Abstract
Ion dynamics that drive the transport and thermophysical properties of molten salts are poorly understood due to challenges in precisely quantifying the spatial and temporal fluctuations of specific ions in highly disordered systems. While the Van Hove correlation function (VHF) obtained from inelastic neutron scattering (INS) probes these dynamics directly, its interpretation is limited by the inherent species-averaging of experiments, which obscures analysis of key ion transport and solvation mechanisms. Here, ab initio molecular dynamics (AIMD) is used to model the VHF, unravel its partial contributions, and elucidate its underlying ionic transport mechanisms. Slow decorrelation is revealed for oppositely charged ions (Mg2+ and Cl−) caused by ion exchange across the solvation shell between adjoining ionocovalent complexes. Furthermore, transport coefficients are accurately recovered, and connections between macroscopic properties and ion dynamics are revealed. This study demonstrates the potential of ab initio-informed VHF to resolve long-standing challenges in uncovering relationships between picosecond-scale ion dynamics, mechanisms, and emergent physical properties of molten salts.
Original language | English |
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Article number | 125821 |
Journal | Journal of Molecular Liquids |
Volume | 412 |
DOIs | |
State | Published - Oct 15 2024 |
Funding
We acknowledge the Department of Energy, Office of Nuclear Energy, Nuclear Energy University Program award no. DE-NE0009204 at the University of Massachusetts Lowell for financial support of this research. Work by Y.S. was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences, and Engineering Division. Work by A.S.I. was supported as a part of the Molten Salts in Extreme Environments (MSEE) Energy Frontier Research Center, funded by the DOE Office of Science, Basic Energy Sciences. VASP can be acquired from the VASP Software GmbH (see www.vasp.at/). For Calculating VHF, we have used scattering, which can be found at: (https://github.com/mattwthompson/scattering).
Keywords
- Cage correlation function
- Diffusion coefficient
- Inelastic neutron scattering
- Liquid dynamics
- MgCl
- Molten salt
- PMF
- Van Hove correlation function