| Tin oxide is the main material of gas sensors for detection of toxic and combustible gases at present. In this thesis, we discuss the preparation of nano-sized SnO2 powder by using Sol-gel method and the powder produced by this way has been analyzed by means of XRD, SEM. TEM, and so on.Nano-sized SnO2 powder, which particle size is less than 100nm, can be obtained by sol-gel method and the particle size can be controlled by adjusting heat treating temperature. For each method final system PH value, circumstance temperature and the concentration of starting materials have different influence on fonnation of sol. Results of XRD and TEM analysis show that the particle which composed of many amorphous and crystalline units has good stability and the particle looks like sphere when heat treating temperature is lower than 500 . However, the particle size increase with the increasing of temperature obviously when treating temperature is higher than 500 . The growing rate of crystalline show powerful relationship to the temperature. The critical temperature is about 530 .The conductivity- temperature property of gas sensor made by nano-sized SnO2 powder has typical surface controlled sensor's characteristic, the conductivity peak is about 130 . The sensor response and reversion time is 8s and 18s respectively, so the sensor can work normally. The working circus of sensor is 170mA. it is higher than that of traditional sensor. The sensor's sensitivity and stability are examined in different gases .such as CO. CH4. C4H10. it shows that the sensor has high sensitivity, especially in atmosphere of CH4.
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