纳米YVO4:Ln(Ln=Eu,Tm,Dy)发光粉的研制及与相应块体发光粉的光谱对比

采用络合溶胶-凝胶法合成出3种YVO4∶Ln(Ln= Eu,Tm,Dy)纳米发光粉,并且对纳米YVO4∶Ln与自合成的块体YVO4∶Ln的红外光谱(FTIR),荧光光谱和X-射线衍射以及粒径的分布进行了对比研究.实验结果证明,当钒基稀土发光材料粒径达到纳米级以后,由于纳米粒子的一些特性,导致发光材料的光谱与块体材料相比有了较大的不同,出现了不同程度的蓝移现象.并且纳米发光材料的发光强度较块体发光材料的强度有一定程度的增强.     

蓝色长余辉发光材料CaAl2O4∶Eu2+, Dy3+的制备

用溶胶—凝胶法(Sol—gel)制备蓝色长余辉发光材料CaAl2O4∶Eu2+,Dy3+(CED),用差热分析(DTA)、红外光谱分析(IR)、X射线粉晶衍射(XRD)、荧光光度计对合成制备产物进行了系列分析测定,确定了制备的最佳条件,产物的激发波长为328nm,发射波长为440nm。     

燃烧法合成稀土纳米长余辉发光材料SrO·xAl2O3:Eu2+,Dy3+

应用燃烧法在空气中较低的温度(<900℃)下成功地合成了SrO·xAl2O3∶Eu2+,Dy3+稀土纳米长余辉发光材料,并研究了炉温、反应物中铝锶比、助溶剂和可燃物等对发光材料性能的影响。研究结果表明,反应物置于温度为600℃的高温炉中时燃烧得到的产物性能最好,发光粉的粒径在70nm左右,发射光谱的最大波长在520nm左右。与其它合成方法相比,该方法具有合成温度低、反应时间短,获得的产物疏松、硬度小、粒度小等优点。     

溶胶-凝胶法制备长余辉发光材料SrAl2O4:Eu2+,Dy3+的研究

用溶胶-凝胶法制备长余辉发光材料SrAl2O4∶Eu2+,Dy3+,选用柠檬酸合成前驱体柠檬酸盐,确定最佳烧结温度在1200～1250℃范围,比一般高温固相法制备该产物降低了200℃,其产物的发射光谱出现了明显"蓝移"现象.     

稀土离子(La3+,Eu3+)掺杂纳米TiO2的光催化性能

采用溶胶-凝胶法制备了Eu^3＋,La^3＋掺杂纳米TiO2粉体,并采用亚甲基蓝为目标降解物考察了稀土掺杂对TiO2光催化活性的影响。实验表明：适量的La^3＋掺杂可以提高TiO2的光催化活性,最佳掺杂浓度为0.3 mol%;La^3＋掺杂后降解反应符合一级反应动力学,H2O2的加入会使其反应速率大大提高;0.25 mol%Eu^3＋掺杂在日光灯下较紫外灯下显示出更好的光催化活性,这可能由于Eu^3＋掺杂导致了TiO2吸收光谱范围的整体红移;通过XRD图谱分析可以看出La^3＋、Eu^3＋掺杂均可以抑制TiO2的晶型转变,减小光催化剂的平均粒径,掺杂后其平均粒径均约为10 nm,TEM结果与XRD大致吻合。     

纳米晶稀土复合氧化物Dy_(1-x)Sr_xCoO_(3-y)低温形成机理研究

采用溶胶—凝胶工艺制备了纳米晶氧化物Ｄｙ１－ｘＳｒｘＣｏＯ３－ｙ，并对其低温形成机理进行了研究，结果表明：１００～２００℃柠檬酸配体变化不大；３００℃时配合物已开始分解，生成了单齿碳酸盐，同时形成了ＳｒＣｏＯ３－ｙ晶相骨架；４００℃晶化过程出现微区不均匀性；一级相变吉布斯自由能一阶偏微熵的改变，体现为结晶放热过程，整个晶化过程处于一种氧缺陷状态；７００℃时已形成纳米晶氧化物Ｄｙ１－ｘＳｒｘＣｏＯ３－ｙ，低于传统的合成温度。     

纳米粉末Ca_(0.8)Ba_(0.2)TiO_3:Pr的制备与表征

采用溶胶—凝胶法合成Ca0.8Ba0.2TiO3:Pr纳米粉末,分别应用XRD、SEM和荧光分光光度计对样品的结构、形貌和光学特性进行表征。结果表明,纳米粉末Ca0.8Ba0.2TiO3:Pr形状近似为球形,在900℃煅烧8h所得样品的激发主峰位于323nm,发射主峰在612nm处,对应Pr3+的1 D2→3 H4跃迁,并且,在900℃时样品的初始发光强度和余辉时间都是最高的。     

溶胶—凝胶法制备长余辉发光材料SrAl_2O_4∶Eu~(2 ),Dy~(3 )的研究

用溶胶—凝胶法制备长余辉发光材料 Sr Al2 O4 ∶ Eu2 ,Dy3 ,选用柠檬酸合成前驱体柠檬酸盐 ,确定最佳烧结温度在 12 0 0～ 12 5 0℃范围 ,比一般高温固相法制备该产物降低了 2 0 0℃ ,其产物的发射光谱出现了明显“蓝移”现象。     

CaMoO_4∶Eu~(3+),M~+(M=Li,Na,K)粉体的制备与发光性能研究

采用溶胶-凝胶法制备了Ca_(1-1.5x)MoO_4∶xEu~(3+)和Ca_(0.5)MoO_4∶0.25Eu~(3+),M~+(M=Li,Na,K)荧光粉,并对样品的物相结构、颗粒形貌及发光性能进行了分析。结果表明,样品属于四方晶系,颗粒接近八面体形状,大小为2~3μm。激发光谱显示,样品的激发中心分别位于364 nm、386 nm、396 nm、419 nm和466 nm,最大激发峰值位于396 nm。在396 nm近紫外光激发下,样品的发射中心分别位于596 nm、616 nm、656 nm、704 nm,特征发射峰为616 nm,Eu3+离子掺杂浓度为25%(体积分数)时发光强度最强,引入的3种电荷补偿剂M~+(M=Li,Na,K)中,Li+对发光强度的提高最为显著。     

燃烧法合成稀土纳米长余辉发光材料SrO·xAl2O3:Eu2+,Dy3+

应用燃烧法在空气中较低的温度(＜900℃)下成功地合成了SrO·xAl2O3∶Eu2+,Dy3+稀土纳米长余辉发光材料,并研究了炉温、反应物中铝锶比、助溶剂和可燃物等对发光材料性能的影响.研究结果表明,反应物置于温度为600℃的高温炉中时燃烧得到的产物性能最好,发光粉的粒径在70nm左右,发射光谱的最大波长在520nm左右.与其它合成方法相比,该方法具有合成温度低、反应时间短,获得的产物疏松、硬度小、粒度小等优点.     

Preparation and Luminescence of SrAi2O4:Eu2+, Dy3+ Nano-Particle

SrAl2O4: Eu2 , Dy3 nano-particle luminescence material was prepared by sol-gel method. Influences of synthesis conditions on the particle size and luminescence properties of SrAl2O4: Eu2 , Dy3 were studied. The synthesis process and the properties of the samples were analyzed by DTA, TGA, XRD, SEM. The result suggested that the formation of SrAl2O4: Eu2 , Dy3 sol is a slow heat release process beginning at 500 ℃ and peaking at 759 ℃.SrAl2O4: Eu2 ,Dy3 crystalline was formed at 1100 ℃. The luminescence properties of the SrAl2O4: Eu2 , Dy3 nanoparticle were compared with the conventional SrAl2O4: Eu2 , Dy3 particles. The average particle size of the product is about 30 nm. The excitation spectrum of the sample shows a broad band with peaks at 240, 330, 378 and 425 nm. The emission spectrum is a broadband spectrum with a peak at 523 nm.     

Luminescence of Eu^3 ＋ in LnAlO3 （Ln = Gd, Y） under UV and VUV Excitation

Single phases of LnAlO3 : Eu^3 ( Ln = Gd, Y ) were obtained by the process of evaporation of their nitric acid solution, and then pyrolysis of their nitrate salts. On monitoring by 613 nm emission, broad bands at around 270 and 170nm were observed in the excitation spectrum of Gd0.95Eu0.05AlO3. These peaks could be assigned to charge transfer (CT)transitions of Eu^3 -O^2- and Gd^3 -O^2- respectively. All the transitions observed in Gd0.95Eu0.05AlO3 are faithfully reproduced in the Y0.95Eu0.05AlO3, but with an exception of the ^8S7/2→^6I11/2 transition of Gd^3 . The 153 nm broad band could be the CT transition of Y^3 -O^2 - . Accordingly, the efficiency luminescence of (Gd, Y) BO3 : Eu^3 was explained as a result of CT transitions of Gd^3 -O^2- and Y^3 -O^2- under 147 nm excitation. Under VUV excitation, Gd0.95Eu0.05AlO3 exhibits a bright red luminescence with CIE chromaticity coordinates of (0.623, 0. 335) with a PL intensity of 30 of the commercial phosphor (Gd, Y) BO3 : Eu^3 (KX-504A). The PL spectrum of Y0.95Eu0.05AlO3 is similar to that of Gd0.95Eu0.05AlO3. Calculation of the color coordinates gives x = 0. 636, y = 0. 340 with a PL intensity of 50 of the (Gd, Y) BO3 : Eu^3 ( KX-504A) for Y0.95Eu0.05AlO3, and confirms that it has the appearance of pure spectral red, corresponding approximately to 608 nm. It can be concluded that LnAlO3:Eu^3 is a promising red VUV phosphor.     

Combustion synthesis and luminescence properties of LaPO4： Eu （5%）

Rare earth doped materials are an important type of phosphors due to their excellent performance such as stability at high tem-perature and light emission covering the entire visible domain. The combustion synthesis at acid pH of the monoclinic LaPO4: Eu(5%) pow-sis was followed by structure, morphology characterisation and luminescent properties of the obtained compound. The room temperature emission measurements under ultraviolet excitation at 254 nm were made for the emission transition 5D0→7FJ of this phosphor. The CIE (Commission Internationale de L'Eclairage) chromatic coordinates, dominant wavelength and colour purity were determined and compared to other luminescent materials obtained by other methods.     

Preparation and characterization of flower-like SrAl2O4:Eu2+,Dy3+ phosphors by sol-gel process

A flower-like Eu2+ and Dy3+ co-doped SrAl2O4 long-lasting phosphorescent (LLP) phosphor was synthesized via the inorganic- salt-based sol-gel method.The crystal structure,morphology and optical properties of the composite were characterized.X-ray diffraction diffu-sion (XRD) data and DSC-TG curves of the phosphor revealed that the SrAl2O4 crystallites have been formed after the precursor was calcined at 900 °C and to be single-phase SrAl2O4 at 1100 °C.The SEM photographs indicated that the sample exhibited ...     

Preparation of Anhydrous LnCl3(Ln=Eu, Er, Lu) by Chemical Vapor Transport

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Luminescence studies of MBrCl： Eu2＋ （M=Ca, Sr, Ba）

Europium doped MBrCl (M=Ca, Sr, and Ba) phosphors were prepared by solid state reaction in reductive atmosphere. Photolu-minescence (PL), photostimulated luminescence (PSL) after X-ray irradiation and optical absorption studies of MBrCl:Eu2+ (M=Ca, Sr, and Ba) revealed that: (1) blue light emission, under the excitation of 300 nm, was observed in all these phosphors; (2) the shape of the emission spectra in CaBrCl:Eu2+ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCl:Eu2+ and BaBrCl:Eu2+ showed no change; and (3) PSL was observed in SrBrCl:Eu2+ and BaBrCI:Eu2+ after X-ray irradiation. Difference absorption spectrum (DAS) in SrBrCl:Eu2+ showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCI:Eu2+ showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser (633 nm) or even semiconductor light-emitting diodes (LED) instead of gas lasers for photostimulation.     

Synthesis and photoluminescence studies of Ba(Gd,Ln)B9O16:Eu3+(Ln=La,Y) phosphors for n-UV LED lighting and display devices

BaGdB9O16:Eu3+ and Ba(Gd,Ln)B9O16:Eu3+(Ln=La, Y) phosphors were synthesized by solid state diffusion method. The X-ray diffraction, scanning electron microscopy(SEM) and photoluminescence properties were investigated. The as-synthesized BaGdB9O16:Eu3+ and Ba(Gd,Ln)B9O16:Eu3+(Ln=La, Y) phosphors showed strong red emission under ultraviolet light excitation. By partially substituting Gd3+ by La3+ and Y3+ ions in the host BaGdB9O16:Eu3+ materials, the maximum emission intensity was observed for the optimum composition of BaGd0.91La0.8B9O16Eu0.01 phosphor. The experimental results indicated that the Eu doped BaGdB9O16 and Ba(Gd,Ln)B9O16(Ln=La, Y) phosphors were promising red phosphors, which might find potential applications in near-UV excited LED lighting as well as display devices. Comparison of as-synthesized phosphors with standard phosphor used in CFL(compact fluorescent lamp) was also done. Energy transfer mechanism of Gd3+ to Eu3+ was also discussed in this paper.     

SrAl2O4:Eu, Dy Nanometer Phosphors Synthesized by Combustion Method

SrAl2 O4: Eu, Dy nanometer phosphors were synthesized by combustion method at 500 ～ 900℃, followed by heating the combustion sample at 1150℃ at a weak reductive atmosphere and nanometer phosphor with much better luminescent properties was obtained. The influences of the initiating combustion temperature, H3BO3 quantity, the mass ratio of urea and nitrate on the luminescent intensity of nanometer phosphors were studied. The optimum synthetic conditions were determined. The analysis results by transmission electron microscopy (TEM) indicate that the particle size of the synthetic product is less than 75 nm. The luminescent materials do not need to be ground. Their coating can be refined. It supplies a new approach to the rapid preparation of the luminescent materials at low temperature. The excitation and emission spectra indicate that the main peaks in the excitation and emission spectrum of nanometer phosphor synthesized by combustion method shifted to the short wavelength compared with the phosphor obtained by the solidstate reaction synthesis method. The reason of blue shift was explained. The afterglow decay results indicate that the decay speed of the afterglow for nanometer phosphor is faster than that obtained by the solid-state reaction method.