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Sharma R.,Government Arts and Commerce Girls College | BiSen D.P.,Pandit Ravishankar Shukla University | Chandra B.P.,Rani Durgavati University
Journal of Electronic Materials | Year: 2015

We report the synthesis and mechanoluminescence (ML) of manganese-doped zinc sulfide (ZnS) nanoparticles. Clusters of ZnS:Mn nanocrystals were prepared by chemical precipitation, by mixing of solutions of zinc chloride, sodium sulfide, and manganese chloride. Mercaptoethanol (ME) was used as capping agent, to modify the surface of the nanoparticles and prevent their growth. The particle size of the nanocrystals, measured by use of x-ray diffraction and transmission electron microscopy, was in the range 2–5 nm. The ZnS:Mn nanoparticles were deformed impulsively by dropping a load from a fixed height. The ML intensity of ZnS:Mn nanocrystals increased with increasing mechanical stress i.e. with increasing impact velocity. The impact velocity-dependence of maximum ML intensity, Im, and total ML intensity, IT, are discussed. The effect of crystal size on the ML intensity–time curve is also discussed. ML intensity initially increases with increasing concentration of Mn in the samples, reaches an optimum value at a specific concentration of Mn, then decreases with further increasing concentration of Mn in the nanocrystals. The theory of the ML of nanoparticles is also discussed. © 2015, The Minerals, Metals & Materials Society. Source


Bisen D.P.,Pandit Ravishankar Shukla University | Sharma R.,Government Arts and Commerce Girls College
Luminescence | Year: 2016

In this paper, europium-doped strontium aluminate (SrAl2O4:Eu2+) phosphors were synthesized using a combustion method with urea as a fuel at 600°C. The phase structure, particle size, surface morphology and elemental analysis were studied using X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FTIR) spectra. The EDX and FTIR spectra confirm the elements present in the SrAl2O4:Eu2+ phosphor. The optical properties of SrAl2O4:Eu2+ phosphors were investigated by photoluminescence (PL) and mechanoluminescence (ML). The excitation and emission spectra showed a broad band with peaks at 337 and 515 nm, respectively. The ML intensities of SrAl2O4:Eu2+ phosphor increased proportionally with the increase in the height of the mechanical load, which suggests that this phosphor could be used in stress sensors. The CIE colour chromaticity diagram and ML spectra confirm that the SrAl2O4:Eu2+ phosphor emitted green coloured light. Copyright © 2015 John Wiley & Sons, Ltd. Source


Sharma R.,Government Arts and Commerce Girls College | Bisen D.P.,Pandit Ravishankar Shukla University | Chandra B.P.,Rani Durgavati University
Journal of Luminescence | Year: 2015

Nanosized strontium aluminate phosphors activated with Dy3+ were prepared by a combustion method. Nanophosphor was prepared by this method at reaction temperatures as low as 600 °C. Powder X-ray diffraction (XRD), scanning electron microscope analysis was used to characterize the prepared product. The monoclinic phase was observed in the XRD pattern. The particle size of the samples was calculated around 35 nm. The SEM images show irregular shape of the prepared nanophosphor. Two peaks were found in the mechanoluminescence (ML) response curve plotted between time and ML intensity. The H3BO3 added strontium aluminate phosphors activated with Dy show more bright ML peak as compared to the powders of SrAl2O4:Dy3+ without H3BO3. It was found that the PL and ML intensity increases with increasing concentration of Dy, it becomes maximum for 3% of Dy. The photoluminescence emission shows two intense fluorescence transitions peaks at 498 nm and 583 nm, 4F9/2→6H15/2 in the blue and 4F9/2→6H13/2 in the yellow-orange wavelength region. © 2015 Elsevier B.V. All rights reserved. Source


Pandey D.,Bhilai Institute of Technology | Brahme N.,Pandit Ravishankar Shukla University | Sharma R.,Government Arts and Commerce Girls College | Pandey A.,Shri Rawatpura Institute of Techmology
International Journal of Applied Engineering Research | Year: 2016

Long afterglow phosphors (Ca2-xMgSi2O7:Dy3+) were prepared by solid state reaction under a weak reductive atmosphere. X ray diffraction patterns, Scanning electron microscopy, EDX, Photo-luminescence spectra, absorption spectra were investigated. The phosphor showed the combination of the 482nm blue emission corresponding to the 4f9/2 →6H15/2 transitions and 575nm yellow emission corresponding to the 4f9/2 →6H13/2 transition yielded white light emission. © 2016, Research India Publications. Source


Sharma R.,Government Arts and Commerce Girls College | Bisen D.P.,Pandit Ravishankar Shukla University
Luminescence | Year: 2014

The thermoluminescence (TL) of nanoparticles has become a matter of keen interest in recent times but is rarely reported. This article reports the synthesis of ZnS:Mn nanocrystals using a chemical route, with mercaptoethanol (ME) as the capping agent. The particle sizes for the nanocrystals were measured by X-ray diffraction (XRD) and also by studying transmission electron microscopy (TEM) patterns. The particle sizes of the synthesized samples were found to be between 1 and 3 nm. For samples with different concentrations of the capping agent, it was found that the TL intensity of the ZnS:Mn nanoparticles increased as the particle size decreased. A shift in the peak position of the TL glow curve was also seen with decreasing particle size. The TL intensity was found to be maximal for samples with 1.2% of Mn. A change in the peak position was not found for samples with different concentrations of Mn. The half-width glow peak curve method was used to determine the trap-depth. The frequency factor of the synthesized samples was also calculated. The stability of the charge carriers in the traps increases with decreasing nanoparticle size. The higher stability may be attributed to the higher surface/volume ratio and also to the increase in the trap-depth with decreasing particle size. Copyright © 2014 John Wiley & Sons, Ltd. Source

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