Solubility Of Silver Research Articles

Effect of Additives on Ostwald Ripening of Silver in Glass

The effect of additives on the growth of silver particles in a lead borosilicate glass was studied. Growth of silver particles was expressed by the Ostwald ripening theory and controlled by diffusion. Addition of palladium retarded the growth of silver particles. This is attributed to the reduced activity of silver caused by the formation of silver–palladium solid solutions. Addition of ruthenium dioxide promoted the growth, whereas addition of tin dioxide had almost no effect on the growth rate. A “solubility parameter” was introduced to evaluate the temperature dependence of solubility of silver in glass, and the effect of additives has been discussed. Association of diffusion species has been proposed as a possible factor responsible for the temperature dependence of the solubility parameter.

Effect of Temperature on Ostwald Ripening of Silver in Glass

The effect of temperature and volume fraction on the growth of silver particles in a lead borosilicate glass has been studied. The particle growth obeyed the Ostwald ripening theory and was controlled by diffusion. An anomaly of growth rate coefficient was observed around 700°C and explained in terms of the dissolution behavior of silver. Also, the solubility of silver in glass was evaluated from the normalized rate coefficient K using volume fraction of silver particles and viscosity of the glass.

Effect of silver solubility on microstructure and superconducting properties of YBa2Cu3−xAgxO7−δ superconductors

The effect of silver (Ag) solubility on microstructure and superconducting properties of YBa2Cu3−xAgxO7−δ (0≤x≤0.5) superconductors has been evaluated. The solubility limit of Ag for copper sites in YBCO at ambient conditions (room temperature, atmospheric pressure) was evaluated to be x≂0.06. Analysis revealed the Ag content (x) of YBCO grains to be lower than the nominal Ag content (xn) used for fabrication, probably due to processing-related problems. Part of the Ag used for fabrication segregates on the YBCO grain boundaries. The segregated Ag particles are believed to pin YBCO grains, resulting in fine-grain microstructures. For low nominal Ag content, xn<0.2, critical current density (Jc) increased from 98 to 160 A/cm2 as a function of increasing Ag content. These improvements are believed to be due to the increased oxygen content and associated microstructural changes in the YBCO. For higher nominal Ag content, xn≳0.2, however, Jc decreased rapidly with the increasing Ag content due to the precipitation of nonsuperconducting phases.

Diffusion and solubility of copper, silver, and gold in germanium.

Diffusion profiles of Cu, Ag, and Au were recorded on Ge crystals with various dislocation densities using the spreading-resistance technique. The penetration rate of Cu in effectively highly dislocated samples proves to be much faster than in virtually dislocation-free material. In the case of intermediate dislocation densities, two-stage Cu profiles are found. Diffusion coefficients of Ag and Au do not depend on the presence of dislocations. For all three elements, equilibrium solubilities were taken from the boundary concentration of the penetration profiles. A combined analysis of diffusivity and solubility data reveals that all features can be explained within the framework of the dissociative mechanism involving interstitial-substitutional exchange with the aid of vacancies. Whereas transport of interstitial Cu atoms proceeds faster than that of vacancies, for Ag and Au the opposite case appears to be true.

Characterization of silver-doped perovskite- and spinel-type electrode coatings

Samples of spinel-type Ag x Co 3− x O 4 and perovskite-type Ag x La 1− x CoO 3 ( x ⩽ 0.3) prepared by thermal decomposition of the metal nitrates and subsequent solid state reaction of the oxides were deposited onto nickel substrates (layer thickness, about 40 μm) by vacuum plasma spraying (VPS). X-ray diffraction and photoelectron spectroscopy measurements show that during the deposition process decomposition of the powders takes place to some extent. However, the original single-phase spinel- and perovskite-type compounds can be reproduced by subsequent annealing at 700 °C. Whereas silver remains incorporated in the spinel lattice during VPS deposition, the solubility of silver in the perovskite lattice is fairly low. After anodic polarization of the electrodes in alkaline solution we found no evidence for alien phases in the electrocatalytic layers.

Bulk diffusion and solubility of silver and nickel in lead, lead-silver and lead-nickel solid solutions

The results of a study of solubility and bulk diffusion of 110Ag and 63Ni in lead, lead-silver and lead-nickel solid solutions in the temperature range 220 to 88°C are reported. Owing to the low solubility of silver and nickel in lead, Pick's solution corresponding to the boundary condition of a constant concentration of solute at the surface has been used. Depth-profile concentration analysis of 110Ag and 63Ni suggests a fundamental difference between the diffusion mechanisms of silver and nickel. Since silver penetration profiles in pure lead give diffusion coefficients independent of the penetration depth and silver concentration, it is suggested that slight decrease of silver diffusivity in lead-silver solid solutions (which remain within experimental error) have no significance. This implies that the interstitial silver atoms do not associate significantly with each other to form Ag-Ag dimers. In contrast, different behaviors of 63Ni depth profile concentration in pure lead and saturated PbNi solid solutions agree with a strong Ni-Ni interaction leading to the formation of less mobile dimers near the surface in pure lead. The model proposed by Decker to describe the diminution of gold diffusivity in PbAu solid solutions yields H = 9500 cal/mol and S = 0.9 k for the binding enthalpy and entropy of Ni-Ni substitutional dimers.

Solubility, diffusion and thermodynamic properties of silver in silicon

Concentration-depth profiles of Ag in Si have been measured with the aid of neutron activation analysis combined with serial removal of sections. The Ag diffusion appears to be very fast. In the bulk of dislocation-free Si wafers saturation is achieved after short periods of annealing. From this the authors conclude that interstitial Agi is the predominant configuration in Si without dislocations. Equilibrium concentrations of Agi are determined for temperatures between 1287 and 1598 K. The results are thermodynamically analysed, taking into account Ag-Si liquidus data. In dislocated Si much higher Ag concentrations are observed, which vary irregularly with the penetration depth. A comparison of the diffusion and solubility of Ag and Au in Si suggests that in Si with dislocations substitutional Ags may arise from Agi-Ags transitions. Finally an estimate of the Agi diffusivity is obtained.

Stratiform copper deposits hosted by low-energy sediments; III, Aspects of metal transport

The approximate compositions of closed basin saline waters that existed in probable source rocks of stratiform copper deposits hosted by low-energy sediments were derived by the simulated evaporation of dilute inflow waters from basalt and granite provenances. The saline water derived from dilute inflow water in the basalt provenance had a pH of 7.6 and was saturated with talc, dolomite, and gypsum. The saline water derived from dilute inflow water in the granite provenance had a pH of 7.7 and was saturated with quartz, calcite, talc, and gypsum. Both waters were 3 molal in chloride and were also saturated with hematite, fluorite, and fluorapatite. The waters probably represent likely end members in the compositional spectrum of metal-transporting waters which existed in the source rocks of the stratiform copper deposits. Copper and cobalt exhibit solubility maxima of 1,500 ppm or greater and 150 ppm, respectively, at oxygen fugacities in the range 10 (super -35) to 10 (super -55) bars. Lead solubility is similar in the two waters and is a maximum of 20 ppm at oxygen fugacities greater than 10 (super -60) bars. Zinc solubility is a maximum of 80 ppm in the basalt-derived saline water, and 20 ppm in the granite-derived saline water. Silver solubility is a maximum of 200 ppm at oxygen fugacities above 10 (super -35) bars. Barium and iron solubilities are less than 5 ppm. Abundances of copper, silver, and in some instances cobalt, in all common source rocks result in concentrations of these metals in the saline waters less than their saturation limits. Concentrations of barium, iron, lead, manganese, and zinc in the saline waters are limited by water composition rather than by abundance in source rocks. The high copper, cobalt, lead, and zinc solubilities are consistent with the hypothesis (Haynes, 1986a) that most sulfides in stratiform copper deposits hosted by low-energy clastic sediments are deposited within 50 cm of the sediment-water interface during bacterial sulfate reduction. Porosity and permeability constraints imposed by uncompacted analogs of ore-hosting sediments show that the copper contents of the metal-transporting waters must be greater than 100 ppm for formation of ore which grades 1 percent or more copper. The modeling demonstrates that the proposed waters are potentially effective metal transporters capable of forming stratiform copper ore when the prevailing oxygen fugacity is within the range 10 (super -35) to 10 (super -55) bars. The saline waters are capable of transporting at least 100 ppm copper, and therefore, are likely to produce copper ore under the porosity and permeability constraints imposed by the hypothesis.

Leaching of silver with various copper(II) salts in aqueous acetonitrile: Solubility measurements and recovery of silver powders via distillation

Copper(II) ions in acidified aqueous acetonitrile solutions are capable of leaching metallic silver. Silver powder may be recovered by distilling off the volatile acetonitrile. The type of acid used in the process is important in determining the solubility of the copper(II) salt and the ultimate solubility of silver. Sulphuric or p-toluenesulphonic acids are preferred. Other acids tested, which proved to be unsatisfactory, were sulphamic, trichloroacetic and phosphoric. The nature of the silver powder produced by distillation of filtered leach solutions was shown to depend on the solution composition and the presence of additives such as gelatin, thiourea and polyacrylamide. Particle sizes ranged from below 5 μm up to 100 μm. The powders were deposited as sheets or fluffy aggregates made up of microcrystals. These silver microcrystals were either flat platelets or nodular in shape with well-defined crystal faces.

Electron microscope observations and measurements in the Al/Ag thin film system

Electron microscope observations were made of phase growth in Al/Ag evaporated thin film diffusion couples. Only one phase formed and was identified as Ag 2Al by selected area electron diffraction. There was some evidence for grain boundary diffusion along the aluminium grains. This is limited because of the low solubility of silver in aluminium. There was no evidence of grain boundary diffusion in the intermediate phase in which the principle diffusion processes occur. Phase growth showed a parabolic dependence on time and an Arrhenius plot enabled an activation energy of 1.01 eV to be established for the growth process.

Surface segregation in a dilute copper–silver alloy

The equilibrium surface composition of a Cu-0.83 at. % Ag alloy has been studied over the range from 600°–400°C. Above 450°C the alloy consists of a single phase, whereas below that temperature the material separates into copper-rich and silver-rich phases. The kinetics of equilibration appear to be controlled by grain boundary diffusion, leading to more rapid equilibration than expected on the basis of lattice diffusion-controlled kinetics. In the single-phase regime, silver segregates to the surface with an average enthalpy of segregation of −24 kJ/mol and an entropy of segregation of 0.94 J/mol K, and displays a trend of increasing equilibrium silver surface concentration with decreasing temperature. Theoretical estimates of the enthalpy of segregation yield the somewhat more negative values of −60 and −47 kJ/mol, respectively. In the two-phase regime, the surface continues to be enriched in silver, but the silver surface concentration decreases with decreasing temperature as a result of the rapidly decreasing equilibrium solubility of silver in copper.

The solubility of gold and silver in the system AuAgSO 2H 2O at 25°C and 1 atm.

During supergene alteration of auriferous carbonate ore, the weathering fluids formed are likely to be alkaline and therefore unsuitable as a medium for gold transport as a chloride complex. Secondary gold remobilization in such deposits can often be attributed instead to gold complexing by sulphur-bearing ligands. Gold and silver solubility in the systems AuSO 2H 2O and AgSO 2H 2O respectively, from the thermodynamic data available, is due to complex formation with thiosulphate and bisulphide ligands. The most stable gold complexes, Au(S 2O 3) 2 3− (at φO 2 > 10 −60) and Au(HS) − 2 ( atφO 2 < 10 −60), exist in neutral or alkaline solutions. Like gold, silver forms a stable thiosulphate complex, Ag(S 2O 3) 3− 2 in moderately oxidizing, and bisulphide complexes, AgHS 0 and Ag(HS) − 2 in reducing, alkaline media. Silver solubility in highly oxidized, neutral or acid solutions is increased by formation of AgS 2O 3 −, Ag + and AgSO 4 − complexes. Colloidal, crystalline and alloyed gold and silver reacted with 0.1 M Na 2S 2O 3 do not, however, demonstrate independent solubility. The rate of gold solubility in 0.1 M Na 2S 2O 3, for example, is increased both by the presence of silver-thiosulphate complexes and alloyed silver. It is possible that such behaviour is due to the formation a mixed metal complex of the type (Au, Ag)(S 2O 3) 2 3−. The nature and mineral association of secondary gold in the oxidized zone of carbonate ore at Wau. in Papua New Guinea, is consistent with prior remobilization as a thiosulphate complex. Here the secondary gold is coarsely crystalline, alloyed with 50–75 at% Ag and enriched at the watertable and with manganese dioxide in the oxidized zone.

Determination of the silver error in the coulometric titration of acids in various media

The dependence of the silver error in coulometric titrations of acids in a one-compartment cell on the solubility of silver halide has been established. The silver error is proportional to the total solubility of silver and inversely dependent on the current density. Because the main contribution to the total titration error is given by the silver error, it is necessary to choose conditions that produce the minimum value. The silver error is below 0.1% when the current density of the cathodic process is at least 10 mA cm–2. This relationship was tested in solutions of chloride, bromide and iodide in water, methanol, ethanol and acetone. For the aqueous solutions the bromide electrolyte is recommended and, for methanolic solutions, the best results are obtained with chloride ions.

The solubility of silver chloride in ferric chloride leaching media

The solubility of silver chloride in various FeCl 3-FeCl 2-HCl solutions has been measured over the temperature range 20–100°C; the densities of the associated saturated solutions have also been determined. The solubility increases systematically with either rising temperature or increasing concentrations of the constituent chlorides. The solubility is higher in a ferrous chloride medium than in an equivalent ferric chloride solution. The presence of CuCl 2 systematically raises the AgCl solubility, but increasing ZnCl 2 concentrations cause the solubility to decrease slightly to about 1.5 M ZnCl 2 and subsequently to increase gradually. The addition of NaCl to the iron chloride media substantially increases the AgCl solubility under all conditions. Although the solubility of AgCI is only a few mg/L in cold water, this increases to over 1 g/L in hot, moderately concentrated chloride media. Silver chloride solubilities at elevated temperatures are sufficiently high that silver solubility limitations should not be a problem in most commercial ferric chloride leaching processes.

Thermodynamics of Ag0-Solvation in Molten Silver Halides, Doped with Metal Halides

From the temperature dependence of the solubility of silver in its molten halides, the thermodynamic functions ΔHsolv and ΔSsolv are calculated. They depend strongly on the presence and concentration of mono- and divalent cations. A possible structure breaking effect of these ions is discussed.

Al中のAgの固溶限への高圧力の影響

Reaction-diffusion experiments of aluminium and silver have been done under high pressure up to 3 GPa at temperatures between 729 K and 873 K. The eutectic reaction temperature of 839 K rises with increasing pressure. The solubility of silver in aluminium decreases with pressure, but the concentration of ζ phase at the interface between ζ and α phases is independent of pressure. The excess enthalpy of mixing for α solid solution increases with pressure.

The solid solubility of silver, gold and zinc in metallic tin

In other studies [1], it has been found that dilute tin alloys containing one of the fast-diffusing solutes Ag, Au and Zn display marked but transitory increases in hardness when quenched from near eutectic temperatures. In this paper, it is shown that an examination of such hardness increases as a function of solute concentration and the equilibrium temperature prior to quenching provides a means of determining the solvus boundaries for the system concerned. Solvus data is derived for Ag, Au and Zn in Sn.

Solubility and complex ion equilibria of silver(I) species in aqueous solution

The sequential formation of precipitates and complex ions is used to demonstrate how the solubility of silver(I) compounds is related to Ksp values.

The solid solubility of silver in lead

The solid solubility of silver in lead

The solubility of silver in aluminum

The solubility of silver in aluminum