CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

compared to the bulk material and are arising due to the defect levels present in the band gap
of Sb 2 O 3 . These can be the oxygen vacancies, the surface dangling bonds or the surface
defects. Similar defect emission with comparable line shape has also been observed in
semiconductors like TiO 2 , ZnO, etc. [205, 206]. Lifetime corresponding to the excited state of
these emission centers could not be accurately measured as the decay is faster than the
experimental time resolution of the luminescence set up (~1 ns). Thus, it can be concluded
that the excited state lifetime is of the order of sub-nanoseconds, similar to what has been
observed in the case of ZnO nanorods [206]. At this stage, it is difficult to understand the
exact origin of defects levels. It is worth while to mention here that Deng, et al. [64] have
observed blue emission around 433 nm from Sb 2 O 3 nanobelts, and they have attributed this to
the oxygen related defect emission from the nanorods. In the case of ZnO nanorods [206], it
has been demonstrated that the orange, red and green defect related emission originate from
them depending on the preparation method, annealing temperature and atmospheres.
Normalised intensity
1.0
0.5
0.0
1.0
0.5
0.0
1.0
0.5
0.0
*
nano-rods
*
400 500 600
400 500 600
As prepared
100 °C heated
200 °C heated
400 °C heated
*
*
*
*
Bulk
400 500 600
Wavelength (nm)
77 K
100 K
150 K
200 K
250 K
300K
(a)
77K
100K
150K
200K
250K
300K
(b)
(c)
Fig.44. Emission spectra of (a) Sb 2 O 3 nanorods and (b) bulk Sb 2 O 3 as a function of
temperature. Room temperature emission spectra of as prepared Sb 2 O 3 nanorods
annealed at different temperatures are shown in (c). Excitation wavelength was 220
nm. Peaks marked * are artifacts.
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