Distribution of Nb and Ce between Two Immiscible Melts in the System CePO4–SiO2–NaF–Fe2O3–Nb2O5

Abstract

The system CePO₄–SiO₂–NaF–Fe₂O₃–Nb₂O₅ is characterized by a wide region of two immiscible melts. This region widened with increasing temperature in the system. The mutual solubility of the immiscible melts was low (3–5 wt %). The decrease in the melting points of the components was caused by chemical reactions between SiO₂ and NaF and between CePO₄ and NaF. New, previously unknown, phases were found in the system: a cerium sodium binary salt, cerium sodium fluorophosphate, and a niobium-rich phase. Niobium oxide was contained in the silicate melt, in silicate spheres occurring in the phosphate–fluoride melt, and in the niobium-rich phase. Cerium was concentrated in the phosphate–salt melt (as the cerium sodium binary salt) and in cerium sodium fluorophosphate.