Transparent ceramics

Transparent spinel (MgAl2O4) ceramic is used traditionally for applications such as high-energy laser windows because of its excellent transmission in visible wavelengths and mid-wavelength infrared (0.2–5.0 μm) when combined with selected materials – source: U.S. Naval Research Laboratory[citation needed]

Many ceramic materials, both glassy and crystalline, have found use as optically transparent materials in various forms from bulk solid-state components to high surface area forms such as thin films, coatings, and fibers.[1] Such devices have found widespread use for various applications in the electro-optical field including: optical fibers for guided lightwave transmission, optical switches, laser amplifiers and lenses, hosts for solid-state lasers and optical window materials for gas lasers, and infrared (IR) heat seeking devices for missile guidance systems and IR night vision.[2] In commercial and general knowledge domains, it is commonly accepted that transparent ceramics or ceramic glass are varieties of strengthened glass, such as those used for the screen glass on an iPhone.[3]

While single-crystalline ceramics may be largely defect-free (particularly within the spatial scale of the incident light wave), optical transparency in polycrystalline materials is limited by the amount of light that is scattered by their microstructural features. The amount of light scattering therefore depends on the wavelength of the incident radiation, or light.[4]

For example, since visible light has a wavelength scale on the order of hundreds of nanometers, scattering centers will have dimensions on a similar spatial scale. Most ceramic materials, such as alumina and its compounds, are formed from fine powders, yielding a fine grained polycrystalline microstructure that is filled with scattering centers comparable to the wavelength of visible light. Thus, they are generally opaque as opposed to transparent materials. Recent nanoscale technology, however, has made possible the production of (poly)crystalline transparent ceramics such as alumina Al2O3, yttrium aluminium garnet (YAG), and neodymium-doped Nd:YAG.[5][6][7][8][9][10]

  1. ^ Patel, P.J., et al., (2000) "Transparent ceramics for armor and EM window applications", Proc. SPIE, Vol. 4102, p. 1, Inorganic Optical Materials II, Marker, A.J. and Arthurs, E.G., Eds.
  2. ^ Harris, D.C. (2009) "Materials for Infrared Windows and Domes: Properties and Performance", SPIE PRESS Monograph, Vol. PM70 (Int. Society of Optical Engineers, Bellingham WA)
  3. ^ "IPhone 15 Pro and iPhone 15 Pro Max".
  4. ^ Belyakov, A.V., "Production of Transparent Ceramics (Review)", Science for Ceramics Manufacture, Glass and Ceramics, Vol. 52, p. 14 (1995)
  5. ^ Ikesue, A.; Kinoshita, Toshiyuki; Kamata, Kiichiro; Yoshida, Kunio; et al. (1995). "Fabrication and Optical Properties of High-Performance Polycrystalline Nd:YAG Ceramics for Solid-State Lasers". Journal of the American Ceramic Society. 78 (4): 1033. doi:10.1111/j.1151-2916.1995.tb08433.x.
  6. ^ Ikesue, A (2002). "Polycrystalline Nd:YAG ceramics lasers". Optical Materials. 19 (1): 183. Bibcode:2002OptMa..19..183I. doi:10.1016/S0925-3467(01)00217-8.
  7. ^ Tachiwaki, T., et al., Novel synthesis of YAG leading to transparent ceramics", Solid State Communications, Vol. 119, p. 603 (2001)
  8. ^ Lu, J., et al., "Neodymium doped YAG nanocrystalline ceramics – a new generation of solid state laser and optical materials", J. All. Comp., Vol. 341, p. 220 (2002)
  9. ^ Bison, J.F., et al., "Nanotechnology is stirring up solid-state laser fabrication technology", Recent Res. Devel. Applied Physics, Vol. 7, p. 475 (2004)
  10. ^ Huie, J.C. and Gentilman, R., "Characterization of transparent polycrystalline YAG fabricated from nanopowders", Proc. SPIE, Vol. 5786, p. 251 (Tustison, R.W., Ed., Window and Dome Technology and Materials IX, 2005)