Cadmium sulfides

Entry number Title of article Comments Reference 

2 Photosensitized Electrolytic Oxidation of Iodide Ions on Cadmium Sulfide Single Crystal Electrode. The stability of CdS probe under irradiation in an electrolyte containing iodide species. Rotating ring disk voltammetry was used as the methodology. 487 

3 Suppression of Surface Dissolution of CdS Photoanode by Reducing Agents. As above but a variety of electron donors used. The use of sulfite for electrode stabilization demonstrated. 488 

4 Photochemical Diodes. A CdS single crystal platelet used in conjunction with Pt to drive the HER from sulfide solutions. 489 

5 Superoxide Generation in the Photolysis of Aqueous Cadmium Sulfide Dispersions. Detection by Spin Trapping. First of many studies examining the behavior of powder dispersions. Electron transfer by irradiation of CdS shown to occur to methyl viologen. The corresponding radicals observed only when an electron donor (EDTA) is simultaneously present. 490 

1 Becquerel Photovoltaic Effect in Binary Compounds. Appears to be the first study on die mechanism of the photovoltaic effect on a CdS/electrolyte interface. 486 

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Lianos P and Thomas J K 1986 Cadmium sulfide of small dimensions produced in inverted micelles Chem. Phys. Lett. 125 299... 

Greenockite, see Cadmium sulfide Gruenerite, see Iron(II) silicate(2—)... 

Carbonate is measured by evolution of carbon dioxide on treating the sample with sulfuric acid. The gas train should iaclude a silver acetate absorber to remove hydrogen sulfide, a magnesium perchlorate drying unit, and a CO2-absorption bulb. Sulfide is determined by distilling hydrogen sulfide from an acidified slurry of the sample iato an ammoniacal cadmium chloride solution, and titrating the precipitated cadmium sulfide iodimetrically. 

Medicated Dandruff Shampoos. Dandmff is a scalp condition characterized by the production of excessive cellular material (18). A number of shampoos have been marketed which are designed to control and alleviate this condition, and many additives have been included in shampoo compositions to classify them as treatment products for dandmff. These additives include antimicrobial additives, eg, quaternary ammonium salts keratolytic agents, eg, saUcychc acid and sulfur heavy metals, eg, cadmium sulfide coal tar resorcinol and many others. More recent (ca 1993) systems use selenium sulfide [7488-56-4] or zinc pyrithione [13463-41 -7] as active antidandmff shampoo additives. Both of these additives are classified as dmgs, but can be found in over-the-counter products. A stronger version, incorporating the use of higher levels of selenium sulfide in a shampoo, is available but requires a prescription for purchase. 

Heterogeneous Photocatalysis. Heterogeneous photocatalysis is a technology based on the irradiation of a semiconductor (SC) photocatalyst, for example, titanium dioxide [13463-67-7] Ti02, zinc oxide [1314-13-2] ZnO, or cadmium sulfide [1306-23-6] CdS. Semiconductor materials have electrical conductivity properties between those of metals and insulators, and have narrow energy gaps (band gap) between the filled valence band and the conduction band (see Electronic materials Semiconductors). 

Cadmium Sulfide Photoconductor. CdS photoconductive films are prepared by both evaporation of bulk CdS and settHng of fine CdS powder from aqueous or organic suspension foUowed by sintering (60,61). The evaporated CdS is deposited to a thickness from 100 to 600 nm on ceramic substates. The evaporated films are polycrystaUine and are heated to 250°C in oxygen at low pressure to increase photosensitivity. Copper or silver may be diffused into the films to lower the resistivity and reduce contact rectification and noise. The copper acceptor energy level is within 0.1 eV of the valence band edge. Sulfide vacancies produce donor levels and cadmium vacancies produce deep acceptor levels. 

Four different types of junctions can be used to separate the charge carriers in solar cebs (/) a homojunction joins semiconductor materials of the same substance, eg, the homojunction of a p—n sibcon solar ceb separates two oppositely doped layers of sibcon 2) a heterojunction is formed between two dissimbar semiconductor substances, eg, copper sulfide, Cu S, and cadmium sulfide, CdS, in Cu S—CdS solar cebs (J) a Schottky junction is formed when a metal and semiconductor material are joined and (4) in a metal—insulator—semiconductor junction (MIS), a thin insulator layer, generaby less than 0.003-p.m thick, is sandwiched between a metal and semiconductor material. 

Copper Sulfide—Cadmium Sulfide. This thin-film solar cell was used in early aerospace experiments dating back to 1955. The Cu S band gap is ca 1.2 eV. Various methods of fabricating thin-film solar cells from Cu S/CdS materials exist. The most common method is based on a simple process of serially overcoating a metal substrate, eg, copper (16). The substrate first is coated with zinc which serves as an ohmic contact between the copper and a 30-p.m thick, vapor-deposited layer of polycrystaUine CdS. A layer is then formed on the CdS base by dipping the unit into hot cuprous chloride, followed by heat-treating it in air. A heterojunction then exists between the CdS and Cu S layers. 

Chemical pigments or synthetics may be metal compounds. A good example is white titanium dioxide. Other chemical pigments include cadmium sulfide colors, iron blue, and several synthetic versions of iron oxides. 

The intermetallic compounds with Group 16 (VIA) elements including CdS, CdSe, and CdTe have interesting semiconductor properties for photoconductors, photovoltaic cells, and ir windows. Cadmium sulfide is widely used as a phosphor in television tubes. 

Cadmium hydroxide is the anode material of Ag—Cd and Ni—Cd rechargeable storage batteries (see Batteries, secondary cells). Cadmium sulfide, selenide, and especially teUuride find utiUty in solar cells (see Solarenergy). Cadmium sulfide, Hthopone, and sulfoselenide are used as colorants (orange, yellow, red) for plastics, glass, glazes, mbber, and fireworks (see Colorants for ceramics Colorants forplastics Pigments). 

Cadmium Sulfide. CdS [1306-23-6] is dimorphic and exists ia the sphalerite (cubic) and wurtzite (hexagonal) crystal stmctures (40). At very high pressures it may exist also as a rock-salt stmcture type. It is oxidized to the sulfate, basic sulfate, and eventually the oxide on heating ia air to 700°C, especially ia the preseace of moisture (9). 

Cadmium Sulfide Cadmium Selenide Tox. Chem. Eelease Kep. Comm. Eight-To-Know 54(201), 42962 (1989). 

Cadmium sulfide yellow can be considered for the brightest low temperature apphcations (15). It is a very bright, clean orange yellow. Primrose yellow and light yellow shades are made by precipitating small amounts of ZnS with the CdS. All the limitations of the cadmium sulfoselenide reds discussed above apply to the cadmium sulfide yellow. 

Othei photoconductive pigments (qv) which found commercial appHcation are cadmium sulfide [1306-23-6] CdS, or the alloy with Se, CdS Se ... 

Schwefel-indium, n. indium sulfide. -jodUr, n. sulfur monoiodide, -kadmium, n. cadmium sulfide. -kalium,n. potassium sulfide, -kalk, m. lime-sulfur, -kalkbrtihe, /. lime-sulfur mixture (for spraying), -kalzium, n. calcium sulfide, -kammer, /. sulfur chamber, sulfuring room, sulfur stove, -karbolsaure, /. sulfo carbolic acid, -kastenbleiche, /. (Dyeing) stoving. 

Thin-layer plates were made with silica gel-calcium sulfate and each contained a mixture of zinc silicate and zinc cadmium sulfide as phosphors. Separated components are generally visible under ultraviolet light by fluorescence quenching. This was true, in part, for the pyrethrins, except that some of the separated components possessed a natural fluorescence under the ultraviolet lamps. 

Cadmium, determination by x-ray emission spectrography, 328 Cadmium sulfide, use in x-ray detection, 43... 

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