Preparation of nanoscale high-purity α-alumina powders

High-purity nanoscale alpha-alumina powders with high specific surface area were prepared from boehmite powders synthesized by the method of aluminium isopropoxide hydrolysis. The physiochemical transformation of boehmite powders under heat-treatment was investigated. The results showed that the reaction progress of boehmite under heat-treatment is as follows: AlO(OH) -> Al2O3 (amorphous) -> gamma-Al2O3 -> delta-Al2O3 -> alpha-Al2O3. The phase transformation from delta-Al2O3 to alpha-Al2O3 begins at 1050 degrees C, and the alpha-Al2O3 grains growth accelerates as temperature increases. High-purity alpha-Al2O3 nanometer powders with higher specific surface area can be obtained after incineration at 1100 degrees C for 4 h.