Multiscale design of carbon-based, high-efficiency and wide-frequency microwave-absorption composites

Dielectric- and magnetic-loss capabilities are directly related to the composition, micro-structure, and macro-scale structure of materials. However, despite progress in understanding loss capabilities, the investigation of designing electromagnetic-wave-absorbing materials with multiscale approaches is less developed. In the present contribution, we design dielectric/magnetic composites on the atomic and nanometer scales to obtain high-efficiency and wide-frequency microwave absorption. Atomic Fe, Ni and ferromagnetic phases of Fe3O4 and Ni3Fe are embedded in carbon at the nanoscale by means of a facile method. C–FeNi 5:8 showed maximum saturation magnetization values of 4.49 emu/g, an effective absorption band (fE) of 6 GHz and the minimum refection loss of −21.6 dB, which is attributed to better impedance matching, and invocation of quarter-wavelength interference-cancellation theory arising from the synergistic effects of atomic Fe, Ni and nanoscale Fe3O4 and Ni3Fe. Our study builds a ferromagnetic-dielectric double-loss complex with multiscale design, and offers a new way to realize both high-efficiency and wide-frequency microwave absorption.