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| Names | |
|---|---|
| Other names Sellaite Irtran-1 | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.029.086 |
| EC Number |
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| RTECS number |
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| UNII | |
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| Properties | |
| MgF2 | |
| Molar mass | 62.3018 g/mol |
| Appearance | Colorless to whitetetragonal crystals |
| Density | 3.148 g/cm3 |
| Melting point | 1,263 °C (2,305 °F; 1,536 K) |
| Boiling point | 2,260 °C (4,100 °F; 2,530 K) |
| 0.013 g/(100 mL) | |
Solubility product (Ksp) | 5.16⋅10−11 |
| Solubility |
|
| −22.7⋅10−6 cm3/mol | |
Refractive index (nD) | 1.37397 |
| Structure | |
| Rutile (tetragonal),tP6 | |
| P42/mnm, No. 136 | |
| Thermochemistry | |
| 61.6 J/(mol⋅K) | |
Std molar entropy(S⦵298) | 57.2 J/(mol⋅K) |
Std enthalpy of formation(ΔfH⦵298) | −1124.2 kJ/mol |
Gibbs free energy(ΔfG⦵) | −1071 kJ/mol |
| Hazards[2][3] | |
| GHS labelling: | |
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| Warning | |
| H303,H315,H319,H335 | |
| P261,P304+P340,P305+P351+P338,P405 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 2330[clarification needed] (rat, oral) |
| Safety data sheet (SDS) | ChemicalBook |
| Related compounds | |
Otheranions | |
Othercations | |
Related compounds | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Magnesium fluoride is an ionically bondedinorganic compound with theformulaMgF2. The compound is a colorless to white crystallinesalt that is transparent over a wide range ofwavelengths, such that it is used in the optical windows ofspace telescopes. It occurs naturally as the rare mineralsellaite.
Magnesiumfluoride is prepared frommagnesium oxide with sources ofhydrogen fluoride such asammonium bifluoride, by the breakdown of it:
Relatedmetathesis reactions are also feasible:
The compound crystallizes astetragonalbirefringent crystals. The structure of the magnesium fluoride is similar to that ofrutile,[4][5] featuringoctahedralMg2+cations and 3-coordinateF−anions.[6]
| Magnesium coordination | Fluorine coordination |
|---|---|
 |  |
In the gas phase,monomericMgF2 molecules adopt alinear molecular geometry.[4][5]
Magnesium fluoride istransparent over an extremely wide range ofwavelengths. Windows,lenses, andprisms made of this material can be used over the entire range of wavelengths from 0.120 μm (vacuum ultraviolet) to 8.0 μm (infrared). High-quality, synthetic magnesium fluoride is one of two materials (the other beinglithium fluoride) that will transmit in the vacuum ultraviolet range at 121 nm (Lyman alpha).
Magnesium fluoride is tough and polishes well but is slightlybirefringent and should therefore be cut with theoptic axis perpendicular to the plane of the window or lens.[6] Due to its suitablerefractive index of 1.37, magnesium fluoride is commonly applied in thin layers to the surfaces of optical elements as an inexpensiveanti-reflective coating.[citation needed] ItsVerdet constant is 0.00810 arcmin⋅G−1⋅cm−1 at 632.8 nm.[8]
Chronic exposure to magnesium fluoride may affect the skeleton, kidneys, central nervous system, respiratory system, eyes and skin, and may cause or aggravate attacks of asthma.[9]
