The distribution of Nb and Ce betweet two immiscible melts in the system CePO4–SiO2–NaF–Fe2O3–Nb2O5

Abstract

The CePO4 – SiO2 – NaF – Fe2O3–Nb2O5 system is characterized by a wide area of two immiscible melts. As the temperature in the system increases, the region of incompressibility of melts increases. Mutual solubility of immiscible melts is low and is 3–5% by weight. The decrease in the melting point of the components is due to chemical reactions between SiO2 and NaF and between cerium orthophosphate and sodium fluoride. New previously unknown phases were established in the system: double salt of cerium and sodium, fluoride phosphate of cerium and sodium and phase with high content of niobium. Niobium oxide is distributed between the silicate melt, silicate balls, which is part of the phosphate fluoride melt and a phase with a high content of niobium. Cerium is concentrated in the phosphate-salt melt, where it is found in the double salt of cerium and sodium and the fluoride phosphate of cerium and sodium.