Preparation And Study On Microwave Absorption Properties Of FeNi/RGO Nanocomposites

Graphene-based magnetic composites materials are currently the hot research topic in the field of electromagnetic wave absorption. They can satisfy the requirements of new microwave absorbing materials, which are thin thickness, light quality, wide frequency band and strong absorption. This paper used three different chemical methods to synthesize graphene-based FeNi alloy (FeNi/RGO) nanocomposites. By comparing the morphologies of the products, in-situ reduction was determined to be the best method for the preparation of the FeNi/RGO nanocomposites. The microstructure and morphology of the nanocomposites were characterized by XRD、TEM、SEM、HRTEM、SEAD、EDS and Raman. The influences of [Fe2+]/[Ni2+] ratio, dosage of NaOH, reaction temperature, reaction time and the use of surfactants on the morphplogy, particle size distribution and particle dispersion of the FeNi/RGO nanocomposites were explored. For the best preparation conditions,[Fe2+]/[Ni2+] ratio should between1:1and1:2, the dosage of NaOH should in the range of1.0～1.5g, the reaction temperature should in the90-110℃range and the reaction time should be45min.The magnetic hysteresis loop measured by VSM reveals the ferromagnetic behavior of nanocomposites at room temperature. The electromagnetic characteristics of the FeNi/RGO nanocomposites in the2-18GHz range were measured by the N5244A type vector network analyzer, and the influences of the FeNi alloy composition and load on the microwave absorption performance of the nanocomposites were also explored. The results demonstrate that the microwave absorption properties of FeNi/RGO nanocomposites are achieved mainly by the magnetic loss in the high frequency range, and the bigger is the magnetic loss, the better are the absorption properties of the nanocomposites. However, the introduction of high dielectric loss would lead to the absorption properties become poor. In this paper, when [Fe2+]/[Ni2+] equals to1:1and [Fe2+]+[Ni2+]=0.49mmol in the raw materials, the nanocomposites show outstanding microwave absorption performance, as evidenced by the minimal reflection loss RL(-32dB) at12.4GHz with a thickness of1.5mm, which means more than99%of the incident microwave is absorbed, and the wide effective absorption bandwidth (up to10.9GHz,3.4～14.3GHz, with RL<-10dB).