Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1553090 | Superlattices and Microstructures | 2015 | 12 Pages |
Abstract
The present paper reports the synthesis, characterization and photoluminescence studies of undoped ZnS nanoparticles. The ZnS nanoparticles were prepared by chemical precipitation method and characterized by X-ray diffraction (XRD), field emission gun scanning electron microscope (FEGSEM), and high resolution transmission electron microscope (HRTEM). When the concentrations of capping agent (mercaptoethanol) used are 0Â M, 0.01Â M, 0.025Â M, 0.040Â M, and 0.060Â M, the sizes of the nanoparticles are 2.86Â nm, 2.69Â nm, 2.40Â nm, 1.90Â nm and 1.80Â nm, respectively. This means the size of nanoparticles decreases with increasing concentration of capping agent used. The PL spectra of ZnS nanoparticles were measured for different concentrations of merceptoethanol, in which the excitation wavelength was 289Â nm for all the samples. One peak is obtained in the photoluminescence (PL) of ZnS, in which the peak shifts from 468Â nm to 408Â nm with decreasing size of the nanocrystals. The blue emission around the peak of PL intensity is very broad and originates from the radiative recombination involving defect states in the ZnS nanocrystals. The photoluminescence spectra of ZnS nanoparticles for different capping agent concentrations reveals that the emission becomes more intensive and shift towards blue side as the size of the nanoparticles is reduced. The optical absorption spectra of the nanoparticles obtained using UV-Vis spectrophotometer shows the blue-shift with decreasing particle size. The value of band gap energy has been found to be in range 4.60-5.18Â eV, which is related to the quantization effect due to small the of the particles. The measurement of exciton luminescence can be used to determine the band gap of pure ZnS crystals.
Related Topics
Physical Sciences and Engineering
Materials Science
Electronic, Optical and Magnetic Materials
Authors
Raju Kumar Chandrakar, R.N. Baghel, V.K. Chandra, B.P. Chandra,