Coupled Microstructural and Transport Effects in p-type Perovskites for Hydrocarbon Sensing

The chemical gas sensor system of propane (C3H8) and propene (C3H6) detection in a SrTi0.8Fe0.2O3 matrix was considered. A model was formulated which incorporated the coupled processes of gases diffusing into a porous ceramic and then participating in two chemical reactions: a reversible oxygen adsorption and a two-step surface reaction which consumed the target gas. Microstructural properties of the sensor matrix were coupled with the diffusion and surface chemistry processes. The base state of the electroceramic material was determined through the solution of its equilibrium defect chemistry. This simulation represents a modeling advance as it is the � rst to couple spatial variation of microstructural properties with diffusing gas species and the attendant surface chemistry and electroceramic properties, to predict sensor response as a function oflm thickness and morphology. The results presented here compare well with experimental measurements over a broad range of conditions. This model validation will be a useful design tool for ensuing materials research work towards improved sensor device development.