Quantitatively Relating Diffusion and Reaction for Shaping Particles

Chemical diffusion and reaction rates are two general kinetic factors involved in the formation of materials. They play an important role in the structure development of materials. In most cases, chemical diffusion and reaction are coupled each other, which makes it difficult to differentiate their effects in shaping materials. Here we propose to quantify diffusion and reaction by the Damkohler number (Da) and to elucidate their roles in shaping particles. Silver particles are synthesized by electrodeposition approach at different reaction and diffusion conditions. Both diffusion efficiency and reaction rate constants are quantified, and the Damkohler number is calculated. If chemical diffusion or reaction is the rate-determining step in the formation of materials, simple structures, such as polyhedrons and irregular particles, are usually formed. When the interplay of diffusion and reaction dominates the structure development, complex structures, such as dendrites, are generated. The formation of each structure is closely related to Da values. On the basis of this finding, three growth modes of particles are put forward and evaluated by the following studies.