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Eu3+
Terms modified by Eu3+ Selected AbstractsBifunctional Eu3+ -doped Gd2O3 nanoparticles as a luminescent and T1 contrast agent for stem cell labelingCONTRAST MEDIA & MOLECULAR IMAGING, Issue 2 2010Zhilong Shi Abstract Magnetic resonance tracking of stem cells has recently become an emerging application for investigating cell,tissue interactions and guiding the development of effective stem cell therapies for regeneration of damaged tissues and organs. In this work, anionic Eu3+ -doped Gd2O3 hybrid nanoparticles were applied as a contrast agent both for fluorescence microscopy and T1 -weighted MRI. The nanoparticles were synthesized through the polyol method and further modified with citric acid to obtain anionic nanoparticles. These nanoparticles were internalized into human mesenchymal stem cells (hMSCs) as confirmed by confocal laser scanning microscopy and quantified by inductively coupled plasma,mass spectrometry. MTT assay of the labeled cells showed that the nanoparticles did not possess significant cytotoxicity. In addition, the osteogenic, adipogenic and chondrogenic differentiation of the hMSCs was not influenced by the labeling process. With MRI, the in vitro detection threshold of cells after incubation with nanoparticles at a Gd concentration of 0.5,mMfor 2,h was estimated to be about 10 000 cells. The results from this study indicate that the biocompatible anionic Gd2O3 nanoparticles doped with Eu3+ show promise both as a luminescent and T1 contrast agent for use in visualizing hMSCs. Copyright © 2010 John Wiley & Sons, Ltd. [source] EuIII -Doping of Lamellar Bilayer and Amorphous Mono-Amide Cross-Linked Alkyl/Siloxane HybridsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2010Silvia C. Nunes Abstract Two structurally different but chemically similar families of alkyl/siloxane mono-amidosil hosts, represented by m-A(x) [where x = 14 or 8 represents the number of CH2 groups of the pendant alkyl chains directly bonded to the carbonyl group of the amide cross-link] have been doped with a wide range of concentrations of Eu(CF3SO3)3. Mono-amidosils m-A(x)nEu(CF3SO3)3 with n,,,10 (where n is the molar ratio of carbonyl groups per Eu3+ ion) have been analyzed. The m-A(8)nEu(CF3SO3)3 mono-amidosils are transparent and amorphous films, in which the alkyl chains adopt gauche conformations. In contrast, the m-A(14)nEu(CF3SO3)3 mono-amidosils are solid powders; here the lamellar bilayer hierarchical structure of m-A(14) coexists with a new lamellar phase in which the Eu3+ ions are bonded to carbonyl oxygen atoms of the amide groups. At n = 10 the hydrogen-bonded associations formed are highly ordered and considerably stronger than those found in the less concentrated hybrids and in the nondoped matrices. "Free" and weakly coordinated triflate ions occur in all the mono-amidosil samples. The hybrids are white light emitters (maximum quantum yield: 0.08,±,0.01), presenting a broad emission band in the blue/purplish-blue spectral region (ascribed to the hybrid host) superimposed on the 5D0,7F0,4 Eu3+ intra-4f6 transitions. Two Eu3+ local coordination sites (named A and B) have been discerned in both systems. Site A is attributed to weakly coordinated Eu3+/CF3SO3, ion pairs, whereas site B involves Eu3+ coordination to the oxygen atoms of the C=O groups, of the CF3SO3, ions and of the water molecules. For site B, the long-range order of the hybrid host induces distinct features in the energy of the 5D0,7F0,4 transitions, the 5D0 lifetime and the degree of covalency of the Eu3+,first-ligand bonds. [source] Self-Assembled Lanthanide Salicylaldimines with a Unique Coordination ModeEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2010gorzata T. Kaczmarek Abstract New lanthanide salicylaldimine complexes of the formula [Ln(H2L)3(NO3)3](H2L), where Ln = La3+ (1), Nd3+ (2), Eu3+ (3), Gd3+ (4), Ho3+ (5), Er3+ (6), Tb3+ (7) or Yb3+ (8), and H2L = N,N,-bis(salicylidene)-4-methyl-1,3-phenylenediamine, were formed in a self-assembly process involving the lanthanide template-induced one-step [2+1] Schiff base condensation reaction between salicylaldehyde and 4-methyl-1,3-phenylenediamine. The unusual coordination pattern of salen-type ligands in these complexes, in which the three potentially tetradentate N2O2 salicylaldimines function as undeprotonated, monodentate, exclusively O-donor ligands without involving the nitrogen atoms in the coordination environment, was proved by single-crystal X-ray diffraction analysis and correlated with spectroscopic characterization. In this species with the nine-coordinate distorted tricapped trigonal prism geometry, the nitrates act as bidentate chelators occupying six coordination sites and leaving the remaining sites available for salicylaldimine ligands formed in situ in the template process. The additional salicylaldimine molecule acts as a guest for the salicylaldimine complex host and stabilizes the overall self-assembled supramolecular network. [source] Facile Synthesis of Bastnaesite -Type LaF[CO3] and Its Thermal Decomposition to LaOF for Bulk and Eu3+ -Doped SamplesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2009Oliver Janka Abstract Rare-earth metal(III) oxide fluorides with the composition MOF (M = La,Lu) seem to offer promising host lattices for luminescence applications by doping these materials with trivalent lanthanoid cations. Unfortunately, there was no simple and practicable way to synthesize the compounds in phase-pure quality with classical solid-state chemistry reactions. However, by using the rare-earth metal(III) fluoride oxocarbonates, MF[CO3], as solution-born precursor materials that crystallize with a bastnaesite -type structure, easy access is now possible by mild thermal decomposition. Synthetic details, investigations on the phase purity and the presence of the oxocarbonate anion [CO3]2, proved by IR measurements as well as from X-ray powder diffraction data are given in this paper for the example of bulk LaF[CO3] and Eu3+ -doped samples. The latter (LaF[CO3]:Eu3+) shows a bright orange-red luminescence that is stronger than that of the product of its thermal decomposition: trimorphic LaOF:Eu3+.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A PCP-Pincer RuII,Terpyridine Building Block as a Potential "Antenna Unit" for Intramolecular SensitizationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007Marcella Gagliardo Abstract The redox- and photoactive mononuclear complex [Ru(PCP)(tpy,DTTANa4)]Cl {PCP = [C6H3(CH2PPh2)2 -2,6],; tpy,DTTA4, = 4,-(2,2,:6,,2,-terpyridine)-diethylenetriamine- N,N,N,,N, -tetraacetate} possesses an externally directed, vacant N3O4 polyaminocarboxylate-type binding site that coordinates to lanthanide(III) ions to give the neutral heterodinuclear RuII,LnIII complexes [Ru(PCP)(tpy,DTTA)Ln(H2O)2] (Ln = Gd3+, Eu3+). The photophysical properties of solutions of the mononuclear complex [Ru(PCP)(tpy,DTTANa4)]Cl were investigated in MeOH/EtOH (1:4) and compared to those of the solutions of heterodinuclear complexes [Ru(PCP)(tpy,DTTA)Ln(H2O)2] (Ln = Gd3+, Eu3+). Rigid matrix excitation at 77 K of the ,,* level of the ruthenium chromophore in the [Ru(PCP)(tpy,DTTA)Eu(H2O)2] complex results in a weak europium(III) emission pointing to a transfer of energy from Ru,Eu as a result of the metal-to-ligand charge-transfer (MLCT) excited state of the ruthenium component to the luminescent lanthanide ion. The excited state lifetime of the europium complex is 0.2 ms in methanol solution. In deuterated solvents, the lifetime increases to 0.4 ms, which indicates that the process is solvent-dependent as a result of the strongly coordinated molecules of water that are responsible for the quenching in nondeuterated solvents.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Series of Lithium Rare Earth Polyphosphates [LiLn(PO3)4] (Ln = La, Eu, Gd) and Their Structural, Optical, and Electronic PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2007Jing Zhu Abstract The structural, optical, and electronic properties of a series of lithium rare earth polyphosphates [LiLn(PO3)4] [Ln = La (1), Eu (2), Gd (3)] have been investigated by means of single-crystal X-ray diffraction, elemental analyses, and spectroscopic measurements, as well as calculations of energy-band structures, density of states, and optical response functions by density functional methods. These LiLn(PO3)4 systems are monoclinic with space group C2/c and Z = 4. Their unit-cell parameters decrease as the ionic radius of Ln3+ decreases (La3+ > Eu3+ > Gd3+). Both (PO4)3, zig-zag chains and infinite chains formed by the alternate connection of LnO8 polyhedra and LiO4 tetrahedra run parallel to the b -axis in the structure. The energy-band structures, density of states, the chemical bonds, and optical properties have been investigated by density functional methods for some of the title compounds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Silica Supported Submicron SiO2@Y2SiO5:Eu3+ and SiO2@Y2SiO5:Ce3+/Tb3+ Spherical Particles with a Core,Shell Structure: Sol,Gel Synthesis and CharacterizationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006Cuikun Lin Abstract X1 -Y2SiO5:Eu3+ and X1 -Y2SiO5:Ce3+ and/or Tb3+ phosphor layers have been coated on nonaggregated, monodisperse, submicron spherical SiO2 particles by a sol,gel process, followed by surface reaction at high temperature (1000 °C), to give core/shell structured SiO2@Y2SiO5:Eu3+ and SiO2@Y2SiO5:Ce3+/Tb3+ particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), TEM, photoluminescence (PL), low voltage cathodoluminescence (CL), and time-resolved PL spectra and lifetimes are used to characterize these materials. The XRD results indicate that X1 -Y2SiO5 layers have been successfully coated on the surface of SiO2 particles, as further verified by the FESEM and TEM images. The PL and CL studies suggest that SiO2@Y2SiO5:Eu3+, SiO2@Y2SiO5:Tb3+ (or Ce3+/Tb3+), and SiO2@Y2SiO5:Ce3+ core/shell particles exhibit red (Eu3+, 613 nm: 5D0,7F2), green (Tb3+, 542 nm: 5D4,7F5), or blue (Ce3+, 450 nm: 5d-4f) luminescence, respectively. PL excitation, emission, and time-resolved spectra demonstrate that there is an energy transfer from Ce3+ to Tb3+ in the SiO2@Y2SiO5:Ce3+,Tb3+ core/shell particles. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Template Synthesis, Crystal Structure and Luminescent Properties of Neutral N4O3 Tripodal LnIIIL Complexes (LnIII = La3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+ or Lu3+; H3L = Tris{[3,-(2,,-pyridyl)-5,- tert -butyl-2,-hydroxybenzylidene-2-imino]ethyl}amine)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2004Wai-Kwok Wong Abstract In the presence of Ln3+ (Ln = La, Eu, Gd, Tb, Dy, Ho, Er, Tm or Lu), tris(2-aminoethyl)amine condensed with three equivalents of 3-(2,-pyridyl)-5- tert -butyl-2-hydroxybenzaldehyde in methanol to give the neutral Schiff-base complex LnIIIL (Ln = La 1, Eu 2, Gd 3, Tb 4, Dy 5, Ho 6, Er 7, Tm 8 and Lu 9; H3L = tris{[3,-(2,,-pyridyl)-5,- tert -butyl-2,-hydroxybenzylidene-2-imino]ethyl}amine). The structures of compounds 4,7 were determined by X-ray crystallography. The crystal structure analyses revealed that the Schiff base behaves as a tri-deprotonated heptadentate ligand encapsulating the lanthanide metal ion within the N4O3 cavity, with all the pyridyl groups being pendant. Solution spectroscopic data suggest that the LnIIIL complexes remain intact in methanol and exist as nine-coordinate non-electrolytes with the lanthanide metal ions coordinated to the N4O3 cavity of the tripodal Schiff base and two solvent molecules. The solution photoluminescent properties of these lanthanide Schiff-base complexes were also examined. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] First Examples of Ternary Lanthanide 2,2,-Diphenyldicarboxylate Complexes: Hydrothermal Syntheses and Structures of Lanthanide Coordination Polymers of 2,2,-Diphenyldicarboxylic Acid and 1,10-PhenanthrolineEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2003Yibo Wang Abstract In the four new lanthanide coordination polymers {[La2(2,2,-dpdc)3(phen)(H2O)]·2H2O}n (1), [Eu2(2,2,-dpdc)3(phen)(H2O)2]n (2), {[Ln2(2,2,-dpdc)3(phen)2(H2O)2]·4H2O}n [Ln = Tb (3), Yb (4)] (2,2,-dpdc = 2,2,-diphenyldicarboxylate, phen = 1,10-phenanthroline), prepared by hydrothermal synthesis, the 2,2,-dpdc dianion affords tetradentate, pentadentate, and hexadentate coordination modes. Complex 1 is a two-dimensional network of infinite 1-D chains assembled through ,,, interactions, with nine- and ten-coordinate La3+, and arranged in wave-like layers. In 2, Eu3+ possesses nine- and ten-coordinate geometries bridged by 2,2,-dpdc ligands to give a 3-D structure. The isomorphous complexes 3 and 4, in which Tb3+ and Yb3+ ions are both nine-coordinate, have two-dimensional structures of 1-D zigzag chains stacked via hydrogen bonds and ,,, interactions of phen molecules. The high-resolution emission spectrum of 2 shows two Eu3+ ion sites, which is consistent with the results of the X-ray crystal structure analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln3+ -Doped Gd2O3 NanotubesADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Andreia G. Macedo Abstract There is a growing interest in understanding how size-dependent quantum confinement affects the photoluminescence efficiency, excited-state dynamics, energy-transfer and thermalization phenomena in nanophosphors. For lanthanide (Ln3+)-doped nanocrystals, despite the localized 4f states, confinement effects are induced mostly via electron,phonon interactions. In particular, the anomalous thermalization reported so far for a handful of Ln3+ -doped nanocrystals has been rationalized by the absence of low-frequency phonon modes. This nanoconfinement may further impact on the Ln3+ luminescence dynamics, such as phonon-assisted energy transfer or upconversion processes. Here, intriguing and unprecedented anomalous thermalization in Gd2O3:Eu3+ and Gd2O3:Yb3+,Er3+ nanotubes, exhibiting up to one order of magnitude larger than previously reported for similar materials, is reported. This anomalous thermalization induces unexpected energy transfer from Eu3+C2 to S6 crystallographic sites, at 11,K, and 2H11/2,,,4I15/2 Er3+ upconversion emission; it is interpreted on the basis of the discretization of the phonon density of states, easily tuned by varying the annealing temperature (923,1123,K) in the synthesis procedure, and/or the Ln3+ concentration (0.16,6.60%). [source] Combined Optical and MR Bioimaging Using Rare Earth Ion Doped NaYF4 NanocrystalsADVANCED FUNCTIONAL MATERIALS, Issue 6 2009Rajiv Kumar Abstract Here, novel nanoprobes for combined optical and magnetic resonance (MR) bioimaging are reported. Fluoride (NaYF4) nanocrystals (20,30,nm size) co-doped with the rare earth ions Gd3+ and Er3+/Yb3+/Eu3+ are synthesized and dispersed in water. An efficient up- and downconverted photoluminescence from the rare-earth ions (Er3+ and Yb3+ or Eu3+) doped into fluoride nanomatrix allows optical imaging modality for the nanoprobes. Upconversion nanophosphors (UCNPs) show nearly quadratic dependence of the photoluminescence intensity on the excitation light power, confirming a two-photon induced process and allowing two-photon imaging with UCNPs with low power continuous wave laser diodes due to the sequential nature of the two-photon process. Furthermore, both UCNPs and downconversion nanophosphors (DCNPs) are modified with biorecognition biomolecules such as anti-claudin-4 and anti-mesothelin, and show in vitro targeted delivery to cancer cells using confocal microscopy. The possibility of using nanoprobes for optical imaging in vivo is also demonstrated. It is also shown that Gd3+ co-doped within the nanophosphors imparts strong T1 (Spin-lattice relaxation time) and T2 (spin-spin relaxation time) for high contrast MR imaging. Thus, nanoprobes based on fluoride nanophosphors doped with rare earth ions are shown to provide the dual modality of optical and magnetic resonance imaging. [source] Organized Nanostructured Complexes of Polyoxometalates and Surfactants that Exhibit Photoluminescence and ElectrochromismADVANCED FUNCTIONAL MATERIALS, Issue 4 2009Tierui Zhang Abstract A variety of functional nanostructured organic/inorganic hybrid materials from the europium-exchanged derivative of a Preyssler-type polyoxometalate (POM), [EuP5W30O110]12,, and functional organic surfactants were prepared by the ionic self-assembly (ISA) route. The effect of organic surfactants on the structure, photoluminescent, electrochemical and electrochromic properties of the POM anions was investigated in detail. All obtained hybrid materials are amphotropic, i.e., exhibit both thermotropic and lyotropic liquid-crystalline phase behaviour. Investigations of their photophysical properties have shown that the interactions of the various surfactants with the polyanions influence the coordination environments and site symmetry of Eu3+ in different ways. The functional groups in the organic surfactants significantly influence the electrochromic properties and photoluminescence of POMs. Different from normal and pyridine-containing complexes, no photoluminescence and no electrochromism were observed from the ferrocene-containing complexes. This may be explained in view of charge transfer between the POM anion and the ferrocenyl group. [source] Spectroscopic Investigation of the Europium(3+) Ion in a New ZnY4W3O16 MatrixHELVETICA CHIMICA ACTA, Issue 11 2009bieta Tomaszewicz Abstract A new Zn and Eu tungstate was characterized by spectroscopic techniques. This tungstate, of the formula ZnEu4W3O16, crystallized in the orthorhombic system and was synthesized by a solid-state reaction. It melts incongruently at 1330°. The luminescent properties, including excitation and emission processes, luminescent dynamics, and local environments of the Eu3+ ions in ZnEu4W3O16 and ZnY4W3O16,:,Eu3+ diluted phases (1, 5, and 10,mol-% of Eu3+ ion) were studied basing on the f6 -intraconfigurational transitions in the 250,720,nm spectral range. The excitation spectra of this system (,em 615 and 470,nm) show broad bands with maxima at 265 and 315,nm related to the ligand-to-metal charge-transfer (LMCT) states. The emission spectra under excitation at the O,W (265,nm) and O,Eu3+ (315,nm) LMCT states present the blue-green emission bands. The emission of tungstate groups mainly originate from the charge-transfer state of excited 2p orbitals of O2, to the empty orbitals of the central W6+ ions. On the other hand, in the emission of the Eu3+ ions, both the charge transfer from O2, to Eu3+ and the energy transfer from W6+ ions to Eu3+ are involved. The emission spectra under excitation at the 7F0,5L6 transition of the Eu3+ ion (394,nm) of ZnY4W3O16,:,Eu3+ diluted samples show narrow emission lines from the 5D3, 5D2, and 5D1 emitting states. The effect of the active-ion (Eu3+) concentration on the colorimetric characteristic of the emissions of the compound under investigation are presented. [source] Minocycline-Based Europium(III) Chelate Complexes: Synthesis, Luminescent Properties, and Labeling to StreptavidinHELVETICA CHIMICA ACTA, Issue 11 2009Takuya Nishioka Abstract Two chelate ligands for europium(III) having minocycline (=(4S,4aS,5aR,12aS)-4,7-bis(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy-1,11-dioxonaphthacene-2-carboxamide; 5) as a VIS-light-absorbing group were synthesized as possible VIS-light-excitable stable Eu3+ complexes for protein labeling. The 9-amino derivative 7 of minocycline was treated with H6TTHA (=triethylenetetraminehexaacetic acid=3,6,9,12-tetrakis(carboxymethyl)-3,6,9,12-tetraazatetradecanedioic acid) or H5DTPA (=diethylenetriaminepentaacetic acid=N,N -bis{2-[bis(carboxymethyl)amino]ethyl}glycine) to link the polycarboxylic acids to minocycline. One of the Eu3+ chelates, [Eu3+(minocycline-TTHA)] (13), is moderately luminescent in H2O by excitation at 395,nm, whereas [Eu3+(minocycline-DTPA)] (9) was not luminescent by excitation at the same wavelength. The luminescence and the excitation spectra of [Eu3+(minocycline-TTHA)] (13) showed that, different from other luminescent EuIII chelate complexes, the emission at 615,nm is caused via direct excitation of the Eu3+ ion, and the chelate ligand is not involved in the excitation of Eu3+. However, the ligand seems to act for the prevention of quenching of the Eu3+ emission by H2O. The fact that the excitation spectrum of [Eu3+(minocycline-TTHA)] is almost identical with the absorption spectrum of Eu3+ aqua ion supports such an excitation mechanism. The high stability of the complexes of [Eu3+(minocycline-DTPA)] (9) and [Eu3+(minocycline-TTHA)] (13) was confirmed by UV-absorption semi-quantitative titrations of H4(minocycline-DTPA) (8) and H5(minocycline-TTHA) (12) with Eu3+. The titrations suggested also that an 1,:,1 ligand Eu3+ complex is formed from 12, whereas an 1,:,2 complex was formed from 8 minocycline-DTPA. The H5(minocycline-TTHA) (12) was successfully conjugated to streptavidin (SA) (Scheme,5), and thus the applicability of the corresponding Eu3+ complex to label a protein was established. [source] A Strategy to Achieve Efficient Dual-Mode Luminescence of Eu3+ in Lanthanides Doped Multifunctional NaGdF4 NanocrystalsADVANCED MATERIALS, Issue 30 2010Yongsheng Liu A strategy is proposed to fabricate dual-mode luminescent NaGdF4 nanocrystals that are composed of NaGdF4:Yb3+,Tm3+ core and NaGdF4:Eu3+ shell. Intense downconversion via the sensitization of Gd3+ and upconversion luminescence of Eu3+ that is one order of magnitude higher than the triply-doped core only counterparts have been achieved by employing the distinct core/shell nanostructures and double sensitizations of Yb3+ and Tm3+. [source] Effects of Rare-Earth Dopants on the Ferroelectric and Pyroelectric Properties of Strontium Barium Niobate CeramicsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 6 2009Yingbang Yao Effects of various rare-earth (RE) dopants (Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tm3+, Dy3+, Er3+, and Yb3+) on the dielectric, ferroelectric, and pyroelectric properties of Sr0.5Ba0.5Nb2O6 (SBN50) ceramics were investigated. In the present studies, the doping concentrations of all the RE dopants were fixed at 1 mol%. Their potential usefulness in pyroelectric applications was discussed based on their measured pyroelectric detectivity figure of merit (FOM). On the basis of our studies, for RE dopants with atomic numbers smaller than Nd, their dielectric constants were greatly increased, while for RE dopants with atomic numbers larger than Sm, their dielectric constants as well as dielectric losses became smaller. Among various dopants, Eu-doped SBN showed the most improved ferroelectric properties. Its remnant polarization (Pr) was increased to 4.86 ,C/cm2 as compared with 3.23 ,C/cm2 obtained in undoped SBN50. On the other hand, Gd-doped SBN exhibited the largest pyroelectric coefficient of 168 ,C/m2 K, which was over three times of that of the undoped sample (49 ,C/m2 K). The work shows that Gd-doped SBN exhibits the greatest potential for pyro-applications because it bears the largest FOM of 0.45 × 10,5 Pa,0.5 [Correction: After online publication on 11/05/2008, an error was found in this article. The original value, 1.35×10,5 Pa,0.5, was incorrect. The data has been replaced with the correct value.]. [source] A Novel Narrow Band Red-Emitting Phosphor for White Light Emitting DiodesINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 4 2009Sivakumar Vaidyanathan Research on down conversion phosphor materials is the key for the development of solid-state lighting (SSL). Especially finding alternative red phosphor for white light emitting diodes (LEDs) based on blue or near ultraviolet (NUV) LEDs is important research task. In this view, we have synthesized a series of Eu3+ -substituted La2W2,xMoxO9 (x=0,2, in step of 0.3) red phosphor and characterized by X-ray diffraction (XRD) and photoluminescence. XRD results reveal a phase transition from triclinic to cubic structure for x>0.2. All the compositions show broad charge transfer (CT) band due to CT from oxygen to tungsten/molybdenum and red emission due to Eu3+ ions. Select compositions show high red emission intensity compared with the commercial red phosphor under NUV/blue ray excitation. Hence, this candidate can be a possible red phosphor for white LEDs. [source] Theoretical and experimental luminescence quantum yields of coordination compounds of trivalent europiumINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2005Wagner M. Faustino Abstract An appraisal of a semiempirical methodology recently introduced by us for the theoretical calculation of luminescence quantum yields is presented. Six coordination compounds of Eu3+ were considered, possessing either benzoylacetonate or benzoyltrifluoroacetonate, together with either water, 2,2,-bipyridine, or 1,10-phenanthroline as ligands. Their geometries were calculated using the SMLC/AM1 method. The ligand,Eu3+ energy transfer rates were calculated in terms of a model of intramolecular energy transfer processes in lanthanide coordination compounds developed earlier by our group. The luminescence quantum yields of the complexes were calculated by solving numerically a system of rate equations for each compound, and by comparing them with the quantum yields determined spectroscopically. Finally, we show that the theoretical quantum yields correlate linearly with the experimental yields, within their error bars. Such linear correlation indicates that the theoretical approach can be useful for the a priori design of highly luminescent lanthanide coordination compounds. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source] Assessment of urinary total testosterone production by a highly sensitive time-resolved fluorescence immunoassay ,JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 6 2008Shihua Bao Abstract Radioimmunoassay (RIA) that involves purification of the analyte by organic solvent extraction is widely used. Although the extraction RIA is reliable when properly validated, it is time consuming and radioactive, we measure urinary total testosterone with a highly sensitive rapid and accurate time-resolved fluorescence immunoassay (TRFIA) method. High affinity antitestosterone antibody and Eu3+ labeled Donkey antisheep IgG as tracers were used. The assay was evaluated for specificity, sensitivity, analytical recovery, precision and dilution linearity by the TRFIA method on urine samples. A satisfactory standard curve for testosterone TRFIA has been developed with good sensitivity (5.1,pmol/L). The validity of the assay for urinarytotal testosterone was confirmed by thegood correlation between the results obtained by TRFIA (X) and those RIA (Y) (Y=0.075+0.971X, R=0.992). Specificity, analytical recovery, precision and dilution linearity studies were determined and all found to be satisfactory. Male urinary total testosterone excretion ranged from 64.00 to 374.11,nmol/24,hr, which was about four times more than the range for women urinary testosterone excretion (14.16,100.65,nmol/24,hr), which suggests that a direct, reliable, easy to automate, highly sensitive and specific TRFIA type assay for the measurement of total testosterone in urine samples has been developed. J. Clin. Lab. Anal. 22:403,408, 2008. © 2008 Wiley-Liss, Inc. [source] Room-Temperature Solid-State Reaction Behavior, Hydrothermal Crystallization and Physical Characterization of NaRE(MoO4)2, and Na5Lu(MoO4)4 CompoundsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Jianhua Wu In the context, a novel composite synthesis technology is engaged in the preparation of NaRE(MoO4)2 (RE=Y, La, Nd, Eu, Gd, Tb, Er, and Yb) and Na5Lu(MoO4)4 compounds, which involves a room-temperature solid-state reaction and hydrothermal crystallization process. The synthesis mechanism is predicted, indicating that higher temperature and moisture can speed up the reaction process and especially the existence of crystalline water molecules in the precursor is necessary for the solid-state reaction at room temperature. It is found that different rare-earth nitrate precursors present different reactivity to sodium molybdate at room temperature. The crystallization degree of the products after the room-temperature solid-state reaction depends on the melting point of rare-earth nitrate precursors. The hydrothermal treatment is beneficial for the good crystallization of NaRE(MoO4)2 (RE=Y, La, Nd, Eu, Gd, Tb, Er, and Yb) and Na5Lu(MoO4)4. Finally, the photoluminescent spectra for these NaRE(MoO4)2:Eu3+ (La, Gd, and Y) are studied, which depend on the species of rare-earth ions. [source] Reproducible Solvent,Thermal Synthesis, Controlled Microstructure, and Photoluminescence of REPO4:Eu3+, Tb3+ (RE=Y, La, and Gd) NanophosphorsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2010Xiuzhen Xiao By altering the temperature and solvents, we have synthesized hydrated and dehydrated Eu3+/Tb3+ -doped REPO4 (RE=Y, La, and Gd) nanophosphors via a solvo-thermal technology. X-ray powder diffraction and scanning electronic microscopy reveal that they have different structures and different morphologies. REPO4 prepared under subsequent heating at 80°, 120°, and 160°C for 1 day, respectively, present larger particle size than that formed by heating at 160°C for 3 days. Moreover, at the same temperature of 160°C and pH 3, three different solvents (ethanol, N,N -dimethylformamide (DMF), and water) were used, whose influence on the microstructure of LaPO4 has been examined. As a result, LaPO4 samples from anhydrous ethanol solvent show a pure hexagonal phase and nanowire morphology, just like that prepared from the water solvent. On the other hand, the microstructure of LaPO4 samples from DMF,H2O-mixed solvents have been changed: with the increasing volume ratio of DMF to H2O, the crystal phase of LaPO4 has been changed from hexagonal phase to monoclinic phase and the morphology from nanowires to nanoparticles. Finally, the photoluminescence properties of these Eu3+ (Tb3+)-activated rare earth phosphates have been investigated, indicating that the photoluminescent behavior are related to their crystal phases and microstructures. [source] A Potential Red-Emitting Phosphor BaGd2(MoO4)4:Eu3+ for Near-UV White LEDJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Chongfeng Guo Red-emitting phosphor BaGd2,xEux(MoO4)4 has been successfully synthesized by a simple sol,gel method. The process of phosphor formation is characterized by thermogravimetric-differential thermal analysis and X-ray diffraction. Field-emission scanning electronic microscopy is used to characterize the size and the shape of the phosphor particles. Photo-luminescent property of the phosphor is also performed at the room temperature. The effects of firing temperature and Eu3+ activator concentration on the photoluminescence (PL) properties are elaborated in detail. PL characterization reveals that the sample with the firing temperature at 800°C and the concentration of Eu3+ at 0.7 shows the most intense emission, and its intensity is about three times stronger than that of phosphor prepared by solid-state method with the same composition and firing temperature. The new red-emitting phosphor shows an intense absorption at 396 nm, which matches well with commercial near-UV light-emitting diode (LED) chips, therefore, it is a good candidate of red phosphor used for near-UV white LEDs. [source] Spectroscopic Properties and Local Structure of Eu3+ in Ge,Ga,S,CsBr (or CsCl) GlassesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2003Woon Jin Chung Spectroscopic properties and local structure of Eu3+ in Ge,Ga,S,CsBr (or CsCl) glasses were investigated using fluorescence measurements and several spectroscopic methods. Fluorescence from Eu3+:5D0,7F2 was observed only from glasses with CsBr/Ga ratios greater than unity and disappeared at temperatures above 140 K. Phonon sideband (PSB) spectra revealed that Eu3+ ions are located next to halogen ions, which form part of well-structured complexes such as EuCl3, tetrahedral [GaS3/2Cl],, subunits and/or Ga2Cl6. These new bonds showed reduced coupling strength compared with Eu3+,S bonds in Ge,Ga,S glass. Fluorescence line narrowing experiments showed little site-to-site variation of Eu3+ ions. [source] Studies on Preparation and Fluorescent Properties of a Novel Photo-Sensitive Nanoparticle Composed of Europium Ion and Cinnamic Acid DerivativeMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 23 2009Dongjian Shi Abstract A novel fluorescent and photo-sensitive nanoparticle was self-assembled from an europium-based random copolymer, europium coordinated poly(methylacrylic acid)- co -poly(cinnamyl acrylate) (PMCFA-Eu3+), which was synthesized from methylacrylic acid (MAA), and Eu3+ -cinnamyl acrylate derivative (CFA) by radical polymerization. DLS and TEM results indicated the formation of spherical nanoparticles with 120,nm in diameter. The PMCFA-Eu3+ complex showed stronger fluorescence than Eu3+, indicating the effective energy transferred from the ligand to Eu3+. Moreover, the photo-crosslinking of the cinnamate groups induced a decrease in the diameter and an increase in the fluorescent properties of the PMCFA-Eu3+ nanoparticles. This functional nanoparticle might be useful as a carrier and a fluorescence probe in biomedical and fluorescent fields. [source] Preparation and Fluorescent and Magnetic Properties of Polyurethane/Eu(MA)3 FilmsMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 24 2007Shuxue Zhou Abstract Europium(III) (Eu3+)-doped polyurethane films were prepared by mixing Eu-methacrylic acid complex (Eu(MA)3) with aliphatic polyurethane oligomer and subsequently curing under UV irradiation. Transmission electron microscopy photos and the appearance of the resulting hybrid films showed that phase separation occurred only at an Eu(MA)3 content above 20 wt.-%. Fluorescence spectra indicated that the fluorescence of Eu3+ was barely influenced by the polyurethane matrix and its intensity increased with an Eu(MA)3 content in the range of approximately 0 to 10 wt.-%. An obvious applied external-field-dependent magnetization (M) of polyurethane/Eu(MA)3 films, namely, an increasing M at low field and a decreasing M at high field, was observed at room temperature from the hysteresis loops, which was influenced by both the Eu(MA)3 content and the ultrasonication imposed on the coatings before curing. It seems that ultrasonication leads to a thermodynamically-unstable structure of Eu3+ in hybrid films, which can be fixed by UV curing but gradually rearranges to its original form during the thermal-curing process, and enhances the diamagnetic part of the hybrid film. Thus, the magnetic property of Eu3+ -doped polyurethane film at room temperature can be adjusted by simply changing the preparation method and the Eu(MA)3 content instead of the type of Eu3+ -organic complex. [source] Effects of Al composition on luminescence properties of europium implanted AlxGa1,xN (0 , x , 1)PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2003Y. Nakanishi Abstract Europium (Eu) ions are introduced into AlxGa1,xN (0 , x , 1) by implantation to investigate the effect of Al composition on the luminescence properties. For all samples with Al contents between 0 and 100%, strong and sharp red emission peaks related to the 4f,4f intra transitions of Eu3+ are observed around 600 , 660 nm at room temperature. The intensity of the Eu3+ -related luminescence increases with increasing Al contents, and the photoluminescence of 5D0,7F2 transition related to Eu3+ shows strongest intensity at Al = 50%. The intensity is 100 times stronger than that of Eu in GaN, and several times stronger than that of near-band-edge emission for un-doped GaN. These results suggest that the luminescence property of Eu3+ can be dramatically improved by using Al0.5Ga0.5N as a host material. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Facile fabrication of novel Eu-containing copolymer and luminescent propertiesPOLYMER ENGINEERING & SCIENCE, Issue 7 2009Ziqun Huang A new Eu-containing copolymer was successfully fabricated through two steps. First, the Eu-containing monomer was synthesized from 4-Vinylbenzoic acid and europium ion (Eu3+) complex, which rare-earth ions connect with the ligand by covalent bands. Next, the copolymer was obtained by free-radical copolymerization of Eu-containing monomer with methyl methacrylate using 2, 2,-azobis(isobutyronitrile) (AIBN) as initiator at low temperature. Infrared spectroscopy, gel permeation chromatography and scanning electron microscopy were applied to characterize the structure of the polymer. UV-visible absorption/photoluminescence spectra and fluorescence spectra were taken to valuate the photophysical properties of the obtained Eu-containing copolymer. The experimental result shows that the strong luminescence of europium ions substantiates optimum energy match and effective intramolecular energy transfer between the triplet state energy of coordination complex and the emissive energy level of the rare-earth ions. A study of the dependence of emission intensities of the Eu-containing nanoparticles on the Eu content showed that the emission intensities increased nearly linearly with increasing Eu content. In addition, no significant emission concentration quenching phenomenon was observed at the Eu content of 0,4.61 mol%. The hybrid material systems can be expected to have potential applications in light conversion materials. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source] Organic,inorganic hybrid mesoporous silicas: functionalization, pore size, and morphology controlTHE CHEMICAL RECORD, Issue 1 2006Sung Soo Park Abstract Topological design of mesoporous silica materials, pore architecture, pore size, and morphology are currently major issues in areas such as catalytic conversion of bulky molecules, adsorption, host,guest chemistry, etc. In this sense, we discuss the pore size-controlled mesostructure, framework functionalization, and morphology control of organic,inorganic hybrid mesoporous silicas by which we can improve the applicability of mesoporous materials. First, we explain that the sizes of hexagonal- and cubic-type pores in organic,inorganic hybrid mesoporous silicas are well controlled from 24.3 to 98.0,Å by the direct micelle-control method using an organosilica precursor and surfactants with different alkyl chain lengths or triblock copolymers as templates and swelling agents incorporated in the formed micelles. Second, we describe that organic,inorganic hybrid mesoporous materials with various functional groups form various external morphologies such as rod, cauliflower, film, rope, spheroid, monolith, and fiber shapes. Third, we discuss that transition metals (Ti and Ru) and rare-earth ions (Eu3+ and Tb3+) are used to modify organic,inorganic hybrid mesoporous silica materials. Such hybrid mesoporous silica materials are expected to be applied as excellent catalysts for organic reactions, photocatalysis, optical devices, etc. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 32,42; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20070 [source] Multi-Frequency PARACEST Agents Based on Europium(III)-DOTA-Tetraamide Ligands,ANGEWANDTE CHEMIE, Issue 49 2009Subha Viswanathan Dr. Farbenfrohe Palette: Eine neue Klasse von multifrequenten, hoch selektiven Eu3+ -PARACEST-Reagentien wurde entwickelt. Die Komplexe können bei simultaner Verabreichung aufeinander abgestimmt werden, was die Möglichkeit der parallelen Detektion von Biomarkern bietet. PARACEST = paramagnetic chemical exchange saturation transfer. [source] A Miniaturized Linear pH Sensor Based on a Highly Photoluminescent Self-Assembled Europium(III) Metal,Organic Framework,ANGEWANDTE CHEMIE, Issue 35 2009Bogdan Ein Miniatur-pH-Sensor für den Bereich pH,5,7.5 enthält ein photolumineszierendes Metall-organisches Gerüst mit zwei unterschiedlichen Eu3+ -Zentren (Eu1 und Eu2; siehe Bild), das durch Wasserstoffbrücken und ,-,-Wechselwirkungen zusammengehalten wird. Das Material hat die Vorteile einer sehr hohen Quantenausbeute und eines ausgewogenen Wechselspiels zwischen Absorption, Energietransfer und Emission. [source] | ||||||||||||||||