• Title/Summary/Keyword: Transition metal ion

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Electrochemical Properties of $LiM_xFe_{1_x}PO_4$ Cathode Materials By Solid-state Reaction

  • Wang, Wan-Lin;Park, Kyung-Hee;Gil, Hal-Bon;Park, Bok-Kee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.212-212
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    • 2010
  • Recently, lithium transition metal phosphates with an ordered olivine-type structure, $LiMPO_4$ (M=Fe, Mn, Ni, and Co), have attracted extensive attention due to a high theoretical specific capacity (170 mAh/g). The $LiMPO_4$ is the most attractive because of its high stability, low cost, high compatibility with environment. However, it is difficult to attain its full capacity because its electronic conductivity is very low, and diffusion of Li-ion in the olivine structure is slow and the supervalue cation doping was used. In this research, we are used the supervalue cation doping methode such as Cu, Ti, and Mg were partially replace the Fe. The cycling performance resulted of the used $LiM_xFe_{1_x}PO_4$ cathode materials for lithium batteries exhibit excellent high capacity than $LiFePO_4$/Li cells.

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La(III) Selective Membrane Sensor Based on a New N-N Schiff's Base

  • Ganjali, Mohammad Reza;Matloobi, Parisa;Ghorbani, Maryam;Norouzi, Parviz;Salavati-Niasari, Masoud
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.38-42
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    • 2005
  • Bis(2-methylbenzaldehyde)butane-2,3-dihydrazone(TDSB) was used as new N-N Schiff's base which plays the role of an excellent ion carrier in the construction of a La(III) membrane sensor. The best performance was obtained with a membrane containing, 30% poly(vinyl chloride), 60% benzyl acetate, 6% TDSB and 4% sodium tetraphenyl borate. This sensor reveals a very good selectivity towards La(III) ions over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The proposed electrode exhibits a Nernstian behavior (with slope of 19.8 mV per decade) over a wide concentration range (1.0 ${\times}$ 10$^{-5}$-1.0 ${\times}$ 10$^{-1}$ M). The detection limit of the sensor is 7.0 ${\times}$ 10$^{-6}$ M. It has a very short response time, in the whole concentration range ($\sim$5 s), and can be used for at least twelve weeks in the pH range of 3.0-9.4. The proposed sensor was successfully applied as an indicator electrode for the potentiometric titration of a La(III) solution, with EDTA. It was also successfully applied in the determination of fluoride ions in three mouth wash preparations.

Novel Copper(Ⅱ)-Selective Senor Based on a New Hexadentates Schiff's Base

  • Ganjali, Mohammad Reza;Emami, Mehdi;Salavati Niasari, Masoud
    • Bulletin of the Korean Chemical Society
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    • v.23 no.10
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    • pp.1394-1398
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    • 2002
  • A novel copper(II) membrane electrode based on diphenylisocyanate bis(acetylacetone) ethylenediimine (DIBAE), as a new hexadentates Schiff's base was prepared. The electrode exhibited a Nernstian response for Cu$^{2+}$ ions over a wide concentration range (1.0 ${\times}$ 10$^{-1}$ to 1.0 ${\times}$ l0$^{-6}$ M) with a limit of detection of 6.0 ${\times}$ 10$^{-7}$ M (39 ppb). The sensor shows a fast response time (15s) and the membrane can be used for more than 4 months without observing any major deviation. The electrode revealed very good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The proposed sensor could be used in a pH range of 3.0-7.5. It was applied to the direct potentiometric determination of copper in black tea, and in wastewater of copper electroplating samples. The electrode was also used in potentiometric titration of the copper(II) ion with EDTA.

Synthesis of a New Hexadendates Schiff's Base and Its Application in the Fabrication of a Highly Selective Mercury(II) Sensor

  • Ganjali, M.R.;Norouzi, P.;Alizadeh, T.;Salavati-Niasari, M.
    • Bulletin of the Korean Chemical Society
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    • v.28 no.1
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    • pp.68-72
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    • 2007
  • A new PVC membrane potentiometric sensor that is highly selective to Hg2+ ions was prepared, using bis(2-hydroxybenzophenone) butane-2,3-dihydrazone (HBBD) as an excellent hexadendates neutral carrier. The sensor works satisfactorily in the concentration range of 1.0 × 10-6 to 1.0 × 10-1 mol L-1 (detection limit 4 × 10-7 mol L-1) with a Nernstian slope of 29.7 mV per decade. This electrode showed a fast response time (~8 s) and was used for at least 12 weeks without any divergence. The sensor exhibits good Hg2+ selectivity for a broad range of common alkali, alkaline earth, transition and heavy metal ions (lithium, sodium, potassium, magnesium, calcium, copper, nickel, cobalt, zinc, cadmium, lead and lanthanum). The electrode response is pH independent in the range of 1.5-4.0. Furthermore, the developed sensor was successfully used as an indicator electrode in the potentiometric titration of mercury ions with potassium iodide and the direct determination of mercury in some binary and ternary mixtures.

Changes in the Shape and Properties of the Precursor of the Rich-Ni Cathode Materials by Ammonia Concentration (암모니아 농도에 따른 Rich-Ni 양극 소재의 전구체 형태와 특성 변화)

  • Park, Seonhye;Hong, Soonhyun;Jeon, Hyeonggwon;Kim, Chunjoong
    • Korean Journal of Materials Research
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    • v.30 no.11
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    • pp.636-640
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    • 2020
  • Due to the serious air pollution problem, interest in eco-friendly vehicles is increasing. Solving the problem of pollution will necessitate the securing of high energy storage technology for batteries, the driving force of eco-friendly vehicles. The reason for the continuing interest in the transition metal oxide LiMO2 as a cathode material with a layered structure is that lithium ions reveal high mobility in two-dimensional space. Therefore, it is important to investigate the effective intercalation and deintercalation pathways of Li+, which affect battery capacity, to understand the internal structure of the cathode particle and its effect on the electrochemical performance. In this study, for the cathode material, high nickel Ni0.8Co0.1Mn0.1(OH)2 precursor is synthesized by controlling the ammonia concentration. Thereafter, the shape of the primary particles of the precursor is investigated through SEM analysis; X-ray diffraction analysis is also performed. The electrochemical properties of LiNi0.8Co0.1Mn0.1O2 are evaluated after heat treatment.

Effect of Na Substitution for the Ca Site in the Bi$_2$Sr$_2$Ca$_{1-x}$Na$_x$Cu$_2$O$_{8+y}$ Superconductors (Bi$_2$Sr$_2$Ca$_{1-x}$Na$_x$Cu$_2$O$_{8+y}$ 산화물 고온초전도체의 Ca 위치에 Na 치환 효과)

  • 이민수;송승용;이종용;송기영;최봉수
    • Journal of the Korean Ceramic Society
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    • v.35 no.10
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    • pp.1007-1013
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    • 1998
  • The samples of Bi2Sr2Ca1-xNaxCu2O8+y with various carrier concentration were synthesized by substituting Na for Ca ion. The superconducting properties hall coefficients and X-ray powder diffraction were measur-ed the sampled. Single phase samples were obtained for 0$\leq$x<0.3 of Bi2Sr2Ca1-xNaxCu2O8+y In the single phase the critical temperature. {{{{ { T}_{c } }} and carrier concentration increase with the increase of Na concentration pass through a maximum and then decreases. In the range of x$\geq$0.7 to the Na doped samples however we observed the metal-semiconductor transition. The c-axis seemed to decrease and a and b-axes increase with increasing Na concentration in the single phase. Decreasing of c-axis while increasing x is due to the smaller size of {{{{ {Na}^{+1 } }} ions to the {{{{ { Ca}^{+2 } }} ions. In the range of x>0.3 however the trend becomes ambiguous due to the inclusion of the 10K phase and impurity phase.

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Study on Current Switching in Electronic Devices Based on Vanadium Dioxide Thin Films Using CO2 Laser (이산화탄소 레이저를 이용한 바나듐 이산화물 박막 전자 소자에서의 전류 스위칭에 관한 연구)

  • Kim, Jihoon;Lee, Yong Wook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.30 no.1
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    • pp.1-7
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    • 2016
  • With a collimated $CO_2$ laser beam, the bidirectional current switching was realized in a two-terminal electronic device based on a highly resistive vanadium dioxide($VO_2$) thin film. A $VO_2$ thin film was grown on a $Al_2O_3$ substrate by a pulsed laser deposition method. For the fabrication of a two-terminal electronic device, the $VO_2$ thin film was etched by an ion beam-assisted milling method, and the $VO_2$ device, of which $VO_2$ patch width and electrode separation were 50 and $100{\mu}m$, respectively, was fabricated through a photolithographic method. A bias voltage range for stable bidirectional current switching was found by using the current-voltage property of the device measured in a current-controlled mode. The transient responses of bidirectionally switched currents were analyzed when the laser was modulated at a variety of pulse widths and repetition rates. A switching contrast was measured as ~3333, and rising and falling times were measured as ~39 and ~21ms, respectively.

Bidirectional Current Triggering in Two-Terminal Planar Device Based on Highly Resistive Vanadium Dioxide Thin Film Using 966nm Near Infrared Laser (966nm 근적외선 레이저를 이용한 고저항성 바나듐 이산화물 박막 기반 2단자 평면형 소자에서의 양방향 전류 트리거링)

  • Kim, Jihoon;Lee, Yong Wook
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.11
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    • pp.28-34
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    • 2015
  • By incorporating a 966nm near infrared laser, we demonstrated bidirectional current triggering of between 0 and 10mA in a two-terminal planar device based on a highly resistive vanadium dioxide ($VO_2$) thin film grown by a pulsed laser deposition method. A two-terminal planar device, which had an electrode separation of $100{\mu}m$ and a $50{\mu}m-wide$ $VO_2$ conducting layer, was fabricated through ion beam-assisted milling and photolithographic techniques. A bias voltage range for stable bidirectional current triggering was determined by investigating the current-voltage curves of the $VO_2-based$ device in a current-controlled mode. Bidirectional current triggering of up to 10mA was realized by directly illuminating the $VO_2$ film with a focused infrared laser beam, and the transient responses of triggered currents were analyzed when the laser was modulated at various pulse widths and repetition rates. A switching contrast between off- and on-state currents was evaluated as ~3571, and the rising and falling times were measured as ~40 and ~20ms, respectively.

$Cu^{2+}$-Anthraquinone Complexes : Formation, Interaction with DNA, and Biological Activity

  • Ko, Thong-Sung;Maeng, Hack-Young;Park, Mi-Kyeong;Park, Il-Hyun;Park, In-Sang;Kim, Byoung-Sun
    • Bulletin of the Korean Chemical Society
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    • v.15 no.5
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    • pp.364-368
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    • 1994
  • Growth inhibition potency of the anthraquinones, anthraquinone-1,5-disulfonic acid and carminic acid, for Sarcoma 180 and L1210 leukemia cells in vivo and in vitro, was induced by the divalent transition metal ion, $Cu^{2+}$. On the other hand spectroscopic titration data show that the anthraquinone drugs form $Cu2^+$ chelate complexes (carminic acid : $Cu^{2+}$ = 1 : 6; anthraquinone-1,5-disulfonic acid : $Cu^{2+}$ = 1 : 3). Furthermore the $Cu^{2+}$-drug complexes associate with DNA to form the $Cu^{2+}$-anthraquinone-DNA ternary complexes. The formation of the complexes was further supported by the $H_2O_2-dependent$ DNA degradation, which can be inhibited by ethidium bromide, caused by the $Cu^{2+}$-drug complexes. It is likely that the $Cu^{2+}$-mediated cytotoxicity of the anthraquinone drugs is related with the $Cu^{2+}-mediated$ binding of the anthraquinone drugs to DNA and DNA degradation.

The $Pb^{2+}$ Ion Affinitive Membrane Electrode Based on New Calix[4]arene Ionophore (새로운 캘릭스[4]아렌 유도체를 이용한 $Pb^{2+}$ 이온 친화성 막전극)

  • Kim, Eun Jin;Kim, Min Kyu;Nam Gung, Mi Ok;Paek, Kyung Soo;Yun, Young Ja
    • Journal of the Korean Chemical Society
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    • v.42 no.5
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    • pp.531-538
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    • 1998
  • The ion selective membrane electrode made of calix[4]arene-based host 1 as ionophore, poly (vinyl chloride) (PVC) as matrix and dioctylsebacate (DOS) as a plasticizer was studied. The potential responses of this membrane electrode to alkali, alkaline earth and transition metal cations were investigated. Especially this membrane electrode was turned out to be affinitive for $Pb^{2+}$ in the deionized water. It was observed that the response was linear in the concentration range from $1.0 \times 10^{-1} M to 1.0 \times 10^{-6} M of Pb^{2+}$ and its slope (26.5 mV/decade) was near to the sub-Nernstian response in deionized water. Also, the potential was maintained constantly in the range of pH $4.00 \sim 12.00$, which supports the potential usage as $Pb^{2+}$ affinitive electrode in the deionized water.

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