CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

that the broad peak can be resolved into three peaks, with an intense peak centered at 278 nm
and two less intense peaks around 300 and 257 nm.
Intensity (arb. units)
(a)
(b)
(c)
200 250 300
wavelength (nm)
Fig.75. Excitation spectrum corresponding to the 5 D 4 → 7 F 5 transition of Tb 3+ ions (544 nm)
from nanoribbons/ nanoparticles of (a) SbPO 4 :Tb 3+ (5%), (b) SbPO 4 : Ce 3+ (2.5%),
3+ 3+ 3+
Tb (5%) and (c) SbPO 4 : Ce (2.5%), Tb (5%) dispersed in silica.
Based on the comparison of the spectra shown in Fig.75, it is inferred that the peak
around 257 nm is due to the 4f→5d transition of Tb 3+ and the remaining two peaks are due to
the 4f →5d transition of Ce 3+ . This is further confirmed from the excitation spectrum of
3+
SbPO4 :Ce (5%) which gave an excitation peak centered around 278 nm with an asymmetry
around 300 nm (not shown). Slight red shift (~ 7 nm) in the excitation peak maximum of
4f→5d transition of Tb 3+ can be attributed to the changes in the SbPO 4 lattice brought about
3+ 3+
by both Tb and Ce ions doping. Observation of 4f→ 5d excitation peaks for both Tb 3+ and
3+ 3+
Ce , ions in the excitation spectrum obtained by monitoring Tb emission around 544 nm
3+ 3+ 3+
confirms the existence of energy transfer from Ce to Tb ions in Ce co-doped
3+ 3+
SbPO 4 :Tb nanoribbons/ nanoparticles. The relative intensity of 4f→5d transition of Tb to
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