Why Violet Tungsten Oxide is Violet?

As the name implies, violet tungsten oxide refers to a kind of tungsten oxide with a violet color. It is one of the stable oxides of tungsten, together with WO₃, WO_2.90 and WO₂. Why violet tungsten oxide is violet. It is closely related to its light absorption property.

Seven different colors of light - red, orange, yellow, green, indigo, blue and purple - constitute visible light. And the light of each color has its unique wavelength. Red light is the light with the longest wavelength and purple light is the light with the shortest wavelength. As for light absorption property of matter, matter is selective in light absorption. When light of different wavelengths is absorbed or reflected, matter will show different colors. Therefore, oxide of tungsten has various colors and violet is one of them.

If all the components of white light are absorbed without reemission, oxide of tungsten will be black; If oxide of tungsten has low reflectivity at the short wavelength end (460-480 nm), as only green and yellow light are reflected, it will be of a yellow to orange color; if oxide of tungsten has low reflectivity at the long wavelength end (550-700 nm), it will be blue or purple. And this explains why violet tungsten oxide is violet.

If all the components of white light are absorbed without reemission, oxide of tungsten will be black; If oxide of tungsten has low reflectivity at the short wavelength end (460-480 nm), as only green and yellow light are reflected, it will be of a yellow to orange color; if oxide of tungsten has low reflectivity at the long wavelength end (550-700 nm), it will be blue or purple. And this explains why violet tungsten oxide is violet.

Generally, the color of violet tungsten oxide powder is different from that of violet tungsten oxide single crystal. Violet tungsten oxide is of a dark purple to pure purple color.

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