Sulfoselenide pigments

Sulfide and sulfoselenide pigments cadmium sulfoselenide cadmium sulfide (Cd, Zn) S ... 

Cadmium sulfide and sulfoselenide pigments have been widely used for their attractive color, high heat resistance and excellent fastness properties. Due to environmental concerns the use of cadmium-based pigments is increasingly restricted. 

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). 

CdSe forms sohd solutions with CdS which are used as pigments ranging ia color from orange to deep maroon and are called cadmium sulfoselenides. Other uses are ia photocells, rectifiers, lumiaous paiats, and as a mby colorant for glass manufacture. CdSe currentiy sells for 1.50/g as phosphor-grade (99.999% purity) material. 

Pigment Systems. Most of the crystals used for ceramic pigments are complex oxides, owing to the great stability of oxides in molten silicate glasses. Table 3 fists these materials. The one significant exception to the use of oxides is the family of cadmium sulfoselenide red pigments. This family is used because the colors obtained caimot be obtained in oxide systems thus it is necessary to sustain the difficulties of a nonoxide system. 

In an attempt to extend the firing range of these colors, the inclusion pigments (11,17) have been developed. In these pigments cadmium sulfoselenides are incorporated within a clear 2h con lattice. The superior stabiHty of 2h con is thus imparted to the pigment. Colors from yellow to orange-red are available. Deep red is not available, and the purity of these colors is limited. 

Cadmium Sulfoselenide Orange, pigment for plastics, 7 370t... 

Cadmium red consists of cadmium sulfoselenide [12656-57-4], [58339-34-7], Cd(S,Se), and is formed when sulfur is replaced by selenium in the cadmium sulfide lattice. With increasing selenium content, the color changes to orange, red, and finally dark red. The density of these pigments increases correspondingly from 4.6 to 5.6 g/cm3 and the refractive index from 2.5 to 2.8. The crystals have cubic or spheroidal habits, the prevalent particle size is 0.3-0.4 pm. 

Mercury-cadmium pigments were developed in the early 1950s as a more cost-effective alternative to cadmium sulfoselenides. Mercury replaces part of the cadmium in the cadmium sulfide compound and eliminates the need for selenium. The resulting pigments range from deep orange to a maroon and offer a cleaner, brighter chroma than their cadmium counterparts. Manufacture is the same as for cadmium sulfides, except that mercury salts are added to the cadmium solution that is reacted with the alkali sulfide solution to cause precipitation. 

Mercury-cadmium pigment performance is somewhat lower than cadmium pigment performance. They are inferior to sulfoselenides in lightfastness and are not recommended for exterior applications. Nor are they as heat stable as sulfoselenides. Maximum processing temperature is about 320°C. They are quite suitable for ABS but are not sufficiently heat stable for ploycarbonate or polyamide 6.6. 

Cepria and coworkers used the voltammetry of immobilized microparticles to detect and quantify the cadmium pigments (e.g., cadmium sulfide and cadmium sulfoselenide) used in artists paints, as well as in glasses, plastics, ceramics, and enamels [141]. For this, a simple, fast and reliable technique was developed that proved to be especially applicable for valuable art objects, as it was minimally invasive and required only nanogram quantities of material (see also Section 6.4.1). For quantification purposes, an abrasive stripping scan was used from + 0.3 V to —1.0 V, following a 10 s pre-treatment step at —1.5 V. The Cd oxidation peak was evaluated with respect to an internal AgCl calibration standard. 

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