Chemistry Reference
In-Depth Information
Fig. 5.5
SEM image of iron
film after 2 min dewetting
Fig. 5.6
SEM image of iron
film after 5 min dewetting
Fe(NO
3
)
3
·
8,7H
2
O
→
Fe(NO
3
)
3
·
2H
2
O + 6,7H
2
O
↑→
(580
◦
C) Fe(OH)
3
+ 0,5H
2
O
(826
◦
C) Fe
2
O
3
+ 1,5H
2
O
→
↑
+ 3NO
3
↑→
↑
(after Elmasry et al.
1998
)
Gaseous species that are formed during heating are designated with
↑
symbol and
it means they drift apart.
After the introduction of carbon monoxide for nanowires growth (see following
section) a reduction process of ferric oxide or nickel oxide takes place and it pro-
duces metallic iron or metallic nickel respectively through different reduction paths,
depending on kinetics and thermodynamic conditions (Jozwiak et al.
2007
; Szekely
and Lin
1976
).
Subsequently the metal forms an alloy with the silicon of the substrate and, after
transformation into liquid phase, it creates a droplets array on the surface (Fig.
5.6
).
From the SEM images the transition is clearly visible: the oxide forms islands
whose elongated shape demonstrate that the liquid phase wasn't reached (Fig.
5.7
),
