Microscopic insight into the bilateral formation of carbon
spirals from a symmetric iron core
Hidetsugu Shiozawa,1∗ Alicja Bachmatiuk,2 Andreas Stangl,1 David C. Cox,3
S. Ravi P. Silva,3 Mark H. Rümmeli,2 Thomas Pichler1
1
Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Wien, Austria,
2
3
IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany,
Advanced Technology Institute, University of Surrey, Guildford, GU2 7XH, UK
∗
To whom correspondence should be addressed; E-mail: hidetsugu.shiozawa@univie.ac.at.
12.02.2016
Supplementary Figure S1
In Fig. S is the magnified TEM micrograph of the same cross sectional cut. The dark
rectangular object is the iron core. Within the arms, patterns of dark-bright contrasts are
observed. Again, these patterns look approximately mirrored at the axis of the arm and
construct a herringbone-like pattern that resembles the appearance of the leaf’s veins. The
patterns in the arms at the opposite side (upper and lower) of the core seem to be mirrored too.
The angle of the fish bones are leaned upwards in the upper arm (the fish heading
downwards), opposite to the orientation of the graphite layers observed with SAED (the fish
heading upwards). Additionally, there is a bright spot observed in the vicinity of the tip of the
iron cone, originating from which are some linear bright contrasts extending parallel to the
arm’s axis, that resembles the fish spine. The origin of this herringbone pattern is sought via
higher resolution TEM observations. The insets in Fig. S show the high resolution TEM
micrographs taken in the vicinity of the core. In the micrographs we clearly see the patterns of
the aligned graphite layers. Closing up around the boundary between the core and the arm, we
can see that the layers of graphite are oriented roughly parallel to the core surface. The layers
in each micrograph are rather randomly undulating, but as a whole arranged in one direction,
as ascertained by the regular patterns of the graphite [002] diffraction observed in the fast
1
Fourier transform (FFT) image on the right insets. The FFT support that the graphite layers
are roughly parallel to the surface of the core, perfectly in line with the SAED observations
over the arms. Right on top of the cone tip (the top FFT), a vacancy inbetween the parallel
graphite layers is observed as bright area, which is the origin of the bright contrasts observed
in the TEM. Hence, the observed fish spine extending along the arms show the presence of the
bamboo-like structures made of an array of the vacancies in the graphite layers. In the middle
inset, defects are seen as darker fringes propagating radially from the iron core, or
perpendicular to the graphite layers. This is inline with what is observed in a larger scale TEM
micrograph in Fig S as part of the herringbone structure.
Figure S1
2
Supplementary Figure S2
Fig. S is the scanning electron micrograph showing the symmetric objects produced in large
yield and high purity. Most of the objects observed exhibit a similar morphological identity
whilst there are variations in size and shape.
Figure S2
3