1
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Gegentana, Cui L, Zhou L, Du X. Diffusion Behaviors of CaCl 2-NaCl Molten Salt under an Electric Field: A Deep Potential Molecular Dynamics Simulation. J Phys Chem B 2024; 128:8484-8493. [PMID: 39190293 DOI: 10.1021/acs.jpcb.4c02413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
CaCl2-NaCl molten salt is one of the widely used electrolytes, and the effect of the electric field on it needs to be considered in the environment of manufacturing metals and alloys as well as in battery applications. To be closer to the state of the CaCl2-NaCl molten salt system in practical applications, this study uses the training-based deep potential, combined with the ionic structure, to analyze the electric field effects on the drift velocity, ionic mobility, ion diffusion, and viscosity of the CaCl2-NaCl system by molecular dynamics simulations. It is shown that the electric field has a stronger effect on the ion diffusion behavior parallel to the direction of the electric field in the CaCl2-NaCl molten salt system. Due to the looser coordinate structure of Na+, the interaction force between Na-Cl is small compared with that between Ca-Cl. Na+ is easily driven and more sensitive to the electric field, whose drift velocity, ionic mobility, and diffusion coefficient are larger than those of the other two ions, with an order of Na+ > Cl- > Ca2+. All ionic drift velocities increase linearly as electric field intensity increases and the ionic mobilities tend to be constant. The diffusion coefficient parallel to the direction of the electric field exponentially increases and the viscosity tends to exponentially decrease with the increase in the electric field intensity. This work is important for accurately predicting the properties and performance of molten salts and their improvement for applications such as solar thermal energy conversion.
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Affiliation(s)
- Gegentana
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
| | - Liu Cui
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
| | - Leping Zhou
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
| | - Xiaoze Du
- School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
- Key Laboratory of Power Station Energy Transfer Conversion and System (North China Electric Power University), Ministry of Education, Beijing 102206, China
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2
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Dong W, Tian H, Zhang W, Zhou JJ, Pang X. Development of NaCl-MgCl 2-CaCl 2 Ternary Salt for High-Temperature Thermal Energy Storage Using Machine Learning. ACS APPLIED MATERIALS & INTERFACES 2024; 16:530-539. [PMID: 38126774 DOI: 10.1021/acsami.3c13412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
NaCl-MgCl2-CaCl2 eutectic ternary chloride salts are potential heat transfer and storage materials for high-temperature thermal energy storage. In this study, first-principles molecular dynamics simulation results were used as a data set to develop an interatomic potential for ternary chloride salts using a neural network machine learning method. Deep potential molecular dynamics (DPMD) simulations were performed to predict the microstructure and thermophysical properties of the NaCl-MgCl2-CaCl2 ternary salt. This work reveals that DPMD simulations can accurately calculate the microstructure and thermophysical properties of ternary chloride salts. The association strength of chloride ions and cations follows the order of Mg2+ > Ca2+ > Na+, and the coordination number decreases gradually with increasing temperature, indicating a progressively looser and more disordered molten structure. Furthermore, thermophysical properties, such as density, specific heat capacity, thermal conductivity, and viscosity, are in good agreement with the experimental measurements. Machine learning molecular dynamics will provide a feasible multivariate molten salt exploration method for the design of next-generation solar power plants and thermal energy storage systems.
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Affiliation(s)
- Wenhao Dong
- School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Heqing Tian
- School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Wenguang Zhang
- School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Jun-Jie Zhou
- School of Mechanical and Power Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
| | - Xinchang Pang
- School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, P. R. China
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3
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Li B, Jones ZR, Eiroa-Lledo C, Knope KE, Mocko V, Stein BW, Wacker JN, Kozimor SA, Batista ER, Yang P. Structure and Dynamics of NaCl/KCl/CaCl 2-EuCl n ( n = 2, 3) Molten Salts. Inorg Chem 2023. [PMID: 37379331 DOI: 10.1021/acs.inorgchem.2c03982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Modern molten salt reactor design and the techniques of electrorefining spent nuclear fuels require a better understanding of the chemical and physical behavior of lanthanide/actinide ions with different oxidation states dissolved in various solvent salts. The molecular structures and dynamics that are driven by the short-range interactions between solute cations and anions and long-range solute and solvent cations are still unclear. In order to study the structural change of solute cations caused by different solvent salts, we performed first-principles molecular dynamics simulations in molten salts and extended X-ray absorption fine structure (EXAFS) measurements for the cooled molten salt samples to identify the local coordination environment of Eu2+ and Eu3+ ions in CaCl2, NaCl, and KCl. The simulations reveal that with the increasing polarizing the outer sphere cations from K+ to Na+ to Ca2+, the coordination number (CN) of Cl- in the first solvation shell increases from 5.6 (Eu2+) and 5.9 (Eu3+) in KCl to 6.9 (Eu2+) and 7.0 (Eu3+) in CaCl2. This coordination change is validated by the EXAFS measurements, in which the CN of Cl- around Eu increases from 5 in KCl to 7 in CaCl2. Our simulation shows that the fewer Cl- ions coordinated to Eu leads to a more rigid first coordination shell with longer lifetime. Furthermore, the diffusivities of Eu2+/Eu3+ are related to the rigidity of their first coordination shell of Cl-: the more rigid the first coordination shell is, the slower the solute cations diffuse.
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Affiliation(s)
- Bo Li
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Zachary R Jones
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Cecilia Eiroa-Lledo
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Karah E Knope
- Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Veronika Mocko
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Benjamin W Stein
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Jennifer N Wacker
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Stosh A Kozimor
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique R Batista
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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4
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Meng K, Li X, Niu Y, Zhang C, Yu X, Rong J, Hou H, Chen H. Computational simulation-driven discovery of novel zeolite-like carbon materials as seawater desalination membranes. Phys Chem Chem Phys 2023. [PMID: 37325848 DOI: 10.1039/d3cp00787a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Freshwater is a scarce and vulnerable resource that has never encountered such an extensive focus on a nearly worldwide scale as it does today. Recently, it has been found that desalination powered by two-dimensional (2D) carbon materials as separation membranes has significantly reduced the operational costs and complexity but presents heavy requirements for the structural stability and separation properties of the membrane materials. Here, we combined carbon materials with promising adsorption properties and zeolites characterized by a regular pore structure to obtain a zeolite-like structured carbon membrane Zeo-C and investigated the suitability of the Zeo-C membrane for seawater desalination based on the computational-simulation-driven approach. The results of molecular dynamics (MD) simulations and density functional theory (DFT) calculations revealed that the periodic pore distribution conferred favorable structural stability and mechanical strength to the Zeo-C desalination membrane. The rejection rate of Na+ and Cl- is ensured at 100% under a pressure of 40-70 MPa, and that of Na+ could reach 97.85% even though the pressure increases to 80 MPa, exhibiting superior desalination properties. The porous nature of the zeolite-like structure and the low free energy potential barrier are conducive for reliable adsorption and homogeneous diffusion of salt ions, which facilitates the acquisition of desirable water molecule permeability and salt ion selectivity. In particular, the interlinked delocalized π-network imparts inherent metallicity to Zeo-C for self-cleaning in response to electrical stimulation, thereby extending the lifetime of the desalination membrane. These studies have greatly encouraged theoretical innovations and serve as a guiding reference for desalination materials.
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Affiliation(s)
- Kun Meng
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Xiuhan Li
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Yutao Niu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Changhong Zhang
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Xiaohua Yu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Ju Rong
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Hongying Hou
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, 650093, China.
| | - Hui Chen
- State Key Laboratory of Special Surface Protection Materials and Application Technology, Wuhan Research Institute of Materials Protection, Wuhan, 430030, China.
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5
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Deng P, Li L, Jia Y, Jiang W, Liu D, Chen X, Kong L. First‐Principles Molecular Dynamics Study on Ionic Structure and Transport Properties of NaCl‐MgCl
2
‐CaCl
2
Ternary Molten Salt System. ADVANCED THEORY AND SIMULATIONS 2023. [DOI: 10.1002/adts.202200833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Pan Deng
- National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and Technology Kunming 650093 P. R. China
- Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
- State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province Kunming 650093 P. R. China
| | - Liang Li
- State Key Laboratory of Vanadium and Titanium Comprehensive Utilization Pangang Group Research Institute Co.Ltd Panzhihua 617000 P. R. China
| | - Yaoqiang Jia
- National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and Technology Kunming 650093 P. R. China
- Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
- State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province Kunming 650093 P. R. China
| | - Wenlong Jiang
- National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and Technology Kunming 650093 P. R. China
- Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
- State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province Kunming 650093 P. R. China
| | - Dachun Liu
- National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and Technology Kunming 650093 P. R. China
- Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
- State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province Kunming 650093 P. R. China
| | - Xiumin Chen
- National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and Technology Kunming 650093 P. R. China
- Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
- State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province Kunming 650093 P. R. China
| | - Lingxin Kong
- National Engineering Research Center of Vacuum Metallurgy Kunming University of Science and Technology Kunming 650093 P. R. China
- Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Kunming 650093 P. R. China
- State Key Laboratory of Complex Nonferrous Metal Resources Clear Utilization in Yunnan Province Kunming 650093 P. R. China
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6
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Evaluation of the local structure and electrochemical behavior in the LiCl-KCl-SmCl3 melt. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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7
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Li B, Dai S, Jiang DE. First-principles molecular dynamics simulations of UCl n-MgCl 2 ( n = 3, 4) molten salts. Phys Chem Chem Phys 2022; 24:24281-24289. [PMID: 36172828 DOI: 10.1039/d2cp02417a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molten chlorides are a preferred choice for fast-spectrum molten salt reactors. Molten MgCl2 forms eutectic mixtures with NaCl and is considered as a promising dilutant to dissolve fuel salts such as UCl3 and UCl4. However, the structure and chemical properties of UCln (n = 3, 4) in molten MgCl2 are not well understood. Here we use first-principles molecular dynamics to investigate the molten salt system UCln-MgCl2 (n = 3, 4) at various concentrations of U3+ and U4+. It is found that the coordination environment of Cl- around U3+, especially in the first coordination shell, varies only slightly with the uranium concentration and that both the 7-fold coordinate (UCl74-) and 6-fold coordinate (UCl63-) structures dominate at ∼40%, leading to an average coordination number of 6.6-6.7. A network or polymeric structure of U3+ cations sharing Cl- ions is extensively formed when the mole fraction of UCl3 is greater than 0.2. In contrast, the average coordination number of Cl- around U4+ is about 6.4 for a mole fraction of UCl4, x(UCl4), of 0.1 but decreases to 6.0 for x(UCl4) = 0.2 and then stays at about 6.0-6.2 with the uranium concentration. The 6-fold coordinate structure (UCl62-) is the most populous in UCl4-MgCl2, at about 60%. U-Cl network formation becomes dominant (>50%) only when x(UCl4) > 0.5. Unlike Na+, Mg2+ forms a network structure with Cl- ions and when x(UCl3) or x(UCl4) < 0.5, over 90% of Mg2+ ions are part of a network structure, implying the complex influences from Mg2+ on the coordination of Cl around U. The present work reveals the impact of MgCl2 as a solvent for UCln (n = 3, 4) on the U-Cl coordination and structure, and motivates further studies of their transport properties and the tertiary systems containing MgCl2-UCln.
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Affiliation(s)
- Bo Li
- Department of Chemistry, University of California, Riverside, California 92521, USA
| | - Sheng Dai
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - De-En Jiang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.
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8
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Structure-property relationships in actinide containing molten salts – A review: Understanding and modelling the chemistry of nuclear fuel salts. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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9
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10
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Liu M, Li X, Wang Y, Xu T, Yan L, Tang Z. Elaborating the high thermal storage and conductivity of molten NaCl-KCl-NaF eutectic from microstructures by FPMD simulations. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.117054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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Xu L, Huang Z, Jia M, Chen F. Microstructural and diffusive properties of Cr solute in MgCl2–NaCl–KCl eutectic: A First-Principles molecular dynamics study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117321] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Roy S, Liu Y, Topsakal M, Dias E, Gakhar R, Phillips WC, Wishart JF, Leshchev D, Halstenberg P, Dai S, Gill SK, Frenkel AI, Bryantsev VS. A Holistic Approach for Elucidating Local Structure, Dynamics, and Speciation in Molten Salts with High Structural Disorder. J Am Chem Soc 2021; 143:15298-15308. [PMID: 34499512 DOI: 10.1021/jacs.1c06742] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To examine ion solvation, exchange, and speciation for minority components in molten salts (MS) typically found as corrosion products, we propose a multimodal approach combining extended X-ray absorption fine structure (EXAFS) spectroscopy, optical spectroscopy, ab initio molecular dynamics (AIMD) simulations, and rate theory of ion exchange. Going beyond conventional EXAFS analysis, our method can accurately quantify populations of different coordination states of ions with highly disordered coordination environments via linear combination fitting of the EXAFS spectra of these coordination states computed from AIMD to the experimental EXAFS spectrum. In a case study of dilute Ni(II) dissolved in the ZnCl2+KCl melts, our method reveals heterogeneous distributions of coordination states of Ni(II) that are sensitive to variations in temperature and melt composition. These results are fully explained by the difference in the chloride exchange dynamics at varied temperatures and melt compositions. This insight will enable a better understanding and control of ion solubility and transport in MS.
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Affiliation(s)
- Santanu Roy
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Yang Liu
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, United States.,Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Mehmet Topsakal
- Nuclear Science and Technology Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Elaine Dias
- Nuclear Science and Technology Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Ruchi Gakhar
- Pyrochemistry and Molten Salt Systems Department, Idaho National Laboratory, Idaho Falls, Idaho 83415, United States
| | - William C Phillips
- Pyrochemistry and Molten Salt Systems Department, Idaho National Laboratory, Idaho Falls, Idaho 83415, United States
| | - James F Wishart
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Denis Leshchev
- National Synchrotron Light Source II (NSLS-II), Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Phillip Halstenberg
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37916, United States
| | - Sheng Dai
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37916, United States
| | - Simerjeet K Gill
- Nuclear Science and Technology Department, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Anatoly I Frenkel
- Department of Materials Science and Chemical Engineering, Stony Brook University, Stony Brook, New York 11794, United States.,Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
| | - Vyacheslav S Bryantsev
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
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13
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Zhang J, Fuller J, An Q. Coordination and Thermophysical Properties of Transition Metal Chlorocomplexes in LiCl-KCl Eutectic. J Phys Chem B 2021; 125:8876-8887. [PMID: 34328331 DOI: 10.1021/acs.jpcb.1c03748] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Eutectic LiCl-KCl molten salt is often used in molten salt reactors as the primary coolant due to its high thermal capacity and high solubility of fission products. Thermophysical properties, such as density, heat capacity, and viscosity, are important parameters for engineering applications of molten salts but may be significantly influenced by metal solutes from corrosion of metallic structural materials. The behavior of the LiCl-KCl eutectic composition is well researched, yet the effects on these properties due to chlorocomplex formation from metals dissolved in the salt are less well known. These properties are often difficult to accurately measure from experimental methods due to the issues arising from the dissolved species, such as volatility. Here, we applied a combination of quantum mechanics molecular dynamics (QM-MD) and deep machine learning force field (DP-FF) molecular dynamics simulations to investigate the structural and thermophysical properties of LiCl-KCl eutectic as well as the influence of dissolved transition metal chlorocomplexes NiCl2 and CrCl3 at low concentrations. We find that the dissolution of Ni and Cr in the LiCl-KCl system forms the local tetrahedral (NiCl4)2- and octahedral (CrCl6)3- chlorocomplexes, respectively, which do not have a significant impact on the overall liquid salt structures. In addition, the thermodynamic properties including diffusion constant and specific heat capacity are not significantly affected by these chlorocomplexes. However, the viscosity significantly increases in the temperature range of 673-773 K. This study thus provides essential information for evaluating the effects of dissolved metals on the thermophysical and transport properties of molten salts.
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Affiliation(s)
- Jing Zhang
- Department of Chemical and Materials Engineering, University of Nevada-Reno, Reno, Nevada 89557, United States
| | - Jon Fuller
- Department of Chemical and Materials Engineering, University of Nevada-Reno, Reno, Nevada 89557, United States
| | - Qi An
- Department of Chemical and Materials Engineering, University of Nevada-Reno, Reno, Nevada 89557, United States
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14
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Roy S, Brehm M, Sharma S, Wu F, Maltsev DS, Halstenberg P, Gallington LC, Mahurin SM, Dai S, Ivanov AS, Margulis CJ, Bryantsev VS. Unraveling Local Structure of Molten Salts via X-ray Scattering, Raman Spectroscopy, and Ab Initio Molecular Dynamics. J Phys Chem B 2021; 125:5971-5982. [PMID: 34037400 DOI: 10.1021/acs.jpcb.1c03786] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we resolve a long-standing issue concerning the local structure of molten MgCl2 by employing a multimodal approach, including X-ray scattering and Raman spectroscopy, along with the theoretical modeling of the experimental spectra based on ab initio molecular dynamics (AIMD) simulations utilizing several density functional theory (DFT) methods. We demonstrate the reliability of AIMD simulations in achieving excellent agreement between the experimental and simulated spectra for MgCl2 and 50 mol % MgCl2 + 50 mol % KCl, and ZnCl2, thus allowing structural insights not directly available from experiment alone. A thorough computational analysis using five DFT methods provides a convergent view that octahedrally coordinated magnesium in pure MgCl2 upon melting preferentially coordinates with five chloride anions to form distorted square pyramidal polyhedra that are connected via corners and to a lesser degree via edges. This is contrasted with the results for ZnCl2, which does not change its tetrahedral coordination on melting. Although the five-coordinate MgCl53- complex was not considered in the early literature, together with an increasing tendency to form a tetrahedrally coordinated complex with decreasing the MgCl2 content in the mixture with alkali metal chloride systems, current work reconciles the results of most previous seemingly contradictory experimental studies.
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Affiliation(s)
- Santanu Roy
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Martin Brehm
- Institut für Chemie, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 4, 06120 Halle (Saale), Germany
| | - Shobha Sharma
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Fei Wu
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Dmitry S Maltsev
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Phillip Halstenberg
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Leighanne C Gallington
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Shannon M Mahurin
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Sheng Dai
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.,Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Alexander S Ivanov
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Claudio J Margulis
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
| | - Vyacheslav S Bryantsev
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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15
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Liang W, Lu G, Yu J. Machine-Learning-Driven Simulations on Microstructure and Thermophysical Properties of MgCl 2-KCl Eutectic. ACS APPLIED MATERIALS & INTERFACES 2021; 13:4034-4042. [PMID: 33430593 DOI: 10.1021/acsami.0c20665] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Theoretical studies on the MgCl2-KCl eutectic heavily rely on ab initio calculations based on density functional theory (DFT). However, neither large-scale nor long-time calculations are feasible in the framework of the ab initio method, which makes it challenging to accurately predict some properties. To address this issue, a scheme based on ab initio calculation, deep neural networks, and machine learning is introduced. By training on high-quality data sets generated by ab initio calculations, a deep potential (DP) is constructed to describe the interaction between atoms. This work shows that the DP enables higher efficiency and similar accuracy relative to DFT. By performing molecular dynamics simulations with DP, the microstructure and thermophysical properties of the MgCl2-KCl eutectic (32:68 mol %) are investigated. The structural evolution with temperature is analyzed through partial radial distribution functions, coordination numbers, angular distribution functions, and structural factors. Meanwhile, the estimated thermophysical properties are discussed, including density, thermal expansion coefficient, shear viscosity, self-diffusion coefficient, and specific heat capacity. It reveals that the Mg2+ ions in this system have a distorted tetrahedral geometry rather than an octahedral one (with vacancies). The microstructure of the MgCl2-KCl eutectic shows the feature of medium-range order, and this feature will be enhanced at a higher temperature. All predicted thermophysical properties are in good agreement with the experimental results. The hydrodynamic radius determined from the shear viscosity and self-diffusion coefficient shows that the Mg2+ ions have a strong local structure and diffuse as if with an intact coordination shell. Overall, this work provides a thorough understanding of the microstructure and enriches the data of the thermophysical properties of the MgCl2-KCl eutectic.
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Affiliation(s)
- Wenshuo Liang
- School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
- 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 Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
- 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 Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
- 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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Liang W, Lu G, Yu J. Molecular Dynamics Simulations of Molten Magnesium Chloride Using Machine‐Learning‐Based Deep Potential. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000180] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Wenshuo Liang
- School of Resources and Environmental Engineering East China University of Science and Technology Shanghai 200237 China
- 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 Resources and Environmental Engineering East China University of Science and Technology Shanghai 200237 China
- 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 Resources and Environmental Engineering East China University of Science and Technology Shanghai 200237 China
- 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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Li X, Liu W, Tang Z, Xu T, Wang J. Insight into dynamic interaction of molten MgCl2-NaCl-KCl with impurity water via FPMD simulations. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113596] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Liang W, Lu G, Yu J. Composition-dependent microstructure evolution in liquid MgCl2-KCl: A first-principles molecular dynamics study. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113131] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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