Aluminium fluoride

Aluminium fluoride is the inorganic compound with the formula AlF₃. It can be prepared by treating aluminium hydroxide or aluminium metal with HF. As a solid, its structure resembles that of rhenium trioxide, ReO₃, consisting of distorted AlF₆ octahedra.

AlF₃ is refractory, in strong contrast to the other halides of aluminium. AlCl₃, AlBr₃, and AlI₃ are dimeric in the liquid and evaporate as dimers as well. In the gas phase, at ca. 1000 °C, aluminium fluoride exists as trigonal molecules of D_3h symmetry group. The Al-F bond lengths are 163 pm.

Aluminum fluoride in the gas phase at 1000°CAluminum fluoride in the gas phase at 1000°C

Aluminium fluoride is an important additive during electrolyte aluminium production because it lowers the melting point of the alumina feed and increases the electrolyte's conductivity.

External Information

Aluminum Fluoride