Electromagnetic performance and microwave absorbing property of nanocrystalline Sm2Fe14B compound

Abstract

A new planar anisotropy Sm2Fe14B nanocrystal as an electromagnetic absorption material was prepared by melt-spinning method. The electromagnetic and microwave absorbing properties of Sm2Fe14B nanocrystal/nonmagnetic 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 Zin/Z0 equals 1, but the modulus of the ratio between the complex permittivity and permeability |e/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.