Investigation into the interactions between Bi2O3-doped ZnO and AgPd electrode

Bi2O3-doped ZnO multilayer specimens with inner AgPd electrodes are prepared. The interactions between the Bi2O3 dopants and AgPd electrodes at elevated temperatures are investigated. It is found that during co-firing, two oxide phases, PdO and PdBi2O4, are formed at 400 °C and 600 °C, respectively, using synchrotron X-ray analysis. The PdBi2O4 phase remains in the multilayer specimens after co-firing. Despite the formation of PdBi2O4, the Pd content in the AgPd electrodes increases with increasing firing temperature. In contrast, a decrease in Ag content in the electrodes at elevated temperatures is apparent; this is mainly due to the vaporization of Ag. The present study shows that after firing at 1200 °C for 1 h, the inner AgPd electrodes experience degradation due to the formation of PdBi2O4 and the loss of Ag.