Experimental constraints on the sound velocities of cementite Fe3C to core pressures

Chen, Bin; Lai, Xiaojing; Li, Jie; Liu, Jiachao; Zhao, Jiyong; Bi, Weihong; Ercan, E.; Hu, Michael Y.; Xiao, Yuming

doi:10.1016/j.epsl.2018.05.002

Cited by 34 publications

(38 citation statements)

References 47 publications

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“…The effect of temperature mainly shifts the volume at which the magnetic moment collapses by ∼0.5 Å 3 /atom to a larger volume with respect to the volumes calculated at 0 K for the Fe 7 C 3 and Fe 3 C phases. Reported magnetic transition pressures from experiments vary from as high as 68 GPa to as low as 6.5 GPa for crystalline carbides (Gao et al, 2008;Fiquet et al, 2009;Chen et al, 2012Chen et al, , 2014Chen et al, , 2018. Both experiments and theoretical calculations show that there is no apparent structural change associated with the magnetic transition of the Fe carbide crystalline phases (Lin et al, 2004;Chen et al, 2012;Prescher et al, 2012), similar to the Fe-Ni-C liquid presented here.…”

Section: Energetics Magnetic Properties and The Equation Of Statesupporting

confidence: 61%

“…Nevertheless, C continues to represent a plausible lighter alloying component within the core. The existing data show that alloying Fe with C might partially account for the shear wave velocity anomaly and anisotropy of the inner core (Nikolussi et al, 2008;Gao et al, 2009;Chen et al, 2014Chen et al, , 2018Prescher et al, 2015;Chen and Li, 2016;Lai et al, 2018). In addition, the Fe 7 C 3 phase has recently been proposed as the leading candidate among possible inner core precipitates from a liquid composed of Fe and a small amount of C (Lord et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

et al. 2019

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Properties of liquid Fe alloys under high-pressure conditions are crucial for understanding the composition, thermal state, and dynamics of Earth's core. Experiments on such liquids, however, are often performed under pressures far below those of the outer core, necessitating long extrapolations of experimental results to core conditions. Such estimates can be complicated by light elements possibly forming pressure-dependent molecular clusters that can significantly affect the physical properties of liquids as core conditions are approached. First-principles molecular dynamics simulations were employed to compute the properties of an Fe-Ni-C liquid with a composition of Fe 3.7 Ni 0.37 C at 1673 K and pressures from 0 to 67 GPa to benchmark computational methods on pressure effects on the structure and properties of the liquid relative to low pressure experimental results. The shortrange structure is manifested by the coordination number (CN) of Fe/Ni-Fe/Ni being around 12, indicative of a nearly close-packed structure in the pressure range, and the CN of C-Fe/Ni gradual increasing from 6.5 to 8.5, indicative of an approximately octahedral to cubic transition as pressure increases. The Fe/Ni-Fe/Ni bond distance, however, is found to be 10 times more compressible than the C-Fe/Ni distance. The intermediate-range structure of Fe/Ni-Fe/Ni and C-Fe/Ni subsystems, described by a partial configurationally decomposed distribution function, undergoes substantial changes, characterized by a significant increase of the number of polyhedra that share 3 atoms with each other. Such dense configurations are related to an increased bulk modulus, decreased diffusion coefficient, decreased activation volume for diffusion, and increased shear viscosity. Reproducing the experimental observations at low pressures provides important support for modeling the liquid under the conditions relevant to the outer core.

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Section: Energetics Magnetic Properties and The Equation Of Statesupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

et al. 2019

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“…The density of the material itself and other linear physicomechanical properties are determined in the initial undeformed state. The geophysical conclusions based on Birch's diagram are similar to those in experiments (Chen et al, ; Roy & Sarkar, ; Tateno et al, ; Wakamatsu et al, ).…”

Section: A Description Of the Datasupporting

confidence: 80%

“…Detailed reviews of the experimental work on this topic (through 2016) have been presented in Anderson (2007), Litasov and Shatskiy (2016), Liu and Lin (2014), and Sumita and Bergman (2007), and the results of these studies are analyzed from the perspective of geomechanics in Guliyev (2017cGuliyev ( , 2018a. The results of new studies are reflected in numerous publications (Antonangeli et al, 2018;Birch, 1952;Chantel et al, 2016;Chen et al, 2018;Das et al, 2017;Fan, Xu, et al, 2019;Hakim et al, 2018;Huntington et al, 2017;Komabayashi, 2014;Komabayashi et al, 2019;Kusakabe et al, 2019;Mao et al, 2018;Qian et al, 2017;Sakairi et al, 2017;Sakamaki et al, 2016;Singh et al, 2017;Stekiel et al, 2017;Takahashi et al, 2019;Tanto et al, 2018;Tateno, 2018;Thompson et al, 2017;Wakamatsu et al, 2018;Xiong et al, 2018;Xu et al, 2019).…”

Section: Laboratory Experimental Work On the Physical Levelmentioning

confidence: 99%

“…New artificial test samples are created that change the initial data at each level of the thermobaric conditions. The theme of the experimental work can be summarized in the following expression underlined in Chen et al (2018). A comparison of the results of laboratory experiments with the results of the PREM implies that the composition of the inner core, which contains iron and its carbon-rich alloys, can satisfactorily explain the observed seismic properties of the inner core.…”

Section: Laboratory Experimental Work On the Physical Levelmentioning

confidence: 99%

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Once Again on Preliminary Reference Earth Model

Guliyev

Javanshir

2020

Earth and Space Science

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We studied the isotropic ball using data of Preliminary Reference Earth Model (PREM). It is shown that such a ball should be either destructed or gone into a more stable equilibrium state with uneven distributed deformation under thermobaric condition of the inner core. Body elastic waves with real velocities cannot propagate in it. This manuscript is devoted to study the situation from the standpoint of nonlinear geomechanics. A number of necessary principles of Mechanics of Deformable Solid Body (MDSB) is given at the beginning of the analysis. A brief review of the published latest experimental work is performed. It is established that proper attention to the role of the MDSB principles in micro‐scale (nano) experiments of the physical level has not been given. Deformation properties of solid bodies are emphasized in microscale and macroscale. Application of linear acoustoelasticity and extrapolation of Birch's linear law of the inner core and use of an idea on variability of elasticity moduli with the increase of pressure and temperature have contributed to obtained pseudo data for the geological medium of the Earth's core instead of linear data on the physicomechanical properties. It is proposed that parallel to elimination of the indicated disadvantages, collection, processing and interpretation should be performed using nonclassically linearized approach. This set of necessary actions is offered as the “key” of geomechanical analysis. The proper application will allow conducting similar analysis concerning other solid‐state structures of the Earth.

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Phase and Melting Relations of Fe ₃ C to 300 GPa and Carbon in the Core

Takahashi

Ohtani

Sakai

et al. 2020

Geophysical Monograph Series

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Carbon is a plausible candidate for a light element in the Earth's core. Here, we show that Fe 3 C melts incongruently to form Fe 7 C 3 and liquid at least up to 200 GPa based on in-situ X-ray diffraction measurements and textural observations of the recovered samples, and Fe 3 C is stable at least up to 300 GPa at high temperatures. The C content of the liquid coexisting with Fe 7 C 3 decreases and the Fe-Fe 3 C eutectic composition shifts toward the Fe-rich direction with increasing pressure. The present result revealed that both Fe 3 C and Fe 7 C 3 are plausible constituents in the inner core.

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Experimental constraints on the sound velocities of cementite Fe3C to core pressures

Cited by 34 publications

References 47 publications

Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

Once Again on Preliminary Reference Earth Model

Phase and Melting Relations of Fe ₃ C to 300 GPa and Carbon in the Core

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Experimental constraints on the sound velocities of cementite Fe3C to core pressures

Cited by 34 publications

References 47 publications

Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

Short- and Intermediate-Range Structure and Dynamics of Fe-Ni-C Liquid Under Compression

Once Again on Preliminary Reference Earth Model

Phase and Melting Relations of Fe 3 C to 300 GPa and Carbon in the Core

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Phase and Melting Relations of Fe ₃ C to 300 GPa and Carbon in the Core