Ammonium paratungstate hydrate is an intermediate for the production of tungsten metal, tungsten-containing catalysts, tungsten-based hard materials (such as tungsten carbide) or sputtering targets. The preparation is carried out mainly by digesting or melting a slag containing tungsten concentrate or tungsten with acid or base, followed by purification, and the purification stage includes a precipitation process and a liquid-liquid extraction. The purified solution is usually concentrated by evaporation to finally crystallize the ammonium paratungstate hydrate.

Tungsten is a very important non-ferrous metal. It has the properties of high density and high hardness. It is commonly used in counterweight materials, shielding materials and military materials. Tungsten-zirconium alloy has a broad application prospect in the military field due to its strong resistance to corrosion.

In recent years, research on tungsten trioxide (WO3) nanofilm has attracted more and more attention. WO3 is an n-type semiconductor material with a narrow band gap (2.4-2.8eV), is capable of responding to visible light, and has similar characteristics to TiO2 photocatalyst, namely stable, non-toxic, photo-resistant, low-cost and low-priced. The potential of the belt is high and the photo-generated holes are highly oxidizing.

Heterojunctions have become an essential element of the modern semiconductor industry, and they play an important role in high-speed electronic devices and optoelectronic devices. Two-dimensional layered materials, including graphene and transition metal disulfide, can serve as a constituent unit of a heterostructure due to their unique electrical and optical properties.