Cathodoluminescence of Nanocrystalline Y2O3:Eu3+ with Various Eu3+ Concentrations (original) (raw)
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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.
2009
The effect of incorporation of trace (Al +3 , B +3) in the Y 2 O 3 lattice on the luminescence efficiency of Y 2 O 3 :Eu +3 red phosphor has been investigated. It is observed that such incorporation causes an enhancement of 5 D 0 → 7 F 2 red luminescence efficiency as well as the associated excitation efficiency of Eu +3. It is concluded that there occurs a change in the polarity of the host rather than the site symmetry of Eu +3 due to incorporation of the hetero cations. Calculation of the Judd-Ofelt parameters gives similar results. In another study, to observe the effect of reduction of particle size on the luminescence efficiency of the Y 2 O 3 :Eu +3 , the change in luminescence efficiency of the phosphor with the reduction particle size and the stability of the different efficiencies with the elapse of time have been investigated. The samples with particle size below 100 nm showed a significant loss in luminescence efficiency and a change in their excitation profile with time. IR studies showed that although the freshly prepared samples were almost free from contaminated water, on ageing in air at room temperature, they absorb the latter. A phenomenon of hydration induced coupling of the excitonic state of Y 2 O 3 with one of its F u modes, has been detected in the case of the aged samples which susequently introduces newer non-radiative channels in the system causing a decrease in the luminescence efficiency of the phosphor. Because of larger surface to volume ratio, the effect is most pronounced in nanocrystalline samples.
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.
151Eu Mössbauer study of luminescent Y2O3:Eu3 + core-shell nanoparticles
Hyperfine Interactions, 2012
Eu Mössbauer spectroscopy was applied to distinguish among different Eu microenvironments and phases in spherical Y 2 O 3 :Eu 3+ and core-shell Y 2 O 3 @Eu 3+ phosphor nanoparticles prepared by using homogeneous precipitation method. 151 Eu isomer shift revealed that Eu atoms exist only in oxidation state Eu 3+ in all spherical and core-shell phosphors. Significant differences have been found between the Mössbauer parameters (isomer shift, principal component of EFG and linewidth) characteristic of spherical Y 2 O 3 :Eu 3+ and core-shell Y 2 O 3 @Eu 3+ phosphor nanoparticles. The Mössbauer parameters of spherical Y 2 O 3 :Eu 3+ were associated with Eu substituting Y in the Y 2 O 3 , while Mössbauer parameters of coreshell Y 2 O 3 @Eu 3+ phosphor were attributed to Eu being in the Eu 2 O 3 shell, proving the structural model and the successful preparation of these phosphors.
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.
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.
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.
Journal of Nanomaterials, 2015
Y2O3:Eu3+nanophosphors were prepared through combustion reaction under controlled condition of the fuel ethylenediaminetetraacetic acid (EDTA-Na2) and in the temperature range from 350 to 700°C. The products were characterized by X-ray diffraction (XRD), field emission scattering electron microscopy (FESEM), and energy dispersive spectroscopy (EDS). The results showed that Y2O3:Eu3+nanoparticles were successfully synthesized by combustion method at low temperature and in short reaction time. The light-emitting ability of Y2O3:Eu3+nanoparticles upon the electron excitation has been studied at the potentials 5, 10, and 15 kV. The thermoluminescent glow curves have elucidated an intense peak at 117°C after UV exposure and at least two peaks at 125 and 336°C with Gamma irradiation. Photoluminescent spectra of Y2O3:Eu3+nanoparticles exhibited strong red luminescent color with highest sharp band at 612 nm under excitation in ultraviolet at 254, 394 and in visible at 465 nm. The dependence...
Journal of …, 2008
Luminescence, energy transfer, and upconversion mechanisms of nanophosphors (Y 2 O 3 : Eu 3+ , Tb 3+ , Y 2 O 3 : Tm 3+ , Y 2 O 3 : Er 3+ , Yb 3+ ) both in particle and colloidal forms were studied. The structure, phase, and morphology of the nanopowders and nanocolloidal media were determined by high-resolution TEM and X-ray diffraction. It was shown that the obtained nanoparticles have a round-spherical shape with average size in the range of 4 to 20 nm. Energy transfer was observed for Y 2 O 3 : Eu 3+ , Tb 3+ colloidal and powders, upconversion transitions were observed for both Y 2 O 3 : Er 3+ and Y 2 O 3 : Er 3+ , Yb 3+ nanophosphors. The dependence of photoluminescence (PL) spectra and decay times on doping concentration has been investigated. The infrared to visible conversion of emission in Y 2 O 3 : Er 3+ , Yb 3+ system was analyzed and discussed aiming to be applied in the photonic technology.