EFFECTS OF DIFFUSIVITY OF HYDROGEN AND OXYGEN THROUGH PORES OF THICK-FILM SNO2-BASED SENSORS ON THEIR SENSING PROPERTIES

Attempts were made to clarify the effects of the diffusivity of H-2 and 02 and the reactivity of H-2 on the sensing properties of thick film SnO2-based sensors. In the case of a SnO2 sensor, the interior exhibited higher sensitivity than the surface. The addition of 1.0 wt.% Pt to the sensor material resulted in a drastic decrease in the interior sensitivity, whereas the surface sensitivity increased slightly. Thus, it was revealed that optimum design of both the diffusion process of gases and the catalytic activity of a sensor material is of primary importance in promoting sensitivity of a thick film sensor with a pair of electrodes in its interior region.