Fluorophosphate glass

Fluorophosphate glass is a class of optical glasses composed of metaphosphates and fluorides of various metals. It is a variant of phosphate glasses. Fluorophosphate glasses are very unusual in nature. Fluorophosphate glasses have ultra-low theoretical loss of 0.001 dB/km, longer fluorescent lifetime of rare earths, lower coefficient of thermal expansion of ~13×10−6/°C.[1]

Some fluorophosphate glasses are used as low dispersion glasses. Some show anomalous partial dispersion.[2] One such glass is composed of Ba(PO3)2, Al(PO3)3, AlF3, and alkaline earth fluorides MgF2, CaF2, SrF2, and BaF2, with possible addition of titanium, sodium, potassium, and/or hydrogen. The components by wt.% are 0.5–3% Mg, 8–10% Ca, 12–20% Sr, 9–12% Ba, 7–9% Al, 5–9% P, 8–12% O, and 35–38% F.[3]

Some doped fluorophosphate glasses are used in laser technology. They are attractive here for their small refractive index nonlinearity.[4] Rare-earth elements are popular dopants. One of the applications is for optical amplifiers.

Exotic dopants like fullerenes[5] and quantum dots can be employed.

Tungsten-doped tin-fluorophosphate glasses (SnO-SnF2-P2O5) can be used for hermetic sealing of organic light-emitting diodes and other devices.[6]

See also

References
  1. Stokowski, S. E; Martin, W. E; Yarema, S. M (1 July 1980). "Optical and lasing properties of fluorophosphate glass". Journal of Non-Crystalline Solids. 40 (1): 481–487. Bibcode:1980JNCS...40..481S. doi:10.1016/0022-3093(80)90123-4.
  2. US 4859635, "Optical fluorophosphate glass having anomalous positive partial dispersion and process for its production"
  3. US 4857487, "Optical fluorophosphate glasses possessing positive anomalous partial dispersion and improved physico-chemical properties, and a process for their preparation"
  4. Balda, R.; Fernández, J.; De Pablos, A. (April 1994). "Optical properties of Nd 3+ ions in fluorophosphate glasses" (PDF). Le Journal de Physique IV. 04 (C4): C4–509–C4-512. doi:10.1051/jp4:19944122.
  5. Lin, Fucheng; Mao, Sen; Meng, Zhicong; Zeng, Heping; Qiu, Jianqing; Yue, Yong; Guo, Ting (14 November 1994). "Fullerene doped glasses". Applied Physics Letters. 65 (20): 2522–2524. Bibcode:1994ApPhL..65.2522L. doi:10.1063/1.112623.
  6. WO 2008045249, "Durable Tungsten-Doped Tin-Fluorophosphate Glasses"


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