Synthesis of core-shell NiO/BFO nanocomposites for microwave absorbing applications

Magnetic core-shell nanostructures are often employed in high-performance microwave-absorbing applications due to their strong concurrent magnetic-dielectric losses. However, microwave absorbers designed using a single core-shell nanostructure may not attain the desired bandwidth of absorption. Herein, we introduce core-shell nanocomposites of (100-x)NiO/(x)BiFeO3 (x = 0, 25, 50, 75, & 100), prepared by a facile two-step sol-gel wet-chemical method for high-efficiency absorbing applications. Measurements of microwave absorption performance show that the core-shell 50NiO/50BiFeO3 (x = 50) nanocomposite exhibits a remarkable reflection loss of up to -27.3 dB at a matching thickness of 1.9 mm, and the corresponding -10 dB reflection loss bandwidth extends to 6.8 GHz (in X- and Ku-bands). The study suggests that the fabricated core-shell nanocomposite has the potential to be a promising candidate for lightweight microwave absorbing applications. This is evidenced by its showcased improved efficiency, attributed to the synergistic effects of magnetic-dielectric losses, multiple internal reflections, superior impedance matching, and enhanced interfacial polarization at NiO/BiFeO3 interfaces.