• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.257-259
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• 2002

As a new host material for a red phosphor for PDP applications, has studied (Y,Gd)$Al_3(BO_3)_4$ which gives non-centrosymmetric sites for $Eu^{3+}$ activators. Vacuum ultraviolet (VUV) excitation spectrum of new red phosphor (Y,Gd)$Al_3(BO_3)_4$:$Eu^{3+}$ has two broad bands. One band with the absorption edge at ca. 168 nm is the band-gap absorption of aluminoborate and the other broad band centered 240 nm is the charge transfer transition between $Eu^{3+}$ and the neighboring oxygen anions. The PL spectrum shows the strongest emission at 617 nm due to the electric dipole $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$, whose luminescent chromaticity is (0.67, 0.33).

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.25-30
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• 2002

The M/sub 1-x/Na/sub 2x/Al₂(BO₃)₂O (M = Ca and Sr) solid solution systems have been shown interstitial solid solutions and continuous substitutional solid solutions. The symmetry around the Eu site of yEu/sup 3+/ : M/sub 1-x/Na/sub 2x/Al/sub 2-y/Mg/sub /(BO₃)₂O (M = Ca and Sr) changes the intensities and the chromaticities of transitions. The Eu/sup 3+/ion can be very bright and efficient and have the desired emission wave-length depending on the site symmetry of the Eu/sup 3+/ion site. As the amount of Na in the Eu/sup 3+/ion doped Ca/sub 1-x/Na/sub 2x/Al₂(BO₃)₂O system increases, the Eu site symmetry is going to be a noncentrosymmetric site. With increasing x, the decreased intensity in the /sup 5/D/sub 0/→/sup 7/F₁(590 nm) transition relates to the low symmetry of the Eus/up 3+/-doped Ca/sub 1-x/Na/sub 2x/Al₂(BO₃)₂O system, because of the Ca-centered octahedron in the CaAl₂(BO₃)₂O compound. The SrAl₂(BO₃)₂O compound also provides an improved chromaticity due to the lower site symmetry of Eu/sup 3+/ion.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.737-743
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• 1998

The synthesis of $SrAI_2O_4:Eu^{2+}$ phosphor and its properties of both photoluminescence and long-phosphorescent were investigated as a function of sintering condition. Single phase of $SrAl_2O_4$ was obtained by sintering the mixtures of $SrCO_3$, $Eu_2O_3$, $AI_2O_34 and 3wt% $B_2O_3$ powders over 100$0^{\circ}C$ in Ar/H2 atmosphere. The optimum sintering condition for the long-phosphorescent phosphor of $SrAI_2O_4:Eu^{2+}$ was found at 130$0^{\circ}C$ for 3hours. The PL emission spectrum of $SrAI_2O_4:Eu^{2+}$ shows a maximum peak intensity at 520nm(2.384eV) with a broad emission extending from 450 to 650nm which resulted from the $4f^65d^1$$\rightarrow$$4f^7$ transition of $Eu^{+2}$ under 360nm exitation. Monitored at 520nm. the excita¬tion spectrum of $SrAI_2O_4:Eu^{2+}$ exhibits a maximum peak intensity at 360nm (3.44eV) with a broad absorption band extending from 250 to 480nm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.210-213
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• 2002

The blue phosphor, $BaMgAl_{10}O_{17}$:$Eu^{2+}$, showing a blue emission band at about 450 nm were prepared by solid state reaction of BaC $O_3$, A $l_2$ $O_3$, MgO and E $u_2$ $O_3$ with Al $F_3$ as a flux. The thermal quenching of BaMgAl $O_{17}$:E $u^{2+}$ phosphor significantly reduces the intensity of the blue emission. It is reduced by an amount of 50% after heating at around 800$^{\circ}C$ for 1 hr. The red emission in the 580∼720 nm region of $^{5}$ $D_{0}$\longrightarro $w^{7}$ $F_1$ and $^{5}$ $D_{0}$\longrightarro $w^{7}$ $F_2$ transition of $Eu^{3+}$ is produced from the phosphor heated above 1,100$^{\circ}C$. The EPR spectrum also reveals that some part of E $u^{2+}$ ions are oxidized to trivalent ions above 1,100$^{\circ}C$ at around 90 and 140mT. This oxidation evidence is also detected from XANES absorption spectra for $L_{III}$ shell of Eu ions: an absorption peak is at 6,977eV of E $u^{2+}$ and 6,984eV of $Eu^{3+}$. The combined X-ray and neutron data suggests that the new phase of EuMgA $l_{11}$ $O_{19}$ magnetoplumbite structure may be formed by heat treatment.eat treatment.tment.eat treatment.tment.t.

• Korean Journal of Materials Research
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• v.32 no.10
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• pp.425-428
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• 2022

In this study, Y₃Al₅O₁₂:Eu³⁺ red phosphors were synthesized at different temperatures using a solid state reaction method. The crystal structures, surface and optical properties of the Y₃Al₅O₁₂:Eu³⁺ red phosphors were investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and photoluminescence (PL) analyses. From XRD results, the crystal structure of the Y₃Al₅O₁₂:Eu³⁺ red phosphors was determined to be cubic. The maximum emission spectra were observed for the Y₃Al₅O₁₂:Eu³⁺ red phosphor prepared by annealing for 4h at 1,700 ℃. The 565~590 nm photoluminescent spectra of the Y₃Al₅O₁₂:Eu³⁺ red phosphors is associated with the ⁵D₀ → ⁷F₂ magnetic dipole transition of the Eu³⁺ ions. The intensity of the photoluminescent spectra in the red phosphors is more dominant for the magnetic dipole transition than the electric dipole transition with increasing annealing temperature. The International Commission on Illumination (CIE) coordinates of Y₃Al₅O₁₂:Eu³⁺ red phosphors prepared by 1,700 ℃ annealing temperature are X = 0.5994, Y = 0.3647.

• Korean Journal of Materials Research
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• v.22 no.3
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• pp.145-149
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• 2012

Red phosphors of $Gd_{1-x}Al_3(BO_3)_4:{Eu_x}^{3+}$ were synthesized by using the solid-state reaction method. The phase structure and morphology of the phosphors were measured using X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM), respectively. The optical properties of $GdAl_3(BO_3)_4:Eu^{3+}$ phosphors with concentrations of $Eu^{3+}$ ions of 0, 0.05, 0.10, 0.15, and 0.20 mol were investigated at room temperature. The crystals were hexagonal with a rhombohedral lattice. The excitation spectra of all the phosphors, irrespective of the $Eu^{3+}$ concentrations, were composed of a broad band centered at 265 nm and a narrow band having peak at 274 nm. As for the emission spectra, the peak wavelength was 613 nm under a 274 nm ultraviolet excitation. The intensity ratio of the red emission transition ($^5D_0{\rightarrow}^7F_2$) to orange ($^5D_0{\rightarrow}^7F_1$) shows that the $Eu^{3+}$ ions occupy sites of no inversion symmetry in the host. In conclusion, the optimum doping concentration of $Eu^{3+}$ ions for preparing $GdAl_3(BO_3)_4:Eu^{3+}$ phosphors was found to be 0.15 mol.

• Korean Journal of Materials Research
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• v.24 no.12
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• pp.658-662
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• 2014

$Eu^{2+}/Dy^{3+}$-doped $Sr_2MgSi_2O_7$ powders were synthesized using a solid-state reaction method with flux ($NH_4Cl$). The broad photoluminescence (PL) excitation spectra of $Sr_2MgSi_2O_7:Eu^{2+}$ were assigned to the $4f^7-4f^65d$ transition of the $Eu^{2+}$ ions, showing strong intensities in the range of 375 to 425 nm. A single emission band was observed at 470 nm, which was the result of two overlapping subbands at 468 and 507 nm owing to Eu(I) and Eu(II) sites. The strongest emission intensity of $Sr_2MgSi_2O_7:Eu^{2+}$ was obtained at the Eu concentration of 3 mol%. This concentration quenching mechanism was attributable to dipole-dipole interaction. The $Ba^{2+}$ substitution for $Sr^{2+}$ caused a blue-shift of the emission band; this behavior was discussed by considering the differences in ionic size and covalence between $Ba^{2+}$ and $Sr^{2+}$. The effects of the Eu/Dy ratios on the phosphorescence of $Sr_2MgSi_2O_7:Eu^{2+}/Dy^{3+}$ were investigated by measuring the decay time; the longest afterglow was obtained for $0.01Eu^{2+}/0.03Dy^{3+}$.

• Applied Science and Convergence Technology
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• v.26 no.2
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• pp.26-29
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• 2017

Thin films of europium-doped yttrium oxide ($Y_2O_3$:Eu) were prepared on Si (100) substrates by using a radio frequency (RF) magnetron sputtering. After the deposition, the films were annealed at $1000^{\circ}C$ in an air ambient for 1 hour. X-ray diffraction analysis revealed that the $Y_2O_3$:Eu films had a polycrystalline cubic ${\alpha}-Y_2O_3$ structure. The as-deposited films showed no photoluminescence (PL), which was due to poor crystalline quality of the films. The crystallinity of the $Y_2O_3$:Eu films was significantly improved by annealing. The strong red PL emission was observed from the annealed $Y_2O_3$:Eu films and the highest intensity peak was centered at around 613 nm. This emission peak originated from the $^5D_0{\rightarrow}^7F_2$ transition of the trivalent Eu ions occupying the $C_2$ sites in the cubic ${\alpha}-Y_2O_3$ lattice. The broad PL excitation band was observed at wavelengths below 280 nm, which was attributed to the charge transfer transition of the trivalent Eu ion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.5
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• pp.204-209
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• 2007

We synthesized a series of $CaS_{1-x}Se_x:Eu$ red-emitting phosphors for application in phosphor-converted three-band white light emitting diode(LED). The photoluminescence and structural properties of $CaS_{1-x}Se_x:Eu$ were examined. The $CaS_{1-x}Se_x:Eu$ phosphors have a strong absorption at 455 nm, which is the emission wavelength of a blue LED. CaS:Eu has a red omission peak at 651 nm due to the $4f^65d^1(T_{2g}){\rightarrow}4f^7(^8S_{7/2})$ transition of the $Eu^{2+}$. The emission peak of $CaS_{1-x}Se_x:Eu$ is shifted from 651 to 598 nm with increasing Se content. $CaS_{1-x}Se_x:Eu$ can be used as wavelength-tunable red-emitting phosphors pumped by a blue LED. We also fabricated a three-band white LED by doping $SrGa_2S_4:Eu$ and $CaS_{0.50}Se_{0.50}:Eu$ phosphors onto a blue LED chip.

• Journal of the Korean Chemical Society
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• v.45 no.6
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• pp.570-576
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• 2001

The europium doped yttrium oxybromide phosphors were synthesized by solid-state reaction method. The YOBr: $Eu^{3+}$ phosphor showed a strong and narrow red emission band at 621 nm and maximum emission intensity obtained when 0.05 mol Eu ions were doped. The red emission of $Eu^{3+}$ originated from $^5D_0$ ${\rightarrow}$ $^7F_2$electric dipole transition. In order to investigate on photoluminescence behavior, several experimental skills and numerical fittings are conducted to the YOBr: $Eu^{3+}$ phosphor. The emission spectrum was measured in the UV range and then decay curve of $^5D_0$ ${\rightarrow}$ $^7F_j$transitions was examined. The energy interaction type of YOBr: $Eu^{3+}$ phosphor was dipole-dipole interaction. In addition to the calculating by critical concentration, the critical distance ($R_0$) was calculated by decay curve fitting parameter from Inokuti-Hirayamas equation, and spectral overlap method. The critical distance was 17.03, 10.51 and 7.18$\AA$ for those methods, respectively. As considering systematic error of measurements, these values are within the same order, so that the above fitting methods are plausible and recommendable.