The structure, electrical and sensing properties for CO of the La0.8Sr0.2Co1−xNixO3−δ system

The perovskite structure of La0.8Sr0.2Co1−xNixO3−δ film can be formed in a wide range between 0≦x≦0.6 by the dipping method. The distortion of the perovskite structure is described with changing Ni content. The influence of Ni ions which replaced the Co ions on B-sites can be directly observed from its electrical and sensing properties to CO gas. In the range from room temperature to 600°C, the La0.8Sr0.2Co1−xNixO3−δ films exhibited semiconductor behavior. The energy barrier for conduction can be reduced by Ni doping. We studied the sensitivity to 50 ppm CO in a temperature range from 150 to 300°C. The influence on sensitivity with different Ni content has also been investigated. The best sensitivity to CO was observed with Ni content equal to 0.5 mol ratio at an operating temperature of 200°C. From the life cycle test at 200°C for La0.8Sr0.2Co0.5Ni0.5O3−δ film, the sensitivity decays to a constant value, but it can be repeatedly used by reheating the film to over 300°C.