• Title/Summary/Keyword: Halide

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Studies on the Homogeneous Precipitiation of Silver Halide (Silver Halide의 均一沈澱法에 關한 硏究)

  • Park, Doo-Won;Oh, Sang O.
    • Journal of the Korean Chemical Society
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    • v.6 no.2
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    • pp.122-124
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    • 1962
  • The silver halide precipitate tends to separate in curdy form of flocculated colloid when it is precipitated by direct mixing of reactant solutions. This type of precipitate has a great tendency to adsorb or occlude foreign ions in the solution.When silver halide in precipitated from homogeneous solution using the slow hydrolysis of Alkyl halide or Ally halide, the precipitate becomes dense, filterable and uniform in particle size which is very advantageous in gravimetric analysis.We found that silver halide precipitates obtained from homogeneous solution with hydrogen halide formed by the hydrolysis of alkyl halide do not give the color change with fluorescein as adsorption indicater, while silver halide precipitates obtained by direct mixing method give sharply pink color which appear to be uniformly distributed through the solution in silver ion excess.

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Reserch and development of metal halide lamp for LCD projector back light (LCD PROJECTOR BACK LIGHT용 METAL HALIDE LAMP의 연구 및 개발)

  • 박창식;정의선;이승수
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 1995.10a
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    • pp.39-46
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    • 1995
  • Metal halide pamp for LCD projector back light is high technologlcal product with its consumption increasing by 30% a year according to LCD merchandise and we are whollydepending on imprtation. At this time exper iment. we achleved those results as below. 1. Reallzation of domestic production of 150W metal halide lamp for LCD progector back light and electrical ballatst. 2. Possession of self-designing and manufacturing technology of submlnlature metal halide lamp. 3. Possession of deslgning technology of electrlcal ballast for metal hallde lamp.

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Kinetic Studies on Halogen Exchange of 1-Naphthyl Methyl Halides (1-나프틸메틸 할라이드의 할로겐 교환반응)

  • Lee Kae-Soo
    • Journal of the Korean Chemical Society
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    • v.13 no.2
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    • pp.115-120
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    • 1969
  • Kinetics of reactions of halide ions with 1-naphthyl methyl halide have been investigated in anhydrous acetone. Semi-quantitative analysis of the results shows that if the softness of the substrate increases remarkably, the nucleophilicity order of halide ions is $I^- > Br^- > Cl^-$ even in dipolar aprotic solvent. But for 1-naphthyl methyl bromide, though the reaction center which was made soft by symbiosis of bromine atom raises the reactivity of soft nucleophile, nucleophilicity order indicates that soft-soft interaction is interfered by perihydrogen.

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Facile Preparation of Copper(I) Halide-Dimethyl Sulfide Complex and Its Application

  • Park, Il-Hyun;So, Myung-Sub;Park, Koon-Ha
    • Bulletin of the Korean Chemical Society
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    • v.28 no.9
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    • pp.1515-1518
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    • 2007
  • A preparative method of Me2SCuX (X = Cl, Br) via one-pot reaction was developed from common chemicals such as benzyl halide, DMSO, and Cu(0). In the reaction mixture small molecules such as methyl halide and dimethyl sulfide etc. were efficiently generated in situ, resulting in the formation of Me2SCuX. Oxidation of Cu(0) in reacting with both benzyl halide (starting material) and methyl halide (in situ generated product) to Cu(I) followed by complexing with dimethyl sulfide (in situ generated product) could explain the formation of Me2SCuX. In particular we found out that heterogeneous reaction of Me2SCuX and arenediazonium tetrafluoroborate in acetonitrile was so effective to afford corresponding bromoaromatics under mild conditions.

Fabrication and characterization of silver-halide sensitized gelatin diffraction grating derived from Slavich PFG-01 holographic plates (Slavich PFG-01을 이용한 은염 홀로그래피 회절 격자의 제작 및 특성)

  • 임춘우;박성진;석성수;최대욱;오철한
    • Proceedings of the Optical Society of Korea Conference
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    • 2000.02a
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    • pp.292-293
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    • 2000
  • Silver-halide sensitized gelatin(SHSG)의 처리 과정에서 silver-halide입자가 감광유제(emulsion)로부터 제거되고, 노출영역과 비노출영역 사이의 gelatin경화정도로 인한 굴절률 변조로 홀로그램 이미지를 기록한다. 일반적으로 널리 사용되는 홀로그램 감광물질로는 silver-halide, dichromated gelatin, photoresist, photochrome 등이 있는데, 이중 silver-halide는 다른 감광물질과 비교하여 고해상도와 큰 감광대역폭, 높은 S/N비, 취급의 용이성과 경제적 이점, 균일한 제품으로 상용화될 수 있다는 점에서 가장 편리하게 사용되고 있는 기록 매질이다. (중략)

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Adsorption of 2-Cyanonaphthalene on Silver Sol Investigated by Raman Spectroscopy$^\dag$

  • Park, Seong Hyeon;Lee, Eun A;Jang, Du Jeon;Kim, Myeong Su;Kim, Gwan
    • Bulletin of the Korean Chemical Society
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    • v.16 no.2
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    • pp.130-134
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    • 1995
  • Surface-enhanced Raman (SER) scattering of 2-cyanonaphthalene (2-CN) has been investigated in silver sol. Addition of halide ions was needed to obtain authentic SER spectra of the molecule. The SER spectra thus obtained exhibited a slight but noticeable dependence on the kind of halide ions used. This halide-dependent spectral variation was attributed to the orientational change of molecule on silver sol surface. A possible mechanism for such an orientational change is proposed in terms of the competitive adsorption of 2-CN with halide ions on the so-called halide-specific sites.

Recent Progress in Blue Perovskite LEDs

  • Joonyun, Kim;Jinu, Park;Byungha, Shin
    • Korean Journal of Materials Research
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    • v.32 no.11
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    • pp.449-457
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    • 2022
  • Halide perovskites are emerging materials for next-generation display applications, thanks to their narrow emission linewidth and band gap tunability, capable of covering the entire range of visible light. Despite their short period of research, perovskite light emitting diodes (PeLEDs) have shown rapid progress in device external quantum efficiency (EQE) in the near-infrared (NIR), red, and green emission wavelengths, and the record EQE has exceeded over 20 %. However there has been limited progress with blue emission compared to the red and green counterparts. In this review, the current status and challenges of blue PeLEDs are introduced, and strategies to produce spectrally stable blue PeLEDs are discussed. The strategies include 1) a mixed halide system in the form of 3-dimensional (3D) perovskites, 2) colloidal perovskite nanocrystals and 3) low dimensional perovskites, known as quasi-2D perovskites. In the mixed halide system, previous reports based on the compositional engineering of 3D perovskites to reduce spectral instability (i.e., halide segregation) will be discussed. Since spectral instability issue originate from the mixed halide composition in perovskites, the two other strategies are based on enlarging the band gap with a single halide composition. Finally, the prospects for each strategy are discussed, for further improvement in spectrally stable blue PeLEDs.

고효율 할로겐화 페로브스카이트 발광 다이오드의 최근 연구 동향

  • Bae, Sa-Rang;;Kim, Su-Yeong
    • Ceramist
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    • v.21 no.1
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    • pp.24-43
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    • 2018
  • Organic-inorganic halide perovskite materials have attracted significant attention during the last few years because of their superior properties for electronic and optoelectronic devices, such as their long charge carrier diffusion lengths and high photoluminescence quantum yields of up to 100% with tunable bandgaps over the entire visible spectral range. In addition to solar cells, light emitting diodes (LEDs) represent a fascinating application for halide perovskite materials. In this study, we review the recent progress in halide perovskite LEDs. The current strategies for improving the performance of halide LEDs, focusing on morphological engineering, dimensional engineering, compositional engineering, surface passivation, interfacial engineering, and the plasmonic effect are discussed. The challenges and perspectives for the future development of halide perovskite LEDs are also considered.

Development of Electronic Ballast for Metal Halide Lamp wilts Free Voltage Input (프리볼트입력용 메탈핼라이드램프 전자식안정기 개발)

  • 김기정
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.1
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    • pp.20-26
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    • 2002
  • HID(high intensity discharge)lamps include high pressure mercury lamp, high pressure sodium lamp and metal halide lamp. Metal halide lamps have been considered to be one of the most erective light sources. These lamps have good efficiency, good color rendering and good focusing capability. The objective of this research is to alum on the metal halide lamp(MH70W) by the developed electronic ballast with free voltage input(AC 100∼277V). The developed electronic ballast consists of a free voltage input converter, a flyback converter & half-bridge inverter, ignitor & protector and control1er. Experimental results show that developed electronic ballast turns on the metal halide lamp(MH70W) with free voltage input(AC 100∼277V) very well.

Effects of LED Lamps for Replacement of Metal Halide Lamp in Roadway Lighting Environment (LED램프와 메탈램프가 도로조명환경에 미치는 특성 비교평가)

  • Lee, Myung Gi;Kim, Jeong Tai
    • KIEAE Journal
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    • v.13 no.2
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    • pp.47-52
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    • 2013
  • The problems of light pollution first became an issue in the 1970s when astronomers identified the degradation of the night sky due to the increase in lighting associated with development and growth. As more impacts to the environment by lighting have been identified, many attempts have been made for reducing light pollutions. To prevent light pollution and increase energy efficiency, Seoul Metropolitan Government(SMG) replaced metal halide road lighting to LED luminaire in four arterial highway in Seoul. The present study compared the lighting characteristics of metal halide and LED luminaire in terms of Korea Standard for road lighting(KS A 3701) and BUG rating from Illuminating Engineering Society of North America(IESNA). The results showed that LED luminaire increased road surface luminance up to 2 times in average compared to the metal halide environment. Also, LED luminaire reduced the glare value by 2 times and luminous flux over 50% than the metal halide luminaire. In comparison with the BUG ratings, LED luminaire rated 1 degree lower for the backlight ratings and 3-4 degrees lower for the uplight ratings. The measured values testified that the LED luminaire is effective for roadway lighting and light pollution reduction.