Tungsten trioxide nanopowder applying for heat insulation coating may be synthesized by hydrothermal method. And you may know the result that the hydrothermal temperature has an important influence on the morphology and grain size of the synthesized WO3 powder.
The photo below shows the SEM image of WO3 powder prepared at different hydrothermal temperatures. As can be seen from the picture, the reaction temperature has a significant influence on the morphology and grain size of the synthesized product. The WO3 powder synthesized at the hydrothermal temperature of 120°C (a in the figure) consists of short needle spherical particles with uniform particle size distribution, 0.8~1μm in diameter. When the hydrothermal temperature is 180°C (j in the figure), the synthesized product consists of irregularly shaped blocky particles. It means that WO3 powders with different morphologies are synthesized at different hydrothermal temperatures as the change of reaction temperature lead to the transformation of crystal forms of the synthesized product. Therefore, WO3 powders of different crystal forms have different morphologies.
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