Possibility of the existence of magnetic ordering in carbon nanotubes (CNTs) was theoretically predicted, but so far nobody has been able to experimentally confirm the existence of localized magnetic moment in carbon. The main obstacle is a presence of residual (magnetic) metal catalyst nanoparticles in CNTs from the production process. Group from Institute of Physics in collaboration with J. Heyrovsky Institute tested several methods for CNTs purification. The results show that commonly used macroscopic methods are not suitable to ascertain the purity of material – it has been demonstrated that even if all macroscopic methods indicate a high purity of the treated sample, a non-negligible amount of the metal may still be present and the metal content has to be examined using local and element sensitive probes.
Schematic illustration of purification and detection of metal content in CNTs. (a) CNTs with magnetic particles before and after purification; (b) left: normalized XAFS spectrum with free Fe atom absorption (black line) and Fourier transformation kχ(k) magnitude with marked bondings for Fe–O (red), Fe–C (green) a Fe–Fe (blue), both for sample with annealing temperature of 2200 °C; (c) illustration of CNTs purification process for cases described in text.
1Institute of Physics of the ASCR, v.v.i., Na Slovance 2, 182 21 Prague 8, Czech Republic
2J. Heyrovsky Institute of Physical Chemistry of the ASCR, v.v.i., Dolejskova 3, 182 23 Prague 8, Czech Republic
3Institut fur Synchrotronstrahlung (ISS), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein Leopoldshafen, Germany
Copyright © 2008-2014, Fyzikální ústav AV ČR, v. v. i.
