Incorporation Of Eu3 Research Articles

Conjugation of TbPO4·H2O-Based Nanowires with Immunoglobulin G for Bioimaging

The surface modification, functionalization, and conjugation of undoped and 11 at.% Eu3+-doped TbPO4 ·H2O nanowires by using silica, a thyocyanate functional group, and immunoglobulin G, respectively, are described in this paper. For the core layer of obtained conjugated nanowires, the undoped TbPO4 ·H2O exhibited characteristic photoluminescent green emission corresponding to 5 D 4 → 7 F J transitions (J = 6, 5, 4, 3) while the incorporation of Eu3+ into TbPO4 ·H2O lattice was evidenced by Starks splitting transitions at 590, 615, 693 nm of Eu3+ ions for the case of 11 at.% Eu3+-doped TbPO4 ·H2O. The results also indicated that both immunoglobulin G-conjugated undoped and Eu3+-doped TbPO4 ·H2O nanowires can be used in the fluorescent immune analysis as a biomedical label maker to identify measles viruses in vaccine testing.

Photoluminescence characteristics of Ce and Eu activated MBPO5 (M = Sr, Ca) phosphors

In this paper we have reported the luminescence characterizations of rare earths Ce and Eu activated MBPO5 (M=Sr, Ca) phosphors synthesized by modified solid state reaction and studied for photoluminescence (PL) studies. The incorporation of Ce and Eu in 3+ oxidation state was ascertained from PL studies. The spectral characteristics have revealed that the excitation spectra of Eu2+ activated SrBPO5 phosphor shows the strong broad peak observed at 354nm (monitored at 422nm) near UV region and is favorable to solid-state lighting excitation. The orange–red (589 and 591nm) emission in Eu3+ activated CaBPO5 is due to 5D0–7F1 transition of Eu3+ and this is permitted only in cases of Cs, Cn, and Cnv symmetries observed at Eu3+ sites. All these are the features of the f↔f transition of the trivalent europium ion. PL properties of Ce3+ activated MBPO5 (M=Sr, Ca) revealed the broad band emission at 375nm.

The influence of phase evolution on optical properties in rare earth doped glass ceramics containing NaYF4 nanocrystals

The crystal phase evolution from cubic α-NaYF4 to hexagonal β-NaYF4 was achieved in transparent oxyfluoride glass ceramics by modifying glass composition and rare earth doping. It was found that the development of compressive stress during the crystallization process may be responsible for the formation of β-NaYF4 nanocrystals. The incorporation of Eu3+ ions into the precipitated NaYF4 nanocrystals was verified and the difference of the distribution of Eu3+ ions in the glass ceramics resulted in remarkable changes in the emission spectra, such as the relative emission intensity, Stark splitting and fluorescence decay lifetimes. Bright and efficient upconversion luminescence was observed in the Er3+/Yb3+ co-doped glass ceramics and the corresponding upconversion mechanisms were analyzed.

Controllable synthesis and selective doping of hexagonal GdF3 and spinel-like Ga2O3 nano-crystals in silicate glass

Eu3+/Ni2+ co-doped transparent glass ceramic containing both hexagonal GdF3 and spinel-like Ga2O3 nano-crystals has been successfully fabricated by melt quenching and subsequent heating. The orderly precipitation of GdF3 and Ga2O3 nano-crystals was discriminated by the X-ray diffraction data and transmission electron microscopy. The incorporation of Eu3+ ions into GdF3 and the selective partitioning of Ni2+ dopants in Ga2O3 were evidenced by the absorption and emission spectra, luminescence decay curves, crystal field calculation, and Judd–Ofelt analysis. Benefitting from the spatial separation, the energy transfer between Eu3+ and Ni2+ was suppressed completely. The distribution related optical properties of Eu3+ and Ni2+ in glass ceramic were investigated in detailed. This work exemplifies a rational design strategy to construct novel multifunctional materials for optical application.

Synthesis of Gd2O3:Eu nanoplatelets for MRI and fluorescence imaging.

We synthesized Gd2O3 and Gd2O3 doped by europium (Eu) (2% to 10%) nanoplatelets using the polyol chemical method. The synthesized nanoplatelets were characterized by X-ray diffraction (XRD), FESEM, TEM, and EDX techniques. The optical properties of the synthesized nanoplatelets were investigated by photoluminescence spectroscopy. We also studied the magnetic resonance imaging (MRI) contrast enhancement of T1 relaxivity using 3 T MRI. The XRD for Gd2O3 revealed a cubic crystalline structure. The XRD of Gd2O3:Eu3+ nanoplatelets were highly consistent with Gd2O3 indicating the total incorporation of the Eu3+ ions in the Gd2O3 matrix. The Eu doping of Gd2O3 produced red luminescence around 612 nm corresponding to the radiative transitions from the Eu-excited state 5D0 to the 7F2. The photoluminescence was maximal at 5% Eu doping concentration. The stimulated CIE chromaticity coordinates were also calculated. Judd-Ofelt analysis was used to obtain the radiative properties of the sample from the emission spectra. The MRI contrast enhancement due to Gd2O3 was compared to DOTAREM commercial contrast agent at similar concentration of gadolinium oxide and provided similar contrast enhancement. The incorporation of Eu, however, decreased the MRI contrast due to replacement of gadolinium by Eu.

Formation of Eu-Doped CaF<sub>2</sub> Naonocrystals in Glass-Ceramics by Infrared Laser Irradiation

Glass-ceramic was precipitated on the oxyfluoride glass surface by thermal annealing with a CO2 laser and a heat gun. Micro x-ray diffraction showed the formation of CaF2 ain the exposed region to the laser. Dopant distribution in glass ceramics was probed by confocal fluorescence microscope by observing much strong emission from Eu ions than the glassy area under 405 nm excitation. Much enhanced visible emissions under 365 nm excitation also showed well incorporation of Eu3+ ions into a crystalline environment.

Structural, photoluminescent, and dielectric properties of Eu3+-doped Ba0.7Sr0.3TiO3 thin films

Eu3+-doped Ba0.7Sr0.3TiO3 thin films were prepared by a chemical solution deposition method and characterized by X-ray diffraction, field emission scanning electron microscopy, photoluminescence and dielectric measurements. The thin films were well crystallized with a pure perovskite structure. A contraction of the unit cell was observed upon incorporation of Eu3+ ions below 2 mol%, while an expansion occurred as the Eu3+ concentration was further increased above 2 mol%, indicating that Eu3+ ions with different concentrations occupied different lattice sites. Photoluminescence spectra showed two prominent transitions of Eu3+ ions at 594 nm (5D0 → 7F1) and 618 nm (5D0 → 7F2) upon excitation at 395 nm (7F0 → 5L6). There existed two quenching concentrations at 2 mol% and 4 mol% due to different lattice sites of the Eu3+ ions. We also investigated the dielectric properties of the thin films. Our study suggests that Eu3+-doped Ba0.7Sr0.3TiO3 thin films have potential applications in multifunctional optoelectronic devices.

Luminescence and energy transfer phenomena in YVO4 single crystal co-doped with Tm3+ and Eu3+

Detailed spectroscopic investigation of YVO4:5 at% Eu3+, 1 at % Tm3+ single crystal encompassing analysis of absorption, excitation and time resolved emission spectra recorded at 5K and 300K made it possible to determine energies, intensities and bandwidths of transitions within 4fn configurations of trivalent thulium and europium. Transients recorded upon femtosecond pulse excitation made it possible to determine dynamics of population build-up and relaxation of excited states involved in luminescence phenomena. It was found that in YVO4:Eu, Tm system the metastable 5D0 level of Eu3+ and 1G4 level of Tm3+ can be populated by energy transfer from excited VO43− group and respective intra-ion relaxation processes from higher energy levels. Recorded excitation spectra of the 5D0 luminescence of Eu3+ and of the 1G4 luminescence of Tm3+ do not evidence the Eu3+↔Tm3+ energy transfer. Nevertheless, an examination of acquired luminescence decay curves, performed with reference to available information on relaxation dynamics of YVO4:Tm3+ system, reveals that the incorporation of Eu3+ accelerates decays of the 1G4 and 3H4 levels of Tm3+. Spectroscopic parameters characterising the donor–acceptor interaction involved in the 3H4 decay were evaluated applying the Inokuti–Hirayama model. Relevance of donor and acceptor transition peculiarities for energy transfer processes contributing to the 1G4 and 3H4 decays was assessed in the framework of phenomenological model proposed by Kushida and discussed. It was concluded that the intensity ratio of the blue 1G4 luminescence to orange–red 5D0 luminescence; hence the colour of visible emission in UV-excited YVO4:Eu3+, Tm3+ phosphor, may be adjusted by appropriate choice of Eu3+ and Tm3+ concentrations.

Incorporation of Eu–Tb codoped nanophosphors in silica-based coatings assisted by atmospheric pressure plasma jet technology

Different deposition methods of nanocomposite silica films with embedded Y2O3:Eu3+, Tb3+ by atmospheric pressure plasma jet (APPJ) technology are presented. We found that a two-step strategy consisting in the APPJ deposition of a silica film on previously deposited nanophosphors is a very efficient method to obtain nanocomposite coatings with excellent adhesion to the substrate. Moreover the APPJ deposited silica film ensures protection of the luminescent nanoparticles and preserves the photoluminescence emission properties of the nanophosphors. Optically active coatings can be therefore deposited by using this technology.

Nanoparticle shape anisotropy and photoluminescence properties: Europium containing ZnO as a Model Case.

The precise control over electronic and optical properties of semiconductor (SC) materials is pivotal for a number of important applications like in optoelectronics, photocatalysis or in medicine. It is well known that the incorporation of heteroelements (doping as a classical case) is a powerful method for adjusting and enhancing the functionality of semiconductors. Independent from that, there already has been a tremendous progress regarding the synthesis of differently sized and shaped SC nanoparticles, and quantum-size effects are well documented experimentally and theoretically. Whereas size and shape control of nanoparticles work fairly well for the pure compounds, the presence of a heteroelement is problematic because the impurities interfere strongly with bottom up approaches applied for the synthesis of such particles, and effects are even stronger, when the heteroelement is aimed to be incorporated into the target lattice for chemical doping. Therefore, realizing coincident shape control of nanoparticle colloids and their doping still pose major difficulties. Due to a special mechanism of the emulsion based synthesis method presented here, involving a gelation of emulsion droplets prior to crystallization of shape-anisotropic ZnO nanoparticles, heteroelements can be effectively entrapped inside the lattice. Different nanocrystal shapes such as nanorods, -prisms, -plates, and -spheres can be obtained, determined by the use of certain emulsification agents. The degree of morphologic alterations depends on the type of incorporated heteroelement M(n+), concentration, and it seems that some shapes are more tolerant against doping than others. Focus was then set on the incorporation of Eu(3+) inside the ZnO particles, and it was shown that nanocrystal shape and aspect ratios could be adjusted while maintaining a fixed dopant level. Special PL properties could be observed implying energy transfer from ZnO excited near its band-gap (3.3 eV) to the Eu(3+) states mediated by defect luminescence of the nanoparticles. Indications for an influence of shape on photoluminescence (PL) properties were found. Finally, rod-like Eu@ZnO colloids were used as tracers to investigate their uptake into biological samples like HeLa cells. The PL was sufficient for identifying green and red emission under visible light excitation.

Europium-Doped Ba7F12Cl2, a Single Component Near-UV Excited Tunable White Phosphor

Europium-doped crystalline Ba7F12Cl2 phosphors have been prepared at temperatures between 650 and 900 °C using alkali chloride fluxes, yielding both disordered (with the incorporation of small amounts of Na) and ordered crystal modifications. The white emission spectrum excited in the near UV consists roughly of two broad emission bands at about 450 and 590 nm, as well as weak sharp Eu2+ 4f–4f emission bands around 360 nm. The incorporation of Eu2+ is further studied using EPR spectroscopy on single crystals and reveals a significant zero field splitting. The emission spectrum can be significantly tuned by varying the excitation wavelength between 300 and 390 nm. Fine tuning may also be achieved by chemical substitutions to form Ba7–xMyF12Cl2–zBrz (M = Na, Ca, Eu). Quantitative measurements of the light produced using commercial near UV LEDs show that the color temperature ranges between 4000 and 9700 K with CIE chromaticity coordinates close to the ideal values of x = y = 0.333. The best color rendering ...

Fabrication and Luminescence Properties of Transparent Glass‐Ceramics Containing Eu3+‐Doped TbPO4 Nanocrystals

Eu3+‐doped transparent phosphate precursor glasses and glass‐ceramics containing TbPO4 nanocrystals were successfully fabricated by a conventional high‐temperature melt‐quenching technique for the first time. The formation of TbPO4 nanocrystals was identified through X‐ray diffraction, transmission electron microscopy, high‐resolution transmission electron microscopy, selected‐area electron diffraction, and photoluminescence emission spectra. The obvious Stark splitting of 5D0‐7FJ (J = 1, 2, 4) transitions of Eu3+and the increase of internal quantum efficiency indicate the incorporation of Eu3+ into TbPO4 nanocrystals. Energy transfer from Tb3+ ions to Eu3+ ions was investigated using excitation and emission spectra at room temperature. The glass‐ceramics obtained have more efficient Tb3+ to Eu3+ energy transfer than the glass, and so serve as good hosts for luminescent materials.

Luminescence and crystallographic sites for Eu3+ ions in Sr5(PO4)3F phosphor

This paper reports on the luminescence studies of Eu3+-doped strontium fluoroapatite. The goal of this paper is to establish and characterize the possible sites for Eu3+ substitution in Sr5(PO4)3F lattice. Eu3+-doped Sr5(PO4)3F phosphor was prepared by the solid state reaction method. The X-ray powder diffraction result of as-synthesized powder phosphor reveals the single phase Sr5(PO4)3F and it also indicates that the incorporation of Eu3+ ions does not affect the crystal structure. Photoluminescence (PL) studies of Eu3+-doped Sr5(PO4)3F phosphor are performed to study spectral properties of the sample. Site-selective excitation and emission spectra together with the decay curves are investigated by site-selective laser-excitation spectroscopy. The three crystallographic sites for Eu3+ ions are identified in the 7F0→5D0 excitation spectra by using a pulsed, tunable, and narrowband dye laser. The luminescence due to the 5D0→7FJ (J=1, 2) transitions under excitation at each crystallographic site exhibits its own spectral features. Three crystallographic sites in Sr5(PO4)3F give rise to different crystal-field splits of the 7F1 and 7F2 multiplets. Heterovalent substitution by rare-earth ions (Eu3+) for Ca2+ positions in the hexagonal crystal lattice requires charge compensation. The charge-compensation mechanism, site symmetry, and the crystal-field strength on Eu3+ in Sr5(PO4)3F are discussed for better understanding of preferential substitution of Eu3+ in the Sr5(PO4)3F lattice.

A novel approach on the synthesis of β-SiAlON:Eu2+ phosphors from kaolin through carbothermal reduction and nitridation (CRN) route

Doping β-SiAlON crystal structure with rare earths leads to a superior tuneable luminescence properties for light emitting diodes (LEDs). However, the widely used conventional methods require high purity starting powders and time consuming processes. Here, a new approach to synthesise Eu2+ activated β-SiAlON phosphors from kaolin through carbothermal reduction and nitridation route was introduced. The Rietveld refinement on powder X-ray diffraction method and scanning electron microscopy with energy dispersive X-ray spectroscopy analyses showed that 78·28 wt-%Eu2+ doped β-Si6−zAlzOzN8−z (z = 2·1) was successfully obtained. Photoluminescence examinations under the 267 nm excitation revealed two distinct broad emission peaks: maxima at around 415 nm (violet) and 540 nm (green). Transmission electron microscopy observations demonstrated the incorporation of Eu2+ ions into β-SiAlON grains giving the observed violet and green emissions. It is anticipated that this study paves a way for cost effective synthesis of rare earth doped single phase β-SiAlON phosphors in LED applications.

Highly Luminescent Colloidal Eu3+‐Doped KZnF3 Nanoparticles for the Selective and Sensitive Detection of CuII Ions

This article describes a green synthetic approach to prepare water dispersible perovskite-type Eu3+-doped KZnF3 nanoparticles, carried out using environmentally friendly microwave irradiation at low temperature (85 8C) with water as a solvent. Incorporation of Eu3+ ions into the KZnF3 matrix is confirmed by strong red emission upon ultraviolet (UV) excitation of the nanoparticles. The nanoparticles are coated with poly(acrylic acid) (PAA), which enhances the dispersibility of the nanoparticles in hydrophilic solvents. The strong red emission from Eu3+ ions is selectively quenched upon addition of CuII ions, thus making the nanoparticles a potential CuII sensing material. This sensing ability is highly reversible by the addition of ethylenediaminetetraacetic acid (EDTA), with recovery of almost 90% of the luminescence. If the nanoparticles are strongly attached to a positively charged surface, dipping the surface in a CuII solution leads to the quenching of Eu3+ luminescence, which can be recovered after dipping in an EDTA solution. This process can be repeated for more than five cycles with only a slight decrease in the sensing ability. In addition to sensing, the strong luminescence from Eu3+-doped KZnF3 nanoparticles could be used as a tool for bioimaging.

Functionalization of Sol-Gel Zirconia Composites with Europium Complexes

Different sol-gel strategies based on functionalization of ZrO2:Eu microparticles with 1,10- phenanthroline (phen) and incorporation of colloidal Eu(phen)2(NO3)3 into zirconia have been used to obtain hybrid sol-gel composites with controlled optical properties. The process leads to materials with quantum yields of about 48% monitoring the 615 nm emission line at 350 nm excitation. Excitation/ luminescence spectroscopy, diffuse reflectance spectroscopy and X-ray diffraction have been used to characterize the hybrid zirconia composites.

Lamellar Salt-Doped Hybrids with Two Reversible Order/Disorder Phase Transitions

A lamellar bilayer hierarchically structured amide cross-linked alkyl/siloxane hybrid matrix (mono-amidosil, m-A(14)) was doped with a wide concentration range of potassium triflate (KCF3SO3), magnesium triflate (Mg(CF3SO3)2), and europium triflate (Eu(CF3SO3)3). In the K(+)-, Mg(2+)-, and Eu(3+)-based samples with n ≥ 5, 20, and 60 (where n is the molar ratio of amide C═O groups per cation), respectively, the original lamellar structure of m-A(14) coexists with a new lamellar phase with lower interlamellar distance. The texture of the mono-amidosils doped with K(+), Mg(2+), and Eu(3+) ions mimics cabbage leaves, foliated schist, and sea sponges, respectively. In the three series of materials, the cations bond to the oxygen atoms of the amide carbonyl groups. The amide-amide hydrogen-bonded array of m-A(14) is less perturbed by the inclusion of KCF3SO3 and Mg(CF3SO3)2 than by the incorporation of Eu(CF3SO3)3. The degree of ionic association is low for n ≥ 20. The cations coordinate to the oxygen atoms of the triflate ions, forming contact ion pairs at higher salt content. In the Mg(CF3SO3)2- and Eu(CF3SO3)3-containing materials with n = 5 and 10, respectively, crystalline salt is formed. The structural changes undergone by the alkyl chains of selected mono-amidosils in a heating/cooling cycle are reversible, are time-independent, and exhibit two distinct hysteresis domains, one associated with the order/disorder phase transition of the original lamellar bilayer structure of m-A(14) and the second one associated with the order/disorder phase transition of the new lamellar bilayer structure formed in the presence of the salts.

Electro-optical properties of the DNA-Eu3+ bio-membranes

Biopolymer-based materials have particular interest and they are alternatives to synthetic polymers based on the decreasing oil resources. In this report they may be viewed as innovative materials for optics area. The incorporation of Eu3+ into natural macromolecules hosts with purpose of producing highly efficient emitting phosphors is of widespread interest in materials science, due to their important roles in display devices. This paper describes studies of the DNA and europium triflate luminescent membranes and its potential technological applications are expanded to electroluminescent devices. The most conductive sample of DNA50Eu, exhibited an ionic conductivity equal to 1.02×10−4Scm−1 and 1.55×10−3Scm−1 at 25°C and 90°C, respectively. Techniques like DSC, XRD and POM, demonstrated that the inclusion of the guest salt does not change significantly the amorphous nature morphology of the samples. Moreover, the overall redox stability of 2.0V was an indication that this material has an acceptable stability window for an application in a solid state electrochemical devices.

Origin of saturated green emission from europium in zinc thiogallate

Europium doped zinc thiogallate, ZnGa2S4:Eu2+, has been reported as a saturated green emitting phosphor, suitable as conversion phosphor in white LEDs for lighting or displays. Up to now, no direct proof for the incorporation of Eu2+ in ZnGa2S4 has been given. We combined X-ray diffraction (XRD), cathodoluminescence in electron microscopy (SEM-CL) and X-ray absorption spectroscopy (XAS) to study the incorporation of the europium ions in the host material. The previously reported green luminescence was found to originate from small amounts of unintentionally formed EuGa2S4, and not from europium ions incorporated into ZnGa2S4. EuGa2S4 has a low quantum efficiency (< 20%) and shows strong thermal quenching, already below room temperature. The XAS data analysis suggests that a certain amount of europium might occupy octahedral voids inside the zinc thiogallate lattice in a divalent state. The zinc ion next to these interstitial dopants is then removed for charge compensation. Notwithstanding the possible, but limited, incorporation of Eu2+ in ZnGa2S4, these ions do not activate any luminescence as was shown with SEM-CL.

Eu-doped ZnO nanowire arrays grown by electrodeposition

The preparation of efficient light emitting diodes requires active optical layers working at low voltage for light emission. Trivalent lanthanide doped wide-bandgap semiconducting oxide nanostructures are promising active materials in opto-electronic devices. In this work we report on the electrochemical deposition (ECD) of Eu-doped ZnO (ZnO:Eu) nanowire arrays on glass substrates coated with F-doped polycrystalline SnO2. The structural, chemical and optical properties of ZnO:Eu nanowires have been systematically characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and photoluminescence. XRD results suggest the substitution of Zn2+ by Eu ions in the crystalline lattice. High-resolution TEM and associated electron diffraction studies indicate an interplanar spacing of 0.52nm which corresponds to the (0001) crystal plane of the hexagonal ZnO, and a growth along the c-direction. The ZnO:Eu nanowires have a single crystal structure, without noticeable defects. According to EDX, SIMS and XPS studies, cationic Eu species are detected in these samples showing the incorporation of Eu into the ZnO matrix. The oxidation states of europium ions in the nanowires are determined as +3 (74%) and +2 (26%). Photoluminescence studies demonstrated red emission from the Eu-doped ZnO nanowire arrays. When Eu was incorporated during the nanowire growth, the sharp 5D0–7F2 transition of the Eu3+ ion at around 612nm was observed. These results suggest that Eu doped ZnO nanowires could pave the way for efficient, multispectral LEDs and optical devices.