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Title: Li{sub 3}Gd{sub 3}Te{sub 2}O{sub 12}:Eu{sup 3+}- an intense red phosphor for solid state lighting applications

Abstract

Li{sub 3}Gd{sub 3−3x}Eu{sub 3x}Te{sub 2}O{sub 12} (x=0.05−1.0) phases with garnet structure were synthesized by high temperature solid state reaction and the photoluminescence properties were investigated. The appearance of bands due to intra 4 f transitions of Gd{sup 3+} in the excitation spectra recorded by monitoring the 612 nm emission line of the activator indicates Gd{sup 3+}→Eu{sup 3+} energy transfer in this host lattice. Under 395 nm excitation, the electric dipole transition is predominant in the emission spectrum of Eu{sup 3+} and is in agreement with the C{sub 2} point group (noncentrosymmetric) of the EuO{sub 8} polyhedron. The critical concentration of the Eu{sup 3+} activator in this series was found to be 0.6 (x=0.2) above which, concentration quenching occurs. The emission intensity of the phosphor composition, Li{sub 3}Gd{sub 2.4}Eu{sub 0.6}Te{sub 2}O{sub 12} is ~4 times that of the commercial sample of Y{sub 2}O{sub 3}:Eu{sup 3+} phosphor. - Highlights: • New Eu{sup 3+} doped garnet. • Intense electric dipole emission. • Gd{sup 3+}→Eu{sup 3+} energy transfer.

Authors:
 [1];  [2];  [1]
  1. Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036 (India)
  2. Department of Chemistry, Rajiv Gandhi University of Knowledge Technologies, Nuzvid, Andhra Pradesh 521202 (India)
Publication Date:
OSTI Identifier:
22658199
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 246; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DOPED MATERIALS; ELECTRIC DIPOLES; EMISSION SPECTRA; ENERGY TRANSFER; EUROPIUM IONS; EXPERIMENTAL DATA; GADOLINIUM COMPOUNDS; GADOLINIUM IONS; LITHIUM COMPOUNDS; PHOSPHORS; TEMPERATURE RANGE 0400-1000 K; YTTRIUM OXIDES

Citation Formats

Tiwari, Hansnath, Asiri Naidu, S., and Varadaraju, U.V., E-mail: varada@iitm.ac.in. Li{sub 3}Gd{sub 3}Te{sub 2}O{sub 12}:Eu{sup 3+}- an intense red phosphor for solid state lighting applications. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.12.005.
Tiwari, Hansnath, Asiri Naidu, S., & Varadaraju, U.V., E-mail: varada@iitm.ac.in. Li{sub 3}Gd{sub 3}Te{sub 2}O{sub 12}:Eu{sup 3+}- an intense red phosphor for solid state lighting applications. United States. doi:10.1016/J.JSSC.2016.12.005.
Tiwari, Hansnath, Asiri Naidu, S., and Varadaraju, U.V., E-mail: varada@iitm.ac.in. Wed . "Li{sub 3}Gd{sub 3}Te{sub 2}O{sub 12}:Eu{sup 3+}- an intense red phosphor for solid state lighting applications". United States. doi:10.1016/J.JSSC.2016.12.005.
@article{osti_22658199,
title = {Li{sub 3}Gd{sub 3}Te{sub 2}O{sub 12}:Eu{sup 3+}- an intense red phosphor for solid state lighting applications},
author = {Tiwari, Hansnath and Asiri Naidu, S. and Varadaraju, U.V., E-mail: varada@iitm.ac.in},
abstractNote = {Li{sub 3}Gd{sub 3−3x}Eu{sub 3x}Te{sub 2}O{sub 12} (x=0.05−1.0) phases with garnet structure were synthesized by high temperature solid state reaction and the photoluminescence properties were investigated. The appearance of bands due to intra 4 f transitions of Gd{sup 3+} in the excitation spectra recorded by monitoring the 612 nm emission line of the activator indicates Gd{sup 3+}→Eu{sup 3+} energy transfer in this host lattice. Under 395 nm excitation, the electric dipole transition is predominant in the emission spectrum of Eu{sup 3+} and is in agreement with the C{sub 2} point group (noncentrosymmetric) of the EuO{sub 8} polyhedron. The critical concentration of the Eu{sup 3+} activator in this series was found to be 0.6 (x=0.2) above which, concentration quenching occurs. The emission intensity of the phosphor composition, Li{sub 3}Gd{sub 2.4}Eu{sub 0.6}Te{sub 2}O{sub 12} is ~4 times that of the commercial sample of Y{sub 2}O{sub 3}:Eu{sup 3+} phosphor. - Highlights: • New Eu{sup 3+} doped garnet. • Intense electric dipole emission. • Gd{sup 3+}→Eu{sup 3+} energy transfer.},
doi = {10.1016/J.JSSC.2016.12.005},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 246,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2017},
month = {Wed Feb 15 00:00:00 EST 2017}
}
  • The authors have investigated the mechanism and determined the enthalpy of crystallization of x-ray amorphous iron garnets of rare-earth elements and their solid solutions. The authors have established a relation between the mechanism of the solid-phase reaction of formation of the iron garnets and the decrease in the ionic radius of the rare-earth element in the dodecahedral positions. A rise in the temperature during crystallization of amorphous phases facilitates a rapid completion of the reaction in which double oxides with a complex three-sublattice structure are released.
  • A series of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, R{sup +}, and Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} (R{sup +}=Li{sup +}, Na{sup +}, and K{sup +}) phosphors are synthesized by solid-state reaction method in air. All phosphors show bright red emissions centered at ∼617 nm upon excitation with UV light of 397 nm. Bi{sup 3+} is a sensitizer for the luminescence of Eu{sup 3+}, and can improve significantly the PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+} phosphor due to energy transfer between Bi{sup 3+} andmore » Eu{sup 3+} ions. The sensitization mechanism is investigated and discussed by energy level diagrams of Bi{sup 3+} and Eu{sup 3+} ions. R{sup +} ion is used as the charge compensator to improve the luminescence intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+} and Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphors, and their PL intensities are enhanced in the sequence K{sup +}→Na{sup +}→Li{sup +}. These phosphors can be promising red emitting candidate for white LED with a ∼397 nm near UV chip excitation owing to the high brightness. - Graphical abstract: Energy transfer and charge compensation can enhance PL intensity of phosphors obviously. - Highlights: • Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor is synthesized. • Energy transfer between Eu{sup 3+} and Bi{sup 3+} ions benefit PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor. • Alkaline metal ions can further improve the PL intensity of Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+} phosphor. • Ca{sub 3}Ti{sub 2}O{sub 7}:Eu{sup 3+}, Bi{sup 3+}, R{sup +} phosphor may be promising red emitting candidate for white LED.« less
  • Graphical abstract: - Highlights: • Novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was prepared by solid-state reaction. • Excitation spectra suggested an obvious absorption in near-ultraviolet region. • Under 392 nm excitation, the phosphors exhibited a red emission at 614 nm. • Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white LEDs. - Abstract: A novel red phosphor Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} was synthesized using a solid-state reaction method, and its luminescence characteristics and charge compensators effect (Li{sup +}, Na{sup +}, K{sup +}) were investigated. The excitation spectra showed a obviousmore » absorption in near-ultraviolet region. Under 392 nm excitation, the phosphors exhibited an intense red emission at 614 nm. The Commission Internationale de l’Eclairage (CIE) chromaticity coordinates and quantum efficiency (QE) were (0.65, 0.35) and 62.3%, respectively. The good color saturation, high quantum efficiency and small thermal-quenching properties indicate that Ca{sub 12}Al{sub 14}O{sub 32}Cl{sub 2}:Eu{sup 3+} could be potentially applied in near UV white light-emitting diodes.« less
  • Photoluminescence studies on Eu{sup 3+}-doped double perovskites with the formula A{sub 2}CaWO{sub 6} (A=Sr, Ba) revealed that the forced electric dipole (ED) transition is present when Eu{sup 3+} is substituted at the non-centrosymmetric Sr-site vis-a-vis substitution at the centrosymmetric Ca-site shows both ED and magnetic dipole (MD) transition. A series of novel orange-red-emitting phosphor compositions Sr{sub 1.9-x}Ba{sub x}Eu{sub 0.05}Li{sub 0.05}CaWO{sub 6} (x=0-1.9) have also been synthesized and characterized by powder X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS) and photoluminescence. XRD results reveal a phase transition from monoclinic to pseudo-cubic structure for x{<=}0.2. All the compositions show broad charge transfer bandmore » and orange-red (MD and ED) emission. However, the relative intensity of the MD and ED depends on the Ba content present in the host lattice. Select compositions in this system of compounds could find potential application as orange-red phosphors for white light generation using blue/near-UV GaN-based light-emitting diodes (LEDs). - Graphical abstract: A series of orange-red-emitting A{sub 2}CaWO{sub 6} (A=Sr, Ba) and Sr{sub 1.9-x}Ba{sub x}Eu{sub 0.05}Li{sub 0.05}MoO{sub 6} (x=0-1.9) phosphor with double perovskite structure have been synthesized by solid-state reaction. All the compositions show broad charge transfer band and orange-red [magnetic dipole (MD) and electric dipole (ED)] emission. The red emission of Sr{sub 1.5}Eu{sub 0.05}Li{sub 0.05}Ba{sub 0.4}CaWO{sub 6} is found to be {approx}4.5 times higher than that of commercial red phosphor (Nichia) under 465 nm excitation and hence this phosphor could be a potential candidate for white LED based on blue/NUV GaN LED.« less
  • The crystal structures of new rare earth-based germanate compounds (Ca{sub 3}Pr{sub 2}Ge{sub 3}O{sub 12}, Ca{sub 3}Nd{sub 2}Ge{sub 3}O{sub 12}, Ca{sub 3}Sm{sub 2}Ge{sub 3}O{sub 12}, Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} and Ca{sub 3}Dy{sub 2}Ge{sub 3}O{sub 12}) have been determined by Rietveld refinement calculations on the collected synchrotron X-ray diffraction powder patterns. A different distribution of the rare earth ions in the three available crystal sites was observed, as the main structural feature. The reasons of the instability of the silico-carnotite structure for lanthanide ions out of the range Pr–Dy have been proposed. Finally, the luminescence spectroscopy of the Eu{sup 3+} dopantmore » ion in Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} was presented and analyzed taking into account the observed structural characteristics. The Eu{sup 3+} luminescence spectroscopy was also compared with the one of Eu{sup 3+} doped Ca{sub 3}Gd{sub 2}Si{sub 3}O{sub 12} and Ca{sub 3}Lu{sub 2}Si{sub 3}O{sub 12} isostructural materials. - Graphical abstract: The structural study on Ca{sub 3}Ln{sub 2}Ge{sub 3}O{sub 12} exploiting synchrotron X-ray diffraction, allows us to determine the detailed geometry of the coordination polyhedra of the metals and their distribution in the crystal sites. These features are, in the case of Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} host, closely related to the luminescence spectroscopy of the Eu{sup 3+} dopant ion. Display Omitted - Highlights: • The structure of the Ca{sub 3}Ln{sub 2}Ge{sub 3}O{sub 12} (Ln=Pr, Nd, Sm, Gd and Dy) was determined. • Different distribution of Ln{sup 3+} ions on the three available crystal sites was observed. • A detailed structural study focused on the metal coordination polyhedra was performed. • The instability of the silico-carnotite structure out of the range Pr–Dy was discussed. • The luminescence of the dopant Eu{sup 3+} ion in Ca{sub 3}Gd{sub 2}Ge{sub 3}O{sub 12} was presented and analyzed.« less