Synthesis of Monodispersed GeO2 Particles in Nonionic Reversed Micelle Systems--Control of Particle Size and Crystal Structure--
Daisuke KANEKO*, Hideki SHOUJI, Tadakazu OHOTOMO, Takeshi KAWAI† and Kijiro KON-NO†
Department of Industrial Chemistry, Faculty of Engineering, Science University of Tokyo; 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 Japan
† Institute of Colloid and Interface Science, Science University of Tokyo; 1-3, Kagurazaka, Shinjuku-ku, Tokyo 162-8601 Japan
On the basis of phase diagram of water solubilization or micelles in poly (oxyethylene) (6) nonylphenyl ether (NP-6)/cyclohexane solutions, the synthesis of GeO2 particles by the hydrolysis of germanium tetraethoxide (GTE) have been carried out as a function of RW (= [H2O]/[NP-6]), [NP-6] and [GTE]. No any particles were formed in monomer region. However, in both the reversed and swollen micelle regions relatively uniform spindle-like particles were produced, but they were turned to cubic-like polyhedral particles in W/O microemulsion region. These particle size depended markedly on RW (= [H2O]/[NP-6]), whereas they increased with increasing the concentration of NP-6 and inversely decreased with increasing GTE concentration. Particle size was decreased with increasing the apparent formation rate of particles and this formation rate depended on the states of solubilized water. On the other hand, X-ray and electron diffraction measurements indicated that any particles were hexagonal and α-quartz typed GeO2, but spindle- and cubic-like particles were polycrystalline and single crystalline, respectively. X-Ray diffraction measurement also indicated that such change of crystalline morphology was brought about by growth of (100) face of the side face of spindle-like particles.
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