Green synthesis of nanocrystalline α-Al2O3 powders by both wet-chemical and mechanochemical methods

Abstract

Nanosized [Formula: see text]-Al2O3 powders were prepared with AlCl[Formula: see text]6H2O and NH4HCO3 as raw materials by both wet-chemical and mechanochemical methods, through the synthesis of the ammonium aluminum carbonate hydroxide (AACH) precursor followed by calcination. The environmentally benign starch was used as an effective dispersant during the preparation of nanocrystalline [Formula: see text]-Al2O3 powders. X-ray diffraction (XRD), thermogravimetric differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to characterize the precursor AACH and products. The results show that nanosized spherical [Formula: see text]-Al2O3 powders without hard agglomeration and with particle size in the range of 20–40 nm can be obtained by the two methods. Comparing the two “green” processes, the mechanochemical method has better prospects for commercial production.