• 제목/요약/키워드: Dendritic

검색결과 765건 처리시간 0.029초

$Bi_2Te_3-PbTe$계 열전소재의 자연나노구조체 형성 및 특성

  • 임주혁;정규호;김광천;유현우;김진상
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2009년도 추계학술대회 논문집
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    • pp.263-263
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    • 2009
  • The microtstructures and properties of alloys in the pseudo-binary $Bi_2Te_3-PbTe$ system were investigated as a first step towards the design of nanostructured materials with enhanced thermoelectric properties. The liquid alloys were cooled by water quenching method. Dendritic and lamellar structures were observed clearly by using environmental scanning electron microscope(eSEM) and electron probe micro analyzer(EPMA) take into account composition ratio between $Bi_2Te_3$ and PbTe. The compound $Pb_2Bi_6Te_{11}$ precipitated as a metastable phase under all conditions. The structure of those samples changed from dendritic to lamellar by increasing $Bi_2Te_3$ ratio of composition.

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Facile Synthesis of Fréchet Type Dendritic Benzyl Azides and Dendrimer via Cycloaddition Reaction with Tripodal Core

  • Lee, Jae-Wook;Kim, Byung-Ku;Kim, Jung-Hwan;Shin, Won-Suk;Jin, Sung-Ho
    • Bulletin of the Korean Chemical Society
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    • 제26권11호
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    • pp.1790-1794
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    • 2005
  • Fréchet-type dendritic benzyl azides were efficiently synthesized using 5-(azidomethyl)-1,3-dihydroxybenzene as an azide focal point functionalized unit by adding a generation to the existing dendron and applied for the construction of dendrimers containing 1,2,3-triazole rings as connectors via click chemistry with a tripodal acetylene core.

Effect of Electrochemical Oxidation-Reduction Cycles on Surface Structures and Electrocatalytic Oxygen Reduction Activity of Au Electrodes

  • Lim, Taejung;Kim, Jongwon
    • 대한화학회지
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    • 제60권5호
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    • pp.310-316
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    • 2016
  • Oxidation-reduction cycling (ORC) procedures are widely used for cleaning nanoparticle surfaces when investigating their electrocatalytic activities. In this work, the effect of ORC on the surface structures and electrocatalytic oxygen reduction activity of Au electrodes is analyzed. Different structural changes and variations in electrocatalysis are observed depending on the initial structure of the Au electrodes, such as flat bulk, nanoporous, nanoplate, or dendritic Au. In particular, dendritic Au structures lost their sharp-edge morphology during the ORC process, resulting in a significant decrease in its electrocatalytic oxygen reduction activity. The results shown in this paper provide an insight into the pretreatment of nanoparticle-based electrodes during investigation of their electrocatalytic activities.

유체 유동을 동반한 수치상결정 미세구조의 3차원 성장에 대한 수치해석적 연구 (NUMERICAL SIMULATION OF THREE-DIMENSIONAL DENDRITIC GROWTH WITH FLUID CONVECTION)

  • 윤익로;신승원
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2009년 춘계학술대회논문집
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    • pp.355-362
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    • 2009
  • Most material of engineering interest undergoes solidification process from liquid to solid state. Identifying the underlying mechanism during solidification process is essential to determine the microstructure of material which governs the physical properties of final product. In this paper, we expand our previous two-dimensional numerical technique to three-dimensional simulation for computing dendritic solidification process with fluid convection. We used Level Contour Reconstruction Method to track the moving liquid-solid interface and Sharp Interface Technique to correctly implement phase changing boundary condition. Three-dimensional results showed clear difference compared to two-dimensional simulation on tip growth rate and velocity.

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