Zinc selenide
Yellow, odorless crystals
Fixed
5.42 g · cm -3
> 1100 ° C.
Practically insoluble in water
Risk
0.05 mg · m-3
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Zinc selenide (ZnSe ) is a II-VI compound semiconductor material. The semiconductor crystal is composed here of a pure element such as silicon, but also from 1:1 stoichiometric amounts of zinc cations (Zn) and selenium anions (s).
Occurrence
Zinc selenide occurs naturally as the mineral Stilleit.
Production and representation
Zinc selenide can be prepared by reaction of solutions of zinc sulfate and hydrogen selenide.
Also possible is the production by the reaction of zinc oxide with zinc sulfide and selenium at 800 ° C.
Or by reaction of zinc sulfide with selenium ( IV) oxide.
The hexagonal modification can be obtained by the action of hydrogen selenide on zinc chloride vapor.
Properties
Zinc selenide is a lemon yellow powder which is soluble in fuming hydrochloric acid, hydrogen selenide development. It has, depending on the modification of a crystal structure of zinc blende (a = 5.67 Å) or wurtzite type (a = 3.98, c = 6.53 Å).
Use
Zinc selenide is, inter alia, for preparing optically highly reflective surfaces used where it is deposited in thin layers alternating with another substance, such as cryolite in vacuum ( multilayer mirrors in laser technology ). Moreover, it is transparent, in contrast to normal glass both in the infrared range and in the visible wavelength range. Therefore, it is particularly suitable for the production of optical windows and focusing lenses for eg CO2 lasers or solid -state lasers. The optical properties of the material can be used to transmit the actual processing wavelength and allowing at the same time the transmission of a most red semiconductor laser for adjustment of the beam path.
The infrared transparency of zinc selenide also makes it interesting for use in infrared spectroscopy. The usable spectral range 20000-650 cm -1 (0.5 to 15 microns ). In this section, zinc selenide crystal is used as a measurement for the technique of attenuated total reflection ( cf. ATR spectroscopy ). Here, the material is referred to as Irtran -1. It is considered by many routine applications as one of the preferred substitutes for highly toxic Thalliumbromidiodid (KRS -5). The refractive index of the two materials is very similar in this area; the refractive index of ZnSe at 1000 cm -1 is 2.4. However, it is not suitable for use in combination with strong acids and bases, as they etch the surface. The same applies to complexing agents such as EDTA and ammonia.
Safety
Comes with zinc selenide acids in contact, very toxic hydrogen selenide gas is released.