Grain-boundary conduction was studied, in 15mol%CaO-stabilized material, after adding Al2O3 - which was in the form of fine powder or monocrystalline particles (4 to 10μm) - as a scavenger for siliceous phases. The addition of 1mol%Al2O3 improved the grain-boundary conduction after sintering at up to 1500C. It deteriorated for higher temperatures. The avoidance of Al2O3 dissolution into intergranular glass phases was a key factor in maximizing scavenging efficiency. At 1450C, the addition of monocrystalline Al2O3 (4 to 10μm) enhanced the grain-boundary conductivity by a factor of 14 to 16. This enhancement was about twice as great as that produced by fine Al2O3 powder. This was explained by a combination of reaction path changes and fast grain-boundary diffusion.

The Influence of Alumina and its Distribution upon Grain-Boundary Conduction in 15mol% Calcia-Stabilized Zirconia. J.H.Lee, T.Mori, J.G.Li, T.Ikegami, S.Takenouchi: Ceramics International, 2001, 27[3], 269-76