Preparation of Nanometer-sized Silver Powder by Polymer Protection Method

Spherical silver powder with the diameter of 30～100nm and the grain size dis-tribution of 1.3～1. 5 was prepared using the reduction reaction of silver nitride by hydrazinehydrate with polyvinyl pirrolidone(PVP ) protection. The influences of mole ratio of hy-drozine/AgNO_3 ,mass ratio of PVP/AgNO_3,reduction time and temperature ,seed addition onsilver particle size particle aggregation and size distribution were investigated. The silvonpowder yield was about 99. 99% only at the reaction time more than 20 min,and the mole ra-tio of hydrozine/AgNO_3 more than 6.Higher reaction temperature and seed addition were fa-vorable to form smaller silver particles. The key issue for the silver particle size and aggrega-tion was the mass ratio of PVP/AgNO_3. The nanometer sized silver powder without any ag-glomerates was obtained in the case of PVP/AgNO_3≥1,whereas the powder containing largeaggremerators with irregular shapes was found,if the PVP/AgNO_31 was kept.