3.3. Investigation of morphology (SEM)
Thesurface morphologyof theZnO samplessynthesized by
microwave irradiation is analyzed using SEM micrographs and it is
shown in Fig. 3A and B. All the SEM micrographs reveal that the
different pH of the precursor solution affect the particle size, length
and diameter of the nano rods and not their morphology[18].As
shown in Fig. 3.2, at pH 9 and 11, ZnO powder exhibited well
separated rods with few tetrapod and flower-like structurewith each
petal having the single hexagonal rod shape respectively. When the
pH of the solution was maintained at 13, shorter nano rods were
formed in aggregation. As can be seen from the SEM images, it could
be inferred that the solution pH keeping the concentration of the
Zn
þ2
ion and other parameters constant play a vital role in determining the morphology of the ZnO crystals. When the pH of the
solution was 9, the length and diameter of the nano rods are around
4.96mm and 704.8 nm, respectively. The length and diameter of the
A3 rods are approximately twice than that of the A1 rods formed at
pH 13. The aspect ratios are listed in Table 2and they vary in the
order A1oA3oA2. Thus higher alkalinity of the precursor solution
resulted in bigger and longer rods. The variation in the aspect ratio
and crystallinity of the samples with pH is depicted inFig. 4.
3.4. Growth mechanism of rods
Many mechanisms have been proposed for the formation of
nano ZnO rods using microwave assisted methods without the
assistance of any surfactants, capping agents, templates, catalysts
and substrates using different sources of zinc[19–23]. Generally,
the growth process can be viewed as a two-step process, viz.,
nucleation and growth. The ZnO rods are fabricated by the
reaction between Zn (NO3)2and KOH as per the following scheme:
3.3. Investigation of morphology (SEM)
Thesurface morphologyof theZnO samplessynthesized by
microwave irradiation is analyzed using SEM micrographs and it is
shown in Fig. 3A and B. All the SEM micrographs reveal that the
different pH of the precursor solution affect the particle size, length
and diameter of the nano rods and not their morphology[18].As
shown in Fig. 3.2, at pH 9 and 11, ZnO powder exhibited well
separated rods with few tetrapod and flower-like structurewith each
petal having the single hexagonal rod shape respectively. When the
pH of the solution was maintained at 13, shorter nano rods were
formed in aggregation. As can be seen from the SEM images, it could
be inferred that the solution pH keeping the concentration of the
Zn
þ2
ion and other parameters constant play a vital role in determining the morphology of the ZnO crystals. When the pH of the
solution was 9, the length and diameter of the nano rods are around
4.96mm and 704.8 nm, respectively. The length and diameter of the
A3 rods are approximately twice than that of the A1 rods formed at
pH 13. The aspect ratios are listed in Table 2and they vary in the
order A1oA3oA2. Thus higher alkalinity of the precursor solution
resulted in bigger and longer rods. The variation in the aspect ratio
and crystallinity of the samples with pH is depicted inFig. 4.
3.4. Growth mechanism of rods
Many mechanisms have been proposed for the formation of
nano ZnO rods using microwave assisted methods without the
assistance of any surfactants, capping agents, templates, catalysts
and substrates using different sources of zinc[19–23]. Generally,
the growth process can be viewed as a two-step process, viz.,
nucleation and growth. The ZnO rods are fabricated by the
reaction between Zn (NO3)2and KOH as per the following scheme:
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