Tungsten trioxide powder, as an important transparent thermal insulation nanopowder, has excellent optical properties, and therefore it has a wide application in thermal insulation materials such as building glass and auto glass.
The color and optical properties of tungsten trioxide are closely related to its electronic structure. And it is the complex electronic structure of tungsten trioxide that makes the color of tungsten trioxide diverse. The color of the material changes from light yellow to light green when some W6+ are reduced to W5+ due to the presence of oxygen vacancies.
If the tungsten trioxide was irradiated with XeCl pulsed excimer laser, its color was changed from yellow to blue. Then, the irradiated tungsten trioxide was analyzed by X-ray photoelectron spectroscopy (XPS) to find that conducting electrons and partial reduction occurred in the tungsten trioxide material. In a word, the change of color of tungsten trioxide can be attributed to the change in the electronic structure accompanying the valence change.
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