Phase equilibria in the La₂O₃-Nb₂O₅-Nb system and thermal stability of compounds with low degree of niobium oxidation.

The phase equilibria in the ternary system La₂O₃-Nb₂O₅-Nb have been studied at subsolidus temperatures in vacuum (6.65 × 10⁻³ Pa), and the temperature stability limits of LaNb₇O₁₂ have been determined in vacuum and during heating in air.