Tungsten oxide nanoparticles for window heat insulation film can be prepared by a solvothermal method. Some experts have adopted this method to prepare tungsten oxide at different temperatures (160°C, 180°C, 200°C) using isopropanol as the alcohol solvent. Wherein, the molar concentration of the solution is 25mM, the reaction time is 12h. And the effect of reaction temperature on the morphology of the product was observed. A SEM photograph of the obtained tungsten oxide is shown below, wherein a) is at 160°C, b) is at 180°C, and c) is at 200°C.
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It can be seen from the figure that under the conditions of fixed molar concentration of the solution and the reaction time, when the reaction temperature is 160°C, the synthesized nanoparticles are linked to each other to form a block-like area without obvious morphology. Nanoparticle bulges can also be seen on the surface of this area, but the diameter of the nanoparticles is very different and the morphology is not spherical. When the reaction temperature is 180°C, the generated tungsten oxide nano particles show a distinct spherical shape. These particles become tungsten oxide nanospheres with a particle size of about 1m, of good uniformity and less surface protrusion. When the reaction temperature is increased to 200°C, the uniformity of particle size of tungsten oxide nanospheres decreases, and some of the nanospheres grow and join each other, making the spherical morphology less obvious.
