Electromagnetic wave absorption properties of mechanically mixed Nd2Fe14B/C microparticles

Nd2Fe14B/C microparticles were prepared by a mechanical mixing technique using a weight ratio of 2:1. Paraffin-bonded Nd2Fe14B/C composites were fabricated using 40 wt% microparticles, and their electromagnetic wave absorption properties were studied and compared with those of the paraffin-bonded Nd2Fe14B composites in the 2–18 GHz frequency range and for 1–5 mm thickness. The Nd2Fe14B/C–paraffin composites exhibit dual dielectric resonance in complex relative permittivity (ɛr) and essentially flat response in complex relative permeability (μr) rather than showing an abrupt change in both ɛr and μr as in the Nd2Fe14B–paraffin composites. The results are ascribed to the increased electrical resistivity in the Nd2Fe14B/C-paraffin composites and the protection on the magnetic properties of the Nd2Fe14B microparticles at 2–18 GHz by the presence of the C phase. Large reflection loss (RL) exceeding −10 dB and an optimal RL of −13.2 dB are achieved in the Nd2Fe14B/C–paraffin composites from 9.6 to 18 GHz at a thickness of 1.4–2.6 mm and at 18 GHz at a thickness of 1.4 mm, respectively.

Research highlights▶ We have prepared mechanically mixed Nd2Fe14B/C microparticles and dispersed them in a paraffin matrix to form Nd2Fe14B/C–paraffin composites. ▶ It has been found that the C phase can effectively increase the electrical resistivity of the Nd2Fe14B/C–paraffin composites and protect the magnetic properties of the Nd2Fe14B microparticles, resulting in dual dielectric resonance in ɛr and relatively flat response in μr in opposition to a dramatic variation in both ɛr and μr in the Nd2Fe14B–paraffin composites. ▶ Large RL in excess of −10 dB is observed in the Nd2Fe14B/C–paraffin composites from 9.6 to 18 GHz for thickness varying from 1.4 to 2.6 mm, with the optimal RL of −13.2 dB at 18 GHz for 1.4 mm thickness. ▶ The Nd2Fe14B/C–paraffin composites offer a relatively high-performance and cost-effective solution to absorb EM waves.