Violet tungsten oxide is powder with unique color between dark purple and pure purple. It is generally prepared by calcining ammonium paratungstate in a rotary furnace. The color of violet tungsten oxide differs from different preparation methods.

Among the many vanadium oxides, vanadium dioxide is different because of its rapid and sudden phase transition. Its phase transition temperature is 68 ℃, which can change reversibly from low temperature monoclinic system to high temperature tetragonal system, making its physical properties such as resistivity, optical transmittance and magnetic conductivity change greatly. This characteristic makes it have a great prospect in intelligent switch, electronic device and photoelectric equipment. The results show that tungsten can effectively reduce the phase transition temperature of vanadium dioxide, and copper can improve the conductivity of vanadium dioxide.

In order to extract tungsten from tungsten minerals, at present, China's tungsten metallurgy industry mostly adopts the alkaline smelting system. After high-pressure leaching of sodium tungstate solution, ion exchange is carried out and apt is extracted by evaporation crystallization. At present, there are two outstanding problems in this process that have not been effectively solved: first, the waste water discharge is large. Second, the discharge of waste salt is large.

Silica bismuth is a typical semiconductor material. Through the action of light, electrons are excited by light to transition and leave corresponding holes, forming electron hole pairs. These photo generated electron hole pairs have strong redox ability and are easy to react with organics and polymers. Due to the narrow band gap, they respond well to visible light;