Preparation and characterization of different morphological silver colloids by ultrasonic field

In order to study the influence of preparation techniques on stability of different morphological silver colloids, stable silver colloids were produced by the reduction of AgNO3 with the protection of polyvinylpyrrolidone (PVP) using KBH4 and N2H4&middotH2O as reductants. The silver colloids were identified by transmission electron microscope (TEM) and Spectrophotometer. The results indicate that the factors, such as distribution of the ultrasonic field, ultrasonic time, ultrasonic power and the species of reductant, make great impact on morphology of silver nanoparticles. The size of silver nanoparticles decreases with the increase of ultrasonic power and ultrasonic time. The silver nanoparticles prepared in the standing wave field grow along a certain direction. The standing wave field is beneficial to the formation of hexagonal and spherical-like silver nanoparticles. Mono-dispersed spherical silver nanoparticles are easily synthesized in the diffusion field. The stability of silver colloid becomes better after ultrasonic treatment. The silver nanoparticles are big spherical-like and hexagonal without ultrasonic. Well-dispersed spherical silver particles with the mean size of about 20 nm are prepared after ultrasonic treatment. Precipitation is not found after several weeks deposited of silver colloid with ultrasonic treatment 180 min. Spherical, spherical-like and hexagonal silver nanoparticles are prepared with the change of reductants.