Synthesis and characterization of spherical and mono-disperse micro-silver powder used for silicon solar cell electronic paste

Spherical and mono-disperse micro-silver powder, a kind of silver powder with controllable size and high tap density, was prepared by using silver nitrate as metal source, ascorbic acid as reducing agent and gum arabic as dispersant under traditional chemical reduction method. The result of SEM images shown the spherical and mono-disperse silver powder with average particle size of about 1–2 μm and narrow particle size distribution was obtained. By varying the concentration of the reactants, dosage of dispersant and the pH of the mixture solution of ascorbic acid and gum arabic, the silver particles showed different size, and different size distribution. It was also found that the morphology of silver particles could transform from sphere to polyhedron and the tap density of silver powder was increased with the prolonging of reactants mixing time.