• Title/Summary/Keyword: $SrSi_2O_2N_2$

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UV pumped three color phosphor blend White emitting LEDs

  • Choi, Kyoung-Jae;Park, Joung-Kyu;Kim, Kyung-Nam;Kim, Chang-Hae;Kim, Ho-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07b
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    • pp.1338-1342
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    • 2005
  • We have synthesized an $Eu^{2+}$-activated $Sr_3MgSi_2O_8$ blue phosphor and $Ba_2SiO_4$ green phosphor and $Ba^{2+}$ co-doped $Sr_3SiO_5$ red phosphor investigated an attempt to develop white LEDs by combining it with a GaN blue LED $chip(\lambda_{em}=405 nm)$. Three distinct emission bands from the GaN-based LED and the $(Sr_3MgSi_2O_8:Eu\; +\; Ba_2SiO_4:Eu\; +\; Ba^{2+}\; co-doped\; Sr_3SiO_5:Eu)$ phosphor are clearly observed at 460nm, 520 nm and at around 600 nm, respectively. These three emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (405 nm chip)-based $(Sr_3MgSi_2O_8:Eu\; +\; Ba_2SiO_4:Eu\; +\; Ba^{2+}\; co-doped\; Sr_3SiO_5:Eu) exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

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Structure of SrO-B2O3-Al2O3 and SrO-B2O3-SiO2 glasses Using 11B Nuclear Magnetic Resonance (11B NMR 방법에 의한 SrO-B2O3-Al2O3와 SrO-B2O3-SiO2 유리들의 구조에 관한 연구)

  • Moon, Seong-Jun
    • Journal of Korean Ophthalmic Optics Society
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    • v.7 no.2
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    • pp.19-25
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    • 2002
  • Ternary $xSrO-yB_2O_3-0.1Al_2O_3$ and $xSrO-yB_2O_3-0.1SiO_2$ glasses were prepared as a function of R(${\equiv}x/y$). The fraction of four-coordinated brans ($N_4$), symmetric three-coordinated barons ($N_{3S}$), and asymmetric three-coordinated barons ($N_{3A}$) were determined quantitatively to study the structures of these glasses by $^{11}B$ NMR. The values of $Q_{cc}$ and ${\eta}$ for $BO_3$ unit in the glasses were 2.74MHz and 0.22, those for $BO_3{^-}$ unit were 2.54MHz and 0.55, and those for $BO_4$ unit 0.60~0.75MHz and 0.00, respectively. The structure of SrBAl glass at $R_{1st}$ consisted of tetraborate ($[B_8O_{13}]^{-2}$) units and 1st-modified diborate ($[B_2Al_2O_7]^{-2}$) units, and those for the glass at $R_{max}$consisted of diborate ($[B_4O_7]^{-2}$) units, metaborate ($[BO_2^{-1}]$), 1st-modified diborate units, and 2nd-modified diborate ($[B_2Al_2O_8]^{-4}$) units. Due to the oxygens introduced from the strontium oxide. $AlO_4$ units were preferably formed rather than $BO_4$ units. And, the structure of SrBSi glasses in the region $R{\leq}0.5$ could be viewed as binary $SrO-B_2O_3$ glasses structure diluted by silicate oxide: therefore, the Si atoms of the glasses did not contributed to the change the configuration around the boron atoms. The silicate oxide was formed the $SiO_4{^-}$ units rather than the $BO_3{^-}$ units by the oxygens introduced from the storntium oxide in the region of $R{\geq}R_{max}$, and structure of those glass at $R_{max}$ consisted of diborate units, metaborate units loose $BO_4([BO_2]^{-1})$, and $SiO_4{^-}([SiO_{2.5}]^{-1})$ units.

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Optical Properties of the Eu2+ Doped Li2SrSiO4-αNα (Li2SrSiO4-αNα에 첨가된 Eu2+의 광학적 특성)

  • Namkhai, Purevdulam;Kim, Taeyoung;Woo, Hyun-Joo;Jang, Kiwan;Jeong, Jung Hyun
    • New Physics: Sae Mulli
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    • v.68 no.11
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    • pp.1196-1202
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    • 2018
  • $Li_2Sr_{1-x}Eu_xSiO_{4-{\alpha}}N_{\alpha}$ ($Li_2SrSiO_{4-{\alpha}}N_{\alpha}:Eu^{2+}$) phosphors were synthesized by using a solid state reaction (SSR) method with submicron $Si_3N_4$ and nano $Si_3N_4$ powders as the sources of Si and N, and the optical properties of those phosphors were studied. The studied phosphors showed efficient excitation characteristics over the broad range from 230 to 530 nm. Also, They showed broad emission spectra covering a range from 500 to 700 nm, with a peak at 568 nm, which was shifted longer wavelength by 18 nm as compared with that of commercial $YAG:Ce^{3+}$. Combined with a 450 nm blue LED chip, the results support the application of the $Li_2SrSiO_{4-{\alpha}}N_{\alpha}:Eu^{2+}$ phosphor as a luminescent material for a white-light source thaat is warmer than the commercial $YAG:Ce^{3+}$ white-light source. In addition, the $Li_2SrSiO_{4-{\alpha}}N_{\alpha}$ phosphors prepared from a submicron $Si_3N_4$ powder was found to emit a previously unreported self-activated luminescence in $Li_2SrSiO_{4-{\alpha}}N_{\alpha}$.

Luminescence Characteristics of Sr3MgSi2O8:Eu Blue Phosphor for Light Emitting Diodes (LED용 Sr3MgSi2O8:Eu청색 형광체의 발광특성)

  • 최경재;박정규;김경남;김창해;김호건
    • Journal of the Korean Ceramic Society
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    • v.41 no.8
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    • pp.573-577
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    • 2004
  • We have synthesized a Eu$^{2+}$-activated Sr$_3$MgSi$_2$ $O_{8}$ blue phosphor and investigated an attempt to develop blue LEDs by combining it with a InGaN blue LED chip (Len=405 nm). The InGaN-based Sr$_3$MgSi$_2$ $O_{8}$:Eu LED Lamp shows two bands at 405 nm and 460 nm. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This 405 nm emission was used as an optical transition of the Sr$_3$MgSi$_2$ $O_{8}$:Eu phosphor. The 460 m emission band is ascribed to a radiative recombination of Eu$^{2+}$ impurity ions in the Sr$_3$MgSi$_2$ $O_{8}$ host matrix. As a consequence of a preparation of W blue LED Lamp using the Sr$_3$MgSi$_2$ $O_{8}$:Eu blue phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/blue phosphor(1/0,202). At this time, the CIE chromaticity was x=0.1417 and y=0.0683.

The Potential Barrier Scavenging Effects of the Charged Colloidal Semiconductors at the Magnetized SrO${\cdot}6Fe_{2}O_{3}$ Ceramics Interfaces (자화된 SrO${\cdot}6Fe_{2}O_{3}$ Ceramics 계면에서 대전된 colloid 반도체의 전위장벽 청소효과)

  • Jang Ho Chun
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.29A no.4
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    • pp.22-27
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    • 1992
  • The cyclic voltammogram characteristics at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ ceramics/(($10^{-3}$M KCI + p-Si powders) and /(($10^{-4}$M CsNO$_3$ + n-GaAs powders) suspension interfaces have been studied using the microelectrophoresis and the cyclic voltammetric method. The negatively charged ions are specifically absorbed on the virgin and the magnetized SrO${\cdot}6Fe_{2}O_{3}$ ceramics surfaces. The zeta potentials of the p-Si and n-GaAs colloidal semiconductors are + 41mV and -44.8mV, respectively. The magnetization effects act as potential barriers at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ interfaces. The positivelely charged p-Si and the negatively charged n-GaAs colloidal semiconductors act as potential barriers at the virgin SrO${\cdot}6Fe_{2}O_{3}$ interfaces. On the other hand, the charged p-Si and n-GaAs colloidal semiconductors act as potential barrier scavengers at the magnetized SrO${\cdot}6Fe_{2}O_{3}$ interfaces. The magnetization effects and the charged colloidal semiconductor effects are irreversible and interdependent.

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UV pumped two color phosphor blend White emitting LEDs

  • Choi, Kyoung-Jae;Park, Joung-Kyu;Kim, Kyung-Nam;Kim, Chang-Hae;Kim, Ho-Kun
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.636-639
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    • 2004
  • We have synthesized a $Eu^{2{\cdot}}$ -activated $Sr_3MgSi_2O_8$ blue phosphor and $Ba^{2{\cdot}}$ co-doped $Sr_2SiO_4$ yellow phosphor investigated an attempt to develop white LEDs by combining it with a GaN blue LED chip. Three distinct emission bands from the GaN-based LED and the ($Sr_3MgSi_2O_8$:Eu + $Ba^{2{\cdot}}$ co-doped $Sr_2SiO_4$:Eu) phosphor are clearly observed at 405nm, 455 nm and at around 540 nm, respectively. These three emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (405 nm chip)-based ($Sr_3MgSi_2O_8$:Eu + $Ba^{2{\cdot}}$ co-doped $Sr_2SiO_4$:Eu) exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.

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Synthesis and Optical Properties of M-Si(Al)-O-N (M: Sr, Ca) Phosphors for white Light Emitting Diodes (백색 발광다이오드용 M-Si(Al)-O-N (M: Sr, Ca) 형광체의 합성 및 발광 특성)

  • Lee, Seung-Jae;Lee, Jun-Seong;Kim, Young-Jin
    • Journal of the Microelectronics and Packaging Society
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    • v.19 no.2
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    • pp.41-45
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    • 2012
  • Oxynitride green phosphors for white light emitting diodes (LEDs) were synthesized and their optical properties were evaluated. The N/O ratio ($\delta$) of $SrSi_2O_{2-{\delta}}N_{2+2/3{\delta}}:Eu^{2+}$ closely depended on the synthesizing conditions. The most excellent green emission (545 nm), which was assigned to the $5d{\rightarrow}4f$ transition of $Eu^{2+}$ ions, was achieved at the conditions of $1700^{\circ}C$, 5 mol% $Eu^{2+}$, and $H_2$ atmosphere. The well-developed $Ca-{\alpha}-SiAlON:Yb^{2+}$ particles with homogeneous size were obtained at m = 3 (n = 0.15) for the compound of $Ca_{0.5m-0.005}Yb_{0.005}Si_{12-(m+n)}Al_{m+n}O_nN_{16-n}$, resulting in the strong green emission at around 550 nm.

Synthesis and Luminescent Characteristics of (Sr,Ba)2Ga2SiO7:Eu2+ Green Phosphor for LEDs (LED용 (Sr,Ba)2Ga2SiO7:Eu2+ 녹색 형광체의 합성 및 발광특성)

  • Park, Jeong-Gyu;Lee, Seung-Jae;Yeon, Jeong-Ho
    • Journal of the Korean Chemical Society
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    • v.50 no.2
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    • pp.137-140
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    • 2006
  • In this report, Europium doped strontium barium gallium silicate ((Sr,Ba)2Ga2SiO7:Eu2+) phosphor has been synthesized by conventional solid-state method and investigated luminescent characteristic. Appropriate proportions of the raw materials were mixed in an agate mortar with acetone to obtain starting mixtures. Also, this phosphor was prepared by simple process under the reduction atmosphere (25% H2/75% N2). This phosphor can be applicated to the green phosphor for white LED because it has green emission band (513 nm), which emits efficiently under the 405nm excitation energy.

Luminescence Characteristics of Blue and Yellow Phosphor for Near-Ultraviolet (자외선 여기용 청색 및 황색 형광체의 발광특성)

  • Choi, Kyoung-Jae;Park, Joung-Kyu;Kim, Kyung-Nam;Kim, Chang-Hae;Kim, Ho-Kun
    • Journal of the Korean Ceramic Society
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    • v.43 no.5 s.288
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    • pp.304-308
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    • 2006
  • We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the $Sr_3MgSi_2O_8:Eu$ and $(Sr,Ba)_2SiO_4$ host matrix. As a consequence of a preparation of UV White LED lamp using the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x = 0.3140, CIE y = 0.3201 and CCT (6500 K).

The Contact Characteristics of Ferroelectrics Thin Film and a-Si:H Thin Film (강유전성 박막의 형성 및 수소화 된 비정질실리콘과의 접합 특성)

  • 허창우
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.3
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    • pp.468-473
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    • 2003
  • In this paper, for enhancement of property on a-Si:H TFTs We measure interface characteristics of ferroelectrics thin film and a-Si:H thin film. First, SrTiO$_3$ thin film is deposited bye-beam evaporation. Deposited films are annealed for 1 hour in N2 ambient at $150^{\circ}C∼600^{\circ}C$. Dielectric characteristics of deposited SrTiO$_3$ films are very good because dielectric constant shows 50∼100 and breakdown electric field are 1 ∼ 1.5 MV/cm. a-SiN:H,a-Si:H(n-type a-Si:H) are deposited onto SrTiO$_3$ film to make MFNS(Meta1/ferroelectric/a-SiN:H/a-Si:H) by PECVD. After the C-V measurement for interface characteristics, MFNS structure shows no difference with MNS(Metal/a-SiN:H/a-Si:H) structure in C-V characteristics but the insulator capacitance value of MFNS structure is much higher than the MNS because of high dielectric constant of ferroelectric.