Red Emission Of Eu3 Research Articles

Effect of Eu<sup>3+</sup> on Microstructure and Luminescence Properties of BiPO<sub>4</sub> for Near-UV LED

The phosphors Bi1-xPO4:xEu3+(x=0.01-0.08) were synthesized by the conventional solid-state reaction method. The crystal structure,morphology,photoluminescence properties and concentration quenching of these phosphors were systematically investigated. The powder X-ray diffraction revealed that the samples BiPO4:Eu3+transform from high-temperature monoclinic phase (HTMP) to low-temperature monoclinic phase (LTMP) with the increasing Eu3+content. All the samples show the characteristic red emission of Eu3+ions using the fluorescence spectrometer. The concentration quenching of Eu3+in BiPO4phosphor can be mainly attributed to multiple-multiple interaction.

Synthesis of (La<sub>0.95</sub>Eu<sub>0.05</sub>)<sub>2</sub>O<sub>3</sub> Red Phosphors with Hydroxide Nanowires as the Precursor: Template-Free Hydrothermal Processing and Photoluminescent Properties

Ln (OH)3(Ln=La0.95Eu0.05) nanowires have been successfully synthesized through hydrothermal reaction, without using any template, from mixed solutions of the component nitrates. It was shown that neither solution pH (7.5-13) nor hydrothermal temperature (120 and 150 °C) significantly influences the phase structure and particle morphology of the product. The resultant Ln (OH)3nanowires are of uniform dimension and good dispersion. A homogeneous Ln2O3solid solution was yielded by calcining the hydroxide nanowires in the air at 800 oC. Under 285 nm excitation, the Ln2O3phosphor exhibits the characteristic red emission of Eu3+at ~630 nm and show emission behaviors clearly dependent on the calcination temperature, which were investigated in detail.

Enrofloxacin Assessment by the Enhancement of the Red Emission of Eu3+ Optical Sensor

The efficiency of excited-state interaction between Eu3+ and the industrial product Enrofloxacin (EFX) has been studied in different solvent. High luminescence intensity peak at 617 nm of europium complex in acetonitrile was obtained. The photophysical properties of the red emissive Eu3+ complex have been elucidated, the europium was used as optical sensor for the assessment of Enrofloxacin in the pharmaceutical tablets and serum sample at pH 7.8 and λex=395 nm with a concentration range 1.0 ×10-7-1.0×10-5 mol L-1 of Enrofloxacin, correlation coefficient of 0.998 and detection limit of 7.5 ×10-8 mol L-1.

Effect of alkali metal ions co-doping on the structure and luminescent properties of phosphor Zn3(BO3)2:Eu3+

A series of the Zn3(BO3)2:Eu3+ without or with alkali metal ions doping at a low sintering temperature were synthesized by the solid-state reaction method. The XRD pattern shows that all samples exhibit Zn3(BO3)2 crystalline phase. The samples co-doped with alkali metal ions have better crystallinity compared with the un-compensated ones. The different charge compensation approaches have no influence on the shape and position of the emission and excitation spectra. However, the luminescent intensity of samples has been obviously enhanced with different alkali metal ions co-doping. The introduction of Li+ can increase the red emission of Eu3+ compared with the others. Thus, the volume compensation and the equilibrium of mole number can be taken into consideration by charge compensated (CC) approaches.

Colour-tuneable double-layer polymeric films doped with lanthanide β-diketonate complexes.

Double-layer polymeric films doped with lanthanide β-diketonate complexes were obtained. To eliminate the ligand exchange during the film processing the layers are composed of poly(methyl-methacrylate) (PMMA) and poly(N-vinylpyrrolidone) (PVP) polymers, which have different solubilities in organic solvents. Under selective excitation the pure green emission of Tb3+ and red emission of Eu3+ is observed with maxima at 543–544 and 612–613nm, respectively. The emission colour tuneability may be achieved not only by tailoring the films composition but also by changing the excitation wavelength. Films can be easily fabricated by sequential casting from solution, using e.g. the doctor blade technique. Moreover, due to the thermal stability of β-diketonate complexes the double-layer films can be also obtained by hot-press moulding of PMMA. The photophysical properties of the obtained films are presented and discussed. The emission intensity of Tb3+ tetrakis-complex with hexafluoroacetylacetonate ligand is significantly enhanced in PVP matrix as compared to that in PMMA.

Fabrication and photoluminescent characteristics of one-dimensional La2O2S:Eu3+ nanocrystals

One-dimensional La2O2S:Eu3+ nanowires (NWs) were fabricated with a simple hydrothermal method. The structures were characterized by X-ray diffraction and transmission electron microscopy (TEM). The photoluminescent properties including excitation and emission spectra were studied. The results indicated that in excitation spectra there existed charge transfer (CT) absorption of both O2−→Eu3+ and S2−→Eu3+, and f-f transitions absorption in NWs and corresponding sub-meter materials (SMs). The relative intensity of CT absorption of O2−→Eu3+ to S2−→Eu3+ in both samples clearly changed. The strong yellow and red emissions of Eu3+ ions in NWs were observed.

Effect of Tb3+ concentration on luminescence properties of Ce/Tb/Eu co-doped borosilicate glasses for white LEDs

Ce, Tb and Eu single and ternary doped borosilicate glasses were prepared and effect of Tb3+ concentration on luminescence properties of ternary co-doped glasses were analyzed by utilizing emission spectra, excitation spectra, the Commission International de I’Eclairage (CIE) colorimetric system and fluorescence decay curves. The results show that Tb3+ concentration significantly affects spectral intensities of ternary co-doped glasses when excited by near ultraviolet (NUV). With the increasing of Tb3+ concentration, the blue emission of Ce3+ is weakened and the red emission of Eu3+ is slightly enhanced. Both the color coordinates and correlated color temperatures (CCTs) can be adjusted by Tb3+ concentration. Besides, the energy transfers from Ce3+ to Tb3+ and from Tb3+ to Eu3+ were observed. Measured characteristic lifetimes of Tb3+ indicate that the energy transfer from Ce3+ to Tb3+ tends to predominate in whole process. The studies show that Ce/Tb/Eu ternary doped borosilicate glasses might be promising luminescence materials for NUV pumped white LEDs.

Size and shape modifications, phase transition, and enhanced luminescence of fluoride nanocrystals induced by doping

The synthesis and growth mechanism of well-defined nanostructures are still challenging. In this study, we offer a novel soft chemistry route to modify the size and shape of irregular fluoride crystals by changing the surface charge distribution of the crystal nucleus by Bi3+, Al3+, Gd3+, Yb3+, Ba2+ and Ca2+ ion doping. As a result, irregular BaF2, SrF2, GdF3, and NaGdF4 alkaline-earth and lanthanide fluorides can be converted into nanoparticles with high yield and controlled size and shape, in which the phase transition from micro-crystals to single-crystalline is also achieved. Enhanced yellow and red emissions of Eu3+-doped BaF2 induced by doping are observed. In conjunction with density functional theory calculations, it shows that the shape and size modifications originate from the surface charge redistribution of the crystal nucleus induced by inner electron charge transfer between the doping ions and lattice cations.

The concentration dependence of luminescent properties for Eu3+ doped CaWO4 micron spherical phosphors

Eu3+ doped CaWO4 micron spherical phosphors with various concentrations were prepared via a precipitation method. The structure and morphology of the samples were characterized by using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM). The excitation spectra, emission spectra and the curves of fluorescence decay of the samples were measured. The energy transfer type causing Eu3+ concentration quenching between Eu3+ ions was notarized. The critical energy transfer distance (Rc), J–O parameters and the quantum efficiencies of the 5D0 level of Eu3+ were calculated. In addition, the Eu3+ concentration dependencies of photoluminescence properties were studied systematically. The study results indicate that the red emission of Eu3+5D0–7F2 transition (616nm) in the samples can be effectively excited by 394.5nm near-UV light and 465nm blue light and the quenching concentration is high. So the CaWO4:Eu3+ red phosphors may have a potential application for white light emitting diodes.

Gd2O3:Eu Nanophosphors Prepared Via Reverse Micelle Processing: Influence of Eu3+ Content on Photoluminescence Property

Europium-doped Gadolinia (Eu-Gd2O3) phosphor nanoparticles have been synthesized by a reverse microemulsion system using cyclohexane as the oil phase, a non-ionic surfactant Igepal CO 520 and the mixed aqueous solutions of gadolinium III nitrate hexahydrate and Europium III nitrate hexahydrate as the water phase. The synthesized and calcined powders were characterized by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). The XRD results showed that the powders were cubic phase of Gd2O3 after being calcined in the air at 1,000°C. DTA and FTIR also evidenced the formation of Gd2O3 at 1,000°C. SEM revealed that the particle size decrease with increase in Eu content. EDS confirmed the presence of Gd and Eu phase in the nanopowders calcined at 1,000°C. The photoluminescence studies indicated that a strong emission peak at 610 nm is a characteristic red emission of Eu3+, and the emission intensity increases with increase in Eu content.

Rare earths (Ce, Eu, Tb) doped Y2Si2O7 phosphors for white LED

Nanocrystalline yttrium pyrosilicate Y2Si2O7 (YPS) singly, doubly or triply doped with Ce3+, Eu3+, Tb3+ was obtained by the reaction of nanostructured Y2O3:Ln3+ and colloidal SiO2 at high temperatures. X-ray diffraction analysis confirmed the formation of a single phase of α-YPS at 1200°C. Two series of YPS samples doped with Eu3+ or Eu3+/Tb3+ were obtained by applying the reducing atmosphere (75%N2+25%H2) at different temperatures. The luminescence and excitation spectra are reported. The singly Eu3+ doped YPS emit from both Eu3+ and Eu2+ ions, with the spectral position and width of the Eu2+ emission different in both series. The presence of Eu2+ in the samples was confirmed by electron paramagnetic resonance (EPR) spectra. A broadband emission of Eu2+ (380–650nm), combined with the red emission of Eu3+ is perceived by the naked eye as white light. Co-doping of YPS:Eu3+ with Tb3+ results in enhancement of the green component of the emission, and well-balanced white luminescence. The colour of this emission is tunable, and it is possible to get Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.327, 0.327), colour-rendering index (CRI) of 85, and quantum efficiency (QE) of 71%. These phosphors are efficiently excited in the wavelength range of 300–420nm, which perfectly matches a near UV-emitting InGaN chip. It was shown that for triply (Ce3+, Eu3+ and Tb3+) doped samples the three emissions from the particular activators can be generated using one excitation wavelength. The white light resulting from the superposition of the blue (Ce3+), green (Tb3+) and red (Eu3+) emissions can be obtained by varying the concentration of the active ions and the treating atmosphere, i.e. reducing or oxidising. Eu2+ was not detected in the triply doped samples, and hence line emissions mostly exhibit CRI values equal to or below 30.

Red emitting tungsto-molybdate phosphor for near-ultraviolet light-emitting diodes-based solid-state lighting

A series of novel red tungsto-molybdate phosphors, LiEu1−xSmx(WO4)0.5(MoO4)1.5 (x = 0, 0.25%, 0.50%, 0.75%, 1.00%, 2.00%, 4.00%, 6.00%, 8.00% and 10.00%), were synthesized using conventional solid state reaction methods. The experimental results indicate that the introduction of Sm3+ changes neither the crystal structure nor the shape and position of the emission spectra. However, it extends the excitation region at 400 nm and enhances the emission at 615 nm. The reason for the improvement of red emission of Eu3+ by the introduction of Sm3+ and the energy transfer mechanism from Sm3+ to Eu3+ was investigated in detail.

Study of concentration dependence of luminescent properties for Eu3+ doped CaWO4 red phosphors

Eu3+ doped CaWO4 phosphors of different concentrations are prepared by a co-precipitation method. The X-ray diffraction patterns and field emission scanning electron microscopy images are investigated. The excitation spectra, emission spectra and the curves of fluorescence decays of the samples are measured. The Judd-Ofelt (J-O) parameters, quantum efficiencies of the 5D0 level of Eu3+ and color coordinates are calculated. The dependences of relative intensity of charge transfer band, J-O parameter and quantum efficiency on doping concentration are discussed. The photoluminescence properties of Eu3+ doped CaWO4 luminescent material are studied. The results indicate that the 616 nm red emission of Eu3+5D07F2 transition can be effectively excited by 394.5 nm and 465 nm with high excitation efficiency and the concentration quenching is high. So the CaWO4: Eu red phosphor may have a potential application for white light emitting diode.

Enhanced red emission in ZnB 2O 4:Eu 3+ by charge compensation

Eu 3+ doped ZnB 2O 4 without or with different charge compensation (CC) approaches (co-doping Li +, Na +, K, decreasing the content of Zn 2+) were prepared by solid state reactions. The phosphors can strongly absorb 393 nm ultraviolet (UV) light which is coupled well with the emission of currently used InGaN-based near UV light emitting diodes (LEDs) and emit red light with a good color purity. The luminescent intensity of phosphors can be remarkably enhanced with any of CC methods. However, the shape and position of excitation and emission spectra keep unchanged. The introduction of Li + can enhance the red emission intensity of Eu 3+ by ∼4 times with the optimal effect. Red emission of Eu 3+ can also be enhanced with the other three CC approaches but the effects are not as good as Li + because the volume unbalance in Li + compensation approach is the smallest while net positive charge was offset. The results of this work suggest that volume compensation and equilibrium of mole number should also be taken into account when a CC approaches is selected.

Hydrothermal Synthesis of GdVO<sub>4</sub>:Eu <sup>3+</sup> Phosphors by Optimizing its Preparation Conditions

Eu3+ -doped GdVO4 powders have been synthesized via a novel hydrothermal method using commercially available Gd2O3, NH4VO3 and Eu2O3 as the reacting precursors. The influences of several important parameters, such as hydrothermal temperature, reaction time and pH value, of the experiment were investigated. The obtained samples were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), and photo-luminescence spectroscopy (PL). The experimental results showed that the optimal reaction condition was processed at 180°C for 12 h and adjusted pH value to 4. The morphology of products was uniform pseudo-octahedron with a little conglomeration. All the phosphors exhibit the characteristic dominant red emission of Eu3+ ion (5D0 → 7F2) at 618nm.

Efficient dual mode multicolor luminescence in a lanthanide doped hybrid nanostructure: amultifunctional material

The present work deals with inorganic–organic hybrid nanostructures capable of producingintense visible emission via upconversion (UC), downconversion (DC), and energy transfer(ET) processes which show the potential of the material as a luminescent solar collector(LSC), particularly to improve the efficiency of silicon solar cells. To achieve this,Gd2O3:Yb3 + /Er3 + phosphor (averageparticle size ∼ 35 nm) and a Eu(DBM)3Phen organic complex have been synthesized separately and then the hybrid structure has been developedusing a simple mixing procedure. Intense UC emission (in the red, green, and blue regions) due toEr3 + is observed on near infrared (976 nm) excitation which shows colortunability with input pump power. In contrast, intense red emission ofEu3 + is observed on ultaviolet (UV) (355 nm) excitation. The feasibility of energy transfer fromEr3 + ionsto Eu3 + ions has also been noted. These excellent optical properties are retained even if theparticles of the hybrid nanostructure are dispersed in liquid medium, which also makes itsuitable for security ink purposes.

A novel europium(III)–imidazol–diketonate–phenanthroline complex as a red phosphor applied in LED

Abstract A β -diketone, 4-imidazol-4,4,4-trifluorobutane-1,3-dione (HIDTFBD) and the corresponding europium(III) complex Eu(IDTFBD) 3 phen were designed and synthesized, where phen was 1,10-phenanthroline. The complex was characterized by IR, UV–visible, thermogravimetric analysis (TGA) and photoluminescence (PL) spectroscopy. Monitored at 610 nm, the Eu(III) complex exhibited a strong and wide excitation band between 320 and 420 nm due to the formation of a big π -conjugated system in the complex molecule. Under near UV-light excitation, the complex showed strong red emission of Eu 3+ ion due to the 5 D 0 – 7 F J ( J = 0–4) transitions. The fluorescence lifetime and the luminescence quantum yield were also measured. Finally, a bright red light-emitting diode was fabricated by coating the europium ternary complex onto an ~ 395 nm-emitting InGaN chip, and the LED exhibited appropriate CIE chromaticity coordinates in red area. All these results suggest that the Eu(III) complex is a promising candidate as red component for fabrication of near UV-based white light-emitting diodes.

The electronic structure and photoluminescence properties of Ca 2GeO 4:Eu 3+ in ultraviolet and vacuum ultraviolet region

Ca 2GeO 4:Eu 3+ phosphors were synthesized by the solid state method. The ultraviolet and vacuum ultraviolet excited photoluminescence properties were investigated in detail. It revealed that the emission of Ca 2GeO 4:Eu 3+ comprised two parts: the red emission of Eu 3+ and host defect emission in 330–550 nm. Ca 2GeO 4:Eu 3+ presented intense excitation intensity at 163–200 and 466 nm, which suggested the potential applications in plasma display panels and light emitting diodes. The excitation spectra were studied to identify the photoluminescence mechanisms of Ca 2GeO 4:Eu 3+. First principles calculation within the local density approximation of the density functional theory was applied to calculate the electronic structure and linear optical properties of Ca 2GeO 4.

Tunable white-light emission in single-phased K_2Y_1-xEu_xZr(PO_4)_3 phosphor

The single-phased K(2)Y(1-x)Eu(x)Zr(PO(4))(3) (x=0~1) phosphors were prepared by solid-state reaction. The greenish-blue Zr(4+)-emission due to the Zr(4+)-O(2-) charge transfer transition is observed in the K(2)YZr(PO(4))(3) (x=0) phosphor under UV excitation. Together with the Zr(4+)-emission, the red emission of Eu(3+) is progressively developed by replacement of Y(3+) to Eu(3+) over the full Eu-content (x=0~1) in K(2)Y(1-x)Eu(x)Zr(PO(4))(3). The emission color varies from greenish-blue to whitish with increasing Eu(3+)-content and the white-light emission is realized in single-phased phosphor of K(2)EuZr(PO(4))(3) (x=1) by combining the Zr(4+)-emission and the Eu(3+)-emission.

Combinatorial chemistry approach to searching phosphors for white light-emitting diodes in (Gd-Y-Bi-Eu)VO4 quaternary system

A red phosphor is desired to improve the color rendering index (Ra) of white light-emitting diodes (LEDs). Instead of developing a novel red phosphor individually, this work exploits a special yellow phosphor that contains red and green components to be matched with blue phosphor to produce white light. The desired emission color of yellow phosphor is tuned up by tailoring the green emission of Bi3+ and the red emission of Eu3+, and the luminescence efficiency and the thermal stability of luminescence are maximized by optimizing the composition of the host in the GdVO4-YVO4 system. A dynamic and virtual variation of samples emission color and intensity with Bi3+, Eu3+, Y3+ and Gd3+ concentrations and excitation wavelengths is clearly displayed in the luminescence images of the combinatorial libraries. The production of white light with high color rendering is demonstrated by preparing a practical white LED with a Ra of up to 90 from commercially available blue phosphor and optimized yellow phosphor.