Synthesis of rare earth sulfides and their UV-vis absorption spectra

Rare earth sulfides were systematically synthesized via the sulfurization of their commercial oxide powders using CS2 gas to shorten sulfurization time, and their UV-vis absorption spectra were investigated. The appropriate sulfurization conditions were studied. For the rare earth sulfides with the same crystal structure, the sulfurization temperature showed increasing tendency with the decrease of rare earth element atomic radii. The UV-vis absorption spectra of rare earth sulfides did not depend on the crystal structure of rare earth sulfides, but on the 4f electronic structure of rare earth element. The data showed that the optical band gaps of rare earth sulfides were irregular, and the values ranged from 1.65 to 3.75 eV.

Syntheses and Infrared Spectra of Rare Earth Complexes with Diethyl Phosphate

The title complexes Ln(DEP),(Ln=La,Sm,Eu,Ho and Yb)were synthesized by reaction of triethyl phosphate with trivalent rare earth chlorides.The mechanism of thermo-decomposition of the complexes has been studied.According to their IR spectra,the residues of the thermo-decomposition of the complexes were identified as Ln(PO_3)_3.Their IR spectra were measured and principal IR bands were assigned.The experimental results of the IR spectra of the complexes show that the title complexes have the same coordination form and mo- lecular configuration as rare earth,e.g.Sm,complex with dimethyl phosphate(Sm(DMP)_3).Each of the rare earth ion links three rare earth ions nearby through double“O-P-O”bridges to form a special network of rings-linking-rings,each of which consists of twenty-four atoms.The Ln-O bond is principally ionic.

Preparation and Spectra Properties of Reactive Blue Rare Earth Dyestuffs

Reactive blue rare earth dyestuffs were prepared by using reactive blue and lanthanum oxide, praseodymium oxide, neodymium oxide, samarium oxide, europium oxide, gadolinium oxide, terbium oxide, dysprosium oxide, erbium oxide, lutetium oxide and yttrium oxide respectively for dyeing silk cloth. The degrees of dyeing of reactive blue gadolinium and fixation of reactive blue neodymium were the biggest respectively, were 84.83% and 97.96 respectively, were 24.13% and 8.36% were increased with that of reactive blue respectively. The spectra of reactive blue rare earths and reactive blue were studied by UV-VIS. In 200.00～800.00 nm, the λmax of reactive blue, reactive blue lanthanum, reactive blue praseodymium, reactive blue neodymium, reactive blue samarium, reactive blue europium, reactive blue gadolinium, reactive blue terbium, reactive blue dysprosium, reactive blue erbium, reactive blue lutetium and reactive blue yttrium are 599.00, 600.00, 602.00, 601.00, 600.00, 600.50, 600.50, 601.00, 600.00, 600.50, 599.50 and 600.50 nm respectively. Reactive blue lanthanum, reactive blue praseodymium, reactive blue neodymium, reactive blue samarium, reactive blue europium, reactive blue gadolinium, reactive blue terbium, reactive blue dysprosium, reactive blue erbium, reactive blue lutetium, reactive blue yttrium and reactive blue had almost same color.

Fabrication of Ormocer Containing Eu^(3+) Ion and Their Optical Spectra

Eu 3+ ions were incorporated in sol and gel by a sol gel processing using 3 glycidoxypropyltrimethoxysilane (CH 2OCHCH 2O(CH 2) 3Si(OCH 3) 3, GPTMS) and ethyl silicate (TEOS) as precursors. The basic chemical physical properties such as DTA curve, FT IR spectra and specific surface area were recorded. The characteristics of their optical spectra were measured and investigated. The results indicate that the emission intensity of Eu 3+ ion in ormocer is much higher and the global line width is wider than those in SiO 2 gel. The relationship between the composition and structure of gels and the fluorescence intensity and width were discussed. The obtained ormocer shows good mechanical strength, which can be cut and polished in machine without broken.

Co-Precipitation Synthesis and Spectral Characteristics of Long Afterglow Phosphor Y_2O_2S: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.

Optics and Spectral Investigation in Dy^(3+)-Doped Borate Glasses

Dy^3＋-doped borate glasses （LBLB） with high effective visible fluorescence emission were synthesized. The absorption spectrum and fluorescence spectrum of this glass were measured and analyzed. By using J-O theory, the oscillator strengths for some absorption transitions were calculated according to the absorption spectra. The intensity parameters Ω1 （t = 2, 4, 6） of Dy^3＋ were determined by using a least-squares fitting approach, and the values are 4.04 × 10^-20, 1.30 × 10^-20 and 1.82 × 10^-20 cm, respectively. The root-mean-square deviation δrma was calculated. Under UV light excitation, Dy^3＋-doped borate glasses （LBLB） emit intense yellowish white lights. The excitation spectrum indicates that argon laser is the effective excitation source in Dy^3＋-doped LBLB glasses

Fluorescence and Judd-Ofelt analysis of rare earth complexes with maleic anhydride and acrylic acid

Two kinds of Eu-complexes, Eu（TTA）2（Phen）（AA） and Eu（TTA）2（Phen）（MA） （HTTA=2-Thenoyltrifluoroacetone, Phen=1,10- phenanthroline, AA=acrylic acid, MA=Maleic anhydride）, which combined the excellent fluorescence properties of Eu（TTA）2（Phen）（H2O） and the reactivity of acrylic acid and maleic anhydride with radicals, were synthesized. The two complexes were characterized by elemental analysis, infrared （IR） spectra, and X-ray photoelectron spectroscopy （XPS）. Based on the data shown from the fluorescent spectra of the Eu-MA and Eu-AA complexes, the Ωλ （λ=2 and 4） experimental intensity parameters were calculated. The results demonstrated that the Ω2 intensity parameters for the two complexes were smaller than those for the Eu（TTA）2（Phen）（H2O） complex, indicating that a less symmetrical chemical environment existed in the complexes. It implied that the radiative efficiency of the ^5D0 of these two complexes could be enhanced by ligand of MA and AA, respectively. The luminescent lifetime of the Eu-AA （r=-7.26×10^-4 s） or Eu-MA complex （r=-8.12×10^-4 s） was higher than that of the Eu（TTA）2（Phen）（H2O） complex, which was attributed to the substitution of the water molecule （H2O） in Eu（TTA）2（Phen）（H2O） by the MA or AA ligand.

Synthesis and Characterization of Rare Earth Tesnary Complexes with Cinnamic Acid and O-Phenanthroline

Thirteen solid rare earth tesnary complexes with cinnamic acid C 6H 5CH=CHCOOH, HL and o phenanthroline (phen), RE(phen)L 3 were synthesized. Their IR absorption spectra, molar conductance, TG DTA, X ray power diffraction analysis and fluorescence spectra were studied. The results show that all coordination compounds are oxidized and decomposed around 400 ℃ to 540 ℃. They are all crystalline material. The fluorescence spectra indicate that the fluorescence emission intensity of Eu(phen)L 3 is the highest among them.

Growth and Spectral Properties of Crystal Er^(3+)∶Y_(0.5)Gd_(0.5)VO_4

Er^3＋ ：Y0.5Gd0.5VO4 crystal with good optical quality was grown by Czochraski method. The structure of the crystal was determined by X-ray powder diffraction method. The segregation coefficient of Er^3 ＋ ions in the crystal was measured by the ICP method. The absorption and emission spectra were also measured. On the basis of the spectra, the absorption cross-sections, emission spectrum FWHM and fluorescence lifetime of the crystal were calculated. From the properties mentioned above.

Research of Three-Dimensional Fluorescence Spectra of RE^(3+)(RE=Eu,Tb) and Na_2WO_4 Co-doped Silica Luminescence Materials

In the preparation of this precursor tetraethlortho silicate (TEOS), sodium tungstate, ethyl alcohol, HCl and RECl3(RE=Eu,Tb) were mixed and then heated at 800 ℃ for 2 h, leading to a luminescent compound. The structure of the materials was characterized by TG-DTA and IR analysis, and the results indicate that the materials were in SiO2 network structure. Three-dimensional fluorescence spectra was used to characterize the luminescent properties of the materials. The luminescence property of doped and un-doped Eu3+or Tb3+ and Na2WO4 in silica materials were prepared and measured. The results show that good energy transfer from WO2-4 to Eu3+ ion, sensitized the luminescence intensity of Eu3+ remarkably. Tb3+ ion incorporated silica materials expressed the inverse energy transition from Tb3+ to WO2-4, however, we got the materials with homogeneous green blue fluorescent light. Finally, the energy transfer of WO2-4 and Eu3+, WO2-4 and Tb3+ were explained by energy levels diagram.

Spectra and Upconversion of Neodymium Tungstate Crystals

The neodymium tungstate single crystals Nd-2(WO4)(3) were grown using the Czochralski method. The energy level scheme of Nd3+, was obtained through the spectral measurement. The upconversion luminescence of the crystals at 457 and 657 nm, corresponding to the (D5/2-->I11/2)-D-4-I-4 and (2)G(7/2)-->I-4(9/2) transitions, respectively, excited by 808 nm of a laser diode, was observed at room temperature. The fluorescence intensity and the excitation light power have a linear relationship at 457 nm and a quadratic relationship at 657 nm.

Charge Transfer Spectra (CTS) in CaS:Ce^(3+) Phosphors

This paper describes the excitation spectra nearby 220hm of CaS:Ce^(3+),Na^+ and CaS:Ce^(3+),X^-(X=F,Cl or Br).It is considered that the charge transfer excitation is caused by electron transfer of S^(2-)on 3p^6 to the 4f shell of Ce^(3+).It has been discussed that,when halogen ions act as coactivators,this excitation band shifts to low- er wavenumber.

Low Temperature Preparation of Ceria Solid Solutions Doubly Doped with Rare-Earth and Alkali-Earth and Their Properties as Solid Oxide Fuel Cells

A series of solid electrolytes, (Ce 0.8 Ln 0.2 ) 1- x M x O 2-δ (Ln= La, Nd, Sm, Gd, M:Alkali earth), were prepared by amorphous citrate gel method. XRD patterns indicate that a pure fluorite phase is formed at 800 ℃. The electrical conductivity and the AC impedance spectra were measured. XPS spectra show that the oxygen vacancies increase owing to the MO doping, which results in the increase of the oxygen ionic transport number and conductivity. The performance of ceria based solid electrolyte is improved. The effects of rare earth and alkali earth ions on the electricity were discussed. The open circuit voltages and maximum power density of planar solid oxide fuel cell using (Ce 0.8 Sm 0.2 ) 1-0.05 Ca 0.05 O 2- δ as electrolyte are 0.86 V and 33 mW·cm -2 , respectively.

Synthesis, Characterization and Luminescence Properties of Rare Earth Complexes with Bis(Pyridinyl-Amide)

A ligand, N^1, N^4-di （ pyridin-2-yl ） succi- namide （L） and its lanthanide（ IH ） complexes （RE = La, Eu, Tb, Gd, Yb ） were synthesized and characterized in detail. The results indicate that the composition of the binary complexes is determined as [ REL （H2O）2（NO3）2] NO3, that the complexes are 1 ： 1 electrolytes in DMF, and that the Tb^3＋ complex has brightly green fluorescence in a solid state. At the same time, the energy levels of the excited triplet states for the six ligands were determined to be 22989 -1 cm . The fact that the ligand sensitize Tb^3＋ complexes was explained by the relative energy gap between the lowest triplet energy level of the ligand （T） and ^5Dj of Tb^3＋ or Eu^3＋ . When 2000 cm^-1 〈 △E（T-^5D4） 〈 3000 cm^-1, the luminescent intensity of the Tb^3＋ complex is stronger. When 3000 cm^-1〈 △E （T-^5D1）, the luminescent intensity of the Eu^3＋ complex is weak- er or close to nil. This means that the triplet energy level of the ligand is a chief factor that dominates RE^3＋ luminescence.

Study on Visible Photoluminescence and Absorption Spectra of Fergusonite Group Minerals

Visible photoluminescence and absorption spectra of the metamict and annealing-recrystallized fergusonite and brocenite, found in Bayun Obo ore deposit in China, were determined and discussed. The results show that the glow centers of the fergusonite group minerals are Er3+ and Eu3 + when 488.0 and 514.5 nm lasers are used as excitation sources. The luminescence of fergusonites results mainly from Er3+, whereas that of brocenites is produced by Er3+ and Eu3+. The absorption spectra indicate that Nd3 + may be an important sensitizer to the luminescence of Er3 + and Eu3+.

Site Selective Spectra of Eu^(3+)-Doped Y_2SiO_5 Crystal

By using a whitelight lamp, an Ar+ ion laser whosewavelength was tuned to 457. 9 nmand a tunable Rh 6G dye laser(linewidth: 0. 5 cm-1) pumped bythe second harmonic of a Nd: YAGlaser as light sources and using amonochromator, a phase-lockingamplifier and a computer as the data detecting system, the transmission spectrum, fluorescence spectra, excitation spectrum and siteselective fluorescence spectra ofthe Eu3+: Y2SiO5 crystal were observed. More than thirty out of thetotal fifty spectral lines were observed for 5D0→7F0,1,2,3,4 transitions. The Eu3+ ions occupy twokinds of the Y3+ sites with the lowsymmetry in this crystal. The difference of the wavelengths of thetwo Eu3+ sites for 7F0→5D0 transition is about 0. 2 nm. It was foundthat the two sites were nonequivalent optical ones at room temperature. Crystal lattice constants a,b, c, and β of Eu3+: Y2SiO5 werealso measured by the X-ray diffraction method. The results show thatthe lattice constants a, b, and cof the crystal doped Eu3+ ions isvery close to those of the Y2SiO5crystal undoped Eu3+ ions.

KZnF_3中Ce^(3+)→Eu^(2+)的能量传递

研究了KZnF3中Ce3+和Eu2+的光谱特性，在共掺Ce3+和Eu2+的体系中，观察到了Ce3+对Eu2+的能量传递过程．计算了能量传递的鼻子效率，探讨了能量传递机理．研究发现，Ce3+的存在有利于Eu2+的f-f跃迁线状发射．

苯甲酸及其一氯代衍生物与邻菲罗啉或联吡啶的稀土铕三元配合物的荧光性质

本文报道合成了八种苯甲酸及其一氯代衍生物与邻菲罗啉或联吡啶的稀土铕三元配合物并测得了荧光光谱。通过改变第一和第二配体,研究了配合物发光峰强度、位置和分裂间隔等的变化情况,依据荧光发射峰的分裂推断出Eu^(3+)离子所处的局域环境对称性大致都是C_1,C_2或C_s。虽然配合物的局域对称性大致相同,但由于配体场作用和能级匹配等原因,发光峰位置和强度是不同的;讨论了第一配体分子结构的变化对荧光性能的影响,认为分子自身结构的对称性可能对提高配合物发光性能有较大影响;实验还观察到第二配体也参与配位且对发光性能影响较大。同时看到发光峰的分裂间隔大小变化和发光峰的相对强度的变化是一致的。

溶胶-凝胶法合成YAG∶Ce^(3+)荧光粉及其发光性能研究

采用以硝酸盐为原料、柠檬酸为络合剂的溶胶-凝胶法,合成了YAG∶Ce3+纳米荧光粉,得到最低合成温度为1000℃。随烧结温度的升高,样品结晶程度越来越好,并且颗粒尺寸随温度的升高而增大。该荧光粉可被460 nm的蓝光LED有效激发,发射光谱为峰值在530 nm的一宽带。Ce3+掺杂浓度的不同并不影响光谱位置的变化,但对强度有一定影响,当x=0.06时发光强度比较理想。

稀土硼酸盐的结构及其真空紫外(VUV)荧光性质

稀土硼酸盐在真空紫外 (VUV)波段的吸收与化合物中硼酸根离子的结构有关 ,扩展 Hückel计算表明 ,硼酸根离子中的 B— O成键轨道与 B— O反键轨道能量差按 BO5- 4>B2 O4 - 5>BO3- 3 >B3O9- 9顺序减小 ,这与 VUV激发光谱的实验结果一致 ,表明 VUV激发过程对应于电子从 B— O成键轨道向反键轨道的跃迁 .