Synthesis and Characterization of Tin Oxide Nanoparticles by Solid State Chemical Reaction Method
Post on 22-Mar-2023
0 Views
Preview:
Transcript
ORI GIN AL PA PER
Synthesis and Characterization of Tin OxideNanoparticles by Solid State Chemical ReactionMethod
Parvin Sarabadani • Mahdi Sadeghi •
Mohamadreza Ghasemi • Zargham Asadollahi •
Narges Afshari
Received: 23 January 2011 / Published online: 18 February 2011
� Springer Science+Business Media, LLC 2011
Abstract High purity tin oxide nanopowders have been synthesized by using a
solid-state chemical reaction technique with annealing at elevated temperature. The
effects of two parameters, specifically by controlling the annealing temperature and
kind of alkaline chlorides as precursors, the effect on particle size, morphology and
IR spectra of synthesized tin oxide nanopowder were investigated. From the X-ray
pattern, the crystal structure of the synthesized powders was confirmed as a tetragonal
structure. Based on the recorded FTIR spectrum of SnO2, the IR bands due to SnO2
vibrations and its lattice modes were observed at 625 and 690 cm-1, respectively. In
addition, an important characterization peak has been identified at 1,450 cm-1 due to
Sn–O–Sn bridges observed only when LiCl was used as precursor. The formation of
Sn–O–Sn bridges was confirmed by TGA–DTA analysis. According to the SEM
images, it is obvious to notice that the kind of alkaline chlorides as precursors play a
dominant role in controlling the morphology of tin oxide nanopowders.
Keywords Tin oxide � Nano-particles � Solid state � Synthesis
Introduction
Nano-structured materials have attracted increasing interest because of their novel
characteristic properties and potential technological applications [1]. Among such
materials, tin oxide nanoparticles has recently received a great scientific interest
because of their wide range of applications as gas-sensing materials, antistatic films,
thin film resisters and anti reflecting coatings in solar cells [2]. These nanoparticles
are synthesized by several methods such as sol–gel [3], spray pyrolysis [4],
P. Sarabadani � M. Sadeghi (&) � M. Ghasemi � Z. Asadollahi � N. Afshari
Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research
Institute, Karaj, Iran
e-mail: msadeghi@nrcam.org
123
J Clust Sci (2011) 22:131–140
DOI 10.1007/s10876-011-0350-1
sputtering [5] and template method [6]. However, the disadvantages of the reported
methods include the need to use expensive organic precursors as starting materials,
or particle aggregations during high temperature oxidation in the air.
Generally, these methods are complicated and expensive, but mechanochemical
processing is a novel candidate to synthesize nano-structured materials [7]. During the
solid state chemical reaction method which a chemical reaction takes place when solid
precursors are ground together [8]. There are three main advantages in the solid-state
reaction approach. They are (a) simple, cheaper and convenient, (b) involve less
solvent and reduce contamination and (c) give high yields of products.
In this paper, we report the preparation of tin oxide nanoparticles by solid-state
chemical reactions at ambient temperature utilizing different alkaline chlorides as
precursors. Our studies show that this is not only a simple processes but also gives
uniform products similar to other profitable methods. We have also investigated the
effect of varying the annealing temperature and type of alkaline chloride precursors.
Experimental
Materials and Equipments
Tin tetrachloride pentahydrate (SnCl4�5H2O) and other regents were all of analytical
grade and used without purification.
The crystal structures were identified by a powder X-ray diffractometer (XRD,
Philips PW-1840) employing Cu Ka radiation (k = 1.5418 A). The XRD Patterns of
nanoparticles were verified by comparing with the JCPDS (Joint Committee on
Powder Diffraction Standards) data.
The morphology and chemical composition of the synthesized tin oxide
nanoparticles were imaged by scanning electron microscopy (SEM, Philips XL-30).
The combined thermogravimetry and differential thermal analysis (TG–DTA,
Rheometeric STA-1500) was performed at a scan rate of 5 �C min-1 from room
temperature to 1,000 �C.
FTIR spectra were taken with an IR spectrometer in the 4,000–400 cm-1 range.
Preparation of Tin Oxide Nanoparticles
A mixed solid powder of SnCl4�5H2O (0.01 mol, 3.51 g) and KCl was ground for
30 min with a weight ratio of 1:1. Powdered KOH (0.038 mol, 2.13 g) was added to
the system and ground for 30 min at room temperature. The reaction began during
the mixing process, accompanied by the emission of water vapor from the system
due to the reaction being exothermic.
The product was washed with distilled water, treated in an ultrasonic bath for
15 min, and then centrifuged for 15 min (6,000 rpm). This process was repeated
until no Cl- ion could be detected. The detection has done with AgNO3 solution
(0.10 mol l-1).The solution was then dried at 85 �C for 24 h to obtain white SnO2
powder was assigned A sample. Also the produced tin oxide powder was further
sintered in air for 2 h at various temperatures (from 85–1,000 �C).
132 P. Sarabadani et al.
123
The synthesis procedure of tin oxide was repeated by using other precursors such
as NaCl and LiCl which named B and C samples, respectively. Figure 1 shows the
synthesis process flowchart.
Results and Discussion
The tin oxide nanoparticles are produced by the following solid-state reaction:
SnCl4 � 5H2O sð Þ þ 4KOH! SnO2 � H2Oþ 4KCl sð Þ þ 6H2O
Often self-initiated and self-sustained reactions started with H2O vapor releasing
after grinding of the precursors mixture. There are four steps in a typical solid-state
of reaction: diffusion, reaction, nucleation and growth [9].
Fig 1 Flowchart of synthesis process of tin oxide nano-particles
Synthesis and Characterization of Tin Oxide Nanoparticles 133
123
10 20 30 40 50 60 70 80
0
100
200
300
400
500
600
700
800
900
1000
1100
(202)(112)
(310)(002)
2θ°
10 20 30 40 50 60 70 80
2θ°
10 20 30 40 50 60 70 80
2θ°
++
+
+
++
(301)(220)
(211)(200)
(101)(110)
1000°C
900°C800°C
700°C
600°C
500°C
400°C
300°C200°C
85°C
Inte
nsi
ty(a
rbit
rary
un
it)
-100
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
(202)(310)(002)(111)
XX
+1000°C
900°C
800°C
700°C
600°C
500°C
400°C
300°C
200°C85°C
+ +
+
+
(301)(220)+
(211)
(200)
(101)(110)
Inte
nsi
ty(a
rbit
rary
un
it)
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
(202)(112)
(310)(002)(111) ++
+
+
++
1000°C
900°C
800°C
700°C600°C
500°C400°C
300°C
200°C85°C
Inte
nsi
ty(a
rbit
rary
un
it)
(301)(220)
(211)
(200)
(101)(110)
a
b
c
Fig. 2 XRD patterns of synthesized tin oxide by different precursor a KCl, b NaCl, c LiCl
134 P. Sarabadani et al.
123
The hand grinding process can only make the precursor particles mix in the range
of lm. As SnCl4�5H2O is mixed and ground with KOH, they conjunct only at the
border point, where several SnCl4�5H2O atoms or molecules react with KOH first.
Due to the decrease of reaction enthalpy, further reactions are initiated and sustained
[10]. The produced SnO2�H2O and KCl atoms expand to tens or even hundreds.
After that, a barrier core mixed of SnO2�H2O and KCl exits between SnCl4�5H2O
and KOH. To continue the reaction between SnCl4�5H2O and KOH, there are two
ways: transferring along the crust of the products or piercing directly through the
products interior. If the produced SnO2�H2O ? KCl formed a ball between
SnCl4�5H2O and KOH, the comparison of the two ways show that the diffusion
activation energy of piercing is several orders higher than that of interface
transferring and the pathway of the length of transferring is about 1.57 times of that
of piercing, thus transferring is chosen to be the right diffusion path.
As the grinding continues, the further conjunction and reaction are continuing
in the system. More cores are obtained and the sizes of them are determined by
the ratio of nucleation and growth of the products. If growth in a reaction is
quicker than nucleation, the particles will aggregate to bulks; otherwise more
cores are created next to the core, which is still composed of limited number of
particles. The constant formation and precipitation of KCl from KCl shells
surrounding the SnO2�H2O particles, prevents them from aggregating to large
particles [11].
Characterization of Tin Oxide Nanoparticles
The Influence of Heat Treatment and Precursor on Particles Size
From the XRD pattern, the average particle sizes are obtained from the most intense
peaks of (110), (101) and (211) in SnO2 nanoparticles by using the Debye–Scherer
equation. The particles size of synthesized samples were measured from the peak
broadening were in good agreement with the values obtained by SEM. Comparison
of the XRD patterns with the JCPDS data confirms the samples are tin oxide with
tetragonal structure.
The XRD patterns of the obtained samples after heat treatment at various
temperatures are shown in Fig. 2. The observed diffraction peaks at (110), (101),
(200), (211), (220), and (113) agree well with the tetragonal structure of tin oxide
(JCPDS file No. 46-1088).
Only two sharp peaks (X) observed in Fig. 2b at 32 and 45 (2h�) indicate
residual NaCl which was removed after 700 �C due to the melting. The XRD
results reveal that the calcining time obviously influences the crystallization of
the powders. The experiments showed that significant growth of the particles
began at about 400 �C for SnO2. The growth accelerated with increased
temperature.
The average grain size D of tin oxide particles were estimated according to the
Scherrer’s equation [12] where h is the diffraction angle of the peak in the tetragonal
phase, k is the wavelength for the X-ray source (for Cu, k = 1.54 A) and b is the
Synthesis and Characterization of Tin Oxide Nanoparticles 135
123
full width at half maximum of the peak (in radian), which is calibrated by high
purity silicon and shown in Fig. 3.
The obtained XRD patterns of these oxide nanoparticles revealed an increase in
the size of the oxide particles at 85–1,000 �C, indicating some crystallization in the
annealing process. The minimum size of the particles is observed at 600 �C, by
increasing the temperature up to 600 �C, both root and terminal hydroxyl groups
condense as grains aggregates and grow but at 600 �C due to the connected
hydroxyl effects, porosity decreases and thus particles became smaller [13].
Inducing hydroxyl-groups condensation by increasing temperature, results on
particles growth back again. In addition, the results reveal that A sample particles
size is smaller than B and C samples. It could be because of smaller size of Li atoms
which would indicate SnO2 is better surrounded by LiCl.
SEM images in Fig. 4 show fine particles with uniform size, which coincide with
the XRD-determined grain size. The SEM images show that using NaCl and KCl as
precursors led to produce morphologically similar tin oxide nano-powders
(spherical particles) whereas LiCl led to formation of smaller SnO2 particles with
a flower structure.
Figure 5 presents the FTIR spectra of SnO2 powders which are heat treated at
400 �C. In all samples, the broad adsorption peak in the range 2,500–4,000 cm-1
was assigned to asymmetric hydroxyl stretching mode. SnO2 vibrations and lattice
modes were observed at 625 and 690 cm-1, respectively. An important character-
ization peak was observed at 1450 cm-1 in Fig. 5c probably an overtone for the
asymmetric stretching mode of a surface bridging oxide formed by condensation of
adjacent surface hydroxyl groups Sn–O–Sn bridges. Dehydration phenomena from
0 200 400 600 800 1000
05
10152025303540455055606570758085
Par
ticl
es s
ize
(nm
)
Temprature(°C )
A B C
Fig. 3 The effect of annealing temperature on particles size of tin oxide powders prepared by differentprecursors: a LiCl, b NaCl, c KCl
136 P. Sarabadani et al.
123
Fig. 4 Scanning electron micrograph of SnO2 powders by different precursors a LiCl, b NaCl, c KCl at 400 �C
Synthesis and Characterization of Tin Oxide Nanoparticles 137
123
of SnO2 surface occurs via adjacent surface hydroxyl groups condensation on the
[100] and [101] planes. Hydroxyl groups condensation on these planes will leads to
Sn–O–Sn bridges formation at surface [14]. These formed Sn–O–Sn bridges remain
on the surface, reducing the number of gas adsorption active sites, so as a
conclusion, it is not recommended to use of LiCl as precursor for producing SnO2
nano-powder as sensor layers.
Figure 6 shows TG–DTA curves of A, B and C samples in N2. As observed in
Fig. 6a, there is an endothermic peak at 25–100 �C with a 22% weight loss
corresponding to the water physically adsorbed on the tin oxide surface desorption.
A second weight loss step (6%) was observed without any induced thermal event.
As presented in Fig. 6b, there are two endothermic peaks. The first peak observed
around 25–100 �C attributed to desorption of that water physically adsorbed on the
tin oxide surface with a 6% weight loss and a second peak is located between
780–800 �C without any weight loss assigned to residual sodium chloride melting
on tin oxide powder as confirmed by XRD patterns results (Fig. 2b).
As seen in Fig. 6c there is an additional endothermic peak at 50–100 �C with a
8% weight loss attributed to desorption of the water physically adsorbed on the tin
oxide surface. A second weight loss step (8%) was observed without any thermal
event. A third 4% weight loss step is assigned to the surface SnO2 dehydration via
adjacent surface hydroxyl groups condensation [14] and Sn–O–Sn bridges
formation is in good agreement with FTIR spectra (Fig. 4c).
Fig. 5 The FTIR spectra of SnO2 powders by different precursors a KCl, b NaCl, c LiCl (The sampleswere heat treated at 400 �C)
138 P. Sarabadani et al.
123
Fig. 6 Thermal analysis of SnO2 powders prepared by using different precursors a KCl, b NaCl, c LiCl
Synthesis and Characterization of Tin Oxide Nanoparticles 139
123
Conclusion
High purity tin oxide nanopowders were synthesized by solid state chemical
reaction method successfully. According to our study, increasing the temperature to
600 �C, both root and terminal hydroxyl groups condense as grains aggregate and
grow but at 600 �C due to connected hydroxyl effects, porosity decrease and thus tin
oxide particles became smaller. Inducing hydroxyl-groups condensation by
increasing temperature, results on particles growth back again. The SEM images
show that using of NaCl and KCl as precursors led to produce morphologically
similar tin oxide nanopowders (spherical particles) whereas LiCl led to formation of
smaller SnO2 particles with flower structure. In addition, the Sn–O–Sn bridges
formed on the surface only using of LiCl as precursor.
References
1. G. G. Mandayo (2007). Sens. Lett. 5, (2), 341.
2. S. H. Park, Y. C. Son, W. S. Willis, S. L. Suib, and K. E. Creasy (1998). Chem. Mater. 10, 2389.
3. A. A. Ansari, P. R. Solanki, and B. D. Malhotra (2009). Sens. Lett. 7, (1), 64.
4. G. Korotchenkov, V. Brynzari, and S. Dmitriev (1999). Sens. Actuators B 54, 197.
5. S. I. Rembeza, E. S. Rembeza, T. V. Svistova, and O. I. Borsiakova (2000). Phys. Status Solidi 179,
147.
6. H. Liu, J. Park, and G. Wang (2010). Sens. Lett. 8, (2), 243.
7. U. Kersen (2002). Mater. Sci. Forum 633, 386.
8. F. Li, J. Xu, X. Yu, L. Chen, J. Zhu, Z. Yang, and X. Xin (2002). Sens. Actuators B 81, 165.
9. Y. M. Zhou, X. Q. Xin, and Chinese (1999). J. Inorg. Chem. 15, 273.
10. J. B. Wiley and R. B. Kaner (1992). Science 225, 1093.
11. X. R. Ye, D. J. Jia, J. Q. Yu, X. Q. Xin, and Z. Xue (1999). Adv. Mater. 11, 941.
12. Y. Wang, Y. Wang, J. Cao, F. Kong, H. Xia, J. Zhang, B. Zhu, S. Wang, and S. Wu (2008). Sens.Actuators B 131, 183.
13. V. Vorgelegt (2006). Ph.D Thesis, Eberhard Karls University, Tubingen, Germany.
14. U. Kersen and M. R. Sundberg (2003). J. Electrochem. Soc 150, 129.
140 P. Sarabadani et al.
123
top related