Synthesis of γ-Al2O3Hexagonal Nanoplatelet by Combining Sol–Gel and Hydrothermal Process

Hexagonal γ-alumina (γ-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°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°C and 800°C was γ-Al2O3. Scanning electron microscopy (SEM) micrographs revealed γ-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°C revealed the average particle size of γ-alumina nanoplatelets of 90 nm in length and 36 nm in diameter. The crystallinity of the γ-alumina nanoparticles were confirmed by selected area diffraction pattern and high resolution TEM.