Electromagnetic attenuation displayed by La-Co substituted Ba-Sr hexaferrite nanoparticles and multiwall carbon nanotubes in polyaniline and polythiophene matrix

Our presented research aims to provide a systematic study of electrical, magnetic and microwave absorption properties of La-Co substituted Ba-Sr hexaferrite nanoparticles and MWCNTs, encapsulated in conductive polymer matrix. La-Co substituted Ba-Sr hexaferrite nanoparticles were produced using Sol-Gel auto combustion, whereas carrier fluid ultrasonication dispersion and in-situ polymerization were used to synthesize their composites with multiwall carbon nanotubes (MWCNTs) and conductive polymers. Structural investigations were accomplished using X-rays diffraction, secondary electron microscopy, Infrared and Raman Spectroscopy. The dielectric measurements revealed increased dielectric losses (4.86 at 1 GHz for pure nanoparticles, which increases up to 11.59 and 13.36 for ternary composites within PANI and PTh matrix), indicating good energy dissipation behavior. The decrease in magnetism was observed due to the weakening of exchange coupling or domain wall pinning at the interface of Ferrite-MWCNTs and Ferrite-Polymer, resulting in lowered saturation magnetization, remanence and coercivity values. The microwave absorption of our samples was evaluated as a function of frequency and thickness, revealing its dependence on the quarter wavelength phenomenon with maximum reflection loss of 40.4 dB observed for ternary composite with Polythiophene matrix at 7.54 GHz resonance frequency. The dependence of reflection loss peaks on matching thickness was analyzed using calculated thickness profiles, revealing their close agreement with simulated thickness. The study highlighted the potential of synthesized samples for electromagnetic signature reduction, in both commercial and military applications. The resonance bands were found to coincide with the operating frequency of military radars for shipborne and airborne surveillance and navigation in the X band (8-12 GHz).

Automated summary

Our research provides a systematic study of the electrical, magnetic and microwave absorption properties of La-Co substituted Ba-Sr hexaferrite nanoparticles and MWCNTs encapsulated in a conductive polymer matrix. The synthesized samples showed good energy dissipation behavior and microwave absorption performance, highlighting their potential for reducing electromagnetic signatures in commercial and military applications.