Planar Impedancemetric NO Sensor with Thick Film Perovskite Electrodes Based on Samarium Cobaltite

Impedancemetric NO sensors were fabricated, comprising yttria stabilized zirconia disc with thick film Sm0.9Sr0.1CoO3- electrodes of different design. Impedance measurements were performed at 600-800 degrees C for frequencies 0.01Hz-100kHz, in gas mixtures with 0-400ppm of NO. The smaller arc on Nyquist plots can be associated with solid electrolyte-electrode interfacial phenomena, while the bigger one to the perovskite electrode reactions. As NO concentration increases, the bigger arc decreases and its maximum shifts toward higher frequencies. Both the sensitivity and the applicable NO concentration range were found to be dependent on the sensor design, temperature and chosen frequency.