Geoscience Reference
In-Depth Information
CdTe, CdS, etc., the so called QDs
[220,221]
. Recently, nontoxic QDs for biomedi-
cal applications have been prepared by liquid phase synthesis
[222,223]
. We have
also prepared nontoxic metal oxide nanoparticles with a photoluminescence prop-
erty using SCF technology. GdVO
4
:Eu nanoparticles synthesized showed sphere-
like morphology with particle size
10 nm (
Figure 10.48
). These GdVO
4
:Eu nano-
particles showed strong red light emission and their photoluminescence property is
very stable in comparison with QD (
Figure 10.49
).
On the other hand, some groups have reported that metal oxides show unique
photoluminescence properties. The perovskite, BaSnO
3
, exhibits strong near-
infrared luminescence
[224]
.Eu
2
1
-activated strontium aluminate phosphor pos-
sesses an afterglow property
[225]
. YVO
4
crystals doped with ytterbium and hol-
mium show upconversion photoluminescence, i.e., conversion of infrared radiation
into visible emission
[226]
. Hence, these nanoparticles, prepared by supercritical
B
Figure 10.48. Luminescence and
stability of synthesized GdVO
4
:Eu
nanoparticles.
100
GdVO
4
:Eu
80
60
40
QD(CdSe)
20
0
0
20
40
60
80
Time (h)
Figure 10.49 Comparison of photoluminescence property of GdVO
4
:Eu nanoparticles with
QD (CdSe).
