• Korean Journal of Materials Research
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• v.9 no.1
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• pp.3-7
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• 1999

The change of phosphorescent property with chemical modification and co-doping of Nd as an auxiliary activator in CaAl$_2$$O_4$: Eu\ulcorner, Nd\ulcorner phosphor, employing Nd\ulcornerion(0.6%) and an co-activator maintained its afterglow for 4.5 hours. And also the initial persistent brightness and phosphorescent property were further improved both by substituting Al by B atoms and incorporation of Nd\ulcorner ion. It was found that the persistent time was 30 hours for&Ca(Al_{0.97}\;B_{0.03}) $_2$$O_4$:EU\ulcorner(0.3%), Nd\ulcorner(0.6%) phosphor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.483-484
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• 2006

$Eu^{3+}$와 $Pr^{3+}$이 첨가된 $SrTiO_3$형광체를 고상반응법으로 제조하였다. $SrTiO_3:Pr$형광체는 $^3P_J(J=0,1,2){\rightarrow}^3H_4$에 의한 490nm 부근의 녹색발광과 $^1D_2{\rightarrow}^3H_4$에 의한 618nm 의 적색발광이 동시에 나타났다. $SrTiO_3:Eu$형광체는 $SrTiO_3:Pr$형광체와 달리 $^5D_0{\rightarrow}^7F_1$에 의한 583nm와 $^5D_0{\rightarrow}^7F_2$에 의한 610nm의 적색발광만 각각 관찰되었다. $SrTiO_3$의 모체에서 $Eu^{3+}$는 inversion sysmmetry를 가짐으로써 610nm의 electric dipole transition 보다는 583nm의 magnetic dipole transition이 강하게 일어났다.

• Advances in materials Research
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• v.3 no.4
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• pp.227-232
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• 2014

$Ce^{4+}$, $Eu^{3+}$, $Tb^{3+}$ co-doped $Ca_3Si_3O_8F_2$ phosphor was synthesized via solid state reaction method using $CaF_2$, $CaCO_3$ and $SiO_2$ as raw materials for the host and $Eu_2O_3$, $CeO_2$, and $Tb_4O_7$ as activators. The luminescent properties of the phosphor was analysed by spectrofluorophotometer at room temperature. The effect of excitation wavelengths on the luminescent properties of the phosphor i.e. under near-ultraviolet (nUV) and visible excitations was investigated. The emission peaks of $Ce^{4+}$, $Eu^{3+}$, $Tb^{3+}$ co-doped $Ca_3Si_3O_8F_2$ phosphor lays at 480(blue band), 550(green band) and 611nm (red band) under 380nm excitation wavelength, attributed to the $Ce^{4+}$ ion, $Tb^{3+}$ ion and $Eu^{3+}$ ions respectively. The results reveal that the phosphor emits white light upon nUV (380nm) / visible (465nm) illumination, and a red light upon 395nm / 535nm illumination. RE ions doped $Ca_3Si_3O_8F_2$ is a promising white light phosphor for LEDs. The emission colours can be seen using Commission international de l'eclairage (CIE) co-ordinates. A single host phosphor emitting different colours under different excitations indicates that it is a potential phosphor having applications in many fields.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1076-1078
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• 2004

In this paper, we report $Eu^{2+}$ activated green phosphor $Ba_2CaMgSi_2O_8:Eu^{2+}$. This phosphor absorbs ultroviolet radation and emits a green visible light. The phosphors were synthesized by conventional solid state reaction method. Reagent grade $BaCO_3$, $CaCO_3$, MgO, $SiO_2$, $Eu_2O_3$ were used as raw materials. The raw materials were mixed thoroughly with an appropriate amount of ethanol in an agate mortar and then dried at 90 $^{\circ}C$ for 2 hours. The mixture was sintered at 900 $^{\circ}C$ for 2 hours and reheated at the mild reducing atmosphere 5% $H_2$ gas mixed with 95% $N_2$ gas at about 900 $^{\circ}C$ to 1250 $^{\circ}C$ for 2 hours. The photoluminescence spectra of the phosphor powders were measured by a fluorescent spectrophotometer. The crystal structure of phosphor powders were investigated by X-ray diffractometer.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2004.05a
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• pp.97-100
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• 2004

We report $EU^{2+}$ activated green phosphor $Ba_{2}CaMgSi_{2}O_{8}:Eu^{2+}$. The phosphor absorbs ultroviolet radation and emits a green visible light. The phosphors were synthesized by conventional solid state reaction method. The high purity $BaCO_3$, $CaCO_3$, MgO, $SiO_2$, $Eu_{2}O_{3}$ were used as raw materials. The raw materials were mixed thoroughly with an appropriate amount of ethanol in an agate mortar and then dried at $90^{\circ}C$ for 2 hours. The mixture was sintered at $900^{\circ}C$ for 2 hours and reheated at the mild reducing atmosphere 5% $H_2$ gas mixed with 95% $N_2$ gas at about $900^{\circ}C$ to $1200^{\circ}C$ for 2 hours. The photoluminescence spectra of the phosphor powders were measured by a fluorescent spectrophotometer. The crystal structure of phosphor powders were investigated by X -ray diffractometer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.1
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• pp.5-16
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• 1991

It was grown Cubic $ZrO_2(10 mol% Y_2O_3)$ single crystals doped with 1 wt% rare earth metal oxides (RE=Ce, Pr, Nd, Eu, Er) by Skull method. It was investigated electrical properties on (111) plane of grown single crystals by Impedance Spectroscopy. It was potted relation between temperature and electrical conductivities and observed the transition at $약300-400^{\circ}$ It was obtained activation energy on the migration of oxygen vacancy between low temperature (before the transition) and high temperature (after the transition till ${\11}500^{\circ}$) and its difference can be seen the activation energy of the formation of oxygen vacancies by break up defect complexes. It was obtained the activation energy according as add yttria and rare earth metal oxides and discussed ionic conduction mechanism. Grown single crystals showed Ce: orange - red, Pr: golden - yellow, Nd: lilac, Eu: light pink, Er: pink due to dopant effect from the light absorption data in the visible range.

• Korean Journal of Materials Research
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• v.27 no.5
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• pp.270-275
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• 2017

Inorganic phosphors based on $ZrO_2:Eu^{3+}$ nanoparticles were synthesized by a salt-assisted ultrasonic spray pyrolysis process that is suitable for industrially-scalable production because of its continuous nature and because it does not require expensive precursors, long reaction time, physical templates or surfactant. This facile process results in the formation of tiny, highly crystalline spherical nanoparticles without hard agglomeration. The powder X-ray diffraction patterns of the $ZrO_2:Eu^{3+}$ (1-20 mol%) confirmed the body centered tetragonal phase. The average particle size, estimated from the Scherrer equation and from TEM images, was found to be approximately 11 nm. Photoluminescence (PL) emission was recorded under 266 nm excitation and shows an intense emission peak at 607 nm, along with other emission peaks at 580, 592 and 632 nm which are indicated in red.

• Korean Journal of Materials Research
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• v.24 no.9
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• pp.469-473
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• 2014

$SrSnO_3$ phosphor powders were synthesized with two different contents of activator ions $Eu^{3+}$ and $Tb^{3+}$ using the solid-state reaction method. The structural, morphological, and optical properties of the phosphors were investigated using X-ray diffractometry, field-emission scanning electron microscopy, and fluorescence spectrophotometry, respectively. All the phosphors showed a cubic structure, irrespective of the type and the content ratio of activator ions. For $Eu^{3+}$-doped $SrSnO_3$ phosphors, the intensity of the 620 nm red emission spectrum resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ was stronger than that of the 595 nm orange emission signal due to the $^5D_0{\rightarrow}^7F_1$ transition in the range 0.01-0.05 mol of $Eu^{3+}$, but the ratio of the intensity was reversed in the range 0.10-0.20 mol of $Eu^{3+}$. The variation in the emission intensity indicates that the site symmetry of the $Eu^{3+}$ ions around the host crystal was changed from non-inversion symmetry to inversion. For the $Tb^{3+}$-doped $SrSnO_3$ phosphors under excitation at 281 nm, one strong green emission band at 550 nm and several weak bands were observed. These results suggest that the optimum red and green emission signals can be realized when the activator ion content for $Eu^{3+}$- or $Tb^{3+}$-doped $SrSnO_3$ phosphors is 0.20 mol and 0.15 mol, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.32-35
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• 2006

For the white UV-LED applications, $Eu^{2+}$-activated calcium aluminium silicate phosphors were synthesized for the first time and the structures and luminescence characteristics of these phosphors were investigated. The phosphors in this study emitted blue. green or blue-green light depending on the starting materials for synthesis. In addition, the structure was also changed when the different starting materials were used. When CaO and $CaCO_3$ was used as a starting material. tetragonal $Ca_2Al_2SiO_7$ was formed and blue-green and pure green light was emitted. respectively. However. in the case of $CaSiO_3$, triclinic $CaAl_2Si2O_8$ was formed and only pure blue emission was detected. The maximum emission intensity was obtained from $CaAl_2Si_2O_8:Eu^{2+}$ phosphors, which intensity was about 1.4 times higher than that of YAG:$Ce^{3+}$ phosphor used for blue LED.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.275-280
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• 2003

Epitaxial Gd$_2O_3:Eu^{3+}$luminescent thin films have been grout on Si(III) substrates using ionized Cluster Beam Deposition (ICBD). After the film growing, they were implanted and post annealed to change the crystal structure. The initial growth stage was monitored by using in-situ Reflection High Energy Electron Diffraction (RHEED). The formed crystal structure was identified with X-ray diffraction (XRD) technique and Fourier transform infrared (FT-R) spectroscopy. The electronic states variations were investigated by Near Edge X-ray Absorption Fine Structure (NEXAFS). Photoluminescence (PL), Cathodoluminescence (CL). and Vacuum ultraviolet (VUV) spectrum were used for examining the optical properties. We report the optical property changes depending on crystal structure and the electronic states.