A21 無機ナノ粒子の湿式合成における出発溶液のエイジングとソフトソニケーション効果

概要

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We propose the aging time as a new parameter to identify a starting solution and to control the nucleation in ceramic particles synthesis containing a non-aqueous solvent. That is, the aging treatment results in the increase of the incubation period (= delay of precipitation), the increase of particle size (= decrease of nucleation site), and the increase of monodispersity (= homogenization of nucleation). In our hypothesis, the structure of starting solutions (or the microscopic mixing state among the molecules of solutes and solvents) changes with an aging time of several days. This paper presents two examples where the aging effect of starting solutions on precipitation behavior was clearly shown in practice. One is an oxalate precipitation from ethanolic solution of oxalic acid, the other is the Stober synthesis of silica spheres. It has been found that soft sonication with a frequency of 40kHz and a power of 〜0.1mW absolutely enhances the aging process, compared to both quite aging and mechanical stirring. Cold spray ionization mass spectroscopy (CSI-MS), where soft ionization enables the measurement of weakly-bonded clusters, has been employed to shed light on the aging process of water-ethanol mixtures. It suggested that they contains some clusters which gradually decreases in size with aging.
日本ソノケミストリー学会の論文
2005-10-14