Luminescence and structural properties of Y(Ta,Nb)O 4:Eu 3+,Tb 3+ phosphors (original) (raw)
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Moldavian Journal of the …, 2009
Yttrium tantalate, yttrium niobium-tantalate, and yttrium niobate doubly doped by Eu 3+ and Tb 3+ were investigated using X-ray diffraction and X-ray excitation luminescence in order to study their structural and luminescent properties. By means of X-ray diffraction, the crystallographic data for YTaO 4, Y(TaNb)O 4 , and YNbO 4 with double activation by Eu 3+ and Tb 3+ was first calculated. Under X-ray excitation luminescence, the rare earth emission centers can contribute to the overall luminescence. The simultaneous incorporation of Eu 3+ and Tb 3+ ions could permit us to obtain different luminescence colors on the entire visible spectrum. Due to their various luminescence chromaticities, the proposed rare earth activated phosphors are promising materials for optoelectronics as well as for X-ray intensifying screens for medical diagnosis providing the broad variation of photoluminescence colors from blue-to-green to yellow-to-red.
Studies concerning the properties of some europium activated phosphors based on yttrium tantalate
Physics Procedia, 2009
Rare earth activated YTaO 4 based phosphors are perspective materials for optoelectronics. The paper presents some physical and chemical aspects related to the influence of the host lattice composition and crystalline order on the luminescence of rare earth ions. In this respect, Eu -activated Y(Ta, Nb)O 4 powders have been prepared by solid state reaction, from homogeneous mixtures consisting of oxide precursors and flux. Photoluminescence (PL) spectroscopy, X-ray diffraction, FTIR spectroscopy and SEM have been used to investigate the structural and luminescent properties of Y(Ta,Nb)O 4 : Eu phosphors. Attempts has been made at establishing a correlation between the morphostructural parameters of the host lattice containing variable niobium amount and the PL properties. The interaction between the tantalate-niobate matrix and the Eu-emission centres is considered in correlation with the PL characteristics.
Journal of Luminescence, 2012
This paper reports the luminescence emission spectra of Y(Ta,Nb)O 4 activated by rare earth ions such as Eu 3 þ and Tb 3 þ. The influence of these rare earth ions on the luminescence of yttrium niobiumtantalate phosphors was investigated. The luminescent properties were studied under X-ray and electron beam excitations. Under these excitations, the emission centers of the rare earth activators (Eu 3 þ ,Tb 3 þ) were found to contribute efficiently to the overall luminescence. Changing the mol concentration of the incorporated activators resulted in a broad variation of visible photoluminescence. Color cathodoluminescence images showed clearly the dependence of chromaticity on the different activators. With their various luminescence chromaticities, these rare earth activated phosphors are promising materials for solid-state lighting applications as well as for X-ray intensifying screens in medical diagnosis, providing a broad variation of visible photoluminescence from blue to red.
Luminescence study of some yttrium tantalate-based phosphors
Journal of Luminescence, 2011
Yttrium tantalate (YTaO 4 ), yttrium niobium-tantalate (YTaNbO 4 ), yttrium niobate (YNbO 4 ), europium and terbium activated yttrium tantalate (YTaO 4 :Eu, YTaO 4 :Tb) and europium activated yttrium niobate (YNbO 4 :Eu) phosphors were prepared by solid-state reaction, from a homogeneous mixture consisting of SO 4 as flux. Photoluminescence (PL), thermally stimulated luminescence (TSL), X-ray diffraction (XRD) and scanning electron microscopy (SEM) of yttrium tantalate based phosphors are reported. In the present study TSL characteristics of these phosphors were first investigated and reported after exposure to beta, UV (311 nm) and X-ray radiations.
Preparation and characterisation of yttrium based luminescence phosphors
2012
High sensitive Y 2 O 3 :Eu 3+ , Gd 2 O 3 :Eu 3+ , (Y x Gd 1−x)O 3 :Eu 3+ , YAG (Y 3 Al 5 O 12):Eu 3+ and (Y x Gd 1−x)BO 3 :Eu 3+ luminescence display phosphors have been made by pyrolysis route followed by sintering at a relatively low temperature of 1000°C. The photoluminescent (PL) efficiencies of all the five phosphors under UV excitation are found to be comparable to that of commercial (Y x Gd 1−x)BO 3 :Eu 3+ (LG make). The PL efficiency as well as 395 nm (4f-4f) to 260 nm (charge transfer) excitation intensity ratio in Y 2 O 3 :Eu 3+ was found to vary in a complex way with Eu concentration. YAG:Eu 3+ could serve as a cheaper substitute to Y 2 O 3 :Eu 3+ red phosphor used currently in compact fluorescent lamps. While the PL efficiency of Y 2 O 3 :Eu 3+ remains fairly constant with excitation temperature in the region 25-250°C, the PL efficiency of (Y x Gd 1−x)BO 3 :Eu 3+ gets reduced by more than 30% when the excitation temperature increased from 25 to 250°C.
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.
Crystals
Eu3+-doped YxLu1−xNbO4 (x = 0, 0.25, 0.5, 0.75, 1) were prepared by the solid-state reaction method. YNbO4:Eu3+ and LuNbO4:Eu3+ crystallize as beta-Fergusonite (SG no. 15) in 1–10 μm diameter particles. Photoluminescence emission spectra show a slight linear variation of emission energies and intensities with the solid-solution composition in terms of Y/Lu content. The energy difference between Stark sublevels of 5D0→7F1 emission increases, while the asymmetry ratio decreases with the composition. From the dispersion relations of pure YNbO4 and LuNbO4, the refractive index values for each concentration and emission wavelength are estimated. The Ω2 Judd–Ofelt parameter shows a linear increase from 6.75 to 7.48 × 10−20 cm2 from x = 0 to 1, respectively, and Ω4 from 2.69 to 2.95 × 10−20 cm2. The lowest non-radiative deexcitation rate was observed with x = 1, and thus LuNbO4:Eu3+ is more efficient phosphor than YNbO4:Eu3+.
Rare earth activated yttrium aluminate phosphors with modulated luminescence
Luminescence : the journal of biological and chemical luminescence, 2015
Yttrium aluminate (Y3 A5 O12 ) was doped with different rare earth ions (i.e. Gd(3+) , Ce(3+) , Eu(3+) and/or Tb(3+) ) in order to obtain phosphors (YAG:RE) with general formula,Y3-x-a Gdx REa Al5 O12 (x = 0; 1.485; 2.97 and a = 0.03). The synthesis of the phosphor samples was done using the simultaneous addition of reagents technique. This study reveals new aspects regarding the influence of different activator ions on the morpho-structural and luminescent characteristics of garnet type phosphor. All YAG:RE phosphors are well crystallized powders containing a cubic-Y3 Al5 O12 phase as major component along with monoclinic-Y4 Al2 O9 and orthorhombic-YAlO3 phases as the impurity. The crystallites dimensions of YAG:RE phosphors vary between 38 nm and 88 nm, while the unit cell slowly increase as the ionic radius of the activator increases. Under UV excitation, YAG:Ce exhibits yellow emission due to electron transition in Ce(3+) from the 5d level to the ground state levels ((2) F5/2 , ...
Journal of Physics D: Applied Physics, 2012
In this work, Eu-doped, Tb-doped and Eu, Tb-codoped Y 2 O 3 nanophosphors were synthesized by the combustion synthesis method. The prepared phosphors were characterized by x-ray diffraction (XRD), Rietveld refinement and Fourier transform infrared (FTIR) spectroscopy. XRD studies and Rietveld refinement confirmed the body-centred cubic structure of doped and codoped phosphors. FTIR studies also confirmed the formation of these compounds. Thermal analysis results indicated that there was no phase transition for all the phosphors in the studied temperature range. In the optical properties, diffuse reflectance (DR) and photoluminescence (PL) measurements were performed. DR spectra were used to determine the bandgap and it increased in the doped and codoped samples due to the crystallite size effect. A strong characteristic emission from Eu 3+ and Tb 3+ ions was identified and the influence of doping concentration and annealing temperature on PL properties was systematically studied. Transfer of energy was observed from Tb 3+ to Eu 3+ ions in the codoped phosphor at room temperature.
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.