• Journal of the Semiconductor & Display Technology
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• v.16 no.4
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• pp.86-90
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• 2017

$Tb^{3+}$ or $Eu^{3+}$ or $Ce^{3+}$-doped $CaYAlO_4$ phosphor were synthesized by solid-state method. $CaYAlO_4:Tb^{3+}$ is shown that the $Tb^{3+}$-doping concentration has a significant effect on the $^5D_4/^5D_3{\rightarrow}7F_J$ (J=6,...,0) emission intensity of $Tb^{3+}$. The $CaYAlO_4:Tb^{3+}$ phosphors show tunable photoluminescence from blue to yellow with the change of doping concentration of $Tb^{3+}$ ions. The $CaYAlO_4:Eu^{3+}$ phosphors exhibit a red-orange emission of $Eu^{3+}$ corresponding to $^5D_0$, $_{1,2}{\rightarrow}^7F_J$ (J=4,...,0) transitions. The $CaYAlO_4:Ce^{3+}$ phosphors show a blue emission due to $Ce^{3+}$ ions transitions from the 5d excited state to the $^2F_{5/2}$ and $^2F_{7/2}$ ground states. The decay time of $CaYAlO_4:Tb^{3+}$ phosphors decrease from 1.33 ms to 0.97 ms as $Tb^{3+}$ concentration increases from 0.1 mol% to 7 mol%. The decay time of $CaYAlO_4:Eu^{3+}$ phosphors increase from 0.94 ms to 1.17 ms as $Eu^{3+}$ concentration increases from 1 mol% to 9 mol%.

• Journal of the Korean institute of surface engineering
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• v.32 no.6
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• pp.665-670
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• 1999

PDP용 적색형광체는 penning가스(Ne 및 5% Xe혼합가스)에 의해 방출되는 147nm파장에서 쉽게 여기되어 논은 양자효율을 주는 물질로 이루어지는데 본 실험은 발광효율을 높이기 위하여 $Y_2$$O_3$:Eu, $(Y,Gd)_2$$O_3$:Eu 및 $(Y,Cd)BO_3$:Eu를 공침법으로 합성하여 부활제인 $Bu^{3+}$ /의 농도, Flux첨가에 따른 미시조직의 변화등을 여기 방출 스펙트럼을 통해 발광효율을 조사하여 다음과 같은 결론을 얻었다. $Y_2$$O_3$:Eu 형광체 합성시 최적조정은 $Y_2$$O_3$에 대한 $Eu_2$$O_3$의 몰비는 5:1, $BaCO_3$ 첨가시 몰비는 15:1로 나타났으며 2차 소성시 $1200^{\circ}C$이상에서 1~3$\mu\textrm{m}$의 구형입상이 형성되었으며 입자의 크기, 형상은 발광특성에 영향을 미쳤다. 또 $Eu^{ 3+}$ 농도는 7wt%가 최적조건으로 나타났다.

• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.573-577
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• 2004

We have synthesized a Eu$^{2＋}$-activated Sr$_3$MgSi$_2$ $O_{8}$ blue phosphor and investigated an attempt to develop blue LEDs by combining it with a InGaN blue LED chip (Len=405 nm). The InGaN-based Sr$_3$MgSi$_2$ $O_{8}$：Eu LED Lamp shows two bands at 405 nm and 460 nm. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This 405 nm emission was used as an optical transition of the Sr$_3$MgSi$_2$ $O_{8}$：Eu phosphor. The 460 m emission band is ascribed to a radiative recombination of Eu$^{2＋}$ impurity ions in the Sr$_3$MgSi$_2$ $O_{8}$ host matrix. As a consequence of a preparation of W blue LED Lamp using the Sr$_3$MgSi$_2$ $O_{8}$：Eu blue phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/blue phosphor(1/0,202). At this time, the CIE chromaticity was x=0.1417 and y=0.0683.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.193-200
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• 2016

Characteristics of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors synthesized by solid state reaction and polymerized complex method were comparatively analyzed. In order to evaluate thermal stability of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors at high temperature, phosphorescent properties of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ were investigated with thermal treatment at $1250^{\circ}C$ under reducing atmosphere, which was the general heat treatment conditions for ceramic manufacturing process. The phosphorescent properties of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphors synthesized by solid state reaction and polymerized complex method were investigated. The crystal structure and crystallite size were observed through XRD analysis. Microstructure and particle size of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphors were analyzed by SEM and PSA. Photoluminescence and afterglow characteristics of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors were measured by spectrofluorometer.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.39-45
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• 2015

$La_2W_3O_{12}:Eu^{3+}$ phosphors were prepared by solid state reaction method. The crystal structure was characterized by XRD pattern and ICSD card (78180). Luminescence properties of $La_2W_3O_{12}:Eu^{3+}$ are investigated by optical and laser-excitation spectroscopy in which emission and excitation spectra and time-resolved spectra are measured. The 1 mol % $Eu^{3+}$-doped $La_2W_3O_{12}$ phosphor exhibits broad excitation band peaking at 286 nm due to the ligand-to-metal charge transfer transition. The excitation lines due to the $^7F_0{\rightarrow}{^5D_4},{^5D_4},{^5L_6},{^5G_4},{^5D_3},{^5D_2}$ transitions of $Eu^{3+}$ are observed in the wavelength region 350-500 nm. The strong line emission is observed at 618 nm corresponding to the due to the $^5D_0{\rightarrow}^7F_2$ transition. The lifetime of 618 nm emission decreases with increasing temperature as 7 K ($114{\mu}s$), 100 K ($94{\mu}s$), 200 K ($10{\mu}s$) and 300 K ($0.5{\mu}s$).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.671-679
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• 2007

[ $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ ] phosphor was synthesized using the impregnation method, and its photoluminescence and long-afterglow properties were investigated, A mixture of $Sr(NO_3)_2,\;Al(NO_3)_2\;9H_2O,\;EuCl_3\;6H_2O,\;DyCl_3\;6H_2O,\;NdCl_3\;6H_2O$ salts were dissolved in distilled water and impregnating into the polymer precursor. After drying, the impregnated mixture was heat treated at $900-1400^{\circ}C$ for 2h in a $N_2-H_2$ reduction atmosphere. The microstructure and crystal structure of the $SrAl_2O_4:Eu^{2+},\;Dy^{3+}$ powders were examined by scanning electron microscopy and X-ray diffraction, respectively. The photoluminescence spectra showed an excitation band along over wide wavelength of 250-450nm, and a broaden emission with a maxima peak at 360nm. In addition, the spectra also showed a good long after glow that decayed over a 1000sec period after 10 min excitation illumination.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.166-166
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• 2000

We studied electronic structure of magnetic semiconductors EuO, EuS, and EuTe. The photoemission spectra show localized Eu 4f states and broad anion p bands. As the size of anion increases from oxygen to tellurium, anion p band width increases and eventually overlaps Eu 4f states. Hence in EuO and EuS, Eu 4f states are the highest occupied stated lying above anion p band, while Te 5p band spreads widely over Eu 4f states to become valence band maximum in EuTe. It was also observed that Eu 4f states have width of 0.7eV and dispersion of 0.2eV in EuS by angle resolved photoemission spectroscopy. The width of the 4f spectra mainly originates from atomic multiplets, but the much larger dispersion than that of Eu metal is due to p-f mixing.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.42-46
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• 2017

$SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphorescent phosphors were synthesized by skull melting method. The molar ratio of oxides in the phosphors synthesized by the skull melting technique was $SrCO_3$ : $Al(OH)_3$ : $Eu_2O_3$ : $Dy_2O_3$= 1 : 2 : 0.015 : 0.02. Crystal structure and surface morphology were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Optical properties of the synthesized $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ were measured by photoluminescence (PL) spectrometer for in-depth study on the excitation, emission and afterglow properties. From the PL measurements, it was found that excitation occurred in the wavelength range from 300 to 420 nm with peak position at 360 nm. The emission spectrum showed a broad curve in the wavelength from 450 to 600 nm with peak position at 530 nm. $SrAl_2O_4$ : $Eu^{2+}$,$Dy^{3+}$ phosphors exhibited afterglow properties with emission that lasted for a long period.

• 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.

• Journal of the Korean Society of Radiology
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• v.2 no.3
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• pp.11-18
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• 2008

In this study, the particle properties and luminescence properties of Gd2O3 nano powder with various Eu content were studied. Gd2O3:Eu nano powder was fabricated using special solvent which mixed the alcohol and the distilled water at specific ratio. This solvent by the solution method showed short fabrication time because solution time of Gd and Eu was reduced. From this experiment with Gd2O3:Eu, the particle properties og nano powder phosphor way analysed using SEM (scanning electron microscope) and EDX(Energy Dispersive X-ray). Also the luminescence properties of nano powder was measured using PL(Photoluminescence) and CL (CathodeLuminescence). The size of powder was 30nm~40nm. The magnitude of powder showed the best peak at 620nm. Among 1,3,5wt% of Eu content, the more Eu content was added in powder, the more photons wre generated. Also it shows luminescence efficiency was improved adding 5% of Eu content.