Phase Relations of the Nd2O3-CaO-Fe2O3 System at 1473 K in Air

The equilibrium phase relations of the Nd2O3-CaO-Fe2O3 system were investigated at 1473 K in air using a high-temperature isothermal equilibration technique followed by quenching. Using x-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) analysis of quenched samples, twelve two-phase equilibria regions and eleven three-phase equilibria regions were observed. A series of solid solutions Nd1−xCaxFeO3−δ formed in the ranges of 0 ≤ x ≤ 0.2, 0.5 ≤ x ≤ 0.6, and 0.6 < x ≤ 1 were found. Ternary compound Ca1−xNd1+xFeO4−δ was observed to be stable at 1473 K with limited substitution of Nd by Ca. The 1473 K isothermal section was constructed for the Nd2O3-CaO-Fe2O3 system.