• Korean Journal of Materials Research
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• v.13 no.6
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• pp.343-346
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• 2003

Photoluminescence(PL), photostimulated luminescence(PSL) and thermoluminescence(TL) in $SrC1_2$:$Eu^{2+}$ , $Na^{+}$ phosphor powder were measured, and the activation energies(trap depth) of traps associated with TL and PSL were investigated. The PL and PSL in the studied sample is due to the $4f^{6}$ 5d\longrightarrow$4f^{7}$transition of $Eu^{ 2+}$. TL glow curve is single peak, and its peak temperature is about 377.2 K. The PL, PSL and TL emission spectra of the phosphors are located in the range of 380∼440 nm, peaking at 408 nm. The activation energy of the PSL trapping center is 0.78 eV and that of the TL trapping center is 0.79 eV. We, thus, suggest that the trapping centers giving rise to the PSL are identical to those giving rise to the TL.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.31-34
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• 2013

Trivalent cerium-ion-doped $Y_3(Al,\;Ga)_5O_{12}$ nanoparticle phosphor nanoparticles were synthesized using the reverse micelle process. The Ce doped $Y_3(Al,\;Ga)_5O_{12}$ particles were obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase and poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant. The crystallinity, morphology, and thermal properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were characterized by thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy. The crystallinity, morphology, and chemical states of the ions were characterized; the photo-physical properties were studied by taking absorption, excitation, and emission spectra for various concentrations of cerium. The photo physical properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were studied by taking the excitation and emission spectra for various concentrations of cerium. The average particle size of the synthesized YAG powders was below $1{\mu}m$. Excitation spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ samples were 485 nm and 475 nm, respectively. The emission spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ were around 560 nm and 545 nm, respectively. $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ is a red-emitting phosphor; it has a high efficiency for operation under near UV excitation, and may be a promising candidate for photonic applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.441-442
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• 2008

For this study, Yttrium aluminum garnet (YAG) particles co-doped with $Ce^{3+}$ and $Eu^{3+}$ were prepared via the combustion process using the 1:1 ratio of metal ions to reagents. The characteristics of the synthesized nano powder were investigated by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), and photoluminescence (PL). The various YAG peaks, with the (420) main peak, appeared at all Eu concentrationin XRD patterns. The YAG phase crystallized with results that are in good agreement with the JCPDS diffraction file 33-0040. The SEM image showed that the resulting YAG:Ce,Eu powders had uniform sizes and good homogeneity. The grain size was about 50nm. The photoluminescence spectra of the YAG:Ce,Eu nanoparticles were investigated to determine the energy level of electron transition related to luminescence processes. It was composed a broad band of $Ce^{3+}$ activator into the weak line peak of $Eu^{3+}$ in YAG host. The PL intensity of $Ce^{3+}$ has the wavelengths of 480-650 nm and The PL intensity of $Eu^{3+}$ has main peak at 590nm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.67-74
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• 2002

A phosphor for Plasma Display Panel, BaMgAl$_{10}$ O$_{17}$ :Eu$^{2+}$, showing a blue emission band at about 450nm was prepared by a solid-state reaction using BaCO$_3$, $Al_2$O$_3$, MgO, Eu$_2$O$_3$ as starting materials wish flux AlF$_3$. The study of the behaviour of Eu in BAM phosphor was carried out by the photoluminescence spectra and the Rietveld method with X-ray and neutron powder diffraction data to refine the structural parameters such as lattice constants, the valence state of Eu, the preferential site of Mg atom and the site fraction of each atom. The phenomenon of the concentration quenching was abound 2.25~2.3wt% of Eu due to a decrease in the critical distance for energy transfer of inter-atomic Eu. Through the combined Rietveld refinement, R-factor, R$_{wp}$, was 8.11%, and the occupancy of Eu and Mg was 0.0882 and 0.526 at critical concentration. The critical distance of Eu$^{2+}$ in BAM was 18.8$\AA$ at 2.25% Eu of the concentration quenching. Furthermore, c/a ratio was decreased to 3.0wt% and no more change was observed over that concentration. The maximum entropy electron density was found that the modeling of $\beta$-alumina structure in BaMgAl$_{10}$ O$_{17}$ :Eu$^{2+}$correct coincided showing Ba, Eu, O atoms of z= 1/4 mirror plane.e.ane.e.

• Journal of the Korean Magnetics Society
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• v.15 no.4
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• pp.246-249
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• 2005

The blue-color emitting phosphor powder, $CaMgSi_{2}O_6:Eu^{2+}(CMS:Eu^{2+})$ was synthesized by the solid-state reaction method. The synthesized powder was annealed from room temperature to $1,100^{\circ}C$ in air. Its PL property and valence state of Eu atoms was measured by the photoluminescence (PL) and the electron paramagnetic resonance (EPR) spectrometers, respectively. The PL intensity was stable to $700^{\circ}C$, but drastically decreased to $1,100^{\circ}C$. The behavior of EPR intensity was very similar to the PL intensity. The EPR measurement showed that decreased intensity of the PL was caused to the oxidation from the ion $Eu^{2+}$ to $Eu^{3+}$ ions. The EPR spectrometer was powerful as a tool that could distinguish between the valence states of Eu atom as a dopant in various phosphors.