Interaction of rare-earth oxides with binary molten mixtures of zirconium and alkali metal fluorides

Isothermal saturation, inductively coupled plasma mass spectrometry (ICP-MS), and X-ray powder diffraction were used to study solubilities of La₂O₃, Sm₂O₃, and Ho₂O₃ in the eutectic mixtures of LiF-ZrF₄, NaF-ZrF₄, and KF-ZrF₄ systems at temperatures from 873 to 1073 K. The solubilities of rare earth oxides in the molten fluorozirconate systems studied decrease in the increasing order of Ln³⁺ ion radii and in the increasing order of alkali metal cation radii in the binary mixture. The thermodynamic parameters of dissolution calculated for the oxides imply the dominance of a chemical dissolution mechanism, and this implication was supported by X-ray powder diffraction data.