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 

作者机构：School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Materials Science and Engineering Tsinghua University Beijing 100084 China 

出 版 物：《International Journal of Minerals,Metallurgy and Materials》 (矿物冶金与材料学报（英文版）)

年 卷 期：2012年第19卷第12期

页      面：1142-1148页

核心收录：

学科分类：080202[工学-机械电子工程] 08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0802[工学-机械工程] 

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

主　　题：gas sensors tungsten trioxide metal oxide semiconductors thin fills microcrystals nanocrystals electrochemical impedancespectroscopy (EIS) 

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.