• 제목/요약/키워드: $Li_2MnO_3$

검색결과 300건 처리시간 0.028초

송곳니구름버섯(Irpex zonatus) BN2에 의한 아조계, 트리페닐메탄계 및 헤테로싸이클릭계 염료의 탈색 (Decolorization of Azo, Triphenylmethane and Heterocyclic Dyes by Irpex zonatus BN2)

  • 윤경하;최양순
    • 한국균학회지
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    • 제26권1호통권84호
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    • pp.8-15
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    • 1998
  • 우리 나라 자연 환경에서 분리 동정된 송곳니구름버섯(Irpex zonatus) BN2 균주의 리그닌분해효소활성과 아조(azo)계, 트리페닐메탄(triphenylmethane)계 및 헤테로싸이클릭(heterocyclic)계에 속하는 몇몇 염료의 탈색능을 조사하였다. 송곳니구름버섯 BN2 균주는 lignin peroxidase(LiP)와 veratryl alcohol oxidase(VAO)를 생산하지 않고 laccase와 manganese dependent peroxidase(MnP)를 생산했다. MnP는 배양 3일부터 생산되었으나 효소활성은 매우 낮았다. 반면 laccase는 배양 초기부터 지속적으로 생산되었고 활성은 대단히 높았다. 균주를 염료와 함께 10일간 배양했을 때 아조계 염료인 orange II, orange G, tropaeolin O 및 congo red의 탈색율은 각각 98.0%, 97.4%, 99.0% 및 95.3%로 나타났고 트리페닐메탄계 염료인 basic fuchsin, malachite green 및 crystal violet 들은 98.5%, 95.7% 및 99.4%로, 헤테로싸이클릭계 염료에 속하는 eosin Y, toludine blue, methyl blue 및 azur B는 각각 97.4% 98.7%, 99.9% 및 94.0%의 탈색율을 보였다. 송곳니구름버섯 BN2 균주에 의한 염료의 탈색은 주로 laccase에 의하여 이루어진다고 생각된다.

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CsI(Li) 단결정의 섬광특성 (Scintillation Characteristics of CsI(Li) Single Crystals)

  • 이우교;도시홍;노태익;김완;강희동;문병수
    • 센서학회지
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    • 제8권5호
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    • pp.359-367
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    • 1999
  • CsI에 lithium을 활성제로 0.02, 0.1, 0.2 및 0.3 mole% 첨가한 CsI(Li) 단결정을 Czochralski 방법으로 육성하였다. 육성한 CsI(Li) 단결정의 격자구조는 bcc구조였으며, 격자상수 $a_o$ 값은 $4.568\;{\AA}$이었다. CsI(Li) 단결정의 흡수단은 245 nm이였으며, 흡수단으로 여기 시킨 발광스펙트럼의 파장범위는 $300{\sim}600\;nm$이었고 중심파장은 425 nm이었다. Li 농도를 0.2 mole% 첨가한 경우 에너지 분해능은 $^{137}Cs$(662 keV)에 대해서는 14.5%, $^{54}Mn$(835 keV)에 대해서는 11.4%이었고 $^{22}Na$의 511 keV와 1275 keV에 대한 에너지 분해능은 각각 17.7%와 7.9% 이었다. 그리고, $\gamma$선 에너지와 에너지 분해능 사이의 관계식은 ln (FWHM%) = -0.893lnE + 8.456이였으며, 에너지 교정곡선은 ${\log}E_r=1.455\;{\log}(ch.)-1.277$이었다. Li를 0.2 mole% 첨가한 CsI(Li) 단결정의 인광감쇠시간은 실온에서 0.51 s이었고, 일정비율 시간분석법(CFT:constant-fraction timing method)으로 측정한 시간분해능은 9.0 ns 이었다.

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입도분포에 따른 하상퇴적물의 지구화학적 분산 및 부화 (Geochemical Dispersion and Enrichment of Fluvial Sediments Depending on the Particla Size Distribution)

  • 이현구
    • 자원환경지질
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    • 제32권3호
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    • pp.247-260
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    • 1999
  • Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

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Li3PO4 Coated Li[Ni0.75Co0.1Mn0.15]O2 Cathode for All-Solid-State Batteries Based on Sulfide Electrolyte

  • Lee, Joo Young;Park, Yong Joon
    • Journal of Electrochemical Science and Technology
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    • 제13권3호
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    • pp.407-415
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    • 2022
  • Surface coating of cathodes is an essential process for all-solid-state batteries (ASSBs) based on sulfide electrolytes as it efficiently suppresses interfacial reactions between oxide cathodes and sulfide electrolytes. Based on computational calculations, Li3PO4 has been suggested as a promising coating material because of its higher stability with sulfides and its optimal ionic conductivity. However, it has hardly been applied to the coating of ASSBs due to the absence of a suitable coating process, including the selection of source material that is compatible with ASSBs. In this study, polyphosphoric acid (PPA) and (NH4)2HPO4 were used as source materials for preparing a Li3PO4 coating for ASSBs, and the properties of the coating layer and coated cathodes were compared. The Li3PO4 layer fabricated using the (NH4)2HPO4 source was rough and inhomogeneous, which is not suitable for the protection of the cathodes. Moreover, the water-based coating solution with the (NH4)2HPO4 source can deteriorate the electrochemical performance of high-Ni cathodes that are vulnerable to water. In contrast, when an alcohol-based solvent was used, the PPA source enabled the formation of a thin and homogeneous coating layer on the cathode surface. As a consequence, the ASSBs containing the Li3PO4-coated cathode prepared by the PPA source exhibited significantly enhanced discharge and rate capabilities compared to ASSBs containing a pristine cathode or Li3PO4-coated cathode prepared by the (NH4)2HPO4 source.

PNN 치환량에 따른 저손실 저온소결 PMN-PNN-PZT 세라믹스의 압전 및 유전특성 (Piezoelectric and Dielectric Characteristics of Low Loss Low Temperature Sintering PMN-PNN-PZT Ceramics with the amount of PNN Substitution)

  • 류주현;김국진;정영호;이수호
    • 한국전기전자재료학회논문지
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    • 제20권9호
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    • pp.766-770
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    • 2007
  • In this study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, $0.07Pb(Mn_{1/3}Nb_{2/3})O_3-xPb(Ni_{1/3}Nb_{2/3})O_3-(0.93-x)Pb(Zr,Ti)O_3$ ceramics system were fabricated using $Li_2CO_3-Bi_2O_3-CuO$ sintering aids and the specimens were sintered at $930^{\circ}C$. Thereafter, their piezoelectric and dielectric characteristics were investigated according to the amount of PNN substitution. At 9 mol% PNN substitution, density, electromechanical coupling factor ($k_p$), dielectric constant, mechanical quality factor ($Q_m$) and piezoelectric constant ($d_{33}$) showed the optimum value of $7.86g/cm^3$, 0.60, 1640, 1323 and 387 pC/N, respectively. It is considered that these values are suitable for piezoelectric divece application such ad multilayer piezoelectric actuator and ultrasonic vibrator with pure Ag internal electrode.

Improvement of Electrochemical Properties and Thermal Stability of a Ni-rich Cathode Material by Polypropylene Coating

  • Yoo, Gi-Won;Son, Jong-Tae
    • Journal of Electrochemical Science and Technology
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    • 제7권2호
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    • pp.179-184
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    • 2016
  • The interface between the surface of a cathode material and the electrolyte gives rise to surface reactions such as solid electrolyte interface (SEI) and chemical side reactions. These reactions lead to increased surface resistance and charge transfer resistance. It is consequently necessary to improve the electrochemical characteristics by suppressing these reactions. In order to suppress unnecessary surface reactions, we coated cathode material using polypropylene (PP). The PP coating layer effectively reduced the SEI film that is generated after a 4.3 V initial charging process. By mitigating the formation of the SEI film, the PP-coated Li[(Ni0.6Co0.1Mn0.3)0.36(Ni0.80Co0.15Al0.05)0.64)]O2(NCS) electrode provided enhanced transport of Li+ ions due to reduced SEI resistance (RSEI) and charge transfer resistance (Rct). The initial charge and discharge efficiency of the PP-coated NCS electrode was 96.2 % at a current density of 17 mA/g in a voltage range of 3.0 ~ 4.3 V, whereas the efficiency of the NCS electrode was only 94.7 %. The presence of the protective PP layer on the cathode improved the thermal stability by reducing the generated heat, and this was confirmed via DSC analysis by an increased exothermic peak.

Thermal Properties of Mn-doped LiNbO3 Crystals from Magneto-Optical Transitions

  • Park, Jung-Il
    • Journal of Magnetics
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    • 제17권4호
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    • pp.255-260
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    • 2012
  • In this study, we determine that the electron paramagnetic resonance line-width (EPRLW) is axially symmetric about the c-axis and analyze the spin Hamiltonian with an isotopic g-factor of 1.9920 at a frequency of 9.5 GHz. It should be noted that the electron paramagnetic resonance signals are Lorentzian. Our findings show that the EPRLW decreases exponentially with an increase in the temperature; i.e., its temperature dependence in the range 300-400 K obeys Arrhenius behavior, this kind of temperature dependence indicates an off-center a motional narrowing of the spectrum when $Mn^{2+}$ impurity ions substitute for $Nb^{5+}$ ions. The specific heats follow a linear dependence suggesting a simple Debye $T^3$ behavior.

운봉지역 하상퇴적물과 압쇄상화강암류의 지구화학적 특성 비교연구 (Comparative Study on Geochemical Characteristics of Stream Sediments and Mylonitic Granites in the Unbong Area)

  • 박영석;박대우;김종균;김성원
    • 자원환경지질
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    • 제40권6호
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    • pp.727-738
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    • 2007
  • 운봉지역 하상퇴적물에 대한 지구화학적 특성규명을 통해, 주성분원소 및 미량원소에 대한 자연 배경치를 제시하고, 그 기반암(압쇄상화강암, Kim et al., 1992)과의 비교를 통해 지구화학적 재해에 대해 예견하고자 한다. 73개의 하상퇴적 물시료를 물이 흐르고 있는 1차 수계를 대상으로 채취하였고, XRD, XRF ICP-AES, NAA를 이용하여 주성분원소 및 미량성분원소를 분석하였다. 운봉지역의 주성분원소 함량은 $SiO_2\;36.94{\sim}65.39 wt.%,\;Al_2O_3\;10.15{\sim}21.77wt.%,\;Fe_2O_3\;3.17{\sim}10.90wt.%,\;CaO\;0.55{\sim}5.27wt.%,\;MgO\;0.52{\sim}4.94wt.%,\;K_2O\;1.38{\sim}4.54wt.%,\;Na_2O\;0.49{\sim}3.36wt.%,\;TiO_2\;0.39{\sim}1.27wt.%,\;MnO\;0.04{\sim}0.22wt.%,\;P_2O_5\;0.08{\sim}0.54wt.%$의 범위를 보이며, 미량성분 및 희토류원소 함량은, $Cu\;4.8{\sim}134ppm,\;Pb\;24.2{\sim}82.5ppm,\;Sr\;95.9{\sim}739ppm,\;V\;19.9{\sim}124ppm,\;Zr\;52.9{\sim}145ppm,\;Li\;25.2{\sim}3.3ppm,\;Co\;3.87{\sim}50.0ppm,\;Cr\;17.4{\sim}234ppm,\;Hf\;3.93{\sim}25.2ppm,\;Sc\;4.60{\sim}20.6ppm,\;Th\;3.82{\sim}36.9ppm,\;Ce\;45.7{\sim}243ppm,\;Eu\;0.89{\sim}2.69ppm,\;Yb\;1.42{\sim}5.18ppm$의 범위를 보인다. 주성분원소의 함량비교에서 CaO, $Na_2O,\;K_2O$ 함량은 하상퇴적물에서 기반암(압쇄상화강암류, Kim et al., 1992)인 압쇄상화강암류보다 높게 나타난다. 그리고 $Al_2O_3$$SiO_2$는 하상퇴적물과 기반암(압쇄상화강암류, Kim et al., 1992) 모두에서 높은 상관관계를 보인다. 하상퇴적물에서는 $SiO_2$ 함량이 높아질수록 희토류원소 함량도 같이 증가하는 특징을 보이나, 압쇄상화강암류에서는 $SiO_2$ 함량이 높아질수록 희토류원소 함량은 감소하는 특징을 보인다.

Synthesis of Multi-component Olivine by a Novel Mixed Transition Metal Oxalate Coprecipitation Method and Electrochemical Characterization

  • 박영욱;김종순;권혁조;서동화;김성욱;홍지현;강기석
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2010년도 춘계학술발표대회
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    • pp.37.1-37.1
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    • 2010
  • The multi-component olivine cathode material, $LiMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$, was prepared via a novel coprecipitation method of the mixed transition metal oxalate, $Mn_{1/3}Fe_{1/3}Co_{1/3}(C_2O_4){\cdot}2H_2O$. The stoichiometric ratio and distribution of transition metals in the oxalate, therefore, in the olivine product, was affected sensitively by the environments in the coprecipitation process, while they are the important factors in determining the electrochemical property of electrode materials with multiple transition metals. The effect of the pH, atmosphere, temperature, and aging time was investigated thoroughly with respect to the atomic ratio of transition metals, phase purity, and morphology of the mixed transition metal oxalate. The electrochemical activity of each transition metal in the olivine synthesized through this method clearly was enhanced as indicated in the cyclic voltammetry (CV) and galvanostatic charge/discharge measurement. Three distinctive contributions from Mn, Fe, and Co redox couples were detected reversibly in multiple charge and discharge processes. The first discharge capacity at the C/5 rate was $140.5\;mAh\;g^{-1}$ with good cycle retention. The rate capability test showed that the high capacity still is retained even at the 4C and 6C rates with 102 and $81\;mAh\;g^{-1}$, respectively.

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복합고체 전해질을 적용한 리튬이차전지의 전기화학적 특성 (Electrochemical Performance of Rechargeable Lithium Battery Using Hybrid Solid Electrolyte)

  • 한종수;유학균;김재광
    • 전기화학회지
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    • 제24권4호
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    • pp.100-105
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    • 2021
  • 최근 리튬이차전지의 안전성을 향상시킨 전고체 전지가 많은 관심의 대상이 되고 있으나 전도성 세라믹 또는 고체 고분자 전해질을 적용한 고체전지는 높은 계면 저항, 부반응 등과 같은 문제점을 지니고 있어 전기화학적 특성이 낮다. 기존 전고체 전지의 이러한 문제점을 해결하기 위하여 복합고체 전해질이 제안되었으며 본 연구에서는 나시콘 구조의 나노 입자 Li1.5Al0.5Ti1.5P3O12 (LATP) 전도성 세라믹, PVdF-HFP, 카보네이티 기반 액체전해질을 복합화 하여 유사고체 전해질을 제작하였다. 이 복합고체 전해질은 5.6 V의 높은 전압 안전성을 가지며 리튬이온의 탈리-착리 테스트에서 리튬 금속전극의 덴드라이트 성장 억제 효과가 있음을 보여준다. 또한 복합고체 전해질을 적용한 LiNi0.83Co0.11Mn0.06O2 (NCM811)기반 전지에서 4.8 V의 높은 충전 종지 전압에도 241.5 mAh/g의 높은 방전 용량을 나타내며 안정적인 전기화학 반응이 일어난다. NCM811 기반 전지의 90도 충전-방전 중에도 전지의 단락이나 폭발 없이 139.4 mAh/g 방전 용량을 보인다. 따라서 LATP기반 복합고체 전해질은 리튬이차전지의 안전성과 전기화학적 특성을 향상 시킬 수 있는 효과적인 방법임을 알 수 있다.