Properties Of Silver Particles Research Articles

Effects of Operating Parameters on the Structural Properties of Silver Particles Synthesized by Chemical Reduction Using Poly(N-Vinylpyrrolidone)

In this study we report the preparation and characterization of fine silver microparticles by simple chemical reduction of silver nitrate using two types of bases and poly(N-vinylpyrrolidone) as protective agent. The influence of silver nitrate concentration and the nature and concentration of bases, on the properties of the silver microparticles was investigated. The structural characteristics of microparticles were determined using x-ray diffraction, scanning electron microscopy, and particle distribution analysis. It was noticed that the structure and the shape of silver microparticles depend on the base nature and the concentration of silver nitrate added to the base. It was also noted the absence of agglomerates in the powder prepared with PVP. This polymer not only serves as both coordinating agent and stabilizing one, but also plays an important role in controlling the size and shape of metal particles.

Optimization of the experimental conditions for the synthesis of micro-size monodisperse spherical silver powders using Box–Behnken design

Monodisperse and spherical micro-size silver powder, which has narrow size distribution and high purity, was prepared by using silver nitrate as metal source, L-ascorbic acid as reductant and sodium sulfate as dispersant. The aim of this paper was to study the simultaneous effects of pH (2–6), silver nitrate concentration [AgNO3] (0.25–0.75mol/L), dropping time td (5–15min) and their interactions on properties of silver particles. In order to detect factor interactions and optimize these parameters, Box–Behnken design of experiments (a response surface methodology) was used. Synthesized silver powders were characterized by a laser particle size analyzer (LPSA), a scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). After surveying the experiment data and regression analysis of the data, a mathematical model was derived for optimizing particle size. The optimum condition was: [AgNO3], 0.75mol/L; pH, 6; and td, 5min. The predicted particle size was 1.39μm and the experimental particle size was 1.38μm at the optimum condition, which showed that the model agreed well with the experimental data. It is found that the [AgNO3] and dropping time have a positive effect and the pH value has a negative influence on the particle size. The possible mechanism for the formation of novel spherical silver particles is explored.

Synthesis of high tap density spherical micro-size silver particles by liquid-phase reduction using response surface methodology

Mono-disperse and spherical micro-size silver particles with high tap density were prepared by using silver nitrate as metal source, ascorbic acid as reductant, sulfuric acid as dispersant and polyethylene glycol 4000 (PEG4000) as surfactant. The aim of this paper was to study the simultaneous effects of surfactant dosage (PEG4000/AgNO3 mass ratio), silver nitrate concentration [AgNO3], deionized water dosage in reductant solution, stirring rate and their interactions on properties of silver particles. For optimizing these parameters, irregular fractional factorial design of experiments was used. As-prepared silver particles were characterized by X-ray diffraction, scanning electron microscopy, laser particle size analyzer and tap density (tap density refers to the stacking density of particles after vibration compaction) meter. The results showed that silver particles were spherical, mono-disperse and with high tap density (>5.0 g/mL), average particle size of about 2–3 μm and narrow particle size distribution. By surveying the experiment results and analysis of variance, two mathematical models were obtained and optimized parameters were determined. Analysis of the variance demonstrated that the interaction of [AgNO3] and stirring rate were the most significant factor affecting particle size and PEG4000/AgNO3 mass ratio and [AgNO3] were main significant factors affecting tap density. The predicted particle size and tap density were respectively 2.5 μm and 5.065 g/mL while the experimental results were 2.52 μm and 5.108 g/mL, which indicated that the models were in good agreement with the experimental data.

Changes in the State of Silver Sol Particles after Low-Temperature Treatments

The influence of the low-temperature treatment of Ag hydrosol on the properties of silver particles was studied by electron absorption spectroscopy over the temperature range 77–230 K. Low-temperature treatment caused the aggregation of particles because of an increase in the number of defects on the surface of Ag observed as an increase in the damping coefficient of electron plasma oscillations. These processes depended on the temperature and initial concentration of disperse silver. Defect formation is explained taking into account the tunnel mechanism of the interaction of low-atomic mobile H+(H2O)nand OH-(H2O)nclusters with the surface of silver particles at low temperatures.