CO2 gas sensors based on La1-xSrxFeO3 nanocrystalline powders

The La1-xSrxFeO3 (0 <= x <= 0.3) nanocrystalline powders were prepared by sol gel method, followed by the subsequent annealing. The sensors based on La1-xSrxFeO3 nanocrystalline powders exhibit considerable response to CO2 gas. The resistance of sensors increases with an increase of CO2 concentration in dry air. Among those sensors, La0.8Sr0.2FeO3 sensor shows the best response. The response to 2000 and 4000 ppm CO2 for La0.8Sr0.2FeO3 at its optimal temperature of 380 degrees C are 1.25 and 1.36, respectively. The response and recovery times to 2000 ppm CO2 for La0.8Sr0.2FeO3 at 380 degrees C are 11 and 5 min, respectively. La0.2Sr0.8FeO3 sensor shows larger CO2 response in the background of oxygen than in the background of dry air. Such results show that the oxygen adsorbed on the surface of semiconductor may be involved in the sensing process of CO2 in dry air for La1-xSrxFeO3. The possible CO2 sensing mechanisms for La1-xSrxFeO3 sensors are discussed. (c) 2012 Elsevier B.V. All rights reserved.