CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

On annealing the nanorods at 100 and 200°C, emission intensity of the 545 and 592
nm peaks relative to the band edge emission has been found to decrease as can be seen from
Fig.44 (c). Based on the luminescence and XRD studies of the as prepared nanorods and the
nanorods annealed at different temperatures it is inferred that the morphological changes are
taking place in Sb 2 O 3 nanorods during annealing and they are responsible for the change in
intensity of 545 and 592 nm peaks. To further confirm the morphological assisted changes
and the associated structural changes in Sb 2 O 3 nanorods on annealing, Raman spectroscopic
studies of both (as prepared and annealed) samples were carried out and the results are
described below. Figure 45 (a) shows Raman spectrum of the as prepared nanorods. The
sample shows peaks at 143, 191, 218, 256, 297, 445, 503, 596 and 681 cm -1 , characteristic of
the orthorhombic valentinite form of Sb 2 O 3 , which agrees well with the reported by data [64,
207–209]. Similar spectra are also observed from bulk and nanorods annealed at different
temperatures. The Raman spectra of the annealed samples show a strong luminescence
background, intensity of which systematically increases as the annealing temperature is
increased. Thus, the broad emission background dominates the sample annealed at 400°C.
The major differences between the patterns corresponding to as prepared nanorods, the one
annealed at different temperatures and the bulk, are depicted by the Raman peaks at ~260 cm -
1 (Fig.45 (b)), 445 cm -1 (Fig.45 (c)) and ~ 710 cm -1 (Fig.45 (d)). The peak at ~ 260 cm -1 (peak
A) in bulk Sb 2 O 3 is clearly seen to have evolved into two peaks for nanorods; one at 256 cm -1
(peak A1) and another at 259 cm -1 (peak A2). The peak A1 is relatively sharper (line width
approximately ~1/3 rd ) than peak A2. As the nanorods are annealed, the intensity of this peak
reduces and that of A2 increases; while their widths remain almost constant. Similar
inferences are drawn for the peak at ~ 445 cm -1 (peak B in Fig.45 (c)). In case of nanorod
sample this shows a triplet, with peaks at ~ 435 cm -1 (peak B1), 443 cm -1 (peak B2) and 451
cm -1 peak (B3). The B2 peak is most intense, followed by B3 and B1. The widths of peak B2
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