234 10 Electrical Properties
Not only metallic nanowires and carbon nanotubes are able to carry extremely
high densities of electrical currents. Similar phenomena are found with polypyrole (an electrically conductive organic compound) coated imogolite (see Chapter
5), a silicate crystallizing in one dimension, only [4]. The effect of imogolite
surface functionalization with polypyrole on the electric conductivity is given in
Figure 10.7.
Figure 10.7 gives a current of 10
−7 A at a voltage of 0.1 V. Even when the current
is only in the range of 10
−7 A, the current density, however, is, because of the small
diameter of these fibers, huge, it is in the range of a few 10
10 A m
−2 . Again, this is
by far more than it could be transported through a macroscopic copper wire. Even
when the resistance of such wires is relatively high, the increase of the electrical
conductivity of an order of magnitude promises many interesting technical appliFigure 10.6 Current density to failure for
gold nanowires of different diameter
determined at room temperature. It is
important to realize the increasing maximum
current density with decreasing wire diameter
[3].
60
70
80
90
100
110
120
diameter of gold wire [nm]
0x10
0
1x10
12
2x10
12
3x10
12
4x10
12
current
density
at
failure
[A
m
–2
]
Figure 10.7 Effect of polypyrole coating of imogolite on the electrical conductivity. The figure
depicts a plot of electrical current versus applied voltage for the pure and the coated imogolite
fibers [4].
–0.1
–0.05
0
0.05
0.1
voltage [V]
–1.5x10
–7
–1.0x10
–7
–5.0x10
–8
0.0x10
0
5.0x10
–8
1.0x10
–7
1.5x10
–7
current
[A]
Imogolite uncoated
Imogolite coated with polypyrole