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.
D. M. Pimpalshende; S. J. Dhoble
Abstract
Nowadays the research on synthesis of inorganic luminescent material with proper dimensions and morphologies has attracted great attention. Inorganic luminescent materials like LaPO4 have found many practical applications in the field of electroluminescent devices, integrated optics, biological labels, ...
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Nowadays the research on synthesis of inorganic luminescent material with proper dimensions and morphologies has attracted great attention. Inorganic luminescent materials like LaPO4 have found many practical applications in the field of electroluminescent devices, integrated optics, biological labels, modern lighting and display fields. We have prepared Dysprosium (Dy) doped LaPO4 nanoparticles at relatively low temperature in polyethylene glycol (PEG) medium by wet chemical method. Dy 3+ is doped in LaPO4 at various atomic concentrations (1, 2, 5 and 10 at %). All the samples have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL) and thermoluminescence (TL) techniques. XRD study reveals the monoclinic structure of prepared nanoparticles. Unit cell volume is found to be decrease linearly with increasing Dy 3+ concentration indicating homogeneous substitution of La 3+ ions in LaPO4 by Dy 3+ . From the FTIR study it is found that the band at 1044 cm -1 assigned to the phosphate group PO4 3- in the region of υ3 anti-symmetric stretching of P-O band. The PL spectrum shows emission band at about 435 nm is observed due to the transision of Dy 3+ ions corresponding to wavelength in the blue color region. The glow curve of LaPO4: Dy phosphor obeys second order kinetics.
V. V. Shinde; S. J. Dhoble
Abstract
The subject of this work is the characterization of the photoluminescence properties of RE 3+ doped bromoapatite inorganic optoelectronic phosphor material. This paper reports the luminescence properties of RE 3+ (Where RE= Ce, Dy, and Eu) doped Ca5(PO4)3Br, which has been prepared by solid state ...
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The subject of this work is the characterization of the photoluminescence properties of RE 3+ doped bromoapatite inorganic optoelectronic phosphor material. This paper reports the luminescence properties of RE 3+ (Where RE= Ce, Dy, and Eu) doped Ca5(PO4)3Br, which has been prepared by solid state reaction route. The prepared phosphor is well characterized by XRD, SEM, FT-IR and photoluminescence (PL) measurement. The apatite Ca5(PO4)3Br:Ce 3+ shows an efficient broad emission at 340 nm and weak 362 nm emission when excited at 293 nm. Ca5(PO4)3Br:Dy 3+ phosphor shows an efficient blue and yellow emissions at 485 nm and 577 nm respectively when excited at 390 nm . Ca5(PO4)3Br:Eu 3+ phosphor shows an orange and weak red emission at 592 nm and 615 nm respectively when excited at 396 nm. The effect of the RE 3+ concentration on the luminescence properties of Ca5 (PO4)3Br:RE 3+ phosphors are also studied. The investigated prepared bromoapatite phosphors may be suitable for a near UV excited LED.
H. K. Dahule; S. J. Dhoble
Abstract
We have synthesized series of new phosphorescent cyclometalated iridium (III) complexes Ir(Br-DPQ)2(acac), with 2-(4-bromo-phenyl)-4-phenyl-quinoline (Br-DPQ) ligand and Ir(Cl-BrDPQ)2 (acac) with 4-chloro-2-(4-bromophenyl)-4-phenyl quinoline (Cl-BrDPQ) ligand. Synthesized complexes and ligands were characterized ...
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We have synthesized series of new phosphorescent cyclometalated iridium (III) complexes Ir(Br-DPQ)2(acac), with 2-(4-bromo-phenyl)-4-phenyl-quinoline (Br-DPQ) ligand and Ir(Cl-BrDPQ)2 (acac) with 4-chloro-2-(4-bromophenyl)-4-phenyl quinoline (Cl-BrDPQ) ligand. Synthesized complexes and ligands were characterized by X-ray diffraction, elemental analysis, infrared spectroscopy (FTIR) and thermal analysis (TGA/DTA,DSC). UV-vis absorption and emission spectroscopy, photoluminescence (PL) emission peaks of Br-DPQ and Cl-BrDPQ in different solvents such as chloroform, dichloromethane, THF, acetic acid and formic acid is between 425 to 460 nm The metal complex display pure red luminescence in solution and in powder states in the range of λmax 615-651 nm. The iridium metal complex Ir(Br-DPQ)2(acac) where (Br-DPQ=2-(4-bromo phenyl)-4-phenyl quinoline shows strong 1MLCTand 3MLCT absorption peak at, 227, 265, 283, 346, and 432 nm in tetrahydrofuran (THF) solution and Ir(Cl-BrDPQ)2(acac) where (Cl-BrDPQ)=4chloro2-(4-Bromo phenyl)-4-phenyl quinoline shows strong 1MLCTand 3MLCT absorption peak at 262, 330, 438, 476, 505 and 535 nm in dichloromethane solution. It is suggested that the synthesized iridium complexes may be efficiently used as the emissive dopants in phosphorescent organic light-lmitting devices (PhOLEDs). Thus these complexes could be promising candidates for potential applications in Phosphorescent organic light-emitting diodes PhOLEDs, light-emitting electrochemical cells and solid-state organic lighting applications.
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.
J. A. Wani; N. S. Dhoble; S. J. Dhoble
Abstract
Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method ...
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Very little data on copper co-doped CaSO4: Dy and CaSO4: Dy, P phosphors seems to have been reported so far. In the present study the influence of copper and rare earths co-doping on thermoluminescence intensity of CaSO4: Dy, P phosphor has been investigated. Acid evaporation re-crystallization method was adopted for the synthesis purpose. Phosphors were characterized by scanning electron microscopy (SEM), photoluminescence (PL) and thermoluminescence (TL) techniques. Results obtained through this study are of mixed nature. In some cases, TL intensity is either greater or nearly equal to standard CaSO4: Dy while in other cases it is half or rather weak in comparison to standard CaSO4: Dy phosphor. Copper was found to suppress temperature peak structure above 300 o C. SEM micrographs of CaSO4: P, Dy, Cu, RE phosphors show that the particle size is in the micrometer range, 1 to 5 µm approximately. The systematic study carried out in this work is solely novel as no such report existed before. From this study it is clear now that by co-doping multi-impurities simultaneously to enhance TL characteristics of CaSO4: Dy phosphor is no longer useful because it proved otherwise.
Sakshi Sahare; S. J. Dhoble; Pranav Singh; Meera Ramrakhiani
Abstract
The powder of ZnS nanoparticles were prepared by using chemical deposition technique and characterized by electroluminescence techniques are reported in this paper. The estimated size of ZnS:Cu nanocrystals with change in capping agent concentration and ZnS:Cu/PVA nanocomposites and no effect of doping ...
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The powder of ZnS nanoparticles were prepared by using chemical deposition technique and characterized by electroluminescence techniques are reported in this paper. The estimated size of ZnS:Cu nanocrystals with change in capping agent concentration and ZnS:Cu/PVA nanocomposites and no effect of doping has been observed on the absorption spectra. Electroluminescence (EL) investigations of nanocrystalline powder as well as nanocomposites, it is seen that Log B vs. 1/V curve is a straight line with negative slope. This indicates that EL is produced by acceleration-collision mechanism. The detail EL characterization and application in display devices of these materials are reported in this paper.
Abhay D. Deshmukh; S. J. Dhoble; N.S. Dhoble
Abstract
The MAl12O19:Eu (M = Ca, Ba, Sr) phosphor were synthesized by combustion method and systematically characterized by photoluminescence excitation and emission spectra, concentration quenching, morphology and X-ray mapping with scanning electron microscopy. In SrAl12O19:Eu phosphor two PL emission peaks ...
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The MAl12O19:Eu (M = Ca, Ba, Sr) phosphor were synthesized by combustion method and systematically characterized by photoluminescence excitation and emission spectra, concentration quenching, morphology and X-ray mapping with scanning electron microscopy. In SrAl12O19:Eu phosphor two PL emission peaks are observed at about 389 nm and another around 420 nm as well as BaAl12O19:Eu phosphor shows blue emission around 460 nm is observed in the blue region of the spectrum and CaAl12O19:Eu shows only red emission at 592 as well as 615 nm. Both phosphors can be efficiently excited in the wavelength range of 250-425 nm, where the near UV (~320 nm) solid state excitation is matched. By combining MAl12O19:Eu (M = Ca, Ba, Sr) phosphor with near UV chops emitting intense blue green (Ba), yellow-red (Ca) and blue purple (Sr) LEDs white LEDs can be produced.
