Solubility of Rare Earth Oxides in Fused Alkali and Alkaline Earth Halides

Solubility of rare earth oxides in mixtures of alkali or alkaline earth halides was determined by the method of isothermal saturation at the temperatures up to 1400 o C. The melts studied included CaCl 2 –CaF 2 (20 or 75 mol. % CaF 2 ), BaCl 2 –BaF 2 (15 or 73 mol. % BaF 2 ), equimolar CaF 2 –BaF 2 and eutectic NaCl–NaF mixtures. Melting points of the salt mixtures were determined by differential thermal analysis and effect of added rare earth oxide on the melting point was considered. Solubility of yttrium, lanthanum, cerium, praseodymium, neodymium, and samarium oxides was determined. The effect of temperature, melt composition, and presence of a mixture of rare earth oxides on solubility was assessed.