Synthesis Of Nanozno Material And Study On Its Gas Sensing Properties

The thin film gas sensor made of ZnO has advantages of fast response, short recovery time, good selectivity and pollution to environment and so on, and ZnO, which is one of the most extensive application of gas-sensitive material, can be detect all kinds of flammable, explosive and dangerous gas. And doping is the main ways, which can improve the sensitivity and selectivity of the ZnO thin films. In this paper, ZnO thin film is prepared by sol-gel method. And we analyze its structure and its components. And we research the impact of fabrication process and doping on the properties of the thin-films. And the mechanism of its gas sensitivity is also proposed briefly. The following is some results:1. The ZnO thin film, which range of particle size is 14.4 to 34.2 nm, is prepared by sol-gel method successfully. Results show that the concentration of Zn(CH₃COO)₂ is little impact on the ZnO grain size. The grain size of ZnO thin films, will ascend with the rising of sintering temperature. The grain size of ZnO thin films doping La³⁺,Cu²⁺ and so on will significantly reduced2. The gas-sensing properties of ZnO films by sol-gel method are explored from the view of sintering temperature and heating voltage. Results show that the sensitivity of the pure ZnO films increases with rising of the heating voltage, and when the heating voltage is 5.11 V, the sensitivity to ethanol is the highest. The gas sensitive property increases firstly, then decreases. There is an optimum sintering temperature, which is 500℃, when the sensitivity is the maximum.3. We detect the gas-sensing properties of ZnO thin film doping La³⁺, Ce³⁺, Cu²⁺. The results show that the gas-sensing sensitivity of ZnO doping La³⁺, Ce³⁺, Cu²⁺ is more than twice than the sensitivity of the pure ZnO thin films. But the heating voltage is also increased at the same time, which may be due to the changes of micro-structures of the doped films, in particular, the structure of grain boundary. And the sensitivity to alcohol of ZnO thin film doping Cu²⁺ is the highest, up to 23.32.