Preparation Of Crack Free Iron Oxide Inverse Opal Photonic Crystals

In recent years,due to the fact that photonic crystals have light manipulation properties,they have important applications in fiber-optical,filter,color filter and so on.Therefore they receive widespread attention.However the existence of cracks in the photonic crystals afect the periodicity and limits the practical applications.The current method for the preparation of the crack free photonic crystal is to eliminate the crack before the template crack is produced.At present,no one can eliminate the crack after the crack is produced,which is generally considered impossible.This paper focuses on how to eliminate cracks in photonic crystals.We design a series of experiments on the preparation of crack free iron oxide inverse opal photonic crystals.The main contents are as follows:1,The preparation of crack free Fe2O3 inverse opal structure photonic crystals with crack free colloidal crystals as templateIn this chapter,we prepares crack free ferrihydrite and Fe2O3 inverse opal photonic crystals by sacrificing template method.In the previous study,our research group prepares crack free colloidal crystals with narrow band gaps.In this part,we successfully prepare crack free Ferrihydrite-P(St-MMA-AA)opal composite photonic crystals by drop coating or coating technique with crack free high quality colloidal crystal as template.Different research on filled ferric shows,ferrihydrite prepared by the reaction of ferric salts and alkali can't be filled because of larger particles while ferric salts under the condition of constant temperature and constant humidity hydrolysis are more conducive for preparing crack free composite opal structure photonic crystals.We explore optimum conditions to prepare Ferrihydrite-P(st-MMA-AA)composite opal structure photonic crystal.There is still few reports on the preparation of crack free photonic crystals by using the crack free templates.This method of crack free inverse opal photonic crystal preparation is simple,quick,convenient and with high safety factor.It greatly reduces costs of preparation,promotes the development of photonic devices and increases a number of possibilities of inverse opal structure diversity.2,The preparation of crack free Fe2O3 inverse opal structure photonic crystals with common cracks colloidal crystals as templateThis chapter adopts poly(styrene-methyl-methacrylate)colloidal crystal with ordinary cracks as template and successfully prepares crack free Fe2O3 inverse opal structure photonic crystal.They show uniform and beautiful structural color with the photonic band gaps cover the entire visible band.The photonic band gap of the crack free Fe2O3 photonic crystal can be effectively controlled by the particle size of the colloidal crystal template.Further research that the FeCl3 filled in solution with crack colloidal crystal template is hydrolyzed into ?-FeOOH rod in constant temperature and humidity environment.The ?-FeOOH bars are growing in the crack of colloidal crystals and connecting with each other along with the hydrolysis.After further calcinationsn,nanoneedle ?-FeOOH is transformed into nanospherical Fe2O3 particles due to loss of water.In transformation process,nanoneedle ?-FeOOH continually shrinks,achieving effective suture of the cracks smoothly.As a result,we obtain the crack free Fe2O3 inverse opal structure photonic crystals.At present,the academia generally think that once the cracks have been formed,they can't be filled and repaired.The cracks of colloidal crystals are effectively eliminated by dint of the stitching the wound process.It provides an important theoretical support for the preparation of the crack free photonic crystal and the elimination of the crack in the other fields.