Experimental melting curve of iron revisited

Anderson, Orson L.; Duba, A.

doi:10.1029/97jb01641

Cited by 72 publications

(33 citation statements)

References 57 publications

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“…Combining ab initio calculations and seismic data, Alfè et al [2002] calculated the melting temperature of Fe‐2.5O‐6.4S and suggested that the melting temperature depression Δ T m is about 700 K at the pressure of 330 GPa. It seems that the conclusion of Alfè et al [2002] is consistent with the predictions of Stevenson [1981] Anderson and Duba [1997], and Anderson et al [1998]. However, when we apply Stevenson 's [1981] and Anderson 's [1998] equations to estimate Δ T m with the amounts of O and S and other values given by Alfè et al [2002], the value of Δ T m is about 1800 ∼ 2400 K, which is much higher than the Δ T m ∼ 700 K proposed by Alfè et al [2002].…”

Section: Introductionsupporting

confidence: 83%

Melting behavior of Fe‐O‐S at high pressure: A discussion on the melting depression induced by O and S

Huang

Jing

et al. 2010

J. Geophys. Res.

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Shock compressed to pressures from 106 GPa to 232 GPa, the sound velocities were determined in Fe‐O‐S (90/8/2 in wt. %), regarded as the candidate compositions of the Earth's outer core. A discontinuity in sound velocity versus pressure relation was observed, which indicated that the shocked sample is initially melted at 149 GPa and completely melted at 167 GPa. On the basis of an energy conservation formulation, the calculated equilibrium melting temperature is about 3880 ± 500 K at 167 GPa. Taking this point as a reference, a high‐pressure melting curve can be inferred through Lindemann Law, which is again confirmed by the release melting temperatures of 3020 ± 500 K and 3200 ± 500 K measured at 90 GPa and 106 GPa, respectively. When extrapolating this melting curve to inner core‐outer core boundary (330 GPa), the melting temperature of this Fe‐O‐S composition is about 5400 ± 500K. Compared with the melting temperature 6000 K for pure iron at 330 GPa, the corresponding melting temperature depression is about 600 K due to the effect of O and S.

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Section: Introductionsupporting

confidence: 83%

Melting behavior of Fe‐O‐S at high pressure: A discussion on the melting depression induced by O and S

Huang

Jing

et al. 2010

J. Geophys. Res.

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“…This pressure is somewhat higher than the ICB pressure of 330 GPa [30]. The temperature is also higher than that at the ICB: our ab initio melting curve gives a melting temperature of ∼ 6350 K (or ∼ 6200 K after the correction due to our estimate of likely DFT errors) [18] at the ICB pressure of 330 GPa, which is already higher than some other estimates [28,47]. But we shall see below that depression of freezing point due to impurity partitioning lowers this by a further ∼ 700 K. We have made rough estimates which show that the difference between 7000 K and our estimated ICB temperature is unlikely to change the chemical potentials of S and Si by more than 0.1 eV and that of O by more than 0.3 eV, which will have no significant effect on our conclusions.…”

Section: The Liquidmentioning

confidence: 68%

Ab initio chemical potentials of solid and liquid solutions and the chemistry of the Earth’s core

Gillan

Price

2002

The Journal of Chemical Physics

111

114

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A general set of methods is presented for calculating chemical potentials in solid and liquid mixtures using ab initio techniques based on density functional theory (DFT). The methods are designed to give an ab initio approach to treating chemical equilibrium between coexisting solid and liquid solutions, and particularly the partitioning ratio of solutes between such solutions. For the liquid phase, the methods are based on the general technique of thermodynamic integration, applied to calculate the change of free energy associated with the continuous interconversion of solvent and solute atoms, the required thermal averages being computed by DFT molecular dynamics simulation. For the solid phase, free energies and hence chemical potentials are obtained using DFT calculation of vibrational frequencies of systems containing substitutional solute atoms, with anharmonic contributions calculated, where needed, by thermodynamic integration. The practical use of the methods is illustrated by applying them to study chemical equilibrium between the outer liquid and inner solid parts of the Earth's core, modelled as solutions of S, Si and O in Fe. The calculations place strong constraints on the chemical composition of the core, and allow an estimate of the temperature at the inner-core/outer-core boundary.

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“…The knowledge of iron EOS is then essential to the construction of a realistic model of Earth and in particular the description of the transition between the liquid outer core and the solid inner core. Many recent works have been devoted to the structure of Earth's core and the iron EOS in geophysical context [1][2][3][4][5][6][7][8][9]. Iron EOS at pressures higher than reached inside the Earth is also interesting for many reasons.…”

mentioning

confidence: 99%

Equation of State Data for Iron at Pressures beyond 10 Mbar

et al. 2002

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We present equation of state points for iron, in the pressure range 10 -45 Mbar, the first obtained with laser-driven shock waves. The experiment has been performed with the high energy laser Phebus, optically smoothed with Kinoform phase plates. Our results double the set of existing experimental data at very high pressures showing good agreement with the predictions of the quotidian equation of state model and with previous results.

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Experimental melting curve of iron revisited

Abstract: Birch [1972]

Cited by 72 publications

References 57 publications

Melting behavior of Fe‐O‐S at high pressure: A discussion on the melting depression induced by O and S

Melting behavior of Fe‐O‐S at high pressure: A discussion on the melting depression induced by O and S

Ab initio chemical potentials of solid and liquid solutions and the chemistry of the Earth’s core

Equation of State Data for Iron at Pressures beyond 10 Mbar

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