[en] Phase equilibria in the system HFO₂-Y₂O₃-La₂O₃ at 1250 C have been studied. State diagram of the system HFO₂-Y₂O₃-La₂O₃ at 1250 C has been plotted. The isothermal cross section is defined by specific features of phase equilibria in restricting binary systems: formation of solid solutions on the basis of ordered phases La₂Hf₂O₇(Py), LaYO₃(R) and different crystal modifications of the initial components. Refs. 33