Page 122 - Book Hosokawa Nanoparticle Technology Handbook

FUNDAMENTALS CH. 2 STRUCTURAL CONTROL OF NANOPARTICLES

Primary particle After spray dring
<10nm
D p

10nm 100nm

=109.2nm
D p

100nm 100nm

Figure 2.5.5
Morphology change of particles prepared by spray-drying method derived from different primary particles size.

1.50 0.40
1.8 Al 2 O 3 /Large-SiO 2
Effective refractive index, ne ff 1.40 D p =110nm D p =8nm 0.25 Porosity, p [-] Effective refractive index, ne ff 1.6 Silica 100% Zirconia 100%
0.35
1.45
1.7
0.30
ZrO 2 /Large-SiO 2
0.20
1.35
1.5
0.15
1.30
0.10
1.25
1.3
0.00
1.20 0.05 1.4
0 20 40 60 80 100
Silica: 110 nm Content of coating material [wt %] Silica: 8 nm 100% Alumina 100%
100% 1.2
0 20 40 60 80 100
Silica: 100% Content of coating material [wt %] Silica: 0%
Figure 2.5.6
Effective refractive index and porosity of SiO particles
2
prepared with different primary particles size. Figure 2.5.7
Variation of effective index of SiO /ZrO or Al O multi-
2
3
2
2
component particles prepared from the different content.
particles can be easily controlled by changing their
content in the precursor.
On the other hand, porous SiO particles can be also then evaporated at low temperature, leading to the
2
produced by spray-drying, as shown in Fig. 2.5.8 [9]. self-organization of particles in the droplet, and
The process is as follows: first, a mixed solution of finally the PSL particles are removed at a high tem-
SiO nanoparticles and polystyrene latex (PSL) parti- perature. Pore size can be controlled by changing the
2
cles are sprayed to form droplets, and the solvent is PSL size, as shown in Fig. 2.5.9. For successfully
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