Fabrication of flexible polymer nanocomposite films of PVDF/BaFe12O19/g-C3N4 for efficient EMI shielding in X-band frequency

Of late, synthesis and application of microwave-absorbing materials have become absolutely necessary to minimize the looming threat of electromagnetic (EM) pollution. The present study discusses the fabrication of multifunctional polymer nanocomposite films, presents the analysis of the resulting films using a polyvinylidene fluoride (PVDF) matrix with M-type barium hexaferrite (BaFe₁₂O₁₉) and graphitic carbon nitride (g-C₃N₄) fillers, and reports on their application in EM interference (EMI) shielding in the X-band (8–12 GHz) frequency range. Crystalline BaFe₁₂O₁₉ nanoparticles and g-C₃N₄ were prepared and used to fabricate PVDF/BaFe₁₂O₁₉/g-C₃N₄ composite films. The structural and compositional details of BaFe₁₂O₁₉ nanoparticles and the films were analyzed, along with the fraction of β-phase PVDF. The morphological, magnetic, ferroelectric, and dielectric properties of the films were studied using field emission scanning electron microscopy (FESEM), vibrating sample magnetometry, ferroelectric hysteresis, and dielectric response, respectively. In addition, the microwave absorption efficiency of the films was analyzed in the X-band frequency range with a vector network analyzer (VNA) using the waveguide technique. Magnetic loss observed in the films was due to domain wall resonance, whereas polarization, conduction, and eddy current losses were attributable to the interaction of PVDF, magnetic BaFe₁₂O₁₉, and semiconducting g-C₃N₄ fillers with the EM wave in the GHz frequency range. The VNA showed that the prepared PVDF/BaFe₁₂O₁₉/g-C₃N₄ composite films show a shielding efficiency of 99.9 %. In particular, the total shielding effectiveness (SE_T) of the film with 20 wt% of BaFe₁₂O₁₉ loading was found to be 52 dB in the X-band frequency range. Furthermore, the prepared films were flexible and showed high β fraction, saturation magnetization, and dielectric loss, along with moderate magnetic loss and high shielding efficiency, making them potential microwave absorbers in the GHz frequency region.