al, 2018;Zhang, Sekine, et al, 2016). It was established recently (e.g., Zhang, Sekine, et al, 2016) 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 Mori et al, 2017;Ozawa et al, 2016;Shibazaki & Kono, 2018;Suehiro et al, 2017;Suer et al, 2017;Tateno et al, 2018).…”

Section: General Implications For Core Evolution and Heat Flowmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: General Implications For Core Evolution and Heat Flowmentioning

confidence: 99%

See 1 more Smart Citation

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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“…Structures of other liquid Fe‐light element alloys have been less studied. There are only a few studies for structures of liquid Fe‐Si (28.9 at.% Si, Sanloup et al, ; 33.2 at.% Si, Morard et al, ), liquid Fe‐C (14.4 at.% C, Shibazaki et al, ; ~10 at.% C, Morard et al, ), and liquid Fe‐H (~23 at.% H, Katayama et al, ). These liquid Fe‐light element alloys show basic structure similar to that of liquid pure Fe.…”

Section: Introductionmentioning

confidence: 99%

Effect of Silicon, Carbon, and Sulfur on Structure of Liquid Iron and Implications for Structure‐Property Relations in Liquid Iron‐Light Element Alloys

Shibazaki

Kono

2018

JGR Solid Earth

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Planetary cores are considered to be composed of iron (Fe) and light elements. Extensive studies on structure and properties of crystalline Fe‐light element alloys have been carried out to discuss composition and structure of the solid inner core. In contrast, structure and properties of liquid Fe‐light element alloys, which are important to discuss nature and dynamics of the liquid outer core, remain poorly understood. Here we conducted series of liquid structure measurements to systematically understand effect of silicon (Si), carbon (C), and sulfur (S) on structure of liquid Fe. We found that incorporation of Si in liquid Fe shortens the nearest (r1) and second (r2) neighbor distances, while incorporation of C and small amount of S expands these distances. The different structural behavior is interpreted in view of different light‐element incorporation mechanisms: substitutional incorporation of Si and interstitial incorporation of C and S. All light elements lower density of liquid Fe regardless of shortening or expansion of the r1 and r2 distances, while P‐wave velocities of liquid Fe‐light element alloys show linear increase with shortening of the r1 and r2. The different light‐element incorporation behavior in the structure of liquid Fe and the resultant variation in the properties of liquid Fe‐light element alloys should be important in understanding behavior of liquid Fe‐light element alloys in the planetary cores.

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“…Structural information of liquid metals is also key to understanding processes within deep terrestrial and exoplanetary interiors, including metallic core formation [7] and magnetic field generation [8]. While challenging, measuring liquid structure at elevated p-T conditions is a rapidly developing field [9][10][11][12][13][14][15][16].…”

mentioning

confidence: 99%

Structural Ordering in Liquid Gallium under Extreme Conditions

et al. 2020

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The atomic-scale structure, melting curve, and equation of state of liquid gallium has been measured to high pressure (p) and high temperature (T) up to 26 GPa and 900 K by in situ synchrotron x-ray diffraction. Ab initio molecular dynamics simulations up to 33.4 GPa and 1000 K are in excellent agreement with the experimental measurements, providing detailed insight at the level of pair distribution functions. The results reveal an absence of dimeric bonding in the liquid state and a continuous increase in average coordination numbern Ga Ga from 10.4(2) at 0.1 GPa approaching ∼12 by 25 GPa. Topological cluster analysis of the simulation trajectories finds increasing fractions of fivefold symmetric and crystalline motifs at high p-T. Although the liquid progressively resembles a hard-sphere structure towards the melting curve, the deviation from this simple description remains large (≥40%) across all p-T space, with specific motifs of different geometries strongly correlating with low local two-body excess entropy at high p-T.

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Structure and Density of Fe‐C Liquid Alloys Under High Pressure

Cited by 32 publications

References 56 publications

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

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

Effect of Silicon, Carbon, and Sulfur on Structure of Liquid Iron and Implications for Structure‐Property Relations in Liquid Iron‐Light Element Alloys

Structural Ordering in Liquid Gallium under Extreme Conditions

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