There is an increasing demand of optics applications for thermal imaging in the wavelength range of 8-12 micro-m, for example for low-light driving conditions. The material is a glass or glass ceramic based on the GeSe2-Ga2Se3-CsCI system. This material is transparent from the visible to the far-IR (15 micro-m); all known selenide glasses are black and do not exhibit any transmission in the visible spectral region. The glass ceramic also has improved mechanical properties because of the presence of Ga2Se3 nano-crystals, which do not induce significant optical losses through diffusion. Finally, this material is compatible with high-precision molding. Chlorine atoms from the CsCI play a key role by fixing the lone pair of electrons on the Se atom, affording a considerably increased electronic bandgap. This purely ionic compound, CsCI, is also indispens-able for controlling nucleation and crystal growth to generate transparent glass ceramics. Because of its transparency in the IR and visible regions, improved mechanical properties, and potential use in low-production-cost optics, the GeSe2-Ga2Se3-CsCI system could have a considerable competitive advantage over currently used IR materials. Two ideas prompted the selection of the GeSe2-Ga2Se3-CsCI system. The first thought was to introduce a maximum number of nonbridging electronegative Cl atoms into the Se network in order to drain and localize the lone pair of electrons on the Se atoms, which are responsible for the black color typically exhibited by the Se-based glasses.
Selenium-based glasses and glass ceramics transmitting light from the visible to the far-IR
Advanced Materials, Weinheim ; 19 , 1 ; 129-132
2007
4 Seiten, 3 Bilder, 1 Tabelle, 9 Quellen
Aufsatz (Zeitschrift)
Englisch
Bildwandler , Cäsiumchlorid , Galliumselenid , Germaniumverbindung , Infrarotdetektor , Infrarotdurchlässigkeit , Nachtsehen , Nachtsichtgerät , optische Absorption , optische Transmission , optische Transparenz , optisches Spezialglas , physikalische Optik , Selenid , sichtbarer Spektralbereich , transparente Keramik
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