Structural properties and x-ray photoelectron spectroscopic study of SnO2 nanoparticles

doi:10.1016/j.matlet.2012.06.073

Materials Letters

Volume 85, 15 October 2012, Pages 168-170

https://doi.org/10.1016/j.matlet.2012.06.073 Get rights and content

Abstract

SnO₂ nanoparticles have been prepared by the sol–gel method using SnCl₄ as a precursor and subsequent heat-treatment at 600 °C. The structural and chemical properties were investigated using x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy. We find SnO₂ nanoparticles of tetragonal structure and sizes varying from 10 to 50 nm. The composition of SnO₂ nanoparticles is studied using x-ray photoelectron spectroscopy. We find a significant deviation from the bulk SnO₂composition pointing towards a different surface stoichiometry or termination.

Highlights

► We find a significant deviation from the bulk SnO₂ composition pointing towards a different surface stoichiometry or termination by XPS method. The discrepancy between x-ray diffraction data and xps, can be explained by the fact that the SnO most likely exists at the surface of the particles and does not form a well ordered crystalline phase which would contribute to the diffraction data but likely represents a surface species with no long-range order.

Introduction

Nanostructured materials have attracted significant interest from many researchers due to their important applications in different fields such as photovoltaics, photocatalysis, energy storage, sensing, medicine and biophysics, catalysis, etc. Nanostructured tin dioxide is a promising material for a wide range of applications. It plays an important role as transparent conductive oxide (TCO) material with remarkable photoelectrical properties that can be used in solar battery, intelligent windows, transparent electrodes; and electrochemical supercapacitors [1], [2], [3], [4]. There is considerable interest in the study of SnO₂ nanoparticles for gas sensing applications [5], [6], [7] not only because of their relatively low operating temperature, but also due to their ability to detect both reducing and oxidizing gases. In all these applications, nanocrystalline tin oxide with a large specific surface area and small particle size is required. Various methods have been adopted for the preparation of nanometer-size materials including the sol–gel methods [8], chemical vapor deposition [9] and hydrothermal treatment [10].

In this paper we report the results of our studies on the morphological; and structural properties, and the chemical composition of tin oxide nanoparticles prepared by sol–gel. The SnO₂ nanoparticles were studied by x-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). While XRD and SEM mainly give us structural information, XPS gives us detailed information about composition and chemical bonding and was also used for the study of SnO₂ nano-particles before [7].

Section snippets

Experimental details

SnO₂ nano-particles were synthesized by a simple sol–gel method (for details on the process see [11]). All reagents were of analytical grade without further purification. The phase composition was characterized by XRD with a Philip's Expert x-ray diffractometer at room temperature using monochromatic Cu-Kα (λ=1.5418 Å). Measurements were taken under beam-acceleration conditions of 40 kV/35 mA. For the XPS measurements a small amount of powder was pressed into in foil forming a closed layer. The

X-ray diffraction

Fig. 1 shows the x-ray diffractogram of the SnO₂ nanoparticles. We find a preferable growth along the (110), (101), (200), and (211) directions. Table 1 gives the peak parameters of the diffractogram in Fig. 1.

The average crystallite size can now be estimated from the given line widths using Scherrer's equation: $t = 0.9 λ / B \cos θ$ where; λ the wavelength of x-rays, θ the diffraction angle of the respective peak and B is the full width of half maximum of the peak in radians. The resulting widths are

Conclusions

Tetragonal tin dioxide nanoparticles were obtained by using the sol–gel technique with thermal treatments. Our morphological data shows randomly arranged particles which form conglomerates. Mean particle sizes between 17 and 18 nm could be derived by XRD and SEM. Our XPS data shows that only trace amounts of the precursor materials remain unreacted and the particles exhibit a Sn:O ratio of ∼1.5 close to the bulk composition of SnO₂.

Acknowledgments

We acknowledge funding by the Ministry of science of Iran.

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Structural properties and x-ray photoelectron spectroscopic study of SnO2 nanoparticles

Abstract

Highlights

Introduction

Section snippets

Experimental details

X-ray diffraction

Conclusions

Acknowledgments

J Alloys Compd

J Alloys Compd

Appl Surf Sci

J Power Sources

Mater Chem Phys

Sens Actuators B

J Alloys Compd

Structural properties and x-ray photoelectron spectroscopic study of SnO₂ nanoparticles