Sound velocity and elastic properties of Fe–Ni and Fe–Ni–C liquids at high pressure

Kuwabara, Shigeya; Terasaki, Hidenori; Nishida, Keisuke; Shimoyama, Yuta; Takubo, Yusaku; Higo, Yuji; Shibazaki, Yuki; Urakawa, Satoru; Uesugi, Kentaro; Takeuchi, Akihisa; Kondo, Tadashi

doi:10.1007/s00269-015-0789-y

Cited by 22 publications

(29 citation statements)

References 31 publications

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“…The thermodynamic properties of liquid iron at a pressure of 0.1 MPa calculated from our EoS (Supplementary Table S4) are in good agreement with the measured values of density84, the sound velocity ( v P ) and adiabatic bulk modulus848586. The calculated entropy at pressure 0.1 MPa is very close to the reference data9.…”

Section: Eoss For Solid and Liquid Fe To 350 Gpasupporting

confidence: 82%

Thermodynamics and Equations of State of Iron to 350 GPa and 6000 K

Dorogokupets

Dymshits

Litasov

et al. 2017

Sci Rep

101

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The equations of state for solid (with bcc, fcc, and hcp structures) and liquid phases of Fe were defined via simultaneous optimization of the heat capacity, bulk moduli, thermal expansion, and volume at room and higher temperatures. The calculated triple points at the phase diagram have the following parameters: bcc–fcc–hcp is located at 7.3 GPa and 820 K, bcc–fcc–liquid at 5.2 GPa and 1998 K, and fcc–hcp–liquid at 106.5 GPa and 3787 K. At conditions near the fcc–hcp–liquid triple point, the Clapeyron slope of the fcc–liquid curve is dT/dP = 12.8 K/GPa while the slope of the hcp–liquid curve is higher (dT/dP = 13.7 K/GPa). Therefore, the hcp–liquid curve overlaps the metastable fcc–liquid curve at pressures of about 160 GPa. At high-pressure conditions, the metastable bcc–hcp curve is located inside the fcc-Fe or liquid stability field. The density, adiabatic bulk modulus and P-wave velocity of liquid Fe calculated up to 328.9 GPa at adiabatic temperature conditions started from 5882 K (outer/inner core boundary) were compared to the PREM seismological model. We determined the density deficit of hcp-Fe at the inner core boundary (T = 5882 K and P = 328.9 GPa) to be 4.4%.

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Section: Eoss For Solid and Liquid Fe To 350 Gpasupporting

confidence: 82%

Thermodynamics and Equations of State of Iron to 350 GPa and 6000 K

Dorogokupets

Dymshits

Litasov

et al. 2017

Sci Rep

101

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“…Indeed, recognizable compressibility behavior anomalies reported for liquids Fe‐5.7 wt % C (Sanloup et al, ), Fe‐6.7 wt % C (Terasaki et al, ), and Fe‐3.5 wt % C (Shimoyama et al, ) at ~5 GPa can be readily explained by the liquid structure transition. Measurements for viscosity (Terasaki et al, ) and sound velocity (Kuwabara et al, ; Shimoyama et al, ) for Fe‐(Ni)‐C liquids are limited to <5 GPa or extremely sparse, and the effect of structural transition on these properties remains unclear. On the analogy of metallic glass systems in which clusters with three‐atom connections are stiffer than the two‐atom and four‐atom counterparts (Ding et al, ), higher viscosity is anticipated for the Fe‐Ni‐C liquids with higher fraction of three‐atom connections above ~5 GPa.…”

Section: Discussion and Geophysical Implicationsmentioning

confidence: 99%

“…In the present study, the Fe‐Ni‐C system is considered, because of the high cosmochemical abundance of carbon, frequent occurrence of Fe carbide phases in meteorites, and high affinity and solubility of carbon in Fe‐Ni liquids under the core‐mantle differentiation conditions (Chen & Li, ; Dasgupta & Walker, ; Wood, ; Wood et al, ). Limited experimental data on the thermoeleastic and viscoelastic properties of the Fe‐Ni‐C liquids, however, have restricted our discussion of carbon‐bearing planetary core compositional models (Kuwabara et al, ; Sanloup et al, ; Shimoyama et al, , ; Terasaki et al, ).…”

Section: Introductionmentioning

confidence: 99%

Polyamorphic Transformations in Fe‐Ni‐C Liquids: Implications for Chemical Evolution of Terrestrial Planets

et al. 2017

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During the formation of the Earth's core, the segregation of metallic liquids from silicate mantle should have left behind evident geochemical imprints on both the mantle and the core. Some distinctive geochemical signatures of the mantle‐derived rocks likely own their origin to the metal‐silicate differentiation of the primitive Earth, setting our planet apart from undifferentiated meteorites as well as terrestrial planets or moons isotopically and compositionally. Understanding the chemical evolution of terrestrial planetary bodies requires knowledge on properties of both liquid iron alloys and silicates equilibrating under physicochemical conditions pertinent to the deep magma ocean. Here we report experimental and computational results on the pressure‐induced structural evolution of iron‐nickel liquids alloyed with carbon. Our X‐ray diffraction experiments up to 7.3 gigapascals (GPa) demonstrate that Fe‐Ni (Fe90Ni10) liquids alloyed with 3 and 5 wt % carbon undergo a polyamorphic liquid structure transition at approximately 5 GPa. Corroborating the experimental observations, our first‐principles molecular dynamic calculations reveal that the structural transitions result from the marked prevalence of three‐atom face‐sharing polyhedral connections in the liquids at >5 GPa. The structure and polyamorphic transitions of liquid iron‐nickel‐carbon alloys govern their physical and chemical properties and may thus cast fresh light on the chemical evolution of terrestrial planets and moons.

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“…The density was measured using the X‐ray absorption method based on the Beer‐Lambert law or using the X‐ray computed tomography (CT) measurement. For the measurements below 1 GPa, an 80‐ton portable uniaxial press (Urakawa et al, ) was used combined with X‐ray computed‐tomography (CT) measurements (Kuwabara et al, ) at the BL20XU beamline, SPring‐8 synchrotron radiation facility in Japan. High pressure was generated using opposing cupped WC anvils (diameter of the center cup was 12 mm) with a ringed groove.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, the compressional wave velocities ( V P ) of liquid Fe‐Ni, Fe‐S, and Fe‐C have been measured in static high‐pressure experiments. These results show that S, C, and Ni reduce the V P of liquid Fe at pressures below 10 GPa (Jing et al, ; Kuwabara et al, ; Nishida et al, , ; Shimoyama et al, ), while S and C increase the V P of liquid Fe above 10 GPa (Kawaguchi et al, ; Nakajima et al, ). To explain these trends, a possible change in the structure and electronic properties of liquid Fe‐S is thought to occur at around 10 GPa (Kawaguchi et al, ).…”

Section: Introductionmentioning

confidence: 95%

Pressure and Composition Effects on Sound Velocity and Density of Core‐Forming Liquids: Implication to Core Compositions of Terrestrial Planets

et al. 2019

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A compositional variety of planetary cores provides insight into their core/mantle evolution and chemistry in the early solar system. To infer core composition from geophysical data, a precise knowledge of elastic properties of core‐forming materials is of prime importance. Here, we measure the sound velocity and density of liquid Fe‐Ni‐S (17 and 30 at% S) and Fe‐Ni‐Si (29 and 38 at% Si) at high pressures and report the effects of pressure and composition on these properties. Our data show that the addition of sulfur to iron substantially reduces the sound velocity of the alloy and the bulk modulus in the conditions of this study, while adding silicon to iron increases its sound velocity but has almost no effect on the bulk modulus. Based on the obtained elastic properties combined with geodesy data, S or Si content in the core is estimated to 4.6 wt% S or 10.5 wt% Si for Mercury, 9.8 wt% S or 18.3 wt% Si for the Moon, and 32.4 wt% S or 30.3 wt% Si for Mars. In these core compositions, differences in sound velocity profiles between an Fe‐Ni‐S and Fe‐Ni‐Si core in Mercury are small, whereas for Mars and the Moon, the differences are substantially larger and could be detected by upcoming seismic sounding missions to those bodies.

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Sound velocity and elastic properties of Fe–Ni and Fe–Ni–C liquids at high pressure

Cited by 22 publications

References 31 publications

Thermodynamics and Equations of State of Iron to 350 GPa and 6000 K

Thermodynamics and Equations of State of Iron to 350 GPa and 6000 K

Polyamorphic Transformations in Fe‐Ni‐C Liquids: Implications for Chemical Evolution of Terrestrial Planets

Pressure and Composition Effects on Sound Velocity and Density of Core‐Forming Liquids: Implication to Core Compositions of Terrestrial Planets

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