Effect of different dopants on the long lasting phosphorescence behavior of CaTiO_3：Pr~（3＋）

In order to improve the luminescence properties of CaTiO3:Pr3+, a series of CaTiO3:Pr3+, such as CaTi0.97Nb0.03O3:Pr3+, Ca0.8Zn0.2TiO3: Pr3+, Ca0.8Zn0.2Ti0.97Nb0.03O3:Pr3+ and B3+-doped Ca0.8Zn0.2Ti0.97Nb0.03O3: Pr3+ were prepared through conventional solid state reaction method. The results of the photoluminescence excitation and emission spectra showed that all the samples emitted red phosphorescence at 612 nm originating from 1D2 to 3H4 emission of Pr3+ under the 337 nm excitation. When examined by the X-ray diffraction (XRD), all the samples presented a predominant phase of CaTiO3 (JCPDS# 42-423) except Zn2+-doped samples which also revealed another phase of Zn2Ti3O8 (JCPDS# 73-579). The results of the afterglow decay curves showed that co-doping Zn2+ ions, Nb5+ ions or adding a small amount of B3+ into Ca0.8Zn0.2Ti0.97Nb0.03O3:Pr3+ were effective in improving the photoluminescence properties of CaTiO3:Pr3+ phosphor. Thermoluminescence results showed that the trap existing in all the samples was the same as in CaTiO3:Pr3+ and doping singly Nb5+ or Zn2+ hardly changed the trap depth but co-doping Nb5+ and Zn2+ could modify the trapping level from 0.63 to 1.26 eV distinctively. In addition, adding a certain amount of B3+ into CTO-PZN could also deepen the trap depth.     

Effect of electron traps on long afterglow behavior of Sr3Al2O6:Eu0.012+,Dy0.02-x3+,Hox3+

The long persistent phosphors Sr3Al2O6:Eu0.012+,Dy0.02-x3+,Hox3+ (x=0, 0.01, 0.02) were prepared by a high temperature solid state reaction. All samples showed a broad band emission peaking at ~510 nm, which could be ascribed to Eu2+ transition between 4f65d1 and 4f7 electron configurations. With the increase of substitution of Ho3+ ions for the Dy3+ ions in the as-prepared phosphors Sr3Al2O6:Eu0.012+,Dy0.02-x3+,Hox3+ (x=0, 0.01, 0.02), the initial intensity of the afterglow obviously decreased. From the thermoluminescence (TL) curves of the samples, we concluded that codoped Ho3+ ions led to a decline of the trap depth and redistribution of the trap. This may be responsible for the change of afterglow of Sr3Al2O6:Eu0.012+,Dy0.02-x3+,Hox3+ (x=0, 0.01, 0.02).     

Luminescence properties of Mn2） ions doped Lu2CaMg2Si3O1） garnet phosphors

Yttrium aluminum garnet structure phosphors Lu2CaMg2Si3O12:Mn2+ were synthesized by conventional high temperature solid-state reaction in reductive atmosphere. The structure and optical properties of samples were characterized by application of powder X-ray diffraction (XRD) and photoluminescence spectroscopy. Results of X-ray diffraction (XRD) analysis showed that the phosphors mainly presented garnet structure with a few weak peaks of impurity phases. Lu2-xCaMg2Si3O12:xMn2+ (x=0.01-0.8) phosphors showed a broad emission band peaking at around 590 nm under ultraviolet (UV) light of 408 nm when Mn2+ concentration was less than 0.08 mol. With an increase in the Mn2+ concentration (above 0.08), another broad emission band peaking at 720 nm besides 590 nm was observed, which may be due to manganese ion having different valence and occupying different host lattice. The critical quenching concentrations of manganese ion in the wavelength of 590 and 720 nm were about 0.06 and 0.2 mol, respectively. With 408 nm excitation wavelength, emission color of the samples had a red shift trend as the Mn2+ concentration increased. All the results indicated that the Lu2CaMg2Si3O12:Mn2+ phosphors could be applicable to n-UV based white LEDs.     

(Zn, Ca) Solid-Solution Behavior and Its Effect on Luminescence Properties in Ca1- xZnx TiO3: 0.002Pr3+ Phosphors

Nominal composition of Ca1 - xZnxTiO3: 0. 002Pr3 ( x = 0. 000 ～ 0. 200) phosphors were prepared by conventional solid reaction route. XRD and PL measurements were used to investigate the solid-solution structure and luminescence properties of Zn-doped Ca1- xZnxTiO3:0. 002Pr3 phosphors. The effect of solid-solution structure formed by substitution between Ca2 and Zn2 ions on the luminescent properties was analyzed. The results reveal that, with the increase of Zn substitution content below 0.010, lattice parameters and the intensity of excitation peak at both 260 and 330 nm as well as the corresponding 610 nm emission intensity are monotonously decreased quickly in a similar tendency. Also, the evolution of luminescence intensity and crystal cell parameters against Zn doping concentration are in good agreement.Above results are closely related with the structure change within Ca1- xZnxTiO3:0. 002Pr3 solid-solution phase formed by the Zn ions substitution for the Ca sites. Present study reveals that the solid-solution structure formed by substitution between Ca2 and Zn2 ions has significant effect on the luminescence properties of single phase Ca1- xZnxTiO3:0.002Pr3 phosphors.     

微波辅助均相沉淀法制备（Y1-x-y, Lay）2O3:xEu3+红色荧光粉

用微波辅助均相沉淀法制备了一系列（Y_1-x-y, La_y）₂O₃:xEu3+(x=0.01~0.05, y=0.05~0.25) 红色荧光粉.研究Eu3+、La3+的掺杂浓度和煅烧温度对荧光粉性能的影响.通过差热分析仪、红外光谱仪、XRD、SEM和荧光分光光度计,对前驱体热重曲线和FTIR曲线、样品的晶体结构、表面形貌及颗粒大小和荧光性能进行表征.结果表明:前驱体组成为 (Y, La, Eu) OHCO₃·nH₂O;所制备样品为立方晶系;SEM显示荧光粉为均匀分散的球形颗粒,粒度为200 nm左右;较为适宜的焙烧温度为900 ℃;La3+掺杂含量y=10 %, Eu3+掺杂含量x=3 %时,样品荧光粉发光性能最好,最大发射波长为614 nm,对应的是Eu3+的5D₀→7F₂跃迁;样品的色坐标为 (0.654, 0.346).所制备的（Y_1-x-y, La_y）₂O₃:xEu3+荧光粉具备较好的发光强度与色纯度.      

Photoluminescence properties of Ce3+ doped YSiO2N blue-emitting phosphors

Oxonitridosilicate phosphors with compositions of Y 1-x Ce x SiO 2 N (x=0-0.1) were synthesized by a new synthetic route based on a solid state reaction among YSi, CeSi, SiO 2 and Y 2 O 3 compounds at high temperature and high pressure. The photoluminescence properties dependent on Ce concentration and temperature were investigated. Concentration quenching occurred when the doped Ce 3+ concentration was more than 3 mol.%. The emission spectra showed red shifts from 430 to 447 nm with the increased Ce concentration from 0.5 mol.% to 10 mol.%. The quenching temperature was estimated as ～380 K. The chromaticity coordinates of the excitation and emission spectra were stable against the temperature. This study showed these YSiO 2 N:Ce 3+ phosphors the potential applications in the three-RGB phosphor-converted white LEDs.     

Properties of red-emitting phosphors Sr2MgSi2O7:Eu3+ prepared by gel-combustion method assisted by microwave

Novel red-emitting phosphors Sr2MgSi2O7:Eu3+ were prepared by gel-combustion method assisted by microwave. The phase struc-ture and luminescent properties of as-synthesized phosphors were investigated by XRD and fluorescence spectrophotometer, respectively. The results showed that the as-synthesized sample was Sr2MgSi2O7 with tetragonal crystal structure. The excitation spectrum of Sr2MgSi2O7:Eu3+ was composed of two major parts: one was the broad band between 200 and 350 nm, which belonged to the charge transfer of Eu3+-O2-; the other consisted of a series of sharp lines between 350 and 450 nm, ascribed to the f-f transition of Eu3+. The emission spec-trum consisted of two emission peaks at 593 and 616 nm, which was attributed to 5D0→7F1 and 5D0→7F2 of Eu3+, respectively. The concen-tration of Eu3+ (x) had great effect on the emission intensity of Sr2-xMgSi2O7:Eu3+x. When x varied in the range of 0.04-0.18, the intensity of emission peaks at 593 and 616 nm increased gradually with the concentration of Eu3+ increasing. It was interesting that no concentration quenching occurred. Moreover, the luminescent intensity could be greatly enhanced with incorporation of charge compensator Li+ ions.     

Co-Precipitation Synthesis and Spectral Characteristics of Long Afterglow Phosphor Y2O2 S： Sm^3＋, Mg^2＋ , Ti^4＋

Y2O2S：Sm^3＋, Mg^2＋, Ti^4＋ phosphor was synthesized by co-precipitation method. The crystalline structure of all synthesized phosphors was investigated by XRD. The result showed that all synthesized phosphors had a hexagonal crystal structure, which was the same as Y2O2S. The emission spectrum and excitation spectrum were measured, and the effect of Sm^3 ＋ molar ratio on the spectra was discussed. The emission spectra of the phosphors showed three emission peaks due to typical transitions of Sm^3 ＋ （4G5/2→6HJ ,J = 5/2, 7/2, 9/2）, and the emission peaks at 606 nm was stronger than others. With the increase of Sm^3 ＋ molar ratio, the emission intensity was strengthened. The excitation peaks were ascribed to the representative energy transition 4f→4f of Ti^4＋ phosphor prepared by co-precipitation method was Sm^3＋ ions. The results indicated that the Y2O2S ： Sm^3＋ , Mg^2＋ , an efficient long afterglow phosphor.     

微波辅助液相沉淀法合成Ca(MoO4)1-x(WO4)x:Eu3+红色荧光粉

以尿素为沉淀剂，采用微波辅助液相沉淀法合成了类球状双基质Ca(MoO₄)_1-x(WO₄)_x:Eu3+红色荧光粉，通过采用XRD、SEM、荧光光谱(PL)等现代分析技术对荧光粉的结构、形貌及发光性能进行了表征.结果表明，制备的Ca(MoO₄)_1-x(WO₄)_x:Eu3+红色荧光粉晶型完整，纯度高，为白钨矿结构；掺杂WO₄2-离子后，CaMoO₄:Eu3+红色荧光粉的发光性能明显增强，当WO₄2-离子的掺杂量x=0.4时，在395 nm激发下，在616 nm处的主发射峰的发光强度达到最大，掺杂浓度过高时会出现浓度淬灭现象.其较优的煅烧温度为1 000 ℃，煅烧时间为4 h.      

Broadband downconversion in YVO4：Tm3＋,Yb3＋ phosphors

An efficient near-infrared (NIR) downconversion (DC) by converting broadband ultraviolet (UV) into NIR was demonstrated in YVO4:Tm3+,Yb3+ phosphors. The phosphors were extensively characterized using various methods such as X-ray diffraction, photoluminescence excitation, photoluminescence spectra and decay lifetime to provide supporting evidence for DC process. Upon UV light varying from 260 to 350 nm or blue light (473 nm) excitation, an intense NIR emission of Yb3+ corresponding to transition of 2F5/2→2F7/2 peaking at 985 nm was generated. The visible emission, the NIR mission and the decay lifetime of the phosphors of various Yb3+ concentrations were investigated. Experimental results showed that the energy transfer from vanadate group to Yb3+ via Tm3+ was very efficient. Application of the broadband DC YVO4:Tm3+,Yb3+ phosphors might greatly enhance response of siliconbased solar cells.     

作为白光LED用铕掺杂氟化镧红色荧光粉的制备与光谱性能研究

采用水热法制备具有单一相六方晶系的LaF₃:Eu3+纳米荧光粉.通过X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、光致发光光谱(PL)和荧光衰减曲线对LaF₃:Eu3+纳米荧光粉进行表征.LaF₃:Eu3+荧光粉的激发光谱主要由250 nm处的宽带(O2-→Eu3+的电荷转移跃迁)和一些尖峰(Eu3+ f-f跃迁)构成,其中位于近紫外区396 nm处有一较强的激发峰.通过发射光谱探测Eu3+在LaF₃晶体中的局部晶场环境.在298 K下激发光谱和发射光谱可知,在六方晶系的LaF₃纳米晶体中的Eu3+晶格位置从D_4h降至到C_2v,这是由于晶格变化所造成的.在396 nm激发下,观测到较优掺杂浓度为10%的LaF₃:Eu3+荧光粉在591 nm(5D₀→7F₁跃迁)处有强烈的红色发射峰.其发光性能表明,LaF₃:Eu3+红色荧光粉在近紫外发光二极管领域具有潜在的应用价值.      

Synthesis of Long Afterglow Phosphors MAl2O4:Eu2+, Dy3+(M=Ca, Sr, Ba) by Microemulsion Method and Their Luminescent Properties

Long afterglow phosphors MAl2O4:Eu2 , Dy3 (M=Ca, Sr, Ba) were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samples indicate that phosphors CaAl2O4:Eu2 , Dy3 and SrAl2O4:Eu2 , Dy3 are with monoclinic crystal structure and phosphor BaAl2O4:Eu2 , Dy3 is with hexagonal crystal structure. The wide range of excitation spectrum of phosphors MAl2O4:Eu2 , Dy3 (M=Ca,Sr,Ba) indicates that the luminescent materials can be excited by light from ultraviolet ray to visible light and the maximum emission wavelength of phosphors MAl2O4:Eu2 , Dy3 (M=Ca, Sr, Ba) is found mainly at λem of 440 nm (M=Ca), 520 nm (M=Sr) and 496 nm (M=Ba) respectively, the corresponding colors of emission light are blue, green and cyna-green respectively. The afterglow decay tendency of phosphors can be summarized as three processes: initial rapid decay, intermediate transitional decay and very long slow decay. Afterglow decay curves coincide with formula I=At-n, and the sequence of afterglow intensity and time is Sr＞Ca＞Ba.     

Preparation and Characterization of Red Luminescent Ca0.8Zn0.2TiO3: Pr3+, Na+ Nanophosphor

Nanophosphor with the nominal composition of Ca0.8Zn0.2TiO3∶Pr3 , Na (CZTOPN) was synthesized at relatively low temperature by the sol-gel method. Metal ions were dispersed by citric acid in ethylene glycol solvent and then react with Ti(OC4H9)4 to form sol and gel. The decomposition process of the precursor, and crystallization and particle size of CZTOPN were examined by thermal analysis (TG-DSC), powder X-ray diffraction (XRD), and scan election microscopy (SEM). Results of TG-DSC and XRD reveal that the composition of Ca0.8Zn0.2TiO3∶Pr3 , Na changes with the sintering temperature. SEM data indicate that the diameter of particles is under 50 nm even if the sintering temperature increases to 1000 ℃. In contrast to a solid state reaction, the excitation spectra of samples synthesized by the sol-gel method shift blue about 10 nm and the emission intensity at 617 nm increases significantly.     

Effect of gadolinium incorporation on optical characteristics of YNbO_4：Eu~（3＋） phosphors for lamp applications

Eu3+-doped (Y,Gd)NbO4 phosphor was synthesized by solid-state reaction for possible application in cold cathode fluorescent lamps. A broad absorption band with peak maximum at 272 nm was observed which was due to the charge transfer between Eu3+ ions and neighboring oxygen anions. A deep red emission at the peak wavelength of 612 nm was observed which could be attributed to the 5D0→7F2 transition in Eu3+ ions. The highest luminance for Y1-x-yGdyNbO4:Eux3+ under 254 nm excitation was achieved at Eu3+ concentration of 18 mol.% (x=0.18) and Gd3+ concentration of 8.2 mol.% (y=0.082). The luminance of Y0.738Gd0.082NbO4:Eu3+0.18 was higher than that of a typical commercial phosphor Y2O3:Eu3+ and the CIE chromaticity coordinate was (0.6490, 0.3506), which was deeper than that of Y2O3:Eu3+. The particle size of the synthesized phosphors was controlled by the NaCl flux and particle size as high as 8 μm with uniform size distribution of particles was obtained.     

白光LED用LaPO4:Eu3+红色荧光粉的合成与表征

利用水热法制备了性能稳定的红色荧光粉LaPO4:Eu3+,同时研究了不同的Eu3+浓度、煅烧温度对荧光粉发光性能的影响.通过X射线粉末衍射(XRD)和扫描电子显微镜(SEM)来表征荧光粉的晶体结构和颗粒大小及形貌;用激发光谱和发射光谱以及荧光衰减曲线来表征荧光粉的荧光性能.结果表明:未煅烧时前躯体主要是六方晶相LaPO4·0.5H2O,煅烧温度在900℃时,所制备样品为单斜相LaPO4:Eu3+;SEM图像显示5 at.%Eu3+掺杂LaPO4呈椭球形,颗粒长约为500 nm,宽约为300 nm.最大发射波长和激发波长分别为592 nm和393 nm,发射光谱中592 nm和612 nm的发射峰对应的是Eu3+离子的5D0→7F1和5D0→7F2跃迁.其荧光寿命为3.32 ms.     

Effects of Host Doping on Spectral and Long-Lasting Properties of Sm^3＋ -Doped Y2O2S

Gd- or Lu-doped long afterglow red phosphor Y2O2S：Sm^3＋ was synthesized using the high temperature flux fusion method. The obtained phosphors were analyzed using X-ray diffraction to determine the crystal structure, and the phase analyses show that the product is in single phase. The luminescence spectra and decay curve were measured on a Hitachi F-4500 fluorescence spectrophotometer. The decay time was determined on an ST-900PM weak light photometer. The analyses show that host doping of Lu improves both luminescence and decay time of the materials. The concentration of doped Lu and Sm was varied in order to determine the optimal condition and to synthesize the product with the best properties. The mechanism of the long afterglow was also briefly discussed.     

Mg~（2＋）,Ca~（2＋）,Ba~（2＋）离子部分取代对SrAl_2O_4：Eu~（2＋）,Dy~（3＋）晶体结构和发光性能的影响

采用高温固相反应法制备了Sr0.9M0.1Al2O4：Eu2＋,Dy3＋（M=Mg,Ca,Ba）长余辉发光材料,并对其晶体结构、光谱性质、余辉特性进行了分析.X射线衍射测试结果表明,Mg2＋,Ca2＋,Ba2＋离子部分取代SrAl2O4基质中的Sr后,基质晶体结构并没有发生改变.光谱测试结果表明,Mg2＋,Ca2＋,Ba2＋取代后发光材料的激发光谱都是一个从250~450 nm范围内的宽激发带,在266nm,320nm,360nm,416 nm处各有一个激发峰.发射光谱中Mg2＋和Ba2＋的取代使波长出现蓝移,而Ca2＋的取代使波长出现红移.余辉测试结果表明,Ca2＋取代后的余辉时间长于Mg2＋和Ba2＋的取代.     

New red phosphor （Y, Gd, Lu）BO3： Eu^3＋ for PDP applications

Highly efficient phosphors under vacuum ultraviolet excitation are still demanded for the development of plasma display panels and Hg-free fluorescent lamps. The phosphors of Eu3+ doped (Y, Gd, Lu)BO3 were synthesized with solid state reaction method and the con-tents of Y3+, Gd3+, and Lu3+ for plasma display panel red phosphor were optimized under vacuum ultraviolet excitation. Two new potential candidates, which were (Y1-S-7TGdSLuT)BO3: Eu3+ (0相似文献   

Ba1-xSrxMgSiO4:Eu2+,Mn2+: A novel tunable single-matrix tricolor phosphor for W-LED

The Ba1-xSrxMgSiO4:Eu2+,Mn2+ phosphors were prepared by solid-state reaction. Their photoluminescence properties were inves-tigated with fluorescence spectrum and CIE chromaticity. The emission color of Eu2+ in Ba0.98-xSrxMgSiO4:0.02Eu2+ could be tuned from green to blue by adjusting the content of Sr2+. The blue emission of Eu2+ overlapped well with the excitation spectra of Mn2+, leading to an ef-ficient energy transfer from Eu2+ to Mn2+ in Ba0.98-xSrxMg1-ySiO4:0.02Eu2+,yMn2+. Ba0.93Sr0.03Mg1-ySiO4:0.02Eu2+,yMn2+ could emit three ef-ficient broad bands at 440, 530 and 640 nm. The emission color of Ba0.93Sr0.03Mg1-ySiO4:0.02Eu2+,yMn2+ could be tuned from greenish blue to yellowish white by increasing the content of Mn2+ from 0 to 0.1. By changing the content of Sr2+/Mn2+, white-light with different hues could be conveniently obtained in the Ba1-xSrxMgSiO4:Eu2+,Mn2+ phosphors. The results showed that Ba1-xSrxMgSiO4:Eu2+,Mn2+ is a promising single-phased tricolor phosphor in the fabrication of W-LED.     

溶胶-凝胶法制备Sr2SiO4:Tb3+绿色荧光粉及其发光性能

采用溶胶-凝胶法合成了一系列适合紫外-近紫外激发的(1-X)Sr₂SiO₄:XTb3+(X=0,0.01,0.02,0.03,0.04,0.05,0.06)绿色荧光粉,并采用X射线衍射(XRD)、扫描电子显微镜(SEM)和荧光光谱(PL)研究了样品的结构及发光性能.由XRD的检测结果可知,合成样品属于单斜晶系的β-Sr₂SiO₄相.由SEM图可知,所有样品都呈无规则块状结构.当监测波长为546 nm,样品的激发光谱的主峰位于370 nm处,属于Tb3+的4f-4f特征跃迁吸收.当激发波长分别为285 nm和250 nm,所有样品在488 nm,547 nm,586 nm,623 nm处都出现了1个强发射峰,分别对应Tb3+的5D₄→7F₆、5D₄→7F₅、5D₄→7F₄和5D₄→7F₃电子跃迁.最强发射峰位于547 nm处,呈现特征为绿光发射.随Tb3+掺杂量增大,发射强度呈现出先增大后减小的变化趋势,即存在浓度猝灭效应.当Tb3+掺杂量为X=0.03时,样品的发光强度最大.