Thermodynamic properties of Y2O3 phases and the yttrium–oxygen phase diagram

We present a thermodynamic evaluation of the yttrium–oxygen (Y–O) system by focusing on the thermodynamic properties of the Y2O3 phases. A review of the experimental data on phase equilibria in the Y–O system and the thermodynamic properties of the Y2O3 phases pertinent to the evaluation is provided. The transition properties of Y2O3 have been assessed by considering systematic trends in the thermodynamic behaviour of rare earth sesquioxides and scandia. With the evaluated data, the phase relations and thermodynamic properties of the Y–O system can be calculated and are in good agreement with the majority of experimental measurements.