• Electrical & Electronic Materials
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• v.10 no.8
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• pp.763-769
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• 1997

In this study we have synthesized Zno:Eu phosphors under various sintering atmospheres and temperatures. The analysis of X-ray diffractometer measurement indicates that for Zno:EuCl$_3$ phosphors sintered in air and vacuum 뗘 exists in the host lattice as Eu$_2$O$_3$and EuOCl respectively. From the photoluminescence for the phosphors sintered in vacuum Eu removes the broad-band emission of the ZnO host consequently isolating the red emission due to Eu$^{3+}$ ion and improves the color purity of red emission. The photoluminescence excitation and time resolving spectrum measurements suggest that energy-transfer process occurres from the self-activated defect center in ZnO host the Eu$^{3+}$ ion which exist in the host lattice in the form of EuOCl.

• Journal of the Semiconductor & Display Technology
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• v.18 no.1
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• pp.48-52
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• 2019

The blue emitting fluorescence of $SrAl_{12}O_{19}:Ce_{0.09}{^{3+}}$, $Eu_{0.01}{^{2+}}$ phosphor includes two kinds of independent energy transfer mechanism through electric multipole interactions between donor and acceptor ions. The first energy transfer takes place between the $Ce^{3+}$ ion and the $Eu^{2+}$ion which strongly depends on the concentration $Eu^{2+}$ions. The second energy transfer occurs between the $Ce^{3+}$ ion and the $O_{Me}-Ce^{3+}$ complexes. Both energy transfer mechanisms of blue emitting peak at 410 nm were investigated by fitting of Gaussian functions. The result shows that the peak at 410 nm is two overlapping emissions originated by $Eu^{2+}$ions and $O_{Me}-Ce^{3+}$ complexes and as time elapses $Eu^{2+}$peak remains whereas $O_{Me}-Ce^{3+}$ related peak disappears.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.239-242
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• 2009

$Sr_2Si_5N_8:Eu^{2+}$, one of the most recently developed phosphors for use in white light emitting diodes, exhibits a two-peak emission. Namely, the emission band of $Sr_2Si_5N_8:Eu^{2+}$ is deconvoluted into two Gaussian peaks irrespective of the $Eu^{2+}$ concentration. We examined the two-peak emission of $Sr_2Si_5N_8:Eu^{2+}$ by analyzing the time-resolved photoluminescence spectra. We revealed that the two-peak emission was closely associated with the energy transfer taking place between $Eu^{2+}$ activators located at two different crystallographic sites in the $Sr_2Si_5N_8$ structure. The experimental results coincided well with the rate equation model involving the crystallographic information of the host.

• Analytical Science and Technology
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• v.8 no.2
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• pp.125-129
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• 1995

The energy transfer is observed in double-activator-doped LaOCl:Pr, Tb and LaOCl:Pr, Eu system. From laser excitation and fluorescence spectra, a peculiar process for energy transfer between the activators is found. The energy absorbed by $Tb^{3+}$ is directly transferred to $Pr^{3+}$ ion. A cascade relaxation of an excited $Pr^{3+}$ level to lower level, $^1D_2$ is induced by $Eu^{3+}$, $Tb^{3+}$, which has $^7F_J$ ground levels like $Eu^{3+}$ ion, does not affect the cascade relaxation. The result represents that the quantum state of ion is not absolute condition for the energy transfer and that the energy transfer is competitive between levels of activator when the activator ions are closely located.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.445-451
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• 2019

The fluorescence intensity and fluorescence lifetime of $Ba_2GdV_3O_{11}$, a vanadate compound based on $Ba^{2+}$ ion, were investigated by adding $Eu^{3+}$ as a rare earth ion which is an alkaline earth metal, which is distributed around active ions and has a large influence on fluorescent properties when used as a host in a phosphor. $Ba_2GdV_3O_{11}:Eu^{3+}$ phosphor was synthesized by solid state method and the crystallinity of the phosphor was confirmed by X - ray diffraction analysis. The fluorescence properties of the $Ba_2GdV_3O_{11}:Eu^{3+}$ phosphor were measured using optical and laser. The energy transfer and diffusion of the $Ba_2GdV_3O_{11}:Eu^{3+}$ phosphor are highly dependent on the concentration of $Eu^{3+}$. When the concentration of $Eu^{3+}$ is low, it shows strong fluorescence to the CT band. However, as the concentration of $Eu^{3+}$ increases, the fluorescence due to 4f - 4f transition is strong. The concentration of $Eu^{3+}$ ion increased and the energy between ions was diffused, and the lifetime of fluorescence decreased. Energy transfer occurs between two $Eu^{3+}$ ions at low $Eu^{3+}$ concentration and energy diffusion occurs at high $Eu^{3+}$ concentration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.6
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• pp.527-530
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• 2007

[ $SrTiO_3$ ] red phosphors doped with Pr, Er and Al were synthesized by solid state reaction method. Three emission peaks in photoluminescence spectra of the $SrTiO_3:Eu$ Phosphors were observed at 583 nm, 610 nm and 685 nm. The emission peaks in the $SrTiO_3:Eu$ phosphors were associated with charge-transfer states. The decrease of photoluminescence intensity in $SrTiO_3:Eu,Al$ phosphors with doping Al ions was interpreted by the change of charge-transfer states.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.49-54
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• 2016

$SrAl_{12}O_{19}:Ce_x{^{3+}}$,$Eu_{0.01}{^{2+}}$ phosphors were synthesized through a combustion process and their optical properties were investigated using time-resolved photoluminescence. A PL spectrum showed two dominant peaks which appeared at 300 and 410 nm. It is seen that, as the $Ce^{3+}$ concentration increases, the intensity of 300 nm decreases and the intensity of 410 nm increases. This behavior has been explained by two independent energy transfer mechanism. The first energy transfer occurs from $Ce^{3+}$ ion to $Eu^{3+}$ ion. The second energy transfer takes place from $Ce^{3+}$ ion to $Ce^{3+}-O_{ME}$ complex created in the magnetoplumbite structural host materials. The blue emitting 410 nm peak has been explained by both energy transfer mechanisms.

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.82-89
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• 1989

The fluorescence of $Eu^{3+},\;Tb^{3+}$ substituted for $La^{3+}$ in Lanthanum Oxychloride (LaOCl) has been studied. The fluorescence intensity of the $Eu^{3+},\;Tb^{3+}$ in LaOCl excited by Ultra-violet light were investigated on its activator concentration and discussed as the energy transfer process. The energy transfer from $Tb^{3+}\;to\;Eu^{3+}$ take place in the $Eu^{3+}\;and\;Tb^{3+}$ codoped LaOCl crystal. This process was confirmed to the change of concentration and the measurement of fluorescence decay time.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.346-352
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• 2008

Eu sites and the effect of Mg codoping were investigated in Eu-implanted GaN films. Photoluminescence (PL) and PL excitation spectroscopies were performed on 620nm $^5D_0\;{\rightarrow}\;^7F_2$ Eu ionic level transition and revealed the existence of 4 different Eu sites including the known 2 sites. PL intensity from one of the sites increased by a factor of 1.6 by the Mg-codoping. The enhancement of PL by Mg-codoping was less pronounced than Er- and Nd-implanted GaN, in which the trap-mediated energy transfer dominates. In GaN:Eu the above-gap excitation transfers the energy directly to the Mg related Eu site.

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.234-238
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• 2009

In the excitation spectra of $YNbO_4$ : $Eu^{3+}$, the charge transfer (CT) band around 270 nm due to $[NbO_4]^{3-}$$-Eu^{3+}$ interaction and sharp excitation peaks by f-f transition of $Eu^{3+}$ strongly appeared simultaneously. CT band depended on the structural properties of powders, showing the red-shift with increasing the crystallinity, while the f-f transition peaks were independent of the crystallinity. For $YNb_{1-x}Ta_xO_4$ : $Eu^{3+}$ (x = 0.05.0.2), $[TaO_4]^{3-}$. configuration was locally constructed, leading to the blue-shift in CT band and the decrease in the red emission intensity with increasing the Ta content.