Cadmium manganese sulfide

The term heavy metals covers a wide range of elements, such as copper, lead, mercury, cadmium, manganese, zinc, etc. These are naturally present in the environment at low concentrations. Some heavy metals are indispensable for plant and animal growth in very small quantities (trace elements), but become toxic at higher doses. Besides the fact that all heavy metal sulfides are insoluble, their chemical properties are dissimilar. Copper is treated separately in winemaking in view... 

Intimate mixtures of chlorates, bromates or iodates of barium, cadmium, calcium, magnesium, potassium, sodium or zinc, with finely divided aluminium, arsenic, copper carbon, phosphorus, sulfur hydrides of alkali- and alkaline earth-metals sulfides of antimony, arsenic, copper or tin metal cyanides, thiocyanates or impure manganese dioxide may react violently or explosively, either spontaneously (especially in presence of moisture) or on initiation by heat, friction, impact, sparks or addition of sulfuric acid [1], Mixtures of sodium or potassium chlorate with sulfur or phosphorus are rated as being exceptionally dangerous on frictional initiation. 

The main sulfide phosphors are the group II-V ones based on high purity zinc and cadmium sulfides activated by dopants, primarily using copper and silver but also manganese, gold and rare earths. The nature and concentration of the activator, the composition of the flux and the firing conditions, normally in furnaces at 800-1500 °C, influence the luminescent properties. 

In 1863 Reich began a search for thallium in some Freiberg zinc ores from the Himmelsfurst mine consisting mainly of arsenical pyrites, blende, lead glance, silica, manganese, copper, and small amounts of tin and cadmium (19, 43). After roasting the blende to remove most of the sulfur and arsenic, he decomposed it with hydrochloric acid (47). When Clemens Winkler, who was then a metallurgist in the Saxon smalt works, visited Professor Reich in 1863, the latter showed him a straw-yellow precipitate and said, This is the sulfide of a new element (52). Because of his colorblindness, however, Reich entrusted the spectroscopic examination to his assistant, Richter. 

After dipping strips of zinc into concentrated solutions of manganese salts, they scraped off a deposit containing zinc, lead, cadmium, nickel, and cobalt. After complete removal of these heavy metals by precipitation as the sulfides, they found no evidence of element 43, but thought they found the X-ray lines of number 75 ( 42). When Dr. Druce took his dwi-manganese preparation to the Charles University in Prague for polaro-graphic examination, the Czechoslovakian chemists confirmed his conclusions. 

FIG. 1.13 Spherical and cubic model particles with crystalline or amorphous microstructure (a) spherical zinc sulfide particles (transmission electron microscopy, TEM, see Section 1.6a.2a) x-ray diffraction studies show that the microstructure of these particles is crystalline (b) cubic lead sulfide particles (scanning electron microscopy, SEM, see Section 1.6a.2a) (c) amorphous spherical particles of manganese (II) phosphate (TEM) and (d) crystalline cubic cadmium carbonate particles (SEM). (Reprinted with permission of Matijevic 1993.)... 

The synthesis of Mn2+-doped CdS nanocrystals has been studied by several groups. In one such study (82), the doped CdS nanocrystals were prepared by simple mixing of ethylene glycol solutions of cadmium and manganese acetate with a solution of sodium sulfide, followed by washing with methanol and thermal treatment in triethyl phosphate to deagglomerate the particles. Mean... 

PHOTOLUMINESCENCE AND EPR SPECTRA OF MANGANESE-DOPED CADMIUM SULFIDE NANOPARTICLES... 

Mn-doped CdS nanoparticles were synthesized by the colloidal chemistry method with cadmium chloride (CdCli), manganese chloride (MnClj) and sodium sulfide (NaaS) as starting materials. PVA was used as a capping reagent. All steps of the synthesis were performed at room temperature under ambient conditions. 

Photoluminescence and EPR spectra of manganese-doped cadmium sulfide nanoparticles. 

The zinc salt solutions, which currently mainly come from zinc and copper smelters, contain impurities which have to be completely removed prior to use, because all heavy metals form colored sulfides. For the purification step the solution is oxidized with chlorine (pH 4), which precipitates most of the iron and manganese as the oxide-hydrate and part of the cobalt, nickel and cadmium present as their hydroxides. In the second step, the elements nobler than zinc (Ni, Co, Cd, In, Tl, Pb, Cu, Ag) are precipitated as their metals by adding zinc dust and the metals returned to the copper smelters for noble metal extraction. After purification the solutions are adjusted to a particular zinc content. Mixtures of zinc sulfate and zinc chloride solutions are used for manufacturing lithopone types with more than 30% ZnS. 

Manganese-activated zinc silicate, zinc/cadmium sulfide, lead/manganese-activated calcium silicate. 

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