Preparation and characterization of plasma-sprayed yttria stabilized zirconia as a potential substrate for NOx sensor

Fully stabilized zirconia containing 8 mol% of yttria was synthesized by solid state reaction method and deposited as a thick film by plasma spray coating. The crystal structure and phases developed were characterized by X-ray diffraction (XRD). The surface structure, surface morphology and microstructure developed were studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The actual doping content was measured by electron probe micro-analyzer(EPMA). The plasma sprayed YSZ was characterized for its electrolytic properties by ac and dc conductivity measurements. The maximum conductivity for plasma sprayed YSZ was found to be -1.62 Scm(-1), which was lesser than the conductivity of standard 8YSZ of -1.03 Scm(-1) at pO(2)=0.21 atm. However; conductivity trends in the arrhenius plot was observed to be similar for entire YSZ's, suggesting that the conductivity mechanism is same and dominated by oxygen ion conductivity independent of oxygen partial pressure. These promising electrolytic properties of thermal sprayed YSZ suggest that the thermal spray coating method may lead to be used as a potential method for the fabrication of NOx sensor.