超声场下不同形貌银胶体的制备与表征

为了研究制备工艺条件对不同形貌银胶体稳定性的影响,在超声场作用下,以AgNO3为前驱物,聚乙烯吡咯烷酮为保护剂,KBH4和N2H4·H2O分别为还原剂,制备了稳定的银胶体,并利用透射电镜和分光光度技术对制备的银胶体进行了表征．结果表明,超声场分布、超声作用时间、超声功率和还原剂种类等对银纳米粒子形貌影响较大．未经超声处理的银胶粒为较大的类球形和六边形,随着超声作用时间和超声功率的增加,颗粒变小．驻波场下制备的银颗粒具有一定的生长取向,有利于类球形和六边形银纳米颗粒的形成,而在扩散场中得到单分散的球形银纳米颗粒．经超声场处理的银胶体稳定性增强,主要以单分散的球形纳米颗粒存在,平均粒径约为20 nm,放置数周后未出现聚沉物．改变还原剂的种类,可制备出球形、类球形和六角形银纳米颗粒．

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 polyvinylpyrroli-done(PVP) using KBH4 and N2H4 ----------- H2O 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.