• 한국세라믹학회지
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• 제49권1호
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• pp.105-110
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• 2012

In this paper, a yellow phosphor $Sr_3SiO_5:Eu^{2+}$ that emits efficiently at the 450 nm excitation for warm white LED is studied. In addition, the effects of various flux $BaF_2$, $NH_4Cl$ on the emission spectra were investigated. The samples were synthesized through conventional solid state reaction under reducing atmosphere of 95% $N_2$-5% $H_2$ mixture at the high temperature. All phosphors showed a excitation band from 450 nm and broad band emission peaking at region of 580 nm. The optimal concentration of $BaF_2$ flux is 3 wt% for $Sr_3SiO_5$ with doping 0.05mol Eu phosphors fired in a reductive atmosphere. The phosphor showed highest emission peaking at 582 nm.

• Advances in nano research
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• 제3권2호
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• pp.55-66
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• 2015

Crystalline $Ce^{3+}$ co-doped $LaPO_4$:RE ($RE=Dy^{3+}$, $Tb^{3+}$, $Eu^{3+}$, $Sm^{3+}$) and mix doped rare earth ions of $Dy^{3+}$, $Tb^{3+}$ and $Eu^{3+}$ were prepared by the polyol method at $150^{\circ}C$. Strongly enhance luminescence intensity is obtained with the co-doping of $Ce^{3+}$ with $LaPO_4$:$Dy^{3+}$ and $LaPO_4$:$Tb^{3+}$ due to charge transfer (CT) occurring from $Ce^{3+}$ to $Dy^{3+}$ and $Ce^{3+}$ to $Tb^{3+}$, where as there is no significant changes in luminescence intensity of $Ce^{3+}$ co-doped $Eu^{3+}$ and $Sm^{3+}$ doped $LaPO_4$ samples. The luminescence color can be tuned from green to white by varying the excitation wavelength for the mix ions $Ce^{3+}$, $Dy^{3+}$, $Tb^{3+}$ and $Eu^{3+}$ doped with $LaPO_4$.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2004년도 춘계학술대회 발표 논문집
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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 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.

• 한국세라믹학회지
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• 제49권4호
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• pp.325-327
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• 2012

Europium-doped $LaSi_3N_5$ phosphor was synthesized from LaSi/Si/$Si_3N_4/Eu_2O_3$ mixture by nitridation at $1390^{\circ}C$ and additional annealing at $1650^{\circ}C$ for 4 h. The phosphor shows emissions in the green light region with a maximum at 560 nm. With increasing europium content in the general formula $La_{1-z}Eu_zSi_3N_{5-z}O_{1.5z}$ from z = 0.01 to 0.06 there was a maximum emission for z = 0.04 followed by concentration quenching for the highest europium content (z = 0.06).

• 한국세라믹학회지
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• 제56권1호
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• pp.71-76
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• 2019

Monochromatic amber phosphor in glasses (PiGs) for automotive LED applications were fabricated with $YAG:Ce^{3+}$, $CaAlSiN_3:Eu^{2+}$ phosphors and Pb-free silicate glass. After synthesis and thickness-thinning process, PiGs were mounted on high-power blue LED to make monochromatic amber LEDs. PiGs were simple mixtures of 566 nm yellow YAG, 615 nm red $CaAlSiN_3:Eu^{2+}$ phosphor and transparent glass frit. The powders were uniaxially pressed and treated again through CIP (cold isostatic pressing) at 200 MPa for 20 min to increase packing density. After conventional thermal treatment at $550^{\circ}C$ for 30 min, PiGs were applied by using GPS (gas pressure sintering) to obtain a fully dense PiG plate. As the phosphor content increased, the density of the sintered body decreased and PiGs containing 30 wt% phosphor had full sintered density. Changes in photoluminescence spectra and color coordination were investigated by varying the ratio of $YAG/CaAlSiN_3$ and the thickness of the plates. Considering the optical spectrum and color coordinates, PiG plates with $240{\mu}m$ thickness showed a color purity of 98% and a wavelength of about 605 nm. Plates exhibit suitable optical characteristics as amber light-converting material for automotive LED applications.

• 한국세라믹학회지
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• 제42권3호
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• pp.145-149
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• 2005

[ $Eu^{2+}$ ]-activated barium magnesium silicate phosphor, $(Ba,Ca)_{3}MgSi_{2}O_{8}:Eu_{x}$, has been known to emit blue-green light. In this study we report the manufacturing processes for producing either pure green or pure blue light-emitting phosphor from the same composition of $Ba_{2-x}Ca_{2}CaMgSi_{2}O_{8}:Eu_{x}$ (0 < x < 1) by controlling heat treatment conditions. Green light emitting phosphor of $Ba_{1.9}CaMgSi_{2}O_{8}:Eu_{0.1}$ can be produced under the sample preparation condition of highly reducing atmosphere of $23\%\;H_2/77\%\;N_2$, while blue or blue-green light emitting phosphor under reducing atmosphere of $5\~20\%\;H_2\;/\;95\~80\%$ N_2. The green light-emitting phosphors are prepared in two steps: firing at $800\~1000^{\circ}C$ for $2\~5$ h in air then at $1100\~1350^{\circ}C$ for 2-5 h under reducing atmo­sphere $23\%$ $H_2/77\%\;N_2$. The excitation spectrum of the green light-emitting phosphor shows a broadband of $300\~410$ nm. The emission spectrum has a maximum intensity at the wavelength of about 501 nm. The CIE value of green light emission is (0.162, 0.528). The pure blue light-emitting phosphors can be produced using the $Ba{2_x}CaMgSi_{2}O_{8}:Eu_{x}$ by introducing additional firing step at $1150\~1300^{\circ}C$ in air before the final reducing treatment. The XRD analysis shows that the green light-emitting phosphor mainly consisted of $Ba_{1.31}Ca_{0.69}SiO_{4}$ (JCPDS $\#$ 36-1449) and other minor phases i.e., $MgSiO_3$ (JCPDS $\#$ 22-0714) and $Ca_{2}BaMgSi_{2}O_{8}$ (JCPDS $\#$ 31-0128). The blue light-emitting phosphor mainly consisted of $Ca_{2}BaMgSi_{2}O_{8}$ phase.

• 융복합기술연구소 논문집
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• 제4권1호
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• pp.21-27
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• 2014

White LEDs (light-emitting diodes) are promising new-generation light sources which can replace conventional lamps due to their high reliability, low energy consumption and eco-friendly effects. This paper briefly reviews recent progress of oxy/nitride host phosphor and quantum dot materials with broad excitation band characteristics for phosphor-converted white LEDs. Among oxy/nitride host materials, $M_2Si_5N_8:Eu^{2+}$, $MAlSiN_3:Eu^{2+}$ M-SiON(M=Ca, Sr, Ba), ${\alpha}/{\beta}-SiAlON:Eu^{2+}$ are excellent phosphors for white LED using blue-emitting chip. They have very broad excitation bands in the range of 440-460 nm and exhibit emission from green to red. In this paper, In this review we focus on recent developments in the crystal structure, luminescence and applications of the oxy/nitride phosphors for white LEDs. In addition, the application prospects and current trends of research and development of quantum dot phosphors are also discussed.

• 대기
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• 제27권1호
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• pp.79-91
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• 2017

It is imperative to understand the characteristics of atmospheric circulation patterns under the climate system due to its impact on climatic factors. Thus this study focused on analyzing the impact of the atmospheric circulation on the relationship between precipitation and temperature regionally. Here we used monthly gridded observational data (i.e., CRU-TS3.2, NOAA-20CR V2c) and HadGEM2-AO climate model by RCP8.5, for the period of 1960~1999 and 2060~2099. The experiment results indicated that the negative relationship was presented over East Asia and Europe during summer. On the other hand, at around Korea (i.e. EA1: $31^{\circ}N{\sim}38^{\circ}N$, $126^{\circ}E{\sim}140^{\circ}E$) and Northwestern Europe (i.e. EU1: $48^{\circ}N{\sim}55^{\circ}N$, $0^{\circ}E{\sim}16^{\circ}E$) in winter, strong positive relationship dominate due to warm moist advection come from ocean related to intensity variation of the East Asian winter monsoon (EAWM) and North Atlantic Oscillation (NAO), respectively. It was found that values of positive relation in EA1 and EU1 at the end of the 21st century is regionally greater than at the end of 20th century during winter since magnitude of variation of the EAWM and NAO is projected to be greater in the future as result of simulation with RCP 8.5. Future summer, the negative correlations are weakened in EA1 region while strengthened in EU1 region. For better understanding of correlations with respect to RCP scenarios, a further study is required.

• 항공우주정책ㆍ법학회지
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• 제30권1호
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• pp.3-29
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• 2015

2012년의 Pedro Espada $S\acute{a}nchez$ and Others v Iberia $L\acute{i}neas$ $A\acute{e}reas$ de $Espa\tilde{n}a$ SA. 판결은 몬트리올협약 제22조 제2항의 적용과 관련하여 협약 제3조 제3항의 연관성을 밝히고 그 범위에 관한 법리해석을 제시한 후, 구체적인 판단기준을 제시하였다는 점에서 중요한 의의를 갖는다. 본 판결을 간략하게 정리하면, 여객 총 4인이 항공기에 탑승하면서, 2인 명의의 식별표가 부착된 2개의 수하물에 4인의 여객 각각의 소유물을 넣었는데, 그것이 멸실되어 몬트리올협약 제22조 제2항에 따른 총 4인 합계 4,000 SDR의 손해배상청구소송을 제기한 것이다. 즉, 몬트리올협약 제22조 제2항을 적용할 때, 협약 제3조 제3항을 어떻게 연결지어 해석하느냐 하는 것이 본건의 주요쟁점이 되었다. EU 사법재판소는 협약 제3조 제3항을 넓게 해석하면, 식별표 부착은 단지 운송인에게 수하물의 식별의무만을 부과한 것이므로 가령 여객이 본건과 같이 동행 여객의 수하물에 자신의 짐을 넣은 경우라도 협약 제22조 제 2항상의 여객 1인당 책임한도액 규정을 원용할 수 있다고 보고 있다. 이러한 재판소의 해석론은 크게 몬트리올협약 제22조 제2항의 적용과 관련하여 협약 제3조 제3항의 연관성 및 그 해석범위에 관한 문제로 논의가 집중되는 바, 다음과 같은 두 가지 측면에서 중요한 의미가 있다. 첫째, 항공여객운송의 실무상 현실적으로는 흔히 발생하는 일이기는 하나 지금까지 구체적으로 논의되지 않았던 몬트리올협약의 해석상의 문제에 대해 본 판결은 일정한 해석지침을 제공함으로써 향후 적용상의 시사를 마련해 주고 있다는 점이다. 둘째, 본 판결을 통해 EU 역내에서의 몬트리올 협약에 대한 해석이 국제적인 측면에서 통일적 진보를 이루게 되었다는 점이다. 보통 특정 협약의 규정에 관한 법리해석은 국내의 사법기관들이 담당하여 지금까지는 해석상의 혼란 내지는 불통일을 피할 수 없었다. 그러나 본 판결은 EU 역내의 개별 국내 법원의 법리해석이 아닌 국제사법기관으로서의 EU 사법재판소가 일정한 판단기준을 제시하고 있으므로 몬트리올 협약이라는 국제적 통일규범에 대한 전례 없는 통일적인 해석론이 가해지게 되었다. 즉, 향후 몬트리올협약의 EU 역내 적용과 관련하여 동 협약상 규정의 의미, 해석 및 적용기준에 통일적 해석의 시도가 이루어지고 있음을 볼 수 있겠다. 궁극적으로는 전 세계적인 차원에서 몬트리올협약의 규정 해석, 나아가 향후 항공운송조약 체제의 입법방향에 큰 영향을 미치게 되었다는 점에서 큰 의미가 있다고 본다. 요컨대, 본 사안은 EU 자체 내의 EU항공운송관계규칙의 해석이 문제가 된것이 아니라 EU법의 일부를 이루고 있는 몬트리올협약이라는 국제조약의 규정해석이 문제가 된 사례이다. 본 판결은 EU 사법재판소라는 국제적 사법기관의 지위에서, 몬트리올협약상 항공여객운송인의 수하물책임에 관한 해석상의 쟁점에 대해 몇 가지의 기준을 제시하고 있다는 점에서 주목된다. 향후 몬트리올 협약의 적용과 관련한 EU 각국의 개별적 사법기관의 판단기준에 본 판결은 상당한 영향을 미칠 것으로 보인다.