FACTORS AFFECTING THE SIZE OF AL_2O_3 NANOPARTICLES SYNTHESIZED BY SOL-GEL PROCESS

摘要

Aluminum oxide, Al_2O_3, nanoparticles were synthesized from alcoholic solution of Aluminum Chloride, AlCl_3, and ammonia via sol-gel process. Molar ratio of NH_3: AlCl_3 has been changed to control the size of the resultant nanoparticles. The structures of Al_2O_3 nanoparticles were investigated and confirmed using Fourier Transform Infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), and their morphology was studied via high resolution transmission electron microscopy (HR-TEM). The HR-TEM images showed that the Al_2O_3 nanoparticles have spherical shape with a particle size ranging from 7 nm to 50 nm depending on the precursor's concentrations. It is found that higher ammonia and water concentration resulted in increasing the particle size of the Al_2O_3 nanoparticles. Micro particles of Al_2O_3 were obtained when the way of the precursors' addition has been altered; adding the ammonia to the alcoholic solution of the AlCl_3. The proposed mechanism behind the nanoparticles preparation as well as the dependence of their size on the selected factors has been discussed.