Thermodynamic properties of the Lu2O3–ZrO2 solid solutions by Knudsen effusion mass spectrometry at high temperature

• The solid solutions of ZrO2–Lu2O3 system were studied at T = 2700 K.
• The Lu, LuO, ZrO and ZrO2 were found as the main vapor species.
• All activities of both components have negative deviation from ideal case.
• The minima on Gibbs free energy curves in Lu2O3–ZrO2 system correspond to 40% Lu2O3 mole fraction.

The zirconium oxide based ceramics with addition of rare-earth metal oxides is widely used for production of high temperature materials. Knudsen effusion mass spectrometry was used to study vaporization processes and thermodynamic properties of solid solutions in the ZrO2–Lu2O3 system at the temperature 2700 K. The Lu, LuO, ZrO and ZrO2 were found as the main vapor species over the samples studied. The ZrO2 and Lu2O3 activities, the Gibbs free energy of formation, the excess Gibbs free energy of formation in the samples studied were calculated. The activities of lutetium oxide in all concentration range of condensed phase have low negative deviation from ideal case whereas zirconium dioxide activities have strong negative deviation from ideal case.