• Title/Summary/Keyword: Secondary Doping

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A Study for the Thermal Heutron Effects on Optical Fiber (광섬유에 대한 열중성자 효과 연구)

  • 김웅기;손석원;이용범;이종민
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.12
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    • pp.1900-1905
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    • 1990
  • In this study, the thermal neutron effects on optical fiber are examined theoretically. Also, the induced loss by thermal neutron irradiation in optical fibers is measured at the optical wavelengths of 0.85 and 1.3\ulcorner, respectively, and the results are analyzed. Thermal neutrons cause nuclear reaction with fiber compositions. So secondary ionizing radiations of high energy are generated. Color centers formed by these secondary ionizing rasiations increase transmission loss of optical fiber by absorbing propagating light in fiber core. As a result of experiment, owing to Ge, P, and B doping effects, the induced loss in multimode fibers has been 5 tmes larger than that in single mode fibers at 1.3 \ulcorner wavelengh. In case of multimode fibers, the loss at 0.8 \ulcorner wavelength region more suceptible for radiations has been twice higher than at 1.3\ulcorner.

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Near IR Luminescence Properties of Er-doped Sol-Gel Films (Er이 도핑된 졸-겔 코팅막의 발광특성)

  • Lim, Mi-Ae;Seok, Sang-Il;Kim, Ju-Hyeun;Ahn, Bok-Yeop;Kwon, Jeong-Oh
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2003.11a
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    • pp.136-136
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    • 2003
  • In fiber optic networks, system size and cost can be significantly reduced by development of optical components through planar optical waveguides. One important step to realize the compact optical devices is to develop planar optical amplifier to compensate the losses in splitter or other components. Planar amplifier provides optical gain in devices less than tens of centimeters long, as opposed to fiber amplifiers with lengths of typically tens of meters. To achieve the same amount of gain between the planar and fiber optical amplifier, much higher Er doping levels responsible for the gain than in the fiber amplifier are required due to the reduced path length. These doping must be done without the loss of homogeniety to minimize Er ion-ion interactions which reduce gain by co-operative upconversion. Sol-gel process has become a feasible method to allow the incorporation of Er ion concentrations higher than conventional glass melting methods. In this work, Er-doped $SiO_2$-A1$_2$ $O_3$ films were prepared by two different method via sol -Eel process. Tetraethylorthosilicate(TEOS)/aluminum secondary butoxide [Al (OC$_4$ $H_{9}$)$_3$], methacryloxypropylcnethoxysaane(MPTS)/aluminum secondary butofde [Al(OC$_4$ $H_{9}$)$_3$] systems were used as starting materials for hosting Er ions. Er-doped $SiO_2$-A1$_2$ $O_3$ films obtahed after heat-treating, coatings on Si substrate were characterized by X-ray din action, FT-IR, and N-IR fluorescence spectroscopy. The luminescence properties for two different processing procedure will be compared and discussed from peak intensity and life time.

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Anode Properties of Boron Doped Polyacene Derived from Phenolic Resin (페놀수지로부터 유도된 Boron을 Doping한 polyacene계 부극의 특성)

  • Oh, Won-Chun;Park, Seung-Huyk;Kim, Bum-Soo
    • Analytical Science and Technology
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    • v.13 no.6
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    • pp.705-711
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    • 2000
  • We have studied the structural characterization, surface morphology and electrical properties for boron dopped polyacene anode material from phenolic resin for lithium secondary battery. The boron dopped anode material were characterized as boron contents of 5, 10, 15 and 20%, respectively. From the X-ray results, the all kinds of compounds were observed for the diffraction patterns for typical amorphous carbons. The SEM morphology showed formation of semi spherical granule for the boron dopped compounds. As the result of the electrical charge/discharge and impedance data, the 10 and 15% boron dopped materials showed good properties on the ions and electron transfer effect of battery.

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Enhanced Electrochemical Properties of NCA Cathode Materials for Lithium Ion Battery by Doping Effect (도핑효과에 따른 리튬이차전지용 NCA 양극활물질의 전기화학적 특성 향상)

  • Fan, Zhi Yu;Jin, n Mei;Jeong, Sang Mun
    • Korean Chemical Engineering Research
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    • v.55 no.6
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    • pp.861-867
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    • 2017
  • In order to improve the capacity and cycling stability of Ni-rich NCA cathode materials for lithium ion batteries, the boron and cobalt were doped in commercial $Li_{1.06}Ni_{0.91}Co_{0.08}Al_{0.01}O_2$ (NCA) powders. Commercial NCA particles are mixed composites such as secondary particles of about $5{\mu}m$ and $12{\mu}m$, and the particle size was decreased by doping boron and cobalt. The initial discharge capacities of the boron and cobalt doped NCA-B and NCA-Co were found to be 214 mAh/g and 200 mAh/g, respectively, which are higher values than that of the raw NCA cathode material. In particular, NCA-Co exhibits the best discharge capacity of 157 mAh/g after 20 cycles, which is probably due to the enhanced diffusion of lithium ion by crystal growth along with the c-axis direction.

Effect of MnO2 and CuO Addition on Microstructure and Piezoelectric Properties of 0.96(K0.5Na0.5)0.95Li0.05Nb0.93Sb0.07O3-0.04BaZrO3 Ceramics

  • Cho, Kyung-Hoon
    • Korean Journal of Materials Research
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    • v.29 no.3
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    • pp.150-154
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    • 2019
  • This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$, which has a rhombohedral-tetragonal phase boundary composition. $MnO_2$ and CuO-added $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$ ceramics sintered at a relatively low temperature of $1020^{\circ}C$ show a pure perovskite phase with no secondary phase. As the addition of $MnO_2$ and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of $MnO_2$.

Effect of substituent and dopant on properties of $LiMn_2O_4$ as cathode materials for lithium ion secondary batteries

  • Lee, Dae-Jin;Wai, Yin-Loo;Jee, Mi-Jung;Bae, Hyun;Choi, Byung-Hyun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.294-294
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    • 2007
  • Spinel cathode material $LiMn_2O_4$ is currently studied as a promising cathode material for lithium ion secondary batteries for future applications because of it is low cost, easy to be prepared and capable to be operated in high voltage range. However as a cathode material, $LiMn_2O_4$ performs a poor capacity retention which leads to short cycle life. In this study, stoichiometric $LiMn_2O_4$ was synthesized with granulation method with ion substitution to stabilize its structure and niobium doping to improve its conductivity. These well-mixed powders were calcined at $850^{\circ}C$ for 6 hours and its properties were investigated. Correlations of dopant and electrochemical properties were examined as well.

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The Structural Stability and Electrochemical Properties of Fe Doped Li[Ni0.575Co0.1Mn0.325]O2 (Fe을 도핑한 Li[Ni0.575Co0.1Mn0.325]O2의 구조적인 안정성 및 전기화학적 특성)

  • Yang, Su-Bin;Yoo, Gi-Won;Jang, Byeong-Chan;Son, Jong-Tae
    • Journal of the Korean Electrochemical Society
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    • v.17 no.3
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    • pp.149-155
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    • 2014
  • In this study, a positive-electrode material in a lithium secondary battery $Li[Ni_{0.575}Co_{0.1}Mn_{0.325}]O_2$ was synthesized as precursor by co-precipitation. Cathode material was synthesized by adding iron. The synthesized cathode material was analyzed by scanning electron microscope and x-ray diffraction. The analysis of x-ray diffraction showed that the a-axis and c-axis is increased by doping iron. And $I_{(003)}/I_{(104)}$ is increased and $I_{(006)}+I_{(102)}/I_{(101)}$ is decreased. Through this result, it was confirmed that the structural stability is improved. And impedance measurements show that the charge transfer resistance ($R_{ct}$) is lowered by doping iron. Consequently, electrochemical properties are improved by doping iron. In particular, the cycle characteristics are improved at a high temperature condition (328 K). Structural stabilities are contributing to the cycle properties.

Electrochemical Properties of Polyaniline Cathode for Lithium Secondary Batteries (리튬 2차 전지용 Polyaniline cathode의 전기화학적 특성)

  • Kim, H.C.;Kim, J.U.;Gu, H.B.;Moon, S.I.
    • Proceedings of the KIEE Conference
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    • 1996.07c
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    • pp.1685-1687
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    • 1996
  • Recently, conducting polymer has been much attracted as novel materials because of its electronic behavior and functional application by doping process. In this paper, we electrochemically synthesized polyaniline films under potential sweep conditions, which exhibit high electric conductivity about 200 S/cm. Specific energy of 600 Wh/kg and Ah efficiency 98% were achieved during the charge/discharge cycling using liquid electrolyte system. On the other hand, consequences of the cycling were 260 Wh/kg and 95% Ah efficiency using polyethylene oxide(PEO) based solid-state electrolyte system.

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The Influence of Re2O3(RDy, Er) on the Electromagnetic Properties of Mn-Zn Ferrite (Re2O3(RDy, Er)가 Mn-Zn ferrite의 전자기적 특성에 미치는 영향)

  • 백승철;최우성
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.15 no.2
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    • pp.178-183
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    • 2002
  • The effects of Dy$_2$O$_3$and Er$_2$O$_3$addition on the electromagnetic properties of Mn-Zn ferrite were investigated in the doping concentration range from 0.05 wt% to 0.25 wt%. All samples were prepared by standard fabrication of ferrite ceramics. The XRD patterns of sample were observed spinel and secondary phase. The densities of sample were showed nearly constant values. As the increased additive, electrical resistivity, initial permeability and real component of the series complex permeability increased with setting limits each other. Excess doped with Dy$_2$O$_3$ and Er$_2$O$_3$, those values decreased. The maximum electrical resistivity was observed with 0.15 we% and initial permeability was observed with 0.05 wt%. Magnetic loss decreased with additive and then increased in proportion to increased.

High-Quality Epitaxial Low Temperature Growth of In Situ Phosphorus-Doped Si Films by Promotion Dispersion of Native Oxides (자연 산화물 분산 촉진에 의한 실 시간 인 도핑 실리콘의 고품질 에피택셜 저온 성장)

  • 김홍승;심규환;이승윤;이정용;강진영
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.2
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    • pp.125-130
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    • 2000
  • Two step growth of reduced pressure chemical vapor eposition has been successfully developed to achieve in-situ phosphorus-doped silicon epilayers, and the characteristic evolution on their microstructures has been investigated using scanning electron microscopy, transmission electron microscopy, and secondary ion mass spectroscopy. The two step growth, which employs heavily in-situ P doped silicon buffer layer grown at low temperature, proposes crucial advantages in manipulating crystal structures of in-situ phosphorus doped silicon. In particular, our experimental results showed that with annealing of the heavily P doped silicon buffer layers, high-quality epitaxial silicon layers grew on it. the heavily doped phosphorus in buffer layers introduces into native oxide and plays an important role in promoting the dispersion of native oxides. Furthermore, the phosphorus doping concentration remains uniform depth distribution in high quality single crystalline Si films obtained by the two step growth.

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