scholarly journals Electronic correlations in Fe at Earth's inner core conditions: Effects of alloying with Ni

2015 ◽  
Vol 91 (24) ◽  
Author(s):  
O. Yu. Vekilova ◽  
L. V. Pourovskii ◽  
I. A. Abrikosov ◽  
S. I. Simak
Keyword(s):  
Inner Core ◽  
Electronic Correlations ◽  
Earth’S Inner Core ◽  
Core Conditions

Measuring the melting curve of iron at super-Earth core conditions

Science ◽  
2022 ◽  
Vol 375 (6577) ◽  
pp. 202-205
Author(s):  
Richard G. Kraus ◽  
Russell J. Hemley ◽  
Suzanne J. Ali ◽  
Jonathan L. Belof ◽  
Lorin X. Benedict ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Inner Core ◽  
Melting Curve ◽  
Radiation Shielding ◽  
Metal Core ◽  
Earth Core ◽  
Core Boundary ◽  
Earth Like Planets ◽  
Earth’S Inner Core ◽  
Core Conditions

Terapascal iron-melting temperature The pressure and temperature conditions at which iron melts are important for terrestrial planets because they determine the size of the liquid metal core, an important factor for understanding the potential for generating a radiation-shielding magnetic field. Kraus et al . used laser-driven shock to determine the iron-melt curve up to a pressure of 1000 gigapascals (see the Perspective by Zhang and Lin). This value is about three times that of the Earth’s inner core boundary. The authors found that the liquid metal core lasted the longest for Earth-like planets four to six times larger in mass than the Earth. —BG

scholarly journals Stability of body-centered cubic iron–magnesium alloys in the Earth's inner core

2009 ◽  
Vol 106 (37) ◽  
pp. 15560-15562 ◽  
Author(s):  
Krisztina Kádas ◽  
Levente Vitos ◽  
Börje Johansson ◽  
Rajeev Ahuja
Keyword(s):  
Inner Core ◽  
The Body ◽  
Mg Alloys ◽  
Functional Study ◽  
Body Centered Cubic ◽  
Calculated Density ◽  
The Core ◽  
Earth’S Inner Core ◽  
Core Conditions ◽  
Bcc Phase

The composition and the structure of the Earth's solid inner core are still unknown. Iron is accepted to be the main component of the core. Lately, the body-centered cubic (bcc) phase of iron was suggested to be present in the inner core, although its stability at core conditions is still in discussion. The higher density of pure iron compared with that of the Earth's core indicates the presence of light element(s) in this region, which could be responsible for the stability of the bcc phase. However, so far, none of the proposed composition models were in full agreement with seismic observations. The solubility of magnesium in hexagonal Fe has been found to increase significantly with increasing pressure, suggesting that Mg can also be an important element in the core. Here, we report a first-principles density functional study of bcc Fe–Mg alloys at core pressures and temperatures. We show that at core conditions, 5–10 atomic percent Mg stabilizes the bcc Fe both dynamically and thermodynamically. Our calculated density, elastic moduli, and sound velocities of bcc Fe–Mg alloys are consistent with those obtained from seismology, indicating that the bcc-structured Fe–Mg alloy is a possible model for the Earth's inner core.

scholarly journals No system-size anomalies in entropy of bcc iron at Earth’s inner-core conditions

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Andrew J. Schultz ◽  
Sabry G. Moustafa ◽  
David A. Kofke
Keyword(s):  
Inner Core ◽  
System Size ◽  
Bcc Iron ◽  
Earth’S Inner Core ◽  
Core Conditions

scholarly journals Two-phase mixture of iron–nickel–silicon alloys in the Earth’s inner core

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Daijo Ikuta ◽  
Eiji Ohtani ◽  
Naohisa Hirao
Keyword(s):  
Inner Core ◽  
Earth Model ◽  
Two Phase ◽  
Silicon Alloys ◽  
Hexagonal Close Packed ◽  
Iron Nickel ◽  
Earth’S Inner Core ◽  
Phase Mixture ◽  
Core Conditions ◽  
Nickel Silicon

AbstractThe Earth’s inner core comprises iron-nickel alloys with light elements. However, there is no clarity on the phase properties of these alloys. Here we show phase relations and equations of state of iron–nickel and iron–nickel–silicon alloys up to 186 gigapascals and 3090 kelvin. An ordered derivative of the body-centred cubic structure (B2) phase was observed in these alloys. Results show that nickel and silicon influence the stability field associated with the two-phase mixture of B2 and hexagonal close-packed phases under core conditions. The two-phase mixture can give the inner core density of the preliminary reference Earth model. The compressional wave velocity of the two-phase mixture under inner core conditions is consistent with that of the preliminary reference Earth model. Therefore, a mixture of B2 and hexagonal close-packed phases may exist in the inner core and accounts for the seismological properties of the inner core such as density and velocity deficits.

scholarly journals The elastic properties of hcp-Fe 1−x Si x at Earth's inner-core conditions

2016 ◽  
Vol 451 ◽  
pp. 89-96 ◽  
Author(s):  
Benjamí Martorell ◽  
Ian G. Wood ◽  
John Brodholt ◽  
Lidunka Vočadlo
Keyword(s):  
Elastic Properties ◽  
Inner Core ◽  
Earth’S Inner Core ◽  
Core Conditions

scholarly journals Electronic properties and magnetism of iron at the Earth's inner core conditions

2013 ◽  
Vol 87 (11) ◽  
Author(s):  
L. V. Pourovskii ◽  
T. Miyake ◽  
S. I. Simak ◽  
A. V. Ruban ◽  
L. Dubrovinsky ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Inner Core ◽  
Earth’S Inner Core ◽  
Core Conditions

scholarly journals Properties Evaluation of Fe95-xSi5Nix Under the Earth's Inner-Core Conditions: Insight from the Ab-Initio Investigation

2021 ◽  
Author(s):  
Mustapha Zidane ◽  
El Mehdi Salmani ◽  
Meryem Elmoulat ◽  
Hamid EZ-ZAHRAOUY ◽  
Abdelilah Benyoussef
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Inner Core ◽  
Local Density ◽  
Ternary Alloys ◽  
Vertex Correction ◽  
Functional Density Theory ◽  
Earth’S Inner Core ◽  
Core Conditions ◽  
Major Factors

Abstract In this article we investigate under the same Earth's core conditions, the structural, electronic, and transport properties of Fe-Si-Ni ternary alloys based on Fe and 5% of Si with various concentrations 0%, 15%, 25%, and 40% of element Ni, by means of First-principles calculations. Based on Functional Density Theory (DFT). The Local Density Approximation (LDA) also has been adopted for the potential exchange correlation. We perform the calculation of electronic property at 360 GPa using the software Akai-KKR (machikaneyama), which used the Korringa-Kohn-Rostoker method along with coherent potential approximation (KKR-CPA). Afterward, we calculate the electrical resistivity of impurities formed on the Kubo-Greenwood formula with the vertex correction using SPR-KKR code, which is based on the relativistic polarized spin method. Then, we model the thermal conductivity by electrical resistivity for both varying in the range of 320–360 GPa and 4500-6000k of pressure and temperature, respectively; according to the conditions of the Earth’s inner core ICB using Wiedemann-Franz law. Hence, our results suggest that 85–115 µΩ·cm at 0 K and 320–360 GPa, then 225–285 µΩ·cm at 4500–6000 K and 360 GPa for electrical resistivity, and then 45–55 W·m− 1·K− 1 at 4500–6000 K and 360 GPa of thermal conductivity of Earth’s inner core. Lastly, the thermal and compositional convection is one of the major factors of global magnetic field that is generated by geodynamo driven.

scholarly journals Two-step nucleation of the Earth’s inner core

2022 ◽  
Vol 119 (2) ◽  
pp. e2113059119
Author(s):  
Yang Sun ◽  
Feng Zhang ◽  
Mikhail I. Mendelev ◽  
Renata M. Wentzcovitch ◽  
Kai-Ming Ho
Keyword(s):  
Molecular Dynamics ◽  
Inner Core ◽  
Nucleation Mechanism ◽  
Body Centered Cubic ◽  
Hexagonal Close Packed ◽  
Key Factor ◽  
Earth’S Inner Core ◽  
Core Conditions ◽  
Dynamics Simulations ◽  
Bcc Phase

The Earth's inner core started forming when molten iron cooled below the melting point. However, the nucleation mechanism, which is a necessary step of crystallization, has not been well understood. Recent studies have found that it requires an unrealistic degree of undercooling to nucleate the stable, hexagonal, close-packed (hcp) phase of iron that is unlikely to be reached under core conditions and age. This contradiction is referred to as the inner core nucleation paradox. Using a persistent embryo method and molecular dynamics simulations, we demonstrate that the metastable, body-centered, cubic (bcc) phase of iron has a much higher nucleation rate than does the hcp phase under inner core conditions. Thus, the bcc nucleation is likely to be the first step of inner core formation, instead of direct nucleation of the hcp phase. This mechanism reduces the required undercooling of iron nucleation, which provides a key factor in solving the inner core nucleation paradox. The two-step nucleation scenario of the inner core also opens an avenue for understanding the structure and anisotropy of the present inner core.

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