Investigations on selected gallium and strontium doped lanthanum chromites as electrode materials for HC detection

Perovskite-type mixed oxides with the formula LaCr_1−yGa_yO_3−δ and La_0.95Sr_0.02Cr_1−yGa_yO_3−δ with y=0.1; 0.2; 0.3 were investigated in view of their usability as electrode materials in exhaust gas sensors for hydrocarbon (HC) detection. The electrode materials were characterized regarding their catalytic activity for propylene and propane oxidation and their potentiometric behavior in oxygen containing gaseous mixtures of these combustibles. The potentiometric measurements with propane indicate higher sensitivities of the strontium doped materials than of the materials without strontium. The comparison of these results with those of the catalytic investigations using propane show, that a lower catalytic activity comes along with a higher sensitivity. The electrodes show non-Nernstian behavior. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.