WANG Shih-Han,CHOU Tse-Chuan,LIU Chung-Chiun.Nano-crys talline tungsten oxide NO2sensor[J].Sens Actuators B,2003,94:343-351. [2]JIMéNEZ I,CENTENO M A,SCOTTI R,et al.NH3interaction with chromium-doped WO3nanocrystalline powders for gas sensing appli-cations[J].J Mater Chem,14:2412-2420. [3]AZAD Abdul-Majeed,HAMMOUD Majed.Fine-tuning of ceramic based chemical sensors via novel microstructural modification:I low level CO sensing by tungsten oxide,WO3[J].Sens Actuators B,2006,119:384-391. [4]ROSSINYOL E,ARBIOL J,PEIRóF,et al.Nanostructured metal oxides synthesized by hard template method for gas sensing applica-tions[J].Sens Actuators B,2005,109:57-63. [5]GEORGE L,SPIROS P,PANAYIOTIS Y,et al.Structural and electro-chemical properties of opaque sol-gel deposited WO3layers[J].Appl Surf Sci,2003,218:275-280. [6]BOULOVA M,GASKOV A,LUCAZEAU G.Tungsten oxide reactivity versus CH4,CO and NO2molecules studied by raman spectroscopy[J].Sens Actuators B,2001,81:99-106.