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Vinod Taxak,Satyender Pal khatkar,Sonika Singh,Sheetal Lohra,Avni Khatkar 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.3
A color tunable terbium doped GdSrAl3O7 nanophosphor has been synthesized at low temperature using solution combustion synthesis. The photoluminescent properties of nanophosphors have been explored by analyzing their excitation and emission spectra alongwith their decay curves. The emission spectra exhibit dominating green light at 544 nm due to 5D4→7F5 transition of Tb3+ ions in GdSrAl3O7 on excitation by UV light of 239 nm. Furthermore, the luminescence in Gd(1-x)SrAl3O7: xTb3+ nanophosphors shifted from blue to green color by properly tuning the concentration of terbium ions. Decay curves indicate that non-radiative cross-relaxation is primarily responsible for concentration quenching phenomenon in the GdSrAl3O7 host. X-ray diffraction (XRD) analysis confirmed that single tetragonal phased nanophosphor could be readily obtained at low temperature 550°C. The smooth surfaced nanocrystals with particle size of 45 - 50 nm have also been examined by transmission electron microscopy (TEM). All these features augmented the probability of GdSrAl3O7: Tb3+ nanophosphor for potential applications in optical devices.
Synthesis, structural and optical properties of Eu3+ -doped Ca2V2O7 nanophosphors
V.B. Taxak,Sheetal,Dayawati,S.P. Khatkar 한국물리학회 2013 Current Applied Physics Vol.13 No.3
Europium doped calcium pyrovanadate nanoparticles Ca2V2O7:Eu3þ, having a size of 57e63 nm, were synthesized using combustion process. Structure, morphological and optical properties of nanophosphors have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), fluorescence spectrometry (PL) and Fourier transform infra-red (FT-IR) spectroscopy. X-ray studies shows that a pure triclinic Ca2V2O7 phase was obtained at 900 C temperature. The red emission observed at 620 nm upon excitation at 305 nm is due to hypersensitive transition 5 D0 / 7 F2 of luminescent activator Eu3þ location at a site with no inversion symmetry in Ca2V2O7 crystal lattice. High luminescent intensity and easy synthesis technique make this red phosphor a promising candidate for application as luminescent materials.
Synthesis and luminescent properties of CaIn2O4:xTb nanocrystals
S.P. Khatkar,Sang Do Han,V.B. Taxak,Gaytri Sharma Dinesh Kumar,Dinesh Kumar 한국물리학회 2006 Current Applied Physics Vol.6 No.1l
Terbium-activated CaIn2O4:xTb (x = 0.12%, 0.5%, 1.0% and 2%) nanocrystals have been produced by combustion synthesis usingglycine as a fuel in a preheated furnace at 500.C. The nanocrystals obtained were characterized by scanning electron microscopyand X-ray diraction (XRD) techniques. The prepared nanocrystals under a UV source revealed green luminescence that was attributedto the transition from5D4 excited state to7F5 ground state of Tb3+ ions. In addition, the dependence of the luminescence intensity onTb3+ concentration and eect of glycine to nitrate ratio on the particle size of the nanocrystals have also been discussed.
Synthesis by Using the Combustion Method and Photoluminescence of SrZnO2 :Tb3+ Nanophosphors
Satyender Pal khatkar,Sang Do Han,Chi Hwan Han,Dinesh Kumar,Gaytri Sharma,Vinod Bala Taxak 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.6
SrZnO2:Tb3+ nanocrystals were synthesized by using a combustion route with metal nitrates as precursors and urea as a fuel in a furnace preheated to 500 C. The nanocrystals obtained through combustion synthesis were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The nanocrystals had sizes from 27 nm to 43 nm. The nanocrystals prepared under an UV source revealed green luminescence that was attributed to transitions from the 5D4 excited state to the 7FJ (J = 3 . 6) ground state of Tb3+ ions. The predominant green color from the magnetic dipole transition 5D4 ! 7F5 of Tb3+ was located at 545 nm. In addition, the dependence of the luminescence intensity on the Tb3+ concentrations and effect of heat treatment on the size of the nanocrystals are discussed. The intensity of the 5D4 emission increases with increasing sintering temperature while that of the 5D3 emission decreases.own
Characteristic white light emission via down-conversion SrGdAlO4:Dy3+ nanophosphor
Anju Hooda,S.P. Khatkar,Avni Khatkar,Sangeeta Chahar,Sushma Devi,Jyoti Dalal,V.B. Taxak 한국물리학회 2019 Current Applied Physics Vol.19 No.4
An efficient and cost-effective technique, solution combustion synthesis was used to synthesize Dy3+ doped SrGdAlO4 nanophosphor utilizing urea as a suitable fuel. The tetragonal phase and nano-crystallinity of the synthesized phosphor belonging to I4/mmm space group was confirmed by powder X-ray diffraction (PXRD) and transmission electron microscope (TEM) technique respectively. Various crystal structure parameters and refined atomic positions of host matrix and SrGd0.95Dy0.05AlO4 nanophosphor were determined by Rietveld refinement. The two intense bands i.e. blue and yellow bands were observed in photoluminescence emission spectrum recorded at 352 nm excitation wavelength, associated to transitions 4F9/2→6H15/2 (484 nm) and 4F9/2→6H13/2 (575 nm) respectively. Photometric characterizations revealed the emission of white color by the synthesized nanophosphor proving its wide applications in WLEDs (white light emitting diodes). Band gap values calculated using diffuse reflectance spectra (DRS) were found to vary in the range of 5.50 eV–5.59 eV for host and doped lattice system. Keeping in mind, the concentration quenching phenomenon, SrGd0.95Dy0.05AlO4 was considered as optimized nanophosphor for WLEDs.