【作者】 常剑；

【导师】 蒋登高；

【作者基本信息】 郑州大学 ， 化学工艺， 2004， 硕士

【摘要】 气体传感器是对气体中所含的特定成分的物理、化学性质做出迅速感应，并将其转化为适当的电信号或光信号，从而对气体种类及浓度做出检测的装置。半导体气体传感器具有灵敏度高、成本低、工艺成熟等优点，使其得到了广泛的应用。In₂O₃作为一种较为新型的气敏材料，有望改善传统气敏材料的选择性、稳定性，降低元件的工作温度；同时，目前对材料敏感机理的研究工作还落后于实际应用，难于从理论上指导气敏材料的开发与设计，对In₂O₃基敏感机理的研究鲜有报道。针对上述问题，本文首次从In₂O₃对目标气体的催化性能和气敏性能的联系这一角度出发，揭示In₂O₃基气敏材料的敏感机理。 采用微反—气相色谱联用装置，系统地评价了不同粒径In₂O₃对异丁烷和乙醇气体的催化性能；同时采用气敏性能测试设备对不同粒径In₂O₃对异丁烷和乙醇气体的气敏性能（灵敏度）进行评价；结果表明：纳米材料比普通材料有着更高的催化活性和灵敏度，且随着材料粒径的减小，二者均有大幅度的提高，有着良好的对应关系。 系统地评价了掺杂贵金属及金属氧化物的In₂O₃气敏材料对异丁烷和乙醇气体的催化性能；同时采用气敏性能测试设备对不同掺杂In₂O₃气敏材料对异丁烷和乙醇气体的气敏性能进行评价；结果表明：掺杂贵金属能够提高元件对异丁烷的灵敏度，提高对异丁烷灵敏度的原因是贵金属能够提高材料对异丁烷的催化活性，从而使In₂O₃气敏材料上吸附的负氧离子数量减少；掺杂碱性金属氧化物MgO和La₂O₃能够显著提高乙醇的灵敏度，同时使异丁烷的灵敏度有所降低；提高对乙醇灵敏度的原因在于增加了In₂O₃的催化活性，使乙醇反应速率加快，而同时降低了In₂O₃对异丁烷的催化活性，降低了异丁烷的灵敏度。因此，可以通过掺杂碱性金属氧化物提高乙醇气敏元件的灵敏度和选择性。 老化是气敏元件制作所必需的一个工艺过程，而对老化现象产生的原因尚未见文献报道。论文首次对老化过程中的乙醇气敏材料的催化性能和灵敏度的变化规律进行了研究，研究表明：材料对乙醇的催化活性和灵敏度均随老化时间的增加而逐步提高，并于七天后达到稳定，有着较好的对应关系。说明元件老化过程中灵敏度的变化是由于气敏材料催化活性的变化引起的，进一步表明材料的气敏性能从本质上依赖于催化性能。 催化活性与灵敏度有着密切的关系，催化活性低则反应速率低，难以引起材料电学性能（电阻）的明显改变，从而灵敏度低;催化活性太高，则仅能引起材料表层、而不能引起材料整体的电学性质改变，从而灵敏度也低;而催化活性适中时，元件表现出最高的灵敏度。更多还原

【Abstract】 Gas sensor is a kind of sensor that detects the target gas in the atmosphere, for it can induct the physical and chemical property of the target gases rapidly, and transform the chemical signal into electrical signal. Semiconductor gas sensor is popularly used for the detection of inflammable and toxic gases, because it has high sensitivity, low cost and mature technology. Indium oxide is a new gas sensing material, which can be expected to improve the selectivity, stability and decrease the power consumption of conventional sensing material. On the other hand, the research of gas sensing mechanism has lagged behind the application of gas sensor, so it is difficult to guide the design and development of gas sensing material. At the same time, gas-sensing mechanism of indium oxide is seldom reported. For the reasons above, the relationship between catalytic property and gas sensing performance has been established in this paper and the mechanism of indium oxide has been revealed firstly.The catalytic property of different grain size indium oxide to iso-butane and alcohol has been evaluated systematically by micro-reactor and gas chromatography; at the same time, gas-sensing property of the same material to iso-butane and alcohol has also been evaluated systematically by testing apparatus about gas sensing performance. The results show that the catalytic property and gas sensing performance of nanometer material are higher than that of common material; both of them are improved greatly with the decrease of grain size. It also shows that gas-sensing property is closely related to the catalytic property.The catalytic property of indium oxide with dopant to iso-butane and alcohol has been evaluated systematically; At the same time, gas sensing property of the same material to iso-butane and alcohol has also been evaluated systematically. The results show that the sensitivity of indium oxide doping noble metal to iso-butane is increased, for the dopant can improve the catalytic property of indium oxide; the sensitivity of indium oxide doping basic oxide(e.g.La203) to alcohol is increased andthe sensitivity to iso-butane is decreased, because these material can improve the catalytic property to alcohol and decrease the catalytic property to iso-butane. In the light of the research above, the conclusion that doping basic metal oxide can improve the sensitivity and selectivity to alcohol can be drew.Aging procedure is a necessary process of gas sensor fabrication, but the reason of this phenomena has not been reported; The catalytic and sensitivity property to alcohol during the aging procedure has also been investigated. The research shows that both of them are improved step by step with the increase of aging time and achieved a stable status in seven days. It also shows that the change of sensitivity is caused by the change of catalytic performance, and the gas-sensing performance is intrinsically depended on the catalytic performance.Catalytic property is close related to the sensing property. If the catalytic oxidation activity and reaction velocity are too small, the interaction of the sensing layer with the gas becomes too weak to generate strong response, so the sensitivity is small too. If the catalytic activity is too high, target gas or its reaction intermediates are consumed out at the surface region of gas sensing layer, being unable to induce a change in electrical resistance. Thus, the sensitivity becomes optimum when the element has an appropriate catalytic activity.更多还原