Calcium Fluoride (CaF2) is a transparent crystalline material prized for its exceptional optical transmission from the ultraviolet (UV) through the mid-infrared (IR) range. With a unique combination of low refractive index, high chemical stability, and outstanding resistance to thermal shock, CaF2 serves as a cornerstone in optical systems, lasers, and photonic applications requiring precise light control and durability under harsh environments.
Material Overview
CaF2 crystallizes in the cubic fluorite structure (space group Fm̅3m), characterized by calcium cations surrounded by eight fluorine anions in a perfectly symmetrical lattice. This highly ordered structure contributes to its wide optical transparency window, extending from approximately 130 nm in the UV to 9 µm in the IR. The material’s low refractive index (n ≈ 1.43 at 589 nm) and high laser damage threshold make it suitable for high-intensity optical components. Su et al. (2005) demonstrated that single crystals of CaF2 grown via temperature-gradient techniques exhibit exceptional optical homogeneity, with transmission efficiencies exceeding 90% in the 190–2500 nm range. In thin-film form, CaF2 acts as an antireflective coating due to its low refractive index and surface smoothness, as reported by Çetin et al. (2013). Moreover, Muniz et al. (2021) showed that incorporating CaF2 nanocrystals into silicate glass matrices enhances luminescence and refractive stability, making it ideal for photonics and laser-host applications.
Applications and Advantages
Calcium Fluoride’s broad transmission spectrum and chemical inertness make it indispensable in optical windows, lenses, prisms, and laser substrates. It is extensively used in UV lithography, spectroscopy, and infrared imaging systems. According to Hahn (2014), CaF2 remains the preferred material for deep-UV lithography lenses used in semiconductor fabrication due to its low birefringence and thermal expansion compatibility. Additionally, its low phonon energy supports its use in laser and scintillation materials where minimal nonradiative losses are required. In emerging applications, CaF2-based composites and coatings are being explored for radiation-resistant optics and energy-efficient photonic devices, offering durability, clarity, and cost-effectiveness.
Goodfellow Availability
Goodfellow offers high-purity Calcium Fluoride (CaF2) suitable for optical, electronic, and structural applications. Available in single-crystal and polycrystalline forms, CaF2 can be customized for wavelength-specific transmission, substrate preparation, and photonic integration needs.
Explore Calcium Fluoride CaF2 – Material Information and other advanced materials in Goodfellow’s online catalogue: Goodfellow product finder.
References
- Su, L., Dong, Y., Yang, W., Sun, T., Wang, Q., Xu, J., & Zhao, G. (2005). Growth, characterization and optical quality of CaF2 single crystals grown by the temperature gradient technique. Materials Research Bulletin, 40(5), 761–767. https://doi.org/10.1016/j.materresbull.2005.01.006
- Çetin, N. E., Korkmaz, Ş., Elmas, S., Ekem, N., Pat, S., Balbağ, M. Z., Tarhan, E., Temel, S., & Özmumcu, M. (2013). The structural, optical and morphological properties of CaF2 thin films by using Thermionic Vacuum Arc (TVA). Materials Letters, 93, 356–359. https://doi.org/10.1016/j.matlet.2012.07.086
- Muniz, R. F., Soares, V. O., Montagnini, G. H., Medina, A. N., & Baesso, M. L. (2021). Thermal, optical and structural properties of sodium calcium silicate glass and glass-ceramic containing CaF2. Ceramics International, 47(17), 24821–24831. https://doi.org/10.1016/j.ceramint.2021.05.224
- Hahn, D. (2014). Calcium fluoride and barium fluoride crystals in optics. Optik & Photonik, 9(4), 38–41. https://doi.org/10.1002/OPPH.201400066