Geoscience Reference
In-Depth Information
Figure 10.46. GdVO
4
:Eu
3
1
nanoparticles: (a) without modifier and (b) with modifier.
Source: Photographs courtesy of T. Adschiri.
Figure 10.47 SEM photographs of (a) LaPO
4
and (b) LaPO
4
:Nd
3
1
.
Source: Photographs courtesy of K. Byrappa.
10.6.12 Rare Earth Phosphates
The synthesis of rare earth phosphates is very old and the most commonly used
techniques were solid-state chemical reactions, aqueous solution methods, flux, and
vapor deposition. However, all the works deal with the growth of bulk or fine crys-
tals and not the nanocrystals. It was only in recent years the synthesis of nanoparti-
cles of these rare earth phosphates began with their new potential applications in
bioimaging
[207]
.
Figure 10.47
shows the nanoparticles of LaPO
4
doped with Nd.
The experiments are usually carried out in the temperature range above 240
C
using batch reactors. Both acidic and basic solvents are employed in their synthesis.
But the use of nonaqueous solvents for their synthesis is better because of the pres-
ence of structural water in the case of products prepared using aqueous solvents
owing to the affinity of [PO
4
]
3
2
radicals to the OH
2
molecules. Also the use
of
surface modifiers would greatly assist
in synthesizing unagglomerated
