CHEM01200604004 Shri Sanyasinaidu Boddu - Homi Bhabha ...

intensity of XRD peaks correspond to (110) and (200) planes around 2θ values 19.66 and
36.62°, respectively. These results indicate a preferred crystallographic orientation existing in
the sample prepared by iso-propanol route which leads to selective enhancement in the
intensity of some of the Bragg reflections. A similar increase in intensity for (110) and (200)
planes has also been observed by Deng, et al. for Sb 2 O 3 nanorods prepared by oxidation of
antimony metal [64]. On annealing it is observed that the intensity of the super-lattice peaks
at 2θ values corresponding to (110) and (200) reflections systematically decreases. This
indicates that the preferred crystallographic orientation associated with the sample is slowly
destroyed (Fig.42 (b and c)). In addition to the orientation changes, annealing at 400°C also
leads to partial conversion of Sb 2 O 3 to Sb 2 O 4 cervantite phase (Fig.42 (d)). In order to check
the morphology and preferred crystallographic orientation existing with the sample, atomic
force and transmission electron microscopic (AFM and TEM) measurements were carried
out.
Figure 43 (a and b) shows the AFM images of methanol dispersion of as prepared
Sb 2 O 3 samples obtained by iso-propanol route. The images consist of long rod shaped species
with a length around 3– 4 μm and width around 100–200 nm. Several such rods can be
clearly seen from the images. A closer look at the image demonstrate that in addition to the
long rods there also exist small rods having length roughly in the range of around 1 μm. A
representative TEM image along with the selected area electron diffraction patterns of the
sample is shown in Fig.43 (c and d). Dimension of the nanorods obtained from TEM images
agree well with that obtained from AFM images. As the SAED pattern taken along the [100]
zone axis consists only spots, it is confirmed that each nanorod is a single crystal of Sb 2 O 3
with [100] orientation. For the purpose of comparison bulk material was also dispersed in
methanol and TEM images were recorded for the supernatant solution (Fig.43 (e and f)).
These particles are aggregated and are having size in the broad range of 50–500 nm.
87