Here, we describe an easy one-step process for producing structurally controlled aluminium hydroxide nano-materials with various morphologies and porosities from an aqueous sodium aluminate (NaAlO2) solution. Crystalline urchin-shaped hollow particles with a boehmite structure were prepared using a simple precipitation process at 60 oC. By lowering the reaction temperature, the formation process for urchin-shaped hollow particles could be monitored: 1) the generation of thin-film shaped materials, 2) the transformation into nano-rods, and 3) the formation of hollow particles. With heat treatment at 700 oC, the urchin-shaped hollow particles were completely converted to γ-Al2O3 particles without changing their morphology. Rodshaped products with a dawsonite structure could be obtained by the slow evaporation of boehmite nanorods in an aqueous alcoholic solution. The sodium dawsonites were converted to the diaoyudaoite phase with heat treatment at 900 oC, exhibiting a disruption in their morphology. In addition, non-crystalline porous spherical particles were also prepared using simple precipitation at 12 oC. Heat treatment at 900 oC transformed the amorphous spherical particles into γ-Al2O3 particles, maintaining their spherical morphologies.

Keywords: sodium aluminate, urchin-shaped hollow particle, porous particles.