Magnesium Fluoride MgF2 - Material Information

Magnesium fluoride (MgF₂) stands as one of the most important optical materials in modern photonics, distinguished by its exceptionally low refractive index, wide transparency from far-ultraviolet to mid-infrared, and excellent chemical stability. This versatile fluoride serves critical roles in antireflection coatings, deep-UV optical systems, multilayer mirrors, and protective coatings from semiconductor lithography to space instrumentation.

Material Overview

MgF₂ crystallizes in a tetragonal rutile-type structure, forming a positive uniaxial crystal with notable UV birefringence [1]. The material exhibits extraordinary optical transparency spanning approximately 120 nm to 8 μm [1]. Thin films deposited by atomic layer deposition, ion beam sputtering, reactive magnetron sputtering, and sol-gel processing demonstrate refractive indices from 1.34 to 1.42 at visible wavelengths [2][3][4]. High-quality films exhibit near-zero optical absorption, with representative values of n ≈ 1.37 at 550 nm [5][6]. The ultralow refractive index combined with durability and wide spectral transparency makes MgF₂ indispensable for precision optical systems.

Applications and Advantages

MgF₂ thin films are standard for antireflection coatings in deep-UV lithography systems at 193 nm and 248 nm, achieving exceptionally low scatter and high laser-induced damage thresholds [7]. In far-ultraviolet applications, MgF₂ serves as the low-index component in multilayer mirrors for wavelengths down to 121–130 nm [1]. Sol-gel nanoparticle coatings offer ultralow effective refractive indices through controlled porosity, enabling reflectance below 0.6% at 193 nm [8]. Reactive magnetron sputtering produces nanocrystalline films with excellent visible-to-infrared transparency for commercial antireflection on camera lenses, solar cells, and displays [6][9]. ALD-deposited MgF₂ provides conformal coverage and precise thickness control at low temperatures [3].

Goodfellow Availability

Goodfellow supplies high-purity magnesium fluoride in various forms suitable for optical applications, thin-film deposition, and research. Custom dimensions are available to meet precise requirements of advanced optical systems.

Explore MgF₂ and other advanced materials in Goodfellow's online catalogue: Goodfellow product finder.

References

• [1] Rodríguez-de Marcos, L. V., Larruquert, J. I., Méndez, J. A., et al. (2017). Self-consistent optical constants of MgF₂, LaF₃, and CeF₃ films. Optical Materials Express, 7(3), 989. https://doi.org/10.1364/OME.7.000989
• [2] Pilvi, T., Hatanpää, T., Puukilainen, E., et al. (2007). Study of a novel ALD process for depositing MgF₂ thin films. Journal of Materials Chemistry. https://doi.org/10.1039/B710903B
• [3] Pilvi, T., Puukilainen, E., Kreissig, U., et al. (2008). Atomic layer deposition of MgF₂ thin films using TaF₅ as a novel fluorine source. Chemistry of Materials. https://doi.org/10.1021/CM800948K
• [4] Murata, T., Ishizawa, H., & Tanaka, A. (2008). Investigation of MgF₂ optical thin films with ultralow refractive indices. Applied Optics, 47(13), C246. https://doi.org/10.1364/AO.47.00C246
• [5] Lien, S.-Y., Xiao, L., Zhang, Z.-X., et al. (2025). Temperature-dependent growth mechanisms and optical properties of MgF₂ thin films. Chemistry. https://doi.org/10.3390/chemistry7050147
• [6] Mertin, S., Marot, L., Sandu, C. S., et al. (2015). Nanocrystalline low-refractive magnesium fluoride films deposited by reactive magnetron sputtering. Advanced Engineering Materials. https://doi.org/10.1002/ADEM.201500129
• [7] Ristau, D., Arens, W., Bosch, S., et al. (1999). UV-optical and microstructural properties of MgF₂-coatings deposited by IBS and PVD. https://doi.org/10.1117/12.360111
• [8] Murata, T., Ishizawa, H., Motoyama, I., et al. (2004). Investigations of MgF₂ optical thin films prepared from autoclaved sol. Journal of Sol-Gel Science and Technology. https://doi.org/10.1007/S10971-004-5782-8
• [9] Song, B.-K., Jung, J.-Y., Cho, Y.-R., et al. (2020). Synthesis of MgF₂ nanoparticles for improved anti-reflective coating. Korean Journal of Metals and Materials, 58(3), 201. https://doi.org/10.3365/KJMM.2020.58.3.201