Synthesis, field emission and microwave absorption of carbon nanotubes filled with ferromagnetic nanowires

Carbon nanotubes filled with ferromagnetic metal nanowires (M-CNTs) were synthesized by using chlorine-contained benzene (e.g. trichlorobenzene) as precursor. The wall thicknesses of M-CNTs synthesized by trichlorobenzene are much thinner than those by precursor without Cl (e.g. benzene). As-synthesized thin-walled M-CNTs exhibit remarkably enhanced field electron emission performance with a low turn-on field of 0.3 V/μm and better field-emission stability. Microwave-absorption coatings were made by dispersing as-synthesized M-CNTs into epoxy resin matrix. It is found that the reflection losses in S-band (2–4 GHz), C-band (4–8 GHz) and X-band (8–12 GHz) are enhanced in the order of FeCoNi-CNTs < FeNi-CNTs< FeCo-CNTs. The areal density of as-prepared coatings is only 2.35 kg/m2 when the coating thickness is 2.0 mm. This demonstrates that M-CNTs are promising to be used as lightweight and wide-band microwave absorbers.