Modeling of hydrocarbon sensors based on p-type semiconducting perovskites.
In the scope of the present contribution, perovskite SrTi(1-x)Fe(x)O(3-delta) was investigated as a model material for conductometric hydrocarbon sensing at intermediate temperatures between 350 and 450 degrees C. To explain the observations made during sensor optimization in a quantitative way, a novel sensor model was proposed. At the microscopic scale, the local gas concentration affects local conductivity of the gas sensitive material. In the case of n-type tin oxide sensors, this interaction is commonly attributed to a redox reaction between the reducing analyte gas and adsorbed oxygen. In contrast, a reduction process affecting the entire bulk was assumed to govern gas sensitivity of SrTi(1-x)Fe(x)O(3-delta) films. Although very few variables needed to be assumed or fitted, the present bulk-type model was found to represent well sensor functionality of p-type conducting SrTi(0.8)Fe(0.2)O(3-delta) films. In addition to the temperature dependence of sensor response, the hydrocarbon sensitivity, m, was predicted with good accuracy. The different sensor responses towards hydrocarbons with a different chemical reactivity and other cross-interfering species, such as NO, was explained as well as the dependence on film thickness for screen printed films.
Sahner
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Functional Materials, University of Bayreuth, Universitätsstr 30, D-95447, Bayreuth, Germany. Functional.Materials@uni-bayreuth.de
Moos
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D017610:Calcium Compounds / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry*; D004553:Electric Conductivity; D004566:Electrodes; D005290:Ferric Compounds / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry*; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D012666:Semiconductors; D012680:Sensitivity and Specificity; D013324:Strontium / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
D017610:Calcium Compounds; D002254:Carbonates; D005290:Ferric Compounds; D006838:Hydrocarbons; D010087:Oxides; C059910:perovskite; C009495:titanium dioxide; C054286:strontium carbonate; D014025:Titanium; D013324:Strontium