Porous and flake-like γ′-Fe4N@iron oxides with enhanced microwave absorption performance

Abstract The refined design of γ′-Fe4N structure plays a significant role in enhancing microwave absorption performance. γ′-Fe4N@iron oxides particles have been fabricated through an economical one-step gaseous nitriding method. The loss mechanism of the particles was studied, and the electromagnetic properties were also investigated in the frequency range of 2-18 GHz. The results show that γ′-Fe4N@iron oxides particles form a hierarchical structure with outer amorphous iron oxides, secondary outer Fe3O4, and inner γ′-Fe4N. Equipped with rugged surfaces and heterogeneities, the γ′-Fe4N@iron oxides particles feature multiple reflection and polarization characteristic, resulting in multiple relaxations in the interior of the as-fabricated particles, which enhance the microwave absorption properties. Its minimum reflection loss (RL) value can reach −38.5 dB with a thickness of 1.24 mm. We provide a facile method to fabricate particles with core-shell structure, which have great prospects for applications in microwave absorption field.