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.
Amrita Das; Vishal Shama
Abstract
In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to ...
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In the present study, we investigate upon the synthesis and characterization of inorganic Eu 3+ doped Al2O3 nanophosphor for its structural and luminescent properties. The luminescent nanopowder was prepared using a combustion method in which the stoichiometric ratio of oxidizers and fuel was fixed to one, with varying concentration of Eu 3+ ions acting as an activator. The prepared powder showed excellent thermal stability. For the identification of the phase and structure of the powder synthesized, X-ray diffractometer was used. From the XRD analysis, it is revealed that the rhombohedral crystallite phase of α-alumina was formed. The type of morphology and particle size was ascertained by Filed Emission-Scanning Electron Microscope (FE-SEM) and it was found that particles were having irregular spherical shape. A qualitative analysis of these nanophosphor particles was made using an Energy dispersive X-ray detector (EDS) and it was found that the samples were composed of Al, O and Eu ions. Photo-luminescence (PL) spectra were obtained using Spectrofluorometer absorption. The intense band position was observed at 618 nm and other less intense bands were also seen at 592 nm, 601 nm, 631 nm, while two weak bands were observed at 660 nm and 718 nm, when excited at 226 nm. The CIE color space chromaticity diagram was calculated from the CIE Calculator program using obtained PL spectra. The prepared nanophosphor powder was tested for latent fingerprint detection in forensic applications. The synthesized nanophosphor was successfully used as a latent fingerprint developing powder on various non-porous surfaces for forensic application.
Atul N. Yerpude; Sanjay Janrao Dhoble; B. Ramesh; Borelli Deva Prasad Raju
Abstract
In this study, Sm 3+ - and Dy 3 -doped SrAl4O7 phosphors were synthesized by combustion method. X-ray diffraction (XRD) measurement confirmed the monoclinic crystal structure of SrAl4O7. Sr-O and Al-O bonds were identified by Fourier transform infrared (FTIR) spectroscopy. Under 352 nm excitation, the ...
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In this study, Sm 3+ - and Dy 3 -doped SrAl4O7 phosphors were synthesized by combustion method. X-ray diffraction (XRD) measurement confirmed the monoclinic crystal structure of SrAl4O7. Sr-O and Al-O bonds were identified by Fourier transform infrared (FTIR) spectroscopy. Under 352 nm excitation, the SrAl4O7: Dy 3+ phosphor shown emission bands at 475 nm (blue) and 574 nm (yellow) that are due to 4 F9/2→ 6 H15/2, 6 H13/2 transitions, respectively. Photoluminescence spectra (PL) of SrAl4O7: Sm 3+ phosphor has shown bright orange red emission at 598 nm with an excitation wavelength of 405 nm. The decay curve of Sm 3+ and Dy 3+ single doped SrAl4O7 phosphors were well fitted to a bi-exponential function. The obtained results show that the prepared phosphors may be applicable in the field of eco-friendly solid state lighting technology.
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.
Niyaz Parvin Shaik; N. V. Poornachandra Rao; K. V. R. Murthy
Abstract
Pure LaPO4 and LaPO4: Eu (0.5 mol %) Ce (0.5 mol %) phosphors were synthesized by the solid-state reaction method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra and the particle size analysis were used to characterize ...
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Pure LaPO4 and LaPO4: Eu (0.5 mol %) Ce (0.5 mol %) phosphors were synthesized by the solid-state reaction method. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra and the particle size analysis were used to characterize these samples. The XRD results reveal that the synthesized LaPO4:Eu (0.5 mol%) Ce (0.5 mol%) phosphors are well crystalline and assigned to the monoclinic structure with a main (120) diffraction peak. The calculated crystallite size of pure LaPO4 and LaPO4:Eu, Ce phosphors were 67.6nm and 64nm respectively. Upon excitation at 254nm wavelength, the emission spectrum of pure LaPO4 phosphor emits a maximum intensity peak at 470 (blue) nm. In the emission spectrum of LaPO4:Eu 3+ Ce 3+ phosphor, the low contributions of the red (613nm) 5D0-7F2 emissions and the high intensity of the orange-red (589nm)5D0-7F1 emission results in high color purities.The most intense emissions appearing in the 580-620nm region is responsible for the strong orange-red luminescence observed in the Eu,Ce doped LaPO4 phosphor whose CIE colour coordinates are x = 0.57 and y = 0.43.Thus the prepared phosphors can be used as an orange-red emitting material in the field of illuminations and display devices.
Deepa Shukla; K. B. Ghormare;S. J. Dhoble
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.
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.
J.A. Wani; M.S. Atone; S.J. Dhoble
Abstract
Anchor CaSO4: Dy, P is known for its dosimetric characteristics for a very long time now. In this work we have carried out a comparative study on TL intensity of CaSO4: Dy, P, Ce phosphors using two different wet chemical synthesis routes. Nobody seems to have reported this kind of study on CaSO4: Dy, ...
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Anchor CaSO4: Dy, P is known for its dosimetric characteristics for a very long time now. In this work we have carried out a comparative study on TL intensity of CaSO4: Dy, P, Ce phosphors using two different wet chemical synthesis routes. Nobody seems to have reported this kind of study on CaSO4: Dy, P, Ce 3+ phosphors and as a result it may be regarded as something new. Phosphors were characterized by scanning electron microscopy, photoluminescence and thermoluminescence techniques. The two methods were found to drastically affect the TL intensity of CaSO4: Dy, P, Ce phosphors. The TL intensity of CaSO4: Dy, P, Ce prepared by co-precipitation method is less by a factor of 204 than the CaSO4: Dy, P, Ce phosphor prepared via acid evaporation method. Moreover, co-doping of P and Ce ions into CaSO4:Dy was observed to enhance the thermoluminescence intensity by a factor of 1.11 than the standard phosphor in case of phosphor prepared via acid evaporation method. Surface morphology resulted through two different synthesis routes was also studied. Structures like broad metal slabs were observed for CaSO4: Dy, P, Ce phosphors using acid evaporation method. We hope that this study may prove very helpful in selecting a preparation method for CaSO4: Dy, RE phosphors especially when better TL properties and good crystal grain size are desired. We also think that acid evaporation method is always a better choice to prepare CaSO4: Dy, RE phosphors than co-precipitation method.
Ch. Atchyutha Rao; Poornachandra Rao V. Nannapaneni; K. V. R. Murthy
Abstract
In this paper we report the synthesis and luminescence of strontium cerium oxide (Sr2CeO4:Eu 3+ (0.5mol%),La 3+ (0.5mol%) prepared by solid state reaction method in air at 12000C.These samples were characterized by X-ray diffraction, scanning electron microscope (SEM) and photoluminescence (PL) techniques, ...
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In this paper we report the synthesis and luminescence of strontium cerium oxide (Sr2CeO4:Eu 3+ (0.5mol%),La 3+ (0.5mol%) prepared by solid state reaction method in air at 12000C.These samples were characterized by X-ray diffraction, scanning electron microscope (SEM) and photoluminescence (PL) techniques, particle size analysis. The photo luminescence (PL) spectra of pure and Eu 3+ , La 3+ codoped Sr2CeO4 were recorded at room temperature. Sr2CeO4 phosphor was effectively excited around 250 nm and observed a broad emission band peak around 467 nm. XRD data revealed that the structure of Sr2CeO4 is orthorhombic, and the mean crystallite size of Sr 2CeO4 and Sr2CeO4: Eu 3+ , La 3+ were 9 nm and 11nm respectively. The colour co-ordinates of Sr2CeO4 were x = 0.16 and y = 0.18 and CIE co-ordinates revealed that the present phosphors may be used in white light applications.
Aiyu Zhang; Ping Yang; Yongqiang Cao; Yuanna Zhu
Abstract
Eu, Dy codoped Y2Zr2O7 crystalline powders have been prepared by a simple sol-gel-combustion method. The lumincescence excitation and emission spectra of the products were measured, and the CIE chromaticity was introduced to characterize the color of the phosphor. It was found that the emission color ...
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Eu, Dy codoped Y2Zr2O7 crystalline powders have been prepared by a simple sol-gel-combustion method. The lumincescence excitation and emission spectra of the products were measured, and the CIE chromaticity was introduced to characterize the color of the phosphor. It was found that the emission color of the Eu, Dy codoped Y2Zr2O7 powders depends on the doping concentration of Eu, Dy ions and the excitation wavelength. White light emission has been observed for Y2Zr2O7: 1.5%Eu 3+ , 2.0%Dy 3+ under 350nm excitation, for which the calculated chromaticity coordinate is (0.37, 0.32).
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.
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.
