Preparation and Formation Mechanism of Silver Particles with Spherical Open Structures

A new type of highly dispersible silver particles has been developed consisting of two- and three-dimensional building blocks that form spherical shapes with open structures. The first morphology consists of uniform particles that are composed of anisotropic building blocks mainly in the form of a network of platelets forming a spherical, open-structured particle. These platelets are 100–2000 nm in length, with a crystallite size in the range 20–100 nm. The second morphology consists of isotropic components that are 100–500 nm in length, with a crystallite size in the range of 20–100 nm. In both cases, the silver powder was comprised of well-defined monosized particles and was highly dispersible. These powders were prepared by rapidly mixing a silver solution with an ascorbic acid/sodium citrate solution at low pH. A mechanism is proposed for the formation of these novel structures.