Phase Composition and Vaporization Study of LaGa 1– x Al x O 3 , 0 ≤ x ≤ 1, and La 0.9 Sr 0.1 Ga 0.8– x Al x Mg 0.2 O 2.85 , x = 0.1, 0.2, 0.3

The vaporization of the LaGa 1– x Al x O 3 solid solution, 0 ≤ x ≤ 1, of the perovskite structure, was investigated using Knudsen effusion mass spectrometry in the temperature range of 1623–1928 K. The partial pressures of the gaseous species O 2 , Ga, GaO, Ga 2 O, and LaO were determined for the samples investigated. The equilibrium partial pressures were used for the computation of thermodynamic activities of Ga 2 O 3 and La 2 O 3 at 1800 K. Thermodynamic activities of Al 2 O 3 were obtained using Gibbs–Duhem integration. Gibbs energies of formation of the solid‐solution LaGa 1– x Al x O 3 resulted from the thermodynamic activities of the oxide components. Samples of the chemical composition La 0.9 Sr 0.1 Ga 0.8– x Al x Mg 0.2 O 2.85 , x = 0.1, 0.2, 0.3, were of practical importance in solid oxide fuel cell (SOFC) technology and also were investigated. The influence of the aluminum concentration in the perovskite phase on the thermodynamic activity and volatility of Ga 2 O 3 is presented and implications for the potential use of this material in SOFC technology are discussed.