Effect Of Eu Research Articles

Eu2+ concentration effects in KCa0.8Sr0.2I3:Eu2+: A novel high-performance scintillator

We report here the effect of Eu2+ concentration in KCa0.8Sr0.2I3:Eu2+ single crystal scintillators. KCa0.8Sr0.2I3:Eu2+ single crystals doped with 0.5, 1, 3, 5, and 7mol% Eu2+ were grown by the Bridgman method. The effects of varying Eu2+concentration and crystal volume on the scintillation properties, including light yield, energy resolution, nonproportionality, scintillation decay time and afterglow level, were systematically investigated. For 5mm×5mm×5mm samples, the best light yield of 86,000±4000photons/MeV was achieved with a content of 5mol% Eu2+; its energy resolution of 2.5% at 662keV was comparable to that of LaBr3:Ce3+ and SrI2:Eu2+. With larger samples of about 2.2cm3, the best performances achieved were for 3mol% Eu2+ concentration, i.e. a light yield of 76,000±4000photons/MeV and an energy resolution of 3% at 662keV. A direct correlation between nonproportionality and Eu2+ concentration was found. A continuous lengthening of scintillation decay time and x-ray induced afterglow level with increasing Eu2+ concentration was observed. The self-absorption effect was evaluated by using the Stokes shift and the temperature dependence of the photoluminescence decay (PL) of the Eu2+ centers. The sample with the highest dopant concentration had more severe temperature quenching of the Eu2+5d-4f emission than the sample with the lowest dopant concentration, which could be ascribed to the thermally activated concentration quenching.

Comparative investigation on structural and spectral properties of SnO2 composites: effect of Eu3+ doping

The present paper reports on the structural, optical and luminescence properties of Eu3+ doped SnO2/Fe2O3 and SnO2/ZnO nanocomposites synthesized by combustion method. The prepared nanocomposites were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), diffuse reflectance and photoluminescence techniques. Control of crystallization and the simultaneous phase formation of SnO2, Fe2O3 and ZnO in the prepared composites were confirmed by XRD. The FESEM images revealed the irregular aggregated morphology of the nanocomposites. The crystallite size of the nanocomposites increases with increase in Eu3+ concentration. The Eu3+ doped nanocomposites illuminated with ultraviolet light show the characteristic red luminescence corresponding to the 5D0 → 7FJ transitions of Eu3+. Different CIE and spectral parameters were calculated using spectral energy distribution function and Judd–Ofelt theory respectively. The photometric characterization indicates the suitability of SnO2/ZnO nanocomposite for red emission in different light-emitting applications.

X-ray photoemission spectroscopy investigation of CaTiO3:Eu for luminescence property: effect of Eu3+ ion

Charge compensation of on-site Eu 4f–5d transition that determines the luminescent performance was confirmed with valance band spectrum. Influence of photoelectrons from CaTiO3: Eu to the corresponding luminescent performance was discussed based on the crystal structure, doping level and the relations to their luminescent property. This paper is important to further optimize the luminescent performance for improving the efficiency and reducing the cost in light emitting diode industry.

Eu3+掺杂浓度及基质氧空位对Ca2-xEuxSnO4发光性能的影响

Eu³⁺掺杂浓度及基质氧空位对Ca_2-xEu_xSnO₄发光性能的影响

Effects of Eu3+ and Dy3+ doping or co-doping on optical and structural properties of BaB2Si2O8 phosphor for white LED applications

AbstractA series of Eu3+ and Dy3+ doped/co-doped as well as un-doped BaB2Si2O8 phosphors were synthesized via solid state reaction method. The PL result showed typical blue and green emission from Dy3+ and red emission from Eu3+. The f-f transitions involving the lanthanide ions along with dopant site occupancy were discussed thoroughly. Phonon assisted energy transfer process was observed from Eu3+ to Dy3+, which enhanced the emissions of Dy3+. Combinations of the emissions from Eu3+ and Dy3+ showed a possible white to red tuneable emission on the CIE diagram. The white warmth emissions of the phosphor were revealed to be adjustable through designing the dopant concentration and excitation wavelengths. An unusual energy transfer that originated from Eu3+ to Dy3+ was also discovered and the energy transfer mechanism was discussed. Proposed energy transfer mechanism was investigated using luminescence decay lifetime. All the phosphor exhibited efficient excitation in the UV range which matched well with the emissions from GaN-based LED chips. This presented the BaB2Si2O8 phosphor as a promising candidate for white LED applications. The effects of doping on the structural properties and the optical band gap of BaB2Si2O8 phosphor were also discussed in this study.

Effect of Eu2+ on the luminescence properties of Ba1.52−xZn0.2Li0.4SiO4:0.05Ce3+, 0.03Mn2+, xEu2+ phosphor

The Ba1.52−xZn0.2Li0.4SiO4:0.05Ce3+, 0.03Mn2+, xEu2+ phosphors are synthesized by a co-precipitation method. Luminescence properties and crystal structure of Ba1.52−xZn0.2Li0.4SiO4:0.05Ce3+, 0.03Mn2+, xEu2+ phosphors are investigated in this paper. Crystal phase, excitation and emission spectra of phosphors are analyzed by XRD and FL. Emission spectra of Ba1.52−xZn0.2Li0.4SiO4:0.05Ce3+, 0.03Mn2+, xEu2+ phosphor show three color bands with the peaks at about 400nm, 502nm and 600nm, respectively. CIE chromaticity coordinates calculated through corresponding emission spectra indicate that white light could be achieved by adjustment of the content of Ce3+, Mn2+ and Eu2+. An overlap of excitation spectra under various monitoring wavelengths demonstrates that three colors can be obtained simultaneously under near-UV excitation. Thus, Ba1.52−xZn0.2Li0.4SiO4:0.05Ce3+, 0.03Mn2+, xEu2+ can be considered as a potential candidate phosphor for near-UV white LED.

Effect of Eu3+ doping on the structural and photoluminescence properties of cubic CaCO3

Abstract CaCO3:xEu3+ (x = 0, 0.010, 0.015, 0.020, and 0.025) cubic nanoparticles were synthesized by carbonation method. The powder XRD patterns and SEM images of the CaCO3:xEu3+ nanoparticles demonstrate that both the crystalline sizes and average particle sizes of synthesized samples decreased with the increase of Eu3+ content until x = 0.020. Kubelka–Munk plots and bandgap energy estimation indicate that the doping of Eu3+ ions changed optical bandgap of CaCO3. Photoluminescence (PL) spectra show that the PL intensity of the CaCO3:xEu3+ nanoparticles was enhanced with the increase of Eu3+ content in cubic CaCO3:xEu3+, and concentration quenching occurred when Eu3+ concentration exceeded 2.0 mol%. In addition, the doped sites of Eu3+ in CaCO3 crystalline were identified by the site-selective spectroscopy and decay curves.

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.

Microwave synthesis of Y2O3:Eu3+ nanophosphors: A study on the influence of dopant concentration and calcination temperature on structural and photoluminescence properties

Red fluorescent emitting monodispersed spherical Y2O3 nanophosphors with different Eu3+ doping concentrations (0–13mol%) are synthesized by a novel microwave assisted urea precipitation, which is recognized as a green, fast and reproducible synthesis method. The effect of Eu3+ doping and calcination temperature on the structural characteristics and luminescence properties of particles is investigated in detail. The as prepared powders have (Y,Eu)(OH)(CO3) structure which converts to Y2O3:Eu3+ from 500°C and become crystalline at higher temperatures. The crystallite size of nanophosphors increased from 15nm to 25nm as the calcination temperature increased from 700°C to 1050°C. The efficient incorporation of Eu3+ ions in cubic Y2O3 host matrix is confirmed by the calculated X-ray Powder diffraction (XRPD) structural parameters. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs show that the as obtained and calcined particles are spherical, monodispersed and non-agglomerated. The overall size of particles increases from 61±8nm to 86±9nm by increasing Eu3+ concentration from 0mol% to 13mol%. High resolution TEM revealed polycrystalline nature of calcined particles. The particles exhibit a strong red emission under ultraviolet (UV) excitation. The photoluminescence (PL) intensity of the peaks increases proportionally with Eu3+ concentration and the calcination temperature with no luminescence quenching phenomenon observed even for Y2O3:13%Eu3+. The fluorescent emission properties combined with the monodispersity and narrow size distribution characteristics make the Y2O3:Eu3+ heavy metal free nanophosphors applicable in fluorescence cell imaging and as fluorescence biolabels.

Effect of Europium Ion on Pseudoboehmite Phase Transition and Microstructure

Abstract After doping Eu(NO3)3 into pseudoboehmite sol suspension, europium-doped pseudoboehmite xerogel was prepared by a spray-drying process. Effects of Eu3+ ions on pseudoboehmite phase transition and microstructure were investigated by differential thermal gravimetric analysis, X-ray powder diffraction and field emission transmission electron microscopy. Results show that upon doping of Eu3+ ions into pseudoboehmite, the phase transition temperatures of γ-Al2O3→θ-Al2O3 and θ-Al2O3→α-Al2O3 increase by 172 oC and 13 oC, respectively. It is found that Eu3+ ions entirely enter γ-Al2O3 or θ-Al2O3 crystal lattices, and the crystallinity of γ-Al2O3 is improved, resulting in increasing of the phase transition temperature of γ-Al2O3→θ-Al2O3. When α-Al2O3 is generated in the phase transition process, all of Eu3+ ions exist among α-Al2O3 grain boundaries in the form of compound EuA112O19, which will hinder the bulk diffusion of Al3+ resulting in an increase of phase transformation temperature of θ-Al2O3→α-Al2O3 process.

Facile controlled synthesis different morphologies of LuBO3:Ln3+ (Ln = Eu, Tb) phosphors and tunable luminescent properties

Sphere-like and cauliflower-like hexagonal-vaterite LuBO3 have been successfully synthesized for the first time via a chemical conversion route using Lu(OH)CO3 colloid spheres as sacrificial precursor and H3BO3 as boron source without any additional surfactant. FTIR analysis provides an additional evidence of the formation of vaterite-type LuBO3 in this method. It was found that, an appropriate amount ethanol in the hydrothermal process has a great effect on the products' morphology and crystallinity. Time-dependent experiments indicate that the formation of LuBO3 crystals went through a two-stage growth process, which involves a fast nucleation of primary particles followed by a slow aggregation and crystallization of primary particles. An investigation on the photoluminescence (PL) properties of LuBO3:Eu3+ phosphors with different morphologies indicates that their PL intensity are dependent on their crystallinity. The effect of Eu3+ and Tb3+ doping concentration on PL intensity were also investigated and the quenching concentration of LuBO3:Eu3+ and LuBO3:Tb3+ is 0.25 and 0.20, respectively. Moreover, for Eu3+/Tb3+ doped LuBO3 phosphors, the color tones can be tuned from green, through green–yellow and yellow, and then to red by simply adjusting the relative doping concentrations of the Tb3+ and Eu3+ ions.

Preparation and investigation of Eu3+-activated ZnMoO4 phosphors for white LED

Eu3+-doped ZnMoO4 red phosphors with different doping concentrations were synthesized at the temperature of 800 °C by solid-state reaction technique in air atmosphere. The structures of the phosphors were characterized by X-ray diffraction and Raman spectra. The excitation and emission spectra were used to investigate the photoluminescent properties of the phosphors. The effect of Eu3+ concentration on the structural and photoluminescent properties of ZnMoO4:Eu3+ red phosphors were discussed systemically. And the photoluminescent properties of ZnMoO4:Eu3+ red phosphors under different excitation wavelengths were investigated to find their utilities in various lighting applications. Strong red emission intensity and high color purity with chromaticity coordinates (0.666, 0.334) were obtained for Zn0.8MoO4:0.2Eu3+ phosphors excited at 395 nm. The Zn1−xMoO4:xEu3+ phosphors, which could be applied as red-emitting phosphors excited by ultra-violet and blue chips, have potential application in white light-emitting diodes.

Enhanced luminescence properties of Sr3−xEuxAlO4−yNyF phosphors

Luminescent materials with the chemical formula Sr3−xEuxAlO4−yNyF were prepared by a solid-state reaction. X-ray diffraction (XRD) patterns, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), photoluminescence emission and excitation spectra, the lifetime, the temperature-dependent luminescence, and the effects of Eu3+ and N3− concentrations were investigated in detail. Partial substitution of Sr2+ by Eu3+ and O2− by N3− in Sr3−xEuxAlO4−yNyF contributes to form quadrangular crystals, and enhance the thermal stability against the temperature quenching effect. After the partial replacement of Sr2+ by Eu3+ and O2− by N3− ions in the Sr3AlO4F host structure, the emission intensity was enhanced and the charge-transfer band of O2p→Eu4f shifted to higher wavelength.

NaLa(MoO4)2: RE3+ (RE3+ = Eu3+, Sm3+, Er3+/Yb3+) microspheres: the synthesis and optical properties

NaLa(MoO4)2: RE3+ (RE3+=Eu3+, Sm3+) microspheres have been synthesized at 180°C via a facile EDTA-mediated hydrothermal route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra were employed to characterize the samples. It was found that the amount of EDTA in the initial solution was responsible for crystal phase and shape determination. The effect of Eu3+ and Sm3+ doping concentrations on the luminescent intensity was also investigated in details. Furthermore, the up-conversion (UC) emissions have been observed in a series of Er3+/Yb3+ co-doped NaLa(MoO4)2 samples. Concentration dependent studies revealed that the optimal composition was realized for a 2% Er3+ and 10% Yb3+-doping concentration.

Enhanced Multiferroic Properties of Eu-Doped BiFeO3 Thin Films Derived from Rhombohedral–Tetragonal Phase Boundary

Eu-doped BiFeO3 multiferroic thin films were prepared using a sol–gel technique. The effect of Eu3+ ion substitutional doping on the multiferroic properties of BiFeO3 thin films was investigated in detail, revealing obvious enhancement of ferroelectricity and ferromagnetism. The enhanced multiferroic properties are attributed to phase boundary, where two phases with rhombohedral and tetragonal structure coexist. Both x-ray diffraction analysis and Raman spectroscopy confirmed that BiFeO3 thin films with 5% Eu doping (Bi0.95Eu0.05FeO3) undergo a phase transformation from a rhombohedral to tetragonal structure. Thus, it is suggested that there is rhombohedral– tetragonal phase boundary in Bi0.95Eu0.05FeO3 thin films. Additionally, the leakage current density of the thin films decreased under high electric field after Eu doping, which is attributed to a change of the leakage current conduction mechanism related to the formation of rhombohedral–tetragonal phase boundary. The present work provides an easy method to enhance the multiferroic properties of BiFeO3-based thin films.

Photoluminescence and resonant energy transfer from Tb3+ to Eu3+ in Tb3Ga5O12:Eu3+ garnet phosphor

Eu3+-activated Tb3Ga5O12 (TGG) phosphor was synthesized by metal-organic deposition and its luminescence properties were reported in detail. The (Tb1−xEux)3Ga5O12 phosphor was synthesized from a mixture of organic gallium solution and acetic acid dissolved with TbCl3/Eu2O3. The X-ray diffraction analysis indicated that the synthesized phosphor was cubic garnet structure. The luminescence properties of the TGG:Eu3+ phosphor were investigated using photoluminescence (PL) analysis, PL excitation (PLE) spectroscopy, and PL decay measurement. The effects of Eu3+ concentration on the PL properties were studied between x=0 and 0.14, and the strongest PL emission was observed at x~0.002. The PLE and PL decay characteristics showed the occurrence of an efficient energy transfer from the host (Tb3+) to Eu3+ in the TGG:Eu3+ phosphor. The increase in the PL intensity with increasing temperature was observed and analyzed on the basis of a simplified charge transfer along with the inclusion of conventional thermal quenching. The detailed energy-level scheme for the Tb3+ and Eu3+ ions in the TGG host was also determined from these PL and PLE spectra.

Preparation and thermally stable luminescence properties of a new blue Sr5Cl0.75F0.25(PO4)3: Eu2+ phosphor for WLEDs

A series of new blue-emitting phosphors Sr5(1−x)Cl0.75F0.25(PO4)3: 5xEu2+ (x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6mol%) were synthesized by high-temperature solid state reaction. X-ray powder diffraction (XRD) and field-emission scanning electron microscope (FE-SEM) were used to characterize the crystal structure and micro-morphology of the prepared samples. The photoluminescence properties of these phosphors were investigated by excitation and emission spectra. The effect of Eu2+ concentration on emission of the phosphor was investigated and the concentration quenching mechanism was discussed in detail. Also, the temperature-dependence luminescence properties of Sr5Cl0.75F0.25(PO4)3: Eu2+ were compared with those of the commercial blue phosphor BaMgAl10O17: Eu2+ (BAM). With the increase of temperature, the emission band exhibited blue shift and decreasing emission intensities. The phosphor Sr5Cl0.75F0.25(PO4)3: Eu2+ possesses higher thermal stability than BAM. Furthermore, a bright blue LED was fabricated by combination of n-UV InGaN chip and the phosphor. The results reveal that Sr5Cl0.75F0.25(PO4)3: Eu2+ is a potential blue phosphor for n-UV-pumped white light-emitting-diodes (WLEDs).

Hydrothermal synthesis, microstructure and luminescence properties of BiPO4:Eu3+ phosphor

The paper focus on the effect of Eu3+ ions concentrations, synthesis temperature and dilute nitric acid content on the microstructure and luminescence of BiPO4:Eu3+ sample. XRD results show that the as-prepared BiPO4:Eu3+ sample had a hexagonal structure and the change of test conditions do not introduce any secondary or other related phase in any of the samples. The emission spectra of BiPO4:Eu3+ samples display the bands associated to the 5D0 → 7FJ electronic transitions characteristics of the Eu3+ ions at different positions. The change of nitric acid content is the most effective way to improve luminescence properties. The reason can be attributed to it caused the morphology has obvious change. The best synthetic conditions of the particles at 0.05Eu3+, synthesis temperature 170 °C and dilute nitric acid content 4 ml, respectively.

Controlled synthesis and luminescent properties of different morphologies GdBO3:Eu3+ phosphors self-assembled of nanoparticles

Abstract Uniform cake-like and olive-like GdBO3 samples have been successfully synthesized for the first time via a simple solution-based hydrothermal method using Gd(OH)CO3 colloid spheres and NaBO2·4H2O as the precursors. It was found that small amount ethanol in the hydrothermal process was responsible for determining the shape of products. The FT-IR analysis indicates that vaterite-type GdBO3 can be synthesized by this method. The obtained cake-like and olive-like GdBO3 with rough surfaces have similar mircostructures which are composed of numerous nanoparticles. Time-dependent experiments were employed to study the possible formation mechanism. The formation of cake-like and olive-like GdBO3 mircostructures self-assembled of nanoparticles can be ascribed to the Ostwald ripening process. A detailed investigation on the photoluminescence (PL) properties of GdBO3:Eu3+ samples with different morphologies indicates that the PL properties of as-obtained GdBO3:Eu3+ phosphors are dependent on their morphologies. The effect of Eu3+ doping concentration on PL intensity was also investigated and the quenching concentration of GdBO3:Eu3+ is 20%.

Hydrothermal synthesis and tunable luminescence of CaSiO3:RE3+(RE3+ = Eu3+, Sm3+, Tb3+, Dy3+) nanocrystals

CaSiO3:RE3+ (RE3+=Eu3+, Sm3+, Tb3+, Dy3+) nanocrystals were prepared by facile hydrothermal method with further calcinations. The crystal structure and the effects of annealing temperature on phase transition have been characterized by X-ray diffraction (XRD). The photoluminescence (PL) and PL excitation (PLE) spectra were used to characterize the optical properties of all samples. The effect of Eu3+ and Sm3+ doping concentrations on the luminescent intensity were also investigated in details, respectively. Moreover, the luminescence colors of the Tb3+ and Eu3+ co-doped CaSiO3 samples can be tuned by simply adjusting the relative doping concentrations of the rare earth ions under a single wavelength excitation, which might find potential applications in the fields of light display systems and optoelectronic devices.