Synthesis, characterization and electromagnetic properties of Fe 1− xCo x alloy flower-like microparticles

Abstract

Fe 1− x Co x alloy microparticles with size 3–5 μm and novel flower-like shapes were prepared by a simple low temperature reduction method. The electromagnetic properties for the paraffin matrix composites containing Fe 1− x Co x alloy microparticles were measured using a vector network analyzer in the 2–18 GHz frequency range. As a consequence of large surface- and shape-anisotropy energy for the flower-like shaped 3D microstructures, the strong natural resonance around 8–12 GHz and remarkable dielectric relaxation were observed in the complex permittivity and permeability spectrum, which are dominant in the enhanced electromagnetic wave absorption (EMA) performance. It was found that both the electromagnetic parameters of complex permittivity and permeability and the intensity and location of absorption band were remarkably dependent on the Co/Fe molar ratio. The enhanced EMA performance was obtained in these Fe 1− x Co x –paraffin ( x=0.4, 0.5, and 0.6) composites system. For the Fe 0.5Co 0.5 alloy, the reflection loss ( RL) exceeding −20 dB was obtained in the broad frequency range of 5.4–18 GHz with a thin sample thickness of between 1.0 and 2.9 mm. In particular, an optimal RL of −59 dB was obtained at 3.61 GHz with a thin thickness of 3.6 mm for the Fe 0.4Co 0.6 sample. The Fe 1− x Co x alloy microparticles may be attractive candidates for applications of microwave absorption materials with a wide frequency range and strong absorption in the high frequency region.