Sintering and conductivity of nano-sized yttria-doped ZrO2synthesized by a supercritical CO2-assisted sol-gel process
Résumé
This study reports on the electrical characterization of nano-sized zirconia powders doped with 3 and8 mol% Yttria, referred to as 3Y-ZrO2and 8Y-ZrO2, respectively. Powders were synthesized using a super-critical CO2assisted sol-gel method to control the size and morphology of the powder particles. Sparkplasma sintering (SPS) was used to sinter the powders and maintain a fine microstructure with small grainsize. The microstructure and chemical composition of the resulting ceramics was evaluated by electronmicroscopy techniques, showing grain boundaries depleted of amorphous phase. Electric conductivity ofthe 8Y-ZrO2pellets was determined by electrochemical impedance spectroscopy techniques, between200 and 800◦C, and correlated with the microstructure. The bulk electric response at 300◦C is compara-ble to commercially available Y-ZrO2compositions. Compared to conventionally prepared samples weobtain lower conductivity in the high temperature range, still values in this study are twice superior to3Y-ZrO2samples similarly prepared by SPS.