ABSTRACT
This paper discusses recent progress made on amperometric oxygen sensors based on tetragonal zirconia polycrystals (TZP) operated at intermediate and near-ambient temperatures. Sensor characteristics such as ac and dc conductivities, complex impedance responses and dc polarization behaviors are described. TZP has favorable properties for lower-temperature sensor application in spite of the lower defect concentration compared to conventional cubic stabilized zirconia (CSZ). The sensors measured oxygen partial pressure from almost 1 atm down to ppm range. Cross-sensitivity can be eliminated by considering the shape of the i-V curves. At high oxygen partial pressure (≥ 0.1 %), the low-biased polarization indicates that the sensor was operating under the limitation of the bulk and grain boundary transport of the TZP electrolyte. At low oxygen partial pressure, the catalytic behavior at the electrode/electrolyte interface dominates in such a polarization.
