Influence of La 2O 3 additive content on the phase stability, sintering and microstructure of 8 MOL% Y 2O 3 stabilized cubic zirconia (8YSZ) ceramic used for solid oxide fuel cell applications

Abstract

The effect of La 2O 3 content up to 15 wt% on phase stability, sintering and microstructure of cubic zirconia (8YSZ) was investigated. XRD results showed that the specimens containing up to 15 wt% La 2O 3 were composed of only cubic structure. Also, the specimens doped up to 5 wt% La 2O 3 revealed no La 2O 3 peaks, indicating that La 2O 3 was completely solubilized in the cubic structure. However, when > 5 wt% La 2O 3 was added, the peak of La 2Zr 2O 7 compound emerged, showing that the overdoped La 2O 3 was not solubilized in the 8YSZ matrix. The lattice parameter of the 8YSZ slightly decreased with the increasing La 2O 3 content up to 1 wt% but further increase in the La 2O 3 amount resulted in an increased lattice parameter. The comparison of grain size of the 8YSZ specimens with various La 2O 3 content showed that grain size slightly increased with the increasing La 2O 3 content up to 1 wt% but further increase in the La 2O 3 amount resulted in a decreased grain size.