【作者】 汤会香；

【导师】 严密； 杨德仁；

【作者基本信息】 浙江大学 ， 材料学， 2005， 博士

【摘要】 ZnO是一种重要的新型半导体材料,由于其独特的电学、光学特性,近年来引起了极大关注。而纳米ZnO材料具有比表面积大、易于表面修饰等优点,在光电子器件、传感器等领域有广泛的应用前景。对于纳米ZnO气体传感器而言,它属于表面控制型传感器件,除了掺杂作用外,其比表面积对性能也具有极其重要的作用,是纳米ZnO气敏器件研究的重点。 本文主要利用溶胶—凝胶法制备了不同掺杂以及不同表面修饰的ZnO纳米颗粒,系统研究了ZnO纳米颗粒的相结构,表面形貌和气敏性能,探索了气敏机理。得到了以下几点创新结果: 首次研究了聚十六烷基吡咯烷酮（polyvinylpyrrolidone,PVP）的表面修饰对ZnO纳米颗粒气敏性能的影响,指出PVP的表面修饰可提高ZnO纳米颗粒的分散性。利用溶胶—凝胶法制备了PVP修饰的ZnO纳米颗粒,研究了不同配比下的PVP修饰的ZnO纳米颗粒的表面形貌和气敏性能,发现Zn²⁺与PVP的摩尔比为1:1时,传感器对三甲胺（trimethylamine,TMA）具有非常高的灵敏度和选择性,并且重复性较好。研究进一步探讨了PVP修饰的ZnO纳米颗粒气敏性能提高的原因。 系统研究了掺入不同Mo含量的ZnO纳米颗粒的形貌、结晶性能和气敏性能。采用溶胶—凝胶法制备了掺入Mo的ZnO纳米颗粒,结果表明,ZnO纳米颗粒的结晶性能和形貌都受到掺入量的影响,当Mo元素的含量为10%时,传感器在室温下对NH₃气体的灵敏度和选择性较好,且重复性较好,并提出了掺入Mo的ZnO纳米颗粒NH₃敏性能变化的机理。 论文研究了掺入Fe₂O₃和Mn₃O₄纳米颗粒的ZnO纳米颗粒气敏特性。通过溶胶—凝胶法分别制备了掺入不同含量的Fe₂O₃和Mn₃O₄纳米颗粒的ZnO纳米颗粒。研究指出,两种物质掺入的ZnO纳米颗粒的结晶性能都受到掺入量的影响。但是,掺入量对形貌的影响却有所不同,Fe₂O₃掺杂的ZnO纳米颗粒的表面形貌与掺入量也有很大的关系,而Mn₃O₄的掺入对ZnO纳米颗粒的形貌几乎没有影响。传感器气敏性能的更多还原

【Abstract】 It is well known that the specific surface area of material is inverse proportion to the size of material. When the size of material is at the level of nanometer, the amounts of atoms on the surface of material increase rapidly. Due to the larger number of the surface atoms, deficiency of atom coordination and higher surface energy, these surface atoms are easy to interact with other atoms and keep a steady state. The chemical activities of them are fairly high. The sensing mechanism of Zinc oxide gas sensors is based on the surface reaction of ZnO. Therefore, high surface-volume ratio is critical to its sensing properties. It can be concluded that the gas sensing properties of nano-sized ZnO will be improved by doping.In the dissertation, the ZnO nanoparticles doped with Mo, Fe₂O₃, Mn₃O₄ and CdS nanoparticles have been prepared by a sol-gel method. PVP-modified ZnO nanoparticles with different molar ratios of Zn²⁺:PVP were also prepared by sol-gel method. The structure, morphology and sensing properties have been systematically investigated. Moreover, the mechanisms of the gas sensing properties have been elucidated. The significant results achieved in this dissertation are given as below:The gas sensing behavior of PVP-modified ZnO nanoparticles with different molar ratios of Zn²⁺:PVP has been studied prepared by sol-gel method for the first time. The sensor with a molar ratio of Zn²⁺ :PVP = 1:1 showed uniform morphology and fairly excellent sensitivity and selectivity to TMA. The response and recovery characteristics are almost reproducible and rather quick when exposed to TMA and when exposed again to N₂. Finally, the mechanism for the improvement in the gas sensing properties was discussed.The gas sensing behavior of ZnO nanoparticles doped with Mo with different molar ratios of Mo:Zn has been studied prepared by sol-gel method. The doping concentration of Mo affected the structure and morphology of ZnO nanoparticles. The sensor with a composition of Mo:Zn = 10% showed fairly excellentsensitivity and selectivity to ammonia at room temperature. The response and recovery characteristics are almost reproducible. Finally, the mechanism for the improvement in NH3-sensing properties was discussed.The gas sensing behavior of ZnO nanoparticles doped with Fe2O3 （Mn3O4） nanoparticles with different percentages of Fe:Zn （Mn:Zn） has been studied prepared by sol-gel method. The doping concentration of Fe （or Mn） affected the structure of ZnO nanoparticles. The doping concentration of Fe2O3 changed the morphology of ZnO. But there was little effect of doping concentration of Mn3O4 on the morphology of ZnO. The sensor with a composition of Fe:Zn = 2% （or Mn:Zn =3.5%） showed fairly excellent sensitivity and selectivity to ammonia at room temperature. The response and recovery characteristics are almost reproducible. Finally, the mechanism for the improvement in NH3-sensing properties was discussed.The gas sensing behavior of ZnO nanoparticles doped with CdS nanoparticles with different percentages of CdS:Zn has been studied prepared by sol-gel method. There was little effect of doping concentration of CdS on the morphology of ZnO. The sensor with a composition of CdS:Zn = 3% showed fairly excellent sensitivity and selectivity to ammonia at room temperature. The response and recovery characteristics are almost reproducible. Finally, the mechanism for the improvement in NH3-sensing properties was discussed.更多还原