Impedance spectroscopy of tetragonal zirconia polycrystals doped with ceria

Tetragonal zirconia, polycrystals doped with x mol% ceria (8 less than or equal to x less than or equal to 20) have been prepared by mechanical mixing using alumina as milling media. Impedance spectroscopy has been used to verify the effect produced by alumina on grain and grain boundary resistivities. For comparison purposes, more homogeneous specimens have been prepared by the coprecipitation technique. The main results show that impedance spectra exhibit predominantly ionic character for x greater than or equal to 12 in the temperature range of measurements. Alumina impurity has a minor effect on electrical resistivity whereas the blocking of charge carriers at grain boundaries is found to be primarily dependent on the grain size. (C) 2002 Elsevier Science B.V.. All rights reserved.