Conductivities and silver electrode polarization resistance of solid electrolyte ceramics from ZrO2-Y2O3 powder synthesized in air plasma

Ceramic specimens have been obtained from the powder of ZrO2-7.5 mol% Y2O3 having a specific surface area of 30 m(2)/g synthesized in air plasma. The novelty of this research lies in the fact that the plasma process makes it possible to prepare so-called nano-powders with a particle size less than 100 nm, possessing specific physical, chemical and technological properties. The sintered density of the specimens was 94-96% of the theoretical value, 6.001 g/cm(3). The X-ray diffraction pattern of the specimens corresponded to a face-centered cubic lattice. Impedance in the frequency range of 100 Hz-15 MHz and d.c. polarization curves in a potential range of -10 to 10 mV were measured in the temperature range 200-850 degrees C in heating and cooling cycles. The intragrain, the grain boundary and the total bulk conductivities, the electrode polarization resistance and their activation energies were determined. The thermal stability of the studied system was proved in three measurement series up to 600-850 degrees C in heating and cooling cycles. The results obtained have shown that the conductivity of ZrO2-7.5 mol% Y2O3 ceramics is not solely a function of temperature, but also depends on the previous thermal state of the ceramics.