Biomedical Engineering Reference
In-Depth Information
(a)
(b)
-3 × 10
6
25
50
100
-2 × 10
7
-2 × 10
6
-1 × 10
7
-1 × 10
6
0 × 10
0
0 × 10
0
0 × 10
0
0 × 10
0
2 × 10
7
4 × 10
7
Real
Z
(Ohm)
6 × 10
7
2 × 10
6
4 × 10
6
6 × 10
6
Real
Z
(Ohm)
(c)
(d)
-5 × 10
4
-4000
150
250
300
200
-4 × 10
4
-3000
-2 × 10
4
-2000
-2 × 10
4
-1000
-1 × 10
4
0 × 10
0
0
4 × 10
4
8 × 10
4
1.2 × 10
5
2 × 10
3
4 × 10
3
6 × 10
3
8 × 10
3
1 × 10
4
0
Real
Z
(Ohm)
Real
Z
(Ohm)
(e)
-3 × 10
4
400
-2 × 10
4
-1 × 10
4
0 × 10
0
0 × 10
0
1 × 10
4
2 × 10
4
3 × 10
4
Real
Z
(Ohm)
FIGURE 4.15
Cole-Cole plots of MPECVD diamond films at different temperatures: (a) 25°C, (b) 50°C and 100°C, (c) 150°C
and 200°C, (d) 250 and 300°C, and (e) 400°C. (From Ye, H.T., PhD thesis, University College London, 2006. With
permission.)
no significant variation in impedance spectroscopy because of its large resistance differ-
ence between diamond and electrode. Therefore, the impedance contribution from the
electrodes could be ignored in diamond-based materials that are less conductive.
Critical to the identification of the grain boundary and grain interior contribution is
the simulated capacitance value for each semicircle. Experimentally, the low-frequency
dispersion corresponds to the grain boundaries and the higher-frequency dispersion cor-
responds to the grain bulk interior if two semicircles appear, which normally have capaci-
tance values in a nF and pF range, respectively [59]. The resistance and capacitance values
for each semicircle (in Figure 4.15) have been simulated using Zview software supplied
by Solartron Inc. It is apparent that all the capacitance values are in the range of 0.2 nF.
