Study On The VIS-NIR Spectral Characteristics Of Modified Chromium Oxide

With the development of hyperspectral imaging technology and infrared reconnaissance technology,it is difficult traditional camouflage methods to meet the stealth needs of modern battlefields.The use of visible-near infrared stealth pigments can change the target’s spectral characteristics,so that it’s easy to blend the targets into the background environment.At present,it is difficult for such stealth pigments to own both low cost,low brightness,stable chemical properties,and obvious infrared plateau.In this paper,the doping modification of chromium oxide is taken as the research object.The effects of doping concentration and sintering temperature on the spectral characteristics of chromium oxide composite pigments were studied using solid-phase reaction sintering method where the Al,Co,Cu,Fe and Ca are using as doping elements.A modified chromium oxide composite pigment with visible light-near-infrared spectral characteristics similar to green plants,low brightness,and a distinct infrared plateau was prepared.Aiming at the problem that the near-infrared reflectance of chromium oxide is too low,a method of alumina-doped chromium oxide is proposed.Based on the carrier light absorption theory,a composite pigment with low carrier concentration and high nearinfrared reflectance was obtained.On this basis,the composite powder with small particle size and unit cell volume was prepared when the sintering temperature was reduced to 1000 ℃ according to the diffusion law of the substance at high temperature.The infrared reflectance is further increased to 80%,meeting the needs of modified chromium oxide for high infrared reflection.In order to solve the problem that the modified chromium oxide simulated the plant’s infrared absorption peak at 1300 nm,the pigments were doped with cobalt oxide and copper sulfide respectively based on the previous research.The results show that these two types of dopants introduce cobalt chromate and copper oxide with narrower band gaps,respectively,so the light absorption of this doped energy level in the near-infrared band results in an absorption peak of the composite pigment in the 1300 nm band.In addition,it has been verified by experiments that the composite pigment doped with cobalt oxide has strong acid and alkali resistance and excellent chemical stability.Considering that the Al doping not only improves the infrared reflectivity of the material,but also improves the brightness,iron oxide was doped on the basis of aluminum / cobalt binary doping in this paper.The introduction of Fe atoms into the composite pigment can effectively reduce the brightness taking advantage of the strong light absorption of iron atoms in the visible light band.Ca doping causes the material to shift blue,which is more conducive to the spectral curve of the composite pigment entering the spectral channel.