Synthesis And Microwave Absorbing Properties Of Doped LaMnO₃ And Hybrid Materials

Nowadays,great impact of electromagnetic interference?EMI?problems on both civilization,and military application has resulted from widely application of electric and electronic devices because of the fast development of advanced technology.EMI problems can be effectively eliminated by microwave absorbing materials and thereby this kind of material has attracted extensive attention.However,traditional single materials cannot meet the demand of effective electromagnetic absorption materials with strong absorption,wide frequency range,low density,etc.Therefore,hybrid EM wave absorbers have become a research hotspot.In this paper,we have synthesized both k doped LaMnO₃(La_1-xK_x MnO₃)materials and Nd doped LaMnO₃(La_1-xNd_xMnO₃)materials by sol-gel method.In addition,the relationship between the doping content and electromagnetic parameters were studied to obtain optimum absorbing materials.The results have indicate that optimum reflection loss of La_0.8K_0.2MnO₃ reaches 33.51 dB at 12.22 GHz with a thickness of 1.25 mm.Also,the bandwidth with the loss of 10 dB is about 2.1 GHz in the GHz range.The calculated results indicate that the La_0.8K_0.2MnO₃ sample has the potential to be utilized as electromagnetic wave absorbers.Graphene has attracted increasing attention in microwave absorbing areas due to its excellent properties.In this paper,we have synthesized graphene oxide by Hummers method.Also,LaMnO₃/GO hybrid materials with different ratio were synthesized by adding LaMn O₃ particles in the process of hydrothermal reduction.Finally,the phase structures,morphologies as well as electromagnetic absorption properties of LaMnO₃/GO hybrid materials were investigated and the results have shown that the microwave absorbing properties of hybrid materials were improved.The maximum reflection loss is 25.53 dB at about 6.78 GHz with a thickness of 2.5mm when the proportion of graphene is equal to 2%.Moreover,the bandwidth with the reflection loss above10 dB is reached about 1.53 GHz?6.10-7.63 GHz?.In a word,the LaMnO3/graphene hybrid material does have good absorbing property with its bandwidth broadened and the maximum reflection loss increased.