Vaporization and thermodynamics of ceramics based on the La2 O3 -Y2 O3 -HfO2 system studied by the high-temperature mass spectrometric method.

Vaporization of ceramics based on the La2 O3 -Y2 O3 -HfO2 system at 2337 K led to selective transition of La2 O3 and Y2 O3 to the gaseous phase, with the La2 O3 vaporization rate being higher than that of Y2 O3 . The directions of composition changes of samples due to their vaporization at 2337 K were determined. In the solid solution of this system negative deviations from ideal behavior were found. The ability to estimate the excess Gibbs energies in the solid solution of the La2 O3 -Y2 O3 -HfO2 system by the Kohler method was shown.