Eu Nanophosphors Research Articles

The experiments for obtaining Huang-Rhys factor and energy transfer rate of Gd2(WO4)3:Eu nanophosphor

In this paper, Gd2(WO4)3:Eu nanophosphors with different Eu3+ concentrations were synthesized through co-precipitation. The crystal structure and morphology of the nanophosphors were characterized by means of XRD and field emission scanning electron microscopy. Emission and excitation spectra (phonon sideband spectra) of each sample were measured, and concentration quenching curves were also drawn. The optimal doping concentration was confirmed to be 20 mol%. Huang-Rhys factor for each sample of different doping concentration was calculated by the phonon sideband spectra. Fluorescence lifetimes of the samples with different Eu3+ doping concentrations were measured. By fitting the fluorescence lifetime data of Eu3+ 5D0 level within the Auzel's model, the intrinsic lifetime for 5D0 level was determined and the generated phonon number in the quenching process was measured. The energy transfer rate of Eu3+ was derived from the fluorescence lifetime data, and the relationship between the energy transfer rate and the concentration was also given.

Luminescent GdVO4:Eu3+ functionalized mesoporous silica nanoparticles for magnetic resonance imaging and drug delivery

Luminescent GdVO4:Eu(3+) nanophosphor functionalized mesoporous silica nanoparticles (MSN) were prepared (denoted as GdVO4:Eu(3+)@MSN). The in vitro cytotoxicity tests show that the sample has good biocompatibility, which indicates that the nanocomposite could be a promising candidate for drug delivery. Flow cytometry and confocal laser scanning microscopy (CLSM) confirm that the sample can be effectively taken up by SKOV3 ovarian cancer cells and A549 lung adenocarcinoma cells. It was also shown that the GdVO4:Eu(3+)@MSN brightened the T1-weighted images and enhanced the r1 relaxivity of water protons, which suggested that they could act as T1 contrast agents for magnetic resonance (MR) imaging. It was found that the carriers present a pH-dependent drug release behavior for doxorubicin (DOX). The composites show a red emission under UV irradiation due to the GdVO4:Eu(3+) nanophosphors. Furthermore, the PL intensity of the composite shows correlation with the cumulative release of DOX. These results suggest that the composite can potentially act as a multifunctional drug carrier system with luminescent tagging, MR imaging and pH-controlled release property for DOX.

Effects of Dy concentration on luminescent properties of SrAl2O4: Eu phosphors

SrAl2O4: Eu is a member of family of long lasting phosphors (LLP) and is useful as a luminescent material which emits green light. It is a promising candidate for detecting an element for a visible display of two dimensional radiation distributions. We have investigated effects of Dy doping on optical and structural properties of SrAl2O4: Eu nano phosphors prepared by combustion synthesis technique (CST). The obtained specimens are thoroughly characterized paying particular attention to their structure, composition, morphology and optical properties. The optical properties are presented and discussed in terms of photoluminescence (PL) and electroluminescence (EL). The PL spectra (under the excitation of 365nm) of SrAl2O4: Eu samples with varied concentrations of Dy have wide peaks in visible region, which are attributed mainly to transitions of Eu2+. With increasing concentration of Dy a slight increase in peak intensities is noticed and at a particular concentration intensity gets saturated owing to concentration quenching. The surface morphology and structural properties of SrAl2O4: Eu, Dy phosphors are studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The average grain size as calculated using SEM and XRD results lies in nano range.

Tuning of size and luminescence of red Y(V,P)O4:Eu nanophosphors for their application to transparent panels of plasma display

Fabrication of transparent plasma display can be demonstrated by simply applying the scatter-less nanophosphors to the currently available plasma display panel (PDP) scheme. For this goal, the optimization of the nanophosphors with respect to size and luminescence is necessary to produce a uniform, transparent, bright emissive layer. To develop red-emitting nanophosphors suitable for transparent PDP fabrication, we hydrothermally synthesized red-emitting Y(V,P)O4:Eu nanophosphors having various V/P ratios and Eu concentrations and varied their subsequent annealing condition. When Y0.94(V0.5,P0.5)O4:Eu0.06 nanophosphor annealed at 1000 °C for 1 h was used, 1.1 μm thick, uniform emissive layer with a high visible transmittance value of 72% was generated on glass substrate by a conventional screen-printing. Mini-sized test panels of transparent red-emitting plasma display were constructed by combining the rear plate (Y(V,P)O4:Eu nanophosphor layer/glass) and the front plate used in alternating current (ac)-type PDP structure, and their discharge luminance characteristics were evaluated.

Molten Salt Synthesis and Luminescent Properties of YNbO<SUB>4</SUB>: Eu Nanophosphors

Molten Salt Synthesis and Luminescent Properties of YNbO<SUB>4</SUB>: Eu Nanophosphors

Effects of crystallization and dopant concentration on the emission behavior of TiO2:Eu nanophosphors

Uniform, spherical-shaped TiO2:Eu nanoparticles with different doping concentrations have been synthesized through controlled hydrolysis of titanium tetrabutoxide under appropriate pH and temperature in the presence of EuCl3·6H2O. Through air annealing at 500°C for 2 h, the amorphous, as-grown nanoparticles could be converted to a pure anatase phase. The morphology, structural, and optical properties of the annealed nanostructures were studied using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy [EDS], and UV-Visible diffuse reflectance spectroscopy techniques. Optoelectronic behaviors of the nanostructures were studied using micro-Raman and photoluminescence [PL] spectroscopies at room temperature. EDS results confirmed a systematic increase of Eu content in the as-prepared samples with the increase of nominal europium content in the reaction solution. With the increasing dopant concentration, crystallinity and crystallite size of the titania particles decreased gradually. Incorporation of europium in the titania particles induced a structural deformation and a blueshift of their absorption edge. While the room-temperature PL emission of the as-grown samples is dominated by the 5D0 - 7Fj transition of Eu+3 ions, the emission intensity reduced drastically after thermal annealing due to outwards segregation of dopant ions.

One-pot solvothermal synthesis of uniform layer-by-layer self-assembled ultrathin hexagonal Gd2O2S nanoplates and luminescent properties from single doped Eu3+ and codoped Er3+, Yb3+

Uniform Gd(2)O(2)S flower-like nano-assemblies were prepared through one-pot mild solvothermal synthesis. The parallel nanoplates are the building blocks, ∼3 nm in thickness and 20-30 in diameter. Ethanediamine, the main solvent, plays an important role in dissolving a large amount of sulphur and producing active S(2-) ions, which results in the direct formation of Gd(2)O(2)S. Oleylamine, the capping agent, controls the growth of the plate-like structure. Under UV excitation, the Gd(2)O(2)S:Eu(3+) nano-phosphor shows good red luminescence with a main emission peak at 627 nm. Under 980 nm laser excitation, Gd(2)O(2)S:xYb(3+),1%Er(3+) nano-phosphors exhibit a tuneable emission, shifting from greenish-yellow to orange-yellow, with increasing Yb(3+) content.

Thermoluminescence and Mechanoluminescence of Eu Doped Y2O3 Nanophosphors

Abstract Thermoluminescence and Mechanoluminescence phenomenon of Y2O3: Eu nanophosphor prepared by combustion method has reported.XRD; Optical absorption spectra have also studied. TL emission spectra show intense peak around 600 nm.

Synthesis and Luminescent Properties of M2V2O7: Eu (M=Sr, Ba) Nanophosphors

A solution combustion route for the synthesis of Eu(3+)-activated M(2)V(2)O(7) (M = Sr, Ba) and their luminescent properties have been investigated. Structure and luminescent characteristics of Sr(2)V(2)O(7):Eu(3+) and Ba(2)V(2)O(7):Eu(3+) nanophosphors have been studied by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrometry and Fourier transform infra-red spectroscopy. The incorporation of Eu(3+) activator in these nanoparticles has been checked by luminescence characteristics. These nanoparticles have displayed red color under a UV source which is due to characteristics transition of Eu(3+) from (5)D(0) → (7)F(2) at 613 nm in both Sr(2)V(2)O(7):Eu(3+) and Ba(2)V(2)O(7):Eu(3+) nanophosphors. In addition, the optimal Eu(3+) - doped contents of Sr(2(1-x))Eu(2x)V(2)O(7) and Ba(2(1-x))Eu(2x)V(2)O(7) nanophosphors for both were 4 mol%.

Preparation and Photoluminescence of GdVO4:Eu Nanophosphors for Flexible and Transparent Displays

:Eu phosphors aregenerally prepared by high-temperature solid-state reactions.However, these micron-sized phosphors cannot be used inflexible and transparent displays due to their high scattering.Because nano-sized materials do not show any scattering inthe visible region, inorganic nanophosphors have receivedmuch attention for their applicability in flexible andtransparent display devices.

Studying the luminescence efficiency of Lu2O3:Eu nanophosphor material for digital X-ray imaging applications

Scintillator materials are widely used in X-ray medical imaging detector applications, coupled with available photoreceptors like radiographic film or photoreceptors suitable for digital imaging like a-Si, charge-coupled devises (CCD), complementary metal-oxide-semiconductors (CMOS) and GaAs). In addition, scintillators can be utilized in non-medical imaging detectors such as industrial detectors for non-destructive testing (NDT) and detectors used for security purposes (i.e. airport luggage control). Image quality and dose burden in the above applications is associated with the amount of optical photons escaping the scintillator as well as the amount of optical photons captured by the photoreceptor. The former is characterized by the scintillator efficiency and the latter by the spectral matching between the emission spectrum of the scintillator and the spectral response of the photoreceptor. Recently, a scintillator material, europium-activated lutetium oxide (Lu2O3:Eu), has shown improved scintillating properties. Lu2O3:Eu samples of compact nanocrystalline non-agglomerated powder were developed in our laboratory using homogeneous precipitation from a water-toluene solution in the presence of polyvinyl alcohol as a surfactant. In order to test their light-emission properties, experimental measurements under the excitation of X-ray spectra with X-ray tube voltages between 50 kVp and 140 kVp were performed. This range of applied voltages is appropriate for X-ray radiology, NDT and security applications. Lu2O3:Eu was evaluated with respect to output yield and spectral compatibility of digital imaging photoreceptors (CCD-based, CMOS-based, amorphous silicon a:Si flat panels, ES20 and GaAs). High light yield and spectral compatibility increase the performance of the medical detector and reduce the dose burden to the personnel involved. In addition a theoretical model was used to determine the values for the Lu2O3:Eu optical photon light propagation parameters. The inverse diffusion length was found to be equal to 33 cm2/g. In addition Lu2O3:Eu was found to match well with several photoreceptors capable of digital imaging (i.e. GaAs).

Study on Luminescent Properties of Eu3+ Doped New Type Yttrium Tungsten Oxide Nanophosphors

In this paper, a novel nanophosphor, Y10W2O21:Eu, was synthesized through co-precipitation which is a simple and low-costing method. The structure and morphology of the nanocrystal samples were characterized by using XRD and FE-SEM. The emission spectra, excitation spectra and fluorescence decay curves were measured. J-O parameters, quantum efficiencies of Eu3+ 5D0 energy level, color coordinates and Huang-Rhys factor of Y10W2O21:Eu nanophosphors were calculated. The results indicate that EU3+ 5D0-7F2 red luminescence at 610 nm can be effectively excited by 394 nm near-UV light and 464 nm blue light in Y10W2O21 host, which is similar to the familiar Eu3+ doped tungstate phosphors (e.g., Gd2(WO4)3:Eu, CaWO4:Eu). Besides, compared with the other types of tungstate phosphors, a less expensive tungsten was used, which can effectively reduce cost. Therefore, the Y10W2O21:Eu red nanophosphors may have a potential application for white LED.

LaPO4:Ce,Tb and YVO4:Eu nanophosphors: Luminescence studies in the vacuum ultraviolet spectral range

Comparative analysis of the luminescent properties of nanocrystalline LaPO4:Ce,Tb and YVO4:Eu luminescent materials with macrocrystalline analogues, commercially produced by Philips, has been performed under excitation by pulsed vacuum ultraviolet (VUV) synchrotron radiation, ranging from 3.7-40 eV. Special attention was paid to VUV spectral range, which is not reachable with commonly used lamp and laser sources. Our results clearly show distinct difference in the excitation spectra for nano- and macrocrystalline samples, especially at energies, when the spatial separation of electron-hole pairs is comparable with sizes of nanoparticles. Differences in the region of multiplication of the electronic excitations are also demonstrated and discussed.

Correlation between ion induced defects and luminescence properties of K3Na(SO4)2: Eu nanophosphor

Abstract The K 3 Na(SO 4 ) 2 : Eu phosphor has been prepared by chemical co-precipitation method. X-ray diffraction studies show that K 3 Na(SO 4 ) 2 : Eu phosphor exhibits hexagonal structure with average particle size of 42 nm. The samples were irradiated with 1.2 MeV Argon ions, with fluences varying between 10 11 and 10 15 ions/cm 2 . Monte Carlo SRIM-2008 Simulation was used for evaluating ion range, ion energy loss and ion induced atomic displacements. Ions having a range of 2.09 μm lose their energy mainly via electronic stopping, by creating large number of defects and activating different trap centers. This results in composite thermoluminescence (TL) glow curves. The growth of lower temperature peak at around 449 K which was linear in the whole studied dose range, might be attributed to the change in trap centers and luminescence centers populations. The observed variation in TL intensity of the higher temperature peak at 533 K is the resultant effect of both increases in density of ion beam tracks and high ionization density. A photoluminescence (PL) emission peak is seen around 415 nm when excited by 310 nm light, due to transition from an excited state of 4f 6 5d configuration to 8 S 7/2 state of Eu 2+ ion. The higher concentration of defects that generate nonradiative states within the band gap is responsible for decrease in PL intensity after irradiation. The composite TL glow peaks were first deconvoluted with GlowFit program and then kinetics parameters of isolated prominent peaks were calculated by the thermoluminescence peak shape and various heating rate methods.

적색발광 Y(V0.5,P0.5)O4:Eu 나노형광체의 수열 합성 및 투명 플라즈마 디스플레이 소자 제작으로의 응용

Transparent plasma display can be realized by developing the synthetic chemistry of appropriate nanophosphors and generatingnanophosphor-based transparent luminescent layers. For this goal, red-emitting Y(V 0.5 , P 0.5 )O₄:Eu nanophosphors were synthesized bya facile hydrothermal route at 200℃ for 48 h and the resulting nanophosphors were subsequently annealed at 800℃ at an ambientatmosphere. The crystallographic structure, morphology, and emission property of the as-synthesized and annealed nanophosphorswere compared. Choosing 2-methoxyethanol as a dispersion medium and applying a standard sonication, well-dispersed nanophosphorsolutions could be prepared. Using these dispersions, visible transparent nanophosphor layers were spin-deposited on glass substrates.By combining Y(V 0.5 , P 0.5 )O₄:Eu nanophosphor layer/glass substrate as a rear plate with a front plate used in a conventional plasmadisplay panels (PDPs), mini-sized transparent red-emitting PDPs were constructed. Transmittance and luminance properties of twotransparent test panels using as-synthesized versus 800℃-annealed nanophosphors were characterized and compared.

Photoluminescence Properties of YVO4: Eu Nanophosphors Prepared by the Hydrothermal Reaction

:Eu phosphors prepared by the hydrothermal reaction of the emulsion followed by calcination had an average size of 800 nm, as shown in Figure 6(b).In general, the photoluminescence intensity increased with increasing phosphor size due to a decrease in the surface area to phosphor volume ratio because surface defects produced nonradiative recombination processes between electrons and holes. However, the emission intensities of the 800 nm YVO

Flame aerosol deposition of Y2O3:Eu nanophosphor screens and their photoluminescent performance

Screens of Y2O3:Eu3 + -nanophosphor (dBET = 24 nm) with coating densities in the range 0.23–3.8 mg cm − 2 were obtainedby flame aerosol deposition (FAD) from nitrate-based precursors. The average deposition rate was 0.22 mg cm − 2 min − 1. Porosity of theobtained deposits was 0.973 ± 0.004. Light scattering of the coatings in the visible range showed a Rayleigh-like dependence on wavelengthand, in comparison to the screens made of the commercial micrometer-sized phosphor powder (dSEM = 4 µm), was reduced by up to two orders of magnitude. As a result, the nanophosphor coatingsmaintained nearly constant brightness in a very wide range of coating densities. Furthermore, itshould be expected that a substantially improved screen resolution can be achieved with suchscreens. For excitation at a wavelength of 254 nm, the maximum brightness of the FAD-deposited(Y0.92Eu0.08)2O3 phosphor screens in the transmission mode was nearly one third of that of the screens madeof the commercial phosphor. It was demonstrated that light reflection from the supportingsubstrate and porosity of the coating significantly influence its photoluminescentperformance.

Study on Fabrication and Photoluminescent Properties of Fine Phosphor Film for Application of Radiation Image Sensor

In this paper, the fabrication and feasibility study of clinical application with euripium doped gadollium oxide (:Eu) nano phosphor derived by low-temperature solution combustion method. From the fabricated phosphor, the photoluminescent characteristic and linearity as a function of phosphor film thickness were investigated to evaluate x-ray converstion properties. From the experimental results, the luminescent intensity was -mR at :Eu film and this value is higher 1.2 time the conventional bulk phosphor, which is possible to imaging acquisition. And good linearity was shown at x-ray exposure range for clinical diagnostic application.

Production of nanocrystalline Y 2O 3:Eu powder by microwave plasma-torch and its characterization

Y 2O 3:Eu red-emitting nanophosphors were synthesized directly by dissolving Y 2O 3 and Eu 2O 3 in HNO 3 and by using an atmospheric microwave-plasma torch for a direct continuous preparation and for mass production of Y 2O 3:Eu powders. Atmospheric microwave plasmas produce a high-temperature plasma flame due to ohmic heating by high frequency electric fields, revealing a maximum central temperature of 6500 ± 350 K. Therefore, the synthesized Y 2O 3:Eu nanophosphors from instantaneous evaporation of dissolved Y 2O 3 and Eu 2O 3 in HNO 3 have favorable characteristics such as regular size and cubic equilibrium structure. The nanophosphors were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL).

Nanoparticles of K2Ca2(SO4)3:Eu as effective detectors for swift heavy ions

The modification of thermoluminescence (TL) and photoluminescence (PL) properties of K2Ca2(SO4)3:Eu nanoparticles by swift heavy ions (SHI), irradiation is studied. Pellets form of the nanomaterials were irradiated by 48 MeV Li3+, 75 MeV C6+, and 90 MeV O7+ ion beams. The fluence range is 1×109−1×1013 ions/cm2. The modification in TL glow curves of the nanomaterials irradiated by Li3+, C6+, and O7+ ion beams are essentially similar to those induced by γ-ray irradiation. These glow curves have single peaks at around 427 K with a small variation in their positions by around ±3 K. The TL intensity of the ion beams irradiated nanomaterials is found to decease, while going from low to high atomic number (Z) ions (i.e., Li3+→O7+). The TL response curve of the pellets irradiated by Li3+ ions is linear in the whole range of studied fluences. The curves for C6+ and O7+ irradiated samples are linear at lower fluences (1×109–1×1012 ion/cm2) and then saturate at higher fluence. These results for the nanomaterials are much better than that of the corresponding microcrystalline samples irradiated with a Li3+ ion. The curves were linear up to the fluence 1×1011 ion/cm2 and then become sublinear at higher fluences. The TL efficiency values of K2Ca2(SO4)3:Eu nanoparticles irradiated by 48 MeV Li3+, 75 MeV C6+, and 90 MeV O7+ ion beams have been measured relative to γ rays of C60o and are found to be 0.515, 0.069, and 0.019, respectively. This value for the Li3+ ion (0.515) is much higher than that of the corresponding microcrystalline material (0.0014). These superiorities for the nanomaterials make K2Ca2(SO4)3:Eu nanophosphor a suitable candidate for detecting the doses of swift heavy ions. PL studies on the ion beams irradiated and unirradiated K2Ca2(SO4)3:Eu nanoparticles show a single band at 384 nm, which could be assigned to Eu2+ emission, while the microcrystalline form of this material shows emission at 436 nm. This wide blueshift in PL of the nanomaterial could be attributed to the extension of the band gap of Eu2+ due to the absence of crystal field effects.