Study On Ethanol Sensitivity Characteristic And Doping With Rare-earth Of ZnSnO₃

Traditional semiconductor ceramics ethanol sensitive materials are mainly some transition metal oxides including SnO₂,Fe₂O₃,WO₃,ZnO,In₂O₃ etc. However, these materials have still some insufficiencies in respects of selectivity, durability, and resistance to environmental influences such as higher temperature, humidity etc. Although much work has been done on the selection of additives and catalysts and on the improvement of production technology etc., things still fall short of the demand for quantitative detection. Consequently, in addition to the continued efforts to improve the existing materials, there is a constant exploration of new material aimed at obtaining ethanol sensors of better performance and still lower prices. This dissertation aims at an original zinc tin complex oxide (ZnSnO₃) based gas sensitive material. The nano-sized powder preparation, gas sensitive properties, gas-sensitive mechanics and modification of ZnSnO₃ have been researched.Perovskite-type ZnSnO₃ was prepared by the chemical coprecipitation method. Powders prepared by different preparation technology have been analyzed through X-ray diffraction. The results showed: With the application of supersonic wave and hypothermia ageing technology to the coprecipitation method, nano-ZnSnO₃ powder prepared was pure. Energy spectrum analysis indicated that there have been impurity elements in the powder. TEM analysis indicated that the powder was less than 40 nm and extraordinary mean.Gas sensitive characteristics of all agglomerate type sensors fabricated from the whole samples have been investigated. The following results could be highlighted: sensors that is manufactured from powders prepared by the technology of ultrasonic shock, ageing at -15℃for 10 hours and heat treated at 600℃for 5 hours have excellent sensitivity(S=25.8 at the C2H5OH concentration of 1000 ppm), selectivity to ethanol and excellent interference rejection to gasoline. when such elements are calcined at 400℃for 2 hours. Among all additives, sensitivity of sensors can be enhanced prominently by La₂O₃ addition and is twice more than sensor from pure ZnSnO₃ as well as the optimal addition amount is 5%mol. Moreover, the response and recovery time is about 10 S, and this sensor with La₂O₃ addition still has a strong selectivity to ethanol when other gases exist at the same time, as well as excellent stability. SEM analysis about sensitive layer indicated that pore and micro crack size...