Optimization of Electrical and Magnetic Properties of SrFe₁₂O₁₉₋GNS Composites by High-Energy Ball Milling for EMI Shielding Applications

Strontium hexaferrite and its composites with GNS (Graphene Nanosheet) prepared by the high energy ball milled process as [(100-x)SrFe₁₂O₁₉-(x)GNS] composites with x = 00, 2.5, 5.0, 7.5 and 10. It has been followed by prepared strontium hexaferrite using modified sol-gel method. The XRD pattern of Strontium hexaferrite confirmed that formation of hexagonal crystal structure with P63/mmc space group. The analysis of Raman spectra well supports the XRD patterns analysis. The average particle size 200 nm estimated by FESEM micrograph and it also reveals that both phases present. The impedance decreases with an increase in frequency as well as temperature, which supports an increase in ac electrical conductivity. The impedance decreases with the increase in the percentage of GNS in composites. The activation energy is decreasing with the increasing percentage of GNS. The effect of electrode, grain and grain boundaries are separated in terms of R_s, R_g and R_gb from Cole-Cole plot modelled with equivalent electrical components. The magnetizations of the composites decrease with the increasing GNS contents. The SHF-GNS-2.5 composite achieves approximately 10 dB, SHF-GNS-5.0 composition reaches approximately 18 dB, while SHF-GNS-7.5 attains around 26 dB of shielding effectiveness. The most impressive results are observed with SHF-GNS-10, which delivers approximately 33 dB of EMI shielding throughout the frequency spectrum. The optimizations of electrical and magnetic parameters with the help of surface modifications in the composites that makes superior for EMI shielding performance.