Deciphering Neodymium Concentration-Dependent Structure-Thermodynamics Interplay in Molten LiF-NdF3 Salts: A Multiscale Mechanistic Exploration

J Phys Chem A. 2025 Aug 22. doi: 10.1021/acs.jpca.5c03292. Online ahead of print.

ABSTRACT

First-principles molecular dynamics simulations combined with differential scanning calorimetry experiments are employed to systematically elucidate how NdF₃ concentration modulates the structural and thermodynamic properties of molten LiF-NdF₃ (FLiNd) complexes─an important salt system unit for Generation IV nuclear reactor applications. Multiscale analysis unveils the concentration-dependent evolution of ionic pair or cluster architectures, electronic structures, phonon vibration modes, and thermophysical properties at operational temperatures, with particular emphasis on the ionic conduction mechanism of molten FLiNd. Preliminary observations suggest that the melting enthalpy depression may correlate with weakened cation-F interactions as NdF₃ concentration increases, percolation-limited transport appears to be predominantly influenced by NdF_n^3-n (n = 7 or 8) polyhedra, possibly due to enhanced electronic polarization effects, and emergent Nd-Nd-Nd networks could potentially contribute to phonon mode softening and a reduction in ionic conductivity. Overall, a predictive structure-property framework where electronic structure reorganization and lattice anharmonicity collectively govern the coordination structure and macroscopic transport is tentatively established, which provides quantitative guidance for optimizing fuel salt compositions and performance in molten salt reactors.

PMID:40847314 | DOI:10.1021/acs.jpca.5c03292