Oxide solubility and Raman spectra of NdF3–LiF–KF–MgF2–Nd2O3 melts

The solubility of Nd2O3 in NdF3–LiF–MgF2 melts is about 0.08–0.38 mol% when the NdF3 concentration varies from 15 to 30 mol% at 900 °C. The solubility increases from 0.13 mol% at 750 °C to 0.22 mol% at 900 °C in the NdF3–LiF eutectic. When MgF2 is added to NdF3–LiF binary melts saturated with Nd2O3, the Nd2O3 solubility seems to decrease slightly at 30 mol% NdF3, while a slight increase was observed with 15 mol% NdF3 in the binary. When dissolving Nd2O3 in the NdF3–LiF eutectic Raman spectroscopy showed that the complex ions NdOF(x − 1)−x and Nd2OF(x − 1)−x + 3 may form in the melt. The most reasonable candidates seem to be: NdOF43− and NdOF54− among the mononuclear compounds and Nd2OF106−, Nd2OF84− among the binuclear complexes.