Luminescence Properties Of Eu3 Research Articles

Synthesis, structural and luminescent properties of Eu2+/Dy3+ activated GdAlO3 phosphors by solid state reaction method under nitrogen atmosphere

Eu2+ and Dy3+ singly doped and codoped GdAlO3 phosphor was synthesized by solid state reaction method in a reducing atmosphere of nitrogen. Samples were characterized by powder X-ray diffraction (PXRD) analysis. The average crystal size was obtained around 68 nm. Surface morphology was verified by scanning electron microscopy (SEM) analysis. The emission spectra of phosphors singly doped with Eu2+ and codoped with Eu2+; Dy3+ respectively were recorded under 354 nm excitation. The emission spectra of Eu2+ has intense emission peak at 515 nm. It was observed that the after codoping with Eu2+ and Dy3+ the emission bands of Eu2+ dominates along with a new emission band centred at 419 nm. CIE chromaticity diagram shows variation in emitted colour with Eu2+, Dy3+ singly doped and codoped phosphor. The investigation of Dy3+ codoping shows the colour tunable behaviour of the phosphor. This colour tunable behaviour of the phosphor makes it useful in the colour display applications.

Raman and photoluminescence studies of europium doped zinc-fluorophosphate glasses for photonic applications

Europium (Eu3+)-doped zinc-fluorophosphate (PKAZfEu) glasses have been synthesized by usual melt-quenching technique. Optical absorption, photoluminescence excitation, photoluminescence and decay curves of these glasses were measured at room temperature and investigated. The Judd-Ofelt (JO) parameters (Ωλ, λ = 2 and 4) were determined from the measured emission spectra and used for quantifying the radiative parameters that include radiative transition probability (AR), radiative lifetime (τR), branching ratios (βR), effective bandwidths (∆λeff) and peak stimulated emission cross-section (σ(λP)) for the 5D0 luminescent state of Eu3+. The electron-phonon coupling strength and phonon energy of the glasses were obtained from the phonon sideband spectrum. The chromaticity coordinates for different concentration of PKAZfEu glasses were evaluated by analyzing the emission spectra with Commission International de l'Eclairage (CIE) color diagram. Decay curves of Eu3+ ions for the 5D0 → 7F2 transition have been obtained under 393 nm excitation. The decay curves exhibit a single exponential behavior for all the investigated glasses. Luminescence properties of Eu3+ ion for the 5DO → 7F2 transition indicate that the PKAZfEu glasses could be a suitable gain medium for visible red lasers and display devices.

Synthesis and luminescence properties of Eu3+ co-doped NaBi(MoO4)2:Dy3+ phosphors for white light-emitting diodes

Dy3+-doped and Dy3+/Eu3+ co-doped NaBi(MoO4)2 phosphors were successfully synthesized using a high temperature solid-state method. The crystal structure and phase purity of these as-prepared samples were characterized by X-ray diffraction. Under 453 nm excitation, NaBi(MoO4)2:Dy3+ phosphors exhibited the characteristic weak blue emission peak at 488 nm and strong yellow emission peak at 577 nm, which originate from the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ ions, respectively. Therefore, a white light could be composed of a blue light from chip and yellow emission of NaBi(MoO4)2:Dy3+ phosphor. Additionally, color-tunable emissions were observed in the spectra of NaBi(MoO4)2:Dy3+, Eu3+ phosphors due to efficient energy transfer from Dy3+ to Eu3+ ions. By varying co-doping concentrations of Dy3+ and Eu3+ ions, the emission color of NaBi(MoO4)2:Dy3+, Eu3+ could be varied for high quality blue-excited white light-emitting diodes.

Synthesis and luminescence properties of Eu3+ and Dy3+ ions single and co-doped Ba2LaV3O11 phosphors for white-light applications

We report the synthesis and luminescence properties of the rare-earth ions doped Ba2LaV3O11 phosphors. The Dy3+ and Eu3+ ions single doped and Dy3+/Eu3+ ions co-doped Ba2LaV3O11 phosphors were synthesized via a citrate-based sol-gel method. The surface morphology, phase purity, photoluminescence properties and thermal stability of the synthesized phosphors were determined from the X-ray diffractometer, field-emission scanning electron microscope and spectrofluorometer, respectively. The obtained results indicate that the prepared phosphor material was crystallized in monoclinic phase with the space group P21/c (14) and the diffraction peaks were well matched with the standard JCPDS (#40-0105) card values. Under charge transfer band excitation wavelengths, the Eu3+ (277 nm) and Dy3+ (274 nm) single doped phosphor samples exhibited characteristic red and yellow emissions, respectively. Meanwhile, the Dy3+/Eu3+ co-doped phosphor samples showed near white-light emission.

Highly Efficient and Thermally Stable Blue-Green (Ba0.8Eu0.2O)(Al2O3)4.575×(1+ x) Phosphor through Structural Modification.

Exploring phosphors with high quantum efficiency (QE) and thermal stability is an important issue for their application in white light-emitting diodes (LEDs). In this work, the crystal structure and luminescent properties of Eu2+-activated aluminate phosphors with a normal composition (Ba0.8Eu0.2O)(Al2O3)4.575×(1+ x) (short for BA1+ xO:0.2Eu2+) were studied. Although the crystal structures of BA1+ xO:0.2Eu2+ have a same space group, the increase of the Al content will lead to the decrease of cell volume, occupancy of Ba and O6 that is at around Ba1 site, and the increase of the average distance between Eu2+ ions, which are responsible for the modification of luminescent properties. BA1+ xO:0.2Eu2+ exhibits a blue-green emission with an emission peak at around 450 nm and a shoulder at around 490 nm. The increase of Al/(BaEu) ratio results in the increase of both absolute QE and thermal stability. The absolute QE of BA1.5O:0.2Eu2+ is 99.4%, and the emission intensity at 150 °C remains more than 90% of that at room temperature, showing the best performance. Furthermore, all of the external QE values of BA1+ xO:0.2Eu2+ ( x = 0.2-0.5) are higher than 70%. The properties of the LEDs based on the as-prepared phosphor suggest its potential as a candidate for UV LED pumped phosphor-converted white LEDs.

Preparation and luminescent properties of Eu(Ⅲ) organic complex and novel transparent ethylene-methyl acrylate copolymer (EMA) films doped with complexes

In this study, a new ternary rare earth organic complex Eu(POA)3TTA was synthesized and successfully doped into the ethylene-methyl acrylate copolymer (EMA) resins. The transparent doped EMA (Eu-EMA) films with excellent fluorescence performance were obtained by making full use of the excellent compatibility and filling performance of EMA resins. Fourier transform infrared spectrometer (FT-IR), elemental analysis, MALDI-TOF MS, scanning electron microscope (SEM), photoluminescence tests, thermogravimetric analysis (TGA) and static water contact angle measurements were used to characterize the properties of the complexes Eu(POA)3TTA and the Eu-EMA films. FT-IR analysis, elemental analysis and MALDI-TOF MS verify the ligands were successfully coordinated with the Eu3+ ions. The Eu(POA)3TTA particles are well dispersed in the EMA matrix and only a small fraction of them precipitate out to the surface of the EMA films. The relationship between fluorescence emission intensity of the Eu-EMA films and the doping ratios of Eu(POA)3TTA to EMA resins has been studied and discussed. The fluorescence intensity of the Eu-EMA films reaches the maximum when the doping ratio is 1.0 wt%. The Eu-EMA films all have high thermal stability (Td ≥ 392 °C) and the Td value enhances as the doping ratio increasing. As a result, the Eu-EMA films possess potential application for luminescent materials even at high temperatures.

Luminescence properties of Eu3+ ions doped in novel host materials Sr9R(PO4)7 (R = In, Ga)

Novel Sr9R(PO4)7 (R = In, Ga) host materials for Eu3+ - doped phosphors were synthesized by a high-temperature solid-state reaction method. The crystal structure, luminescence properties and thermal stability of the phosphors were explored. The phase analysis indicated that the phosphors crystallized in monoclinic structure, the emission spectra of both In and Ga containing phosphors were mainly composed of two sharp peaks centered at about 591 and 617 nm, corresponding to the 5D0→7F1 and 5D0→7F2 transitions of Eu3+ ions. While, the relative emission and excitation intensities of Sr9In(PO4)7: Eu3+ were weaker than Sr9Ga(PO4)7: Eu3+. Moreover, the energy transfer mechanism among Eu3+ ions in the phosphors depended upon energy transfer among the nearest-neighbor ions described by the Dexter theory. The selected Sr9In(PO4)7: 0.06Eu3+ and Sr9Ga(PO4)7: 0.06Eu3+ exhibited high thermal stability and the chromaticity coordinate of the phosphors were located in the red-orange light region.

Investigation on crystallization kinetics and luminescent properties of Eu2+/Eu3+-coactivated hexacelsian based glass ceramics

The thermal properties and crystallization behavior of MgOBaOSiO2B2O3Al2O3 glass have been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). After crystallization at temperature (800 °C) close to the DSC crystallization peak, dendritic hexacelsian crystals are found to form as the major crystalline phase among glass. The crystallization kinetics was studied by analyzing DSC curves with Chen's and Ozawa's equations. The mean crystallization activation energy and Avrami's parameter are evaluated to be 229 kJ/mol and 1.4, indicating that the crystallization process occurs predominantly by surface crystallization as consistent with experimental data. Concurrent emissions of Eu2+ and Eu3+ under 304 nm excitation demonstrate that partial reduction of Eu3+ to Eu2+ occurs, which could be ascribed to the partition of Eu3+ into the precipitated hexacelsian crystals during the sintering process of glass ceramics. These results indicate that glass ceramic route may serve as an intriguing way for synthesis of phosphors applicable to lighting and display fields.

Luminescence properties of Eu3+-activated TbAlO3 perovskite compound synthesized by metal organic decomposition

Eu3+-activated TbAlO3 perovskite (TAP:Eu3+) phosphor was synthesized by metal organic decomposition and subsequent calcination at Tc = 1200 °C in air. The luminescence properties of the TAP:Eu3+ phosphor were investigated in detail by photoluminescence (PL) spectroscopy and PL excitation (PLE) spectroscopy, together with PL decay measurements. The PLE spectra and PL decay behaviors of the Eu3+ and Tb3+ emissions showed evidence of resonant energy transfer from the TAG host (Tb3+) to Eu3+. The temperature dependence of the Eu3+ emission intensity was measured at T = 10–450 K and analyzed using the conventional quenching model with the addition of the phonon occupation number term, which was promising for gaining the parity-forbidden Eu3+ transition intensity. This study was also focused on a lattice site of the Eu3+ dopant ions substituting whether for the A-site (Tb3+) or B-site (Al3+) in the TAP lattice. The Stark splitting of the 5D0 to 7FJ level transitions suggests that the Eu3+ ions are substituted for the A-site with the point symmetry Cs.

Effect of H2O and D2O Thermal Anomalies on the Luminescence of Eu3+ Aqueous Complexes

Aqueous solutions of luminescent metal–ion complexes, in particular, those of lanthanide ions, can play an essential role in biomedical applications. For all of these applications, the knowledge about the influence of temperature variations within the physiological range (20–60 °C) on their optical properties becomes essential. At variance with other liquids, water is unique as it does present an anomalous temperature-dependent behavior. In particular, most water properties present remarkable physicochemical changes above a certain temperature, which ranges between 30 and 50 °C. In this work, we systematically investigate the effect of temperature on the luminescence properties of Eu3+ ions when dissolved in either H2O or D2O. An anomalous thermal behavior, manifested as a bilinear trend, with crossover at around 35 °C for H2O and 38 °C for D2O, is found in a variety of Eu3+ optical spectroscopic properties (branching ratio, luminescence lifetime, and emission band shape). The observed changes are tentatively explained here in terms of different aggregation states of H2O and D2O molecules below and above the crossover temperature. Such changes in the molecular clustering lead to a temperature-induced change in the relative concentrations of the 8-fold and 9-fold coordinated Eu3+ complexes. Finally, we have observed that the pH of the aqueous solution plays an essential role in defining the temperature at which the anomaly takes place so that the differences in the values reported in the literature for the crossover temperature are accounted for.

TRLFS study of hydrolyzed Eu(III) species

The hydrolysis of Eu(III) and Am(III) begins near neutral pH conditions, above which precipitation occurs due to low solubility. Careful sample characterization steps are a prerequisite for the speciation study of hydrolyzed Eu(III) complexes without the interference of colloidal particles or precipitation. Herein, the hydrolysis reaction of Eu(III) was studied using time-resolved laser fluorescence spectroscopy (TRLFS). Laser-induced breakdown detection was employed to monitor the presence of colloidal particles. The luminescence properties of Eu(III) and precipitated Eu(OH)3(s) were investigated and comparisons were made to those of aqua Eu3+. Parallel factor analysis was applied for the deconvolution of the TRLFS results. Both primary hydrolyzed Eu(III), EuOH2+ and precipitated Eu(OH)3(s) showed distinct luminescence spectral properties, including an enhanced hypersensitive luminescence peak (J = 2). An increased luminescence lifetime was observed for both EuOH2+ (τ = 130 ± 1 μs) and precipitated Eu(OH)3(s) (τ = 158 ± 7 μs) compared to that of aqua Eu3+ (τ = 112 ± 1 μs). A formation constant log*β1,1 of EuOH2+ at I = 0.1 M NaClO4 and 25 °C was measured to be –8.28 ± 0.22, which was converted to log*β°1,1 = –7.87 ± 0.22 at an infinitely diluted condition of I = 0 based on the specific ion interaction theory.

Luminescence properties of Eu3+ activated Y2O3 red phosphor with incorporation of Ga3+ and Bi3+ trace hertero-cations in the Y2O3 lattice

The luminescence characteristics of Eu3+ doped Y2O3 in the presence and absence of Bi3+/Ga3+ trace ions prepared by the sol-gel combustion method were investigated. The results revealed that, the Bi3+ and Ga3+ ions have a significant influence on the excitation position and emission bands intensity of Eu3+ doped Y2O3. The cathodoluminescence (CL) intensity of the Y2O3:Eu3+ incorporated with Bi3+/Ga3+ ions has been considerably enhanced (five times), compared to the CL intensity of the unincorporated Y2O3:Eu3+ samples. This phenomenon was attributed to the energy exchange in the excitation bands of the Bi3+ and Eu3+ ions.

Effects of Bi3+ ions on luminescence properties of ZnWO4:Eu3+, Sm3+, Bi3+ nanorods

To develop red emitting phosphors for white LEDs, a series of ZnWO4:xEu3+, ySm3+, zBi3+ (x, y and z are values in mol%, x = 5; y = 0, 0.6; 0 ≤ z ≤ 11) phosphors were prepared by hydrothermal method, and their structures, characteristic photoluminescence properties and energy transfer mechanism were studied in detail. The causes for the morphological changes after doping Sm3+ and Bi3+ ions were also analyzed in our work. It could be determined that all the samples were pure monoclinic ZnWO4. For Bi3+ doped ZnWO4:Eu3+, the dominant emission band located at 617 nm (when λex = 357 nm) was significantly enhanced by the efficient energy transfer (from Bi3+ to Eu3+). In addition, the experiment also found that Bi3+ doped ZnWO4:Eu3+ had a stronger emission than ZnWO4:Eu3+ (without Bi3+ sensitization) excited at 465 nm. This phenomenon appeared in ZnWO4:Eu3+, Sm3+, Bi3+ as well. Thus, we suggest that the introduction of Bi3+ leads to structural distortion that affects the f–f transition of Eu3+ in ZnWO4:RE3+. The obtained results clearly indicate the beneficial influence of introduction of Bi3+ ions on luminescence properties of Eu3+ in our work.

Reduction of Eu3+ to Eu2+ in α-Y2Si2O7 and X1-Y2SiO5 and their luminescent properties

Due to its bright tunable emission, Eu-doped yttrium silicates are very interesting materials for LED applications. The microparticles of α-Y1.98 Eu0.02 Si2O7 and the low-temperature phase of Y1.98 Eu0.02 SiO5 (X1) were prepared by sol gel technique. Then, the samples were reduced at high temperatures using pure hydrogen as reduction agent. The materials obtained were characterized by X-Ray diffraction, Scanning Electron Microscopy, Energy Dispersive X-Ray and Photoluminescence spectroscopy. The presence of Eu2+ in the materials after the reduction was confirmed by the blue-green band emission and the wide absorption band, observed only in the excitation spectra of the reduced samples. These bands are congruent with the information previously reported in the literature. A red shift of the broadband emission of Eu2+ doped α-Y2Si2O7 system was observed compared to previously reported results. Also, the luminescent properties of Eu2+ host in X1-Y2SiO5 are presented for first time. The relative contribution of Eu2+ and Eu3+ depends on the excitation wavelength leading to a tunable emission phosphor with potential application in white LEDs. Summarizing, the reduction of Eu ions in yttrium silicates is presented in this work, leading to a tunable emission phosphor with potential application in white LEDs.

Investigation of Upconversion, downshifting and quantum –cutting behavior of Eu3+, Yb3+, Bi3+ co-doped LaNbO4 phosphor as a spectral conversion material

This work presents the spectral conversion characteristics [upconversion (UC), downshifting (DS) and quantum–cutting (QC) optical processes] of Eu3+, Yb3+ and Bi3+ co-doped LaNbO4 (LBO) phosphor samples synthesized by solid state reaction technique. The crystal structure and the pure phase formation have been confirmed by x-ray diffraction (XRD) measurements. The surface morphology and particle size are studied by scanning electron microscopy (SEM). The rarely observed intense red UC emission from Eu3+ ion has been successfully obtained in Eu3+/Yb3+ co-doped LaNbO4 phosphor (on excitation with 980 nm) by optimizing the concentrations of Eu3+ and Yb3+ ions. The downshifting (DS) behavior has been studied by photoluminescence (PL) measurements on excitation with 265 nm wavelength from a Xe lamp source. A broad blue emission in the region 300–550 nm with its maximum ∼415 nm due to charge transfer band (CTB) of the host and large number of sharp peaks due to f-f transitions of Eu3+ ion have been observed. The energy transfer has been observed from (NbO4)3− to Eu3+ ion and the fluorescence emission has been optimized by varying the concentration of Eu3+ ion. An intense red emission has also been observed corresponding to 5D0 → 7F2 transition of Eu3+ ion at 611 nm in LBO: 0.09Eu3+ phosphor on excitation with 394 nm. The luminescence properties of Eu3+ ion are enhanced further through the sensitization effect of Bi3+ ion. The near infra-red (NIR) quantum cutting (QC) behavior due to Yb3+ ion has been monitored on excitation with 265 as well as 394 nm. The NIR QC is observed due to 2F5/2 → 2F7/2 transition of Yb3+ ion via co-operative energy transfer (CET) process from (NbO4)3− as well as Eu3+ ions to Yb3+ ion. This multimodal behavior (UC, DS and QC) makes this a promising phosphor material for multi-purpose spectral converter.

Gamma-radiation effects on luminescence properties of Eu3+ activated LaPO4 phosphor

Abstract Eu3+ activated LaPO4 phosphors were prepared by a high-temperature solid-state method and irradiated to different high-doses gamma-radiation in the 0–4 MGy range. No effects of high-doses of high-energy radiation on phosphor’s morphology and structure were observed, as documented by electron microscopy and X-ray diffraction measurements. On the other hand, photoluminescence measurements showed that emission properties of phosphor were affected by gamma-radiation; changes in radiative properties being prominent for absorbed radiation doses up to 250 kGy after which no additional changes are observed. Judd-Ofelt analysis of emission spectra is performed to thoroughly investigate radiative properties of phosphors. Analysis showed that radiative transition probability of Eu3+ emission decreases while non-radiative probability increases upon gamma-irradiation. Quantum efficiency of emission is decreased from about 46% to 35% when Eu3+ doped LaPO4 powders are exposed to gamma-radiation of 250 kGy dose, showing no additional decrease for higher gamma-radiation doses.

Effects of Tb3+ doping on luminescence properties of NaMg4(PO4)3:Eu2+

Eu2+ and Tb3+ co-doped NaMg4(PO4)3 phosphors have been synthesized via a combustion-assisted synthesis method. A detailed study of the role of Tb3+ concentration on the luminescence properties of Eu2+ in NaMg4(PO4)3: Eu2+,Tb3+ has been carried out. NaMg4(PO4)3:Eu2+,Tb3+ phosphors exhibited a broad excitation band ranging from 220 to 400 nm and two broad emission bands that peaked at 424 and 546 nm, which were ascribed to the allowed 4f65d1→4f7 transition of Eu2+ ions and the 5D4→7F5 transition of Tb3+ ions, respectively. Initially, the emission intensity of Eu2+ decreases with increasing Tb3+ concentrations, which is related to the energy transfer (ET) from Eu2+ to Tb3+. Then, the Tb3+-doping enhances the emission intensity of Eu2+ obviously. This can be ascribed to the possible oxidation-reduction process between Eu3+ and Tb3+ to give Eu2+ and Tb4+, as confirmed by X-ray photoelectron spectroscopy and luminescence studies. The combined effects of ETEu−Tb and oxidation-reduction process between Eu3+ and Tb3+ on luminescence and emission color of NaMg4(PO4)3:Eu2+,Tb3+ phosphors are systematically investigated.

Site occupancy and luminescence properties of Eu3+ in double salt silicate Na3LuSi3O9

Eu3+ luminescence is helpful to probe the local structure of luminescent centers in a host lattice. In order to analyze the site occupancy and luminescence properties of Eu3+ in double salt silicate Na3LuSi3O9, Na3LuSi3O9:Eu3+ phosphors were prepared using a high temperature solid-state reaction method, and their luminescence spectra and decay curves under UV excitation were determined. According to the characteristic emission of O2- - Eu3+ charge transfer bands, 5D0-7F0, 5D0-7F1 and 5D0-7F2 transitions of Eu3+ in Na3LuSi3O9, the site occupancy of Eu3+ in the host Na3LuSi3O9 was clarified, which will be of benefit to the development of new luminescence materials based on the double salts silicates host Na3LuSi3O9.

Luminescent properties of Eu3+ co-doped Y2O3: Dy3+ phosphors synthesized via ceramic route

The Eu3+ co-doped Y2O3: Dy3+ phosphors were synthesized by solid-state reaction method, also known as a ceramic route. The properties of synthesized phosphors were studied with the help of PXRD, SEM, EDX, FTIR, Photoluminescence (PL) spectra, CIE coordinates and Thermoluminescent (TL) spectra. The PL spectra exhibit emissions at 486, 588, 596, 610, 681 and 693 nm due to the energy transfer between dopant ions. The blue emission is dominated due to dysprosium ions. The TL spectra were recorded for synthesized phosphors irradiated by UV and γ radiation. For UV irradiated phosphors, TL glow peaks were obtained at 455, 490 and 549 K whereas for γ irradiated phosphors TL glow peaks were obtained at 470 and 650 K. Using deconvoluted TL curves, kinetic parameters were computed by peak shape method. Second order kinetics were obtained with activation energy values varying from 7.553 × 10− 1 to 11.10 × 10− 1 eV for UV irradiated phosphors and 11.152 × 10− 1 to 15.252 × 10− 1 eV for γ irradiated phosphors.

The self-reduction synthesis and luminescent properties of Eu2+-Eu3+ activated BaZr0.2Si2O5.4 phosphors with white light emission for white light-emitting diodes

The BaZr[Formula: see text]Si2O[Formula: see text]: Eu[Formula: see text]/Eu[Formula: see text] phosphors were prepared with different concentrations of Eu2O3 by a self-reduction method under air condition. The X-ray diffraction and the photoluminescence properties of the prepared samples were analyzed. The emission spectra consisting of a broadband emission from the 4f[Formula: see text]5d transitions of Eu[Formula: see text] and sharp emissions from 5D0-7F[Formula: see text] (J = 0, 1, 2, 3, 4) transitions of Eu[Formula: see text] are observed. The different luminescent colors can be obtained and modulated by doping different concentrations of Eu2O3 and the white light emission can be observed as the concentration of europium is 6%.