Zinc selenide

Abrasion and corrosion protection for germanium, magnesium fluoride, cadmium telluride, zinc sulfide, and zinc selenide IR windows. 

Note Zinc sulfide (ZnS) has higher mechanical properties and better erosion resistance than zinc selenide but its optical transmission is not as good. ... 

Commonly used II-VI compounds include zinc sulfide, zinc selenide, zinc telluride, cadmium sulfide, cadmium telluride, and mercury cadmium telluride. These materials are not as widely used as the III-V compounds, one reason being that it is difficult to achieve p-type doping. Mercury cadmium telluride is used extensively in military night sights, which detect in the 8-13 im spectral band (a similar material, platinum silicide, is being developed for that purpose). The major applications ofCVD II-VI compounds are found in photovoltaic and electroluminescent displays. 

Infrared optics is a fast growing area in which CVD plays a maj or role, particularly in the manufacture of optical IR windows. 1 The earths atmosphere absorbs much of the infrared radiation but possesses three important bandpasses (wavelengths where the transmission is high) at 1-3 im, 3-5 im and 8-17 pm. As shown in Table 16.2, only three materials can transmit in all these three bandpasses single crystal diamond, germanium, and zinc selenide. 

The most common IR window materials are zinc sulfide, which is translucent, and zinc selenide, which is transparent. Both of these materials are made by low-pressure CVD by the reaction of vaporized zinc and hydrogen sulfide or selenide (see Ch. 12). Germanium, another common IR window material, is also produced by CVD (see Ch. 8). 

Zinc sulfide, ZnS, sphalerite (zinc blende) zinc sulfide, ZnS, wurtzite zinc selenide, ZnSe zinc telluride, ZnTe, cubic zinc telluride, ZnTe, hexagonal zinc polonide, ZnPo zinc aluminum selenide, ZnAl2Se4 zinc indium selenide, ZnIn2Se4 zinc indium telluride, Znhi2Te4. 

Cathodic electrodeposition of microcrystalline cadmium-zinc selenide (Cdi i Zn i Se CZS) films has been reported from selenite and selenosulfate baths [125, 126]. When applied for CZS, the typical electrocrystallization process from acidic solutions involves the underpotential reduction of at least one of the metal ion species (the less noble zinc). However, the direct formation of the alloy in this manner is problematic, basically due to a large difference between the redox potentials of and Cd " couples [127]. In solutions containing both zinc and cadmium ions, Cd will deposit preferentially because of its more positive potential, thus leading to free CdSe phase. This is true even if the cations are complexed since the stability constants of cadmium and zinc with various complexants are similar. Notwithstanding, films electrodeposited from typical solutions have been used to study the molar fraction dependence of the CZS band gap energy in the light of photoelectrochemical measurements, along with considerations within the virtual crystal approximation [128]. 

Natarajan C, Sharon M, Levy-Clement C, Neumann-SpaUart M (1994) Electrodeposition of zinc selenide. Thin Solid Films 237 118-123... 

P. Lemasson and J. Gautron (1981) On the anodic decomposition of the zinc selenide electrode. J Electroanal Chem 119 289-299... 

Smiley M, Biagioni RN, Ellis AB (1984) Zinc selenide photoelectrodes. J Electrochem Soc 131 1068-1073... 

Figure 9.9 Schesatic diagrans of flow-through cell. A, and solvent elimination interfar B, for SFC/FTIR. For A (1) polished stainless steel lig..v.pipe (2) zinc selenide window (3) PTFE spacer (4) viton rubber o-ring (5) graphitized Vespel nicroferrule (6) deactivated fused-silica capillary tubing (7) bolt with Allen nut (8) stainless steel end-fitting and (9) stainless steel body of flow cell.

Zinc telluride and zinc selenide polymetallic species with phosphine ligands have been structurally characterized 301 further details are discussed in Section 6.8.7. The use of mono- and bidentate phosphine ligands of varying steric bulk contributes to the variation of structural types in the formation of zinc tellurolate polyzinc species with Zn10, Zn14, and Zn16 species structurally characterized by Fenske et al.30... 

A number of zinc selenium complexes have now been characterized, with particular interest in the formation of zinc selenide semiconductors and quantum dots. In many cases analogous structures to those observed with thiol or thiolates are recorded. 77Se NMR is frequently used in characterization, and comparison with the sulfur equivalent is relevant. Zinc selenium compounds are of particular interest as precursors for metal/selenide materials and their relevance as models for selenocysteine-containing metalloproteins. 

The preparation of ZnSe materials is an area of interest and study. The coordinating ability of the solvent used in the solvothermal synthesis of zinc selenide was demonstrated to play an important role in the nucleation and growth of nanocrystalline ZnSe.604 Thermolysis of bis [methyl( -hexyl)di-seleno]carbamato]zinc gave highly monodispersed particles characterized by electronic spectroscopy, photoluminescence, X-ray diffraction, and electron microscopy.605... 

A few ATR probes are commercially available. In the near-IR ATR probes are mostly used as easy-to-use sticking probes for liquids and solids. As the aim is primarily to identify a material, not to measure low concentrations, probes with typically one or two reflections (Figure 5-d) are used. In the mid-IR, similar layouts can be found, using e.g. zinc selenide, germanium or silicon crystals as sensing elements. More sensitive and generally better suited for industrial process control DiComp -type probes (Figure 5-e). The actual ATR element is in this case a thin diamond disc supported by a suitably shaped ZnSe crystal. ATR probes of that type are available off the shelf with between one and nine reflections. If more... 

Shinn, G. B. Gillespie, P. M. Wilson, W. L., Jr. Duncan, W. M. 1989. Laser-assisted metalorganic chemical vapor deposition of zinc selenide epitaxial films. Appl. Phys. Lett. 54 2440-2442. 

Zinc rolling slabs, 26 596 Zinc salt (1 2), hydrate, 4 242t Zinc salts, 26 605 Zinc scrap, 27 395 Zinc selenide... 

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