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Enhanced luminescence of Tb(3+)/Eu(3+) doped tellurium oxide glass containing silver nanostructures

KASSAB, Luciana R. P.; ALMEIDA, Ricardo de; SILVA, Davinson M. da; ASSUMPCAO, Thiago A. A. de; ARAUJO, Cid B. de
Fonte: AMER INST PHYSICS Publicador: AMER INST PHYSICS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.04%
We report on energy transfer studies in terbium (Tb(3+))-europium (Eu(3+)) doped TeO(2)-ZnO-Na(2)O-PbO glass containing silver nanostructures. The samples excitation was made using ultraviolet radiation at 355 nm. Luminescence spectra were recorded from approximate to 480 to approximate to 700 nm. Enhanced Eu(3+) luminescence at approximate to 590 nm (transition (5)D(0)-(7)F(1)) and approximate to 614 nm (transition (5)D(0)-(7)F(2)) are observed. The large luminescence enhancement was obtained due to the simultaneous contribution of the Tb(3+)-Eu(3+) energy transfer and the contribution of the intensified local field on the Eu(3+) ions located near silver nanostructures.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); Fundacao de Amparo a Ciencia e Tecnologia de Pernambuco (FACEPE)

Photoluminescence enhancement by gold nanoparticles in Eu(3+) doped GeO(2)-Bi(2)O(3) glasses

KASSAB, Luciana R. P.; SILVA, Diego S. da; ALMEIDA, Ricardo de; ARAUJO, Cid B. de
Fonte: AMER INST PHYSICS Publicador: AMER INST PHYSICS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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We report large photoluminescence (PL) enhancement in Eu(3+)-doped GeO(2)-Bi(2)O(3) glasses containing gold nanoparticles (NPs). Growth of approximate to 1000% in the PL intensity corresponding to the Eu(3+) transition (5)D(0)->(7)F(2), at 614 nm, was observed in comparison with a reference sample that does not contain gold NPs. Other PL bands from 580 to 700 nm are also enhanced. The enhancement of the PL intensity is attributed to the increased local field in the Eu(3+) locations due to the presence of the NPs and the energy transfer from the excited NPs to the Eu(3+) ions.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE)

Polymer matrix sensitizing effect on photoluminescence properties of Eu(3+)-beta-diketonate complex doped into poly-beta-hydroxybutyrate (PHB) in film form

KAI, Jiang; PARRA, Duclerc Fernandes; BRITO, Hermi Felinto
Fonte: ROYAL SOC CHEMISTRY Publicador: ROYAL SOC CHEMISTRY
Tipo: Artigo de Revista Científica
Português
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46.06%
In this work is reported the sensitization effect by polymer matrices on the photoluminescence properties of diaquatris(thenoyltrifluoroacetonate)europium(III), [Eu(tta)(3)(H(2)O)(2)], doped into poly-beta-hydroxybutyrate (PHB) with doping percentage at 1, 3, 5, 7 and 10% (mass) in film form. TGA results indicated that the Eu(3+) complex precursor was immobilized in the polymer matrix by the interaction between the Eu(3+) complex and the oxygen atoms of the PHB polymer when the rare earth complex was incorporated in the polymeric host. The thermal behaviour of these luminescent systems is similar to that of the undoped polymer, however, the T(onset) temperature of decomposition decreases with increase of the complex doping concentration. The emission spectra of the Eu(3+) complex doped PHB films recorded at 298 K exhibited the five characteristic bands arising from the (5)D(0) -> (7)F(J) intraconfigurational transitions (J = 0-4). The fact that the quantum efficiencies eta of the doped film increased significantly revealed that the polymer matrix acts as an efficient co-sensitizer for Eu(3+) luminescent centres and therefore enhances the quantum efficiency of the emitter (5)D(0) level. The luminescence intensity decreases, however...

Synthesis and Study of the Photophysical Properties of a New Eu(3+) Complex with 3-Hydroxypicolinamide

ROSA, Ieda Lucia Viana; SOUSA FILHO, Paulo Cesar de; NERI, Claudio Roberto; SERRA, Osvaldo Antonio; FIGUEIREDO, Alberthmeiry Teixeira de; VARELA, Jose Arana; LONGO, Elson
Fonte: SPRINGER/PLENUM PUBLISHERS Publicador: SPRINGER/PLENUM PUBLISHERS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
56.01%
This work reports on the synthesis and characterization of a new complex of Eu(3+) with the 3-hydroxypicolinamide ligand (Hhpa). Here we present an approach for obtaining bis[2-carbamoyl(kappa O)pyridin-3-olato(kappa O`)] lanthanide complexes, which were characterized through elemental analysis, thermal analysis, infrared and photoluminescence spectroscopies (emission, excitation, luminescence lifetimes, quantum efficiencies, Judd-Ofelt parameters and quantum yields). Although hpa can act as a bidentate ligand in different conformations, the results attest for the occurrence of a unique coordination site of low symmetry for the Eu(3+) ions, in which two anionic hpa ligands coordinate the cations through an O/O chelating system. The phosphorescence of the synthesized gadolinium complex provides the energy of the triplet state, which is determined to be at 20,830 cm(-1) over the ground state. This makes the Hhpa ligand very adequate for sensitizing the Eu(3+) luminescence, which leads to a very efficient antenna effect and opens a wide range of applications for the complex in light emitting organic-inorganic devices.; CAPES; CNPq/INCTMN/inct-INAMI; FAPESP

Visible and near-infrared luminescent Eu(3+) or Er(3+) doped laponite-derived xerogels and thick films: Structural and spectroscopic properties

TRONTO, Jairo; RIBEIRO, Sidney Jose Lima; VALIM, Joao Barros; GONCALVES, Rogeria Rocha
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
Português
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46.08%
Laponite-derived materials represent promising materials for optical applications. In this work, Eu(3+)- or Er(3+)-doped laponite xerogels and films were prepared from colloidal dispersion. Homogeneous, crack-free and transparent single layers were deposited on soda-lime substrates with a thickness of 10 mu m. Structural and spectroscopic properties were analyzed by thermal analyses, X-ray diffractometry, transmission electron microscopy, infrared spectroscopy, and luminescence spectroscopy. The addition of a rare earth ion to the laponite does not promote any changes in thermal stability or phase transition. Laponite clay was identified after annealing up to 500 degrees C, with a decrease in basal spacing when the annealing temperature is changed from 100 degrees C to 500 degrees C. Enstatite polymorphs and amorphous silicate phases were observed after heat treatment at 700 degrees C and 900 degrees C. Stationary and time-dependent luminescence spectra in the visible region for Eu(3+), and (5)D(0) lifetime are discussed in terms of thermal treatment and structural evolution. In the layered host, the Eu(3+) ions are distributed in many different local environments. However, Eu(3+) ions were found to occupy at least two symmetry sites...

Luminescent Langmuir-Blodgett film of a new amphiphilic Eu(3+) beta-diketonate

GOMES, Luciano F.; OLIVEIRA, Kleber T. de; NERI, Claudio R.; SOUSA FILHO, Paulo C. de; BIANCO, Marcos J. Dal; RAMOS, Ana P.; ZANIQUELLI, Maria E. D.; SERRA, Osvaldo A.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.04%
This work reports on the synthesis and characterization of the ligand 3-hexadecylpentane-2,4-drone (Hhdacac) and its Eu(3+) complexes Eu(hdacac)(6) center dot 2H(2)O, Eu(hdacac)(6) center dot phen and Eu(hdacac)(6) center dot tta, where phen and tta denote 1,10-phenanthroline and thenoyltrifluoroacetone, respectively. These new compounds present long carbon chains and their expected miscibility into non-polar ambients is confirmed by the emission spectra of Eu(hdacac)6 center dot tta in hexane. Moreover, the amphiphilic properties of Eu(hdacac)6 complexes allow the obtainment of thin luminescent films by the Langmuir-Blodgett technique. In both cases (solids and films), the typical antenna effect of beta-diketonates is observed. The alluring characteristics of these compounds raise great interest in many fields of Materials Science, like photo- and electro-luminescent materials (mainly thin ""organic"" films), metal catalysts or probes in non-polar solutions, and Langmuir-Blodgett films of several compositions. For the characterization of these products, nuclear magnetic resonance spectroscopy ((1)H NMR), thermogravimetric analysis, elementary analyses (C, H), scanning electron microscopy (energy dispersive X-ray spectroscopy), absorption (UV-vis/FT-IR) and photoluminescence spectroscopies were used. (c) 2008 Elsevier B.V. All rights reserved.

Photoluminescence behavior of Eu(3+) ion doped into gamma- and alpha-alumina systems prepared by combustion, ceramic and Pechini methods

Monteiro, Maria Adriana Fraiha; Brito, Hermi Felinto de; Felinto, Maria Claudia França da Cunha; Brito, Giancarlo Esposito de Souza; Teotonio, Ercules Epaminondas de Sousa; Vichi, Flavio Maron; Stefani, Roberval
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.14%
Al(2)O(3):Eu(3+)(1%) samples were prepared by combustion, ceramic, and Pechini methods annealed from 400 to 1400 degrees C. XRD patterns indicate that samples heated up to 1000 degrees C present disordered character of activated alumina (gamma-Al(2)O(3)). However, alpha-Al(2)O(3) phase showed high crystallinity and thermostability at 1200-1400 degrees C. The sample characterizations were also carried out by means of infrared spectroscopy (IR), scanning electron microscopy (SEM) and specific surface areas analysis (BET method). Excitation spectra of Al(2)O(3):Eu(3+) samples present broaden bands attributed to defects of Al(2)O(3) matrices and to LMCT state of O -> Eu(3+), however, the narrow bands are assigned to (7)F(0) -> (5)D(J),(5)H(J) and (5)L(J) transitions of Eu(3+) ion. Emission spectra of samples calcined up to 1000 degrees C show broaden bands for (5)D(0) -> (7)F(J) transitions of Eu(3+) ion suggesting that the rare earth ion is in different symmetry sites showed by inhomogeneous line broadening of bands, confirming the predominance of the gamma-alumina phase. For all samples heated from 1200 to 1400 degrees C the spectra exhibit narrow (5)D(0) -> (7)F(J) transitions of Eu(3+) ion indicating the conversion of gamma to alpha-Al(2)O(3) phases...

Synthesis, Characterization, Luminescence and Defect Centres in CaYAl(3)O(7):Eu(3+) Red Phosphor

SINGH, Vijay; Watanabe, Shigueo; Rao, Tumkur Krishnaswamy Gundu; KWAK, Ho-Young
Fonte: SPRINGER/PLENUM PUBLISHERS Publicador: SPRINGER/PLENUM PUBLISHERS
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.05%
CaYAl(3)O(7):Eu(3+) phosphor was prepared at furnace temperatures as low as 550A degrees C by a solution combustion method. The formation of crystalline CaYAl(3)O(7):Eu(3+) was confirmed by powder X-Ray diffraction pattern. The prepared phosphor was characterized by SEM, FT-IR and photoluminescence techniques. Photoluminescence measurements indicated that emission spectrum is dominated by the red peak located at 618 nm due to the (5)D(0)-(7)F(2) electric dipole transition of Eu(3+) ions. Electron Spin Resonance (ESR) studies were carried out to identify the centres responsible for the thermoluminescence (TL) peaks. Room temperature ESR spectrum of irradiated phosphor appears to be a superposition of two distinct centres. One of the centres (centre I) with principal g-value 2.0126 is identified as an O(-) ion while centre II with an isotropic g-factor 2.0060 is assigned to an F(+) centre (singly ionized oxygen vacancy). An additional defect centre is observed during thermal annealing experiments and this centre (assigned to F(+) centre) seems to originate from an F centre (oxygen vacancy with two electrons). The F(+) centre appears to correlate with the observed high temperature TL peak in CaYAl(3)O(7):Eu(3+) phosphor.; FAPESP, Brazil; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization, photoluminescence, thermally stimulated luminescence and electron spin resonance studies of Eu(3+) doped LaAlO(3) phosphor

SINGH, Vijay; Watanabe, Shigueo; RAO, T. K. Gundu; Chubaci, Jose Fernando Diniz; KWAK, Ho-Young
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.05%
Europium-doped lanthanum aluminate (LaAlO(3)) powder was prepared by using a combustion method. The crystallization, surface morphology, specific surface area and luminescence properties of the samples have been investigated. Photoluminescence studies of Eu doped LaAlO(3) showed orange-reddish emission due to Eu(3+) ions. LaAlO(3):Eu(3+) exhibits one thermally stimulated luminescence (TSL) peak around 400 degrees C. Room temperature electron spin resonance spectrum of irradiated phosphor appears to be a superposition of two centres. One of them (centre I) with principal g-value 2.017 is identified as an O(-) centre while centre II with an isotropic g-value 2.011 is assigned to an F(+) centre (singly ionized oxygen vacancy). An additional defect centre observed during thermal annealing around 300 degrees C grows with the annealing temperature. This centre (assigned to F(+) centre) originates from an F-centre (oxygen vacancy with two electrons) and the F-centre along with the associated F(+) centre appear to correlate with the observed TSL peak in LaAlO(3):Eu(3+) phosphor. The activation energy for this peak has been determined to be 1.54 eV from TSL data. (C) 2010 Elsevier Masson SAS. All rights reserved.

Study on the observation of Eu(2+) and Eu(3+) valence states in low silica calcium aluminosilicate glasses

SAMPAIO, J. A.; FILADELPHO, M. C.; ANDRADE, A. A.; ROHLING, J. H.; MEDINA, A. N.; BENTO, A. C.; SILVA, L. M. da; GANDRA, F. C. G.; NUNES, L. A. O.; BAESSO, M. L.
Fonte: IOP PUBLISHING LTD Publicador: IOP PUBLISHING LTD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.1%
The optical, magnetic and structural properties of Eu doped low silica calcium aluminosilicate glasses were investigated. The optical absorption coefficient presented two bands at 39 246 and 29 416 cm(-1), which were assigned respectively to the 4f(7) ((8)S(7/2)) -> 4f(6) (4F(J)) 5d (T(2g)), and 4f(7) ((8)S(7/2)) -> 4f(6) (4F(J)) 5d (E(g)) transitions of Eu(2+). The fluorescence measured at 300 K on a sample doped with 0.5 wt% of Eu(2)O(3) exhibited a broad band centered at 17 350 cm(-1), which is attributed to the 4f(6)5d -> 4f(7) transition of Eu(2+), whereas the additional peaks are due to the (5)D(0) -> (7)F(J) (J = 1, 2, 4) transitions of Eu(3+). From magnetization and XANES data it was possible to evaluate the fractions of Eu(2+) and Eu(3+) for the sample doped with 0.5 and 5.0 wt% of Eu(2)O(3), the values of which were approximately 30 and 70%, respectively.; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CAPES; FAPERJ; Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ); FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Novel electroluminescent devices containing Eu(3+)-(2-acyl-1,3-indandionate) complexes with TPPO ligand

TEOTONIO, E. E. S.; BRITO, H. F.; CREMONA, M.; QUIRINO, W. G.; LEGNANI, C.; FELINTO, M. C. F. C.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
56.12%
Fabrication and electroluminescent properties of devices containing europium complexes of general formula [Eu(ACIND)(3)(TPPO)(2)], where ACIND, 2-acyl-1,3-indandionate ligands: and TPPO, triphenylphosphine oxide. as emitter layers are discussed. The double-layer devices based on these complexes present the following configurations: device 1: ITO/TPD/[Eu(AlND)(3)(TPPO)(2)]/Al: device 2: ITO/TPD/[Eu(ISOV-IND)(3)(TPPO)(2)]/Al and device 3: ITO/TPD/[Eu(BIND)(3)(TPPO)(2)]/Al, where AlND, 2-acetyl-1,3-indandionate; ISOVIND, 2-isovaleryl-1,3-indandionate; and BIND, 2-benzoyl-1,3-indandionate, respectively. These devices exhibited photo and electroluminescent emissions. An important characteristic presented by devices is that their electroluminescent (EL) spectra, in the region of (5)D(0) -> (7)F(J) (J = 0, 1, 2, 3 and 4) transitions of Eu(3+) ion, show profiles that are different from photoluminescent (PL) ones. In addition to narrow bands arising from intraconfigurational-4f(6) transitions, devices 1 and 2 also exhibited a broad band with maximum at around 500 nm which is assigned to electrophosphorescence from the indandionate ligands. On the other hand, EL spectra of device 3 present only narrow bands from (5)D(0) -> (7)F(J) transitions. [Eu(ACIND)(3)(TPPO)(2)] complexes are promising candidates to prepare efficient organic light-emitting devices (OLEDs) when compared with those containing Eu(3+)-complexes of aliphatic beta-diketonate anions. (C) 2009 Elsevier B.V. All rights reserved.; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FACEPE; FACEPE; RENAMI; RENAMI; CNPq-PRONEX; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Espectroscopia de ions Eu+3 em cristais de baixa simetria; Espectroscopy of Eu+3 ions in low simmetry cristals.

Oliveira, Antonio Cesar de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 21/02/1991 Português
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66.17%
Neste trabalho estudamos o íon Eu3+ no aluminato EuAlO3 e no garnet Ca3Ga2Ge3O12:Eu+3 através de espectroscopia óptica. Técnicas convencionais de absorção e fluorescência foram utilziadas, e elas nos permitiram um levantamento sistemático dos níveis eletrônicos 7FJ (J= 0,1,2,3,4) e 5DJ (J= 0,1,2) do Eu+3. A análise dos espectros de absorção feitos com luz polarizada confirma a ocupação dos íons Eu+3 em sítios de simetria C no EuAlO3. Com isso também confirmamos as regras de seleção esperadas. Efetuamos medidas da variação da largura de linha com a temperatura, da transição 7F1 → 5D0 em EuAlO3. Isso nos permitiu determinar a estatística de íons excitados termicamente ao sub-nível 7F1, cuja energia é próxima a kT para temperatura ambiente. Os espectros de fluorescência resolvida no tempo nos forneceram o comportamento do decaimento radiativo em função da temperatura para as transições 5D0 → 7FJ do Eu3+ tanto no sistema EuAlO3 quanto no garnet Ca3Ga2Ge3O12:Eu+3. Além das técnicas convencionais citadas acima, utilizamos também uma técnica espectroscópica não linear denominada Coherent antiStokes Raman Spectroscopy. Essa é uma técnica muito útil na determinação de níveis vibracionais ou eletrônicos na região de infravermelho. O processo de alinhamento e medidas preliminares foram feitos com o benzeno e a calcita (CaCO3). Na seqüência processamos a detecção e o estudo de um dos níveis 7F2 do Eu+3 no garnet.; In this work we studied the íon Eu3+ in aluminate EuAlO3 and in the garnet Ca3Ga2Ge3O12:Eu+3 through the optical spectroscopy. Conventional techniques of absorption and fluorescence were used and enabled us to study systematically the levels 7FJ (J= 0...

Espectroscopia de íons de Eu+3 como impureza em GdAlO3; Optical spectroscopy of Eu+3 dopped GdAlO3

Padua, Sebastiao Jose Nascimento de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/08/1988 Português
Relevância na Pesquisa
46.08%
Espectros de absorção, fluorescência e excitação do íon Eu+3 em GdAlO3 na região do visível são mostrados neste trabalho. Todos os níveis 7Fj (j= 0, 1, 2 e 4) e 5Dj (j= 0 a 2) foram medidos e quase todas as transições do íon, na região do visível, foram identificadas nos espectros. A abertura dos níveis de energia verificada está de acordo com a simetria C5 do campo cristalino. Medidas de absorção polarizada foram feitas com o intuito de verificar a natureza das transições de dipolo e para determinar as representações irredutíveis dos níveis de energia 7F0, 7F1 e 5Dj (j= 0 a 2). Linhas da impureza Er+3 (não intencional) foram identificadas no espectro de absorção e sua presença no cristal foi verificada através dos valores conhecidos dos níveis de energia do íon Er+3 em GdAlO3 [III-4]. Além disso, medidas dos níveis de energia 7F2 do íon Eu+3 através da técnica espectroscópica não linear CARS, foram tentadas. Medidas preliminares destes níveis e dos níveis vibracionais do benzeno e da calcita são mostrados no final da dissertação.; Absorption, fluorescence and excitation of the Eu+3 íon in GdAlO3 in the visible region are presented in this work. All of the 7Fj (j= 0, 1, 2 and 4) and 5Dj (j= 0 to 2) energy levels were measured and almost all of the transitions in the visible region of the ion were seen in the spectra. The splitting of energy levels verified is according to the C5 symmetry of the crystal field. Polarized absorption techniques are used to check the nature of the dipole transitions and to determine the irreducible representations of the 7F0...

Photoluminescence of Eu(3+) ion in SnO(2) obtained by sol-gel

Morais, Evandro A.; Scalvi, Luis V. A.; Tabata, Americo; De Oliveira, Jose B. B.; Ribeiro, Sidney J. L.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 345-349
Português
Relevância na Pesquisa
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Photoluminescence data of Eu-doped SnO(2) xerogels are presented, yielding information on the symmetry of Eu(3+) luminescent centers, which can be related to their location in the matrix: at lattice sites, substituting to Sn(4+), or segregated at particles surface. Influence of doping concentration and/or particle size on the photoluminescence spectra obtained by energy transfer from the matrix to Eu(3+) sites is investigated. Results show that a better efficiency in the energy transfer processes is obtained for high symmetry Eu(3+) sites and low doping levels. Emission intensity from (5)D(0) -> (7)F(1) transition increases as the temperature is raised from 10 to 240 K, under excitation at 266 nm laser line, because in this transition the multiphonon emission becomes significant only above 240 K. As an extension of this result, we predict high effectiveness for room temperature operation of Eu-based optical communication devices. X-ray diffraction data show that the impurity excess inhibits particle growth, which may influence the asymmetry ratio of luminescence spectra.

Luminescence properties of Eu(3+)- and Mg(2+)-doped LiTaO(3) obtained via the polymeric precursor method

Gasparotto, G.; Lima, S. A. M.; Davolos, M. R.; Varela, José Arana; Longo, Elson; Zaghete, M. A.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1606-1610
Português
Relevância na Pesquisa
46.01%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); This work reports the pure lithium tantalate (LiTaO(3)), europium (III)-doped LiTaO(3) and magnesium (II)-europium (III)-doped LiTaO(3) preparation by the polymeric precursor method, using four different powered samples of Eu(3+) ion concentrations 0.1 and 1 at%, observing their effect on the luminescent property of the material. Results indicated LiTaO(3) phase free of secondary phases at 650 degrees C and the photoluminescence (PL) emission spectra showed the characteristic sharp emission bands given by Eu(3+) ions when they are excited at a wavelength of 399 rim. An increase of dopants led its to a non-homogeneous broadening and showed a slightly larger one when Mg was added. A displacement of the transition (5)D(0) --> (7)F(0) to shorter wavelengths as function of Eu(3+) concentration was also noticed. (C) 2008 Elsevier B.V. All rights reserved.

Study on the observation of Eu(2+) and Eu(3+) valence states in low silica calcium aluminosilicate glasses

SAMPAIO, J. A.; FILADELPHO, M. C.; ANDRADE, A. A.; ROHLING, J. H.; MEDINA, A. N.; BENTO, A. C.; SILVA, L. M. da; GANDRA, F. C. G.; NUNES, L. A. O.; BAESSO, M. L.
Fonte: IOP PUBLISHING LTD Publicador: IOP PUBLISHING LTD
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.1%
The optical, magnetic and structural properties of Eu doped low silica calcium aluminosilicate glasses were investigated. The optical absorption coefficient presented two bands at 39 246 and 29 416 cm(-1), which were assigned respectively to the 4f(7) ((8)S(7/2)) -> 4f(6) (4F(J)) 5d (T(2g)), and 4f(7) ((8)S(7/2)) -> 4f(6) (4F(J)) 5d (E(g)) transitions of Eu(2+). The fluorescence measured at 300 K on a sample doped with 0.5 wt% of Eu(2)O(3) exhibited a broad band centered at 17 350 cm(-1), which is attributed to the 4f(6)5d -> 4f(7) transition of Eu(2+), whereas the additional peaks are due to the (5)D(0) -> (7)F(J) (J = 1, 2, 4) transitions of Eu(3+). From magnetization and XANES data it was possible to evaluate the fractions of Eu(2+) and Eu(3+) for the sample doped with 0.5 and 5.0 wt% of Eu(2)O(3), the values of which were approximately 30 and 70%, respectively.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Enhanced photoluminescence features of Eu(3+)-modified di-ureasil-zirconium oxocluster organic-inorganic hybrids

Ferreira, R. A. S.; Oliveira, D. C.; Maia, L. Q.; Vicente, C. M. S.; André, P. S.; Bermudez, V. Zea; Ribeiro, S. J. L.; Carlos, L. D.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
45.99%
In this work, a series of transparent di-ureasil hybrids containing different amounts of methacrylic acid modified zirconium tetrapropoxide (ZrMcOH) nanoclusters (5-85 mol%) and incorporating EuCl(3) and [Eu(tta)(3)(H(2)O)(2)](tta = thenoyltrifluoroacetonate) complex were prepared. These hybrids are multi-wave-length emitters due to the convolution of the host intrinsic emission (electron-hole recombinations occurring in siliceous and urea cross-linkages) Eu(3+) intra-4f(6) transitions. The ZrMcOH incorporation deviates the maximum excitation wavelength of the hybrid host intrinsic emission from the UV (365 nm) to the blue (420 nm) and enhances the absolute emission quantum yield from 6.0 +/- 0.6% to 9.0 +/- 0.9%, and contributes to an increase in the (5)D(0) lifetime values, quantum efficiency due to a decrease in the non-radiative transition probability and OH groups coordinated to the Eu(3+) ions. (C) 2010 Elsevier B.V. All rights reserved.

Modulating the Photoluminescence of Bridged Silsesquioxanes Incorporating Eu(3+)-Complexed n,n '-Diureido-2,2 '-bipyridine Isomers: Application for Luminescent Solar Concentrators

Graffion, Julien; Cattoen, Xavier; Man, Michel Wong Chi; Fernandes, Vasco R.; Andre, Paulo S.; Ferreira, Rute A. S.; Carlos, Luis D.
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.13%
Two new urea-bipyridine derived bridged organosilanes (P5 and P6) have been synthesized and their hydrolysis-condensation under nucleophilic catalysis in the presence of Eu(3+) salts led to luminescent bridged silsesquioxanes (M5-Eu and M6-Eu). An important loading of Eu(3+) (up to 11%(w)) can be obtained for the material based on the 6,6'-isomer. Indeed the photoluminescence properties of these materials, that have been investigated in depth (photoluminescence (PL), quantum yield, lifetimes), show a significantly different complexation mode of the Eu(3+) ions for M6-Eu, compared with M4-Eu (obtained from the already-reported 4,4'-isomer) and M5-Eu. Moreover, M6-Eu exhibits the highest absolute emission quantum yield value (0.18 +/- 0.02) among these three materials. The modification of the sol composition upon the addition of a malonamide derivative led to similar luminescent features but with an increased quantum yield (026 +/- 0.03). In addition, M6-Eu can be processed as thin films by spin-coating on glass substrates, leading to plates coated by a thin layer (similar to 54 nm) of Eu(3+)-containing hybrid silica exhibiting one of the highest emission quantum yields reported so far for films of Eu(3+)-containing hybrids (0.34 +/- 0.03) and an interesting potential as new luminescent solar concentrators (LSCs) with an optical conversion efficiency of similar to 4%. The ratio between the light guided to the film edges and the one emitted by the surface of the film was quantified through the mapping of the intensity of the red pixels (in the RGB color model) from a film image. This quantification enabled a more accurate estimation of the transport losses due to the scattering of the emitted light in the film (0.40)...

Modulating the photoluminescence of bridged silsesquioxanes incorporating Eu(3+)-complexed n,n '-diureido-2,2 '-bipyridine isomers: application for luminescent solar concentrators

Graffion, Julien; Cattoën, Xavier; Man, Michel Wong Chi; Fernandes, Vasco R.; André, Paulo S.; Ferreira, Rute A. S.; Carlos, Luís D.
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.13%
Two new urea-bipyridine derived bridged organosilanes (P5 and P6) have been synthesized and their hydrolysis-condensation under nucleophilic catalysis in the presence of Eu(3+) salts led to luminescent bridged silsesquioxanes (M5-Eu and M6-Eu). An important loading of Eu(3+) (up to 11%(w)) can be obtained for the material based on the 6,6'-isomer. Indeed the photoluminescence properties of these materials, that have been investigated in depth (photoluminescence (PL), quantum yield, lifetimes), show a significantly different complexation mode of the Eu(3+) ions for M6-Eu, compared with M4-Eu (obtained from the already-reported 4,4'-isomer) and M5-Eu. Moreover, M6-Eu exhibits the highest absolute emission quantum yield value (0.18 +/- 0.02) among these three materials. The modification of the sol composition upon the addition of a malonamide derivative led to similar luminescent features but with an increased quantum yield (026 +/- 0.03). In addition, M6-Eu can be processed as thin films by spin-coating on glass substrates, leading to plates coated by a thin layer (similar to 54 nm) of Eu(3+)-containing hybrid silica exhibiting one of the highest emission quantum yields reported so far for films of Eu(3+)-containing hybrids (0.34 +/- 0.03) and an interesting potential as new luminescent solar concentrators (LSCs) with an optical conversion efficiency of similar to 4%. The ratio between the light guided to the film edges and the one emitted by the surface of the film was quantified through the mapping of the intensity of the red pixels (in the RGB color model) from a film image. This quantification enabled a more accurate estimation of the transport losses due to the scattering of the emitted light in the film (0.40)...

Long range antiferromagnetic order of formally non-magnetic Eu$^{3+}$ Van Vleck ions observed in multiferroic Eu$_{1-x}$Y$_{x}$MnO$_3$

Skaugen, Arvid; Schierle, Enrico; van der Laan, Gerrit; Shukla, Dinesh K.; Walker, Helen C.; Weschke, Eugen; Strempfer, Jörg
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 19/05/2015 Português
Relevância na Pesquisa
46.02%
We report on resonant magnetic x-ray scattering and absorption spectroscopy studies of exchange-coupled antiferromagnetic ordering of Eu$^{3+}$ magnetic moments in multiferroic Eu$_{1-x}$Y$_{x}$MnO$_3$ in the absence of an external magnetic field. The observed resonant spectrum is characteristic of a magnetically ordered $^7F_1$ state that mirrors the Mn magnetic ordering, due to exchange coupling between the Eu $4f$ and Mn $3d$ spins. This is the first observation of long range magnetic order generated by exchange coupling of magnetic moments of formally non-magnetic Van Vleck ions, which is a step further towards the realization of exotic phases induced by exchange coupling in systems entirely composed of non-magnetic ions.; Comment: 5 pages, 3 figures, to be published in Physical Review B: Rapid Communications