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Structure and Bonding in Cryolitic Melts A Combined Study by Density Functional Theory and Ionic Model Calculations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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2
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Zhang Y, Hu X, Lin M, Liu A, Shi Z, Wang Z. Quantum Chemical Calculation on the Decomposition Mechanism of Na3AlF6. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2022. [DOI: 10.1134/s0036024422050302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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3
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Ab initio molecular dynamics study on microstructure and diffusion properties of CaF2-2.2NaF-AlF3 system. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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4
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Shear viscosities and thermal conductivity of NaF-AlF3 molten salts: A non-equilibrium molecular dynamics study. J Fluor Chem 2021. [DOI: 10.1016/j.jfluchem.2020.109675] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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5
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Quantum chemical prediction of the spectroscopic properties and ionic composition of the molten NaF-AlF3 salts. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113937] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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6
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Parker SF, Ramirez-Cuesta AJ, Daemen LL. The structure and vibrational spectroscopy of cryolite, Na 3AlF 6. RSC Adv 2020; 10:25856-25863. [PMID: 35518579 PMCID: PMC9055329 DOI: 10.1039/d0ra04804f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/01/2020] [Indexed: 11/21/2022] Open
Abstract
Cryolite, Na3[AlF6], is essential to commercial aluminium production because alumina is readily soluble in molten cryolite. While the liquid state has been extensively investigated, the spectroscopy of the solid state has been largely ignored. In this paper, we show that the structure at 5 K is the same as that at room temperature. We use a combination of infrared and Raman spectroscopies together with inelastic neutron scattering (INS) spectroscopy. The use of INS enables access to all of the modes of Na3[AlF6], including those that are forbidden to the optical spectroscopies. Our spectral assignments are supported by density functional theory calculations of the complete unit cell. We use a combination of infrared, Raman and inelastic neutron scattering spectroscopies to access all of the modes of cryolite, Na3[AlF6], including those that are forbidden to the optical spectroscopies.![]()
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Affiliation(s)
- Stewart F Parker
- ISIS Facility, STFC Rutherford Appleton Laboratory Chilton, Didcot Oxon OX11 0QX UK
| | - Anibal J Ramirez-Cuesta
- Spallation Neutron Source, Neutron Spectroscopy Division, Oak Ridge National Laboratory Oak Ridge TN 37831-6475 USA
| | - Luke L Daemen
- Spallation Neutron Source, Neutron Spectroscopy Division, Oak Ridge National Laboratory Oak Ridge TN 37831-6475 USA
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7
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Guo H, Li J, Zhang H, Li T, Luo J, Yu X, Wu S, Zong C. First-principles molecular dynamics investigation on KF-NaF-AlF3 molten salt system. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.06.060] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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8
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Li J, Guo H, Zhang H, Li T, Gong Y. First-principles molecular dynamics simulation of the ionic structure and electronic properties of Na3AlF6 molten salt. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.01.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Lv X, Han Z, Zhang H, Liu Q, Chen J, Jiang L. Ionic structure and transport properties of KF–NaF–AlF3 fused salt: a molecular dynamics study. Phys Chem Chem Phys 2019; 21:7474-7482. [DOI: 10.1039/c9cp00377k] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Studying the ionic structure and transport properties of the KF–NaF–AlF3 fused salt at the atomic level.
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Affiliation(s)
- Xiaojun Lv
- School of Metallurgy and Environment, Central South University
- Changsha
- China
| | - Zexun Han
- School of Metallurgy and Environment, Central South University
- Changsha
- China
| | - Hengxing Zhang
- School of Metallurgy and Environment, Central South University
- Changsha
- China
| | - Qingsheng Liu
- Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology
- Ganzhou 341000
- China
| | - Jiangan Chen
- Faculty of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology
- Ganzhou 341000
- China
| | - Liangxing Jiang
- School of Metallurgy and Environment, Central South University
- Changsha
- China
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10
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Temperature Dependent Micro-Structure of KAlF₄ from Solid to Molten States. MATERIALS 2018; 11:ma11101846. [PMID: 30262756 PMCID: PMC6213106 DOI: 10.3390/ma11101846] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 09/23/2018] [Accepted: 09/25/2018] [Indexed: 11/16/2022]
Abstract
In situ high temperature X-ray diffraction and Raman spectroscopy were used to investigate the temperature dependent micro-structure of KAlF₄. Density functional theory was applied to simulate the structure of crystalline KAlF₄ while a quantum chemistry ab initio simulation was performed to explore the structure of molten KAlF₄. Two crystal polymorphs demonstrated to be present in solid KAlF₄. At the temperature below 673 K, it belongs to the tetragonal crystal system within the P4/mbm space group, while the high temperature phase is attributed to the monoclinic crystal system within the P2₁/m space group. Both polymorph KAlF₄ phases are characterized by a layered structure consisting of K⁺ and [AlF₆]3- octahedra, each of the [AlF₆]3- octahedra equivalently shares four corners with other four [AlF₆]3- octahedra along the layer. The layered structure became unstable at higher temperatures and crashed when the temperature exceeded the melting point. It demonstrated that the molten KAlF₄ consisted of predominant [AlF₄]- and a small amount of [AlF₆]3-. The Raman spectrum of molten KAlF₄ simulated by using a quantum chemistry ab initio method agreed well with the experimental Raman spectrum.
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11
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Lv X, Han Z, Chen J, Jiang L, Xu Z, Liu Q. First-principles molecular dynamics study of ionic structure and transport properties of LiF-NaF-AlF3 molten salt. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.06.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Gheribi AE, Machado K, Zanghi D, Bessada C, Salanne M, Chartrand P. On the determination of ion transport numbers in molten salts using molecular dynamics. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.04.094] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Bučko T, Šimko F. Effect of alkaline metal cations on the ionic structure of cryolite melts: Ab-initio NpT MD study. J Chem Phys 2018; 148:064501. [DOI: 10.1063/1.5017106] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Tomáš Bučko
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, SK-84215 Bratislava, Slovakia
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, SK-84236 Bratislava, Slovakia
| | - František Šimko
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravska cesta 9, SK-84236 Bratislava, Slovakia
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14
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Lv X, Xu Z, Li J, Chen J, Liu Q. Molecular dynamics investigation on structural and transport properties of Na3AlF6–Al2O3 molten salt. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.05.064] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Adams DJ, Passerone D. Insight into structural phase transitions from the decoupled anharmonic mode approximation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:305401. [PMID: 27269514 DOI: 10.1088/0953-8984/28/30/305401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We develop a formalism (decoupled anharmonic mode approximation, DAMA) that allows calculation of the vibrational free energy using density functional theory even for materials which exhibit negative curvature of the potential energy surface with respect to atomic displacements. We investigate vibrational modes beyond the harmonic approximation and approximate the potential energy surface with the superposition of the accurate potential along each normal mode. We show that the free energy can stabilize crystal structures at finite temperatures which appear dynamically unstable at T = 0. The DAMA formalism is computationally fast because it avoids statistical sampling through molecular dynamics calculations, and is in principle completely ab initio. It is free of statistical uncertainties and independent of model parameters, but can give insight into the mechanism of a structural phase transition. We apply the formalism to the perovskite cryolite, and investigate the temperature-driven phase transition from the P21/n to the Immm space group. We calculate a phase transition temperature between 710 and 950 K, in fair agreement with the experimental value of 885 K. This can be related to the underestimation of the interaction of the vibrational states. We also calculate the main axes of the thermal ellipsoid and can explain the experimentally observed increase of its volume for the fluorine by 200-300% throughout the phase transition. Our calculations suggest the appearance of tunneling states in the high temperature phase. The convergence of the vibrational DOS and of the critical temperature with respect of reciprocal space sampling is investigated using the polarizable-ion model.
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Affiliation(s)
- Donat J Adams
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
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16
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Lv X, Xu Z, Li J, Chen J, Liu Q. Theoretical investigation on local structure and transport properties of NaFAlF3 molten salts under electric field environment. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2016.03.076] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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17
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Lv X, Xu Z, Li J, Chen J, Liu Q. First-principles molecular dynamics investigation on Na3AlF6 molten salt. J Fluor Chem 2016. [DOI: 10.1016/j.jfluchem.2016.03.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Liu M, Jacob A, Schmetterer C, Masset PJ, Hennet L, Fischer HE, Kozaily J, Jahn S, Gray-Weale A. From atomic structure to excess entropy: a neutron diffraction and density functional theory study of CaO-Al₂O₃-SiO₂ melts. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:135102. [PMID: 26940854 DOI: 10.1088/0953-8984/28/13/135102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Calcium aluminosilicate CaO-Al2O3-SiO2 (CAS) melts with compositions (CaO-SiO2)(x)(Al2O3)(1-x) for x < 0.5 and (Al2O3)(x)(SiO2)(1-x) for x ≥ 0.5 are studied using neutron diffraction with aerodynamic levitation and density functional theory molecular dynamics modelling. Simulated structure factors are found to be in good agreement with experimental structure factors. Local atomic structures from simulations reveal the role of calcium cations as a network modifier, and aluminium cations as a non-tetrahedral network former. Distributions of tetrahedral order show that an increasing concentration of the network former Al increases entropy, while an increasing concentration of the network modifier Ca decreases entropy. This trend is opposite to the conventional understanding that increasing amounts of network former should increase order in the network liquid, and so decrease entropy. The two-body correlation entropy S2 is found to not correlate with the excess entropy values obtained from thermochemical databases, while entropies including higher-order correlations such as tetrahedral order, O-M-O or M-O-M bond angles and Q(N) environments show a clear linear correlation between computed entropy and database excess entropy. The possible relationship between atomic structures and excess entropy is discussed.
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Affiliation(s)
- Maoyuan Liu
- School of Chemistry, University of Melbourne, Victoria 3010, Australia
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19
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Bučko T, Šimko F. On the structure of crystalline and molten cryolite: Insights from the ab initio molecular dynamics in NpT ensemble. J Chem Phys 2016; 144:064502. [DOI: 10.1063/1.4941333] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Tomáš Bučko
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, SK-84215 Bratislava, Slovakia
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská Cesta 9, SK-84236 Bratislava, Slovakia
| | - František Šimko
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská Cesta 9, SK-84236 Bratislava, Slovakia
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20
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Demmel F, Mukhopadhyay S. Quasielastic neutron scattering measurements and ab initio MD-simulations on single ion motions in molten NaF. J Chem Phys 2016; 144:014503. [DOI: 10.1063/1.4939072] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Affiliation(s)
- F. Demmel
- ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - S. Mukhopadhyay
- ISIS Facility, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
- Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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21
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Corradini D, Madden PA, Salanne M. Coordination numbers and physical properties in molten salts and their mixtures. Faraday Discuss 2016; 190:471-86. [DOI: 10.1039/c5fd00223k] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Mixtures of trivalent metal halides with alkali halides are involved in many technologies but, from a more fundamental and general perspective, are worthy of study as interesting systems in which to examine the relationship between atomic-scale structure and physical properties. Here we examine the relationship between the viscosity and local and longer range structural measures in such mixtures where the trivalent metal cations span a significant size range and exhibit different behaviours in the dependence of their viscosity on the mixture composition. We characterise the structure and dynamics of the first coordination shell and the relationship between its structural relaxation time and the shear relaxation time of the mixture (the Maxwell relaxation time). We are then led to an examination of the structure of the networks which progressively form between the trivalent metal cations as their concentration increases in the mixtures. Here we find significant differences between small and larger cations, sufficient to explain the different behaviour of their viscosities. We draw attention to the similarities and differences of these networks with those which form in highly viscous, glass-forming materials like BeF2:LiF.
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Affiliation(s)
| | - Paul A. Madden
- Department of Materials
- University of Oxford
- Oxford OX1 3PH
- UK
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22
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Rakhmatullin A, Keppert M, Šimko F, Bessada C. Aluminium phosphate behaviour in Na3AlF6–Al2O3 melts: a new insight from in situ high temperature NMR measurements. NEW J CHEM 2016. [DOI: 10.1039/c5nj02416a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The formation of complex oxofluoroaluminate species containing bridging oxygen atoms from the chemical processes between AlPO4, Al2O3, and Na3AlF6.
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Affiliation(s)
| | - Martin Keppert
- Department of Materials Engineering and Chemistry
- Faculty of Civil Engineering
- Czech Technical University in Prague
- 166 29 Prague 6
- Czech Republic
| | - František Šimko
- Institute of Inorganic Chemistry
- Slovak Academy of Sciences
- 845 36 Bratislava
- Slovakia
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23
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Abstract
Molten salts have been known for centuries and have been used for the extraction of aluminium for over one hundred years and as high temperature fluxes in metal processing. This and other molten salt routes have gradually become more energy efficient and less polluting, but there have been few major breakthroughs. This paper will explore some recent innovations that could lead to substantial reductions in the energy consumed in metal production and in carbon dioxide production. Another way that molten salts can contribute to an energy efficient world is by creating better high temperature fuel cells and novel high temperature batteries, or by acting as the medium that can create novel materials that can find applications in high energy batteries and other energy saving devices, such as capacitors. Carbonate melts can be used to absorb carbon dioxide, which can be converted into C, CO and carbon nanoparticles. Molten salts can also be used to create black silicon that can absorb more sunlight over a wider range of wavelengths. Overall, there are many opportunities to explore for molten salts to play in an efficient, low carbon world.
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Affiliation(s)
- Derek Fray
- Department of Materials Science and Metallurgy
- University of Cambridge
- Cambridge CB3 0FS
- UK
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24
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Wang J, Sun Z, Lu G, Yu J. Molecular Dynamics Simulations of the Local Structures and Transport Coefficients of Molten Alkali Chlorides. J Phys Chem B 2014; 118:10196-206. [DOI: 10.1021/jp5050332] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jia Wang
- School of Mechanical and Power Engineering and ‡National Engineering Research Center
for Integrated Utilization of Salt Lake Resource, East China University of Science and Technology, Shanghai 200237, China
| | - Ze Sun
- School of Mechanical and Power Engineering and ‡National Engineering Research Center
for Integrated Utilization of Salt Lake Resource, East China University of Science and Technology, Shanghai 200237, China
| | - Guimin Lu
- School of Mechanical and Power Engineering and ‡National Engineering Research Center
for Integrated Utilization of Salt Lake Resource, East China University of Science and Technology, Shanghai 200237, China
| | - Jianguo Yu
- School of Mechanical and Power Engineering and ‡National Engineering Research Center
for Integrated Utilization of Salt Lake Resource, East China University of Science and Technology, Shanghai 200237, China
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