• Title/Summary/Keyword: preparation method

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The study of Ag coated silica composite preparation by chemical method and their characteristics (화학적 방법에 의한 Ag coated silica 복합체의 제조 및 그 특성에 대한 연구)

  • Park, Sun-Min
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.16 no.6
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    • pp.260-266
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    • 2006
  • Well dispersed uniform silver coated silica was prepared by chemical liquid method. The optimum conditions for preparation of the silver coated silica were as follows: alkaline solution, reaction temperature of $100^{\circ}C$, reaction time of 2 hrs, and amount of Ag of 5wt%. It was found that the prepared silver coated silica were far infrared emissivity of $0.916{\sim}0.918$ and antimicrobial effect of 99.9%.

Preparation and characterization of ZnWO4 nanocrystallines and single crystals

  • Lim, Chang-Sung
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.20 no.5
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    • pp.197-201
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    • 2010
  • $ZnWO_4$ nanocrystallines were prepared from polymeric complex method using microwave irradiation. The average nanocrystalline sizes were 18~25 nm showing an ordinary tendency to increase with the temperatures from 400 to $600^{\circ}C$. Bulk type single crystals of $ZnWO_4$ were grown successfully in the [100], [010] and [001] directions using the Czochralski method. The effect of the growth parameters, such as the rotation speed, pulling rate and diameter of the grown crystals, were examined. The hardness, thermal expansion coefficients and dielectric constants of the crystals were evaluated.

Preparation and EPR Characteristics of $ZnGa_2O_4$ : Mn Phosphor

  • 정하균;박도순;박윤창
    • Bulletin of the Korean Chemical Society
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    • v.19 no.12
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    • pp.1320-1325
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    • 1998
  • ZnGa2O4: Mn phosphors were prepared by a new chemical process, and their photoluminescence and electron paramagnetic resonance characteristics were investigated. The chemical method showed a low temperature formation of phosphors and a rod-type shape of particles. The strong ultraviolet emission was observed in the undoped ZnGa2O4 phosphor, while strong green emission in the Mn2+-activated ZnGa2O4 phosphor. The green emission intensity of the phosphor prepared by the chemical method was much stronger than that prepared by the conventional method. This difference with preparation methods was interpreted as due to the difference in the distribution of Mn2+ in the host lattice. From EPR results, it was explained that the line intensity of the undoped ZnGa2O4 is associated with the electrical conductivity of this material and the concentration quenching of green luminescence of ZnGa2O4: Mn at higher Mn2+ concentration is attributed to the coupling by exchange interaction between Mn2+ ions.

Transmission Electron Microscopy Specimen Preparation for Two Dimensional Material Using Electron Beam Induced Deposition of a Protective Layer in the Focused Ion Beam Method

  • An, Byeong-Seon;Shin, Yeon Ju;Ju, Jae-Seon;Yang, Cheol-Woong
    • Applied Microscopy
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    • v.48 no.4
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    • pp.122-125
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    • 2018
  • The focused ion beam (FIB) method is widely used to prepare specimens for observation by transmission electron microscopy (TEM), which offers a wide variety of imaging and analytical techniques. TEM has played a significant role in material investigation. However, the FIB method induces amorphization due to bombardment with the high-energy gallium ($Ga^+$) ion beam. To solve this problem, electron beam induced deposition (EBID) is used to form a protective layer to prevent damage to the specimen surface. In this study, we introduce an optimized TEM specimen preparation procedure by comparing the EBID of carbon and tungsten as protective layers in FIB. The selection of appropriate EBID conditions for preparing specimens for TEM analysis is described in detail.