The Study On Microwave Absorption Performances Of Doped M-type Barium Ferrite And The Doped Ferrites Composite Materials

This research aimed at preparing "strong absorption,low reflection,light quality,broad band" microwave absorbing materials,through the ion doping modification of M type barium ferrite which have the capability of strong magnetic loss,studying the microwave attenuation properties of the doped M-type barium ferrites;Then,selecting the doped M type barium ferrite showed better absorbing performance and to carbothermal reduction with glucose,comparing the absorbing performance before and after the reduction processes;Finally,selecting the doped M-type barium ferrites possessing perfect magnetic loss were combined with graphene which have good dielectric loss,exploring the microwave attenuation properties of the composites.The test results are as follows:?1?BaMg_xCo_1-xTiFe₁₀O₍19 hexaferrites were prepared via the sol-gel combustion reaction method.Mg²⁺substitution could significantly modify the magnetic properties and the microstructure of the barium ferrites.The Hc of Ba Mg_xCo_1-xTiFe₁₀O₁₉ could be enlarged with the increase of the doped Mg²⁺,whereas the Ms and grain size were inversely proportional to the doping content of Mg²⁺.Meanwhile,Ba Mg_0.4Co_0.6TiFe₁₀O₁₉ exhibited optimum microwave absorption characteristics with a maximum reflection loss?-33.7 dB?when the thickness of composite was 2.0 mm,and also had a 5.7 GHz?11.5-17.2 GHz?bandwidth below-20 dB.Moreover,the permeability of the synthesized ferrites was tunable by controlling the doped content of Mg²⁺,which would be significant to the application of Ba Mg_xCo_1-xTiFe₁₀O₁₉ in the field of the microwave absorbing materials.?2?BaMg_0.2Co_0.8TiFe₁₀O₁₉?BMCTF?hexaferrites was synthesized by the sol-gel combustion reaction method.The magnetic-dielectric heterostructured nanoparticles were created via a combination of hydrothermal carbonization and carbothermal reduction processes.Magnetic measurement of C@BMCTF indicated that the Hc could be enlarged with the doping of carbon,whereas the Ms was inversely to thedoping.Meanwhile,C@BMCTF exhibited optimum microwave absorption characteristics with a maximum reflection loss?-45.2 dB?when its thickness was 1.8mm,and when the thickness of C@BMCTF composite was 2.0 mm,the bandwidth of RL less than-10 dB was from 12.14 GHz to 18 GHz.?3?Using the Hummers method prepared the graphene oxide?GO?,and then prepared the composite material of rGO/BaMg_0.2Co_0.8TiFe₁₀O₁₉.The results show that:rGO/BaMg_0.2Co_0.8TiFe₁₀O₁₉ have a small Ms than Ba Mg0.2Co0.8TiFe10O19,whereas the Hc was almost the same.When the mass ratio of rGO/BaMg_0.2Co_0.8TiFe₁₀O₁₉ was 1:1,the maximum reflection loss of rGO/BaMg_0.2Co_0.8TiFe₁₀O₁₉ could reach-48 dB at f=17.5 GHz.When the mass ratio of rGO/BaMg_0.2Co_0.8TiFe₁₀O₁₉ was 1:5,the bandwidth of reflection loss less than-10 dB for the composite could reach 4.6 GHz?11.5 GHz-16.1 GHz?.