Temperature compensating materials were investigated for a resistive oxygen sensor using Ce0.9Zr0.1O2 as a sensor material for lean-burn engines. The temperature dependence of a temperature compensating material should be the same as the sensor material; therefore, the Y concentration in CeO2-Y2O3 was optimized. The resistance of Ce0.5Y0.5O2-δ was independent of the air-to-fuel ratio (oxygen partial pressure), so that it was confirmed to function as a temperature compensating material. Sensor elements comprised of Ce0.9Zr0.1O2 and Ce0.5Y0.5O2-δ were fabricated and the output was determined to be approximately independent of the temperature in the wide range from 773 to 1,073 K.
We fabricated resistive-type oxygen sensors having a Ce 0.9 Zr 0.1 O 2 thick film as a sensing material and a Zr 0.8 Y 0.2 O 2 d thick film as a temperature compensating material for the first time, and measured the resistance of the two thick films and the output of the sensors in model exhaust gas which was a combustion gas of propane. Then, we considered whether the sensor could be used as aélambda sensor,êwhich can identify whether the airto-fuel ratio of exhaust gas is rich or lean region. As a result, we confirmed that the resistance of the Ce 0.9 Zr 0.1 O 2 thick film was low and high in the case of rich and lean regions, respectively. The activation energy of the resistance of the Ce 0.9 Zr 0.1 O 2 film was 0.41 and 1.20 eV in rich and lean regions, respectively, and the mean value of them was 0.8 eV. The resistance of the Zr 0.8 Y 0.2 O 2 d thick film in rich was almost the same as that in lean. The activation energy was 0.92 and 0.98 eV in rich and lean, respectively, and similar to the mean value of the activation energies of the Ce 0.9 Zr 0.1 O 2 film in rich and lean. This result shows that the combination of the Ce 0.9 Zr 0.1 O 2 and Zr 0.8 Y 0.2 O 2 d films is better for theélambda sensor.êThe electrode structures of the sensor were optimized so that the mean value of the resistances of the Ce 0.9 Zr 0.1 O 2 film in rich and lean was the same as the resistance of the Zr 0.8 Y 0.2 O 2 d film. The difference in output of the resistive oxygen sensor having the optimized electrode between rich and lean regions was more than 0.7 V, when the source voltage was 1.0 V. The output dramatically changed on the stoichiometric air-fuel ratio. From above-mentioned results, we conclude that the resistive oxygen sensors fabricated in this study are able to be used asélambda sensors.ê
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.