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1.
《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   

2.
ABSTRACT

Uniform Al2O3:Eu3+ samples were successfully fabricated via a hydrothermal method and subsequent thermal decomposition of Eu3+-doped precursors. The sample characterisations were carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectra. XRD results revealed Eu3+-doped samples were a pure γ-Al2O3 phase after being calcined at 1173?K. SEM results showed that these Eu3+-doped Al2O3 samples were stalk-like, with an average length of 1.5?μm. Upon excitation at 394?nm, the orange–red emission bands, having wavelengths longer than 580?nm, were to be from 5D07FJ (J?=?1, 2) transitions. The asymmetry ratio of (5D07F2)/(5D07F1) intensity is about 0.54, 2.76, 3.29, 2.86, 3.36, 3.13 for Eu3+ concentrations of 0.1, 0.4, 0.7, 1.0, 1.5 and 2.0?mol-%, respectively. The optimal doping concentration of Eu3+ ions in Al2O3 is 1.5?mol-%. According to Dexter's theory, the critical distance between Eu3+ ions for energy transfer was determined to be 14?Å.  相似文献   

3.
《Ceramics International》2016,42(12):13841-13848
A series of Eu3+- or Dy3+-doped and Eu3+/Dy3+ co-doped Y2WO6 in pure phase was synthesized via high-temperature solid-state reaction. X-ray diffraction, diffuse reflection spectra, photoluminescence excitation and emission spectra, the CIE chromaticity coordinates and temperature-dependent emission spectra were exploited to investigate the phosphors. Upon UV excitation at 310 nm, efficient energy transfer from the host Y2WO6 to dopant ions in Eu3+ or Dy3+ single-doped samples was demonstrated and those phosphors were suitable for the UV LED excitation. The intense red emission was observed in Y2WO6: Eu3+, and blue and yellow ones were observed in Y2WO6: Dy3+. Concentration quenching in Y2WO6: Dy3+ phosphors could be attributed to the electric dipole-dipole interaction. In Eu3+/Dy3+ co-doped Y2WO6 phosphors energy transfer process only took place from the host to Eu3+/Dy3+ ions and warm white-light emission can be obtained by adjusting the dopant concentrations. The temperature-dependent luminescence indicated Eu3+/Dy3+ co-doped Y2WO6 was thermally stable. Our overall results suggested that Y2WO6: Ln3+ (Ln3+=Eu3+, Dy3+) as warm white-light emitting host-sensitized phosphor might be potentially applied in WLEDs.  相似文献   

4.
Eu2+-doped BaAl2O4 green phosphors were prepared by a conventional solid-state reaction and the effects of Dy3+ co-doping on the photoluminescence property were investigated. The phosphors were characterized by X-ray powder diffraction (XRD), fluorescence spectroscopy, field-emission scanning electron microscopy (FESEM) and X-ray photoelectron spectroscopy (XPS). XRD showed that all prepared samples exhibited a hexagonal BaAl2O4 phase. Fluorescence spectroscopy showed that the photoluminescence efficiency increased with increasing Eu2+ concentration until 3 mol% then decreased at higher concentrations due to concentration quenching effect. Moreover, Dy3+ co-doping increased the photoluminescence efficiency of the Eu2+-doped BaAl2O4 phosphor.  相似文献   

5.
Cubic Y2O3:Eu3+ nanoparticles with a size about 32 nm were synthesized using a facile hydrothermal method followed by an annealing process. As expected, the Y2O3:Eu3+ nanoparticles had a broad Eu–O excitation band ranging from 200 nm to 285 nm peaking at about 260 nm. The Y2O3:Eu3+ nanoparticles were then used to fabricate the inorganic–organic hybrid nanostructures with thenoyltrifluoroacetone (TTA). The Y2O3:Eu3+–TTA hybrid nanostructures exhibited a new strong excitation band ranging from 280 nm to 390 nm peaking at about 368 nm. This new excitation band was attributed to the energy transfer mechanism of the Y2O3:Eu3+–TTA hybrid system. It is interesting to note that this energy transfer mechanism had a close interaction with the Eu–O excitation of Y2O3:Eu3+ nanoparticles. The phase structures, chemical bonding information, microstructural characteristics and luminescence properties were investigated.  相似文献   

6.
《Ceramics International》2015,41(8):9680-9685
Pure, Eu3+, Dy3+ or Nd3+-doped NiNb2O6 powders have been prepared by a molten salt synthesis method by using Li2SO4–Na2SO4 salt mixture as a flux at relatively low temperatures as compared to the solid state reaction method. X-ray diffraction patterns of pure NiNb2O6 samples indicated an orthorhombic single phase. For Eu3+-doped NiNb2O6 samples, the luminescence of Eu3+ was observed at 615 nm as red emission while Dy3+-doped NiNb2O6 showed yellow emission at 577 nm and Nd3+ doped sample exhibited a typical emission at 1064 nm varying with the Eu3+ or Nd3+ doping concentrations. These luminescence characteristics of the doped samples may be attributed to the energy transfer between rare earth ions and NiO6 octahedral groups in the columbite structure.  相似文献   

7.
《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   

8.
Transparent glass‐ceramics containing Ce3+: Y3Al5O12 phosphors and Eu3+ ions were successfully fabricated by a low‐temperature co‐sintering technique to explore their potential application in white light‐emitting diodes (WLEDs). Microstructure of the sample was studied using a scanning electron microscope equipped with an energy dispersive X‐ray spectroscopy. The impact of co‐sintering temperature, Ce3+: Y3Al5O12 crystal content and Eu3+ doping content on optical properties of glass‐ceramics were systematically studied by emission, excitation spectra, and decay curves. Notably, the spatial separation of these two different activators in the present glass‐ceramics, where Ce3+ ions located in YAG crystalline phase while the Eu3+ ones stayed in glass matrix, is advantageous to the realization of both intense yellow emission assigned to Ce3+: 5d→4f transition and red luminescence originating from Eu3+: 4f→4f transitions. As a result, the quantum yield of the glass‐ceramic reached as high as 93%, and the constructed WLEDs exhibited an optimal luminous efficacy of 122 lm/W, correlated color temperature of 6532 K and color rendering index of 75.  相似文献   

9.
Columnar Gd2O2S:Eu3+ nanophosphors have been synthesized through solvothermal reaction and subsequent calcination process. The structure, morphology, and luminescence properties of samples were investigated via X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) spectra, UV-vis absorption spectra, field emission scanning electron microscope (FE-SEM), and photoluminescence (PL) spectra. The Judd-Ofelt (J-O) parameters of Gd2O2S:Eu3+ nanophosphors with different doping concentration were calculated by emission spectra to understand the symmetry, coordination environment, and luminescence behavior of Eu3+ ions in Gd2O2S matrix. In addition, the luminescence properties of columnar Gd2O2S:Eu3+ and Gd2O3:Eu3+ were compared in detail. The comparison results show that there are subtle differences in luminescence intensity, main peak position, luminescence color, and fluorescence lifetime between them, which are closely related to their different substrate's structure, including the band-gap energy, crystallinity, and symmetry, etc.  相似文献   

10.
In this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid-state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from 3P1 → 1S0 transition of Bi3+ ions and characteristic emission peaks from 4f–4f transition of Eu3+ ions. Outstanding temperature-sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (Sr) can attain 1.51% K−1 (λex = 290 nm). With temperature raising (303–513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (λex = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high-temperature safety marker.  相似文献   

11.
As-synthesized Fe3O4 nanoparticles were encapsulated with carbon layers through a simple hydrothermal process. Fe3O4/C nanoparticles were coated with YVO4:Dy3+ phosphors to form bifunctional Fe3O4@C@YVO4:Dy3+ composites. Their structure, luminescence and magnetic properties were characterized by XRD, SEM, TEM, HRTEM, PL spectra and VSM. The experimental results indicated that the as-prepared bifunctional composites displayed well-defined core–shell structures. The ∼12 nm diameter YVO4:Dy3+ shell exhibited tetragonal structure. Additionally, the composites exhibited a high saturation magnetization (13 emu/g) and excellent luminescence properties, indicating their promising potential as multifunctional biosensors for biomedical applications.  相似文献   

12.
《应用陶瓷进展》2013,112(8):455-459
Abstract

Tb3+ doped Y2O2SO4 (Y2O2SO4:Tb3+) microflakes were prepared by a combination method of electrospinning and calcination. The two-dimensional microflakes had smooth surface and high radial/axial ratio. Crystal structures of the Y2O2SO4:Tb3+ microflakes resulted in layer by layer growth in axial direction. A possible formation mechanism was proposed on the basis of experimental results, which indicated that poly(vinyl pyrrolidone) played the role of the nanostructure directing template and revealed the growth priority in radial direction. The microflakes showed a favourable fluorescent property symbolised by the characteristic green emission (541 nm) resulting from the 5D47F5 transition of Tb3+ ions under 229 nm ultraviolet excitation. The maximum intensity of Tb3+ emission of the Y2O2SO4:Tb3+ microflakes was 2·3 times stronger than that of the Y2O2SO4:Tb3+ bulk powders with the same doping concentration.  相似文献   

13.
Using the melt-quench technique, potassium zinc borophosphate (KZnBP) glasses incorporated with Dy3+, Eu3+, and Dy3+/Eu3+ ions individually and combinedly were prepared, and their photoluminescence (PL)-related features were investigated. The KZnBP glass containing an optimized content of Dy3+ (0.5 mol%) is co-doped with Eu3+ in various contents, and the energy transfer (ET) process between them was studied at λexci = 349, 364, 387 (Dy3+), and 394 nm (Eu3+). The Dy3+/Eu3+ co-doped system, when excited with Dy3+ excitations has resulted in a significant decrease in the intensity of Dy3+ peaks observed at 480 nm (4F9/26H15/2, blue) and 574 nm (4F9/26H13/2, yellow), with simultaneous enhancement of the intensity of Eu3+ peaks at 591 nm (5D07F1, orange) and 617 nm (5D07F2, red). This trend is due to the efficient energy transfer from Dy3+ to Eu3+, indicating that Eu3+ ions were sensitized by Dy3+ ions. Dexter's theory and the Inokuti–Hirayama (I–H) model revealed that the dipole–dipole interaction is accountable for the energy transfer from Dy3+ to Eu3+ through energy-transfer channels [4F9/2(Dy3+)+7F1,2(Eu3+)→6H15/2(Dy3+)+5D2(Eu3+)] and [4F9/2(Dy3+)+7F0(Eu3+)→6H13/2(Dy3+)+5D0(Eu3+)]. The color coordinates of the Dy3+/Eu3+ co-doped glasses under various excitations fall within the white light emission spectrum, indicating their potential application in warm white LEDs.  相似文献   

14.
Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol–gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of 5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration.  相似文献   

15.
The polycrystalline Eu2+ and Dy3+ codoped strontium aluminates SrAl2O4: Eu2+,Dy3+ were prepared by a solid-state reaction. The UV-excited photoluminescence, persistent luminescence, and thermoluminescence of the SrAl2O4: Eu2+,Dy3+ phosphors with different compositions and ion doping was studied and compared. The results showed that the Eu2+ ion doped in SrAl2O4: Eu2+,Dy3+ phosphors is not only the UV-excited luminescent center but also the persistent luminescent center. The Dy3+ ion introduced into SrAl2O4: Eu2+ crystal matrix can hardly yield any luminescence under UV excitation but acts as an electron trap with a suitable depth for persistent luminescence. The Dy3+ codoping would effectively enhance the persistent luminescence and thermoluminescence. Different codoping RE 3+ ions have a different effect on persistent luminescence. Only the RE 3+ ions (for example, Dy3+ and Nd3+), which have suitable optical electronegativity, can form suitable electron traps and effectively improve the persistent luminescence of SrAl2O4: Eu2+. Based on the above observations, a persistent luminescence mechanism, electron transfer model, was proposed and illustrated. The text was submitted by the authors in English.  相似文献   

16.
《Ceramics International》2022,48(2):1814-1819
Sr3Al2-xBxO5Cl2:Eu2+, Dy3+ (x = 0, 0.2, 0.4) long persistent phosphors were prepared via solid-state process. The pristine Sr3Al2O5Cl2:Eu2+, Dy3+ phosphor exhibits orange/red broad band emission around 609 nm, which can be attributed to the electric radiation transitions 4f65 d1→4f7 of Eu2+. Upon the same excitation, the B3+-doped Sr3Al2-xBxO5Cl2:Eu2+, Dy3+ phosphors display red-shift from 609 nm to 625 nm with increasing B3+ concentrations. The XRD patterns show that Al3+ can be replaced by B3+ in the host lattice at the tetrahedral site, which causes lattice contraction and crystal field enhancement, and thereafter achieves the red-shift on the emission spectrum. The XPS investigation provides direct evidence of the dominant 2-valent europium in the phosphor, which can be ascribed for the broad band emission of the prepared phosphors. The afterglow of all phosphors show standard double exponential decay behavior, and the afterglow of Sr3Al2O5Cl2:Eu2+, Dy3+is rather weak, while the sample co-doped with B3+shows longer and stronger afterglow, as confirmed after the curve simulation. The analysis of thermally stimulated luminescence showed that, when B3+ is introduced, a much deeper trap is created, and the density of the electron trap is also significantly increased. As a result, B3+ ions caused redshift and enhanced afterglow for the Sr3Al2-xBxO5Cl2:Eu2+, Dy3+ phosphor.  相似文献   

17.
Eu2O3/Si multilayer nanostructured films are deposited on Si substrates by magnetron sputtering. Transmission electron microscopy and X-ray diffraction measurements demonstrate that multicrystalline Eu silicate is homogeneously distributed in the film after high-temperature treatment in N2. The Eu2+ silicate is formed by the reaction of Eu2O3 and Si layers, showing an intense and broad room-temperature photoluminescence peak centered at 610 nm. It is found that the Si layer thickness in nanostructures has great influence on Eu ion optical behavior by forming different Eu silicate crystalline phases. These findings open a promising way to prepare efficient Eu2+ materials for photonic application.  相似文献   

18.
《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   

19.
Europium doped yttrium oxide phosphors were synthesized by a rapid microwave-assisted solvothermal method. The microwave processing time for synthesizing the precursors of Y2O3:Eu3+ powders was as short as 5 min. After calcination at 600 °C, a well-crystallized pure phase of Y2O3:Eu3+ was obtained. The morphology of the precipitated powders was spherical and composed of nano-sized grains. As the microwave irradiation time was increased, the average particle size of the spherical powders increased, and the crystallinity of heat-treated powders was also enhanced. The synthesized powders retained the spherical morphology after heating treatments. An intense red emission at 611 nm was assigned to the 5D0-7F2 transition of Eu3+.  相似文献   

20.
Europium-doped yttrium orthovanadate/polyethylene oxide nanofibers were fabricated by firstly, synthesizing crystalline YVO4:Eu3+ nanoparticles using an aqueous precipitation method followed by electrospinning of PEO/YVO4:Eu3+ polymer composites. X-ray diffraction patterns showed that the nanoparticles exhibited well-defined peaks that were indexed as the tetragonal phase of YVO4. No additional peaks of other phases were observed indicating that Eu3+ ions were effectively built into the YVO4 host lattice. The photoluminescence spectra for the nanofibers showed peaks at 593, 615, 650, and 698 nm which was ascribed to the 5D0? 7F1, 5D0? 7F2, 5D0? 7F3 and 5D0? 7F4 transitions of Eu3+. Due to an efficient energy transfer from vanadate groups to Eu3+, the composite nanofibers showed a strong red emission under ultraviolet excitation characteristic of the red luminescence of the europium ion. The results demonstrate that this synthetic approach could prove to be viable for the fabrication of rare earth/polymer composite nanofibers intended for luminescent device applications.  相似文献   

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