Transport properties of dissolved [O] in the (LiF–CaF₂)_eut.–NdOF molten salt system

The transport properties of [O] in dissolved rare-earth oxyfluorides provide an important theoretical basis for optimizing anode reactions during molten salt electrolysis in fluoride systems for rare-earth metal production. In this study, the solubility of NdOF in (LiF-CaF₂)_eut. was investigated, and the electrical conductivity and density of the saturated NdOF system were measured. The self-diffusion coefficients and radial distribution functions of the ions in the system were analyzed using first-principles molecular dynamics. The transport number of dissolved O*(ii) ions in the saturated (LiF-CaF₂)_eut.-NdOF system was determined using the coulometric method, providing a comprehensive analysis of the variation in the migration rate and diffusion coefficients of dissolved O*(ii) ions. The results showed that the solubility of NdOF in the (LiF-CaF₂)_eut. System, along with the electrical conductivity and density of the saturated system, exhibited linear variations in the temperature range of 1123-1373 K. The transport number, migration rate, and diffusion coefficient of dissolved O*(ii) ions underwent non-linear changes with increasing potential within the range of 3.0-4.5 V, reaching a maximum in the range of 3.75-4.25 V, while still increasing linearly with temperature. When the [temperature-potential] was in the [1200 K↑-3.5 V↑] range, the migration rate and diffusion coefficient of O*(ii) ions were the highest, with the potential playing a dominant role in the diffusion coefficient of O*(ii) ions. The radial distribution function values of the ions in the system indicated that Nd*(iii) ions had the strongest restraining effect on the dissolved O*(ii) ions during the diffusion process.