Micro Semiconductor CO Sensors Based on Indium-Doped Tin Dioxide Nanocrystalline Powders

The precursors of SnO2 or In2O3/SnO2 nanocrystlline powders have been prepared bythe sol-precipitation method. The precursors were calcined at different temperatures to prepareSnO2 or In2O3/SnO2 nanocrystalline powders with different particle sizes. The nanocrystalliteswere examined by differential thermal analysis (DTA), X-ray diffraction (XRD) andtransmission electron microscopy (TEM). And then thick film CO sensors were fabricated usingprepared SnO2 or In2O3/SnO2 nanocrystlline powders loaded with PdOx. The composition thatgave the highest sensitivity for CO was in the weight% ratio of 5 wt.% In2O3/SnO2:PdOx as99:1(wt %). The composite material was found sensitive against CO at the working temperature200 °C. It was found that the sensors based on In2O3/SnO2 nanocrystalline system exhibitedvery short response time to CO at ppm level. These characteristics make the sensor to be apromising candidate for detecting low concentrations of CO.