Influences of ZnO on the Properties of SrZr0.9Y0.1O2.95 Protonic Conductor

The effects of ZnO additive on the microstructure, phase formation, and electrical conduction of yttrium-doped strontium zirconate were investigated. The sintering temperature of SrZr_0.9Y_0.1O_2.95 can be lowered to 1350°C by addition of ZnO. The electrical conduction is found to be strongly correlated with the ZnO contents. When the ZnO content is <5 mol%, the electrical conductivity increased with an increase in the ZnO contents. Electromotive force measurements under fuel cell conditions indicated a pure ionic conduction over this range of ZnO contents. However, it had a detrimental effect on the electrical conduction when the ZnO content was more than 6 mol%. The main reason for this is discussed according to the defect chemistry and microstructure.