PHASE EQUILIBRIA IN THE La₂O₃–Er₂O₃ SYSTEM IN THE TEMPERATURE RANGE 1100–1500 °C

Abstract

Phase equilibria and structural transformations in the binary La₂O₃–Er₂O₃ system at 1100–1500 °C have been studied by X-ray diffraction, microstructural analysis, and electron microprobe analysis over the entire composition range. It has been established that solid solutions based on the hexagonal modification of A-La₂O₃, cubic modification of C-Er₂O₃, and ordered perovskite-type LaErO₃ (R) phase with orthorhombic distortion exist in the system. The boundaries of phase regions and lattice parameters of the phases formed in the system have been determined. It has been found that the ordered perovskite-type LaErO₃ (R) phase is present in the composition range 45–51 mol.% Er₂O₃ at 1100 та 1500 °C. When temperature decreases to 1100 °C, the homogeneity ranges of the C-Er₂O₃ and А-La₂O₃ solid solutions are reduced. The complete La₂O₃–Er₂O₃ phase diagram has been constructed over the composition range 800–2400 °С using literature data.