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Bruno, M.; Herstad, O.; Holm, Jesper

doi:10.1023/a:1010175006354

Cited by 12 publications

(3 citation statements)

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“…For β-Na 3 AlF 6 and other systems, our approach is thus purely predictive. It is known that cryolite (Na 3 AlF 6 ) is found as two polymorphs: a low-temperature phase, the so-called α-cryolite, which crystallizes in a monoclinic structure ( P 21/ n ), and the β-cryolite (Elpasolite Fm 3̅ m ) which is stable at high temperatures, more specifically above 836 K. − While α-cryolite is a stoichiometric compound, β-cryolite is more complex. The NaF–AlF 3 phase diagram is shown in Figure , according to the critical assessment by Chartrand and Pelton, using the CALPHAD method .…”

Section: Resultsmentioning

confidence: 99%

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na₃AlF₆, Na₅Al₃F₁₄, and Molten Na₃AlF₆ Supported by Equilibrium Molecular Dynamics and Density Functional Theory

2016

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Numerical modeling of heat transport in the side ledge of a cryolite bath as a function of its thickness requires an accurate knowledge of the thermal transport properties of the cryolite bath as well as the solid phases constituting the side ledge. Unfortunately, due to experimental limitations, there is a lack of experimental data on this subject. The aim of this work is to predict these otherwise unknown properties. The thermal conductivity of major constituents of the side ledge in their solid state, namely: NaF, β– Na3AlF6 and Na5Al3F14 as well as molten Na3AlF6 are formulated as a function of temperature. To achieve this, we have performed a series of equilibrium molecular dynamics simulations (EMD) in both the NPT (isobar-isotherm) and NVT (canonical) statistical ensembles. The proposed approach is purely predictive as the ionic interaction potentials were parametrized on the basis of Density Functional Theory (DFT). The results are then compared to a theoretical model which has been shown to be a very good predictive ability for many ionic and ionocovalent compounds. For solid NaF and liquid Na3AlF6, for which data are available, the predictions were found to be in excellent agreement with experiment.

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Section: Resultsmentioning

confidence: 99%

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na₃AlF₆, Na₅Al₃F₁₄, and Molten Na₃AlF₆ Supported by Equilibrium Molecular Dynamics and Density Functional Theory

2016

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“…-the potassium deposition occurs at a potential by 0.4-0.6 V negatively than the sodium deposition potential; 17 -potassium does not form alloys with aluminium; -the potassium boiling point is 759°С; 16 -a change in the electrolyte composition in the cathode layer is more crucial (the formation of the solid salt on the cathode surface) in the KF-AlF 3 melt than in the NaF-AlF 3 . 18,19 It follows from the above mentioned that the primary task for the implementation of electrolysis in the KF-AlF 3 -Al 2 O 3 -based melt is the cathode process, that is the determination of overvoltage and the limited current density of the aluminum deposition. This will prevent the potassium deposition and the formation of solid at the cathode surface, which will ensure the electrolysis stability without destroying the carbon pot and the cathode passivation.…”

mentioning

confidence: 99%

Cathode Process in the KF-AlF₃-Al₂O₃ Melts

Nikolaev

Suzdaltsev

Zaikov

2019

J. Electrochem. Soc.

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Kinetics of the cathode process in the KF-AlF 3 and KF-AlF 3 -Al 2 O 3 melts has been studied by means of the steady-state polarization and voltammetry techniques. The kinetic parameters of the aluminum electrodeposition in dependence on such factors as cathode material, process temperature, alumina concentration in the melt, etc. were determined. Based on the experiment data analysis, a mechanism of the cathode process in the KF-AlF 3 -Al 2 O 3 melts was proposed. The operating parameters were defined and electrolysis was carried out.

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“…is discussed in a long series of papers about the NaF-AlF3 system since 1954 (Howard, 1954). The whole story is summarized in two relatively recent articles (Bruno et al , 1998, 1999) and in the references therein. Owing to the importance of this system in the industrial production of aluminum, NaAlF 4 is also cited in a huge number of patents.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of NaAlF₄, a new aristotype

Bail

2009

Powder Diffr.

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A model for the long awaited crystal structure of metastable NaAlF4 is established from the powder diffraction pattern of a partly disproportionated sample. Orthorhombic, Cmcm, a=3.6121(3), b=14.952(1), c=5.2692(4) Å, Z=4, V=284.58(4) Å3. Sodium atoms are in NaF6 trigonal prisms interconnected by edges in compact layers. AlF6 octahedra are both cis- and trans-corner connected forming a layer structure similar to that observed in the NaNbO2F2 (P21/c) and BaZnF4 (Cmc21) structure types. NaAlF4 is ideally simple and symmetrical, isostructural with BiReO4 (Cmcm), representing the aristotype of the NaMIIIF4 and BaMIIF4 series.

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Cited by 12 publications

References 2 publications

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na₃AlF₆, Na₅Al₃F₁₄, and Molten Na₃AlF₆ Supported by Equilibrium Molecular Dynamics and Density Functional Theory

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na₃AlF₆, Na₅Al₃F₁₄, and Molten Na₃AlF₆ Supported by Equilibrium Molecular Dynamics and Density Functional Theory

Cathode Process in the KF-AlF₃-Al₂O₃ Melts

Crystal structure of NaAlF₄, a new aristotype

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Untitled

Cited by 12 publications

References 2 publications

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na3AlF6, Na5Al3F14, and Molten Na3AlF6 Supported by Equilibrium Molecular Dynamics and Density Functional Theory

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na3AlF6, Na5Al3F14, and Molten Na3AlF6 Supported by Equilibrium Molecular Dynamics and Density Functional Theory

Cathode Process in the KF-AlF3-Al2O3 Melts

Crystal structure of NaAlF4, a new aristotype

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Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na₃AlF₆, Na₅Al₃F₁₄, and Molten Na₃AlF₆ Supported by Equilibrium Molecular Dynamics and Density Functional Theory

Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na₃AlF₆, Na₅Al₃F₁₄, and Molten Na₃AlF₆ Supported by Equilibrium Molecular Dynamics and Density Functional Theory

Cathode Process in the KF-AlF₃-Al₂O₃ Melts

Crystal structure of NaAlF₄, a new aristotype