Mass spectrometric study of thermodynamic properties of BaO-CeO2. The formation enthalpy of BaCeO3 (solid)

Abstract Barium cerate with additions of rare-earth or 3- d metal oxides is widely used for production of solid electrolytes, ionic, and electron–ionic conductors. Knudsen effusion mass spectrometry was used to study vaporization processes and thermodynamic properties of solid solutions in the BaO – CeO 2 system at the temperature 2000 K. Ba, BaO, CeO and CeO 2 were found as the main vapor species over the samples studied. Activity values and Gibbs energy of BaO and CeO 2 in the samples studied were calculated. The activities of barium and cerium oxides in the concentration range of the homogeneous melt (70–32 mol. % of BaO) and in the region from 32 to 5 mol % of BaO (solid solution of CeO 2  + liquid) have low negative deviations from the ideal case. The determined value of the standard formation enthalpy of solid barium cerate is equal to −1692 ± 17 kJ/mol.