Devender Singh; Suman Sheoran; Vijeta Tanwar
Abstract
In this review article, different synthetic procedures and characterization techniques used for the development of materials are discussed briefly. The stability and high luminous intensity of silicate materials makes them practically important in the field of white light emitting diodes (WLEDs). During ...
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In this review article, different synthetic procedures and characterization techniques used for the development of materials are discussed briefly. The stability and high luminous intensity of silicate materials makes them practically important in the field of white light emitting diodes (WLEDs). During the experimental designing of our research, we have understood carefully the theoretical and methodological strategy regarding the synthesis of phosphors and then, a large number of silicate-based luminescent materials have been prepared using sol-gel technology. Among them, a series of silicate materials having composition M(2-x)EuxSi2O7 (M = Y, Gd, La and x = 0.03 moles) have been described in this review prepared with sol-gel process. Intense peak in europium (III) doped M2Si2O7 silicates originate from 5 D0→ 7 F2 transition of Eu 3+ ion available in crystal lattices. X-ray diffraction pattern have triclinic structure for Y2Si2O7 and Gd2Si2O7 silicate phosphors. However, hexagonal and monoclinic structures are obtained for La2Si2O7 material at different temperatures employed for further annealing. Transmission electron microscopic analysis is used to study the morphology and particle size of prepared phosphors. Excellent luminescence response of these silicate phosphors make them suitable for photonic applications and also open up new avenues for solid-state lighting, cathode ray tubes, fluorescent lamps and scintillators etc.
Ketki S. Dhoble; J. A. Wani; S. J. Dhoble
Abstract
Phosphate based compounds doped with rare earth ions are promising luminescent materials for many applications including solid state lighting. In this work photoluminescence properties of K2SrP < sub>2O7:RE 3+ (RE = Sm, Tb, Eu, Dy) phosphors are presented for the first time. K2SrP < sub>2O7:RE ...
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Phosphate based compounds doped with rare earth ions are promising luminescent materials for many applications including solid state lighting. In this work photoluminescence properties of K2SrP < sub>2O7:RE 3+ (RE = Sm, Tb, Eu, Dy) phosphors are presented for the first time. K2SrP < sub>2O7:RE 3+ phosphors activated with the trivalent rare earth ions were synthesized by combustion method. Phosphors were characterized for phase purity, morphology and luminescent properties. Elemental analysis was done through energy dispersive spectroscopy (EDS). The emission and excitation spectra were followed to study the luminescence characteristics of K2SrP < sub>2O7:RE 3+ phosphors. The as prepared powders of RE 3+ doped K2SrP < sub>2O7 emit red, green and yellowish white light as a result of f-f transitions. The study is novel as no such luminescence data are available for this compound.
N. S. Kokode; V. R. Panse; S. J. Dhoble
Abstract
In present work we studied the luminescence properties of Tb 3+ and Mn 2+ doped Ca2PO4Cl phosphor synthesized by wet chemical method were studied with extra heat treatment, to understand the mechanism of excitation and the corresponding emission of prepared phosphor. For the green emission, Tb 3+ ion ...
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In present work we studied the luminescence properties of Tb 3+ and Mn 2+ doped Ca2PO4Cl phosphor synthesized by wet chemical method were studied with extra heat treatment, to understand the mechanism of excitation and the corresponding emission of prepared phosphor. For the green emission, Tb 3+ ion is used as an activator, the excitation and emission spectra indicate that this phosphor can be effectively excited by 380 nm, to exhibit bright green emission centered at 545 nm corresponding to the f→f transition of Tb 3+ ions. The emission spectrum of Mn 2+ ion at 405 nm excitation 4 T1(4G) - 6 A1(6S) gives an emission band at 591 nm (orange-red). The observed photoluminescence (PL) measurements of Tb 3+ and Mn 2+ activated prepared phosphor indicates that these are the outstanding green and orange-red emitting potential phosphor , suitable application for the solid state lighting. The synthesized phosphors were analyzed by X-ray diffraction (XRD) for confirmation of phase and purity. The morphology and structure were characterized by scanning electron microscopy. Thus the phosphors in this system may be chosen as the green component for the tri-color lamp and certainly applied in w-UV LEDs. In the view of the excitation band and excellent luminescent properties, Ca2PO4Cl:Tb 3+ and Mn 2+ phosphor is expected to be a potential candidate for application in n-UV white LEDs and solid-state lighting because of its cost-efficient manufacturing, mercury-free excitation and eco-friendly characteristics.
J. A. Wani; N. S. Dhoble; N. S. Kokode; S. J. Dhoble
Abstract
As host materials, phosphate compounds offer great potential for lanthanides to display luminescence characteristics. In this work luminescence behaviour of Na2CaP < sub>2O7:RE 3+ are presented for the first time. Na2CaP < sub>2O7 novel phosphors activated with the trivalent rare earth ions ((RE = Ce, ...
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As host materials, phosphate compounds offer great potential for lanthanides to display luminescence characteristics. In this work luminescence behaviour of Na2CaP < sub>2O7:RE 3+ are presented for the first time. Na2CaP < sub>2O7 novel phosphors activated with the trivalent rare earth ions ((RE = Ce, Eu, Tb, Sm) were synthesized by solid state diffusion method. Phosphors were characterized for phase purity and luminescent properties. The emission and excitation spectra were followed to explore the luminescence attributes. The as prepared powders of Ce 3+ , Eu 3+ ,Tb 3+ and Sm 3+ doped Na2CaP < sub>2O7 emit near-uv, red, green and orange reddish light as result of f-d and f-f transitions respectively. The study is novel as no such luminescence data are available for this compound. The results are promising in view of the requirement for pc-white LEDs for solid state lighting applications.
A.N. Yerpude;S.J. Dhoble
Abstract
Eu 3+ , Dy 3+ activated SrCaAl2O5 phosphor were synthesized by the combustion method at 550°C. The prepared phosphor characterized by X-ray diffraction and photoluminescence measurements. The photoluminescence study of Eu 3+ doped phosphor shows that the intensity of electric dipole transition ( ...
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Eu 3+ , Dy 3+ activated SrCaAl2O5 phosphor were synthesized by the combustion method at 550°C. The prepared phosphor characterized by X-ray diffraction and photoluminescence measurements. The photoluminescence study of Eu 3+ doped phosphor shows that the intensity of electric dipole transition ( 5 D0→ 7 F2) at 615 nm dominates over that of magnetic dipole transition ( 5 D0→ 7 F1) at 596 nm under 395nm excitation. The PL emission spectrum of Dy 3+ ion at 350nm excitation gives an emission band at 484 nm (blue) and 575 nm (yellow). The optimum concentration of both the dopant having highest luminescence intensity is found to be 0.5 mole %. The obtained PL results indicated that prepared phosphor is suitable as near UV excited white light-emitting diodes.
K. N. Shinde;S. J. Dhoble
Abstract
In this article, the influence of lithium co-doped on Sr5(PO4)3F:Eu 3+ halophosphate based phosphor reported. The Sr5(PO4)3F:Eu 3+ and Sr5(PO4)3F:Eu 3+ , Li + phosphors were prepared by combustion synthesis route using urea as the fuel. The phosphors were characterized by X-ray diffraction (XRD) and ...
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In this article, the influence of lithium co-doped on Sr5(PO4)3F:Eu 3+ halophosphate based phosphor reported. The Sr5(PO4)3F:Eu 3+ and Sr5(PO4)3F:Eu 3+ , Li + phosphors were prepared by combustion synthesis route using urea as the fuel. The phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) techniques. The powders were annealed at 900 o C and 1200 o C and characterized by X-ray diffraction (XRD) which shows that the major crystalline phases from the as prepared or annealed powder samples were identical. The PL results show that the incorporation of Li + ions into the Sr5 (PO4)3F:Eu 3+ lattice could induce a remarkable improvement of the PL intensity in red region at 395 nm excitation wavelength. The highest emission intensity was observed with the compound of Eu 3+ 0.5 mol% and Li + 0.5 mol% co-doped Sr5(PO4)3F, whose brightness was increased by a factor of more than 3.0 in comparison with that of the Sr5(PO4)3F:Eu 3+ . The 300–400 nm is Hg free excitation (Hg excitation is 85% 254 nm wavelength of light and 15% other wavelengths), which is characteristic of solid-state lighting phosphors. Hence PL emission in trivalent europium co-doped with lithium may be efficient photoluminescent materials for solid-state lighting phosphors as a red component.