Synthesis of α-Al2O3 nanoparticles with uniform size distribution by stearic acid-assisted mechanochemical method

Severe agglomeration caused by high calcination temperature is a major challenge to the preparation of highly dispersed α-Al2O3. In this study, α-Al2O3 nanoparticles were prepared by stearic acid-assisted mechanochemical method. The mechanochemistry induced the conversion of ammonium aluminum carbonate hydroxide (AACH) to α-Al2O3 during the calcination process and significantly reduced the phase transition temperature of α-Al2O3. The sintering phenomenon between α-Al2O3 particles was reduced by constructing an organic protective layer on the AACH surface using stearic acid. The composition, structure, and morphology of the prepared powders were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric-differential scanning calorimetry (TG-DSC). Carbon produced by calcining stearic acid in the N2 atmosphere was distributed on the surface of the α-Al2O3 grains, which impeded the growth of the α-Al2O3 nanoparticles. The average size of the samples obtained was smaller, and the size distribution was narrower than that of the directly calcined AACH.