Electromagnetic wave absorption properties of mechanically mixed Nd2Fe14B/C microparticles

Abstract Nd 2 Fe 14 B/C microparticles were prepared by a mechanical mixing technique using a weight ratio of 2:1. Paraffin-bonded Nd 2 Fe 14 B/C composites were fabricated using 40 wt% microparticles, and their electromagnetic wave absorption properties were studied and compared with those of the paraffin-bonded Nd 2 Fe 14 B composites in the 2–18 GHz frequency range and for 1–5 mm thickness. The Nd 2 Fe 14 B/C–paraffin composites exhibit dual dielectric resonance in complex relative permittivity ( ɛ r ) and essentially flat response in complex relative permeability ( μ r ) rather than showing an abrupt change in both ɛ r and μ r as in the Nd 2 Fe 14 B–paraffin composites. The results are ascribed to the increased electrical resistivity in the Nd 2 Fe 14 B/C-paraffin composites and the protection on the magnetic properties of the Nd 2 Fe 14 B 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 Nd 2 Fe 14 B/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.