• Journal of the Korean Chemical Society
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• 제50권2호
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• pp.137-140
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• 2006

In this report, Europium doped strontium barium gallium silicate ((Sr,Ba)2Ga2SiO7:Eu2+) phosphor has been synthesized by conventional solid-state method and investigated luminescent characteristic. Appropriate proportions of the raw materials were mixed in an agate mortar with acetone to obtain starting mixtures. Also, this phosphor was prepared by simple process under the reduction atmosphere (25% H2/75% N2). This phosphor can be applicated to the green phosphor for white LED because it has green emission band (513 nm), which emits efficiently under the 405nm excitation energy.

• Transactions on Electrical and Electronic Materials
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• 제4권5호
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• pp.28-32
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• 2003

Europium-doped gadolinium oxide ($Gd_2O_3;Eu^{3+}$) phosphors have been prepared by combustion method using urea[H$_2$NCONH$_2$] or carbohydrazide[H$_2$NNHCONHNH$_2$] as fuel materials in a preheated furnace at 500$^{\circ}C$. The phosphors obtained were fired at 1200$^{\circ}C$ for 3 hours to get better luminescent properties. The combustion method used was found to be a simple and fast method for the preparation of fine-sized particles. The influence of the fuel/oxidant (urea or carbohydrazide/nitrate) mole ratio on the phosphor has been investigated and the optimum values for various parameters have been determined. By this method, phosphor that has better brightness and smaller size particles than that obtained by conventional method has been prepared.d has been prepared.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.200-203
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• 2003

Ferroelectric europium-substitution $Bi_4Ti_3O_{12}$ thin films were fabricated by spin-coating onto a Pt/Ti/$SiO_2$/Si substrate. The $Bi_{3.25}Eu_{0.75}Ti_3O_{12}$ (BET) films have polycrystalline structure annealed at 700 C. We investigated that the influence of $Bi_4Ti_3O_{12}$ thin films by substituting for Bi ions with Bi ions using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). From the XPS measurement, it was suggested that the stability of the metal-oxygen octahedral should be related to substitute for Bi ions with Eu ions at annealed $800^{\circ}C$. The BET thin films showed a large remanent polarization (2Pr) of $60.99C/cm^2$ at an applied voltage of 10 V. The BET thin films exhibited no significant degradation of switching charge at least up to $5{\times}10^9$ switching cycles at a frequency of 50 kHz.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.109-116
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• 2018

$Eu_2(SO_4)_3$ was synthesized by chemical precipitation method and the crystal structure was determined by Rietveld analysis. The compound crystallizes in monoclinic space group C2/c. In the air environment, $Eu_2(SO_4)_3$ is stable up to $670^{\circ}C$. The sample of $Eu_2(SO_4)_3$ was examined by Raman, Fourier-transform infrared absorption and luminescence spectroscopy methods. The low site symmetry of $SO_4$ tetrahedra results in the appearance of the IR inactive ${\nu}_1$ mode around $1000cm^{-1}$ and ${\nu}_2$ modes below $500cm^{-1}$. The band intensities redistribution in the luminescent spectra of $Eu^{3+}$ ions is analyzed in terms of the peculiarities of its local environment.

• Journal of the Semiconductor & Display Technology
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• 제23권1호
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• pp.88-91
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• 2024

The europium doped yttrium oxide (Y₂O₃:Eu³⁺) thin film was formed on a Si substrate by the conventional spin-coating process followed by rapid thermal annealing (RTA) treatment. The spinning profiles such as rotation speed, acceleration and holding times were controlled during the spin-coating process for the best condition of the Y₂O₃:Eu³⁺ thin film. The RTA treatment was conducted for several temperature in order to crystallize the spin coated film. The Y₂O₃:Eu³⁺ thin film presented best performance in the conditions of 4000 rpm, 30 s and 10 s of rotation speed, acceleration time and holding time, respectively, at a fixed RTA temperature of 900 ℃.

• Journal of Sensor Science and Technology
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• 제6권1호
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• pp.16-23
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• 1997

Bismuth germanate crystals well known as scintillator were grown by Czochralski method. In order to understand a mechanism of radiation resistance in Eu-doped BGO, we measured radiation induced-absorption spectra, excitation spectra, emission spectra and luminescence lifetimes of BGO crystals. We found that the charge transfer state of $Eu^{3+}$ ion is to play a key role to enhance the radiation resistance in BGO crystal. The $^{5}D_{0}$ emission of $Eu^{3+}$ ions that is not suitable for the radiation detectors due to a long decay time was found to be increased with increasing europium concentration. In the BGO crystal doped with 0.1 mole%, the density of radiation induced color centers was reduced about twenty times and the light output of $^{5}D_{0}$ was negligible by comparing to that of BGO.

• Bulletin of the Korean Chemical Society
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• 제26권12호
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• pp.1969-1974
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• 2005

Composite systems of $Eu(phen)_2Cl_3{(H_2O)}_2$, Eu(DN-bpy)$(phen)Cl_3{(H_2O)}_2$ and Eu(DB-bpy)$(phen)Cl_3{(H_2O)}_2$ (DNbpy: $4,4^\prime$-Dinonyl-$2,2^\prime$-dipyridyl; DB-bpy: $4,4^\prime$-Di-tert-butyl-$2,2^\prime$-dipyridyl) with crown ethers of Benzo-15-crown-5 (B15C5), Benzo-18-crown-6 (B18C6), 18-crown-6 (18C6), Dibenzo-18-crown-6 (DB18C6) and Dibenzo-24-crown-8 (DB24C8) were fabricated successfully and characterized by using photoluminescent spectroscopy and luminescent lifetime measurements. All composites formed show high luminescence mainly in red region. It was found that the heterocyclic ligands such as phen, DN-bpy and DB-bpy as well as the crown ethers have great influences on the photoluminescent properties of $Eu^{3+}$ ion. The environment around $Eu^{3+}$ ion in the composite systems changes greatly,presumably the variation of the first coordination sphere. The $Eu^{3+}$ ion occupies higher symmetrical environment and in more than one kind of symmetrical site in the composite systems studied in this work.

• Korean Journal of Materials Research
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• 제16권3호
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• pp.163-167
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• 2006

The transition of europium-doped gadolinium oxide phosphor to gadolinium borate phosphor with the concentration of boron in the spray pyrolysis was investigated. The particles prepared from spray solution below 10 wt% boric acid of prepared phosphor had crystal structure of $Gd_2O_3:Eu$ phosphor, in which the crystallinity of the particles decreased with increasing the boron concentration. A single phase $GdBO_3:Eu$ phosphor particles were prepared from spray solution above 50 wt% boric acid of prepared phosphor. The phosphor particles prepared from spray solution with 20 wt% boric acid of prepared phosphor had no XRD peaks of $Gd_2O_3:Eu$ and $GdBO_3:Eu$ Therefore the phosphor particles prepared from spray solution with 20 wt% boric acid of prepared phosphor had the lowest photoluminescence intensity under ultraviolet and vacuum ultraviolet. $GdBO_3:Eu$ and $Gd_2O_3:Eu$ phosphor particles prepared from spray solutions with proper concentrations of boric acid had good photoluminescence intensity under vacuum ultraviolet. The morphology of the phosphor particles were strongly affected by the concentrations of boric acid added into spray solution.

• Journal of Powder Materials
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• 제23권5호
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• pp.348-352
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• 2016

Quantum dots (QDs) are capable of controlling the typical emission and absorption wavelengths because of the bandgap widening effect of nanometer-sized particles. These phosphor particles have been used in optical devices, photovoltaic devices, advanced display devices, and several biomedical complexes. In this study, we synthesize ZnSe QDs with controlled surface defects by a heating-up method. The optical properties of the synthesized particles are analyzed using UV-visible and photoluminescence (PL) measurements. Calculations indicate nearly monodisperse particles with a size of about 5.1 nm at $260^{\circ}C$ (full width at half maximum = 27.7 nm). Furthermore, the study results confirm that successful doping is achieved by adding $Eu^{3+}$ preparing the growth phase of the ZnSe:Eu QDs when heating-up method. Further, we investigate the correlation between the surface defects and the luminescent properties of the QDs.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제12권2호
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• pp.600-604
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• 2011

In this paper, the scintillation properties of $LaCl_3:Eu^{2+}$ crystal were investigated as new scintillator. This scintillation material was grown by a Czochralski method. $LaCl_3:Eu^{2+}$ was determined to have a hexagonal $P_63$/m space group with cell parameters a = b = $7.48{\AA}$, c = $4.37{\AA}$. Under 335 nm UV excitation, the crystal shows a broad emission band between 370 nm and 640 nm wavelength range, peaking at 430 nm. At room temperature, the crystal exhibits one exponential decay time component. The component of scintillation time profile of the crystal emission decays with a $2.82{\pm}0.72{\mu}s$ time constant. The energy resolution of the crystal was measured to be 8.8% (FWHM) for $^{137}Cs$ 662 keV ${\gamma}$-rays.