Copper, Silver and Gold

The United States gets most of its bismuth as a by-product from smelting ores of lead, silver, copper, and gold. It is also recovered from the refining of tin and tungsten ores. 

Khaydarov RA, Khaydarov RR, Olsen RL, Rogers SE (2004) Water disinfection using electrolyticaUy generated silver, copper and gold ions. J Water Supply Res T 53 567-572... 

Absorption resonances resulting from excitation of surface modes are accompanied by scattering resonances at approximately the same frequencies this was pointed out following (12.26). In most experiments transmission is measured to determine extinction, which is nearly equal to absorption for sufficiently small particles. However, surface mode resonances have been observed in spectra of light scattered at 90° by very small particles of silver, copper, and gold produced by nucleation of vapor in an inert gas stream (Eversole and Broida, 1977). The scattering resonance peak was at 3670 A, near the expected position of the Frohlich mode, for the smallest silver particles. Although peak positions were predictable, differences in widths and shapes of the bands were concluded to be the result of nonsphericity. 

Eversole, J. D., and H. P. Broida, 1977. Size and shape effects in light scattering from small silver, copper, and gold particles, Phys. Rev., B15, 1644-1655. 

Potassium and sodium are good conductors of heat.23 If the conductivity of silver be unity, that of sodium is 0 365. J. W. Hornbeck found the temp, coeff. of the thermal conductivity of potassium or sodium falls with rise of temp. The alkali metals are also good conductors of electricity 24 for example, the conductivity of sodium for heat and electricity is exceeded only by silver, copper, and gold. According to E. F. Northrup, the metals sodium, potassium, mercury, tin, lead, and bismuth have the same value for the ratio of the coeff. of electrical resistance to the coeff. of cubical expansion at the same temp. The electrical conductivity of lithium is nearly ll-4xl04 reciprocal ohms at 20°, that is, about 20 4 per cent, of the conductivity of hard silver of sodium at 2T 70, 22 4 XlO4 reciprocal ohms, that is, about 36 5 per cent, of the value of silver. 

Drilled samples, 200-1000 fig and sealed in pure quartz vials, are activated and analyzed in a similar way for silver, copper, and gold content. Drill bits of tungsten carbide and stainless steel, materials much harder than silver, were used in taking samples. Since no significant differences in concentrations of the major elements of the drill bit materials could be found in samples taken with either of them, possible contamination by the drill bits can be neglected. 

A drawback which has limited somewhat the practical applications of SERS to surface chemistry is that satisfactory enhancement can apparently only be obtained at relatively few metal surfaces, most prominently silver, copper, and gold, under conditions where the surface is mildly roughened. These metals, especially gold, are nevertheless of importance in electrochemistry in view of their strongly adsorptive and electrocatalytic properties in aqueous media. 

In the formation of SAMs, the film-forming molecules order themselves by chemical interaction with neighbouring molecules and with the substrate surface. This technique has been applied for a large variety of modifier/substrate combinations. Various sulphur compounds, like alkanethiols and (di)sulfides have been deposited on metals such as silver, copper and gold isocyanides on platinum and carboxylic acids on aluminum oxide and silver oxide.75 Alkyltrichlorosilanes have been deposited on gold, mica, aluminum, tin oxide and silicon oxide. The latter combination is of interest here. 

Sodium is a good conductor of heat, and as a conductor of electricity it stands next to silver, copper, and gold. Its electric conductivity has been studied by several investigators.13... 

Raw Lead, mixed with Silver, Copper and Gold. 

Another interesting point from Equation 13.49 is the magnitude of the electrolyte conductivity inside the pore, x depends on the function of the bulk electrolyte conductivity [15], x° ar d the porosity factor in the case of hemispherical particles (silver, copper, and gold, for example) where is less than 0.45 ... 

Surface-enhanced Raman spectroscopy was intensively used to study organic additives on silver, copper, and gold." An example is an investigation of the orientation of nicotinic acid on silver. The Raman spectra were measured at different pH values. This is shown in Figure 7.29a. Preferential adsorption of the nicotinic acid anion was observed. The dissociation reactions are shown in Figure 7.29b. 

Metallic fillers can impart special properties to an epoxide formulation, such as giving response to magnetic fields and providing a radiation shielding capability. They are also used to enhance properties such as thermal conductivity and electrical conductivity and it is this last feature that makes them so useful in the electronics industry, where they find wide use in die attach materials. The principal metals used for enhancing electrical conductivity are silver, copper and gold, although various metal alloys such as silver/palladium have also been utilised. 

Cyanides such as silver cyanide AgCN, copper cyanide Cu(CN)2, and gold cyanide AuCN, that are used in galvanoplastic processes, lead to pitting corrosion of aluminium due to the presence of cations of heavy metals (silver, copper, and gold). 

Although less common than many other non-ferrous metals in the earth s crust, lead is widely distributed throughout the world and is mined in all continents apart from Antarctica. However, three countries (Australia, Canada and the USA) supply about one-half of mined lead in the West. Most lead is mined as a co-product with, or by-product of, other metals (zinc mainly, but also silver, copper and gold, in that order). This has important implications for the comparative economics of individual lead mining operations, for market structure and for metal price formation. 

On average, the most important lead mine co- and by-products, in value terms, are zinc, silver, copper and gold, in that order. Lead generates a relatively small share of total mine revenues at most operations (probably less than 20 per cent, at current prices). This consequently implies that developments in the price of other metals will have a crucial impact on lead supply decisions, and indirectly on lead prices themselves. Although there does seem to be a close correlation between base metal prices, there is no guarantee that the markets for these or other of lead s co-products will always move in tandem with the price of lead, as Fig. 17.5 illustrates. 

Aluminum is indeed used for interconnects in some integrated circuits even though its electrical conductivity is shghtly lower than the values for silver, copper, and gold, its extremely low diffusion coefficient makes it the material of choice for this application. An alumi-num-copper-silicon alloy (94.5 wt% Al wt% Cu-1.5 wt% Si) is sometimes also used for interconnects it not only bonds easily to the surface of the chip, but is also more corrosion resistant than pure aluminum. 

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