Silver selenides

The silver-selenium binary phase diagram was reviewed by Karakaya and Thompson [90KAR/THO]. Ag2Se(cr) is the only intermediary phase in the system and exists in two polymorphs, a and p. The a form is stable below 406 K. The melting point is 1170 K. 

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Nantokite, see Copper(I) chloride Natron, see Sodium carbonate Naumannite, see Silver selenide Neutral verdigris, see Copper(H) acetate Nitre (niter), see Potassium nitrate Nitric oxide, see Nitrogen(II) oxide Nitrobarite, see Barium nitrate Nitromagnesite, see Magnesium nitrate 6-water Nitroprusside, see Sodium pentacyanonitrosylfer-rate(II) 2-water... 

Selenium occurs in the slimes as intermetallic compounds such as copper silver selenide [12040-91 -4], CuAgSe disilver selenide [1302-09-6], Ag2Se and Cu2 Se [20405-64-5], where x < 1. The primary purpose of slimes treatment is the recovery of the precious metals gold, silver, platinum, palladium, and rhodium. The recovery of selenium is a secondary concern. Because of the complexity and variabiUty of slimes composition throughout the world, a number of processes have been developed to recover both the precious metals and selenium. More recently, the emphasis has switched to the development of processes which result in early recovery of the higher value precious metals. Selenium and tellurium are released in the later stages. Processes in use at the primary copper refineries are described in detail elsewhere (25—44). 

Selen-kupfer, n. copper selenide. -kupfer-silber, n. copper silver selenide (Min.) eucairite. -metall, n. metallic selenide. 

Selen-saure, /. selenic acid, -saureanhydrid, n. selenic anhydride (SeOa). -schlamm, m. selenium mud, selenium slime (seleniferous sulfuric acid works). -schwefel, m. Min.) selensulfur. -schwefelkohlenstoff, m. carbon sulfide selenide, CSSe. -silber, n. silver selenide. -silberglanz, m. naiimannite. 

Birss VI, Wright GA (1981) The kinetics of the anodic formation and reduction of phase silver sulfide films on silver in aqueous sulfide solutions. Electrochim Acta 26 1809-1817 Petrov GV, Belen ku AM (2005) Interactions in the silver selenide-water system. Russ J Appl Chem 78 53-56... 

Aloisi et al. [337] have performed in situ STM and electrochemical investigations of oxidative UPD of sulfur on Ag(lll). Electrodepositions of silver selenide [338], silver telluride thin films [339], and silver selenide nanowires [340] have also been described. 

Selenium reduces hot aqueous solutions of silver or gold salts with the formation of silver selenide or metallic gold, respectively. In the case of silver salts the reaction corresponds with the equation 6... 

Dunn (156) showed that colloidal selenium likewise is a sensitizer and produces similar effects to those obtained with selenoureas. Spencer, Atwell, and Levy (94) confirmed this and showed that silver selenide can be formed by reaction of silver bromide with selenium. They further demonstrated the similarity between sulfur and selenium sensitization. In the absence of evidence to the contrary, the presumption is that the mechanism or mechanisms of sensitization by the two agents is the same. 

Ag2Se (c, II). Fabre2 measured the heats of reaction of silver selenide with bromine water and of aqueous silver acetate with gaseous hydrogen selenide. See also Pelabon1 and Tubandt and Reingold.1... 

However, high intake of selenium (e.g., as sodium selenite or selenium oxide) may lead to increased deposition of insoluble silver salts in body tissues through the formation of silver selenide (Alexander and Aaseth 1981) Berry and Galle 1982 Nuttall 1987). Exposure to silver nitrate in... 

Those that convert the silver image into silver selenide (Formulas Toners Dassonville T-55 Direct Selenium Toner). 

Figure 5. Plot of the logarithm of electronic conductivity against inverse of absolute temperature for various compositions of a-and 3-silver selenide. The degree of nonstoichiometry, 5, was determined by solid-state coulometry (taken from ref 32).

Silver selenide, AgaSe.—Measurements of E.M.F. in selenide cells indicate the existence of the monoselenide only.4 It is formed by the action of selenium on the nitrate (p. 316). 

Silver and silver selenide thin films were prepared from a series of liquid silver precursors containing /3-diketonates and phosphite ligands (Table 5) as demonstrated by Shim and coworkers. In a typical deposition experiment, Ag(tfac)(P(OEt)3) produced very pure silver films under relatively mild conditions (170 °C) without any appreciable amount of fluorine, oxygen and phosphorus impurities. These films could easily be converted to Ag2Se by selenium vapor deposition . 

In the measurements performed by Mehra and Gubeli [70MEH/GUB], the solubility measurements conducted with radioactively labelled silver showed a constant dissolved silver selenide concentration of about 6 x 10 to 8 x 10 M at pH < 10. The solubility was independent of the total Se(- 11) concentration in the test solutions. From this finding it was concluded that a species of the formula Ag2(HSe)(OH)(aq) was formed and its stability constant was evaluated from the data. The composition of this complex is formally equivalent to the composition Ag2Se(aq) and therefore not unique. The observed constant solubility would then correspond to an intrinsic solubility of Ag2Se(s)... 

One report indicates a nontoxic dose of silver acetate in rats minimizes effects of acute selenium toxicity. However, the body burden of selenium in several organs increased with treatment with silver acetate. It is postulated that this antagonistic effect may be due to the formation and disposition of silver selenides which are relatively insoluble and nontoxic (Eybl et al. 1992). 

O 14.01%, Se 23.04%. Ag,SeO,. Prepd by dissolving silver selenide in boiling nitric acid and cooling Berzelius, cited by Mellor, A Comprehensive Treatise on Inorganic and Theoretical Chemistry 10, 824 (1930) from a soln of silver carbonate in selenlous acid Thomsen, Ber. 2, 598... 

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