Oxygen Liberation from Stabilized Zirconia upon Changing DC Polarization Condition

Abstract

AbstractThe compositional change of stabilized zirconia upon the change of oxygen chemical potential was studied by applying DC-polarization method to a galvanic cell using stabilized zirconia as the electrolyte. The flow of excess charge observed upon the change of the DC-polarization condition was found due to the oxygen liberation from the bulk of the electrolyte. The total amount of liberated oxygen determined by the excess charge was analyzed in terms of the compositional change of the electrolyte due to the change of oxygen chemical potential profile in the electrolyte. The calculated values based on the increase or decrease of the electronic defects could not account for the experimental values. However, the ones based on the reduction of impurity oxides were in good agreement with the experimental values. Considerable amount of oxygen can be released from or absorbed into the zirconia electrolyte by the redox reaction of impurity oxide. It is noteworthy that this phenomenon may cause serious errors to the transport properties of electronic defect determined with the use of the relaxation processes.