Eu 3+ /Tb 3+ -codoped Y 2 O 3 nanophosphors: Rietveld refinement, bandgap and photoluminescence optimization (original) (raw)
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Structural and photoluminescence studies of Eu 3 þ doped cubic Y 2 O 3 nanophosphors
Structural and photoluminescence properties of undoped and Eu 3 þ doped yttrium oxide (Y 2 O 3 :Eu 3 þ ) nanoparticles heat-treated at 600 and 900 1C were reported. Three concentrations of Eu 3 þ (1, 3 and 5 mol%) were doped in Y 2 O 3 . The heat-treated Y 2 O 3 :Eu 3 þ nanoparticles were cubic in structure without any impurity phase as studied by X-ray diffraction and transmission electron microscopy. The samples showed high crystallinity and average particle size was in the range of 10-16 nm and 20-25 nm when annealed at 600 and 900 1C respectively. The 900 1C annealed Y 2 O 3 :Eu 3 þ exhibited a strong red photoluminescence due to homogeneously occupied Eu 3 þ ions in the Y 2 O 3 lattice and high crystallinity. The PL lifetime decreases with the dopant concentration from of 2.26 to 1.77 ms and from 2.35 to 1.81 ms in the case of 600 and 900 1C annealing respectively. Emission becomes faster with higher loading of Eu 3 þ . Strong photoluminescence characteristics at most commonly available UV-blue excitation wavelengths make these phosphors suitable for LEDs and other display applications.
2015
Y2O3:Eu nanophosphors are prepared from different synthesis viz. Combustion synthesis, Precipitation Method, Sol-Gel. The samples are annealed from 600-14000C temperature. Effect of Temperature on luminescence intensity of Europium Doped Y2O3 phosphor prepared from different synthesisroutes is studied in the presented paper. Prepared samples are found to have monoclinic structure when compared with JCPDS standard data. The luminescence intensity increases with the increase of particle size and is affected by synthesis route. Eu doped Y2O3 particle shows sharp emission at 611nm at UV excitation. The samples are excited with different UV wavelength and maximum emission intensity is found when excited with 234nm wavelength. Powder X-Ray Diffraction (XRD) results indicated that high temperature leads to increase in the particle size. TEM photographs show the agglomeration of the samples at higher temperature.
Luminescence : the journal of biological and chemical luminescence, 2015
Europium trivalent (Eu(3+) )-doped Y2 O3 nanopowders of different concentrations (0.5, 2.5, 5 or 7 at.%) were synthesized by the sol-gel method, at different pH values (pH 2, 5 or 8) and annealing temperatures (600°C, 800°C or 1000°C). The nanopowders samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and steady state photoluminescence spectroscopy. The effect of pH of solution and annealing temperatures on structural, morphological and photoluminescence properties of Eu(3+) -doped Y2 O3 were studied and are discussed. It was found that the average crystallite size of the nanopowders increased with increasing pH and annealing temperature values. The Y2 O3 :Eu(3+) material presented different morphology and its evolution depended on the pH value and the annealing temperature. Activation energies at different pH values were determined and are discussed. Under ultraviolet (UV) ligh...
Structure and Luminescence Properties of Y\(_2\)O\(_3\): Eu\(^{3+}\) Nanophosphors
Journal of Atomic, Molecular, Condensate and Nano Physics
Europium trivalent (Eu 3+ , 2%) doped Y 2 O 3 nanophosphors were synthesized by solgel method and annealed at temperature 600 • C and 900 • C. The phosphors were characterized by XRD, FTIR, UV-visible and PL spectroscopy. The average crystal size was in the range of 10-26 nm. FTIR spectra show that the intensities of all impurity peaks get reduce with increasing annealing temperature. The band gap was determined from the diffuse reflectance (DR) spectra using the K-M function. The photoluminescence spectra were describe by well known 5 D 0-7 F j transitions (J = 0, 1, 2, 3, 4) of Eu 3+ ions.
Journal of Luminescence, 2007
Eu-doped Y2O3 nanophosphors were prepared using combustion synthesis. In this method, urea was employed as a fuel. The particle size was estimated to be in the range of 10–20 nm as determined by X-ray diffractometry and transmission electron microscopy. The photoluminescent and cathodoluminescent spectra are described by the well-known 5D0→7FJ transition (J=0, 1, 2, etc.) of Eu3+ ions with the strongest emission for J=2. The optical properties of nanophosphors were compared with commercial with an order of micrometer size. The effects of urea-to-metal nitrate molar ratio and the other synthesis conditions on the particle size and luminescent properties will be discussed in detail. The red emission of Eu-doped Y2O3 nanophosphors is promising materials not only in high-resolution screen but also in telecomunication as well as in biosensor.
Journal of Fluorescence, 2013
This paper reports the structural and optical properties of rare earth doped and codoped yttrium oxide nanophosphors. Dysprosium (Dy 3+) and Terbium (Tb 3+) doped and codoped yttrium oxide (Y 2 O 3) phosphors were prepared by combustion synthesis method and subsequently annealed to high temperature to eliminate the hydroxyl group (−OH) and to get more crystallinity. The formation of compounds was confirmed by the X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR). The diffuse reflectance spectra (DRS) of doped and codoped Y 2 O 3 powder phosphors were measured and it is observed that the absorption edge of the doped samples is shifted towards blue region with respect to undoped sample. The bandgap of the prepared samples were evaluated with the help of Kubelka-Munk function using Diffuse Reflectance Spectra (DRS) and an increase in bandgap was observed with the decrease in crystallite size. A strong characteristics emission from Tb 3+ and Dy 3+ ions was identified and the influence of doping concentration and annealing temperature on photoluminescence properties was systematically studied. Transfer of energy was observed in dysprosium-terbium codoped Y 2 O 3 nanophosphor at room temperature from Dy 3+ ions toTb 3+ ions.
Photoluminescence Efficiencies of Nanocrystalline versus Bulk Y2O3:Eu Phosphor—Revisited
Highly efficient yttrium oxide doped with trivalent europium (Y 2 O 3 :Eu) phosphor was prepared through precursors synthesized by hydrothermal method. Crystalline precursors, namely europium-doped yttrium carbonate (Y 2 (CO 3 ) 3 . 2H 2 O:Eu) and europium-doped yttrium hydroxy carbonate (Y(OH)CO 3 :Eu), were prepared by varying the concentration of yttrium to europium ions and urea in the reaction mixture. The precursor materials on annealing at 7001C gave nanocrystalline Y 2 O 3 :Eu, which was further processed at high temperatures in the absence and presence of sintering aid to yield phosphor materials with varying crystallite size and morphology. The precursors and phosphor material were characterized using FTIR, TGA, powder XRD, SEM, TEM, and photoluminescence (PL) spectral studies. The emission efficiency was found to depend on the crystallite size, morphology, and particle size of the phosphor materials. It was observed that phosphor material with spherical morphology and particle size of 0.5-1.0 lm with crystallite size of 100 nm has the highest PL efficiency.
In this work, thermally stable Y2O3:Eu3+ nanophosphors by organic mediated combustion technique using dilute citric acid / citric acid mixed with diethylene glycol as fuel was prepared. The structural analysis establishes that these oxides crystallize into body-centered cubic structure with a space group la3. The nanophosphor prepared by citric acid with diethylene glycol as fuel exhibits better surface morphology and enhanced photoemission. The addition of polymeric precursors greatly enhanced the photoluminescence intensity of Y2O3: Eu phosphor by reducing the surface defects via the morphological control and improvement of crystallite growth. Investigations on temperature dependent photoluminescence studies reveal that the materials are thermally stable and the respective activation energy was 0.130 and 0.143 eV. The nanophosphor, fueled with diethylene glycol, exhibit remarkable CIE chromaticity coordinates (0.655, 0.345),in agreement with the National Television System Committe...
Luminescence studies of europium doped yttrium oxide nano phosphor
Sensors and Actuators B: Chemical, 2012
Luminescence exhibiting europium doped yttrium oxide (Y 2 O 3 :Eu 3+) phosphor was prepared by solution combustion method, using disodium ethylene diamine tetra acetic acid (EDTA-Na 2) as fuel at ∼350 • C. Powder X-ray diffraction (PXRD) pattern of Y 2 O 3 :Eu 3+ revealed the cubic crystalline phase. The morphology of the samples was studied by scanning electron microscopy (SEM) and was foamy, fluffy and porous in nature. Fourier transformed infrared spectroscopy (FTIR) revealed prominent absorption with peaks at 3415, 1435, 875 and 565 cm −1. Optical absorption studies showed the energy gap of the synthesized samples to be 5.4-5.5 eV. The photoluminescence (PL) of Y 2 O 3 :Eu 3+ exhibiting emission peak at 611 nm under the excitation of 254 nm. Thermoluminescence of ␥-irradiated Y 2 O 3 :Eu 3+ showed two well resolved TL glows with peaks at 460 and 610 K and they were analyzed by glow curve shape method and the activation energies were found to be 0.421 eV and 1.016 eV respectively.
Optical Materials, 2014
Nano-sized yttria (Y 2 O 3 ) doped with Eu 3+ powders were successfully synthesized by co-precipitation method, where the quenching concentration for photoluminescence study of Eu 3+ ions is 12 mol% which is much higher than the micro-scaled powders. The effect of changing concentration of co-dopants (Li + , Na + and K + ) along with Eu 3+ (12 mol%) is studied on optical properties of Y 2 O 3 nanoparticles. The results showed that the incorporation of these metal ions can further improve the luminescence intensity. The highest emission intensity was observed with 6 mol% of Li + , 2 mol% of Na + , and 1 mol% of K + doping in Y 2 O 3 :Eu 3+ (12 mol%) nanoparticles given by the formula (Y 0.82mol% Eu 0.12mol% Li 0.06mol% ) 2 O 3 , (Y 0.86mol%-Eu 0.12mol% Na 0.02mol% ) 2 O 3 , and (Y 0.87mol% Eu 0.12mol% K 0.01mol% ) 2 O 3 respectively. The structural, morphological and optical properties were studied by X-ray diffraction, Rietveld refinement, transmission electron microscopy, Fourier transform infrared spectroscopy, and Photoluminescence spectroscopy. XRD studies followed by Rietveld refinement confirmed the body-centered cubic structure of doped nanophosphors. All the powders were well crystallized and the emission intensity was observed to increase further from quenching concentration of Eu 12 mol% with co-doped samples.