• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 추계총회,초청강연,특별강연,연구발표회
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• pp.129.1-129
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• 2000

• 한국전기전자재료학회논문지
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• 제20권5호
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• pp.443-449
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• 2007

The structural and thermal stability of $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ electrode during cycling process was studied. The sample was prepared by simple combustion method. Although there were irreversible changes on the initial cycle, O3 stacking for $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ structure was retained during the first and subsequent cycling process. Impedance of the test cell was decreased after the first charge-discharge process, which would be of benefit to intercalation and deintercalation of lithium ion on subsequent cycling. As expected, cycling test for 75 times increased impedance of the cell a little, instead, thermal stability of $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ was improved. Moreover, based on DSC analysis, the initial exothermic peak was shifted to high temperature range and the amount of heat was also decreased after cycling test, which displayed that thermal stability was not deteriorated during cycling.

• Journal of Magnetics
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• 제10권2호
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• pp.44-47
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• 2005

The oscillatory interlayer exchange coupling (IEC) has been shown in pinned $[CoFe/Pt(t_{pt})/CoFe]/IrMn$ multi-layers with perpendicular anisotropy. The period of oscillation corresponds to about 2 monolayers of Pt. The oscillatory behavior of IEC depending on the nonmagnetic metallic Pt thickness is thought to be related the antiferromagnetic ordering induced by IrMn layer. Oscillatory IEC as function of insulating NiO thickness has been observed in $[Pt/CoFe]_4/NiO(t_{NiO})/[CoFe/Pt]_4$ multilayers. The effect of N (number of bilayer repeats) upon the magnetic property of [Pt/CoFe]N/IrMn is also studied.

• 전기화학회지
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• 제16권2호
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• pp.59-64
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• 2013

$Na_2CO_3$와 [M($SO_4$)(M = Ni, Co, Mn)]을 사용함으로써, Carbonate 공침 합성법에 의해 $[Ni_{0.6}Co_{0.2}Mn_{0.2}]CO_3$ 전구체를 합성하였다. 합성된 전구체는 공기분위기에서 $Li_2CO_3$와 혼합하여 각각, 750, 850 그리고 $950^{\circ}C$에서 소성되었고, 이로 인한 $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$ 양극활 물질의 소성온도가 미치는 영향을 조사하였다. $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$의 구조와 특성은 X-선 회절 분석(XRD), 시차주사현미경(SEM) 그리고 전기화학적 측정으로 분석되었는데, X-선 회절 결과 $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$는 소성온도가 증가함에 따라서 $I_{(003)}/I_{(104)}$는 증가하고 R-factor 는 감소하였으며, 시차주사현미경 결과에서는 1차 입자의 크기가 증가하는 경향을 보였다. 특히, $950^{\circ}C$에서 24시간 동안 소성된 $Li[Ni_{0.6}Co_{0.2}Mn_{0.2}]O_2$는 가역 용량이 $165.3mAhg^{-1}$[cut-off voltage 2.5~4.3 V, 0.1 C($17mAhg^{-1}$)] 그리고 50번째 충 방전 사이클 [cut-off voltage 2.5~4.3 V, 1 C($170mAhg^{-1}$)]까지 95.4%의 우수한 용량 보존율을 가지면서 가장 우수한 전기화학적 특성을 보여주었다.

• 한국세라믹학회지
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• 제35권10호
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• pp.1101-1106
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• 1998

Various $Zn_{2-x}SiO_4$:xMn based green phosphors were investigated in association with a co-dopant. The co-dopant incorporated into the phosphors are believed to alter the internal energy state of $Zn_{2-x}SiO_4$ : xMn So that the improvement in their intensity could be expected. Phosphor samples were prepared using the solid state reaction therein raw powders are mixed in the acetone and successively fired at $1300^{\circ}C$ for 4 hour. The fired powders are also heated up to $900^{\circ}C$ for 2 hour in the reduced atmoshpere and thereby giving The fired powders are also heated up to $900^{\circ}C$ for 2 hour in the reduced atmosphere and thereby giving rise to conspicuous enhancement of radiative efficiency. Basically the 0.08 mole ratio of the Mn con-centrations has the maximum value of the intensity so that a co-dopant are added to this Mn con-centration. When the Mg is co-doped with Mn luminescent intensity is proven to be promoted significantly.

• 전기화학회지
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• 제11권3호
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• pp.197-210
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• 2008

리튬이차전지용 양극재는 전지 성능발전과 더불어 다양하게 발전되어 왔다. 처음으로 채용된 $LiCoO_2$는 초기의 부족한 성능을 도핑이나 표면개질이라는 기술을 채용하여 지속적인 발전을 거듭하면서 최근 4.3V에 가까운 충전전압에서도 적용 가능하게 되었다. 한편으로 응용기기가 복잡해지면서 요구되는 특성도 한층 강화되었다. 높은 작동전압 뿐만 아니라 고용량이 요구되면서 새로운 재료에 대한 연구개발이 시작되었고, 그 중에서도 ${LiNi}_{1-x}{M_xO_2}$, $Li[Ni_{x}Mn_{y}Co_{z}]O_{2}$, $Li[{Ni}_{1/2}{Mn}_{1/2}]O_{2}$등 다양한 재료들이 개발되기에 이르렀다. 최근에는 고유가에 따라 전기자동차용 개발이활발해지면서 고안전성의 새로운 재료가 필요하게 되었고, 이러한 요구에 수렴하여 ${LiMn_2}{O_4}$, $LiFePO_4$와 같은 안전성이 매우 우수한 재료가 개발되었다. 향 후 양극재 부분은 이외에도 다양한 상들이 고용량과 동시에 안전성이 뛰어난 고용체를 이루고 있는 복합체 양극재를 비롯하여 다양한 재료들이 개발될 것으로 여겨진다.

• 한국재료학회지
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• 제28권7호
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• pp.371-375
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• 2018

The manganese-, nickel-, and aluminum-doped cobalt ferrite powders, $Mn_{0.2}Co_{0.8}Fe_2O_4$, $Ni_{0.2}Co_{0.8}Fe_2O_4$, and $Al_{0.2}CoFe_{1.8}O_4$, are fabricated by the sol-gel method, and the crystallographic and magnetic properties of the powders are studied in comparison with those of $CoFe_2O_4$. All the ferrite powders are nano-sized and have a single spinel structure with the lattice constant increasing in $Mn_{0.2}Co_{0.8}Fe_2O_4$ but decreasing in $Ni_{0.2}Co_{0.8}Fe_2O_4$ and $Al_{0.2}CoFe_{1.8}O_4$. All the $M{\ddot{o}}ssbauer$ spectra are fitted as a superposition of two Zeeman sextets due to the tetrahedral and octahedral sites of the $Fe^{3+}$ ions. The values of the magnetic hyperfine fields of $Ni_{0.2}Co_{0.8}Fe_2O_4$ are somewhat increased in the A and B sites, while those of $Mn_{0.2}Co_{0.8}Fe_2O_4$ and $Al_{0.2}CoFe_{1.8}O_4$ are decreased. The variation of $M{\ddot{o}}ssbauer$ parameters is explained using the cation distribution equation, superexchange interaction and particle size. The hysteresis curves of the ferrite powders reveal a typical soft ferrite pattern. The variation in the values of saturation magnetization and coercivity are explained in terms of the site distributions, particle sizes and the spin magnetic moments of the doped ions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.313-316
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• 2002

비철금속 습식 제련용 고효율 장수명의 양극을 개발하기 위해서 산소 과전압이 낮은 $MnO_{2}$를 촉매로 사용하여 반도체 산화물계의 산소선택성 전극을 제조하고 산화물 coating층의 미세구조와 전기화학적 특성을 분석하였다. PVDF : $MnO_{2}$의 함량비플 1 : 1 에서 1 : 40까지 정량적으로 변화시켰고， 용제의 점도에 지배적인 영향을 미치는 DMF의 함량을 각각의 고정된 PVDF : $MnO_{2}$의 함량비에서 변화시켜 용제를 제조하였으며 4% $HNO_{3}$ 용액에 세척된 Pb전극을 1.5 mm/sec 의 속도로 5회 dipping 하였다. PVDF : $MnO_{2}$ = 1 : 6인 경우 PVDF의 양이 증가하고 DMF의 양이 감소할수록 피막층이 두꺼워지고 PVDF : DMF = 4 : 96인 경우 pb 전극의 피막층이 얇기 때문에 박리현상이 일어났으며 이는 산화물 용제의 낮은 점도 때문인 것으로 판단된다. 또한 PVDF : DMF = 10 : 90의 경우는 5회 dipping 하여 약 $150{\mu}m$의 피막층을 형성하였다. PVDF : Mn02의 함량비가 1:1에서 1:6 까지는 DMF의 함량에 무관하게 전극 특성이 나타나지 않았지만 $MnO_{2}$의 양이 상대적으로 증가하면 cycle 이 증가하더라도 거의 일정한 전류 값을 갖고$MnO_2$와 PVDF의 비가 20:1 이상의 조성에서는 균일한 CV 특성을 나타냈다 이는 $MnO_{2}$가 효과적으로 촉매 작용을 한 것으로 판단되며 anodic polarization에 의한 산소 발생 과전압도 약 1.4V 정도로 감소되었다.

• 한국전기전자재료학회논문지
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• 제25권11호
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• pp.878-885
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• 2012

In this study we aims to examine the co-doping effects of 1/3 mol% $Mn_3O_4+Co_3O_4$ (1:1) on the reaction, microstructure, and electrical properties such as the bulk defects and grain boundary properties of $ZnO-Bi_2O_3-Sb_2O_3$ (ZBS; Sb/Bi=0.5, 1.0, and 2.0) varistors. The sintering and electrical properties of Mn,Co-doped ZBS, ZBS(MCo) varistors were controlled by Sb/Bi ratio. Pyrochlore ($Zn_2Bi_3Sb_3O_{14}$) was decomposed and promoted densification at lower temperature on heating in Sb/Bi=1.0 by Mn rather than Co. Pyrochlore on cooling was reproduced in all systems however, spinel (${\alpha}$- or ${\beta}$-polymorph) did not formed in Sb/Bi=0.5. More homogeneous microstructure was obtained in $Sb/Bi{\geq}1.0$ In ZBS(MCo), the varistor characteristics were improved drastically (non-linear coefficient, ${\alpha}$=30~49), and seemed to form $Zn_i^{..}$(0.17 eV) and $V_o^{\bullet}$(0.33 eV) as dominant defects. From impedance and modulus spectroscopy (IS & MS), the grain boundaries have divided into two types, i.e. the one is tentatively assign to $ZnO/Bi_2O_3(Mn,Co)/ZnO$ (0.47 eV) and the other ZnO/ZnO (0.80~0.89 eV) homojunctions.

• Journal of Electrochemical Science and Technology
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• 제5권1호
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• pp.32-36
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• 2014

The $0.3Li_2MnO_3{\cdot}0.7LiMn_{0.55}Ni_{0.30}Co_{0.15}O_2$ cathode material was prepared via a co-precipitation method. The vapor grown carbon fiber (VGCF) was used as a conductive material and its effects on electrochemical properties of the $0.3Li_2MnO_3{\cdot}0.7LiMn_{0.55}Ni_{0.30}Co_{0.15}O_2$ cathode material were investigated. From the XRD pattern, the typical complex layered structure was confirmed and a solid solution between $Li_2MnO_3$ and $LiMO_2$ (M = Ni, Co and Mn) was formed without any secondary phases. The VGCF was properly distributed between cathode materials and conductive sources by a FE-SEM. In voltage profiles, the electrode with VGCF showed higher discharge capacity than the pristine electrode. At a 5C rate, 146 mAh/g was obtained compared with 232 mAh/g at initial discharge in the electrode with VGCF. Furthermore, the impedance of the electrode with VGCF did not changed much around $9-10{\Omega}$ while the pristine electrode increased from 21.5${\Omega}$ to $46.3{\Omega}$ after the $30^{th}$ charge/discharge cycling.