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采用柠檬酸作燃烧剂用燃烧合成法制备了Gd2O3:Eu3+纳米晶.用X射线衍射仪(XRD)、高分辨透射电子显微镜(HRTEM)和荧光分光光度计等对Gd2O3:Eu3+纳米晶的结构、形貌和发光性能进行了分析.结果表明:不同柠檬酸与稀土离子配比(C/M)制备的样品经800℃ 退火1 h后,均得到了纯立方相的Gd2O3:Eu3+纳米晶,晶粒尺寸约为30 nm,尺寸分布较窄,其中以C/M=1.0时制备的纳米晶结晶性最好,发光强度最大.Gd2O3:Eu3+纳米晶主发射峰位置均在612 nm处 (5D0→7F2跃迁),激发光谱中电荷迁移态发生红移,观察到Gd3+向Eu3+的有效能量传递.对柠檬酸与稀土离子配比(C/M)对结晶度、发光性质等的影响也进行了分析和讨论. 相似文献
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采用传统固相法和水热法成功地制备出棒状La2Zr2O7:Eu3+荧光粉. 利用X射线粉末衍射仪、透射电镜和荧光光谱仪等分析了产物的结构、形貌和发光特性. 结果表明红色荧光粉La2Zr2O7:Eu3+有良好的晶相,属于立方结构,空间点群为Fd3m; 其形貌主要为纳米棒, 平均直径约47 nm, 长度为50~700 nm. 并对纳米棒的生长机理进行了探讨. 在466 nm蓝光激发下,La2Zr2O7:Eu3+荧光粉能发射出Eu3+的特征红色荧光,发射主峰位于616 nm处,归属于Eu3+的5DO→7F2超灵敏电偶极跃迁.此外,在产物的发射光谱中能够观察到5D1→7FJ (J=0, 1, 2)跃迁和5D1→7FJ (J=1, 2, 4)跃迁的劈裂峰,这说明Eu3+处在低对称性的晶体场格位中. 相似文献
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用高温固相法合成了Eu2+,Mn2+共激活的Ca2SiO3Cl2高亮度白色发光材料,并对其发光性质进行了研究. 该荧光粉在近紫外光激发下发出强的白色荧光,Eu2+中心形成峰值为419 nm和498 nm的特征宽带,通过Eu2+中心向Mn2+中心的能量传递导致了峰值为578 nm的发射,三个谱带叠加从而在单一基质中得到了白光. 激发光谱均分布在250—415 nm的波长范围,红绿蓝三个发射带的激发谱峰值分别位于385 nm,412 nm,370 nm和396 nm处,可以被InGaN管芯产生的紫外辐射有效激发. Ca2SiO3Cl2:Eu2+,Mn2+是一种很有前途的单一基质白光LED荧光粉. 相似文献
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三基色荧光粉中, 红色荧光粉性能较差, 为获得性能优良的红色荧光粉, 本文采用高温固相法合成了Eu2+, Cr3+单掺杂及共掺杂的碱土金属多铝酸盐MAl12O19 (M =Ca, Sr, Ba) 发光体. 实验表明, 在以上三种基质中均存在Eu2+→Cr3+的能量传递, 利用能量传递可以有效将Eu2+的蓝光或绿光转换为红光. 三种碱土金属多铝酸盐基质的晶体结构相似,但Eu2+, Cr3+发光受晶体场影响,导致在不同的基质中Eu2+, Cr3+间能量传递效率不同.通过光谱分析及能量传递效率计算发现, 相同掺杂浓度下,CaAl12O19中Eu2+→Cr3+的能量传递效率最高,SrAl12O19次之, BaAl12O19最低.红光转换率在CaAl12O19中最高. 相似文献
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为研究Yb3+离子浓度变化对Tm3+离子在蓝色波段荧光强度的影响,以NaF和La(NO3)3为原料,采用水热法制备了Tm3+和Yb3+共掺的Tm3+/ Yb3+∶LaF3纳米颗粒.用X射线衍射对LaF3纳米颗粒进行表征的结果显示,纳米晶体结构呈六方相.透射电镜的观测结果显示,纳米颗粒样品大小均匀、分散性良好.在波长为800 nm的激光激发下,观测到了上转换蓝光发射,其中包括波长为474 nm和479 nm的较强的荧光辐射(相应的跃迁为1G4→3H6)和波长位于450 nm的强度较弱的荧光发射(相应的跃迁为1D2→3F4).通过观测不同Yb3+离子浓度条件下共掺Tm3+/Yb3+∶LaF3样品的荧光光谱,研究了Yb3+离子掺杂浓度对于Tm3+离子的荧光发射的影响,并探讨了产生这种现象的原因.研究结果显示,对于1G4→3H6跃迁产生的荧光发射(474 nm),当Yb3+离子浓度增大时,反向能量传递速率的增加导致了荧光强度的增大.然而,当Yb3+离子浓度增大到一定程度时,Yb3+离子激发态能级寿命的减少将引发荧光强度的下降.相比较而言,Yb3+离子的浓度的变化对于1D2→3F4跃迁产生的位于450 nm处荧光强度的影响较弱. 相似文献
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Jong Seong Bae Kyoo Sung Shim Soung-soo Yi Young Soo Kim 《Applied Surface Science》2006,252(13):4564-4568
The influence of lithium doping on the crystallization, the surface morphology, and the luminescent properties of pulsed laser deposited Y2−xGdxO3:Eu3+ thin film phosphors was investigated. The crystallinity, the surface morphology, and the photoluminescence (PL) of films depended highly on the Li-doping and the Gd content. The relationship between the crystalline and morphological structures and the luminescent properties was studied, and Li+ doping was found to effectively enhance not only the crystallinity but also the luminescent brightness of Y2−xGdxO3:Eu3+ thin films. In particular, the incorporation of Li and Gd into the Y2O3 lattice could induce remarkable increase in the PL. The highest emission intensity was observed Li-doped Y1.35Gd0.6O3:Eu3+ thin films whose brightness was increased by a factor of 4.6 in comparison with that of Li-doped Y2O3:Eu3+ thin films. 相似文献
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V. Sudarsan 《Journal of luminescence》2010,130(8):1379-1383
Binary (ZnO)0.5(P2O5)0.5 glasses doped with Eu2O3 and nanoparticles of Gd2O3:Eu were prepared by conventional melt-quench method and their luminescence properties were compared. Undoped (ZnO)0.5(P2O5)0.5 glass is characterized by a luminescent defect centre (similar to L-centre present in Na2O-SiO2 glasses) with emission around 324 nm and having an excited state lifetime of 18 ns. Such defect centres can transfer the energy to Eu3+ ions leading to improved Eu3+ luminescence from such glasses. Based on the decay curves corresponding to the 5D0 level of Eu3+ ions in both Gd2O3:Eu nanoparticles incorporated as well as Eu2O3 incorporated glasses, a significant clustering of Eu3+ ions taking place with the latter sample is confirmed. From the lifetime studies of the excited state of L-centre emission from (ZnO)0.5(P2O5)0.5 glass doped with Gd2O3:Eu nanoparticles, it is established that there exists weak energy transfer from L-centres to Eu3+ ions. Poor energy transfer from the defect centres to Eu3+ ions in Gd2O3:Eu nanoparticles doped (ZnO)0.5(P2O5)0.5 glass has been attributed to effective shielding of Eu3+ ions from the luminescence centre by Gd-O-P type of linkages, leading to an increased distance between luminescent centre and Eu3+ ions. 相似文献
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Chengkang Chang Wen Li Xiaojun Huang Zhiyu Wang Xi Chen Xi Qian Rui Guo Yuelei Ding Dali Mao 《Journal of luminescence》2010,130(3):347-350
This paper reports the photoluminescence and afterglow behavior of Eu2+ and Eu3+ in Sr3Al2O6 matrix co-doped with Dy3+. The samples containing Eu2+ and Eu3+ were prepared via solid-state reaction. X-ray diffraction (XRD), photo luminescent spectroscope (PLS) and thermal luminescent spectroscope (TLS) were employed to characterize the phosphors. The comparison between the emission spectra revealed that Sr3Al2O6 phosphors doped with Eu2+, Dy3+ and Eu3+, Dy3+ showed different photoluminescence. The phosphor doped with Eu3+, Dy3+ showed an intrinsic f-f transition generated from Eu3+, with two significant emissions at 591 and 610 nm. However, the phosphor doped with Eu2+, Dy3+ revealed a broad d-f emission centering around 512 nm. After the UV source was turned off, Eu2+, Dy3+ activated Sr3Al2O6 phosphor showed excellent afterglow while Eu3+, Dy3+ activated phosphor almost showed no afterglow. Thermal simulated luminescence study indicated that the persistent afterglow of Sr3Al2O6: Eu2+, Dy3+ phosphor was generated by suitable electron traps formed by the co-doped rare-earth ions (Dy3+) within the host. 相似文献
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In this work, we report the high temperature solid-state synthesis of red phosphors Sr2MgSi2O7: Eu3+ with various Eu3+ concentrations. Their luminescent properties at room temperature are investigated. The X-ray diffraction patterns indicate that the red phosphors powder conforms to the tetragonal Sr2MgSi2O7. Impurity structure appears when more than 20% Eu3+ is doped. The samples show a strong emission line at 615 nm and the intensity increases with the increase of Eu3+ concentration until concentration quenching occurs. Charge compensation assists in the reduction of the impurity structure and vacancies; hence the luminescent intensity is enhanced. The decay measurement indicates that the lifetime of Eu3+ emission is about 2-3 ms. Some of the Eu3+ can be reduced to Eu2+; this is also discussed. 相似文献
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Eu,Ti co-doped Y2O2S:0.03Ti,0.03Eu phosphors and single Eu or Ti doped Y2O2S phosphors were prepared and their luminescent properties were investigated in detail by photoluminescence (PL) spectra, long afterglow spectra and thermoluminescence spectra measurements. The results showed that Y2O2S:Ti,Eu phosphors possess orange-red afterglow color with afterglow time above 5 h. The reddish afterglow color, which corresponds to a set of linear Eu3+ emissions at low-energy range (540-630 nm), was demonstrated to come from the energy transfer process from yellow Ti afterglow emissions, the proposed energy transfer mechanism may well explain the Eu3+ afterglow emission. 相似文献
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Zuoling Fu 《Journal of luminescence》2007,124(2):213-216
Y2O3:Eu3+ nanocrystals were prepared by combustion synthesis. The particle size estimated by X-ray powder diffraction (XRD) was about 10 nm. A blue-shift of the charge-transfer (CT) band in excitation spectra was observed in Y2O3:Eu3+ nanocrystals compared with bulk Y2O3:Eu3+. The electronic structure of Y2O3 is calculated by density functional method and exchange and correlation have been treated by the generalized gradient approximation (GGA) within the scheme due to Perdew-Burke-Ernzerhof (PBE). The calculated results show that the energy centroid of 5d orbital in nanocrystal has increasing trend compared with that in the bulk material. The bond length and bond covalency are calculated by chemical bond theory. The bond lengths of Y2O3:Eu3+ nanocrystal are shorter than those of the bulk counterpart and the bond covalency of Y2O3:Eu3+ nanocrystal also has an increasing trend. By combining centroid shift and crystal-field splitting, the blue-shift of the CT band is interpreted. 相似文献
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Fushan Wen Wenlian Li Taeun Kim Sanghoon Shin Jin Hyeok Kim 《Solid State Communications》2005,133(7):417-420
Sb3+-doped, Eu3+-doped and (Sb3+, Eu3+) co-doped YBO3 crystals have been synthesized using Y2O3, B2O3, SbCl3 and Eu2O3 as raw materials through a hydrothermal method. Phase-pure YBO3 crystal with hexagonal flake shape has been synthesized at 473 K for 3 days. The photoluminescent property of YBO3 with different activators were investigated using luminescent spectrometer at room temperature. The color of the (Sb3+, Eu3+) co-doped YBO3 crystal could be controlled from blue to red by changing the Sb3+/Eu3+ ratio in the initial reactants. The nearly white emission could be obtained through changing the Sb3+/Eu3+ ratio in reaction. 相似文献
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Dheeraj Jain 《Journal of luminescence》2009,129(5):439-3684
Zinc phosphate glasses doped with Gd2O3:Eu nanoparticles and Eu2O3 were prepared by conventional melt-quench method and characterized for their luminescence properties. Binary ZnO-P2O5 glass is characterized by an intrinsic defect centre emission around 324 nm. Strong energy transfer from these defect centres to Eu3+ ions has been observed when Eu2O3 is incorporated in ZnO-P2O5 glasses. Lack of energy transfer from these defect centres to Eu3+ in Gd2O3:Eu nanoparticles doped ZnO-P2O5 glass has been attributed to effective shielding of Eu3+ ions from the luminescence centre by Gd-O-P type of linkages, leading to an increased distance between the luminescent centre and Eu3+ ions. Both doped and undoped glasses have the same glass transition temperature, suggesting that the phosphate network is not significantly affected by the Gd2O3:Eu nanoparticles or Eu2O3 incorporation. 相似文献
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Nanostructured Gd2O3:Eu3+ and Li+ doped Gd2O3:Eu3+ thin films were prepared by pulsed laser ablation technique. The effects of annealing and Li+ doping on the structural, morphological, optical and luminescent properties are discussed. X-ray diffraction and Micro-Raman investigations indicate a phase transformation from amorphous to nanocrystalline phase and an early crystallization was observed in Li+ doped Gd2O3:Eu3+ thin films on annealing. AFM images of Li+ doped Gd2O3:Eu3+ films annealed at different temperatures especially at 973 K show a spontaneous ordering of the nanocrystals distributed uniformly all over the surface, with a hillocks (or tips) like self-assembly of nanoparticles driven by thermodynamic and kinetic considerations. Enhanced photoemission from locations corresponding to the tips suggest their use in high resolution display devices. An investigation on the photoluminescence of Gd2−xEuxO3 (x=0.10) and Gd2−x−yEuxLiyO3 (x=0.10, y=0.08) thin films annealed at 973 K reveals that the enhancement in luminescence intensity of about 3.04 times on Li+ doping is solely due to the increase in oxygen vacancies and the flux effect of Li+ ions. The observed decrease in the values of asymmetric ratio from the luminescence spectra of Li+ doped Gd2O3:Eu3+ films at high temperature region is discussed in terms of increased EuO bond length as a result of Li+ doping. 相似文献
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Y2O3:Eu3+ phosphor films have been developed by using the sol-gel process. Comprehensive characterization methods such as Photoluminescent (PL) spectroscopy, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy were used to characterize the Y2O3:Eu3+ phosphor films. In this experiment, the XRD profiles show that the Y2O3:Eu3+ phosphor films crystallization temperature and optimum annealing temperature occur at about 650 and 750 °C, respectively. The optimum dopant concentration is 12 mol% Eu3+ and the critical transfer distance (Rc) among Eu3+ ions is calculated to be about 0.84 nm. Vacuum environment is more efficient than oxygen and nitrogen to eliminate the OH content and hence yields higher luminescent phosphor films. The PL emission intensity of Y2O3:Eu3+ phosphor films is also dependent on the annealing time. It was found that the H2O impurities were effectively eliminated after annealing time of 25 s at 750 °C in vacuum environment. From the experiment results, the schematic energy band diagram of Y2O3:Eu3+ phosphor films is constructed. 相似文献