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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20nm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50min制得的银胶体主要以球形纳米颗粒形式存在,粒径在10nm~20nm范围内,稳定性好。
Under the action of ultrasonic field, polyvinylpyrrolidone was used as protective agent, silver nitrate was used as precursor, and silver colloid was prepared by potassium borohydride reduction. The effects of the amount of protective agent and reductant, ultrasonic time and ultrasonic power on the stability of silver colloids were studied. The prepared silver colloids were characterized by transmission electron microscopy, selected area electron diffraction and spectrophotometry. The results show that the silver nanoparticles are face-centered cubic (fcc) structures. When the mass ratio of PVP to AgNO3 is 1: 1, PVP can effectively protect the silver particles and obtain spherical particles. When the molar ratio of AgNO3 to KBH4 is 1: 2, Spherical silver nanoparticles with a diameter of about 20 nm were prepared. The dispersibility and stability of the silver colloid were enhanced under the action of ultrasonic field. As the ultrasonic power increases, the diameter of silver nanoparticles becomes smaller and the particle size distribution becomes narrower. Silver colloids prepared by ultrasonic for 50min are mainly in the form of spherical nanoparticles with particle size of 10nm ~ 20nm and good stability.