• Journal of Powder Materials
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• v.24 no.6
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• pp.457-463
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• 2017

Nanosized $Gd_2O_3:Eu^{3+}$ red phosphor is prepared using a template method from metal salt impregnated into a crystalline cellulose and is dispersed using a bead mill wet process. The driving force of the surface coating between $Gd_2O_3:Eu^{3+}$ and mica is induced by the Coulomb force. The red phosphor nanosol is effectively coated on mica flakes by the electrostatic interaction between positively charged $Gd_2O_3:Eu^{3+}$ and negatively charged mica above pH 6. To prepare $Gd_2O_3:Eu^{3+}$-coated mica ($Gd_2O_3:Eu/mica$), the coating conditions are optimized, including the stirring temperature, pH, calcination temperature, and coating amount (wt%) of $Gd_2O_3:Eu^{3+}$. In spite of the low luminescence of the $Gd_2O_3:Eu/mica$, the luminescent property is recovered after calcination above $600^{\circ}C$ and is enhanced by increasing the $Gd_2O_3:Eu^{3+}$ coating amount. The $Gd_2O_3:Eu/mica$ is characterized using X-ray diffraction, field emission scanning electron microscopy, zeta potential measurements, and fluorescence spectrometer analysis.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.6
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• pp.400-406
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• 2000

The fired Precursor (Y,Gd,Eu)(OH)$CO_3$.$H_2O$$900^{\circ}C$ was used to synthesize the red phosphor $(Y,Gd)_2O_3$: Eu for plasma display panel. Rounded and ~l $\mu\textrm{m}$ diameter phosphor $(Y,Gd)_2O_3$: Eu can be obtained by the reaction of aformentioned powder with a small amount addition of flux at $1350^{\circ}C$ for 2 hours. Emission spectra of these phosphors were measured under excitation wavelength at 254 nm and 147 nm and the optimum concentrations of activator ion were determined at around 15 mo1e % and 10 mole % under these conditions, respectively. $BaCO_3$flux had the best property in emission intensity among the prepared $BaCO_3AlF_3$and $Li_3PO_4$phosphors. The properties of optimized sample were improved in terms of relative luminance and color coordinate comparing with commercial phosphor such as $Y_2O_3$: Eu.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.6
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• pp.225-228
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• 2005

We have grown the long persistent $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ phosphor single crystal by Verneuil method. The obtained single crystals were long persistent phosphorescence peaking at ${\lambda}=520nm$ with a size of about 5 mm diameter, 55 mm length. The melting temperature of $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ measured $T_{mp}=1968^{\circ}C$. The optimum composition was $SrCO_3:Al(OH)_3:Eu_2O_3:Dy_2O_3$ = 1 : 2 : 0.015 : 0.02. Flow rate of $H_2:O_2$ is about 4 : 1. Growthing rate is about 5 mm/hr. The spectra of the phosphorescence from the crystals are quite similar to those obtained with sintered powders used for luminous pigments. The crystalline structure of long persistent $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ phosphor single crystal was determined by X-ray diffraction.

• Journal of the Korean Chemical Society
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• v.44 no.4
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• pp.350-355
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• 2000

The compounds, CaAl$_2$(BO$_3$)$_2$O, SrAl$_2$(BO$_3$)$_2$O and BaAl$_2$(BO$_3$)$_2$O, are good host lattices for highly efficient $Eu^{2+}$ luminescence. The europium emission peaks at 450 nm in $Eu^{2+}$:CaAl$_2$(B0$_3$)$_2$O, 411 nm in $Eu^{2+}$: SrAl$_2$(BO$_3$)$_2$O and 375 nm in $Eu^{2+}$: BaAl$_2$(BO$_3$)$_2$O. The $Eu^{2+}$: CaAl$_2$(BO$_3$)$_2$O Phosphor shows a high output and should be a good maintenance in VUV Xe lamps. It is ideally suited for use in PDP phosphors. The $Eu^{2+}$ ion is interesting because the Stokes shift emission is a strong host dependent. The difference in the Stokes shift is oneimportant factor leadingto a difference in wavelength. If the 5d level of $Eu^{2+}$ ion is lower in energy,according to a decrease in the doping lattice size, then the emission wavelength will be longer and the Stokes shift will be smaller. Therefore, a knowledge of the relationship between the crystal lattice size and the Stokes shift. (orthe energy of the 5d level),is essential for beingable to predict $Eu^{2+}$ emission properties.

• Journal of Sensor Science and Technology
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• v.11 no.6
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• pp.371-377
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• 2002

$Y_2O_3:Eu^{3+}$ and Li-doped $Y_2O_3:Eu^{3+}$ thin films have been grown on sapphire substrates using a pulsed laser deposition technique. The thin film phosphors were deposited at a substrate temperature of $600^{\circ}C$ under the oxygen pressure of 100, 200 and 300 mTorr. The films grown under different deposition conditions have been characterized using microstructural and luminescent measurements. The crystallinity and photoluminescence (PL) of the films are highly dependent on the oxygen pressure. The PL brightness data obtained from $Y_2O_3:Eu^{3+}$ films grown under optimized conditions have indicated that sapphire is one of the most promising substrate for the growth of high quality $Y_2O_3:Eu^{3+}$ thin film red phosphor. In particular, the incorporation of $Li^{+}$ ions into $Y_2O_3$ lattice could induce a remarkable increase of PL. The highest emission intensity was observed with LiF-doped $Y_{1.84}Li_{0.08}Eu_{0.08}O_3(Y_2O_3LiEu)$, whose brightness was increased by a factor of 2.7 in comparison with that of $Y_2O_3:Eu^{3+}$ films. This phosphor may promise for application to the flat panel displays.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.144.1-144
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• 2003

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.272-279
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• 2015

$Y_2O_3:Eu^{3+}$ is an excellent red-emitting phosphor, which has been widely used for display devices due to highly luminescent property and chemical stability. In this study, $Y_2O_3:Eu^{3+}$ red phosphors were prepared using the solid state reaction and RF thermal plasma synthesis. The particle size of $Y_2O_3:Eu^{3+}$ phosphors obtained by the solid state reaction varied from 10 to $20{\mu}m$, and 30~100 nanometer sized $Y_2O_3:Eu^{3+}$ particles were obtained from a liquid form of raw material through RF thermal plasma synthesis without an additional heat treatment. Photoluminescence measurements of the obtained $Y_2O_3:Eu^{3+}$ particles showed a red emission peak at 611 nm ($^5D_0{\rightarrow}^7F_2$). PL intensity of red nano phosphors prepared by RF thermal plasma synthesis was comparable to that of red phosphors prepared by the solid state reaction, indicating that nano-sized $Y_2O_3:Eu^{3+}$ red phosphors could be successfully synthesized using one-step process of RF thermal plasma.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.111-116
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• 2003

The red emitting phosphors for low voltage cathode luminescent, fine $(Y,Gd)_2O_2$S : Eu powders were synthesized and investigated the effect of $Gd^{3+}$as sensitizer at variety of sintering temperature. The highly intense emission line of $(Y,Gd)_2O_2$S : Eu at 627 nm is attributed in the transition from $^5D_o to ^7F_2$ energy levels. It showed the maximum value at the doping level of 5 mole% of $Gd^{3+}$at $950^{\circ}C$ of sintering temperature and then, it was degraded rapidly. The mean particle size of $(Y,Gd)_2O_2$S : Eu was obtained around 1 fm and the cathode luminescent properties of (Y,Gd)$_2$O$_2$S : Eu were better than those of $(Y,Gd)_2O_2$S : Eu.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1062-1065
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• 2003

본 연구에서는 초미세 $Y_2O_3:EU^{3+}$ 분말을 이용하여 나노 형광체를 제조하였다. 나노 형광체는 소량의 Eu가 도핑된 $Y_2O_3$ 재질로 구성되어 있다. 형광체 분말의 결정화를 위해 $500{\sim}900^{\circ}C$의 온도로 열처리하였다. 제조된 나노 형광체를 HRTEM으로 관찰한 결과 입자 크기가 열처리 온도에 따라 약 $4{\sim}30nm$의 분포를 나타내었다. 또한 XRD로 결정상을 분석한 결과 주로 입방정 구조로 되어 있고 소량의 단사정 구조가 포함된 $Y_2O_3$ peak가 검출되었다. EDS 분석 결과 약 $6.7{\sim}7.5%$의 Eu가 검출되었다. 약 4nm 크기의 $Y_2O_3:EU^{3+}$ 분말로 제조한 나노 형광체의 발광 특성은 주요 파장대가 612nm인 PL spectrum이 관찰되어, 적색 형광체로서의 $Y_2O_3:EU^{3+}$ 나노 분말이 제조되었다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.60-63
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• 2004

Sulfurization of rare-earth oxides R203 (R=Nd, Eu) using sulfurizing reagents, such as $H_2S$ and $SC_2$was examined for the sulfide magnetic separation of spent fuel. $EU_2O_3$was found to react with H$_3$S gas forming the mixture of $EU_2O_2S$ and EuS at 500 oC, while EuS was formed by $SC_2$ at 800 oC. In the case of the mixture of $R_2O_3$and $UO_2$, EuS and $ND_3S_4$ were formed as well as $EU_2O_2S$ and $Nd_2O_2S$ at 500oC in $H_2S$, though $UO_2$ remained unreacted.