Calcium fluoride

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</table> Calcium fluoride (CaF2) is an insoluble ioniccompound of calcium and fluorine. It occurs naturally as the mineral fluorite (also called fluorspar), and it is the source of most of the world's fluorine. It reacts with concentrated sulfuric acid to produce hydrogen fluoride: CaF2(s) + H2SO4(l) → CaSO4(s) + 2 HF(g) Calcium fluoride is commonly used as a window material for both infrared and ultraviolet wavelengths, since it is transparent in these regions and exhibits extremely weak birefringence. Nevertheless, at wavelengths as low as 157 nm, which are interesting to semiconductor manufacturers, the birefringence of calcium fluoride exceeds tolerable limits. This may be overcome by minimizing birefringence by optmimizing the growth process. It is particularly important as an ultraviolet optical material for integrated circuitlithography. Canon also uses artificially crystallized calcium fluoride elements in some of its L series lenses to reduce light dispersion.
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Image:Calcium fluoride.jpg

General

Name Calcium fluoride
Chemical formula CaF2
Solid state strucutre (note that this is the same as uranium dioxide) Image:UO2lattice.jpg
SMILES [F-].[F-].[Ca+2]
CAS registry number 7789-75-5</sub>
Appearance White (or colored by impurities) crystalline solid.

Physical properties

Formula weight 78.07 amu
Melting point 1675 K (1402 °C)
Boiling point 2770 K (2500 °C)
Density 3.18 ×103 kg/m3 (solid)
Solubility virtually none in water

SI units were used where possible. Unless otherwise stated, standard conditions were used.

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