Controllable preparation of iron nanostructure/carbon nanotube composite materials and their microwave absorption properties

Iron nanoparticles, iron nanochains and composite materials of iron nanoparticles and carbon nanotubes were prepared using a simple reduction method. The complex permittivity and complex permeability in the frequency range of 1–18 GHz were measured, upon which the reflection loss was calculated. Iron nanochains have achieved effective absorption of electromagnetic waves in the frequency range of 6–14 GHz when the thickness varies from 1.5 to 2.5 mm. Moreover, the reflection loss reaches −40 dB when the thickness is 2 mm, indicating that the absorption rate is almost 100%. Composite materials of iron nanoparticles and carbon nanotubes have a better absorption performance in low frequency range (2.36–7.8 GHz). Iron nanochains are expected to become an excellent absorbent with strong absorption ability, wide band, small thickness and low cost. Composite materials of iron nanoparticles and carbon nanotubes are expected to be a light absorbent with good absorption of S and C bands (2–8 GHz, IEEE Std 521^TM-2002). By analyzing the relationship between attenuation constant, impedance matching, and reflection loss, we verified that for optimal absorption, the attenuation constant and the impedance matching must be perfectly matched.