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1.
《Ceramics International》2017,43(15):12044-12056
Perovskite type titanate phosphors Sr0.97−xDy0.03LixTi1−xNbxO3, Sr0.9−xDyxLi0.1Ti0.9Nb0.1O3 and Sr0.87−yDy0.03EuyLi0.1Ti0.9Nb0.1O3 were prepared by conventional solid state method. Herein, white light emission from Sr0.9−xDyxLi0.1Ti0.9Nb0.1O3 phosphors and the lowering of its color temperature through codoping with Eu3+ ions are reported. Raman measurements have shown that the incorporation of dopants alters the vibrational properties of these phosphors significantly, indicating the reduction of the local symmetry in the crystal lattice. The addition of LiNbO3 in SrTiO3:Dy3+ phosphor enhances the luminescence intensity and the yellow to blue ratio resulting in emission of high quality white light with color coordinates corresponding to that of standard white. Life time measurements and data fits of Sr0.9−xDyxLi0.1Ti0.9Nb0.1O3 phosphors revealed the biexponential behaviour of luminescence decay profiles. From Judd-Ofelt analysis it is found that the intensity parameter Ω2 increases with Dy3+ concentration and a quantum efficiency of 90.4% was obtained for optimum concentration. In the case of Dy3+ and Eu3+ codoped phosphors, the color coordinates are found to be sensitive to the Eu3+ concentration and the highest energy transfer efficiency of 92% was obtained for the phosphor doped with 10 mol% Eu3+. The emission color changes from cold white to reddish orange when the wavelength of excitation alters from 452 to 388 nm, since the energy transfer mechanism alone take place under 452 nm excitation and both direct absorption and the energy transfer mechanism occurs under 388 nm excitation.  相似文献   

2.
A series of Ca5(PO4)3F:Dy3+, Eu3+ phosphors was synthesized by a solid‐state reaction method. The XRD results show that all as‐prepared Ca5(PO4)3F:Dy3+, Eu3+ samples match well with the standard Ca5(PO4)3F structure and the doped Dy3+ and Eu3+ ions have no effect on the crystal structure. Under near‐ultraviolet excitation, Dy3+ doped Ca5(PO4)3F phosphor shows blue (486 nm) and yellow (579 nm) emissions, which correspond to 4F9/26H15/2 and 4F9/26H13/2 transitions respectively. Eu3+ co‐doped Ca5(PO4)3F:Dy3+ phosphor shows the additional red emission of Eu3+ at 631 nm, and an improved color rendering index. The chromaticity coordinates of Ca5(PO4)3F:Dy3+, Eu3+ phosphors also indicate the excellent warm white emission characteristics and low correlated color temperature. Overall, these results suggest that the Ca5(PO4)3F:Dy3+, Eu3+ phosphors have potential applications in warm white light‐emitting diodes as single‐component phosphor.  相似文献   

3.
《Ceramics International》2022,48(24):36706-36714
A single-component Ca3YAl3B4O15 (CYAB):Dy3+, Eu3+ phosphor was synthesized by the traditional high temperature solid-phase method, Dy3+ and Eu3+ were codoped in the structure to obtain a warm white emission. The results of XRD and EDS revealed that all samples had the standard Ca3YAl3B4O15 structure, and no impurity phase appeared with codoping. The emission of Dy3+ in CYAB consisted of both main peaks at 476 nm and 570 nm, with which a white emission could be observed. Furthermore, a characteristic emission peak of Eu3+ appeared at 617 nm in Dy3+/Eu3+-codoped samples to supplement red component for the white emission of Dy3+, due to the energy transfer effect between Dy3+ and Eu3+. With the amount of Eu3+ raised, the correlated colour temperature of CYAB:Dy3+, Eu3+ phosphor obviously decreased, and a warm white light was successfully realized from the manufactured w-LEDs. Therefore, all results indicated that the single-component Dy3+/Eu3+ codoped CYAB white-emitting phosphor had a potential application in ultraviolet excited w-LEDs.  相似文献   

4.
A series of Dy3+–Eu3+‐codoped ZrO2 nanocrystals with tetragonal and cubic symmetry was synthesized via a wet chemical reaction. When the Eu3+‐doping content was fixed, the crystal structure could be stabilized from the mixed phase to single cubic phase by simply adjusting the content of Dy3+. The cubic ZrO2:Dy3+–Eu3+ nanoparticles exhibited spherical and nonagglomerated morphology. The effective phonon energy of cubic ZrO2:5%Dy3+–5%Eu3+ was calculated to be 445 cm?1, which is lower than the previously reported results. Extensive luminescence studies of ZrO2:Dy3+–Eu3+ as a function of Dy3+ content demonstrated that the dopant concentration and its site symmetry play an important role in the emissive properties. Under 352 nm excitation, the increment of Dy3+ concentration in ZrO2:Dy3+–Eu3+ led to an increase in orange (590 nm) and red (610 nm) emissions of Eu3+ ions, which are attributed to the 5D07FJ(J = 1, 2) transitions of Eu3+ ions. This increment is possibly due to the efficient energy transfer (ET) 4F9/2:Dy3+5D0:Eu3+. The phosphors can generates light from yellow through near white and eventually to warm white by properly tuning the concentration of Dy3+ ions through the ET and change in site symmetry. These phosphors may be promising as warm‐white‐/yellow‐emitting phosphors.  相似文献   

5.
Making illumination light sources become comfortable to the human eye is a long-term effort, which justifies the current research on warm white-light-emitting diodes (w-LEDs). In this work, a novel phosphor for w-LEDs, namely SrGa12O19: Dy3+(SGO: Dy3+), with a low-color temperature (CT) was designed and synthesized. The crystal structure, the luminescence properties, the thermoluminescence properties and the stability of SGO: Dy3+ were investigated. We demonstrate outstanding luminescent characteristics and excellent stabilities. The intensity of emission light keep remained when excited by a flickering light source with a chopping speed or off-time of a few seconds, which indicates that the SGO: Dy3+ phosphor has anti-flicker properties that will be useful for potential applications, as LEDs driven by alternating current (AC-LED). The chromaticity coordinates and the correlated color temperature (CCT) of SGO: Dy3+ phosphors with different Dy3+ concentrations are close with an optimal doping at 4.00 mol% Dy3+ for chromaticity coordinate (0.4269, 0.4348) and a lowest CCT of 3361 K. The perfect weatherability of this phosphor was also confirmed since the phosphorescence intensity and the color were stable at high temperature and in a high humidity environment. The performance obtained shows that SGO: Dy3+ is a suitable candidate for illumination sources that are beneficial to human health.  相似文献   

6.
Dy3+:Eu3+ doped calcium sulfate (CaSO4:Dy3+,Eu3+) phosphors co-doped with various K+ compensator concentrations were synthesized by recrystallization method. These orthorhombic phased phosphors showed intense multi-color near white light. The multi-color aspect ratios and the emission life times were strongly dependent on K+-concentration. These results suggest that the rare-earth (Re3+) ions are situated at the sites of Ca2+ and the site occupancy was being compensated by K+ ions. The near white light emission and large lifetimes suggest that present phosphor could be potentially applied as a blue excited white light-emitting phosphor for light emitting diodes.  相似文献   

7.
《Ceramics International》2021,47(20):28384-28399
Many color-tunable LiLaSiO4: αTm3+, βDy3+ phosphors were prepared using the traditional high-temperature solid-phase method. The phase composition, surface morphology, fluorescence spectrum, fluorescence lifetime, energy transfer mechanism, and color coordinates of the samples were analyzed using XRD, SEM, TEM and fluorescence spectrometer. The results show that LiLaSiO4: αTm3+ phosphor emits high intensity blue light at 460 nm and the concentration quenching point of Tm3+, α = 0.015 mol. In LiLaSiO4: αTm3+, βDy3+ phosphors, as the doped Dy3+ doping increases, the luminescence intensity of Tm3+ gradually decreases, the luminescence intensity of Dy3+ first increases and then decreases. The concentration quenching point of Dy3+, β = 0.015 mol. Adjustable light-emitting color can be obtained by changing the doping molar mass of Dy3+ or the wavelength of the excitation light. There is an effective energy transfer between Tm3+→Dy3+. The energy transfer mechanism is the electric dipole-electric dipole interaction, and the energy transfer efficiency reaches 90.11% when β = 0.06 mol. The quantum yield of LiLaSiO4:0.015 Tm3+,0.015Dy3+ was 39.0%. The single-matrix white light LiLaSiO4: αTm3+, βDy3+ phosphors with excellent performance is a prospective material for of white LEDs.  相似文献   

8.
A series of Dy3+/Eu3+ single- and co-doped calcium borosilicate luminescent glasses were prepared by the conventional high temperature melt-quenching method. A compact glass structure is obtained by the addition of Dy3+/Eu3+ ions, which is verified by the physical properties of synthetic glasses. As network modifiers, Dy3+/Eu3+ fill in the interspaces of glass network and contribute to the conversion of [BO3] to [BO4]. Dy3+/Eu3+ co-doped calcium borosilicate glasses can emit white light, which consists of blue, yellow, and red light under 387 nm excitation. The emission spectra and decay curves of the white-emitting glasses have proved the existence of energy transfer. The average lifetime of Dy3+ decreases from 0.251 to 0.165 ms with the increasing Eu3+ concentration. Changing rare earth ions concentration, CIE color coordinates of Dy3+/Eu3+ co-doped glass shifts from cyan to white with increasing excitation wavelength. A white-light emission is obtained when the concentration of Dy3+ and Eu3+ equals to 4% and 2%, respectively. Moreover, the Dy3+/Eu3+ co-doped calcium borosilicate glass shows high-thermal stability and it may be applicable for high-quality white LEDs based on high power near ultraviolet (n-UV) LED chip in the future.  相似文献   

9.
《Ceramics International》2016,42(11):13004-13010
A series of Dy3+ or/and Eu3+ doped Y2Mo4O15 phosphors were successfully synthesized at a low temperature of 600 °C via solid state reaction. The as-prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electronic microscope (SEM), photoluminescence (PL) excitation, emission spectra and PL decay curves. XRD results demonstrate that Y2Mo4O15: Dy3+, Eu3+ has the monoclinic structure with the space group of p21/C(14). Under the excitation of ultraviolet (UV) or near-UV light, the Dy3+ and Eu3+ ions activated Y2Mo4O15 phosphors exhibit their characteristic emissions in the blue, yellow and red regions. The emitting light color of the Y2Mo4O15: 0.08Dy3+, yEu3+ phosphors can be adjusted by varying the concentration ratio of Dy3+ to Eu3+ ions and a white light is achieved when the doping concentration of Eu3+ is 5%. In addition, the energy transfer from Dy3+ to Eu3+ is also confirmed based on the luminescence spectra and decay curves.  相似文献   

10.
SrAl2O4:Eu2+,Dy3+ phosphors can convert near ultraviolet light with lower sensitivity to the solar cell to yellow‐green light at which the solar cell has higher sensitivity and exhibit the excellent luminescent property of long persistence. Therefore, in this study, the authors firstly synthesized the fine SrAl2O4:Eu2+,Dy3+ phosphors and then produced SrAl2O4:Eu2+,Dy3+/SiO2 composite films as spectral shifters to understand the effects of SrAl2O4:Eu2+,Dy3+ phosphor on photoelectric conversion efficiencies of a crystalline silicon photovoltaic module. Under one sun illumination, the composite film containing an appropriate amount of SrAl2O4:Eu2+,Dy3+ phosphor enhances the photoelectric conversion efficiency of the cell through spectral down‐shifting as compared to the bare glass substrate, and the maximum achieves 11.12%. In contrast, the commercial SrAl2O4:Eu2+,Dy3+ phosphor composite film is not effective for improving the photoelectric conversion efficiency because of the relatively lower visible light transmittance of film caused by the large aggregates. After one sun illumination for 1 min, the light source was turned off, and the cell containing the synthesized SrAl2O4:Eu2+,Dy3+ phosphor still shows an efficiency of 1.16% in the dark due to the irradiation by the long persistent light from SrAl2O4:Eu2+,Dy3+, which provides a possibility to fulfill the operation of solar cells even in the dark.  相似文献   

11.
《Ceramics International》2021,47(24):34323-34332
Eu3+-activated Sr3−xCaxLa(VO4)3 phosphors were fabricated via citric-acid-assisted sol combustion. Characterization of the Sr3−xCaxLa(VO4)3:Eu3+ samples with different concentrations of Ca2+ revealed a hexagonal crystal structure belonging to the R-3m space group. The amount of Ca2+ added (x) was controlled within 0 ≤ x ≤ 2 to yield high-purity phosphors. Scanning electron microscopy results showed that an increase in Ca2+ concentration resulted in a decrease in the particle size of Sr3−xCaxLa(VO4)3:Eu3+, with the shape gradually changing from nearly equiaxed to lath-shaped. The Sr2CaLa(VO4)3:Eu3+ phosphor (denoted as SCLVO:Eu3+) exhibited the strongest photoluminescence (PL) intensity at 618 nm among the samples under excitation of 394-nm near-UV (NUV) light. The study of Eu3+ doping concentration confirmed that Eu3+ could enter the lattice of the SCLVO matrix without altering its crystal structure. SCLVO:Eu3+ was found to strongly absorb 394 nm NUV light and 464 nm blue light. The optimal concentration of the Eu3+ dopant in the SCLVO host was 0.11, which resulted in the phosphor achieving an excellent PL intensity and a color purity of 98.68%. Tunable luminescence from the orange area (0.5280, 0.4522) of Commission Internationale de l'éclairage (CIE) to the red area (0.6313, 0.3650) was achieved by adjusting the concentration of Eu3+. Under 394 nm excitation, SCLVO:0.11Eu3+ phosphor has a quantum yield (QY) of 28.2% and excellent thermal stability with 0.383 eV activation energy. Consequently, White-light-emitting diode (WLED) based on SCLVO:0.11Eu3+ phosphor yielded a high color rendering index (CRI), low correlated color temperature (CCT), and CIE coordinates of 91.8, 5196 K, and (0.3407, 0.3612), respectively, under the 20 mA driven current. These results indicated the tremendous potential of SCLVO:0.11Eu3+ phosphors for application in WLEDs excited by NUV or blue light.  相似文献   

12.
Developing narrowband red phosphors has always been a frontier topic in the phosphor community. In this study, a novel hafnium germanate red phosphor, BaHfGe3O9:Eu3+, was successfully synthesized by solid-state reaction method. The phase and crystal structure of BaHfGe3O9 were investigated by the Rietveld refinement of powder X-ray powder diffraction. The band structure was analyzed by density functional theory calculations. Most importantly, the luminescence behavior of phosphors under near-ultraviolet (n-UV) light and cathode rays sources was studied in detail to explore the possibility of their applications in white light-emitting diodes and field emission display. The BaHfGe3O9:Eu3+ phosphor exhibits strong f–f excitation and excellent thermal robustness due to Eu3+ localization in the rigid lattice and asymmetric Ba2+ sites. Under cathode rays and n-UV light excitation, BaHfGe3O9:Eu3+ exhibits narrowband red light emission peaked at 610 nm. Moreover, BaHfGe3O9:Eu3+ shows excellent saturation resistance and aging resistance. The performance of the LED lamp encapsulated by the BaHfGe3O9:Eu3+ phosphor was studied. The results show that BaHfGe3O9:Eu3+ is a potential red phosphor for multifunctional applications.  相似文献   

13.
LaF3:Eu nanophosphors were prepared by a traditional hydrothermal method with citric acid as a reducing agent. X-ray diffraction, scanning electronic microscopy, and luminescence spectroscopy were used to study the nanophosphors. The formation of three different luminescence centers of Eu2+ and two different luminescence centers of Eu3+ is attributed to the existence of abundant surface defects in this nanophosphor. Eu3+ is effectively excited by energy transfer from Eu2+ to Eu3+. The excitation wavelength of Eu3+ covers a broad spectral range from 250 to 480 nm. The nanophosphor shows a tunable luminescence color varying from blue to white and then to red, which is explained from three aspects of Eu concentration, energy transfer, and concentration quenching. Utilizing the surface defect of nanoparticles to control the reduction of Eu3+ is considered a promising strategy for exploring Eu2+ and Eu3+ codoped phosphor suitable for the lighting and display application.  相似文献   

14.
Pure and Eu2+-activated fluoroborate BaGaBO3F2 was prepared using high-temperature solid-state reaction. BaGaBO3F2 is a wide band semiconductor with the indirect transition characteristic. The excitation and luminescence spectra of the phosphor were measured, and it was found that Eu2+-activated BaGaBO3F2 exhibits a bright blue color under ultraviolet (UV) light. The narrow emission band peaked at 425 nm is attributed to the transitions of 4f65d→4f7(8S7/2), and the Stokes shift estimated for this phosphor sample is 3140 cm−1. The lifetime of the luminescence is also reported. The absolute quantum efficiency (QE) of the phosphor was evaluated, and it was found that the absolute QE decreases with increasing Eu2+ concentration. The phosphor shows an excellent quantum efficiency of 72.5% and a high thermal activation energy of 0.342 eV. The study concludes that Eu2+-doped BaGaBO3F2 phosphor has promising luminescence application abilities and can be used as a blue-emitting phosphor in a variety of applications.  相似文献   

15.
《Ceramics International》2020,46(5):6276-6283
In this study, novel Eu3+-, Dy3+-, and Sm3+-activated Na3La(VO4)2 phosphors were synthesized using a solid state reaction method. X-ray diffraction analysis results indicated that the Na3La(VO4)2 phosphors had an orthorhombic crystal structure with the Pbc21 space group. There were two different La(1)O8 and La(2)O8 polyhedra with high asymmetry in the crystal structure. Scanning electron microscopy revealed that the product had a sheet morphology with an irregular particle size. Further, the luminescence properties, including the excitation and emission spectra, and luminescence decay curve, were investigated using a fluorescence spectrometer. The results showed that the Na3La(VO4)2 compound was an excellent host for activating the luminescence of Eu3+ (614 nm), Dy3+ (575 nm), and Sm3+ (647 nm) ions. Further, Dy3+/Eu3+ co-doped Na3La(VO4)2 phosphors were exploited, and the energy transfer from Dy3+ to Eu3+ was demonstrated in detail by the photoluminescence excitation, photoluminescence spectra, and luminescent decay curves. The results showed that the energy transfer efficiency from Dy3+ to Eu3+ was highly efficient, and the energy transfer mechanism was dipole–dipole interactions. Finally, tunable emissions from the yellow region of CIE (0.3925, 0.4243) to the red region of CIE (0.6345, 0.3354) could be realized by rationally controlling the Dy3+/Eu3+ concentration ratio. These phosphors may be promising materials for the development of solid-state lighting and display systems.  相似文献   

16.
Dy3+, Eu3+: NaLa(WO4)2 phosphors are successfully synthesized through the solid-state reaction technique. The phase-structure and morphology are measured via X-ray diffraction and energy dispersive spectrometry. The concentrations of Dy3+, Eu3+, La3+, and W6+ are measured via ICP. The absorption and excited spectra are presented, which indicate that a blue band ranging from 430 to 480 nm is suitable for excitation. Using a commercial blue LED with a wavelength of 450 nm as the excitation light source, emission spectra for samples with varying dopant concentration ratios of Dy3+ to Eu3+ are obtained, which show good tunable yellow and red emission. For the purpose of investigating white LED performance, CIE spectra and a white light photo are also presented. The results reveal that varying the dopant concentration ratio of Dy3+ to Eu3+ plays a key role in the warm-white performance. With increasing concentration of Eu3+, the correlated color temperature decreases from 4069 to 3172 K, which indicates good warm-white performance.  相似文献   

17.
《Ceramics International》2019,45(15):18604-18613
A red-emitting Eu3+-activated double perovskite Sr3MoO6 phosphor material was successfully synthesized by a high-temperature solid-state reaction. Upon 353 and 467 nm excitations, the prepared phosphors exhibited the feature emission properties of Eu3+ ions with the corresponding characteristic electronic transitions. The concentration quenching of Eu3+ ions was found at 30 mol% and the quadrupole-quadrupole interaction was dominant in quenching process. The chromaticity coordinates for the optimal doping concentration of Eu3+ ions under the 353 and 467 nm excitations were in the pure red region, while the color purity was calculated to be about 94.536 and 94.780%, respectively. The superior luminescence properties of the red-emitting Sr3MoO6:0.3Eu3+ phosphor were achieved and with further blending with commercial phosphors, the white light-emitting diode (WLED) devices were fabricated for practical application. The fabricated WLED device based on 385 nm near-ultraviolet (NUV) chip revealed the color-rendering index and color temperature values of 90.96 and 6381 K, respectively. And the soft polydimethylsiloxane film emitted the pure red region under NUV light. These results suggest that this kind of material could be a promising red-emitting phosphor for WLEDs and flexible display film.  相似文献   

18.
《Ceramics International》2023,49(10):15320-15332
A variety of Bi3+ and/or Eu3+ doped KBaYSi2O7 phosphors with deep blue, cyan, orange-red, and white light multicolor emissions have been fabricated by a Pechini sol-gel (PSG) method. The KBaYSi2O7:Bi3+ phosphors exhibit an intense cyan emission or a unique narrow deep blue emission when excited by different wavelengths, which may bridge the cyan gap or act as a promising deep blue phosphor for white light-emitting diodes (WLEDs). The tunable multicolor emissions can be achieved by changing the Bi3+ doping concentrations. The Bi3+/Eu3+ co-doped KBaYSi2O7 phosphors display intrinsic emissions of Bi3+ and Eu3+ and an energy transfer process between Bi3+ and Eu3+ can be detected. The luminescence colors of KBaYSi2O7:Bi3+,Eu3+ regularly shift from blue, through cold and warm white, finally toward orange-red by adjusting the relative doping concentrations of Bi3+ and Eu3+. The single-phase white light-emitting material can be generated in both cold and warm white regions by simply varying the Eu3+ doping concentrations. Furthermore, three kinds of WLEDs devices are fabricated by KBaYSi2O7:Bi3+ or KBaYSi2O7:Bi3+,Eu3+ phosphors, which can exhibit dazzling white light emissions with eminent CIE coordinates, correlated color temperature, and color rendering index. The result offers direct evidence that the as-synthesized phosphors may be potentially applied in WLEDs and solid-state lighting.  相似文献   

19.
In this study, the amino silane coupling agent (KH550)-modified SrAl204: Eu2+, Dy3+ phosphor powder coated with phenolic epoxy resin (EOCN) in the presence of triarylsulfonium hexafluoroantimonate catalyst was prepared using the combination of organic–inorganic composite dip-coating and UV curing coating methods. The results of SEM, TEM, and FTIR showed that the organic coating was a layer of compact membrane with a thickness of 20–50 nm, which can be named silane-modified epoxy monomer generated by the KH550 and the EOCN. Furthermore, it was observed that afterglow and spectrum properties of the coated phosphor powder had good long-afterglow luminescence properties, and revealed two emission peaks at 435 nm and 520 nm under the same excitation wavelength of 360 nm, respectively. More interesting, the emitting color of the coated sample was located in the area of cyan light on CIE1931 chromaticity diagram, which led to a slight blue shift rather than the yellow–green color of the pure SrAl204: Eu2+, Dy3+ phosphor powder.  相似文献   

20.
Eu3+‐doped tungstate Ba2La2ZnW2O12 phosphors with perovskite‐structure were prepared by the high temperature solid‐state reaction. The X‐ray powder diffraction (XRD) patterns and structure refinements indicate that the phosphors crystalized in the trigonal layer‐perovskite. The luminescence properties of the phosphors were investigated such as photoluminescence (PL) excitation and emission spectra, decay lifetimes, and color coordinates. It was found that the pure host shows self‐activated emission excited by the UV light. Moreover, Ba2La2ZnW2O12 also shows scintillation characteristics under the X‐ray irradiation. The near‐UV and blue light can efficiently excite Eu3+‐doped Ba2La2ZnW2O12 phosphors inducing the strong orange–red luminescence. The optimal Eu3+ doping concentration in this host is 40 mol%. The luminescence spectra and the luminescence color of the phosphors strongly depend on the doping levels and excitation wavelength. The different luminescence features were discussed on the base of crystal structure. Eu3+ ions have two possible substitutions on A or B sites in this trigonal layered perovskite. The phosphor could act as a candidate for the potential application in near‐UV excited white‐LEDs lighting.  相似文献   

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