Penetration and characteristics of an intergranular-liquid phase during sintering of CaSi2O5-dropped 8 mol%-yttria-stabilized zirconia estimation by impedance spectroscopy

The grain-boundary resistivity of CaSi2O5-dropped 8 mol%-yttria-stabilized zirconia (8YSZ) was determined by impedance spectroscopy using sub-millimeter-scale electrodes. During sintering, a liquid that formed at the top surface of the specimen penetrated into the 8YSZ and induced enhanced grain growth near the surface region. The grain-boundary resistivity of the specimen surface was observed to be 150 times higher than that of the interior. The deterioration of the grain-boundary conductivity was explained in terms of the presence of an intergranular siliceous phase.