Magnetic properties of aligned iron containing nitrogen-doped multi-walled carbon nanotubes

Abstract

In this study, aligned nitrogen-doped multi-walled carbon nanotubes (A-CNTs) have been synthesized by Aerosol Assisted Chemical Vapour Deposition. Three solutions were nebulized (toluene, acetonitrile, 1:1 toluene/acetonitrile) and the as synthesized carbon nanostructures formed were collected from the three different reactions. After synthesis, the A-CNTs were purified by acid treatment and retained for further analysis. The effect of in-situ nitrogen doping on the internal structure of the aligned carbon nanotube bundles was studied by scanning electron microscopy. Transmission electron microscopy studies confirmed the formation of bamboo like tubes upon nitrogen doping. Thermal gravimetric analysis indicated that nitrogen doping does not significantly degrade the thermal stability of the A-CNT samples. The structural properties of the A-CNT after incorporation of nitrogen and the subsequent formation of bamboo-like tubes were studied by Raman spectroscopy. The presence of ferromagnetic impurities was identified by Mössbauer spectroscopy as α-Fe, γ-Fe, Fe2O3 and Fe3C, and these were further confirmed by SQUID hysteresis and temperature dependence magnetization data.