0000000000073395
AUTHOR
M. Kemere
Influence of boron on the essential properties for new generation scintillators
Abstract Cerium doped yttrium aluminum (YAG:Ce) and lutetium aluminum garnets (LuAG:Ce) are some of the most popular materials used as scintillators. While the scintillators themselves are materials that absorb and convert high-energy radiation into light. The decay time in YAG:Ce and LuAG:Ce is about 60 ns, therefore the essential task for their improvement would be to shorten it as much as possible. For this reason, in this work, the aforementioned garnets were doped with different amounts of boron. B3+ ion has a suitable neutron capture cross section and can therefore absorb gamma radiation. Because of the extremely strong absorption of thermal neutrons and the weak interaction with MeV …
Electron paramagnetic resonance and photoluminescence investigation of europium local structure in oxyfluoride glass ceramics containing SrF2 nanocrystals
Different compositions of europium doped aluminosilicate oxyfluoride glass ceramics prepared in air atmosphere have been studied by electron paramagnetic resonance (EPR) and optical spectroscopy methods. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements show presence of homogenously distributed SrF2 nanocrystals after the heat treatment of the precursor glass. Efficient Eu3+ incorporation in the high symmetry environment of glass ceramics is observed from the photoluminescence spectra. EPR spectra indicate Eu3+ → Eu2+ reduction upon precipitation of crystalline phases in the glass matrix. For composition abundant with Eu2+ in the glassy state such behaviour is …
Luminescence and energy transfer in Dy3+/Eu3+ co-doped aluminosilicate oxyfluoride glasses and glass-ceramics
Abstract A series of oxyfluoride glasses with the composition SiO2–CaF2–Al2O3–CaO, doped with Dy2O3 (0.5–1 mol%) and Eu2O3 (0–4 mol%), have been prepared using the melt quenching method. The glass-ceramics have been obtained by heating the as-made glasses at 680 °C and 750 °C for 1 h. The glasses and the glass-ceramics were investigated using photoluminescence techniques in the near-UV and visible ranges, and differential thermal analysis (DTA) and x-ray diffraction (XRD) measurements were performed. The samples doped with 0.5 mol% Dy3+ were observed to have the highest luminescence intensity under 453 nm excitation compared to the samples doped with 1 mol% Dy3+ and the co-doped samples. Th…
Electron paramagnetic resonance and magnetic circular dichroism of Gd3+ ions in oxyfluoride glass–ceramics containing CaF2 nanocrystals
Abstract Magnetic resonance investigations of the Gd3 + centre structure in the oxyfluoride glass and glass–ceramics (GCs) have been carried out. The electron paramagnetic resonance (EPR) measurements showed the presence of low symmetry Gd3 + centres in the glass sample. The cubic Gd3 + centre appeared in the glass–ceramics after heat treatment of the samples at temperatures above 650 °C. The magnetic circular dichroism (MCD) measurements of both glass and glass–ceramics showed wide absorption band around 310 nm. In the GC samples MCD–EPR of the cubic Gd3 + centre has been detected.
Spectroscopic studies of Cr3+ ions in natural single crystal of magnesium aluminate spinel MgAl2O4
Abstract The natural spinel crystal MgAl2O4 containing the Cr3+ ions was studied experimentally and theoretically in this paper. The absorption and emission spectra at room and low temperatures were recorded. The experimental spectroscopic results were aided with the crystal field calculations, which returned the energy level schemes of the Cr3+ ions at the Al sites with the local D3d symmetry. Effects of the trigonal crystal field were clearly seen in the calculated results, which were compared with the experimental spectra to yield a good agreement between both data sets.
Fast Luminescence Studies of NaLaF4: Pr3+ Glass Ceramics
Cathodoluminescence (CL) emission and photoluminescence (PL) emission and excitation spectra of $16\mathbf{Na}2\mathbf{O}-9\mathbf{NaF}-5\mathbf{LaF}_{3}-7\mathbf{Al}_{2}\mathbf{O}_{3}-63\mathbf{SiO}_{2}$ (mol%) activated with 3% $\mathbf{PrF}_{3}$ , hereinafter referred to as $\mathbf{NaLaF}_{4}:\mathbf{Pr}_{9}^{3+}$ have been investigated. In particular, CL spectra were measured with time resolution after excitation with a 120 keV electron beam. The characteristic Pr3+ ion emission with fast decay times $\tau_{1}=1.77$ ns and $\tau_{2}=52.97$ ns at peak intensity at 406 nm were observed, which correspond well to the emission bands of the $\mathbf{Pr}^{3+}$ ion in other luminescent materia…
Local structure of gadolinium in oxyfluoride glass matrices containing SrF2 and BaF2 crystallites
Abstract Gd3 + doped aluminosilicate oxyfluoride glasses and glass-ceramics containing SrF2 and BaF2 crystallites have been studied by differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL) and electron paramagnetic resonance (EPR) spectroscopy techniques. A pronounced EPR fine structure emerges after the heat treatment of the glass matrix. EPR spectra simulations indicate the formation of cubic, tetragonal and trigonal Gd3 + centres in the studied compositions.
Luminescence properties of Eu, RE3+ (RE = Dy, Sm, Tb) co-doped oxyfluoride glasses and glass–ceramics
Abstract Eu, RE3+ (RE = Dy, Sm, Tb) co-doped SiO2–CaF2–Al2O3–CaO oxyfluoride glasses have been prepared by the melt quenching method. By heating the precursor glasses at 670 °C for 1 h, glass–ceramics containing CaF2 nanocrystallites were obtained. DTA and XRD measurements were performed. Excitation spectra of the prepared samples as well as photoluminescence spectra at the excitation of 355 nm and 450 nm were measured, CIE colour coordinates and colour rendering indexes were found. In the glass–ceramics the presence of Eu2+ ions was observed by a broad emission band in the 400–500 nm spectral range. The most promising doping combinations for white light luminophores within our research are…
Time-resolved luminescence of YAG:Ce and YAGG:Ce ceramics prepared by electron beam assisted synthesis
Abstract The luminescence characteristics of YAG:Ce and YAGG:Ce ceramic phosphors produced by electron beam assisted synthesis have been investigated. The obtained emission and decay kinetics characteristics have been compared with those for commercial phosphors synthesized by conventional methods and showed good qualitative and quantitative correspondence. In our opinion, the used electron-beam-assisted synthesis method could be considered as a perspective production method of high refractory multicomponent oxide ceramics.
Multisite formation in gadolinium doped SrF2 nanoparticles
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