Investigation on Impedencemetric-type NO_2 Sensor Based on La_(0.75)Sr_(0.25)Mn_(0.5)Co_(0.5)O_(3-δ) Sensing Electrode

The perovskite nanoparticle materials La0.75Sr0.25Mn0.5Co0.5O3-δ were prepared in YSZ porous layer by in-filtration technology.An impedancemetric-type NO2 sensor was prepared with the nanoparticle materials as sensing electrode and YSZ as solid state electrolyte.The crystalline phase and microstructure of sensing electrode in the NO2 sensor were investigated by XRD and SEM.The result of XRD indicated that perovskite LSCM was obtained in porous YSZ after infiltrating precursor solution and heat-treatment.SEM analysis demonstrated that the grain size of LSCM was 50-100 nm,and the LSCM nanoparticles were closely incorporated with YSZ frames in porous layer.The sensing characteristics of the present device were also investigated at 450-600℃.The results suggested that the sensor showed preferential sensitivity to NO2 with NO2 concentration from 0 to 1000μL/L.When frequency was fixed at 0.1 Hz,the total impedance of the sensor changed almost linearly with NO2 concentration.The real response time of the sensor to NO2 gas was around 40s at gas flow rate of 400mL/min.It is also found that the response of sensor is stable at given time and the sensor has good anti-interference to O2 and CO2.