六方片状银粉的合成

Synthesis of hexagonal flake silver powder

以硝酸银为前驱物,过氧化氢为还原剂,在乙二醇(或乙醇)介质中,有分散保护剂PVP存在的情况下,通过控制H2O2/NH3和NH3/Ag不同的比例(摩尔比,MR),合成分散的球状单颗粒和六方片状银粉。本文着重考察了NH3/Ag、H2O2/Ag以及H2PtCl6/Ag对片状六方晶体银粉形成的影响。结果表明,在NH3/Ag<3 5情况下,得到的是<1 0μm的球状银粉。当NH3/Ag>3 5,且H2O2/NH3≥1时,得到厚度<0 1μm、最大投影面的长度为0 2～0 5μm的六方片状单晶体银粉。H2PtCl6是形成片状银的必要与关键条件,但不是充分的条件,PVP是形成单分散粒子的决定性因素。

The disperse spherical and hexagonal flake silver powders have been synthesized by the reduction of silver nitrate in ethylene glycol. Hydrogen peroxide was used as reducing agent and polyvinyl pyrrolidine (PVP) was used as protective agent. The influences of the ratios of NH3/Ag, H2O2/Ag and H2PtCl6/Ag on the formation of the hexagonal flake silver powders have been studied. The results show that the particle size of spherical silver powder is smaller than 1.0 μm when the ratio of NH3/Ag is less than 3.5. The hexagonal crystal flake silver powders with the thickness of less than 0.1 μm and the max diameter of 0.2-0.5 μm are available when the ratio of NH3/Ag is greater than 3.5 and the ratio of H2O2/NH3 is equal to or greater than 1 (M.R.). H2PtCl6 is absolutely necessary and PVP is crucial factor for the formation of monodisperse particles.