Magnesium fluoride

Sellaite

Colorless odorless tetragonal crystals

Fixed

3.13 g · cm -3

1256 ° C

2260 ° C

Poor ( 0.13 g · l-1 ) in water

Attention

1 mg · m-3

Template: Infobox chemical / molecular formula search available

Magnesium fluoride is a chemical compound made ​​of magnesium and fluorine. It is one of the salts and is present as a white powder or as a colorless crystal.

Occurrence

Magnesium fluoride was delineated as a mineral first time in 1868 by the Italian mining engineer Quintino Sella ( 1827-1884 ). According to him, it bears the name sellaite. The natural resources have no economic significance.

Production and representation

In contrast to magnesium fluoride magnesium chloride is readily soluble in water. The simplest and most economical way of manufacturing the fluoride therefore precipitating it from a solution of magnesium chloride with hydrofluoric acid.

Moreover, magnesium fluoride, can also be obtained by dissolving magnesium metal or magnesium in hydrofluoric acid, or directly from the elements of magnesium and fluorine, the latter reaction is strongly exothermic.

Properties

Magnesium fluoride is colorless and odorless, incombustible crystals which crystallize in the tetragonal rutile structure of. The Mohs hardness is 6 The standard enthalpy of formation is -1124 kJ / mol. Chemically, MgF2 very stable and is only attacked by hot sulfuric acid.

Magnesium fluoride has some optical properties that make it interesting for technical applications. So it is transparent in an exceptionally wide range of wavelengths. This range is from about 120 nm (VUV ) radiation, up to about 8.0 microns ( infrared). Furthermore, it has in the visible region of the spectrum relatively low refractive indices of about 1.38. MgF2 further shows a positive birefringence.

Use

The optical properties of magnesium fluoride to make it together with its chemical stability, a major material for optical applications. It is suitable because of the low refractive index for the production of anti -reflective coatings, thus to antireflective lenses by, for example, or photo lenses. Because of the well into the UV range reaching MgF2 transmission is also used for the sealing of aluminized mirrors that work in this area. As a single crystal of magnesium fluoride is used for optical windows that require a wide range of transparency.

And outside of the optical industry, there are a number of applications, including as an additive to ceramics, and as catalysts in the chemical industry, in metallurgy as welding means for light metals, as a carrier for catalysts and for increasing the resistance and gas resistance of moldings made from alumina.

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