Characteristics of La0.8Sr0.2Co1−xCuxO3−δ film and its sensing properties for CO gas

La0.8Sr0.2Co1−xCuxO3−δ films prepared by using the dipping method have been shown to give a relatively high sensitivity to CO of concentration between 50 and 200 ppm for the temperature between 200 and 350°C. The sensing properties of La0.8Sr0.2Co1−xCuxO3−δ films are functions of temperature and Cu content. The maximum sensitivity was obtained for films doped with x=0.4 of Cu and operated at the temperature of 250°C. The sensing mechanism is a surface reaction process, which can be thermally activated. The relationship of sensitivity to CO concentration is shown to be linear; while, the electric resistance of the films is shown to be an exponential function of CO concentration. An empirical relationship of R≈KCCOα with α=0.0273 can be obtained.