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

Kraus, R. G.; Hemley, Russell J.; Ali, Suzanne; Belof, Jonathan L.; Benedict, Lorin X.; Braun, D. G.; Cohen, R. E.; Collins, G. W.; Coppari, F.; Desjarlais, M. P.; Fratanduono, D. E.; Hamel, Sébastien; Krygier, A.; Lazicki, Amy; McNaney, J. M.; Millot, Marius; Myint, Philip C.; Newman, M.; Rygg, J. R.; Sterbentz, Dane M.; Stewart, S. T.; Stixrude, Lars; Swift, Damian; Eggert, J. H.

doi:10.1126/science.abm1472

Cited by 65 publications

(34 citation statements)

References 72 publications

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“…Combining eqn (14) and (15) yieldswhereNext, to minimize the number of empirical inputs for WHEP calculations, we constrain T 1 ( P 1 ) and T 2 ( P 2 ) by T 1 ( P 1 ) = T m (0),Interestingly, the initial melting gradient can be linked to the bulk modulus via the Lindemann criterion as 58 Entering eqn (20)–(22) into eqn (18) provides us with the final expression for the melting profile asUnlike eqn (17) and (23) only requires empirical information about the zero-pressure melting temperature T m (0). To verify the reliability and flexibility of eqn (23), we perform numerical calculations for tantalum, 59–62 iron, 63–66 and magnesium oxide 67–70 because their melting behaviors have been thoroughly measured by modern DAC and SW methods. As presented in Section II and Fig.…”

Section: Resultsmentioning

confidence: 99%

Toward better understanding of the high-pressure structural transformation in beryllium by the statistical moment method

Cuong

Phan

2023

Phys. Chem. Chem. Phys.

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Section: Resultsmentioning

confidence: 99%

Toward better understanding of the high-pressure structural transformation in beryllium by the statistical moment method

Cuong

Phan

2023

Phys. Chem. Chem. Phys.

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“…We note that, although the Jian et al. model is nominally designed for ambient-pressure conditions, we have found that, when coupled with an appropriate equation of state, it is possible to adjust the single empirical fitting parameter ξ in their model to yield reasonable results for solid–liquid interfaces in water/ice VII, ,− gallium, and iron at high-pressure conditions. The new model that we present in this work, while it is still largely phenomenological in nature like the others we have discussed, is nevertheless expected to provide a more realistic representation of the underlying behavior at high pressures.…”

Section: Methodsmentioning

confidence: 95%

Model for the Solid–Liquid Interfacial Free Energy at High Pressures

et al. 2022

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The free energy involved in the formation of an interface between two phases (e.g., a solid−liquid interface) is referred to as the interfacial free energy. For the case of solidification, the interfacial free energy dictates the height of the energy barrier required to nucleate stable clusters of the newly forming solid phase and is essential for producing an accurate solidification kinetics model using classical nucleation theory (CNT)-based methods. While various methods have been proposed for modeling the interfacial free energy for solid−liquid interfaces in prior literature, many of these formulations involve making restrictive assumptions or approximations, such as the system being at or near equilibrium (i.e., the system temperature is approximately equal to the melt temperature) or that the system is at pressures close to atmospheric. However, these approximations and assumptions may break down in highly non-equilibrium situations, such as in dynamic-compression experiments where metastable liquids that are undercooled by hundreds of kelvin or overpressurized by several gigapascals or more are formed before eventually solidifying. We derive a solid−liquid interfacial free-energy model for such high-pressure conditions by considering the enthalpies of interactions between pairs of atoms or molecules. We also consider the contribution of interface roughness (disordering) by incorporating a multilayer interface model known as the Temkin n-layer model. Our formulation is applicable to a diverse variety of materials, and we demonstrate it by developing models specifically for two different materials: water and gallium. We apply our interfacial free-energy formulation to CNT-based kinetics simulations of several suites of dynamic-compression experiments that cause liquid water to solidify to the high-pressure solid polymorph ice VII and have found good agreement to the observed kinetics with only minor empirical fitting.

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“…For example, measurements of the dissipated thermal energy by means of infrared detection have been found to be rather sensitive to the calibration procedure, with updates to this procedure able to change the apparent TQC by as much as a factor of two [9]. During material tests performed at most extreme deformation rates, e.g., at the National Ignition Facility [10,11], uncertainty in specimen temperature can reach hundreds of Kelvin making extraction of the material's intrinsic thermo-mechanical properties quite difficult. Despite (or perhaps due to) our continually expanding and improving experimental capabilities, the range of TQC values appearing in the literature is not narrowing, and if anything has expanded to the entire interval between 0.1 and 1.0.…”

Section: Introductionmentioning

confidence: 99%

Energy storage under high-rate compression of single crystal tantalum

Stimac,

Bertin,

Mason

et al. 2022

Preprint

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When a material is plastically deformed the majority of mechanical work is dissipated as heat, and the fraction of plastic work converted into heat is known as the Taylor-Quinney coefficient (TQC). Large-scale molecular dynamics simulations were performed of high strain rate compression of single-crystal tantalum, and the resulting integral and differential TQC values are reported up to true strains of 1.0. A phenomenological model is proposed for the energy stored in the material as a function of plastic strain with an asymptotic limit for this energy defined by the deformation conditions. The model reasonably describes the convergence of TQC values to 1.0 with increasing plastic strain, but leaves aside the physical nature of thermo-mechanical conversion. This is instead developed in a second more detailed model that accurately accounts for energy storage in two distinct contributions, one being the growing dislocation network and the other the point defect debris left behind by moving dislocations. The contribution of the point defect debris is found to lag behind that of the dislocation network but to be substantial under high-rate straining conditions considered here.

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

Cited by 65 publications

References 72 publications

Toward better understanding of the high-pressure structural transformation in beryllium by the statistical moment method

Toward better understanding of the high-pressure structural transformation in beryllium by the statistical moment method

Model for the Solid–Liquid Interfacial Free Energy at High Pressures

Energy storage under high-rate compression of single crystal tantalum

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