High Performance Electromagnetic Interference Shielding in X‐Band Using Dysprosium‐Doped Cobalt Ferrite–Polypyrrole Nanocomposites

ABSTRACT Dysprosium‐doped cobalt ferrite and polypyrrole (PPy) nanocomposites (CoFe _1.96 Dy _0.04 O ₄ /PPy) were formed via in situ chemical oxidative polymerization using different weight percentages of CoFe _1.96 Dy _0.04 O ₄ nanoparticles. X‐ray diffraction (XRD) investigation conferred the multiphasic nature of materials, while Fourier transform infrared spectroscopy (FTIR) verified the creation of chemical bonds. Nanocomposites exhibited globular morphology with multiple magnetic domains, and agglomeration was observed due to the incorporation of magnetic nanoparticles. Thermogravimetric analysis (TGA) demonstrated a significant enhancement in nanocomposites' thermal stability as compared to pure PPy, with the PCFD40 sample achieving a char yield of 28.65% at 670°C. The degradation steps of PPy and the nanocomposites were thoroughly analyzed and explained. Magnetic characterization using a vibrating sample magnetometer (VSM) revealed that CoFe _1.96 Dy _0.04 O ₄ exhibited a saturation magnetization of 61.99 emu/g, while the CoFe _1.96 Dy _0.04 O ₄ /PPy nanocomposite with 40% ferrite content displayed a saturation magnetization of 18.06 emu/g. PPy exhibited diamagnetic behavior, which was modified by the incorporation of ferrite, resulting in induced magnetization. Dielectric and scattering parameters were obtained using a vector network analyzer (VNA) in the 8.2–12.4 GHz frequency range (X‐band), where the highest AC conductivity of 146 S/m at 12.2 GHz was recorded for PCFD40. The nanocomposites exhibited higher dielectric and magnetic losses, and as a result, PCFD40 has shown a total shielding effectiveness (SE _T ) of 35.18 dB, which can block up to 99.97% of the incoming electromagnetic radiation.