Preparation Of TiO₂/SiO₂ Complex Particles And Fabrication Of Complex Colloid Crystal

Photonic crystal is a 3-D ordered structure material with photonic band-gap and photon localization, its reflective index has a spatial modulation at the scale of visible or near-infrared light's wavelengths. High-quality photonic crystal can be used to make special photonic devices with high speed, large capacity and huge integration, therefore, it has a lot of prospective applications. One of the effective ways to fabricate photonic crystal is the method of self-assembly: obtaining colloid crystal from sub-micrometer colloidal spheres.The refractive index of the traditional opal materials (e.g. silica, PS) is less than 1.6.In the near-infrared and visible regions, they don't own a complete band-gap and can't meet the need of photonic crystal. Because of their high refractive index, titania spheres may be good candidates for a photonic crystal with a complete band gap in the near-infrared and visible regions if they are made uniformly in size and packed orderly in structure. Since monodisperse silica spheres can be easily prepared by Stober procedure, it would be possible to coat a certain thickness of titania on the silica spheres without changing their monodispersity. On the basis of researching to the references, following studies were carried out in this paper:1. Under different reaction conditions (mainly the concentration of ammonia and the experiment temperature), well monodispersed silica colloidal particles with different diameter were synthesized freely. The particle sizes increased with the increasing of the concentration of ammonia.2.TiO₂/SiO₂ complex spheres were prepared with the monodisperse silicasubmicrospheres as the cores.(1)XRD,EDS,FT-IR,Microelectrophoresis instrument were used to convince thattitania was coated on the surface of silica.(2)The effect of different reaction conditions (TBOT concentration,waterconcentration,diameter of core and steps of coating)on coating quality including theuniformity and thickness were discussed with SEM ,microelectrophoresis instrumentand gravity sedimentation.The results showed that uniform, absolute coating couldbe achieved if choosing proper concentration of TBOT and water. Coating thicknessincreased with increasing of coating steps.The diameter of core had little influence...