Cadmium sulfide formation

The wet synthesis of CdS nanoparticles used in this work is based on the reaction between a dissolved cadmium salt (CdCl2) and a S-containing compound (thiourea (NH2)2CS) in an aqueous solution. Chemical deposition of CdS nanoparticles in the CdCl2 - NH3 - NaOH - (NH2)2CS - H2O bath was described elsewhere [3]. In the present work all the baths had the same composition and were prepared from solutions of cadmium chloride CdCl2 (0.005 mold-1), ammonia NH3-H2O (1.5 moll"1), sodium hydroxide NaOH (0.074 mold-1) and thiourea (NH2)2CS (0.025 mol-F1) using distilled water. The synthesis temperature was varied from 294 to 325 K. The primary concentrations of the precursors have been chosen according to the thermodynamic analysis [4]. A supersaturation of the solution with Cd(OH)2 takes place in the baths. It means that the mechanism of the cadmium sulfide formation could involve the stage of Cd(OH)2 formation. When the deposition process of CdS particles in the solution completed, the residue was filtered at an ambient pressure and dried at room temperature. 

Power GP, Peggs DR, Parker AJ (1981) The Cathodic formation of photoactive cadmium sulfide films from thiosulfate solutions. Electrochim Acta 26 681-682... 

Towey TF, Khanlodhi A, Robinson BH (1990) Kinetics and Mechanism of Formation of Quantiun-Sized Cadmium-Sulfide Particles in Water Aerosol-Ot Oil Microemulsions. J Chem Soc Faraday Trans 86 3757-3762... 

The electrodeposition of cadmium sulfide thin films was carried out by the electroreduction of the aqueous thiocyanate complex of Cd(II). Formation of CdS is supposed to proceed by metal-catalyzed ligand reduction [179]. 

H. Noglik and W. J. Pietro, Chem. Mater., 7, 1333 (1995). Surface Functionalization of Cadmium Sulfide Quantum Confined Semiconductor Nanoclusters. 2. Formation of a Quantum Dot Condensation Polymer. 

Substitution of the lattice cadmium ions in a CdS colloidal particle by the ions of another metal is often accompanied by the formation of the so-called coated particles CdS/MexSy. Such particles are readily produced via the substitution of cadmium ions by other ions if only their sulfide are less soluble compared to the cadmium sulfide. Our studies on the luminescence properties of such particles and regularities of their luminescence... 

There have been only a few reports of mesostructured metal sulfides. Mesoporous cadmium sulfide was prepared from polyethylene oxide surfactants and cadmium salts exposed to hydrogen sulfide [35], A study of the effects of the counter-anion on the formation of CdS mesostructures led to the conclusion that the use of cadmium nitrate and perchlorate salts improved the degree of order of the mesostructure over the chloride, sulfate and acetate salts. This effect was attributed to the stronger acidity of conjugate acid by-products of the reaction in the case of nitrates that leads to the dissolution of high-energy defects and enhances structural order. 

Formation of the hydrazobenzene product is strongly favored when platinized zinc or cadmium sulfide is used as the photocatalyst (Table 3). In both cases the rate decreases considerably and hydrazobenzene becomes the major product. It is known that platinum favors multi-electron processes [34]. 

A in particle size distribution curves. Colloidal gold, silver, platinum and platinized cadmium sulfide were generated in Aerosol-OT reversed micelles or in microemulsions by in situ photolysis of the appropriate ions (Figure 3.15). Under suitable conditions, each assembly contained approximately eight Au " ions, which firstly led to the formation of Aug clusters. ... 

Variation of the hue of yellow cadmium sulfide pigments hy mixed-crystal formation ... 

Tributylphosphine sulfide has been used as a co-catalyst with dicobalt octacarbonyl for the Pawson-Khand reaction. Thermolysis of a mixture of cadmium chloride and trioctylphosphine sulfide at 250 °C has been used as a route to the formation of nanocrystalline cadmium sulfide." A complex of triphenylphosphine sulfide with a silver-tungsten-iodine acceptor has been characterised by X-ray studies. Ferrocenylphosphine chalcogenides have attracted considerable interest as ligands. Complexes of the monophosphino-phosphine sulfide (269) with rhodium have been characterised." The disulfide (270) forms complexes with both gold(i) and gold(iii) acceptors," and a silver(i) complex of the diselenide (271) has been prepared. ... 

Heavy Metals (e.g.cadmium) Sulfide precipitation Formation of mobile polysulfide and organic complexes under certain conditions with low Fe(0H)3 concentrations strong increase mobility under acidic conditions... 

The concentrations depend on the solution composition, for instance cadmium sulfide films prepared at lower pH are close to stoichiometry whereas those prepared at higher pH have a ratio [Cd]/[S] about 1.1 due to the presence of hydroxide species (Cd(OH)2) [45]. The formation of other hydroxy-sulfide films (ofZn [105,106], In [116], Sn [116]) can be also related to competitive precipitation phenomenon. As a consequence, the analysis of the solubility diagrams of all solid compounds in a given CBD system is a useful tool to improve the composition control of the films. This approach... 

However, It Is well to note that Na is not an activator in the strictest sense but is a member of the lattice structure, placed there to avoid formation of a lattice vacancy. If a -vacancy is formed, it is likely that the resulting "phosphor" may be non-luminescent or will exhibit a low degree of luminescent efficiency. Although you will find that many phosphors like ZnS Ag, Al K are listed as requiring the K activator, in reality this cation is present for charge compensation in the lattice. This fact has not been recognized by many prior workers in the field. Furthermore, some zinc (cadmium) sulfides have several listed "activators", part of which are undoubtedly there for charge compensation. Elxamples Include ... 

The results presented above show that Cu nanoparticles can be produced via RESOLV with PFPE-NH4-stabilized water-in-C02 microemulsion as solvent for the rapid expansion. The formation of Cu nanoparticles is apparently similar to that of Ag nanoparticles under comparable experimental conditions (9). The same approach is also applicable to the synthesis of nanoscale metal sulfides, including silver sulfide (Ag2S), cadmium sulfide (CdS), and lead sulfide (PbS) nanoparticles. 

J. Z. Zhang, M. J. Geselbracht, A. B. EUis, Binding of Fullerenes to Cadmium Sulfide and Cadmium Selenide Surfaces, Photolu-minescence as a Probe of Strong, Lewis Acidity-Driven, Surface Adduct Formation, J. Am. Chem. Soc. 1993, 115, 7789-7793. 

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