Dependence of Eu3+ luminescence dynamics on the structure of the combustion synthesized Sr5(PO4)3F host (original) (raw)
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Influence of Li+ doping on photoluminescence properties of Sr5(PO4)3F:Eu3+
Advanced Materials Letters, 2010
In this article, the influence of lithium co-doped on Sr 5 (PO 4) 3 F:Eu 3+ halophosphate based phosphor reported. The Sr 5 (PO 4) 3 F:Eu 3+ and Sr 5 (PO 4) 3 F:Eu 3+ , Li + phosphors were prepared by combustion synthesis route using urea as the fuel. The phosphors were characterized by X-ray diffraction (XRD) and photoluminescence (PL) techniques. The powders were annealed at 900 o C and 1200 o C and characterized by X-ray diffraction (XRD) which shows that the major crystalline phases from the as prepared or annealed powder samples were identical. The PL results show that the incorporation of Li + ions into the Sr 5 (PO 4) 3 F:Eu 3+ lattice could induce a remarkable improvement of the PL intensity in red region at 395 nm excitation wavelength. The highest emission intensity was observed with the compound of Eu 3+ 0.5 mol% and Li + 0.5 mol% co-doped Sr 5 (PO 4) 3 F, whose brightness was increased by a factor of more than 3.0 in comparison with that of the Sr 5 (PO 4) 3 F:Eu 3+. The 300-400 nm is Hg free excitation (Hg excitation is 85% 254 nm wavelength of light and 15% other wavelengths), which is characteristic of solidstate lighting phosphors. Hence PL emission in trivalent europium co-doped with lithium may be efficient photoluminescent materials for solid-state lighting phosphors as a red component.
Journal of Non-crystalline Solids, 2009
Strong blue-green light emitting Eu doped SrAl 2 O 4 phosphor was synthesized by a low-temperature initiated, self-propagating and gas producing combustion process in a very short time (<5 min). The prepared powder was characterized by X-ray diffraction, Fourier-transform infrared spectrometry and scanning electron microscopy. The excitation spectrum shows a peak at 397 nm. Upon excitation at 397 nm, the emission spectrum exhibits a well defined broad band with maximum at 493 nm corresponding to 4f 6 5d ? 4f 7 transition. Electron paramagnetic resonance (EPR) measurements at X-band showed low field signals due to Eu 2+ ions in SrAl 2 O 4 :Eu.
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.
The combustion synthesis method was employed for the synthesis of red-emitting monoclinic SrAl2O4:Eu 3+ phosphors. Structural characterization of annealed samples was carried out via X-ray Diffraction (XRD). XRD patterns reveal that strontium aluminate samples were cubic spinel nanoparticles and the grain size determined by the Debye-Scherrer formula is 35.34 nm. The vibrational stretching frequencies corresponding to the composites were confirmed by FT-IR spectroscopy. The PL spectra show the strongest emission at 612 nm corresponds to the 5 D0 → 7 F2 transition of Eu 3+ , which results in bright red color emitting phosphor used for display devices and lamp industries.
Displays, 2008
Eu2+, Dy3+ and Gd3+ co-doped strontium aluminate yellow-green phosphor was synthesized by combustion method using urea as reducer at 600 °C. The crystallization, particles size and luminescence properties of the sample have been investigated. The results are as follows: Eu2+, Dy3+ and Gd3+ doped into the phosphor do not change the crystalline structure of strontium aluminate. The average size of particles is about 100 nm. The excitation and emission spectra are broad bands with the peaks at 348 and 515 nm, respectively. Compared with SrAl2O4: Eu2+, Dy3+ phosphor, the initial brightness improved and the afterglow time prolonged.
Optik, 2017
Orange-red emitting europium doped (1-9 mol %) SrTiO3 (ST) nanophosphor was synthesized by solution combustion method using urea as a fuel. The crystallinity and phase formation of the nanophosphor was studied by powder X-ray diffraction (PXRD). The Field-emission scanning electron microscopy (FE-SEM) images are evident for the porous and agglomeration nature for the product. The Fourier transform infrared spectroscopy (FT-IR) indicates the formation of the oxide bonds. The photoluminescence (PL) of SrTiO3:Eu 3+ phosphor with different mol % of Eu 3+ excited by 395 nm light was studied. The photoluminescence spectra exhibit characteristic luminescence from 5 D0 → 7 F1, 2, 3 intra-4f shell Eu 3+ ion transitions. An intense orange red emission peak at 615 nm was observed due to electric dipole (5 D0 → 7 F2) transition. The color purity of the phosphor was confirmed by CIE coordinates. The study demonstrates a simple and efficient method for the synthesis of novel nanophosphor with enhanced orange-red emission.
Journal of Radiation Research and Applied Sciences, 2015
Europium doped di-strontium magnesium di-silicate phosphor namely (Sr 2 MgSi 2 O 7 :Eu 3þ) was prepared by the traditional high temperature solid state reaction method. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P42 1 m, this structure is a member of the melilite group and forms a layered compound. The EDX and FTIR spectra confirm the present elements in Sr 2 MgSi 2 O 7 :Eu 3þ phosphor. Photoluminescence measurements showed that the phosphor exhibited strong emission peak with good intensity, corresponding to 5 D 0 / 7 F 2 (613 nm) red emission and weak 5 D 0 / 7 F 1 (590 nm) orange emission. The excitation spectra monitored at 613 nm show broad band from 220 to 300 nm ascribed to OeEu charge-transfer band (CTB) centered at about 269 nm, and the other peaks in the range of 300e400 nm originated from fef transitions of Eu 3+ ions. The strongest band at 395 nm can be assigned to 7 F 0 / 5 L 6 transition of Eu 3þ ions due to the typical fef transitions within Eu 3þ of 4f 6 configuration.
Nanostructured europium oxalate was successfully synthesized for the first time by microwave assisted co-precipitation method. Structure and nanocrystalline nature of the synthesized europium oxalate was analyzed using X-ray diffraction and the results were confirmed by transmission electron microscopy. Fourier transform infrared spectroscopy was employed to identify the different functional groups present in the nanostructured europium oxalate. Detailed spectroscopic investigations were carried out using JuddeOfelt theory to find out the spectroscopic parameters of europium oxalate. Nature of the metal-ligand bond and symmetry of the environment around Eu 3þ ions, which strongly influences the lumi-nescence characteristics of the material, were analyzed. Photoluminescence emission spectrum of the material confirmed the strong red emission predicted by the JO theoretical analysis which is further ascertained by CIE chromaticity diagram. Further analysis on the luminescence parameters such as life time, quantum efficiency and color purity of nanostructured europium oxalate revealed the suitability of this material as a potential phosphor for red emission.
Social Science Research Network, 2022
Europium doped lanthanum aluminate nanophosphors were synthesized by a combustion process using Oxalyl di-hydrazide as fuel. The nanophosphors calcined at 900 C for 3 h were characterized by PXRD, FTIR spectroscopy, SEM and TEM. The average crystallite size determined by TEM and Scherrer's method was found to be in the range 20e50 nm. The characteristic emission peaks (l exi-395 nm) recorded at~591, 616, 646 and 696 nm (5 D 0 / 7 F j¼0,1,2,3) may be attributed to the 4fe4f intra shell transitions of Eu 3þ ions. The estimated CIE chromaticity coordinates were calculated from emission spectra, were close to the national television standard committee value of red emission. Correlated color temperature was found to be 1929 K.