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1.
The luminescent properties of europium (Eu)‐ and dysprosium (Dy)‐co‐doped K3Ca2(SO4)3Cl halosulfate phosphors were analyzed. This paper reports the photoluminescence (PL) properties of K3Ca2(SO4)3Cl microphosphor doped with Eu and Dy and synthesized using a cost‐effective wet chemical method. The phosphors were characterized by X‐ray diffraction and scanning electron microscopy. The CIE coordinates were calculated to display the color of the phosphor. PL emission of the prepared samples show peaks at 484 nm (blue), 575 nm (yellow), 594 nm (orange) and 617 nm (red). The emission color of the Eu,Dy‐co‐doped K3Ca2(SO4)3Cl halophosphor depends on the doping concentration and excitation wavelength. The addition of Eu in K3Ca2(SO4)3Cl:Dy greatly enhances the intensity of the blue and yellow peaks, which corresponds to the 4 F9/26H15/2 and 4 F9/26H13/2 transitions of Dy3+ ions (under 351 nm excitation). The Eu3+/Dy3+ co‐doping also produces white light emission for 1 mol% of Eu3+, 1 mol% of Dy3+ in the K3Ca2(SO4)3Cl lattice under 396 nm excitation, for which the calculated chromaticity coordinates are (0.35, 0.31). Thus, K3Ca2(SO4)3Cl co‐doped with Eu/Dy is a suitable candidate for NUV based white light‐emitting phosphors technology. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

2.
Eu3+‐activated MAl(SO4)2Br phosphors (where M = Mg or Sr) are successfully prepared using a wet chemical reaction technique. The samples are characterized by X‐ray diffraction (XRD) and photoluminescence (PL) spectroscopies. The XRD pattern revealed that both the samples are microcrystalline in nature. PL of Eu3+‐doped SrAl(SO4)2Br and MgAl(SO4)2Br phosphors exhibited characteristic red emission coming from the 5D07F2 (616 nm) electron transition, when excited by 396 nm wavelength of light. The maximum intensity of luminescence was observed at a concentration of 1 mol% Eu3+. The intensity of the electric dipole transition at 616 nm is greater than that of the magnetic dipole transition at 594 nm. The results showed that MAl(SO4)2Br:Eu3+, (M = Mg, Sr) phosphors have potential application in near‐UV light‐emitting diodes as efficient red‐emitting phosphor. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

3.
In this article we report Eu3+ luminescence in novel K3Ca2(SO4)3Cl phosphors prepared by wet chemical methods. The Eu3+ emission was observed at 594 nm and 615 nm, keeping the excitation wavelength constant at 396 nm nearer to light‐emitting diode excitation, Furthermore, phosphors were characterized by X‐ray diffraction for the confirmation of crystallinity. The variation of the photoluminescence intensity with impurity concentration has also been discussed. Thus, prominent emission in the red region makes prepared phosphors more applicable for white light‐emitting diodes. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

4.
A new halophosphor K3Ca2(SO4)3 F activated by Eu or Ce and K3Ca2(SO4)3 F:Ce,Eu co‐doped halosulfate phosphor has been synthesized by the co‐precipitation method and characterized for its photoluminescence (PL). The PL emission spectra of the K3Ca2(SO4)3 F :Ce phosphor show emission at 334 nm when excited at 278 nm due to 5d → 4f transition of Ce3+ ions. In the K3Ca2(SO4)3 F:Eu lattice, Eu2+ (440 nm) as well as Eu3+ (596 nm and 615 nm) emissions have been observed showing 5D07 F1 and 5D07 F2 transition of the Eu3+ ion, which is in the blue and red region of the visible spectrum respectively. The trivalent europium ion is very useful for studying the nature of metal coordination in various systems owing to its non‐degenerate emitting 5D0 state. K3Ca2(SO4)3 F:Ce,Eu is suitable for Ce3+ → Eu2+ → Eu3+ energy transfer in which Ce3+and Eu2+ play the role of sensitizers and Eu2+ and Eu3+ act as the activators. The observations presented in this paper are relevant for lamp phosphors. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
Europium ion (Eu2+) doped Sr2SiO4 phosphors with greenish‐yellow emission were synthesized using microwave‐assisted sintering. The phase structure and photoluminescence (PL) properties of the obtained phosphor samples were investigated. The PL excitation spectra of the Sr2SiO4:Eu2+ phosphors exhibited a broad band in the range of 260 nm to 485 nm with a maximum at 361 nm attributed to the 5f‐4d allowed transition of the Eu2+ ions. Under an excitation at 361 nm, the Sr2SiO4:Eu2+ phosphor exhibited a greenish‐yellow emission peak at 541 nm with an International‐Commission‐on‐Illumination (CIE) chromaticity of (0.3064, 0.4772). The results suggest that the microwave‐assisted sintering method is promising for the synthesis of phosphors owing to the decreased sintering time without the use of additional reductive agents.  相似文献   

6.
A new phosphor CaAl(SO4)2Br doped with Dy, Ce and Eu is reported. Rare earth (Dy, Eu and Ce)‐doped polycrystalline CaAl(SO4)2Br phosphors were prepared using a wet chemical reaction method and studied for X‐ray diffraction and photoluminescence (PL) characteristics. Dy3+ emission in the CaAl(SO4)2Br lattice was observed at 484 and 574 nm in the blue and yellow regions of the spectrum, which are assigned to 4 F9/26H15/2 and 4 F9/26H13/2 transitions of the Dy3+ ion, respectively. While the PL emission spectra of CaAl(SO4)2Br:Ce phosphor showed Ce3+ emission at 347 nm due to 5d → 4f transition of the Ce3+ ion. In a CaAl(SO4)2Br:Eu lattice, Eu3+ emissions were observed at 593 and 617 nm, coming from the 5D07 F1 and 5D07 F2 electron transitions, respectively. The PL study showed that the intensity of electric dipole transition at 617 nm dominates over that of magnetic dipole transition at 590 nm. The maximum PL intensity was obtained for a 1 mol% concentration of Eu3+ in CaAl(SO4)2Br host lattice. The results showed that the material may be a promising candidate as a blue‐, yellow‐ and red‐emitting phosphor. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

7.
A series of Ca2Mg0.25Al1.5Si1.25O7:Ce3+/Eu2+/Tb3+ phosphors was been prepared via a conventional high temperature solid‐state reaction and their luminescence properties were studied. The emission spectra of Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Eu2+ and Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Tb3+ phosphors show not only a band due to Ce3+ ions (409 nm) but also as a band due to Eu2+ (520 nm) and Tb3+ (542 nm) ions. More importantly, the effective energy transfer from Ce3+ to Eu2+ and Tb3+ ions was confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and energy transfer mechanism were investigated and were demonstrated to be of resonant type via dipole–dipole (Ce3+ to Eu2+) and dipole–quadrupole (Ce3+ to Tb3+) reactions, respectively. Under excitation at 350 nm, the emitting color could be changed from blue to green by adjusting the relative doping concentration of Ce3+ and Eu2+ ions as well as Ce3+ and Tb3+ ions. The above results indicate that Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Eu2+/Tb3+ are promising single‐phase blue‐to‐green phosphors for application in phosphor conversion white‐light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
In this paper, we have reported the photoluminescence (PL) properties of the Ba2Mg(PO4)2:Eu3+ phosphor synthesized using a wet chemical method. The preliminary scanning electron microscopy (SEM) investigation of the sample revealed irregular surface morphology with particle sizes in the 10–50 μm range. The strongest PL excitation peak was observed at 396 nm. The emission spectra indicated that this phosphor can be effectively excited by the 396 nm wavelength. Upon 396 nm excitation, the emission spectrum showed characteristics peaks located at 592 nm and 615 nm. These intense orange‐red emission peaks were obtained due to f→f transitions of Eu3+ ions. The emission peak at 592 nm is referred to as the magnetic dipole 5D07F1 transition and the emission peak at 615 nm corresponded to the electric dipole 5D07F2 transition of Eu3+. The Commission Internationale de l’Eclairage (CIE) coordinates of the Ba2Mg(PO4)2:Eu3+ phosphor were found to be (0.586, 0.412) for wavelength 592 nm and (0.680, 0.319) for wavelength 615 nm situated at the edge of the CIE diagram, indicating high colour purity of phosphors. Due to the high emission intensity and a good excitation profile, Eu3+‐doped Ba2Mg(PO4)2 phosphor may be a promising orange‐red phosphor candidate for solid‐state lighting applications.  相似文献   

9.
CaF2:Eu2+ is a well known phosphor having efficient excitation in the near ultraviolet (NUV) range. Phosphors with NUV excitation are required in newly emerging applications such as photoluminescence liquid crystal displays (PLLCD), solid‐state lighting (SSL), and down‐conversion for solar cells. However, emission of CaF2:Eu2+ is around 424 nm. Eye sensitivity drops considerably at these wavelengths. It is thus not useful for display applications for which emission in one of the primary colours (blue – 450 nm, green – 540 nm or red – 610 nm) is required. Efforts were made to modify the Photoluminescence (PL) spectra of CaF2:Eu2+ to meet these requirements using co‐dopants. A Ca0.49Sr0.50Eu0.01F2 phosphor showing better colour coordinates and having an emission maximum around 440 nm was discovered during these studies. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

10.
K. N. Shinde  K. Park 《Luminescence》2013,28(5):793-796
A series of efficient Li3Al2(PO4)3:Eu2+ novel phosphors were synthesized by the facile combustion method. The effects of dopant on the luminescence behavior of Li3Al2(PO4)3 phosphor were also investigated. The phosphors were characterized by X‐ray diffraction, field emission scanning electron microscope and photoluminescence techniques. The result shows that all samples can be excited efficiently by near‐ultraviolet excitation under 310 nm. The emission was observed for Li3Al2(PO4)3:Eu2+ phosphor at 425 nm, which corresponded to the d → f transition. The concentration quenching of Eu2+ was observed in Li3Al2(PO4)3:Eu2+ when the Eu concentration was at 0.5 mol%. The prepared powders exhibited intense blue emission at the 425 nm owing to the Eu2+ ion by Hg‐free excitation at 310 nm (i.e., solid‐state lighting excitation). Consequently, the availability of such a phosphor will significantly help in the development of blue‐emitting solid‐state lighting applications. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

11.
A solid‐state reaction route‐based LiTi2 ? xEux(PO4)3 was phosphor synthesized for the first time to evaluate its luminescence performance by excitation, emission and lifetime (τ) measurements. The LiTi2 ? xEux(PO4)3 phosphor was excited at λexci. = 397 nm to give an intense orange–red (597 nm) emission attributed to the 5D07F1 magnetic dipole (ΔJ = ±1) transition and red (616 nm) emission (5D07F2), which is an electric dipole (ΔJ = ±2) transition of the Eu3+ ion. Beside this, excitation and emission spectra of host LiTi2(PO4)3 powder were also reported. The effect of Eu3+ concentration on luminescence characteristics was explained from emission and lifetime profiles. Concentration quenching in the LiTi2 ? xEux(PO4)3 phosphor was studied from the Dexter's model. Dipole–quadrupole interaction is found to be responsible for energy transfer among Eu3+ ions in the host lattice. The LiTi2 ? xEux(PO4)3 phosphor displayed a reddish‐orange colour realized from a CIE chromaticity diagram. We therefore suggest that this new phosphor could be used as an optical material of technological importance in the field of display devices. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

12.
A luminescent double perovskite phosphor Sr2YNbO6 doped with Eu3+ crystallized to the monoclinic phase and was synthesized successfully via a conventional high-temperature combustion method. The formation of the crystal structure, phase purity, and surface morphology were studied using X-ray diffraction patterns and scanning electron microscopy. The characteristic vibrations between the atoms of the functional groups present in phosphor were studied using Fourier transform infrared spectra analysis. The luminescence properties of the prepared phosphors were investigated in terms of photoluminescence (PL) and thermoluminescence (TL). PL excitation spectra exhibited charge transfer bands and the characteristic 4f6 transitions of Eu3+. A prominent PL emission was obtained for the phosphor doped with 4 mol% Eu3+ under the 396 nm excitation wavelength. PL emission quenching was observed for the higher doping concentrations due to a multipole–multipole interaction. A highly intense PL emission arose due to the hypersensitive 5D07F2 electric dipole transition of Eu3+ that dominated the emission spectra. The thermal stability of the phosphor was examined through temperature-dependent PL. The TL properties of the Sr2YNbO6 double perovskites irradiated with a 90Sr beta source at different doses were measured. The double perovskite phosphors under study showed a linear dose–response with increasing beta dose, ranging from 1 Gy to 10 Gy. Trapping parameters of the TL glow curves were determined using Chen's peak shape method and computerized glow curve deconvolution (CGCD). CGCD fitting of the TL glow curves revealed that it was consisted of three major peaks and followed second-order kinetics. The estimated activation energies were determined using different methods and were comparable and significant.  相似文献   

13.
Peng Du  Jae Su Yu 《Luminescence》2017,32(8):1504-1510
A series of Sm3+‐activated Sr3La(VO4)3 phosphors were synthesized by a facile sol‐gel method. X‐ray diffraction patterns and photoluminescence (PL)/cathodoluminescence (CL) spectra as well as PL decay curves were employed to characterize the obtained samples. Upon 402 nm light excitation, the characteristic emissions of Sm3+ ions corresponding to 4G5/26HJ transitions were observed in all the as‐prepared products. The PL emission intensity was increased with increase in Sm3+ ion concentration, while concentration quenching occurred when the doping concentration was over 4 mol%. The non‐radiative energy transfer mechanism for concentration quenching of Sm3+ ions was dominated by dipole–dipole interaction and the critical distance was around 21.59 Å. Furthermore, temperature‐dependent PL emission spectra revealed that the obtained phosphors possessed good thermal stability with an activation energy of 0.19 eV. In addition, the CL spectra of the samples were almost the same as the PL spectra, and the CL emission intensity showed a tendency to increase with increase in accelerating voltage and filament current. These results suggest that the Sm3+‐activated Sr3La(VO4)3 phosphors with good color coordinates, high color purity and superior thermal stability may be a potential candidate for applications in white light‐emitting diodes and field‐emission displays as red‐emitting phosphors.  相似文献   

14.
Ca2Al2O5:Eu3+, Ca2Al2O5:Dy3+ and Ca2Al2O5:Tb3+ phosphors were synthesized using a combustion synthesis method. The prepared phosphors were characterized by X‐ray powder diffraction for phase purity, by scanning electron microscopy for morphology, and by photoluminescence for emission and excitation measurements. The Ca2Al2O5:Eu3+ phosphors could be efficiently excited at 396 nm and showed red emission at 594 nm and 616 nm due to 5D0 → 7F1 and 5D0 → 7F2 transitions. Dy3+‐doped phosphors showed blue emission at 482 nm and yellow emission at 573 nm. Ca2Al2O5:Tb3+ phosphors showed emission at 545 nm when excited at 352 nm. Concentration quenching occurred in both Eu3+ and Dy3+phosphors at 0.5 mol%. Photoluminescence results suggested that the aluminate‐based phosphor could be a potential candidate for application in environmentally friendly based lighting technologies.  相似文献   

15.
A series of blue phosphors Ca1.98–xMxPO4Cl:0.02Eu2+ (M = Mg and Sr) with different values of x were synthesized using a high‐temperature solid‐state reaction. X‐Ray diffraction and photoluminescence measurements were used to study the phase structure and luminescence properties. Ca2PO4Cl:0.02Eu2+ exhibits a tunable emission intensity and color due to the incorporation of Sr2+ or Mg2+. The incorporation of Sr2+ reduces the luminescence intensity and results in a slight red shift in the emission band. The incorporation of Mg2+ results in enhanced emission and a clear blue shift in the emission band along with a tunable chromatic coordination. Under excitation at λ = 334 nm, the emission intensity of the Mg2+‐doped Ca2PO4Cl:0.02Eu2+ is found to be 250% that of Ca2PO4Cl:0.02Eu2+. The luminescence behaviors of the as‐synthesized phosphors are discussed according to the host crystal structure and site occupancy of Eu2+. The results indicate that Mg2+‐doped Ca2PO4Cl:Eu2+ is more applicable as a near‐UV‐convertible blue phosphor for white light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

16.
Dy3+ and Eu3+ activated Ca3Y2Si3O12 phosphors were synthesized by the solid‐state synthesis method. The phosphors were characterized by X‐ray diffraction (XRD), mechanoluminescence (ML), thermoluminescence (TL) and photoluminescence (PL) to determine structure and luminescence. For ML glow curves, only one peak was observed, as only one type of luminescence centre was formed during irradiation. The Ca3Y2Si3O12:Dy3+ TL glow curve showed a single peak at 151.55°C and the Ca3Y2Si3O12:Eu3+ TL glow curve peaked at 323°C with a small peak at 192°C, indicating that two types of traps were activated. The trapping parameters for both the samples were calculated using Chen's peak shape method. Dy3+‐activated Ca3Y2Si3O12 showed emission at 482 and 574 nm when excited by a 351 nm excitation wavelength, whereas the Eu3+‐activated Ca3Y2Si3O12 phosphor PL emission spectra showed emission peaks at 613 nm, 591 nm, 580 nm when excited at 395 nm wavelength. When excited at 466 nm, prominent emission peaks were observed at their respective positions with very slight shifts. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
Ca2MgSi2O7:Eu2+,Dy3+ phosphor was prepared by the solid‐state reaction method under a weak reducing atmosphere. The obtained phosphor was characterized using X‐ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy dispersive X‐ray spectroscopy (EDX) and Fourier transform infrared (FT‐IR) techniques. The phase structure of the Ca2MgSi2O7:Eu2+,Dy3+ phosphor was akermanite type, which is a member of the melilite group. The surface morphology of the sintered phosphor was not uniform and phosphors aggregated tightly. EDX and FT‐IR spectra confirm the elements present in the Ca2MgSi2O7:Eu2+,Dy3+ phosphor. Under UV excitation, a broadband emission spectrum was found. The emission spectra observed in the green region centered at 535 nm, which is due to the 4f–5d transition. The mechanoluminescence (ML) intensity of the prepared phosphor increased linearly with increases in the mechanical load. The ML spectra were similar to the photoluminescence (PL), which indicates that ML is emitted from the same emitting center of Eu2+ ions as PL. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

18.
Triple whitlockite‐type structure‐based red phosphors Ca8MgBi1?x(PO4)7:xEu3+ (x = 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80 and 1.00) were synthesized by a conventional solid‐state reaction route and characterized by their X‐ray crystal structures. The X‐ray diffraction (XRD) patterns, Fourier transform infrared spectra, morphologies, photoluminescence spectra, UV/Vis reflectance spectra, decay times and the International Commission on Illumination (CIE) chromaticity coordinates of Ca8MgBi1?x(PO4)7:xEu3+ were analyzed. Eu‐doped Ca8MgBi(PO4)7 phosphors exhibited strong red luminescence with peaks at 616 nm due to the 5D07 F2 electric dipole transition of Eu3+ ions after excitation at 396 nm. The UV/Vis spectra indicated that the band gap of Ca8MgBi0.30(PO4)7:0.70Eu3+ is larger than that of Ca8MgBi(PO4)7. The phosphor developed in this study has great potential as a red‐light‐emitting phosphor for UV light‐emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

19.
A series of Eu2+ activated SrCaP2O7 pyrophosphate phosphors were synthesized by the modified solid‐state reaction method. The X‐ray diffraction (XRD) and photoluminescence (PL) properties of these phosphors were investigated at room temperature. The excitation spectra indicate that these phosphors can be effectively excited by Hg‐free excitation. The emission spectra exhibit strong blue performance, which is due to the 4f65d1→4f7 transition of Eu2+. The Fourier transform infrared spectrum at room temperature was investigated and surface morphology has been studied by scanning electron microscope. The prepared phosphor exhibited intense blue emission at the 427 nm owing to Eu2+ ion by Hg‐free excitation at 330 nm, that is, solid‐state lighting excitation. Hence, the availability of such a phosphor will significantly help in the growth of blue‐emitting solid‐state lighting applications. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

20.
A series of Eu3+‐activated NaLi2PO4 novel phosphors was synthesized by the solid‐state reaction method. The X‐ray diffraction (XRD) and photoluminescence (PL) properties of these phosphors were investigated at room temperature. The excitation spectra indicate that these phosphors can be effectively excited by near‐UV (370–410 nm) light. The emission spectra exhibit strong reddish‐orange performance, which is due to the 5D07FJ transitions of Eu3+ ions. The orange emission from transition 5D07F1 is dominant over that of 5D07F2. The concentration quenching of Eu3+ was observed in NaLi2PO4:Eu3+ when the Eu concentration was at 1 mol%. The impact of doping Eu3+ and photoluminescence properties were investigated and we propose a feasible interpretation. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

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