単分散Al_2O_3微粒子の合成に及ぼす安定化剤の添加効果  [in Japanese] Effect of Stabilizing Agents on Synthesis of Monodispersed Al_2O_3 Powders by Hydrolysis of Aluminium Sec-Butoxide  [in Japanese]

Effects of hydrolysis-rate-control-additives (carbonyl compounds such as ethylacetoacetate and acetylacetone) on the hydrolysis behavior of aluminium secondary butoxide and condition for the formation of monodispersed alumina particles were investigated. The reactive enol form of the carbonyl compounds substituted butoxyl group of aluminium secondary butoxide and chelated the aluminium atom. The chelating ligand would not be easily removed upon hydrolysis reaction because the aluminium-ligand bond was sufficiently strong. As a consequence, the rate of hydrolysis and polycondensation of modified precursor decreased. By hydrolyzing this modified stable precursor, the monodispersed alumina particles were prepared in the wide range of water concentration; about 8 times that of non-modified precursor when 0.006 mol/l ethylacetoacetate was added and about 4 times when 0.006 mol/l acetylacetone was added. The average particle size of obtained monodispersed particles and the geometrical standard deviation were 0.2 μm and 1.18, respectively. The morphology of particles changed with increasing water concentration as follows; agglomerates of coarse texture→monodispersed particles→agglomerates of fine texture.