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1.
Eu 2+-doped bromophosphateapatite Sr 5(PO 4) 3Br phosphors were synthesized by the conventional high-temperature solid-state reaction. The crystal structure and luminescence properties of the phosphors, as well as their thermal stability and CIE chromaticity coordinates were systematically investigated. Photoluminescence spectra of Sr 5(PO 4) 3Br:Eu 2+ exhibit a single blue emission at 450 nm under the excitation of 345 nm, which is ascribed to the 4f–5d transition of Eu 2+. The phosphor shows very good thermal stability. The CIE color coordinates are very close to those of BaMgAl 10O 17:Eu 2+ (BAM). All the properties indicate that the blue-emitting Sr 5(PO 4) 3Br:Eu 2+ phosphor has potential application in white LEDs. 相似文献
2.
The hardystonite phosphors of Eu 2+ activated M 2ZnSi 2O 7 (M=Sr, Ba) were synthesized by combustion-assisted method. They were systematically characterized by photoluminescence excitation and emission spectra. The emission spectra of these two phosphors showed that the main emission peaks are at 475 and 503 nm due to 4f 65d 1→4f 7 transition of Eu 2+. Both phosphors could be efficiently excited in the wavelength range of 250-425 nm where the near ultraviolet light-emitting diode was well matched. The ( x, y) color coordinates were determined with the emission values ( x, y)=(0.41, 0.21) and (0.16, 0.45) for the M 2ZnSi 2O 7: Eu 2+ (M=Sr, Ba) phosphors. 相似文献
3.
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
4.
In order to improve the red luminescent properties,Sr 2 MgSi 2 O 7:Eu 2+,Dy 3+was selected as a blue persistent luminescent donor phosphor,while light conversion agent was utilized to tune the persistent luminescent spectra from blue to red.Composite red luminescent material Sr 2 MgSi 2 O 7:Eu 2+,Dy 3+/light conversion agent(SMED/LCA) was fabricated with light conversion agent and Sr 2 M... 相似文献
5.
Eu 2+ activated phosphors with the composition of Ca 013Sr 0.87Al 2Si 2O 8 were synthesized by combustion technique. The luminescent properties of these phosphors have been explored by analyzing their excitation and emission spectra with the help of photoluminescence (PL) spectroscopy. The phase-forming processes and presence of associated mode of vibrations of the phosphors were studied by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) respectively. Under ultra-violet (UV) excitation, Ca 013Sr 0.87Al 2Si 2O 8 phosphors had broad emission spectrum between 418 and 550 nm in the blue-green region of spectra corresponding to 4f 65d→4f 7 transition of Eu 2+ ion. The results show Ca 013Sr 0.87Al 2Si 2O 8: Eu 2+ is a promising host candidate for the phosphors and can be used for improving the efficiency and quality of phosphor-converted white light-emitting diodes. 相似文献
6.
In this investigation, Ba2CaZn2Si6O17:Eu2+ phosphor (BCZSOE) was successfully synthesized through the facile solid-state approach. Accordingly, spherical/commercial SiO2 particles were used through synthesizing BCZSOE phosphors. The crystal structure and microstructure of the produced phosphors were characterized using powder X-ray diffraction, field emission scanning electron microscope and high-resolution transmission electron microscope (HRTEM) instruments, while the luminescence properties of BCZSOE materials were analyzed by a photoluminescence (PL) analyzer. It was interestingly found that the use of spherical silica resulted in an uniform grain size distribution of BCZSOE phosphor in the range of 120–180 nm. In addition, the HRTEM images showed that the soaking time within the solid-state procedure was one of the most important parameters for the successful synthesis of BCZSOE compound. The luminescence emission spectra revealed that the use of silica spheres gave rise to the enhanced emission intensity than that of commercial silica particles. In addition, it was concluded that the emission bands at the wavelengths of 447 and 505 nm were due to the substitution of Ca2+ and Ba2+ by Eu2+ ions, respectively. 相似文献
7.
Sr2SiO4:xEu^2+ phosphors were synthesized through the solid-state reaction technique. The crystal phase of Sr2SiO4:xEu^2+ phosphor manipulated by Eu^2+ concentration was studied. The phase transited from β to α' in Sr2SiO4:xEu^2+ phosphor with increasing europium concentration. The single β phase was formed as x≤005 and changed α' phase when x〉0.01. The emission spectrum of the β-Sr2SiO4:Eu^2+ phosphor consisted of a green-yellow broadband peaking at around 540 nm and a blue band at 470 nm under near ultraviolet excitation. The white LEDs by combining near ultraviolet chips with β-Sr2SiO4:Eu^2+ phosphors were fabricated. The luminous efficiency (15.7lm/W) was higher than α'-Sr2SiO4:Eu^2+ phosphor white LED. 相似文献
8.
The BaGd_(2-2 x)Eu_(2 x)O_4(BG, x = 0.01-0.09) phosphors were successfully synthesized via the sol-gel method,and BaY_(2-2 y)Eu_(2 y)O_4(BY, y = 0.005-0.07) phosphors were included for comparison. The pure phase BG phosphors with the ordered CaFe_2 O_4-type structure are obtained by annealing at 1300℃ for5 h. The phosphors with uniform particle size of 120 nm and good dispersion display typical Eu~(3+)emission with the strongest peak at 613 nm(~5 D_0→~7 F_2 transition of Eu3+) under optimal excitation band at 262 nm(CTB band). The presence of Gd~(3+) excitation bands on the PLE spectra monitoring the Eu3+emission directly proves an evidence of Gd~(3+)-Eu~(3+) energy transfer. Owing to the concentration quenching, the optimum content of Eu3+ addition is 5 at%(x = 0.05), and the quenching mechanism is determined to be the exchange reaction between Eu3+. All the BG samples have similar color coordinates and temperature of(0.64 ± 0.02, 0.36 ± 0.01) and 2000 ± 100 K,respectively. The lifetime value of BaGd_(1.9)Eu_(0.1)O_4 for 613 nm is fitted to be 2.19 ± 0.01 ms, and the Eu~(3+) concentration does not change the lifetime significantly. Owing to the Gd~(3+)-Eu~(3+) energy transfer, the luminescent intensity of the BaGd_(1.9)Eu_(0.1)O_4 phosphor is better than BY system. The BG system served as a new type of phosphor is expected to be widely used in lighting and display areas. 相似文献
9.
The Zn_(1-x)Al_2 O_4:xEu~(2+) phosphor powders were synthesized by the solid-state reaction method.The synthesis temperature for ZnAl_2 O_4 was optimized,whereas the phase structure,TEM images,photoluminescence(PL) properties,the concentration quenching mechanism,the fluorescence decay curves,as well as the CIE chromaticity coordinates of the samples were investigated in details.Under the excitation at 379 nm,the phosphor exhibits an asymmetric broad-band green emission with a peak at 532 nm,which is ascribed to the 5 d-4 f transition of Eu2+.When the doping concentration of Eu2+ ions is 0.01,the luminescence intensity of the sample reaches the maximum value.It is further proved that the exchange interaction results in the concentration quenching of Eu2+ in the Zn_(1-x)Al_2 O_4:xEu~(2+) phosphor powders.The thermal quenching property of ZnAl_2 O_4:Eu~(2+)phosphor was investigated and the quantum efficiency(QE) values of the selected Zn_(0.99)Al_2 O_4:0.01 Eu~(2+) phosphor was measured and determined as 54.85%.The lifetime of the optimized sample Zn_(0.99)Al_2 O_4:0.01 Eu~(2+) is 3.0852 μs and the CIE coordinate of the sample was calculated as(0.3323,0.5538) with high-color-purity green emission.All properties indicate that the green-emitting ZnAl_2 O_4:Eu~(2+) phosphor powder has potential application in white LEDs. 相似文献
10.
Cyan-emitting Ca 9NaGd 2/3(PO 4) 7:Eu 2+phosphors were synthesized via high temperature solid-state route.X-ray powder diffraction(XRD)and scanning electron microscopy(SEM)were used to verify the phase and morphology of the Ca 9NaGd 2/3(PO 4) 7:Eu 2+(CNGP:Eu 2+)phosphors.The as-obtained phosphor exhibits a broad excitation band of 250-420 nm,which is near the ultraviolet region.An intense asymmetric cyan emission at 496 nm corresponds to the 5 d-4 f transition of Eu 2+.The multiplesite luminescent properties of Eu 2+ions in CNGP benefit from versatile structure ofβ-Ca3(PO4)2 compounds.The effective energy transfer distance is 5.46 nm(through the spectral overlap calculation),validating that the resonant energy migration type is via dipole-dipole interaction mechanism.Compared to the initial one at room temperature,the luminescent intensity of CNGP:Eu 2+phosphor can maintain 77%as it is heated up to 420 K.A white light-emitting diode(WLED)with excellent luminesce nt properties was successfully fabricated.Moreover,the CIE chromaticity coordinates of fabricated WLED driven by changing current just change slightly. 相似文献
11.
Eu 2+ activated BaSi 2O 2N 2 oxynitride bluish-green phosphor was synthesized adopting conventional high-temperature solid-state reaction method, in which BaF 2, Na 2CO 3 and NH 4Cl were used as the fluxes. The phase formation, size distribution and microscopic morphology were characterized to investigate the influence of adding fluxes on photoluminescence properties. The results indicate that with the addition of BaF 2 flux, the particle morphology becomes regular and size distribution narrows and the phase purity of BaSi 2O 2N 2:Eu 2+ phosphor can be improved effectively. The photoluminescence intensity of BaSi 2O 2N 2:Eu 2+ phosphor with BaF 2 as flux gets enhanced obviously, which is much higher than that of Na 2CO 3, NH 4Cl and without flux. The optimum content of BaF 2 flux is 4 wt%, and the maximum photoluminescence intensity of the BaSi 2O 2N 2:Eu 2+ phosphor prepared with BaF 2 flux rises to 141%, meanwhile, the phosphors with BaF 2 flux exhibits low thermal quenching. The results indicate that the BaSi 2O 2N 2:Eu 2+ is sort of promising bluish-green phosphor for application in full-spectra LED. 相似文献
12.
A single-phase full-color emitting phosphor Sr 2Ca 2La(PO 4) 3O:Eu 2+,Tb 3+,Mn 2+ was synthesized by the high temperature solid-state method. The phase formation, luminescence properties, thermal stability, and energy transfer from Eu 2+ to Tb 3+ and Eu 2+ to Mn 2+ in Sr 2Ca 2La(PO 4) 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 Eu 2+ to Tb 3+ or Mn 2+ ions by varying the ratio of Eu 2+/Tb 3+ or Eu 2+/Mn 2+ ions. White light was obtained with chromaticity coordinates of (0.3558, 0.3500) in the Sr 2Ca 2La(PO 4) 3O:0.04Eu 2+,0.08Tb 3+,0.40Mn 2+ phosphor, suggesting their potential applications in white light emitting diodes. 相似文献
13.
Ba 0.9-ySr yAl 12O 19:Eu 0.1 phosphors were prepared by sol-gel technique, the crystalline structures of samples characterized by XRD, and the luminescence properties were investigated. The influence of crystallographic positions on the luminescent properties of Sr 2+-doped BaAl 12O 19:Eu was investigated in detail. The results indicated that the crystal lattice of BaAl 12O 19:Eu was not influenced by the Sr 2+ and doping Sr 2+ in BaAl 12O 19:Eu enhanced the luminescent properties of the phosphors at the proper concentration of Sr 2+. With the increasing of concentration of Sr 2+ doped in BaAl 12O 19:Eu, the relative luminescent intensity of Ba 0.9-ySr yAl 12O 19:Eu 0.1 strengthened and blue-shifted. 相似文献
14.
The Sr 2CeO 4:Ln 3+ (Ln = Eu, Dy) fine phosphor particles were prepared by a facile wet chemical approach, in which the consecutive hydrothermal-combustion reaction was performed. The doping of Ln 3+ into Sr 2CeO 4 has little influence on the structure of host, and the as-prepared samples display well-crystallized spherical or elliptical shape with an average particle size at about 100–200 nm. For Eu 3+ ions-doped Sr 2CeO 4, with the increase of Eu 3+-doping concentration, the blue light emission band with the maximum at 468 nm originating from a Ce 4+ → O 2− charge transfer of the host decreases obviously and the characteristic red light emission of Eu 3+ ( 5D 0→ 7F 2 transition at 618 nm) is enhanced gradually. Simultaneously, the fluorescent lifetime of the broadband emission of Sr 2CeO 4 decreases with the doping of Eu 3+, indicating an efficient energy transfer from the host to the doping Eu 3+ ions. The energy transfer efficiency from the host to Eu 3+ was investigated in detail, and the emitting color of Sr 2CeO 4:Eu 3+ can be easily tuned from blue to red by varying the doping concentration of Eu 3+ ions. Moreover, the luminescence of Dy 3+-doped Sr 2CeO 4 was also studied. Similar energy transfer phenomenon can be observed, and the incorporation of Dy 3+ into Sr 2CeO 4 host leads to the characteristic emission of 4F 9/2 → 6H 15/2 (488 nm, blue light) and 4F 9/2 → 6H 13/2 (574 nm, yellow light) of Dy 3+. The Sr 2CeO 4:Ln 3+ fine particles with tunable luminescence are quite beneficial for its potential applications in the optoelectronic fields. 相似文献
15.
Red phosphor,with longer wavelength,is highly desirable for full-spectrum WLEDs.Targeted deep red phosphors(Sr,Gd)Li(AI,Mg) 3N 4:Eu 2+ were designed from the initial model of SrLiAl 3N 4:Eu 2+ by structural modification.The correlations among structural evolution,crystal-field environment,and luminescence properties were elucidated.Replacing Sr 2+ with Gd 3+in(Sr,Gd)LiAl 3N 4:Eu 2+ leads... 相似文献
16.
The luminescent properties of Sr2.97MgSi2O8:Eu2+0.01 phosphors were investigated with different Ln3+0.02(Ln3+:Dy3+,Er3+,Ho3+) co-dopants. The co-dopants had no influence on both the structure of the lattice and the position of the emission peak. However, the afterglow properties of samples were enhanced with different co-dopants. The afterglow duration of the Dy3+ co-doped sample was longer than that of the others. Furthermore, the co-doping samples had stronger thermoluminescence (TL) intensity and therefore longer afterglow duration. At last, the self-reduction of Eu3+→Eu2+ was observed in an silicate compound of Sr3-xMgSi2O8:xEu phosphor in air condition. This is the first time to show a blue long afterglow phosphor synthesized avoiding reducing atmosphere. 相似文献
17.
NaBaPO 4:Eu 2+,Er 3+ phosphors and Ag nano-particles (NPs) were prepared by the solid-state reaction and chemical reduction method, respectively. The fluorescence spectra and decay curves demonstrate the effective energy transfer from Eu 2+ to Er 3+ and the existence of three-photon quantum-cutting through two-step cross-relaxation of Er 3+. The quantum-cutting emission is peaked at 1534 nm with a broad excitation band centered at 352 nm. Plasmon-enhanced quantum-cutting of NaBaPO 4:Eu 2+,Er 3+ phosphors was realized by decorating Ag NPs. The largest enhancement factor is 1.395. It is hopeful to improve the photovoltaic conversion efficiency of Ge solar cells by using this phosphor. 相似文献
18.
In this work,through a facile method of low-temperature(only 350 ℃) self-reduction,1D nano-sized M 2B 5O 9CI:Eu 2+(M=Sr,Ca) blue phosphors with highly efficient performance can be obtained.The crystal structure,morphology and photoluminescence(PL) properties including thermal stability of M 2B 5O 9CI:Eu 2+(M=Sr,Ca) phosphors were investigated.The M 2B 5O 9CI:Eu 2+(M=Sr,Ca) phos... 相似文献
19.
The (Ba1- x, Srx ) 2 SiO4 : EU^2+ green-emitting phosphors were synthesized by conventional solid-state reaction in a CO-reductive atmosphere, and their luminescent properties were investigated. The XRD data show that the Ba/Sr ratio not only affects the lattice parameters, but also influences the emission peak. The excitation spectra indicate that this phosphor can be effectively excited by UV light from 370 to 470 nm. The emission band is due to the 4f^65d^1→4f^7 transition of the Eu^2+ ion. With an increase in x, the emission band shifts to longer wavelength and the reason was discussed. The emission spectra exhibit a satisfactory green performance under different excitation wavelength(380,398,412,420,460 nm). (Ba1- x, Srx ) 2 SiO4 : EU^2+ is a promising phosphor for green white-lighting-emission diode by ultraviolet chip. 相似文献
20.
A blue phosphor Ca 2PO 4Cl:Eu 2+ (CAP:Eu 2+) was synthesized by solid state reaction. The Ca 2PO 4Cl:Eu 2+ exhibited high quantum efficiency and excellent thermal stability. The luminescent intensity of Ca 2PO 4Cl:Eu 2+ was found to be 128% under excitation at 380 nm, 149% under 400 nm, and 247% under 420 nm as high as that of BaMgAl 10O 17:Eu 2+. The optimal doping concentration was observed to 11 mol.% of CAP:Eu 2+. The energy transfer between Eu 2+ ions in CAP were occurred via electric multipolar interaction, and the critical transfer distance was estimated to be 1.26 nm. A mixture of blue-emitting Ca 2PO 4Cl:Eu 2+, green-emitting (Ba,Sr) 2SiO 4:Eu 2+ and red-emitting CaAlSiN 3:Eu 2+ phosphors were selected in conjunction with 400 nm chip to fabricate white LED devices. The average color-rendering index Ra and correlated color temperature ( Tc) of the white LEDs were found to be 93.4 and 4590 K, respectively. The results indicated that it was a promising candidate as a blue-emitting phosphor for the near-UV white light-emitting diodes. 相似文献
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