The effect of samarium substitution on magnetic properties and microwave absorption of the rare earth-iron-boron compounds and composites

Soft magnetic composites (SMCs), consisting of micrometer-scale magnetic particles and insulating materials, are extensively used as microwave absorbing materials (MAMs) due to their advantages concerning the lightweight, low cost, manufacturing flexibility, and adjustable microwave properties. SMCs composed of rare earth-iron intermetallics for MAMs are rarely studied. Here we show that Sm substituted (Nd1-xSmx)(2)Fe14B/paraffin composites exhibit excellent microwave absorption properties with an average value of reflection loss (RL) being below -10 dB at 6-18 GHz. The Sm substitution for Nd not only increases the complex permeability by 23%, decreases the permittivity by 24%, but also improves the characteristic impedance matching, due to their easy magnetization directions (EMDs) change from easy c-axis to c-cone, then to ab-plane with Sm concentration increasing. Thus the microwave absorption properties of these composites are greatly enhanced. Besides, (Nd0.7Sm0.3)(2)Fe-14/paraffin composite exhibits the strongest microwave absorption with an RL value of -43.8 dB and a small thickness of 1.5 mm at a frequency of 9.1 GHz, which can be one of the promising microwave absorbing materials. (C) 2020 Elsevier B.V. All rights reserved.