Hydrothermal Synthesis of Petal-Like Alumina Flakes

Petal-like alumina flakes were prepared by hydrothermal reaction at 170 degrees C for 6 h with aqua-based precursor materials. The gel particles were calcined at 550 degrees-1200 degrees C. The gel and calcined particles were characterized by differential thermal analysis (DTA), thermogravimetry (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), multipoint Brunauer-Emmett-Teller (BET) surface area, and field emission scanning electron microscopy (FESEM). Crystallization of alumina was confirmed by DTA and XRD studies. XRD results showed that boehmite particles were formed in as-prepared sample while gamma-alumina (gamma-Al2O3) persisted up to 800 degrees C followed by the appearance of h-alumina (theta-Al2O3) at 1000 degrees-1200 degrees C. The characteristics Al-O vibrations in alumina polymorphs were examined by FTIR study. FESEM confirmed the formation of petal-like alumina flakes with the assembly of alumina nanorods.