Polymorphic Nanosize Tungsten Trioxide Produced Continuously from Ammonium Paratungstate 1/2

Tungsten trioxide (WO₃) is a kind of importantηtype semiconductor oxides with varieties of crystal structure, and has been applied in fields of electrochromic, photochromic, sensing, and catalysis. The size of quasi-spherical and spherical tungsten trioxide is respectively 100nm-700nm and 20-200nm. These two kinds of WO₃ can used as precursor for synthesing nanosize tungsten carbide; the length of diagonal of octahedral tungsten trioxide is less than 1μm, used as gas sensing to produce gas sensor because of the high sensitive; the length of diagonal of WO₃ with irregular polyhedral angle is about 10nm-2μm, and it can be used to adsorb organic molecules, or used to photodegradate organic material. The more fine particles the WO₃ is, the more superior property the subsequent products. Therefore, reducing size of WO₃  is the best way to further utilize the excellent properties of WO₃ and broaden its application field.



Vapor Deposition Method is one of the most effective methods to prepare nano structure, and a variety forms of particles produced by the technology of vapor deposition, such as thin films, whiskers and particles ect.. And the Vapor Deposition Method can produce product with high purity from the low concentration of reactants. But the disadvantage of conventional Vapor Deposition Method is the limited yield; and it can’t achieve producing continuously because of products collected in the environment of high vacuum or temperature. This paper presents a method that can produce polymorphic nanosize tungsten trioxide continuously, take APT.XH₂O as raw material, innovatively combine Vapor Deposition Method with calcination, take argon as carrier gas, collect the products in the area of low temperature, and then achieve the goal of producing polymorphic nanosize tungsten trioxide continuously.

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