Effect of heat treatment on the electromagnetic absorption performance of spherical, flower-like and thorny Co@Fe composite particles

values of the heat-treated spherical, flower-like, and thorny Co@Fe composite particle samples exhibited a downward trend with increasing electromagnetic wave frequency. In the 2-6 GHz range, magnetic losses were primarily due to natural resonance, while in the 6-18 GHz range, magnetic losses resulted from the combined effects of eddy current loss and natural resonance. The maximum attenuation constants of the heat-treated spherical, flower-like, and thorny Co@Fe composite particle samples showed a slight increase, although the value of the thorny Co@Fe particle sample decreased. Heat treatment improved the impedance matching of the spherical Co@Fe particle samples, while the impedance matching performance of the flower-like and thorny Co@Fe composite particle samples deteriorated. Heat treatment enhanced the electromagnetic wave absorption performance of the spherical and flower-like Co@Fe particles to some degree, while for the thorny Co@Fe particles, the electromagnetic wave absorption performance did not improve after heat treatment. The heat-treated spherical Co@Fe particle achieved a minimum reflection loss of -15.36 dB at a thickness of 2.0 mm, with an effective absorption bandwidth of 4.96 GHz.