CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

3+ 3+
faster decay component is assigned to the surface Eu ions and slower component to Eu
ions present in the bulk of the nanomaterials. Values of 5 D 0 lifetimes increase with increase in
Eu 3+ concentration up to 2.5 atom% and above this concentration the lifetime values started
decreasing (Table 9 and Fig.85 (b)). Thus, the lifetime values support the inferences drawn
from emission spectra.
Table 9. Lifetime values corresponding to 5 D 0 level of Eu 3+ in BiPO4 nanorods doped with
different amounts of Eu 3+ ions.
% of Eu 3+ 5 D 0 lifetime values of Eu 3+
τ 1 (ms) τ 2 (ms)
1 atom % 0.18 (35 %) 1.63 (65 %)
2.5 atom % 0.31 (13%) 2.0 (87%)
5 atom % 0.34 (30 %) 1.72 (70%)
4.4.5 Luminescence studies on Tb 3+ doped BiPO 4 nanorods: Figure 86 (a) shows the
emission spectra of 1, 2.5, and 5 atom% Tb 3+
doped BiPO 4 nanorods. Emission peaks
centered at ~ 487, 543, 585 and 621 nm correspond to transitions from 5 D 4 level to 7 F 6, 7 F5,
7 F 4 and 7 3+
F 3 levels respectively of Tb ions present in the BiPO lattice. 4
Intensity (arb.units)
700
600
500
400
300
200
100
λ exc
= 255 nm
1 % Tb
2.5 % Tb
5 % Tb
0
450 500 550 600 65
Wavelength (nm)
Normalised intensity
1
0.1
1 % Tb
2.5 % Tb
5 % Tb
0 2 4 6 8 10
Time (ms)
(a)
(b)
Fig.86. (a) Emission spectra obtained after excitation at 255 nm, (b) decay curves
corresponding to 5 D 4 level of Tb 3+ ion from BiPO : Tb 3+ nanorods prepared at 185°C.
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