Electrical properties of scandia- and ceria-stabilized zirconia ceramics

Electrical properties of 10 mol% Sc2O3 and 1 mol% CeO2 stabilized zirconia (10Sc1CeSZ) ceramics are investigated at temperatures up to 1000 K. Measurements are performed by combining 2- and 4-electrode methods with working frequencies of 10 Hz to 10 GHz and 10 Hz to 2 MHz, respectively. An advantage of 4-electrode method allows direct determination of contributions of grain and grain boundary conductivities to the total conductivity. These contributions at higher temperatures (when the responses of grain and grain boundary move to high frequencies) and permittivity are reliably measured by employing high frequency equipment. Obtained total conductivity values are found to be slightly higher, and activation energies lower than the vast majority of literature values. Dependence of character of distribution of charge carriers' relaxation times in ceramics grain on temperature is also estimated. It is found that grain conductivity values for 10Sc1CeSZ practically coincide with these for 10 mol% Sc2O3 stabilized zirconia (10ScSZ) at 830 K and higher temperatures. This indicates that an addition of 1 mol% CeO2 to 10ScSZ practically has no effect on charge transport and dielectric properties of cubic 10ScSZ, though even such a small amount of ceria stabilizes cubic phase at 830 K and lower temperatures.