151Eu Mössbauer study of luminescent Y2O3:Eu3 + core-shell nanoparticles (original) (raw)
Related papers
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.
Enhancement of Luminescence Efficiency of Y2O3 Nanophosphor via Core/Shell Structure
Nanomaterials, 2021
We successfully fabricated Y2O3:RE3+ (RE = Eu, Tb, and Dy) core and core–shell nanophosphors by the molten salt method and sol–gel processes with Y2O3 core size of the order of 100~150 nm. The structural and morphological studies of the RE3+-doped Y2O3 nanophosphors are analyzed by using XRD, SEM and TEM techniques, respectively. The concentration and annealing temperature dependent structural and luminescence characteristics were studied for Y2O3:RE3+ core and core–shell nanophosphors. It is observed that the XRD peaks became narrower as annealing temperature increased in the core–shell nanophosphor. This indicates that annealing at higher temperature improves the crystallinity which in turn enhances the average crystallite size. The emission intensity and quantum yield of the Eu3+-doped Y2O3 core and core–shell nanoparticles increased significantly when annealing temperature is varied from 450 to 550 °C. No considerable variation was noticed in the case of Y2O3:Tb3+ and Y2O3:Dy3+ ...
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.
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.
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.
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 studies of Blue emission of Y2O3:Eu 2+ Nanophosphor
International Journal of Luminescence & its applications, 2017
The present paper reports the Photoluminescence of Eu 2+ electronic transition of Y2O3:Eu Nanophosphor. The samples are prepared by combustion synthesis route. Urea is employed as fuel in this synthesis method. XRD results of samples were found to have cubic nanocrystalline structure ranging from 12-65nm which resembles with the TEM results. Research work explores the PL emission of 425nm corresponding to 374nm excitation of Y2O3:Eu 2+ Nanophosphor. Paper reports the effect of annealing temperature on PL intensity of Y2O3:Eu 2+ phosphor. 1931 CIE coordinates shows Eu 2+ transition of Blue emission corresponding to coordinates x=0.1703, y=0.0057.
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.
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.