The Characteristics Of Gas Sensitivity And Micro-structure Of SnO₂

The phase structure, particle size and gas sensitive character of SnO₂ gas sensor prepared by solid reactivity method and Sol-gel method have been studied by means of XRD, SEM, I-V measurements, sensitivity, selectivity, response resume time. The influence of composition and technological conditions of SnO₂ gas sensor on particle size and gas sensitivity has also been investigated. SnO₂ gas sensor is prepared at different sinter temperature using SnO₂ material produced by solid reactivity method and sol-gel method respectively, with Sb₂O₃ as drop resistance solution. The XRD and SEM test results show that technological conditions of SnO₂ material, Sb₂O₃ doping quantity, sinter temperature, the stickiness have great effect on the particle size. The particle sizes of SnO₂ prepared by sol-gel method and by solid reactivity method are about 30 nm and 70 nm respectively; it has been found that with the increase of annealing temperature, the particle size become large accordingly; the effect of Sb₂O₃ doping quantity on the particle size is smaller. When Sb₂O₃ doping quantity is 2%, the particle size is about 80 nm; the kinds of stickiness affect the particle size, and the particle sizes of SnO₂ prepared by using organic stickiness and by using inorganic stickiness are about 70 nm and 150 nm respectively. By studying on its work voltage-resistance, sensitive, selectivity, response resume time, the conclusion can be drawn that under the sinter temperature 500 ℃, the performance of the gas SnO₂ sensor is best optimized when using the SnO₂ made by sol-gel as the based material, doping 2%Sb₂O₃ as the drop resistance,polythene as the stickiness, platinum as the activator. The theory analysis shows that the resistance of gas sensitive sensor has a consanguineous correlation with transference. The variety of transference with temperature changing determines the variety of work resistance; The quantum size effect and surface effect of nanometer SnO₂ make sensor's gas sensitivity optimized. The effect of stickiness on SnO2 particle size make the particle size become large through forming congealable center by doping melt ion and attracting positive and negative ion; At the same time, the melt ion has also an catalyze and increase sensitivity.