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Sample records for ni okeru doro

  1. Management of technical date in Nihon Doro kodan

    NASA Astrophysics Data System (ADS)

    Hanada, Jun'ichi

    Nihon Doro Kodan Laboratory has collected and contributed technical data (microfiches, aerial photographs, books and literature) on plans, designs, constructions and maintenance of the national expressways and the ordinary toll roads since 1968. This work is systematized on computer to retrieve and contribute data faster. Now Laboratory operates Technical Data Management System which manages all of technical data and Technical Document Management System which manages technical documents. These systems stand on users' on-line retrieval and data accumuration by microfiches and optical disks.

  2. Complexity on a small scale: Emplacement dynamics and evolution of the Doros layered mafic intrusion, Namibia

    NASA Astrophysics Data System (ADS)

    Owen-Smith, Trishya; Ashwal, Lewis

    2014-05-01

    The Doros Complex in Namibia is a relatively small (~8 km x 4 km), shallow-level layered mafic intrusion that forms part of the ~132 Ma Paraná-Etendeka Large Igneous Province. It consists of a ~500 m-thick preserved sequence of roughly concordant, sill-like gabbro layers dipping in towards the centre of the intrusion, cut by syenitic (bostonite) dykes. The fundamental mineralogy is essentially the same throughout the main package (plagioclase + calcic clinopyroxene + oxy-exsolved Fe-Ti oxides ± olivine), and hence the layering is defined by variations in the modal proportions of these minerals, and in the mineral and rock textures. A detailed petrographic, whole-rock and mineral major and trace element, and Sr-, Nd- and Pb-isotopic study, combined with major element modelling, has shown that the stratigraphic order of appearance of cumulus minerals and overall trends in rock compositions are consistent with fractional crystallisation and accumulation from an uncontaminated basaltic parental magma. However, these data also reveal considerable complexity and stratigraphic trends in mineralogy, chemistry and physical properties incongruent with a simple progressive differentiation path. Based on a comprehensive set of field, petrographic, geochemical and geophysical evidence, we put forward a compelling argument in favour of an origin for the Doros intrusion by multiple, closely-spaced influxes of crystal-bearing magmas (magma mushes), rather than from the post-emplacement differentiation of a single batch of crystal-free melt. This evidence includes intrusive layer relations, textural evidence for primocrysts, disequilibrium features, and stratigraphic reversals in mineral and whole-rock chemistry and magnetic properties. At least seven distinct major injections of magma have been identified in the stratigraphy, as well as several smaller pulses. These findings represent a departure from the traditional single-pulse liquid magma model for the formation of such

  3. Evidence for multiple pulses of crystal-bearing magma during emplacement of the Doros layered intrusion, Namibia

    NASA Astrophysics Data System (ADS)

    Owen-Smith, T. M.; Ashwal, L. D.

    2015-12-01

    The Doros Complex is a relatively small (maximum 3.5 km × 7.5 km) shallow-level, lopolithic, layered mafic intrusion in the early Cretaceous Paraná-Etendeka Large Igneous Province. The stratigraphy broadly comprises a minor, fine-grained gabbroic sill and a sequence of primitive olivine-cumulate melagabbros, with a basal chilled margin, an intermediate plagioclase-cumulate olivine gabbro, and a sequence of mineralogically and texturally variable, intermediate, strongly foliated, plagioclase-, olivine- or magnetite-cumulate gabbros. An evolved syenitic (bostonite) phase occurs as cross-cutting dykes or as enclaves within the foliated gabbros. Major element modelling of the liquid line of descent shows that the spectrum of rock types, including the bostonite, is consistent with the fractionation of a basaltic parental magma that crystallised olivine, clinopyroxene, plagioclase, magnetite, K-feldspar and apatite. However, the stratigraphic succession does not correspond to a simple progressive differentiation trend but instead shows a series of punctuated trends, each defined by a compositional reversal or hiatus. Incompatible trace element concentrations do not increase upwards though the body of the intrusion. The major units show similar, mildly enriched rare earth element patterns, with minimal Eu anomalies. Back-calculation of the rare earth element concentrations of these cumulate rocks produces relatively evolved original liquid compositions, indicating fractionation of this liquid from a more primitive precursor. Based on combined field, petrographic, geochemical and geophysical evidence, we propose an origin for the Doros Complex by a minimum of seven closely spaced influxes of crystal-bearing magmas, each with phenocryst contents between 5% and 55%. These findings represent a departure from the traditional single-pulse liquid model for the formation of layered mafic intrusions and suggest the presence of an underlying magmatic mush column, i.e., a large

  4. Bridging exchange bias effect in NiO and Ni(core)@NiO(shell) nanoparticles

    NASA Astrophysics Data System (ADS)

    Rinaldi-Montes, Natalia; Gorria, Pedro; Martínez-Blanco, David; Fuertes, Antonio B.; Fernández Barquín, Luis; Puente-Orench, Inés; Blanco, Jesús A.

    2016-02-01

    Among all bi-magnetic core(transition metal)@shell(transition metal oxide) nanoparticles (NPs), Ni@NiO ones show an onset temperature for the exchange bias (EB) effect far below the Néel temperature of bulk antiferromagnetic NiO. In this framework, the role played by the magnetism of NiO at the nanoscale is investigated by comparing the microstructure and magnetic properties of NiO and Ni@NiO NPs. With the aim of bridging the two systems, the diameter of the NiO NPs (~4 nm) is chosen to be comparable to the shell thickness of Ni@NiO ones (~2 nm). The EB effect in Ni@NiO NPs is attributed to the exchange coupling between the core and the shell, with an interfacial exchange energy of ΔE~0.06 erg cm-2, thus comparable to previous reports on Ni/NiO interfaces both in thin film and NP morphologies. In contrast, the EB detected in NiO NPs is explained in a picture where uncompensated spins located on a magnetically disordered surface shell are exchange coupled to the antiferromagnetic core. In all the studied NPs, the variation of the EB field as a function of temperature is described according to a negative exponential law with a similar decay constant, yielding a vanishing EB effect around T~40-50 K. In addition, the onset temperature for the EB effect in both NiO and Ni@NiO NPs seems to follow a universal dependence with the NiO crystallite size.

  5. Bonding in zerovalent Ni compounds - NiN2 and Ni(N2)4 compared with NiCO and Ni(CO)4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Barnes, Leslie A.

    1989-01-01

    Calculations are carried out on NiN2, which may be considered a prototypical metal surface-ligand system. A large Gaussian basis set and an MCPF treatment of electron correlation are used. Consideration is also given to the 2Sigma(+) states of NiN2(-), NiCO(-), and NiN2(+), the low-lying 2Delta and 2Pi states of NiN2(+), and the 1A1 states of Ni(CO)4 and Ni(N2)4.

  6. Ni-Co laterite deposits

    USGS Publications Warehouse

    Marsh, Erin E.; Anderson, Eric D.

    2011-01-01

    Nickel-cobalt (Ni-Co) laterite deposits are an important source of nickel (Ni). Currently, there is a decline in magmatic Ni-bearing sulfide lode deposit resources. New efforts to develop an alternative source of Ni, particularly with improved metallurgy processes, make the Ni-Co laterites an important exploration target in anticipation of the future demand for Ni. This deposit model provides a general description of the geology and mineralogy of Ni-Co laterite deposits, and contains discussion of the influences of climate, geomorphology (relief), drainage, tectonism, structure, and protolith on the development of favorable weathering profiles. This model of Ni-Co laterite deposits represents part of the U.S. Geological Survey Mineral Resources Program's effort to update the existing models to be used for an upcoming national mineral resource assessment.

  7. The oxidation of Ni-rich Ni-Al intermetallics

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Smialek, J. L.; Barrett, C. A.

    1989-01-01

    The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy compositions under cyclic and isothermal oxidation. The isothermal growth rates did not increase monotonically as the alloy Al content was decreased. The characteristically ridged alpha-Al203 scale morphology, consisting of cells of thin, textured oxide with thick growth ridges at cell boundaries, forms on oxidized beta-NiAl alloys. The correlation of scale features with isothermal growth rates indicates a predominant grain boundary diffusion growth mechanism. The 1200 C cyclic oxidation resistance decreases near the lower end of the beta-NiAl phase field.

  8. The oxidation of Ni-rich Ni-Al intermetallics

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph; Smialek, James L.; Barrett, Charles A.

    1988-01-01

    The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy compositions under cyclic and isothermal oxidation. The isothermal growth rates did not increase monotonically as the alloy Al content was decreased. The characteristically ridged alpha-Al2O3 scale morphology, consisting of cells of thin, textured oxide with thick growth ridges at cell boundaries, forms on oxidized beta-NiAl alloys. The correlation of scale features with isothermal growth rates indicates a predominant grain boundary diffusion growth mechanism. The 1200 C cyclic oxidation resistance decreases near the lower end of the beta-NiAl phase field.

  9. Magnetic properties of Ni/NiO nanocomposites synthesized by one step solution combustion method

    NASA Astrophysics Data System (ADS)

    Ganeshchandra Prabhu, V.; Shajira, P. S.; Lakshmi, N.; Junaid Bushiri, M.

    2015-12-01

    Ni/NiO nanocomposites were synthesized using solution combustion method and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX) and carbon, hydrogen, nitrogen (CHN) analyser. The Ni or NiO content in Ni/NiO nanocomposites vary with the quantity of HNO3 used for the synthesis. Magnetic coercivity (Hc) of Ni/NiO nanocomposites is found to be 413 Oe which can be used in magnetic applications. A feeble exchange bias of 7 Oe is seen from the NiO rich Ni/NiO.

  10. Reactive Ni/Ti nanolaminates

    SciTech Connect

    Adams, D. P.; Bai, M. M.; Rodriguez, M. A.; McDonald, J. P.; Jones, E. Jr.; Brewer, L.; Moore, J. J.

    2009-11-01

    Nickel/titanium nanolaminates fabricated by sputter deposition exhibited rapid, high-temperature synthesis. When heated locally, self-sustained reactions were produced in freestanding Ni/Ti multilayer foils characterized by average propagation speeds between approx0.1 and 1.4 m/s. The speed of a propagating reaction front was affected by total foil thickness and bilayer thickness (layer periodicity). In contrast to previous work with compacted Ni-Ti powders, no preheating of Ni/Ti foils was required to maintain self-propagating reactions. High-temperature synthesis was also stimulated by rapid global heating demonstrating low ignition temperatures (T{sub ig})approx300-400 deg. C for nanolaminates. Ignition temperature was influenced by bilayer thickness with more coarse laminate designs exhibiting increased T{sub ig}. Foils reacted in a vacuum apparatus developed either as single-phase B2 cubic NiTi (austenite) or as a mixed-phase structure that was composed of monoclinic B19{sup '} NiTi (martensite), hexagonal NiTi{sub 2}, and B2 NiTi. Single-phase, cubic B2 NiTi generally formed when the initial bilayer thickness was made small.

  11. Interdiffusion in the Ni/TD-NiCr and Cr/TD-NiCr systems

    NASA Technical Reports Server (NTRS)

    Pawar, A. V.; Tenney, D. R.

    1974-01-01

    The diffusion of Ni and Cr into TD-NiCr has been studied over the 900 to 1100 C temperature range. The diffusion couples were prepared by electroplating Cr and Ni on polished TD-NiCr wafers. Concentration profiles produced as a result of isothermal diffusion at 905, 1000, and 1100 C were determined by electron microprobe analysis. The Boltzmann-Matano analysis was used to determine concentration-dependent diffusion coefficients which were found to compare favorably with previously reported values. These data suggest that 2 vol % ThO2 distribution has no appreciable effect on the rates of diffusion in TD-NiCr with a large grain size. This supports the view that an inert dispersoid in an alloy matrix will not in itself lead to enhanced diffusion unless a short-circuit diffusion structure is stabilized.

  12. Synthesis and electrochemical behavior of nanostructured cauliflower-shape Co-Ni/Co-Ni oxides composites

    SciTech Connect

    Gupta, Vinay Kawaguchi, Toshikazu; Miura, Norio

    2009-01-08

    Nanostructured Co-Ni/Co-Ni oxides were electrochemically deposited onto stainless steel electrode by electrochemical method and characterized for their structural and supercapacitive properties. The SEM images indicated that the obtained Co-Ni/Co-Ni oxides had cauliflower-type nanostructure. The X-ray diffraction pattern showed the formation of Co{sub 3}O{sub 4}, NiO, Co and Ni. The EDX elemental mapping images indicated that Ni, Co and O are distributed uniformly. The deposited Co-Ni/Co-Ni oxides showed good supercapacitive characteristics with a specific capacitance of 331 F/g at 1 mA/cm{sup 2} current density in 1 M KOH electrolyte. A mechanism of the formation of cauliflower-shape Co-Ni/Co-Ni oxides was proposed. A variety of promising applications in the fields such as energy storage devices and sensors can be envisioned from Co-Ni/Co-Ni oxides.

  13. Domain Structures and Anisotropy in Exchange-coupled [Co/Pd]-NiFe and [Co/Ni]-NiFe Multilayers

    NASA Astrophysics Data System (ADS)

    Tryputen, Larysa; Chung, Sunjae; Mohseni, Majid; Nguyen, T. N. Anh; Åkerman, Johan; Guo, Feng; McMichael, Robert D.; Ross, Caroline A.

    2014-03-01

    Exchange-coupled multilayers [Co/Pd]5-/NiFe and [Co/Ni]4-NiFe with strong perpendicular magnetic anisotropy have been proposed to use in spin-torque switching and oscillators devices with tilted fixed and free layer to improve their functional performance. We present an experimental study of the magnetization behavior of [Co/Pd]5-/NiFe and [Co/Ni]4-NiFe multilayers measured using magnetometry, magnetic force microscopy (MFM) and ferromagnetic resonance (FMR) as a function of the thickness of the top NiFe layer. We varied the thickness of the NiFe layer in [Co/Pd]5-NiFe (t), t = 0 - 80 nm and [Co/Ni]4-NiFe (t), t = 0.5 - 2.5 nm in order to study the interplay between perpendicular magnetization of the Co/Pd or Co/Ni multilayers and in-plane magnetization of the NiFe. Our magnetometry and FMR data suggest that the [Co/Ni]4/NiFe multilayer behaves like a homogeneous ferromagnetic film with anisotropy that reorients towards in-plane as the NiFe thickness increases, whereas the [Co/Pd]5/NiFe multilayer reveals more complex behavior in which the [Co/Pd] layer retains out-of-plane anisotropy while the magnetization of NiFe layer tilts in-plane with increasing thickness. MFM showed that domains with ~0.1 +/-m size were visible in [Co/Pd]-/NiFe with NiFe thickness of 20-80 nm. Multilayers were patterned into sub-100 nm dots using ion beam etching and their magnetization behavior are compared with unpatterned films.

  14. Measurement of 59Ni and 63Ni by accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; He, Ming; Ruan, Xiangdong; Xu, Yongning; Shen, Hongtao; Du, Liang; Xiao, Caijin; Dong, Kejun; Jiang, Shan; Yang, Xuran; Lan, Xiaoxi; Wu, Shaoyong; Zhao, Qingzhang; Cai, Li; Pang, Fangfang

    2015-10-01

    The long lived isotopes 59Ni and 63Ni can be used in many areas such as radioactive waste management, neutron dosimetry, cosmic radiation study, and so on. Based on the large accelerator and a big Q3D magnetic spectrometer, the measurement method for 59Ni and 63Ni is under development at the AMS facility at China Institute of Atomic Energy (CIAE). By using the ΔE-Q3D technique with the Q3D magnetic spectrometer, the isobaric interferences were greatly reduced in the measurements of 59Ni and 63Ni. A four anode gas ionization chamber was then used to further identify isobars. With these techniques, the abundance sensitivities of 59Ni and 63Ni measurements are determined as 59Ni/Ni = 1 × 10-13 and 63Ni/Ni = 2 × 10-12, respectively.

  15. Thermal modeling of NiH2 batteries

    NASA Technical Reports Server (NTRS)

    Ponthus, Agnes-Marie; Alexandre, Alain

    1994-01-01

    The following are discussed: NiH2 battery mission and environment; NiH2 cell heat dissipation; Nodal software; model development general philosophy; NiH2 battery model development; and NiH2 experimental developments.

  16. Ni5, Ni8, and Ni10 clusters with 2,6-diacetylpyridine-dioxime as a ligand.

    PubMed

    Escuer, Albert; Esteban, Jordi; Roubeau, Olivier

    2011-09-19

    In the present work, novel coordination possibilities for the system dapdoH(2)/Ni(II) (dapdoH(2) = 2,6-diacetylpyridine-dioxime) have been explored. Depending on the starting reagents and solution conditions, several clusters with nuclearities ranging from Ni(5) to Ni(10) were achieved and structurally characterized, namely, [Ni(5)(R-COO)(2)(dapdo)(2)(dapdoH)(2)(N(CN)(2))(2)(MeOH)(2)] in which R-COO(-) = benzoate (1) or 3-chlorobenzoate (2), [Ni(8)(dapdo)(4)(NO(3))(4)(OH)(4)(MeOH)(4)] (3), and [Ni(10)(dapdo)(8)(N(CN)(2))(2)(MeO)(MeOH)](NO(3)) (4). For the first time, pentadentate coordination for the dapdo(2-) ligand has been established. All compounds show a combination of square-planar and octahedrally coordinated nickel atoms. According to the Ni(2)(sp)Ni(3)(Oh) (1 and 2), Ni(4)(sp)Ni(4)(Oh) (3), and Ni(4)(sp)Ni(6)(Oh) (4) environments, these systems magnetically behave as trimer, tetramer, and hexanuclear clusters, respectively. dc magnetic measurements in the 2-300 K range of temperature reveal antiferromagnetic coupling for all compounds, and the correlation of the superexchange interaction with the torsion angles involving the oximato bridges is experimentally confirmed. PMID:21853990

  17. On the similarity of the bonding in NiS and NiO

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1985-01-01

    The bonding in NiS is found to be quite similar to that in NiO, having an ionic contribution arising from the donation of the Ni 4s electron to the S atom and a covalent component arising from bonds between the Ni 3d and the S 3p. The one-electron d bonds are found to be of equal strength for NiO and NiS, but the two-electron d bonds are weaker for NiS.

  18. Recycling Ni from Contaminated and Mineralized Soils.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rare plant species accumulate potentially valuable concentrations of some metals. Alyssum murale readily accumulates over 2% Ni in aboveground dry matter when grown on Ni-mineralized serpentine soils in Oregon, allowing production of “hay” biomass with at least 400 kg Ni ha-1 with low levels of fer...

  19. Oxygen potentials in Ni + NiO and Ni + Cr[sub 2]O[sub 3] + NiCr[sub 2]O[sub 4] systems

    SciTech Connect

    Kale, G.M.; Fray, D.J. . Dept. of Mining and Mineral Engineering)

    1994-06-01

    The chemical potential of O for the coexistence of Ni + NiO and Ni + Cr[sub 2]O[sub 3] + NiCr[sub 2]O[sub 4] equilibria has been measured employing solid-state galvanic cells, (+) Pt, Cu + Cu[sub 2]O [vert bar][vert bar] (Y[sub 2]O[sub 3])ZrO[sub 2] [vert bar][vert bar] Ni + NiO, Pt (-) and (+) Pt, Ni + NiO [vert bar][vert bar] (Y[sub 2]O[sub 3])ZrO[sub 2] [vert bar][vert bar] Ni + Cr[sub 2]O[sub 3] + NiCr[sub 2]O[sub 4], Pt (-) in the temperature range of 800 to 1,300 K and 1,100 to 1,460 K, respectively. The electromotive force (emf) of both he cells was reversible, reproducible on thermal cycling, and varied linearly with temperature. for the coexistence of the two-phase mixture of Ni + NiO, [Delta][mu][sub O[sub 2

  20. Reaction of amorphous Ni-W and Ni-N-W films with substrate silicon

    NASA Technical Reports Server (NTRS)

    Zhu, M. F.; Suni, I.; Nicolet, M.-A.; Sands, T.

    1984-01-01

    Wiley et al. (1982) have studied sputtered amorphous films of Nb-Ni, Mo-Ni, Si-W, and Si-Mo. Kung et al. (1984) have found that amorphous Ni-Mo films as diffusion barriers between multilayer metallizations on silicon demonstrate good electrical and thermal stability. In the present investigation, the Ni-W system was selected because it is similar to the Ni-Mo system. However, W has a higher silicide formation temperature than Mo. Attention is given to aspects of sample preparation, sample characterization, the interaction between amorphous Ni-W films and Si, the crystallization of amorphous Ni(36)W(64) films on SiO2, amorphous Ni-N-W films, silicide formation and phase separation, and the crystallization of amorphous Ni(36)W(64) and Ni(30)N(21)W(49) layers.

  1. Kinetics of Ni2Si growth from pure Ni and Ni(V) films on (111) and (100) Si

    NASA Astrophysics Data System (ADS)

    Harith, M. A.; Zhang, J. P.; Campisano, S. U.; Klaar, H.-J.

    1987-01-01

    The kinetics of Ni2Si growth from pure Ni and from Ni0.93V0.07 films on (111) and (100) silicon has been studied by the combination of He+ backscattering, x-ray diffraction, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) techniques. The activation energies are 1.5 and 1.0 eV for pure Ni and Ni(V) films, respectively while the pre-exponential factors in Ni(V) are 4 5 orders of magnitude smaller than in the pure Ni case. The variations in the measured rates are related to the different grain size of the growing suicide layers. The vanadium is rejected from the silicide layer and piles up at the metalsilicide interface.

  2. Kinetics of Ni Sorption in Soils: Roles of Soil Organic Matter and Ni Precipitation

    SciTech Connect

    Shi, Zhenqing; Peltier, Edward; Sparks, Donald L.

    2012-12-10

    The kinetics of Ni sorption to two Delaware agricultural soils were studied to quantitatively assess the relative importance of Ni adsorption on soil organic matter (SOM) and the formation of Ni layered double hydroxide (Ni-LDH) precipitates using both experimental studies and kinetic modeling. Batch sorption kinetic experiments were conducted with both soils at pH 6.0, 7.0, and 7.5 from 24 h up to 1 month. Time-resolved Ni speciation in soils was determined by X-ray absorption spectroscopy (XAS) during the kinetic experiments. A kinetics model was developed to describe Ni kinetic reactions under various reaction conditions and time scales, which integrated Ni adsorption on SOM with Ni-LDH precipitation in soils. The soil Ni speciation (adsorbed phases and Ni-LDH) calculated using the kinetics model was consistent with that obtained through XAS analysis during the sorption processes. Under our experimental conditions, both modeling and XAS results demonstrated that Ni adsorption on SOM was dominant in the short term and the formation of Ni-LDH precipitates accounted for the long-term Ni sequestration in soils, and, more interestingly, that the adsorbed Ni may slowly transfer to Ni-LDH phases with longer reaction times.

  3. Thermal Stability of Ni-Mn Electrodeposits

    SciTech Connect

    Talin, A. A.; Marquis, E. A.; Goods, S. H.; Kelly, J. J.; Miller, Michael K

    2006-01-01

    The effect of Mn additions on the structural stability of electrodeposited Ni is investigated by comparing the microstructure evolution of Ni and Ni-Mn specimens with similar crystallographic initial textures. As deposited, Ni-Mn electrodeposits have a smaller crystallite size and substantially higher yield strength than Ni deposits, in agreement with the Hall-Petch relationship. Moreover, dilute Ni-Mn electrodeposits exhibit a thermal stability that significantly exceeds that of pure Ni. Indeed, Ni-Mn retains its texture, fine-grain microstructure, and strength above 500 C (for 1 h anneal), and does not recrystallize up to 800 C. In contrast, pure Ni with larger average grain size and similar preferred orientation shows abnormal grain growth at 300 C and recrystallization at 600 C. This study suggests two distinct temperature regimes. Below 600 C, grain boundary segregation appears as a plausible mechanism for the thermal stability of Ni-Mn electrodeposits, whereas grain boundary pinning by precipitation contributes to the improved microstructural stability of Ni-Mn above 600 C.

  4. Phonon Dispersion in Amorphous Ni-Alloys

    NASA Astrophysics Data System (ADS)

    Vora, A. M.

    2007-06-01

    The well-known model potential is used to investigate the longitudinal and transverse phonon dispersion curves for six Ni-based binary amorphous alloys, viz. Ni31Dy69, Ni33Y67, Ni36Zr64, Ni50Zr50, Ni60 Nb40, and Ni81B19. The thermodynamic and elastic properties are also computed from the elastic limits of the phonon dispersion curves. The theoretical approach given by Hubbard-Beeby is used in the present study to compute the phonon dispersion curves. Five local field correction functions proposed by Hartree, Taylor, Ichimaru-Utsumi, Farid et al. and Sarkar et al. are employed to see the effect of exchange and correlation in the aforesaid properties.

  5. California Niño/Niña

    PubMed Central

    Yuan, Chaoxia; Yamagata, Toshio

    2014-01-01

    The present study shows the existence of intrinsic coastal air-sea coupled phenomenon in the coastal ocean off Baja California and California in boreal summer for the first time. It contributes significantly to the interannual sea surface temperature (SST) anomalies there. An initial decrease/increase in the equatorward alongshore surface winds weakens/strengthens the coastal upwelling and raises/lowers the coastal SSTs through oceanic mixed-layer processes. The resultant coastal warming/cooling, in turn, heats/cools the overlying atmosphere anomalously, decreases/increases the atmospheric pressure in the lower troposphere, generates an anomalous cross-shore pressure gradient, and thus reinforces or maintains the alongshore surface wind anomalies. The regional air-sea coupled phenomenon seems to be analogous to the well-known El Niño/Southern Oscillation (ENSO) in the tropical Pacific but with much smaller time and space scales, and may be referred to as California Niño/Niña in its intrinsic sense. PMID:24763062

  6. California Niño/Niña.

    PubMed

    Yuan, Chaoxia; Yamagata, Toshio

    2014-01-01

    The present study shows the existence of intrinsic coastal air-sea coupled phenomenon in the coastal ocean off Baja California and California in boreal summer for the first time. It contributes significantly to the interannual sea surface temperature (SST) anomalies there. An initial decrease/increase in the equatorward alongshore surface winds weakens/strengthens the coastal upwelling and raises/lowers the coastal SSTs through oceanic mixed-layer processes. The resultant coastal warming/cooling, in turn, heats/cools the overlying atmosphere anomalously, decreases/increases the atmospheric pressure in the lower troposphere, generates an anomalous cross-shore pressure gradient, and thus reinforces or maintains the alongshore surface wind anomalies. The regional air-sea coupled phenomenon seems to be analogous to the well-known El Niño/Southern Oscillation (ENSO) in the tropical Pacific but with much smaller time and space scales, and may be referred to as California Niño/Niña in its intrinsic sense. PMID:24763062

  7. B-Ni-Ti (164)

    NASA Astrophysics Data System (ADS)

    Carow-Watamura, U.; Louzguine, D. V.; Takeuchi, A.

    This document is part of Part 2 http://dx.doi.org/10.1007/97.etType="URL"/> 'Systems from B-Be-Fe to Co-W-Zr' of Subvolume B 'Physical Properties of Ternary Amorphous Alloys' of Volume 37 'Phase Diagrams and Physical Properties of Nonequilibrium Alloys' of Landolt-Börnstein - Group III 'Condensed Matter'. It contains the Chapter 'B-Ni-Ti (164)' with the content:

  8. Processing and Mechanical Properties of Directionally Solidified NiAl/NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1994-01-01

    Promising creep strengths were found for a directionally solidified NiAl-NiAlTa alloy when compared to other NiAl based intermetallics. The directionally solidified alloy had an off-eutectic composition that resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The room temperature toughness of the two phase alloy was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa. Alloying additions that may improve the room temperature toughness by producing multiphase alloys are discussed.

  9. Measured Activities of Al and Ni in gamma-(Ni) and gamma'-(Ni)3Al in the Ni-Al-Pt System

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2007-01-01

    Adding Pt to Ni-Al coatings is critical to achieving the required oxidation protection of Ni-based superalloys, but the nature of the Pt effect remains unresolved. This research provides a fundamental part of the answer by measuring the influence of Pt on the activities of Al and Ni in gamma-(Ni), gamma prime-(Ni)3Al and liquid in the Ni-Al-Pt system. Measurements have been made at 25 compositions in the Ni-rich corner over the temperature range, T = 1400-1750 K, by the vapor pressure technique with a multiple effusion-cell mass spectrometer (multi-cell KEMS). These measurements clearly show adding Pt (for X(sub Pt) less than 0.25) decreases a(Al) while increasing a(Ni). This solution behavior supports the idea that Pt increases Al transport to an alloy / Al2O3 interface and also limits the interaction between the coating and substrate alloys in the gamma-(Ni) + gamma prime-(Ni)3Al region. This presentation will review the progress of this study.

  10. Ultrafast Alkaline Ni/Zn Battery Based on Ni-Foam-Supported Ni3S2 Nanosheets.

    PubMed

    Hu, Pu; Wang, Tianshi; Zhao, Jingwen; Zhang, Chuanjian; Ma, Jun; Du, Huiping; Wang, Xiaogang; Cui, Guanglei

    2015-12-01

    Self-supported Ni3S2 ultrathin nanosheets were in situ formed by direct sulfurization of commercially available nickel foam using thioacetamide as sulfur source under hydrothermal process. The morphology and structure of the as-obtained sample were analyzed by using XRD, XPS, SEM, and TEM, revealing that an ultrathin nanosheets Ni3S2 were grown on the surface of Ni form. The as-obtained Ni3S2/Ni composite with uniform architecture was used as cathode material for alkaline Ni/Zn battery, which delivered high capacity of 125 mAh g(-1) after 100 cycles with no obvious capacity fading, extraordinary rate capability (68 mAh g(-1) at the current density of 5.0 A g(-1)), and high operating voltage (1.75 V). PMID:26599523

  11. The impact of Ni on the physiology of a Mediterranean Ni-hyperaccumulating plant.

    PubMed

    Roccotiello, Enrica; Serrano, Helena Cristina; Mariotti, Mauro Giorgio; Branquinho, Cristina

    2016-06-01

    High nickel (Ni) levels exert toxic effects on plant growth and plant water content, thus affecting photosynthesis. In a pot experiment, we investigated the effect of the Ni concentration on the physiological characteristics of the Ni hyperaccumulator Alyssoides utriculata when grown on a vermiculite substrate in the presence of different external Ni concentrations (0-500 mg Ni L(-1)). The results showed that the Ni concentration was higher in leaves than in roots, as evidenced by a translocation factor = 3 and a bioconcentration factor = 10. At the highest concentration tested (500 mg Ni L(-1)), A. utriculata accumulated 1100 mg Ni per kilogram in its leaves, without an effects on its biomass. Plant water content increased significantly with Ni accumulation. Ni treatment did not, or only slightly, affected chlorophyll fluorescence parameters. The photosynthetic efficiency (FV/FM) of A. utriculata was stable between Ni treatments (always ≥ 0.8) and the photosynthetic performance of the plant under Ni stress remained high (performance index = 1.5). These findings support that A. utriculata has several mechanisms to avoid severe damage to its photosynthetic apparatus, confirming the tolerance of this species to Ni under hyperaccumulation. PMID:26983814

  12. Investigation on the Interactions of NiCR and NiCR-2H with DNA

    PubMed Central

    Chitranshi, Priyanka; Chen, Chang-Nan; Jones, Patrick R.; Faridi, Jesika S.; Xue, Liang

    2010-01-01

    We report here a biophysical and biochemical approach to determine the differences in interactions of NiCR and NiCR-2H with DNA. Our goal is to determine whether such interactions are responsible for the recently observed differences in their cytotoxicity toward MCF-7 cancer cells. Viscosity measurement and fluorescence displacement titration indicated that both NiCR and NiCR-2H bind weakly to duplex DNA in the grooves. The coordination of NiCR-2H with the N-7 of 2′-deoxyguanosine 5′-monophosphate (5′-dGMP) is stronger than that of NiCR as determined by 1H NMR. NiCR-2H, like NiCR, can selectively oxidize guanines present in distinctive DNA structures (e.g., bulges), and notably, NiCR-2H oxidizes guanines more efficiently than NiCR. In addition, UV and 1H NMR studies revealed that NiCR is oxidized into NiCR-2H in the presence of KHSO5 at low molar ratios with respect to NiCR (≤4). PMID:20671951

  13. A threonine stabilizes the NiC and NiR catalytic intermediates of [NiFe]-hydrogenase.

    PubMed

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-03-27

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production. PMID:25666617

  14. A Threonine Stabilizes the NiC and NiR Catalytic Intermediates of [NiFe]-hydrogenase*

    PubMed Central

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L.; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-01-01

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production. PMID:25666617

  15. Electromigration effect of Ni electrodes on the resistive switching characteristics of NiO thin films

    NASA Astrophysics Data System (ADS)

    Lee, C. B.; Kang, B. S.; Lee, M. J.; Ahn, S. E.; Stefanovich, G.; Xianyu, W. X.; Kim, K. H.; Hur, J. H.; Yin, H. X.; Park, Y.; Yoo, I. K.; Park, J.-B.; Park, B. H.

    2007-08-01

    The effects of Ni and Ni0.83Pt0.17 alloy electrodes on the resistance switching of the dc-sputtered polycrystalline NiO thin films were investigated. The initial off-state resistances of the films were similar to that of Pt /NiO/Pt film. However, after the first cycle of switching, the off-state resistance significantly decreased in the films with Ni in the electrode. It can be attributed to the migration of Ni from electrodes to the NiO films. The improvement in data dispersion of switching parameters is explained in terms of the decrease of the effective thickness of the films resulting from the migration of Ni.

  16. Radioanalytical studies of fallout 63Ni.

    PubMed

    Holm, E; Roos, P; Skwarzec, B

    1992-01-01

    Fallout of Nickel-63 (T1/2 = 100 a) produced in small amounts at nuclear weapon tests following the neutron activation of weapon construction material was investigated by studying carpets of lichen collected during 1961 to 1988 at the Lake Rogen district in central Sweden (62.3 degrees N, 12.4 degrees E). The maximal level of 63Ni in the lichen carpet, which occurred in 1964, was about 0.6 Bq kg-1, dry weight, and decreased to 0.1 Bq kg-1 in 1988. The deposition pattern for 63Ni was similar to other fallout radionuclides such as 137Cs, 90Sr and 239 + 240Pu. The concentrations of stable Ni were relatively constant at 0.5 to 1.0 microgram g-1 throughout the years resulting in, for example, a specific activity (63Ni/stable Ni) of 0.5 Bq mg-1 in 1964 and 0.1 Bq mg-1 in 1988. The total area content of 63Ni was estimated to be 1.0 Bq m-2 and the activity ratio 63Ni/60Co was estimated to be 0.03 in 1966. The Chernobyl accident in April 1986 did not significantly increase the levels of 63Ni. For the measurement of these extremely low-levels of 63Ni, 200 g of dry material (about 1 kg fresh) were ashed and leached with aqua regia after hydroxides had been precipitated with ammonia, leaving Ni in the aqueous phase. Nickel was extracted as a dimethylglyoxime complex by chloroform and back-extracted with HCl. Finally, Ni was electroplated onto copper discs from an ammonium sulfate medium at high pH. The radiochemical yield was determined by atomic absorption spectrometry of stable Ni before and after electrodeposition.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1310303

  17. Microstructure and superelasticity of NiS/TiNi composite electrode

    NASA Astrophysics Data System (ADS)

    Kim, Han-seong; Cho, Gyu-bong; Kim, Ki-won; Cho, Kwon-koo; Liu, Yinong; Nam, Tae-hyun

    2007-07-01

    Surface Ni sulfides layers were formed on the surface of a Ti-50.0Ni alloy by reacting sulfur and Ni film deposited on the alloy, and then microstructures, transformation behavior, shape memory characteristics, superelasticity and electrochemical properties of a Ti-50.0Ni(at%) alloy with the sulfides were investigated. When Ni film deposited on a Ti-50.0Ni alloy was annealed under the sulfur pressure of 100 kPa at 623 K, sulfides layers consisted of NiS and NiS 1.97 were formed. When annealing was made at 648 K annealing with annealing time less than 0.9 ks, sulfides layers consisted of NiS and NiS 1.97 were formed also, while only NiS 1.97 was formed when it was made for 1.8 ks. When annealing was made at 673 K annealing with annealing time longer than 0.9 ks, only NiS 1.97 was formed. A Ti- 50.0Ni(at%) alloy with surface NiS 1.97 layer showed the two-stage B2-R-B19' transformation behavior, the perfect shape memory effect and a partial superelasticity with a superelastic recovery ratio of 78 %. NiS 1.97 cathode showed a clear discharge behavior with multi voltage plateaus. Discharge capacity of NiS 1.97 cathode decreased abruptly with increasing number of cycles up to 3, above which it decreased gradually.

  18. Composite Ni/NiO-Cr2O3 Catalyst for Alkaline Hydrogen Evolution Reaction

    SciTech Connect

    Bates, MK; Jia, QY; Ramaswamy, N; Allen, RJ; Mukerjee, S

    2015-03-12

    We report a Ni-Cr/C electrocatalyst with unpreeedented massactivity for the hydrogen evolution reaction (HER). in alkaline electrolyte. The HER Oietics of numerous binary and ternary Ni-alloys and composite Ni/metal-euride/C samples were evaluated in aquebus 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni-Cr materials which exhibit metallic Ni as well as NiOx and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to munerous binary dor ternary Ni-alloys, inCluding Ni Mg materials. It is likely that at adjacent Ni/NiOx sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a, sink for the H-ads, intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiO content and that the Cr2O3 appears to stabilize the composite NiO component-under HER conditions (where NiOx would typically be reduced to metallic Ni-0). Furthermore, in contrast to Pt, the Ni(O-x)/Cr2O3 catalyst appears resistant to poisoning by the anion.exchange ionomer (AEI), a serloua consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a: detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI.

  19. DFT study of the water gas shift reaction on Ni(111), Ni(100) and Ni(110) surfaces

    NASA Astrophysics Data System (ADS)

    Mohsenzadeh, Abas; Richards, Tobias; Bolton, Kim

    2016-02-01

    Density functional theory (DFT) calculations were used to study the water gas shift (WGS) reaction on Ni(111), Ni(100) and Ni(110) surfaces. The adsorption energy for ten species involved in the reaction together with activation barriers and reaction energies for the nine most important elementary steps were determined using the same model and DFT methods. The results reveal that these energies are sensitive to the surface structure. In spite of this, the WGS reaction occurs mainly via the direct (also referred to as redox) pathway with the CO + O → CO2 reaction as the rate determining step on all three surfaces. The activation barrier obtained for this rate limiting step decreases in the order Ni(110) > Ni(111) > Ni(100). Therefore, if O species are present on the surfaces then the WGS reaction is fastest on the Ni(100) surface. However, the barrier for desorption of H2O (which is the source of the O species) is lower than its dissociation reaction on the Ni(111) and Ni(100) surfaces, but not on the Ni(110) surface. Hence, at low H2O(g) pressures, the direct pathway on the Ni(110) surface will dominate and will be the rate limiting step. The calculations also show that the reason that the WGS reaction does not primarily occur via the formate pathway is that this species is a stable intermediate on all surfaces. The reactions studied here support the Brønsted-Evans-Polanyi (BEP) principles with an R2 value of 0.99.

  20. Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

    NASA Astrophysics Data System (ADS)

    Ohmi, Tatsuya; Mizuma, Kiminori; Matsuura, Kiyotaka; Iguchi, Manabu

    2008-02-01

    A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen.

  1. Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

    SciTech Connect

    Ohmi, Tatsuya; Matsuura, Kiyotaka; Iguchi, Manabu; Mizuma, Kiminori

    2008-02-15

    A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen.

  2. Porous NiTi shape memory alloys produced by SHS: microstructure and biocompatibility in comparison with Ti2Ni and TiNi3.

    PubMed

    Bassani, Paola; Panseri, Silvia; Ruffini, Andrea; Montesi, Monica; Ghetti, Martina; Zanotti, Claudio; Tampieri, Anna; Tuissi, Ausonio

    2014-10-01

    Shape memory alloys based on NiTi have found their main applications in manufacturing of new biomedical devices mainly in surgery tools, stents and orthopedics. Porous NiTi can exhibit an engineering elastic modulus comparable to that of cortical bone (12-17 GPa). This condition, combined with proper pore size, allows good osteointegration. Open cells porous NiTi was produced by self propagating high temperature synthesis (SHS), starting from Ni and Ti mixed powders. The main NiTi phase is formed during SHS together with other Ni-Ti compounds. The biocompatibility of such material was investigated by single culture experiment and ionic release on small specimen. In particular, NiTi and porous NiTi were evaluated together with elemental Ti and Ni reference metals and the two intermetallic TiNi3, Ti2Ni phases. This approach permitted to clearly identify the influence of secondary phases in porous NiTi materials and relation with Ni-ion release. The results indicated, apart the well-known high toxicity of Ni, also toxicity of TiNi3, whilst phases with higher Ti content showed high biocompatibility. A slightly reduced biocompatibility of porous NiTi was ascribed to combined effect of TiNi3 presence and topography that requires higher effort for the cells to adapt to the surface. PMID:24928669

  3. Cyclic and isothermal oxidation behavior at 1100 and 1200 C of Ni-20Cr, Ni-20Cr-3Mn, Ni-20Cr-3Si, and Ni-40Cr alloys

    NASA Technical Reports Server (NTRS)

    Lowell, C. E.

    1973-01-01

    Alloys of Ni-20Cr, Ni-20Cr-3Mn, Ni-20Cr-3Si, and Ni-40Cr were cyclically oxidized at 1100 and 1200 C for up to 100 hours. Oxidation behavior was judged by sample thickness and weight change, metallography, diffraction, and microprobe analysis. The least attacked were Ni-40Cr and Ni-20Cr-3Si. The alloy Ni-20Cr-3Mn was much less attacked than Ni-20Cr, but more than the other alloys. The formation of Cr2O3 accounted for the increased resistance of Ni-Cr and Ni-20Cr-3Si, and the formation of MnCr2O4 accounts for the improvement in Ni-20Cr-3mn over Ni-20Cr.

  4. Swift observations of ASASSN-15ni

    NASA Astrophysics Data System (ADS)

    Campana, S.

    2015-07-01

    Swift observed ASASSN-15ni (Dong et al. 2015, Atel #7850) starting on 2015-07-29 01:13:07.00 UT for 2.0 ks. The XRT detected one source coincident with the optical position of ASASSN-15ni at a rate of (1.4+/-0.3) x 10^-2 counts s^-1.

  5. Who is El Niño?

    NASA Astrophysics Data System (ADS)

    Philander, S. George

    It is a curious story, about a phenomenon we first welcomed as a blessing but now view with dismay, if not horror [Philander, 1998]. We named it El Niño for the child Jesus, provided it with relatives—La Niña and ENSO—and are devoting innumerable studies to the description and idealization of this family. These scriptures provide such a broad spectrum of historical, cultural, and scientific perspectives that there is now confusion about the identity of El Niño. Trenberth [1997] summarizes the situation as follows.The atmospheric component tied to El Niño is termed the “Southern Oscillation.” Scientists often call the phenomenon where the atmosphere and ocean collaborate ENSO, short for El Niño-Southern Oscillation. El Niño then corresponds to the warm phase of ENSO. The opposite “La Niña” (“the girl” in Spanish) phase consists of a basinwide cooling of the tropical Pacific and thus the cold phase of ENSO. However, for the public, the term for the whole phenomenon is “El Niño.”

  6. AF Ni-Cd cell qualification program

    NASA Technical Reports Server (NTRS)

    Hall, Steve; Brown, Harry; Collins, G.; Hwang, Warren

    1994-01-01

    The present status of the USAF NiCd cell qualification program, which is underway at the Naval Surface Warfare Center-Crane Division, is summarized. The following topics are discussed: overview; background; purpose; stress tests; results for super Ni-Cd; results for SAFT cells; GPS stress test; GPS simulated orbit; and results for gates cells. The discussion is presented in viewgraph format.

  7. Ion scattering experiment on Ni(110) surface

    SciTech Connect

    Nicholas, B.; Rambabu, B.; Collins, W.E.

    1986-01-01

    Light emission from excited neutral scattered Ne and sputtered Ni were investigated using the LEIS method. A 5-keV Ne/sup +/ beam was used to bombard a Ni(110) surface. Results of the light emission data is presented and compared with neutral production of Ne. 4 refs., 3 figs.

  8. Formation of dioxins on NiO and NiCl2 at different oxygen concentrations.

    PubMed

    Yang, Jie; Yan, Mi; Li, Xiaodong; Lu, Shengyong; Chen, Tong; Yan, Jianhua; Olie, Kees; Buekens, Alfons

    2015-08-01

    Model fly ash (MFA) containing activated carbon (AC) as source of carbon, NaCl as source of chlorine and either NiO or NiCl2 as de novo catalyst, was heated for 1h at 350 °C in a carrier gas flow composed of N2 containing 0, 6, 10, and 21 vol.% O2, to study the formation of PCDD/Fs (dioxins) and its dependence on oxygen. The formation of PCDD/Fs with NiCl2 was stronger by about two orders of magnitude than with NiO and the difference augmented with rising oxygen concentration. The thermodynamics of the NiO-NiCl2 system were represented, X-ray absorption near edge structural (XANES) spectroscopy allowed to probe the state of oxidation of the nickel catalyst in the MFA and individual metal species were distinguished using the LCF (Linear combination fitting) technique: thus three supplemental nickel compounds (Ni2O3, Ni(OH)2, and Ni) were found in the fly ash. Principal Component Analysis (PCA) indicates that both Ni2O3 and NiCl2 probably played an important role in the formation of PCDD/Fs. PMID:25951618

  9. Preparation and characterization of Ni-P/Ni3.1B composite alloy coatings

    NASA Astrophysics Data System (ADS)

    Wang, Yurong; He, Jiawei; Wang, Wenchang; Shi, Jianhua; Mitsuzaki, Naotoshi; Chen, Zhidong

    2014-02-01

    The preparation of Ni-P/Ni3.1B composite alloy coating on the surface of copper was achieved by co-deposition of Ni3.1B nanoparticles with Ni-P coating during electroless plating. Ni-P-B alloy coating was obtained by heat-treating the as-plated Ni-P/Ni3.1B composite coating. The effect of the concentration of sodium alginate, borax, thiourea, Ni3.1B, temperature, and pH value on the deposition rate and B content were investigated and determined to be: 30 g L-1, 10 g L-1, 2 mg L-1, 20 mg L-1, 70 °C and 9.0 , respectively. Sodium alginate and thiourea were played as surfactant for coating Ni3.1B nanoparticles and stabilizer for the plating bath, respectively. Ni-P/Ni3.1B composite coating had good performance such as corrosion resistance and solderability.

  10. Water dissociation on Ni(100) and Ni(111): Effect of surface temperature on reactivity

    SciTech Connect

    Seenivasan, H.; Tiwari, Ashwani K.

    2013-11-07

    Water adsorption and dissociation on Ni(100) and Ni(111) surfaces are studied using density functional theory calculations. Water adsorbs on top site on both the surfaces, while H and OH adsorb on four fold hollow and three fold hollow (fcc) sites on Ni(100) and Ni(111), respectively. Transition states (TS) on both surfaces are identified using climbing image-nudged elastic band method. It is found that the barrier to dissociation on Ni(100) surface is slightly lower than that on Ni(111) surface. Dissociation on both the surfaces is exothermic, while the exothermicity on Ni(100) is large. To study the effect of lattice motion on the energy barrier, TS calculations are performed for various values of Q (lattice atom coordinate along the surface normal) and the change in the barrier height and position is determined. Calculations show that the energy barrier to reaction decreases with increasing Q and increases with decreasing Q on both the surfaces. Dissociation probability values at different surface temperatures are computed using semi-classical approximation. Results show that the influence of surface temperature on dissociation probability on the Ni(100) is significantly larger compared to that of Ni(111). Moreover, on Ni(100), a dramatic shift in energy barrier to lower incident energy values is observed with increasing surface temperature, while the shift is smaller in the case of Ni(111)

  11. Predictability of the Ningaloo Niño/Niña.

    PubMed

    Doi, Takeshi; Behera, Swadhin K; Yamagata, Toshio

    2013-01-01

    The seasonal prediction of the coastal oceanic warm event off West Australia, recently named the Ningaloo Niño, is explored by use of a state-of-the-art ocean-atmosphere coupled general circulation model. The Ningaloo Niño/Niña, which generally matures in austral summer, is found to be predictable two seasons ahead. In particular, the unprecedented extreme warm event in February 2011 was successfully predicted 9 months in advance. The successful prediction of the Ningaloo Niño is mainly due to the high prediction skill of La Niña in the Pacific. However, the model deficiency to underestimate its early evolution and peak amplitude needs to be improved. Since the Ningaloo Niño/Niña has potential impacts on regional societies and industries through extreme events, the present success of its prediction may encourage development of its early warning system. PMID:24100593

  12. Electrochemical properties of NiO-Ni nanocomposite as anode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, X. H.; Tu, J. P.; Zhang, B.; Zhang, C. Q.; Li, Y.; Yuan, Y. F.; Wu, H. M.

    NiO-Ni nanocomposite was prepared by calcining a mixture of Ni 2(OH) 2CO 3 and ethanol in a tube furnace at 700 °C for 45 min in air. The microstructure and morphology of the powders were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). In the composite, nanoscale Ni particles (<10 nm) were dispersed in the NiO matrix (about 100 nm). Electrochemical tests showed that the nanocomposite had higher initial and reversible capacity than pure NiO. The presence of the nanoscale Ni phase had improved both of the initial coulombic efficiency and the cycling performance, due to its catalytic activity, which would facilitate the decomposition of Li 2O and the SEI during the charge process.

  13. A ternary Ni-Al-W EAM potential for Ni-based single crystal superalloys

    NASA Astrophysics Data System (ADS)

    Fan, Qin-Na; Wang, Chong-Yu; Yu, Tao; Du, Jun-Ping

    2015-01-01

    Based on experiments and first-principles calculations, a ternary Ni-Al-W embedded-atom-method (EAM) potential is constructed for the Ni-based single crystal superalloys. The potential predicts that W atoms do not tend to form clusters in γ(Ni), which is consistent with experiments. The impurity diffusion of W in γ(Ni) is investigated using the five-frequency model. The diffusion coefficients and the diffusion activation energy of W are in reasonable agreement with the data in literatures. By W doping, the lattice misfit between the two phases decreases and the elastic constants of γ‧(Ni3Al) increase. As for alloyed elements Co, Re and W, the pinning effect of solute atom on the γ(Ni)/γ‧(Ni3Al) misfit dislocation increases with the increasing of the atomic radius.

  14. Direct observation of infinite NiO2 planes in LaNiO2 films

    NASA Astrophysics Data System (ADS)

    Ikeda, Ai; Krockenberger, Yoshiharu; Irie, Hiroshi; Naito, Michio; Yamamoto, Hideki

    2016-06-01

    Epitaxial thin films of LaNiO2, which is an oxygen-deficient perovskite with “infinite layers” of Ni1+O2, were prepared by a low-temperature reduction of LaNiO3 single-crystal films on NdGaO3 substrates. We report the high-angle annular dark-field and bright-field scanning transmission electron microscopy observations of infinite NiO2 planes of c-axis-oriented LaNiO2 epitaxial thin films with a layer stacking sequence of NiO2/La/NiO2. Resistivity measurements on the films show T 2 dependence between 400 and 150 K and a negative Hall coefficient.

  15. Nanoscale structural heterogeneity in Ni-rich half-Heusler TiNiSn

    SciTech Connect

    Douglas, Jason E. Pollock, Tresa M.; Chater, Philip A.; Brown, Craig M.; Seshadri, Ram

    2014-10-28

    The structural implications of excess Ni in the TiNiSn half-Heusler compound are examined through a combination of synchrotron x-ray and neutron scattering studies, in conjunction with first principles density functional theory calculations on supercells. Despite the phase diagram suggesting that TiNiSn is a line compound with no solid solution, for small x in TiNi{sub 1+x}Sn there is indeed an appearance—from careful analysis of the scattering—of some solubility, with the excess Ni occupying the interstitial tetrahedral site in the half-Heusler structure. The analysis performed here would point to the excess Ni not being statistically distributed, but rather occurring as coherent nanoclusters. First principles calculations of energetics, carried out using supercells, support a scenario of Ni interstitials clustering, rather than a statistical distribution.

  16. Capture of Hydrogen Using ZrNi

    NASA Technical Reports Server (NTRS)

    Patton, Lisa; Wales, Joshua; Lynch, David; Parrish, Clyde

    2005-01-01

    Water, as ice, is thought to reside in craters at the lunar poles along with CH4 and H2 . A proposed robotic mission for 2012 will utilize metal/metal hydrides for H2 recovery. Specifications are 99% capture of H2 initially at 5 bar and 100C (or greater), and degassing completely at 300C. Of 47-systems examined using the van't Hoff equation, 4 systems, Mg/MgH2, Mg2Ni/Mg2NiH4, ZrNi/ZrNiH2.8, and Pd/PdH0.77, were considered likely candidates for further examination. It is essential, when selecting a system, to also examine questions regarding activation, kinetics, cyclic stability, and gas impurity effects. After considering those issues, ZrN1 was selected as the most promising candidate, as it is easily activated and rapidly forms ZrNiH 2.8 . In addition, it resists oxide poisoning by CO2, and H2O, while some oxidation by O2 is recommended for improved activation . The presence of hydrogen in the as received Zr-Ni alloy from Alfa Aesar posed additional technical problems. X-ray diffraction of the Zr-Ni powder (-325 mesh), with a Zr:Ni wt% ratio of 70:30, was found to consist of ZrH2, ZrNiH2.8, and ZrNi. ZrH2 in the alloy presented the risk that after degassing that both Zr and ZrNi would be present, and thus lead to erroneous results regarding the reactivity of ZrNi with H2 . Fortunately, ZrH2 is a highly stable hydride that does not degas H2 to any significant extent at temperatures below 300C. Based on equilibrium calculations for the decomposition of ZrH2, only 1 millionth of the hydride decomposed at 300C under a N2 atmosphere flowing at 25 ccm for 64 hours, the longest time for pretreatment employed in the investigation. It was possible, from the X-ray results and knowledge of the Zr:Ni ratio, to compute the composition of a pretreated specimen as being 76 wt% ZrNi and the balance ZrH2.

  17. Tensile deformation of NiTi wires.

    PubMed

    Gall, Ken; Tyber, Jeff; Brice, Valerie; Frick, Carl P; Maier, Hans J; Morgan, Neil

    2005-12-15

    We examine the structure and properties of cold drawn Ti-50.1 at % Ni and Ti-50.9 at % Ni shape memory alloy wires. Wires with both compositions possess a strong <111> fiber texture in the wire drawing direction, a grain size on the order of micrometers, and a high dislocation density. The more Ni rich wires contain fine second phase precipitates, while the wires with lower Ni content are relatively free of precipitates. The wire stress-strain response depends strongly on composition through operant deformation mechanisms, and cannot be explained based solely on measured differences in the transformation temperatures. We provide fundamental connections between the material structure, deformation mechanisms, and resulting stress-strain responses. The results help clarify some inconsistencies and common misconceptions in the literature. Ramifications on materials selection and design for emerging biomedical applications of NiTi shape memory alloys are discussed. PMID:16138359

  18. Charge ordering in Ni1 +/Ni2 + nickelates: La4Ni3O8 and La3Ni2O6

    NASA Astrophysics Data System (ADS)

    Botana, Antia S.; Pardo, Victor; Pickett, Warren E.; Norman, Michael R.

    2016-08-01

    Ab initio calculations allow us to establish a close connection between the Ruddlesden-Popper layered nickelates and cuprates not only in terms of filling of d levels (close to d9) but also because they show Ni1 +(S =1 /2 ) /Ni2 +(S =0 ) stripe ordering. The insulating charge-ordered ground state is obtained from a combination of structural distortions and magnetic order. The Ni2 + ions are in a low-spin configuration (S =0 ) yielding an antiferromagnetic arrangement of Ni1 + S =1 /2 ions like the long-sought spin-1/2 antiferromagnetic insulator analog of the cuprate parent materials. The analogy extends further with the main contribution to the bands near the Fermi energy coming from hybridized Ni dx2-y2 and O p states.

  19. NiAl alloys for structural uses

    NASA Technical Reports Server (NTRS)

    Koss, D. A.

    1991-01-01

    Alloys based on the intermetallic compound NiAl are of technological interest as high temperature structural alloys. These alloys possess a relatively low density, high melting temperature, good thermal conductivity, and (usually) good oxidation resistance. However, NiAl and NiAl-base alloys suffer from poor fracture resistance at low temperatures as well as inadequate creep strength at elevated temperatures. This research program explored macroalloying additions to NiAl-base alloys in order to identify possible alloying and processing routes which promote both low temperature fracture toughness and high temperature strength. Initial results from the study examined the additions of Fe, Co, and Hf on the microstructure, deformation, and fracture resistance of NiAl-based alloys. Of significance were the observations that the presence of the gamma-prime phase, based on Ni3Al, could enhance the fracture resistance if the gamma-prime were present as a continuous grain boundary film or 'necklace'; and the Ni-35Al-20Fe alloy was ductile in ribbon form despite a microstructure consisting solely of the B2 beta phase based on NiAl. The ductility inherent in the Ni-35Al-20Fe alloy was explored further in subsequent studies. Those results confirm the presence of ductility in the Ni-35Al-20Fe alloy after rapid cooling from 750 - 1000 C. However exposure at 550 C caused embrittlement; this was associated with an age-hardening reaction caused by the formation of Fe-rich precipitates. In contrast, to the Ni-35Al-20Fe alloy, exploratory research indicated that compositions in the range of Ni-35Al-12Fe retain the ordered B2 structure of NiAl, are ductile, and do not age-harden or embrittle after thermal exposure. Thus, our recent efforts have focused on the behavior of the Ni-35Al-12Fe alloy. A second parallel effort initiated in this program was to use an alternate processing technique, mechanical alloying, to improve the properties of NiAl-alloys. Mechanical alloying in the

  20. Neutron Spectroscopic factors of 56Ni

    NASA Astrophysics Data System (ADS)

    Sanetullaev, A.; Ghosh, T. K.; Lynch, W. G.; Bazin, D.; Chajecki, Z.; Coupland, Daniel; Hodges, R.; Lee, Jenny; Henzl, V.; Henzlova, D.; Rogers, A. M.; Sun, Z. Y.; Tsang, M. B.; Winkelbauer, J.; Youngs, M.; Famiano, M.; Clement, R. R. C.; Howard, M. E.; Cizewski, J. A.; O'Malley, P. D.; Manning, B.; Charity, R. J.; Charity, L. G.; Shapira, D.; Shmitt, K. T.

    2011-10-01

    The exact shell-structure of the unstable doubly-magic nucleus 56Ni has attracted a lot of interest recently. To test if 56Ni is a good core, 56Ni(p, d)55Ni transfer reactions were measured using 56Ni beam at two different energies, 37 MeV/u and 80 MeV/u, in inverse kinematics in two experiments. The second measurement was done in order to test the sensitivity of reaction cross sections and models to reaction energies. The measurements were performed at NSCL using HiRA array and S800 spectrometer. Spectroscopic factors have been extracted for the first experiment. The results show good agreement with shell-model calculations. Preliminary results of the measurements with 80 MeV/u beam will be presented as well. This work is funded by NSF under Grant No. PHY-0606007.

  1. XAFS study of Ni (II) aminovinylketone complexes

    NASA Astrophysics Data System (ADS)

    Yalovega, Galina E.; Vlasenko, Valerii G.; Uraev, Ali I.; Garnovskii, Alexander D.; Soldatov, Alexander V.

    2006-11-01

    The functional properties of the active sites in a metalloproteins depend on coordination geometry of metal, the number and the nature of coordination ligands. The Ni K-edge XAFS spectra of novel nickel complexes as models for the MeN 2O 2(S 2) active site in metalloproteins were measured and analyzed. Theoretical analysis of the Ni K-edge XANES was performed using FDMNES code based on the finite difference method (FDM) to solve the Schrödinger equation beyond muffin-tin approximations and self-consistent full multiple-scattering approach (code FEFF8.2). It was found that the spectrum is almost totally formed by the octahedron of the nearest neighbor atoms around Ni ion in the II (Ni) complex. The III (Ni) complex active center exists in square-planar configuration with shorter distances.

  2. The Ni-rich part of the Al–Ge–Ni phase diagram

    PubMed Central

    Jandl, Isabella; Reichmann, Thomas L.; Richter, Klaus W.

    2013-01-01

    The Ni-rich part of the ternary system Al–Ge–Ni (xNi > 50 at.%) was investigated by means of optical microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM). The two isothermal sections at 550 °C and 700 °C were determined. Within these two sections a new ternary phase, designated as τ4, AlyGe9−yNi13±x (hP66, Ga3Ge6Ni13-type) was detected and investigated by single crystal X-ray diffraction. Another ternary low temperature phase, τ5, was found only in the isothermal section at 550 °C around the composition AlGeNi4. This compound was found to crystallise in the Co2Si type structure (oP12, Pnma). The structure was identified by Rietveld refinement of powder data. The NiAs type (B8) phase based on binary Ge3Ni5 revealed an extended solid solubility of Al and the two isotypic compounds AlNi3 and GeNi3 form a complete solid solution. Based on DTA results, six vertical sections at 55, 60, 70, 75 and 80 at.% Ni and at a constant Al:Ni ratio of 1:3 were constructed. Furthermore, the liquidus surface projection and the reaction scheme (Scheil diagram) were completed by combining our results with previous results from the Ni-poor part of the phase diagram. Six invariant ternary reactions were identified in the Ni-rich part of the system. PMID:27087754

  3. Preferred orientation relationships with large misfit interfaces between Ni{sub 3}Sn{sub 4} and Ni in reactive wetting of eutectic SnPb on Ni

    SciTech Connect

    Suh, J. O.; Tu, K. N.; Wu, Albert T.; Tamura, N.

    2011-06-15

    Ni{sub 3}Sn{sub 4} grains were formed on Ni by reactive wetting between molten eutectic SnPb and thermally annealed Ni foil. Using synchrotron white beam micro x-ray diffraction analysis, two kinds of preferred orientation relationships between Ni{sub 3}Sn{sub 4} and Ni were found. The existence of preferred orientation with large interfacial misfit is suggested as a general mechanism of intermetallic compound formation in reactive solder wetting on metals.

  4. Microstructure of Ni-Al powder and Ni-Al composite coatings prepared by twin-wire arc spraying

    NASA Astrophysics Data System (ADS)

    Wang, Ji-xiao; Wang, Gui-xian; Liu, Jing-shun; Zhang, Lun-yong; Wang, Wei; Li, Ze; Wang, Qi-xiang; Sun, Jian-fei

    2016-07-01

    Ni-Al powder and Ni-Al composite coatings were fabricated by twin-wire arc spraying (TWAS). The microstructures of Ni-5wt%Al powder and Ni-20wt%Al powder were characterized by scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS). The results showed that the obtained particle size ranged from 5 to 50 μm. The morphology of the Ni-Al powder showed that molten particles were composed of Ni solid solution, NiAl, Ni3Al, Al2O3, and NiO. The Ni-Al phase and a small amount of Al2O3 particles changed the composition of the coating. The microstructures of the twin-wire-arc-sprayed Ni-Al composite coatings were characterized by SEM, EDS, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the main phase of the Ni-5wt%Al coating consisted of Ni solid solution and NiAl in addition to a small amount of Al2O3. The main phase of the Ni-20wt%Al coating mainly consisted of Ni solid solution, NiAl, and Ni3Al in addition to a small amount of Al and Al2O3, and NiAl and Ni3Al intermetallic compounds effectively further improved the final wear property of the coatings. TEM analysis indicated that fine spherical NiAl3 precipitates and a Ni-Al-O amorphous phase formed in the matrix of the Ni solid solution in the original state.

  5. Enthalpy of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys

    SciTech Connect

    Witusiewicz, V.T.; Sommer, F.

    2000-04-01

    Since the Al-Cu-Ni-Zr system is a basis for the production of bulk amorphous materials by rapid solidification techniques from the liquid state, it is of great scientific interest to determine the partial and the integral thermodynamic functions of liquid and undercooled liquid alloys. Such data, as was pointed out previously, are important in order to understand their extremely good glass-forming ability in multicomponent metallic systems as well as for processing improvements. In order to measure the thermodynamic properties of the Al-Cu-Ni-Zr quaternary, it is necessary to have reliable thermochemical data for its constituent canaries and ternaries first. In a series of articles, the authors have reported in detail the thermodynamic properties of liquid Al-Cu, Al-Ni, Cu-Ni, Cu-Zr, Al-Zr, Al-Cu-Ni, and Al-Cu-Zr alloys. This article deals with the direct calorimetric measurements of the partial and the integral enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys and the heat capacity of liquid Ni{sub 26}Zr{sub 74}. In a subsequent article, the authors will present similar data for the liquid ternary Al-Ni-Zr and for the liquid quaternary Al-Cu-Ni-Zr alloys.

  6. Composite Ni/NiO-Cr2O3 Catalyst for Alkaline Hydrogen Evolution Reaction

    PubMed Central

    Bates, Michael K.; Jia, Qingying; Ramaswamy, Nagappan; Allen, Robert J.; Mukerjee, Sanjeev

    2015-01-01

    We report a Ni–Cr/C electrocatalyst with unprecedented mass-activity for the hydrogen evolution reaction (HER) in alkaline electrolyte. The HER kinetics of numerous binary and ternary Ni-alloys and composite Ni/metal-oxide/C samples were evaluated in aqueous 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni–Cr materials which exhibit metallic Ni as well as NiOx and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to numerous binary and ternary Ni-alloys, including Ni–Mo materials. It is likely that at adjacent Ni/NiOx sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a sink for the Hads intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiOx content and that the Cr2O3 appears to stabilize the composite NiOx component under HER conditions (where NiOx would typically be reduced to metallic Ni0). Furthermore, in contrast to Pt, the Ni(Ox)/Cr2O3 catalyst appears resistant to poisoning by the anion exchange ionomer (AEI), a serious consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI. PMID:26191118

  7. Silicide formation process of Pt added Ni at low temperature: Control of NiSi2 formation

    NASA Astrophysics Data System (ADS)

    Ikarashi, Nobuyuki; Masuzaki, Koji

    2011-03-01

    Transmission electron microscopy (TEM) and ab initio calculations revealed that the Ni-Si reaction around 300 °C is significantly changed by adding Pt to Ni. TEM analysis clarified that NiSi2 was formed in a reaction between Ni thin film (˜1 nm) and Si substrate, while NiSi was formed when Pt was added to the Ni film. We also found that the Ni-adamantane structure, which acts as a precursor for NiSi2 formation around the reaction temperature, was formed in the former reaction but was significantly suppressed in the latter reaction. Theoretical calculations indicated that Pt addition increased stress at the Ni-adamantane structure/Si-substrate interface. The increase in interface stress caused by Pt addition should raise the interface energy to suppress the Ni-adamantane structure formation, leading to NiSi2 formation being suppressed.

  8. Shape coexistence in and near 68Ni

    NASA Astrophysics Data System (ADS)

    Suchyta, Scott

    2015-10-01

    The nuclei in the vicinity of 68Ni have been the subject of considerable experimental and theoretical work focused on studying the evolution of nuclear structure. Situated at the Z = 28 proton shell closure and the fragile N = 40 subshell closure, 68Ni is an important nucleus to understand as a progression is made from stable to increasingly exotic nuclei. The nature and decay of the first excited state in 68Ni has been thoroughly investigated in recent years. The first excited state has a spin and parity of 0+, can be described by the excitation of neutrons across the N = 40 gap, and has been interpreted as a moderately oblate-deformed state that coexists with the spherical ground state. A second low-energy excited 0+ state is also known to exist in 68Ni. Based on comparisons with theoretical calculations, the second excited 0+ state has been proposed to be strongly prolate deformed and based primarily on the excitation of protons across the Z = 28 gap, leading to the inference that three different 0+ states with three distinct shapes coexist below 3 MeV in 68Ni. Additional studies suggest that shape coexistence is not unique to 68Ni in this neutron-rich region near Z = 28. For instance, in the neighboring even-even isotope 70Ni, theory predicts that a prolate-deformed minimum in the potential energy surface occurs at even lower energy than in 68Ni, and experimental evidence is consistent with the theoretical prediction. The results of recent experiments studying shape coexistence in the region, particularly investigations of 68,70Ni, will be presented and theoretical interpretations will be discussed.

  9. NiPt silicide agglomeration accompanied by stress relaxation in NiSi(010) ∥ Si(001) grains

    NASA Astrophysics Data System (ADS)

    Mizuo, Mariko; Yamaguchi, Tadashi; Pagès, Xavier; Vanormelingen, Koen; Smits, Martin; Granneman, Ernst; Fujisawa, Masahiko; Hattori, Nobuyoshi

    2015-04-01

    Pt-doped Ni (NiPt) silicide agglomeration in terms of NiSi crystal orientation, Pt segregation at the NiSi/Si interface, and residual stress is studied for the first time. In the annealing of Ni monosilicide (NiSi), the growth of NiSi grains whose NiSi b-axes are aligned normal to Si(001) [NiSi(010) ∥ Si(001)] with increasing Pt segregation at the NiSi/Si interface owing to a high annealing temperature was observed. The residual stress in NiSi(010) ∥ Si(001) grains also increases with increasing annealing temperature. Furthermore, the recrystallization of NiSi(010) ∥ Si(001) grains with increasing residual stress continues through additional annealing after NiSi formation. After the annealing of NiSi(010) ∥ Si(001) grains with their strain at approximately 2%, the start of NiPt silicide agglomerates accompanied by stress relaxation was observed. This preferential recrystallization of NiSi(010) ∥ Si(001) grains with increasing residual stress is considered to enhance the NiPt silicide agglomeration.

  10. Nickel Release, ROS Generation and Toxicity of Ni and NiO Micro- and Nanoparticles

    PubMed Central

    Hedberg, Jonas; Di Bucchianico, Sebastiano; Möller, Lennart; Odnevall Wallinder, Inger; Elihn, Karine; Karlsson, Hanna L.

    2016-01-01

    Occupational exposure to airborne nickel is associated with an elevated risk for respiratory tract diseases including lung cancer. Therefore, the increased production of Ni-containing nanoparticles necessitates a thorough assessment of their physical, chemical, as well as toxicological properties. The aim of this study was to investigate and compare the characteristics of nickel metal (Ni) and nickel oxide (NiO) particles with a focus on Ni release, reactive oxygen species (ROS) generation, cellular uptake, cytotoxicity and genotoxicity. Four Ni-containing particles of both nano-size (Ni-n and NiO-n) and micron-size (Ni-m1 and Ni-m2) were tested. The released amount of Ni in solution was notably higher in artificial lysosomal fluid (e.g. 80–100 wt% for metallic Ni) than in cell medium after 24h (ca. 1–3 wt% for all particles). Each of the particles was taken up by the cells within 4 h and they remained in the cells to a high extent after 24 h post-incubation. Thus, the high dissolution in ALF appeared not to reflect the particle dissolution in the cells. Ni-m1 showed the most pronounced effect on cell viability after 48 h (alamar blue assay) whereas all particles showed increased cytotoxicity in the highest doses (20–40 μg cm2) when assessed by colony forming efficiency (CFE). Interestingly an increased CFE, suggesting higher proliferation, was observed for all particles in low doses (0.1 or 1 μg cm-2). Ni-m1 and NiO-n were the most potent in causing acellular ROS and DNA damage. However, no intracellular ROS was detected for any of the particles. Taken together, micron-sized Ni (Ni-m1) was more reactive and toxic compared to the nano-sized Ni. Furthermore, this study underlines that the low dose effect in terms of increased proliferation observed for all particles should be further investigated in future studies. PMID:27434640

  11. Ni{sub 3}Al aluminide alloys

    SciTech Connect

    Liu, C.T.

    1993-10-01

    This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

  12. Binary Ni-Nb bulk metallic glasses

    SciTech Connect

    Xia, L.; Li, W.H.; Fang, S.S.; Wei, B.C.; Dong, Y.D.

    2006-01-15

    We studied the glass forming ability of Ni-Nb binary alloys and found that some of the alloys can be prepared into bulk metallic glasses by a conventional Cu-mold casting. The best glass former within the compositional range studied is off-eutectic Ni{sub 62}Nb{sub 38} alloy, which is markedly different from those predicted by the multicomponent and deep eutectic rules. The glass formation mechanism for binary Ni-Nb alloys was studied from the thermodynamic point of view and a parameter {gamma}* was proposed to approach the ability of glass formation against crystallization.

  13. Utilization of Active Ni to Fabricate Pt-Ni Nanoframe/NiAl Layered Double Hydroxide Multifunctional Catalyst through In Situ Precipitation.

    PubMed

    Ren, Fumin; Wang, Zheng; Luo, Liangfeng; Lu, Haiyuan; Zhou, Gang; Huang, Weixin; Hong, Xun; Wu, Yuen; Li, Yadong

    2015-09-14

    Integration of different active sites into metallic catalysts, which may impart new properties and functionalities, is desirable yet challenging. Herein, a novel dealloying strategy is demonstrated to decorate nickel-aluminum layered double hydroxide (NiAl-LDH) onto a Pt-Ni alloy surface. The incorporation of chemical etching of Pt-Ni alloy and in situ precipitation of LDH are studied by joint experimental and theoretical efforts. The initial Ni-rich Pt-Ni octahedra transform by interior erosion into Pt3 Ni nanoframes with enlarged surface areas. Furthermore, owing to the basic active sites of the decorated LDH together with the metallic sites of Pt3 Ni, the resulting Pt-Ni nanoframe/NiAl-LDH composites exhibit excellent catalytic activity and selectivity in the dehydrogenation of benzylamine and hydrogenation of furfural. PMID:26241390

  14. Accessing Ni(III)-Thiolate Versus Ni(II)-Thiyl Bonding in a Family of Ni–N2S2 Synthetic Models of NiSOD

    PubMed Central

    Broering, Ellen P.; Dillon, Stephanie; Gale, Eric M.; Steiner, Ramsey A.; Telser, Joshua; Brunold, Thomas C.; Harrop, Todd C.

    2015-01-01

    Superoxide dismutase (SOD) catalyzes the disproportionation of superoxide (O2• −) into H2O2 and O2(g) by toggling through different oxidation states of a first-row transition metal ion at its active site. Ni-containing SODs (NiSODs) are a distinct class of this family of metalloenzymes due to the unusual coordination sphere that is comprised of mixed N/S-ligands from peptide-N and cysteine-S donor atoms. A central goal of our research is to understand the factors that govern reactive oxygen species (ROS) stability of the Ni–S(Cys) bond in NiSOD utilizing a synthetic model approach. In light of the reactivity of metal-coordinated thiolates to ROS, several hypotheses have been proffered and include the coordination of His1-Nδ to the Ni(II) and Ni(III) forms of NiSOD, as well as hydrogen bonding or full protonation of a coordinated S(Cys). In this work, we present NiSOD analogues of the general formula [Ni(N2S)(SR′)]−, providing a variable location (SR′ = aryl thiolate) in the N2S2 basal plane coordination sphere where we have introduced o-amino and/or electron-withdrawing groups to intercept an oxidized Ni species. The synthesis, structure, and properties of the NiSOD model complexes (Et4N)[Ni(nmp)(SPh-o-NH2)] (2), (Et4N)[Ni(nmp)(SPh-o-NH2-p-CF3)] (3), (Et4N)[Ni(nmp)(SPh-p-NH2)] (4), and (Et4N)[Ni(nmp)(SPh-p-CF3)] (5) (nmp2− = dianion of N-(2-mercaptoethyl)picolinamide) are reported. NiSOD model complexes with amino groups positioned ortho to the aryl-S in SR′ (2 and 3) afford oxidized species (2ox and 3ox) that are best described as a resonance hybrid between Ni(III)-SR and Ni(II)-•SR based on ultraviolet–visible (UV-vis), magnetic circular dichroism (MCD), and electron paramagnetic resonance (EPR) spectroscopies, as well as density functional theory (DFT) calculations. The results presented here, demonstrating the high percentage of S(3p) character in the highest occupied molecular orbital (HOMO) of the four-coordinate reduced form of NiSOD (Ni

  15. Synthesis of Ni-poor NiO nanoparticles for p-DSSC applications

    NASA Astrophysics Data System (ADS)

    Polteau, Baptiste; Tessier, Franck; Cheviré, François; Cario, Laurent; Odobel, Fabrice; Jobic, Stéphane

    2016-04-01

    To improve the performances of p-Dye Sensitized Solar Cell (p-DSSC) for the future, the synthesis of modified p-type nickel oxide semiconductor, commonly used as photocathode in such devices, was initiated with Ni3O2(OH)4 as precursor. This specific nickel oxyhydroxide was first characterized by X-ray photo-electron spectroscopy and magnetic susceptibility measurements. Then its thermal decomposition was thoroughly studied in order to control the particles size of the as-prepared NiO nanopowders. Low temperature decomposition in air of this precursor allows the formation of Ni1-xO nanoparticles with a large amount of Ni vacancies and specific surface areas up to 250 m2 g-1. Its ammonolysis at 250 °C leads to nanostructured N-doped NiO (NiO:N) materials.

  16. Enhanced broadband near-infrared luminescence from Ni in Bi/Ni-doped transparent glass ceramics

    NASA Astrophysics Data System (ADS)

    Wu, Botao; Ruan, Jian; Qiu, Jianrong; Zeng, Heping

    2009-07-01

    Spectral properties of Bi/Ni-doped transparent MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics (GCs) containing spinel solution nanocrystals were investigated. The emission intensity of Ni in Bi/Ni-doped GCs was about 4 times stronger than that of Ni-doped GCs due to energy transfer from Bi to Ni. The Bi/Ni-doped GCs with 0.75 mol% Bi2O3 concentration exhibited a near-infrared emission with full width at half maximum of about 270 nm and a fluorescent lifetime of about 350 µs, making them very promising for applications in broadband optical amplifiers and tunable lasers.

  17. Phase stability and magnetism in NiPt and NiPd alloys

    NASA Astrophysics Data System (ADS)

    Paudyal, Durga; Mookerjee, Abhijit

    2004-08-01

    We show that the differences in stability of 3d-5d NiPt and 3d-4d NiPd alloys arise mainly due to relativistic corrections. The magnetic properties of disordered NiPd and NiPt alloys also differ due to these corrections, which lead to increase in the separation between the s-d bands of 5d elements in these alloys. For the magnetic case we also analyse the results in terms of splitting of majority and minority spin d band centres of the 3d elements. We further examine the effect of relativistic corrections to the pair energies and order-disorder transition temperatures in these alloys. The magnetic moments and Curie temperatures have also been studied along with the short range ordering/segregation effects in NiPt/NiPd alloys.

  18. NiCo-lead zirconium titanate-NiCo trilayered magnetoelectric composites prepared by electroless deposition

    SciTech Connect

    Zhou, M. H.; Wang, Y. G.; Bi, K.; Fan, H. P.; Zhao, Z. S.

    2015-04-15

    The NiCo layers with various Ni/Co atomic ratio have been successfully electroless deposited on PZT layers by varying the bath composition. As the cobalt atomic ratio in the deposited layer increases from 17.2 to 54.8 wt%, the magnetostrictive coefficient decreases. The magnetoelectric effect depends strongly on the magnetostrictive properties of magnetostrictive phase. The magnetoelectric coefficient of NiCo/PZT/NiCo trilayers increases with Ni/Co atomic ratio of the deposited NiCo layers increasing from 45:55 to 83:17. A maximum ME voltage coefficient of α{sub E,31} = 2.8 V ⋅ cm{sup −1} ⋅ Oe{sup −1} is obtained at a frequency of about 88 kHz, which makes these trilayers suitable for applications in actuators, transducers and sensors.

  19. The self-discharge of the NiOOH/Ni(OH)2 electrode constant potential study

    NASA Technical Reports Server (NTRS)

    Mao, Z.; White, R. E.

    1992-01-01

    Hydrogen oxidation currents at a NiOOH/Ni(OH)2 electrode were measured directly at constant potentials for various hydrogen pressures and states of charge. It was found that the hydrogen oxidation current is linearly proportional to the hydrogen pressure at all electrode potentials and that the logarithm of the anodic current is a linear function of electrode potential. It was also found that hydrogen oxidation on the nickel substrate material was strongly inhibited by the presence of nickel hydroxide on the substrate surface. By comparing the currents for hydrogen oxidation and oxygen evolution on the NiOOH/Ni(OH)2 electrode and a nickel substrate, it is suggested that the self-discharge of the NiOOH/Ni(OH)2 electrode is mainly due to electrochemical oxidation of hydrogen on the active electrode material.

  20. Optical absorption of Ni2+ and Ni3+ ions in gadolinium gallium garnet epitaxial films

    NASA Astrophysics Data System (ADS)

    Vasileva, N. V.; Gerus, P. A.; Sokolov, V. O.; Plotnichenko, V. G.

    2012-12-01

    Single-crystal Ni-doped gadolinium gallium garnet films were grown for the first time from supercooled Bi2O3-B2O3-based melt solutions by liquid-phase epitaxy. Optical absorption bands due to Ni2+, Ni3+ and Bi3+ ions were observed in those films. Interpretation and tabulation of all absorption bands of nickel ions occupying octahedral and tetrahedral sites in the garnet lattice are presented.

  1. Growth of nanotubular oxide layer on Ti-Ni alloys with different Ni contents

    NASA Astrophysics Data System (ADS)

    Kim, Min-Su; Tsuchiya, Hiroaki; Fujimoto, Shinji

    2016-04-01

    Anodization of near-equiatomic Ti-Ni alloys was performed in an ethylene glycol based electrolyte under various conditions in order to investigate the effects of crystal structure and chemical composition of the Ti-Ni alloy on the morphology of the resulting oxide layers. X-ray diffraction patterns revealed that Ti-Ni substrates with Ni content lower than 50.0 at.% were in the martensitic phase, while substrates with Ni content higher than 50.0 at.% were in the austenitic phase. Oxide layers formed at 20 or 35 V for 5 min exhibited no distinct nanotubular structures; however, at 50 V, nanotubular oxide layers were formed. After anodization at 50 V for 20 min, the growth of an irregular-shaped porous layer underneath the nanotubular oxide layer was observed for Ti-Ni alloys with Ni content lower than 52.2 at.%, whereas the oxide layer consisted of only irregular-shaped porous structures for the Ti-52.5 at.% Ni alloy. Further anodization resulted in the formation of irregular-shaped porous oxide layers on all Ti-Ni alloys examined. Energy-dispersive X-ray analysis indicated that this morphological transition is related to Ni accumulation in the vicinity of the interface between the bottoms of the oxide layers and the surfaces of the substrate alloys. Therefore, nanotubular oxide layers cannot be grown, and instead irregular-shaped porous oxide layers are formed underneath the nanotubular layers. These results indicate that the morphology of anodic oxide layers formed on the near-equiatomic Ti-Ni alloys is not affected by their crystal structure, but by Ni content and anodization time.

  2. Pressure dependence on the remanent magnetization of Fe-Ni alloys and Ni metal

    NASA Astrophysics Data System (ADS)

    Wei, Qingguo; Gilder, Stuart Alan; Maier, Bernd

    2014-10-01

    We measured the acquisition of magnetic remanence of iron-nickel alloys (Fe64Ni36, Fe58Ni42, and Fe50Ni50) and pure Ni under pressures up to 23 GPa at room temperature. Magnetization decreases markedly for Fe64Ni36 between 5 and 7 GPa yet remains ferromagnetic until at least 16 GPa. Magnetization rises by a factor of 2-3 for the other compositions during compression to the highest applied pressures. Immediately upon decompression, magnetic remanence increases for all Fe-Ni alloys while magnetic coercivity remains fairly constant at relatively low values (5-20 mT). The amount of magnetization gained upon complete decompression correlates with the maximum pressure experienced by the sample. Martensitic effects best explain the increase in remanence rather than grain-size reduction, as the creation of single domain sized grains would raise the coercivity. The magnetic remanence of low Ni Invar alloys increases faster with pressure than for other body-centered-cubic compositions due to the higher magnetostriction of the low Ni Invar metals. Thermal demagnetization spectra of Fe64Ni36 measured after pressure release broaden as a function of peak pressure, with a systematic decrease in Curie temperature. Irreversible strain accumulation from the martensitic transition likely explains the broadening of the Curie temperature spectra, consistent with our x-ray diffraction analyses.

  3. Electroslag surfacing of steel shafting with Ni alloy 625 and 70Cu-30Ni strip

    SciTech Connect

    Devletian, J.H.; Gao, Y.P.; Wood, W.E.

    1996-12-31

    A comprehensive study of electroslag surfacing (ESS) of steel with Ni Alloy 625 and 70Cu-30Ni strip electrodes was conducted to establish the feasibility of replacing forged bearing sleeves on propulsion shafting with integral weld surfacing. The base material was MIL-S-23284, Class 1 steel in the form of 41--66 cm (16--26 in.) diameter shafting and 76 mm (3 in.) thick flat plate. All ESS was carried out at a heat input level of approximately 5.9kJ/mm (150 kJ/in.) using 30 x 0.5 mm (1.2 x 0.02 in.) strip electrodes. Assessments of mechanical properties and microstructure of Ni Alloy 625 surfacing and 70Cu-30Ni surfacing were conducted to establish the structure-property relationships in these complex alloy systems. In addition, a solidification cracking test was developed to determine the relative cracking susceptibilities of these strip surfacing alloys. Although the Ni Alloy 625 surfacing contained small islands of interdendritic MC type carbides and Laves phase, the mechanical properties of this surfacing were satisfactory. The 70Cu-30Ni surfacing required a buttering layer of 30Cu-70Ni or pure Ni to prevent solidification cracking. The inherent ductility-dip sensitivity of 70Cu-30Ni surfacing was overcome by the development of a suitable ESS procedure.

  4. Anodic vacuum arc developed nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples

    SciTech Connect

    Mukherjee, S. K.; Sinha, M. K.; Pathak, B.; Rout, S. K.; Barhai, P. K.

    2009-12-01

    This paper deals with the development of nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples (TFTCs) by using ion-assisted anodic vacuum arc deposition technique. The crystallographic structure and surface morphology of individual layer films have been studied by x-ray diffraction and scanning electron microscopy, respectively. The resistivity, temperature coefficient of resistance, and thermoelectric power of as deposited and annealed films have been measured. The observed departure of these transport parameters from their respective bulk values can be understood in terms of intrinsic scattering due to enhanced crystallite boundaries. From the measured values of thermoelectric power and the corresponding temperature coefficient of resistance of annealed Cu, Ni, and Fe films, the calculated values of log derivative of the mean free path of conduction electrons at the Fermi surface with respect to energy (U) are found to be -0.51, 3.22, and -8.39, respectively. The thermoelectric response of annealed Cu-Ni and Fe-Ni TFTCs has been studied up to a maximum temperature difference of 300 deg. C. Reproducibility of TFTCs has been examined in terms of the standard deviation in thermoelectric response of 16 test samples for each pair. Cu-Ni and Fe-Ni TFTCs agree well with their wire thermocouple equivalents. The thermoelectric power values of Cu-Ni and Fe-Ni TFTCs at 300 deg. C are found to be 0.0178 and 0.0279 mV/ deg. C, respectively.

  5. Electronic transport properties of ultra-thin Ni and Ni-C nanowires.

    PubMed

    Zhang, Leining; Wu, Weikang; Zhou, Yi; Ren, Hongru; Dong, Jichen; Li, Hui

    2016-02-21

    The structures and electronic transport properties of ultra-thin Ni and Ni-C nanowires obtained from carbon nanotube (CNT) templates are theoretically investigated. C atoms tend to locate at the central positions of nanowires and are surrounded by Ni atoms. Spin polarization at the Fermi level is not responsible for the spin filtration of these nanowires. Increasing C concentration can improve the resistance of nanowires by abating the number of electronic transmission channels and the coupling of electron orbitals between Ni atoms. Moreover, with the increase of diameter, the conductance of these nanowires increases as well. This study is helpful for guiding the synthesis of nanowires with desired applications. PMID:26818090

  6. Directional Solidification and Mechanical Properties of NiAl-NiAlTa Alloys

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Chen, X. F.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1995-01-01

    Directional solidification of eutectic alloys is a promising technique for producing in-situ composite materials exhibiting a balance of properties. Consequently, the microstructure, creep strength and fracture toughness of directionally solidified NiAl-NiAlTa alloys were investigated. Directional solidification was performed by containerless processing techniques to minimize alloy contamination. The eutectic composition was found to be NiAl-15.5 at% Ta and well-aligned microstructures were produced at this composition. A near-eutectic alloy of NiAl-14.5Ta was also investigated. Directional solidification of the near-eutectic composition resulted in microstructures consisting of NiAl dendrites surrounded by aligned eutectic regions. The off-eutectic alloy exhibited promising compressive creep strengths compared to other NiAl-based intermetallics, while preliminary testing indicated that the eutectic alloy was competitive with Ni-base single crystal superalloys. The room temperature toughness of these two-phase alloys was similar to that of polycrystalline NiAl even with the presence of the brittle Laves phase NiAlTa.

  7. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    DOE PAGESBeta

    Jin, Ke; Zhang, Yanwen; Bei, Hongbin

    2016-01-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm–2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing themore » ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Here, under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.« less

  8. Modeling and simulation of NiO dissolution and Ni deposition in molten carbonate fuel cells

    SciTech Connect

    Nam, Suk Woo; Choi, Hyung-Joon; Lim, Tae Hoon

    1996-12-31

    Dissolution of NiO cathode into the electrolyte matrix is an important phenomena limiting the lifetime of molten carbonate fuel cell (MCFC). The dissolved nickel diffuses into the matrix and is reduced by dissolved hydrogen leading to the formation of metallic nickel films in the pores of the matrix. The growth of Ni films in the electrolyte matrix during the continuous cell operation results eventually in shorting between cathode and anode. Various mathematical and empirical models have been developed to describe the NiO dissolution and Ni deposition processes, and these models have some success in estimating the lifetime of MCFC by correlating the amount of Ni deposited in the matrix with shorting time. Since the exact mechanism of Ni deposition was not well understood, deposition reaction was assumed to be very fast in most of the models and the Ni deposition region was limited around a point in the matrix. In fact, formation of Ni films takes place in a rather broad region in the matrix, the location and thickness of the film depending on operating conditions as well as matrix properties. In this study, we assumed simple reaction kinetics for Ni deposition and developed a mathematical model to get the distribution of nickel in the matrix.

  9. Preparation of magnetic Ni/wollastonite and zeolite P/Ni/wollastonite composite fibers

    NASA Astrophysics Data System (ADS)

    Jiang, Jinlong; Lu, Xinyuan; Huang, Huan; Duanmu, Chuansong; Zhou, Sumin; Gu, Xu; Chen, Jing

    2012-08-01

    Magnetic composite fibers with wollastonite (WO) core and Ni shell were prepared by electroless plating using natural mineral WO fibers as supporters. Zeolite P layers were then loaded on the surface of Ni/WO fibers by in situ hydrothermal method. The sample structure and properties were characterized via SEM, XRD, SQUID, EDX, and N2 adsorption. The compact Ni-P coatings on the surface of WO fibers resulted in good magnetic properties of the Ni/WO fibers and zeolite P/Ni/WO fibers. After two crystallization cycles, a continuous zeolite P layer could be formed on the surface of Ni-P coating. The zeolite loading improved the stability of Ni-P coating in the acid solution, resulting in that the zeolite P/Ni/WO fibers can be used at a wide pH range of 3-7. Zeolite P/Ni/WO fiber exhibited a good sorption property for Cu2+ in the aqueous solution (12.48 mg/g) and could be reused after regeneration, indicating that it could be an effective and reusable adsorbent for metal ions from a liquid system.

  10. Thickness and ordering temperature of surface NiO/Ni systems

    SciTech Connect

    Shih, Ying-Ta; Su, Chien-Yu; Tsai, Chung-Wei; Pan, Wei

    2014-02-15

    We estimate the thickness and ordering temperature of an antiferromagnetic and passivation surface oxide through exchange bias coupling. The surface NiO, which is generated through the exposure of a Ni/Cu(001) surface to oxygen, is taken as a model system on which to perform the estimation. Since no exchange bias is found in the surface NiO/Ni/Cu(001), we have built a sandwich structure of NiO/n ML Ni/10 ML Co/Cu(001) to measure the n dependence of exchange bias. With n ⩽ 2, a large exchange bias field is found above 300 K, which could be due to the direct contact between the oxides and the Co layer. With 3 ⩽ n ⩽ 6, a smaller exchange bias field is found with a blocking temperature of 190 K. This implies that the thickness of NiO is, at most, 3 ML. Discovering the thickness and ordering temperature of the surface NiO provides us to explore the potential applications by using surface NiO.

  11. Tiny Ni-NiO nanocrystals with exchange bias induced room temperature ferromagnetism

    NASA Astrophysics Data System (ADS)

    Chaghouri, Hanan Al; Tuna, F.; Santhosh, P. N.; Thomas, P. John

    2016-03-01

    Ni nanocrystals coated with a thin layer of NiO with a diameter of 5.0 nm show exchange bias induced ferromagnetism at room temperature. These particulates are freely dispersible in water and were obtained by annealing Ni nanoparticles coated with a thin amorphous layer of NiO. Particulates with diameters between 5.0 and 16.8 nm are studied. Detailed magnetic measurements reveal signs consistent with strong exchange bias including elevated blocking temperatures and tangible loop shifts. The structure of the particulates are characterized by high resolution transmission electron microscopy, energy dispersive x-ray analysis and x-ray diffraction.

  12. Complex band structure with ultrasoft pseudopotentials: fcc Ni and Ni nanowire

    NASA Astrophysics Data System (ADS)

    Smogunov, Alexander; Dal Corso, Andrea; Tosatti, Erio

    2003-06-01

    We generalize to magnetic transition metals the approach proposed by Choi and Ihm for calculating the complex band structure of periodic systems, a key ingredient for future calculations of conductivity of an open quantum system within the Landauer-Buttiker theory. The method is implemented with ultrasoft pseudopotentials and plane wave basis set in a DFT-LSDA ab initio scheme. As a first example, we present the complex band structure of bulk fcc Ni (which constitutes the tips of a Ni nanocontact) and monatomic Ni wire (the junction between two tips). Based on our results, we anticipate some features of the spin-dependent conductance in a Ni nanocontact.

  13. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    SciTech Connect

    Jin, Ke; Zhang, Yanwen; Bei, Hongbin

    2016-01-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm–2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing the ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Here, under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.

  14. Ion irradiation induced defect evolution in Ni and Ni-based FCC equiatomic binary alloys

    NASA Astrophysics Data System (ADS)

    Jin, K.; Bei, H.; Zhang, Y.

    2016-04-01

    In order to explore the chemical effects on radiation response of alloys with multi-principal elements, defect evolution under Au ion irradiation was investigated in the elemental Ni, equiatomic NiCo and NiFe alloys. Single crystals were successfully grown in an optical floating zone furnace and their (100) surfaces were irradiated with 3 MeV Au ions at fluences ranging from 1 × 1013 to 5 × 1015 ions cm-2 at room temperature. The irradiation-induced defect evolution was analyzed by using ion channeling technique. Experiment shows that NiFe is more irradiation-resistant than NiCo and pure Ni at low fluences. With continuously increasing the ion fluences, damage level is eventually saturated for all materials but at different dose levels. The saturation level in pure Ni appears at relatively lower irradiation fluence than the alloys, suggesting that damage accumulation slows down in the alloys. Under high-fluence irradiations, pure Ni has wider damage ranges than the alloys, indicating that defects in pure Ni have high mobility.

  15. Giant magnetoresistance in evaporated NiFe/Cu and NiFeCo/Cu multilayers (abstract)

    NASA Astrophysics Data System (ADS)

    Zeltser, A. M.; Smith, Neil

    1996-04-01

    The magnetic and transport properties of electron beam evaporated (Ni83Fe17/Cu)10 and (Ni66Fe16Co18/Cu)10 multilayers (ML) were studied as a function of the Cu spacer and magnetic layer thicknesses (tCu and tNiFe), annealing conditions and Ta buffer layer thickness. The ML were evaporated in a magnetic field at deposition rates ˜ 2 Å/s and background pressure <5×10-8 mbar on Si/SiO2 substrates at Ts=200 °C. These ML exhibited two unique features: (1) ΔR/R and the interlayer coupling did not show oscillatory behavior as a function of tCu; and (2) after magnetic post annealing, ΔR/R increased from <0.3% in the as-deposited state, to up to ˜6% and 7% in Ta/(NiFe/Cu) and (NiFeCo/Cu), respectively. The coupling between the NiFe layers changed from ferromagnetic in the as-deposited state Mr/Ms˜0.9k;20 to essentially antiferromagnetic Mr/Ms<0.2) after appropriate annealing, and the ML became virtually isotropic in-plane. This is quite different from strong oscillatory behavior of giant magnetoresistance (GMR) previously reported in (NiFe/Cu) as-deposited ML made by ion-beam sputtering. After annealing at 300° and 325 °C for 2 h, the ΔR/R became ˜4.5% and ˜6.5% in (NiFe/Cu) and (NiFeCo/Cu) ML, respectively, and remained approximately constant for tCu=20 to 40 Å. The coupling field generally decreased with an increase in Cu and NiFe and after annealing at 300 °C dropped to as low as ˜25 and 45 Oe in (NiFe/Cu) and (NiFeCo/Cu) ML, respectively. The of ΔR/R Ta/(NiFe/Cu) ML increased with the thickness of Ta buffer layer from 30 to 70 Å. The high-angle θ-2θ x-ray scans of (NiFe/Cu) ML showed (111) texture, essentially independent of annealing temperature. The low-angle x-ray diffraction did not reveal roughening of the Cu-NiFe interfaces as a result of annealing. In many respects the GMR behavior of these ML is similar to that reported in sputtered ``discontinuous'' NiFe/Ag. However, in contrast to the latter, the resistivity of NiFe/Cu monotonically

  16. Single Particle States in ^56Ni

    NASA Astrophysics Data System (ADS)

    Sanetullaev, Alisher; Lynch, W. G.; Tsang, M. B.; Bazin, D.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Lee, Jenny; Rogers, A. M.; Signoracci, A.; Sun, Z. Y.; Youngs, M.; Famiano, M.; Hudan, S.; O'Malley, P.; Peters, W. A.; Schmitt, K.; Shapira, D.; Charity, R. J.; Sobotka, L. G.

    2010-11-01

    Neutron spectroscopic factor of ^56Ni using (p, d) neutron transfer reaction has been measured using 37 MeV/u ^56Ni beam in inverse kinematics. The measurement was performed at NSCL using the high resolution silicon array, HiRA, to detect the deuterons in coincidence with the recoil residues detected in the S800 spectrometer. To test if ^56Ni is a good core, the most direct way is to measure the single particle nature of the neutrons or protons in the f7/2 orbits. Direct measurements of the spectroscopic factors of the neutron hole state in ^56Ni using the pickup (p,d) reaction will determine if the neutron f7/2 orbit is indeed a closed shell. In present work, preliminary experimental results will be presented.

  17. Preparation of C/Ni-NiO composite nanofibers for anode materials in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Luo, Chenghao; Lu, Weili; Li, Yu; Feng, Yiyu; Feng, Wei; Zhao, Yunhui; Yuan, Xiaoyan

    2013-11-01

    Carbon nanofibers (CNFs) embedded with various amounts of Ni and NiO nanoparticles (C/Ni-NiO) were prepared by electrospinning of polyacrylonitrile (PAN), followed by heat treatment. The structure and composition of the obtained C/Ni-NiO composite nanofibers were analyzed by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results suggested that the morphology, nanofiber diameter, and the content of the Ni-NiO nanoparticles in the CNFs were controlled by different amounts of nickel acetate added into the PAN. The electrochemical measurements of a charge/discharge experiment and a cyclic voltammetry test indicated that the content and the size of Ni-NiO nanoparticles embedded in the CNFs had a great influence on the electrochemical performance of lithium-ion batteries. CNFs embedded with a certain content of Ni-NiO nanoparticles as binder-free anodes for rechargeable lithium-ion batteries exhibited improved electrochemical performance, including high reversible capacities, good capacity retention, and stable cycling performance. This is mainly ascribed to the formation of a well-distributed Ni-NiO nanoparticle structure and the buffering role of the carbon nanofiber matrix, together with the high theoretical capacity of NiO and the increase in electrode connectivity caused by the formation of electrochemically inactive Ni nanoparticles.

  18. Increasing foliar Zn:Ni or Cu:Ni concentration ratios increase severity of nickel deficiency symptoms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of essential micronutrients on the endogenous bioavailability of Ni is unknown. This study examines the linkage between Ni deficiency and endogenous foliar concentration of Ni, Zn, and Cu. It was hypothesized that expression of morphological symptoms of Ni deficiency by pecan [Carya i...

  19. Magnetic properties of ordered NiPt

    NASA Astrophysics Data System (ADS)

    Brommer, P. E.; Franse, J. J. M.

    1988-04-01

    Thermal expansion, forced volume magnetostriction and high magnetic field data are presented on the ordered equiatomic NiPt compound. Values are derived for the magnetovolume parameter κC (≃3 × 10 -6kg2A-2m-4), and for the electronic and lattice Grüneisen parameters (Γ e ≊ 5.6; Γ latt ≊ 2.5) . Ordering effects on the magnetoelastic properties are studied for alloys containing 40-60 at % Ni.

  20. Effects of Ni content on the shape memory properties and microstructure of Ni-rich NiTi-20Hf alloys

    NASA Astrophysics Data System (ADS)

    Saghaian, S. M.; Karaca, H. E.; Tobe, H.; Pons, J.; Santamarta, R.; Chumlyakov, Y. I.; Noebe, R. D.

    2016-09-01

    Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti29.3Hf20, Ni51.2Ti28.8Hf20, and Ni52Ti28Hf20 (at.%)) were systematically characterized in the furnace cooled condition. H-phase precipitates were formed during furnace cooling in compositions with greater than 50.3Ni and the driving force for nucleation increased with Ni content. Alloy strength increased while recoverable strain decreased with increasing Ni content due to changes in precipitate characteristics. When the precipitates were small (∼5–15 nm), they were readily absorbed by martensite plates, which resulted in maximum recoverable strain of 2% in Ni50.7Ti29.3Hf20. With increasing Ni content, the size (>100 nm) and volume fraction of precipitates increased and the growth of martensite plates was constrained between the precipitates when the Ni concentration was greater than 50.7 at.%. Near perfect dimensional stability with negligible irrecoverable strain was observed at stress levels as high as 2 GPa in the Ni52Ti28Hf20 alloy, though the recoverable strain was rather small. In general, strong local stress fields were created at precipitate/matrix interphases, which lead to high stored elastic energy during the martensitic transformation.

  1. The new structure type Gd3Ni7Al14.

    PubMed

    Pukas, Svitlana; Gladyshevskii, Roman

    2015-11-01

    The crystal structure of Gd3Ni7Al14 (trigadolinium heptanickel tetradecaaluminide) belongs to a family of two-layer structures and can be described as an assembly of interpenetrating centred straight prisms. For the Ni atoms, trigonal prisms (Al4Gd2 and Al6) are observed, the Al atoms are inside tetragonal (Ni2Al2Gd4, Ni2Al4Gd2, Al4Gd4, Ni4Al4 and Al8) and pentagonal (Ni4Al6 and Al10) prisms, while the Gd atoms are at the centres of pentagonal (Ni4Al6) and hexagonal (Ni4Al8) prisms. In each case, the true coordination polyhedron is a capped prism, also including atoms from the same layer. The structural features of Gd3Ni7Al14 are similar to those of the intermetallides PrNi2Al3 and ZrNiAl. In all these structures, Ni-centred trigonal prisms form infinite columns via common triangular faces. The columns share prism edges and form a three-dimensional framework with six-membered rings in the (001) plane in the case of the PrNi2Al3 and ZrNiAl types. In the case of Gd3Ni7Al14, six-membered rings are also observed, but only two-thirds of the rings are interconnected via prism edges. PMID:26524174

  2. Methanethiol decomposition on Ni(100)

    SciTech Connect

    Castro, M.E.; Ahkter, S.; Golchet, A.; White, J.M. ); Sahin, T. )

    1991-01-01

    Static secondary ion mass spectroscopy (SSIMS), temperature programmed desorption (TPD), and Auger electron spectroscopy (AES) were used under ultrahigh vacuum conditions to study the decomposition of CH{sub 3}SH on Ni(100). Only methane, hydrogen, and the parent molecule are observed in TPD. Complete decomposition to C(a), S(a) and desorbing H{sub 2} is the preferred reaction pathway for low exposures, while desorption of methane is observed at higher coverages. Preadsorbed hydrogen promoted methane desorption. Upon adsorption, and for low coverages, SSIMS evidence indicates S-H bond cleavage into CH{sub 3}S and surface hydrogen. S-H bond cleavage is inhibited for high coverages. The TP-SSIMS data are consistent with an activated C-S bond cleavage in CH{sub 3}S, with an activation energy of 8.81 kcal/mol and preexponential factor of 10{sup 6.5}s{sup {minus}1}. The low preexponential factor is taken as indicating a complex decomposition pathway. A mechanism consistent with the observed data is discussed.

  3. Alpha Ni optical model potentials

    NASA Astrophysics Data System (ADS)

    Billah, M. M.; Abdullah, M. N. A.; Das, S. K.; Uddin, M. A.; Basak, A. K.; Reichstein, I.; Sen Gupta, H. M.; Malik, F. B.

    2005-11-01

    The present work reports the analyses of the experimental differential cross-sections of α elastic scattering on 58,60,62,64Ni, over a wide range of incident energies, in terms of four types of optical potentials, namely shallow (molecular), deep non-monotonic, squared Woods-Saxon and semi-microscopic folding. All the four potentials produce a reasonable description of the experimental data. The potential parameters, calculated from the energy density functional theory using a realistic two-nucleon interaction, resemble closely the molecular potential parameters, which produce the best description of the experimental data for the four isotopes. The volume integrals and the energy variation of the parameters indicate the effect of the shell-model structure on the potentials. The folding potentials, without any need for renormalization, are found to describe reasonably well the elastic scattering cross-section data for the four isotopes within the energy range considered. In conformity with the previous observation on Ca isotopes, the number of nucleons, 4A=49, existing in α-like clusters in the target nucleus, is the same for the four isotopes, considered herein.

  4. Improvement of Ni phytostabilization by inoculation of Ni resistant Bacillus megaterium SR28C.

    PubMed

    Rajkumar, Mani; Ma, Ying; Freitas, Helena

    2013-10-15

    The use of metal tolerant plants for the phytostabilization of metal contaminated soil is an area of extensive research and development. In this study the effects of inoculation of Ni-resistant bacterial strains on phytostabilization potential of various plants, including Brassica juncea, Luffa cylindrica and Sorghum halepense, were studied. A Ni-resistant bacterial strain SR28C was isolated from a nickel rich serpentine soil and identified as Bacillus megaterium based on the morphological features, biochemical characteristics and partial 16S rDNA sequence analysis. The strain SR28C tolerated concentrations up to 1200 mg Ni L(-1) on a Luria-Bertani (LB) agar medium. Besides, it showed high degree of resistance to various metals (Cu, Zn, Cd, Pb and Cr) and antibiotics (ampicillin, tetracycline, streptomycin, chloramphenicol, penicillin and kanamycin) tested. In addition, the strain bound considerable amounts of Ni in their resting cells. Besides, the strain exhibited the plant growth promoting traits, such as solubilization of phosphate and production of indole-3-acetic acid (IAA) in modified Pikovskayas medium and LB medium, respectively in the absence and presence of Ni. Considering such potential, the effects of SR28C on the growth and Ni accumulation of B. juncea, L. cylindrica and S. halepense, were assessed with different concentrations of Ni in soil. Inoculation of SR28C stimulated the biomass of the test plants grown in both Ni contaminated and non-contaminated soils. Further, SR28C alleviated the detrimental effects of Ni by reducing its uptake and translocation to the plants. This study suggested that the PGPB inoculant due to its intrinsic abilities of growth promotion and attenuation of the toxic effects of Ni could be exploited for phytostabilization of Ni contaminated site. PMID:23895909

  5. Peculiarities of thermoelectric half-Heusler phase formation in Gd-Ni-Sb and Lu-Ni-Sb ternary systems

    NASA Astrophysics Data System (ADS)

    Romaka, V. V.; Romaka, L.; Horyn, A.; Rogl, P.; Stadnyk, Yu; Melnychenko, N.; Orlovskyy, M.; Krayovskyy, V.

    2016-07-01

    The phase equilibria in the Gd-Ni-Sb and Lu-Ni-Sb ternary systems were studied at 873 K by X-ray and metallographic analyses in the whole concentration range. The interaction of the elements in the Gd-Ni-Sb system results the formation of five ternary compounds at investigated temperature: Gd5Ni2Sb (Mo5SiB2-type), Gd5NiSb2 (Yb5Sb3-type), GdNiSb (MgAgAs-type), Gd3Ni6Sb5 (Y3Ni6Sb5-type), and GdNi0.72Sb2 (HfCuSi2-type). At investigated temperature the Lu-Ni-Sb system is characterized by formation of the LuNiSb (MgAgAs-type), Lu5Ni2Sb (Mo5SiB2-type), and Lu5Ni0.56Sb2.44 (Yb5Sb3-type) compounds. The disordering in the crystal structure of half-Heusler GdNiSb and LuNiSb was revealed by EPMA and studied by means of Rietveld refinement and DFT modeling. The performed electronic structure calculations are in good agreement with electrical transport property studies.

  6. Processing condition for the development of cube texture in Ni and Ni alloy tapes fabricated by powder metallurgy process

    NASA Astrophysics Data System (ADS)

    Ji, Bong Ki; Lee, Dong-Wook; Kim, Min-Woo; Jun, Byung-Hyuk; Park, Pyeong Yeal; Jung, Kyu-Dong; Kim, Chan-Joong

    2004-10-01

    Bi-axially textured Ni, Ni-W (1, 3 and 5 at.%) and Ni-Cu alloy tapes for YBCO coated conductors were fabricated by powder metallurgy process including powder compaction, cold isostatic pressing, cold rolling and recrystallization heat treatment. The rod-like Ni and Ni alloy compacts were sintered at 1100 °C for 6 h in 96% Ar-4% H 2 atmosphere. The sintered Ni and Ni-W rods were successfully cold-rolled into thin tapes of 80-100 μm thickness with 5% reduction at each path, but the Ni-Cu alloy rods with Cu content less than 20 at.% were made into tapes. The Ni and Ni alloy tapes were heat-treated at 800-1200 °C for the development of cube texture. The good (2 0 0) texture was obtained for both Ni and Ni-W alloy tapes, while it was obtained only for the Ni-Cu tapes with low Cu contents. The W and Cu addition to Ni improved the mechanical properties by solid solution hardening. Critical current density ( Jc) of YBCO film deposited on the CeO 2/YSZ/CeO 2(CYC)/Ni template was 0.25 MA/cm 2 at 77 K and self-field.

  7. Spontaneous formation of superconducting NiBi3 phase in Ni-Bi bilayer films

    NASA Astrophysics Data System (ADS)

    Siva, Vantari; Senapati, Kartik; Satpati, Biswarup; Prusty, Sudakshina; Avasthi, D. K.; Kanjilal, D.; Sahoo, Pratap K.

    2015-02-01

    We report the spontaneous formation of superconducting NiBi3 phase in thermally evaporated Ni-Bi bilayer films. High reaction-diffusion coefficient of Bi is believed to drive the formation of NiBi3 during the deposition of Bi on the Ni film. Cross sectional transmission electron microscopy and glancing incidence X-ray depth profiling confirmed the presence of NiBi3 throughout the top Bi layer. Superconducting transition at ˜3.9 K, close to the bulk value, was confirmed by transport and magnetization measurements. The bilayers were irradiated with varying fluence of 100 MeV Au ions to study the robustness of superconducting order in presence of large concentration of defects. Superconducting parameters of NiBi3, such as transition temperature and upper critical field, remained unchanged upto an ion dose of 1 × 1014 ions/cm2. The diffusive formation of NiBi3 in Ni opens the possibility of studying superconducting proximity effect at a truly clean superconductor-ferromagnet interface.

  8. Evaporative segregation in 80% Ni-20% Cr and 60% Fe-40% Ni alloys

    NASA Technical Reports Server (NTRS)

    Gupta, K. P.; Mukherjee, J. L.; Li, C. H.

    1974-01-01

    An analytical approach is outlined to calculate the evaporative segregation behavior in metallic alloys. The theoretical predictions are based on a 'normal' evaporation model and have been examined for Fe-Ni and Ni-Cr alloys. A fairly good agreement has been found between the predicted values and the experimental results found in the literature.

  9. Electronic circuits having NiAl and Ni.sub.3 Al substrates

    DOEpatents

    Deevi, Seetharama C.; Sikka, Vinod K.

    1999-01-01

    An electronic circuit component having improved mechanical properties and thermal conductivity comprises NiAl and/or Ni.sub.3 Al, upon which an alumina layer is formed prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  10. Spontaneous formation of superconducting NiBi{sub 3} phase in Ni-Bi bilayer films

    SciTech Connect

    Siva, Vantari; Senapati, Kartik Prusty, Sudakshina; Sahoo, Pratap K.; Satpati, Biswarup

    2015-02-28

    We report the spontaneous formation of superconducting NiBi{sub 3} phase in thermally evaporated Ni-Bi bilayer films. High reaction-diffusion coefficient of Bi is believed to drive the formation of NiBi{sub 3} during the deposition of Bi on the Ni film. Cross sectional transmission electron microscopy and glancing incidence X-ray depth profiling confirmed the presence of NiBi{sub 3} throughout the top Bi layer. Superconducting transition at ∼3.9 K, close to the bulk value, was confirmed by transport and magnetization measurements. The bilayers were irradiated with varying fluence of 100 MeV Au ions to study the robustness of superconducting order in presence of large concentration of defects. Superconducting parameters of NiBi{sub 3}, such as transition temperature and upper critical field, remained unchanged upto an ion dose of 1 × 10{sup 14} ions/cm{sup 2}. The diffusive formation of NiBi{sub 3} in Ni opens the possibility of studying superconducting proximity effect at a truly clean superconductor-ferromagnet interface.

  11. Photosensitivity of the Ni-A state of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F with visible light

    SciTech Connect

    Osuka, Hisao; Shomura, Yasuhito; Komori, Hirofumi; Shibata, Naoki; Nagao, Satoshi; Higuchi, Yoshiki; Hirota, Shun

    2013-01-04

    Highlights: Black-Right-Pointing-Pointer Ni-A state of [NiFe] hydrogenase showed light sensitivity. Black-Right-Pointing-Pointer New FT-IR bands were observed with light irradiation of the Ni-A state. Black-Right-Pointing-Pointer EPR g-values of the Ni-A state shifted upon light irradiation. Black-Right-Pointing-Pointer The light-induced state converted back to the Ni-A state under the dark condition. -- Abstract: [NiFe] hydrogenase catalyzes reversible oxidation of molecular hydrogen. Its active site is constructed of a hetero dinuclear Ni-Fe complex, and the oxidation state of the Ni ion changes according to the redox state of the enzyme. We found that the Ni-A state (an inactive unready, oxidized state) of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F (DvMF) is light sensitive and forms a new state (Ni-AL) with irradiation of visible light. The Fourier transform infrared (FT-IR) bands at 1956, 2084 and 2094 cm{sup -1} of the Ni-A state shifted to 1971, 2086 and 2098 cm{sup -1} in the Ni-AL state. The g-values of g{sub x} = 2.30, g{sub y} = 2.23 and g{sub z} = 2.01 for the signals in the electron paramagnetic resonance (EPR) spectrum of the Ni-A state at room temperature varied for -0.009, +0.012 and +0.010, respectively, upon light irradiation. The light-induced Ni-AL state converted back immediately to the Ni-A state under dark condition at room temperature. These results show that the coordination structure of the Fe site of the Ni-A state of [NiFe] hydrogenase is perturbed significantly by light irradiation with relatively small coordination change at the Ni site.

  12. First-principles studies of Al-Ni intermetallic compounds

    SciTech Connect

    Shi Dongmin; Wen Bin; Melnik, Roderick; Yao Shan; Li Tingju

    2009-10-15

    The structural properties, heats of formation, elastic properties, and electronic structures of Al-Ni intermetallic compounds are analyzed here in detail by using density functional theory. Higher calculated absolute values of heats of formation indicate a very strong chemical interaction between Al and Ni for all Al-Ni intermetallic compounds. According to the computational single crystal elastic constants, all the Al-Ni intermetallic compounds considered here are mechanically stable. The polycrystalline elastic modulus and Poisson's ratio have been deduced by using Voigt, Reuss, and Hill (VRH) approximations, and the calculated ratio of shear modulus to bulk modulus indicated that AlNi, Al{sub 3}Ni, AlNi{sub 3} and Al{sub 3}Ni{sub 5} compounds are ductile materials, but Al{sub 4}Ni{sub 3} and Al{sub 3}Ni{sub 2} are brittle materials. With increasing Ni concentration, the bulk modulus of Al-Ni intermetallic compounds increases in a linear manner. The electronic energy band structures confirm that all Al-Ni intermetallic compounds are conductors. - Graphical abstract: Calculated bulk modulus compared to experimental and other theoretical values for the Al-Ni intermetallic compounds.

  13. Effects of two-temperature model on cascade evolution in Ni and NiFe

    DOE PAGESBeta

    Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; Weber, William J.

    2016-07-05

    We perform molecular dynamics simulations of Ni ion cascades in Ni and equiatomic NiFe under the following conditions: (a) classical molecular dynamics (MD) simulations without consideration of electronic energy loss, (b) classical MD simulations with the electronic stopping included, and (c) using the coupled two-temperature MD (2T-MD) model that incorporates both the electronic stopping and the electron-phonon interactions. Our results indicate that the electronic e ects are more profound in the higher energy cascades and that the 2T-MD model results in a smaller amount of surviving damage and smaller defect clusters, while less damage is produced in NiFe than inmore » Ni.« less

  14. Improvement of thermoelectric properties for half-Heusler TiNiSn by interstitial Ni defects

    SciTech Connect

    Hazama, Hirofumi; Matsubara, Masato; Asahi, Ryoji; Takeuchi, Tsunehiro

    2011-09-15

    We have synthesized off-stoichiometric Ti-Ni-Sn half-Heusler thermoelectrics in order to investigate the relation between randomly distributed defects and thermoelectric properties. A small change in the composition of Ti-Ni-Sn causes a remarkable change in the thermal conductivity. An excess content of Ni realizes a low thermal conductivity of 2.93 W/mK at room temperature while keeping a high power factor. The low thermal conductivity originates in the defects generated by an excess content of Ni. To investigate the detailed defect structure, we have performed first-principles calculations and compared with x ray photoemission spectroscopy measurement. Based on these analyses, we conclude that the excess Ni atoms randomly occupy the vacant sites in the half-Heusler structure, which play as phonon scattering centers, resulting in significant improvement of the figure of merit without any substitutions of expensive heavy elements, such as Zr and Hf.

  15. Oxide Scales Formed on NiTi and NiPtTi Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Garg, Anita; Rogers, Richard B.; Noebe, Ronald D.

    2011-01-01

    Ni-49Ti and Ni-30Pt-50Ti (at.%) shape memory alloys were oxidized isothermally in air over the temperature range of 500 to 900 C. The microstructure, composition, and phase content of the scales were studied by SEM, EDS, XRD, and metallography. Extensive plan view SEM/EDS identified various features of intact or spalled scale surfaces. The outer surface of the scale was a relatively pure TiO2 rutile structure, typified by a distinct highly striated and faceted crystal morphology. Crystal size increased significantly with temperature. Spalled regions exhibited some porosity and less distinct features. More detailed information was obtained by correlation of SEM/EDS studies of 700 C/100 hr cross-sections with XRD analyses of serial or taper-polishing of plan surfaces. Overall, multiple layers exhibited graded mixtures of NiO, TiO2, NiTiO3, Ni(Ti) or Pt(Ni,Ti) metal dispersoids, Ni3Ti or Pt3Ti depletion zones, and substrate, in that order. The NiTi alloy contained a 3 at.% Fe impurity that appeared in embedded localized Fe-Ti-rich oxides, while the NiPtTi alloy contained a 2 v/o dispersion of TiC that appeared in lower layers. The oxidation kinetics of both alloys (in a previous report) indicated parabolic growth and an activation energy (250 kJ/mole) near those reported in other Ti and NiTi studies. This is generally consistent with TiO2 existing as the primary scale constituent, as described here.

  16. Tuning the magnetic properties of multisegmented Ni/Cu electrodeposited nanowires with controllable Ni lengths

    NASA Astrophysics Data System (ADS)

    Susano, M.; Proenca, M. P.; Moraes, S.; Sousa, C. T.; Araújo, J. P.

    2016-08-01

    The fabrication of segmented Ni/Cu nanowires (NWs), with tunable structural and magnetic properties, is reported. A potentiostatic electrodeposition method with a single electrolytic bath has been used to fabricate multisegmented Ni/Cu NWs inside a highly hexagonally ordered anodic nanoporous alumina membrane, with diameters of 50 nm and Ni segment lengths (L Ni) tuned from 10 nm up to 140 nm. The x-ray diffraction results evidenced a strong dependence of the Ni NWs crystallographic face-centered-cubic (fcc) texture along the [220] direction on the aspect ratio of the NWs. The magnetic behavior of the multisegmented Ni/Cu NW arrays, as a function of the magnetic field and temperature, is also studied and correlated with their structural and morphological properties. Micromagnetic simulations, together with the experimental results, showed a dominant antiferromagnetic coupling between Ni segments along the wire length for small low aspect-ratio magnetic segments. When increasing the Ni segments’ length, the magnetic interactions between these along the wire became stronger, favouring a ferromagnetic coupling. The Curie temperature of the NWs was also found to strongly depend on the Ni magnetic segment length. Particularly the Curie temperature was found to be reduced 75 K for the 20 nm Ni segments, following the finite-size scaling relation with ξ 0 = 8.1 Å and γ = 0.48. These results emphasize the advantages of using a template assisted method to electrodeposit multilayer NWs, as it allows an easy tailor of the respective morphological, chemical, structural and magnetic properties.

  17. Tuning the magnetic properties of multisegmented Ni/Cu electrodeposited nanowires with controllable Ni lengths.

    PubMed

    Susano, M; Proenca, M P; Moraes, S; Sousa, C T; Araújo, J P

    2016-08-19

    The fabrication of segmented Ni/Cu nanowires (NWs), with tunable structural and magnetic properties, is reported. A potentiostatic electrodeposition method with a single electrolytic bath has been used to fabricate multisegmented Ni/Cu NWs inside a highly hexagonally ordered anodic nanoporous alumina membrane, with diameters of 50 nm and Ni segment lengths (L Ni) tuned from 10 nm up to 140 nm. The x-ray diffraction results evidenced a strong dependence of the Ni NWs crystallographic face-centered-cubic (fcc) texture along the [220] direction on the aspect ratio of the NWs. The magnetic behavior of the multisegmented Ni/Cu NW arrays, as a function of the magnetic field and temperature, is also studied and correlated with their structural and morphological properties. Micromagnetic simulations, together with the experimental results, showed a dominant antiferromagnetic coupling between Ni segments along the wire length for small low aspect-ratio magnetic segments. When increasing the Ni segments' length, the magnetic interactions between these along the wire became stronger, favouring a ferromagnetic coupling. The Curie temperature of the NWs was also found to strongly depend on the Ni magnetic segment length. Particularly the Curie temperature was found to be reduced 75 K for the 20 nm Ni segments, following the finite-size scaling relation with ξ 0 = 8.1 Å and γ = 0.48. These results emphasize the advantages of using a template assisted method to electrodeposit multilayer NWs, as it allows an easy tailor of the respective morphological, chemical, structural and magnetic properties. PMID:27378738

  18. Generalized melting criterion for amorphization. [NiZr, NiZr[sub 2], NiTi, FeTi

    SciTech Connect

    Devanathan, R. Northwestern Univ., Evanston, IL . Dept. of Materials Science and Engineering); Lam, N.Q.; Okamoto, P.R. ); Meshii, M. . Dept. of Materials Science and Engineering)

    1992-12-01

    We present a thermodynamic model of solid-state amorphization based on a generalization of the well-known Lindemann criterion. The original Lindemann criterion proposes that melting occurs when the root-mean-square amplitude of thermal displacement exceeds a critical value. This criterion can be generalized to include solid-state amorphization by taking into account the static displacements. In an effort to verify the generalized melting criterion, we have performed molecular dynamics simulations of radiation-induced amorphization in NiZr, NiZr[sub 2], NiTi and FeTi using embedded-atom potentials. The average shear elastic constant G was calculated as a function of the total mean-square atomic displacement following random atom-exchanges and introduction of Frenkel pairs. Results provide strong support for the generalized melting criterion.

  19. Corrosion performance of bi-layer Ni/Cr2C3-NiCr HVAF thermal spray coating

    NASA Astrophysics Data System (ADS)

    Sadeghimeresht, E.; Markocsan, N.; Nylén, P.; Björklund, S.

    2016-04-01

    The corrosion behavior of three HVAF thermal spray coating systems (A: single-layer Ni, B: single-layer Cr2C3-NiCr coatings, and C: bi-layer Ni/Cr2C3-NiCr coating) was comparatively studied using immersion, salt spray, and electrochemical tests. Polarization and EIS results showed that the corrosion behavior of Cr2C3-NiCr coatings in 3.5 wt.% NaCl solution was significantly improved by adding the intermediate layer of Ni. It was illustrated that the polarization resistance of the bi-layer Ni/Cr2C3-NiCr and single-layer Cr2C3-NiCr coatings were around 194 and 38 kΩ cm2, respectively. Microstructure analysis revealed that the bond coating successfully prevented the corrosion propagation toward the coating.

  20. Low-lying excitations in 72Ni

    NASA Astrophysics Data System (ADS)

    Morales, A. I.; Benzoni, G.; Watanabe, H.; Nishimura, S.; Browne, F.; Daido, R.; Doornenbal, P.; Fang, Y.; Lorusso, G.; Patel, Z.; Rice, S.; Sinclair, L.; Söderström, P.-A.; Sumikama, T.; Wu, J.; Xu, Z. Y.; Yagi, A.; Yokoyama, R.; Baba, H.; Avigo, R.; Bello Garrote, F. L.; Blasi, N.; Bracco, A.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; de Angelis, G.; Delattre, M.-C.; Dombradi, Zs.; Gottardo, A.; Isobe, T.; Kojouharov, I.; Kurz, N.; Kuti, I.; Matsui, K.; Melon, B.; Mengoni, D.; Miyazaki, T.; Modamio-Hoyborg, V.; Momiyama, S.; Napoli, D. R.; Niikura, M.; Orlandi, R.; Sakurai, H.; Sahin, E.; Sohler, D.; Shaffner, H.; Taniuchi, R.; Taprogge, J.; Vajta, Zs.; Valiente-Dobón, J. J.; Wieland, O.; Yalcinkaya, M.

    2016-03-01

    Low-lying excited states in 72Ni have been investigated in an in-flight fission experiment at the RIBF facility of the RIKEN Nishina Center. The combination of the state-of-the-art BigRIPS and EURICA setups has allowed for a very accurate study of the β decay from 72Co to 72Ni, and has provided first experimental information on the decay sequence 72Fe→72Co→72Ni and on the delayed neutron-emission branch 73Co→72Ni . Accordingly, we report nearly 60 previously unobserved γ transitions which deexcite 21 new levels in 72Ni. Evidence for the location of the so-sought-after (42+) ,(62+) , and (81+) seniority states is provided. As well, the existence of a low-spin β -decaying isomer in odd-odd neutron-rich Co isotopes is confirmed for mass A =72 . The new experimental information is compared to simple shell-model calculations including only neutron excitations across the f p g shells. It is shown that, in general, the calculations reproduce well the observed states.

  1. Single-crystalline Ni(OH)2 and NiO nanoplatelet arrays as supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Li, Jiangtian; Zhao, Wei; Huang, Fuqiang; Manivannan, Ayyakkannu; Wu, Nianqiang

    2011-12-01

    Vertically aligned Ni(OH)2 and NiO single-crystalline nanoplatelet arrays were directly grown on the fluorine-doped tin oxide (FTO) substrate by a simple hydrothermal method. The effects of the hydrothermal parameters on the morphology and crystal structure of the nanoarray film were investigated. Controlling the ammonia and persulfate concentrations was the key to controlling the morphology of the nanoarray film. The experimental results showed that the single-crystalline NiO nanoplatelet array was a promising candidate for the supercapacitor electrode. It exhibited a high specific capacitance, prompt charge/discharge rate, and good stability of cycling performance. It is believed that the vertically oriented aligned single-crystalline NiO nanoplatelet array is beneficial to the charge transfer in the electrode and to the ion transport in the solution during redox reaction.Vertically aligned Ni(OH)2 and NiO single-crystalline nanoplatelet arrays were directly grown on the fluorine-doped tin oxide (FTO) substrate by a simple hydrothermal method. The effects of the hydrothermal parameters on the morphology and crystal structure of the nanoarray film were investigated. Controlling the ammonia and persulfate concentrations was the key to controlling the morphology of the nanoarray film. The experimental results showed that the single-crystalline NiO nanoplatelet array was a promising candidate for the supercapacitor electrode. It exhibited a high specific capacitance, prompt charge/discharge rate, and good stability of cycling performance. It is believed that the vertically oriented aligned single-crystalline NiO nanoplatelet array is beneficial to the charge transfer in the electrode and to the ion transport in the solution during redox reaction. Electronic supplementary information (ESI) available: XRD patterns of Ni(OH)2 and NiO powders; SEM and TEM images of Ni(OH)2 and NiO nanoplatelet arrays; and electrochemical performances for NiO nanoarrays and powders. See

  2. Cyclic creep and fatigue of TD-NiCr (thoria-dispersion-strengthened nickel-chromium), TD-Ni, and NiCr sheet at 1200 C

    NASA Technical Reports Server (NTRS)

    Hirschberg, M. H.; Spera, D. A.; Klima, S. J.

    1972-01-01

    The resistance of thin TD-NiCr sheet to cyclic deformation was compared with that of TD-Ni and a conventional nickel-chromium alloy. Strains were determined by a calibration technique which combines room-temperature strain gage and deflection measurements with high-temperature deflection measurements. Analyses of the cyclic tests using measured tensile and creep-rupture data indicated that the TD-NiCr and NiCr alloy specimens failed by a cyclic creep mechanism. The TD-Ni specimens, on the other hand, failed by a fatigue mechanism.

  3. First-principles studies of Ni-Ta intermetallic compounds

    SciTech Connect

    Zhou Yi; Wen Bin; Ma Yunqing; Melnik, Roderick; Liu Xingjun

    2012-03-15

    The structural properties, heats of formation, elastic properties, and electronic structures of Ni-Ta intermetallic compounds are investigated in detail based on density functional theory. Our results indicate that all Ni-Ta intermetallic compounds calculated here are mechanically stable except for P21/m-Ni{sub 3}Ta and hc-NiTa{sub 2}. Furthermore, we found that Pmmn-Ni{sub 3}Ta is the ground state stable phase of Ni{sub 3}Ta polymorphs. The polycrystalline elastic modulus has been deduced by using the Voigt-Reuss-Hill approximation. All Ni-Ta intermetallic compounds in our study, except for NiTa, are ductile materials by corresponding G/K values and poisson's ratio. The calculated heats of formation demonstrated that Ni{sub 2}Ta are thermodynamically unstable. Our results also indicated that all Ni-Ta intermetallic compounds analyzed here are conductors. The density of state demonstrated the structure stability increases with the Ta concentration. - Graphical abstract: Mechanical properties and formation heats of Ni-Ta intermetallic compounds are discussed in detail in this paper. Highlights: Black-Right-Pointing-Pointer Ni-Ta intermetallic compounds are investigated by first principle calculations. Black-Right-Pointing-Pointer P21/m-Ni{sub 3}Ta and hc-NiTa{sub 2} are mechanically unstable phases. Black-Right-Pointing-Pointer Pmmn-Ni{sub 3}Ta is ground stable phase of Ni{sub 3}Ta polymorphs. Black-Right-Pointing-Pointer All Ni-Ta intermetallic compounds are conducting materials.

  4. Transformation to Ni5Al3 in a 63.0 at. pct Ni-Al alloy

    NASA Technical Reports Server (NTRS)

    Khadkikar, P. S.; Locci, I. E.; Vedula, K.; Michal, G. M.

    1993-01-01

    Microstructures of 63 at. pct P/M Ni-Al alloys with a composition close to the stoichiometry of the Ni5Al3 phase were investigated using homogenized and quenched specimens aged at low temperatures for various times. Results of analyses of XRD data and electron microscopy observations were used for quantitative phase analysis, performed to calculate the (NiAl + Ni5Al3)/Ni5Al3 phase boundary locations. The measured lattice parameters of Ni5Al3 phase formed at 823, 873, and 923 K indicated an increase in tetragonality of the phase with increasing nickel content.

  5. [NiFeSe]-hydrogenase chemistry.

    PubMed

    Wombwell, Claire; Caputo, Christine A; Reisner, Erwin

    2015-11-17

    The development of technology for the inexpensive generation of the renewable energy vector H2 through water splitting is of immediate economic, ecological, and humanitarian interest. Recent interest in hydrogenases has been fueled by their exceptionally high catalytic rates for H2 production at a marginal overpotential, which is presently only matched by the nonscalable noble metal platinum. The mechanistic understanding of hydrogenase function guides the design of synthetic catalysts, and selection of a suitable hydrogenase enables direct applications in electro- and photocatalysis. [FeFe]-hydrogenases display excellent H2 evolution activity, but they are irreversibly damaged upon exposure to O2, which currently prevents their use in full water splitting systems. O2-tolerant [NiFe]-hydrogenases are known, but they are typically strongly biased toward H2 oxidation, while H2 production by [NiFe]-hydrogenases is often product (H2) inhibited. [NiFeSe]-hydrogenases are a subclass of [NiFe]-hydrogenases with a selenocysteine residue coordinated to the active site nickel center in place of a cysteine. They exhibit a combination of unique properties that are highly advantageous for applications in water splitting compared with other hydrogenases. They display a high H2 evolution rate with marginal inhibition by H2 and tolerance to O2. [NiFeSe]-hydrogenases are therefore one of the most active molecular H2 evolution catalysts applicable in water splitting. Herein, we summarize our recent progress in exploring the unique chemistry of [NiFeSe]-hydrogenases through biomimetic model chemistry and the chemistry with [NiFeSe]-hydrogenases in semiartificial photosynthetic systems. We gain perspective from the structural, spectroscopic, and electrochemical properties of the [NiFeSe]-hydrogenases and compare them with the chemistry of synthetic models of this hydrogenase active site. Our synthetic models give insight into the effects on the electronic properties and reactivity of

  6. Magnetic quantum diesel engine in Ni2

    NASA Astrophysics Data System (ADS)

    Dong, C. D.; Lefkidis, G.; Hübner, W.

    2013-12-01

    Quantum Diesel cycles are numerically realized using the electronic states of a Ni2 dimer. The quantum nature and the complexity of the electronic structure of the Ni2 dimer result in new features in the evolution of the pressure as well as in the heat-work transformation. The multitude of internal degrees of freedom in the isobaric process in molecules can result in crossing of the two adiabatic processes in the P-V diagram. The interplay of heat and work, originating from thermal nonequilibrium effects, can lead to a thermal efficiency of up to 100%. The spin moment of the Ni2 can be decreased by the isobaric process. To link the molecular heat capacity to easily accessible experimental quantities, we also calculate the Kerr effect and the magnetic susceptibility at different temperatures and magnetic fields.

  7. Comparative study of the performance of alumina-supported Ni-Mo, Ni-W and Ni-Mo-W catalysts in hydrotreating vacuum residue

    SciTech Connect

    Absi-Halabi, M.; Stanislaus, A.; Al-Dolama, K.

    1996-12-31

    The performance of a NiMoW/Al{sub 2}O{sub 3} catalyst for promoting various reactions during residual oil hydroprocessing is reported. Catalyst performance and properties are compared to that of conventional NiMo and NiW catalysts. Performance evaluation tests were conducted in a high pressure fixed bed reactor system using Kuwait vacuum residue as feed. Hydrodesulfurization, hydrodenitrogenation, hydrodemetalization, hydroconversion to distillates, asphaltene removal and CCR reduction reactions were monitored. The NiMoW catalyst was more active for various conversions than the NiMo and NiW catalysts. The addition of W to NiMo/Al{sub 2}O{sub 3} enhanced the hydrogenation function of the catalyst. 11 refs., 3 figs., 2 tabs.

  8. Blending Cr2O3 into a NiO-Ni electrocatalyst for sustained water splitting.

    PubMed

    Gong, Ming; Zhou, Wu; Kenney, Michael James; Kapusta, Rich; Cowley, Sam; Wu, Yingpeng; Lu, Bingan; Lin, Meng-Chang; Wang, Di-Yan; Yang, Jiang; Hwang, Bing-Joe; Dai, Hongjie

    2015-10-01

    The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2 O3 -blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2 O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2 O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20 mA cm(-2) at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. The non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells. PMID:26307213

  9. Corrosion and wear resistance study of Ni-P and Ni-P-PTFE nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Ankita, Sharma; Singh, Ajay

    2011-09-01

    This article reports on the corrosion and wear resistance of Ni-P and Ni-P-PTFE nanocomposite coatings deposited on mild steel substrates using the electroless plating technique. The coatings were characterized by scanning electron microscopy (SEM), energy dispersive analysis of X-Ray (EDAX), and X-ray diffractometry (XRD). The coatings were smooth and had thicknesses between 7 and 23 µm. They contained Ni, P, and additionally, F, in the case of the Ni-P-PTFE films. A broadening of the Ni peak in XRD was attributed to the amorphous nature and/or fine grain size of the films. Corrosion resistance was measured using immersion and electrochemical polarization tests in 3.5% NaCl solution whereas wear resistance was determined by the pin-on-disc method. Both Ni-P and Ni-P-PTFE coatings exhibited significant improvement in corrosion (in salty media) and wear behavior. Furthermore, the addition of PTFE in the coatings showed improvement in their corrosion resistance as well as a reduction in friction coefficient. Our testing revealed that the coatings' wore out following the "adhesive type" mechanism.

  10. Blending Cr2O3 into a NiO-Ni electrocatalyst for sustained water splitting

    DOE PAGESBeta

    Gong, Ming; Zhou, Wu; Kenney, Michael James; Kapusta, Rich; Cowley, Sam; Wu, Yingpeng; Lu, Bingan; Lin, Meng -Chang; Wang, Di -Yan; Yang, Jiang; et al

    2015-08-24

    The rising H2 economy demands active and durable electrocatalysts based on low-cost, earth-abundant materials for water electrolysis/photolysis. Here we report nanoscale Ni metal cores over-coated by a Cr2O3-blended NiO layer synthesized on metallic foam substrates. The Ni@NiO/Cr2O3 triphase material exhibits superior activity and stability similar to Pt for the hydrogen-evolution reaction in basic solutions. The chemically stable Cr2O3 is crucial for preventing oxidation of the Ni core, maintaining abundant NiO/Ni interfaces as catalytically active sites in the heterostructure and thus imparting high stability to the hydrogen-evolution catalyst. The highly active and stable electrocatalyst enables an alkaline electrolyzer operating at 20more » mA cm–2 at a voltage lower than 1.5 V, lasting longer than 3 weeks without decay. Thus, the non-precious metal catalysts afford a high efficiency of about 15 % for light-driven water splitting using GaAs solar cells.« less

  11. Ni3Si2 nanowires grown in situ on Ni foam for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Jiang, Yizhe; Li, Zhihui; Li, Beibei; Zhang, Jinying; Niu, Chunming

    2016-07-01

    Ni3Si2 nanowires and nanoawls have grown in situ on the surface of Ni foams by a controlled low pressure chemical vapor deposition process. Structural characterization shows that the individual Ni3Si2 nanowire is single crystal covered with a thin layer (1-2 nm) of SiO2 with a diameter of ∼20-30 nm and length of ten's micrometers. Individual nanoawl with a circular cone shape is polycrystalline. Both Ni3Si2 nanowire and nanoawl samples are evaluated as potential electrode materials for supercapacitors. The nanowire electrode delivers a very high specific capacitance and excellent rate capability. A specific capacitance of 760 F g-1 is measured at current density of 0.5 A g-1, which decreases to 518 F g-1 when the current density increases to 10 A g-1. The capacitance is dominated by pseudocapacitance with a mechanism similar to that of NiO or Ni(OH)2 widely studied in the literature. An asymmetric supercapacitor fabricated by pairing Ni3Si2 nanowire electrode with an activated carbon electrode exhibits energy densities of 17.5 Wh kg-1 and 8.8 Wh kg-1 at power densites of 301 W kg-1 and 3000 W kg-1.

  12. Giant magnetoresistance in evaporated Ni-Fe/Cu and Ni-Fe-Co/Cu multilayers

    NASA Astrophysics Data System (ADS)

    Zeltser, Alexander M.; Smith, Neil

    1996-06-01

    The magnetic and transport properties of electron-beam evaporated (Ni83Fe17/Cu)10 and (Ni66Fe16Co18/Cu)10 multilayers were studied as a function of the Cu spacer, magnetic layer and Ta buffer layer thicknesses, as well as annealing conditions. All multilayers exhibited very small giant magnetoresistance (GMR) effect (<0.3%) in the as-deposited state, however, after magnetic post-annealing at 300-325 °C, GMR increased up to 4.5%-7%, depending on the multilayer type. In contrast to sputtered Ni-Fe-(Co)/Cu multilayers, GMR showed no oscillatory behavior as a function of Cu thickness. Similar to that reported in sputtered ``discontinuous'' Ni-Fe/Ag multilayers, it is believed that Cu diffusion along the Ni-Fe-(Co) grain boundaries creates intra-layer magnetic discontinuities in Ni-Fe-(Co) layers which promote inter-layer antiferromagnetic coupling. The evaporated Ni-Fe/Cu multilayers exhibited very low remanence, exceptionally low hysteresis, and quite uniform GMR properties through the thickness of the multilayer. All of these makes them potentially attractive for application to future magnetoresistive reproduce heads for very high areal density magnetic storage systems.

  13. Ni spin switching induced by magnetic frustration in FeMn/Ni/Cu(001)

    SciTech Connect

    Wu, J.; Choi, J.; Scholl, A.; Doran, A.; Arenholz, E.; Hwang, Chanyong; Qiu, Z. Q.

    2009-03-08

    Epitaxially grown FeMn/Ni/Cu(001) films are investigated by Photoemission Electron Microscopy and Magneto-Optic Kerr Effect. We find that as the FeMn overlayer changes from paramagnetic to antiferromagnetic state, it could switch the ferromagnetic Ni spin direction from out-of-plane to in-plane direction of the film. This phenomenon reveals a new mechanism of creating magnetic anisotropy and is attributed to the out-of-plane spin frustration at the FeMn-Ni interface.

  14. Separation of radiation defects in Ni and Ni-C alloys under electron and neutron irradiation

    NASA Astrophysics Data System (ADS)

    Arbuzov, S. E.; Danilov, V. L.; Goshchitskii, B. N.; Kar'kin, A. E.; Parkhomenko, V. D.

    2016-02-01

    Complex investigations of radiation damage of Ni and Ni- 880 at. ppm C alloy under electron and neutron irradiation in the region of room temperature hardened and deformed state. In pure nickel, with the deformation microstructure, both in electron and in the neutron irradiation is observed separation of radiation-induced defects. When electron irradiation in the alloy Ni-C separation effect is observed, and when neutron irradiation there is no. This is due to the interaction of carbon atoms with radiation defects. The main sinks for radiation-induced defects are the areas with a high concentration of defects in cascades of atomic displacements.

  15. The effect of Ni:Si ratio on microstructural properties of Ni/Si ohmic contacts to SiC

    NASA Astrophysics Data System (ADS)

    Wzorek, M.; Borysiewicz, M. A.; Czerwinski, A.; Myśliwiec, M.; Ekielski, M.; Ratajczak, J.; Piotrowska, A.; Kątcki, J.

    2016-04-01

    Detailed microstructural studies were performed on Ni/Si ohmic contacts to silicon carbide in order to investigate the effect of initial Ni:Si ratio in as-deposited structures on the occurrence of characteristic defects in Ni silicide layers, such as voids, layer discontinuities, rough surface or rough interface. The chosen range of investigated Ni:Si ratios corresponded to δ-Ni2Si as a dominant phase after complete annealing sequence. Strong effect of the initial stoichiometry on the ohmic contact's microstructure was observed. The highest Ni concentration significantly lowered the temperature at which roughening of the surface and the interface occurred. The middle value of investigated concentrations resulted in the rough interface after high temperature annealing, while the lowest investigated Ni content preserved smooth interface but introduced large voids and layer discontinuities. After the first annealing step, γ-Ni31Si12 and/or δ-Ni2Si phases were detected. In the ohmic contacts (after two-step annealing sequence), beside δ-Ni2Si, the metastable, high temperature phase θ-Ni2Si was detected (also referred to as Ni3Si2·h). This phase can exist within a relatively broad range of Ni:Si stoichiometry. The stoichiometry change toward higher Si content, which occurs during high temperature annealing, was realized through this phase. Superstructures were detected in θ-Ni2Si (Ni3Si2·h) and in γ-Ni31Si12 grains. The effect of the stoichiometry change on the morphology of the Ni silicide layers is discussed.

  16. Perpendicularly magnetized spin filtering Cu/Ni multilayers

    SciTech Connect

    Shirahata, Yasuhiro; Wada, Eiji; Itoh, Mitsuru; Taniyama, Tomoyasu

    2014-01-20

    Spin filtering at perpendicular magnetized Cu/Ni multilayer/GaAs(001) interfaces is demonstrated at remanence using optical spin orientation method. [Cu(9 nm)/Ni(t{sub Ni} nm)]{sub n} multilayers are found to show a crossover from the in-plane to out-of-plane magnetic anisotropy at the Cu/Ni bilayer repetition n = 4 and the Ni layer thickness t{sub Ni} = 3. For a perpendicularly magnetized Cu/Ni multilayer/n-GaAs(001) interface, circular polarization dependent photocurrent shows a clear hysteretic behavior under optical spin orientation conditions as a function of magnetic field out-of-plane while the bias dependence exhibits a substantial peak at a forward bias, verifying that Cu/Ni multilayers work as an efficient spin filter in the remanent state.

  17. Properties of Ni/Nb magnetic/superconducting multilayers

    SciTech Connect

    Mattson, J.E.; Osgood III, R.M.; Potter, C.D.; Sowers, C.H.; Bader, S.D.

    1997-05-01

    We examine structural, magnetic, and superconducting properties of magnetic/superconducting Ni/Nb multilayers. The Ni(Nb) films are textured {l_brace}111{r_brace}({l_brace}110{r_brace}) and have smooth interfaces. The average moment of the Ni atoms in the structure drops by 80{percent} from that of bulk Ni for 19 {Angstrom} thick Ni layers in proximity to 140 {Angstrom} thick Nb layers, and goes to zero for smaller Ni thicknesses. The Nb layer is not superconducting for thicknesses {lt}100 {Angstrom} in the presence of a 19 {Angstrom} thick ferromagnetic Ni layer. The behavior of the superconducting critical temperature as a function of the superconducting layer thickness was fitted and an interfacial scattering parameter and scattering time for the paramagnetic Ni regime determined.

  18. Sonochemical preparation of nanosized amorphous Fe-Ni alloys

    NASA Astrophysics Data System (ADS)

    Shafi, K. V. P. M.; Gedanken, A.; Goldfarb, R. B.; Felner, I.

    1997-05-01

    Nanosized amorphous alloy powders of Fe20Ni80, Fe40Ni60, and Fe60Ni40 were prepared by sonochemical decomposition of solutions of volatile organic precursors, Fe(CO)5 and Ni(CO)4 in decalin, under an argon pressure of 100 to 150 kPa at 273 K. Magnetic susceptibility of Fe40Ni60 and Fe60Ni40 indicates blocking temperatures of 35 K and a magnetic particle size of about 6 nm. Thermogravimetric measurements of Fe20Ni80 give Curie temperatures of 322 °C for amorphous and 550 °C for crystallized forms. Differential scanning calorimetry exhibits an endothermic transition at 335 °C from a combination of the magnetic phase transition and alloy crystallization. The Mössbauer spectrum of crystallized Fe20Ni80 shows a sextet pattern with a hyperfine field of 25.04 T.

  19. Benchtop Delivery of Ni(cod)2 using Paraffin Capsules.

    PubMed

    Dander, Jacob E; Weires, Nicholas A; Garg, Neil K

    2016-08-01

    A facile method that allows for Ni(cod)2 to be used on the benchtop is reported. The procedure involves the preparation of paraffin-Ni(cod)2 capsules, which are stable to air and moisture. It is demonstrated that these readily available capsules can be used to promote a range of Ni(cod)2-catalyzed transformations. These studies are expected to promote the further use of Ni(cod)2 in organic synthesis. PMID:27454146

  20. Photoactivation of the Ni-SIr state to the Ni-SIa state in [NiFe] hydrogenase: FT-IR study on the light reactivity of the ready Ni-SIr state and as-isolated enzyme revisited.

    PubMed

    Tai, Hulin; Xu, Liyang; Inoue, Seiya; Nishikawa, Koji; Higuchi, Yoshiki; Hirota, Shun

    2016-08-10

    The Ni-SIr state of [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F was photoactivated to its Ni-SIa state by Ar(+) laser irradiation at 514.5 nm, whereas the Ni-SL state was light induced from a newly identified state, which was less active than any other identified state and existed in the "as-isolated" enzyme. PMID:27456760

  1. Ternary system Er-Ni-In at T=870 K

    SciTech Connect

    Dzevenko, M.; Tyvanchuk, Yu.; Bratash, L.; Zaremba, V.; Havela, L.; Kalychak, Ya.

    2011-10-15

    Isothermal section of the Er-Ni-In system at T=870 K was constructed by means of X-ray powder diffraction and EDX-analyses. Nine ternary compounds, namely ErNi{sub 9}In{sub 2} (YNi{sub 9}In{sub 2}-type), Er{sub 1-1.22}Ni{sub 4}In{sub 1-0.78} (MgCu{sub 4}Sn-type), Er{sub 10}Ni{sub 9.07}In{sub 20} (Ho{sub 10}Ni{sub 9}In{sub 20}-type), ErNi{sub 1-0.60}In{sub 1-1.40} (ZrNiAl-type), Er{sub 2}Ni{sub 2}In (Mn{sub 2}AlB{sub 2}-type), Er{sub 2}Ni{sub 1.78}In (Mo{sub 2}FeB{sub 2}-type), Er{sub 5}Ni{sub 2}In{sub 4} (Lu{sub 5}Ni{sub 2}In{sub 4}-type), Er{sub 5}Ni{sub 2}In (Mo{sub 5}SiB{sub 2}-type), and Er{sub 13.53}Ni{sub 3.14}In{sub 3.33} (Lu{sub 14}Co{sub 2}In{sub 3}-type), exist in the Er-Ni-In system at this temperature. The substitution of Ni for In was observed for ErNi{sub 1-0.60}In{sub 1-1.40} and In for Er in the case of related compounds ErNi{sub 2} and ErNi{sub 4}In. Er can enter NiIn (CoSn-type) leading to including-substitution type of compound Er{sub 0-0.12}NiIn{sub 1-0.89}. Basic magnetic properties of the Er{sub 0.04}NiIn{sub 0.97}, ErNi{sub 2}, Er{sub 0.9}Ni{sub 2}In{sub 0.1}, and ErNi{sub 4}In phases were inspected. Electrical-resistivity studies were performed on the ErNiIn, ErNi{sub 0.9}In{sub 1.1}, and ErNi{sub 4}In phases. - Graphical Abstract: Phase relations in the ternary system Er-Ni-In have been established for the isothermal section at T=870 K based on X-ray phase and EDX-analyses. Nine ternary compounds were observed. Highlights: > Isothermal section of Er-Ni-In system at T=870 K was constructed. > Nine ternary compounds were detected. > Basic magnetic properties of Er{sub 0.04}NiIn{sub 0.97} and ErNi{sub 4}In phases were inspected.

  2. Playing hide and seek with El Niño

    NASA Astrophysics Data System (ADS)

    McPhaden, M. J.

    2015-09-01

    A much-anticipated 'monster' El Niño failed to materialize in 2014, whereas an unforeseen strong El Niño is developing in 2015. El Niño continues to surprise us, despite decades of research into its causes. Natural variations most probably account for recent events, but climate change may also have played a role.

  3. Kinetics of NiO and NiCl2 hydrogen reduction as precursors and properties of produced Ni/Al2O3 and Ni-Pd/Al2O3 catalysts.

    PubMed

    Sokić, Miroslav; Kamberović, Željko; Nikolić, Vesna; Marković, Branislav; Korać, Marija; Anđić, Zoran; Gavrilovski, Milorad

    2015-01-01

    The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2 reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3 catalysts. The effect of temperature and time on NiO and NiCl2 reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2 reduction for the investigated temperature range (623-923 K) and time intervals (1-5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3 catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3 catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3 catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K. PMID:25789335

  4. Kinetics of NiO and NiCl2 Hydrogen Reduction as Precursors and Properties of Produced Ni/Al2O3 and Ni-Pd/Al2O3 Catalysts

    PubMed Central

    Sokić, Miroslav; Kamberović, Željko; Nikolić, Vesna; Marković, Branislav; Korać, Marija; Anđić, Zoran; Gavrilovski, Milorad

    2015-01-01

    The objects of this investigation were the comparative kinetic analysis of the NiO and NiCl2 reduction by hydrogen during an induction period and elimination of the calcination during the synthesis of Ni/Al2O3 catalysts. The effect of temperature and time on NiO and NiCl2 reduction degrees was studied. Avrami I equation was selected as the most favorable kinetic model and used to determine activation energy of the NiO and NiCl2 reduction for the investigated temperature range (623–923 K) and time intervals (1–5 minutes). The investigation enabled reaching conclusions about the reaction ability and rate of the reduction processes. Afterward, Ni/Al2O3 catalysts were obtained by using oxide and chloride precursor for Ni. The catalysts were supported on alumina-based foam and prepared via aerosol route. Properties of the samples before and after low-temperature hydrogen reduction (633 K) were compared. Obtained results indicated that the synthesis of Ni/Al2O3 catalysts can be more efficient if chloride precursor for Ni is directly reduced by hydrogen during the synthesis process, without the calcination step. In addition, Ni-Pd/Al2O3 catalysts with different metal content were prepared by using chloride precursors. Lower reduction temperature was utilized and the chlorides were almost completely reduced at 533 K. PMID:25789335

  5. The evolution of phase transformation in Ni/Ni3Al laminated composite under high temperature treatments

    NASA Astrophysics Data System (ADS)

    Shmorgun, V.; Gurevich, L.; Bogdanov, A.; Trunov, M.

    2016-02-01

    In this study the impact of isothermal annealing on the phase transformation rate in laminated Ni/Ni2Al3 composite was investigated. The method of nickel-aluminide coatings of the required chemical composition fabrication was proposed.

  6. Near-barrier fusion of Sn+Ni and Te+Ni Systems: Examining the influence of neutron transfer couplings

    SciTech Connect

    Liang, J Felix; Kohley, Zachary W; Shapira, Dan; Varner Jr, Robert L; Gross, Carl J; Allmond, J M; Lagergren, Karin B; Mueller, Paul Edward

    2011-01-01

    The fusion excitation functions for radioactive 132Sn+58Ni and stable 130Te+58;64Ni were measured at energies near the Coulomb barrier. The role of transfer couplings in heavy-ion fusion was examined through a comparison of Sn+Ni and Te+Ni systems, which have large variations in the number of positive Q-value nucleon transfer channels. In contrast with previous comparisons, where increased sub-barrier fusion cross sections were observed in the systems with positive Q-value neutron transfer channels, the reduced excitation functions were equivalent for the different Sn+Ni and Te+Ni systems. The present results suggest a significant change in the influence of transfer couplings on the fusion process for the Sn+Ni and Te+Ni systems.

  7. From Water Oxidation to Reduction: Transformation from Ni(x)Co(3-x)O4 Nanowires to NiCo/NiCoO(x) Heterostructures.

    PubMed

    Yan, Xiaodong; Li, KeXue; Lyu, Lu; Song, Fang; He, Jun; Niu, Dongmei; Liu, Lei; Hu, Xile; Chen, Xiaobo

    2016-02-10

    A homologous Ni-Co based nanowire catalyst pair, composed of Ni(x)Co(3-x)O4 nanowires and NiCo/NiCoO(x) nanohybrid, is developed for efficient overall water splitting. Ni(x)Co(3-x)O4 nanowires are found as a highly active oxygen evolution reaction (OER) catalyst, and they are converted into a highly active hydrogen evolution reaction (HER) catalyst through hydrogenation treatment as NiCo/NiCoO(x) heteronanostructures. An OER current density of 10 mA cm(-2) is obtained with the Ni(x)Co(3-x)O4 nanowires under an overpotential of 337 mV in 1.0 M KOH, and an HER current density of 10 mA cm(-2) is obtained with the NiCo/NiCoO(x) heteronanostructures at an overpotential of 155 mV. When integrated in an electrolyzer, these catalysts demonstrate a stable performance in water splitting. PMID:26784862

  8. TEM studies of oxidized NiAl and Ni3Al cross sections

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Ruhle, M.

    1989-01-01

    Cross sections of oxide scale/(Ni-Al) intermetallics were prepared by a new method and studied using primarily TEM. The cross sections were prepared by encasing an oxidized metal specimen sandwich in a low-melting-temperature zinc alloy. Observations of oxidized zirconium-doped beta-NiAl cross sections revealed crystallographic voids beneath an adherent Al2O3 scale. The oxide-metal interface was incoherent, but a high dislocation density in the metal near the interface suggested that a large tensile stress was induced by the attached oxide scale. A duplex Al2O3-NiAl2O4 scale formed on zirconium-doped and zirconium/boron-doped gamma-prime-Ni3Al alloys. Additional results are presented involving oxidation mechanisms and oxide-metal interface structures.

  9. Tracer diffusion of /sup 60/Co and /sup 63/Ni in amorphous NiZr alloy

    SciTech Connect

    Hoshino, K.; Averback, R.S.; Hahn, H.; Rothman, S.J.

    1987-01-01

    Tracer diffusion of /sup 60/Co and /sup 63/Ni in equiatomic amorphous NiZr alloy in the temperature range between 486 and 641/sup 0/K can be described by: D/sub Co/sup */ = 3.7 x 10/sup -7/ exp(-(135 +- 14) kJ mole/sup -1//RT) m/sup 2//sec and D/sub Ni//sup */ = 1.7 x 10/sup -7/ exp(-(140 +- 9) kJ mole/sup -1//RT) m/sup 2//sec. The values of D/sub Ni//sup */ are in reasonable agreement with those measured by the Rutherford backscattering technique. The measured diffusivities were independent of time, indicating that no relaxation took place during diffusion. 27 refs., 2 tabs.

  10. Angle-resolved spectroscopy study of Ni-based superconductor SrNi2As2

    NASA Astrophysics Data System (ADS)

    Zeng, L.-K.; Richard, P.; van Roekeghem, A.; Yin, J.-X.; Wu, S.-F.; Chen, Z. G.; Wang, N. L.; Biermann, S.; Qian, T.; Ding, H.

    2016-07-01

    We performed an angle-resolved photoemission spectroscopy study of the Ni-based superconductor SrNi2As2 . Electron and hole Fermi surface pockets are observed, but their different shapes and sizes lead to very poor nesting conditions. The experimental electronic band structure of SrNi2As2 is in good agreement with first-principles calculations after a slight renormalization (by a factor 1.1), confirming the picture of Hund's exchange-dominated electronic correlations decreasing with increasing filling of the 3 d shell in the Fe-, Co-, and Ni-based compounds. These findings emphasize the importance of Hund's coupling and 3 d -orbital filling as key tuning parameters of electronic correlations in transition-metal pnictides.

  11. Spin-glass transition in Ni carbide single crystal nanoparticles with Ni3C - type structure

    NASA Astrophysics Data System (ADS)

    Fujieda, S.; Kuboniwa, T.; Shinoda, K.; Suzuki, S.; Echigoya, J.

    2016-05-01

    Hexagonal shaped nanoparticles about 60 nm in size were successfully synthesized in tetraethylene glycol solution containing polyvinylpyrrolidone. By the analysis of the electron diffraction pattern, these were identified as a single crystal of Ni carbide with Ni3C - type structure. Their magnetization curve at 5 K was not completely saturated under a magnetic field of 5 T. The thermomagnetization curves after zero-field cooling and after field cooling exhibited the magnetic cooling effect at low temperatures. Furthermore, the 2nd order nonlinear term of AC magnetic susceptibility exhibited a negative divergence at about 17 K. It is concluded that Ni carbide single crystal nanoparticles with the Ni3C - type structure exhibit spin-glass transition at low temperatures.

  12. Synthetic Ni3S2/Ni hybrid architectures as potential contrast agents in MRI

    NASA Astrophysics Data System (ADS)

    Ma, J.; Chen, K.

    2016-04-01

    Traditional magnetic resonance imaging (MRI) contrast agents mainly include superparamagnetic (SPM) iron oxide nanoparticle as T 2 contrast agent for liver and paramagnetic Gd (III)-chelate as T 1 contrast agent for all organs. In this work, weak ferromagnetic kale-like and SPM cabbage-like Ni3S2@Ni hybrid architectures were synthesized and evaluated as potential T 1 MRI contrast agents. Their relatively small r 2/r 1 ratios of 2.59 and 2.38, and high r 1 values of 11.27 and 4.89 mmol‑1 L s‑1 (for the kale-like and cabbage-like Ni3S2@Ni, respectively) will shed some light on the development of new-type MRI contrast agents.

  13. Access to Formally Ni(I) States in a Heterobimetallic NiZn System

    PubMed Central

    Uyeda, Christopher

    2014-01-01

    Heterobimetallic NiZn complexes featuring metal centers in distinct coordination environments have been synthesized using diimine-dioxime ligands as binucleating scaffolds. A tetramethylfuran-containing ligand derivative enables a stable one-electron-reduced S = 1/2 species to be accessed using Cp2Co as a chemical reductant. The resulting pseudo-square planar complex exhibits spectroscopic and crystallographic characteristics of a ligand-centered radical bound to a Ni(II) center. Upon coordination of a π-acidic ligand such as PPh3, however, a five-coordinate Ni(I) metalloradical is formed. The electronic structures of these reduced species provide insight into the subtle effects of ligand structure on the potential and reversibility of the NiII/I couple for complexes of redox-active tetraazamacrocycles. PMID:25614786

  14. Three-Dimensional EBSD Analysis of YSZ, NiO-YSZ and Ni-Alloy

    SciTech Connect

    Saraf, Laxmikant V.

    2012-01-03

    In this report, a method is discussed to perform successive milling on yttria-stabilized zirconia (YSZ), NiO-YSZ and Ni-alloy at the intervals of 85 nm 50 nm and 100 nm, respectively using a focused ion beam (FIB) followed by electron backscatter diffraction (EBSD) analysis on each slice. The EBSD data is then reconstructed to generate 3D volume. The 3D-EBSD band quality data is superimposed on inverse pole figure (IPF) grain orientation analysis to get a correlation with quality of band indexing. For the NiO-YSZ case, grain orientations and band quality factors were matched for grains {approx}250 nm diameters producing a high resolution 3D-EBSD data. For this case, a pore space in 3D volume was visible due to nanocrystalline NiO-YSZ grain network. The advantages of 3D EBSD are discussed in the context of its applications to SOFC research community.

  15. The isothermal section of Gd-Ni-Si system at 1070 K

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Knotko, A. V.; Yapaskurt, V. O.; Manfrinetti, P.; Pani, M.; Provino, A.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2016-03-01

    The Gd-Ni-Si system has been investigated at 1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: GdNi10Si2, GdNi8Si3, GdNi5Si3, GdNi7Si6, GdNi6Si6, GdNi4Si, GdNi2Si2, GdNiSi3, Gd3Ni6Si2, GdNiSi, GdNiSi2, GdNi0.4Si1.6, Gd2Ni2.35Si0.65, Gd3NiSi2, Gd3NiSi3 and Gd6Ni1.67Si3, has been confirmed. Moreover, five new phases have been identified in this system. The crystal structure for four of them has been determined: Gd2Ni16-12.8Si1-4.2 (Th2Zn17-type), GdNi6.6Si6 (GdNi7Si6-type), Gd3Ni8Si (Y3Co8Si-type) and Gd3Ni11.5Si4.2(Gd3Ru4Ga12-type). The compound with composition ~Gd2Ni4Si3 still remains with unknown structure. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi5, GdNi3, GdNi2, GdNi, GdSi2 and GdSi1.67; while no appreciable solubility was observed for the other binary compounds of the Gd-Ni-Si system. Magnetic properties of the GdNi6Si6, GdNi6.6Si6 and Gd3Ni11.5Si4.2 compounds have also been investigated and are here reported.

  16. Surface Segregation in Cu-Ni Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

    Monte Carlo simulation is used to calculate the composition profiles of surface segregation of Cu-Ni alloys. The method of Bozzolo, Ferrante, and Smith is used to compute the energetics of these systems as a function of temperature, crystal face, and bulk concentration. The predictions are compared with other theoretical and experimental results.

  17. Magnetic Irreversibility in VO2/Ni Bilayers

    NASA Astrophysics Data System (ADS)

    de La Venta, Jose; Lauzier, Josh; Sutton, Logan

    The temperature dependence of the coercivity and magnetization of VO2/Ni bilayers was studied. VO2 exhibits a well-known Structural Phase Transition (SPT) at 330-340 K, from a low temperature monoclinic (M) to a high temperature rutile (R) structure. The SPT of VO2 induces an inverse magnetoelastic effect that strongly modifies the coercivity and magnetization of the Ni films. In addition, the growth conditions allow tuning of the magnetic properties. Ni films deposited on top of VO2 (M) show an irreversible change in the coercivity after the first cycle through the high temperature phase, with a corresponding change in the surface morphology of VO2. On the other hand, the Ni films grown on top of VO2 (R) do not show this irreversibility. These results indicate that properties of magnetic films are strongly affected by the strain induced by materials that undergo SPT and that it is possible to control the magnetic properties by tuning the growth conditions.

  18. El Niño and health.

    PubMed

    Kovats, R Sari; Bouma, Menno J; Hajat, Shakoor; Worrall, Eve; Haines, Andy

    2003-11-01

    El Niño Southern Oscillation (ENSO) is a climate event that originates in the Pacific Ocean but has wide-ranging consequences for weather around the world, and is especially associated with droughts and floods. The irregular occurrence of El Niño and La Niña events has implications for public health. On a global scale, the human effect of natural disasters increases during El Niño. The effect of ENSO on cholera risk in Bangladesh, and malaria epidemics in parts of South Asia and South America has been well established. The strongest evidence for an association between ENSO and disease is provided by time-series analysis with data series that include more than one event. Evidence for ENSO's effect on other mosquito-borne and rodent-borne diseases is weaker than that for malaria and cholera. Health planners are used to dealing with spatial risk concepts but have little experience with temporal risk management. ENSO and seasonal climate forecasts might offer the opportunity to target scarce resources for epidemic control and disaster preparedness. PMID:14602445

  19. Morphological Evolution of Multilayer Ni/NiO Thin Film Electrodes during Lithiation.

    PubMed

    Evmenenko, Guennadi; Fister, Timothy T; Buchholz, D Bruce; Li, Qianqian; Chen, Kan-Sheng; Wu, Jinsong; Dravid, Vinayak P; Hersam, Mark C; Fenter, Paul; Bedzyk, Michael J

    2016-08-10

    Oxide conversion reactions in lithium ion batteries are challenged by substantial irreversibility associated with significant volume change during the phase separation of an oxide into lithia and metal species (e.g., NiO + 2Li(+) + 2e(-) → Ni + Li2O). We demonstrate that the confinement of nanometer-scale NiO layers within a Ni/NiO multilayer electrode can direct lithium transport and reactivity, leading to coherent expansion of the multilayer. The morphological changes accompanying lithiation were tracked in real-time by in-operando X-ray reflectivity (XRR) and ex-situ cross-sectional transmission electron microscopy on well-defined periodic Ni/NiO multilayers grown by pulsed-laser deposition. Comparison of pristine and lithiated structures reveals that the nm-thick nickel layers help initiate the conversion process at the interface and then provide an architecture that confines the lithiation to the individual oxide layers. XRR data reveal that the lithiation process starts at the top and progressed through the electrode stack, layer by layer resulting in a purely vertical expansion. Longer term cycling showed significant reversible capacity (∼800 mA h g(-1) after ∼100 cycles), which we attribute to a combination of the intrinsic bulk lithiation capacity of the NiO and additional interfacial lithiation capacity. These observations provide new insight into the role of metal/metal oxide interfaces in controlling lithium ion conversion reactions by defining the relationships between morphological changes and film architecture during reaction. PMID:27419860

  20. Characteristics of Reactive Ni3Sn4 Formation and Growth in Ni-Sn Interlayer Systems

    NASA Astrophysics Data System (ADS)

    Lis, Adrian; Kenel, Christoph; Leinenbach, Christian

    2016-06-01

    The near-isothermal growth and formation of Ni3Sn4 intermetallic compounds (IMC) in Ni-Sn interlayer systems was studied in the solid state at 473 K (200 °C) and under solid-liquid conditions at 523 and 573 K (250 °C and 300 °C) from an initial state of a few seconds. Scalloped solid-state IMC formation was mainly driven by grain boundary diffusion of Ni through the IMC layer combined with the grain coarsening of the IMC layer. Under solid-liquid conditions, the formation of faceted and needle-shaped Ni3Sn4 grains as well as an atypical IMC growth behavior with similar parabolic growth constants for 523 K and 573 K (250 °C and 300 °C) was observed within the first 180 seconds of the holding time, and IMC growth occurred as an isothermal solidification from the Ni-saturated Sn melt. Due to the progressive densification of the IMC layer and the diffusion-controlled growth, the kinetics slowed down by approximately one order of magnitude after 180 seconds of annealing. The final stage was characterized by the formation of IMC islands ahead of the interfacial Ni3Sn4 layer. Needle-like IMC growth was effectively suppressed under combined solid-state and solid-liquid conditions. Textured Ni3Sn4 IMC formation at the Ni-Sn interface was approved with pole figure measurements. The activation energy Q for solid-liquid IMC formation was calculated as 43.3 kJ/mol, and processing maps for IMC growth and Sn consumption were derived as functions of temperature and time, respectively.

  1. Characteristics of Reactive Ni3Sn4 Formation and Growth in Ni-Sn Interlayer Systems

    NASA Astrophysics Data System (ADS)

    Lis, Adrian; Kenel, Christoph; Leinenbach, Christian

    2016-03-01

    The near-isothermal growth and formation of Ni3Sn4 intermetallic compounds (IMC) in Ni-Sn interlayer systems was studied in the solid state at 473 K (200 °C) and under solid-liquid conditions at 523 and 573 K (250 °C and 300 °C) from an initial state of a few seconds. Scalloped solid-state IMC formation was mainly driven by grain boundary diffusion of Ni through the IMC layer combined with the grain coarsening of the IMC layer. Under solid-liquid conditions, the formation of faceted and needle-shaped Ni3Sn4 grains as well as an atypical IMC growth behavior with similar parabolic growth constants for 523 K and 573 K (250 °C and 300 °C) was observed within the first 180 seconds of the holding time, and IMC growth occurred as an isothermal solidification from the Ni-saturated Sn melt. Due to the progressive densification of the IMC layer and the diffusion-controlled growth, the kinetics slowed down by approximately one order of magnitude after 180 seconds of annealing. The final stage was characterized by the formation of IMC islands ahead of the interfacial Ni3Sn4 layer. Needle-like IMC growth was effectively suppressed under combined solid-state and solid-liquid conditions. Textured Ni3Sn4 IMC formation at the Ni-Sn interface was approved with pole figure measurements. The activation energy Q for solid-liquid IMC formation was calculated as 43.3 kJ/mol, and processing maps for IMC growth and Sn consumption were derived as functions of temperature and time, respectively.

  2. Density functional theory study on Ni-doped MgnNi (n = 1-7) clusters

    NASA Astrophysics Data System (ADS)

    Chen, Xue-Feng; Zhang, Yan; Qi, Kai-Tian; Li, Bing; Zhu, Zheng-He; Sheng, Yong

    2010-03-01

    The possible geometrical and the electronic structures of small MgnNi (n = 1-7) clusters are optimised by the density functional theory with a LANL2DZ basis set. The binding energy, the energy gap, the electron affinity, the dissociation energy and the second difference in energy are calculated and discussed. The properties of MgnNi clusters are also discussed when the number of Mg atom increases.

  3. Ni-Al2O3 and Ni-Al composite high-aspect-ratio microstructures

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Sorrell, Melford; Kelly, Kevin W.; Ma, Evan

    1998-09-01

    High-aspect-ratio microstructures (HARMs) have a variety of potential applications in heat transfer, fluid mechanics, catalysts and other microelectromechanical systems (MEMS). The aim of this work is to demonstrate the feasibility to fabricate high performance particulate metal-matrix composite and intermetallic micromechanical structures using the LIGA process. Well-defined functionally graded Ni-Al2O3 and Ni-Al high-aspect-ratio microposts were electroformed into lithographically patterned PMMA holes from a nickel sulfamate bath containing submicron alumina and a diluted Watts bath containing microsized aluminum particles, respectively. SEM image analysis showed that the volume fraction of the alumina reached up to around 30% in the Ni-Al2O3 deposit. The Vickers microhardness of these composites is in the range of 418 through 545, which is higher than those of nickel microstructures from a similar particle-free bath and other Ni-based electrodeposits. In the work on Ni-Al electroplating, a newly developed diluted Watts bath was used to codeposit micron-sized aluminum particles. The intermetallic compound Ni3Al was formed by the reaction of nickel matrices and aluminum particles through subsequent annealing at 630 degrees Celsius. WDS and XRD analyses confirmed that the annealed coating is a two-phase (Ni-Ni3Al) composite. The maximum aluminum volume fraction reached 19% at a cathode current density of 12 mA cm-2, and the Vickers microhardness of the as-deposited coatings is in the range 392 - 515 depending on the amount of aluminum incorporated.

  4. Bone Cell–materials Interactions and Ni Ion Release of Anodized Equiatomic NiTi Alloy

    PubMed Central

    Bernard, Sheldon A.; Balla, Vamsi Krishna; Davies, Neal M.; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    Laser processed NiTi alloy was anodized for different durations in H2SO4 electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-materials interactions. The anodized surfaces were assessed for their in vitro cell-materials interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that the anodization creates a surface with nano/micro roughness depending on anodization conditions. The hydrophilicity of NiTi surface was found to improve after anodization due to lower contact angles in cell media, which dropped from 32° to < 5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy comparable to that of cp Ti. Relatively high surface energy, especially polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268 ± 11 to 136 ± 15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improve bone cell-materials interactions and reduce Ni ion release in vitro. PMID:21232641

  5. Film Thickness Influences on the Thermoelectric Properties of NiCr/NiSi Thin Film Thermocouples

    NASA Astrophysics Data System (ADS)

    Chen, Y. Z.; Jiang, H. C.; Zhang, W. L.; Liu, X. Z.; Jiang, S. W.

    2013-06-01

    NiCr/NiSi thin film thermocouples (TFTCs) with a multi-layer structure were fabricated on Ni-based superalloy substrates (95 mm × 35 mm × 2 mm) by magnetron sputtering and electron beam evaporation. The five-layer structure is composed of NiCrAlY buffer layer (2 μm), thermally grown Al2O3 bond layer (200 nm), Al2O3 insulating layer (10 μm), NiCr/NiSi TFTCs (1 μm), and Al2O3 protective layer (500 nm). Influences of thermocouple layer thickness on thermoelectric properties were investigated. Seebeck coefficient of the samples with the increase in thermocouple layer thickness from 0.5 μm to 1 μm increased from 27.8 μV/°C to 33.8 μV/°C, but exhibited almost no change with further increase in thermocouple layer thickness from 1 μm to 2 μm. Dependence on temperature of the thermal electromotive force of the samples almost followed standard thermocouple characteristic curves when the thickness of the thermocouple layer was 1 μm and 2 μm. Sensitive coefficient K of the samples increased greatly with the increase in thickness of the thermocouple layer from 0.5 μm to 1 μm, but decreased insignificantly with the increase in thermocouple layer thickness from 1 μm to 2 μm, and continuously decreased with the increase in temperature. The sensitive coefficient and the stability of NiCr/NiSi TFTCs were both improved after annealing at 600°C.

  6. Geometric structures of thin film: Pt on Pd(110) and NiO on Ni(100)

    SciTech Connect

    Warren, O.L.

    1993-07-01

    This thesis is divided into 3 papers: dynamical low-energy electron- diffraction investigation of lateral displacements in topmost layer of Pd(110); determination of (1{times}1) and (1{times}2) structures of Pt thin films on Pd(110) by dynamical low-energy electron-diffraction analysis; and structural determination of a NiO(111) film on Ni(100) by dynamical low-energy electron-diffraction analysis.

  7. Laser induced chemical vapor deposition of Ni by decomposition of Ni(CO)4

    NASA Astrophysics Data System (ADS)

    Kräuter, W.; Bäuerle, D.; Fimberger, F.

    1983-05-01

    Polycrystalline Ni has been grown by decomposition of Ni(CO)4 using different wavelengths of the visible radiation of a Kr+ laser. The influence of laser irradiance, substrate material and scanning velocity on deposition rate and widths of patterns has been investigated. The deposition rates achieved are typically several μm/s, and the lateral dimensions of the deposits can be as small as 1 μm.

  8. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires

    PubMed Central

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19′ martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19′ martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  9. Chiral Three-Dimensional Microporous Nickel Aspartate with Extended Ni-O-Ni Bonding

    SciTech Connect

    Anokhina,E.; Go, Y.; Lee, Y.; Vogt, T.; Jacobson, A.

    2006-01-01

    In the course of our investigation aimed at the preparation of homochiral coordination polymers using readily available in optically pure form ligands and building blocks of condensed metal polyhedra, we recently reported a one-dimensional nickel aspartate compound [Ni{sub 2}O(L-Asp)(H{sub 2}O){sub 2}]{center_dot}4H{sub 2}O (1) based on helical chains with extended Ni-O-Ni bonding. Here we report a new nickel aspartate [Ni{sub 2.5}(OH)(L-Asp){sub 2}]{center_dot}6.55H{sub 2}O (2) with a three-dimensional Ni-O-Ni connectivity that forms at a higher pH and is based on the same helices as in 1 which are connected by additional nickel octahedra to generate a chiral open framework with one-dimensional channels with minimum van der Waals dimensions of 8 x 5 Angstroms. The crystal structure of 2 was determined by synchrotron single-crystal X-ray diffraction on a 10 x 10 x 240 {micro}m crystal.

  10. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires.

    PubMed

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-01-01

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19' martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19' martensitic transformation, and (V) plastic deformation of the specimen. PMID:27049025

  11. Controlled synthesis of Ni/CuOx/Ni nanowires by electrochemical deposition with self-compliance bipolar resistive switching

    PubMed Central

    Park, Kyuhyun; Lee, Jang-Sik

    2016-01-01

    We demonstrate synthesis of Ni/CuOx/Ni nanowires (NWs) by electrochemical deposition on anodized aluminum oxide (AAO) membranes. AAO with pore diameter of ~70 nm and pore length of ~50 μm was used as the template for synthesis of NWs. After deposition of Au as the seed layer, NWs with a structure of Ni/CuOx/Ni were grown with a length of ~12 μm. The lengths of 1st Ni, CuOx, and 2nd Ni were ~4.5 μm, ~3 μm, and ~4.5 μm, respectively. The Ni/CuOx/Ni device exhibits bipolar resistive switching behavior with self-compliance characteristics. Due to the spatial restriction of the current path in NW the Ni/CuOx/Ni NW devices are thought to exhibit self-compliance behaviour. Ni/CuOx/Ni NWs showed bipolar resistive changes possibly due to conducting filaments that are induced by oxygen vacancies. The reliability of the devices was confirmed by data retention measurement. The NW-based resistive switching memory has applications in highly scalable memory devices and neuromorphic devices. PMID:26975330

  12. Controlled synthesis of Ni/CuOx/Ni nanowires by electrochemical deposition with self-compliance bipolar resistive switching

    NASA Astrophysics Data System (ADS)

    Park, Kyuhyun; Lee, Jang-Sik

    2016-03-01

    We demonstrate synthesis of Ni/CuOx/Ni nanowires (NWs) by electrochemical deposition on anodized aluminum oxide (AAO) membranes. AAO with pore diameter of ~70 nm and pore length of ~50 μm was used as the template for synthesis of NWs. After deposition of Au as the seed layer, NWs with a structure of Ni/CuOx/Ni were grown with a length of ~12 μm. The lengths of 1st Ni, CuOx, and 2nd Ni were ~4.5 μm, ~3 μm, and ~4.5 μm, respectively. The Ni/CuOx/Ni device exhibits bipolar resistive switching behavior with self-compliance characteristics. Due to the spatial restriction of the current path in NW the Ni/CuOx/Ni NW devices are thought to exhibit self-compliance behaviour. Ni/CuOx/Ni NWs showed bipolar resistive changes possibly due to conducting filaments that are induced by oxygen vacancies. The reliability of the devices was confirmed by data retention measurement. The NW-based resistive switching memory has applications in highly scalable memory devices and neuromorphic devices.

  13. Studies on the Sliding Wear Performance of Plasma Spray Ni-20Cr and Ni3Al Coatings

    NASA Astrophysics Data System (ADS)

    Kaur, Maninder; Singh, Harpreet; Singh, Balraj; Singh, Bhupinder

    2010-01-01

    Two metallic powders namely Ni-20Cr and Ni3Al were coated on AISI 309 SS steel by shrouded plasma spray process. The wear behavior of the bare, Ni-20Cr and Ni3Al-coated AISI 309 SS steel was investigated according to ASTM Standard G99-03 on a Pin-on-Disc Wear Test Rig. The wear tests were carried out at normal loads of 30 and 50 N with a sliding velocity of 1 m/s. Cumulative wear rate and coefficient of friction (μ) were calculated for all the cases. The worn-out surfaces were then examined by scanning electron microscopy analysis. Both the as-sprayed coatings exhibited typical splat morphology. The XRD analysis indicated the formation of Ni phase for the Ni-20Cr coating and Ni3Al phase for the Ni3Al coating. It has been concluded that the plasma-sprayed Ni-20Cr and Ni3Al coatings can be useful to reduce the wear rate of AISI 309 SS steel. The coatings were found to be adherent to the substrate steel during the wear tests. The plasma-sprayed Ni3Al coating has been recommended as a better choice to reduce the wear of AISI 309 SS steel, in comparison with the Ni-20Cr coating.

  14. Using Chelator-Buffered Nutrient Solutions to Induce Ni-Deficiency in the Ni-Hyperaccumulator Alyssum murale

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ni is essential for all plants due to its role in urease. Many Alyssum species are known to hyperaccumulate Ni to over 20 g kg-1 dry weight (DW) while normal plants require only about 0.1 mg kg-1 DW. As part of our research on Ni hyperaccumulation by plants, we conducted experiments to measure the...

  15. Controlled synthesis of Ni/CuOx/Ni nanowires by electrochemical deposition with self-compliance bipolar resistive switching.

    PubMed

    Park, Kyuhyun; Lee, Jang-Sik

    2016-01-01

    We demonstrate synthesis of Ni/CuOx/Ni nanowires (NWs) by electrochemical deposition on anodized aluminum oxide (AAO) membranes. AAO with pore diameter of ~70 nm and pore length of ~50 μm was used as the template for synthesis of NWs. After deposition of Au as the seed layer, NWs with a structure of Ni/CuOx/Ni were grown with a length of ~12 μm. The lengths of 1(st) Ni, CuOx, and 2(nd) Ni were ~4.5 μm, ~3 μm, and ~4.5 μm, respectively. The Ni/CuOx/Ni device exhibits bipolar resistive switching behavior with self-compliance characteristics. Due to the spatial restriction of the current path in NW the Ni/CuOx/Ni NW devices are thought to exhibit self-compliance behaviour. Ni/CuOx/Ni NWs showed bipolar resistive changes possibly due to conducting filaments that are induced by oxygen vacancies. The reliability of the devices was confirmed by data retention measurement. The NW-based resistive switching memory has applications in highly scalable memory devices and neuromorphic devices. PMID:26975330

  16. Antiferromagnetism in EuNiGe3

    SciTech Connect

    Goetsch, R. J.; Ananad, V. K.; Johnston, David C.

    2013-02-07

    The synthesis and crystallographic and physical properties of polycrystalline EuNiGe3 are reported. EuNiGe3 crystallizes in the noncentrosymmetric body-centered tetragonal BaNiSn3-type structure (space group I4mm), in agreement with previous reports, with the Eu atoms at the corners and body center of the unit cell. The physical property data consistently demonstrate that this is a metallic system in which Eu spins S = 7/2 order antiferromagnetically at a temperature TN = 13.6 K.Magnetic susceptibility χ data forT >TN indicate that the Eu atoms have spin 7/2 with g = 2, that the Ni atoms are nonmagnetic, and that the dominant interactions between the Eu spins are ferromagnetic. Thus we propose that EuNiGe3 has a collinear A-type antiferromagnetic structure, with the Eu ordered moments in the ab plane aligned ferromagnetically and with the moments in adjacent planes along the c axis aligned antiferromagnetically. A fit of χ(T TN) by our molecular field theory is consistent with a collinear magnetic structure. Electrical resistivity ρ data from TN to 350 K are fitted by the Bloch-Gr¨uneisen model for electron-phonon scattering, yielding a Debye temperature of 265(2) K.Astrong decrease in ρ occurs belowTN due to loss of spin-disorder scattering. Heat capacity data at 25 K T 300Kare fitted by the Debye model, yielding the same Debye temperature 268(2) K as found from ρ(T ). The extracted magnetic heat capacity is consistent with S = 7/2 and shows that significant short-range dynamical spin correlations occur above TN. The magnetic entropy at TN = 13.6 K is 83% of the expected asymptotic high-T value, with the remainder recovered by 30 K.

  17. A New Polycrystalline Co-Ni Superalloy

    NASA Astrophysics Data System (ADS)

    Knop, M.; Mulvey, P.; Ismail, F.; Radecka, A.; Rahman, K. M.; Lindley, T. C.; Shollock, B. A.; Hardy, M. C.; Moody, M. P.; Martin, T. L.; Bagot, P. A. J.; Dye, D.

    2014-12-01

    In 2006, a new-ordered L12 phase, Co3(Al,W), was discovered that can form coherently in a face-centered cubic (fcc) A1 Co matrix. Since then, a community has developed that is attempting to take these alloys forward into practical applications in gas turbines. A new candidate polycrystalline Co-Ni γ/ γ' superalloy, V208C, is presented that has the nominal composition 36Co-35Ni-15Cr-10Al-3W-1Ta (at.%). The alloy was produced by conventional powder metallurgy superalloy methods. After forging, a γ' fraction of ~56% and a secondary γ' size of 88 nm were obtained, with a grain size of 2.5 μm. The solvus temperature was 1000°C. The density was found to be 8.52 g cm-3, which is similar to existing Ni alloys with this level of γ'. The alloy showed the flow stress anomaly and a yield strength of 920 MPa at room temperature and 820 MPa at 800°C, similar to that of Mar-M247. These values are significantly higher than those found for either conventional solution and carbide-strengthened Co alloys or the γ/ γ' Co superalloys presented in the literature thus far. The oxidation resistance, with a mass gain of 0.08 mg cm-2 in 100 h at 800°C, is also comparable with that of existing high-temperature Ni superalloys. These results suggest that Co-based and Co-Ni superalloys may hold some promise for the future in gas turbine applications.

  18. Layer-Resolved Magnetic Moments in Ni/Pt Multilayers

    NASA Astrophysics Data System (ADS)

    Wilhelm, F.; Poulopoulos, P.; Ceballos, G.; Wende, H.; Baberschke, K.; Srivastava, P.; Benea, D.; Ebert, H.; Angelakeris, M.; Flevaris, N. K.; Niarchos, D.; Rogalev, A.; Brookes, N. B.

    2000-07-01

    The magnetic moments in Ni/Pt multilayers are thoroughly studied by combining experimental and ab initio theoretical techniques. SQUID magnetometry probes the samples' magnetizations. X-ray magnetic circular dichroism separates the contribution of Ni and Pt and provides a layer-resolved magnetic moment profile for the whole system. The results are compared to band-structure calculations. Induced Pt magnetic moments localized mostly at the interface are revealed. No magnetically ``dead'' Ni layers are found. The magnetization per Ni volume is slightly enhanced compared to bulk NiPt alloys.

  19. Atomistic modeling of ternary additions to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt and Ni-Ti-Hf shape memory alloys

    NASA Astrophysics Data System (ADS)

    Mosca, H. O.; Bozzolo, G.; del Grosso, M. F.

    2012-08-01

    The behavior of ternary and quaternary additions to NiTi shape memory alloys is investigated using a quantum approximate method for the energetics. Ternary additions X to NiTi and quaternary additions to Ni-Ti-Pd, Ni-Ti-Pt, and Ni-Ti-Hf alloys, for X=Au, Pt, Ir, Os, Re, W, Ta,Ag, Pd, Rh, Ru, Tc, Mo, Nb, Zr, Zn, Cu, Co, Fe, Mn, V, Sc, Si, Al and Mg are considered. Bulk properties such as lattice parameter, energy of formation, and bulk modulus of the B2 alloys are studied for variations due to the presence of one or two simultaneous additives.

  20. In Situ XAS of Ni-W Hydrocracking Catalysts

    NASA Astrophysics Data System (ADS)

    Yang, N.; Mickelson, G. E.; Greenlay, N.; Kelly, S. D.; Bare, Simon R.

    2007-02-01

    Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS2 platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni (˜25%) and W (<10%) in the lower activity sample.

  1. Creep in Directionally Solidified NiAl-Mo Eutectics

    SciTech Connect

    Dudova, Marie; Kucharova, Kveta; Bartak, Tomas; Bei, Hongbin; George, Easo P; Somsen, Ch.; Dlouhy, A.

    2011-01-01

    A directionally solidified NiAl-Mo eutectic and an NiAl intermetallic, having respective nominal compositions Ni-45.5Al-9Mo and Ni-45.2Al (at.%), were loaded in compression at 1073 and 1173 K. Formidable strengthening by regularly distributed Mo fibres (average diameter 600 nm, volume fraction 14%) was observed. The fibres can support compression stresses transferred from the plastically deforming matrix up to a critical stress of the order of 2.5 GPa, at which point they yield. Microstructural evidence is provided for the dislocation-mediated stress transfer from the NiAl to the Mo phase.

  2. Detection of Ni 2 lambda 7378 in six Seyfert galaxies

    NASA Technical Reports Server (NTRS)

    Halpern, J. P.; Oke, J. B.

    1985-01-01

    A line due to Ni 2 7378 in the Seyfert galaxies NGC 1068, 2110, 3227, 4151, 5506, and Arp 102 B was detected. The average Ni abundance is about 2 times solar, which is 5 times less than in the filaments of the Crab Nebula. This argues for nucleosynthetic processing in the latter. The Ni 2 line is spatially revolved in NGC 1068, and shows at least a factor of 4 enhancement in the Ni abundance away from the nucleus. The off-nuclear abundance of Ni in NGC 1068 approaches that of the Crab, which strongly suggests that type supernovae enriched the off-nuclear gas clouds.

  3. Cyanide-bridged NiCr and alternate NiFe-NiCr magnetic ultrathin films on functionalized Si(100) surface.

    PubMed

    Tricard, Simon; Costa-Coquelard, Claire; Mazerat, Sandra; Rivière, Eric; Huc, Vincent; David, Christophe; Miserque, Frédéric; Jegou, Pascale; Palacin, Serge; Mallah, Talal

    2012-04-21

    Sequential growth in solution (SGS) was performed for the magnetic cyanide-bridged network obtained from the reaction of Ni(H(2)O)(2+) and Cr(CN)(6)(3-) (referred to as NiCr) on a Si(100) wafer already functionalized by a Ni(II) complex. The growth process led to isolated dots and a low coverage of the surface. We used the NiFe network as a template to improve the growth of the magnetic network. We elaborated alternate NiFe (paramagnetic)-NiCr (ferromagnetic) ultrathin films around 6 nm thick. The magnetic behaviour confirmed the alternate structure with the ferromagnetic zones isolated between the paramagnetic ones since the evolution of the blocking temperature is consistent with the evolution of the layers' thickness expected from the SGS process. PMID:22344390

  4. State of Supported Nanoparticle Ni during Catalysis in Aqueous Media

    SciTech Connect

    Chase, Zizwe; Vjunov, Aleksei; Fulton, John; Camaioni, Donald; Balasubramanian, Mahalingam; Lercher, Johannes

    2015-11-09

    The state of Ni supported on HZSM-5 zeolite, silica, and sulfonated carbon was studied during aqueous-phase catalysis of phenol hydrodeoxygenation using in situ extended X-ray absorption fine structure spectroscopy. On sulfonated carbon and HZSM-5 supports, NiO and Ni(OH)(2) were readily reduced to Ni-0 under reaction conditions (approximate to 35bar H-2 in aqueous phenol solutions containing up to 0.5wt.% phosphoric acid at 473K). In contrast, Ni supported on SiO2 was not stable in a fully reduced Ni-0 state. Water enables the formation of Ni-II phyllosilicate, which is more stable, that is, difficult to reduce, than either -Ni(OH)(2) or NiO. Leaching of Ni from the supports was not observed over a broad range of reaction conditions. Ni-0 particles on HZSM-5 were stable even in presence of 15wt.% acetic acid at 473K and 35bar H-2.

  5. Nickeltetracarbonyl formation on non-equilibrium Ni surfaces

    NASA Astrophysics Data System (ADS)

    Medvedev, V. K.; Börner, R.; Kruse, N.

    1998-05-01

    The subject of this investigation was the kinetics of Ni volatilization in form of nickeltetracarbonyl (Ni(CO) 4) during the interaction of CO gas with a Ni foil at room temperature (or slightly above). A trap-decomposition technique on an auxiliary Rh surface and posterior Auger spectroscopy were used for the product analysis. The presence of a high step site density (kinks) on an intentionally roughened Ni surface was found to cause a strong rate enhancement. CO pressures as low as 5×10 -5 mbar turned out to be sufficient for the reaction to occur. However, a well-annealed equilibrium Ni surface remained inactive in Ni(CO) 4 formation under these conditions. A reaction model is presented by taking into account the present-day knowledge about Ni-subcarbonyl intermediate formation.

  6. In situ NiTi/Nb(Ti) composite

    SciTech Connect

    Jiang, Daqiang Cui, Lishan; Jiang, Jiang; Zheng, Yanjun

    2013-12-15

    Graphical abstract: - Highlights: • In situ NiTi/Nb(Ti) composites were fabricated. • The transformation temperature was affected by the mixing Ti:Ni atomic ratios. • The NiTi component became micron-scale lamella after forging and rolling. • The composite exhibited high strength and high damping capacity. - Abstract: This paper reports on the creation of a series of in situ NiTi/Nb(Ti) composites with controllable transformation temperatures based on the pseudo-binary hypereutectic transformation of NiTi–Nb system. The composite constituent morphology was controlled by forging and rolling. It is found that the thickness of the NiTi lamella in the composite reached micron level after the hot-forging and cold-rolling. The NiTi/Nb(Ti) composite exhibited high damping capacity as well as high yield strength.

  7. Long Term Performance Retention Test Using High Power COTS NiCd and NiMH Cells

    NASA Technical Reports Server (NTRS)

    Hall, Dan; Darcy, Eric; Strangways, Brad; Nelson, Tim

    2003-01-01

    This slide presentation reviews the tests and results for performance retention of high powered commercial off the shelf (COTS) NiCd, and NiMH cells. Electromechanical actuators for space flight requires short duration high power batteries. The concern is that NiCd battery designs demonstrate an unfavorable power degradation after long periods of inactivity. Cycling can recover some of the decay, but this reduces the readiness that these batteries must have. Two 5-cell SubC stick test batteries ere chosen using NiCd and NiMH were tested and then the differences for charge maintenance were compared.

  8. The Effect of Metal Composition on Fe-Ni Partition Behavior between Olivine and FeNi-Metal, FeNi-Carbide, FeNi-Sulfide at Elevated Pressure

    NASA Technical Reports Server (NTRS)

    Holzheid, Astrid; Grove, Timothy L.

    2005-01-01

    Metal-olivine Fe-Ni exchange distribution coefficients were determined at 1500 C over the pressure range of 1 to 9 GPa for solid and liquid alloy compositions. The metal alloy composition was varied with respect to the Fe/Ni ratio and the amount of dissolved carbon and sulfur. The Fe/Ni ratio of the metal phase exercises an important control on the abundance of Ni in the olivine. The Ni abundance in the olivine decreases as the Fe/Ni ratio of the coexisting metal increases. The presence of carbon (up to approx. 3.5 wt.%) and sulfur (up to approx. 7.5 wt.%) in solution in the liquid Fe-Ni-metal phase has a minor effect on the partitioning of Fe and Ni between metal and olivine phases. No pressure dependence of the Fe-Ni-metal-olivine exchange behavior in carbon- and sulfur-free and carbon- and sulfur-containing systems was found within the investigated pressure range. To match the Ni abundance in terrestrial mantle olivine, assuming an equilibrium metal-olivine distribution, a sub-chondritic Fe/Ni-metal ratio that is a factor of 17 to 27 lower than the Fe/Ni ratios in estimated Earth core compositions would be required, implying higher Fe concentrations in the core forming metal phase. A simple metal-olivine equilibrium distribution does not seem to be feasible to explain the Ni abundances in the Earth's mantle. An equilibrium between metal and olivine does not exercise a control on the problem of Ni overabundance in the Earth's mantle. The experimental results do not contradict the presence of a magma ocean at the time of terrestrial core formation, if olivine was present in only minor amounts at the time of metal segregation.

  9. Ni cycling in mangrove sediments from New Caledonia

    NASA Astrophysics Data System (ADS)

    Noel, V. S.; Morin, G.; Juillot, F.; Marchand, C.; Brest, J.; Bargar, J.; Munoz, M.; Ardo, S.; Brown, G. E.

    2014-12-01

    In New Caledonia, mangroves receive large inputs of lateritic materials eroded from massive ultramafic deposits enriched in Fe, Ni, Mn, Cr, and Co. Because of the major physicochemical gradients, especially redox gradients, that characterize these ecosystems, mineralogical transformations may influence the crystal-chemistry and bioavailability of Ni and its mobility towards a lagoon of over 20,000 km2. Bulk and spatially resolved chemical analyses by SEM-EDXS were coupled with Ni K-edge X-ray absorption fine structure (XAFS) spectroscopy analysis to characterize the vertical and lateral changes in Ni speciation across the intertidal zone of a mangrove forest in the Vavouto Bay (New Caledonia) where Ni concentrations range from 1000 to 5300 mg•kg-1. XAFS results indicate that phyllosilicates and goethite inherited from the eroded lateritic materials are the dominant Ni-bearing phases in the surface horizons of the mangrove sediments. They are fully preserved at depth in the dry and oxic salt flat area, located on the inland side of the coast. In contrast, beneath the vegetated Rhizophoras and Avicennias stands Ni-bearing goethites rapidly diminish with increasing depth in the anoxic horizons of the sediments, and pyrite and organic complexes become the dominant Ni-containing species. Moreover, Ni incorporation in pyrite is more developed in the sediments beneath the intermediate Avicennia stand than beneath the Rhizophora stand that is closest to the shore. Such lateral changes in Ni speciation may be related to reoxidation of Ni-bearing pyrites in the Rhizophora stand, which is subject to periodic alternation of reducing and oxidizing events due to tidal fluctuations. These major changes in Ni speciation could significantly influence Ni mobility across the interidal zone. Indeed, as estimated with respect to Ti concentration, which is taken as a geochemical invariant, Ni is found to be immobile in the salt flat, to accumulate beneath the Avicennia stand, and to

  10. Microstructure of the Native Oxide Layer on Ni and Cr-doped Ni Nanoparticles

    SciTech Connect

    Wang, Chong M.; Baer, Donald R.; Bruemmer, Stephen M.; Engelhard, Mark H.; Bowden, Mark E.; Sundararajan, J. A.; Qiang, You

    2011-10-01

    Metallic or alloy nanoparticles exposed to air at room temperature will be instantaneously oxidized and covered by an oxide layer. However, for most cases, the true structural nature of the oxide layer formed at this stage is hard to determine. In this paper, we report the structure, morphology, and electronic structure (the density of state of both valence and conduction bands measured by a combination of XPS and EELS) of pure Ni and Cr-doped Ni nanoparticles synthesized using a cluster deposition process. Structural characterization carried out at the atomic level using aberration corrected high resolution transmission electron microscopy (HRTEM) in combination with electron and x-ray diffractions reveals that both pure Ni and Cr-doped Ni particles exposed to air at room temperature similarly possesses a core-shell structure of metal core covered by an oxide layer of typically 1.6 nm in thickness. There exists a critical size of ~ 6 nm, below which the particle is fully oxidized. The oxide particle corresponds to the rock-salt structured NiO and is faceted on the (001) planes. XPS of O-1s shows a strong peak that is attributed to (OH)-, which in combination with the atomic level HRTEM imaging indicates that the very top layer of the oxide is hydrolyzed as Ni(OH)2. Chemical composition analysis using EDS, EELS, and XPS indicates that the Cr dopant at the level of ~ 5at% forms solid solution with the Ni lattice. The Cr shows no segregation on the surface or preferential oxidation during the initial oxidation.

  11. Thiolate-protected Ni39 and Ni41 nanoclusters: synthesis, self-assembly and magnetic properties

    NASA Astrophysics Data System (ADS)

    Ji, Jianwei; Wang, Guan; Wang, Tianwei; You, Xiaozeng; Xu, Xiangxing

    2014-07-01

    Thiolate-protected soluble nickel clusters, Ni39(SC2H4Ph)24 and Ni41(SC2H4Ph)25, were synthesized via a wet chemical method. The cluster formulae were identified by MALDI-TOF. Possible structures of the clusters were discussed. These clusters exhibit ferromagnetism with hysteresis loops in the 1.8-300 K range. By solvent evaporation, the clusters can self-assemble into simple cubic structured crystals with a width in the range of 1-10 μm and length up to 300 μm. These properties shed light on their application potentials in nanomagnetics working at room temperature.Thiolate-protected soluble nickel clusters, Ni39(SC2H4Ph)24 and Ni41(SC2H4Ph)25, were synthesized via a wet chemical method. The cluster formulae were identified by MALDI-TOF. Possible structures of the clusters were discussed. These clusters exhibit ferromagnetism with hysteresis loops in the 1.8-300 K range. By solvent evaporation, the clusters can self-assemble into simple cubic structured crystals with a width in the range of 1-10 μm and length up to 300 μm. These properties shed light on their application potentials in nanomagnetics working at room temperature. Electronic supplementary information (ESI) available: XPS, EDS, MALDI-TOF mass spectrum and TGA analysis of the Ni39(SC2H4Ph)24 and Ni41(SC2H4Ph)25 clusters. TEM and XRD spectra of the Ni clusters annealed in Ar at 240 °C for 2 h. See DOI: 10.1039/c4nr01063a

  12. High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

    NASA Astrophysics Data System (ADS)

    Rhen, Fernando M. F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

    We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4Fe 27.7Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux ( μ0Ms) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μr' ˜475 up to 30 MHz with a quality factor ( Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μr'=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency.

  13. Ab initio molecular dynamics investigations of low-energy recoil events in Ni and NiCo

    SciTech Connect

    Liu, Bin; Yuan, Fenglin; Jin, Ke; Zhang, Yanwen; Weber, William J.

    2015-10-06

    Low-energy recoil events in pure Ni and the equiatomic NiCo alloy are studied using ab initio molecular dynamics simulations. We found that the threshold displacement energies are strongly dependent on orientation and weakly dependent on composition. The minimum threshold displacement energies are along the [1 1 0] direction in both pure Ni and the NiCo alloy. Compared to pure Ni, the threshold displacement energies increase slightly in the NiCo alloy due to stronger bonds in the alloy, irrespective of the element type of the PKA. A single Ni interstitial occupying the center of a tetrahedron formed by four Ni atoms and a <1 0 0> split interstitial is produced in pure Ni by the recoils, while only the <1 0 0> split interstitial is formed in the NiCo alloy. Compared to the replacement sequences in pure Ni, anti-site defect sequences are observed in the alloy, which have high efficiency for both producing defects and transporting energy outside of the cascade core. These results provide insights into energy transfer processes occurring in equiatomic alloys under irradiation.

  14. Fe-Ni composition dependence of magnetic anisotropy in artificially fabricated L1 0-ordered FeNi films.

    PubMed

    Kojima, Takayuki; Ogiwara, Misako; Mizuguchi, Masaki; Kotsugi, Masato; Koganezawa, Tomoyuki; Ohtsuki, Takumi; Tashiro, Taka-Yuki; Takanashi, Koki

    2014-02-12

    We prepared L10-ordered FeNi alloy films by alternate deposition of Fe and Ni monatomic layers, and investigated their magnetic anisotropy. We employed a non-ferromagnetic Au-Cu-Ni buffer layer with a flat surface and good lattice matching to L10-FeNi. An L10-FeNi film grown on Au6Cu51Ni43 showed a large uniaxial magnetic anisotropy energy (Ku = 7.0 × 10(6) erg cm(-)3). Ku monotonically increased with the long-range order parameter (S) of the L10 phase. We investigated the Fe-Ni composition dependence by alternating the deposition of Fe 1 − x and Ni 1 + x monatomic layers (− 0.4 < x < 0.4). Saturation magnetization (Ms) and Ku showed maxima (Ms = 1470 emu cm(-3), Ku = 9.3 × 10(6) erg cm(-3)) for Fe60Ni40 (x = -0.2) while S showed a maximum at the stoichiometric composition (x = 0). The change in the ratio of lattice parameters (c/a) was small for all compositions. We found that enrichment of Fe is very effective to enhance Ku. The large Ms and Ku of Fe60Ni40 indicate that Fe-rich L10-FeNi is promising as a rare-earth-free permanent magnet. PMID:24469082

  15. Ab initio molecular dynamics investigations of low-energy recoil events in Ni and NiCo

    DOE PAGESBeta

    Liu, Bin; Yuan, Fenglin; Jin, Ke; Zhang, Yanwen; Weber, William J.

    2015-10-06

    Low-energy recoil events in pure Ni and the equiatomic NiCo alloy are studied using ab initio molecular dynamics simulations. We found that the threshold displacement energies are strongly dependent on orientation and weakly dependent on composition. The minimum threshold displacement energies are along the [1 1 0] direction in both pure Ni and the NiCo alloy. Compared to pure Ni, the threshold displacement energies increase slightly in the NiCo alloy due to stronger bonds in the alloy, irrespective of the element type of the PKA. A single Ni interstitial occupying the center of a tetrahedron formed by four Ni atomsmore » and a <1 0 0> split interstitial is produced in pure Ni by the recoils, while only the <1 0 0> split interstitial is formed in the NiCo alloy. Compared to the replacement sequences in pure Ni, anti-site defect sequences are observed in the alloy, which have high efficiency for both producing defects and transporting energy outside of the cascade core. These results provide insights into energy transfer processes occurring in equiatomic alloys under irradiation.« less

  16. Microstructure and mechanical properties of sputter deposited Ni/Ni3Al multilayer films at elevated temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Feng, Kai; Li, Zhuguo; Lu, Fenggui; Huang, Jian; Wu, Yixiong

    2016-08-01

    Nano-structured Ni/Ni3Al multilayer was prepared by magnetron sputtering, with individual layer thicknesses h varying from 10 to 160 nm. The microstructure and hardness of Ni/Ni3Al multilayer were investigated by X-ray diffraction, transmission electron microscopy and nanoindentation. The results show that the hardness increases with decreasing h for as-deposited and 500 °C annealed multilayers. When annealed at 700 °C, the hardness approach a peak value at h = 40 nm with followed by softening at smaller h. The influence of individual layer thickness, grain size as well as formation of ordered Ni3Al on strengthening mechanisms of Ni/Ni3Al multilayers at elevated temperature are discussed.

  17. Stripe-to-bubble transition of magnetic domains at the spin reorientation of (Fe/Ni)/Cu/Ni/Cu(001)

    SciTech Connect

    Wu, J.; Choi, J.; Won, C.; Wu, Y. Z.; Scholl, A.; Doran, A.; Hwang, Chanyong; Qiu, Z.

    2010-06-09

    Magnetic domain evolution at the spin reorientation transition (SRT) of (Fe/Ni)/Cu/Ni/Cu(001) is investigated using photoemission electron microscopy. While the (Fe/Ni) layer exhibits the SRT, the interlayer coupling of the perpendicularly magnetized Ni layer to the (Fe/Ni) layer serves as a virtual perpendicular magnetic field exerted on the (Fe/Ni) layer. We find that the perpendicular virtual magnetic field breaks the up-down symmetry of the (Fe/Ni) stripe domains to induce a net magnetization in the normal direction of the film. Moreover, as the virtual magnetic field increases to exceed a critical field, the stripe domain phase evolves into a bubble domain phase. Although the critical field depends on the Fe film thickness, we show that the area fraction of the minority domain exhibits a universal value that determines the stripe-to-bubble phase transition.

  18. Ni{sub 3}Al technology transfer

    SciTech Connect

    Sikka, V.K.; Santella, M.L.; Alexander, D.J.

    1995-05-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for (1)high-strength castable composition for turbochargers, furnace furniture, and hot-die applications; (2) castability (fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) hot fabricability of cast ingots. All of the issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes work completed to address some of these issues during the fourth quarter of FY 1994.

  19. Diffusion induced recrystallization of NiO

    SciTech Connect

    Parthasarathy, T.A.; Shewmon, P.G.

    1984-01-01

    It is shown that changing the composition of a sample from that in equilibrium with air at 1200/sup 0/C to that in equilibrium with oxygen saturated Ni at 800-900/sup 0/C recrystallize the surface to a finer grain size. Annealing back at 1200/sup 0/C in air will again recrystallize the surface layer. This type of diffusion-induced recrystallization has been observed in metals, but never reported in ceramics. Its occurrence in NiO is interpreted as a demonstration that diffusion-induced grain boundary motion is driven directly by the free energy of mixing defects into the matrix instead of indirectly as suggested by others.

  20. Ni-Catalyzed Amination Reactions: An Overview.

    PubMed

    Marín, Mario; Rama, Raquel J; Nicasio, M Carmen

    2016-08-01

    Nitrogen-containing organic compounds are valuable in many fields of science and industry. The most reliable method for the construction of C(sp(2) )-N bonds is undoubtedly palladium-catalyzed amination. In spite of the great achievements made in this area, the use of expensive Pd-based catalysts constitutes an important limitation for large-scale applications. Since nickel is the least expensive and most abundant among the group 10 metals, the interest in Ni-based catalysts for processes typically catalyzed by palladium has grown considerably over the last few years. Herein, we revise the development of Ni-catalyzed amination reactions, emphasizing the most relevant and recent advances in the field. PMID:27265724

  1. Ni doping of semiconducting boron carbide

    SciTech Connect

    Hong, Nina; Liu Jing; Adenwalla, S.; Langell, M. A.; Kizilkaya, Orhan

    2010-01-15

    The wide band gap, temperature stability, high resistivity, and robustness of semiconducting boron carbide make it an attractive material for device applications. Undoped boron carbide is p type; Ni acts as a n-type dopant. Here we present the results of controlled doping of boron carbide with Ni on thin film samples grown using plasma enhanced chemical vapor deposition. The change in the dopant concentration within the thin film as a function of the dopant flow rate in the precursor gas mixture was confirmed by x-ray photoelectron spectroscopy measurements; with increasing dopant concentration, current-voltage (I-V) curves clearly establish the trend from p-type to n-type boron carbide.

  2. Ni{sub 3}Al technology transfer

    SciTech Connect

    Sikka, V.K.; Viswanathan, S.; Santella, M.L.

    1997-04-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, wire, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for: (1) high-strength castable composition for many applications that have been identified; (2) castability (mold type, fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) workability of cast or powder metallurgy product to sheet, bar, and wire. The four issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes the work completed to address some of these issues during FY 1996.

  3. CO adsorption on the Ni2Pb/Ni(1 1 1) surface alloy: A DFT study

    NASA Astrophysics Data System (ADS)

    Kośmider, K.; Kucharczyk, R.; Jurczyszyn, L.

    2013-02-01

    Structural and electronic properties of the Pb/Ni(1 1 1) overlayer and the Ni2Pb/Ni(1 1 1) surface alloy have been investigated within a DFT-PBE approach in order to determine its reactivity towards adsorption of CO molecules. This work has been motivated by a photoemission study of CO adsorption on Pb/Ni(1 1 1) surface phases [V. Matolín et al., Phys. Rev. B 74 (2006) 075416] indicating that Pb adatoms inhibit CO adsorption in a purely geometrical way by site blocking at Ni(1 1 1), whereas surface alloying has a poisoning effect of the Ni-CO bond weakening. In general, our DFT computations confirm experimental findings for the Pb/Ni(1 1 1) overlayer, as the very high activation barrier of about 2 eV due to the presence of Pb adatoms makes the CO chemisorption virtually impossible. For the Ni2Pb/Ni(1 1 1) surface alloy, we show that CO can bind to Ni atoms in the on-top position, and this process occurs to be exothermic with the energy gain of 0.35 eV per CO molecule. Dramatic reduction of the computed adsorption energy with respect to the pure Ni(1 1 1) substrate is in apparent agreement with experiment. However, it follows from our simulations that the CO adsorption process is accompanied by a substantial rearrangement of Ni atoms within the Ni2Pb surface alloy layer. Taking into account the associated deformation energy in the overall energetic balance yields nearly the same interaction energy between the CO molecules and the Ni atoms for the alloyed and the pure Ni(1 1 1) substrate, so the Ni-CO bond appears not to be weakened. The experimentally observed suppression of CO adsorption upon the alloy formation can be explained by a notable increase of the activation barrier for CO chemisorption from about 0.1 eV for the pure Ni(1 1 1) to roughly 0.5 eV for the Ni2Pb/Ni(1 1 1) surface alloy, affecting the corresponding reaction rate.

  4. Structural basis of a Ni acquisition cycle for [NiFe] hydrogenase by Ni-metallochaperone HypA and its enhancer

    PubMed Central

    Watanabe, Satoshi; Kawashima, Takumi; Nishitani, Yuichi; Kanai, Tamotsu; Wada, Takehiko; Inaba, Kenji; Atomi, Haruyuki; Imanaka, Tadayuki; Miki, Kunio

    2015-01-01

    The Ni atom at the catalytic center of [NiFe] hydrogenases is incorporated by a Ni-metallochaperone, HypA, and a GTPase/ATPase, HypB. We report the crystal structures of the transient complex formed between HypA and ATPase-type HypB (HypBAT) with Ni ions. Transient association between HypA and HypBAT is controlled by the ATP hydrolysis cycle of HypBAT, which is accelerated by HypA. Only the ATP-bound form of HypBAT can interact with HypA and induces drastic conformational changes of HypA. Consequently, upon complex formation, a conserved His residue of HypA comes close to the N-terminal conserved motif of HypA and forms a Ni-binding site, to which a Ni ion is bound with a nearly square-planar geometry. The Ni binding site in the HypABAT complex has a nanomolar affinity (Kd = 7 nM), which is in contrast to the micromolar affinity (Kd = 4 µM) observed with the isolated HypA. The ATP hydrolysis and Ni binding cause conformational changes of HypBAT, affecting its association with HypA. These findings indicate that HypA and HypBAT constitute an ATP-dependent Ni acquisition cycle for [NiFe]-hydrogenase maturation, wherein HypBAT functions as a metallochaperone enhancer and considerably increases the Ni-binding affinity of HypA. PMID:26056269

  5. Superparamagnetic behavior in ultrathin CoNi layers of electrodeposited CoNi/Cu multilayer nanowires

    NASA Astrophysics Data System (ADS)

    Tang, X.-T.; Wang, G.-C.; Shima, M.

    2006-06-01

    We present evidence that in a very thin regime the magnetic layers become discrete islands and superparamagnetic in multilayered CoNi(1-17 nm)/Cu(4.2 nm) nanowires grown by pulsed electrodeposition using a hole pattern of anodized alumina templates. Magnetic hysteresis loops measured at room temperature using a vibrating sample magnetometer show that superparamagnetism appears at t(CoNi)<1.7 nm, due to a volumetric reduction of the CoNi layers that may result in discontinuity of the layer or formation of islands. The magnetic hysteresis loops for the superparamagnetic nanowires can be represented by the Langevin function. The temperature dependence of coercivity data obtained for the superparamagnetic nanowires using a superconducting quantum interference device indicates that the magnetization reversal can be consistently explained by the Stoner-Walfarth model for coherent rotation. The volumetric reduction accounted for the observed superparamagnetism is probably due to an electrochemical exchange reaction between CoNi and Cu species at the interface during each Cu deposition cycle. The exchange reaction may cause partial dissolution of the CoNi layers at the interface which is eventually stabilized by cementation with Cu. The effects of the nucleation and growth process on the formation of superparamagnetic islands are also discussed.

  6. Tungsten inert gas (TIG) welding of Ni-rich NiTi plates: functional behavior

    NASA Astrophysics Data System (ADS)

    Oliveira, J. P.; Barbosa, D.; Braz Fernandes, F. M.; Miranda, R. M.

    2016-03-01

    It is often reported that, to successfully join NiTi shape memory alloys, fusion-based processes with reduced thermal affected regions (as in laser welding) are required. This paper describes an experimental study performed on the tungsten inert gas (TIG) welding of 1.5 mm thick plates of Ni-rich NiTi. The functional behavior of the joints was assessed. The superelasticity was analyzed by cycling tests at maximum imposed strains of 4, 8 and 12% and for a total of 600 cycles, without rupture. The superelastic plateau was observed, in the stress-strain curves, 30 MPa below that of the base material. Shape-memory effect was evidenced by bending tests with full recovery of the initial shape of the welded joints. In parallel, uniaxial tensile tests of the joints showed a tensile strength of 700 MPa and an elongation to rupture of 20%. The elongation is the highest reported for fusion-welding of NiTi, including laser welding. These results can be of great interest for the wide-spread inclusion of NiTi in complex shaped components requiring welding, since TIG is not an expensive process and is simple to operate and implement in industrial environments.

  7. Growth and characterization of epitaxial NiMnSb/ZnTe/NiMnSb magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Gerhard, F.; Naydenova, T.; Baussenwein, M.; Schumacher, C.; Gould, C.; Molenkamp, L. W.

    2016-02-01

    The half-metal ferromagnet NiMnSb, with its high spin polarization, low magnetic damping and tunable magnetic anisotropy, is a promising material for applications in spin torque devices. We develop the epitaxial growth of NiMnSb/ZnTe/NiMnSb heterostructures, aiming towards the realization of an all-NiMnSb based magnetic tunneling junction (MTJ). Layers are grown in situ by Molecular Beam Epitaxy (MBE) and Atomic Layer Epitaxy (ALE) methods. By tuning Mn content, the magnetic anisotropy of each of the two NiMnSb layers is adjusted in order to achieve mutually orthogonal uniaxial anisotropies. SQUID measurements of the magnetization along orthogonal crystal directions [110] and [ 1 1 bar 0] confirm that the two layers have mutually orthogonal anisotropy. High Resolution X-Ray Diffraction measurements and simulations confirm the nominal layer stack and demonstrate the high crystalline quality of the individual layers. Such layer stacks provide a potential basis for TMR-based spin-torque devices such as spin-torque oscillators.

  8. Comparative study on graphene growth mechanism using Ni films, Ni/Mo sheets, and Pt substrates

    NASA Astrophysics Data System (ADS)

    Lee, Byeong-Joo; Jeong, Goo-Hwan

    2014-07-01

    We demonstrate a comparative study on graphene growth mechanism using various catalytic metal substrates such as Ni thin films, Ni-deposited Mo (Ni/Mo) sheets, and Pt sheets during chemical vapor deposition (CVD). Depending on the substrates, two kinds of graphene growth mechanisms that involve either precipitation or surface adsorption of carbon have been reported. We synthesized graphene, focusing especially on the initial growth stage during CVD, by varying synthesis parameters such as synthesis time, amount of feedstock, and cooling rate after synthesis. We concluded that precipitation-driven synthesis is dominant in the case of Ni substrates whereas adsorption-driven growth is dominant in the Ni/Mo system. In the case of the Pt substrate, which is generally believed to grow by carbon precipitation, graphene growth by adsorption was found to be dominant. We believe that our results will contribute to a clearer understanding of the graphene synthesis mechanism, and development of manufacturing routes for controllable synthesis of high-quality graphenes.

  9. Porous Alumina Template by Selective Dissolution of Ni from Sintered Al2O3-Ni Composite

    NASA Astrophysics Data System (ADS)

    Jain, M.; Moon, A. P.; Mondal, K.

    2015-07-01

    In the present study, porous alumina template was fabricated by selective dissolution of Ni from the pressureless sintered Al2O3-Ni. Alumina and Ni powders of 99.9% purity were subjected to ball milling (200 rpm, 1 h, 10:1 ball-to-powder weight ratio) in order to get homogeneous mechanical mixture. The milled powder was compacted using hydraulic press under the uniaxial pressure of 400 MPa for 1 min, and the pressureless sintering was carried out in reducing atmosphere (H2) at 1400 °C. Ni was then selectively and completely dissolved from the 1-mm-thick sintered disk of diameter 16 mm in 1 M HCl + 3 wt.% FeCl3 solution to get the porous template of alumina. The porous alumina template was found to have sufficient compressive strength. BET, x-ray diffraction, optical microscopy, and scanning electron microscopy studies along with energy dispersive spectroscopy were performed to study microstructural evolutions, bonding characteristics, and distributions of Ni before and after the dissolution of the sintered composite.

  10. Evolution of Ni nanofilaments and electromagnetic coupling in the resistive switching of NiO.

    PubMed

    Luo, Yuxiang; Zhao, Diyang; Zhao, Yonggang; Chiang, Fu-kuo; Chen, Pengcheng; Guo, Minghua; Luo, Nannan; Jiang, Xingli; Miao, Peixian; Sun, Ying; Chen, Aitian; Lin, Zhu; Li, Jianqi; Duan, Wenhui; Cai, Jianwang; Wang, Yayu

    2015-01-14

    Resistive switching effect in conductor/insulator/conductor thin-film stacks is promising for resistance random access memory with high-density, fast speed, low power dissipation and high endurance, as well as novel computer logic architectures. NiO is a model system for the resistive switching effect and the formation/rupture of Ni nanofilaments is considered to be essential. However, it is not clear how the nanofilaments evolve in the switching process. Moreover, since Ni nanofilaments should be ferromagnetic, it provides an opportunity to explore the electromagnetic coupling in this system. Here, we report a direct observation of Ni nanofilaments and their specific evolution process for the first time by a combination of various measurements and theoretical calculations. We found that multi-nanofilaments are involved in the low resistance state and the nanofilaments become thin and rupture separately in the RESET process with subsequent increase of the rupture gaps. Theoretical calculations reveal the role of oxygen vacancy amount in the evolution of Ni nanofilaments. We also demonstrate electromagnetic coupling in this system, which opens a new avenue for multifunctional devices. PMID:25423124

  11. Ni-MH spent batteries: a raw material to produce Ni-Co alloys.

    PubMed

    Lupi, Carla; Pilone, Daniela

    2002-01-01

    Ni-MH spent batteries are heterogeneous and complex materials, so any kind of metallurgical recovery process needs a mechanical pre-treatment at least to separate irony materials and recyclable plastic materials (like ABS) respectively, in order to get additional profit from this saleable scrap, as well as minimize waste arising from the braking separation process. Pyrometallurgical processing is not suitable to treat Ni-MH batteries mainly because of Rare Earths losses in the slag. On the other hand, the hydrometallurgical method, that offers better opportunities in terms of recovery yield and higher purity of Ni, Co, and RE, requires several process steps as shown in technical literature. The main problems during leach liquor purification are the removal of elements such as Mn, Zn, Cd, dissolved during the leaching step, and the separation of Ni from Co. In the present work, the latter problem is overcome by co-deposition of a Ni-35/40%w Co alloy of good quality. The experiments carried out in a laboratory scale pilot-plant show that a current efficiency higher than 91% can be reached in long duration electrowinning tests performed at 50 degrees C and 4.3 catholyte pH. PMID:12423047

  12. Reentrant superconductivity in HoNi5-NbN-HoNi5 nanostructures

    NASA Astrophysics Data System (ADS)

    Singh, Gyanendra; Joshi, P. C.; Hossain, Z.; Budhani, R. C.

    2013-08-01

    Superconductivity (S) and ferromagnetism (F) are probed through transport and magnetization measurements in nanometer scale HoNi5-NbN (F-S) bilayers and HoNi5-NbN-HoNi5 (F-S-F) trilayers. The choice of materials has been made on the basis of their comparable ordering temperatures and strong magnetic anisotropy in HoNi5. We observe the normal state reentrant behavior in resistance vs. temperature plots of the F-S-F structures just below the superconducting transition in the limited range of HoNi5 layer thickness dHN (20\\ \\text{nm}) when d_{\\textit{NbN}} is fixed at{}\\simeq 10\\ \\text{nm} . The reentrance is quenched by increasing the out-of-plane (H_{\\perp} ) magnetic field and transport current where as in-plane (H_{\\parallel} ) field of \\leq 1500\\ \\text{Oe} has no effect on the reentrance. The origin of the reentrant behavior seen here in the range T_{\\textit{Curie}}/T_C \\leq 0.92 is attributed to a delicate balance between the magnetic exchange energy and the condensation energy in the interfacial regions of the trilayer.

  13. Multiatom Resonant Photoemission on NiO

    NASA Astrophysics Data System (ADS)

    Fadley, Charles; Mannella, Norman; Yang, See-Hun; Mun, Simon; van Hove, Michel

    2002-03-01

    In several recent papers, it has been pointed out that the core photoemission intensities of a given atom can be modified significantly when the photon energy is tuned through the absorption edge of a neighboring atom. Although some first experimental results of this type were distorted by detector non-linearity, a clear picture of the phenomenon has now emerged, with both macroscopic x-ray optical (dielectric) and microscopic quantum mechanical models quantitatively describing the effects [1]. In this talk, we will clarify a remaining experimental discrepancy with these models [2] by presenting new experimental results for O 1s photoemission from NiO(001) as photon energy is scanned through the Ni 2p absorption edges, and comparing the data to x-ray optical calculations. Other data for an adsorbate and free molecules will also be discussed. This work was supported by DOE contract No. DE-AC03-76SF00098. [1] A.W. Kay, F.J. Garcia de Abajo, S.-H. Yang, E. Arenholz, B.S. Mun, N. Mannella, Z. Hussain, M.A. Van Hove, and C.S. Fadley, Phys. Rev. B 63, 115119 (2001). [2] M. Finazzi, G. Ghiringhelli, O. Tjernberg, L. Duo, A. Tagliaferri, P. Ohresser, and N. B. Brookes, photoemission measurements for CuO and NiO, Phys. Rev. B 62, R16215 (2000).

  14. Laser ablation of Al-Ni alloys and multilayers

    NASA Astrophysics Data System (ADS)

    Roth, Johannes; Trebin, Hans-Rainer; Kiselev, Alexander; Rapp, Dennis-Michael

    2016-05-01

    Laser ablation of Al-Ni alloys and multilayers has been studied by molecular dynamics simulations. The method was combined with a two-temperature model to describe the interaction between the laser beam, the electrons, and the atoms. As a first step, electronic parameters for the alloys had to be found and the model developed originally for pure metals had to be generalized to multilayers. The modifications were verified by computing melting depths and ablation thresholds for pure Al and Ni. Here known data could be reproduced. The improved model was applied to the alloys Al_3Ni, AlNi and AlNi_3. While melting depths and ablation thresholds for AlNi behave unspectacular, sharp drops at high fluences are observed for Al_3Ni and AlNi_3. In both cases, the reason is a change in ablation mechanism from phase explosion to vaporization. Furthermore, a phase transition occurs in Al_3Ni. Finally, Al layers of various thicknesses on a Ni substrate have been simulated. Above threshold, 8 nm Al films are ablated as a whole while 24 nm Al films are only partially removed. Below threshold, alloying with a mixture gradient has been observed in the thin layer system.

  15. Electrodeposition Behavior of Mn with Ni in Acidic Sulfate Solutions

    NASA Astrophysics Data System (ADS)

    Ji, Dan; Le, Xiawen; Zhong, Qingdong; Zhou, Qiongyu

    2014-09-01

    The influence of Mn2+/Ni2+ mole ratio in electrolytes on the Ni-Mn alloy deposits was studied. The electrodeposition mechanism of Mn with Ni is analyzed by the cyclic voltammogram (CV) and an "induced co-deposition" mechanism is proposed for Ni-Mn alloy electrodeposition. The results show that the Mn content in Ni-Mn alloy deposit and the hardness increased with the increase of Mn2+/Ni2+ mole ratio in electrolytes. When the Mn2+/Ni2+ mole ratio in bath was 2/1, the corrosion current density of the deposit coating was the lowest and the corresponding corrosion potential was higher, and under these conditions the coating with a Mn content of 1.20 wt.% showed good corrosion resistance. The scanning electron microscopy (SEM) of the alloy coatings exhibited that the morphology of Ni-Mn alloy coatings were different from Pure Ni coating, and when Mn2+/Ni2+ was 2/1, the surface was compact and homogeneous.

  16. Measurement of {sup 63}Ni and {sup 59}Ni by accelerator mass spectrometry using characteristic projectile x-rays

    SciTech Connect

    McAninch, J.E.; Hainsworth, L.J.; Marchetti, A.A.

    1996-05-01

    The long-lived isotopes of nickel ({sup 59}Ni, {sup 63}Ni) have current and potential use in a number of applications including cosmic radiation studies, biomedical tracing, characterization of low-level radioactive wastes, and neutron dosimetry. Methods are being developed at LLNL for the routine detection of these isotopes by AMS. One intended application is in Hiroshima dosimetry. The reaction {sup 63}Cu(n,p){sup 63}Ni has been identified as one of a small number of reactions which might be used for the direct determination of the fast neutron fluence emitted by the Hiroshima bomb. AMS measurement of {sup 63}Ni(t{sub 1/2} = 100 y) requires the chemical removal of {sup 63}Cu, which is a stable isobar of {sup 63}Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 x 10{sup -8} (Cu/Ni) using the reaction of Ni with carbon monoxide to form the gas Ni(CO){sub 4}. The Ni(CO){sub 4} is thermally decomposed directly in sample holders for measurement by AMS. After analysis in the AMS spectrometer, the ions are identified using characteristic projectile x-rays, allowing further rejection of remaining {sup 63}Cu. In a demonstration experiment, {sup 63}Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a {sup 252}Cf source. We successfully measured {sup 63}Ni at levels necessary for the measurement of Cu samples exposed near the Hiroshima hypocenter. For the demonstration samples, the Cu content was chemically reduced by a factor of 10{sup 12} with quantitative retention of {sup 63}Ni. Detection sensitivity (3{sigma}) was {approximately}20 fg {sup 63}Ni in 1 mg Ni carrier ({sup 63}Ni/Ni {approx} 2 x 10{sup -11}). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for {sup 59}Ni (t{sub 1/2} = 10{sup 5} y).

  17. Measurement of 63Ni and 59Ni by accelerator mass spectrometry using characteristic projectile X-rays

    NASA Astrophysics Data System (ADS)

    McAninch, J. E.; Hainsworth, L. J.; Marchetti, A. A.; Leivers, M. R.; Jones, P. R.; Dunlop, A. E.; Mauthe, R.; Vogel, J. S.; Proctor, I. D.; Straume, T.

    1997-03-01

    The long-lived isotopes of nickel (59Ni, 63Ni) have current and potential use in a number of applications including cosmic radiation studies, biomedical tracing, characterization of low-level radioactive wastes, and neutron dosimetry. Methods are being developed at LLNL for the routine detection of these isotopes by AMS. One intended application is in Hiroshima dosimetry. The reaction 63Cu(n,p)63Ni has been identified as one of a small number of reactions which might be used for the direct determination of the fast neutron fluence emitted by the Hiroshima bomb. AMS measurement of 63Ni (t{1}/{2} = 100 y) requires the chemical removal of 63Cu, which is a stable isobar of 63Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 × 10-8 ({Cu}/{Ni}) using the reaction of Ni with carbon monoxide to form the gas Ni(CO)4. The Ni(CO)4 is thermally decomposed directly in sample holders for measurement by AMS. After analysis in the AMS spectrometer, the ions are identified using characteristic projectile X-rays, allowing further rejection of remaining 63Cu. In a demonstration experiment, 63Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a 252Cf source. We successfully measured 63Ni at levels necessary for the measurement of Cu samples exposed near the Hiroshima hypocenter. For the demonstration samples, the Cu content was chemically reduced by a factor of 1012 with quantitative retention of 63Ni. Detection sensitivity (3σ) was ˜ 20 fg 63Ni in 1 mg Ni carrier ({63Ni}/{Ni} ≈ 2 × 10-11). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for 59Ni (t{1}/{2} = 105 y). Initial work has been undertaken on the application of this isotope as a biomedical tracer in living systems.

  18. Spray forming of NiTi and NiTiPd shape-memory alloys

    NASA Astrophysics Data System (ADS)

    Smith, Ronald; Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-03-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  19. Spray Forming of NiTi and NiTiPd Shape-Memory Alloys

    NASA Technical Reports Server (NTRS)

    Mabe, James; Ruggeri, Robert; Noebe, Ronald

    2008-01-01

    In the work to be presented, vacuum plasma spray forming has been used as a process to deposit and consolidate prealloyed NiTi and NiTiPd powders into near net shape actuators. Testing showed that excellent shape memory behavior could be developed in the deposited materials and the investigation proved that VPS forming could be a means to directly form a wide range of shape memory alloy components. The results of DSC characterization and actual actuation test results will be presented demonstrating the behavior of a Nitinol 55 alloy and a higher transition temperature NiTiPd alloy in the form of torque tube actuators that could be used in aircraft and aerospace controls.

  20. Sorption properties of new composite materials suitable for radioanalytical determination of 59Ni and 63Ni

    NASA Astrophysics Data System (ADS)

    Fišera, O.; Šebesta, F.

    2006-01-01

    Results of the study of new and cheaper composite materials for selective separation and radioanalytical determination of radionickel (59,63Ni) in radioactive waste are presented in this work. Chelating agents dimethylglyoxime (DMG) and diphenylglyoxime (DPG) as active components were immobilized in porous matrix of binding polymer polyacrylonitrile (PAN). Sorption properties of these materials were compared with commercial Ni Resin (Eichrom Technologies, USA). Weight distribution ratios, sorption kinetics and operating capacities were investigated during the experiments performed. The highest weight distribution ratios were found for the material DPG-PAN. The sorbent DMG-PAN has the highest operating capacity. The fastest kinetics of nickel sorption was determined for the Ni Resin. Elution of nickel with nitric acid solution allows subsequent and direct determination of radionickel by liquid scintillation counting.

  1. Local structure study of Fe dopants in Ni-deficit Ni3Al alloys

    DOE PAGESBeta

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; Lei, Hechang; Li, Lijun; Cekic, B.; Koteski, V.; Petrovic, C.

    2015-08-24

    We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor Vzz=1.6 1021Vm-2 matches well with the results of Mössbauer spectroscopymore » and indicates that the Fe atoms occupy Ni sites.« less

  2. Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: an experimental and mechanistic modeling study.

    PubMed

    Regelink, Inge C; Temminghoff, Erwin J M

    2011-03-01

    Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At pH ≥ 7.2 both adsorption and Ni-Al LDH precipitation occurred. In batch experiments with the sandy soil up to 70% of oxalate-extractable Al was taken up in LDH formation during 56 days. In a long term column experiment 99% of influent Ni was retained at pH 7.5 due to Ni adsorption (≈ 34%) and Ni-Al LDH precipitation (≈ 66%) based on mechanistic reactive transport modeling. The subsequent leaching at pH 6.5 could be largely attributed to desorption. Our results show that even in sandy aquifers with relatively low Al content, Ni-Al LDH precipitation is a promising mechanism to immobilize Ni. PMID:21186070

  3. Martensitic transformation of FeNi nanofilm induced by interfacial stress generated in FeNi/V nanomultilayered structure

    PubMed Central

    2014-01-01

    FeNi/V nanomultilayered films with different V layer thicknesses were synthesized by magnetron sputtering. By adjusting the thickness of the V layer, different interfacial compressive stress were imposed on FeNi layers and the effect of interfacial stress on martensitic transformation of the FeNi film was investigated. Without insertion of V layers, the FeNi film exhibits a face-centered cubic (fcc) structure. With the thickness of V inserted layers up to 1.5 nm, under the coherent growth structure in FeNi/V nanomultilayered films, FeNi layers bear interfacial compressive stress due to the larger lattice parameter relative to V, which induces the martensitic transformation of the FeNi film. As the V layer thickness increases to 2.0 nm, V layers cannot keep the coherent growth structure with FeNi layers, leading to the disappearance of interfacial compressive stress and termination of the martensitic transformation in the FeNi film. The interfacial compressive stress-induced martensitic transformation of the FeNi nanofilm is verified through experiment. The method of imposing and modulating the interfacial stress through the epitaxial growth structure in the nanomultilayered films should be noticed and utilized. PMID:25232296

  4. Effect of metal ion concentration in Ni-W plating solution on surface roughness of Ni-W film

    NASA Astrophysics Data System (ADS)

    Yasui, Manabu; Kaneko, Satoru; Kurouchi, Masahito; Ito, Hiroaki; Ozawa, Takeshi; Arai, Masahiro

    2016-01-01

    Since nanopatterns are used for various purposes including solar cells, super-hydrophilicity, and biosensors, it is necessary to miniaturize the patterns on glass devices from micro- to nano-order. We have studied glass imprinting as an excellent microfabrication technology for glass devices. Uniformity of the nanopattern height is required for a mold, since a nodular structure on the Ni-W surface is recognized as a problem in Ni-W nanopattern formation. We confirmed that the Ni-W plating bath increasing metal ion concentration is effective for inhibition of the nodular structure on the Ni-W film, and succeeded in Ni-W nano pattern formation with uniform height. However, the W content rate of plated Ni-W film was reduced in exchange for enhancing the flatness of the Ni-W film. It is necessary to examine the Ni-W plating condition for obtaining planarization of the Ni-W surface and a high content rate of W in the Ni-W film.

  5. Fabrication and catalytic activity of FeNi@Ni nanocables for the reduction of p-nitrophenol.

    PubMed

    Zhou, Linyi; Wen, Ming; Wu, Qingsheng; Wu, Dandan

    2014-06-01

    Magnetic FeNi@Ni nanocables were prepared as a superior recyclable catalyst towards the hydrogenation reduction of p-nitrophenol to p-aminophenol through a two-step tunable assembly process in a solvothermal system. The proposed fabrication mechanism was verified through characterization by SEM, TEM, XRD, XPS, and UV-Vis. The as-prepared FeNi@Ni nanocomposites are core-shell-structured nanocables with Ni nanoparticles (NPs) attached on FeNi nanorods (NRs) surface loosely. The catalytic reactivity monitored by means of a UV-vis dynamic process shows FeNi@Ni nanocables can catalyse the transformation of p-nitrophenol to p-aminophenol completely under an ambient atmosphere at room temperature, and enable the catalysis to be more efficient than its counterparts FeNi NRs and Ni NPs due to the interfacial synergistic effect. Additionally, the resultant hierarchical metal-alloy nanocomposites possess ferromagnetic behaviour, and can be easily separated and recycled by an external magnet field for application. PMID:24714959

  6. NiO-Microflower Formed by Nanowire-weaving Nanosheets with Interconnected Ni-network Decoration as Supercapacitor Electrode

    NASA Astrophysics Data System (ADS)

    Ci, Suqing; Wen, Zhenhai; Qian, Yuanyuan; Mao, Shun; Cui, Shumao; Chen, Junhong

    2015-07-01

    We propose a ‘weaving’ evolution mechanism, by systematically investigating the products obtained in controlled experiments, to demonstrate the formation of Ni-based ‘microflowers’ which consists of multiple characteristic dimensions, in which the three dimensional (3D) NiO ‘microflower’ is constructed by a two-dimensional (2D) nanosheet framework that is derived from weaving one-dimensional (1D) nanowires. We found such unique nanostructures are conducive for the generation of an electrically conductive Ni-network on the nanosheet surface after being exposed to a reducing atmosphere. Our study offers a promising strategy to address the intrinsic issue of poor electrical conductivity for NiO-based materials with significant enhancement of utilization of NiO active materials, leading to a remarkable improvement in the performance of the Ni-NiO microflower based supercapacitor. The optimized Ni-NiO microflower material showed a mass specific capacitance of 1,828 F g-1, and an energy density of 15.9 Wh kg-1 at a current density of 0.5 A g-1. This research not only contributes to understanding the formation mechanism of such ‘microflower’ structures but also offers a promising route to advance NiO based supercapacitor given their ease of synthesis, low cost, and long-term stability.

  7. Dealloying NiCo and NiCoCu Alloy Thin Films Using Linear Sweep Voltammetry

    NASA Astrophysics Data System (ADS)

    Peecher, Benjamin; Hampton, Jennifer

    When electrodeposited into thin films, metals have well-known electrochemical potentials at which they will be removed from the film. These potential differences can be utilized to re-oxidize only certain metals in an alloy, altering the film's structure and composition. Here we discuss NiCo and NiCoCu thin films' response to linear sweep voltammetry (LSV) as a means of electrochemical dealloying. For each of four different metal ratios, films were dealloyed to various potentials in order to gain insight into the evolution of the film over the course of the LSV. Capacitance, topography, and composition were examined for each sample before and after linear sweep voltammetry was performed. For NiCo films with high percentages of Ni, dealloying resulted in almost no change in composition, but did result in an increased capacitance, with greater increases occurring at higher LSV potentials. Dealloying also resulted in the appearance of large (100-1000 nm) pores on the surface of the film. For NiCoCu films with high percentages of Ni, Cu was almost completely removed from the film at LSV potentials greater than 500 mV. The LSV first removed larger copper-rich dendrites from the film's surface before creating numerous nano-pores, resulting in a net increase in area. This work is supported by an Award to Hope College from the HHMI Undergraduate Science Education Program, the Hope College Department of Physics Frissel Research Fund, and the National Science Foundation under Grants RUI-DMR-1104725 and MRI-CHE-0959282.

  8. NiW and NiRu Bimetallic Catalysts for Ethylene Steam Reforming: Alternative Mechanisms for Sulfur Resistance

    SciTech Connect

    Rangan, M.; Yung, M. M.; Medlin, J. W.

    2012-06-01

    Previous investigations of Ni-based catalysts for the steam reforming of hydrocarbons have indicated that the addition of a second metal can reduce the effects of sulfur poisoning. Two systems that have previously shown promise for such applications, NiW and NiRu, are considered here for the steam reforming of ethylene, a key component of biomass derived tars. Monometallic and bimetallic Al{sub 2}O{sub 3}-supported Ni and W catalysts were employed for ethylene steam reforming in the presence and absence of sulfur. The NiW catalysts were less active than Ni in the absence of sulfur, but were more active in the presence of 50 ppm H{sub 2}S. The mechanism for the W-induced improvements in sulfur resistance appears to be different from that for Ru in NiRu. To probe reasons for the sulfur resistance of NiRu, the adsorption of S and C{sub 2}H{sub 4} on several bimetallic NiRu alloy surfaces ranging from 11 to 33 % Ru was studied using density functional theory (DFT). The DFT studies reveal that sulfur adsorption is generally favored on hollow sites containing Ru. Ethylene preferentially adsorbs atop the Ru atom in all the NiRu (111) alloys investigated. By comparing trends across the various bimetallic models considered, sulfur adsorption was observed to be correlated with the density of occupied states near the Fermi level while C{sub 2}H{sub 4} adsorption was correlated with the number of unoccupied states in the d-band. The diverging mechanisms for S and C{sub 2}H{sub 4} adsorption allow for bimetallic surfaces such as NiRu that enhance ethylene binding without accompanying increases in sulfur binding energy. In contrast, bimetallics such as NiSn and NiW appear to decrease the affinity of the surface for both the reagent and the poison.

  9. Novel gold nanocluster electrochemiluminescence immunosensors based on nanoporous NiGd-Ni2O3-Gd2O3 alloys.

    PubMed

    Lv, Xiaohui; Ma, Hongmin; Wu, Dan; Yan, Tao; Ji, Lei; Liu, Yixin; Pang, Xuehui; Du, Bin; Wei, Qin

    2016-01-15

    Herein, three-dimensional nanoporous NiGd alloy (NP-NiGd) was prepared by selectively dealloy Al from NiGdAl alloy in mild alkaline solution, then Ni2O3 and Gd2O3 grew further on the surface of NP-NiGd to obtain the NP-NiGd-Ni2O3-Gd2O3. On this basis, NP-NiGd-Ni2O3-Gd2O3 was further functionalized with gold nanoparticles (NP-NiGd-Ni2O3-Gd2O3@Au) and acted as sensor platform to fabricate a novel electrochemiluminescence (ECL) immunosensor. Bovine serum albumin protected gold nanoclusters (AuNCs@BSA) were prepared and acted as illuminant. AuNCs@BSA modified graphene oxide (GO/AuNCs@BSA) were used as labels of second antibody. In order to characterize the performance of the ECL immunosensor, carcino embryonie antigen (CEA) was used as the model to complete the experiments. Due to the good performances of NP-NiGd-Ni2O3-Gd2O3@Au (high surface area, excellent electron conductivity) and AuNCs@BSA (low toxicity, biocompatibility, easy preparation and good water solubility), the ECL immunosensor exhibited a wide range from 10(-4) to 5ng/mL with a detection limit of 0.03pg/mL (S/N=3). The immunosensor with excellent stability, acceptable repeatability and selectivity provided a promising method to detect CEA in human serum sample sensitively. PMID:26318782

  10. High areal capacitance three-dimensional Ni@Ni(OH)2 foams via in situ oxidizing Ni foams in mild aqueous solution

    NASA Astrophysics Data System (ADS)

    Zhou, Qingfeng; Cui, Mangwei; Tao, Keyu; Yang, Yongzhen; Liu, Xuguang; Kang, Litao

    2016-03-01

    In this work, commercial Ni foams are directly oxidized into Ni@Ni(OH)2 foams in a mild NH4NO3 solution at 80 °C. When used as binder-free electrodes, these Ni@Ni(OH)2 electrodes demonstrate a high areal capacitance of 6.4 F/cm2 at a current density of 2.5 mA/cm2, or 1.62 F/cm2 at a high current density of 30 mA/cm2. Nevertheless, they show a poor cycling ability with 70.4% (or 42%) capacitance retention after 2000 (or 5000) cycles at 30 mA/cm2. This kind of electrodes has a promising application in low-cost, high-performance supercapacitor, if an effective strategy is found to improve their cycling ability.

  11. Temperature-induced sign change of the magnetic interlayer coupling in Ni/Ni25Mn75/Ni trilayers on Cu3Au(001)

    NASA Astrophysics Data System (ADS)

    Shokr, Y. A.; Erkovan, M.; Wu, C.-B.; Zhang, B.; Sandig, O.; Kuch, W.

    2015-05-01

    We investigated the magnetic interlayer coupling between two ferromagnetic (FM) Ni layers through an antiferromagnetic (AFM) Ni25Mn75 layer and the influence of this coupling on the exchange bias phenomenon. The interlayer coupling energy of an epitaxial trilayer of 14 atomic monolayers (ML) Ni/45 ML Ni25Mn75/16 ML Ni on Cu3Au(001) was extracted from minor-loop magnetization measurements using in-situ magneto-optical Kerr effect. The interlayer coupling changes from ferromagnetic to antiferromagnetic when the temperature is increased above 300 K. This sign change is interpreted as the result of the competition between an antiparallel Ruderman-Kittel-Kasuya-Yosida (RKKY)-type interlayer coupling, which dominates at high temperature, and a stronger direct exchange coupling across the AFM layer, which is present only below the Néel temperature of the AFM layer.

  12. Gate-tunable large negative tunnel magnetoresistance in Ni-C60-Ni single molecule transistors.

    PubMed

    Yoshida, Kenji; Hamada, Ikutaro; Sakata, Shuichi; Umeno, Akinori; Tsukada, Masaru; Hirakawa, Kazuhiko

    2013-02-13

    We have fabricated single C(60) molecule transistors with ferromagnetic Ni leads (FM-SMTs) by using an electrical break junction method and investigated their magnetotransport. The FM-SMTs exhibited clear gate-dependent hysteretic tunnel magnetoresistance (TMR) and the TMR values reached as high as -80%. The polarity of the TMR was found to be always negative over the entire bias range studied here. Density functional theory calculations show that hybridization between the Ni substrate states and the C(60) molecular orbitals generates an antiferromagnetic configuration in the local density of states near the Fermi level, which gives a reasonable explanation for the observed negative TMR. PMID:23327475

  13. Transmutation-induced embrittlement of V-Ti-Ni and V-Ni alloys in HFIR

    SciTech Connect

    Ohnuki, S.; Takahashi, H.; Garner, F.A.; Pawel, J.E.

    1996-04-01

    Vanadium, V-1Ni, V-10Ti and V-10Ti-1Ni (at %) were irradiated in HFIR to doses ranging from 18 to 30 dpa and temperatures between 300 and 600C. Since the irradiation was conducted in a highly thermalized neutron spectrum without shielding against thermal neutrons, significant levels of chromium (15-22%) were formed by transmutation. The addition of such large chromium levels strongly elevated the ductile to brittle transition temperature. At higher irradiation temperatures radiation-induced segregation of transmutant Cr and solute Ti at specimen surfaces leads to strong increases in the density of the alloy.

  14. Enhanced diffusion welding of TD-NiCr sheet.

    NASA Technical Reports Server (NTRS)

    Holko, K. H.; Moore, T. J.

    1972-01-01

    A method termed 'enhanced diffusion welding' has been developed to produce solid-state welds in TD-NiCr (Ni-20Cr-2ThO2) alloy sheet with weld strengths of 100% of the parent metal strength. Diffusion welded joints were made in specially processed TD-NiCr that equaled the tensile-shear and creep-rupture shear strengths of the parent material at 1090 deg C. The following observations have been made: specially processed TD-NiCr is preferred over commercial TD-NiCr for diffusion welding; the weld line can be eliminated when joining specially processed TD-NiCr by 600-grit sanding and electropolishing the faying surfaces prior to welding; and, a two-step weld cycle is preferred for diffusion welding of this alloy.

  15. Study of surfactant mediated growth of Ni/V superlattices

    SciTech Connect

    Amir, S. M.; Gupta, Mukul; Potdar, Satish; Gupta, Ajay; Stahn, Jochen

    2013-07-14

    The Ni/V multilayers are useful as soft x-ray mirrors, polarizers, and phase retarders. For these applications, it is necessary that the interfaces roughness and interdiffusion must be as small as possible. The V-on-Ni and Ni-on-V interfaces are asymmetric due to the difference in the surface free energy of Ni and V. In this work, we report Ag surfactant mediated growth of Ni/V superlattices prepared using ion beam sputter deposition technique. These superlattices were studied using x-ray and neutron scattering techniques. It was found that when added in an optimum amount, Ag surfactant results in reduced interface roughness and interdiffusion across the interfaces. Obtained results can be understood with the surfactant floating-off mechanism leading to a balance in the surface free energy of Ni and V.

  16. Resistance Switching Behavior in Epitaxially Grown NiO

    NASA Astrophysics Data System (ADS)

    Lee, S. R.; Bak, J. H.; Park, Y. D.; Char, K.; Kim, D. C.; Jung, R.; Seo, S.; Li, X. S.; Park, G.-S.; Yoo, I. K.

    2008-03-01

    Reproducible resistance switching behavior has been found in NiO films prepared by a pulsed laser deposition system. The I-V measurements of epitaixally grown NiO on SrRuO3 electrode show a bipolar resistive memory switching behavior, in contrast with a unipolar switching behavior of polycrystalline NiO on Pt electrode. In order to understand the resistive memory switching mechanism in NiO, the I-V characteristics and memory switching property of epitaxial NiO prepared under various synthesis conditions and electrodes has been investigated. The IV measurements at room temperature suggest that the interface between NiO and the electrode plays an important role on the resistive switching phenomena. To analyze the role of the interface, our efforts to control the interfaces and to measure the I-V characteristics at low temperature will be presented.

  17. Model study of CO inhibition of [NiFe]hydrogenase.

    PubMed

    Matsumoto, Takahiro; Kabe, Ryota; Nonaka, Kyoshiro; Ando, Tatsuya; Yoon, Ki-Seok; Nakai, Hidetaka; Ogo, Seiji

    2011-09-19

    We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H(2)ase) by CO. We present a model study, using a NiRu H(2)ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the Ru(II) center rather than taking an axial position on the Ni(II) center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H(2)ase by complexing to the Fe(II) center. PMID:21853978

  18. Facile in situ synthesis of hierarchical porous Ni/Ni(OH)₂ hybrid sponges with excellent electrochemical energy-storage performances for supercapacitors.

    PubMed

    Wang, Wanren; Wang, Wenhua; Wang, Mengjiao; Guo, Xiaohui

    2014-09-01

    Herein, we report the in situ growth of single-crystalline Ni(OH)2 nanoflakes on a Ni support by using facile hydrothermal processes. The as-prepared Ni/Ni(OH)2 sponges were well-characterized by using X-ray diffraction (XRD), SEM, TEM, and X-ray photoelectron spectroscopy (XPS) techniques. The results revealed that the nickel-skeleton-supported Ni(OH)2 rope-like aggregates were composed of numerous intercrossed single-crystal Ni(OH)2 flake-like units. The Ni/Ni(OH)2 hybrid sponges served as electrodes and displayed ultrahigh specific capacitance (SC=3247 F g(-1)) and excellent rate-capability performance, likely owing to fast electron and ion transport, sufficient Faradic redox reaction, and robust structural integrity of the Ni/Ni(OH)2 hybrid electrode. These results support the promising application of Ni(OH)2 nanoflakes as advanced pseudocapacitor materials. PMID:25048538

  19. NiAl-based Polyphase in situ Composites in the NiAl-Ta-X (X = Cr, Mo, or V) Systems

    NASA Technical Reports Server (NTRS)

    Johnson, D. R.; Oliver, B. F.; Noebe, R. D.; Whittenberger, J. D.

    1995-01-01

    Polyphase in situ composites were generated by directional solidification of ternary eutectics. This work was performed to discover if a balance of properties could be produced by combining the NiAl-Laves phase and the NiAl-refractory metal phase eutectics. The systems investigated were the Ni-Al-Ta-X (X = Cr, Mo, or V) alloys. Ternary eutectics were found in each of these systems and the eutectic composition, temperature, and morphology were determined. The ternary eutectic systems examined were the NiAl-NiAlTa-(Mo, Ta), NiAl-(Cr, Al) NiTa-Cr, and the NiAl-NiAlTa-V systems. Each eutectic consists of NiAl, a C14 Laves phase, and a refractory metal phase. Directional solidification was performed by containerless processing techniques in a levitation zone refiner to minimize alloy contamination. Room temperature fracture toughness of these materials was determined by a four-point bend test. Preliminary creep behavior was determined by compression tests at elevated temperatures, 1100-l400 K. Of the ternary eutectics, the one in the NiAl-Ta-Cr system was found to be the most promising. The fracture toughness of the NiAl-(Cr, Al)NiTa-Cr eutectic was intermediate between the values of the NiAl-NiAlTa eutectic and the NiAl-Cr eutectic. The creep strength of this ternary eutectic was similar to or greater than that of the NiAl-Cr eutectic.

  20. Conducting Ni nanoparticles in an ion-modified polymer

    SciTech Connect

    Sze, J.Y.; Tay, B.K.; Pakes, C.I.; Jamieson, D.N.; Prawer, S.

    2005-09-15

    Conductive-atomic force microscopy has been used to perform nanoscale current imaging of Ni-ion-implanted polythylene terephthlate films. A reduction in bulk sheet resistivity, as the Ni dose is increased, is found to be accompanied by an evolution in local conductivity from a spatially homogeneous insulator to an interconnected network of conducting Ni crystallites. The crystallites have a mean dimension of 12.3 nm, confirmed by x-ray-diffraction analysis.

  1. Enhanced Noble Gas Adsorption in Ag@MOF-74Ni

    SciTech Connect

    Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.

    2014-01-14

    Various amounts of Ag nanoparticles were successfully deposited in porous MOF-74Ni (or Ni/DOBDC) with an auto-reduction method. An optimized silver-loaded MOF-74Ni was shown to have an improved Xe adsorption capacity (15% more) at STP compared to the MOF without silver nanoparticles. The silver-loaded sample also has a higher Xe/Kr selectivity. These results are explained by the stronger interactions between polarizable Xe molecules and the well-dispersed Ag nanoparticles.

  2. Euhedral metallic-Fe-Ni grains in extraterrestrial samples

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1993-01-01

    Metallic Fe-Ni is rare in terrestrial rocks, being largely restricted to serpentinized peridotites and volcanic rocks that assimilated carbonaceous material. In contrast, metallic Fe-Ni is nearly ubiquitous among extraterrestrial samples (i.e., meteorites, lunar rocks, and interplanetary dust particles). Anhedral grains are common. For example, in eucrites and lunar basalts, most of the metallic Fe-Ni occurs interstitially between silicate grains and thus tends to have irregular morphologies. In many porphyritic chondrules, metallic Fe-Ni and troilite form rounded blebs in the mesostasis because their precursors were immiscible droplets. In metamorphosed ordinary chondrites, metallic Fe-Ni and troilite form coarse anhedral grains. Some of the metallic Fe-Ni and troilite grains has also been mobilized and injected into fractures in adjacent silicate grains where local shock-reheating temperatures reached the Fe-FeS eutectic (988 C). In interplanetary dust particles metallic Fe-Ni most commonly occurs along with sulfide as spheroids and fragments. Euhedral metallic Fe-Ni grains are extremely rare. Several conditions must be met before such grains can form: (1) grain growth must occur at free surfaces, restricting euhedral metallic Fe-Ni grains to systems that are igneous or undergoing vapor-deposition; (2) the metal (+/-) sulfide assemblage must have an appropriate bulk composition so that taenite is the liquidus phase in igneous systems or the stable condensate phase in vapor-deposition systems; and (3) metallic Fe-Ni grains must remain underformed during subsequent compaction, thermal metamorphism, and shock. Because of these restrictions, the occurrence of euhedral metallic Fe-Ni grains in an object can potentially provide important petrogenetic information. Despite its rarity, euhedral metallic Fe-Ni occurs in a wide variety of extraterrestrial materials. Some of these materials formed in the solar nebula; others formed on parent body surfaces by meteoroid

  3. Multicoloured electrochromic thin films of NiO/PANI

    NASA Astrophysics Data System (ADS)

    Sonavane, A. C.; Inamdar, A. I.; Deshmukh, H. P.; Patil, P. S.

    2010-08-01

    NiO/polyaniline (PANI) thin films have been prepared by a two-step process. NiO thin films were electrodeposited from an aqueous solution of NiCl2 · 6H2O at pH 7.5 on fluorine-doped tin oxide coated glass substrates and a layer of PANI was formed on NiO thin films by chemical bath deposition. The films were characterized for their structural, optical, morphological and electrochromic properties. X-ray diffraction and Fourier-transform infrared spectroscopy indicated the formation of NiO and PANI, in which NiO is of cubic structure. Scanning electron micrographs represent porous granular NiO, which get uniformly carpeted with PANI, leading to a matty morphology of NiO/PANI samples. The electrochromic performance of NiO/PANI films has been studied using cyclic voltammetry and chronoamperometry over the -1.2 to +2.2 V (versus saturated calomel electrode (SCE)) potential window in 1M LiClO4 + propylene carbonate. The NiO/PANI films exhibit electrochromism with colour that changes from pale yellow (leucoemeraldine base at -0.7 V versus SCE) to dark green (emeraldine salt at 0.4 V versus SCE) to purple (pernigraniline at 0.8 V versus SCE) in the reduced states and dark blue (nigraniline at 0.5 V versus SCE) to dark green (emeraldine salt at 0.1 V versus SCE) to light green (photoemeraldine at -0.3 V versus SCE) in its oxidized states. These colours, though akin to pure PANI, have higher contrast, high speed of operation and high stability, owing to the properties of NiO. The colouration efficiency of the NiO/PANI film was estimated to be 85 cm2 C-1.

  4. Shock induced reaction of Ni/Al nanopowder mixture.

    PubMed

    Meng, C M; Wei, J J; Chen, Q Y

    2012-11-01

    Nanopowder Ni/Al mixture (mixed in Al:Ni = 2:1 stoichiometry) was shock compressed by employing single and two-stage light gas gun. The particle size of Al and Ni are 100-200 nm and 50-70 nm respectively, morphologies of Al and Ni are sphere like either. Recovered product was characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD) analysis. According to the XRD spectrum, the mixed powder undergo complete reaction under shock compression, reaction product consist of Ni2Al3, NiAl and corundum structure Al2O3 compound. Grain size of Ni-Al compound is less than 100 nm. With the shock pressure increasing, the ratio of Ni2Al3 decreased obviously. The corundum crystal size is 400-500 nm according to the SEM observation. The results of shock recovery experiments and analysis show that the threshold pressure for reaction of nano size powder Ni/Al mixture is much less than that of micro size powder. PMID:23421276

  5. Ni-WC/C nanocluster catalysts for urea electrooxidation

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Li, Mingtao; Huang, Zhiyu; Li, Yingming; Qi, Suitao; Yi, Chunhai; Yang, Bolun

    2014-10-01

    A nanocluster Ni-WC/C electrocatalyst is prepared through a sequential impregnation method and is used for the urea electrooxidation in alkaline conditions. The micro-morphology, lattice parameter, composition and surface states of Ni-WC/C particles are determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and X-ray photoelectron spectrometry (XPS) analysis. The electrooxidation activity and stability of the Ni-WC/C catalyst are also investigated by cyclic voltammograms and chronoamperograms. Characterization results indicate that the Ni nanoclusters are uniformly distributed on the WC/C framework, and the Ni-WC/C catalyst shows high electrocatalytic activity and stability for urea electrooxidation. The maximum current density at the Ni-WC/C electrode is almost 700 mA cm-2 mg-1 which is one order of magnitude higher than that at the Ni/C electrode, and the steady current density at the Ni-WC/C electrode is also markedly improved. Furthermore, the ESA values and XPS spectra indicate that the enhanced performance of the Ni-WC/C catalyst could be attributed to the structure effect and electron effect between nickel and tungsten carbide.

  6. Phase transformation controlled tetragonality of MnNi-based nanocrystals

    NASA Astrophysics Data System (ADS)

    Shen, Jian; Dai, Qilin; Ren, Shenqiang

    2016-03-01

    The phase transformation controlled tetragonality of MnNi nanostructures has attracted wide interest for their shape memory effect. In this study, MnNi nanocrystals were selected to epitaxially grow an FeCo shell, where the antiferromagnetic L10 phase transformation of the MnNi core triggers the tetragonal distortion in the magnetically soft FeCo shell. The tetragonality change of L10 MnNi under thermal annealing enables the control of the tetragonality of the FeCo phase, ultimately increasing magnetocrystalline anisotropy and coercivity. This study opens up a new route to fabricate functional nanostructures with unique magnetic properties.

  7. An Exploration of Catalytic Chemistry on Au/Ni(111)

    SciTech Connect

    Sylvia T. Ceyer

    2011-12-09

    This project explored the catalytic oxidation chemistry that can be effected on a Au/Ni(111) surface alloy. A Au/Ni(111) surface alloy is a Ni(111) surface on which less than 60% of the Ni atoms are replaced at random positions by Au atoms. The alloy is produced by vapor deposition of a small amount of Au onto Ni single crystals. The Au atoms do not result in an epitaxial Au overlayer or in the condensation of the Au into droplets. Instead, Au atoms displace and then replace Ni atoms on a Ni(111) surface, even though Au is immiscible in bulk Ni. The two dimensional structure of the clean Ni surface is preserved. This alloy is found to stabilize an adsorbed peroxo-like O2 species that is shown to be the critical reactant in the low temperature catalytic oxidation of CO and that is suspected to be the critical reactant in other oxidation reactions. This investigation revealed a new, practically important catalyst for CO oxidation that has since been patented.

  8. The combustion synthesis of Ni-Ti shape memory alloys

    SciTech Connect

    Moore, J.J.; Yi, H.C. )

    1990-08-01

    Combustion synthesis of Ni-Ti-series shape-memory alloys yields both time and energy savings over conventional production methods. The solidified combustion synthesis process products have been cold-rolled into plates which exhibit the shape-memory effect, and it was noted that shape-memory transition temperatures may be tailored over a -78 to 460 C temperature range through the substitution of a third element for Ni; this element may be Pd or Fe. Accounts are given of the experimental combustion syntheses of Ni-Ti-Fe and Ti-Ni-Pd. 24 refs.

  9. Mechanisms of Formation and Transformation of Ni-Fe Hydroxycarbonates

    SciTech Connect

    Refait, Ph.; Jeannin, M.; Reffass, M.; Drissi, S.H.; Abdelmoula, M.; Genin, J.-M.R.

    2005-04-26

    The mechanisms of the transformation of (Ni,Fe)(OH)2 precipitates in carbonated aqueous solutions were studied. The reactions were monitored by measuring the redox potential of the aqueous suspension, and end products were studied by Moessbauer spectroscopy, X-ray diffraction and Raman spectroscopy. The oxidation processes were compared to those occurring without Ni, that is when the initial hydroxide is Fe(OH)2. Schematically, the oxidation of Fe(OH)2 involves two intermediate compounds, the carbonated GR of formula Fe{sup II}{sub 4}Fe{sup III}{sub 2}(OH){sub 12}CO{sub 3} {center_dot} 2H{sub 2}O, and ferrihydrite, before to lead finally to goethite {alpha}-FeOOH. It proved possible to prepare Ni(II)-Fe(III) hydroxycarbonates with ratios Fe/Ni from 1/6 to 1/3. When the Fe/Ni ratio is larger than 1/3, a two stage oxidation process takes place. The first stage leads to a Ni(II)-Fe(II)-Fe(III) hydroxycarbonate. The second stage corresponds to the oxidation of the Fe(II) remaining inside the hydroxycarbonate and leads to a mixture of Ni(II)-Fe(III) hydroxycarbonate with ferrihydrite. The main effect of Ni is then to stop the reaction at an intermediate stage, as Ni(II) is not oxidised by O2, leaving unchanged the main features of the mechanisms of transformation.

  10. High-performance Ni3Al synthesized from composite powders

    NASA Astrophysics Data System (ADS)

    Chiou, Wen-Chih; Hu, Chen-Ti

    1994-05-01

    Specimens of Ni3Al + B of high density (>99.3 Pct RD) and relatively large dimension have been synthesized from composite powders through processes of replacing plating and electroless Ni-B plating on Al powder, sintering, and thermal-mechanical treatment. The uniformly coated Ni layer over fine Al or Ni core particles constituting these coating/core composite powders has advantages such as better resistance to oxidation relative to pure Al powder, a greater green density as a compacted powder than prealloyed powder, the possibility of atomically added B to the material by careful choice of a suitable plating solution, and avoidance of the expensive powder metallurgy (PM) equipment such as a hot isostatic press (HIP), hot press (HP), etc. The final Ni3Al + B product is made from Ni-B-Al and Ni-B-Ni mixed composite powders by means of traditional PM processes such as compacting, sintering, rolling, and annealing, and therefore, the dimensions of the product are not constrained by the capacity of an HIP or HP. The properties of Ni3Al composite powder metallurgy (CPM) specimens tested at room temperature have been obtained, and comparison with previous reports is conducted. A tensile elongation of about 16 Pct at room temperature was attained.