The improvement of radar absorption performance in Mn_xFe_3–xO₄/PANI/AC nanocomposites by manipulating the composition of 3d transition metal elements

Radar-absorbing materials (RAMs) have been extensively employed, particularly in national security stealth technologies. Even though various novel RAMs have been invented, iron oxides still attract tremendous attention due to their distinctive properties that are suitable for radar absorption applications. However, some development should still be carried out to improve the feasibility of iron oxides as RAMs. In this study, iron oxides-based RAMs were developed by manipulating the composition of 3d metal transition elements, Fe and Mn, which mainly influence the radar absorption performance. We also use a compositing strategy by combining this iron oxide with conductive and dielectric polymer materials to form Mn_xFe_3–xO₄/PANI (polyaniline)/AC (activated carbon) nanocomposites. The nanocomposites were synthesized using the coprecipitation method with x = 0–1.2 variation. The RAMs functioned in the X-band frequency range (approximately 7–13 GHz) with a thickness of 2 mm to 5 mm. The Mn_xFe_3–xO₄/PANI/AC nanocomposites were successfully fabricated by various examinations. The Mn²⁺ ion was incorporated into Fe₃O₄, while the nanocomposites exhibited sphere-like morphologies constructed from Mn_xFe_3–xO₄, AC, and PANI having aggregates, granules, and chains forms, respectively. Moreover, the nanocomposite sample exhibited superparamagnetic properties, with the saturation magnetization decreasing with the increase in the Mn²⁺. Interestingly, the Mn_xFe_3–xO₄/PANI/AC nanocomposites with x = 1.2 showed a high radar absorption performance with a reflection loss of –42 dB at 9.3 GHz, which mainly attributed to the magnetic loss mechanism and, thus, makes the obtained nanocomposite very potential for radar absorption applications. We believe our findings could pave the way for the realization of iron oxide-based RAMs for radar absorption applications.