Everything about Calcium Fluoride totally explained
| Section2 =
| Section3 =
}}
Calcium fluoride (CaF
2) is an insoluble
ionic
compound of
calcium and
fluorine. It occurs naturally as the mineral
fluorite (also called fluorspar), and it's the source of most of the world's fluorine. This insoluble solid adopts a cubic structure wherein calcium is coordinated to eight fluoride anions and each F
− ion is surrounded by four Ca
2+ ions. Although the pure material is colourless, the mineral is often deeply coloured due to the presence of
F-centers.
Source of HF
Naturally occurring CaF
2 is the principal source of
hydrogen fluoride, a commodity chemical used to produce a wide range of materials. Fluoride is liberated from the mineral by the action of concentrated
sulfuric acid:
» CaF
2(
s) + H
2SO
4(
l) →
CaSO4(solid) + 2 HF(
g)
The resulting HF is converted into fluorine,
fluorocarbons, and diverse fluoride materials. As of the late 1990s, five billion kilograms were mined annually.
Other applications
Calcium fluoride is commonly used as a window material for both
infrared and
ultraviolet wavelengths, since it's transparent in these regions (about 0.15 µm to 9 µm) and exhibits extremely weak
birefringence. Furthermore the material is fairly inert chemically so that these windows are not attacked. Nevertheless, at wavelengths as low as 157 nm, which are interesting to
semiconductor manufacturers, the birefringence of calcium fluoride exceeds tolerable limits. This problem with birefringence can be mitigated through optimised growth process. It is particularly important as an ultraviolet optical material for
integrated circuit lithography.
Canon also uses artificially-crystallized calcium fluoride components in some of its
L-series lenses to reduce
light dispersion. As an infrared optical material, calcium fluoride is sometimes known by the
Eastman Kodak trademarked name "Irtran-3," although this designation is obsolete.
Uranium-
doped calcium fluoride was the second type of
solid state laser invented, in the 1960s. Peter Sorokin and Mirek Stevenson at
IBM's laboratories in
Yorktown Heights (US) achieved lasing at 2.5 µm shortly after
Maiman's
ruby laser.
It is also used as a flux for melting and liquid processing of iron, steel and their composites. Its action is based on its similar melting point to iron, on its ability to dissolve oxides and on its ability to wet oxides and metals.
Safety
Fluorides are toxic to humans, however CaF
2 is considered relatively harmless due to its extreme insolubility. The situation is analogous to
BaSO4, where the toxicity normally associated with Ba
2+ is offset by the very low solubility of its sulfate derivative.
Further Information
Get more info on 'Calcium Fluoride'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://calcium_fluoride.totallyexplained.com">Calcium fluoride Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
