Metal Oxide Gas Sensing Materials

In this dissertation, it was studied how to modify the gas-sensing properties of β-CdSnO₃. On the other hand, gas-sensing properties to alcohol and acetone were improved by adding Co₃O₄ to SnO₂.A serials of Sb-doped β-CdSnO₃ samples were prepared by chemical coprecipitation method in accordance with the formula CdSn_1-xSb_xO₃. X-ray diffraction(XRD) results indicated that the ilmenite structure of β-CdSn_1-xSb_xO₃ was formed while x between 0 and 0.4. However, the resistance and gas sensitivity decreased as Sb-doped. The gas sensitivity was improved dramatically through treated Sb-doped samples at 600℃ with pure O₂ and was as high as 100. We give a preliminary interpretation of the changes of sensitivity and conductance. These changes arise from both the bulk of the grains and the grain boundaries, and are due to defects in Sb-doped samples.A serials of Co₃O₄-SnO₂ samples were prepared by chemical precipitation method. X-ray diffraction(XRD) results indicated that only structures of Co₃O₄ and SnO₂ was appeared. However, the resistance and gas sensitivities to alcohol and acetone increased as Co₃O₄ increased. But the resistance and gas sensitivity was decreased dramatically when more Co₃O₄ was added. This mechanism of promotion (electronic sensitization) is essentially the same as has been observed in the PdO-loaded SnO₂ sensor.