Synthesis of plate-like alpha-Al2O3 single-crystal particles in NaCl-KCl flux using Al(OH)(3) powders as starting materials

Plate-like alpha-Al2O3 single-crystal particles were successfully synthesized in NaCl-KCl flux using Al(OH)(3) powders as starting materials, and the influence of pre-calcining of Al(OH)(3) powders on the phase formation and morphology of alpha-Al2O3 powders was focused. When Al(OH)(3) powders are used as starting materials, the synthesized product at 900 degrees C is mainly composed of alpha-Al2O3 and kappa-Al2O3, and most synthesized particles show alveolate morphology. At 1100 degrees C, single-phase alpha-Al2O3 powders are developed, in which there are many aggregations of intensively bound plate-like particles. In contrast, using porous amorphous Al2O3 powders obtained by pre-calcining Al(OH)(3) powders at 550 degrees C for 3 h as the starting material, plate-like alpha-Al2O3 single-crystal particles can be well developed above 900 degrees C. The reason of the influence of pre-calcining of Al(OH)(3) powders on the phase formation and morphology of alpha-Al2O3 powders is also discussed in the paper. (C) 2007 Published by Elsevier Ltd and Techna Group S.r.l.