Ce和Dy在Cd0.5Zn0.5B4O7中的发光特性及能量双向传递

采用高温固相法制备了白蓝光双发射为一体的Cd0.5Zn0.5B4O7∶Ce/Dy系列发光材料. 由XRD测得Cd0.41Zn0.5B4O7∶Ce0.04/Dy0.02的晶胞参数: a=1.3885 nm, b=0.8020 nm, c=0.8670 nm, 属于正交晶系, Pbca空间群. 在Ce/Dy双掺的体系中存在Ce3+和Dy3+两种发光中心, 254~350 nm激发主要是Dy3+的 4F9/2→6H15/2和4F9/2→6H13/2跃迁发射, 而355—390 nm激发主要为Ce3+的5d→4f跃迁发射. 340 nm激发Ce/Dy双掺发光体的发射强度是同浓度Dy3+单掺的31倍, Ce3+是Dy3+的高效敏化剂, 而355—390 nm激发Dy3+是Ce3+的敏化剂. 体系中存在少见的Ce3+→Dy3+与Dy3+→Ce3+的能量双向传递.     

Spectroscopy and upconversion of Dy3+ doped in sodium zinc phosphate glass

Optical absorption and fluorescence spectra of Dy3+ doped in sodium zinc phosphate glasses have been reported. Judd-Ofelt theory has been applied to analyze the spectra and determine the optical parameters such as transition probabilities, radiative lifetime, stimulated emission cross-section, etc. The fluorescence intensity of Dy3+ corresponding to 4F9/2-->6H13/2 transition increases with increasing concentration of Dy3+ but at higher concentrations, concentration quenching is observed. The radiative lifetime of the 4F9/2 level at 1 mol% concentration of Dy3+ in this host is found to be 541 micros. Emission corresponding to 4F9/2-->6H13/2 transition (570 nm) is observed on excitation with NIR radiation due to upconversion. An attempt is made to explain this observation.     

一种上转换白光荧光粉的制备与发光性能研究

采用高温固相法制备了上转换白光荧光粉AlF3-YbF3:Er3+/Tm3+。通过XRD物相分析可知:上转换白光荧光粉AlF3-YbF3:Er3+/Tm3+是由三方AlF3相和正交YbF3相组成;利用发射光谱研究了该荧光粉的上转换发光性能,并且分析了当固定Er3+离子掺杂浓度时,Tm3+离子掺杂浓度对上转换白光荧光粉AlF3-YbF3:Er3+/Tm3+色度的影响,进而提出其上转换能量传递机制。结果表明:在980 nm激光激发下,波长为410 nm的紫光峰、550 nm的绿光峰和660 nm的红光峰分别对应于荧光粉中Er3+离子的2H9/2→4I15/2,4S3/2→4I15/2和4F9/2→4I15/2能级的跃迁,而波长为360 nm的紫外光峰、450 nm的蓝光峰、700 nm的红光峰,分别对应于荧光粉中Tm3+离子的1D2→3H6,1G4→3H6和1G4→3F4能级的跃迁,Er3+离子发出的光与Tm3+离子发出的光最终混合成色坐标为x=0.32,y=0.36的白光。此外,通过980 nm半导体激光器和EPM 2000 Dual-channel Joulemeter/Power meter测得该荧光粉最大上转换效率为6.90%。     

A facile synthesis and photoluminescence properties of water-dispersible Re3+ doped CeF3 nanocrystals and solid nanocomposites with polymers

Water-dispersible Re(3+) doped CeF(3) colloidal nanocrystals with well controllable morphology and high crystallinity have been successfully synthesized through a solvothermal process. The TEM images illustrate that the Re(3+) doped CeF(3) nanocrystals are rectangular (or cubic) with a mean diameter of ~10 nm. The excellent dispersibility in some of the polar solvents including water is achieved by using polyethyleneimine as the capping agent. The amine groups of the polymer chains on one hand bind to the nanocrystal surface; on the other hand the free ones could link to functional materials including bio-molecules. The CeF(3) nanocrystals doped with Tb(3+) and Dy(3+) ions show the characteristic emission of Tb(3+ 5)D(4)-(7)F(J) (J = 6-3, with (5)D(4)-(7)F(5) green emission at 542 nm as the strongest one) and Dy(3+ 4)F(9/2)-(6)H(15/2) (blue-green color at 478 nm) and (4)F(9/2)-(6)H(13/2) (yellow color at 571 nm) transitions, respectively. The energy transfer from Ce(3+) to Tb(3+) and Dy(3+) was also investigated in detail. In vitro studies of Re(3+) doped CeF(3) colloidal nanocrystals on HepG2 cells confirm their excellent biological compatibility. The obtained solid CeF(3)?: Tb(3+)/PDMS nanocomposites are very stable and flexible and exhibit strong green photoluminescence upon UV excitation.     

Emission analysis of Dy(3+):Ca(4)GdO(BO(3))(3) powder phosphor

Emission spectrum of Dy(3+):Ca(4)GdO(BO(3))(3) powder phosphor has been analyzed. Two emission bands at 492 and 588 nm with lambda(exci)=311 nm ((6)H(15/2)-->(4)L(19/2)) have been measured from this phosphor. For the intense yellow emission at 588 nm ((4)F(9/2)-->(6)H(13/2)), its lifetime has been measured. Emission performance of this phosphor has been explained in terms of an energy level diagram. Besides carrying out the emission analysis, XRD, SEM and FTIR studies have also been carried out in order to understand the nature and structural details of the optical material studied.     

GdAlO_3∶Tb,RE中Tb,RE的能量传递研究

采用柠檬酸盐硝酸盐燃烧法制备了GdAlO3∶Tb,RE荧光粉体.在紫外激发下(254nm),GdAlO3∶Tb发射绿色荧光(5D4→7F5,544nm),Dy共掺杂对绿色发光有增强作用,Ce共掺杂对GdAlO3∶Tb绿色发光有降低作用.激发谱和能谱研究表明:Dy能级嵌入Tb主发射能级5D4(绿色发光能级)、5D3(蓝色发光能级)能级之间,Ce能级嵌入Tb主发射能级5D4、5D3能级上方.这种能级嵌入方式,使得稀土离子之间存在声子支持的共振能量传递,但Tb→Dy→Tb能量传递使Tb绿色发射(5D4→7FJ(J=3,4,5,6))增强,蓝色发射(5D3→7FJ(J=3,4,5,6))减弱;而Ce→Tb能量传递使Tb蓝色发射增强,绿色发射减弱.     

Optical characterization of Sm3+ and Dy3+:ZnO-PbO-B2O3 glasses

Here, we present the results of the analysis of Sm(3+) or Dy(3+) (0.5 mol%) ions doped heavy metal oxide (HMO)-based zinc lead borate (ZLB) glasses. Optical measurements such as absorption, emission spectra, lifetimes, XRD, DSC profiles have been carried out. The emission spectrum of Sm(3+):ZLB has shown the emission transitions of (4)G(5/2)-->(6)H(5/2) (563 nm), (4)G(5/2)-->(6)H(7/2) (598 nm), (4)G(5/2)-->(6)H(9/2) (646 nm), (4)G(5/2)-->(6)H(11/2) (708 nm) with lambda(exc): 401 nm ((6)H(5/2)-->(4)F(7/2)). In the case of the Dy(3+):ZLB glass, emission transitions of (4)F(9/2)-->(6)H(15/2) (485 nm), (4)F(9/2)-->(6)H(13/2) (575 nm) and (4)F(9/2)-->(6)H(11/2) (664 nm) with lambda(exi): 447 nm ((6)H(15/2)-->(4)I(15/2)) have been identified. Energy level schemes relating to the emission mechanisms involved in Sm(3+) and Dy(3+) glasses have been given.     

一种新的橙红色长余辉荧光材料Y2O2S∶Sm3+

铜激活的硫化锌(ZnS∶Cu)和铕激活的硫化钙(CaS∶Eu)是最早获得应用的蓝色和红色长余辉材料. 随后, 相继发现了铝酸盐体系和硅酸盐体系两大类长余辉荧光材料[1～3]. 这两类长余辉荧光材料在发光亮度、余辉时间、稳定性方面都较前述硫化物系列长余辉荧光材料有很大提高, 从而具有非常广阔的应用前景和应用范围[4～6]. 但这两类长余辉荧光材料的发光颜色一般为蓝紫、蓝或黄绿, 没有红色发光现象. 随着研究的深入, 人们发现了稀土元素激活的碱土钛酸盐红色长余辉荧光材料, 这种荧光材料在发光亮度及余辉上都有明显的提高[7,8], 而且解决了硫化物不稳定的缺点. 近年来才发展起来的以碱土金属氧化物为发光基质, 以Eu3+为激活剂的红色长余辉荧光材料进一步提高了余辉亮度及时间[9].     

白光LED用黄色荧光粉Ba(Y1-0.5x-yAly)2S4:xHo3+的合成和发光特性

采用高温固相法合成了Ba(Y1-0.5x-yAly)2S4:xHo3+系列荧光粉。在465 nm蓝光激发下,荧光粉的发射光谱呈多谱带发射,主峰位于492、543和661 nm处,分别对应于Ho3+的5F3→5I8,(5S2,5F4)→5I8和5F5→5I8跃迁发射。研究了Ho3+和Al3+掺杂量对BaY2S4:Ho3+发光性能的影响。结果表明,随着Ho3+掺杂量的逐渐增大,荧光粉的发光颜色由绿色逐渐向红色转变;适量Al3+取代Y3+可以提高BaY2S4:Ho3+荧光粉的发光强度。荧光粉Ba(Y0.665Al0.3)2S4:0.07Ho3+在蓝光(465 nm)激发下发射黄光,是一种潜在的白光LED用黄色荧光粉。     

High-temperature High-pressure Hydrothermal Synthesis of Dy3＋-doped YNbO4 Single Crystal and Its Luminescence Properties

Single crystal Dy3＋ doped YNbO4phosphors were prepared via a high-temperature high-pressure hydrothermal procedure. Under excitation at 270 nm, the Dy3＋-doped YNbO4 phosphor shows bright white emission, which is composed of two strong bands at 492 and 576 nm corresponding to the characteristic 4F9/2→6H15/2 and aF9/2→6H13/2 transitions of Dy3＋, respectively. The dominant band was observed at 352 nm, which corresponds to the 6H15/2→6p7/2 transition of Dy3＋. Nearly white light was achieved at 2ex 270, 310 and 388 nm and the CIE（International Commission on Illumination） values were （0.3135, 0.3421）, （0.3088, 0.3380） and （0.3146, 0.3296）, respectively.     

Sr2SiO4∶Dy3+材料制备及发光特性

采用高温固相法制备了Sr2SiO4∶Dy3+发光材料. 在365 nm紫外光激发下, 测得Sr2SiO4∶Dy3+材料的发射光谱为一个多峰宽谱, 主峰分别为486, 575和665 nm; 监测575 nm的发射峰, 所得材料的激发光谱为一个多峰宽谱, 主峰分别为331, 361, 371, 397, 435, 461和478 nm. 研究了Dy3+掺杂浓度对Sr2SiO4∶Dy3+材料发射光谱强度的影响. 研究结果显示, 随着Dy3+浓度的增大, 黄、蓝发射峰比值(Y/B)也逐渐增大; 随着Dy3+浓度的增大, 575 nm发射峰强度先增大后减小. 加入电荷补偿剂Li+, Na+和K+均提高了Sr2SiO4∶Dy3+材料的发射光谱强度, 其中以Li+的情况最为明显.     

白色荧光粉NaGd（MoO4）2:Dy3+,Eu3+的水热合成及发光性能

采用谷氨酸辅助水热法合成了八面体形NaGd(MoO4)2:Dy3+,Eu3+白色荧光粉.X射线衍射结果表明,合成的样品为四方晶系的NaGd(MoO4)2纯相.扫描电子显微镜照片显示所制备的粒子为八面体形,各边长约为2μm.荧光光谱结果表明,在NaGd(MoO4)2:4%Dy3+,yEu3+(y=0,0.5%,0.6%,0.7%,0.8%,0.9%,1.0%)样品中,随着Eu3+掺入量的增加,Dy3+的发射峰逐渐减弱,而Eu3+的发射峰逐渐增强,说明Dy3+-Eu3+之间存在能量传递.通过色坐标图可知,当Eu3+掺杂量y=0.9%时,荧光粉的色坐标(0.338,0.281)与标准的白光色坐标(0.33,0.33)接近,表明NaGd(MoO4)2:4%Dy3+,0.9%Eu3+是很好的近紫外光激发下的白色荧光粉.     

Photoluminescence and energy transfer studies of Dy(3+)-doped fluorophosphate glasses

Dy(3+)-doped fluorophosphate glasses with composition (in mol%) (56-x/2)P(2)O(5)+17K(2)O+(15-x/2)BaO+8Al(2)O(3) + 4AlF(3)+ xDy(2)O(3), x=0.01, 0.05, 0.1, 1.0 and 2.0, have been prepared by melt quenching technique. The luminescence spectra and lifetimes of (4)F(9/2) level of Dy(3+) ions in these glasses have been measured using the 457.9 nm line of argon ion laser as an excitation source. The free-ion calculation and Judd-Ofelt analysis have been performed. The room temperature emission spectra corresponding to (4)F(9/2)-->(6)H(J) (J=7/2, 9/2, 11/2, 13/2 and 15/2) transitions of Dy(3+) ions were measured. The fluorescence decay from (4)F(9/2) level have been measured by monitoring the intense (4)F(9/2)-->(6)H(13/2) transition. The lifetime of the decay is obtained by taking the first e-folding times of the decay curves and is found to decrease with increase in Dy(3+) ions concentration due to concentration quenching. The decay curves are found to be perfectly single exponential for samples with low Dy(3+) ion concentration. The non-exponential decay curves observed for higher concentrations are well fitted to the Inokuti-Hirayama model for S=6, which indicates that the energy transfer between the donor and acceptor is of dipole-dipole nature. The energy transfer parameter and donor to acceptor interaction increases with Dy(3+) ions concentration due to increase of energy transfer from Dy(3+) (donor) to unexcited Dy(3+) (acceptor) ions.     

Reversible SC‐SC Transformation involving [4+4] Cycloaddition of Anthracene: A Single‐Ion to Single‐Molecule Magnet and Yellow‐Green to Blue‐White Emission

In search of magneto‐optic materials, the mononuclear compounds Ln^III(depma)(NO₃)₃(hmpa)₂ (Ln=Dy, Gd) were synthesized. The anthracene moieties undergo [4+4] dimerization when irradiated at 365 nm without loss of crystallinity. The Dy compound switches from a single‐ion to a single‐molecule magnet with doubling of the spin reversal barrier energy and from yellow‐green to blue‐white emission. The dimerization is reversed by heating at 100 °C or partially on light irradiating at 254 nm. The results suggest that lanthanide phosphonates with anthracene are promising smart materials displaying synergistic magneto‐optic property.     

Sr2MgSi2O7∶Tb3+，Li+荧光粉的合成和发光机理

采用高温固相法合成Sr2-mMg1-nSi2O7∶mTb3+,nLi+(m=0.03~0.50,n=m)系列荧光粉。使用X射线衍射仪和荧光光谱仪对样品的物相和发光性质进行了表征。在377 nm紫外光激发下,荧光粉的发射光谱呈多谱带发射,主峰位于490 nm,542 nm,590 nm和613 nm处,分别对应于Tb3+的5D4→7FJ(J=6,5,4,3)跃迁发射。调节Tb3+离子掺杂浓度,可实现荧光粉的发光颜色从蓝到白、黄、绿的可调发射;名义组成为Sr1.95Mg0.95Si2O7∶0.05Tb3+,0.05Li+的荧光粉在紫外光(377 nm)激发下发白光,其色坐标(0.322,0.317)接近纯白光(0.33,0.33),是一种潜在的LED用单基质白光荧光粉。     

Preparation, characterization and photoluminescence properties of BaB2O4: Eu3+ red phosphor

A new red emitting BaB2O4: Eu3+ phosphor was synthesized by solid-state reaction method. X-ray powder diffraction (XRD) analysis confirmed the monoclinic formation of BaB2O4. Field-emission scanning electron-microscopy (FE-SEM) observation indicated that the microstructure of the phosphor consisted of irregular grains with heavy agglomerate phenomena. Upon excitation with 394 nm light, the BaB2O4: Eu3+ phosphor shows bright red emissions with the highest photoluminescence (PL) intensity at 611 nm due to 5D0→7F2 transitions of Eu3+ ions. The CIE chromaticity coordinates are calculated from the emission spectrum to be x=0.64, y=0.35. The effects of the Eu3+ concentration on the PL were investigated. The results showed that the optimum concentration of Eu3+ in BaB2O4 host is 6 mol% and the dipole-dipole interaction plays the major role in the mechanism of concentration quenching of Eu3+ in BaB2O4: Eu3+ phosphor. The effect of charge compensation on the emission intensity was also studied. The charge compensations of Li+, Na+ and K+ anions all increased the luminescent intensity of BaB2O4: Eu3+. K+ anion gave the best improvement to enhance the intensity of the emission, indicating K+ is the optimal charge compensator. All properties show that this phosphor could serve as a potential candidate for application as a red phosphor for NUV chip LED.     

Synthesis, characterization and photoluminescence properties of CaSiO3:Eu3+ red phosphor

CaSiO3:Eu3+ (1-5 mol%) red emitting phosphors have been synthesized by a low-temperature solution combustion method. The phosphors have been well characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical spectroscopy. PXRD patterns reveal monoclinic CaSiO3 phase can be obtained at 900°C. The SEM micrographs show the crystallites with irregular shape, mostly angular. Upon 254 nm excitation, the phosphor show characteristic fluorescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 614 nm corresponding to 5D0→7F2 of Eu3+ ions, which is stronger than the magnetic dipole transition located at 593 nm corresponding to 5D0→7F1 of Eu3+ ions. Different pathways involved in emission process have been studied. Concentration quenching has been observed for Eu3+ concentration>4 mol%. UV-visible absorption shows an intense band at 240 nm in undoped and 270 nm in Eu3+ doped CaSiO3 which is attributed to oxygen to silicon (O-Si) ligand-to-metal charge-transfer (LMCT) band in the SiO3(2-) group. The optical energy band gap is widened with increase of Eu3+ ion dopant.     

镝与二甘醇酸的配位聚合物的水热合成、晶体结构及荧光性质

DyCl₃·6H₂O与二甘醇酸(H₂dga)在水热条件下反应得到配位聚合物{[Dy₂(dga)₃(H₂O)₄]·2H₂O}_n，用X-射线衍射单晶结构分析方法确定了其晶体结构。该配合物的晶体属于正交晶系，C222₁空间群。在配合物中，Dy³⁺离子存在两种类型的配位环境。九配位的Dy1离子与3个二甘醇酸根的6个羧基氧原子和3个醚氧原子配位，其配位多面体可描述为一个扭曲的单帽四方反棱柱;八配位的Dy2离子周围的8个配位氧原子形成一个扭曲的四方反棱柱配位多面体，其中4个氧原子来自4个二甘醇酸根，另外4个氧原子由4个配位水分子提供。二甘醇酸配体的2个羧基和其醚氧原子同时与Dy³⁺离子配位而形成2D网状结构。 该配合物在室温下的固体荧光光谱显示了中心Dy³⁺离子的特征荧光，位于483 nm和574 nm的发射峰分别对应于Dy³⁺离子的 ⁴F_9/2 → ⁶H_15/2和 ⁴F_9/2 → ⁶H_13/2跃迁。     

橙红色荧光粉BaZnP2O7∶Eu3+的制备与发光特性

采用高温固相法合成了BaZnP2O7∶Eu3+荧光粉, 并对其发光性质进行了研究.     

Visible luminescence of dysprosium ions in oxyhalide lead borate glasses

Visible luminescence of Dy(3+) ions in oxyhalide lead borate glasses was examined. Luminescence spectra show two intense bands at 480 nm and 573 nm due to (4)F(9/2)→(6)H(15/2) (blue) and (4)F(9/2)→(6)H(13/2) (yellow) transitions of Dy(3+). Luminescence decays from (4)F(9/2) state and yellow-to-blue luminescence intensity ratios (Y/B) were analysed with PbX(2) (X=F, Cl) content. An introduction of PbX(2) to the borate glass results in the increasing of (4)F(9/2) lifetime and the decreasing of yellow-to-blue luminescence intensity ratio, which is due to reduction of covalency between Dy(3+) and O(2-)/X(-) ions.