Preparation of ultrafine γ-Al2O3 particles in non-ionic water in oil microemulsions

Ultrafine γ-Al₂O₃ particles are synthesized in Triton X-100/n-hexanol/cyclohexane/water water in oil(w/o) microemulsion by mixing two separately prepared microemulsions containing Al(NO)₃ and (NH₄)₂CO₃ respectively. The ultrafine Al₂O₃ particles are characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) and their size and distribution are measured. The effects of water, surfactant and reactant concentrations on the particle size and distribution are studied. The results show that the particle size and distribution can be changed by varying the preparation conditions, and the size of the microemulsion droplets has a controlling effect on the size of the particles. A possible mechanism of ultrafine particles (UFPs) prepared by microemulsions is proposed.