Aerosol-deposited BaFe0.7Ta0.3O3−δ for nitrogen monoxide and temperature-independent oxygen sensing

The gas sensing properties of resistive gas sensors of BaFe0.7Ta0.3O3−δ (BFT30) prepared by the socalled aerosol deposition method, a method to manufacture dense ceramic films at room temperature, were investigated. The electrical response of the films was investigated first under various oxygen concentrations and in a wide temperature range between 350 and 900 C. Between 700 and 900 C, the conductivity of BaFe0.7Ta0.3O3−δ (BFT30) depends on the oxygen concentration with a slope of almost 1/4 in the double-logarithmic plot vs. oxygen partial pressure. In addition, the sensor response is temperature independent. BFT30 responds fast and reproducibly to changing oxygen partial pressures even at 350 C. The cross-sensitivity has been investigated in environments with various gases (C3H8, NO, NO2, H2, CO, CO2, and H2O) in synthetic air between 350 and 800 C. BFT30 exhibits good sensing properties to NO between 350 and 400 C in the range from 1.5 to 2000 ppm with a high selectivity to the other investigated gas species. Thus this semiconducting ceramic material is a good candidate for a temperature-independent oxygen sensor at high temperatures with the application in exhausts and for a selective nitrogen monoxide (NO) sensor at low temperatures for air quality monitoring.