Synthesis and excellent electromagnetic wave absorption properties of parallel aligned FeCo@C core–shell nanoflake composites

Abstract

Soft magnetic FeCo@C nanoflakes were prepared by a simple anoxic annealing technique. The crystalline structure, morphology, and microstructure were systematically characterized. The frequency-dependent electromagnetic and absorbing properties of the nanoflake paraffin composites were investigated in the 0.1–18 GHz frequency range. The rotational orientation of the composite in an applied magnetic field was performed to make the plane of nanoflakes parallel to each other. The measurement results showed that both the complex permeability and complex permittivity of the FeCo@C composite were enhanced after orientation. The calculated absorption properties showed that the orientation plays an important role in decreasing the absorber thickness and increasing the absorption performance. For the oriented FeCo@C nanoflake paraffin composite, the maximum reflection loss of −48.2 dB at 2.1 mm thickness and the effective absorption with RL < −10 dB from 2.5 to 12 GHz at thickness ranging from 1.5 to 4.0 mm were obtained.