Shape and Size Control of Barium Chromate Nanoparticles Using Reverse Micelle

Abstract

Shape and size control of barium chromate nanoparticles using water-in-oil microemulsion formed by anionic surfactant AOT was examined experimentally. As a result, nanowire, nanorod, and nanodot could be synthesized by changing the raw ion concentration and the addition of ethanol as a poor solvent, and the nanowire and nanorod were self-assembled. It has been shown that the aspect ratio of the generated particles decreased with increasing chromate ion concentration or adding more ethanol. In contrast, the aspect ratio was almost constant even if the barium ion concentration was changed. The surfactant AOT has selectively adsorbed on the crystal faces along the a axis and suppressed their crystal growth. Furthermore, the generated nanoparticles were self-assembled by hydrophobic interaction between the surface-anchored AOT molecules. In conclusion, it was clarified that the supersaturation ratio and the particle-surfactant interaction were important factors for controlling the shape and size of inorganic nanoparticles using microemulsion method.