Microwave absorbing properties of FeCo/Cr₂AlC-based multilayer structure over a wide-temperature range

Magnetic-electric composite microwave absorbing materials have unique advantages in expanding absorption bandwidth and reducing material thickness. However, the rapid decline in permeability with increasing temperature severely restricts their application in a wide temperature range. Meanwhile, the temperature-dependent evolution of magnetic-electric synergy remains unclear. Here, Cr₂AlC-coated FeCo magnetic flakes are prepared and used as building blocks to design efficient and stable multilayer microwave absorbing materials operating within the temperature range of 298–473 K. The Cr₂AlC coating effectively adjusts the permittivity, improves the permeability, and enhances the stability of FeCo flakes at high temperatures. The modulation of the magneto-electric synergistic effect enables the composite to achieve excellent impedance matching and a high absorption coefficient over a wide temperature range. Furthermore, a multilayer composite absorbing material is designed using FeCo/Cr₂AlC as filler, consisting of one wave-transmission layer, three wave-absorption layers and one wave-reflection layer. This material achieves broadband and stable microwave absorption from 298 to 473 K, and reaches a minimum reflection loss of − 45.2 dB and a maximum bandwidth of 3.9 GHz below a thickness of 2 mm at 473 K.