The Sensing Mechanism in a Semiconducting Humidity Sensor with Pt Electrodes

The sensitivity of Sr0.95La0.05SnO3 semiconducting humidity sensors increased with a rise in firing temperature when Pt electrodes were used; such enhancement of sensitivity was not observed for sensors with RuO2 electrodes. From these results, a sensitisation model based on variations in the amount of oxygen adsorbed on the Pt particles, which were deposited on the surface of grain boundaries in the interior part of the Sr0.95La0.05SnO3 by thermal diffusion, with the firing temperatures of the Pt electrodes was presented. The validity of this model was confirmed by the fact that enhancement of the sensitivity was achieved even at a low firing temperature of the electrodes by depositing Pt on the specimen prior to the firing. 21 refs.