A5068300396- Luminescence Properties of Advanced Materials
- Radiation Detection and Scintillator Technologies
- Glass properties and applications
- Solid-state spectroscopy and crystallography
- Inorganic Chemistry and Materials
- Ammonia Synthesis and Nitrogen Reduction
- Inorganic Fluorides and Related Compounds
- Perovskite Materials and Applications
- Crystal Structures and Properties
- Nuclear materials and radiation effects
- MXene and MAX Phase Materials
- Gas Sensing Nanomaterials and Sensors
- Electronic and Structural Properties of Oxides
- Photorefractive and Nonlinear Optics
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum Dots Synthesis And Properties
- X-ray Diffraction in Crystallography
- ZnO doping and properties
- Rare-earth and actinide compounds
- bioluminescence and chemiluminescence research
- Advanced Photocatalysis Techniques
- 2D Materials and Applications
- Terahertz technology and applications
- Ga2O3 and related materials
- Pigment Synthesis and Properties
Ghent University
2009-2021
Ghent University Hospital
2017-2018
Laser excitation and x-ray spectroscopy are combined to settle a long-standing question in persistent luminescence. A reversible electron transfer is demonstrated, controlled by light showing the same kinetics as Exposure violet induces charging oxidation of excited Eu^{2+} while Dy^{3+} simultaneously reduced. Oppositely, detrapping Dy^{2+} occurs at ambient temperature or infrared illumination, yielding afterglow optically stimulated luminescence, respectively.
Traditional light sources, e.g., incandescent and fluorescent lamps, are currently being replaced by white light-emitting diodes (wLEDs) because of their improved efficiency, prolonged lifetime, environmental friendliness. Much effort has recently been spent to the development Mn4+-doped fluoride phosphors that can enhance color gamut in displays improve rendering index, luminous efficacy radiation, correlated temperature wLEDs used for lighting. Purity, stability, degradation are, however,...
The development of new efficient afterglow phosphors is currently hampered by a limited understanding the persistent luminescence mechanism. Radioluminescence (RL) and x-ray absorption measurements on phosphor SrAl${}_{2}$O${}_{4}$:Eu,Dy were combined to reveal possible valence state changes for rare earth (co)dopants. Traps in material are quickly filled when exposing thermally emptied powder x rays. On same time scale partial oxidation Eu${}^{2+}$ Eu${}^{3+}$ observed near-edge...
A combination of techniques is used to investigate the incorporation chromium in persistent phosphor LiGa<sub>5</sub>O<sub>8</sub>:Cr<sup>3+</sup>. Afterglow can be enhanced by codoping with Si(<sc>iv</sc>) or Ge(<sc>iv</sc>) ions.
Mn4+-activated phosphors are emerging as a novel class of deep red/near-infrared emitting persistent luminescence materials for medical imaging promising alternative to Cr3+-doped nanomaterials. Currently, it remains challenge improve the afterglow and photoluminescence properties these through traditional high-temperature solid-state reaction method in air. Herein we propose charge compensation strategy enhancing performance LaAlO₃ phosphors. LaAlO₃:Mn4+ (LAO:Mn4+) was synthesized by The...
Persistent luminescent CaAl 2 O 4 :Eu 2+ ,Nd 3+ powders were prepared by a non-aqueous sol-gel technique.The crystallization of calcium aluminate heat-treatment the sols is described in detail.After heat treatment air, europium dopant ions are mainly trivalent state.For reduction to divalent state post-annealing reducing nitrogen-hydrogen atmosphere used.The monitored photoluminescence and x-ray absorption (XANES) spectroscopy.The degree strongly dependent on annealing temperature.Although...
The efficient blue luminescence of Eu2+ doped BaMgAl10O17 is well-known to be severely degraded by prolonged irradiation with vacuum-ultraviolet light. degradation process at the atomic level however not fully understood. In this work we employed X-rays as an equivalent but accelerated cause degradation, excitation source and element-selective probe both dopants host-lattice chemical species. X-ray absorption near edge structure (XANES) recorded in high energy resolution mode reveals that...
Single-crystal, submicrometer-sized CaS:Eu luminescent particles were synthesized via a solvothermal route, and these moisture-sensitive coated with aluminum oxide using atomic layer deposition (ALD). Photoluminescence (PL) spectra of uncoated compared. They both showed broad-band PL emission maximum 650 nm. Microencapsulation by layers did not have pronounced effect on the intensity emission. In situ luminescence measurements during accelerated aging (, 80% relative humidity) performed....
Degradation pathways of K<sub>2</sub>MnF<sub>6</sub>, an essential precursor for the synthesis red fluoride phosphors, are revealed.
Abstract Light sensors are widely used to monitor light intensities, for instance in medical applications, agriculture or conservation of art. Most these electronic devices that record continuously but applications only require information integrated measured over a long time, could greatly benefit from an integrating dosimeter does not power supply. In this work wireless and quantitative is presented based on SrAl 2 O 4 :Eu 2+ ,Sm 3+ , phosphor exhibits stable energy storage upon exposure...
Light-emitting diodes (LEDs) are efficient, energy-saving light sources. Unfortunately, designing phosphors for LEDs that emit warm white is not straightforward. We solvothermally prepared rare earth doped alkaline sulfides with a core-shell structure in order to obtain physical separation between different dopants (europium and cerium). Cathodoluminescence of single phosphor particle an electron microscope proves simultaneous Eu2+ Ce3+ broad band emission. The emission color can be tuned by...
The R2(MoO4)3 (R = rare earth elements) molybdates doped with Eu3+ cations are interesting red-emitting materials for display and solid-state lighting applications. structure luminescent properties of the R2–xEux(MoO4)3 Gd, Sm) solid solutions have been investigated as a function chemical composition preparation conditions. Monoclinic (α) orthorhombic (β′) Sm; 0 ≤ x 2) modifications were prepared by reaction, their structures using synchrotron powder X-ray diffraction transmission electron...
A spectroscopic study shows that energy storage prior to mechanoluminescence and thermoluminescence in CaZnOS:Mn can be effectuated by a ligand-to-Mn charge transfer.
Due to its bright yellow-to-red emission, europium doped Ca2SiS4 is a very interesting material for phosphor converted light emitting diodes. The emission spectrum highly dependent on the Eu concentration and can consist of more than one band. We combined X-ray absorption fine structure photoluminescence measurements analyze centers in (Ca,Eu)2SiS4 luminescent powders. This paper provides an explanation dependency spectra. find that at low dopant concentrations large fraction trivalent ions...
Europium doped zinc thiogallate, ZnGa 2 S 4 :Eu 2+ , has been reported as a saturated green emitting phosphor, suitable conversion phosphor in white LEDs for lighting or displays.Up to now, no direct proof the incorporation of Eu given.We combined X-ray diffraction (XRD), cathodoluminescence electron microscopy (SEM-CL) and absorption spectroscopy (XAS) study europium ions host material.The previously luminescence was found originate from small amounts unintentionally formed EuGa not...
Optical whispering gallery modes were observed in micron-sized SrS:Eu2+ octahedrons. Cathodoluminescence a scanning electron microscope was used to evaluate the emission characteristics of individual octahedrons with various sizes. The resonance superposed on orange Eu2+ broadband explained by plane wave model, taking wavelength dispersion refractive index into account. occur three equatorial planes octahedrons, which approximated corner-cut square disks.
(Co, Nb, Sm)‐doped SnO 2 ‐based ceramic with varistor characteristics was successfully fabricated by a conventional sintering of nanosized powders prepared coprecipitation method. Values α∼38 and E B =1430 V/mm were obtained for the doped 0.05 mol % Sm O 3 , sintered at 1200°C 1 h. Microstructure development studied scanning transmission electron microscopy, elemental analysis, X‐ray diffraction. The mean grain size 1.75 μm. No other phase besides observed in . presence Co, inside grains...
Correction for ‘K<sub>2</sub>MnF<sub>6</sub> as a precursor saturated red fluoride phosphors: the struggle structural stability’ by Reinert Verstraete <italic>et al.</italic>, <italic>J. Mater. Chem. C</italic>, 2017, <bold>5</bold>, 10761–10769.