Effect of composite additives on phase transition and dispersibility of α-Al2O3

Abstract α-Al2O3 nanoparticles are easy to agglomerate in the preparation, thereby leading to adverse effects during the applications. This paper reported the preparation of α-Al2O3 nanoparticles with good dispersity and controllable morphology by lowering temperature calcination of the precipitated precursor powders. The composite composed of PVP and ammonium sulfate is used to control the morphology and improve the precursor's dispersion. The influences of R ((NH4)2CO3/Al3+, molar ratio) and PVP-ammonium sulfate composite were studied thoroughly. It was found that an urchin-shaped ammonium aluminum carbonate hydroxide (AACH) precursor can be formed under the conditions of R=3, and the ammonium sulfate and PVP are 20wt% and 5wt%, respectively. After calcination at 1000 °C for 2 h, such urchin-like precursor particles were converted to quasi-spherical and well crystallized α-Al2O3 nanoparticles, which possessed a narrow size distribution of 110 nm and a specific surface area of 12.13 m2/g. The resultant α-Al2O3 nanoparticles prepared by such a simple method were expected to be applied in transparent ceramics and high-performance catalysts.