One-pot synthesis of FeCo alloy and iron borate composite nanorods with excellent electromagnetic wave absorption properties

Abstract

FeCo alloy and iron borate composites with homogeneous morphologies of the nanorods were successfully synthesized by heat treatments on iron oxide and Co–B composites. The nanorods have mean diameters of about 60 nm and lengths of several micrometers. The crystallization phases of the composites are composed of Co₇Fe₃, Co, Fe(BO₂)₂ and Fe₂Fe(BO₃)O₂. The composite nanorods exhibited ferromagnetism with a high coercivity value attributed to the integration anisotropy of shape and interface anisotropy since the increase in the effective anisotropy μ′′ of the nanorods exhibited peaks at around 11 GH. Because of the better impedance matching and higher attenuation caused by the homogeneous morphologies of the nanorods and eddy current effects of alloys virtually weakened by existence of iron borate, an excellent electromagnetic wave absorption performance was obtained in composite nanorods, in which the maximum reflection loss can reach −35.0 dB with reflection loss values of less than −10 dB with a frequency width more than 4 GHz for a thickness of only 1.5 mm.