Simple point contact WO_3 sensor for NO_2 sensing and relevant impedance analysis  

作　　者：Wu-bin Gao Yun-han Ling Xu Liu Jia-lin Sun 

机构地区：[1]School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China [2]Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China

出　　处：《International Journal of Minerals,Metallurgy and Materials》2012年第12期1142-1148,共7页矿物冶金与材料学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.NSAF10876017, NSAF10776017, and91023037)

摘　　要：A simple and new point contact tungsten trioxide （WO3） sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration （ppm level） environmental pollutants such as NO2. X-ray diffraction （XRD） and field emission scanning electron microscopy （FE-SEM） were applied to characterize the phase and the microstructure of the samples, respec-tively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor （W-WO3-W） showed rectifying characteristics and an ideal sensing performance of about 110 C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy （EIS） at a relatively low temperature of 150 C but faded away above 200 C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.A simple and new point contact tungsten trioxide （WO3） sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration （ppm level） environmental pollutants such as NO2. X-ray diffraction （XRD） and field emission scanning electron microscopy （FE-SEM） were applied to characterize the phase and the microstructure of the samples, respec-tively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor （W-WO3-W） showed rectifying characteristics and an ideal sensing performance of about 110 C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy （EIS） at a relatively low temperature of 150 C but faded away above 200 C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.

关 键 词：gas sensors tungsten trioxide metal oxide semiconductors thin fills MICROCRYSTALS NANOCRYSTALS electrochemical impedancespectroscopy （EIS） 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置] O484[自动化与计算机技术—控制科学与工程]