Preparation of High-Purity Ultrafine α-Al2O3 by Solid-State Reaction at Room Temperature
Ammonium aluminium carbonate hydroxide (AACH), with a small quantity of γ-AlOOH, was synthesized through solid-state reaction at room temperature using AlCl3·6H2O and NH4HCO3 as raw materials and polyethylene glycol (PEG-10000) as the dispersant. After calcined at 1100°C for 1.5h, α-Al2O3 powders with primary particle sizes of 20~30nm were obtained. The crystal phase, particle size and morphology of the high-purity ultrafine α-Al2O3 were characterized. The results showed that a small quantity of γ-AlOOH in the AACH decomposed and formed crystal seeds. The presence of crystal seeds reduced the nucleation activation energy and therefore reduced the phase transformation temperature.
Wei Pan and Jianghong Gong
C. W. Hao et al., "Preparation of High-Purity Ultrafine α-Al2O3 by Solid-State Reaction at Room Temperature", Key Engineering Materials, Vols. 368-372, pp. 683-685, 2008