Preparation of Functional Oxide Nano-particles with Controlled Properties through Alkoxide Route

Abstract

In this paper, reaction control of metal alkoxides has been tried to obtain oxide nano-particles with controlled properties. As a result, the principle to design the molecular structure of the precursors consisted of metal-oxygen-metal bonds was proposed based on the Zachariasen and Warren’s network theory or single bond strength proposed by K. H. Sun. Some examples of the molecular design were presented and discussed, such as the stoichiometric mullite nano-particles, non-silicates of zirconia and VO₂/SiO₂ nanocomposite particles. In the case of mullite nano-particles, importance of the aggregation control was discussed for the control of the nanostructure of the resulting nanoparticles. Zirconium alkoxide was the model case of the reaction control for the metal alkoxides with lower electronegativity using controlled chemical modification (CCM) method for the partial hydrolysis and following polycondensation to obtain the bulk gel. Nanocoating on the nanoparticles was also realized by CCM method. A few nanometers thick of VO₂ nanolayer was successfully deposited on a monodispersed silica particles of 50 nm, and their thermochromic property was confirmed at around room temperatures. All these results exhibits that the molecular design using metal alkoxides is the powerful tool to obtain the high performance oxide nano-particles.