Environmental Engineering Reference
In-Depth Information
(a)
(b)
280
260
240
220
200
Fe203.003.tif
10:31 08/29/08
TEM Mode: Imaging
5 nm
HV=200kV
Direct Mag: 300000x
Ti lt: −.2
AMT Camera System
30
40
50
60
70
80
2θ
FIGURE 37.3
XRD pattern (a) and TEM image (b) for synthesized γ-Fe
2
O
3
nanoparticles. Scale bar represents 5 nm, and aggre-
gated cubic structure shape of nanoparticles is imaged.
spinel cubic structure and particle size between the 5 and 20 nm range. The calculated average
particle size of the γ-Fe
2
O
3
nanoparticle (14.3 nm) agreed well with TEM data.
37.3.2.3 Nanogibbsite
Figure 37.4 shows the XRD pattern of the synthesized gibbsite particles after a 60-day
dialysis period. The 2⊖
values of the synthesized gibbsite nanoparticles at 18.24°, 20.24°,
21.46°, 26.91°, 36.50°, 37.58°, 39.42°, 41.5°, 44.3°, 45.4°, 50.72°, 54.22°, and 63.8° are well itted
with literature data [56,63]. Synthesized gibbsite particles obtained after 60 days of dialy-
sis were examined with TEM (Figure 37.4). The nanogibbsite crystals showed a pseudo-
hexagonal morphology with an average crystallite size of 90 ± 25 nm. Gibbsite crystals
exhibit plate-like crystal structures [64]. According to the TEM images, the thicknesses of
(a)
(b)
600
400
200
0
15
30
45
60
75
100 nm
2θ
FIGURE 37.4
XRD pattern (a) and TEM image (b) for synthesized gibbsite nanoparticles. Scale bar represents 100 nm, and
aggregated hexagonal structure shape of nanoparticles is imaged.