64
Transition Metal Silicide Nanowires
Table 3.1
67,72 –109
IA IIA IIIB IVB VB VIB VIIB VIII VIII VIII IB IIB
H
4
Si
Li
22
Si
5
Li
13
Si
4
Li
7
Si
3
Li
12
Si
7
LiSi
NaSi
NaSi
2
Na
8
Si
46
Na
x
Si
136
Mg
2
Si
12
Si
17
8
Si
46
7
Si
46
Ca
2
Si
Ca
5
Si
3
CaSi
Ca
3
Si
4
CaSi
2
Sc
5
Si
3
Sc
5
Si
4
ScSi
Sc
3
Si
5
Ti
3
Si
Ti
5
Si
3
Ti
5
Si
4
TiSi
TiSi
2
V
3
Si
V
5
Si
3
VSi
2
Cr
3
Si
Cr
5
Si
3
CrSi
CrSi
2
M
6
Si
Mn
4
Si
Mn
3
Si
Mn
5
Si
2
Mn
5
Si
3
MnSi
MnSi
1.8
Fe
3
Si
(Fe
5
Si
3
)
FeSi
FeSi
2
(Co
3
Si)
Co
2
Si
CoSi
CoSi
2
Ni
3
Si
Ni
31
Si
12
Ni
2
Si
Ni
3
Si
2
NiSi
NiSi
2
Cu
5
Si
Cu
15
Si
4
Cu
3
Si
65
IA IIA IIIB IVB VB VIB VIIB VIII VIII VIII IB IIB
12
Si
17
5
Si
46
Sr
2
Si
Sr
5
Si
3
SrSi
SrSi
2
Y
5
Si
3
Y
5
Si
4
YSi
Y
2
Si
3
Y
3
Si
5
Zr
3
Si
Zr
2
Si
Zr
3
Si
2
Zr
5
Si
4
ZrSi
ZrSi
2
5
Si
3
NbSi
2
Mo
3
Si
Mo
5
Si
3
MoSi
2
Tc
4
Si
Tc
3
Si
Tc
5
Si
3
TcSi
Tc
4
Si
7
Ru
4
Si
3
RuSi
Ru
2
Si
3
RuSi
2
Rh
2
Si
Rh
5
Si
3
Rh
3
Si
2
RhSi
Rh
4
Si
5
Rh
3
Si
4
Pd
21
Si
5
Pd
14
Si
3
Pd
3
Si
Pd
2
Si
Pd
39
Si
20
Pd
19
Si
10
CsSi
Cs
7
Si
136
Ba
2
Si
Ba
5
Si
3
BaSi
Ba
3
Si
4
BaSi
2
La
5
Si
3
La
3
Si
2
La
5
Si
4
LaSi
LaSi
2
Hf
2
Si
Hf
3
Si
2
Hf
5
Si
4
HfSi
HfSi
2
Ta
3
Si
Ta
2
Si
Ta
5
Si
3
TaSi
2
W
5
Si
3
WSi
2
Re
2
Si
ReSi
1.8
OsSi
Os
2
Si
3
OsSi
2
Ir
3
Si
Ir
3
Si
2
IrSi
Ir
4
Si
5
Ir
3
Si
4
Ir
3
Si
5
IrSi
3
Pt
25
Si
7
Pt
3
Si
Pt
5
Si
2
Pt
17
Si
8
Pt
2
Si
Pt
6
Si
5
PtSi
Note
in parenthesis.
Introduction
66
Transition Metal Silicide Nanowires
69–71
mostly of rare earth
of free-standing transition metal silicide NWs, and their current and
potential future applications.
3.2 Formation of Bulk and Thin-Film Metal
Silicides in Diffusion Couples
110
growth
111
silicides widely used in technological applications are often formed
4,112,113
atoms to a growth interface, nucleation of new silicide phases, and
Figure 3.2
67
3.2.1 Basic Description
solid, vapor, or liquid;
114
however, one most commonly encounters
113,115
A
the molecular level, i.e., greater than 10 µ
113
to grow and nucleate other silicide phases. The actual sequence of
the silicides produced depends greatly on the relative quantities
and the experimental conditions. The important considerations of
3.2.2 Diffusion, Thermodynamics, and Nucleation in
Silicide Reactive Phase Formation
3.2.2.1 Diffusion and the dominant diffusing species
one of the atoms (i.e., either the metal species or Si) is much more
Formation of Bulk and Thin-Film Metal Silicides in Diffusion Couples
68
Transition Metal Silicide Nanowires
116
depends strongly on the
nature of the phases present in the system. Initially, the metal and Si
into each other, forming a solid solution at the interface. However,
formed layer is the DDS.
compound, such as a silicide, generally follows the Cu
3
Au ordered
rule.
117
According to this rule, the majority constituent of an
pure element. Silicides tend to follow this rule fairly well, with the
118
2
and CoSi
2
).
116
Arrenhius relation,
D = D
0
e
(–Q/RT)
with D D
0
Q the activation
energy of the process, and RT the thermal energy. Further the
n
formula,
LnDt
D
= 2
with L
D
n
the system (i.e., 1, 2, or 3), and t
–8
cm
2
/s
D is closer to
10
–12
cm
2
/s.
116
intended to give a sense of the scale over which one must consider
D can vary over six orders of
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.