【作者】 陈枫；

【导师】 肖奇；

【作者基本信息】 中南大学 ， 材料工程， 2014， 硕士

【摘要】 摘要：Ti02的禁带宽度分别为3.0eV(金红石相)和3.2eV(锐钛矿相)。纯Ti02气敏元件电阻较高,同时其气敏性能也较差,限制了它的进一步应用。本文通过形貌控制和Sb离子掺杂,不仅降低了材料的电阻和工作温度,还有效提高了材料的灵敏度。论文主要结果如下：(1)在碱性体系中采用水热法制备了纯Ti02纳米带和Sb掺杂Ti02纳米带,并用XRD、TEM对样品进行了表征。结果表明,纯Ti02纳米带和Sb掺杂Ti02纳米带都为锐钛矿相,Sb掺杂Ti02的形貌是长5～10μm,宽100～300nm的纳米带结构。Sb掺杂Ti02纳米带对乙醇的气敏性能结果表明：Sb掺杂不仅可以提高Ti02纳米带的灵敏度,而且使最佳工作温度由掺杂前的400℃降低为掺杂后的300℃；在摩尔比为7.5%的最佳掺杂量下,对浓度为100ppm的乙醇气体的响应时间为19s,恢复时间为11s,灵敏度为13.82,检测下限可达到1ppm。(2)在酸性体系中采用水热法制备了三种形貌组成单元的Ti02微球,并用XRD、SEM对样品进行了表征。结果表明,以纳米颗粒为组成单元的样品为纯金红石相,而以纳米棒和纳米带为组成单元的样品除了主相为金红石相外,还含有少量板钛矿相；这三种样品均为微球结构,球的直径在2-4μm。以纳米颗粒为组成单元的Ti02微球显示出最好的气敏性能,该材料在工作温度为350℃时对100ppm乙醇的灵敏度达到72.45,响应时间为28s,恢复时间为19s,检测下限可达到10ppm。(3)在酸性体系中采用水热法制备了Sb掺杂Ti02微球,并用XRD、SEM对样品进行了表征。结果表明,样品为纯金红石相,掺杂影响了样品组成单元的生长,由纳米颗粒变为长1μm左右的纳米棒。另外Sb掺杂使Ti02微球的工作温度降低至200℃。在摩尔比为7.5%的最佳掺杂量下,Sb掺杂Ti02微球对100ppm乙醇的灵敏度达到11.82,响应时间为23s,恢复时间为8s,其检测下限可达到10ppm。更多还原

【Abstract】 Abstract:Due to its wide bandgap of3.0eV(rutile) and3.2eV(anatase), TiO2gas sensor show a high resistance and poor sensitive performance, which limit its further application. In this paper, TiO2with high sensitive is fabricated by morphology control and doping, which not only reduces the resistance but also reduces the working temperature. The main contexts are as follows:(1) Sb-doped TiO2nanobelts were prepared by a simple alkaline hydrothermal process. The samples were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM). All of the samples are anatase and the nanobelts are about5-10μm in length and100-300nm in width. Compared with the undoped TiO2nanobelts, Sb-doped TiO2nanobelts show an enhancement of the sensors sensitivity, as well as a decrease of the optimal working temperature from400℃to300℃. The optimum Sb doping amount of TiO2nanobelts for ethanol sensing was7.5mol%. The7.5mol%doped TiO2nanobelts sample shows the highest response with a value of13.82and the response and recovery times to100ppm ethanol were19s and11s respectively. Moreover, the low detection limit of ethanol was estimated to be bellow lppm.(2)3D TiO2microspheres with three different building blocks morphologies were prepared by a simple alkaline hydrothermal process. The samples were characterized by X-ray powder diffraction (XRD), Scanning electron microscope (SEM). All of the samples are made up of3D microspheres, and the diameter of the microspheres is around2-4μm. The samples with3D microspheres nanostructures composed of nanoparticles are rutile, The samples with3D microspheres nanostructures composed of nanorod or nanobelts are the mixture phases of rutile and brookite. The samples with3D microspheres nanostructures composed of nanoparticles show the highest response with a value of72.45and the response and recovery times to100ppm ethanol were23s and8s respectively at the work temperture of350℃. Moreover, the low detection limit of ethanol was estimated to be bellow10ppm. (3) Sb-doped3D microspheres TiO2nanostructures were prepared by a simple acid hydrothermal process. The samples were characterized by X-ray powder diffraction (XRD), Scanning electron microscope (SEM). All of the samples are rutile, and the Sb-doped3D microspheres nanostructures composed of nanorods with a lengh of about1μm. Sb-doped3D microspheres show a decrease of the optimal working temperature from350℃to200℃. The optimum Sb doping amount of3D microspheres composed of nanorods for ethanol detection was7.5mol%. The7.5mol%doped3D microspheres composed of nanorods sample show the highest response with a value of11.82and the response and recovery times to100ppm ethanol were23s and8s respectively. Moreover, the detection limit of ethanol was estimated to be bellow10ppm.更多还原