Resistive temperature independent oxygen and NO sensors of BaFe1-xTaxO3-δ produced by aerosol deposition method

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Bektas, Murat ; Hanft, Dominik ; Schönauer-Kamin, Daniela ; Stöcker, Thomas ; Hagen, Gunter ; Moos, Ralf:
Resistive temperature independent oxygen and NO sensors of BaFe1-xTaxO3-δ produced by aerosol deposition method.
2014
Veranstaltung: E-MRS 2014 Spring Meeting , 26.-30.05.2014 , Lille, France.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung , Sonstige Präsentationstyp)

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Abstract

The sensing properties of the resistive gas sensor material BaFe1-xTaxO3-δ (0.1≤x≤0.5) were investigated. BFT fine powders have been prepared by mixed-oxide route. X-ray diffraction pattern showed that perovskite BFT phase can be obtained when the powders are calcined at 1350 °C. BFT thick films have been successfully deposited by the novel Aerosol Deposition Method (ADM) on alumina substrates with a thickness around 5μm on Pt electrodes in four wire configuration. With ADM, thick and dense ceramic films can be deposited at room temperature with a carrier gas under rough vacuum.

The electrical response of the films was investigated first under various oxygen concentrations and in a wide temperature range between 350-900 °C. Between 700 and 900 °C, the sample resistance of BaFe0.7Ta0.3O3-δ (BFT30) is highly oxygen dependent but shows an almost negligible temperature dependency. BFT30 responds fast and reproducibly to a changing oxygen partial pressure even at 350 °C. The cross sensitivity of coated samples has been investigated in environments with various gases (C3H8, NO, NO2, CO, CO2 and H2O) in flowing synthetic air between 350 and 800 °C. BFT30 exhibits excellent sensing properties to NO between 300 and 450 °C in the range from 2.5 to 1000 ppm with a high selectivity towards the other investigated gas species. This semiconductor ceramic material is a good candidate for a temperature independent oxygen sensor at high temperatures and as a NO sensor at low temperatures.