Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Synthesis of SnO 2 Nanoparticles via Sol-Gel Method
Hilal Kose 1 *, Emrah Bulut 1 1
1 Department of Chemistry, Arts and Sciences Faculty, Sakarya University, 54187, Sakarya, Turkey
Abstract- SnO 2 nanop articles fabricated at different pH values by sol-gel method. Sols were prepared from aqueous solution of tin(II)
chloride at room temperature. SEM and XRD analysis were performed to characterize nanoparticles. The results indicate the
nanocrystalline nature of the SnO 2 particles.
Tin oxide (SnO2), cassiterite structure, is a typical wide
band gap n-type semiconductor (3.8 eV) [1] and, one of the
most widely used semiconductor oxides due to its chemical
and mechanical stabilit ies. The electrical and chemical
properties of SnO 2 have been extensively studied because of
its application as transparent electrodes for solar cells, liquid
crystal displays; antistatic coatings and gas sensors; anodes
for lithium ion batteries, transistors, catalyst supports; nano
and ultra filtration membranes and anticorrosion coatings [2].
Recently tin oxide-based materials have received
considerable attention as promising anode materials for Liion
batteries due to their high capacity [3]. SnO 2
nanoparticles can be obtained by different techniques.
Among the processing techniques, sol-gel offers advantages
such as low cost, low temperatures processing and also
precise control of stoichiometry [4].
In this work, sol-gel method was applied to synthesize
SnO 2 nanoparticles at different pH values. The SnO 2
precursor solution was prepared from tin chloride by
dissolving SnCl 2·2H 2 O in 50 ml of deionized water. The
solution was in the form of turbid nature during the first
period of the dissolving and then the color was returned to a
transparent nature when acetic acid was added. The addition
of acetic acid was also aimed to prevent rapid hydrolysis for
obtaining nucleation of nano sized species in the solution.
After stirring a few hours, the solution pH was adjusted to 7,
8, 9, and 10 by using ammonia solution (%25). Then the
solution stirred for 24 h. The resultant sols washed and
centrifuged 5 times with deionized water. Finally, sols dried
at 150 o C for 2 hours and precalcination was performed at
300 o C. Subsequently, the calcination temperature was
increased to 400 o C and the sols were calcinated for two
hours at treatment.
of spherical nanoparticles in diameter under 100 nm were
obtained.
Figure 2. XRD diffraction of SnO 2 nanop articles.
Figure 2 shows the XRD patterns of the powders obtained
at the peak positions in each sample agree well with the
reflections of SnO 2 (cassiterite). The XRD diffraction peaks
are evidenced that a crystalline type of SnO 2 was obtained.
As can be seen from the Figure 2, the width of the reflections
is considerably broadened, because of nanocrystalline do main
size.
In summary, SnO 2 nanoparticles were obtained from solgel
method. Strong acidic conditions enhanced the hydrogen
bonding among the protonated nanocrystallites, leading to a
high degree of agglomeration, while in higher pH value
solutions; the coordinated water molecules should suppress
the agglomeration among the freshly formed nanocrystallites
[2]. Because of this reason, synthesis of SnO 2 nanoparticles
was performed at higher pH values such as 7, 8, 9 and 10.
The size o f nanocrystallines decreased with reducing pH
value to 7. The broad XRD peaks and SEM image indicate
the nanocrystalline nature of the SnO2 particles. The small
grain size obtained in the present work is believed proper
optimization of the precursor colloidal solution used and
process parameters such as low heat treatment temperature.
*Corresponding author: 0Thkose@sakarya.edu.tr
Figure 1. SEM image of SnO 2 nanop articles prepared by sol-gel
technique at pH 7.
Scanning electron microscopy (SEM) analysis was used
to investigate the morphology of the as-synthesized SnO2
samples. As shown in Figure 1, SnO 2 nanoparticles consist
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6th Nanoscience and Nanotechnology Conference, zmir, 2010 305