Abstract
Several shapes of BaSO4 particles were synthesized by the reaction of Ba(AOT)2 microemulsion with NaAOT microemulsion containing SO42– at differing [Ba2+]/[SO42–] mole ratios. BaSO4 nanofilaments were obtained under an excess of Ba2+ with the same mole ratio to that of Li and Mann (2000). A plasma replica SEM revealed that the nanofilaments were formed exactly in the microemulsion. Further excess Ba2+ resulted in the formation of short rags and thick spirals rather than nanofilaments. In contrast, fine particles were formed under a shortage of Ba2+. By addition of excess Ba2+ to the microemulsion after the generation of the fine particles under a shortage of Ba2+, whisker-like rods were obtained. These results suggest a new mechanism for formation of the whisker-like rods through an anisotropic aggregation of the fine particles.
