Emission Spectra Of Eu3 Research Articles

Influence of sintering conditions on the microstructure and optical properties of Eu: CaF2 transparent ceramic

Nanopowders of the 5 at.% Eu doped CaF2 have been synthesized by co-precipitated method. X-ray diffraction (XRD) indicated that the samples corresponds to the cubic CaF2 phase and scanning electron microscopy (SEM) showed that the morphology of nanopowders were approximately spherical. The Eu: CaF2 transparent ceramics were fabricated by hot-pressing (HP) method at different P-T conditions in a vacuum environment. The fracture surface, the relative density, average grain size and shrinkage displacements were also studied to analysis the influence of sintering conditions on Eu: CaF2 ceramic. In comparison with other samples, the proper sintering temperature and pressure was 600°C/30MPa. The transmittance of ceramic was up to 79.7% and 88.85% at the wavelength of 760nm and 2400nm. Furthermore, the emission spectra of Eu: CaF2 transparent ceramics under 393.5nm excitation was also discussed.

Hydrothermal synthesis combined with calcination of NaGd(SO4)2 nanoparticles and their luminescent properties from single doped Eu3+ and co-doped Yb3+,Er3+

The NaGd(SO4)2: Eu3+/Yb3+,Er3+ nanoparticles were successfully synthesized by a facile hydrothermal method combined with calcination. DTA-TG-DTG, FT-IR, and XRD results reveal that the precursor is composed of gadolinium hydrate with sulfate groups and can convert into pure NaGd(SO4)2 nanoparticles with a dispersed fishing net shape after calcined at 800 °C for 2 h. Upon excitation at 273 nm UV light, the emission spectra of Eu3+-doped phosphors consist of 5D0 → 7Fj (j = 1, 2, 3, 4) transitions and the target NaGd(SO4)2: Eu3+ shows a highest red luminescent intensity than NaGd(SO4)2·H2O: Eu3+ and Gd2O3: Eu3+ phosphors, corresponding to the 5D0 → 7F2 transition of Eu3+. The calculated lifetime of NaGd(SO4)2 is determined to be 2.345 ms. The up-conversion luminescence (UCL) mechanism of Yb3+ and Er3+ co-doped NaGd(SO4)2 and Gd2O3 phosphors were also discussed in the typical energy level diagram for their possible UCL processes.

Structural and luminescence studies of Eu3+: TeO2[sbnd]B2O3[sbnd]AO[sbnd]AF2 (A = Pb, Ba, Zn, Cd, Sr) glasses

Eu3+ doped oxyfluoro boro-tellurite (TBXFE) with molar composition 29 TeO230B2O320AO20AF21Eu2O3 (where A = Pb, Ba, Zn, Cd, Sr) glasses were prepared and investigated by XRD, FTIR, UV–Vis–NIR, luminescence and decay measurements. XRD patterns confirm the glassy nature of the prepared glasses. The influence of metal ions on the structure of boro-tellurite glasses were investigated through FTIR spectra. The intra band (4f-4f) transitions of Eu3+ ions are discussed through UV–Vis–NIR absorption spectra. The covalent nature around the Eu3+ ions with ligands are discussed using the bonding parameter (δ) and nephelauxetic ratio (β). The fundamental absorption edge, direct, indirect band gap, Urbach energy and band tailing parameters are reported. A bright red emission at 616 nm corresponding to the 5D0 → 7F2 transition of Eu3+ ions could be observed in the title glasses. Judd-Ofelt parameters were estimated from the emission spectra of Eu3+ ions. The dependence of these parameters on the composition of the glass is discussed. Judd-Ofelt parameters were used to derive the radiative parameters such as transition probabilities (A, s−1), branching ratios (βR), radiative lifetime (τrad) and stimulated emission cross-section (σPE) for the 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) transitions. The luminescence intensity ratio (LIR) of 5D0 → 7F2/5D0 → 7F1 transitions was estimated to analyze the local site symmetry around the Eu3+ ions in the present glasses. The chromaticity coordinates and colour purity were calculated from the emission spectra and analyzed with Commission International de I'Eclairage (CIE) 1931 diagram. The experimental lifetime of 5D0 level could be fitted to a single exponential indicating the absence of energy transfer between the Eu3+ ions in the present glasses.

Structural and optical study of glasses in the TeO2-GeO2-PbF2 ternary system

New glass compositions were investigated in this specific proportion (90-x)TeO2-10GeO2-xPbF2 in order to study the influence of lead fluoride content on the thermal, structural and optical properties. Glass samples with x=5 to 30% were prepared by melt-quenching method. Thermal characterizations by DSC allowed to identify a clear decrease of the glass transition temperature as well as a very distinct crystallization behavior for higher PbF2 contents. Raman spectroscopy suggests a progressive PbF2 incorporation with conversion of TeO4 to TeO3 units related with the modifier behavior of PbF2 in the glass network. X-ray diffraction patterns of crystallized samples support these results since crystalline TeO2 was detected for lower PbF2 contents whereas lead tellurite Pb2Te3O7 was identified for the most lead fluoride concentrated sample. UV–Vis–NIR absorption spectra are in agreement with a progressive increase of the optical bandgap with lead fluoride concentration. Emission spectra of Eu3+ doped samples also pointed out a progressive structural change around Eu3+ ions with more symmetric sites. Finally, experimental lifetimes, Judd-Ofelt parameters and quantum efficiencies were obtained from these samples and exhibited a strong dependency of the lead fluoride contents, suggesting that these new fluorotellurite glasses are interesting hosts for rare earth ions.

Thermal and optical properties of oxyfluorotellurite glasses doped with europium ions

Abstract The paper shows some results related to thermal and optical properties of Eu3+ -doped (65-x)TeO2-20ZnF2-12PbO-3Nb2O5-xEu2O3 glass systems. Concentration of the Eu2O3 was different (x = 0.5, 2 and 5 mol%) so it could determine the influence of active admixture on relevant properties of oxyfluorotellurite glass. Thermal stability and crystalline phases formed by the glass matrix were examined by differential thermal analysis (DTA). The characteristic temperatures (glass transition temperature and oxide glass crystallization temperature) have been determined. Optical absorption and emission spectra of Eu3+ ions in oxyfluorotellurite glasses have been investigated at room temperature in the ultraviolet (UV), visible (VIS) and near-infrared (NIR) region. Oscillator strengths, phenomenological Judd-Ofelt intensity parameters Ω2,4,6, radiative transition probabilities, branching ratios and radiative lifetimes of luminescent levels have been also estimated. Lifetimes and the luminescence dynamics were studied as a function of the Eu2O3 concentration.

Li3Gd3Te2O12:Eu3+- an intense red phosphor for solid state lighting applications

Li3Gd3−3xEu3xTe2O12 (x=0.05−1.0) phases with garnet structure were synthesized by high temperature solid state reaction and the photoluminescence properties were investigated. The appearance of bands due to intra 4f transitions of Gd3+ in the excitation spectra recorded by monitoring the 612nm emission line of the activator indicates Gd3+→Eu3+ energy transfer in this host lattice. Under 395nm excitation, the electric dipole transition is predominant in the emission spectrum of Eu3+ and is in agreement with the C2 point group (noncentrosymmetric) of the EuO8 polyhedron. The critical concentration of the Eu3+ activator in this series was found to be 0.6 (x=0.2) above which, concentration quenching occurs. The emission intensity of the phosphor composition, Li3Gd2.4Eu0.6Te2O12 is ~4 times that of the commercial sample of Y2O3:Eu3+ phosphor.

Synthesis and characterization of Mg2SiO4:Tb3+, Eu3+ phosphors for white light generation

The effect of Eu3+ codoping on the structural, morphological, and optical properties of Mg2SiO4:Tb3+ was investigated. The phosphor powders were synthesized by changing the molar concentration of Eu3+ at a fixed Tb3+ content of 5 mol% by using a conventional solid-state reaction. The X-ray diffraction patterns revealed that the crystal structure of all the phosphors, irrespective of the Eu3+ and the Tb3+ contents, showed an orthorhombic structure, and the surface morphology exhibited pebble-like crystalline grains. The emission spectra of Eu3+ and Tb3+-codoped Mg2SiO4 phosphors under an ultraviolet excitation of 252 nm consisted of one intense red band at 619 nm and five weak bands at 448, 488, 598, 658, and 707 nm originating from the transitions of Eu3+, in addition to the several emission bands located at 492, 552, 592, and 628 nm arising from the transitions of Tb3+. As the Eu3+ content was increased, the intensity of the main green emission band at 552 nm decreased markedly and disappeared at 10 mol% Eu3+, when complete energy transfer from Tb3+ to Eu3+ was observed. The results suggest that the emission wavelength and the luminescent intensity of the phosphors can be tuned by modulating the Eu3+ and the Tb3+ contents incorporated into the host matrix.

RETRACTED: Estimation of spectroscopic parameters and colour purity of the red-light-emitting YBa3B9O18 phosphor: Judd–Ofelt approach

Herein, Eu3+ doped YBa3B9O18 (YBB) phosphors have been synthesized via the solid state reaction method. The formation of YBB structure is confirmed via X-ray diffraction (XRD) studies and Rietveld refinement. The photoluminescence (PL) emission measurements upon excitation by ultraviolet and visible light show the characteristics emission of Eu3+ ion due to the 5D0→7FJ transitions. The occurrence of charge transfer band in the excitation spectra has been explained in details. The PL intensity is seen to be increased with the increase of Eu3+ concentration up to 2mol% and then decreased because of the concentration quenching. The critical distance for the quenching mechanism is calculated to be 11.83Å suggesting dipole-dipole interactions between Eu3+ ions. Different spectroscopic parameters are calculated from the emission spectra of Eu3+ ion via Judd–Ofelt theory. The results indicate the strong covalent and asymmetric nature of Eu3+ in YBB host. The as estimated values of transition probabilities indicate the efficiency of 5D0→7F2 transition and support the enhancement of the red colour emission. The red colour purity is increased with the increase in Eu3+ concentration and obtained to be 91% for the 2mol% Eu3+ doped sample. This has been explained on the basis of electron phonon coupling and multipolar interaction. The purity of the red emission has been checked and the obtained results indicate the suitability of Eu3+ doped YBB as a promising candidate for the lighting and display applications.

Resonant and non-resonant energy transfer from Ce3+ →X (X=Tb3+ , Eu3+ or Dy3+ ) in NaMgSO4 F material.

An inorganic NaMgSO4 F fluoride material was prepared by the wet chemical method and studied for its photoluminescence (PL) and resonant-non-resonant energy transfer (RET and NORET) capabilities between Ce3+ →Tb3+ , Ce3+ →Eu3+ and Ce3+ →Dy3+ rare earth ions. The Tb3+ emission for Ce3+ →Tb3+ transfers under ultraviolet (UV) wavelengths peaked at 491, 547, and 586nm, for excitation at 308nm due to 5 D4 →7 FJ (J=4, 5, 6) transitions. Eu emission spectra were observed at 440nm (Eu2+ ), 593nm and 616nm (Eu3+ ) recorded for different concentrations of materials, whereas Dy3+ emission from Ce3+ →Dy3+ transfer under UV wavelengths peaked at 485nm and 577nm due to 4 F9/2 →6 H15/2 and 6 H13/2 transitions. The purpose of the present study is to understand the RET and NORET effects of Tb3+ , Eu3+ and Dy3+ co-doping in a NaMgSO4 F:Ce3+ luminescent material, which could be used as a green-emitting material for lamp phosphors.

Consequences of ET and MMCT on Luminescence of Ce(3+)-, Eu(3+)-, and Tb(3+)-doped LiYSiO4.

Ce(3+), Eu(3+), and Tb(3+) singly doped, Ce(3+)-Tb(3+), Tb(3+)-Eu(3+), and Ce(3+)-Eu(3+) doubly doped, as well as Ce(3+)-Tb(3+)-Eu(3+) triply doped LiYSiO4 phosphors were prepared by a high-temperature solid-state reaction technique. Rietveld refinement was performed to determine the structure of host compound. The cross-relaxation (CR) of Tb(3+) is quantitatively analyzed with the Inokuti-Hirayama model of energy transfer (ET), and the site occupancy is confirmed by emission spectra of Eu(3+). ET and metal-metal charge transfer (MMCT) are systematically investigated in Ce(3+)-Tb(3+), Tb(3+)-Eu(3+), and Ce(3+)-Eu(3+) doubly doped systems. The combined effects of ET and MMCT on luminescence and emission color of Ce(3+)-Tb(3+)-Eu(3+) triply doped samples are discussed in detail, showing that the photoluminescence emission is tunable in a large color gamut.

Investigated on Photoluminescence Properties of Sm<sup>3+</sup> Ions in Gadolinium Calcium Phosphate Glasses

Sm3+-doped gadolinium calcium phosphate glasses of the composition (70-x)P2O5 : 10CaO : 20Gd2O3 : xSm2O3 (PCGSm), where x = 0.05, 0.10, 0.50, 1.00, 1.50, 2.00, 2.50 and 3.00 mol% have been prepared by melt-quenching technique and investigated their photoluminescence properties. The emission spectra of Eu3+-doped glasses recorded in wavelength range 500-750 nm with 402 nm excitation. All the spectra exhibited 4 emission bands corresponding to the 4G5/2→6H5/2, 4G5/2→6H7/2, 4G5/2→6H9/2 and 4G5/2→6H11/2 transition, respectively. The peak intensities increase with the increase of concentration from 0.05 to 0.5 mol% and beyond that the quenching in the emission peak intensities have been observed.

Synthesis and Optical Properties of Novel Red-Emitting PbNb2O6: Eu(3+) Phosphors.

Undoped and PbNb2O6:Eu(3+) (1.0≤x≤6.0mol%) phosphors were synthesized at 1100°C for 3.5h by the conventional solid state reaction method. Synthesized PbNb2O6:Eu(3+) phosphors were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and Photoluminescence (PL) analyses. The PL spectra showed series of excitation peaks between 350 and 430nm due to the 4f-4f transitions of Eu(3+). For 395.0nm excitation, emission spectra of Eu(3+) doped samples were observed at 591nm (orange) and 614nm (red) due to the (5)D0→(7)F1 transitions and (5)D0→(7)F2 transitions, respectively. PL analysis results also showed that the emission intensity increased by increasing Eu(3+) ion content. No concentration quenching effect was observed. The CIE chromaticity color coordinates (x,y) of the PbNb2O6:Eu(3+) phosphors were found to be in the red region of the chromaticity diagram.

Influence of MO/MF2 modifiers (M = Ca, Sr, Ba) on spectroscopic properties of Eu3+ ions in germanate and borate glasses

Series of Eu3+-doped lead-free germanate and borate glasses were synthesized. The MO glass modifiers (M = Ca, Sr or Ba) were partially or totally substituted by MF2 in chemical composition. In contrast to samples modified by CaO/CaF2 or SrO/SrF2, the germanate glass samples containing BaO and/or BaF2 are fully amorphous, while the lead-free borate glasses are fully amorphous, independently from glass modifiers. Effect of glass modifiers on spectroscopic properties of Eu3+ were systematically investigated.For that reason, excitation and emission spectra of Eu3+ ions in examined systems were registered. Based on the emission spectra, ratio of integrated luminescence intensity of the 5D0 → 7F2 transition to that of the 5D0 → 7F1 transition (R factor) was calculated. Moreover, the luminescence decay curves were collected and the luminescence lifetimes of the 5D0 excited state of Eu3+ ions were determined in function of MF2 concentration.

Comparison on effect of EDTA and citrate mediated on luminescence property of Eu3+ doped YPO4 nanoparticles

Summary Nanoparticles of Eu 3+ doped YPO 4 have been prepared by co-precipitation method. The structure, morphology, composition and photoluminescence were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), IR Spectroscopy, and Scanning electron microscopy (SEM) and Photoluminescence spectroscopy (PL). In this method EG was used as a solvent, tri sodium citrate dihydrate and EDTA were used as a complexing agent. X-ray diffraction results show that the nanoparticles are crystalline in tetragonal structure and the presence of two phases, tetragonal and hexagonal phase for citrate mediated and EDTA complexed nanoparticles. The SEM image shows spherical nanoparticles which are non-agglomerated and highly dispersible in water. With the addition of citrate and EDTA, there is a slightly shift towards the lower wavelength in emission peaks. A broad peak at 250 nm is observed due to the Eu O charge transfer band in the excitation spectra. Emission intensity decreases with complexing agent because of decrease of particle size as well as decrease of number of Eu 3+ activators per unit volume. The emission spectrum of Eu 3+ doped YPO 4 nanoparticles clearly shows f–f transitions of Eu 3+ .

Formation and photoluminescence of Eu3+ doped zirconia coatings formed by plasma electrolytic oxidation

Eu3+ doped ZrO2 coatings were formed by plasma electrolytic oxidation of zirconium in electrolyte containing Eu2O3 powder. The content of Eu in coatings increases with the time of PEO process. The coatings are crystallized and mostly composed of monoclinic ZrO2 phase. Photoluminescence (PL) emission spectra of Eu3+ doped ZrO2 coatings feature two distinct regions. The first region is related to ZrO2 PL band with a maximum positioned at about 490 nm, while the second region in the orange–red part of the spectrum shows sharp emission bands which are related to f–f transitions of Eu3+ from excited level 5D0 to lower levels 7FJ (J=0, 1, 2, 3, and 4). Excitation PL spectra of Eu3+ doped ZrO2 coatings monitored at 480nm feature a broad PL band with spectral maximum at about 280nm. In contrast, the excitation PL spectra monitored at the wavelength of the most intense peak in emission PL spectra can be divided into two regions: (a) the broad band region from 240nm to 350nm with a maximum at about 250nm, which is associated with the electron transfer transition from 2p orbital of O2− ions to 4f orbital of Eu3+ ions and (b) the region in the range from 350nm to 550nm with the series of sharp peaks, which correspond to direct excitation of the Eu3+ ground state 7F0 into higher levels of the 4f-manifold.

Evolution of Structure and Photoluminescence by Cation Cosubstitution in Eu2+-Doped (Ca1–xLix)(Al1–xSi1+x)N3 Solid Solutions

Red-emitting nitride phosphors excited with blue light have great potential for the fabrication of warm white light-emitting diodes (WLEDs). Chemical composition and structural modification are generally adopted to optimize the photoluminescence behaviors of the targeted phosphors. Herein, on the basis of the famous CaAlSiN3 phosphors, Eu(2+)-doped (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 solid solutions via the cations' cosubstitution of (CaAl)(5+) pair by (LiSi)(5+) pair are successfully synthesized by a solid state reaction, and the lattice parameters show a linear decrease with chemical compositions suggesting the formation of the isostructural phase relationship. Four types of coordinated structure models, corresponding to different coordination environments of Eu(2+), are proposed over the course of structural evolution, which induces different structural rigidity and stability, and then they are responsible for three-stage changes of emission spectra of Eu(2+) in (Ca(1-x)Li(x))(Al(1-x)Si(1+x))N3 solid solution.

Properties and Investigation on Effect of Eu<sup>3+</sup> Ions in Lithium Barium Borate Glasses

Eu3+-doped lithium barium borate glasses of the composition 50Li2O : 20BaO : (30-x)B2O3 : xEu2O3, where x = 0.00, 0.10, 0.30, 0.50, and 1.00 mol%. The glasses were fabricated by normal melt quenching technique at 1,000°C and their properties were investigated. The emission spectra of Eu3+-doped glasses were recorded in wavelength range of 550-770 nm with 394 nm excitation. All the spectra exhibited 5 emission bands corresponding to the 5D0→7F0, 5D0→7F1, 5D0→7F2, 5D0→7F3 and 5D0→7F4 transition, respectively. The peak intensities increase with the increase of concentration from 0.10 to 1.0 mol%

Preparation and Properties of La<sub>2</sub>O<sub>3</sub>-CaO-P<sub>2</sub>O<sub>5</sub> Glasses Doped with Eu<sup>3+</sup> Ions

Lanthanum calcium phosphate glasses doped with Eu3+ ions in compositions 20La2O3:10CaO:(70-x)P2O5:xEu2O3 (where x = 0.05, 0.10, 0.50 and 1.50 mol%) were prepared by melt-quenching technique. The density and molar volume measurements were carried out at room temperature. The absorption spectra were investigated in the UV-Vis-NIR region from 200 to 2500 nm. The emission spectra of Eu3+-doped glasses centered at 590 nm (5D0→7F1), 612 nm (5D0→7F2), 652 nm (5D0→7F3) and 699 nm (5D0→7F4) have been observed with 393 nm excitation wavelength.

Energy transfer process in highly photoluminescent binuclear hydrocinnamate of europium, terbium and gadolinium containing 1,10-phenanthroline as ancillary ligand

New binuclear lanthanide (III) complexes of general formula [Ln2(hcin)6(phen)2] (where Ln=Eu 1; Gd 2; Tb 3; hcin=hydrocinnamate anion; phen=1,10-phenanthroline) were synthesized and fully characterized by elemental analysis, vibrational spectroscopy (infrared and Raman), thermal analysis (TGA/DTA), CP/MAS 13C NMR and powder X-ray diffraction. The crystal description based on powder X-ray diffraction data reveals that all compounds are isostructural and that each lanthanide ion is nine coordinated by oxygen and nitrogen atoms to form distorted tricapped trigonal-prismatic coordination polyhedron. The photoluminescence behavior was studied based on the excitation and emission spectra and luminescence decay curves. The emission spectra of Eu(III) and Tb(III) complexes are composed of intense and typical red and green emissions, respectively. Phosphorescence data of Gd(III) complex showed that the triplet states (T1) of ligands have higher energy than the main emitting states of Eu(III) and Tb(III) indicating the possibility of intramolecular energy transfer for these metal ions. To elucidate the energy transfer process in the Eu(III) complex, spectroscopic properties as Ωλ intensity parameters (λ=2 and 4), radiative (Arad) and nonradiative (Anrad) decay rates and quantum efficiency (η) of [Eu2(hcin)6(phen)2] were determined. Such spectroscopic properties were compared with [Eu2(hcin)6(bpy)2] complex properties recently reported. The high emission quantum efficiency (η=72%) for Eu(III) complex 1 showed that it is a potential candidate as emitter in photonic systems.

Effects of Eu3+ concentration and heat-treatment on photoluminescence properties of Zn1−x Eu x Al2O4 phosphors

A series of Eu3+-doped ZnAl2O4 phosphors were synthesized by sol–gel method. The photoluminescence properties and morphology were systematically investigated. X-ray diffraction patterns indicated that pure spinel phase of high crystallinity can be obtained when the concentration of Eu3+ was less than 7 at.% with secondary calcination temperature in the range of 600–900 °C. The results of PL indicated that the emission spectra of Eu3+-doped ZnAl2O4 phosphors consist of five peaks located at 580, 593, 618, 653, 700 nm, which correspond to 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, 5D0 → 7F5 transitions, respectively. The luminescence intensity was significantly influenced by doping concentration and calcination temperature. The best Eu3+ concentration is 5 at.% and the best secondary calcination temperature is 800 °C. The phosphors can be efficiently excited under the excitation of 395 nm, indicating that Zn0.95Eu0.05Al2O4 can act as a potential near-UV LED-based red-emitting component for possible applications in solid-state lighting and display.