CO2 sensing properties of La1−xBaxFeO3 thick film and packed powder sensors

Abstract

We compared the CO₂ sensing properties of La_1−xBa_xFeO₃ packed powder and thick film sensors. The thick film sensor exhibits a larger response to CO₂ gas with lower working temperature and shorter response and recovery times than the packed powder sensor because the former exposes a larger surface, absorbs the oxygen and interacts with CO₂ gas more easily than the latter. However, the resistance of the thick film sensor is much larger than the packed powder sensor. La_0.8Ba_0.2FeO₃ sensor exhibits the largest CO₂ response among all La_1−xBa_xFeO₃ packed powder and thick film sensors investigated. The response for the La_0.8Ba_0.2FeO₃ thick film sensor to 2000 ppm CO₂ at 150 °C is 2.29 and the response and recovery times are 14 s and 8 s, respectively. In addition, the CO₂ responses for these two types of La_0.8Ba_0.2FeO₃ sensors decrease with increase in the humidity. The possible sensing mechanisms of La_1−xBa_xFeO₃ sensors are discussed.