Nano particle size tungsten trioxide may be applied for producing thermal insulation coating, and therefore it is widely used in architectural window films, automotive heat-insulating films and the like. Therefore, it is necessary to conduct relative research on the preparation of nano grain size tungsten trioxide. For example, the role of urea in the preparation of nanometer tungsten trioxide by hydrothermal reaction using sodium tungstate, urea and hydrochloric acid as raw materials should be studied.
Studies have shown that it is possible to stabilize the metastable hexagonal phase tungsten trioxide due to the existence of those monovalent cations in the hexagonal phase WO3. In this process, urea undergoes a hydrolysis reaction (hydrothermal condition) to release NH4+ (monovalent cations) and HCO3-. So, it is necessary to study the role of urea in the reaction process. Thus, a comparative experiment was conducted for the addition of different inorganic salts containing NH4+ and HCO3-. First, (NH4)2SO4 with an equivalent molar amount of NH4+ of urea and NH4HCO3 of an equimolar amount of HCO3- of urea are added to the reaction system instead of urea. The synthesized samples were subjected to XRD testing.
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