上川 直文

Dialysis and peptization, which are colloid chemical solution processes, are simple and effective techniques for controlling hydrolysis of hydrated metal cations. These synthetic processes preparation of stable sol with dispersion of doped oxide nanoparticles with wide molar fraction range from metal chloride aqueous and glycol solutions. Furthermore, control and introduction of lattice defects can be possible due to low temperature synthesis below 373 K. Design of optical and electrical characteristics of oxide nanoparticles by the solutions processes can be realized by controlling the situation of doping and lattice defects.

Porous materials were prepared by stacking needle-like titania particles. The uniform, needle-like titania particles were synthesized by hydrothermal treatment of titanium hydroxide gel containing ethylenediamine. A seeding technique controlled the particle size of them. The obtained particles were dispersed in aqueous solutions with various pH values and vacuum-filtered to form bulk materials. Porous materials with uniform microstructure were obtained when the pH of the suspension was adjusted to the value suitable for generating electrostatic repulsion between dispersed titania particles. Changing the size of component particles also controlled the pore size of the porous titania.