Abstract：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 of SEM, 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.

Keywords：growth mechanism; spherical silver powders; liquid reduction method