Chemistry Reference
In-Depth Information
Fig. 5.12
Top view SEM
image of iron catalysed pure
SiC nanowires
Fig. 5.13
Side view SEM
image of iron catalysed pure
SiC nanowires
The morphology of the wires grown with iron catalyst (Figs.
5.12
and
5.13
)is
slightly different, possibly owing to the higher growth temperature (1250
◦
C), but
the length and diameter are similar to those grown using nickel catalyst.
Some preliminary trials were done using gold as catalyst, the result was the
formation of randomly oriented nanowires (Fig.
5.14
), the gold was found also on
nanowires walls (Fig.
5.15
) owing to the high surface diffusivity of gold. This is
due to the growth temperature, far above the eutectic temperature of the gold-silicon
system.
SiC nanowires were successfully synthesized using magnetite (Fe
3
O
4
) nanopar-
ticles prepared with a coprecipitation procedure (Massart
1981
). From SEM images
(Fig.
5.16
) it was possible to observe a higher nanowires density. The average
diameter of the wires is 55 nm, the length is more than 10 nm.
Nanoparticles synthesis via co-precipitation allows a good control over particles
size and in principle this would result in a more accurate control over nanowires
diameter. In our case we couldn't notice this because a coalescence of nanoparticles
was observed prior to the growth during the heating stage. The final islands, even
