Vaporization and thermodynamics of La1-xSrxCrO3-delta investigated by Knudsen effusion mass spectrometry

摘要

Vaporization of the La1-xSrxCrO3-delta perovskite phase, x = 0.10-0.30, was investigated by the use of Knudsen effusion mass spectrometry at 2000 K. The partial pressures of Cr(g), CrO(g), Cro,(g), Sr(g), Sro(g), and LaO(g) were determined for all the samples investigated. The partial pressure of O-2(g) was, in addition, evaluated from the gaseous equilibria. The experimental data were interpreted by the use of the phase diagram of the SrO-Cr2O3-La2O3 system under low oxygen pressure previously studied by us. The equilibrium partial pressures were used for the calculation of thermodynamic activities of the components at 2000 K. Gibbs energies of formations of La1-xSrxCrO3 at 2000 K resulted from the thermodynamic activities as -85.2 +/- 3.7 kJ mol(-1) (for x = 0.11) to - 93.5 +/- 4.3 kJ mol(-1) (for x = 0.30). The results were compared with the thermodynamic data of the undoped LaCrO3(s). Implications of the present data for the potential use of the material in SOFC technology were also discussed, (C) 2001 Elsevier Science B.V. All rights reserved. [References: 32]