The dissolution mechanism of YbOF in a fluoride-containing (LiF-CaF2)eut. molten salt is the basis for analyzing the structure of the resulting medium and optimizing the electrolytic preparation of rare-earth Yb alloys. In this study, isothermal saturation was used to analyze solubility changes of YbOF in the (LiF-CaF2)eut. system. Quantum chemical and molecular dynamics ab initio methods were used to study the basic properties of the components of the (LiF-CaF2)eut.-YbOF system and the microscopic structural changes during the dissolution process. In addition, structural changes in the YbOF-saturated (LiF-CaF2)eut. system were analyzed by combining cryogenic-temperature Raman spectroscopy with experimental methods. The results show the solubility of YbOF increased linearly in the temperature range of 1073-1323 K. As the melting temperature exceeded 1073 K, LiF and CaF2 gradually dissociated into Li+, Ca2+, and F-. In the initial stages of YbOF dissolution (1073-1173 K), the Yb-F bond was less stable than the Yb-O bond; YbOF dissociated into YbO+ and F- in this temperature range. When the temperature was increased above 1173 K, YbO+ further dissociated into Yb3+ and O2-. Overall, the dissolution of YbOF did not affect the main structure of the (LiF-CaF2)eut. system.
Keywords: ab initio molecular dynamics; fluorine oxides; high-temperature Raman spectroscopy; molten salt systems; solubility.