Core-Shell Co3Fe7@C Composite as Efficient Microwave Absorbent

To reduce the density of the absorbent Co3Fe7, a core-shell Co3Fe7@C microwave absorbent was synthesized by preparing an iron/cobalt-containing carbon precursor followed by high-temperature carbonization. According to the X-ray diffraction (XRD) and transmission electron microscopy (TEM) results, Co3Fe7 particles were coated with graphitized carbon layers to form a core-shell structure. Furthermore, the Co3Fe7@C composite with a surface area and density of 358.5 m(2)center dot g(-1) and 2.25 g center dot cm(-3), respectively, exhibited excellent microwave absorbability. A minimum reflection loss (RL) of -43.5 dB and an effective bandwidth (RL below - 10 dB) of 4.1 GHz were obtained at the coating thickness of 2 mm, which could be mainly attributed to the effective impedance match and multiple interfacial polarizations. Owing to the low density and remarkable microwave absorption, we believe that the Co3Fe7@C composite can be a promising candidate for use as a lightweight and efficient microwave absorbent.