• 한국세라믹학회지
• /
• 제47권6호
• /
• pp.503-508
• /
• 2010

$Eu^{2+}$-doped $\beta$-SiAlONs ($Si_{6-z}Al_zO_zN_{8-z}:Eu_y$) are recognized as promising phosphor materials to build an white LED for lighting application due to its excellent absorption/emission efficiency in the long wave length region. In this research, the fabrication of $\beta$-SiAlON:Eu plate phosphor by sintering was investigated with fixed Eu content(y) and varied composition of the host lattice(z). The addition of the activator $Eu_2O_3$ lead to enhanced densification by forming the transient liquid phase. The refinement of a composition by the calculated lattice parameter indicated that the measured composition of the fabricated specimens is nearly same to that of designed one. The single phase $\beta$-SiAlON:Eu plate with relative density of 96.4% was achieved by addition of 2 wt% CaO, which implies the possibility of full densification by adjusting the processing variables.

• E2M - 전기 전자와 첨단 소재
• /
• 제8권6호
• /
• pp.752-758
• /
• 1995

Red emitting CaS:Eu,S electroluminescent(EL) device prepared at 550.deg. C by an electron-beam evaporation technique, demonstrated luminance of 175cd/m$\^$2/ and efficiency of 0.311m/W with 3kHz drive. Luminance was increased with the increase of applied voltage and frequency. From the results of the PL spectrum and the EL spectrum, the CaS:Eu, S device showed emission peak near 640nm resulted from the transition of EU$\^$2+/ 4f$\^$6/5d.rarw.4f$\^$7/. The capacitance of the phosphor layer from the Sawyer-Tower circuit was 10.5nF/cm$\^$2/.

• Current Optics and Photonics
• /
• 제1권6호
• /
• pp.613-617
• /
• 2017

Due to optimal advances such as chromatic performance, durability, low power consumption, high efficiency, long-lifetime, and excellent environmental friendliness, white LEDs (WLEDs) are widely used in vehicle front lighting, backlighting, decorative lighting, street lighting, and even general lighting. In this paper, the remote packaging WLEDs (RP-WLEDs) with bi-layer red-emitting $Sr_2Si_5N_8:Eu^{2+}$ and yellow-emitting YAG:Ce phosphor was proposed and investigated. The simulation results based on the MATLAB software and the commercial software Light Tools indicated that the color rendering index (CRI) of bi-layer phosphor RP-WLEDs had a significant increase. The CRI had a considerable increase from 72 to 94. In conclusion, the results showed that bi-layer red-emitting $Sr_2Si_5N_8:Eu^{2+}$ and yellow-emitting YAG:Ce phosphor could be a prospective approach for manufacturing RP-WLEDs with enhanced optical properties.

• 대한화학회지
• /
• 제48권4호
• /
• pp.371-378
• /
• 2004

기존의 $SrGa_2S_4:Eu^{2+}$ 녹색 발광 형광체는 주로 CRT (Cathode Ray Tube)용이나 FED (Field Emission Display), 그리고 EL (Electroluminescence)용 발광소자로 많이 연구되어졌다. 현재는 장파장 영역의 여기 특성을 이용한 LED (Light Emitting Diode)용 형광체로 주목 되어지고 있다. $SrGa_2S_4:Eu^{2+}$ 형광체의 일반적 합성 방법은 Flux를 이용하여 인체에 유해한 $H_2S$나 $CS_2$ 기체를 사용할 뿐만 아니라 높은 합성온도, 긴 반응시간 및 공정이 복잡한 단점을 지니고 있다. 따라서 본 실험은 황화물계 원료인 SrS, $Ga_2S_3$ 그리고 EuS를 출발 물질로 하여 $H_2S$ 기체를 사용하지 않고 혼합 기체$(5% H_2/95% N_2)$를 사용해 환원 분위기 하에서 $SrGa_2S_4:Eu^{2+}$을 합성하였다. 그리고 다양한 합성 조건과 LED용으로 사용되기 위해 수세처리와 Sieving 과정을 거친 형광체의 발광특성을 검토하였다.

• 한국재료학회지
• /
• 제14권8호
• /
• pp.529-534
• /
• 2004

$Sr_{4}Al_{14}O_{25}$ was synthesized by solid state reaction with flux. $H_{3}BO_3$ was used to synthesize $SrO-Al_{2}O_{3}$ phosphor system as a flux. The effect of doping system such as Eu+Dy, Eu, and Ce on the luminescent properties of $Sr_{4}Al_{14}O_{25}$ was investigated. Both PL spectra of $Sr_{4}Al_{14}O_{25}$:Eu and $Sr_{4}Al_{14}O_{25}$:Eu+Dy excited at 390 nm showed greenish-blue emission at about 490 nm, while the emission wavelength was shifted to 400 nm by doping Ce. The reduction of $Eu^{3+}$ ions to $Eu^{2+}$ could be accomplished by the annealing process under $N_{2}^{+}$ vacuum atmosphere, and attributed to the emission at 490 nm. It is verified that $Sr_{4}Al_{14}O_{25}$:Eu phosphor is suitable for white LEDs became of a broad absorption band peaking at 390 nm.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 1994년도 제6회 학술발표회 논문개요집
• /
• pp.43-43
• /
• 1994

We studied chemical reactio of Eu metal on the in situ cleaved CdTe(110) surface by pphotoemission sppectroscoppy using synchrotron radiation. The chamber was maintained with base ppressure $\leq$2${\times}$10-10 mb during the expperiment. The expperiment was carried out in pphoton Factory in Jappan. Core level pphotoemission sppectroscoppy was carried out with Al K${\alpha}$ Line. The CdTe simiconductor was determined to be pp-typpe with low dopping concentration from Hall measurement. We found that there are two reacted pphases of Te with Eu (related to divalent Eu and trivalent Eu, resppectively) from least square fitting of Te 4d sppectra, but three is no indication of Cd reaction. Trivalent Eu exists after roughly one monolayer depposition (600 sec. depposition time is considered as one monolayer), which is also observed at Eu 3d core level sppectra. Overlayer Eu is metallized after roughly 2 monolayers depposition, as can be deduced from the fact that metallic edge near Fermi level begins to appear. The intensity of core-level of Te decreases expponentially at the initial stage (near one monolayer) and after one monolayer depposition it decreases more slowly due to Te out-diffusion. We categorized the growth mode of Eu on CdTe as S-K growth mode (cluster formation after one monolayer deppisition) from the relative intensity pplot of Te 4d normalized to the cleaved surface. At cleaved surface band bending is already established due to surface defects. At first 100 sec. depposition time the shift toward lower binding side by 0.6 eV is found at all core level sppectra of all elements in semiconductor. This shift is considered as the re-adjustment of surface Fermi level to the pposition induced by Eu metal (0.2 eV above the valence band maximum).

• Bulletin of the Korean Chemical Society
• /
• 제32권5호
• /
• pp.1745-1747
• /
• 2011

• 정보과학회지
• /
• 제30권10호
• /
• pp.34-41
• /
• 2012

• Journal of Ceramic Processing Research
• /
• 제13권spc2호
• /
• pp.189-192
• /
• 2012

Manufacturing process for silicate glass phosphors containing Eu2+ activator and their photoluminescence property have been studied. We adopted powder sintering process instead of traditional glass melting process for making glass phosphor. At first, phosphor powders were synthesized at 1200 ℃ for 2-3 hours under a reducing atmosphere with 10% H2-90% N2 gas mixture. The reduced powders were compacted into discs and then the discs weresintered at 1400 ~ 1500 ℃ for 1 hr under a reducing atmosphere of 5H2-95% N2. The enhancement of PL intensity by Al2O3 addition, XPS binding energy shift of Si 2p and O 1s, sintering shrinkage, and crystallization were characterized.

• 한국결정성장학회지
• /
• 제23권4호
• /
• pp.195-200
• /
• 2013

고상반응법으로 Ba-Y-Si-계 산질화물 황색 형광체를 합성하였고, 형광체의 발광특성에 미치는 고상반응온도, 환원 열처리 온도 및 $Eu^{2+}$ 활성제 농도의 영향에 대하여 조사하였다. 고상반응온도 $1400^{\circ}C$, 환원 열처리 온도 $1300^{\circ}C$가 최적화된 온도조건으로 조사되었다. 450 nm 파장의 여기 광원에 대하여 합성된 $Ba_9Y_{2+y}Si_6O_{24-3y}N_{3y}:Eu^{2+}$ 형광체는 571~585 nm 영역의 중심파장을 갖는 단일 발광밴드 특성을 나타내었다. 활성제 $Eu^{2+}$ 농도가 3 mol%일 때 가장 강한 발광강도가 얻어졌으며, 5 mol% 이상의 농도에서는 농도소광현상이 관찰되었다. FE-SEM 및 PSA 분석 결과 합성된 형광체는 약 $8.2{\mu}m$의 평균 입경을 갖는 것으로 확인되었다.