Combustion synthesis and luminescence properties of LaPO 4: Eu (5 (original) (raw)
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Facile combustion-derived LaPO4:Eu3+ nanosystem and its photoluminescence properties
Indian Journal of Physics
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Eu3+ and Dy3+ doped La2MoO6 and La2Mo2O9 phosphors: Synthesis and luminescence properties
Materials Research Bulletin, 2020
We report a detailed structural analysis and properties of the photoluminescence (PL) and thermoluminescence (TL) spectra of Eu 3+ and Dy 3+ incorporated into novel La 2 MoO 6 and La 2 Mo 2 O 9 phosphors synthesized successfully through gel combustion synthesis. The formation of a tetragonal phase and a cubic structure were verified for La 2 MoO 6 and La 2 Mo 2 O 9 phosphors via X-ray diffraction (XRD) studies. Dy doped samples exhibited blue and green emissions at 480 nm (4 F 9/2 → 6 H 15/2) and 572 nm (4 F 9/2 → 6 H 13/2), and also Eu doped samples showed a sharp emission peaks at 612 and 619 nm (5 D 0 → 7 F 2) upon 349 nm pulse laser excitation. Peak shape (PS) technique was utilised to determine activation energy, frequency factor and order of kinetics associated with the main glow curves in undoped and Eu and Dy doped samples after X-ray irradiation. The present findings suggest that Eu and Dy incorporated La 2 MoO 6 and La 2 Mo 2 O 9 phosphors are highly auspicious candidates for applications in solid-state lighting.
Preparation and Optical Properties of La3PO7:Eu3+ Nanophosphors Synthesized by Combustion Method
MATERIALS TRANSACTIONS, 2020
Eu 3+ doped La 3 PO 7 nanoparticles were successfully synthesized under facial combustion method. The nano-phosphors then were characterized by some techniques including X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), photoluminescence spectrum (PL), and lifetime decay. SEM and TEM micrographs reveal exhibit of the La 3 PO 7 : Eu 3+ nanopowders in spherical morphology with an average size of about 20 nm, matching with Scherrer's formula calculation. Otherwise, the influence of annealing temperature and concentration of Eu 3+ ions on optical characteristics of Eu 3+ was doped La 3 PO 7 , and optical properties were investigated too. The photoluminescence shows the strong red emission originating from the 5 D 0 ¼ 7 F J (J = 1, 2, 3, and 4) transitions of Eu3+ and the 614 nm emission from the 5 D 0 ¼ 7 F 2 electronic dipole transition is dominant.
Preparation, characterization and luminescence of La 2TeO 6 phosphor doped with Eu 3
Materials Research Bulletin, 2008
Phosphors of La 2 TeO 6 doped with Eu 3+ ions have been synthesized by the oxidation of the corresponding rare-earths oxytellurides of formula La 2Àx Eu x O 2 Te (x = 0.02, 0.06, and 0.1) at 1050 K. Powder X-ray diffraction confirms that the as prepared materials consist of the orthorhombic La 2 TeO 6 as main phase. The photoluminescence (PL) of red-emitting La 2Àx Eu x TeO 6 powder phosphors is reported. The emission spectrum, exhibits an intense emission peak due to 5 D 0 ! 7 F 2 transition at 616 nm, which indicates that the Eu 3+ ion occupies a non-centrosymmetric site in the host lattice. These materials could find application for use as lamp phosphors in the red region. #
Journal of Alloys and Compounds, 2010
Rare-earth (Ce3+or Eu3+) or alkali-earth metal (Mn2+) doped Na3Al2(PO4)3 phosphor powder were prepared by a combustion method. Regardless of the dopants, the Na3Al2(PO4)3 was shown to crystallize as hexagonal (rhombohedral) NASICON phase with spheroidal micron sized particles based upon X-ray diffraction (XRD) and scanning electron microscopy (SEM) data. As confirmed by thermogravimetric (TGA) and differential thermal analysis (DTA) data, the powders were stable at high temperatures up to 900 °C. A broad UV emission (with maximum at 328 nm) associated with the 5d → 4f transition of Ce3+ was observed from Na3Al2(PO4)3:Ce3+ while Mn2+ and Eu3+ doping showed stable green and red photoluminescence emission at 515 and 615 nm, respectively. For different molar concentrations of rare-earth/alkali-earth metal dopants, the PL intensity was shown to increase to a certain concentration before quenching occurred at higher concentrations. The structure and optical properties of these phosphors were evaluated.
Solid State Sciences, 2011
Europium-doped lanthanum aluminate (LaAlO 3 ) powder was prepared by using a combustion method. The crystallization, surface morphology, specific surface area and luminescence properties of the samples have been investigated. Photoluminescence studies of Eu doped LaAlO 3 showed orange-reddish emission due to Eu 3þ ions. LaAlO 3 :Eu 3þ exhibits one thermally stimulated luminescence (TSL) peak around 400 C. Room temperature electron spin resonance spectrum of irradiated phosphor appears to be a superposition of two centres. One of them (centre I) with principal g-value 2.017 is identified as an O À centre while centre II with an isotropic g-value 2.011 is assigned to an F þ centre (singly ionized oxygen vacancy). An additional defect centre observed during thermal annealing around 300 C grows with the annealing temperature. This centre (assigned to F þ centre) originates from an F-centre (oxygen vacancy with two electrons) and the F-centre along with the associated F þ centre appear to correlate with the observed TSL peak in LaAlO 3 :Eu 3þ phosphor. The activation energy for this peak has been determined to be 1.54 eV from TSL data.
A B S T R A C T We synthesized the trivalent europium ions (Eu 3+) doped lanthanum aluminate (LaAlO 3 , LAO) nanophosphors by a solvothermal method. Their structural, morphological, and luminescent properties were systematically investigated. The obtained nanoparticles possessed single nanocrystallinity with a rhombohedral structure. For the excitation originating from the charge transfer band (O 2-to Eu 3+ ions) under 320 nm illumination, the featured emissions of Eu 3+ ions were detected in all the compounds. The optimum doping concentration of Eu 3+ ions in LAO was about 9 mol% and the concentration quenching was dominated by dipole-dipole interaction. Furthermore, the Judd-Ofelt (J-O) theory was used to estimate the J-O intensity parameters. Based on the temperature-dependent PL emission spectra, the thermal stability was analyzed and the activation energy was obtained to be 0.234 eV. Meanwhile, the decay time, color coordinate/purity, and cathodoluminescence behaviors of the synthesized nanophosphors were also studied. These characteristics make the Eu 3+-doped LAO nanoparticles a promising red-emitting phosphor for both ultraviolet-based white light-emitting diodes and field-emission displays.
Optical Materials, 2019
Stimulated luminescence of novel La 2 O 3 nanophosphors doped with Dy 3+ and Eu 3+ and co-activated with Li + , prepared by microwave-assisted solution combustion synthesis, was investigated for the very first time. X-ray diffraction results indicated hexagonal La 2 O 3 crystalline phase. Lanthanide and Li + doping did not affect the La 2 O 3 crystal structure. Scanning electron microscopy images showed nanoparticle morphologies such as plates, rods and irregular shapes. Photoluminescence spectra of La 2 O 3 :Dy 3+ , Li + exhibited blue and green emission bands due to Dy 3+ transitions. For La 2 O 3 :Eu 3+ , Li + , sharp emission lines, corresponding to the optical transitions of Eu 3+ were observed. Thermoluminescence glow curve of La 2 O 3 :Dy 3+ , Li + previously exposed to beta radiation exhibited a prominent glow peak located at ∼46 °C, possibly useful for after-glow or persistent lu-minescence applications, whereas La 2 O 3 :Eu 3+ , Li + curve, displayed three intense peaks at ∼50, ∼110 and ∼150 °C. Thermoluminescent signal repeatability and decay curve asymptotic behaviour could place La 2 O 3 :Eu 3+ , Li + as suitable for medium and high-dose radiation dosimetry applications.
LaAlO3:Eu3+ and LaAlO3:Tb3+ phosphors were prepared by microwave-induced combustion reaction. X-ray diffraction (XRD), scanning electron microscopy (SEN) and photoluminescence spectroscopy (PL) were used to characterize the produced powders. X-ray diffraction patterns confirmed the formation of nanocrystalline LaAlO3 oxide. Traces of secondary phase, La(OH)3, were observed in the pattern of the sample doped with terbium. Under UV excitation, Eu3+ and Tb3+-doped LaAlO3 phosphors show red and blue/green photoluminescence, respectively. These systems are potential candidates for use as luminescent materials.