ABSTRACT
Oxide compositions in the system Sr-Co-O were prepared by solid-state reaction. The oxide–oxygen reactions were investigated by thermo-gravimetric measurements. Equilibration was controlled by an amperometric lambda sensor. Thermodynamic data for the oxides-oxygen reaction were calculated. For the reaction CoO Co₃O₄ with complete change of crystal structure between ferrite- and NaCl-types, the amount of oxygen exchanged (δ = 1), and the absolute values of changes in enthalpy and entropy are the highest. The lowest values were observed in the case of the solid-solution reaction of oxygen within the stable perovskite phase of Sr_0.965Ce_0.035CoO_2.535-n-δ. As an example of an oxide characterised by a transition between rhombohedral and pseudo-perovskite modifications of the perovskite structure, literature results for SrCoO_2.5 were used. This reaction shows moderate values in oxygen exchange and enthalpy change.