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 pl asma. The novelty of this research lies in the fact that the plasma pr ocess makes it possible to prepare so-called nano-powders with a parti cle 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 pa ttern of the specimens corresponded to a face-centered cubic lattice. Impedance in the frequency range of 100 Hz-15 MHz and d.c. polarizatio n curves in a potential range of -10 to 10 mV were measured in the tem perature range 200-850 degrees C in heating and cooling cycles. The in tragrain, the grain boundary and the total bulk conductivities, the el ectrode polarization resistance and their activation energies were det ermined. The thermal stability of the studied system was proved in thr ee measurement series up to 600-850 degrees C in heating and cooling c ycles. The results obtained have shown that the conductivity of ZrO2-7 .5 mol% Y2O3 ceramics is not solely a function of temperature, but als o depends on the previous thermal state of the ceramics.