Polymorphous Fe/FexOy composites: One-step oxidation preparation, composition control, and static magnetic and electromagnetic characteristics

Polymorphous Fe/FexOy core–shell and urchin-like composites were synthesized via a facile oxidation process at relatively low temperatures (100–300 °C) in the absence of surfactants or an external magnetic field. The oxidation temperature plays a key role in determining the morphology, crystal size, and composition of the resulting products. The static magnetic and electromagnetic (EM) properties of Fe/FexOy composites are influenced by their morphology, crystal size, and composition. In this study, excellent soft magnetic properties and enhanced permeability were obtained from core–shell Fe/FexOy composites with low FexOy shell contents and low surface anisotropy. In contrast, high coercivity and dielectric performance were exhibited by urchin-like Fe/FexOy composites with high shape and surface anisotropy. This work provides insights into the absorption mechanism of urchin-like complex absorption materials.

► The FexOy nanoshell morphology and composition evolution of Fe/FexOy core–shell and urchin-like composites with oxidation temperature.
► The establishment of the relationship between microstructure of FexOy nanoshells and properties of Fe/FexOy core–shell and urchin-like composites (e.g. static magnetic, and microwave electromagnetic and absorbing properties).
► The analysis of the absorption mechanism of Fe/FexOy composites.