Doping Modulation Of Mid-and Far-infrared Radiation Properties Of La_0.5Ba_0.5CoO_3-δ Ceramics

With the development of science and technology,the detection capabilities of infrared detectors have been gradually optimized,and the detection capabilities have been greatly improved.Once a military target is exposed,it faces the risk of being destroyed.It is the key to reduce the infrared exposure of military targets by developing low infrared emissivity materials.For the current low-infrared emissivity materials,although most inorganic low-emissivity materials have the incomparable advantages of metal materials in terms of high-temperature stability,anti-diffusion,and adaptability to the substrate,the high infrared emissivity limits its practical application.In this paper,inorganic non-metallic materials La_0.5Ba_0.5CoO_3-δperovskite ceramics were used as the research object.The modulation effect of La site and Co site doping on the mid-far infrared radiation characteristics of the system was studied,and low infrared emissivity perovskite ceramics with mid-far infrared stealth characteristics were obtained.The main results of this paper are summarized as follows:（1）La_0.5-xCa_xBa_0.5CoO_3-δand La_0.5-xSr_xBa_0.5CoO_3-δ（x=0,0.05,0.10,0.15）were obtained by substituting bivalent Ca²⁺and Sr²⁺ions for trivalent La³⁺ions,respectively.The experimental results show that the samples of the two doping systems have a highly symmetrical cubic phase structure,and the introduced Ca²⁺and Sr²⁺completely replace the position of La ions.The samples have good compactness and low porosity.When the doping amount is x=0.05,the introduction of divalent ions increases the content of Co⁴⁺ions in the system,and enhances the double exchange(Co³⁺-O^2--Co⁴⁺)between Co ions,which promotes the transfer of carriers,enhances the metallicity of the material,enhances the reflection of infrared light by the material,and reduces the infrared emissivity.The infrared emissivity of Ca²⁺doped samples decreased from 0.23 to 0.05 in the 3～5μm band and from 0.22 to 0.12 in the 8～14μm band.The infrared emissivity of doped Sr²⁺ions decreased from 0.23 to 0.10 in the3～5μm band,and slightly increased in the 8～14μm band,and the infrared thermal image radiation temperature was significantly lower than the actual temperature.（2）La_0.5Ba_0.5Co_1-yNi_yO_3-δand La_0.5Ba_0.5Co_1-yFe_yO_3-δ（y=0、0.05、0.10、0.15）were prepared by substituting Ni²⁺and Fe²⁺/Fe³⁺for Co sites,respectively.The results show that the samples doped with Ni²⁺are perovskite structure of single-phase,while the samples doped with Fe have impurity phase due to the saturation of solid solubility of La_0.5Ba_0.5CoO_3-δwhen y=0.10 and 0.15.When the doping amount is y=0.05,the appropriate amount of Ni²⁺ion substitution increases the carrier concentration,resulting in a decrease in resistivity.The introduction of Fe ions reduces the bond length of the Co-O bond,promotes the exchange between Co ions,and reduces the resistivity.The infrared emissivity of doped Ni²⁺ions in the 3～5μm band decreased from 0.23 to 0.18,and the infrared emissivity in the 8～14μm band decreased from 0.22 to 0.14;The infrared emissivity of doped Fe ions in 3～5μm band increased slightly,and the infrared emissivity in8～14μm band decreased from 0.22 to 0.15,and the infrared thermal image radiation temperature of the sample was significantly lower than the actual temperature.Therefore,La_0.5Ba_0.5CoO_3-δ,La_0.45Ca_0.05Ba_0.5CoO_3-δ,La_0.45Sr_0.05Ba_0.5CoO_3-δ,La_0.5Ba_0.5Co_0.95Ni_0.05O_3-δand La_0.5Ba_0.5Co_0.95Fe_0.05O_3-δ,La_0.5Ba_0.5CoO_3-δhave potential applications in infrared stealth due to their low infrared emissivity in 3～5μm and8～14μm bands.