scholarly journals Thermodynamics of hexagonal-close-packed iron under Earth’s core conditions

2001 ◽  
Vol 64 (4) ◽  
Author(s):  
D. Alfè ◽  
G. D. Price ◽  
M. J. Gillan
Keyword(s):  
Earth’S Core ◽  
Earth's Core ◽  
Hexagonal Close Packed ◽  
Core Conditions

scholarly journals New high-pressure phases of Fe7N3 and Fe7C3 stable at Earth's core conditions: evidences for carbon–nitrogen isomorphism in Fe-compounds

RSC Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 3577-3581 ◽  
Author(s):  
Nursultan Sagatov ◽  
Pavel N. Gavryushkin ◽  
Talgat M. Inerbaev ◽  
Konstantin D. Litasov
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Ab Initio ◽  
Structure Prediction ◽  
Harmonic Approximation ◽  
Crystal Structure Prediction ◽  
Earth’S Core ◽  
Earth's Core ◽  
Core Conditions

We carried out ab initio calculations on the crystal structure prediction and determination of P–T diagrams within the quasi-harmonic approximation for Fe7N3 and Fe7C3.

scholarly journals First-principles calculations of properties of orthorhombic iron carbideFe7C3at the Earth's core conditions

2015 ◽  
Vol 91 (21) ◽  
Author(s):  
Zamaan Raza ◽  
Nina Shulumba ◽  
Nuala M. Caffrey ◽  
Leonid Dubrovinsky ◽  
Igor A. Abrikosov
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Earth’S Core ◽  
Earth's Core ◽  
Core Conditions

The Thermal Conductivity of Earth's Core: A Key Geophysical Parameter's Constraints and Uncertainties

2018 ◽  
Vol 46 (1) ◽  
pp. 47-66 ◽  
Author(s):  
Q. Williams
Keyword(s):  
Thermal Conductivity ◽  
High Pressures ◽  
Inner Core ◽  
Thermal Evolution ◽  
Magnetic Moments ◽  
Earth’S Core ◽  
Earth's Core ◽  
Current State ◽  
Core Conditions

The thermal conductivity of iron alloys at high pressures and temperatures is a critical parameter in governing ( a) the present-day heat flow out of Earth's core, ( b) the inferred age of Earth's inner core, and ( c) the thermal evolution of Earth's core and lowermost mantle. It is, however, one of the least well-constrained important geophysical parameters, with current estimates for end-member iron under core-mantle boundary conditions varying by about a factor of 6. Here, the current state of calculations, measurements, and inferences that constrain thermal conductivity at core conditions are reviewed. The applicability of the Wiedemann-Franz law, commonly used to convert electrical resistivity data to thermal conductivity data, is probed: Here, whether the constant of proportionality, the Lorenz number, is constant at extreme conditions is of vital importance. Electron-electron inelastic scattering and increases in Fermi-liquid-like behavior may cause uncertainties in thermal conductivities derived from both first-principles-associated calculations and electrical conductivity measurements. Additional uncertainties include the role of alloying constituents and local magnetic moments of iron in modulating the thermal conductivity. Thus, uncertainties in thermal conductivity remain pervasive, and hence a broad range of core heat flows and inner core ages appear to remain plausible.

scholarly journals Approaching Earth’s core conditions in high-resolution geodynamo simulations

2019 ◽  
Vol 219 (Supplement_1) ◽  
pp. S137-S151 ◽  
Author(s):  
Julien Aubert
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Large Scale ◽  
Small Scale ◽  
Low Resolution ◽  
Earth’S Core ◽  
Earth's Core ◽  
Density Anomaly ◽  
Core Conditions ◽  
The Magnetic Field

SUMMARY The geodynamo features a broad separation between the large scale at which Earth’s magnetic field is sustained against ohmic dissipation and the small scales of the turbulent and electrically conducting underlying fluid flow in the outer core. Here, the properties of this scale separation are analysed using high-resolution numerical simulations that approach closer to Earth’s core conditions than earlier models. The new simulations are obtained by increasing the resolution and gradually relaxing the hyperdiffusive approximation of previously published low-resolution cases. This upsizing process does not perturb the previously obtained large-scale, leading-order quasi-geostrophic (QG) and first-order magneto-Archimedes-Coriolis (MAC) force balances. As a result, upsizing causes only weak transients typically lasting a fraction of a convective overturn time, thereby demonstrating the efficiency of this approach to reach extreme conditions at reduced computational cost. As Earth’s core conditions are approached in the upsized simulations, Ohmic losses dissipate up to 97 per cent of the injected convective power. Kinetic energy spectra feature a gradually broadening self-similar, power-law spectral range extending over more than a decade in length scale. In this range, the spectral energy density profile of vorticity is shown to be approximately flat between the large scale at which the magnetic field draws its energy from convection through the QG-MAC force balance and the small scale at which this energy is dissipated. The resulting velocity and density anomaly planforms in the physical space consist in large-scale columnar sheets and plumes, respectively, co-existing with small-scale vorticity filaments and density anomaly ramifications. In contrast, magnetic field planforms keep their large-scale structure after upsizing. The small-scale vorticity filaments are aligned with the large-scale magnetic field lines, thereby minimizing the dynamical influence of the Lorentz force. The diagnostic outputs of the upsized simulations are more consistent with the asymptotic QG-MAC theory than those of the low-resolution cases that they originate from, but still feature small residual deviations that may call for further theoretical refinements to account for the structuring constraints of the magnetic field on the flow.

scholarly journals Dynamical stability of body center cubic iron at the Earth's core conditions

2010 ◽  
Vol 107 (22) ◽  
pp. 9962-9964 ◽  
Author(s):  
W. Luo ◽  
B. Johansson ◽  
O. Eriksson ◽  
S. Arapan ◽  
P. Souvatzis ◽  
...  
Keyword(s):  
Dynamical Stability ◽  
Earth’S Core ◽  
Earth's Core ◽  
Body Center Cubic ◽  
Body Center ◽  
Core Conditions

scholarly journals First-principles simulations of liquid Fe-S under Earth’s core conditions

1998 ◽  
Vol 58 (13) ◽  
pp. 8248-8256 ◽  
Author(s):  
Dario Alfè ◽  
Michael J. Gillan
Keyword(s):  
First Principles ◽  
Earth’S Core ◽  
Earth's Core ◽  
Core Conditions
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