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

Abstract

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.