Electromagnetic characteristics of surface modified iron nanowires at x-band frequencies

Surface modified iron nanowire nanoparticles were prepared via reduction of iron salts (FeCl3·6H2O) under an applied magnetic field. To minimize the surface oxidation, dextran (0.05 and 0.25 wt. %) was added during the process and formed a thin passive layer over iron nanowires with alcohol and acetone used to wash iron nanowires. The complex permittivity (ɛ′-jɛ′′) and permeability (μ′-jμ″) of absorbers are measured by a cavity perturbation method from 7 to 14 GHz. In the present study, the iron nanowire prepared with 0.25 wt. % dextran and washed by acetone (D25AC) exhibited the best microwave absorption performance. Depending on the test frequency, D25AC possessed the largest permittivity loss ranged from 0.14 to 0.17 and relatively small permeability loss (<0.05). Its high permittivity dissipation is responsible for the excellent microwave absorption performance where the reflection loss was-7.7 dB at a matching frequency of 9.0 GHz.