Aluminium fluoride
Other names	Aluminium(III) fluoride Aluminum trifluoride
Identifiers
CAS number	7784-18-1 Y, 32287-65-3 (monohydrate) 15098-87-0 (trihydrate)
PubChem	2124
RTECS number	BD0725000
Properties
Molecular formula	AlF3
Molar mass	83.9767 g/mol (anhydrous) 101.022 g/mol (monohydrate) 138.023 (trihydrate)
Appearance	white, crystalline solid odorless
Density	2.88 g/cm (anhydrous) 2.1 g/cm3 (monohydrate) 1.914 g/cm3 (trihydrate)
Melting point	1291 °C (anhydrous)
Solubility in water	0.56 g/100 mL (0 °C) 0.67 g/100 mL (20 °C) 1.72 g/100 mL (100 °C)
Structure
Crystal structure	Rhombohedral, hR24
Space group	R-3c, No. 167
Hazards
EU classification	Harmful (Xn)[1]
R-phrases	R22, R36/37/38[1]
S-phrases	S26[1]
NFPA 704	0 2 0
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Aluminium fluoride is the inorganic compound with the formula AlF₃. This colourless solid can be prepared synthetically but also occurs in nature. It is produced on a substantial scale as a component in the production of aluminium.

Contents 1 Production and occurrence 2 Structure 3 Applications 4 References 5 External links

[edit] Production and occurrence

The majority of aluminium fluoride is produced by heating hexafluorosilicic acid in nitrogen:^[2]

H₂SiF₆ + Al₂O₃ → 2 AlF₃ + SiO₂ + H₂O

In the laboratory, AlF₃ can be prepared by treating aluminium hydroxide or aluminium metal with HF. Aluminium fluoride trihydrate is found in nature as the rare mineral rosenbergite.

[edit] Structure

Its structure resembles that of rhenium trioxide, ReO₃, consisting of distorted AlF₆ octahedra. Each fluoride is connected to two Al centers. The structure helps explain why AlF₃ is refractory, in strong contrast to the other halides of aluminium.^[3] 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.

[edit] Applications

Aluminium fluoride is an important additive that allows the production of aluminium by electrolysis. It lowers the melting point of the alumina feed and, together with cryolite, increases the electrolyte's conductivity of the solution.^[2] Together with zirconium fluoride, aluminium fluoride is the basis of fluoroaluminate glasses.

It is also used in ceramics as flux in metallurgy and to inhibit fermentation, and as an evaporation material and sputtering target for preparation of low index films. Should be made into color parts of the atom.

[edit] References

1. ^ ^{a b c} BGIA GESTIS (English version)
2. ^ ^{a b} J. Aigueperse, P. Mollard, D. Devilliers, M. Chemla, R. Faron, R. Romano, J. P. Cuer, “Fluorine Compounds, Inorganic” in Ullmann’s Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005
3. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.

[edit] External links

• MSDS

v • d • e   Aluminium compounds AlAs · AlB2 · AlB12 · AlBr3 · AlCl · AlCl3 · AlF · AlF3 · AlH3 · AlI3 · AlN · Al(NO3)3 · AlO · Al(OH)3 · AlON · AlP · AlPO4 · AlSb · Al2(MoO4)3 · Al2O3 · Al2S3 · Al2(SO4)3 · Al2Se3 · Al2SiO5 · Al4C3