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1.
The powder samples of Ca9Sc(PO4)7:xDy^(3+)white emitting phosphors were prepared via a solid state reaction technique.The Ca9Sc(PO4)7:Dy3+samples were researched by using the GSAS Rietveld refinement and X-ray diffraction(XRD) methods,and SEM images and elemental maps were recorded.Under 350 nm excitatio n,the emission spectra of Ca9Sc(PO4)7:xDy3+samples have two obvious peaks and one weak peak at 484,572 and660 nm,corresponding to the characteristic electron transitions of(4F9/26H15/2,blue),(4F9/26H13/2,yellow) and(4F9/2→ 6 H11/2,red),respectively.The concentration quenching effect,decay lifetime and thermal quenching of the as-synthesized Ca9Sc(PO4)7:Dy3+samples were researched systematically.The Ca9Sc(PO4)7:0.02 Dy3+phosphor possesses a good thermal stability,of which the emission intensity at 423 K can maintain 79% of the initial value(273 K).In addition,through the study of the chro maticity coordinates of the Ca9Sc(PO4)7:0.02 Dy3+phosphor,it is found that it is located in the white region,and the Commission Internationalede L’Eclairage(CIE) chromaticity coordinates are(0.339,0.389),The above results show that Ca9Sc(PO4)7:xDy3+phosphors can be excellent candidate material for applications in NUV-excited white LEDs.  相似文献   

2.
White-light-emitting phosphors based on phosphate host matrix, KSrPO_4 doped with Dy~(3+), were prepared by solid state reaction and their VUV luminescent properties were firstly investigated. The excitation band peaking at 125-153 nm corresponding to the absorption of PO_4~(3-) group exhibits very strong absorption. The phosphors emit warm-white luminescence under vacuum ultraviolet excitation of 147 nm, which consists of three main emission peaks located at 475, 570 and 662 nm, respectively.According to the luminescence and color chromaticity of the optimal sample KSrPO_4:1 mol%Dy~(3+),1.3 mol%Li~+, it can be a potential candidate for mercury-free fluorescent lamps.  相似文献   

3.
Nanosized 1 at% Sm3+doped Y2O3 powders were prepared by an ultrasound assisted sol-gel method.Y2O3:Sm3+powders crystallize in Y2 O3 pure cubic phase and XRD analysis shows that the as-used agitation protocol affects strongly the crystallite’s shape and mean size.The recorded emission spectra under λem=600 nm exhibit two absorption bands;the first one is assigned to O2-→Sm3+cha...  相似文献   

4.
Tri-doped Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors were prepared by a high-temperature solid state method.Under UV light excitation,Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+)samples exhibit a broad band ranging from 320 to 500 nm.At 77 K,the emission spectra of Ca_9 LiY_(2/3)(PO_4)7:Ce~(3+)samples present two obvious emission peaks,indicating that Ce~(3+)ions occupy two different kinds of lattice sites(Ca(1/2) and Ca(3)),As a good sensitizer for Tb~(3+),Ce~(3+)ions in Ca_9 LiY_(2/3)(PO_4)_7 lattice can effectively transfer part of energy to Tb~(3+),and the energy trans fer mechanism is determined to be dipole-dipole interaction.Consequently,the emitting color for Ce~(3+) and Tb~(3+) co-doped Ca_9 LiY_(2/3)(PO_4)_7 samples can be tuned from bluish violet to green.In order to further enlarge the emission gamut,Mn~(2+)ions as red emission components were added,forming tri-doped single-phase Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors.The Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors exhibit tunable emission properties through controlling the relative doping concentration of Ce~(3+),Tb~(3+)and Mn~(2+).Especially,Ca_9 LiY_(2/3)(PO_4)_7:0.09 Ce~(3+),0.12 Tb~(3+),0.30 Mn~(2+)can emit warm white light.The sample shows good thermal stability.At 150℃,the emission intensity for Ce~(3+)(360 nm),Tb~(3+)(545 nm) and Mn~(2+)(655 nm) decreases to 63%,69%,and 72% of its initial intensity,respectively.Moreover,the sample obtains good stability after 10 cycles between room temperature and150℃.  相似文献   

5.
This work presents the synthesis of Y2O3:Eu3+,xCa2+ (x = 0 mol%, 1 mol%, 3 mol%, 5 mol%, 7 mol%, 9 mol%, 11 mol%) nanophosphors with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic, display, and lighting applications. The X-ray diffraction (XRD) patterns of the proposed nanophosphor reveal its structural properties and crystalline nature. The transmission electron microscope (TEM) results confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca2+. Fourier transform infrared spectroscopy (FTIR) and Raman vibrations also confirm the presence of Y–O vibration and subsequently explain the crystalline nature, structural properties, and purity of the samples. All the synthesized nanophosphors samples emit intense red emission at 613 nm (5D07F2) under excitation with 235, 394 and 466 nm wavelengths of Eu3+ ions. The photoluminescence (PL) emission spectra excited with 235 nm illustrate the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhanced by 394 nm wavelength, respectively. The emission intensity of Y2O3:Eu3+,xCa2+ (5 mol%) is increased 8-fold as compared to Eu:Y2O3. Doping with Ca2+ ions enhances the emission intensity of Eu:Y2O3 nanophosphors due to an increase in energy transfer in Ca2+→Eu3+ through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria matrix. It is also observed that the optical band gap and the lifetime of the 5D0 level of Eu3+ ions in Y2O3:Eu3+,xCa2+ nanophosphor sample gets changed with a doping concentration of Ca2+ ions. Nanophosphor also reveals high thermal stability and quantum yield as estimating activation energy of 0.25 eV and 81%, respectively. CIE, CCT, and color purity values (>98%) show an improved red-emitting nanophosphor in the warm region of light, which makes this material superior with a specific potential application for UV-based white LEDs with security ink, display devices, and various other optoelectronics devices.  相似文献   

6.
A series of Eu2+/Dy3+ single doped and co-doped Na3Sc2(PO4)3 phosphors were synthesized by the high-temperature solid-state method, and their phase, morphology, and luminescence properties were characterized. Under the excitation of 370 nm, the Na3Sc2(PO4)3:Eu2+,Dy3+ phosphor can emit white light whose spectrum is composed of a broad emission band centered at 460 nm and the other three peaks at 483, 577, and 672 nm, respectively. There is energy transfer from Eu2+ to Dy3+ ion in Na3Sc2(PO4)3:Eu2+,Dy3+ phosphor due to the good overlap between the emission spectrum of Na3Sc2(PO4)3:Eu2+ and the excitation spectrum of Na3Sc2(PO4)3:Dy3+, which is further confirmed by the fluorescence lifetime decrease of Eu2+ ion with the increase of Dy3+ concentration. The process of energy transfer is via dipole–quadruple interaction which is confirmed by applying Dexter's theory. By increasing the Dy3+ concentration, the color coordinates of the Na3Sc2(PO4)3:0.01Eu2+,xDy3+ phosphors can be adjusted from blue to white, and then to yellow. The optimized concentration of Dy3+ ions is 4.0 mol%, beyond which the concentration quenching will take place. The Na3Sc2(PO4)3:Eu2+,Dy3+ phosphor shows fairly good resistance to thermal quenching behavior, of which the emission intensity at 423 K can maintain 90.3% of the initial value (298 K). These results suggest that the Na3Sc2(PO4)3:0.01Eu2+,xDy3+ phosphors have potential applications as the color-tunable or a single-phase white emitting phosphor in white LEDs.  相似文献   

7.
Due to the characteristic emission of phosphors,phosphor-converted LEDs have been employed to provide the requisite light sources for indoor plant growth in the optical agricultural industry.Herein,we prepared a series of Mn2+co-doped NaSrB5 O9:Dy3+phosphors via a solid-state reaction method.These phosphors have significant three-band emissions at 467 nm(blue region),606 nm(orange region),and765 nm(far-red region),ascribed to the4F9/2-6H15/2and 4 F9/2-6 H13/2 transitions of the Dy3+ions and the4T1g(G)-6A1g(S)spin-forbidden transition of the Mn2+ions,respectively,when excited by light of 376 nm(near-UV region).The co-dopant in the host material facilitates tunable photoluminescence(PL)due to energy transfer from the Dy3+ions to the Mn2+ions.The three emission peaks from the prepared phosphors well match with the absorption spectra of the photosynthesis pigments of plants,chlorophyll and phytochrome,which can absorb blue(400-500 nm),orange-red(550-700 nm),and infrared(IR)radiation,indicating that these phosphors have potential applications in the fabrication of plant-growth LEDs.Prior to the PL studies,the structure of the phosphors was determined by X-ray diffraction,refined by Rietveld method and chemically quantified by X-ray photoelectron spectroscopy.  相似文献   

8.
A single-phase full-color emitting phosphor Sr2Ca2La(PO4)3O:Eu2+,Tb3+,Mn2+ was synthesized by the high temperature solid-state method. The phase formation, luminescence properties, thermal stability, and energy transfer from Eu2+ to Tb3+ and Eu2+ to Mn2+ in Sr2Ca2La(PO4)3O were investigated in details. Tunable emission color from blue to blueish green or orange can be observed under 365 nm near-ultraviolet excitation based on the energy transfer from Eu2+ to Tb3+ or Mn2+ ions by varying the ratio of Eu2+/Tb3+ or Eu2+/Mn2+ ions. White light was obtained with chromaticity coordinates of (0.3558, 0.3500) in the Sr2Ca2La(PO4)3O:0.04Eu2+,0.08Tb3+,0.40Mn2+ phosphor, suggesting their potential applications in white light emitting diodes.  相似文献   

9.
A novel white-light emitting single-phase phosphor La3Si6N11:Dy3+, exhibiting two emission peaks centering at 475 and 575 nm, was prepared via conventional solid-state reactions. The structure and morphology of La3Si6N11:Dy3+/Tb3+ were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The emission colors can be tuned from white to yellow-green through increasing the Tb3+ concentration in La3Si6N11:Dy3+,Tb3+. The mechanism of energy transfer (ET) from Dy3+ to Tb3+ is confirmed according to the excitation, emission spectra and decay lifetimes curve. The temperature-dependent luminescence measurements of La2.83Si6N11:0.1Dy3+,0.07Tb3+ were also performed, and a good thermal stability is shown, suggesting superior properties for the application as white light-emitting diodes (w-LEDs) phosphor.  相似文献   

10.
A novel orange-red emitting Ba3Y4O9:Sm3+ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra, fluorescence decay and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties. The results show that the excitation spectrum includes a series of linear peaks at 350, 367, 382, 410, 424, 445, 470 and 495 nm, respectively. Under 410 nm excitation, the emission peaks were located at 574 nm (4G5/26H5/2), 608 nm (4G5/26H7/2), 659 nm (4G5/26H9/2) and 722 nm (4G5/26H11/2), respectively. The concentration quenching occurs when x equals 0.08 for Ba3Y4–xO9:xSm3+ phosphor and its mechanism is ascribed to the dipole–dipole interaction. The chromaticity coordinates of Ba3Y3.92O9:0.08Sm3+ phosphor are in the orange-red region. The temperature-dependent study shows that this phosphor has excellent luminescence thermal-stability. And the luminescence intensity of Ba3Y3.92O9:0.08Sm3+ phosphor at 473 K only declines by about 25.75% of its initial intensity. The experimental data indicate that Ba3Y4O9:Sm3+ phosphor may be promising as an orange-red emitting phosphor for white light emitting diodes.  相似文献   

11.
Mn2+doped LuAG phosphors with different contents of Si4+ions were synthesized via the solid-state reaction method and the effects of Si4+doping on the crystal structure and luminescence properties of phosphors were studied.XRD patterns of all phosphors exhibit a pure phase but with different extents of deviations.Owing to the 4 T1→6 A1 transition of Mn2+,the LuAG:Mn2+,Si4+phosphors exhibit a broad emission band with an emission peak at 582 nm.Moreover,the introduction of Si4+not only improves the emission intensity but also induces a red-shift with the emission peak from 582 to 612 nm and the spectra broadening with the full width at half maximum value from 64 to 74 nm,which results from the decrease of bond length between O2-anions and Mn2+cations and the re-absorption of Mn2+-Mn2+pairs.Suitable content of Si4+replacement can weaken thermal quenching of Mn2+.Thus,via regulating the content of Si,the Mn2+,Si4+co-doped LuAG phosphor with low correlated color temperature is a candidate for warm wLEDs.  相似文献   

12.
A series of Eu~(2+),Tb~(3+)-codoped Sr_3 Y(PO_4)_3(SYP) green phosphors were synthesized by hightemperature solid-state reaction. Several techniques, such as X-ray diffraction, UV-vis spectrum,and photoluminescence spectrum, were used to investigate the obtained phosphors. The present study investigates in detail photoluminescence excitation and emission properties, energy transfer between the two dopants, and effects of doping ions on optical band gap. SYP:0.05 Eu2+ phosphor shows an intense and broad excitation band ranging from 220 to 400 nm and exhibits a bright green emission band with CIE chromaticity coordinates(0.189, 0.359) under 350 nm excitation. Green emission of SYP:0.03 Tb3+ is intensified by codoping with Eu~(2+), and energy transfer mechanism between them is demonstrated to be a dipole-dipole interaction. Upon 350 nm excitation, SYP:Eu~(2+),Tb~(3+) phosphors exhibits two dominating bands peaking at 466 and 545 nm, which are assigned to 4 f~65 d~1→4 f~7 transition of Eu~(2+) ions and ~5 D_4→~7 F_5 transition of Tb~(3+) ions, respectively. Optimal doping concentrations of Eu~(2+) and Tb~(3+) in the SYP host are 5 mol% and 15 mol%, respectively. Results indicate that SYP:Eu~(2+),Tb~(3+) phosphors are potentially used as green-emitting phosphors for white light-emitting diodes.  相似文献   

13.
In order to obtain near-infrared phosphor pumped by blue chip with high luminous efficiency, a novel near-infrared phosphor Ce3+/Er3+ doped La3Si6N11 was designed and firstly prepared via conventional solid-state reactions. The structure and morphology of Ce3+/Er3+ doped La3Si6N11 were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Compared with Er3+ doped La3Si6N11, the emission intensity of the Ce3+, Er3+ co-doped phosphor can be increased more than 5 times. Meanwhile, the mechanism of energy transfer from Ce3+ to Er3+ is confirmed according to the excitation, emission spectra and decay lifetimes curve. Above results suggest that La3Si6N11:Ce3+,Er3+ is a promising near-infrared phosphor for blue pumped LEDs (light-emitting diodes).  相似文献   

14.
A series of single Ce3+ doped and Ce3+ and Tb3+ co-doped Na2BaCa(PO4)2 (NBCP) phosphors was synthesized by conventional solid-stated reaction method. The crystal structure, luminescence properties, thermal stability and energy transfer were carefully investigated. Ce3+ is inferred to substitute the Ba2+ site in NBCP lattice. The color-tunable emission from blue to green is observed by adjusting Tb3+ concentration among NBCP:0.03Ce3+,yTb3+ phosphors. The energy transfer behavior from Ce3+ to Tb3+ ions is both illustrated by co-doped PL spectra and decay curves. The energy transfer efficiency is as high as 91.5%. The mechanism of energy transfer is resonance type of dipole-dipole transition. In this work, the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150 °C. The Ce3+ and Tb3+ co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields.  相似文献   

15.
A series of new double perovskite La2–xEuxCaSnO6 (0 ≤ x ≤ 0.8) red phosphors were synthesized by traditional solid-state reaction. The phase, microstructure, photoluminescence (PL) properties, quantum efficiency, and thermal stability of the phosphors were investigated. La2CaSnO6 matrix has a monoclinic double perovskite structure with space group P21/n. Under near-ultraviolet (UV) light at 395 nm, La2–xEuxCaSnO6 phosphors exhibit the most typical red emission peak at 614 nm, which corresponds to 5D07F2 electric dipole transition of Eu3+. The optimum Eu3+ doping content is attained at x = 0.5, and the La1.5Eu0.5CaSnO6 phosphor shows a moderate quantum efficiency (32.3%) and high color purity (92.2%). Besides, the temperature-dependent spectrum of the phosphor was studied. The emission intensity of Eu3+ at 423 K decreases to 70.94% of the initial intensity at 303 K, and the activation energy ΔE is estimated to be 0.232 eV, suggesting that the phosphors possess good thermal stability. The fabricated w-LED based on the phosphors has higher Ra (89), lower CCT (4539K), and better chromaticity coordinates (0.371, 0.428). These results prove that the Eu3+-doped La2CaSnO6 red phosphor has great potential applications in w-LEDs.  相似文献   

16.
In this work, CaF_2:Ln~(3+)(Ln:Er,Er/Yb)/Nafion composite films were prepared using Nafion as modifications and matrices by dripping method. The composite films were characterized by Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD) and scanning electron microscopy(SEM). Composite films are transparent and CaF_2:Ln~(3+)(Ln:Er,Er/Yb) nanoparticles are well dispersed in Nafion films.The thicknesses of CaF_2:Er~(3+)/Nafion and CaF_2:Er~(3+),Yb~(3+)/Nafion composite film are about 77 and 73 μm,respectively. The nanoparticles in composite film possess cubic phase. CaF_2:Er~(3+),Yb~(3+)/Nafion composite film has stronger characteristic emission of Er~(3+) around 1530 nm with full width at half-maximum(FWHM) of 73 nm and longer luminescence lifetimes of 22.04 μs(25.03%) and 100.77 μs(74.97%).  相似文献   

17.
A series of Ca_(10)Na(PO_4)_7:Ce~(3+)/Tb~(3+)/Mn~(2+)(CNPO:Ce~(3+)/Tb~(3+)/Mn~(2+)) phosphors with high brightness were synthesized by high-temperature solid-state method. X-ray diffraction(XRD), scanning electron microscopy(SEM), diffuse reflectance spectra(DRS), photo luminescence(PL) spectra, luminescence decay curves and thermally stability were performed to characterize the as-prepared samples. For Ce~(3+)-doped samples, an intense and broad band emission is present under 265 nm excitation. When Ce~(3+) and Tb~(3+)are codoped, energy transfer(ET) process from Ce3+ to Tb3+ is demonstrated with electric dipole-dipole interaction. The internal and external quantum efficiencies(QEs) of CNPO:0.15 Ce~(3+), 0.04 Tb~(3+), 0.005 Mn~(2+)are measured to 76.79% and 54.11% under 265 nm excitation and temperature-dependent PL intensity can remain 51.78% at 150 ℃ of its initial intensity at 25 ℃. It is indicated that single-phased white lightemitting CNPO:Ce~(3+)/Tb~(3+)/Mn~(2+) phosphor can serve as a promising phosphor for illumination devices.  相似文献   

18.
In this work,calcium niobium gallium garnet(Ca3 Nb1.6875Ga3.1875O12-CNGG) ceramic samples singledoped with Tb3+ and co-doped with Tb3+ and Yb3+ ions were sintered by the solid-state reaction method.The structural characterization of the samples was carried out by X-ray diffraction measurements.The optimal concentration of Tb3+ ions corresponding to the maximum luminescence in the green spectral range in CNGG:...  相似文献   

19.
In this work,tunable white up-conversion luminescence was achieved in the Yb3+,Er3+,Tm3+,Ho3+ codoped Na3La(VO4)2 phosphors under 980 nm excitation.The emissions of three primary colors are mainly attributed to the 2H11/2/4S3/24I15/2 transitions of Er3+,1G43H6 transition of Tm3+,and5...  相似文献   

20.
Energy transfer among the co-doped activators is an efficient route to achieve color-tunable emission in inorganic phosphors.Herein,photoluminescence tuning from blue to cyan has been achieved in the Lu_2MgAl_4 SiO_(12);Eu~(2+),Ce~(3+)phosphors by varying the Ce~(3+) concentration with a fixed Eu~(2+)content.With the further introduction of a Mn~(2+)-Si4+couple into the host lattice,the emission color can be tuned to red through the energy transfer of Eu~(2+)and Mn~(2+).The luminescence properties and the energy transfer mechanism were studied in detail.The energy transfer from Eu~(2+)to Ce~(3+)is certified as a dipolequadrupole interaction with the energy transfer efficiency of 41.4% and Eu~(2+)to Mn~(2+)belongs to a dipole-dipole interaction with the energy transfer efficiency of 94.3%.The results imply that this singlephased Lu_2MgAl4 SiO_(12):Eu~(2+),Ce~(3+),Mn~(2+)phosphor has a potential prospect for application in near-UV chip pumped white light emitting diodes.  相似文献   

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