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

SmCoO3 precursor powder was synthesised by dissolving stoichiometric amounts of the metal nitrates in water containing citric acid, followed by drying and exothermic reaction at 75 C. The precursor was calcined in air at 600-900 C to obtain single-phase perovskite structure mixed oxide. Thick films were prepared on alumina substrates by screen printing followed by sintering at 700 C. DC resistivity was measured over the temperature range ambient-700 C, in atmospheres of dry air, oxygen and carbon dioxide. Maximum sensitivity was exhibited at 420 C. The films were more sensitive to changes in carbon dioxide content than to changes in oxygen, exhibiting a faster response and a greater resistivity change. The perovskite structure was retained following exposure to the test gases. 34 refs.