THE INFLUENCE OF COMPOSITIONAL VARIABLES ON THE THERMODYNAMIC PROPERTIES OF LANTHANUM STRONTIUM FERRITE MANGANITES AND LANTHANUM STRONTIUM MANGANITES

In order to obtain a better understanding of the stability limits of p erovskite phases used in new SOFC (solid oxide fuel cell) cathodes mat erials, a study of the thermodynamic properties of some perovskite-typ e oxides based on lanthanum strontium ferrite manganite and lanthanum strontium manganite was initiated. For the determination of thermodyna mic quantities, a solid state electrochemical technique has been emplo yed. The relative partial molar free energies, enthalpies, and entropi es of oxygen dissolution in the perovskite phase, as well as the parti al pressures of oxygen, have been obtained in the temperature range of 1073-1273 K. The results evidence the influence of different composit ional variables on the thermodynamic properties. (C) 1997 Elsevier Sci ence Ltd.