High-T NO_x Sensing Elements Using Conductive Oxides and Pt

摘要

Development of NO_x sensing elements intended for operation at T ～600℃ are described. The elements were fabricated by depositing co-planar La_(1-x)Sr_xBO_3 (B = Cr, Fe) and Pt electrodes on yttria-stabilized zirconia substrates. Characterization of the elements included response to NO_2 and NO as well as the [O_2] dependence of the NO_2 response. Much stronger (～40 mV for 450 ppm NO_2 in 7 vol% O_2 at 600℃) sensing responses were observed for NO_2 than NO, indicating these elements are best suited for detection of NO_2. Pronounced asymmetries were observed between the NO_2 step response and recovery times for the elements, with temperature being the primary variable governing the recovery times in the temperature range 500-700℃.