Structural, dielectric, magnetic and electromagnetic interference shielding investigations of polyaniline decorated Co_0.5Ni_0.5Fe₂O₄ nanoferrites

In the present work, we have investigated structural, dielectric, ac conductivity, magnetic and electromagnetic interference (EMI) shielding effectiveness (SE) performance of Co_0.5Ni_0.5Fe₂O₄ nanoparticles and Polyaniline (PANI)/Co_0.5Ni_0.5Fe₂O₄ nanocomposites for EMI shielding applications. The Co_0.5Ni_0.5Fe₂O₄ nanoparticles were synthesized by solution combustion method. PANI/Co_0.5Ni_0.5Fe₂O₄ nanocomposites were prepared by in-situ polymerization method. As-prepared samples were examined by using X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The microstructural and composition studies have been performed using Field emission scanning electron microscopy (FE-SEM) and Energy Dispersive X-ray (EDX) analysis. Thermal stability of the composite was analyzed using thermo gravimetric analysis (TGA). Frequency dependence of dielectric and ac conductivity (σ_ac) studies have been undertaken on the Co_0.5Ni_0.5Fe₂O₄ nanoparticles and PANI/Co_0.5Ni_0.5Fe₂O₄ nanocomposites in the frequency range 50 Hz–5 MHz. The electrical conduction mechanism in the synthesized samples found to be in accordance with the electron hopping model. Present Co_0.5Ni_0.5Fe₂O₄ nanoparticles and PANI/Co_0.5Ni_0.5Fe₂O₄ nanocomposites exhibited hysteretic behavior under the applied magnetic field at room temperature. The maximum values 39.9 and 58.22 dB of SE at 50 Hz were obtained at room temperature for Co_0.5Ni_0.5Fe₂O₄ nanoparticles and PANI/Co_0.5Ni_0.5Fe₂O₄ nanocomposites respectively. Present Co_0.5Ni_0.5Fe₂O₄ nanoparticles decorated with PANI can be recognized as a promising functional material for the absorbing of electromagnetic (EM) waves due to large amount of dipole polarizations in the polymer backbone and at the interfaces of the Co–Ni ferrite nanoparticles and PANI matrix.