材料期刊网

在超声场作用下,以聚乙烯吡咯烷酮为保护剂,硝酸银为前驱物,经硼氢化钾还原制备了稳定的银胶体.研究了保护剂和还原剂用量、超声时间和超声功率等因素对银胶体稳定性的影响,利用透射电镜、选区电子衍射和分光光度等技术对制备的银胶体进行了表征.结果表明:银纳米粒子为面心立方(fcc)结构;PVP与AgNO3质量比为1:1时,PVP可有效保护银粒子,获得了球形颗粒;AgNO3与KBH4摩尔比为1:2时,可制得分散较好的直径约为20 nm的类球形银纳米颗粒;在超声场作用下,银胶体的分散性和稳定性增强.随着超声功率的增大,银纳米粒子直径变小,粒径分布变窄.超声50 min制得的银胶体主要以球形纳米颗粒形式存在,粒径在10 nm～20 nm范围内,稳定性好.

Well-dispersed Silver colloids are prepared from AgNO3 and KBH4 under the protection of polyvinylpyrrolidone (PVP) in the ultrasonic field. The main factors influencing on stability of silver colloids, such as the concentration of PVP and KBH4, ultrasonic time and power, are discussed. The silver colloids are characterized by TEM, SAED and Spectrophotometer.The result indicates that the stable silver nanoparticles are prepared with PVP/AgNO3 mass ratio of 1:1. Selected area electron diffraction pattern reveals that the silver nanoparticle is of face-centered cubic structure. Spherical-like silver nanoparticles with about 20 nm size are synthesized with AgNO3/KBH4 molar ratio of 1:2. The dispersion and stability of the silver colloid will be improved after ultrasonic wave treatment. The diameters of silver nanoparticles decrease and the particle size distribution becomes narrow with the ultrasonic power increase. Silver particles with 10～20 nm size and spherical shape have been prepared after 50 min of ultrasonic wave treatment.