| 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.
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