Elasticity and anisotropy of iron-nickel phosphides at high pressures

Wu, Xiang; Mookherjee, Mainak; Gu, Tingyue; Qin, Shan

doi:10.1029/2011gl049158

Cited by 9 publications

(8 citation statements)

References 36 publications

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“…Structural properties of three Fe-P compounds (iron phosphides, FeP-35.68 wt% P, Fe 2 P-21.71 wt% P, and Fe 3 P-15.60 wt% P) at high-pressure and high-temperature conditions have been done by experimental and theoretical methods. Like other well-investigated Fe-L system (e.g., Fe-C, Fe-S, and Fe-Si), These Fe-P compounds has similar chemical structure and crystalline structure (e.g., Fe 3 C, Fe 3 S, FeSi) at core pressure condition (Dera et al, 2008;Gu et al, 2011Gu et al, , 2014Scott et al, 2007Scott et al, , 2008Wu et al, 2011;Wu & Qin, 2010;Yan, 2015). Understanding the thermal dynamic properties and transport properties of these Fe-P compounds is essential to constrain the chemistry and physics of the metallic core of terrestrial planets.…”

Section: Introductionmentioning

confidence: 81%

Electrical Resistivity of Iron Phosphides at High‐Pressure and High‐Temperature Conditions With Implications for Lunar Core's Thermal Conductivity

et al. 2019

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Based on cosmochemistry evidence and element partitioning experiments, phosphorus is thought to be present in the iron‐rich cores of Earth and Moon. Phosphorus has a similar effect as silicon and sulfur on the electrical and thermal transport properties of iron at core conditions. However, the magnitude of the impurity scattering caused by phosphorus, the temperature dependence of iron phosphorus compounds, and the change across melting all have not been intensively investigated. We measured the electrical resistivity of Fe3P, Fe2P, and FeP using a four‐wire method at 1.3 to 3.2 GPa and temperatures up to 1800 K. We also identify the melting temperatures of FeP, Fe2P, and Fe3P by sudden changes in resistivity upon heating. The present experimental results demonstrate that phosphorus can enhance the electrical resistivity of iron more effectively than silicon. The resistivity of iron phosphides decreases with increasing pressures and decreasing phosphorus content. The resistivity of Fe‐P alloys obeys the Matthiessen's rule, which describes the positive linear correlation between resistivity and phosphorus content. This finding is comparable to previously observed atomic order‐disorder in Fe‐Si and Fe‐C systems. Furthermore, the resistivity of liquid Fe2P and Fe3P shows a negative linear correlation with temperatures. Different from pure iron, the calculated thermal conductivity of Fe3P increases by 33% upon melting. It is speculated that the thermal conductivity of the lunar solid inner core may be much lower than that of the liquid outer core when ordered iron light element compounds (e.g., Fe3C and Fe3P) are present in the solid core.

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Section: Introductionmentioning

confidence: 81%

Electrical Resistivity of Iron Phosphides at High‐Pressure and High‐Temperature Conditions With Implications for Lunar Core's Thermal Conductivity

et al. 2019

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“…The pattern of anisotropy for iron near its 458 melting point 60 is very different from the observed IC anisotropy. Alloys of iron with plausible light elements modify the character of anisotropy, but the limited number of experiments leaves the dependence on pressure and temperature uncertain 20,[65][66][67][68][69] . We select hcp iron-nickel alloy (Fe93.75Ni6.25 20 ) as its pattern of single crystal anisotropy (Extended 462 Data Fig.…”

Section: Mineral Physics 447mentioning

confidence: 99%

Dynamic history of the inner core constrained by seismic anisotropy

et al. 2021

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Progressive crystallisation of Earth's inner core over geological times drives convection in the outer core and the generation of the Earth's magnetic field. Resolving the rate and pattern of inner core growth is thus crucial to understanding the evolution of the geodynamo. The growth history of Earth's inner core is likely recorded in the distribution and strength of seismic anisotropy arising from 19 deformation texturing constrained by boundary conditions at the inner-core solid-20 fluid boundary. Travel times of seismic body waves indicate that seismic anisotropy 21 increases with depth. Here we find that the strongest anisotropy is offset from Earth's rotation axis. Using geodynamic growth models and mineral physics calculations, we simulate the development of inner core anisotropy in a self-consistent manner. We show for the first time that an inner core model composed of hexagonally closepacked iron-nickel alloy, deformed by a combination of preferential equatorial growth and slow translation can match the seismic observations without requiring the introduction of hemispheres with sharp boundaries. We find a model of the inner core 28 growth history compatible with external constraints from outer core dynamics, supporting arguments for a relatively young inner core (~0.5-1.5 Ga) and a viscosity >10 18 Pa-s.The presence of seismic anisotropy -the dependence of seismic wavespeed on direction of propagation -in the inner core (IC) was proposed over 30 years ago to explain the early arrival times of IC sensitive seismic body waves (PKPdf) travelling on paths parallel to the Earth's rotation axis 1,2 and anomalous splitting of core-sensitive free oscillations 3 . This anisotropy is thought to result from alignment of iron crystals caused by deformation in a flow field induced by the evolution of the core, i.e. deformation texturing. In previous work, different geodynamic 4 and plastic deformation mechanisms 5 were explored to explain the variation of PKPdf travel times with angle of the ray path with respect to the rotation axis.Here, for the first time, we combine geodynamic modelling of the evolution of flow in the IC, allowing for slow lateral translation, with presently available knowledge on the mineralogy and deformation mechanisms proposed for the IC to explain spatially varying patterns of observed seismic travel times in an updated global dataset.

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Section: Mineral Physics 447mentioning

confidence: 99%

Dynamic history of the inner core constrained by seismic anisotropy

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Lasbleis

Chandler

et al. 2021

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Progressive crystallisation of Earth's inner core over geological times drives convection in the outer core and the generation of the Earth’s magnetic field. Resolving the rate and pattern of inner core growth is thus crucial to understanding the evolution of the geodynamo. The growth history of Earth’s inner core is likely recorded in the distribution and strength of seismic anisotropy arising from deformation texturing constrained by boundary conditions at the inner-core solid-fluid boundary. Travel times of seismic body waves indicate that seismic anisotropy increases with depth. Here we find that the strongest anisotropy is offset from Earth's rotation axis. Using geodynamic growth models and mineral physics calculations, we simulate the development of inner core anisotropy in a self-consistent manner. We show for the first time that an inner core model composed of hexagonally close-packed iron-nickel alloy, deformed by a combination of preferential equatorial growth and slow translation can match the seismic observations without requiring the introduction of hemispheres with sharp boundaries. We find a model of the inner core growth history compatible with external constraints from outer core dynamics, supporting arguments for a relatively young inner core (~0.5-1.5 Ga) and a viscosity >1018 Pa-s.

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Elasticity and anisotropy of iron-nickel phosphides at high pressures

Cited by 9 publications

References 36 publications

Electrical Resistivity of Iron Phosphides at High‐Pressure and High‐Temperature Conditions With Implications for Lunar Core's Thermal Conductivity

Electrical Resistivity of Iron Phosphides at High‐Pressure and High‐Temperature Conditions With Implications for Lunar Core's Thermal Conductivity

Dynamic history of the inner core constrained by seismic anisotropy

Dynamic history of the inner core constrained by seismic anisotropy

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