TiOCl_2の自己加水分解によるTiO_2粒子合成に対するマイクロ波効果

概要

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TiO_2 nanoparticles were synthesized by self-hydrolysis of TiOCl_2 using conventional and microwave heating methods. By XRD analysis, rutile and anatase phases were detected at the early stage of reaction. In conventional heating method, the XRD peaks of rutile became stronger with time and the roundish agglomerates surrounded by acicular particles were observed by SEM. The initial product was confirmed by TEM to consist of small acicular particles assigned to rutile and fine nanoparticles assigned to hydrous TiO_2 sol having anatase-like structure. As the reaction time was longer, the amount of acicular particles increased. These results suggest that TiO_2 sol formed at the early stage by hydrolysis of TiOCl_2 and the crystal growth of rutile progressed by dissolution-reprecipitation of TiO_2 sol. In order to synthesize TiO_2 nanoparticles, microwave was applied to this system. The microwave irradiation shortened the period of the precipitation because microwave can quickly heat up the aqueous solution, but retarded the crystal growth of rutile, leading to size reduction of TiO_2 particles identified a hydrous TiO_2 phase.
2006-10-01