• 제목/요약/키워드: LiAlO2

검색결과 382건 처리시간 0.029초

수열법에 의한 $(Li,Al)MnO_{2}(OH)_{2}$:Co 화합물의 합성 (Hydrothermal synthesis of $(Li,Al)MnO_2(OH)_2$:Co compound)

  • 최종건;황완인;김판채
    • 한국결정성장학회지
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    • 제11권4호
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    • pp.154-159
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    • 2001
  • (Li,Al)$MnO_2(OH)_2$:Co 화합물의 합성르 수열법에 의해 행하였다. 출발원료는 $MnO_2$, LiOH.$H_2$O, $Co_3O_4$, $Al(OH)_3$이 사용되었으며, 단일상의 (Li,Al)$MnO_2(OH)_2$:Co 화합물을 얻을 수 있는 최적의 합성조건은 다음과 같았다. 반응온도 : $200^{\circ}C$ 반응시간 ; 3일간, 반응장치 ; 시이소형, 수열용매 ; 3M-KOH, (Li,Al)$MnO_2(OH)_2$:Co 의 원자비 = 1:2.1:2.5~2:0.5~1. 수열합성된 단사의 (Li,Al)$MnO_2(OH)_2$:Co 화합물은 결정성이 우수하였으며, 청색안료로써 천연 오수에 필적하는 발색효과를 나타내었다. 합성된 (Li,Al)$MnO_2(OH)_2$:Co 화합물의 형태는 육각 판싱이였으며, 입자의 크기는 0.5~1 $\mu\textrm{m}$의 미립자이였다.

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고상법으로 합성한 LiMn2O4:Al의 전기화학적 특성 (Electrochemical Performances of LiMn2O4:Al Synthesized by Solid State Method)

  • 박혜정;박선민;노광철;한정화
    • 한국세라믹학회지
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    • 제48권6호
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    • pp.531-536
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    • 2011
  • Al doped $LiMn_2O_4$ ($LiMn_2O_4:Al$) synthesized by several Al doping process and Solid State method. The Al contents in $Mn_{1-x}Al_xO_2$ for $LiMn_2O_4:Al$ were analyzed 1.7 wt% by EDS. The $LiMn_2O_4:Al$ confirmed cubic spinel structure and approximately 5 ${\mu}m$ particles regardless of three kinds of doping process by solid state method. In the result of electrochemical performances, initial discharge capacity had 115 mAh/g in case of $LiMn_2O_4$ and 111 mAh/g of $LiMn_2O_4:Al$ after 100th cycle at room temperature. But the capacity retention results showed that $LiMn_2O_4$ and $LiMn_2O_4:Al$ were 44% and 69% respectively in the 100th cycle at 60$^{\circ}C$. Therefore we are confirmed that $LiMn_2O_4:Al$ increased the capacity retention about 25% than $LiMn_2O_4$, thus the effect of Al dopping on $LiMn_2O_4$ capacity retention.

의사이성분계, Li2Cr2O4-MgCr2O4와 Li2Cr2O4-MgAl2O4에서의 LiCrO2 고용체 형성과 결합구조 (Solid Solution and Defect Structure of LiCrO2 in the Pseudo-binary Systems : Li2Cr2O4-MgAl2O4)

  • 정영서;오근호;김호기
    • 한국세라믹학회지
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    • 제25권1호
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    • pp.35-41
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    • 1988
  • In the system of Li2O-MgO-Al2O3-Cr2O3, the crystalline solid solution of LiCrO2 along the pseudo-binary join between rocksalt structure(LiCrO2) and spinel structure(MgCr2O4 or MgAl2O4) have been investigated by x-ray diffraction techniques. In this study, order-disorder phase transition of LiCrO2 was observed and the unit cell of the disordered LiCrO2 structure has been established. It has been found that LiCrO2 makes a solid solution over a wide range with MgAl2O4, while not with MgCr2O4. This difference was explained as being due to the ability of oxygen lattice distortion which depended on the relative sizes and chemical bonding characteristics of the substituted ions.

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$Li_2O-Al_2O_3-Ta_2O_5$ 삼성분계에 있어 $LiTaO_3$ 고용체의 구조 및 특성에 관한 연구 (Structure and Properties of $LiTaO_3$ Type Solid Solutions in $Li_2O-Al_2O_3-Ta_2O_5$ Ternary System)

  • 김정돈;흥국선;주기태
    • 한국세라믹학회지
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    • 제33권4호
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    • pp.405-410
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    • 1996
  • The partial substitution of LiTaO3 with Al2O3 caused the variation of dielectric properties and a lower melting temperature yielding an easier growth of single crystal. The lattice constants and Raman band broadening were measured for the LiTaO3 solid solution in which the cations of Li+ and Ta5+ were partially substituted by Al3+ cation. The LiTaO3 type limit phases were obtained. ; Li1.15Al0.45Ta0.7O3 for cationic excess Li1.15Al0.45Ta0.7O3 for stoichiometry Li0.85Al0.05TaO3 for cationic deficit. The second phase was formed beyond the solubility limit. The limit phase (Li0.85Al0.05TaO3) in the region of cationic deficit showed the lowest Cuire temperature of 61$0^{\circ}C$ and melting point of 152$0^{\circ}C$ compared to the solid solutions in other regions (TMp=1$650^{\circ}C$, Tc=69$0^{\circ}C$ for LiTaO3)

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Raman 분광법을 이용한 $Li_{1-X}Al_{2X}Ta_{1-X}O_3$ 고용한계 분석 (Raman Spectroscopy of the Solid Solution Limit in $Li_{1-X}Al_{2X}Ta_{1-X}O_3$ System)

  • 김정돈;홍국선;주기태
    • 분석과학
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    • 제5권1호
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    • pp.115-120
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    • 1992
  • 강유전체인 $LiTaO_3$ 소재는 SAW filters나 IR sensors의 기본재료로 사용되고 있다. Dopant로서 $Al_2O_3$$LiTaO_3$에 일부 치환함으로써 유전 특성을 변화시키고 특히 용융점을 낮춤으로써 단결정 제조를 용이하게 한다. X-선 회절분석에 의한 격자상수 변화와 Raman spectroscopy의 band broadening을 측정한 결과 $LiTaO_3$에 대한 $Al_2O_3$의 고용한계가 $Li_{1-X}Al_{2X}Ta{1-X}O_3$에서 X=0.25mol이었으며, 고용한계 이상에서는 2차상인 $Al_2O_3$상이 XRD로 관찰되었다. Grain size에 의한 Raman band의 broadening을 고려하기 위하여 단결정과 소결체 $LiTaO_3$를 측정 비교하였다.

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$LiAl_5O_8-LiFe_5O_8$ 합성과 결정구조 해석 (Crystal structure refinement and synthesis of $LiAl_5O_8-LiFe_5O_8$)

  • 조남웅;김찬욱;장세기;유광수
    • 한국결정성장학회지
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    • 제7권2호
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    • pp.244-252
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    • 1997
  • $LiCO_3, Al_2O_3, Fe_2O_3$ 혼합물을 1620K에서 반응시켜 리튬전지의 음극재료로 응용이 가능한 스핀넬형 $LiAl_{2.5}/Fe_{2.5}O_8$를 합성하였다. XRD의 Rietveld 해석을 통하여 결정구조 해석을 하였다. 고용체의 공간군은 $P4_3$32(a=8.1293$\AA$)이고, 결정구조해석의 최종 Residual index는 약 5%정도이었다. 역 스핀넬구조에서 양이온 $Al^{3+}, Fe^{3+}$은 4-배위와 6-배위로 위치하고, $Li^+$은 4b, 12d의 6-배위자리에 존재하였다.

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졸-겔 법에 의한 $\gamma-LiAlO_2$ 화이버의 제조 및 특성 (Preparation and Characteristics of $\gamma-LiAlO_2$ Fibers by the Sol-Gel Method)

  • 현상훈;홍성안;신현철
    • 한국세라믹학회지
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    • 제32권2호
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    • pp.197-208
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    • 1995
  • ${\gamma}$-LiAlO2 fibers for fiber reinforced molten carbonate fuel cell (MCFC) matrix have been produced from LiAlO2 complex polymeric sols using the sol-gel process. The stable and spinnable LiAlO2 sols could be synthesized by mixing LiNO3 alcohol solutions in aluminum complex polymeric sols prepared through the condensationpolymerization reaction of 1 more of aluminum tri-sec-butoxide with 0.55 mole of mixed chelates (mole ratio of acetylaceton/triethanolamine=0.25/0.3). It was found that the viscosity range for fiber-spinning should be higher than 30 poise. The defect-free flexible ${\gamma}$-LiAlO2 fibers with the average tensile strength of 350 MPa could be obtained when the spinned fibers were heat-treated to 120$0^{\circ}C$ on the specified heating schedule after dried at room temperature.

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Surface Treatment of LiFePo4 Cathode Material for Lithium Secondary Battery

  • Son, Jong-Tae
    • 전기화학회지
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    • 제13권4호
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    • pp.246-250
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    • 2010
  • In this study, nano-crystallized $Al_2O_3$ was coated on the surface of $LiFePO_4$ powders via a novel dry coating method. The influence of coated $LiFePO_4$ upon electrochemical behavior was discussed. Surface morphology characterization was achieved by transmission electron microscopy (TEM), clearly showing nano-crystallized $Al_2O_3$ on $LiFePO_4$ surfaces. Furthermore, it revealed that the $Al_2O_3$-coated $LiFePO_4$ cathode exhibited a distinct surface morphology. It was also found that the $Al_2O_3$ coating reduces capacity fading especially at high charge/discharge rates. Results from the cyclic voltammogram measurements (2.5-4.2 V) showed a significant decrease in both interfacial resistance and cathode polarization. This behavior implies that $Al_2O_3$ can prevent structural change of $LiFePO_4$ or reaction with the electrolyte on cycling. In addition, the $Al_2O_3$ coated $LiFePO_4$ compound showed highly improved area-specific impedance (ASI), an important measure of battery performance. From the correlation between these characteristics of bare and coated $LiFePO_4$, the role of $Al_2O_3$ coating played on the electrochemical performance of $LiFePO_4$ was probed.

핵융합로 증식재용 $\gamma$-$LiAlO_2$분말 합성

  • 박지연;문영태;김원주;오석진;김영석;국일현
    • 한국원자력학회:학술대회논문집
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    • 한국원자력학회 1995년도 추계학술발표회논문집(2)
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    • pp.747-752
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    • 1995
  • 핵융합로 증식재용 ${\gamma}$-LiAlO$_2$ 분말을 자발착화 연소반응법을 적용하여 합성하였다. LiAlO$_2$분말을 합성하는데 이 방법을 적용하면 다른 분말 합성법과 달리 짧은 시간 내에 미세한 ${\gamma}$상을 쉽게 형성할 수 있었다. 최적의 ${\gamma}$-LiAlO$_2$ 분말을 합성하려면 구연산과 우레아의 혼합연료가 가장 적절하다고 판단되며, 이 연료로 합성된 ${\gamma}$-LiAlO$_2$ 분말을 24시간 볼분쇄하면 비표면적 값이 15.8 m$^2$/g인 미세한 분말을 얻을 수 있었다.

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졸-겔법에 의한 알루미나 화이버의 ${\gamma}-LiAlO_2$ 코팅 (${\gamma}-LiAlO_2$ Coating on Alumina Fibers by the Sol-Gel Method)

  • 현상훈;홍성안;김완식;신현철
    • 한국세라믹학회지
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    • 제31권11호
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    • pp.1271-1282
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    • 1994
  • The surface of commercial alumina fibers used for reinforcing the MCFC matrix has been coated with ${\gamma}$-LiAlO2 being the same material as the matrix, by the sol-gel method in order to enhance the corrosion resistivity of alumina fibers. Stable LiAlO2 complex polymeric sols for coating was synthesized by mixing aluminum alkoxide polymeric sols with LiNO3 solution. It was found that the LiAlO2 polymeric sol prepared by adding the mixed chelate of acethylacetone and triethanolamine (the mole ratio of AA/TEA = 0.125/0.75) to the 1 mole of the aluminum alkoxide had the excellent stability and coating behavior. The crystalline structure of the dried gel from the ${\gamma}$-LiAlO2 sol was completely transformed into the ${\gamma}$-LiAlO2 at $600^{\circ}C$. The optimum viscosity of the sol for coating the alumina long fibers was 30~40 cP, while it was 12~20 cP in case of the short fiber coating. The ${\gamma}$-LiAlO2 coated alumina fibers without defects fully densified when heat-treated at 120$0^{\circ}C$.

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