Structural and electrical properties of ZnO-doped 8 mol% yttria-stabilized zirconia

Abstract

8 mol% Yttria-stabilized zirconia (8YSZ) powder was prepared by coprecipitation. ZnO (0.5, 1.0, 2.0, 5.0, 10.0 wt.%) was added to the YSZ powder through a mechanical mixing method. The densification , microstructure and electrical properties of the YSZ ceramics sintered at 1300 °C for 2 h, were investigated. It was found that the small addition of ZnO was effective in reducing the sintering temperature and promoting the densification rate of the ceramics. The 5.0 wt.% ZnO-doped YSZ has ∼ 96% relative density, as compared to ∼ 89% relative density for the undoped sample. The total conductivity of 8YSZ was evidently increased by doping small amount of ZnO. For the 0.5 wt.% doped sample, the total conductivity of 2.89 × 10 − 2 Ω − 1 cm − 1 and an increase of 120% in conductivity were observed at 800 °C, as compared to that of the undoped one. We also found that the grain boundary (GB) conductivity could be improved by small addition of ZnO. At intermediate temperature (∼ 300 °C), the maximum enhancement of GB conductivity was observed with 5.0 wt% ZnO dopant. Finally, the volume percentage of GB in the ceramics was estimated by the brick layer model. The possible mechanism related to the improved GB conduction of the YSZ due to the ZnO additions was discussed.