• 한국진공학회지
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• 제19권1호
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• pp.66-71
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• 2010

PDP를 비롯한 형광체를 이용하는 디스플레이 분야에서 현재 마이크로미터($\mu}$-meter) 이상의 크기를 갖는 기존의 벌크(bulk) 형광체를 능가하는 성능과 새로운 물성을 나타내는 나노형광체(nanophosphor) 개발 및 응용에 대한 연구가 절대적으로 필요한 시점이다. 따라서 본 실험에서는 나노 사이즈의 평균 입자 크기를 갖는 구형의 $Zn_2SiO_4:Mn$ 형광체 입자를 초음파 분무열 분해(ultrasonic spray pyrolysis) 방법을 이용하여 합성하였다. 구형의 형광체 입자의 크기는 분무 장치의 droplet separator를 도입하여 조절하였다. 2 mol%의 망간을 도핑하여 합성한 $Zn_2SiO_4:Mn$ 입자는 시간이 지남에 따라 감소되고, 최근에 고상에서 합성하여 상용화된 물질에 비교할 수 있을 만한 빛 방출의 세기를 가졌다. 형광체 입자의 크기는 무기질 염의 농도가 0에서 5 M로 증가함에 따라 $1\;{\mu}m$에서 $0.2\;{\mu}m$로 감소하였다. 0.5 M 이상의 농도의 전구체 용액에서 얻어진 형광체 입자의 빛 방출은 상용화되어 있는 물질과의 비교를 통해 알아보았다.

• 한국재료학회지
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• 제19권3호
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• pp.163-168
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• 2009

$Eu^{3+}$-doped $Y_2O_3$ red phosphor was synthesized in a flux method using the chemicals $Y_2O_3,\;Eu_2O_3,\;H_3BO_3$ and $BaCl_2{\cdot}2H_2O$. The effect of a flux addition on the preparation of $Y_2O_3:Eu_{3+}$ red phosphor used as a cold cathode fluorescence lamp was investigated. $H_3BO_3$ and $BaCl_2{\cdot}2H_2O$ fluxes were used due to their different melting points. The crystallinity, thermal properties, morphology, and emission characteristics were measured using XRD, TG-DTA, SEM, and a photo-excited spectrometer. Under UV excitation of 254 nm, $Eu_2O_3$ 3.7 mol% doped $Y_2O_3$ exhibited a strong narrow-band red emission, peaking at 612 nm. From this result, the phosphor synthesized by firing $Y_2O_3$ with 3.7 mol% of $Eu_2O_3$, 0.25 mol% of $H_3BO_3$ and 0.5 mol% of $BaCl_2{\cdot}2H_2O$ fluxes at $1400^{\circ}C$ for 2 hours had a larger particle size of $4{\mu}m$ on average compared to the phosphor of the $H_3BO_3$ flux alone. In addition, a phosphor synthesized by the two fluxes together had a rounder corner shape, which led to the maximum emission intensity.

• 한국응용과학기술학회지
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• 제23권3호
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• pp.207-214
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• 2006

$Y_{2-x}Gd_xO_3:Eu$, phosphors for plasma display panel(PDP), were prepared by Pechini method which use yttriun chloride, gadolinium chloride, and europium oxide as starting materials. This method is a different way to the synthesis of europium(Eu)-doped phosphors, and it consists of the formation of a polymeric resin obtained by polyesterification between metal chelate compounds and a polyfunctional alcohol. This needs lower temperature than solid-state synthetic method. The prepared $Y_{2-x}Gd_xO_3:Eu$ phosphor particles had spherical shape and coherence. The luminescence intensity of $Y_{2-x}Gd_xO_3:Eu$ phosphor particles increased according to the increase of gadolinium(Gd) content(to 0.8mol%), and $Y_{1.2}Gd_{0.8}O_3:Eu$ phosphors had the highest luminescence intensity under vacuum ultra violet(VUV) excitation. The optimum concentration of Eu in the phosphor and optimum calcination temperature was 3wt% and $1100^{\circ}C$. The prepared phosphors were consist of particle, and its size was between 100nm and 150nm. Among the different polyfunctional alcohols, diethylene glycol(DEG) improved the luminescence intensities of phosphors more than other additives. The Pechini method proved that it is demonstrated to be suitable for the synthesis of phosphors used in PDP.

• 한국세라믹학회지
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• 제39권11호
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• pp.1023-1027
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• 2002

본 연구에서는 초임계 mixing을 이용하여 $SrTiO_3:\;Pr^{3+}$ 형광체 분말을 제조하였으며, 일반적 제조 방법인 고상법으로 제조된 분말과 발광특성을 비교하였다. 초임계 mixing에 의해 제조된 $SrTiO_3:\;Pr^{3+}$ 형광체 분말은 단상의 perovskite 구조를 갖으며, 형상은 구형인 좁은 입도분포를 보인다. 발광특성의 증대를 sensitizer인 $Al^{3+}$과 $Ga^{3+}$을 첨가하여 형광체의 발광특성을 관찰하였다.

• 센서학회지
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• 제3권2호
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• pp.11-15
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• 1994

LiF(Mg,Cu,Na,Si)형광체의 ${\gamma}$ 선과 ${\beta}$ 선에 대한 TSEE 특성을 조사하였다. 이 형광체의 TSEE glow 곡선은 $20^{\circ}C$에서 $400^{\circ}C$사이에서 5개의 피크를 나타내었으며 주피크는 $240^{\circ}C$였다. $^{60}Co$ ${\gamma}$ 선에 대한 형광체의 감도는 약 450 counts/mR 이었다. ${\beta}$ 선에 대한 TSEE 에너지의존성은 ${\beta}$ 입자의 평균에너지 0.02MeV에서 0.8MeV 사이에서 ${\pm}10%$이었다. 그리고 이 형광체의 ${\beta}$ 선에 대한 TSEE 효율은 $(2{\sim}15){\times}10^{-3}$ 이었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.263-265
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• 2005

In the alternative current plasma display panel(AC-PDP) technology, it is very important to remove the image sticking for improving an image quality. In this paper, we have investigated the driving method of alternative current plasma display panel(AC-PDP) for preventing image sticking. We have investigated the driving method of alternative current plasma display panel(AC-PDP) for preventing image sticking. The preventing method of image sticking was proposed by adopting the Sticking Remove Pulse(SRP). The variation of brightness is most affected by the MgO to be formed at the surface of the phosphor layer. As a result, the image sticking is reduced when the driving method adopted an SRP.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.518-521
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• 2004

The degradation characteristics of MgO protective layer and phosphors have been investigated in terms of the ion-induced secondary electron emission coefficient ${\gamma}$ and static margin of discharge voltages, respectively, in this experiment. The ion-induced secondary electron emission coefficients ${\gamma}$ for the degraded MgO protective layer and phosphors have been studied by ${\gamma}$ -focused ion beam system. The energy of Ne+ ions used is from 80 eV to 200 eV in this experiment. The degraded MgO and phosphor layers are found to have higher ${\gamma}$ than that of normal ones without degradations or aged one. Also, the static margin of discharge voltages for test panels with degraded MgO protective layer and phosphors been found to be seriously decreased in comparison with those of normal ones without degradations.

• 한국방사선학회논문지
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• 제13권3호
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• pp.333-338
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• 2019

방사선치료 분야에서는 치료의 안전성을 검증하기 위한 Quality Assurance(QA) 절차가 매우 중요하게 여겨진다. 그러나 일반적으로 이에 사용되는 선량계들의 다양한 문제점 때문에, 이를 대체하기 위한 선량계 연구가 활발히 진행되고 있다. 본 연구에서는 형광체로부터 방출된 visible light(VL)에 의한 Sensitivity 극대화를 위해, 뛰어난 형광 효율을 가지는 형광체인 $Gd_2O_2S:Tb$를 요오드화납(Lead(II) Iodide; $PbI_2$)에 다양한 weight percent(wt%)로 혼합한 Blended hybrid sensor를 제작하였다. 이후 Blended sensor 및 Pure $PbI_2$ sensor의 고에너지 방사선에 대한 반응특성을 비교 및 평가하였다. 민감도 평가결과, 3wt%는 sensor에서 타 sensor들과 40% 이상 차이나는 최댓값이 나타났으며, 이를 제외한 센서에서 wt%의 증가에 따른 점차적 민감도 감소추세를 확인하였다. 또한, 재현성 평가에서는 Pure $PbI_2$ sensor가 coefficient of variation(CV)>0.015의 큰 편차를 보인 반면, blended sensor는 모두 CV<0.015 이하의 결과를 보였다.

• 한국재료학회지
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• 제22권4호
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• pp.195-201
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• 2012

$Ce^{3+}$-doped yttrium aluminum gallium garnet (YAGG:$Ce^{3+}$), which is a green-emitting phosphor, was synthesized by solid state reaction using ${\alpha}$-phase or ${\gamma}$-phase of nano-sized $Al_2O_3$ as the Al source. The processing conditions and the chemical composition of phosphor for the maximum emission intensity were optimized on the basis of emission intensity under vacuum UV excitation. The optimum heating temperature for phosphor preparation was $1550^{\circ}C$. Photoluminescence properties of the synthesized phosphor were investigated in detail. From the excitation and emission spectra, it was confirmed that the YAGG:$Ce^{3+}$ phosphors effectively absorb the vacuum UV of 120-200 nm and emit green light positioned around 530 nm. The crystalline phase of the alumina nanoparticles affected the particle size and the luminescence property of the synthesized phosphors. Nano-sized ${\gamma}-Al_2O_3$ was more effective for the achievement of higher emission intensity than was nano-sized ${\alpha}-Al_2O_3$. This discrepancy is considered to be because the diffusion of $Al^{3+}$ into $Y_2O_3$ lattice is dependent on the crystalline phase of $Al_2O_3$, which affects the phase transformation of YAGG:$Ce^{3+}$ phosphors. The optimum chemical composition, having the maximum emission intensity, was $(Y_{2.98}Ce_{0.02})(Al_{2.8}Ga_{1.8})O_{11.4}$ prepared with ${\gamma}-Al_2O_3$. On the other hand, the decay time of the YAGG:$Ce^{3+}$ phosphors, irrespective of the crystalline phase of the nano-sized alumina source, was below 1 ms due to the allowed $5d{\rightarrow}4f$ transition of the $Ce^{3+}$ activator.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.784-787
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• 2008

Nanoscale $YVO_4:Eu^{3+}$ phosphor has been synthesized by a mild hydrothermal reaction at various experimental conditions. The particle and luminescent properties of nanophosphors were characterized with X-ray diffraction, electron microscopy and photoluminescence. It has been found that pH value play a key factor both controlling particle size and luminous efficiency.