Photoluminescence Efficiencies of Nanocrystalline versus Bulk Y2O3:Eu Phosphor—Revisited (original) (raw)
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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.
Research on Chemical Intermediates, 2014
The present paper reports the synthesis, photoluminescence (PL), and thermoluminescence (TL) studies of Eu 3?-doped yttrium oxide (Y 2 O 3) phosphor using inorganic materials like Y 2 O 3 , flux calcium fluoride, and europium oxide. The sample was prepared by the modified solid state reaction method, which is the most suitable for large-scale production. The prepared phosphor sample was characterized using powder X-ray diffraction, field emission gun scanning electron microscopy, high resolution transmission electron microscopy, Fourier transform infrared spectroscopy , PL, TL, and Commission Internationale de I'Eclairage techniques. The PL emission was observed in the range 417-632 nm ranges all visible regions for the Y 2 O 3 phosphor doped with Eu 3?. Excitation spectrum found at 254 nm. Sharp intense peaks found around 467, 534, 594, 612, and 632 nm with high intensity. From the XRD data, using the Scherer's formula, the calculated average crystallite size of Eu 3?doped Y 2 O 3 phosphor is around 45 nm. TL study was carried out for the phosphor with UV irradiation. The present phosphor can act as single host for white light emission in display devices.
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.
2011
Yttrium oxide doped with europium (Y2O3: Eu3+) is one of the main red emitting phosphor used in lightning industry and other optoelectronic devices [1-3]. To improve brightness and resolution of displays, it is important to develop phosphors with controlled morphology and small particle sizes. In order to achieve improved luminescent properties of Y2O3: Eu3+ the precursors characteristics as well as the synthetic route are very important factors.
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.
Micro & Nano Letters, 2012
In this study, Y 2 O 3 :Eu nanocrystals (NCs) were prepared through the combustion, Pechini and hydrothermal methods followed by the heat treatment of samples at 873 K. The resultant NCs were investigated by X-ray diffractometery, scanning electron microscopy, transmission electron microscopy, selected area electron diffractometery and photoluminescence (PL) spectroscopy. The obtained sample by the Pechini method presents cubic phase, whereas the hydrothermal sample consists of different phases (cubic, monoclinic and hexagonal phases of Y 2 O 3 besides yttrium nitrate hydrate phase). Cubic and monoclinic phases of Y 2 O 3 as well as tetragonal phase of yttrium oxide nitride (YO(NO 3 ) 3 ) phases were observed in combustion sample before heat treatment, whereas just the cubic phase stayed after heat treatment of this sample. The morphological investigations demonstrated that the hydrothermal sample has flower-like morphology with micron-size petals, whereas other samples have rounded particles. The PL intensity and chromaticity of Pechini sample are not as good as combustion and hydrothermal samples, but low agglomeration of the Pechini sample makes it good candidate for biological applications as a luminescence sensors and tags.
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.
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.
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...
Photoluminescence and Thermoluminescence Study of Europium Doped YAM Phosphor
2015
Paper reports the photoluminescence and thermoluminescence analysis of europium doped Y4Al2O9 phosphor for variable concentration of Eu 3+ . The sample was prepared by the conventional solid state reaction method, which is the most suitable for large-scale production. The prepared phosphor sample was characterized using X-Ray Diffraction (XRD), Photoluminescence (PL), Thermoluminescence (TL) and CIE techniques. The PL emission was observed in 613nm which is dominant peak gives the intense red emission for the Y4Al2O9 phosphor doped with Eu 3+ (0.2 mol% to 2 mol%). Excitation spectrum found at 254nm. The emission spectrum of Eu 3+ ions consists mainly due to the transitions from the 5 D0 level to the levels 7 FJ (J=0, 1, 2, 3, 4) of Eu ions. The dependence of luminescence intensity on Eu concentration shows concentration quenching after 2mol% of europium. Thermoluminescence study was carried out for the phosphor with UV irradiation. Kinetic parameter was calculated by CGCD technique.