3.1 Mixing Elements
57
Some examples of composition dependence are shown in Fig. 3.22a–c for Ni–Au
[18], Au–Pt [19], and Pt–Ru [20], respectively, together with their phase diagrams.
For Ni–Au, it is clear that the work function gradually changes near 100% Au,
becomes constant regardless of the Ni content, and then suddenly decreases at 100%
Ni. A very similar composition dependence has been reported for Au–Pt; on the side
with higher solubility, the work function changes moderately but it sharply increases
on the other side (near 100% Pt in this case). In contrast, the Pt–Ru system shows a
very smooth composition dependence similar to that for an alloy, because it actually
Au
at. Percent Ni
Ni
1500
(a)
(b)
(c)
700
300
1064
1455
(Au,Ni)
L
100
0
2 0
4 0
6 0
8 0
1 0 0
500
900
1100
1300
955
810
Temperature, C
q
Au
at. Percent Pt
1800
1000
600
1064
1769
(Au,Pt)
L
400
0
20
40
60
80
100
800
1200
1400
1600
1260
0
2 0
4 0
6 0
8 0
1 0 0
5.3
5.4
5.5
5.6
5.7
5.8
work funccon (eV)
Pt at%
Temperature, C
q
Temperature, C
q
Pt
at. Percent Pt
Ru
1800
1000
600
1769
2334
(Pt)
L
400
0
2 0
4 0
6 0
8 0
1 0 0
800
1200
1400
1600
2130
(Ru)
0
2 0
4 0
6 0
8 0
1 0 0
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
work funccon (eV)
Ru (at%)
Fig. 3.22 a Phase diagram and work function [18] for Au–Ni system. b Phase diagram and work
function [19] for Au–Pt system. c Phase diagram and work function [20] for Pt–Ru system