• Title/Summary/Keyword: halide

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Suppression Effect in Some Solvent Extration System (특정용매 추출계의 억제효과)

  • Chin Taik Rhee;Young Sam Jung
    • Nuclear Engineering and Technology
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    • v.14 no.3
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    • pp.110-115
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    • 1982
  • The mechanism of the suppression effect of the extraction of microquantities of an element in the presence of microquantities of another element in some solvent extraction systems is considered. For the system of metal halide complex acids, it has been revealed that the principal cause of the suppression phenomenon is due to the dissociation of the compounds extracted into the organic phase. The various factors, such as relative value of distribution ratios of the individual micro and macroelements, stability of halide complex anion are discussed, and a equation relating those factors are derived.

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Fabrication of High Efficiency Silver Halide Holograms by Reversal Bleaching Process (반전표백 방법에 의한 고효율 은염건판 홀로그램 제작)

  • 백성훈;홍석경;김철중
    • Korean Journal of Optics and Photonics
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    • v.2 no.2
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    • pp.89-95
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    • 1991
  • High diffraction efficiency holographic gratings in silver halide emulsion were fabricated by using reversal bleaching process. The diffraction efficiencies of gratings were improved greatly by applying rapid drying procedure with isopropyl alcohol after bleaching with optimized developers. The dependency of diffraction efficiencies on the different groups of developers, the concentration of bleaching solutions, and the drying methods are investigated experimentally and the results were analyzed theoretically. Same as usual reversal bleaching process, the fabricated gratings showed very low scttering compared to those made by conventional bleach process. The maximum diffraction efficiency was 88%.

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The Study on Adaptive ignition for HID lamps according to lamp state (램프 상태 적응형 점등 방법에 관한 연구)

  • Jo, Gye-Hyun;Song, Myoung-Suk;Park, Chong-Yeun
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2004.05a
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    • pp.205-209
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    • 2004
  • The metal halide lamps are now widely used in the application and commercial lighting due to their attracting properties such as good color rendering and high efficiency. But they have the serious problem of acoustic resonance for high frequency operation and they need the high voltage to ignite. So, they have not been applied to indoors. Over the past few years, a considerable number of studies have been conducted on the electronic ballast together with hot restarting and resonance phenomenon. But very few attempts have been made with the adaptive ignition method according to the lamp state. In this paper, electronic ballast is proposed for metal halide lamps with an igniter for adaptive ignition. The proposed electronic ballast can generate different ignition voltages according to the arc tube state.

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The Development of Dimmable Electronic Ballast for 250W Metal Halide Lamp (250 Watt 메탈할라이드 램프용 전자식 Dimming 안정기 개발)

  • Park, Chong-Yeon;Jung, Kwang-Hyun;Shin, Dong-Suk;Park, Young-Gil
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2006.05a
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    • pp.103-107
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    • 2006
  • In this paper, the dimmable electronic ballast for the 250W metal halide lamp was realized by three stage structure. We developed stable the dimming ballast by using a Micro-controller, and measured the output wattage in the dimming range(illumination) from 100% to about 20%. Under the 35% dimming level, it is possible to cause the redution of lamp's life. The dimming performance can reduce the light system's wattage but can reduce the luminance efficiency (lux/watt).

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Technological Progress Towards Commercialization of Organometal Halide Perovskite Solar Cells (유기금속 할라이드 페로브스카이트 태양전지의 상용화를 위한 기술의 진전)

  • Pyun, Sun Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.27 no.12
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    • pp.776-791
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    • 2014
  • A marvellous solar cell technology system based on organometal halide perovskites has recently shown an unprecedented progress in power conversion efficiency (PCE); the certified one of 17.9% and unconfirmed of 19.3%, as well as the estimated electricity with a generating cost lower than the half of conventional methods based on fossil fuels. In this report the present status of stability with regards to moisture, ambient temperature, ultraviolet and lead toxicity as well as the key technological developments for the early commercialization are covered. Comprehensive understanding of material science for perovskites is required, together with complete encapsulation technologies beyond those for OLEDs, in order to ensure a 20-year-longer-than lifetime of PSCs (perovskite solar cells) and the stability according to the IEC 61646 damp heat test standard, which will result in the replacement of silicon solar cells with PSCs.

Reduction of Alkyl Halides by Homonuclear Bridging Hydride, (μ-H)[(η$^5-MeCp)$Mn(CO)₂]₂-ppn+

  • 박용광;김영웅
    • Bulletin of the Korean Chemical Society
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    • v.17 no.3
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    • pp.269-273
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    • 1996
  • Alkyl halides were reduced to the corresponding alkanes by the homonuclear bridging hydride, (μ-H)[(η5-MeCp)Mn(CO)2]2-PPN+ in THF at the elevated temperatures (40-60 ℃) under the pseudo first order reaction conditions where excess of alkyl halide was employed under nitrogen atmosphere. The reaction is of overall second order; first order with respect to [bridging hydride] and first order with respect to [alkyl halide] with the activation parameters, ΔH≠=28.93 kcal/mol and ΔS≠=17.95 e.u. The kinetic data, the ESR evidence and the reaction with cyclopropyl canbinyl bromide ensure that two possible reaction pathways are operable in this reaction: (1) concerted mechanism, and (2) single electron transfer pathway are in competition leading to the same product, the corresponding alkane.

Temperature Driven Phase Transition of Organic-Inorganic Halide Perovskite Single Crystals

  • Byun, Hye Ryung;Kim, Hyo In;Byun, Su Jeong;Park, Dae Young;Jeong, Mun Seok;Byeon, Clare Chisu
    • Journal of the Korean Physical Society
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    • v.73 no.11
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    • pp.1729-1734
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    • 2018
  • Organic-inorganic halide perovskite single crystals undergo phase transition of being cubic, tetragonal, or orthorhombic depending on the temperature. We investigated the $CH_3NH_3PbBr_{3-x}I_x$ single crystals grown by the inverse temperature crystallization method with temperature-dependent UV-Vis absorption and photoluminescence. From the temperature-dependent absorption measurement, the optical band gap is extracted by derivation of absorption spectrum fitting and Tauc plot. In our results, $CH_3NH_3PbBr_{3-x}I_x$ single crystals show that an abrupt change in optical band gap, PL peak position and intensity appears around 120 K - 170 K regions, indicating the phase transition temperature.

Polymer Passivation Effect on Methylammonium Lead Halide Perovskite Photodetectors

  • Kim, Hyojung;Byun, Hye Ryung;Kim, Bora;Kim, Sung Hyuk;Oh, Hye Min;Jeong, Mun Seok
    • Journal of the Korean Physical Society
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    • v.73 no.11
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    • pp.1675-1678
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    • 2018
  • Methylammonium lead halide ($MAPbI_3$) perovskites are considered as promising materials owing to their excellent optical and electrical properties. However, perovskite materials suffer from degradation in air, which limits their practical applications. Here, we demonstrate successful passivation of the $MAPbI_3$ photodetectors through monochloro-para-xylylene (Parylene-C) deposition. The time-dependent photocurrent characteristics were systematically investigated, and we achieved significantly improved device performance and stability with Parylene-C passivation. Based on the excitation-power-dependent photoluminescence (PL) data, we confirmed that Parylene-C can reduce the carrier losses in $MAPbI_3$, leading to the enhancement of photocurrent and PL in $MAPbI_3$ photodetectors.