O3 and NO2 sensing properties of SmFe1−xCoxO3 perovskite oxides

Novel sensing materials of tri-metallic perovskite oxides, SmFe1−xCoxO3 (x = 0–1.0), were applied for a conductometric O3 and NO2 gas sensor. Fine particles of the oxides were prepared by pyrolysis of corresponding cyano-complexes, Sm[Fe1−xCox(CN)6]·4H2O. The conductivity in air increased with an increase in the Co content. This increment in the conductivity reduced the operating temperature for a reliable conductivity measurement from 250 °C for x = 0 to 150, 100 and 80 °C for x = 0.05, 0.1 and 0.15, respectively. Furthermore, the measurement at room temperature was possible for x ≥ 0.2. In 0.4 ppm O3, a large response (S > 100) was obtained for x = 0–0.15 at the above operating temperatures. While in 10 ppm NO2, the elements of x = 0.05–0.5 exhibited the maximal response at 200 °C. The Co-added oxides showed good response and recovery behavior, compared to SmFeO3 even at low temperature.