Al₂O₃ nanoparticles have been prepared by polyethylene glycol octylphenyl ether (Triton X-100)/n-butyl alcohol/cyclohexane/water reverse microemulsion. The result of thermal analysis of the precursor products showed that the proper calcination temperature was 1150 ℃. The structures and morphologies of Al₂O₃ nanoparticles were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM) and UV-vis spectrophotometry. The influences of molar ratio of water to surfactant (ω_o), calcination temperature and heating rates on the morphologies and sizes of the product were studied, and the formation mechanisms in the reverse microemulsion were also discussed. The results show that the obtained Al₂O₃ powder has no obvious agglomeration and narrow particle size distribution under the condition of ω_o＝10, T＝1150 ℃, and heating rate of 2 ℃/min is propitious to the phase change of a stable α-Al₂O₃.

Key words: reverse microemulsion, Al₂O₃, nanoparticle, formation mechanism