The Infrared Emissivity Of ZnO With Different Particle Size And Morphology

Since the 1980s,infrared stealth has become one of the focuses of the development of aIRcraft stealth technology.In the new century,our country has invested huge amounts of capital and manpower in the infrared stealth technology. However,current infrared stealth whether in theory or in practical applications is still a big blank.This paper tries to make little contributions to the development of infrared stealth from both theory and practice.A's long a's any object is above absolute zero,it will radiate energy out.Infrared detector detects the target through the differ between the object and the background radiation.Therefore,Infrared Stealth is to achieve lower infrared radiation energy of object.The infrared emissivity is an important parameter.The bigger the emissivity is, the greater the infrared radiation of object is.In thermal equilibrium conditions,the object of radiation energy is equivalent to the energy absorption.The light absorption contains two sides,on the one hand it is determined by the nature of the absorption of object,on the other hand it is due to the different structure of object.Those can effet scattering attenuation are material particle size,particle morphology,and so on.Through homogeneous precipitation and hydrothermal method,different particle size ZnO materials,a's well a's the morphology of ZnO with petal-like,needle-like, tetrapod-shaped were synthesized.After discussing the mechanism of the growth of ZnO and its optical properties,infrared emissivity was mainly studied.It was found that with the decreasing of ZnO particle size,the infrared emissivity decreased gradually.The emissivity of Petal-like,needle-like,tetrapod-shaped ZnO reduced gradually.With particle scattering theory,the relationship between ZnO particle size,morphology and emissivity was explained.According to Mie-scattering mechanism,a quantitative curve of size and absorption can be got.From the curve,when micron particle size fell down to nanometer level,the absorption decreased significantly, thereby the emissivity reduced.This rule is not only adapted to ZnO,and should be universal. The relationship between morphology and emissivity is complicated,and it is difficult to conduct quantitative calculation.But we can see that the more complex the morphology was,the stronger its scattering so the emissivity was higher.When the morphology was similar,the greater the distance between particles,the lower the emissivity.This could be explained in independent scattering.