Viscosity of liquid Na–K alloys from molecular dynamics simulations

Becker, Sandrine; Meyer, Nadège; Xu, Hòng; Wax, J.-F.

doi:10.1088/1361-648x/ab6d13

Cited by 3 publications

(5 citation statements)

References 15 publications

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“…The accuracy of the description of the interactions is an important question which must be discussed. We have chosen this description since Fiolhais potential [24] combined with Ichimaru-Utsumi [28] screening functions has already shown very good ability to describe interatomic interactions in the case of pure and binary alloys of alkali metals over wide ranges of temperatures and densities (see for instance [22,23,29] and references therein). In the scope of this study of a ternary alloy, it will be ascertained by comparison of the predictions of the simulations with available experimental data (viscosity and melting point).…”

Section: Interaction Descriptionmentioning

confidence: 99%

“…We used the set of configurations generated during the whole production stage to obtain a well-converged evaluation of the stressautocorrelation function (SACF) δσ αβ (0)δσ αβ (t) where notation • • • refers to thermodynamic mean. The viscosity was then obtained from Green-Kubo formula and its determination was refined using the same approach as described in reference [23].…”

Section: Simulation Details and Physical Properties Implementationmentioning

confidence: 99%

“…Therefore, in this article, we present a study of this very special alloy from 100 K to 1000 K. We use classical molecular dynamics to investigate several properties: structure and chemical order, self-diffusion and viscosity. Following previous studies of alkali metals [8,9,[21][22][23], we use a pair potential derived from Fiolhais et al [24] pseudo potential to describe the interactions between the atoms in the mixture. The accuracy of this description in the case of this alloy is ascertained by comparing the predictions of our simulations with available experimental data.…”

Section: Introductionmentioning

confidence: 99%

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Numerical simulation study of a low freezing point metallic alloy: Na–K–Cs

Harchaoui¹,

Jf²

2021

J. Phys.: Condens. Matter

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A molecular dynamics study is performed of liquid Na 0.139 K 0.435 Cs 0.426 alloy known to have the lowest reported freezing point (195.2 K). Using Fiolhais's pair potential, we study the temperature dependence of the atomic structure of this alloy from 100 to 1000 K. Na atoms appear to play an important role in the lowering of its melting temperature. The self-diffusion coefficients as well as the viscosity are also computed. Their temperature dependence does not show any unusual behaviour. However, as temperature is nearing the melting point, diffusion and viscosity reach uncommon values for this kind of materials.

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Section: Interaction Descriptionmentioning

confidence: 99%

Section: Simulation Details and Physical Properties Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical simulation study of a low freezing point metallic alloy: Na–K–Cs

Harchaoui¹,

Jf²

2021

J. Phys.: Condens. Matter

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“…It provides valuable information on the atomic arrangement and interatomic interaction forces from a microscopic perspective [1][2][3][4]. On the one hand, density reflects the atomic arrangement information of liquid alloys, which is of great value to the research of liquid structure [5,6]. On the other hand, it serves as a vital parameter for measuring or evaluating other thermophysical properties, such as thermal expansion coefficient, viscosity and surface tension [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Thermophysical properties and atomic structure of liquid Zr–Nb alloys investigated by electrostatic levitation and molecular dynamics simulation

Zuo,

Chang,

Wang

et al. 2023

J. Phys.: Condens. Matter

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The investigation of the thermophysical properties of liquid Zr–Nb alloys holds great significance for theoretical research and technical application in liquid physics. However, the high temperatures involved make their experimental measurement challenging. In this study, the densities of liquid Zr-x wt.% Nb (x= 1.0, 2.5, 6.0) alloys were examined by electrostatic levitation and molecular dynamics calculation. Remarkably, the alloys achieved maximum undercooling of 335 K, 311 K and 326 K, respectively. Correspondingly, the densities are 6.20, 6.22 and 6.26 g·cm−3 at the liquidus temperatures (T L), respectively. The corresponding temperature coefficients are 2.61 × 10−4, 2.75 × 10−4 and 2.84 × 10−4 g·cm−3·K−1, respectively. Notably, the experimental density results align well with the simulated results. Moreover, the molar volume (V m), thermal expansion coefficient (α) and diffusion coefficient (D) were derived based on the experimental data and simulations. The thermal expansion coefficients reduce linearly with decreasing temperature. The analysis of the pair distribution function, coordination number (CN) and the radial distribution function reveals the temperature-dependent evolution of the atomic structure. The CN total and CN Zr–Zr initially increase and then decrease with decreasing temperature, while the change trends for CN Zr–Nb and CN Nb–Nb varied among the three alloys. The radial distribution function of three liquid alloys reveals that the atomic number density increases as the temperature drops. Additionally, the total diffusion coefficients decrease with the reduction of temperature and the rise of Nb content from 1.0 wt.% Nb to 6.0 wt.% Nb.

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“…We will also consider K-Cs [12] and Na-K [13] binary alloys at 10, 50 and 90 at percent of K as a function of temperature, as well as Na0.139K0.435Cs0.426 alloy [14], known to have the lowest reported freezing point (195.2 K), from 200 K up to 1000 K. The alloys are considered under atmospheric pressure so that density is also changing with temperature.…”

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confidence: 99%

Stokes-Einstein Relation in Pure Alkali Metals and their Alloys

Wax

Harchaoui

2022

DDF

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Stokes-Einstein relation is a convenient way to evaluate diffusion properties in liquids from viscosity results (and vice-versa). However, the accuracy of this relation in the case of atomic fluids is often debated as it was initially established in the case of a big Brownian particle immersed in a fluid. Especially, the question is raised to properly define the hydrodynamic radius entering the formula, as well as the constant depending on the boundary conditions at the surface of the particle. In this study, we use our results of viscosity and self-diffusion coefficient obtained by molecular dynamics simulations in the case of alkali metals and their alloys to evaluate the applicability of Stokes-Einstein relation in the case of these liquids. In the case of pure metals, its validity is discussed over a wide range of thermodynamic states, from ambient pressure up to several gigapascals. In the case of alloys, the evolution of its accuracy as a function of temperature and composition is considered. Both definitions of hydrodynamic radius and boundary conditions constant are examined.

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Viscosity of liquid Na–K alloys from molecular dynamics simulations

Cited by 3 publications

References 15 publications

Numerical simulation study of a low freezing point metallic alloy: Na–K–Cs

Numerical simulation study of a low freezing point metallic alloy: Na–K–Cs

Thermophysical properties and atomic structure of liquid Zr–Nb alloys investigated by electrostatic levitation and molecular dynamics simulation

Stokes-Einstein Relation in Pure Alkali Metals and their Alloys

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