MgF2
Magnesium fluoride · Sellaite
Magnesium fluoride is a transparent, stable insulating compound primarily used for its excellent optical properties in lens coatings and specialized glass components.

About Magnesium fluoride
Magnesium fluoride is a thermodynamically stable inorganic compound that serves as a critical material in optical engineering. Its wide-gap insulating nature allows it to remain transparent across a broad range of the electromagnetic spectrum, making it an essential component for high-precision optical systems.
Due to its robust stability and favorable physical properties, it is frequently utilized in the production of thin-film coatings. These coatings are vital for reducing reflection and enhancing the performance of lenses and windows in demanding environments.
Key Properties
Cross-validated computational properties for Magnesium fluoride, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Reported Structures
Lowest-energy structures reported for MgF2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| P42/mnm (No. 136) | tetragonal | 6.82 | 0.0000 | -7.298 | 3.19 |
| Pnnm (No. 58) | orthorhombic | 6.85 | 0.0025 | -7.295 | 3.04 |
| Pa-3 (No. 205) | cubic | 6.72 | 0.0661 | -7.232 | 3.29 |
| Imma (No. 74) | orthorhombic | 6.47 | 0.1002 | -7.198 | 1.87 |
| C2/m (No. 12) | monoclinic | 6.38 | 0.1076 | -7.190 | 1.91 |
| Pnma (No. 62) | orthorhombic | 0.00 | 0.2070 | -7.091 | 3.43 |
| Amm2 (No. 38) | orthorhombic | 0.00 | 0.2636 | -7.034 | 3.22 |
| P-1 (No. 2) | Triclinic | — | — | — | 1.86 |
| I4/mmm (No. 139) | Tetragonal | — | — | — | 3.73 |
| Cm (No. 8) | Monoclinic | — | — | — | 4.18 |
| C2/m (No. 12) | — | — | — | — | — |
| Pa-3 (No. 205) | — | — | — | — | — |
Applications
Where Magnesium fluoride is used.
Frequently Asked Questions
Common questions about Magnesium fluoride, answered from cross-validated data.
What is MgF2?
Magnesium fluoride is a transparent, stable insulating compound primarily used for its excellent optical properties in lens coatings and specialized glass components.
What is MgF2 used for?
What is the band gap of MgF2?
Is MgF2 a metal, semiconductor, or insulator?
Is MgF2 thermodynamically stable?
What is the crystal structure of MgF2?
What is the density of MgF2?
How many polymorphs of MgF2 are known?
What elements does MgF2 contain?
Where does the data for MgF2 come from?
How It Compares
As a highly stable and well-characterized material, magnesium fluoride stands as a foundational reference point for fluoride-based insulators, representing a standard of reliability in optical and structural applications.
Data sources & attribution
- materials_project — Data from the Materials Project. Cite: Jain et al., APL Materials 1, 011002 (2013).
- mpaloe — Data from mpaloe.
- jarvis — Data from JARVIS (NIST). Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020).
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