Formation and Oriented Aggregation of Tabular Hexagonal Silver Particles

Silver tabular hexagonal particles (<diagonal> = 200 nm) were prepared at 40 oC by the reduction of silver nitrate with ascorbic acid in a solution of a polynaphthalene sulphonic dispersant agent, Daxad 19, in strong acidic conditions. By varying the reaction temperature and thus the dispersion viscosity between 10 oC and 30 oC, mesostructures of silver flat rods and flakes were obtained, the former resulting from linear aggregation of tabular hexagonal particles and the latter formed by intertwined flat rods. The results indicate an easy way to tune the aggregation of particles to obtain ordered mesostructures.