Integration of high-entropy spinel/FeCo magnetic composites with carbon nanotubes for enhanced microwave absorption properties

The integration of magnetic materials with dielectric carbon architectures is promising for enhancing microwave absorption properties due to their inherent resonance properties. In this paper, magnetic composites constituted by high-entropy spinel oxides/conductive heterogeneous FeCo phase were obtained through solid-phase sintering and hydrogen reduction process, which show excellent wave-absorbing properties by modulating the elemental Cr content. Further coating with carbon nanotubes via chemical surface modification dramatically improves the composite’s microwave absorption capability across multiple frequency bands, achieving a reflection loss of − 43.10 dB at 3.1 mm thickness in the C-band and an exceptional minimum reflection loss of − 44.20 dB at 1.5 mm thickness in the Ku-band. This tri-phase composite demonstrates a wide effective absorption bandwidth of 4.77 GHz at a remarkably thin matched thickness of just 1.3 mm. The obtained superior microwave-absorbing properties were ascribed to excellent impedance matching and attenuation properties contributed by natural resonance, interfacial polarization, conductive loss, multiple reflections, and scattering in the multi-component system with abundant heterogeneous interfaces. This unique absorption behavior highlights its potential for next-generation compact microwave absorption applications.