Papers by Keyword: Silver

Abstract: Coloring silver for decorative purposes and for applying identification marks is an important task. In this paper, we consider a method for coloring silver surfaces using VIS plasmonic response in laser-induced nanoparticles (NPs). An analysis was made of the resulted morphology and chemical composition of nanoparticles obtained with nanosecond laser pulses. The dependence of the size and distribution of silver NPs on the laser exposure parameters is determined. The developed color palette was characterized using colorimetric coordinates.

Abstract: A novel approach for the synthesis of graphene oxide silver alginate has been developed for the antibacterial performance. Graphene oxide (GO) was used as a supporting material towards formation of silver nanoparticle (AgNPs) by a rapid microwave irradiation on mixture of GO and silver complexes and layered on alginate film. The obtained nanocomposite were characterized by using Ultraviolet-visible spectroscopy (UV-Vis), Xray diffraction (XRD) to confirm the formation of GOAgAlginate. The surface morphological studies for the nanocomposite was done by using scanning electron microscope (SEM). Nanometer-sized AgNPs (an average diameter of about 70 nm) with spherical-shape structure loaded on the GO Alginate layer showed a good antibacterial towards E.Coli and Methicillin-resistant Staphylococcus aureus (MRSA).

Abstract: The paper studies applicability of individual particles of Ag-Cu nanoalloys as data bits in the next generation memory devices constructed on the phase change memory principle. To fulfill this task, the structure formation was simulated with the molecular dynamics method on cooling from the melt of Ag-Cu nanoparticles of the diameter of 2.0 – 8.0 nm of different chemical compositions (with copper content in the alloy from 10 to 50 percent), based on the modified tight-binding potential (TB-SMA). The authors investigated the influence of the size effects and the heat removal rate on the formation of the clusters structure. The investigation showed that different internal structures can be developed upon cooling from the liquid phase, so there were determined some criteria of their stability. Clusters with copper content of not more than 10% and diameters of more than 6.0 nm were isolated from the entire set of the considered particles.

Abstract: The processing conditions of the of electronic wastes are largely dependent on environmental standards and requirements. Modern technologies for processing electronic waste should meet the increased demand for metals as well as the requirements. Electronic wastes can be classified as hazardous materials, as household and industrial electrical devices, which contain components such as batteries, capacitors, cathode ray tubes, etc. Electronic waste can consist of a large number of components of various sizes, shapes and chemical composition. Some of them contain hazardous metals, including mercury, lead, cadmium. The presence of precious metals in electronic waste such as gold, silver, platinum, palladium, as well as non-ferrous metals (copper, nickel, zinc, tin, etc.) make it attractive for processing. In industry, both hydrometallurgical and pyrometallurgical methods are used to extract valuable metals from electronic waste. Applied technologies may have both advantages and disadvantages.

Abstract: Fusing of silver (Ag) nanoparticles synthesized in an aqueous system was observed at room temperature using halide solutions. The as-synthesized Ag nanoparticles have an average diameter of about 24 nm. After dispersing the Ag nanoparticles in a halide solution, a significant increase in particle size to about 188-197 nm was observed. The enlargement of particle size was accompanied by the increase in conductivity of the Ag nanoparticle ink. The resistance was reduced from 110 kiloohms to 35 and 9.3 ohms for the as-prepared and sintered Ag nanoparticles using NaBr and NaCl solution, respectively.

Abstract: The paper is devoted to the study of the influence of surface modification by catalysts on the gas sensitivity of a gas sensor. The sample for the study is a gas sensor crystal with dimensions of 1 × 1 mm², manufactured using microelectronic technology. Its design is represented by a film heater, two sensitive elements (SE) based on tin dioxide with the addition of 1 % at. Si (film thickness = 250 nm, the size of the SE area is 200 x 320 μm²) and contacts for the sensitive layer in the form of an interdigital platinum structure with a distance between contacts of 10 μm. It is established that doping increases the gas sensitivity and lowers the operating temperature.

Abstract: In the article, the authors examined the technological aspects of obtaining a functional alloy based on silver alloyed with chromium, zirconium, rhenium and rare earth elements (cerium, lanthanum, yttrium). A technology has been developed for producing powder from this alloy and nanostructured functional coatings based on it using the method of cold gas-dynamic spraying.

Abstract: The objective of this work was to recover gold and silver from the printed circuit board (PCB) of discarded mobile phones by thiourea leaching. Effects of thiourea concentration, leaching temperature, leaching time, and ferric ion (Fe³⁺) concentration on the recovery of gold and silver were investigated. The PCB was pretreated physically to reduce the thiourea consumption and enhance the leaching process. It was found that the percentage of gold leaching was higher than that of silver at different conditions studied. The highest percentages of gold (96%) and silver (90%) leachings were achieved with 20 g/L of thiourea and 8 vol% of Fe³⁺ at 4 h of leaching time and 25°C of leaching temperature.

Abstract: The ceramic fibers can be obtained from different techniques. Due to the technological development, searches are performed to improve the existing fibers. Thus, recent studies have enabled the development of an unprecedented synthesis route for the production of nanofibers, the Solution Blow Spinning (SBS). In this context, the present work proposes to develop silica nanofibers doped with silver by the SBS method, evaluating parameters such as: silver content and acidification of solutions. The fibers were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The results of XRD showed that the samples with 4% silver that were not acidified showed the most defined and intense characteristic peaks. The SEM showed the formation of fibers with diameters in the nanometer range independent of acidification or not of the solutions, with reduction of the agglomerates in the samples with 2% silver.

Abstract: Infection related to orthopedic implant surgeries is one of the significant postoperative complications. Recently, many studies have been conducted on silver-containing hydroxyapatite (AgHA) composites as antibacterial and osteoconductive biomaterials to prevent postoperative infection. In this study, we prepared 1 and 10 wt% Ag-containing carbonate hydroxyapatite composites (1AgCHA and 10AgCHA, respectively) by solid-phase reaction, and investigated the relation between the elution rate of Ag ions from the composites and the chemical or physical states of Ag in AgCHA. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that metallic Ag particles disappeared in 1AgCHA heated at 800°C, whereas they were distributed in 10AgCHA heated at all temperatures. The amount of A-type CO₃^2- group in AgCHA structure drastically increased at 800°C, but decreased with increasing amount of Ag. The lattice constant (a-axis) of hydroxyapatite expanded drastically when heated at 800°C, and with increasing Ag content, the extent of expansion of a-axis decreased as well as amount of A-type CO₃^2- in CHA. Moreover, after the 48-h elution test, the concentration of Ag⁺ released from 10AgCHA heated at 800°C was less than 0.1% of total Ag amounts, while 1AgCHA heated at 800°C released over 0.8% of total Ag amounts. The results indicate that Ag⁺ and CO₃^2- were substituted competitively into the Ca²⁺ and OH^- sites of HA, respectively, after heating at 800°C, and that the elution rate of Ag⁺ from the sites of Ag⁺-substituted CHA was faster than that from metallic Ag particles. A better understating of the elution behavior of Ag from AgCHA is important for controlling the physical and chemical states of Ag in composites.