• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.148-152
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• 2007

In this paper, we have synthesized $Gd_2O_3:Eu^{3+}$ nano phosphor particle using a low temperature solution-combustion method. We have investigated the structure and the luminescent characteristic as the sintering temperature and europium concentration. From XRD(X-ray diffraction) and SEM(scanning electron microscope) results, we have verified that the phosphor particle was fabricated a spherical shape with $30{\sim}40nm$ particle size. From the photoluminescence results, the strong peak exhibits at 611 um and the luminescent intensity depends on europium concentration. $Gd_2O_3:Eu$ fine phosphor particle has shown excellent luminescent efficiency at 5 wt% of europium concentration. The phosphors calcinated at $500^{\circ}C$ have possessed the x-ray peaks corresponding to the cubic phase of $Gd_2O_3$. As calcinations temperature increased to $700^{\circ}C$, the new monoclinic phase has identified except cubic patterns. From the luminescent decay time measurements, mean lifetimes were $2.3{\sim}2.6ms$ relatively higher than conventional bulk phosphors. These results indicate that $Gd_2O_3:Eu$ nano phosphor is possible for the operation at the low x-ray dose, therefore, the application as medical imaging detector.

• 대한화학회지
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• 제55권6호
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• pp.932-935
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• 2011

Using tetrabutyl titanate as precursor, $Eu^{3+}$ doped $TiO_2$ nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with $Eu^{3+}$ doped $TiO_2$ was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was quenched by chlorpyrifos and the quenching rate constant ($k_q$) was $1.24{\times}10^{11}\;L/mol{\cdot}s$ according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of $TiO_2$ nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (${\Delta}G_{et}$) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was proportional to chlorpyrifos concentration. The range of detection was $5.0{\times}10^{-10}-2.5{\times}10^{-7}mol/L$ and the election limit ($3{\sigma}$) was $3.2{\times}10^{-11}$ mol/L.

• 한국재료학회지
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• 제8권6호
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• pp.520-525
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• 1998

활성제로 $Eu^{+2}$을 사용한 BaO-MgO-$AI_2O_3$에서 화학조성 변화에 따른 청색 형광체의 광학특성을 254nm 자외선 및 147nm의 진공자외선 하에서 측정하였다. 동 형광체는 자외선 및 진공자외선 조사를 받아 주 파장이 445nm 인 가시광선의 청색을 발하는 형광체이다. $BaMgAI_{14}O_{23}$ : Eu 농도에 따라 증가하였으며 진공자외선의 경우에는 5%농도에서 최대가 됨을 알 수 있었다. 자외선 및 진공자외선 모두에서 $BaMgAI_{10}O_{17}$형광체의 청색 발광강도는$BaMgAI_{14}O_{23}$보다 좋았다. 또한 $BaMgAI_{10}O_{17}$에서 Ba대신 Ca이나 Sr을 0.1mole 치환시킨 $Ba_{0.9}Ca_{0.1}MgAI_{10}O_{17}$과 $Ba_{0.9}Sr_{0.1}MgAI_{10}O_{17}$ 형광체로 광특성을 더욱 개선할 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.676-678
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• 2004

In order to develop new yellow phosphor that emit efficiently under the 450 - 470 nm excitation range, we have synthesized a $Eu^{2+}$-activated $Sr_3SiO_5$ yellow phosphor and investigated an attempt to develop white LEDs by combining it with a InGaN blue LED chip (460 nm). Two distinct emission bands from the InGaN-based LED and the $Sr_3SiO_5$:Eu phosphor are clearly observed at 460 nm and at 570 nm, respectively. These two emission bands combine to give a spectrum that appears white to the naked eye. Our results showed that InGaN (460 nm chip)-based $Sr_3SiO_5$:Eu exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1079-1082
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• 2004

Dense $BaMgAl_{10}O_{17}:Eu^{2+}$ phosphor particles with a spherical shape have been synthesized through spray pyrolysis method using basic aluminum nitrate precursor as a spray solution. Also, a thin layer of silica on the surface of $BaMgAl_{10}O_{17}:Eu^{2+}$ particles were coated by hydrolysis reaction of alkoxide sources with the particles. The correlation between PL intensity and surface treatment by coating for the dense $BaMgAl_{10}O_{17}:Eu^{2+}$ particles have been investigated.

• 한국재료학회지
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• 제9권1호
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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.

• Journal of Information Display
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• 제13권3호
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• pp.97-100
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• 2012

We have conducted two kinds of the so-called charge-compensated aliovalent element substitutions to control the photoluminescence properties of $NaAlSiO_4:Eu^{2+}$ with a special focus on the enhancement of the excitation intensity at 400 nm. The aliovalent element substitutions include cation-cation and cation-anion co-substitutions according to the general formulas $Na_{1-x}M_xAl_{1+x}Si_{1-x}O_4:Eu^{2+}$ and $Na_{1-x}M_xAlSiO_{4-x}N_x:Eu^{2+}$ (M = $Mg^{2+}$, $Ca^{2+}$, and $Sr^{2+}$), respectively. The increase in the relative excitation intensity at 400 nm has been achieved in both types of the co-substitutions. Thus, the present research has demonstrated the effectiveness of the charge-compensated element substitution.

• Journal of Information Display
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• 제13권3호
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• pp.107-111
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• 2012

An almost pure phase of $Ba_3Si_6O_{12}N_2$ doped with $Eu^{2+}$ was successfully synthesized through the ammonia nitridation of an oxide precursor prepared through an aqueous-solution method, using propylene- glycol-modified silane. The emission peak intensity of the obtained $Ba_3Si_6O_{12}N_2:Eu^{2+}$ was -2.2 times higher than that of the sample prepared through a solid-state reaction method.

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.33-35
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• 2014

We report here results of a study of superconductivity in the ($Ta_{1-x} Sn_x)Sr_2EuCu_2O_z$ system. We observe resistive superconducting transitions for the samples with x = 0.15-0.3, and the highest superconducting transition has been achieved for the sample with x = 0.2 which reveals onset $T_c$ of 43 K and zero-resistivity of 25 K. Thermoelectric power measurements indicate that Sn doping introduces holes into the system and thereby superconductivity can be achieved in the ($Ta_{1-x} Sn_x)Sr_2EuCu_2O_z$ system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.570-573
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• 1999

High brightness (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu Phosphor Particles were directly Prepared in the spray Pyrolysis by adding flux materials such as LiCl and HBO$_3$. The (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu particles prepared from solution with flux material had higher PL (photoluminescence) intensities than those prepared from solution without flux. In the spray pyrolysis, the flux acts as promoter of the growth of crystallite and activation of doping material as in the solid state reaction method. Additionally, the flux improved PL intensity of (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu phosphor particles by densifying the internal structure and eliminating the defect existing inside and surface of (Y$_{x}$/Gd$_{1-x}$ )$_2$O$_3$:Eu phosphor particles.r particles.