Proposal of flame synthesis method for nanoparticles using flash boiling spray (Discussion of condition to form anatase phase particle)

Abstract

In this study, the novel flame synthesis method using flash boiling spray is proposed in order to form the homogeneous characteristics nanoparticle. In this method, the precursors are injected and the injected precursors are evaporated by flash boiling. The evaporated precursors form vapor and the nanoparticles are formed at high temperature with flame. The factors for homogeneous characteristics of nanoparticles are precursor, flash boiling spray, flame characteristics and nozzle. These factors affect each other and affect to the nanoparticle characteristics as diameter distribution and crystal characteristics. It is necessary to optimize these factors to form homogeneous characteristics particles. In the previous study, TiO₂ nanoparticles were formed and the relationship between the flame and injection characteristics, and the particle characteristics were investigated. From the result, the equivalence ratio affects to the nanoparticle crystal characteristics and injection condition affect to the particle diameter and mass fraction of anatase phase. In this paper, TiO₂ nanoparticles were produced and the particle property influenced by ambient pressure and particle trapping position is investigated. As the result, the mass fraction of TiO₂ anatase phase decreases by increasing ambient pressure. The rutile phase is formed at the short nanoparticle trapping position. The factors such as precursors, injection condition and fuel/oxygen flow ratio for producing the anatase phase particle in this method was discussed.