• Title, Summary, Keyword: Ni

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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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Effect of Co substitution on NiSi and $NiSi_2$: ab initio calculation (NiSi와 $NiSi_2$에 대한 Co 치환의 영향: ab initio 계산)

  • Kim, Yeong-Cheol;Seo, Hwa-Il
    • Journal of the Semiconductor & Display Technology
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    • v.6 no.3
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    • pp.13-17
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    • 2007
  • Effect of Co substitution on crystal structures of two nickel silicides, NiSi and $NiSi_2$, is investigated by using an ab initio calculation. Relaxed NiSi and $NiSi_2$ structures are calculated and the calculated lattice parameters are in good agreement with experimentally determined lattice parameters within about 2%. A Co atom substitutes a Ni and Si site, respectively, to evaluate the preferable site between them. Co prefers Ni site to Si site in both NiSi and $NiSi_2$. The calculated total energy also indicates that the Co substitution to Ni site stabilizes both the NiSi and $NiSi_2$ structures. Co also prefers Ni site in $NiSi_2$ to that in NiSi, indicating that $NiSi_2$ becomes more stable than NiSi with Co substitution. As Co addition to NiSi improves its thermal stability experimentally, this indicates that the energy barrier between the two phases is high enough to prevent the phase transformation from NiSi to $NiSi_2$ up to high temperature.

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Polymer-Metal Complexes(II). Catalytic Activity of Some Ni(II)-Polyethyleneimine Complexes (고분자-금속착물 (제2보). 몇가지 Ni(II)-Polyethyleneimine 착물의 촉매활성도)

  • Jung Hag Park;Tae Sub Cho
    • Journal of the Korean Chemical Society
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    • v.25 no.6
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    • pp.394-398
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    • 1981
  • Two types of Ni(II)-polyethyleneimine (PEI) complexes, [Ni(PEI)]$Cl_2$ and [Ni(P-EI)$Cl_2$] were synthesized and their catalytic activities in the decomposition reaction of hydrogen peroxide were investigated. For the purpose of comparison, the corresponding monomeric complexes, $[Ni(en)_3]Cl_2$ and $[Ni(en)_2Cl_2$ were also prepared; it was observed that their activities increase in the following order; $0{\approx}[Ni(en)_3]Cl_2{\le}[Ni(en)_2Cl_2]<[Ni(PEI)]Cl_2<[Ni(PEI)Cl_2]$ On the basis of structural analysis by means of visible and infrared spectroscopy, the catalytic activiy of these Ni(II)-PEI complexes is assumed to depend on the bond strength between the ligand and the nickel ion.

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Chemical Reactivity between Ni(II)-Macrocycle Complex Ions ($NiL_m{^{2+}}$) and $CN^-$ (Ni(II)-거대고리 리간드 착이온 ($NiL_m{^{2+}}$) 과 $CN^-$ 이온간의 반응성)

  • Yu-Chul Park;Jong-Chul Byun
    • Journal of the Korean Chemical Society
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    • v.31 no.4
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    • pp.334-343
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    • 1987
  • The Chemical reactions between $NiL_m{^{2+}}\{$Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;Ni(1[14]4-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{\beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}$}\and\ CN^-$ ion were studied by the spectrophotometric method. The equilibrium constants (K_1$) for the 1:1 complex ion, $[NiL_m(CN)]^+\;with\;NiL_m{^{2+}}\;and\;CN^-$ ion were determined in the range of 3 to $25^{\circ}C$. The $K_1\;for\;Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;Ni(1[14]4-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}\;at\;15^{\circ}C$ was 4.7, 5.3, 6.2, 7.5, 9.4, and 9.8, respectively. The values of $K_1$ decreased with increasing temperature. From the temperature effect on equilibrium constant ($K_1$), thermodynamic parameters $({\Delta}H^{\circ},\;{\Delta}S^{\circ},\;{\Delta}G^{\circ})$ for reaction were evaluated and the reaction of $NiL_m{^{2+}}\;and\;CN^-$ ion was exothermic. $NiL_m{^{2+}\;reacts\;with\;CN^-$ ion to give $Ni(CN)_4{^{2-}}$ ion and macrocyclic ligand $(L_m)$. The kinetics of formation of the $Ni(CN)_4{^{2-}}$ ion of varying the $[CN^-],\;[HCN],\;and\;[OH^-]$ have been investigated at 3∼$25^{\circ}C\;and\;0.5M\;NaClO_4$. Maintaining a constant $[CN^-],\;k_{obs}/[CN^-]^2$ increases linearly with increasing [HCN]. In the presence of large quantities of $[OH^-],\;k_{obs}/[CN^-]^2$ also increases linearly with $[OH^-]$. From the temperature effect on kinetic constant (k_{obs})$, parameter of activation $({\Delta}H^{\neq},\;{\Delta}S^{\neq})$ of reaction of $NiL_m{^{2+}}\;with\;CN^-$ ion were determined. For the $Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{\beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}\;series\;{\Delta}H^{\neq}$ gradually decrease as the d-d transition energy, $ν(cm^{-1})$ decrease. And the reaction of the five $NiL_m{^{2+}}\;with\;CN^-$ ion take place by way of equal paths.

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Effects of NiFeCo of NiFe Insertion Layers on the Giant Magnetoresistance Behavior of Ni/Cu Artificial Superlattice (Ni/Cu 인공초격자에서 NiFeCo 및 NiFe 계면 삽입층이 거대자기저항 거동에 미치는 영향)

  • 송용진;주승기
    • Journal of the Korean Magnetics Society
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    • v.5 no.6
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    • pp.963-967
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    • 1995
  • Ultra thin layers of NiFeCo or NiFe were inserted at the interfaces of Ni and Cu to form a multilayer structure. In case of inserting a NiFe layer, the magnetoresistance was about 6%, the saturation magnetic field was 50 Oe and the hysteresis of R-H (resistance-magnetic field) was very small. In case of inserting a NiFeCo layer, the magnetoresistance increased to about 7% but the saturation magnetic field and hysteresis were also increased. The increase of the output under biased magnetic field was much larger in case of inserting a NiFe layer because of relatively smaller hysteresis in R-H behavior.

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Interdiffusion in Cu/Capping Layer/NiSi Contacts (Cu/Capping Layer/NiSi 접촉의 상호확산)

  • You, Jung-Joo;Bae, Kyoo-Sik
    • Korean Journal of Materials Research
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    • v.17 no.9
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    • pp.463-468
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    • 2007
  • The interdiffusion characteristics of Cu-plug/Capping Layer/NiSi contacts were investigated. Capping layers were deposited on Ni/Si to form thermally-stable NiSi and then were utilized as diffusion barriers between Cu/NiSi contacts. Four different capping layers such as Ti, Ta, TiN, and TaN with varying thickness from 20 to 100 nm were employed. When Cu/NiSi contacts without barrier layers were furnace-annealed at $400^{\circ}C$ for 40 min., Cu diffused to the NiSi layer and formed $Cu_3Si$, and thus the NiSi layer was dissociated. But for Cu/Capping Layers/NiSi, the Cu diffusion was completely suppressed for all cases. But Ni was found to diffuse into the Cu layer to form the Cu-Ni(30at.%) solid solution, regardless of material and thickness of capping layers. The source of Ni was attributed to the unreacted Ni after the silicidation heat-treatment, and the excess Ni generated by the transformation of $Ni_2Si$ to NiSi during long furnace-annealing.

Influence of Change of Ni Concentration in Baths Fabricated by Dissolving Metal Ni Powders on Properties of Electrodeposited Ni Film (금속 Ni 분말을 용해하여 제조된 용액에서 Ni 농도 변화가 전기도금 된 Ni 필름 특성에 미치는 영향)

  • Yoon, Pilgeun;Park, Deok-Yong
    • Journal of the Korean institute of surface engineering
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    • v.52 no.2
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    • pp.78-83
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    • 2019
  • Chloride baths for electrodeposited Ni thin films were fabricated by dissolving metal Ni powders with the mixed solution consisting of HCl and de-ionized water. Current efficiency, residual stress, surface morphology and microstructure of Ni films with the change of metal ion ($Ni^{2+}$) concentrations in the plating solution were studied. Current efficiency was measured to be more than 90% with increasing $Ni^{2+}$ concentrations in the plating solution. Residual stress of Ni thin film was increased from about 400 to 780 MPa with increasing $Ni^{2+}$ concentration from 0.2 to 0.5 M. It is gradually decreased to 650 MPa at 0.9 M $Ni^{2+}$ concentration. Smooth surface morphologies were observed over 0.3 M $Ni^{2+}$ concentration, but nodule surface morphology at 0.2 M. Ni films consist of FCC(111), FCC(200), FCC(220) and FCC(311) peaks in XRD patterns. Preferred orientation of FCC(111) was observed and its intensity was slightly decreased with increasing $Ni^{2+}$ concentration. The average grain size was slightly increased at 0.3 M $Ni^{2+}$ concentration and then slightly decreased with increasing $Ni^{2+}$ concentration.

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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Magneto resistance in NiO/NiFe/Cu/NiFe spin-valve Sandwiches (NiO/NiFe/Cu/NiFe 스핀-밸브 샌드위치의 자기저항 특성)

  • 김재욱
    • Electrical & Electronic Materials
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    • v.10 no.10
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    • pp.1016-1021
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    • 1997
  • Magneto resistance properties in spin-valve sandwiches with various thickness of nanmagnetic layer in contact with the ferromagnetic NiFe film were investigated. The NiFe layer in contact with the NiO film was pinned by strongly exchange-biased coupling and the free NiFe layer at the film surface induced a sharp change in the magnetoresistance at -5~15Oe due to small coercivity. The NiO/NiFe/Cu/NiFe film showed a magnetoresistance ratio in the range of 2.3~2.9% and a field sensitivity above 2.2%/Oe with various of nonmagnetic layer. The NiO/NiFe/Cu/NiFe film of the field sensitivity above 2.2%/Oe suggests stang possibility of magnetic sensor matter.

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Reaction diffusion and formation of$Ni_3Al$ phase at the Ni-NiAl diffusion couple (Ni-NiAl 확산대에서 $Ni_3Al$ 상의 형성과 반응확산)

  • 정승부
    • Journal of Welding and Joining
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    • v.15 no.3
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    • pp.128-135
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    • 1997
  • Reaction diffusion and formation of $Ni_3Al$phase with $L1_2$ structure have been studied in temperature range of 1432K to 1573K using the diffusion couple of (Ni-40, 5at%Al)/(Ni-14, 1at%Al) and (Ni-49, 2at%Al)/ (Nickel). The layer growth of Ni$_{3}$Al pyhase in the annealed diffusion couple was measured by optical microscope and electron probe microanalyzer (EPMA). The layer growth of $Ni_3Al$phase in diffusion zone obeyed the parabolic law without any indication of grain boundary effects. The layer growth of $Ni_3Al$phase in temperature range of 1423K to 1573K was mainly controlled by the volume diffusion mechanism. The rate of layer growth of $Ni_3Al$phase was found to be colsely related to the composition of intermetallic compound NiAl phase. The activation energy for layer growth of $Ni_3Al$phase was calculated to be 127kJ/mol.

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