Research On Sensitivity Of ZnO Nanoparticles With Special Shapes

Zn,tetrapod ZnO and grainy ZnO nanoparticles were produced by renovated hybrid induction and laser heating (HILH). Based of these raw materials, the thick film gas sensors of ZnO nanoparticles were prepared by reactive sintering(600 ℃,2h) or low temperature sintering(300 ℃, 2h). The effects on resistance and gas sensor sensitivities to volatile organic compounds (VOCs) by different in shape were studied. Moreover, modern microanalysis device is used to explain the formation or growth of ZnO nanoparticles, when Zn/ZnO nanoparticles coated on tubal fundus of Al2O3 ceramic were sintered in air. The micro-analysis indicates, by low temperature sintering, ZnO nanoparticles still keep the initial shape but nanoparticles had grown up due to curvature by mass transfer in gas phase. Obviously small-size effect helps to the growth of noparticles ZnO. The Polar growth of ZnO and the melting of Zn make the porous flakes of ZnO nanoparticles uncleate and grow up when Zn nanoparticles heating. It can be shown from the sensitivity testing of ethanol that the sensitivity of the thick film of ZnO nanoparticles ascends and the peak temperature descends, compared with ZnO micro-particles. At the meantime, the surface area of ZnO nanoparticles influences the magnitude of sensitivity. Furthermore, at the same heating voltage, different electrical resistivity for different initial microscopic shape of ZnO nanoparticles, it hints there has a correlation between the carrier mobility of the thick film and the microscopic shape of ZnO nanoparticles. In addition, many times of gas sensitivity testing on many organs about different shape of ZnO nanoparticles testifies the key error of the gas sensitivity testing come from the random fluctuation of heating voltage. As the results of sensitivity testing, likewise, the thick film gas sensor of ZnO nanoparticles has diacritical and degressive gas sensitivity in sequence of ethanol, acetone, xylene, toluene, benzene. Meanwhile, the peak temperature stands at between 300℃and 400℃, and the sensitivity goes up as the concentration increased.