Effect of Synthesis Approaches and Morphological Properties on Dielectric Enhancement and Microwave Absorption of Fe3O4/PANI Nanocomposites

In the present work, Fe3O4 spherical (Fe3O4-cop) and raspberry-like (Fe3O4-hyd) nanoparticles were synthesized via co-precipitation and hydrothermal routes, respectively. Fe3O4/polyaniline (PANI) nanocomposites were prepared by in situ oxidative polymerization of aniline monomer in the presence of the Fe3O4 materials. Characterization of the nanocomposites by XRD, FT-IR, FESEM, and TEM techniques revealed a core/shell structure for Fe3O4-hyd/PANI, unlike the PANI blocks with embedded Fe3O4 and gamma-Fe2O3 observed in Fe3O4-cop/PANI composites. The larger and pure magnetite nanoparticles produced with the hydrothermal process and the respective nanocomposite with PANI possess higher magnetization and coercivity values, according to the magnetic investigation with VSM. Moreover, according to the electromagnetic characterization in the X-band, the Fe3O4-hyd/PANI nanocomposite exhibits the highest complex permittivity level, as a consequence of increased interfacial polarization in the Fe3O4-hyd/PANI system. On this account, reflection loss measurements have shown the superior microwave absorption capability of Fe3O4-hyd/PANI composite, compared with Fe3O4-cop/PANI, with a measured maximum of -31.28 dB at 8.5 GHz for 3.5 mm layer thickness.