【作者】 利佳；

【导师】 刘天模；

【作者基本信息】 重庆大学 ， 材料科学与工程， 2007， 硕士

【摘要】 通过对钙钛矿型复合氧化物偏锡酸锌ZnSnO3气敏性能的测试和研究,发现ZnSnO3制备的气敏传感器对乙醇具有良好的气敏性能。本文以ZnSnO3为主要研究对象,分别对这种材料的制备新工艺、气敏性能、掺杂改性等方面进行了试验研究,并对其气敏机理进行了初步的探究。用离子置换低温烧结法对ZnSnO3粉末进行了制备,并对其制备的气敏传感器进行了气敏测试。测试结果表明:由反应物离子间直接置换制备得到的前驱体ZnSn(OH)6,500℃煅烧24小时制备的ZnSnO3粉末所制得的烧结型气敏传感器在工作温度为250℃时,对1000ppm的乙醇气敏的灵敏度达17.593,且选择性较好。XRD图谱分析表明:用新工艺制得的ZnSnO3粉末中未检测到其它相,说明ZnSnO3粉末为纯相;EDS分析结果表明前驱体中无杂质元素;TEM分析结果表明新工艺合成的ZnSnO3粉末粒度达到纳米级尺寸。分别选用贵金属系列和TiO2、La2O3对ZnSnO3粉末进行了掺杂改性,结果发现:La2O3或TiO2能大幅提高气敏传感器对乙醇的灵敏度;在有其它气体存在的情况下,对乙醇保持较好的选择性。掺入La2O3和TiO2的ZnSnO3气敏传感器具有良好的稳定性和可重复性;掺入La2O3的ZnSnO3气敏传感器的响应时间达9s,恢复时间达10s;掺入TiO2的ZnSnO3气敏传感器的响应时间达7s,恢复时间达12s。利用SEM对敏感层表面分析表明:气敏特性和表面的气孔率、显微裂纹分布和晶粒大小有一定关系。ZnSnO3的研究主要局限在酒敏性能方面。在ZnSnO3中掺杂贵金属PdCl2后发现其对H2有较高的灵敏度,试验确定5wt%为其最佳掺杂量。对掺5wt% PdCl2的ZnSnO3气敏传感器进行了气敏测试,结果表明:在1500ppm的氢气气氛下,灵敏度可以达到50.785,且对LPG、氨气、乙炔和甲醇的抗干扰能力较强;在工作温度为280℃时,气敏传感器的灵敏度将达最大值;掺5wt% PdCl2的ZnSnO3气敏传感器的回复-响应时间足够实际应用。有望能成为一种新型氢敏传感器。ZnSnO3是N型表面电阻控制型氧化物半导体气敏材料。当两种以上气体存在时,根据气体表面覆盖度的不同,就产生了优先吸附的现象,这是选择性的原因;并说明了掺杂剂的作用机理。更多还原

【Abstract】 Through the testing and research on gas sensitive effect of ZnSnO3, which is a kind of perovskite-type metal oxide semiconductors, it is found that gas sensors made from these ZnSnO3 powders show a high sensitivity to ethanol gas. Gas sensitive material based ZnSnO3 is viewed as the primary subject investigated in this paper. The experimental investigation with nano-sized powder preparation, gas sensitive properties and doping vario-property of ZnSnO3 has been carried out, and the gas-sensitive mechanics of ZnSnO3 have been studied simply.The nano-sized powder of ZnSnO3 was prepared by the new technology. Gas sensitive characteristics have been investigated mainly by means of HW-30A gas sensitivity detector. The precursors ZnSn(OH)6 was prepared by reactant ion exchange. Sensors that is manufactured from powders, prepared by the technology heat treated at 500℃for 24h having excellent sensitivity(S=17.593 at the C2H5OH concentration of 1000 ppm) and selectivity to ethanol. Powders prepared by different preparation technology have been analyzed, through X-ray diffraction. The results showed: the ZnSnO3 powders prepared by new technology was pure. Energy spectrum analysis indicated that there have been impurity elements in the precursors powder. TEM analysis indicated that the powders by the new technology have been achieved the nanometer.ZnSnO3 powders were doped with noble metals, TiO2 or La2O3. The results showed: sensitivity of gas sensors to ethanol can be enhanced prominently by TiO2 or La2O3 addition. The sensors with TiO2 or La2O3 addition still has a strong selectivity to ethanol when other gases exist at the same time, as well as excellent stability. The response time and the recovery time of ZnSnO3 with La2O3 addition are 9s and 10s; The response time and the recovery time of ZnSnO3 with TiO2 addition are 7s and 12s. SEM analysis about sensitive layer indicated that pore and micro crack size distribution and grain size have all significant influences on gas-sensitive characteristic.The ZnSnO3 is usually used to be the ethanol gas sensor. As our research, the gas sensor made up of ZnSnO3 and PdCl2 addition have a high sensitivity to H2 and the optimum addition amount of PdCl2 is 5wt%.We have an experiment for the gas sensitive properties, the sensitivity value of the sensor can reach to 50.785(1500ppm), selectivity to hydrogen and excellent interference rejection to LPG, Ammonia, Acetylene and Methanol. The highest sensitivity to hydrogen of gas sensor can be reached at working temperature 280℃. Moreover, the response and recovery time is excellent, The ZnSnO3 gas sensor with PdCl2 addition could be the new hydrogen gas sensor.ZnSnO3 has been recognized to be a N-type surface-control type semiconductor and complex oxide gas material. There being two distinct gases in environment, on the basis of the differentiation coverage of variant gases the phenomenon of priority adsorption come into being, so it appears selectivity to gas. Two mechanisms have been proposed for the catalyst in gas sensor.更多还原