• 공업화학
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• 제20권5호
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• pp.565-569
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• 2009

녹색과 청색의 나노 형광체 합성에 있어서 입자 형상 및 입자 크기의 변화를 알아보기 위해 액상법으로 진행하였으며, 이를 바탕으로 최종적으로 녹색 형광체의 경우 약 80 nm를, 그리고 청색 형광체의 경우 약 60 nm급의 나노 형광체 분말 합성이 가능하였다. 합성된 두 가지의 $Zn_2SiO_4$ : Mn 녹색 형광체와 BAM : Eu의 청색 나노 형광체 분말의 특성 평가를 비교하였으며, 그 결과 PL 특성면에서 녹색 형광체인 $Zn_2SiO_4$ : Mn이 BAM : Eu의 청색 형광체 대비 높은 형광성을 보여주었다.

• 한국결정성장학회지
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• 제9권5호
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• pp.480-485
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• 1999

FED용의 적색 형광체로 Al과 Pr이 첨가된 $SrTiO_3$의 제조와 형광특성에 대하여 연구하였다. 이 형광체는 metallic nitrates, ethylene glycol, citric acid를 출발물질로 하여 polymeric complex를 형성하는 Pechini 법으로 합성하였다. 본 실험에서 합성된 분말의 성장기구는 $900^{\circ}C$를 경계로 서로 다른 경향을 보이고 있으며, $600^{\circ}C$의 저온에서도 $SrTiO_3$상이 형성됨을 확인하였다. 또한 빛 발광특성의 경우는 Pr 이온에 의한 359 nm에서의 여기 스펙트럼과 저전압 음극선 발광의 경우 617 nm에서 최대 피크를 갖고 575 nm와 650 nm 사이에서 적색의 발광 스펙트럼이 관찰되었다. Pechini 법으로 합성된 $SrTiO_3$:Al, Pr 형광체의 경우 FED의 적색 형광체에 적용될 수 있을 것이다.

• Transactions on Electrical and Electronic Materials
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• 제12권1호
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• pp.11-15
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• 2011

In this study, $ZnGa_2O_4$ phosphors in its application to field emission displays and electroluminescence were synthesized through the precipitation method and $Mn^{2+}$ ions. A green luminescence activator, $Cr^{3+}$ ions, and a red luminescence activator were separately doped into $ZnGa_2O_4$, which was then screen printed to an indium tin oxide substrate. The thick films of the $ZnGa_2O_4$ were deposited with the various thicknesses using nano-sized powder. The best luminescence characteristics were shown at a thickness of 60 ${\mu}m$. Additionally, green-emission $ZnGa_2O_4:Mn^{2+}$ and red-emission $ZnGa_2O_4:Cr^{3+}$ phosphor thick films, which have superior characteristics, were manufactured through the screen-printing method. These results indicate that $ZnGa_2O_4$ phosphors prepared through the precipitation method have wide application as phosphor of the full color emission.

• 자원리싸이클링
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• 제16권5호
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• pp.46-50
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• 2007

[ $Eu^{2+},\;Nd^{3+}$ ]로 도핑된 $CaAl_2O_4$ 청색 형광체를 고상반응법으로 제조하였다. 1 mol% $Eu^{2+}$로 doping된 형광체에 다양한 조성의 $Nd^{3+}$를 co-doping함에 따라 고휘도, 장잔광 특성을 보였다. 제조한 형광체에 대하여 XRD, SEM, TEM, 빛발광 특성을 조사하였다. $CaAl_2O_4:Eu^{2+}:Nd^{3+}$의 넓은 밴드의 UV로 여기된 빛발광 특성이 $Eu^{2+}$의 $4f^65d^1$에서 $4f^7$ 상태로 천이에 의해 기인된 청색영역(${\lambda}_{max}=440\;nm$)에서 관찰되었다. $Nd^{3+}$로 co-doping한 형광체는 여기광을 차단하였을 때 장잔광 발광 특성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.121-124
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• 1998

Generally the structure of powder electroluminescent devices (PELDs) on ITO-film was makeup of the ZnS:Cu phosphor layer and BaTiO$_3$ insulating layer. The active layer, which consists of a suitably doped ZnS powder mixed in a dielectric, is sandwiched between two electrodes; one of which are ITO film and the other is aluminum. In this paper, three kinds of powder eleotroluminescent devices (PELDs) : WK-A(ITO/BaTiO$_3$/ZnS:Cu/Silver paste). WK-B(ITO/BaTiO$_3$+ZnS:Cu/Silver paste) and WK-C(ITO/BaTiO$_3$/ZnS:Cu/BaTiO$_3$/Silver paste), fabricated by spin coating method, were investigated. To evaluate the luminescence properties of three kinds of PELDs, EL emission spectroscopy, transferred charge density and time response of EL emission intensity under square wave voltage driving were measured.

• 한국세라믹학회지
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• 제38권12호
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• pp.1085-1092
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• 2001

고효율 AC powder EL 소자를 초저가형과 저전력 소모형으로 분류하여 막의 두께와 제조된 유기결합제에 따라 스크린 프린팅법으로 제조하였다. 제조된 소자의 광전기적 특성을 평가하기 위하여 인가 주파수는 400Hz~1kHz, 인가 전압은 50~300 $V_{rms}$까지 변화시켜 휘도 및 전류밀도를 측정하였다. 주파수 및 전압공급원은 정현파 발생 장치로서 frequency generator를 이용하였다. 또한 휘도는 luminometer 의해 측정되었으며 전류밀도 측정을 위하여 multimeter를 사용하였다. 초저가형 AC powder EL 소자의 경우에는 가소제를 첨가하지 않고 발광층의 두께는 45~50$\mu\textrm{m}$이며 유전층의 두께는 약 10$\mu\textrm{m}$에서 43cd/$m^2$ 정도의 휘도와 20$\mu$A/$cm^2$정도의 전류밀도를 얻을 수 있었으며 저전력 소모형 AC powder EL 소자의 경우에는 15wt의 가소제 첨가하에 발광층의 두께는 45~50$\mu$m이며 유전층의 두께는 15~20$\mu$m에서 74cd/ $m^2$정도의 휘도와 30~40$\mu$A/ $m^2$정도의 전류밀도를 얻을 수 있었다. 또한 수명시간에 있어서 본 연구에서 제조한 AC powder EL 소자가 타사 제품보다 절대적으로 우수한 특성을 보였다.다.

• 반도체디스플레이기술학회지
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• 제18권1호
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• pp.10-14
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• 2019

In this study, we synthesized two $Y_3Al_5O_{12}:Ce^{3+}$ phosphors ($7{\mu}m$-sized and $2{\mu}m$-sized YAG) with different sizes by controlling particles sizes of starting materials of the phosphors for white LED. In the smaller one ($2{\mu}m$-sized YAG), its photoluminescence intensity in the reflective mode was 63 % that of the bigger one ($7{\mu}m$-sized YAG); the quantum efficiencies were 93 % and 70 % for the smaller and the bigger ones. Two kinds of white LED packages with the same color coordinates were fabricated with a blue package (chip size $53{\times}30$) and two phosphors. The luminous flux of the white LED package with the smaller YAG phosphor was 92 % of that with the bigger one, indicating that the quantum efficiency of phosphor dispersed inside LED package was higher than that of the pure powder. It was consistently confirmed by the optical simulation (LightTools 6.3). It is notable according to the optical simulation that the white LED with the smaller phosphor showed 24 % higher luminous efficiency. If the smaller one had the same quantum efficiency as the bigger one (~93 %). Therefore, it can be suggested that the higher luminous efficiency of white LED can be possible by reducing the particle size of the phosphor along with maintaining its similar quantum efficiency.

• 한국분말재료학회지
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• 제26권6호
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• pp.463-470
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• 2019

Fe₃O₄/SiO₂/YVO₄:Eu³⁺ multifunctional nanoparticles are successfully synthesized by facile stepwise sol-gel processes. The multifunctional nanoparticles show a spherical shape with narrow size distribution (approximately 40 nm) and the phosphor shells are well crystallized. The Eu³⁺ shows strong photoluminescence (red emission at 619 nm, absorbance at 290 nm) due to an effective energy transfer from the vanadate group to Eu. Core-shell structured multifunctional nanoparticles have superparamagnetic properties at 300 K. Furthermore, the core-shell nanoparticles have a quick response time for the external magnetic field. These results suggest that the photoluminescence and magnetic properties could be easily tuned by either varying the number of coating processes or changing the phosphor elements. The nanoparticles may have potential applications for appropriate fields such as laser systems, optical amplifiers, security systems, and drug delivery materials.

• 한국분말재료학회지
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• 제19권3호
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• pp.220-225
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• 2012

YAG:Ce yellow phosphor particles were synthesized by spray pyrolysis with changing the solution properties and their luminous properties, crystal structure, and morphological changes were studied by using PL measurement, XRD, and SEM analysis. It was clear that the solution properties significantly affected the crystal phase, crystallite size, the PL intensity, and the morphology of YAG:Ce particles. At low calcination temperature, the addition of urea only to the spray solution was helpful to form a pure YAG phase without any impurity phases, as the result, the highest luminescence intensity was achieved at the calcination temperature of $900^{\circ}C$. When the calcination temperatures were larger than $1300^{\circ}C$, however, the YAG particles prepared without any additive showed the highest luminescent intensity. Regardless of the solution conditions, the emission intensity of YAG:Ce particles prepared by spray pyrolysis showed a linear relation with the crystallite size. In terms of the morphology of YAG:Ce particles, the addition of both DCCA and $NH_4OH$ to the spray solution was effective to prepare a spherical and dense structured YAG particles.

• 한국분말재료학회지
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• 제27권2호
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• pp.146-153
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• 2020

The co-doping effect of aliovalent metal ions such as Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Zn²⁺ on the photoluminescence of the Y₂O₃:Eu³⁺ red phosphor, prepared by spray pyrolysis, is analyzed. Mg²⁺ metal doping is found to be helpful for enhancing the luminescence of Y₂O₃:Eu³⁺. When comparing the luminescence intensity at the optimum doping level of each Mg²⁺ ion, the emission enhancement shows the order of Zn²⁺ ≈ Ba²⁺ > Ca²⁺ > Sr³⁺ > Mg²⁺. The highest emission occurs when doping approximately 1.3% Zn²⁺, which is approximately 127% of the luminescence intensity of pure Y₂O₃:Eu³⁺. The highest emission was about 127% of the luminescence intensity of pure Y₂O₃:Eu³⁺ when doping about 1.3% Zn²⁺. It is determined that the reason (Y, M)₂O₃:Eu³⁺ has improved luminescence compared to that of Y₂O₃:Eu³⁺ is because the crystallinity of the matrix is improved and the non-luminous defects are reduced, even though local lattice strain is formed by the doping of aliovalent metal. Further improvement of the luminescence is achieved while reducing the particle size by using Li₂CO₃ as a flux with organic additives.