Photonic Crystal To Build The Primitive Preparation And Surface Modification

Photonic crystals are 3D structures with a dielectric constant that varies largely and periodically with lattice spacing comparable to the wavelength of light.This creates a periodically varying scattering potential for the light,giving the material optical properties similar to the electrical properties of a semi-conductors.It has attracted much attention to their capacity for manipulating,confining,and controlling light for many potential applications in photonics and electronics fields.One of the effective ways to fabricate photonic crystal is the method of self-assembly:obtaining colloid crystal from sub-micrometer colloidal spheres.Generally speaking,the material is the monodisperse silica spheres.The significant results achieved in this dissertation go as follows:1.The traditional St(o｜¨)ber method for the preparation of monodisperse silica spheres has been modified and been optimized.Highly uniform silica spheres with diameters ranging from 125 to 1000nm and with relative standard deviation less than 5.0%have been obtained based on the modified process.The effects of temperature,stirring rate, electrolyte of CaCl₂ and the rate of the TEOS addition in the process of the microspherules formation on the diameter and the monodispersity of silica spheres have been studied.The studies showed that the TEOS should be diluted enough and be added slowly in order to get monodispersed spheres.At lower temperature and with high stirring rate,one can get spheres of large diameter with the lower monodispersity.Additionally, the influence of the temperature on the spheres is obvious than that of the stirring rate. With the increasing of the temperature,the diameter of the spheres decreased gradually. When the concentration of the Ca²⁺ reaches a concentration of 3.3mmol/L,the particles lost their sphere shape and aggregations were obtained.2.The methylene blue was adhered to the SiO₂ surface by a simple dip coating method,but it can be easily rinsed out by solvent.Hydrolyzed KH-570 can adhere more tightly to the surface of SiO₂ spheres.TiO₂@SiO₂ core/shell structured spheres were prepared with the monodisperse silica submicrospheres as the cores by hydrolyzing TBOT in the water/ethanol mixture solvent.A pH of about 4.5 is the suitable value for the preparation of the TiO₂@SiO₂ spheres by the electrostatic adsorption method.