液相还原法制备超细球形银粉的生长机理

摘要

以抗坏血酸为还原剂,硝酸银为反应前驱体,通过对液相体系分时间段取样研究液相还原法制备超细球形银粉的生长机理.借助扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱(EDS)仪、X射线衍射(XRD)仪、紫外吸收光谱(UV-Vis)仪和颗粒图像分析仪对银粉进行表征和分析.结果表明,以抗坏血酸还原硝酸银制得了平均粒度为0.543 μm,球形度为0.926,分散良好的超细球形银粉;该氧化还原反应可自发进行,使被还原的银原子达到过饱浓度形成银原子团簇和细小的银晶核,银晶核主要以原子扩散控制生长和晶核聚集两种方式长大,最终获得表面自由能较小、粒度分布均匀的球形银粉.%With ascorbic acid as reductant,AgNO3 as reaction precursor,the growth mechanism of ultrafine spherical silver powders prepared by liquid-phase reduction method was investigated through sub-time sampling and characterization in the liquid phase system.Particles were characterized and analyzed by means ofSEM,TEM,XRD,UV-Vis and particle image analyzer.The results show that average particle size of 0.53 μm,a sphericity of 0.926,well dispersed crystalline silver powders are prepared by the reduction of silver nitrate with ascorbic acid.The oxidation-reduction reaction can be carried out spontaneously so that the reduced silver atoms reach supersaturated concentration to form clusters and small silver crystal nucleus.Silver nucleus grow up mainly in two ways of atomic diffusion controlled growth and nucleus aggregation growth to obtain more uniform spherical silver powders with smaller surface free energy.