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.