Impedance spectroscopy analysis of percolation in (yttria-stabilized zirconia)-yttria ceramic composites

(ZrO2:8 Mol% Y2O3)+M mol% Y2O3 ceramic composites with nominal yttria concentration varying from 0 to 70 mol% (0-82.9 vol.%) were prepared by evaporation of a suspension of ZrO2:8 mol% Y2O3 and Y2O3 in ethanol followed by pressing and sintering. The samples were analyzed by X-ray diffractometry and scanning electron microscopy for microstructural characterization. The electrical properties were studied by impedance spectroscopy (IS) allowing for the separation of the inter- and intragranular components of the electrical conductivity. The percolative behavior of these components was analyzed using the general effective media (GEM) equation and the percolation thresholds found were similar to 28 vol.%. The results indicate that impedance spectroscopy provides useful information in addition to the dc techniques concerning the electrical characterization of composite materials. (C) 2003 Elsevier B.V. All rights reserved.