Estimation of lattice strain in ZnO nanoparticles: X-ray peak profile analysis

P Bindu,Sabu Thomas

doi:10.1007/s40094-014-0141-9

P Bindu, Sabu Thomas

Open Access

https://doi.org/10.1007/s40094-014-0141-9

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Abstract

ZnO nanoparticles were synthesized from chitosan and zinc chloride by a precipitation method. The synthesized ZnO nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction peak profile analysis, Scanning electron microscopy, Transmission electron microscopy and Photoluminescence. The X-ray diffraction results revealed that the sample was crystalline with a hexagonal wurtzite phase. We have investigated the crystallite development in ZnO nanoparticles by X-ray peak profile analysis. The Williamson–Hall analysis and size–strain plot were used to study the individual contributions of crystallite sizes and lattice strain ϵ on the peak broadening of ZnO nanoparticles. The parameters including strain, stress and energy density value were calculated for all the reflection peaks of X-ray diffraction corresponding to wurtzite hexagonal phase of ZnO lying in the range 20°–80° using the modified form of Williamson–Hall plots and size–strain plot. The results showed that the crystallite size estimated from Scherrer’s formula, Williamson–Hall plots and size–strain plot, and the particle size estimated from Transmission electron microscopy analysis are very much inter-correlated. Both methods, the X-ray diffraction and Transmission electron microscopy, provide less deviation between crystallite size and particle size in the present case.

Highlights

The wide band gap semiconductors, viz. GaN, Zinc oxide (ZnO), InN, AlN, have gained more attention among semiconductor materials, because of their potential application in optoelectronic devices in both the visible and UV regions, such as light emitting diodes (LEDs) and laser diodes
The crystallite size D obtained from the size–strain plot’ (SSP) method is in good agreement with the values obtained from W–H models and transmission electron microscopy (TEM) (Table 2)
The average values of crystallite size obtained from uniform deformation model (UDM), UDSM, and uniform deformation energy density model (UDEDM) are almost similar, which indicate that the inclusion of strain in various forms of W–H methods has a very small effect on the average crystallite size of ZnO nanoparticles

Summary

Introduction

The wide band gap semiconductors, viz. GaN, ZnO, InN, AlN, have gained more attention among semiconductor materials, because of their potential application in optoelectronic devices in both the visible and UV regions, such as light emitting diodes (LEDs) and laser diodes. There are other methods reported in the literature to estimate the crystallite size and lattice strain, which are the pseudo-Voigt function, Rietveld refinement, and Warren-Averbach analysis [12,13,14]. The Williamson–Hall (W–H) analysis is a simplified integral breadth method employed for estimating crystallite size and lattice strain, considering the peak width as a function of 2h [15]. The present work describes a facile route for the synthesis of ZnO nanoparticles from chitosan and ZnCl2 by a precipitation method. The XPPA was carried out for estimating the crystallite size, lattice strain, lattice stress and lattice strain energy density of ZnO nanoparticles based on modified W–H plots using uniform deformation model (UDM), uniform stress deformation model (USDM), uniform deformation energy density model (UDEDM) and another method viz. The luminescence is dispersed with a monochromator and recorded using a CCD detector

Results and discussion

Characterization methods

Conclusions