Electromagnetic performance and microwave absorbing property of nanocrystalline Sm_2Fe_(14)B compound

摘要

A new planar anisotropy Sm_2Fe_(14)B nanocrystal as an electromagnetic absorption material was prepared by melt-spinning method. The electromagnetic and microwave absorbing properties of Sm_2Fe_(14)B nanocrystalonmagnetic matrix composite in the frequency range of 0.1-10 GHz were measured and calculated. At the perfect matching point (2.9 GHz), the minimum reflection loss reaches -42.0 dB at the matching thickness of 3.1 mm. Furthermore, the calculation shows that the normalized input impedance Z_(in)/Zo equals 1, but the modulus of the ratio between the complex permittivity and permeability |/μ∣ is far away from unity at the perfect matching point. The effective permeability of the composite was simulated using the combination of the Landau-Lifshitz-Gilbert equation and Bruggeman's effective medium theory; the agreement between the experimental data and the theoretical one demonstrates that the magnetic loss in the composite is mainly caused by natural resonance.