• 제목/요약/키워드: chemical materials

검색결과 11,555건 처리시간 0.045초

Functional Li-M (Ti, Al, Co, Ni, Mn, Fe)-O Energy Materials

  • Kim, In Yea;Shin, Seo Yoon;Ko, Jea Hwan;Lee, Kang Soo;Woo, Sung Pil;Kim, Dong Kyu;Yoon, Young Soo
    • 한국세라믹학회지
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    • 제54권1호
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    • pp.9-22
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    • 2017
  • Many new functional materials have been studied for efficient production and storage of energy. Many new materials such as sodium-based and sulfide-based materials have been proposed for energy storage, but research on Li batteries is still dominant. Due to the influence of environmental concerns regarding nuclear energy, interest in and research on fusion power are steadily increasing. For the commercialization of nuclear fusion, a design standard based on a considerable level of physical analysis and modeling is proposed. Nevertheless, limitations of existing materials in nuclear fusion environments limit practical applications. Tritium propagation material for continuous fusion reaction is one of the core materials, and therefore research on this material is being carried out intermittently. The key material for Li-based energy storage and tritium generation is the functional material Li-M-O. In this review, a structural description of functional Li-M-O system materials and technical trends for its applications are introduced.

Vapor Phase Epitaxy of Magnesium Oxide on Si(001) Using a Single Precursor

  • Lee, Sun-Sook;Lee, Sung-Yong;Kim, Chang G.;Lee, Sang-Heon;Nah, Eun-Ju;Kim, Yunsoo
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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    • pp.122-122
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    • 2000
  • Magnesium oxide is thermodynamically very stable, has a low dielectric constant and a low refractive index, and has been widely used as substrate for growing various thin film materials, particulary oxides of the perovskite structure. There has been a considerable interest in integrating the physical properties of these oxides with semiconductor materials such as GaAs and Si. In this regard, it is considered very important to be able to grow MgO buffer layers epitaxially on the semiconductors. Various oxide films can then be grown on such buffer layers eliminating the need for using MgO single crystal substrates. Vapor phase epitaxy of magnesium oxide has been accomplished on Si(001) substrates in a high vacuum chamber using the single precursor methylmagnesium tert-butoxide in the temperature range 750-80$0^{\circ}C$. For the epitaxy of the MgO films, SiC buffer layers had to be grown on Si(001). The films were characterized by reflection high energy electron diffraction (RHEED) in situ in the growth chamber, and x-ray diffraction (XRD), x-ray pole figure analysis, scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS) after the growth.

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Resistance Switching Phenomena in Fe203 Thin Films Using

  • Lee, Sung-Yong;Lee, Jun-Young;So, Byung-Soo;Bae, Seung-Muk;Hwang, Jin-Ha;Lee, Ho-Min;Lee, Sun-Sook;Chung, Taek-Mo;Kim, Chang-Gyoun;An, Ki-Seok;Kim, Yeong-Cheol
    • 한국반도체및디스플레이장비학회:학술대회논문집
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    • 한국반도체및디스플레이장비학회 2007년도 춘계학술대회
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    • pp.251-251
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    • 2007
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One-step Microwave Synthesis of Hierarchical Structured LiFePO4 using Citric Acid

  • Wu, Mihye;Choi, Sungho;Kang, Yongku;Jung, Ha-Kyun
    • Bulletin of the Korean Chemical Society
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    • 제35권10호
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    • pp.2901-2905
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    • 2014
  • The hierarchical-structured $LiFePO_4$ cathode materials were synthesized by one-step microwave synthesis, and their electrochemical properties were investigated. Addition of citric acid during the reaction lead to the formation of hierarchical structured $LiFePO_4$, which has both nano- and micron-characteristics advantageous for energy density and electrode fabrication. Adjusting the molar ratio of Fe to citric acid enhanced the electrochemical properties of $LiFePO_4$.

Carbon Nanofibers with Controlled Size and Morphology Synthesized with Ni-MgO Catalyst Treated by Mechanochemical Process

  • Fangli Yuan;Ryu, Ho-Jin;Kang, Yong-Ku;Park, Soo-Jin;Lee, Jae-Rock
    • 반도체디스플레이기술학회지
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    • 제3권1호
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    • pp.9-13
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    • 2004
  • Carbon nanofibers (CNFs) with uniform diameter and controlled size were prepared from catalytic decomposition of $\textrm{C}_{2}\textrm{H}_{2}$ with Ni-MgO catalyst treated by mechanochemical (MC) process. The properties of Ni catalyst, such as size, distribution and morphology, can be governed by tuning grinding time in MC process. As a result, size and structure of CNFs can be tailored. The effect of grinding time to the as-grown CNFs was studied. CNFs with diameter from 10-70 nm were synthesized. CNFs with bundle formation sharing one tip and twisted CNFs were also synthesized with catalyst treated by MC process.

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Preparation of Nanoflake Bi2MoO6 Photocatalyst Using CO(NH2)2 as Structure Orientation and Its Visible Light Degradation of Tetracycline Hydrochloride

  • Hu, Pengwei;Zheng, Dewen;Xian, Yuxi;Hu, Xianhai;Zhang, Qian;Wang, Shanyu;Li, Mingjun;Cheng, Congliang;Liu, Jin;Wang, Ping
    • 한국재료학회지
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    • 제31권6호
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    • pp.325-330
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    • 2021
  • Bi2MoO6 (BMO) via the structure-directing role of CO(NH2)2 is successfully prepared via a facile solvothermal route. The structure, morphology, and photocatalytic performance of the nanoflake BMO are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectrum analysis (PL), UV-vis spectroscopy (UV-vis) and electrochemical test. SEM images show that the size of nanoflake BMO is about 50 ~ 200 nm. PL and electrochemical analysis show that the nanoflake BMO has a lower recombination rate of photogenerated carriers than particle BMO. The photocatalytic degradation of tetracycline hydrochloride (TC) by nanoflake BMO under visible light is investigated. The results show that the nanoflake BMO-3 has the highest degradation efficiency under visible light, and the degradation efficiency reached 75 % within 120 min, attributed to the unique hierarchical structure, efficient carrier separation and sufficient free radicals to generate active center synergies. The photocatalytic reaction mechanism of TC degradation on the nanoflake BMO is proposed.

Synthesis of the sulfide phosphors and white light generation based on InGaN chip

  • Kim, Kyung-Nam;Kim, Jae-Myung;Choi, Kyoung-Jae;Park, Joung-Kyu;Kim, Chang-Hae
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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    • pp.679-682
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    • 2004
  • $SrGa_2S_4$:Eu green phosphor and SrS:Eu red phosphor have been synthesized by co-precipitation method, respectively. Two sulfide phosphors were influenced by oxygen defect in host materials. Excitation spectra of these phosphors have high efficiency at the long wavelength region. And emission efficiency is increased under the excitation wavelength of 465nm. The combination of thiogallate green phosphor and sulfide red phosphor based on blue light InGaN chip has made it possible to emit white light.

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Fabrication of Nanostructured WC/Co Alloy by Chemical Processes

  • Kim, Byoung-Kee;Ha, Gook-Hyun
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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    • pp.346-347
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    • 2006
  • New manufacturing processes, such as thermochemical, mechanochemical and chemical vapor condensation processes have been developed to obtain nanostructured WC/Co materials. Nanoscale size WC/Co composite powders of near 100-150nm can be synthesizes by thermochemical and mechanochemical processes using water soluble precursors. Non-agglomerated and nano sized WC powder can be synthesized by the chemical vapor condensation process using metallorganic precursors as starting materials. In this paper, the scientific and technical issues on synthesis and consolidation of nanostructured WC/Co alloys produced by new chemical processes are introduced.

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Polymide 6에서 Cyclic Diphosphonate Ester와 Melamine의 난연 효과 (Flame Retardant Synergistic Performance between Cyclic Diphosphonate Ester and Melamine in Polyamide 6)

  • Wang, Xueli;Jiang, Jianming;Yang, Shenglin;Jin, Junhong;Li, Guang
    • 폴리머
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    • 제32권2호
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    • pp.125-130
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    • 2008
  • A commercial cyclic diphosphonate ester (TPMP) and melamine (MA) was combined and added to polyamide 6 (PA6) to prepare the fire retardant PA6. An increase of the oxygen index to 28.6 as well as an improvement of the UL-94 classification to V-0 rating was observed. Cone measurements explained the rate of heat release (RHR) decreased and TGA showed the early decomposition and high solid residue due to co-addition of TPMP and MA, suggesting the occurrence of synergistic effect of TPMP and MA on fire resistance of PA6. The morphology of the char developed during combust ion showed the appearance of thick, intumescent cells on the surface of retardant PA6, which protects the underlying material from the action of the heat flux or flame and limits the diffusion of combustible volatile products towards the flame and oxygen.