Alumina was doped into cubic yttrium-stabilized zirconia by using a ceramic method, and the effect of an excess of Al2O3 upon the electrical properties was studied. The results showed that doping with alumina could significantly improve the sintering behaviour, by reducing the sintering temperature. Impedance analysis showed that the electrical properties could also be improved by such doping. This was because of the improvement in grain boundary conditions. The yttrium-stabilized zirconia, when doped with various amounts of alumina, had differing grain-boundary conductivities. Among these, the highest value corresponded to a specimen which was doped with 4wt%Al2O3.

Study of the Properties of Al2O3-Doped ZrO2-Y2O3 Electrolyte. Y.Ji, J.Liu, Z.Lu, X.Zhao, T.He, W.Su: Solid State Ionics, 1999, 126[3-4], 277-83