Structural, morphological and steady state photoluminescence spectroscopy studies of red Eu(3+) -doped Y2 O3 nanophosphors prepared by the sol-gel method (original) (raw)
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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.
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.
Morphology controlled Y2O3:Eu3+ nanophosphors with enhanced photoluminescence properties
Journal of Luminescence, 2015
Eu 3 þ doped Y 2 O 3 is prepared by a co-precipitation method using ammonium hydrogen carbonate as precipitating agent. In the present work we studied the effect of different molar concentrations of Poly vinyl pyrrolidone (PVP) and 1-Thio-glycerol (TG) as capping agents to enhance the optical and morphological properties of Y 2 O 3 :Eu 3 þ nanophosphors. In addition, variation of pH was studied to control the particle size of the synthesized product. The polymer concentration (TG and PVP) was also optimized at different pH to get higher luminescence of Eu 3 þ doped Y 2 O 3 nanoparticles (NPs). It was observed that pH of solution during synthesis and also its concentration affect the morphological and optical properties of Y 2 O 3 :Eu 3 þ . The structural, morphological and optical properties were studied by an X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and photoluminescence spectroscopy. XRD studies followed by Rietveld refinement confirmed the bodycentered cubic structure of doped nanophosphors. It was observed that at optimized pH and polymer concentration the nanoparticles of Y 2 O 3 :Eu 3 þ have narrow size distribution and exhibited enhanced photoluminescent properties.
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.
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.
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.
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...
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.
Optical Materials, 2015
This work reports on the synthesis and characterization of Y 2 O 3 :Eu 3+ powders obtained by the hydrothermal method. We studied the influence of different pH values (7-12) and Eu 3+ concentrations (2.5-25 mol%) on the structural, morphological and luminescent characteristics of Y 2 O 3 :Eu 3+ powders. The hydrothermal synthesis was performed at 200°C for 12 h by employing Y 2 O 3, HNO 3 , H 2 O and Eu (NO 3) 3 as precursors, in order to obtain two sets of samples. The first set of powders was obtained with different pH values and named Eu5PHx (x = 7, 8, 9, 10, 11, and 12), and the second set was obtained by using a constant pH = 7 with different Eu concentrations, named EuxPH7 (x = 2.5, 5, 8, 15, 20 and 25). The XRD spectra showed that the Y 2 O 3 :Eu 3+ powders exhibited a cubic phase, regardless of the pH values and Eu 3+ concentrations. The SEM observations indicated that pH influenced the morphology and size of phosphors; for instance, for pH = 7, hexagonal microplatelets were obtained, and microrods at pH values from 8 to 12. Doping Y 2 O 3 with various Eu 3+ concentrations (in mol%) also produced changes in morphology, in these cases, hexagonal microplatelets were obtained in the range of 2.5-5 mol%, and non uniform plates were observed at higher doping concentrations ranging from 8 to 25 mol%. According to our results, the microplatelets synthesized with a pH of 7 and an 8 mol% Eu 3+ concentration presented the highest luminescence under excitation at 254 nm. All of these results indicate that our phosphors could be useful for applications of controlled drug delivery, photocatalysis and biolabeling.
Spherical-shaped Y2O3:Eu3+ nanoparticles with intense photoluminescence emission
Ceramics International, 2015
Herein we report on the crystallized nanoparticles based on Eu 3 þ -doped Y 2 O 3 with 5 mol% using citric acid as precursor. The heating temperatures were evaluated in order to obtain the best crystallized nanoparticles with size around 12 nm and with highest red intense photoluminescence emission. Nanocrystallite size was calculated by Scherrer's equation based on diffractogram of the material heated at 750 1C for 4 h, obtaining size around 8 nm. The low photoluminescence intense emissions were attributed to the presence of quenchers remaining from precursors used in the synthesis. In general the photoluminescence properties were evaluated based on emission and excitation spectra profile. Rietveld refinement was performed based on the diffractogram of the material annealed at 750 1C for 4 h, and the visualization of the cubic structure was obtained. The centered cubic crystalline structure of Y 2 O 3 was obtained and the photoluminescence properties of Eu 3 þ ion in Y 2 O 3 host lattice was verified as being dependent on the temperature of heating and C 2 and S 6 site of symmetry present in the cubic structure. CIE chromaticity diagram was obtained with x and y being 0.682 and 0.316, respectively, for material with the highest relative photoluminescence intensity.