U. Schönauer - Academia.edu (original) (raw)

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Papers by U. Schönauer

Research paper thumbnail of Separation of electrode reactions in multi electrode amperometric sensors

Ionics, 1995

Multi electrode amperometric sensors based on stabilized zirconia have been studied with respect ... more Multi electrode amperometric sensors based on stabilized zirconia have been studied with respect to the simultaneous detection of oxygen and NO. Both gases are of particular interest in oxygen rich exhaust gases. With a setup consisting of two subsequent electrodes it was possible to separate the reduction of oxygen and the reduction of NO spatially. Hence the currents of the two electrodes are directly correlated with the oxygen and the NO concentrations. Combustible gases like CO are oxidized at the oxygen electrode, thus lowering the effective oxygen concentration in the cell. I420 and CO2 are partly reduced at the NO electrode. This effect strongly depends on the applied potential and may be eliminated by an appropriate selection of the working parameters. The results demonstrate the potential of such multi electrode cells to the simultaneous detection of several gas components.

Research paper thumbnail of Chemical modifications of au-electrodes on YSZ and their influence on the non-Nernstian behaviour

Ionics, 1996

The interface between gold electrodes and the solid electrolyte Zr0.86Yo.1401.93 (YSZ) was chemic... more The interface between gold electrodes and the solid electrolyte Zr0.86Yo.1401.93 (YSZ) was chemically modified in several ways. Nb205 was obtained in two states: as an X-ray amorphous surface layer after vacuum evaporation and dissolved in YSZ after annealing at 1150 ~ This was confirmed by X-ray diffraction with grazing incidence and Bragg-Brentano technique. On the metal side the modification was made by potentiostatic deposition of the electronically conducting perovskite Lal.xSrxCrO3 and subsequent annealing at 1000 ~ The influence of these modifications on the electrode potential in gases containing oxygen and propylene at temperatures < 700 ~ was investigated. The known sensitivity of the Au electrode to propylene is nearly maintained after both Nb205 modifications of the solid electrolyte. After modification with the chromite layer, the sensitivity to propylene disappeared completely in gas mixtures with excess oxygen.

Research paper thumbnail of Possibilities of NOx and CHx determination using galvanic cells with perovskite-electrodes on YSZ

Ionics, 1996

Perovskite-type mixed oxides with the formula Lal_xA~Mel.yByO3~ (x = 0.01...0.2; y = 0.01...0.5; ... more Perovskite-type mixed oxides with the formula Lal_xA~Mel.yByO3~ (x = 0.01...0.2; y = 0.01...0.5; A = Ca, Sr; Me = Cr, Mn, Fe, Co; B = Mg, Ga) were investigated with the aim to use the oxides as electrode materials for galvanic cells with Y203-stabilized ZrO2 solid electrolytes (YSZ). The catalytic activity of the oxides for the oxidation, reduction and decomposition of gas components was varied by changing the transition metal and by partial substitution of lanthanum and the metal.

Research paper thumbnail of Investigation of the influence of solid ionic conductor admixtures on the performance of gas sensors based on tin oxide

Ionics, 2002

Tin oxide is a well-known and widely used gas sensitive material for detection of toxic and hazar... more Tin oxide is a well-known and widely used gas sensitive material for detection of toxic and hazardous gas components in air. Different admixtures such as catalysts, aliovalent ions and solid ionic conductors were ~ to improve the sensitivity, selectivity and stability of these sensors. For material preparation a sol-gel route is usually used and catalysts are added before sintering to improve the sensitivity and to favour the sensors to specific gas components.

Research paper thumbnail of Separation of electrode reactions in multi electrode amperometric sensors

Ionics, 1995

Multi electrode amperometric sensors based on stabilized zirconia have been studied with respect ... more Multi electrode amperometric sensors based on stabilized zirconia have been studied with respect to the simultaneous detection of oxygen and NO. Both gases are of particular interest in oxygen rich exhaust gases. With a setup consisting of two subsequent electrodes it was possible to separate the reduction of oxygen and the reduction of NO spatially. Hence the currents of the two electrodes are directly correlated with the oxygen and the NO concentrations. Combustible gases like CO are oxidized at the oxygen electrode, thus lowering the effective oxygen concentration in the cell. I420 and CO2 are partly reduced at the NO electrode. This effect strongly depends on the applied potential and may be eliminated by an appropriate selection of the working parameters. The results demonstrate the potential of such multi electrode cells to the simultaneous detection of several gas components.

Research paper thumbnail of Chemical modifications of au-electrodes on YSZ and their influence on the non-Nernstian behaviour

Ionics, 1996

The interface between gold electrodes and the solid electrolyte Zr0.86Yo.1401.93 (YSZ) was chemic... more The interface between gold electrodes and the solid electrolyte Zr0.86Yo.1401.93 (YSZ) was chemically modified in several ways. Nb205 was obtained in two states: as an X-ray amorphous surface layer after vacuum evaporation and dissolved in YSZ after annealing at 1150 ~ This was confirmed by X-ray diffraction with grazing incidence and Bragg-Brentano technique. On the metal side the modification was made by potentiostatic deposition of the electronically conducting perovskite Lal.xSrxCrO3 and subsequent annealing at 1000 ~ The influence of these modifications on the electrode potential in gases containing oxygen and propylene at temperatures < 700 ~ was investigated. The known sensitivity of the Au electrode to propylene is nearly maintained after both Nb205 modifications of the solid electrolyte. After modification with the chromite layer, the sensitivity to propylene disappeared completely in gas mixtures with excess oxygen.

Research paper thumbnail of Possibilities of NOx and CHx determination using galvanic cells with perovskite-electrodes on YSZ

Ionics, 1996

Perovskite-type mixed oxides with the formula Lal_xA~Mel.yByO3~ (x = 0.01...0.2; y = 0.01...0.5; ... more Perovskite-type mixed oxides with the formula Lal_xA~Mel.yByO3~ (x = 0.01...0.2; y = 0.01...0.5; A = Ca, Sr; Me = Cr, Mn, Fe, Co; B = Mg, Ga) were investigated with the aim to use the oxides as electrode materials for galvanic cells with Y203-stabilized ZrO2 solid electrolytes (YSZ). The catalytic activity of the oxides for the oxidation, reduction and decomposition of gas components was varied by changing the transition metal and by partial substitution of lanthanum and the metal.

Research paper thumbnail of Investigation of the influence of solid ionic conductor admixtures on the performance of gas sensors based on tin oxide

Ionics, 2002

Tin oxide is a well-known and widely used gas sensitive material for detection of toxic and hazar... more Tin oxide is a well-known and widely used gas sensitive material for detection of toxic and hazardous gas components in air. Different admixtures such as catalysts, aliovalent ions and solid ionic conductors were ~ to improve the sensitivity, selectivity and stability of these sensors. For material preparation a sol-gel route is usually used and catalysts are added before sintering to improve the sensitivity and to favour the sensors to specific gas components.

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