Calcium Fluoride (CaF2)
1998; Elsevier BV; Linguagem: Inglês
10.1016/b978-0-08-055630-7.50051-1
Autores Tópico(s)Ga2O3 and related materials
ResumoThis chapter describes calcium fluoride (CaF2) as a compound whose X-ray diffraction analysis has shown it to belong to the cubic fluorite structure. The Ca2+ ions are arranged in a face-centered cubic lattice and the F– ions in a cubic lattice. Each fluorine ion is surrounded by four calcium ions and each calcium ion by eight fluorine ions. Based on symmetry considerations, CaF2 is classified under the space group Fm3m. High-purity, synthetic CaF2 material is readily available in cylindrical form up to 200 mm in diameter. Both mechanical and thermal shock are avoided during optical processing of CaF2 because of its physical properties. The wide transmission band of CaF2 leads to a multitude of applications. These applications range from dispersive elements in infrared monochromators, filters for reducing stray light and radiation-blocking elements, to lenses and windows. Laser-induced desorption treatment leads to passivated CaF2 surfaces that are highly resistant to water adsorption at room temperature. CaF2, which is a highly ionic compound, has a wide band gap. The edge of the fundamental absorption band lies in the vacuum ultraviolet at about 12 eV.
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