Phase Equilibria in the Sm2O3–CaO–NiO and Sm2O3–NiO–CoO Systems

Abstract

Phase equilibria in the 1/2 Sm₂O₃–CaO–NiO and 1/2 Sm₂O₃–NiO–CoO systems are systematically studied at 1100°C in air. The formation of two types of solid solutions Sm_{2– y}Ca_yNiO_{4 – δ} (0.5 ≤ y ≤ 0.55) and SmCo_{1– x}Ni_xO_{3 – δ} (0 < x ≤ 0.15) crystallized in the K₂NiF₄-type structure and perovskite structure, respectively, is detected. The oxygen content in the samples within the temperature range 25–1100°C in air is determined by means of high temperature thermogravimetry and dichromatometric titration. Isobaric isothermal cross sections of the phase diagrams for the 1/2 Sm₂O₃–CaO–NiO and 1/2 Sm₂O₃–NiO–CoO systems at 1100°C and \({{p}_{{{{{\text{O}}}_{{\text{2}}}}}}}\) = 0.21 atm are proposed.