rGO-tailored Ba–Sr hexaferrite composites for high-performance X-band microwave absorption and EMI shielding

Lightweight and ultrathin microwave absorbers demand a composition that simultaneously minimizes thickness, maximizes attenuation, and broadens bandwidth. Here we report a composite of reduced graphene oxide (rGO) and Ba 0.7 Sr 0.3 Fe 12 O 19 (BSF), which provides a tunable route to optimize absorber thickness, reflection loss, and shielding effectiveness. Pristine BSF shows weak absorption ( R L ≈ − 8 dB @ > 3 mm), whereas rGO incorporation enhances dielectric loss and achieves strong impedance matching and progressive thinning: BSFRG2 (− 37.69 dB @ 2.4 mm), BSFRG4 (− 35.83 dB @ 2.0 mm, 2.86 GHz bandwidth), BSFRG6 (− 26.18 dB @ 1.5 mm, Ku-band extension), and BSFRG8 (− 27.93 dB @ 1.3 mm, Ku-band extension). Attenuation analysis confirms absorption-dominated loss (> 99% for all BSF-rGO composite samples), while shielding effectiveness exceeds 21 dB for BSFRG6 and BSFRG8 samples, approaching commercial standards. The results establish rGO loading as a compositional knob to tune the trade-off between thickness, bandwidth, and shielding, providing a general design principle for next-generation ultrathin absorbers in EMI shielding and stealth technologies. Conceptual schematic illustrating potential application domains of BSF-rGO-based ultrathin microwave absorbers for electromagnetic wave attenuation. The illustrated aerospace and marine platforms are shown solely as schematic representations to indicate prospective EMI shielding and stealth-relevant scenarios.