1. International Conference on Electron Microscopy
& XXXVI Annual Meeting of the Electron Microscope Society of India (EMSI)
July 8-10 ,2015
Synthesis and Characterization of ZnO-SnO2 Nanocomposite
Rewrewa Narzary, Biplob Mondal
Department of Electronics and Communication Engineering Tezpur University, Tezpur, Assam, India
Introduction
Multi-compositional metal oxide synthesized in a simple solution method for gas sensing application.
Metal oxides has emerged as an excellent gas sensing material due to their low cost fabrication technique, high purity, long term stability etc.
Selectivity of sensor can be improved tuning the composition of multi-compositional sensing layer.
Although few reports are available on the multi- compositional sensor films, hydrogen sensing behavior of ZnO-SnO2 composite is not investigated extensively.
Thin films of ZnO-SnO2 nanocomposites were prepared with varied percentage of zinc and tin ions.
Samples with three different composition is studied denoted as Zn60Sn40 (a) Zn50Sn50 (b) & Zn40Sn60 (c), suffix denotes the molar percentage of Zinc & Tin ions
3. Synthesis of ZnO-SnO2 micro/nanocomposites
4. Formation process of ZnO–SnO2 composite
PVA solution
Zn(CH3COO)2·2H2O
SnCl4·5H2O
70-120°C
1000 rpm
NaOH (1 M)
Zn2+
&
Sn4+
Si/SiO2 substrate
Solution drop wise
1200 rpm
Figure 2: Formation Mechanism of ZnO–SnO2 composite
Zn OH-  [Zn(OH)4]2-
Sn OH- + [Zn(OH)4]2-  [ZnSn(OH)6] ( ºC)
[ZnSn(OH)6]  ZnO-SnO2 + 3H2O (above 400ºC)
Sol Preparation
Spin Casting
Annealing (500°C)
Figure 1: Synthesis of ZnO-SnO2
A. Material Characterization
Figure 3: X-Ray Diffraction Pattern of (A) Zn60Sn40 (B) Zn50Sn50 (C) Zn40Sn60
Figure 4 : SEM images of ZnO-SnO2 composite (A) Zn60Sn40 (B) Zn50Sn50 (C) Zn40Sn60
B. Gas Sensing Characteristics
CONCLUSION
The XRD pattern of the samples shows characteristic peaks at distinct angles that matches the hexagonal phase of ZnO (JCPDS # ) and tetragonal phase of rutile SnO2 (JCPDS# )
The SEM micrographs reveal the formation of hexagonal rod like ZnO microstructure dispersed over nanoparticles of SnO2. Sample ‘a’ is dominated by long and thick hexagonal ZnO nanorods compared to sample ‘b’ which is dominated by nanaparticles of SnO2.
sample shows a different and distinct morphology where the entire area is covered with flacks like SnO2 nanostructures.
Gas sensing results of the sensor constructed using composite materials (a &c) were satisfactory as they represent repeatable cyclic behavior.
Figure 5: Transient Response of sensor at 150°C to hydrogen
Acknowledgement: DST-FIST program of the Department of Electronics and Communication Engineering, Tezpur University.
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