Solubility Of Silver Research Articles

The atypical solubility of silver(i) pentafluorobenzoate and its use as a catch-and-release agent

The atypically good solubility of (AgCO2C6F5)n reversibly forms crystalline adducts with liquid substrates (including chiral natural products) for SCXRD analysis.

Geochronology, pyrite trace elements, and in-situ S isotopes of the giant Nagengkangqie’er silver deposit in the Eastern Kunlun Orogenic Belt, Northern Tibetan Plateau

The Nagengkangqie'er (Nageng) silver deposit, situated in the Eastern Kunlun Orogenic Belt (EKOB), Northwestern China. It contains 5,070 tons of contained silver at a silver grade of 325 g/t. Nonetheless, the genesis of the Nageng silver deposit is still under debate, due to the absence of definitive constraints the mineralization age and the metal sources. The U-Pb data analysis of a post-ore calcite vein established the minimum age of the mineralization at 207 ± 3 Ma, whereas the maximum age of 217 ± 4 Ma was determined from zircon U-Pb data obtained from the altered and mineralized rhyolitic porphyry host-rock. These temporal limitations suggest that the mineralization formed at ca. 217–207 Ma, and it is associated with the post-collisional setting of the Paleo-Tethys evolution in the EKOB. The distinct textural patterns, as revealed by petrographic observations, suggest three types of pyrites: py1 is composed of euhedral pyrite in the early barren quartz vein at stage 1, py2 is represented by subhedral-anhedral grains in massive ore veins at stage 2, and py3 forms euhedral crystals of varying sizes, which are interspersed with early-formed marcasite in the quartz + calcite + silver-bearing sulfosalt-dominated veins at stage 3. In-situ δ34S values of pyrites range between −2.33 ‰ and −0.37 ‰, indicating a dominantly magmatic origin. EPMA studies have revealed that silver in the Nageng deposit predominantly occurs as silver-bearing galena at stage 2, whereas silver is enriched in sulfosalts of stage 3. From py1 to py3, a decrease in the Co-content indicates a decrease in the ore-forming fluid temperatures. The presence of stage 3 sulfide, sliver-bearing sulfosalt, and calcite-quartz in a fracture-filled vein indicates low-pressure conditions during its formation, compared to stages 1 and 2. In summary, the Nageng deposit is a typical magmatic-hydrothermal vein-type Ag-Pb-Zn deposit. Fluid cooling and decrease in pressure, coupled with decreases in fO2 and fS2, are the parameters inferred to have led to a decrease of silver solubility in the hydrothermal fluids and, successively, promoted extensive Ag deposition.

Solubility of Silver in Liquid Cesium and Thermodynamic Properties of the Solutions

Solubility of Silver in Liquid Cesium and Thermodynamic Properties of the Solutions

A Novel Method for the Fabrication of Antibacterial Stainless Steel with Uniform Silver Dispersions by Silver Nanoparticle/Polyethyleneimine Composites.

Only a few studies have so far focused on the addition of silver to SS316L alloys by conventional sintering methods. Unfortunately, the metallurgical process of silver-containing antimicrobial SS is greatly limited due to the extremely low solubility of silver in iron and its tendency to precipitate at the grain boundaries, resulting in an inhomogeneous distribution of the antimicrobial phase and loss of antimicrobial properties. In this work, we present a novel approach to fabricate antibacterial stainless steel 316L by functional polyethyleneimine-glutaraldehyde copolymer (PEI-co-GA/Ag catalyst) composites. PEI is a highly branched cationic polymer, which makes it exhibit very good adhesion on the surface of the substrate. Unlike the effect of the conventional silver mirror reaction, the introduction of functional polymers can effectively improve the adhesion and distribution of Ag particles on the surface of 316LSS. It can be seen from the SEM images that a large number of silver particles are retained and well dispersed in 316LSS after sintering. PEI-co-GA/Ag 316LSS exhibits excellent antimicrobial properties and does not release free silver ions to affect the surrounding environment. Furthermore, the probable mechanism for the influence of the functional composites on the enhancement of adhesion is also proposed. The formation of a large number of hydrogen bonds and van der Waals forces, as well as the negative zeta potential of the 316LSS surface, can effectively enable the formation of a tight attraction between the Cu layer and the surface of 316LSS. These results meet our expectations of designing passive antimicrobial properties on the contact surface of medical devices.

COUPLED SOLUBILITY OF Cu and Ag IN CHLORIDE-BEARING HYDROTHERMAL FLUIDS (350-650 °С, 1000 - 1500 BAR)

The coupled solubility of Cu(cr) and Ag(cr) was measured in acidic chloride solutions at 350 °С/1000 bar, 450 °С/1000 bar and 653 °С/1450 bar in a wide range of chloride concentrations (0.02m HCl + (0-15m) NaCl). The experiments were performed using autoclave (350, 450 °С) and ampoule (653 °С) techniques, the dissolved metal concentrations were measured after quenching the experimental system. The equilibrium constants of the reaction combining the dominant forms of transport of the metals are determinedCu(cr) + AgCl2- = Ag(cr) + CuCl2- K°(Cu-Ag) . The calculated reaction constant is independent of chloride concentration. It is known that AgCl2- predominates in the studied chloride concentration range. Therefore, the main cupper form of occurrence is CuCl2- in all experimental fluids with chloride content up to 47 wt.%, which is close to the NaCl saturation limit. The constant of the coupled Cu and Ag solubility was determined for the experimental PT-parameters as lg K°(Cu-Ag) = 2.65±0.20 (350 °С/1000 bar), 2.28±0.10 (450 °С/1000 bar), 1.49±0.34 (653 °С/1450 bar). These data, together with values from the literature for temperatures from 200 to 900 °С and pressure up to 2000 bar were fitted to the density model equation: lg K°(Сu-Ag) = 1.066 + 1.108∙103∙T(K)-1 + 3.585lgd(w) – 1.443∙lg d(w)103T(K)-1, where d(w) is the pure water density. According to these data, copper is much more soluble in chloride solutions compared to silver, but the difference in the solubility decreases with the temperature increase. Reliable literature data on the silver solubility constant allow to calculate the copper solubility oneCu(к) + HCl° + Cl- = CuCl2-+ 0.5H2(р-р) K°(Cu) ,lg K°(Cu) = 1.39±0.20 (350 °С, 1000 bar), 1.91±0.10 (450 °С, 1000 bar), 2.06±0.34 (653 °С, 1450 bar). The new values of K°(Cu) are combined with reliable literature data to calculate the density model parameters. The obtained density model equation can be used to calculate the copper solubility constant up to 800 °C and pressures to 2000 bar: lg K°(Сu) = 6.889 – 3.298∙103∙T(K)-1 + 8.694∙lg d(w) – 4.807∙lg d(w)∙103∙T(K)-1. The solubility of chalcopyrite in the system with mineral buffer assemblages pyrite-hematite-magnetite and K-feldspar-muscovite-quartz is discussed.

Investigating the structure, solubility, and antibacterial properties of silver- and copper-doped hydroxyapatite.

Hydroxyapatite (HA) powders were synthesized by the wet precipitation method in which two experimental compositions were synthesized (10mol% Ag-HA and Cu-HA) where the CaNO3 content was partially substituted with AgNO3 and Cu(NO3 )2 . X-ray diffraction (XRD) was employed to characterize changes to the HA structure as the dopants (Cu2+ , Ag+ ) were incorporated into the materials structure. Energy-dispersive X-ray spectroscopy (EDS) determined confirmed the compositions and found that the Ca/P ratio was 1.63 for the control (HA) while Ag-HA and Cu-HA exhibited (X + Ca)/P ratios of 1.79 and 1.65, respectively. Antibacterial efficacies were evaluated against E. coli and S. aureus, as a function of surface area and incubation time. The more prominent antibacterial effects were observed with both Ag-HA and Cu-HA and the materials antibacterial influence was maintained with respect to time. Ion release studies of each HA composition (15, 30, and 45 days) showed that Cu-HA released significantly more Cu2+ (36.1 ± 5.1mg/L) than Ag+ (2.9 ± 1.2mg/L) from Ag-HA. Analysis of each composition incubated in simulated body fluid (SBF) exhibited surface depositions that are likely calcium phosphate (CaP). Cytocompatibility testing in MC 3T3 Osteoblasts showed slight reductions in cell viability when tested using MTT assay, however cell adhesion studies were positive for each composition.

Research on Mechanical and Electrical Properties of Cu-Ag Alloys Designed for the Construction of High Magnetic Field Generators

The individual sections, wiring and construction of electromagnet windings responsible for strong magnetic field impulses may be one application for hypoeutectic Cu-Ag alloys. High electrical properties and mechanical properties (tensile strength, yield strength, impact strength) as well as high heat, fatigue and rheological resistance are required for these kinds of applications due to the unique nature of such operations (strong vibrations of high frequency and amplitude resulting from Lorenz forces and the possibility of significant and rapid heating from Jule’s heat). The limited solubility of copper and silver in the solid state enables the effective modification of the alloys’ microstructure through heat treatment and further shaping of their high mechanical and electrical properties via cold plastic working. The article presents the manufacturing of Cu-Ag alloys with the weight percent of Ag between 3 and 7 using the continuous casting process along with research on the physicochemical, mechanical and electrical properties of the obtained casts. The research on the amount of plastic deformation and its influence on the wire drawing process and the mechanical and electrical properties of the wires is also discussed. The temperature coefficients of resistance were defined in order to determine the temperature influence on the electrical resistance changes dynamics. The microstructural analysis was carried out in the as-cast state. The preliminary research conducted indicates that the obtained Cu-Ag alloys in the as-cast state exhibit a set of high mechanical and electrical properties. The prospective next stage of research includes the selection of favourable heat treatment parameters which would provide optimally modified microstructure of the alloys, as well as determining the deformation coefficients allowing for further increases in the mechanical and electrical properties.

Silver complexation in chlorine- and sulfur-rich hydrothermal fluids: Insight from ab initio molecular dynamics simulations

Silver (Ag) is a precious metal and has been widely used in a variety of high-technology areas, and it is mainly mined from the various of hydrothermal deposits. To quantify changes of silver solubility in hydrothermal fluids, many previous studies were focused on the thermodynamic properties of silver complexation with single ligands under different P-T conditions. Recent studies have revealed that the mixed complexes of metals (including Au, Ag and Cu) are of great significance in improving their transportation efficiency. However, the behavior of mixed silver complexes is not substantially constrained by different ore formation conditions. In this study, eight ab initio molecular dynamics (MD) simulations were designed to investigate the stoichiometries and relative stabilities of AgCl(HS)− and Na[AgCl(HS)] complexes in solution boxes containing various Cl− and HS− concentrations within the temperature range 25 to 900 °C and under pressures above the water-saturation pressures. The results revealed that the AgCl(HS)− and Na[AgCl(HS)] complexes remained relatively stable at temperatures between 25 and 600 °C and 900 °C, respectively. The complexes were distorted linearly, and the degree of distortion increased with increasing the solution temperature. The thermodynamic properties of the AgCl(HS)− and Na[AgCl(HS)] complexes were obtained using ab initio thermodynamic integration under T-P conditions corresponding to those of MD simulations. The logK values for the formation of the AgCl(HS)− complex at 25–600 °C were obtained for the first time.Ag+ + Cl− + HS− = AgCl(HS)−The logK values for this reaction at 25 °C, 200 °C, 350 °C, and 600 °C were 13.12, 10.52, 10.46 and 10.13, respectively. The logK value for the formation of the Na[AgCl(HS)]− complex at 900 °C was obtained to compare it with that of a the previous study.Ag+ + Cl− + HS− + Na+ = Na[AgCl(HS)]The standard Gibbs energy for formation of Na[AgCl(HS)] complex in our study is highly consistent with that in a the previous report from Yin and Zajacz (2018). In addition, the newly obtained thermodynamic properties for the AgCl(HS)− complex were then used to build equilibrium models, which suggested that the stability of the AgCl(HS)− complex increases progressively with increasing temperature. Water-rock interaction modeling with and without the addition of this mixed-ligand complex indicated that the AgCl(HS)− complex plays at most a minor role in the transport of silver at temperatures below 200 °C but could be a predominant complex of silver in geofluids at elevated temperatures.

Rapid Ag diffusion in granitic melt: Implications for Ag mineralization and melt inclusion record

Element diffusion in silicate melts is an important process in the transport and enrichment of metals in magmatic and magmatic-hydrothermal systems, but the diffusivity of Ag, unlike other metals such as Cu, Mo, and W, is still unknown. In this study, Ag diffusion in granitic melts with up to 6.9 wt% H2O was investigated at 973–1673 K and 0.1–1 GPa in a piston cylinder apparatus and a cold seal vessel, using both a diffusion couple approach and an argentite (Ag2S) dissolution approach. Silver concentration profiles were analyzed by LA-ICP-MS on recovered samples. Silver solubility, determined by Ag concentration at melt-argentite interface, increases with increasing temperature. Silver diffusivity is found to increase with increasing temperature and water content but to decrease with pressure. At 1 GPa, Ag diffusivity in granitic melt can be described by the following expression:lnDAg,1GPa=-13.77±0.46-13341±534-700±39wTwhere D is Ag diffusivity in m2/s, w is the water content in wt%, and T is the temperature in K. The pressure effect over 0.1–1 GPa gives an activation volume of 11.3 cm3/mol for Ag diffusion. While not being on a par with the mobility of Na and Li, Ag diffusion is among the most rapid, comparable to Cu and faster than other species including H2O and Fe. This implies that Ag diffusion in melt is unlikely to be a rate-limiting step for Ag enrichment into exsolved fluid bubbles or sulfide blobs. Furthermore, melt inclusions in silicate minerals are expected to record Ag concentration in the bulk melt instead of an elevated concentration in the presence of an Ag-rich boundary layer. Our Ag diffusivity data also suggest that a few tens of hours are long enough to homogenize Ag concentration in melt in solubility or partition experiments at temperatures above 800 °C.

Silver Solubility in Supercritical Fluids in a Wide Range of NaCl Concentration (0.6–50 wt %)—Experimental and Thermodynamic Description

The solubility of Agcr has been measured in a 0.1m (mol·(kg H2O)−1) solution of HCl at a fixed hydrogen content (∼0.5m) as a function of NaCl concentration from 0.1 to 18m at temperatures ranging f...

High pressure torsion of Cu–Ag and Cu–Sn alloys: Limits for solubility and dissolution

The high-pressure torsion (HPT) of binary copper alloys with 3, 5, 8, 10 wt. % Ag and 14 wt. % Sn has been studied at room temperature THPT. Before HPT, the Cu–Ag alloys have been annealed at 12 different temperatures between 320 and 800 °C and Cu–14 wt. % Sn has been annealed at 9 different temperatures between 310 and 500 °C. Thus, before HPT the Cu–Ag alloys consisted of Ag-particles in the Cu-based matrix with silver content cinit from almost zero to 8 wt.%. The Cu–14 wt. % Sn samples had Cu-based matrix with tin concentration cinit from almost zero to 14 wt.% Sn and precipitates of ε or δ Hume-Rothery intermetallic phases. After about 1.5 plunger rotations a certain steady-state concentration css of the alloying element is reached in the matrix. The measured css values were 5.5±0.1 wt. % Ag and 13.1±0.1 wt. % Sn. If the initial concentration cinit in Cu matrix was below css (cinit < css), it increased towards css during HPT. If cinit > css it decreased towards css. We observed that css did not depend on cinit in broad interval of cinit and was, therefore, equifinal. The equifinal css values corresponded to the certain equilibrium solubilities of silver and tin in Cu matrix and allowed to estimate the (elevated) effective temperature as Teff (Ag) = 700±10 °C and Teff (Sn) = 400±10 °C, respectively. The observed phenomena are discussed using the ideas of non-equilibrium thermodynamics of open systems. During HPT the decomposition of a solid solution competed with dissolution of precipitates. As a result, a dynamic equilibrium established between precipitation and dissolution at steady-state deformation stage. In this dynamic equilibrium a certain steady-state concentration css of the alloying element is reached in the matrix. In Cu-based alloys, the obtained Teff is always higher than THPT and correlates with activation enthalpy of dopant diffusion in Cu. Other HPT-driven phenomena such as accelerated mass transfer, intermetallic phase formation, grain boundary faceting and grain boundary segregation are taken into account to evaluate the effective temperature Teff.

Divining gold in seafloor polymetallic massive sulfide systems

Hydrothermal fluids on the modern seafloor are important carriers of base and precious metals in a wide range of volcanic and tectonic settings. The concentrations and distribution, especially of gold and silver, in associated seafloor massive sulfide (SMS) deposits are strongly influenced by variable source rocks, fluid chemistry, and precipitation mechanisms. Compositional data of 130 SMS deposits around the world show a large range of gold and silver grades, in part reflecting strong buffering of the hydrothermal fluids by their host rocks. Geochemical reaction-path modeling shows that in most cases the investigated hydrothermal fluids are undersaturated with gold and silver, and solubilities can be orders of magnitude higher than the Au and Ag concentrations measured in the corresponding fluids. Precipitation of gold during conductive cooling of mid-ocean ridge black smoker (MOR) fluids occurs at low temperatures but can be very rapid, with > 90% of the gold deposited in the first 25 °C of cooling below ~ 150 °C. The result is a Zn–Au polymetallic assemblage with Au and Ag deposited at the same time together with Pb and sulfosalts. In ultramafic-dominated (UM) systems, the strongly reduced hydrothermal fluids promote the deposition of gold at higher temperatures and explain the correlation between gold and copper in these deposits. In this case, the lower stability of the AuHS° complex at low ƒO2 (buffered by fayalite, magnetite, and quartz) results in gold deposition at > 250 °C with early bornite and chalcopyrite and before sphalerite and silver, producing a high-temperature Cu–Au assemblage. In sediment-hosted (SED) systems, the much higher pH stabilizes Au(HS)2− and keeps gold in solution to very low temperatures, after the precipitation of chalcopyrite, sphalerite, and galena, resulting in Au-poor polymetallic sulfides and very late-stage deposition of gold, commonly with amorphous silica. In arc-related (ARC) systems, gold deposition occurs at somewhat higher temperatures than in the MOR case, in part because the fluids start with higher gold concentrations. This can be explained by probable direct magmatic contributions, and the high ƒO2 of the fluids, which promotes the solubility of gold at the source. During cooling, gold precipitates at about 160 °C with sphalerite, tennantite, silver, and galena, resulting in an Au-rich polymetallic sulfide assemblage. The mixing of hydrothermal fluids with seawater generally causes oxidation and eventually a decrease in the pH at a mixing ratio of 1:1, causing an initial increase in the solubility of gold and silver. This can delay gold deposition from aqueous species to very low temperatures. These complex systematics make prediction of Au and Ag grades difficult. However, important new data are coming to light on the actual concentrations of the precious metals in hydrothermal fluids. In particular, the input of magmatic volatiles and leaching of pre-existing gold can lead to significant increases in the Au and Ag concentrations of the venting fluids and earlier deposition. In several cases, it appears that at least part of the gold load is present as nanoparticles in suspension, allowing bulk gold concentrations that may be far in excess of liquid saturation. Boiling at the seafloor is now widely observed, even at great water depths close to the critical point of seawater. Model calculations of phase separation during boiling show the competing effects on gold solubility of H2, H2S, and CO2 partitioning into the vapor, which can result in highly variable gold-to-base metal ratios in the deposits. Flashing of the vent fluids into steam at high temperatures is also commonly observed and can lead to spectacular Au grades, with a strong Cu–Au association in the deepest and hottest vents.

Photoluminescence of Ag+ and Agn+m in co-doped Pr3+/Yb3+ fluorophosphate glasses: tuning visible emission and energy transfer to Pr3+/Yb3+ ions through excitation in different silver species

Here, we report the luminescence properties of Yb3+/Pr3+ dual-doped fluorophosphate glasses containing silver clusters. Through the solubility of silver into the glass system as function of its initial concentration, charged species characterized as Ag+ and Ag m n+ were formed and identified according to their absorption and emission spectral responses. By changing the transition metal concentration, multi-energy transfer mechanisms were observed between silver and Yb3+/Pr3+ co-doped glasses. The stabilization of silver species seems to be detrimental to the radiative processes of the rare earth ions under excitation at 444 nm (Pr3+3H4 → 3P0 absorption line). In other words, the main visible emissions of Pr3+ and the NIR emission of Yb3+ decrease with increment of Ag concentration. However, energy transfer occurs for large spectral range by the excitation of the silver species. In consequence, the visible and NIR emission could be activate in a broadband from ultraviolet to the blue part of the spectral region. These two observations highlight the competitive absorption processes and probabilities between the cationic elements and the interest to use the transition metal species as sensitizers to excite the rare earth elements.

The solubility of silver in magmatic fluids: Implications for silver transfer to the magmatic-hydrothermal ore-forming environment

Silver is a common and economically important constituent of many magmatic-hydrothermal ore deposits, yet little is known about its mobility during magma degassing. We performed experiments to determine the effect of various chemical components (NaCl, KCl, LiCl, HCl, CaCl2, H2S) on the solubility and speciation of Ag in high-temperature, low-density fluids (≈0.38–0.54 g/cm3). The experiments were conducted at T = 900 °C, P = 2000 bar and oxygen fugacity (fO2) of 0.5 log units below Ni-NiO buffer (NNO-0.5) in rapid-quench Molybdenum-Hafnium Carbide externally-heated pressure vessel assemblies. The fluid phase was sampled at run conditions by the entrapment of synthetic fluid inclusions (SFI) in in situ fractured quartz chips. As capsule material, Au97Ag2Cu1 alloy was used, which imposed an Ag activity of 0.005. The apparent Ag solubility, defined as the equilibrium concentration of Ag in the fluid phase at an Ag activity of 0.005, exponentially increases as a function of total chloride concentration in the NaCl-H2O and NaCl-HCl-H2O systems. In the mixed NaCl-HCl system, at a fixed total Cl concentration of 1 mol/kg (1 m) H2O and varying NaCl/HCl ratios, the apparent solubility of Ag reaches a maximum (432 ± 123 μg/g) at equal NaCl and HCl concentration (0.5 m each) and then decreases towards both end-members (1 m for NaCl or HCl) following a parabolic function. Apparent silver solubilities predicted using the HKF model and thermodynamic properties for traditional Ag-chloride and bisulfide complexes greatly underestimate the measured values. Model calculations suggest that instead of charged AgCl2−, a neutral NaAgCl2 species is the dominant dissolved Ag species in S-free, chloride-bearing fluids with the additional presence of NaAgHSCl in S-bearing fluids. Comparison of the solubility data in high-temperature fluids to measured Ag solubilities in silicate melts suggests that efficient Ag partitioning into magmatic fluids will only take place when the composition of the silicate melt is felsic enough (rhyodacitic to rhyolitic), similarly to the behavior of Cu but in contrast to that of Au.

Simple and rapid method for silver nanoparticles incorporation in polymethyl methacrylate (PMMA) substrates

Due to its antimicrobial properties, silver has been used in many areas of medicine and today silver nanoparticles have been incorporated into different biomaterials. The objective of this study was to implement a simple method for the incorporation of silver nanoparticles in polymethyl methacrylate substrates, to determine their mechanical properties, antimicrobial functionality and the solubility of silver incorporated. Using this approach an antimicrobial material can be obtained; the surface of a commercial polymethyl methacrylate (Opti-cryl®) was impregnated with silver nanoparticles (AgNps) using a spray deposition method (0.03% by weight). The antimicrobial activity of the material was evaluated using the Japanese industrial standard (JIS Z 2801) against Escherichia coli and Staphylococcus aureus. Inductively coupled plasma optical spectrometry (ICP-OES) was used to measure the solubility of the incorporated silver nanoparticles. Mechanical tests of flexural strength were performed to observe changes in mechanical properties. The antimicrobial results show that PMMA / AgNps has significant antimicrobial activity, showing better results for Escherichia coli. ICP-OES analysis suggests low solubility in silver nanoparticles. Mechanical tests showed a 1.6% increase in flexural strength for PMMA added with silver nanoparticles. The method presented for incorporating silver nanoparticles into PMMA and producing an acrylic antimicrobial substrate is easy and has the advantage of improving its mechanical properties.

Solubility of silver in the K–KCl melt at 850°C

The solubility of silver in K–KCl melts at 850°C is studied in varying the potassium content from 0 to 100 mol %. It is shown that the solubility linearly increases as the alkali metal content increases; the solubility of silver in potassium melt is 6.0 mol %.

Effect of Ag doping and isothermal aging on phase transformation in 2205 duplex stainless steel

Abstract In this study, 0.2 wt% Ag-doped 2205 duplex stainless steel (DSS) was adopted to investigate the relationship between secondary precipitates and aging temperature. Before aging, 2205-0.2Ag samples were homogenized at 1200 °C for 12 h to resolve other secondary phases. The eutectoid reaction of α → γ 2 + σ and the formation of intergranular γ 2 at the α/γ interfaces were observed after aging at 900 °C for 2 h. Notable quantities of α-ferrite transferred to the γ 2 , χ, σ, and Cr 2 N phases, resulting in decreases of α-ferrite content during 900 °C aging. Because of decomposition of α-ferrite under 800 °C aging, the considerable Cr eq /Ni eq ratio difference between α-ferrite/γ-austenite facilitated the formation of the γ′ 2 phase and its growth at the α-ferrite/γ-austenite interface. This also indicated that doping DSS with silver can benefit the precipitation of γ 2 phases from α-ferrite. Furthermore, α-ferrite transferred to γ-austenite and the merger of primary austenitic grains facilitated the stabilization of phase constitution. Because the mutual solubility of silver and iron is very low, liquid silver solidified and caused silver particles to distribute at the α phase, γ phase, and α/γ interface. Furthermore, the solubility of silver in α, γ, and γ 2 phases decreased progressively as the aging temperature decreased. Moreover, the behavior of secondary precipitates was not affected by silver doping in 2205 DSS.

Silver(I) Binding Properties of Organic Soil Materials Are Different from Those of Isolated Humic Substances.

The solubility of silver(I) in many soils is controlled by complexation reactions with organic matter. In this work we have compared the ability of isolated humic and fulvic acids to bind silver(I) with that of mor and peat materials. One new data set for Suwannee River Fulvic Acid was produced, which was consistent with published data sets for isolated fulvic and humic acids. The ability of soil materials to bind silver(I) was studied as a function of pH in the range 2.5-5.0, at a wide range of silver(I)-to-soil ratios (10(-4.2) - 10(-1.9) mol kg(-1)). By calibrating the Stockholm Humic Model on the humic and fulvic acids data sets, we showed that binding of silver(I) to both types of soil materials was much stronger (up to 2 orders of magnitude) than predicted from the silver(I) binding properties of the isolated humic materials. Thus, the approach taken for many other metals, that is, to model solubility in soils by using metal and proton binding parameters derived from isolated humic and fulvic acids, cannot be used for silver(I). One possible explanation for the discrepancy could be that silver(I) predominately interacted with various biomolecules in the soil samples, instead of humic- and fulvic-acid type materials.

Effect of silver on microstructure and antibacterial property of 2205 duplex stainless steel

In this study, 2205 duplex stainless steel (DSS) was employed to enhance the antibacterial properties of material through silver doping. The results demonstrated that silver-doped 2205 DSS produces an excellent bacteria-inhibiting effect against Escherichia coli and Staphylococcus aureus. The antibacterial rates were 100% and 99.5%, respectively. Because the mutual solubility of silver and iron is very low in both the solid and liquid states, a silver-rich compound solidified and dispersed at the ferrite/austenite interface and the ferrite, austenite, and secondary austenite phases in silver-doped 2205 DSS. Doping 2205 DSS with silver caused the Creq/Nieq ratio of ferrite to decrease; however, the lower Creq/Nieq ratio promoted the rapid nucleation of γ2-austenite from primary α-ferrite. After 12h of homogenisation treatment at 1200°C, the solubility of silver in the γ-austenite and α-ferrite phases can be increased by 0.10% and 0.09%, respectively. Moreover, silver doping was found to accelerate the dissolution of secondary austenite in a ferrite matrix during homogenisation.

Experimental constraints on gold and silver solubility in iron sulfides

Experiments were performed to determine crystallization of Fe,S-melts (pyriti≿ and troilitic with molar ratio S/Fe ratios of 2 and 1, respectively) containing traces of gold and silver at (Ag/Au)wt ratios varying from 10 to 0.1. The solid products were studied by optical microscopy, scanning electron microscopy, X-ray powder diffraction (XRD), microprobe analysis, and X-ray photoelectron spectroscopy (XPS) in order to reveal the concentration limits of “invisible” gold and silver in magmatic iron sulfides, and to determine the influence of sulfur on forms of precious metals in the Fe–S system with different Ag/Au ratios.Au–Ag phases do not form inclusions but instead concentrate on the grain boundaries in the synthetic pyrrhotite and troilite, while pyrite comprises micro- (1–5 μm) and macroinclusions of Au–Ag alloys and Au–Ag sulfides. In “pyriti≿” systems, the fineness of alloys increases from 650 to 970‰ and the composition of sulfides changes from acanthite (Ag2S) to uytenbogaardtite (Ag3AuS2) and petrovskaite (AgAuS) as the Ag/Au ratio decreases. The concentrations of “invisible” precious metals revealed in troilite were 0.040 ± 0.013 wt.% Au and 0.079 ± 0.016 wt.% Ag. Measured concentrations in pyrite and pyrrhotite were <0.024 wt.% Au and <0.030 wt.% Ag. The surface layers of iron sulfides probed with XPS were enriched in the precious metals, and in silver relative to gold, especially in the systems with Fe/S = 1, probably, due to depletion of the metallic alloy surfaces with gold. Au- and Ag-bearing iron sulfides crystallized primarily from melts may be the source of redeposited phases in hydrothermal and hypergene processes.