Luminescent Property of Eu^3＋ Doped in TiO2-SiO2 Sol

Formability of Rare Earth-Containing Solid Solution Based on Compounds with Scheelite-Type Structure     

Persistent Spectral Hole Burning of Eu^3＋ Doped Y2SiO5 Crystal at 579.62 nm

By using an Ar^＋ ion laser, a tunable Rh6G dye laser（linewidth： 0.5 cm^-1） pumped by the second harmonic of a YAG：Nd laser and an 899-21 dye laser as light sources and using a monochromator, a phase-locking amplifier and a computer as the data detecting system, the spectra and spectral hole burning of Eu^3＋：Y2SiO5 crystal were researched in this paper.Photoluminescence excitation spectrum and site selective fluorescence spectrum were detected at room temperature and 77 K. Hole burning experiments were reached at 16 K. A spectral hole with hole width of about 80 MHz were detected and it could be kept for 10 h.     

Thermal Stability and Luminescence Properties of Eu^3＋ and Tb^3＋ Complexes with a Silica Matrix by Sol-Gel Method

Ternary complexes of europium and terbium with benzoic acid and 1, 10-phenanthroline [RE(BA)3phen] (BA=benzoate phen=1,10-phenanthroline) were introduced into a silica matrix by sol-gel method. The thermal stability and luminescence behavior of the complexes in silica gels were studied in comparison with the corresponding solid-state complexes by thermal decomposition, excitation and emission spectra. The thermal stability of the complexes is enhanced in silica gel matrix and the luminescence remaines unchanged.     

Transient Charge Trapping in Eu^3＋ -Doped Nanocomposites by Ultrafast Laser Excitation

Eu^3＋ was incorporated as probe ions into nanocomposite glasses, such as metal silver doped phosphate glass and crystalline nanocomposites Si-enriched SiO2 glass. Luminescence studies show that the doped europium ions are present as trivalent Eu^3＋ , and are distributed in the matrix on the boundary surface of nanoparticles. The valence switching from Eu^3＋ to Eu^2＋ was observed in Si-SiO2 nanocomposites when ultrafast laser excitation was applied. In silver metal nan-oparticles embedded aluminophosphate glass, a time-resolved ultrafast degenerate-four-wave-mixing （DFWM） experiment shows enhanced third-order nonlinearity at zero-delay time, followed by a bell-like signal buildup. It is attributed to the creation of electronic polaron and vibronic Wannier-Mott exciton （WME）. In europium codoped sample, however, the bell-like signal is depressed. All the above observations are interpreted as the result of a strong Coulomb interaction between conduction electrons produced inside the nanoparticles by laser excitation and Eu^3＋ ions residing near the surface. The trivalent europium ions play the role as positive boundary charges attracting electrons. This results in temporary formation of Eu^2＋ , and blocks the resonant tunneling transition in the silver-glass system to avoid creating large radius polaron.     

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.     

Synthesis and Properties of Tb^3＋-Doped CaxSr1-xWO4

Tb^3 -doped CaxSr1-xWO4 was prepared by solid state reaction and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belongs to tetragonal system, which is consistent with space group 141/α. Lattice parameters in the systems CaxSr1-xWO4 were found to vary linearly with compositions. The emission and excitation spectra were measured. The miscibility, luminescence properties of Tb^3 -doped CaxSr1-xWO4 and energy transfer mechanism were discussed.     

Citrate-Gel Synthesis and Luminescent Properties of α-Zn3 （PO4）2 Doped with Eu^3＋

By using inorganic salts as raw materials and citric acid as complexing agent, α-Zn3(PO4)2 and Eu^3 doped α-Zn3( PO4)2 phosphor powders were prepared by a citrate-gel process. X-ray diffraction (XRD), TG - DTA, FF - IR and luminescence excitation and emission spectra were used to characterize the resulting products. The results of XRD reveal that the powders begin to crystallize at 500℃ and pure α-Zn3(PO4)2 phase is obtained at 800℃. And the results of XRD reveal that Eu^3 exists as EuPO4 in the powder. In the phosphor powders, the Eu^3 shows its characteristic red-orange(592 nm, ^5D0 -^7F1) emission and has no quenching concentration.     

Sol-Gel Synthesis and Luminescent Characteristic of Doped Eu^3 ＋ Silicate-Silica Phosphor

Silicagelphosphorsdopedrareearthionshave attractedgreatattentionofmanyresearchersdueto theseadvantages,suchashighersamplehomogeneity,purityandstable,efficientandenvironmentallyfriend lyphotoluminescencematrixmaterials,whichisless toxicleadtonetconversione…     

Study on Spectra of La2CaB10O19：Eu^3＋ in VUV-VIS Range

Excitation and emission spectra of new borate La2CaB10O19 doped Eu^3 in VUV-VIS range, high resolution emission spectra at room temperature and lifetime of Eu^3 were investigated. The emission line at about 616nm attributed to the ^5D0-^7F2 transition of Eu^3 is the most intense emission of Eu^3 . The broad band at about 244nm is originated from charge transition band (CTB) of O^2→Eu^3 . According to the numbers of spectral lines ^5D0-^7F0 and ^5D0-7F1 in highresolution spectrum, Eu^3 ions occupy two crystallographic sites. The lifetimes of ^5D0-^7F0 transition of Eu^3 of two kinds of lattice sites are individually 2.1 and 2.6ms, and both are exponential decay. In the VUV excitation spectrum, complicated band between 130 and 170nm consists of host absorption and f-d transition of Eu^3 .     

Study on UV Excitation Properties of Eu^3＋ at S6 Site in Bulk and Nanocrystalline Cubic Y2O3

Increases of emission intensities for Eu^3 at the S6 site relative to that at the C2 site were observed as UV excitation wavelength decreases from 300 nm to 200 nm in both bulk and nanocrystalline cubic Y2O3:Eu^3 . Decomposition of excitation spectra shows that the charge transfer band of Eu^3 at the S6 site lies in the high-energy side of that at the C2 site, resulting in that the energy transfer from the host prefers to the S6 site. Detailed emission and excitation spectral characteristics were analyzed and discussed. In addition, spectral red-shift were found in both charge transfer bands in nanocrystalline Y2O3: Eu^3 compared to the bulk material. The number ratio of S6 sites to C2 sites is also smaller in nanocrystalline Y2O3:Eu^3 than that in the bulk one.     

Ab initio calculation of electronic structures and 4f-5d transitions of some rare earth ions doped in crystal YPO4

The ab initio self-consistent DV-Xα (discrete variational Xα) method was used in its relativistic and spin-polarized model to investigate the ground-state electronic structures of the crystal YPO4 and YPO4:RE3 (RE=Ce, Pr and Sm) and f-d transition energies of the lattice. The calculation was performed on the clusters Y5P10O32 and REY4P10O32 embedded in a microcrystal containing about 1500 ions, respectively. The ground-state calculation provided the locations of the 4f and 5d crystal-field one-electron levels of RE3 relative to the valence and conduction bands of host, the curve of total and the partial density of states, and the corresponding occupation numbers, etc. Especially, the transition-state calculation was performed to obtain the 4f→5d transition energies of RE3 in comparison to the experimental observations. The lattice relaxation caused by the dopant ion RE3 was discussed based on the total energy calculation and the transition-state calculation of the f-d transition energies.     

Doped Organic Electroluminescence from a Novel Rare Earth Complex Tb （3-metho） 3 phen

A novel rare earth complex Tb (3-metho)3phen was synthesized and characterized. The complex was doped into PVK to improve the conductivity and film-forming property of Tb(3-metho) 3phen. A device with a structure of ITO/PVK: Tb(3-metho)3phen/Al was fabricated to study the eleetrolumineseent properties of Tb(3-metho) 3 phen. And the optoluminescent and AFM properties of this device were also studied, which proved the existence of energy transfer from PVK to Tb(3-metho)3phen. As a result, a pure green emission with sharp spectral band at 547.5 nm was observed.     

Fabrication of Ormocer Containing Eu3＋ Ion and Their Optical Spectra

Eu3 ions were incorporated in sol and gel by a sol-gel processing using 3-glycidoxypropyltrimethoxysilane(CH2OCHCH2O(CH2)3Si(OCH3)3, GPTMS) and ethyl silicate (TEOS) as precursors. The basic chemical-physical properties such as DTA curve, FF-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 Eu3 ion in ormocer is much higher and the global line width is wider than those in SiO2 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.     

Structure and Luminescence Properties of Eu~(3+) Doped SiO_2 Glass Synthesized by Sol-Gel Process

Ａｍｏｎｇｌａｎｔｈａｎｉｄｅｉｏｎｓ ,Ｅｕ3 + ｉｏｎｐｏｓｓ ｅｓｅｓｇｏｏｄｌｕｍｉｎｅｓｃｅｎｔｃｈａｒａｃｔｅｒｉｓｔｉｃｓ ,ｈｉｇｈｃｏｌｏｒｐｕｒｉｔｙａｎｄｈｉｇｈｑｕａｎｔｕｍｅｆｆｉｃｉｅｎｃｙ .Ｅｕ3 + ｉｓｏｎｅｏｆｔｈｅｃｅｎｔｒａｌｉｏｎｓｆｉｒｓｔｓｅｌｅｃｔｅｄｆｏｒｔｈｅｐｒｅｐａｒａｔｉｏｎｏｆｒａｒｅｅａｒｔｈｉｏｎｓｄｏｐｅｄｌｕｍｉ ｎｅｓｃｅｎｔｍａｔｅｒｉａｌｓ .Ｄａｆｉｎｏｖａｅｔａｌ .[1] ｐｒｏｄｕｃｅｄＥｕ3 + ａｎｄＳＯ2 -4 ｄｏｐｅｄｔｕｎｇｓｔａ…     

Upconversion Luminescence of Ce^3＋ Doped BK7 Glass by Femtosecond Laser Irradiation

Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate （BK7） glass containing Ce^3 ＋ ions under focused infrared femtosecond laser irradiation. The emission spectra show that the upconversion luminescence comes from the 4f-5d transition of the Ce^3 ＋ ions. The relationship between the intensity of the Ce^3 ＋ emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.     

Study on Spectra of La2CaB10O19∶Eu3+ in VUV-VIS Range

Excitation and emission spectra of new borate La2CaB10O19 doped Eu3 in VUV-VIS range, high resolution emission spectra at room temperature and lifetime of Eu3 were investigated. The emission line at about 616 nm attributed to the 5D0-7F2 transition of Eu3 is the most intense emission of Eu3 . The broad band at about 244 nm is originated from charge transition band (CTB) of O2-→Eu3 . According to the numbers of spectral lines 5D0-7F0 and 5D0-7F1 in high-resolution spectrum, Eu3 ions occupy two crystallographic sites. The lifetimes of 5D0-7F0 transition of Eu3 of two kinds of lattice sites are individually 2.1 and 2.6 ms, and both are exponential decay. In the VUV excitation spectrum, complicated band between 130 and 170 nm consists of host absorption and f-d transition of Eu3 .     

Synthesis and Crystal Structure of Two Cyano-Bridged dimeric 4f-3d Complexes

Ｒｅｃｅｎｔｌｙ ,ｔｈｅｒｅｈａｓｂｅｅｎｃｏｎｓｉｄｅｒａｂｌｅｉｎ ｔｅｒｅｓｔｉｎｌａｎｔｈａｎｉｄｅｈｅｘａｃｙａｎｏｆｅｒｒａｔｅｓａｎｄｔｈｅａｎａｌｏｇｏｕｓｃｏｂａｌｔａｓｗｅｌｌａｓｃｈｒｏｍｉｕｍｃｏｍｐｌｅｘ ｅｓｂｅｃａｕｓｅｏｆｔｈｅｉｒｐｏｔｅｎｔｉａｌａｓｃａｔａｌｙｔｉｃ ,ｓｅｍｉ ｃｏｎｄｕｃｔｉｖｅ ,ａｎｄｍａｇｎｅｔｉｃｍａｔｅｒｉａｌｓ[1～ 9] .Ａｎｄ ,ｓｏｍｅｏｆｔｈｅｓｅｃｙａｎｉｄｅｓａｒｅｓｅｍｉｐｅｒｍｅ ａｂｌｅｍｅｍｂｒａｎｅｓｗｈｉｃｈａｒｅｖ…     

Growth and characterization of ferroelectric Tb2（MoO4）3 crystal

By using Zb4O7 and MoO4 as starting materials, ferroelectric Tb2(MoO4)3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction (XRPD), transmission spectrum, dielectric con-stant and polarization-electric field (P-E) hysteresis loop measurements were performed to characterize the crystal. The XRPD confirmed the as-grown crystal to be Tb2(MoO4)3. The transmission spectrum of the crystal showed that its transmittance in the entire visible and most near-infrared region was more than 70% except for an absorption peak around 486 nm. Obvious dielectric anomaly could be observed at low frequencies with increasing temperature through the dielectric constant measurement and the Curie temperature of Tb2(MoO4)3 crystal was determined to be 162.3℃. The unsaturated P-E hysteresis loops indicated that it was difficult for the ferroelectric domains in Tb2(MoO4)3 crystal to array regularly with repeated switching of the electric field.     

Energy transfer from Ce~(3+) to Tb~(3+) and Eu~(3+) in zinc phosphate glasses

Ce3+,Eu3+ and Tb3+ singly doped and Ce3+/Eu3+ and Ce3+/Tb3+ co-doped zinc phosphate glasses were prepared by sintering P2O5,ZnO,Ce2(C2O4)3·10H2O and Eu2O3/Tb4O7 mixtures at 1200 °C in the air for 2 h and then annealing at 450 °C for 10 h.The obtained glasses were homogeneous and transparent.The glasses without Ce3+ were colorless and those with Ce3+ showed slightly yellow.The singly doped glasses showed strong emissions and excitations from doped trivalent rare earth ions.Strong energy transfer from Ce3+ to Tb3+ was observed for Ce3+/Tb3+ coped samples.There were also some very weak evidences for the energy transfer from Ce3+ to Eu3+.     

Ab Initio Calculation of 4f→5d Transition Energy and Electronic Structure of Ce3+ Doped in LiYF4 Crystal

The electronic structures of LiYF4:Ce3 and LiYF4 crystals simulated by an embedded (in a microcrystal containing 1938 ions) cluster CeY4Li8F24, and Y5Li8F24 respectively, were computed by the ab initio self-consistent relativistic DV-Xa(discrete variational Xa) method. The ground-state calculation showed that only the lowest 5d level Ed of Ce3 ion lies around the BCB (bottom of the conduction band) while the lowest 4f levels is 2.5 eV lower than BCB. The CB states consist of 4p of Y mixed with 5d of Ce, even for the wavefunctions (WFS) of Ed under BCB there are still 24% of Y-4p and 9% of F-2p as components. Furthermore, transition state (TS) calculation was performed in this work to obtain the 4f→5d transition energies Efd, to improve the calculation of Ref.[6] in which a small CeF8 cluster embedded in an array of point charge was used and the results of ground-state calculation were roughly used to compare directly with the observed 4f→5d transition energies. The ionic radius of Ce3 is larger than that of Y3 , for modeling approximately the lattice relaxation, we simply let the eight fluorine ions of the nearest-neighbor and next-nearest-neighbor move out radially and simultaneously. As results, the CeY4Li8F24 cluster with 4.56% outward relaxation of the eight fluorines has the lowest total energy and gave satisfactory 4f→5d energies Efd, but the calculated ground-state Ed is 0.68 eV higher than BCB. For another cluster with 7.36% outward relaxation the Ed is 0.43 eV lower than BCB, which makes the observation of fine structure (including zero-phonon line) of the lowest 5d band understandable easier, but the splits between the transition energies Efd were not as good as the former. Therefore, we consider the relaxation is somehow around 4.56%～7.36% outward, not as large as 10%.