Preparation and Microwave Absorption of Nitrogen-Doped Carbon Nanotubes With Iron Particles

Abstract

In this paper, the nitrogen-doped carbon nanotubes with iron particles (NCNTs/Fe) for microwave absorption were synthesized by a simple method that could be used for the large-scale production. The as-prepared sample can easily disperse into the matrix without any pretreatments. The micrometer to nanometer size Fe particles encapsulated in shells and bamboolike nanotubes with the diameter ranged from 50 to 500 nm were observed. The Fe phase structures of the NCNTs/Fe, which mainly consist of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha -\text {Fe}$ </tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gamma -\text {Fe}$ </tex-math></inline-formula> , and Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> C, were explored by the Mössbauer spectroscopy and the X-ray diffraction method. The electromagnetic properties of the composites of the NCNTs and paraffin at different mass ratios were studied. Interestingly, the material exhibits an excellent microwave absorption property, i.e., the reflection loss (RL) of 1.58 mm NCNTs/Fe mixed with paraffin (20% mass ratio) could achieve −57.96 dB at 14.96 GHz with a bandwidth (RL ≤ −10 dB) of 3.52 GHz.