氟化物玻璃中Yb^3＋敏化稀土离子的上转换发光

研究了氟化物玻璃中Ｙｂ＾３＋敏化Ｐｒ＾３＋、Ｔｍ＾３＋、Ｅｒ＾３＋和Ｈｏ＾３＋产生的上转换发光,在波长为８８０ｎｍ光的激发下,Ｙｂ＾３＋敏化Ｐｒ＾３＋产生波长为４８２,５２０,５２９,６０５和６３５ｎｍ的荧光。     

上转换氟化物光纤激光器

氟化物玻璃是一种性能优异的激光基质材料。本文介绍了稀土离子上转换发光的机理和光纤顺的基本结构，综述了近几年来对掺Ｔｍ＾３＋、Ｐｒ＾３＋、Ｅｒ＾３＋、Ｈｏ＾３＋和Ｎｄ＾３＋的上转换氟化物光纤激光器的研究和应用概况。     

加入敏化离子C_r~（3＋）的RE：YAG晶体中能量转移

测量了Ｃｒ３＋和ＲＥ３＋（Ｔｍ３＋，Ｈｏ３＋，Ｎｄ３＋）共掺的ＹＡＧ晶体的吸收谱、荧光谱和Ｃｒ３＋的荧光衰减曲线．计算了Ｃｒ３＋向ＲＥ３＋能量转移的效率和速率．它是依Ｈｏ３＋、Ｎｄ３＋，Ｔｍ３＋递增的，提出比较能量转移效率大小的简便方法．     

Tm：YAG和Ho：YAG单晶光纤的光谱及Cr~（3＋）的敏化作用

测量了Ｔｍ３＋和Ｈｏ３＋离子的吸收谱以及Ｃｒ３＋离子在ＹＡＧ单晶光纤中的Ｒ荧光线的寿命．用Ｄｅｘｔｅｒ理论讨论了Ｃｒ３＋离子的能量转移效率。结果表明Ｃｒ３＋→Ｔｍ３＋的能量转移效率比Ｃｒ３＋→Ｈｏ３＋的大．     

高密度发光材料γ-Bi_2WO_6:Pr~(3 )的发光性质研究

研究了用固相法制备的高密度发光材料γ－Ｂｉ２ＷＯ６：Ｐｒ３＋的结构、光致发光光谱、激发谱和γ－Ｂｉ２ＷＯ６的漫反射谱．由实验测得它的晶格参数为α＝５．４５Ａ,ｂ＝１６．４２Ａ,ｃ＝５．４３Ａ,密度Ｄｘ＝９．５３ｇ／ｃｍ３．它的光致发光光谱主发射峰位于６００、６０８、６１１、６２９ｎｍ,分别来自于Ｐｒ３＋的１Ｄ２→３Ｈ４、２Ｐｏ→３Ｈ６、３Ｐｏ→３Ｈ６、３Ｐｏ→３Ｆ２跃迁的发射．其激发谱由位于约２２５～４３０ｎｍ范围内、最大值约在３７２ｎｍ的主激发带和４５０ｎｍ的激发峰组成;主激发带来自于基质,可能是基质的带间吸收、Ｗ－Ｏ间电荷迁移吸收和缺陷能级的吸收;４５０ｎｍ的激发峰来自于 Ｐｒ３＋的３Ｈ４→３Ｐ２跃迁吸收．ＢＷＯ：Ｐｒ３＋的最佳掺杂浓度为 ０．８ｍｏｌ％左右．     

微波快速合成硫化锶铜铋磷光体及Bi3+对Cu+的敏化发光

本文首次采用微波辐射法快速合成了以ＳｒＳ为基质,Ｃｕ、Ｂｉ＾３＋为共激活剂的箍余辉蓝绿色光致发光磷不体,其激发和发射主峰波长分别为２６７和５２１ｎｍ,工余辉时间约为０．５ｈ。系统考察了在单掺杂和双掺杂情况下的发光规律,发现Ｂｉ＾３＋与Ｃｕ＋之间存在着能量传递作用,且Ｂｉ＾３＋对Ｃｕ＾＋具有很强的敏化和猝灭效应。     

溶胶-凝胶法合成Y_3Al_5O_(12):Ce~(3 ),Tb~(3 )稀土荧光粉的研究

采用溶胶－凝胶法在低温下合成了 Ｙ３Ａｌ５Ｏ１２：０．０８Ｃｅ３＋; ０．１２Ｔｂ３＋稀土荧光粉．通过 Ｘ射线衍射（ＸＲＤ）分析及激发、发射光谱测试结果表明：合成的粉末为ＹＡＧ晶体结构,粉体 的最大激发峰为２７３ｎｍ,最大发射峰为５４５ｎｍ,色坐标为：ｘ＝０．３３１;ｙ＝０．５５８,在２７３ｎｍ的紫 外光激发下发出明亮的绿光．     

P2O3—B2O3—Al2O3—SrO—BaO玻璃中的Yb^3＋非辐射能量转移下E …

本文研究了共掺Ｅｒ＾３＋／Ｙｂ＾３Ｐ２Ｏ３－Ｂ２Ｏ３－Ａｌ２Ｏ３－ＳｒＯ－ＢａＯ玻璃的能量转移过程。实验中制备了高掺杂Ｂｂ＾３＋离子的双掺Ｅｒ＾＃＋／Ｙｂ＆＾３＋的磷酸盐玻璃样品。在Ｅｒ＾３＋／Ｙｂ＾３＋掺杂比率〉１：１８（ｍｏｌ％）时,观测到了基于Ｙｂ＾３＋离子至Ｅｒ＾３＋离子能量转移下Ｅｒ＾３＋（＾３Ｉ１３／２→＾４Ｉ１５／２）的增强发射和ｂ＾３＋（＾２Ｆ７１／→＾２Ｆ５／２）发射的减弱,当Ｂ     

不同稀土元素掺杂对钛酸钡陶瓷导电性的影响

采用溶胶－凝胶法制备了１４种稀土掺杂的ＢａＴｉＯ３超细粉体（ＲＥ＝Ｙ，Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｙｂ，Ｌｕ），用一般陶瓷工艺将这些超细粉体分别烧成了１４种稀土掺杂的ＢａＴｉＯ３陶瓷，测得了这些陶瓷体的电阻率并对Ｅｕ和Ｙｂ掺杂的ＢａＴｉＯ３陶瓷成绝缘体的原因进行了初步讨论。     

（Y，Zn，Sr）_3（P，VO_4）_2：Eu~（3＋），Bi~（3＋）发光性

合成了组成为（Ｙ，Ｚｎ，Ｓｒ）３（Ｐ，ＶＯ４）２：Ｅｕ３＋，Ｂｉ３＋的荧光材料，经射线结构分析确定为Ｚｎ３（ＰＯ４）２结构，属于单斜晶系，空间群为Ｐ２１／ｎ讨论了基质组成对Ｅｕ３＋离子发光性质的影响，用Ｙ３＋取代了一部分Ｚｎ２＋，用ＶＯ取代了一部分ＰＯ．由于基质的４３６ｎｍ发射与Ｅｕ３＋的激发态能级的能量重叠，Ｅｕ３＋产生较强的５９８ｎｍ和６１８ｎｍ发射．另外，掺入少量Ｂｉ３＋能增强Ｅｕ３＋发射．     

Multicolor up-conversion emissions of Tm3+/Er3+/Yb3+ tri-doped YF3 phosphors

Tm3+/Er3+/Yb3+ tri-doped yttrium fluoride (YF3) phosphors were prepared by a facile hydrothermal method. X-ray topographic analysis found that the phosphors were crystallized products. Their sizes and morphologies were characterized by scanning electron microscopy (SEM, Hitachi S-4800), which indicated that most of the YF3 phosphors were hundreds of nanometers in size. Up-conversion (UC) spectra were recorded under 980-nm diode laser excitation at room temperature with a fluorescence spectrometer (Hitachi F-4500). Plenty of UC emissions of Tm3+ and Er3+ were observed from ultraviolet to red. For Tm3+ ions, a five-photon process (approximately 291 nm and approximately 347 nm), a four-photon process (approximately 362 nm and approximately 452 nm), and a three-photon process (approximately 475 nm) were identified in the UC spectra. The UC emissions from the Er3+ were: approximately 380 nm, approximately 408 nm, approximately 521 nm, approximately 537 nm, and approximately 652 nm. Therefore, cyan-white light can be observed by the naked eye at 980-nm excitation, even under low excitation power density. By comparing the UC spectra of the phosphors annealed at different temperatures, we found that the intensity of the UC luminescence increased as annealing temperature increased. Furthermore, the spectral dependencies on Tm3+ doped concentrations were studied. The energy transfer processes and fluorescence dynamics in the tri-doped system are currently being investigated.     

Investigation on Yb3+∕Er3+∕Tm3+ tri-doped phosphate glass ceramic for white-light-emitting diode

Yb3+∕Er3+∕Tm3+ tri-doped phosphate glass ceramics were prepared by a high-temperature melting method and thermal treatment technology. Upconversion (UC) emissions of the Yb3+∕Er3+∕Tm3+ tri-doped phosphate glass ceramic samples were studied under 975 nm excitation. The glass ceramic samples can simultaneously generate blue, green, and red emissions. The multicolor emission obtained was tuned to white light by adjusting the Er3+ ion concentration. The emission color of the sample doped with 8 mol.% Er3+ ion is white to the naked eye, and CIE coordinates (x=0.316, y=0.354) of the sample are close to the standard equal energy white-light illumination (x=0.333, y=0.333). The material will be useful in developing the white-light-emitting diode.     

Intense red upconversion emission of Yb/Tm/Ho triply-doped tellurite glasses

By conventional melting and quenching methods, 3Yb2O3-0.2Tm2O3-xHo2O3 (wt%, x=0.2~1.2) was doped into an easily fiberized tellurite glass with composition of 78TeO2-10ZnO-12Na2O (mol%) to form YTH-TZN78 glasses. Under 976 nm excitation, the direct sensitizing effect of Yb ions (Yb→Ho) and indirect sensitizing and self-depopulating effects of Tm ions (Yb→Tm→Ho) were found to present intense red upconversion emission at 657 nm (Red, Ho:5F5→5I8) and were responsible for the absence of the usually observed 484 nm emission (Blue, Tm:1G4→3H36). Regardless of the dopant concentration of Ho ions, the intensity of the red emission at 657 nm (Red, Ho:5F5→5I8) is about three times stronger than that of the green one at 543 nm (Green, Ho:5S2→5I8). For this certain red emission at 657 nm, 0.4 wt% Ho2O3-doped YTH-TZN78 glass was found to present the highest emission intensity and is therefore determined as a promising active tellurite glass for red fiber laser development.     

Broadband emission from a multicore fiber fabricated with granulated oxides

We demonstrate a multicore multidopant fiber which, when pumped with a single pump source around approximately 800 nm, emits a more than one octave-spanning fluorescence spectrum ranging from 925 to 2300 nm. The fiber preform is manufactured from granulated oxides and the individual cores are doped with five different rare earths, i.e., Nd3+, Yb3+, Er3+, Ho3+, and Tm3+.     

Diode-pumped 2 μm vibronic (Tm3+, Yb3+):KLu(WO4)2 laser

We report on laser operation in a (6 at. % Tm, 5 at. % Yb):KLu(WO4)2 codoped crystal. The vibrational frequencies of KLu(WO4)2 are coupled to the electronic transitions of Tm3+ at 1946 nm, creating virtual final laser levels at higher energy than the ground level 3H6 of Tm3+. The longest recorded laser wavelength was 2039 nm, which is longer than permitted by a pure electronic transition in Tm3+ ions in KLu(WO4)2. We show that every laser wavelength can be explained with the electron-phonon coupling effect, where the vibration frequencies were determined through Raman spectroscopy.     

Controlled synthesis and up-conversion emission of rare-earth tri-doped NaYF4 nanocrystals under femtosecond-laser excitation

Cubic nanocrystal and hexagonal micro-rods NaYF4, with predictable size, shape and phase, have been successfully synthesized through hydrothermal reaction. The growth mechanism and the effect of mass transfer on the morphology of hexagonal micro-prism are both discussed in detail. The increase of tri-doping lanthanide ion concentration decreased the size of crystal particle, which was explained by the Arrhenius rate equation together combined with the Gibbs-Thomson relationship. Furthermore, the dopants did not only affect the sizes of tri-doped NaYF4 micro-rods, but also impacted upon fluorescence intensity. The fluorescence of tri-doped NaYF4: Nd3+/Yb3+/Er3+ system, excited by an 800 nm femtolaser, was intensified with the increase of doped lanthanide ions concentration. Nevertheless owing to the fluorescence quenching, the other two systems (NaYF4: Nd3+/Ho3+/Er3+ and NaYF4: Nd3+/Tm3+/Er3+) did not show the same phenomenon.     

Dual-mode luminescence from lanthanide tri-doped NaYF4 nanocrystals

Silica-coated NaYF₄:Yb/Er(Tm)/Eu nanocrystals (NCs) with a mean size of 35 nm were prepared and characterized. Each of the core/shell NCs can be dispersed in ethanol and water to form stable colloidal solutions and emit bright visible light of two colors (blue and red, green and red) by up- and down-converting excitation modes. As we know, this is the first time to obtain the distinct dual-color photos of NaYF₄:Yb/Er(Tm)/Eu NCs which were dispersed in deionized water. In particular, the ability to optically manipulate luminescence color of NCs doped with RE ions opens the door to multiplexed detection for high precision in more complex biotic environment.     

Synthesis and Study of Uranates of Rare-Earth Elements of Compositions LnU3O10.5·6H2O (Ln = La,Ce, Pr,Nd, Sm), LnU6O19.5·10H2O (Ln = Nd,Sm, Eu,Gd, Tb,Dy), and LnU2O7.5 (Ln = Dy,Ho, Er,Tm, Yb,Lu)

Radiochemistry - The interaction of synthetic skupite UO3·2.25H2O with aqueous solutions of La, Ce, Pr, Nd, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu nitrates under hydrothermal conditions at a...     

Controllable multicolor upconversion luminescence of lanthanide doped NaGdF4 nanocrystals through single laser excitation at 980 nm

Room temperature multicolor Upconversion (UC) luminescence in Yb3+, Tm3+, Er3+ ions doped NaGdF4 nanocrystals have been successfully synthesized by a hydrothermal method. As-prepared nanocrystals are highly crystalline and well-dispersed in cyclohexane to form stable and clear colloidal solutions, which demonstrates strong emission properties with a single laser excitation at 980 nm. The multicolor light consists of blue, green, and red UC radiations that correspond to transitions 1G4 --> 3H6 of Tm3+, 2H(11/2)/4S(3/2) --> 4I(15/2), and 4F(9/2) --> 4I(15/2) of Er3+ ions, respectively. The UC mechanisms were proposed based on spectral, kinetic, and pump power dependence analyses.     

Improved infrared emissions of Er(3+)-Tm3+ co-doped Al2O3 thin films: the role of cross relaxation among rare earth ions

We report the infrared emissions of Er(3+)-Tm3+ co-doped amorphous Al2O3 thin films pumped at 791 nm by a Ti:sapphire laser. The as-deposited films were annealed to improve the photoluminescence performance. Three cross relaxation channels among Er(3+)-Tm3+ and Tm(3+)-Tm3+ ions incorporated in the films were investigated as annealing temperature increases especially from 800 to 850 degrees C. In order to understand the Stark effect and cross relaxations, the photoluminescence spectra were deconvoluted by Gaussian fittings. Our results indicate that the luminescence intensity of 1.62 microm in comparison to 1.5 microm can be enhanced by the cross relaxation process [Er3+ (4I13/2) + Tm3+ (3H6) --> Er3+ (4I15/2) + Tm3+ (3F4)], and the longer-wavelength side of Er3+ emission can be improved by the CR process [Er3+ (4I15/2) + Tm3+ (3H4) --> Er3+ (4I3/2) + Tm3+ (3F4) at expense of the Tm3+ 1.47 microm emission which is also maybe quenched by the CR effect between themselves. These results suggest one possible approach to achieve broadband infrared emissions at the wavelength region of 1.45-1.65 microm from the Er(3+)-Tm3+ co-doped systems.