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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Poelman, Dirk
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (27/27 displayed)
- 2024Ratiometric dual-emitting thermometers based on rhodamine B dye-incorporated (nano) curcumin periodic mesoporous organosilicas for bioapplicationscitations
- 2024Evolution of low Z-elements in a Ni/MgFeAlO 4 catalyst during reaction : insight from in situ XRScitations
- 2024Unleashing the glow : upconverting nanoparticles recharge persistent luminescent materials - applications in 3D-printing and optical codingcitations
- 2023Flexible and luminescent polymer nanocomposite films (YPO4:Pr3+/ polystyrene) : investigation of structural, morphological and photoluminescence properties for solid-state lighting applicationscitations
- 2023The exact morphology of metal organic framework MIL-53(Fe) influences its photocatalytic performancecitations
- 2023Thermoluminescence dosimetric and kinetic characterization of Pakistani fluorite after β irradiationcitations
- 2023Crystalline tin disulfide by low-temperature plasma-enhanced 2 atomic layer deposition as an electrode material for Li-ion batteries 3 and CO2 electroreductioncitations
- 2023High temperature H2S removal via CO2-assisted chemical looping over ZrO2-modified Fe2O3citations
- 2023Plasma-enhanced atomic layer deposition of crystalline Ga2S3 thin filmscitations
- 2023Plasma-enhanced atomic layer deposition of crystalline Ga2S3 thin filmscitations
- 2022Photocatalytic nanocomposite membranes for environmental remediationcitations
- 2021Young's modulus of thin SmS films measured by nanoindentation and laser acoustic wavecitations
- 2021Emergence of Metallic Conductivity in Ordered One-Dimensional Coordination Polymer Thin Films upon Reductive Dopingcitations
- 2020A new microwave approach for the synthesis of green emitting Mn2+-doped ZnAl2O4citations
- 2020A new microwave approach for the synthesis of green emitting Mn 2+ -doped ZnAl 2 O 4 :A detailed study on its structural and optical propertiescitations
- 2019SmS/EuS/SmS tri-layer thin films : the role of diffusion in the pressure triggered semiconductor-metal transitioncitations
- 2019Sol-gel syntheses of photocatalysts for the removal of pharmaceutical products in watercitations
- 2018Visible-enhanced photocatalytic performance of CuWO4/WO3 hetero-structurescitations
- 2014Crystal Structure and Luminescent Properties of R2-xEux(MoO4)(3) (R = Gd, Sm) Red Phosphorscitations
- 2013Cs7Nd11(SeO3)(12)Cl-16: first noncentrosymmetric structure among alkaline-metal lanthanide selenite halidescitations
- 2013Combining optical and electrical studies to unravel the effect of Sb doping on CIGS solar cell
- 2012The configuration of rare earth centers in nitridosilicates: an x-ray absorption and optical investigation
- 2010Structure and luminescence of (Ca,Sr)2SiS4:Eu2+ phosphorscitations
- 2008Cathodoluminescence mapping with an energy-dispersive x-ray detector: principle, simulation and application
- 2008Synthesis and photoluminescence characteristics of Al2O3 thin films doped with (Ca,Sr)S:Eu2+
- 2008Cathodoluminescence mapping with an EDX detector: principle, simulation and application
- 2007Effect of microstructure and crystallinity on the photocatalytic activity of TiO2 thin films deposited by dc magnetron sputtering
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document
The configuration of rare earth centers in nitridosilicates: an x-ray absorption and optical investigation
Abstract
White light emitting diodes (LEDs) are environmentally friendly lighting systems because of their low energy consumption and long lifetime. White LEDs are combinations of a blue LED and one or more phosphor materials. Rare earth doped nitridosilicates can be applied as phosphor in such white LEDs. Their advantages are a high thermal quenching temperature and a high stability [1,2]. Since the emission characteristics in these materials depend highly on the local environment of the dopant ions, a direct investigation of their neighborhood is necessary to optimize the phosphor.The photoluminescence of the rare earth doped nitridosilicates Ca2Si5N8:Ce and Ca2Si5N8:Eu was investigated in detail. Furthermore the incorporation of the dopant ions in the Ca2Si5N8 host lattice was investigated using x-ray absorption spectroscopy. Exafs data were collected at the BM01 (SNBL) and BM23 beamlines at the ESRF synchrotron facility in Grenoble (France).This study reports on the structure of the rare earth centers and the influence of a Li codopant on the emission spectrum, thermal quenching temperature and quantum efficiency of the phosphor. We found that the rare earth dopants, i.e. Ce and Eu, occupy both Ca2+ sites in the monoclinic host lattice, albeit with some preferential substitution (figure 1). From the x-ray absorption spectra it is found that Ca2Si5N8:Eu only contains Eu2+, and remarkably Ca2Si5N8:Ce contains not only Ce3+ but also an unexpected large fraction of Ce4+, which is known to be a luminescence killer [3]. It was proven both on the micro-scale (with SEM-CL and SEM-EDX mapping) and nano-scale (with Exafs) that this is not due to the presence of extra phases like CeO2. Moreover, because the fraction of Ce4+ shows the inverse trend as the quantum efficiency, it is believed that Ce4+ indeed builds into the lattice. It is thought that the most probable way for the Ce ions to do this is via two Ce3+ ions together with a nearby Ca2+ vacancy or via one Ce4+ ion with one nearby vacancy, since such clusters respect electrostatic equilibrium.In such cases of doping with Ce, Li+ is sometimes added as a codopant for charge compensation. Such codoping makes the previous cluster superfluous and the Ce ions rather build into the lattice with one or two Li+ ions nearby. This change in local Ce structure in codoped and non-codoped samples is investigated with Exafs.Photoluminescence measurements show that adding a codopant during synthesis does not affect the emission spectrum but influences the thermal quenching temperature and quantum efficiency of the phosphor – both of which can be explained by looking at the change in the local environment of the luminescent ion.