Biomedical Engineering Reference
In-Depth Information
(A)
(B)
20 kV
X1, 000
10
µ
m
JEOL
20 kV
X3, 500
5
µ
m
JEOL
(C)
20 kV
X3, 500
5
µ
m
JEOL
FIGURE 15.8
The effect of bur position in the filament coil on the diamond crystallite size (position within the filament) is
indicated on the micrograph.
were measured to investigate further the differences between the different regions on the bur. A shift
in the diamond peak centered normally at 1,332 cm
1
indicates stress in the films.
From the Raman spectra of the as-grown diamond film coating at positions A, B, and C (
Figure
15.9
), it is evident from the spectra that all the films display a rather broad band centered at
1,500 cm
1
. This broad band indicates the presence of an amorphous carbon phase in the coating.
The intensity of the Raman diamond peak relative to the broad band is almost identical in all three
positions, which indicates that the quality of the diamond is similar at the three positions on the bur.
However, the peak energies are slightly different from one another. The peaks at positions A, B, and C
on the bur are at 1,338, 1,336, and 1,335 cm
1
, respectively.
The variation in the peak position can be used to calculate stress in the films. Agar and Dory
[65]
investigated residual biaxial stress in diamond films grown on a titanium alloy by Raman spectros-
copy and developed a general model, which describes quantitatively the relations between singlet and
doublet phonon scattering and the biaxial stress σ as follows:
σ
= −
0 567
.
(
v
−
v
)(
GPa
)
m
0
