Improved Electromagnetic Interference Shielding Response of Polyaniline Containing Magnetic Nano-ferrites

Improvement of electromagnetic interference (EMI) shielding materials with miniaturization of devices is an important area of research in various applications like communication, electronic warfare, defense, and different civilian applications. Nano-crystalline ferrite, MFe2O4 (M = Ni, Zn, and Co), powders have been synthesized by sol-gel citrate nitrate precursor method. The crystalline size of samples was found in the range of 20–45 nm as analyzed by XRD and TEM analysis. Polyaniline/ferrite nano-composites with 50 wt% were synthesized by mechanical blending. The structural and magnetic properties of the nano-particles were characterized by using Rietveld analysis of powder X-ray diffraction and vibrating sample magnetometer (VSM) respectively. Using the Rietveld refinement, the goodness of fit, interatomic distance, Bragg contribution, and R factors have been determined. Ferrites and their nano-composites, under applied magnetic field up to 20 KOe, exhibited the hysteresis loops of ferromagnetic nature with maximum saturation magnetization of 51.68 emu/g shown by CoFe2O4. The electromagnetic shielding parameters (various shielding effectiveness and reflection loss) and microwave absorbing properties were measured in X band frequency region (8.2–12.2 GHz). Nano-composites show promising and enhanced EMI shielding behavior with overall highest SE value of 52 dB shown by CoFe2O4 composite.