Luminescent properties of rare-earth-doped CaWO4 phosphor films prepared by the Pechini sol-gel process

CaWO4 phosphor films doped with rare-earth ions (Eu3+, Dy-,(3+) Sm3+, Er3+) were prepared by the Pechini sol-gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, atomic force microscopy, and photoluminescence spectra, as well as lifetimes, were used to characterize the resulting powders and films. The results of the XRD analysis indicated that the films began to crystallize at 400degreesC and that the crystallinity increased with elevation of the annealing temperature. The doped rare-earth ions showed their characteristic emissions in crystalline CaWO4 phosphor films due to energy transfer from WO42- groups to them. Both the lifetimes and PL intensities of the doped rare-earth ions increased with increasing annealing temperature, from 500 to 900degreesC, and the optimum concentrations for Eu3+, Dy3+, Sm3+, Er3+ were determined as 30, 1.5, 1.5, 0.5 at.% of Ca2+ in CaWO4 films annealed at 900degreesC, respectively.

Patterning and luminescent properties of nanocrystallineY(2)O(3): Eu3+ phosphor films by sol-gel soft lithography

Nanocrystalline Y2O3:Eu3+ phosphor films and their patterning were fabricated by a Pechini sol-gel process combined with a soft lithography. X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), atomic force microscopy (AFM), optical microscopy, UV/vis transmission and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 500 degreesC and the crystallinity increased with the elevation of annealing temperatures. Uniform and crack free non-patterned phosphor films were obtained, which mainly consisted of grains with an average size of 70 nm. Using micro-molding in capillaries technique, we obtained homogeneous and defects-free patterned gel and crystalline phosphor films with different stripe widths (5, 10, 20 and 50 mum). Significant shrinkage (50%) was observed in the patterned films during the heat treatment process. The doped Eu3+ showed its characteristic emission in crystalline Y2O3 phosphor films due to an efficient energy transfer from Y2O3 host to them. Both the lifetimes and PL intensity of the Eu3+ increased with increasing the annealing temperature from 500 to 900 degreesC, and the optimum concentrations for Eu3+ were determined to be 5 mol%.

Multi-color long-lasting phosphorescence of rare earth ions in CdSiO3 matrix

A series of rare earth ions doped CdSiO3:RE3+(RE=Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) multi-color long-lasting phosphorescence phosphors are prepared by the conventional high-temperature solid-state method. The results of XRD measurement indicate that the products fired under 1050degreesC for 3 h have a good crystallization without any detectable amount of impurity phase. Rare earth ions doped CdSiO3 phosphors possess excellent luminescence properties. When rare earth ions such as Y3+, La3+, Gd3+, Lu3+, Ce3+, Nd3+, Ho3+, Er3+, Tm3+ and Yb3+ are introduced into the CdSiO3 host, one broadband centered at about 420 nm resulting from traps can be observed. In the case of other earth ions such as Pr3+, Sm3+, Eu3+, Tb3+ and Dy3+, their characteristic line emitting as well as the similar to420 nm broadband luminescence can be obtained. The mixture of their characteristic line emitting with the similar to420 nm broadband luminescence results in various afterglow color.

LaF3:Ce3+荧光特性的研究

LaF3:Ce多晶中Ce3+的荧光发射谱由双峰带结构组成。Ce3+与其他稀土粒子共掺杂,Ce3+发射强度均降低,原因是一部分稀土离子(如Eu3+等)与Ce3+产生了电子转移;一部分稀土离子(如Er3+等)与Ce3+产生了能量传递。

Y_2O_3∶Eu~(3+)发光薄膜的溶胶凝胶法制备、表征及图案化

采用Pechini溶胶 凝胶法制备了纳米级Y2O3∶Eu3+发光薄膜,同时,通过软石印技术得到了条纹宽度为5～60μm的Y2O3∶Eu3+图案化发光薄膜。通过X射线衍射(XRD)、付里叶变换 红外光谱(FT IR)、原子力显微镜(AFM),光致发光(PL)光谱及寿命等方法对得到的发光薄膜进行了表征。XRD结果表明500℃时薄膜开始结晶,900℃已结晶完全,得到了立方相的产物。图案化的条纹在烧结的过程中发生了明显的收缩(50%)。Y2O3基质向掺杂的稀土离子Eu3+发生了有效的能量传递,使得Eu3+显示出5D0 7FJ(J=0,1,2,3,4)特征发射。寿命和光致发光光谱的研究表明,发光强度随着温度的升高而增强。

杂质离子对Y_2O_3∶Eu~(3+)发光性能的影响

研究了碱金属及碱土金属离子掺杂的荧光体Y2 O3∶Eu3+ 0 .0 5,A+ 0 .0 2 (A =Li、Na、K)和Y2 O3∶Eu3+ 0 .0 5,B2 + 0 .0 2 (B =Mg、Ca、Sr、Ba)的荧光、余辉发光及热释光特性。余辉光谱数据表明 :杂质离子掺杂的荧光体Y2 O3∶Eu3+ 的余辉发射主峰与未掺杂荧光体Y2 O3∶Eu3+ 的荧光发射主峰 (611nm)一致 ,为经典Eu3+ 的5D0 7F2 电偶极跃迁 ;杂质离子的引入明显地延缓了Y2 O3∶Eu3+ 的余辉衰减 ,其中Y2 O3∶Eu3+ ,A+ (A =Li、Na、K)的余辉衰减趋势几乎完全一致 ,而Y2 O3∶Eu3+ 、B2 + (B =Mg、Ca、Sr、Ba)的余辉衰减趋势由慢到快依次为Ca、Sr、Ba、Mg。热释光谱数据显示 ,杂质离子的掺杂导致基质中电子陷阱能级的生成 ,这是导致余辉衰减减慢的直接原因。Y2 O3∶Eu3+ ,A+ 的热释峰都位于 175℃左右 ,相应电子陷阱能级深度为 0 .966eV左右 ;而Y2 O3∶Eu3+ ,B2 + 的热释峰由高到低分别位于 192℃ (Ca)、164℃ (Sr)、1...

Preparation, patterning and luminescence properties of rare earth-doped YVO4 nanocrystalline phosphor films via sol-gel soft lithography

In this presentation, nanocrystalline YVO4:A (A=Eu3+, Dy3+, SM3+, Er3+) phosphor films and their patterning were fabricated by a Pechini sol-gel process combined with a soft lithography (micro-molding in capillaries). XRD, FT-IR, AFM and optical microscope, absorption spectra, photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 400 degrees C and the crystallinity increased with the increase of annealing temperatures. Transparent nonpattemed phosphor films were uniform and crack free, which mainly consisted of grains with an average size of 90nm. Patterned crystalline phosphor film bands with different widths (5-30 mu m) were obtained. The doped rare earth ions (A) showed their characteristic emission in crystalline YVO4 phosphor films due to an efficient energy transfer from vanadate groups to them. The Sm3+ and Er3+ ions also showed upconversion luminescence in YVO4 film host. The optimum concentration for Eu3+ was determined to be 7 mol% and those for Dy3+, Sm3+, Er3+ were 2 Mol% of Y3+ in YVO4 films, respectively.

Luminescent properties of Gd3PO7 : Eu in UV/VUV region

The luminescent properties of Gd3PO7:Eu were investigated in W and VUV regions. This phosphor has such strong emissions around 618.5 nn under UV excitation, especially around 209nn, that it has a better colour saturation than that of Y2O3:Eu. It could be a new potential red phosphor for lamp and other applications with W-excitation source or even for displaying devices. In the VUV excitation spectrum of Eu3+ emissions, energy absorptions by Gd3+, Gd-O and PO43- have been observed, on which it can be inferred that there are three kinds of energy transferring processes to Eu-3(+) ions. The energy absorptions of Gd3+, Gd-O and PO43- are induced by 4f --> 4f transitions, a bandgap transition of Gd3PO7 and intramolecular (2t(2) --> 2a, 3t(2)) transition, respectively. The energy transfer efficiency of the PO43- intramolecular transition is lower compared with that of the bandgap transition (Gd-O).

稀土离子的高能光谱

讨论了稀土离子在能量高于 5 0 0 0 0cm- 1 (波长短于 2 0 0nm)的光谱 ,包括 4f 4f跃迁 ,4f 5d跃迁 ,4f 6s跃迁 ,基质吸收和电荷迁移带。利用Dorenbos提出的公式 :E(Ln ,A ) =493 40 -D(A) +ΔELn ,Ce,指认了Sm3+ 离子在我们合成的Ba3BP3O1 2 中的 4f 5d跃迁的能量值为 170nm。利用我们提出的稀土离子光学电负性 χM与标准还原电位E0Ln的关系式 :E0Ln(Lnn + →Ln(n - 1 ) ) =4 2 73 χM-7 776(其中n =3或 4) ,从稀土离子的光学电负性 χM 与J rgensen提出的公式Ect=[χX-χM]× 3 0 0 0 0cm - 1 ,估算出Er3+和Eu3+离子在含氧杂质的LiYF4 ∶Er和LiYF4 ∶Eu3+中Er O和Eu3+ O的电荷迁移带的能量 ,以及LiYF4 ∶Eu3+ 中Eu3+ F的电荷迁移带的能量 ,估算值与文献报道的实验值基本相符。

Calculations of cross sections of resonant two-photon transitions to the second excited 4f5d state in Pr3+: Y3Al5O12 using density matrix theory

The density matrix resonant two-photon absorption (TPA) theory applicable to laser crystals doped with rare earth ions is described. Using this theory, resonant TPA cross sections for transitions from the ground state to the second excited state of the 4f5d configuration in cm(4)s Pr3+:Y3Al5O12 are calculated. The peak value of TPA cross section calculated is 2.75 x 10(-50) cm(4)s which is very close to the previous experimental value 4 x 10(-50) cm(4) s. The good agreement of calculated data with measured values demonstrates that the density matrix resonant TPA theory can predict resonant TPA intensity much better than the standard second-order perturbation TPA theory.

Ni~(2+)和Er~(3+)在固体中的电子云扩大效应计算

应用介电描述的复杂晶体化学键理论，给出计算Ni2+和Er3+在固体中的电子云扩大效应的新方法.

Rheological properties and crystallization behavior of yttrium oxide filled low ethylene content polypropylene copolymer

The rheological properties and crystallization characteristics of low ethylene content poly propylene (EPM) with and without Yittrium oxide (Y2O3) as a filler was investigated by cone-plate viscometer and differential scanning calorimetry. Yittrium oxide had a profound effect on the viscosities of the systems. To determine the nonisothermal crystallization rate of the materials, a new estimation method was used. From the results, we can conclude that Y2O3 acts as a nucleating agent, which increased the crystallization rate of the EPM. (C) 1996 John Wiley & Sons, Inc.

Syntheses and crystal structures of [(C6H5CH2C5H4)(2)GdCl center dot THF](2) and (C6H5CH2C5H4)(2)ErCl center dot THF

[(C6H5CH2C5H4)(2)GdCl . THF](2) (1) and (C6H5CH2C5H4)(2)ErCl . THF (2) were prepared by the reaction of LnCl(3) (Ln=Gd, Er) with benzylcyclopentadienyl sodium in THF and characterized by elemental analysis, IR, H-1 NMR, C-13 NMR, MS and thermal gravimetry. The crystal structures of both compounds were determined. Complex 1 is dimeric and its structure belongs to the monoclinic, P2(1)/c space group with a=1.1432(2), b=1.2978(2), c=1.7604(3) nm, beta=108.75(2), V=2.4732(9) nm(3), Z=2(four monomers), D-c=1.54 g . cm(-3). R=0.0342 and R(w)=0.0362. Complex 2 is monomer and its structure belongs to the orthorhombic, P2(1)2(1)2(1) space group with a=0.8645(2), b=1.1394(3), c=2.5289(4) nm, V=2.4919(9) nm(3), Z=4, D-c=1.56 g . cm(-3). R=0.0514, R(w)=0.0529. The determination of the crystal structure shows that in complex 1 the benzyl groups on the cyclopentadienyls coordinated to Gd3+ are located in the opposite direction (139 degrees); in complex 2 the benzyl groups on the cyclopentadienyls coordinated to Er3+ are located in the same direction (6.5 degrees).

Crystal structure of polypropylene filled with rare earth oxides

The effect of a fine powder of Y2O3, Nd2O3, and Ho2O3 on the crystal structure of isotactic polypropylene (iPP) was studied with WAXD and DSC techniques. The results showed that the addition of the three rare earth oxides (REOs) can increase the crystallite size of the alpha-form crystal and the degree of crystallinity of iPP at an annealing temperature of 120 degrees C and that both Y2O3 and Nd2O3 are the beta-nucleator of iPP. REOs enhance the overall growth rate of the spherulites of iPP. All the iPP samples filled with REOs which were crystallized isothermally at 132 degrees C from the melt exhibited their melting peaks of the beta-form on the DSC heating traces, indicating that the REOs are the nucleating agents for both the alpha- and beta-forms of iPP under isothermal conditions. (C) 1996 John Wiley & Sons, Inc.

TETRAKIS(MU-DL-ALANINE-O-O')OCTA-AGUADIERBIUM(III) HEXAPERCHLORATE

The structure of the title compound, [Er-2(C3H7NO2)(4)- (H2O)(8)](ClO4)(6), consists of dimeric [Er-2(DL-alanine)(4)-(H2O)(8)](6+) cations and perchlorate anions. The four alanine molecules act as bridging ligands linking two Er3+ ions through their carboxyl O atoms. Each Er3+ ion is also coordinated by four water molecules to complete eightfold coordination in a square antiprism fashion. The perchlorate anions and the methyl groups of the alanine ligands are disordered.