Co-precipitation synthesis of alumina doped yttria stabilized zirconia

Highlights: • Co-precipitation method is applied to directly synthesize Al₂O₃–doped YSZ. • The lattice parameter increases first and decreases with more Al₂O₃ doping amount. • 1 wt% Al₂O₃ doped YSZ pellet reveals the largest inter-particle contact areas. • YSZ doped with 1 wt% Al₂O₃ shows the highest ionic conductivity of 0.0334 S cm⁻¹. Co-precipitation method is applied to fabricate different amount of Al₂O₃–doped yttria stabilized zirconia (YSZ). The crystal phase, microstructure and electrical properties of the sample with access of Al₂O₃ are studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS), simultaneously a comparison is made with pure YSZ. When doping weight percentage of Al₂O₃ varies from 0 to 4%, the grain size decreases and existence of Al₂O₃ does not introduce new phase but pure cubic structure of YSZ can be observed. The lattice parameter increases first until doping 1 wt% Al₂O₃, then decreases with more doping amount. YSZ doped with different amount of Al₂O₃ has different ionic conductivity. As YSZ is doped with 0.5 wt%, 2 wt%, 3 wt% or 4 wt% Al₂O₃, the total ionic conductivity for each sample is lower than pure YSZ. Among all of the samples, the highest conductivity value belongs to the specimen of YSZ doped with 1 wt% Al₂O₃ owing to increased grain boundaries, reaching to 0.0334 S cm⁻¹.