• Title/Summary/Keyword: metal ion mole fraction

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Effects of Metal Ion Mole Ratio and Calcination Temperatures on Magnetic Properties and Microstructure of Ba2Co2Fe12O22 Powders Synthesized by Solid State Reaction (고상반응법으로 제조된 Ba2Co2Fe12O22분말의 자기적 성질과 미세구조에 미치는 금속이온몰비와 열처리 온도의 영향)

  • Cho, Kwang-Muk;Nam, In-Tak
    • Journal of the Korean Magnetics Society
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    • v.19 no.6
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    • pp.216-221
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    • 2009
  • Y-type barium ferrite $Ba_2Co_2Fe_{12}O_{22}$ was synthesized by a solid state reaction method. Effects of metal ion mole ratio and calcination temperatures on magnetic properties and microstructures of the synthesized powders were investigated. Phase analysis and microstructure observation were performed with a XRD (X-ray diffractometer) and a FESEM (field effect scanning electron microscope), respectively. Magnetic properties of the powders were measured with a VSM (vibrating sample magnetometer). Single phase Y-type was synthesized when metal ion mole fraction $Fe^{3+}:\;Ba^{2+}:\;Co^{2+}$ was 6 : 1 : 1 and calcination temperature was $1050\;{^{\circ}C}$. High saturation magnetization value of 39.1 emu/g was obtained when metal ion mole fraction $Fe^{3+}:\;Ba^{2+}:\;Co^{2+}$ was 8 : 1 : 1 and calcination temperature was $1200\;{^{\circ}C}$.

Evaluation of Distribution Coefficient of a Metal Ion in the Presence of n Chelating Agent

  • Baik, Min-Hoon;Lee, Kun-Jai
    • Journal of Energy Engineering
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    • v.1 no.1
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    • pp.97-101
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    • 1992
  • A mathematical model has been developed for an analytical calculation of distribution coefficient (K$_1$) in the presence of a chelating agent, The newley formulated K$\_$D/ is given as a function of the mole fraction of a free metal ion in the solution, ${\beta}$, and will serve as an alternative for the tedious individual measurements of K$\_$D/. This formulation will be used to analyze the effects of the presence of chelating agents on the adsorption capacity of geologic media such as clay minerals and soils. The present method may be a significant progess for the evaluation of the transport phenomena and separation processes of metal ions (or radionuclides) in the presence of chelating agents.

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Electrochemical Performance of Li4Ti5O12 Particles Manufactured Using High Pressure Synthesis Process for Lithium Ion Battery (초고압 합성법으로 제조한 리튬이온전지 음극활물질 Li4Ti5O12의 전기화학적 특성)

  • Ji, Sung Hwa;Jo, Wan Taek;Kim, Hyun Hyo;Kim, Hyojin
    • Korean Journal of Materials Research
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    • v.28 no.6
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    • pp.337-342
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    • 2018
  • Using a high pressure homonizer, we report on the electrochemical performance of $Li_4Ti_5O_{12}(LTO)$ particles manufactured as anode active material for lithium ion battery. High-pressure synthesis processing is performed under conditions in which the mole fraction of Li/Ti is 0.9, the synthesis pressure is 2,000 bar and the numbers of passings-through are 5, 7 and 10. The observed X-ray diffraction patterns show that pure LTO is manufactured when the number of passings-through is 10. It is found from scanning electron microscopy analysis that the average size of synthesized particles decreases as the number of passings-through increases. $LiCoO_2-based$ active cathode materials are used to fabricate several coin half/full cells and their battery characteristics such as lifetime, rate capability and charge transfer resistance are then estimated, revealing quite good electrochemical performance of the LTO particles as an effective anode active material for lithium secondary batteries.

Excimer Studies on Copolymer of Styrene-Acrylic Acid (스티렌-아크릴산 공중합체의 들뜬이합체 연구)

  • Lee, Yeon Hui;Gang, Seong Cheol;Kim, Gang Jin
    • Journal of the Korean Chemical Society
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    • v.34 no.1
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    • pp.91-97
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    • 1990
  • Copolymers (PSAA) of styrene-acrylic acid were prepared through a free radical mechanism using azobisisobutyronitrile as an initiator. The fluorescence emission spectra of PSAA and the styrene-acrylic acid copolymers complexed with $Eu^{3+}$ (PSAA-Eu) were studied. The excimer fluorescence, centered at 330 nm, increases when the styrene mole fraction increases. Since the excimer fluorescence intensities of PSAA-EU, PSAA-Tb and PSAA-Eu-Tb were almost same, it appears that the kind of metal ion does not affect the excimer fluorescence. An interpretation of the results which takes into account the statistical composition of the copolymers, indicates that energy migration can occur from isolated to non-isolated styrene units.

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