• Title, Summary, Keyword: NiO

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A Study on the Magnetic Properties and Microstructures of Ni-Fe/NiO Bilayers with Various Ar Presure in NiO Deposition (NiO 증착시의 Ar 압력 변화에 따른 Ni-Fe/NiO 이층막의 자기적특성과 미세구조에 대한 연구)

  • 노재철;이두현;김용성;서수정;박경수
    • Journal of the Korean Magnetics Society
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    • v.8 no.6
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    • pp.369-373
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    • 1998
  • The exchange anisotropy between NiO antiferromagnetic layer and NiFe ferromagnetic layer has been investigated in NiFe(10 nm)/NiO(60 nm) formed by magnetron sputtering. The NiO films were sputtered from nickel oxide using R. F. poser and NiFe, Ta were deposited using D. C. power under Ar atmosphere. Above all. we studied the exchange anisotropy of Ni-Fe/NiO bilayer, and focused especially on the effect of NiO depostion condition. Our experimental data showed that the dominant factor for determining the exchange anisotropy properties was the Ar pressure during NiO deposition. The better exchange anisotropy properties were found when the NiO film was deposited at low Ar pressure probably due to the flatten interface and the epitaxial tendency of NiO grains and NiFe grains. However, as Ar pressure increased, interfacial diffusion at NiFe/NiO interface and oxygen content of NiO film increase, and consequently reduced the exchange anisotropy. We concluded that the flatten interface and relatively low oxygen content of NiO layer are dominant factors for the enhancement of the exchange anisotropy in NiFe/NiO bilayer.

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The Effects of Deposition Rates on Exchange Coupling and Magnetoresistance in NiO Spin-Valve Films

  • D. G. Hwang;Park, C. M.;Lee, S. S.;Lee, K. A.
    • Journal of Magnetics
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    • v.2 no.4
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    • pp.143-146
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    • 1997
  • The effects of deposition rate on exchange coupling field Hex and coercive field Hc in NiO spin-valves are discussed. The Hex and Hc increased with deposition rate of NiO film. The rms roughnesses of the NiO deposited at 6 ${\AA}$/min (NiO-Low) and 30${\AA}$/min (NiO-High) were almost similar, however, the short-range roughness increased with the deposition rate. The Hex, Hc and surface morphologies for the modulated NiO spin-valve films such as NiO-Low\NiO-High\NiO-Low and NiO-High\NiO-Low were investigated.

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Effect of NiO spin switching on the Fe film magnetic anisotropy in epitaxially grown Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems

  • Kim, Won-Dong;Park, Ju-Sang;Hwang, Chan-Yong;Wu, J.;Qiu, Z.Q.
    • Proceedings of the Korean Vacuum Society Conference
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    • pp.366-366
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    • 2010
  • Single crystalline Fe/NiO bilayers were epitaxially grown on Ag(001) and on MgO(001), and investigated by Low Energy Electron Diffraction (LEED), Magneto-Optic Kerr Effect (MOKE), and X-ray Magnetic Linear Dichorism (XMLD). We find that while the Fe film has an in-plane magnetization in both Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems, the NiO spins switch from out-of-plane direction in Fe/NiO/MgO(001) to in-plane direction in Fe/NiO/Ag(001). These two different NiO spin orientations generate remarkable different effects that the NiO induced magnetic anisotropy in the Fe film is much greater in Fe/NiO/Ag(001) than in Fe/NiO/MgO(001). XMLD measurement shows that the much greater magnetic anisotropy in Fe/NiO/Ag(001) is due to a 90o-coupling between the in-plane NiO spins and the in-plane Fe spins which causes a switching of the NiO spins during the Fe magnetization reversal.

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Low Temperature Optical Properties of NiO coated ZnO Nanorods (NiO 코팅 두께에 따른 ZnO 나노막대의 저온분광특성)

  • Shin, Y.H.;Park, Y.H.;Kim, Yong-Min
    • Journal of the Korean Vacuum Society
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    • v.16 no.4
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    • pp.286-290
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    • 2007
  • We fabricated NiO coated ZnO nanorods using ZnO nanorods grown on a Si substrate. After thermal hydrogenation process of these NiO-ZnO core-shell nanorods, we confirm that Ni nanodots were built up on the surface of ZnO nanorods. Photoluminescence (PL) measurements at T=5 K were made to understand the optical properties of these various nanorods. As samples sequencially transformed into $ZnO{\rightarrow}NiO-ZnO{\rightarrow}Ni$ nanodot-ZnO, PL transition energies and intensities are varied as well. In comparison to pure ZnO nanorod, the acceptor bound exciton ($A^0X$) became the minor peak for NiO-ZnO nanorods. On the other hand, for Ni nanodot-ZnO sample, ($A^0X$) transition peak intensity became the most dominant peak. This is due to the fact that during thermal hydrogenation process, appreciable amounts of Ni and hydrogen ions defused into ZnO nanorod which played as accepters.

Characterization of NiO and Co3O4-Doped La(CoNi)O3 Perovskite Catalysts Synthesized from Excess Ni for Oxygen Reduction and Evolution Reaction in Alkaline Solution (과량의 니켈 첨가로 합성된 NiO와 Co3O4가 도핑된 La(CoNi)O3 페로브스 카이트의 알칼리용액에서 산소환원 및 발생반응 특성)

  • BO, LING;RIM, HYUNG-RYUL;LEE, HONG-KI;PARK, GYUNGSE;SHIM, JOONGPYO
    • Transactions of the Korean hydrogen and new energy society
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    • v.32 no.1
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    • pp.41-52
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    • 2021
  • NiO and Co3O4-doped porous La(CoNi)O3 perovskite oxides were prepared from excess Ni addition by a hydrothermal method using porous silica template, and characterized as bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for Zn-air rechargeable batteries in alkaline solution. Excess Ni induced to form NiO and Co3O4 in La(CoNi)O3 particles. The NiO and Co3O4-doped porous La(CoNi)O3 showed high specific surface area, up to nine times of conventionally synthesized perovskite oxide, and abundant pore volume with similar structure. Extra added Ni was partially substituted for Co as B site of ABO3 perovskite structure and formed to NiO and Co3O4 which was highly dispersed in particles. Excess Ni in La(CoNi)O3 catalysts increased OER performance (259 mA/㎠ at 2.4 V) in alkaline solution, although the activities (211 mA/㎠ at 0.5 V) for ORR were not changed with the content of excess Ni. La(CoNi)O3 with excess Ni showed very stable cyclability and low capacity fading rate (0.38 & 0.07 ㎶/hour for ORR & OER) until 300 hours (~70 cycles) but more excess content of Ni in La(CoNi)O3 gave negative effect to cyclability.

Preparation of La0.5Nd0.5Ni5 Alloy by an Electrochemical Reduction in Molten LiCl (LiCl 용융염에서 전해환원법을 통한 La0.5Nd0.5Ni5 합금 제조)

  • Lim, Jong Gil;Jeong, Sang Mun
    • Korean Chemical Engineering Research
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    • v.53 no.2
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    • pp.145-149
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    • 2015
  • The electrochemical behavior of $Nd_2O_3-La_2O_3-NiO$ mixed oxide including rare earth resources has been studied to synthesize $La_{0.5}Nd_{0.5}Ni_5$ alloy in a LiCl molten salt. The $Nd_2O_3-La_2O_3-NiO$ mixed oxide was converted to $NiNd_2O_4$ (spinel) and $LaNiO_3$ (perovskite) structures at a sintering temperature of $1100^{\circ}C$. The spinel and perovskite structures led a speed-up in the electrolytic reduction of the mixed oxide. Various reaction intermediates such as Ni, $NiLa_2O_4$ were observed during the electrochemical reduction by XRD analysis. A possible reaction route to $La_{0.5}Nd_{0.5}Ni_5$ in the LiCl molten salt was proposed based on the analysis result.

Improvement of Magnetoresistance in NiO Spin-Valves including CoO layer (CoO가 삽입된 NiO스핀밸브의 자기저항특성 향상에 관한 연구)

  • ;;;;;J. Ginsztler
    • Journal of the Korean Magnetics Society
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    • v.10 no.3
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    • pp.112-117
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    • 2000
  • We inserted CoO layer in NiO spin-valves to improve on magnetoresistance and exchange coupling field. The magnetoresistance ratio was increased from 4.5 % to 5.5 % with the increase of CoO thickness. We can not find the dependence between (111) texture and exchange coupling by the measurement of XRD of CoO/NiO spin-valves. The surface roughness of CoO layer, 6.1 $\AA$ is twice more than that of NiO layer, 3.1 $\AA$. The increase of exchange coupling field and coercive field in the CoO/NiO spin-valves will be due to increasing roughness. We prepared the NiO/CoO/NiO/CoO/NiO spin-valves to reduce coercive field and the coercive field decreased from 110 Oe to 50 Oe, and the coupling field is not changed from 70 Oe.

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Formation and Color of the Spinel Solid Solution in NiO-ZnO-$Fe_2O_3$-$TiO_2$-$SnO_2$ System (NiO-ZnO-$Fe_2O_3$-$TiO_2$-$SnO_2$ 계 Spinel 고용체의 생성과 발색에 관한 연구)

  • 이응상;이진성
    • Journal of the Korean Ceramic Society
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    • v.28 no.4
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    • pp.305-314
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    • 1991
  • This study was conducted to research the formation and the color development of NiO-ZnO-Fe2O3-TiO2-SnO2 system for the purpose of synthesizing the spinel pigments which are stable at high temperature. After preparing ZnO-Fe2O3 as a basic composition, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.Fe2O3 system, {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.TiO2 system, and {{{{ chi }}NiO.(l-{{{{ chi }})ZnO.SnO2 system were prepared with {{{{ chi }}=0, 0.2, 0.5, 0.7, 1 mole ratio respectively. The manufacturing was carried out at 128$0^{\circ}C$ for 30 minutes. The reflectance measurement and the X-ray analysis of these specimens were carried out and the results were summarized as follows. 1. In the specimens which included NiO, it was difficult for the spinel structure to be formed. 2. As increasing the contents of NiO and Fe2O3, all the groups which were yellow or green colored changed to brown. 3. NiO-ZnO-Fe2O3 system and NiO-ZnO-TiO2 system formed the spinel structure and the illmenite structure appeared in NiO-TiO2 system.

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Distribution Behavior of Ni between CaO-SiO2-Al2O3-MgO Slag and Cu-Ni Alloy (CaO-SiO2-Al2O3-MgO 슬래그와 Cu-Ni합금 사이의 Ni 분배거동)

  • Han, Bo-Ram;Sohn, Ho-Sang
    • Resources Recycling
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    • v.24 no.1
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    • pp.35-42
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    • 2015
  • To obtain the fundamental information on the dissolution of nickel into the slag in the pyrometallurgical processes for treatment of wasted PCB, the distribution ratios of nickel between CaO-$SiO_2-Al_2O_3$-MgO slag and copper-5 wt%Ni alloy were measured at 1623 K to 1823 K under a controlled $CO_2$-CO atmosphere. The distribution ratio of Ni increased linearly with increasing oxygen partial pressure. Therefore, the dissolution reaction of nickel into the slags could be described by the following equation; $$Ni(l)_{metal}+\frac{1}{2}O_2(g)NiO(l)_{slag}$$ The distribution ratio of Ni increased linearly with increasing content of basic oxides(CaO and MgO) in slag. However, the distribution ratio of Ni decreased linearly with increasing temperature. From these results, the empirical equation of distribution ratio of Ni was obtained by the following equation from the analysis of experimental conditions by multiple regression. $${\log}L_{Ni}=0.4000{\log}P_{O2}-5.1{\times}10^{-4}T+0.3375\(\frac{X_{CaO}+X_{MgO}}{X_{SiO2}}\)$$

Fabrication of YBCO thin film on a cube-textured Ni substrate by metal organic chemical vapor deposition (MOCVD) method

  • Lee, Young-Min;Lee, Hee-Gyoun;Hong, Gye-Won;Shin, Hyung-Sik
    • 한국초전도학회:학술대회논문집
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    • v.10
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    • pp.56-60
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    • 2000
  • Cube texture를 갖는 Ni기판위에 MOCVD(Metal Chemical Vapor Deposition)를 이용하여 NiO, CeO$_2$, YBCO 박막을 제조하였다. NiO(200)와 CeO$_2$(200) buffer layer는 450${\sim}$470$^{\circ}$C에서 10분간 MOCVD방법으로 (100)<001>Ni 기판위에 직접 증착하였다. 제조된 NiO, CeO$_2$ buffer layer는 조직이 치밀하며 표면의 상태가 매우 좋으며 Ni기판 위에 epitaxial하게 성장하였다. NiO는 Ni기판과 NiO<100>//Ni<100>의 방위관계를 가지고 성장하였으며, CeO$_2$는 증착조건에 따라 CeO$_2$ <100>//Ni<100> 및 CeO$_2$ <110>//Ni<100> 의 방위관계를 가지고 성장하였다. 증착된 NiO막과 CeO$_2$막에서 균열은 발생하지 않았다. MOCVD법으로 표면에 biaxial texture를 갖는 ceramic buffer를 증착시킨 NiO/Ni및 CeO$_2$/Ni 기판위에 YBCO박막을 MOCVD법으로 제조하였다. YBCO막은 기판온도 800$^{\circ}$C,증착압력 10torr, 산소분압을 0.7torr로 하여 10분간 행하였다. 공급원료의 조성에 따라 YBCO의 막의 texture와 형성되는 상이 변화되었다. NiO/Ni및 CeO$_2$/Ni 기판 위에 증착된 YBCO막은 c축 배향성을 가지고 성장하였으며, -scan 및 ${\varphi}$ -scan으로 측정한 (500)면의 in-plane과 (110)면의 out-of-plane의 FWHM(Full Width Half Maximum)값은 각각 10$^{\circ}$ 미만으로 우수하였다.

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