Synthesis and Characterization of Alumina Nanoparticles by Igepal CO-520 Stabilized Reverse Micelle and Sol-Gel Processing

Nanosized alumina powders have been prepared via reverse micelle and sol-gel processing. By stepwise hydrolysis using aqueous ammonia as the precipitant, hydroxide precursor was obtained from nitrate solutions dispersed in the nanosized aqueous domains of microemulsion consisting of cyclohexane as the oil phase, poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant, and an aqueous solution containing aluminium nitrate as the water phase. The synthesized and calcined powders were characterized by thermogravimetry-differential thermal analysis, transmission electron microscopy, and scanning electron microscopy. The XRD analysis showed that the complete transformation from γ -Al2O3 nanocrystalline to α-Al2O3 was observed at 1100°C. The resulting alumina nanopowder exhibits particle agglomerates of 135–200 nm in average diameter occur when they calcined at 1200°C. The average particle size was found to increase with increase in water to surfactant (R) molar ratio.