The electromotive force measurements were made on the stacked pellet type galvanic cells consisting of the 0.85 ZrO2-0.15 CaO electrolyte with the electrodes including Fe-FeO (wiistite), FeO-Fe2O4 (magnetite), Fe2O4-Fe2O3 (hematite), Ni-NiO and Co-CoO two-phase coexisting systems at temperatures of 630°to 1100°C, in order to obtain the relative partial molar free energies of oxygen for the two-phase oxide systems. The data obtained were in good agreement with the accepted values, which proved that the cells functioned satisfactorily.
The feasibility of employing the solid electrolyte galvanic cell method, especially the open cell staccked pellet technique, was discussed. The careful consideration of several factors made it possible to obtain equilibrium values of the electromotive force.