Preparation And Study On Visible-Infrared Properties Of SiO₂/ZnO Amorphous Photonic Crystal

SiO₂ amorphous Photonic crystals(APCs)which are disorderly arranged structural materials possess rich and subtle structural colors.These structural colors show anisotropic performance and would not be affected by the angles,so they have great potential in the visible light stealth filed.While the APCs have some restrictions on the application of infrared stealth because it is difficult to achieve low emissivity while ensering structural color in single phase APCs.In this paper,we firstly obtain monodisperse SiO₂ spheres with different diameter and prepare SiO₂ APCs by various self-assembly methods.Then the relationship between SiO₂ diameter and the structural color of SiO₂ APCs has been known as well as the the most suitable self-assembly method.ZnO particles,a low-emissivity material,are using to fill the gap of SiO₂ APCs by electrodeposition method to achieve the compatiblith between low emissivity in 3?5mm and well structural color performance.Beisdes,we obtain SiO₂@ZnO APCs by the SiO₂ spheres coated with ZnO particles,which were also using to adjust both properties.The main research contents and conclusions are as follows:(1)Well monodisperse SiO₂ spheres with different diameter(150 nm?1mm)were synthesized by modified St(?)ber method,it can be found that the diameter SiO₂ particles are proportional to the ammonia concentration,TEOS concentration and the temperature due to the increased nucleation speed.of SiO₂ within limits.The fast and efficient spin-coating method have been chosen to prepare the SiO₂APCs;and with the increase of spin-coating times,the structural color of SiO₂APCs become brighter and deeper,the emissivity of SiO₂APCs in 3?5mm also decrease modestly because the influence of the glass substrate have been greatly weakened and emissivity at room temperature is between 0.5?0.6.(2)SiO₂-ZnO APCs were prepared by electrodeposition method for reducing the emissivity in 3?5mm.When the amount of ZnO electrodesposition is small,the structure of the SiO₂-ZnO APCs is the same as that of SiO₂ APCs,and its structural color is mainly determined by the particle size of SiO₂ nanospheres;with the increase of ZnO electrodeposition time,the structural color of SiO₂ APCs have the tendency to fade and the infrared emissivity in the 3?5mm decreases continuously.While the SiO₂-ZnO APCs with the spin-coating times of 40 would lead to the increase of emissivity because it would induce many defects in the structure.Finally,when SiO₂pellets with a particle size of 225 nm as the building element,the number of spin-coating times was 30 times and the electrodeposition time was 20 minutes,the SiO₂-ZnO APCs possess the best compatibility of structural color and emissivity in 3?5mm(?0.4),besides it has good temperature resistance.(3)In order to further decrease the infrared emissivity of 3?5mm based on ensuring the structural color of SiO₂APCs,we try to prepare different diameter SiO₂ coated with ZnO particles and then obtain the SiO₂@ZnO APCs by self-assembly method.It is found that as the particle size of SiO₂ increases,the surface charge density of SiO₂ decreases,which is not conducive to nucleation of ZnO on the surface of SiO₂ and causes the uneven coating,so the emissivity decrease a little and structural color become uneven.Then we use the SiO₂ nanospheres with the diameter of 250 nm to change the ZnO coating amount.As the coating amount increases,the structural color changes due to the change in effective refractive index,and the emissivity continues to decrease.Finally,the SiO₂ pellets with diameter of 250 nm are used as the core,and the SiO₂@ZnO APCs with a mass ratio of ZnO to SiO₂ of 4:1 shows a better light green color and a lower emissivity?0.24 at the wavelength of 3?5mm,which is a excellent material with the compatible visible-infrared stealth.