Synthesis of γ-Al2O3 Hexagonal Nanoplatelet by Combining Sol-Gel and Hydrothermal Process

Hexagonal gamma-alumina (gamma-Al2O3) platelets were prepared by combining sol-gel process and hydrothermal process. The starting material used for the preparation of alumina sol was aluminium-tri-isopropoxide. Alumina sol was subjected to hydrothermal treatment at a reaction temperature of 250 degrees C for 12 h. X-ray diffraction (XRD) of as-synthesized powder confirms the formation of boehmite. The phase present in the powders calcined at 600 degrees C and 800 degrees C was gamma-Al2O3. Scanning electron microscopy (SEM) micrographs revealed gamma-alumina nanoplatelets had diameters ranging from 30 to 50 nm and lengths ranging from 60 to 90 nm. The transmission electron microscopy (TEM) analysis of the calcined powders at 800 degrees C revealed the average particle size of gamma-alumina nanoplatelets of 90 nm in length and 36 nm in diameter. The crystallinity of the gamma-alumina nanoparticles were confirmed by selected area diffraction pattern and high resolution TEM.