Characteristics of Synthesized Alumina Nanoparticles in a High-Pressure Radio Frequency Thermal Plasma Reactor

摘要

Nanophase alumina is synthesized in an atmospheric pressure radio frequency (RF) plasma reactor through melting, evaporation, and vapor phase nucleation technique. A specially designed high-pressure RF plasma reactor fitted with an indigenously built RF plasma torch converts commercially available micrometer size alumina chunks into spherical nanophase alumina in a single step under ambient quenching conditions without use of any additional quenching gas. Obtained powder contains mixed phases of $alpha$ and $delta$ -alumina as revealed by X Ray Diffraction studies. Transmission Electron Microscopy analyses exhibit very small particle size (peak at 15 nm), narrow size distribution (half width ${sim}{rm 24}~{rm nm}$), zero agglomeration, and good crystallinity. Obtained particle characteristics together with the high purity owing to inherent electrode-less feature of the RF discharge are suitable for important technological applications including fabrication of high-power ceramic laser gain media like ${rm Y}_{3}~{rm Al}_{5}{rm O}_{12}$ (YAG) from composites of ${rm Al}_{2}{rm O}_{3}$ and ${rm Y}_{2}{rm O}_{3}$. Characteristics of the synthesized alumina are compared with that of nanoalumina synthesized in atmospheric arcs.