nanotube is monocrystalline, as might be expected since the formation of a grain
boundary requires additional energy. Filling a carbon nanotube with iron leads to a
ferromagnetic part with a high shape anisotropy; hence, such aggregates show a
large hysteresis in their magnetization curve.
Figure 5.26 represents a typical example of a magnetization curve of such a
composite, where the remanent magnetization as a function of the external field is
shown for an iron-filled carbon nanotube. This multiwall nanotube had a diameter
Figure 5.25 Multiwall carbon nanotube filled with CuJ. The different layers of the wall and the
lattice structure of the filling are clearly visible in this high-resolution electron micrograph [12].
(Reproduced with permission by IFW Dresden, 2007.)
Figure 5.26 Remanent magnetization of an
iron-filled carbon nanotube with a length of a
few micrometers and 60 nm diameter. To
obtain this data, the magnetic field was
changed from À1000 to 400 mT. At an external
field of approximately 250 mT, the
magnetization of the iron filling changed its
direction suddenly; this point is indicated as A.
After reducing the external field, the changed
direction is maintained. By extrapolation, the
direction of magnetization changes back at
–250 mT [12].
108j 5 Nanotubes, Nanorods, and Nanoplates
boundary requires additional energy. Filling a carbon nanotube with iron leads to a
ferromagnetic part with a high shape anisotropy; hence, such aggregates show a
large hysteresis in their magnetization curve.
Figure 5.26 represents a typical example of a magnetization curve of such a
composite, where the remanent magnetization as a function of the external field is
shown for an iron-filled carbon nanotube. This multiwall nanotube had a diameter
Figure 5.25 Multiwall carbon nanotube filled with CuJ. The different layers of the wall and the
lattice structure of the filling are clearly visible in this high-resolution electron micrograph [12].
(Reproduced with permission by IFW Dresden, 2007.)
Figure 5.26 Remanent magnetization of an
iron-filled carbon nanotube with a length of a
few micrometers and 60 nm diameter. To
obtain this data, the magnetic field was
changed from À1000 to 400 mT. At an external
field of approximately 250 mT, the
magnetization of the iron filling changed its
direction suddenly; this point is indicated as A.
After reducing the external field, the changed
direction is maintained. By extrapolation, the
direction of magnetization changes back at
–250 mT [12].
108j 5 Nanotubes, Nanorods, and Nanoplates