【作者】 黄利华；

【导师】 周东祥；

【作者基本信息】 华中科技大学 ， 微电子学与固体电子学， 2007， 硕士

【摘要】 H2S是广泛存在于石油化工生产过程中的一种有毒气体,研究并开发检测微量H2S气体的气敏元件十分迫切,并具有广阔的应用前景。结合纳米技术制备的纳米SnO2气敏元件具有灵敏度高、选择性好、响应迅速等良好特性,越来越受到人们关注。本文采用水热法合成纳米SnO2粉体,利用丝网印刷技术制备厚膜型纳米SnO2气敏元件,对厚膜气敏元件进行CuO掺杂以提高对H2S的灵敏度和选择性。本文首先研究了高分子网络法和水热法制备纳米SnO2粉体工艺过程,通过反复实验并结合XRD、SEM和TEM等分析手段,研究得到最佳工艺条件。微观测试表明用高分子网络法和水热法制备的SnO2粉体颗粒为球状、分散性好、粒度分布均匀,并且晶粒平均粒径均小于30nm,其中用水热法制备的SnO2粉体晶粒平均粒径为3.7 nm。接下来研究了用丝网印刷法制备纳米SnO2厚膜气敏元件和H2S气敏元件的掺杂改性,工艺过程如下所述:用水热法制备CuO掺杂的纳米SnO2粉体,混合一定量的玻璃粉和Sb2O3粉体,研磨后加入有机粘合剂再研磨制成厚膜浆料,印刷在印好电极的陶瓷基片上。在空气中流平、干燥,然后烧结,制成CuO-SnO2厚膜气敏元件。对不同CuO掺杂量的厚膜进行微观表征和气敏性能测试。结果表明:厚膜颗粒为球形,粒径小于50 nm;厚膜多孔多通道,有利于H2S气体的吸附;当掺杂量为3 wt%时,厚膜元件对H2S的气敏性最好,工作温度为200℃、H2S浓度为100 ppm时,厚膜对H2S的灵敏度为219.63,同时相对CO和CH4对H2S具有很好的选择性。该厚膜气敏元件还可在室温(25℃)下检测低浓度的H2S气体。更多还原

【Abstract】 Nanocrystalline sensors have attracted great research interests due to their excellent and unique sensing properties such as high sensitivity, high selectivity and quick recover/response. Hydrogen sulfide (H2S) gas sensor has important application in industrial areas such as oil, natural gases exploitation and coal manufacturing. In this study, a type of thick-film gas sensor has been developed through screen printing method with tin oxide nanoparticles. The addition of CuO is adopted to increase the selectivity toward H2S.The fabrication of SnO2 nanoparticles through the polymer-network technique and hydrothermal method was firstly studied, and the best conditions were defined by investigation and the analysis of XRD、SEM and TEM. Meanwhile, the particle size of the SnO2 nanoparticles made on the best conditions was measured. The experiment results show that the average crystalline size of SnO2 particles obtained is below 30 nanometers. Both the nanoparticles are spherical, uniform, and well-dispersed. The investigation of fabricating nanocrystalline CuO-SnO2 thick films by the screen-printing method is introduced. In this process, hydrothermal method was used to synthesize CuO doped tin oxide nanoparticles, which was mixed with glass frit, antimony trioxide and organic vehicle to form a paste with suitable viscosity. The paste was printed on alumina substrates and then leveled at room temperature. The printed thick film samples were dried in air and sintered to obtain sufficient mechanical strength. The morphology and crystallinity of the CuO-SnO2 thick-films with different CuO doping percentage was characterized and the sensing characteristics were investigated in a vacuum chamber for H2S gas at different temperature. The results show that the particles of CuO-SnO2 thick-film are spherical and have a narrow size distribution typically below 50 nanometers. The CuO-SnO2 thick-film was highly porous and has many channels, which helps to improve the sensitivity towards H2S gas. The gas sensing element has the best performance when doping 3 wt% CuO. The gas sensitivity is 219.63 to 100 ppm H2S at 200°C, and the selectivity towards CH4 and CO is perfect. This kind of CuO-SnO2 thick-film also has good sensitivity to low consentration H2S gas at room temperature (25°C).更多还原