Thesis (M.Eng.)--Chulalongkorn University, 2008

Recently, synthesis of ZnO nanaparticles has been widely interested because of their excellent properties in a semiconductor and a wide direct band gap of 3.37 eV which can apply to the several industrial applications such as electronics, pharmaceutical industry, and rubber industry. ZnO has various morphologies such as nanorod, nanotube and tetrapod. These morphologies lead to the difference in properties. ZnO could be synthesized by various methods. The commercial ZnO is mostly manufactured via the French process, which is a continuous process capable of producing high purity product. In this research, the effects of operating conditions on the size and the shape of ZnO nanoparticles were experimentally investigated. These parameters include evaporation temperature, nitrogen gas flow rate, oxygen concentration, amount of zinc vapor, and the oxidation time. From the experimental results, it could be clearly observed that size and morphology of the ZnO nanoparticles are strongly dependent upon mixing ratio of zinc vapor and oxygen gas. ZnO nanoparticles change from spherical shape to tetrapod shape when the evaporation or oxidation temperature is increased. The nanocombs were found when amount of zinc vapor was decreased and the multipods were found under the short oxidation time.