Aluminium fluoride, with the chemical formula AlF3, is a chemical compound composed of aluminium (Al) and fluorine (F). It is an ionic compound and belongs to the family of metal halides.

Aluminium fluoride is typically encountered as a white crystalline solid that is highly hygroscopic, meaning it readily absorbs moisture from the air.

Some key properties and uses of aluminium fluoride include:

1. Aluminium Smelting: Aluminium fluoride is a crucial component in the production of aluminium metal. It is used as a flux in the aluminum smelting process to lower the melting point of alumina (aluminium oxide) and improve the efficiency of electrolysis.
2. Glass and Ceramic Industry: Aluminium fluoride is used in the glass and ceramic industry as a fluxing agent to reduce the melting point of glass or ceramic materials and improve their workability.
3. Chemical Industry: Aluminium fluoride is employed in various chemical reactions and processes as a catalyst or to enhance specific reactions.
4. Optical Coatings: Aluminium fluoride coatings are used in some optical applications due to their low refractive index.
5. Insecticides: Aluminium fluoride is used in certain insecticides.

As with other metal halides, aluminium fluoride requires careful handling and storage to prevent exposure to moisture, which can cause it to degrade or react unpredictably.

Aluminium fluoride plays a critical role in the production of aluminium metal and has various industrial applications. Its properties as a flux and catalyst make it valuable in the glass, ceramic, and chemical industries. Moreover, its use in optical coatings and insecticides highlights its versatility in different fields of application.