Effect of yttria-stabilized zirconia sintering temperature on mixed potential sensor performance

In this article, the influence of yttria-stabilized zirconia (YSZ) sintering temperature on a Pt/YSZ/La0.8Sr0.2CrO3 mixed potential sensor performance is reported. The sintering temperature of YSZ was varied from 1000 to 1200 °C. Mercury porosity measurements were performed to estimate the porosity and tortuosity of the YSZ sample as a function of sintering temperature. Further, the surface area of YSZ was computed by the BET method. After YSZ characterization, the unbiased and biased sensor response was recorded.The 1000 °C sintered YSZ sample was taken as the reference for comparison purposes. Experimental results indicated a 30% reduction in porosity for the 1200 °C sintered YSZ sample, resulting in a 14-fold increase in the sensor response rise time. In addition, for the same sample, a 13-fold increase in sensitivity was observed upon exposure to propylene (100 ppm), associated with a 76% reduction in surface area. The slow response time of the sensor with YSZ sintered at higher temperatures has been attributed to higher tortuosity (delay in gas permeation to the three-phase interface). Whereas, reduced heterogeneous catalysis induced by lower surface area accounts for the rise in sensitivity levels. The optimum YSZ sintering temperature was found to lie between 1100 and 1150 °C.