A microstructure-driven magnetic composite for excellent microwave absorption in extended Ku-band

Abstract

In this study, we present an innovative approach for the fabrication of efficient electromagnetic shielding material by tuning the microstructure of the filler in a flexible PDMS polymer matrix. Here, hollow, Prussian blue (HPB) nanoparticles anchored on reduced graphene oxide (rGO) sheets (HPBR) play as active fillers for the composites where the hollow structure performs as magnetic nanoparticles. We have explored how the magnetic property is changed by transforming the microstructure from solid to HPB (shell thickness ∼32 nm) via a simple self-etching method. The PDMS-based polymer composite with solid and hollow PB exhibited EMI SE values of ∼6.31 and ∼7.51 dB at 14.5 GHz, respectively, which was further improved after the addition of rGO. It is found that at 14.5 GHz, polymer composite containing HPBR1-1 where the precursors, K₃Fe(CN)₆ and GO remain at 1 : 1 mass ratio, exhibited a total EMI SE_T value of ∼32.01 along with the highest absorption property EMI SE_A value of ∼27.07 dB (SE_A% ∼84.56) in comparison to other composites with a thickness of ∼2.4 mm. Moreover, the dielectric and magnetic properties of the HPBR composite can be altered by varying the mass ratio of the precursors and eventually a synergistic balance between energy conservation and impedance matching emerges with a 1 : 1 mass ratio of precursors. Such excellent EM attenuation properties can be attributed to the synergistic effect between magnetic and dielectric loss, polarization relaxation, conductive network, magnetic property, and multiple reflections, which claim an innovative design for advanced and effective EM wave absorbers having strong absorption capacity.