Nanocrystalline BaSnO(3) as an Alternative Gas Sensor Material: Surface Reactivity and High Sensitivity to SO(2)

Nanocrystalline perovskite-type BaSnO(3) was obtained via microwave-assisted hydrothermal route followed by annealing at variable temperature. The samples composition and microstructure were characterized. Particle size of 18–23 nm was unaffected by heat treatment at 275–700 °C. Materials DC-conduction was measured at variable temperature and oxygen concentration. Barium stannate exhibited n-type semiconductor behavior at 150–450 °C with activation energy being dependent on the materials annealing temperature. Predominant ionosorbed oxygen species types were estimated. They were shown to change from molecular to atomic species on increasing temperature. Comparative test of sensor response to various inorganic target gases was performed using nanocrystalline SnO(2)-based sensors as reference ones. Despite one order of magnitude smaller surface area, BaSnO(3) displayed higher sensitivity to SO(2) in comparison with SnO(2). DRIFT spectroscopy revealed distinct interaction routes of the oxides surfaces with SO(2). Barium-promoted sulfate formation favoring target molecules oxidation was found responsible for the increased BaSnO(3) sensitivity to ppm-range concentrations of SO(2) in air.