High-entropy ferrite with ultrafine heterostructured nanoclusters for broadband and intelligent switchable microwave absorption

Abstract

High-entropy (HE) ferrites with multi-element substitution emerge as promising candidates for microwave absorption (MA) due to their adjustable structure and unique HE effects. However, the effective absorption bandwidth (EAB) and the absorption strength of conventional kinetically random-mixing single-phase HE ferrites are limited. Herein, we report the synthesis of HE ferrite with the formation of ultrafine nanoclusters within the matrix anchored on carbon aerogel (CA) through rapid microwave heating. Benefiting from the binary formation energy differences among the constituent elements (Fe, Co, Ni, Cu, Mn, Ce, O), CeO2 nanoclusters are formed within the HE ferrite matrix. The CeO2/HE ferrite-decorated CA (CH/CA) exhibits polarization-enhanced electromagnetic attenuation, which substantially widens the EAB. At 4.0 mm thickness, CH/CA achieves a minimum reflection loss of −69.14 dB at 5.21 GHz, with EAB covering 92.9% of C-band. Notably, the EAB reaches 8.94 GHz at a thickness of 2.5 mm, covering 89.4% of the combined X- and Ku-bands. The integrated EAB of CH/CA at a thickness ranging from 1.5 to 5.0 mm reaches 14.82 GHz, which is comparable to the reported highest values. Furthermore, the CH/CA exhibits compressive strain-driven intelligent on/off switchable and frequency-tunable MA performance. This work proposes a phase-separated HE composite for broadband and smart MA applications.