Tungsten oxide has good physical and chemical properties, so it can be widely applied in many different fields. The fine tungsten oxide has strong absorption capacity on electromagnetic wave, so it can be used as perfect absorbing material in solar system applications and important invisible material in military field. Also it has good catalytic property, so it can be used as catalytic materials in the anode electrode of fuel cells. It can also be applied as low temperature superconducting materials. After mixed with TiO2, it can be used as photocatalyst.Tungsten oxide is unstable with NOX, H2S and NH, thus it is used as sensitive material for tranducer and test food, pharmaceuticals, off-gas. Besides that, it is also used to produce chemical products, such as oil paint, coating, oil industry catalyst, etc.
Tungsten Oxide Species
Tungsten oxide, in W - O lines, there are tungsten oxide like WO3, WO 2.9, WO 2.72, WO2. WO3 (yellow) - WO 2.90 (blue) - WO 2.72 (violet) - WO2 (brown) - W (gray). That is, there are four stable tungsten oxide: yellow tungsten oxide (WO3), blue tungsten oxide (WO2.90), violet tungsten oxide (WO2.72) and brown tungsten oxide (WO2).
Tungsten Oxide Thin Film
Tungsten oxide thin film is the most distinctive ion sensitive color material, it has ReO structure. This crystal structure is actually the ABO3 type perovskite structure vacant cation sites A and B bits into W6 +. When there is a positive ion source, the electric field is applied to cause the positive ions M and electron diffusion and migration of WO3 films.When a negative voltage is applied on WO, positive ions are implanted WO3 films, occupy one of the "A" position to form a tungsten bronze MxWO3. When the voltage is reversed, implanting ions extracted from the WO3 film.
Tungsten Oxide Formation
The crystal structure of tungsten oxide is temperature dependent. It is tetragonal at temperatures above 740 °C, orthorhombic from 330 to 740 °C, monoclinic from 17 to 330 °C, and triclinic from -50 to 17 °C. The most common structure of WO3 is monoclinic with space group P21/n.