Environmental Engineering Reference
In-Depth Information
0
×
.
89
×
d
=
(Eq. 7.8)
B
cos
B
where d is the grain size (Å), is 1.54060 Å, B is the full width at half-maximum
(FWHM) and θ
B
is Bragg angle. The XRD line of palladium showing in Figure 7.8(a)
was used to calculate the palladium grain size. The grain size is about 34 nm. It
should be aware that an error for the grain size by Eq. 7.8 can be up to 50%.
Nevertheless, this estimation suggests that palladium deposited onto the iron surface is
in the form of nanoparticles, which is consistent with the conceptual model proposed by
Zhang et al. (1998).
Figure 7.7
SEM image of bimetallic Pd/Fe nanoparticle aggregates.
Fe
Fe
(a) 5%
(a) 5%
Fe
3
O
4
/
ƻ
-Fe
2
O
3
Fe
3
O
4
/
ƻ
-Fe
2
O
3
Fe
3
O
4
/
ƻ
-Fe
2
O
3
Fe
3
O
4
/
ƻ
-Fe
2
O
3
Pd
Pd
X1
X1
(b) 1%
(b) 1%
X2
X2
20
20
20
20
25
25
25
25
30
30
30
30
35
35
35
35
40
40
40
40
45
45
45
45
50
50
50
50
Diffraction Angle 2
Diffraction Angle 2
θ
θ
Figure 7.8
XRD patterns of bimetallic Pd/Fe nanoparticles (Pd content = 5 and 1%).
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