An alternative gas sensor material: Synthesis and electrical characterization of SmCoO3

Single-phase perovskite SmCoO3 was prepared by a wet-chemical synthesis technique using metal-nitrates and citric acid; after its characterization by thermal analyses and X-ray diffraction, sintering at 900 °C in air, gave single phase and well crystallized powders. The powders were mixed with an organic solvent to prepare a slurry, which was deposited on alumina substrates as thick films, using the screen-printing technique. Electrical and gas sensing properties of sintered SmCoO3 films were investigated in air, O2 and CO2, the results show that sensitivity reached a maximum value at 420 °C, for both gases. Dynamic tests revealed a better behavior of SmCoO3 in CO2 than O2, due to a fast response and a larger electrical resistance change to this gas. X-ray diffraction made on powders after electrical characterization in gases, showed that perovskite-type structure was preserved.