Yellow tungsten oxide, for producing thermal insulation master batch, may be synthesized by hydrothermal method using Na2WO4 • 2H2O and HCl as raw materials, Na2SO4 as an additive.
Influence of Additive Concentration on Crystal Form of WO3
XRD image of WO3 prepared at different Na2SO4 concentration is shown in the figure below. As can be seen from the picture, when the concentration of additive Na2SO4 is 0.5M, 0.25M, and 0.125M, the diffraction peaks of WO3 are basically the same, belonging to the typical hexagonal WO3. And there is no impurity peak, indicating purity of the product is very high. The diffraction peak of tungsten trioxide is strong and sharp, indicating that its crystallinity and grain size are large. When the concentration of Na2SO4 gradually decreases, the intensity of the diffraction peaks of crystal faces of WO3 gradually increase, which indicates that the lower the Na2SO4 concentration, the more complete the product crystallization. When concentration of Na2SO4 is reduced to 0.125M, the diffraction peak is very sharp, indicating that grain size of crystal is large. It can be seen that, the adding of Na2SO4, the synthesized products are hexagonal WO3, and different concentrations of Na2SO4 have an influence on grain size, but have no effect on crystal form.
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Yellow Tungsten Oxide Applied for Thermal Insulation Master Batch
