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1.
Hexagonal YPO4 phosphors doped with Eu3+/Dy3+ and co-doped with Ce3+ were synthesized by a hydrothermal route assisted using lauric acid as a capping agent. The prepared phosphors were characterized by transmission electron microscopy, infrared spectroscopy, powder X-ray diffraction and photoluminescence spectra. YPO4: Eu3+ gives two red emission peaks at 587 and 610?nm corresponding to 5D07F1 and 5D07F2 transitions, respectively. YPO4: Dy3+ exhibits two emission peaks at 485?nm (blue) and 575?nm (yellow) corresponding to 4F9/26H15/2 and 4F9/26H13/2 transitions, respectively. Ce3+ ions enhanced the emission intensity as a co-dopant in both phosphors. Moreover, the effect of γ-radiation in the dose range 5–300?kGy on the photoluminescence behaviour of YPO4:Eu3+,Ce3+ and YPO4:Dy3+,Ce3+ was also investigated. Quenching of emission intensity, after irradiation at 5 and 300?kGy, was observed in both the phosphors due to loss of excess energy through a non-radiative relaxation process.  相似文献   

2.
In this study, we report a comprehensive structural and photoluminescence (PL) study on lithium metasilicate (Li2SiO3) phosphor ceramics doped with four rare earth (RE) ions. X-ray diffraction (XRD) patterns show a dominant phase, characteristic of the orthorhombic structure Li2SiO3 compound and the presence of dopants has no effect on the basic crystal structure of the material. The first excited state Er3+ luminescence at 1.54 μm arises from a sharp atomic-like radiative transition between the 4I13/2 state and the 4I15/2 state (ground level) under a 532 nm line of an Ar ion laser excitation. Sm doped samples showed Sm3+ emission characteristics corresponding to the some 4G5/26Hj (j=5/2,9/2,11/2) transitions indicating a strong crystal-field effect. PL spectra of Eu doped material exhibited peaks corresponding to the 5D07Fj (j=0,1,2,3 and 4) transitions under 405 nm excitation. The dominant red color emission at 612 nm from the hypersensitive (5D07F2) transition of Eu3+ indicates the inversion antisymmetry crystal field around Eu3+ ion, which is favorable to improve the red color purity. Dy doped samples showed the Dy3+ emission characteristic due to the 4F9/26H13/2 transition. Their relative intensity ratios also suggested the presence of a symmetric environment around the metal ion. We suggest that lithium metasilicate has enough potential candidates to be a phosphor material.  相似文献   

3.
红色LiMBO3 : Re3+(Re=Eu,Sm) 发光材料的特性   总被引:2,自引:1,他引:1       下载免费PDF全文
采用固相法制备了红色LiM(M=Ca, Sr, Ba)BO3 : Re3+(Re=Eu, Sm)发光材料,研究了材料的发光性能。研究发现LiM(M=Ca, Sr, Ba)BO3 : Eu3+材料呈现多峰发射,最强发射分别位于610,615,613 nm处,分别监测这三个最强峰,所得激发光谱峰值位于369,400,470 nm。LiM(M=Ca, Sr, Ba)BO3 : Sm3+材料也呈多峰发射,分别对应Sm3+4G5/26H5/24G5/26H7/24G5/26H9/2跃迁发射;分别监测602,599,597 nm三个最强发射峰,所得激发光谱峰值位于374,405 nm。研究了激活剂浓度对材料发射强度的影响,结果随激活剂浓度的增大,发射强度先增强后减弱,即,存在浓度猝灭效应。实验表明,加入电荷补偿剂Li+、Na+或K+均可提高LiM(M=Ca, Sr, Ba)BO3 : Re3+(Re=Eu, Sm)材料的发射强度。  相似文献   

4.
Li2Sr1−3x/2Dy x SiO4 phosphors were synthesized at 900°C in the normal atmosphere by a solid-state method. The synthesized phosphors were characterized by X-ray powder diffraction (XRD) and photoluminescence (PL) spectra. The photoluminescence excitation (PLE) spectra show excitation peaks ranging from 300 to 400 nm due to the 4f-4f transitions of Dy3+. This mercury-free excitation is useful for solid-state lighting and light-emitting diodes (LEDs). The predominant emission of Dy3+ ions under 349 nm excitation is observed at 479 nm (blue) due to the 4F9/26H15/2 transitions and 572 nm (yellow) due to 4F9/26H13/2 transitions, respectively. The PL results reveal that the optimal concentration of the Dy3+ ions in Li2Sr1−3x/2Dy x SiO4 phosphors is x=0.03 mol. The nature of the resonance energy transfer for the Dy3+ ions is confirmed by Huang’s rule. Simulation of the white light excited by 349 nm near-ultraviolet (n-UV) light is also performed for its potential for white LEDs.  相似文献   

5.
In this paper we report the combustion synthesis of rare earth (RE=Eu, Dy) doped Ba4Al2O7 phosphors. Prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), CIE color co-ordinates and their photoluminescence (PL) properties were also investigated. In case of Ba4Al2O7: Eu2+, the emission spectra show unique band centered at 495 nm, which corresponds to the 4f65d1→4f7 transition of Eu2+, and PL emission spectra of Dy3+ ion under 348 nm excitation give two bands centered at 478 nm (blue) and 575 nm (yellow), which originate from the transitions of 4F9/26H15/2 and 4F9/26H13/2 of Dy3+, respectively. The results indicate that the Eu2+ and Dy3+ activated Ba4Al2O7 phosphor could find application in solid state lighting.  相似文献   

6.
Lithium titanate ceramics doped with three rare earth (RE) ions namely Eu3+, Dy3+ and Tb3+ were synthesized and their photoluminescence (PL) properties were investigated. PL spectra of Eu doped sample showed peaks corresponding to the 5D07Fj (j=0, 1, 2, 3 and 4) transitions under 230 nm excitation. Strong red emission coming from the hypersensitive 5D07F2 transition of Eu3+ ion suggested the presence of the dopant ion in a highly asymmetric environment. Dy doped samples showed the Dy3+ emission characteristic due to 4F9/26H15/2 and 4F9/26H13/2 transitions. Their relative intensity ratios also suggested the presence of asymmetric environment around the metal ion. In case of the Tb3+ doped sample blue-green emission corresponding to the 5D47Fj (j=6, 5 and 4) transitions was seen. The fluorescence lifetimes of Eu3+, Dy3+ and Tb3+ ions were found to be 645, 900 and 740 μs, respectively. PL intensity of the individual rare earth doped samples was compared with commercial red and green phosphors. It was found that the emission from Eu doped titanate sample was 46% of the commercial red phosphor and in case of the Tb samples it was 30% when excited at 230 nm. However, the synthesized Eu doped titanate sample showed better color purity as compared to the commercial phosphor. The titanate host was doped with all the three rare earths to get white light emission from the system. The individual rare earth ion content was optimized so as to get a near white light emission. The color coordinates of the triple doped systems were evaluated and plotted on the CIE xy diagram. Our results suggest that lithium titanate has enough potential to be a phosphor material.  相似文献   

7.
A series of Eu2+ and Sm3+ co-doped Li2SrSiO4 phosphors are prepared by the high temperature solid-state reaction. The morphology, structure and spectroscopic properties of the prepared samples are characterized by scanning electron microscopy, X-ray diffraction, diffuse reflection spectra, photoluminescence spectra and electron paramagnetic resonance spectra, respectively. The effect of Sm3+ doping concentration on the photoluminescence intensity of the prepared samples is also investigated. The results indicate that the crystal structure of Li2SrSiO4 is not changed with the Eu2+, Sm3+ co-doping. The spherical-like particle size of the obtained product is about 20–30 nm in diameter. When the Sm3+ concentration is 0.3 mol% and the Eu2+ concentration is 0.7 mol%, the phosphors show the maximum emission intensity, which is 50% higher than that of Eu2+ doped Li2SrSiO4. Excited at 420 nm, the phosphor presents a single broad emission band peaking at 558 nm, which is ascribed to the 4f65d1 → 4f7 transitions of Eu2+ and 4G5/2 → 6H5/2 and 4G5/2 → 6H7/2 transitions of Sm3+. The Commission International de I′Eclairage chromaticity coordinates of Li2SrSiO4:0.7 mol% Eu2+, 0.3 mol% Sm3+ are x = 0.28, y = 0.28.  相似文献   

8.
Structural, morphological and optical properties of rare earth ions (RE3+=Sm3+ or Dy3+) activated Ca3Ga2Si3O12 (CaGaSi) phosphors synthesized by the sol-gel method are reported. XRD results confirmed the cubic phase structure of RE3+:CaGaSi phosphors. From the SEM images of RE3+:CaGaSi phosphors, it is observed that the particles are agglomerated. Photoluminescence spectra of Sm3+:CaGaSi phosphors have shown bright orange red emission at 598 nm (4G5/26H7/2) with an excitation wavelength of λexci=401 nm. In the case of Dy3+:CaGaSi phosphors bright yellow emission has been observed at 574 nm (4F9/26H13/2) with λexci=451 nm. From the PL spectral results, the rare earth ion concentration of CaGaSi phosphors is optimized.  相似文献   

9.
BaGd2ZnO5:Dy3+ phosphors were synthesized by a traditional solid-state reaction. The crystal structure of the phosphors was characterized by X-ray diffraction (XRD). The blue emission (456 nm) corresponding to 4H15/26H15/2 transition was observed at higher sample temperatures, and the population mechanism of 4H15/2 level was assigned to the thermal excitation of 4F9/2 level. The fluorescence concentration quenching of 4F9/2 level was studied based on Van Uitert's model, and that the electric dipole–dipole interaction was confirmed to be the responsible mechanism for the energy transfer between Dy3+ ions. Finally, the fluorescence thermal quenching of 4F9/2 level was studied, and the crossover effect was found to be the main physical mechanism for the fluorescence temperature quenching of Dy3+.  相似文献   

10.
SrAl_2B_2O_7:Dy~(3+)材料的制备及其发光性能   总被引:1,自引:0,他引:1       下载免费PDF全文
杨志平  马欣  赵盼盼  宋兆丰 《物理学报》2010,59(8):5387-5391
采用高温固相法制备了SrAl2B2O7:Dy3+发光材料.在350nm紫外光激发下,测得SrAl2B2O7:Dy3+材料的发射光谱为一个多峰宽谱,主峰分别为480,573和678nm;分别和Dy3+的4F9/2→6H15/2,4F9/2→6H13/2,4F9/2→6H11/2的跃迁发射相对应;监测573nm的发射峰,得到材料的激发光谱为一个多峰宽谱,主峰分别为295,325,350,365,400nm.研究了Dy3+掺杂浓度对SrAl2B2O7:Dy3+材料发射光谱的影响,随着Dy3+掺杂浓度的增大,SrAl2B2O7:Dy3+材料的Iy/Ib逐渐增大,根据Judd-Ofelt理论解释了其原因.随着Dy3+掺杂浓度的增大,Dy3+的4F9/2→6H13/2跃迁产生的573nm发射峰强度先增大,在4%时达到最大值,之后减小,其自身的浓度猝灭机理为电偶极-电偶极相互作用.不同的电荷补偿剂Li+,Na+,K+的引入均使发光强度得到提高,尤其以Li+最佳,发光强度提高了大约33%.  相似文献   

11.
Ce3+ and Dy3+ activated Li2CaGeO4 phosphors were prepared by a solid-state reaction method, and characterized by XRD (X-ray diffraction) and photoluminescence techniques. The characteristic emission bands of Dy3+ due to 4F9/26H15/2 (blue) and 4F9/26H13/2 (yellow) transitions were detected in the emission spectra of Li2CaGeO4:Dy3+. Ce3+ broad band emission was observed in Li2CaGeO4:Ce3+ phosphors at 372 and 400 nm due to 5d→4f transition when excited at 353 nm. Co-doping of Ce3+ enhanced the luminescence of Dy3+ significantly and concentration quenching occurs when Dy3+ is beyond 0.04 mol%. White-light with different hues can be realized by tuning Dy3+ concentration in the phosphors.  相似文献   

12.
The new trivalent dysprosium activated X6AlP5O20 (where X=Sr, Ba, Ca and Mg) phosphors were prepared by the combustion method. The prepared phosphors are characterized by XRD, photoluminescence and SEM techniques. Excited by 350 nm near-ultraviolet (NUV) light, the phosphors show an efficient blue and yellow band emissions, which originates from the 4F9/26H15/2 and 4F9/26H13/2 transitions of Dy3+ ion, respectively. The excitation spectra of the phosphors are broadband extending from 340 to 400 nm, which are characteristics of NUV excited LED. The effect of the Dy3+ concentration on the luminescence properties of X6AlP5O20:Dy3+ (where X=Sr, Ba, Ca and Mg) phosphors is studied. Ca6AlP5O20 phosphors show strong PL emission intensity around 25 times more as compared to Ba6AlP5O20, Sr6AlP5O20 and Mg6AlP5O20 phosphors. The investigated prepared phosphors are suitable for a NUV excited LED.  相似文献   

13.
崔彩娥  王森  黄平 《物理学报》2009,58(5):3565-3571
采用溶胶凝胶法制备了Sr3Al26:Eu2+,Dy3+红色长余辉发光材料,利用X射线衍射仪对材料的物相进行了分析,结果表明,1200℃下制备的样品的物相为Sr3Al26,少量的Eu和Dy掺杂没有影响样品的相组成.采用荧光分光光度计、照度计测定了样品的发光特性.结果表明Sr3Al2关键词: 红色长余辉 3Al26')" href="#">Sr3Al26 溶胶凝胶法  相似文献   

14.
This paper reports the luminescence potential of the dysprosium ion (Dy3+)-doped (varying contents from 0.1 to 1.0 mol%) magnesium borate glasses prepared by the melt-quenching method. As-quenched samples were characterized systematically to determine the effects of various Dy3+ contents on their structure, physical and optical traits. The Judd−Ofelt (J−O) intensity parameters (Ω2, Ω4, Ω6) and radiative properties of the best sample (with 0.7 mol% of Dy3+ doping) was evaluated to complement the experimental optical data. The studied glasses revealed three luminescence emission peaks at 382 nm (4F9/26H15/2, intense Blue), 572 nm (4F9/26H15/2, intense Yellow) and 661 nm (4F9/26H11/2, weak Red) under the excitation wavelength of 347 nm. The emission intensity was first increased up to the Dy3+ content of 0.7 mol% and then quenched. The observed luminescence intensity quenching was due to the resonant energy transfer from the excited state to the neighbouring ground state of Dy3+. The obtained high value of Ω2 signified the strong degree of covalency between the Dy3+ and ligand environment. The optimum glass sample (with 0.7 mol% of Dy3+) showed higher values of the branching ratio and stimulated emission cross-cross section for the 4F9/26H15/2 (yellow) emission transition, indicating its potential as bright yellow luminescent material and high gain visible laser applications.  相似文献   

15.
Photoluminescence studies of pure and Dy3+, Eu3+ doped Sr2CeO4 compounds are presented by oxalate precipitation method for solid state lighting. The prepared samples also characterized by XRD, SEM (EDS) and FTIR spectroscopy. The pure Sr2CeO4 compound displays a broad band in its emission spectrum when excited with 280 nm wavelength, which peaks centered at 488 nm, which is due to the energy transfer between the molecular orbital of the ligand and charge transfer state of the Ce4+ ions. Emission spectra of Sr2CeO4 with different concentration of Dy3+ ions under near UV radiation excitation, shows that intensity of luminescence spectra is found to be affected by Dy3+ ions, and it increases with adding some percentages of Dy3+ ions. The maximum doping concentration for quenching is found to be Dy3+?=?0.2 mol % to Sr2+ions. The observed broad spectrum from 400 to 560 nm is mainly due to CT transitions in Sr2CeO4 matrix and some fractional contribution of transitions between 4F9/26H15/2 of Dy3+ ions. Secondly the effect of Eu3+ doping at the Sr2+ site in Sr2CeO4, have been studied. The results obtained by doping Eu3+ concentrations (0.2 mol% to 1.5 mol%), the observed excitation and emission spectra reveal excellent energy transfer between Ce4+ and Eu3+. The phenomena of concentration quenching are explained on the basis of electron phonon coupling and multipolar interaction. This energy transfer generates white light with a color tuning from blue to red, the tuning being dependent on the Eu3+ concentration. The results establish that the compound Sr2CeO4 with Eu3+?=?1 mol% is an efficient “single host lattice” for the generation of white lights under near UV-LED and blue LED irradiation. The commission internationale de I’Eclairage (CIE) coordinates were calculated by Spectrophotometric method using the spectral energy distribution of prepared phosphors.  相似文献   

16.
YAlO3: Sm3+ phosphor has been synthesized by the solid state reaction method with calcium flouride used as a flux. The resulting YAlO3: Sm3+ phosphor was characterized by X-ray diffraction (XRD) technique, Fourier transmission infrared spectroscopy (FTIR), photoluminescence . . PL excitation spectrum was found at 254,332,380,400,407, 603 and 713 nm. Under excitation of UV(713 nm) YAlO3: Sm3+ (0–3 %) broad band emission were observed from 400 to 790 nm with a maximum around 713 nm of YAlO3 host lattice accompanied by weak emission of Sm3+ (4G5/26H5/2, 6H7/2,6H9/2) transitions. The results of the XRD show that obtained YAlO3: Sm3+ phosphor has a orthorhombic structure. The study suggested that Sm3+ doped phosphors are potential luminescence material for laser diode pumping and inorganic scintillators.  相似文献   

17.
Results of detailed spectroscopic investigation of Sm3+ and Dy3+ ions incorporated in crystal structures of Yal YAl3(BO3)4, LiNbO3, Gd3Ga5O12, Gd2SiO5, Lu2SiO5 and (Gd, Lu)2SiO5 are reported and discussed. The impact of the hosts on transition intensities and excited state relaxation dynamics of incorporated luminescent ions was examined. Distribution of luminescence intensity among spectral bands in terms of luminescence branching ratios was evaluated based on numerical integration of luminescence bands. Intensities of UV and blue absorption bands potentially useful for optical pumping were determined quantitatively in units of absorption cross section. The most intense luminescence bands related to potential laser transitions 4 G 5/26 H 7/2 of Sm3+ around 600 nm and 4 F 9/26 H 13/2 of Dy3+ around 580 nm were calibrated in units of emission cross section. Evaluated peak values of emission cross section range from 0.43 × 10?20 cm2 for Sm3+ in (Gd, Lu)2SiO5 to 1.17 × 10?20 cm2 for Sm3+ in LiNbO3. Those for dysprosium-doped crystals range from 0.63 × 10?20 cm2 for LiNbO3:Dy3+ to 2.0 × 10?20 cm2 for Yal YAl3(BO3)4:Dy3+. It follows from these considerations that samarium-doped crystals show promise for laser application owing to the combination of a strong absorption that matches radiation of commercial laser diodes emitting near 405 nm and long luminescence lifetime. Major shortcoming of dysprosium-doped crystals results from a weak intensity of absorption bands available for optical pumping near 450 nm and 385 nm combined with relatively strong self-quenching of luminescence.  相似文献   

18.
Lead telluroborate (PTBDy) glasses doped with different Dy3+ ion concentrations were prepared by melt quenching technique and investigated through optical absorption, fluorescence and decay measurements. The Judd–Ofelt intensity parameters (Ωλ) are obtained by a least square fit analysis. The small root mean square deviation of ±0.34×10?6 shows a good fit between the experimental and calculated oscillator strengths. The radiative properties of the 4F9/26H13/2 emission transition of PTBDy10 glass are determined and compared to the other reported glasses. The variation of decay time of the 4F9/2 emission state is attributed to the interaction among the excited Dy3+ ions at higher concentration. The PTBDy10 glass is found to be a suitable candidate for solid state laser materials to produce intense yellow (576 nm) luminescence through the 4F9/26H13/2 transition.  相似文献   

19.
Oxynitride phosphor powders comprising of CaSi2O2N2 doped with Tb3+ were successfully synthesized using a high-temperature solid-state reaction method. The experimentally determined photoluminescence (PL) properties of the produced phosphors meet the requirements of 2D/3D plasma display panels (PDPs). In particular, under the excitation of vacuum ultraviolet (VUV) synchrotron radiation and ultraviolet (UV) irradiation, emission peaks corresponding to the 5D37FJ (J=6, 5, 4, 3) and 5D47FJ (J=6, 5, 4, 3) transitions of Tb3+ ions were recorded. Monitoring the 5D47F5 emission of Tb3+ at 545 nm, the excitation bands were assigned to the host-related absorption as well as the 4f–5d (fd) and the 4f–4f (ff) transitions of Tb3+. The produced phosphors can be efficiently excited at 147 nm, and have an adequately short decay time (τ1/10=1.14 ms).  相似文献   

20.
The cationic surfactants assisted ultrasound route was used to prepare Dy3+ doped Zn2SiO4 nanophosphors. The final products were characterized by powder X-ray diffraction (PXRD), ultraviolet visible spectroscopy, scanning electron microscopy, transmission electron microscopy and photoluminescence. Orthorhombic phase of Zn2SiO4:Dy3+ (JCPDS card No. 35-1485) was confirmed from PXRD. It was evident that the morphology of spherical and broom like structures were obtained with epigallocatechin gallate (EGCG) and cetyltrimethylammonium bromide (CTAB) surfactants respectively. Further the size and agglomeration of the products were varied with surfactants concentration, sonication time, pH and sonication power. The probable formation mechanisms to obtain various micro/nano superstructures were discussed. The characteristic PL peaks were observed at 484, 574 and 666 nm due to the electronic transitions 4F9/2  6Hj (j = 15/2, 13/2, 11/2) of Dy3+ ions upon excited at NUV pumping wavelength of 350 nm [6H15/2  6P7/2 (4M15/2)]. The Judd–Ofelt intensity parameters and radiative properties were estimated by using PL emission data. The photometric studies indicated that the obtained phosphors could be promising materials in white light emitting diodes (wLED’s). The present synthesis route was rapid, environmentally benign, cost-effective and useful for industrial applications such as solid state lighting and display devices.  相似文献   

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