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Sample records for bunkoho ni yoru

  1. Magnetic properties of Ni and Cu-Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Ganga, B. G.; Santhosh, P. N.; Thomas, P. John

    2012-06-01

    Ni and Cu-Ni nanoparticles were prepared by solution phase method and crystal phase was identified by XRD. SEM and EDX were used to analyze morphology and elemental composition of nanoparticles. Magnetic measurements indicate that Ni nanoparticles are superparamagnetic at room temperature and blocking temperature is around 103 K. Ferromagnetism is observed in the case of Cu-Ni nanoparticles with decrease in magnetization compared to Ni nanoparticles.

  2. Adjustment of temperature coefficient of resistance in NiCr/CuNi(Mn)/NiCr films

    NASA Astrophysics Data System (ADS)

    Brückner, W.; Baunack, St.; Elefant, D.; Reiss, G.

    1996-06-01

    The thin-film system Ni0.37Cr0.63/Cu0.57Ni0.42Mn0.01/Ni0.37Cr0. 63 with a typical thickness of 1 μm is used for low-ohmic precision resistors. The necessary adjustment of the temperature coefficient of resistance (TCR) by annealing has been studied by investigating the irreversible changes of the resistance during various annealing steps of NiCr/CuNi(Mn)/NiCr multilayers in comparison with single layers of CuNi(Mn) and NiCr. Auger depth profiles showed that the interdiffusion of CuNi(Mn) and NiCr results in an impoverishment of Ni in CuNi(Mn), explaining the TCR shift by comparison with data of Cu1-xNix bulk material. The decrease of the resistivity and the reduction of the width of the copper-nickel conductive layer by formation of a Ni0.6Cr0.2Cu0.2 interdiffusion zone phase (in accordance with the Cu-Ni-Cr phase diagram) cause a significant curvature of the resistance-temperature curve. As main result, it is shown that the NiCr base and cover layers and their interdiffusion with CuNi(Mn) play the decisive role in adjusting the TCR. It was checked that oxidation and topography effects have no remarkable influences.

  3. Thermal expansion behavior of NiSi/NiSi2

    NASA Technical Reports Server (NTRS)

    Wilson, D. F.; Cavin, O. B.

    1992-01-01

    The thermal expansion of NiSi/NiSi2 for a range of temperatures from 293 to 1223 K was determined using high-temperature X-ray diffraction. While a linear relation with temperature was found for the lattice parameter of NiSi2, third-order relationships were found for the three lattice parameters of NiSi, with one of the parameters showing a decrease with increasing temperature. The volumetric expansion of both materials exhibited linear relationships.

  4. 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.

  5. 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.

  6. Bulk Migration of Ni/NiO in Ni-YSZ during Reducing Conditions

    SciTech Connect

    Saraf, Laxmikant V.; Baer, Donald R.; Lea, Alan S.; Zhu, Zihua; Strohm, James J.; Sitzman, S. D.; King, David L.

    2010-02-09

    Understanding the migration of Ni/NiO in Ni-YSZ can potentially help to design a better solid oxide fuel cell (SOFC) anode. We have observed that extensive hydrogen reduction and methane steam reforming of Ni-YSZ caused bulk migration of Ni/NiO to at least ~ 5 µm deeper from the Ni-YSZ surface. No significant bulk migration effects were detected after simple thermal treatments in non-reducing/non-reforming environment. Surface analysis of a single zirconia grain in the first 10-20 nm region from annealed, hydrogen reduced and methane steam reformed Ni-YSZ shows Ni-enriched surface supporting earlier claims of Ni exsolution. 3D-EBSD analysis of thermally treated sample before exposing it to reducing and reforming environment indicated mixed NiO/YSZ phase with some porosity and random grain orientation. The surface analysis and mapping were carried out using ToF-SIMS and AES whereas EDS maps on FIB sliced areas on Ni-YSZ were utilized for the bulk analysis. The results provide additional information related to complex reactions occurring in SOFC during internal reforming conditions.

  7. ZnNi data

    DTIC Science & Technology

    2014-11-01

    carried out HE testing and passed, so that issue is resolved Concern over dezincification Keith Legg 847-680-9420 klegg@rowantechnology.com http...of the Zn-Ni plating 417 SCMS /GUEA, BR&T and ES3 are currently reviewing past industry de-zincification studies  Initial findings show that the...corrosion electro- potential is consistent throughout the corrosion process 417 SCMS /GUEA, BR&T and ES3 will identify any addition testing that

  8. Imaging Chemical Aggregation of Ni/NiO Particles from Reduced NiO-YSZ

    SciTech Connect

    Saraf, Laxmikant V.

    2011-07-20

    Energy dispersive X-ray spectroscopy (EDS) mapping of nickel oxide yttria-stabilized zirconia (NiO-YSZ) was carried out after various hydrogen reducing and methane steam reforming conditions. Nickel aggregation was visualized after methane steam reforming by correlating Ni K{sub {alpha}} map with scanning transmission electron microscopy (STEM) images. From the reduced O K{sub {alpha}} intensities in the Ni K{sub {alpha}} dominated regions after methane steam reforming, NiO reduction in to Ni can be interpreted. From correlation between Zr K{sub {alpha}} and O K{sub {alpha}} maps, high stability of YSZ was also realized. Examples of NiO-YSZ overlapped particles are considered to discuss chemical imaging of a single particle.

  9. 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.

  10. Atomic diffusion in liquid Ni, NiP, PdNiP, and PdNiCuP alloys

    SciTech Connect

    Chathoth, S. Mavila; Meyer, A.; Koza, M.M.; Juranyi, F.

    2004-11-22

    We investigated the self-diffusion of Ni in liquid Ni, Ni{sub 80}P{sub 20}, Pd{sub 40}Ni{sub 40}P{sub 20}, and Pd{sub 43}Ni{sub 10}Cu{sub 27}P{sub 20} at temperatures up to 1795 K with incoherent, quasielastic neutron scattering. Values of measured self-diffusion coefficients vary over the accessible temperature ranges as a function of composition only within 10%. Although mixing has a drastic effect on the liquidus temperature and the undercooling capabilities, a relation between these properties and the atomic diffusion in the liquid is not observed. Apparently, diffusive motion is governed by the packing fraction of the atoms, that is very similar in these dense liquids.

  11. Comparison of benzene adsorption on Ni(111) and Ni(100)

    SciTech Connect

    Myers, A.K.; Schoofs, G.R.; Benziger, J.B.

    1987-04-23

    The adsorption of benzene on the Ni(100) and the Ni(111) crystal faces was compared in order to investigate the effect of crystallographic orientation on the interaction of benzene with nickel. Temperature programmed reaction (TPR) was used to characterize adsorption bond strengths and determine product distributions. Benzene was found to adsorb 44 kJ/mol less strongly on the Ni(111) plane than on the Ni(100) surface. Di-hydrogen evolution formed after decomposition of benzene was similar for both surfaces. Benzene chemisorption was modeled by using extended Hueckel theory (EHT), a semiempirical molecular orbital method. The calculations predict bonding of benzene over a threefold hollow site on Ni(111). Multicenter bonding of the benzene carbon atoms with the nickel atoms is indicated by the calculations. The binding strength of benzene is controlled by the degree of overlap of the carbon ..pi.. orbitals with the nickel atom orbitals. Benzene binds more strongly to the Ni(100) surface because the carbon ..pi.. orbitals can overlap with four nickel atoms on the fourfold hollow site, whereas on Ni(111) the carbon atoms are closely associated with only three nickel atoms on the threefold hollow site.

  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. Solvotermal synthesis of NiO, Ni and NiS nanoparticles.

    PubMed

    Gutierrez, Angel; Perpiñán, M Felisa; Sánchez, Ana E; Torralba, M Carmen

    2013-01-01

    Nanoparticles of NiO, Ni or NiS have been obtained by solvothermal decomposition of different molecular precursors. The influence of several parameters, such as temperature, reaction time, solvent or capping agent used, in the nature and size of the obtained nanoparticle has been studied. The characterization by XRD and TEM techniques indicates that the nanoparticles of NiO exhibit average sizes of 3-8 nm, while those of Ni are in the 30-40 nm range. This difference in size has been attributed to the presence of molecules of the capping agent (n-octylamine or oleic acid) that surround the NiO nanoparticles but were not present in the nickel ones. The capping agent is, thus, preventing the aggregation of the smallest nanoparticles. The use of either a S-donor capping agent (4-mercaptopyridine) or a precursor having S-donor ligands (diethyldithiocarbamate) have led to the formation of NiS with average sizes around 35 nm. The magnetic properties of the nanoparticles have been studied, showing superparamagnetism and magnetic hysteresis below the blocking temperature, which, in time, is dependent of the particle size.

  15. Shape coexistence in 68Ni

    NASA Astrophysics Data System (ADS)

    Suchyta, S.; Liddick, S.; Bennet, M.; Larson, N.; Prokop, C.; Quinn, S.; Spyrou, A.; Chemey, A.; Simon, A.; Otsuka, T.; Tsunoda, Y.; Shimizu, N.; Honma, M.; Utsuno, Y.; Tripath, V.; Vonmoss, J.

    2013-10-01

    68 Ni has been a focus of recent work aiming to understand the apparent rapid development of collectivity along neutron-rich N = 40 nuclei, but despite many studies, is not entirely understood. The decay of the first excited 0+ state in 68Ni was investigated at the NSCL. Ions of 68Co were implanted into a planar germanium double-sided strip detector (GeDSSD). The beta decay of 68Co populated the first excited 0+ state in 68Ni and within hundreds of nanoseconds the decay of the first excited 0+ state was measured in the GeDSSD. Both the energy of the first excited 0+ state and the electric monopole transition strength from the first excited 0+ state were precisely determined. Comparisons to Monte Carlo Shell Model calculations suggest shape coexistence between spherical ground and oblate first excited 0+ states in 68Ni. The experimental results and theoretical interpretation will be presented.

  16. Abnormal Intermetallic Compound Evolution in Ni/Sn/Ni and Ni/Sn-9Zn/Ni Micro Solder Joints Under Thermomigration

    NASA Astrophysics Data System (ADS)

    Zhao, N.; Deng, J. F.; Zhong, Y.; Huang, M. L.; Ma, H. T.

    2017-04-01

    Interfacial reactions in Ni/Sn/Ni and Ni/Sn-9Zn/Ni micro solder joints during thermomigration (TM) have been studied by reflowing solder joints on a hot plate. Asymmetrical growth and transformation of interfacial intermetallic compounds (IMCs) were clearly observed. The growth of the Ni3Sn4 IMC in the Ni/Sn/Ni solder joints was always fast at the cold end and relatively slow at the hot end. Only asymmetrical growth of the Ni5Zn21 IMC in the Ni/Sn-9Zn/Ni solder joints occurred at the beginning because Zn was the dominant TM species; however, asymmetrical transformation of the Ni5Zn21 IMC also occurred under the combined effect of Zn depletion and Ni dissolution and migration, resulting in formation of a thin τ-phase layer at the hot end and a thick τ-phase/Ni5Zn21/τ-phase sandwich structure at the cold end. TM of Ni and Zn atoms was identified towards the cold end, being responsible for the abnormal IMC evolution. Addition of Zn was found to slow the TM-induced IMC growth and Ni dissolution.

  17. 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.

  18. Accessing Ni(III)-thiolate versus Ni(II)-thiyl bonding in a family of Ni-N2S2 synthetic models of NiSOD.

    PubMed

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

    2015-04-20

    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) (nmp(2-) = 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 (2(ox) and 3(ox)) 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

  19. Static atomic displacements in Ni-rich Ni-Al

    NASA Astrophysics Data System (ADS)

    Schönfeld, B.; Kostorz, G.; Celino, M.; Rosato, V.

    2001-05-01

    Short-range order and static atomic displacement parameters, previously determined from diffuse neutron scattering for Ni-8.9 at.% Al equilibrated at 775 K and quenched to room temperature, were used to study lattice relaxation effects in molecular-dynamics simulations. An occupation of average lattice sites with Ni and Al atoms compatible with the short-range ordered state was taken as the starting situation. Displacement parameters obtained from the relaxation simulations and from diffuse neutron scattering show general similarity in magnitude and dependence on distance. Also, the species dependence of the displacement parameters known from diffuse X-ray scattering investigations is reproduced in magnitude.

  20. Synthesis and Characterization of Pure Ni and Ni-Sn Intermetallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yakymovych, A.; Ipser, H.

    2017-02-01

    The present research focused on the synthesis of Ni and Ni-Sn nanoparticles via a chemical reduction method using hydrazine hydrate. The syntheses were performed applying highly purified water or diethylene glycol as solvent. The produced nanoparticles were characterized by scanning electron microscopy and powder X-ray diffraction. The as-synthesized Ni-Sn nanoparticles with nominal starting ratios Ni:Sn = 3:1, 3:2, and 3:4 consisted of different amounts of pure Ni and a low-temperature Ni3Sn2 phase. It was found that all synthesized nanopowders had a spherical shape with the largest average size for pure Ni and decreasing size for particles containing Sn. X-ray diffraction showed that all synthesized nanoparticles contained Ni and a low-temperature Ni3Sn2 phase independent of the initial molar ratio; while Ni3Sn and Ni3Sn4 could not be detected.

  1. Preparation and property of duplex Ni-B-TiO2/Ni nano-composite coatings

    NASA Astrophysics Data System (ADS)

    Wang, Shu-Jen; Wang, Yuxin; Shu, Xin; Tay, Seeleng; Gao, Wei; Shakoor, R. A.; Kahraman, Ramazan

    2015-03-01

    The duplex Nickel-Boron-Titania/Nickel (Ni-B-TiO2/Ni) coatings were deposited on mild steel by using two baths with Ni as the inner layer. TiO2 nanoparticles were incorporated into the Ni-B coatings as the outer layer by using solid particle mixing method. The microstructure, morphology and corrosion resistance of the duplex Ni-B-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the duplex interface was uniform and the adhesion between two layers was very good. The microhardness of duplex Ni-B-TiO2/Ni coating was much higher than the Ni coating due to the outer layer of Ni-B-TiO2 coating. The corrosion resistance of the duplex Ni-B-TiO2/Ni coating was also significantly improved comparing with single Ni-B coating. The Ni-B-10 g/L TiO2/Ni coating was found to have the best corrosion resistance among these duplex coatings. This type of duplex Ni-B-TiO2/Ni coating, with high hardness and good corrosion resistance properties, should be able to find broad applications under adverse environmental conditions.

  2. Shape coexistence in Ni68

    NASA Astrophysics Data System (ADS)

    Suchyta, S.; Liddick, S. N.; Tsunoda, Y.; Otsuka, T.; Bennett, M. B.; Chemey, A.; Honma, M.; Larson, N.; Prokop, C. J.; Quinn, S. J.; Shimizu, N.; Simon, A.; Spyrou, A.; Tripathi, V.; Utsuno, Y.; VonMoss, J. M.

    2014-02-01

    The internal-conversion and internal-pair-production decays of the first excited 0+ state in Ni68 are studied following the β decay of Co68. A novel experimental technique, in which the ions of Co68 were implanted into a planar germanium double-sided strip detector and which required digital pulse processing, is developed. The values for the energy of the first excited 0+ state and the electric monopole transition strength from the first excited 0+ state to the ground state in Ni68 are determined to be 1605(3) keV and 7.6(4)×10-3, respectively. Comparisons of the experimental results to Monte Carlo shell-model calculations suggest the coexistence between a spherical ground state and an oblate first excited 0+ state in Ni68.

  3. 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.

  4. Dominating Role of Ni(0) on the Interface of Ni/NiO for Enhanced Hydrogen Evolution Reaction.

    PubMed

    Wang, Jing; Mao, Shanjun; Liu, Zeyan; Wei, Zhongzhe; Wang, Haiyan; Chen, Yiqing; Wang, Yong

    2017-03-01

    The research of a robust catalytic system based on single NiOx electrocatalyst for hydrogen evolution reaction (HER) remains a huge challenge. Particularly, the factors that dominate the catalytic properties of NiOx-based hybrids for HER have not been clearly demonstrated. Herein, a convenient protocol for the fabrication of NiOx@bamboo-like carbon nanotube hybrids (NiOx@BCNTs) is designed. The hybrids exhibit superb catalytic ability and considerable durability in alkaline solution. A benchmark HER current density of 10 mA cm(-2) has been achieved at an overpotential of ∼79 mV. In combination with the experimental results and density functional theory (DFT) calculations, this for the first time definitely validates that the inherent high Ni(0) ratio and the Ni(0) on the interface of Ni/NiO play a vital role in the outstanding catalytic performance. Especially, the Ni(0) on the interface of Ni/NiO performs superior activity for water splitting compared with that of bulk Ni(0). These conclusions provide guidance for the rational design of the future non-noble metallic catalysts.

  5. Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

    PubMed

    Zou, Wenli; Liu, Wenjian

    2006-04-21

    The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

  6. Density functional theory study of the interfacial properties of Ni/Ni3Si eutectic alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Yuhong; Wen, Zhiqin; Hou, Hua; Guo, Wei; Han, Peide

    2014-06-01

    In order to clarify the heterogeneous nucleation potential of α-Ni grains on Ni3Si particles in Ni-Ni3Si eutectic alloy, the work of adhesion (Wad), fracture toughness (G), interfacial energy (γi), and electronic structure of the index (0 0 1), (1 1 0) and (1 1 1) Ni/Ni3Si interfaces with two different cohesive manners are investigated using first-principles method based on density functional theory. Results indicate that the center site stacking sequence (OM) is preferable to continue the natural stacking sequence of bulk Ni and Ni3Si. Since OM stacking interfaces have larger Wad, G and γi than that of the top site stacking (OT) interfaces. The Ni/Ni3Si (1 1 0) interface with OM stacking has the best mechanical properties. Therefore, the formation of this interface can improve the stability, ductility and fracture toughness of Ni-Ni3Si eutectic alloy. The calculated interfacial energy of Ni/Ni3Si (0 0 1), (1 1 0) and (1 1 1) interfaces with OM stacking proves the excellent nucleation potency of Ni3Si particles for α-Ni phase from thermodynamic considerations. Besides, the electronic structure and chemical bonding of (1 1 0) interface with OM stacking are also discussed.

  7. Chemical reactivity of Ni-Rh nanowires.

    PubMed

    Schoiswohl, J; Mittendorfer, F; Surnev, S; Ramsey, M G; Andersen, J N; Netzer, F P

    2006-09-22

    The properties of bimetallic Ni-Rh nanowires, fabricated by decorating the steps of vicinal Rh(111) surfaces by stripes of self-assembled Ni adatoms, have been probed by STM, photoemission, and ab initio density functional theory calculations. These Ni-Rh nanowires have specific electronic properties that lead to a significantly enhanced chemical reactivity towards oxygen. As a result, the Ni-Rh nanowires can be oxidized exclusively, generating novel quasi-one-dimensional oxide structures.

  8. 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.

  9. 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.

  10. Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes

    DOE PAGES

    Qiao, Ruimin; Wray, L. Andrew; Kim, Jung -Hyun; ...

    2015-11-11

    The LiNi0.5Mn1.5O4 spinel is an appealing cathode material for next generation rechargeable Li-ion batteries due to its high operating voltage of ~4.7 V (vs Li/Li+). Although it is widely believed that the full range of electrochemical cycling involves the redox of Ni(II)/(IV), it has not been experimentally clarified whether Ni(III) exists as the intermediate state or a double-electron transfer takes place. Here, combined with theoretical calculations, we show unambiguous spectroscopic evidence of the Ni(III) state when the LiNi0.5Mn1.5O4 electrode is half charged. This provides a direct verification of single-electron-transfer reactions in LiNi0.5Mn1.5O4 upon cycling, namely, from Ni(II) to Ni(III), thenmore » to Ni(IV). Additionally, by virtue of its surface sensitivity, soft X-ray absorption spectroscopy also reveals the electrochemically inactive Ni2+ and Mn2+ phases on the electrode surface. Our work provides the long-awaited clarification of the single-electron transfer mechanism in LiNi0.5Mn1.5O4 electrodes. Furthermore, the experimental results serve as a benchmark for further spectroscopic characterizations of Ni-based battery electrodes.« less

  11. 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.

  12. Stability of NiTi-Pd and NiTi-Hf high temperature shape memory alloys

    SciTech Connect

    Zhu, Y.R.; Pu, Z.J.; Li, C.; Wu, K.H.

    1994-09-28

    The thermal cycling tests and high temperature aging tests were performed to characterize the stability of NiTi-Pd and NiTi-Hf high temperature shape memory alloys. These alloys have better stability than NiTi during thermal cycling. In addition, it also found that the NiTi-Pd and NiTi-Hf alloy have a very good stability in high temperature aging.

  13. Electrical and thermal transport in CeNi and LaNi

    NASA Astrophysics Data System (ADS)

    Rudajevová, Alexandra; Vasylyev, Denis; Musil, Ondřej

    2006-05-01

    We have measured the electrical resistivity and thermal conductivity of CeNi, LaNi and La 0.15Ce 0.85Ni in the temperature range 4-400 K simultaneously on the same specimen using the TTO option in PPMS (Quantum Design) facility. Anomalous behaviour of the resistivity and the Lorenz number for CeNi and La 0.15Ce 0.85Ni can be attributed to valence fluctuations.

  14. 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.

  15. 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.

  16. Synthesis and catalytic performance of SiO2@Ni and hollow Ni microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Liu, Yanhua; Shi, Xueting; Yu, Zhengyang; Feng, Libang

    2016-11-01

    Nickel (Ni) catalyst has been widely used in catalytic reducing reactions such as catalytic hydrogenation of organic compounds and catalytic reduction of organic dyes. However, the catalytic efficiency of pure Ni is low. In order to improve the catalytic performance, Ni nanoparticle-loaded microspheres can be developed. In this study, we have prepared Ni nanoparticle-loaded microspheres (SiO2@Ni) and hollow Ni microspheres using two-step method. SiO2@Ni microspheres with raspberry-like morphology and core-shell structure are synthesized successfully using SiO2 microsphere as a template and Ni2+ ions are adsorbed onto SiO2 surfaces via electrostatic interaction and then reduced and deposited on surfaces of SiO2 microspheres. Next, the SiO2 cores are removed by NaOH etching and the hollow Ni microspheres are prepared. The NaOH etching time does no have much influence on the crystal structure, shape, and surface morphology of SiO2@Ni; however, it can change the phase composition evidently. The hollow Ni microspheres are obtained when the NaOH etching time reaches 10 h and above. The as-synthesized SiO2@Ni microspheres exhibit much higher catalytic performance than the hollow Ni microspheres and pure Ni nanoparticles in the catalytic reduction of methylene blue. Meanwhile, the SiO2@Ni catalyst has high stability and hence it can be recycled for reuse.

  17. Kinetics of Ni sorption in soils: roles of soil organic matter and Ni precipitation.

    PubMed

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

    2012-02-21

    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.

  18. Structural evaluation and nonlinear optical properties of Ni/NiO, Ni/NiCo2O4 and Co/Co3O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Rahulan, K. Mani; Padmanathan, N.; Philip, Reji; Balamurugan, S.; Kanakam, Charles C.

    2013-10-01

    Nanocomposites of Ni/NiO, Ni/NiCo2O4 and Co/Co3O4 have been synthesized by a chemical reduction technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images confirm the mixed composite nature of the sample and uniform particle size of approximately 13 nm. Formation of Ni/NiCo3O4 solid solution or NiCo2O4 spinel phase in the mixed composite is confirmed by energy dispersive X-ray (EDX) spectrum. Magnetic hysteresis (M-H) curves of the nanocomposites show excellent ferromagnetic (FM) nature at room temperature. Nonlinear optical transmission of the nanocomposites is measured using the open aperture Z-scan technique employing 7 nanosecond laser pulses at 532 nm. Experimental results show that NiO/NiO-Co3O4/Co3O4 nanocomposites exhibit good optical limiting performance. From the measurements and numerical fitting of the data to theory, it is found that nonlinear absorption has contributions from excited state absorption and two-photon absorption. Optical limiting is enhanced in Co3O4 and Ni/NiCo2O4 in which the Co3O4 content has a larger volume ratio.

  19. 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

  20. California Niño/Niña.

    PubMed

    Yuan, Chaoxia; Yamagata, Toshio

    2014-04-25

    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.

  1. Corrosion behavior of Ni/sup +/-ion irradiated NiTi alloys

    SciTech Connect

    Wang, R.; Brimhall, J.L.

    1983-11-01

    Corrosion behavior of Ni/sup +/-irradiated NiTi alloys was studied in chloride solutions, together with unirradiated NiTi material with different surface conditions. Ion irradiation with either 2.5 or 5 MeV Ni/sup +/ ions transformed the NiTi surface into an amorphous layer up to 1.5 micrometers thick. Studies of corrosion potential vs time and polarization behavior indicated a small enhancement of the passivation for the Ni/sup +/-irradiated NiTi over the unirradiated NiTi. The unirradiated NiTi with a mechanically polished, course surface was susceptible to pitting and crevice corrosion attack in 1 N HCl solution. The homogeneous amorphous structure in the irradiated alloy retarded this type of localized corrosion.

  2. Synthesis and magnetic studies of Ni/NiO core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Rinsha, C.; Anumol, C. N.; Chithra, M.; Sahu, B. N.; Sahoo, Subasa C.

    2015-06-01

    Ni/NiO core/shell nanoparticles were synthesized by chemical reduction method followed by oxidation by two different methods; (a) in air and (b) in microwave oven. Structural studies showed that the thickness of NiO shell on Ni core is less in air oxidized sample than the microwave oxidized samples which were supported by the magnetic studies. The samples prepared by air oxidation showed positive exchange biasing where as the samples prepared by microwave oxidation showed negative exchange biasing. Our study also showed that the thickness of the antiferromagnetic NiO is responsible for the different types of magnetic interactions at the interfaces between antiferromagnetic NiO and ferromagnetic Ni in Ni/NiO core/shell nanoparticles.

  3. Monoligated monovalent Ni: the 3d(Ni)9 manifold of states of NiCu and comparison to the 3d9 States of AlNi, NiH, NiCl, and NiF.

    PubMed

    Rothschopf, Gretchen K; Morse, Michael D

    2005-12-22

    A dispersed fluorescence investigation of the low-lying electronic states of NiCu has allowed the observation of four out of the five states that derive from the 3d(Ni)9 3d(Cu)10 sigma2 manifold. Vibrational levels of the ground X2delta(5/2) state corresponding to v = 0-11 are observed and are fit to provide omega(e) = 275.93 +/- 1.06 cm(-1) and omega(e)x(e) = 1.44 +/- 0.11 cm(-1). The v = 0 levels of the higher lying states deriving from the 3d(Ni)9 3d(Cu)10 sigma2 manifold are located at 912, 1466, and 1734 cm(-1), and these states are assigned to omega values of 3/2, 1/2, and 3/2, respectively. The last of these assignments is based on selection rules and is unequivocal; the first two are based on a comparison to ab initio and ligand field calculations and could conceivably be in error. It is also possible that the v = 0 level of the state found at 912 cm(-1) is not observed, so that T0 for the lowest excited state actually lies near 658 cm(-1). These results are modeled using a matrix Hamiltonian based on the existence of a ground manifold of states deriving from the 3d9 configuration on nickel. This matrix Hamiltonian is also applied to the spectroscopically well-known molecules AlNi, NiH, NiCl, and NiF. The term energies of the 2sigma+, 2pi, and 2delta states of these molecules, which all derive from a 3d9 configuration on the nickel atom, display a clear and understandable trend as a function of the electronegativity of the ligands.

  4. 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.

  5. 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:

  6. Al-La-Ni (069)

    NASA Astrophysics Data System (ADS)

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

    This document is part of Part 1 http://dx.doi.org/10.1007/9getType="URL"/> 'Systems from Ag-Al-Ca to Au-Pd-Si' 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 'Al-La-Ni (069)' with the content:

  7. 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.

  8. Cytosolic Ni(II) Sensor in Cyanobacterium

    PubMed Central

    Foster, Andrew W.; Patterson, Carl J.; Pernil, Rafael; Hess, Corinna R.; Robinson, Nigel J.

    2012-01-01

    Efflux of surplus Ni(II) across the outer and inner membranes of Synechocystis PCC 6803 is mediated by the Nrs system under the control of a sensor of periplasmic Ni(II), NrsS. Here, we show that the product of ORF sll0176, which encodes a CsoR/RcnR-like protein now designated InrS (for internal nickel-responsive sensor), represses nrsD (NrsD is deduced to efflux Ni(II) across the inner membrane) from a cryptic promoter between the final two ORFs in the nrs operon. Transcripts initiated from the newly identified nrsD promoter accumulate in response to nickel or cobalt but not copper, and recombinant InrS forms specific, Ni(II)-inhibited complexes with the nrsD promoter region. Metal-dependent difference spectra of Ni(II)- and Cu(I)-InrS are similar to Cu(I)-sensing CsoR and dissimilar to Ni(II)/Co(II)-sensing RcnR, consistent with factors beyond the primary coordination sphere switching metal selectivity. Competition with chelators mag-fura-2, nitrilotriacetic acid, EDTA, and EGTA estimate KD Ni(II) for the tightest site of InrS as 2.05 (±1.5) × 10−14 m, and weaker KD Ni(II) for the cells' metal sensors of other types: Zn(II) co-repressor Zur, Co(II) activator CoaR, and Zn(II) derepressor ZiaR. Ni(II) transfer to InrS occurs upon addition to Ni(II) forms of each other sensor. InrS binds Ni(II) sufficiently tightly to derepress Ni(II) export at concentrations below KD Ni(II) of the other sensors. PMID:22356910

  9. 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

    2015-12-09

    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).

  10. Magnetic Properties of Grain Boundaries of Nanocrystalline Ni and of Ni Precipitates in Nanocrystalline NiCu Alloys

    NASA Astrophysics Data System (ADS)

    Wolf, H.; Guan, Z.; Li, X.; Wichert, Th.

    2001-11-01

    Perturbed γγ-angular correlation spectroscopy (PAC) was used to investigate nanocrystalline Ni and NiCu alloys, which are prepared by pulsed electrodeposition (PED). Using diffusion for doping nanocrystalline Ni with 111In four different ordered grain boundary structures are observed, which are characterized by unique electric field gradients. The incorporation of 111In on substitutional bulk sites of Ni is caused by moving grain boundaries below 1000 K and by volume diffusion above 1000 K. The nanocrystalline NiCu alloys prepared by PED are microscopically inhomogeneous as observed by PAC. In contrast, this inhomogeneity cannot be detected by X-ray diffraction. The influence of the temperature of the electrolyte, the current density during deposition, and the optional addition of saccharin to the electrolyte on the homogeneity of nanocrystalline NiCu alloys was investigated.

  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.

  12. Solidification Behavior in Newly Designed Ni-Rich Ni-Ti-Based Alloys

    NASA Astrophysics Data System (ADS)

    Samal, Sumanta; Biswas, Krishanu; Phanikumar, Gandham

    2016-12-01

    The present investigation reports phase and microstructure evolution during solidification of novel Ni-rich Ni-Ti-based alloys, Ni60Ti40, Ni50Cu10Ti40, Ni48Cu10Co2Ti40, and Ni48Cu10Co2Ti38Ta2 during suction casting. The design philosophy of the multicomponent alloys involves judicious selection of alloying elements such as Cu, Co, and Ta in the near Ni60Ti40 eutectic alloy by replacing both Ni and Ti so that phase mixture in the microstructure remains the same from the binary to quinary alloy. The basic objective is to study the effect of addition of Cu, Co, and Ta on the phase evolution and transformation in the Ni-rich Ni-Ti-based alloys. The detailed electron microscopic studies on these suction cast alloys reveal the presence of ultrafine eutectic lamellae between NiTi and Ni3Ti phases along with dendritic NiTi and Ti2Ni phases. It has also been observed that in the binary (Ni60Ti40) alloy, the ordered NiTi (B2) phase transforms to trigonal (R) phase followed by NiTi martensitic phase (M-phase), i.e., B2 → R-phase → M-phase during solid-state cooling. However, the addition of alloying elements such as Cu, Co to the binary (Ni60Ti40) alloy suppresses the martensitic transformation of the ordered NiTi (B2) dendrite. Thus, in the ternary and quaternary alloys, the ordered NiTi (B2) phase is transformed to only trigonal (R) phase, i.e., B2 → R-phase. The secondary precipitate of Ti2Ni has been observed in all of the studied alloys. Interestingly, Ni48Cu10Co2Ti38Ta2 quinary alloy shows the disordered nature of NiTi dendrites. The experimentally observed solidification path is in good agreement with Gulliver-Scheil simulated path for binary alloy, whereas simulated solidification path deviates from the experimental results in case of ternary, quaternary, and quinary alloys.

  13. Point defect evolution in Ni, NiFe and NiCr alloys from atomistic simulations and irradiation experiments

    SciTech Connect

    Aidhy, Dilpuneet S.; Lu, Chenyang; Jin, Ke; Bei, Hongbin; Zhang, Yanwen; Wang, Lumin; Weber, William J.

    2015-08-08

    Using molecular dynamics simulations, we elucidate irradiation-induced point defect evolution in fcc pure Ni, Ni0.5Fe0.5, and Ni0.8Cr0.2 solid solution alloys. We find that irradiation-induced interstitials form dislocation loops that are of 1/3 <111>{111}-type, consistent with our experimental results. While the loops are formed in all the three materials, the kinetics of formation is considerably slower in NiFe and NiCr than in pure Ni, indicating that defect migration barriers and extended defect formation energies could be higher in the alloys than pure Ni. As a result, while larger size clusters are formed in pure Ni, smaller and more clusters are observed in the alloys. The vacancy diffusion occurs at relatively higher temperatures than interstitials, and their clustering leads to formation of stacking fault tetrahedra, also consistent with our experiments. The results also show that the surviving Frenkel pairs are composition-dependent and are largely Ni dominated.

  14. Point defect evolution in Ni, NiFe and NiCr alloys from atomistic simulations and irradiation experiments

    DOE PAGES

    Aidhy, Dilpuneet S.; Lu, Chenyang; Jin, Ke; ...

    2015-08-08

    Using molecular dynamics simulations, we elucidate irradiation-induced point defect evolution in fcc pure Ni, Ni0.5Fe0.5, and Ni0.8Cr0.2 solid solution alloys. We find that irradiation-induced interstitials form dislocation loops that are of 1/3 <111>{111}-type, consistent with our experimental results. While the loops are formed in all the three materials, the kinetics of formation is considerably slower in NiFe and NiCr than in pure Ni, indicating that defect migration barriers and extended defect formation energies could be higher in the alloys than pure Ni. As a result, while larger size clusters are formed in pure Ni, smaller and more clusters are observedmore » in the alloys. The vacancy diffusion occurs at relatively higher temperatures than interstitials, and their clustering leads to formation of stacking fault tetrahedra, also consistent with our experiments. The results also show that the surviving Frenkel pairs are composition-dependent and are largely Ni dominated.« less

  15. 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

  16. 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.

  17. Grain boundary segregation of Ni in W

    SciTech Connect

    Nieh, T.G.

    1984-11-01

    The compatibility between Ni and W is an important consideration in a number of structural applications involving tungsten alloys. Here, results of an experimental study using Auger electron spectroscopy are presented which provide direct evidence of grain boundary segregation of Ni in W. It is also demonstrated that the segregation of nickel results in a severe embrittlement of tungsten filaments. Also, the activation energy for grain boundary diffusion of Ni in W has been calculated to be 358 kJ/mol, almost identical to the activation energy for recrystallization of dilute W-Ni alloys. This suggests that grain boundary diffusion of Ni may govern the recrystallization processes in dilute W-Ni alloys. 11 references.

  18. Electroless Plated Co-Ni-P-B/Ni Foam Catalyst for Hydrogen Generation from Sodium Borohydride.

    PubMed

    Park, Daeil; Kim, Taegyu

    2016-02-01

    Co-Ni-P-B catalyst supported on Ni foam was prepared using electroless plating for hydrogen generation from an alkaline NaBH4 solution. Co-B, Co-P-B, and Co-Ni-B were prepared for comparison. Surface morphology of catalyst/Ni foams were observed using SEM analysis. The Co- Ni-P-B/Ni foam catalyst showed the superior performance on hydrogen generation rate due to the uniform formation of catalyst particles on the surface of Ni foam. Characteristics of hydrogen generation rate on the Co-N-P-B/Ni foam catalyst were investigated at the variety of NaBH4 and NaOH concentrations. The hydrogen generation rate increased with decreasing NaBH4 concentration, while increasing NaOH concentration. Durability test was performed, resulting in the stable hydrogen generation for 6 hours.

  19. 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.

  20. Ni clay neoformation on montmorillonite surface.

    PubMed

    Dähn, R; Scheidegger, A; Manceau, A; Schlegel, M; Baeyens, B; Bradbury, M H

    2001-03-01

    Polarized extended X-ray absorption fine structure spectroscopy (P-EXAFS) was used to study the sorption mechanism of Ni on the aluminous hydrous silicate montmorillonite at high ionic strength (0.3 M NaClO4), pH 8 and a Ni concentration of 0.66 mM. Highly textured self-supporting clay films were obtained by slowly filtrating a clay suspension after a reaction time of 14 days. P-EXAFS results indicate that sorbed Ni has a Ni clay-like structural environment with the same crystallographic orientation as montmorillonite layers.

  1. Morphology controlled synthesis of 2-D Ni-Ni3S2 and Ni3S2 nanostructures on Ni foam towards oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Chaudhari, Nitin Kaduba; Oh, Aram; Sa, Young Jin; Jin, Haneul; Baik, Hionsuck; Kim, Sang Gu; Lee, Suk Joong; Joo, Sang Hoon; Lee, Kwangyeol

    2017-03-01

    Catalysts for oxygen evolution reactions (OER) are at the heart of key renewable energy technologies, and development of non-precious metal catalysts with high activity and stability remain a great challenge in this field. Among various material candidates, metal sulfides are receiving increasing attention. While morphology-dependent catalytic performances are well established in noble metal-based catalysts, relatively little is known for the morphology‒catalytic performance relationship in metal sulfide catalysts. In this study, uniform spider web-like Ni nanosheets-Ni3S2 and honeycomb-like Ni3S2 structures are deposited on nickel foam (Ni3S2/NF) by a facile one-step hydrothermal synthetic route. When used as an oxygen evolution electrode, the spider web-like Ni-Ni3S2/NF with the large exposed surface area shown excellent catalytic activity and stability with an overpotential of 310 mV to achieve at 10 mA/cm2 and a Tafel slope of 63 mV/dec in alkaline media, which is superior to the honeycomb-like structure without Ni nanosheet. The low Tafel slope of the spider web-like Ni-Ni3S2/NF represents one of the best OER kinetics among nickel sulfide-based OER catalysts. The results point to the fact that performance of the metal sulfide electrocatalysts might be fine-tuned and optimized with morphological controls.

  2. 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.

  3. Ni cluster formation in low temperature annealed Ni50.6Ti49.4

    NASA Astrophysics Data System (ADS)

    Pourbabak, Saeid; Wang, Xiebin; van Dyck, Dirk; Verlinden, Bert; Schryvers, Dominique

    Various low temperature treatments of Ni50.6Ti49.4 have shown an unexpected effect on the martensitic start temperature. Periodic diffuse intensity distributions in reciprocal space indicate the formation of short pure Ni strings along the <111> directions in the B2 ordered lattice, precursing the formation of Ni4Ti3 precipitates formed at higher annealing temperatures.

  4. Internal-nitriding behavior of Ni-V and Ni-3Nb alloys

    SciTech Connect

    Allen, A.T.; Douglass, D.L.

    1999-02-01

    Ni-2V, Ni-5V, Ni-12V, and Ni-3Nb alloys (w/o) were nitrided in 10 v/o NH{sub 3} (bal H{sub 2}) over the range of 700--1000 C. The growth rates of the reaction zones followed parabolic behavior for all of the alloys from 700 to 900 C. At 1000 C, Ni-2V and Ni-3Nb formed nitride scales, whereas Ni-5V and Ni-12V formed internal-nitride zones. Nitridation rates decreased with increasing vanadium content for the Ni-V alloys. VN precipitated in the Ni-V alloys and NbN precipitated in Ni-3Nb for all exposure conditions in which internal nitridation occurred. The precipitate morphology changed with temperature and distance from the gas-metal surface. The VN and NbN precipitates were generally small and spheroidal near the surface, increasing in size with distance and temperature. The NbN precipitates became Widmanstaetten at higher temperatures and/or increasing distance within the nitrided zone. The solubility of nitrogen in pure Ni was determined and found to decrease with increasing temperature from 700 to 1000 C. Expressions for the diffusion coefficient of nitrogen in nickel were determined from the measured permeabilities of each alloy and the nitrogen solubilities in nickel.

  5. Effect of air annealing on structural and magnetic properties of Ni/NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Nadeem, K.; Ullah, Asmat; Mushtaq, M.; Kamran, M.; Hussain, S. S.; Mumtaz, M.

    2016-11-01

    We reported systematic study on structural and magnetic properties of nickel/nickel oxide (Ni/NiO) nanoparticles annealed under air atmosphere at different temperatures in the range 400-800 °C. The XRD spectra revealed two phases such as Ni and NiO. The average crystallite size increases with increasing annealing temperature. A phase diagram was developed between two phases versus annealing temperature using XRD analysis. At lower annealing temperatures, Ni phase is dominant which does not easily undergo oxidation to form NiO. The NiO phase increases with increasing annealing temperature. FTIR spectroscopy revealed an increase in the NiO phase content at higher annealing temperature, which is in agreement with the XRD analysis. SEM images showed that nanoparticles are well separated at lower annealing temperatures but get agglomerated at higher annealing temperatures. The ferromagnetic (FM) Ni phase content and saturation magnetization (Ms) showed nearly the same trend with increasing annealing temperature. The nanoparticles annealed at 500 °C and 800 °C revealed highest and lowest Ms values, respectively, which is in accordance with the XRD phase diagram. Coercivity showed an overall decreasing trend with increasing annealing temperature due to decreased concentration of FM Ni phase and increasing average crystallite size. All these measurements indicate that the structural and magnetic properties of Ni/NiO nanoparticles are strongly influenced by the annealing temperature.

  6. 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.

  7. 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.

  8. Where is La Niña?

    NASA Image and Video Library

    2003-07-14

    Since the weak El Niño event of last winter, the equatorial Pacific has cooled and oceanographers have been on a La Niña watch. Thus far, equatorial waters have seesawed between cooling and the present slight warming.

  9. 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.”

  10. 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.

  11. 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.

  12. 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)

  13. Analyzing the magnetic profile in NiFe/NiO bilayers

    NASA Astrophysics Data System (ADS)

    Tafur, Miguel; Nascimento, V. P.; Alayo, W.; Xing, Y. T.; Baggio-Saitovitch, E.

    2017-04-01

    The magnetic profile of the Si(100)/NiO(35 nm)/NiFe(10 nm)/Ta(1 nm) sample has been obtained by X-ray absorption spectroscopy (XAS) and the X-ray magnetic circular dichroism (XMCD). Two experimental procedures were used. In the procedure 1, the magnetic depth profile has been determines using samples deposited with different NiFe thicknesses, Si(100)/NiO(35 nm)/NiFe(t)/Ta(1 nm), t = 1 , 3 , 5 , 7 , 10 nm . In procedure 2, the sample (NiFe=10 nm), was thinned by several in situ sputtering cycles with Ar+ ions, followed by XAS and XMCD analysis. In both procedures, the calculated magnetic moments values tend to decrease close to interface with the NiO antiferromagnetic (AF) layer, however, this decreasement is more evidenced in the sputtered sample. There is no charge transfer between Ni and Fe in the inner part of the NiFe layer, a reduction of the morb /mspineff has been found at the NiFe/NiO interface. Procedure 1 emerged as the most indicated to analyse the interface region.

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

    SciTech Connect

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

    1984-11-15

    Amorphous films of Ni-W and Ni-N-W were deposited on single-crystal silicon with discharge gases of Ar or Ar+N/sub 2/ by rf cosputtering of Ni and W. The reaction of these Ni-W and Ni-N-W films with the Si substrate were studied in the temperature range of 450--750 /sup 0/C by a combination of backscattering spectrometry, x-ray diffraction, cross-sectional transmission electron microscopy, and resistivity measurements. Films with composition Ni/sub 36/W/sub 64/ are stable below 500 /sup 0/C. NiSi and NiSi/sub 2/ form at 500 /sup 0/C, and WSi/sub 2/ forms rapidly in the temperature range of 625--650 /sup 0/C. The nickel silicide forms adjacent to and within the silicon, while the outer layer becomes a mixture of WSi/sub 2/ and NiSi/sub 2/. The morphologies of the reacted layers are revealed by cross-sectional transmission electron microscopy. The crystallization temperature of amorphous Ni/sub 36/W/sub 64/ films on SiO/sub 2/ is near 650 /sup 0/C also. Adding nitrogen to form amorphous Ni/sub 30/N/sub 21/W/sub 49/ films lowers the crystallization temperature, but raises the reaction temperature with Si to 750 /sup 0/C.

  15. Water dissociation on Ni(100) and Ni(111): effect of surface temperature on reactivity.

    PubMed

    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).

  16. Thermodynamic Assessment of the Bi-Ni and Bi-Ni-X (X = Ag, Cu) Systems

    NASA Astrophysics Data System (ADS)

    Liu, Yuling; Liu, Shuhong; Zhang, Cong; Lu, Xingxu; Chen, Chong; Du, Yong; Živković, Dragana

    2016-02-01

    The Bi-Ni system was reassessed by means of the calculation of phase diagrams (CALPHAD) method by considering the latest published experimental data. To maintain the compatibility in higher-order systems, the excess Gibbs energy of the solution phases was modeled with the Redlich-Kister polynomials, and a three-sublattice model, (Bi)0.3334(Ni,Va)0.3333(Va,Ni)0.3333, was used to describe the intermetallic compound BiNi with NiAs-type crystal structure. Compared with the previous thermodynamic description for the Bi-Ni system, noticeable improvements are achieved in the present work. The current thermodynamic parameters can well reproduce the newly published experimental data on thermodynamic properties. Based on the newly obtained parameters for the Bi-Ni system, as well as the thermodynamic descriptions for the Bi-Ag, Ni-Ag, Bi-Cu, and Ni-Cu systems in literature, a thermodynamic database of the Bi-Ni-Ag and Bi-Ni-Cu ternary systems was established by considering the available experimental data. The calculated phase equilibria in these ternary systems are in satisfactory agreement with experimental observations.

  17. Predictability of the Ningaloo Niño/Niña.

    PubMed

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

    2013-10-08

    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.

  18. Self-oxidized NiO on cube-textured Ni for YBCO coated superconductor

    NASA Astrophysics Data System (ADS)

    Wang, Rong-Ping; Wang, Huan-Hua; Zhou, Yue-Liang; Pan, Shao-Hua; Liu, Chun-Fang; Wu, Xuan; Liu, Dan-Ming; Zhang, Ping-Xiang; Zhou, Lian

    2000-10-01

    In this paper, we report a self-oxidation approach to obtain NiO on the surface of Ni substrates. Under optimal oxidizing conditions, high-textured NiO layers on the surface of Ni substrates were obtained. Detailed pole figure (PF) measurements show an improvement in the full width at half maximum of NiO layers compared with that of Ni substrate. Orientation distribution function calculated from two PFs shows that the best cubic texture of NiO can be formed at 680°C in 5 Pa oxygen. A grain size less than 1 μm is evident from scanning electron microscopy observation. Some possible ways were proposed to improve surface quality. The self-oxidation approach provides a potential to prepare high- Jc YBCO films on a large scale.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. A dinuclear Ni(II) complex with two types of intramolecular magnetic couplings: Ni(II)-Ni(II) and Ni(II)-TTF*+.

    PubMed

    Liu, Shi-Xia; Ambrus, Christina; Dolder, Stefan; Neels, Antonia; Decurtins, Silvio

    2006-11-27

    A dinuclear Ni(II) complex involving tetrathiafulvalene (TTF) radicals as ligands has been prepared and characterized, [Ni2(mu-Cl)2(L*+)2(I3)4(I2)3.(H2O)2.(C4H8O)3 (1), L = 4,5-bis(2-pyridylmethylsulfanyl)-4',5'-ethylenedithiotetrathiafulvalene. There are two types of intramolecular magnetic exchange interactions, namely one ferromagnetic Ni(II)-Ni(II) and one antiferromagnetic Ni(II)-TTF*+. This study is new in the respect of revealing a magnetic exchange interaction between a TTF*+ radical and a paramagnetic transition metal ion. This is due to the fact of a direct binding of the transition metal ion to the skeleton of the TTF*+ radical.

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

    DOE PAGES

    Botana, Antia S.; Pardo, Victor; Pickett, Warren E.; ...

    2016-08-09

    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. We obtained the insulating charge-ordered ground state 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. Furthermore, the analogy extends further with the main contribution to the bands near the Fermi energy coming from hybridized Ni dmore » $$_x$$2-$$_y$$2 and O $p$ states.« less

  5. 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

  6. 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.

  7. Auger electron spectroscopy study of interdiffusion, oxidation and segregation during thermal treatment of NiCr/CuNi(Mn)/NiCr thin films

    NASA Astrophysics Data System (ADS)

    Baunack, S.; Brückner, W.; Pitschke, W.; Thomas, J.

    1999-04-01

    The effect of annealing on sputter deposited thin-films NiCr/CuNi(Mn)/NiCr is studied by Auger electron depth profiling. The samples were annealed to maximum temperatures of 300°C to 550°C and investigated at ambient temperature. Auger transitions of Cu and Ni are separated by target factor analysis, principal component analysis and linear least squares fit to standard spectra. For the CuNi(Mn) layer in the as-received state AES results shows a Cu depletion caused by bombardment induced segregation. After annealing the measured Cu concentration has increased due to Ni diffusion to the interfaces. The NiCr layer is degraded with increasing annealing temperature due to formation of a chromium oxide and diffusion of Ni from the CuNi(Mn) layer. A sequence with nominal compositions near Cr 2Ni, CrNi and CrNi 2 is found. At the NiCr/CuNi(Mn) interface an interdiffusion zone phase Ni 0.6Cr 0.2Cu 0.2 is formed.

  8. Water dissociation on Ni(100), Ni(110), and Ni(111) surfaces: Reaction path approach to mode selectivity

    DOE PAGES

    Seenivasan, H.; Jackson, Bret; Tiwari, Ashwani K.

    2017-02-17

    We performed a comparative study of mode-selectivity of water dissociation on Ni(100), Ni(110), and Ni(111) surfaces at the same level of theory using a fully quantum approach based on the reaction path Hamiltonian. Calculations show that the barrier to water dissociation on the Ni(110) surface is significantly lower compared to its close-packed counterparts. Transition states for this reaction on all three surfaces involve the elongation of one of the O–H bonds. Furthermore, a significant decrease in the symmetric stretching and bending mode frequencies near the transition state is observed in all three cases and in the vibrational adiabatic approximation, excitationmore » of these softened modes results in a significant enhancement in reactivity. Inclusion of non-adiabatic couplings between modes results in the asymmetric stretching mode showing a similar enhancement of reactivity as the symmetric stretching mode. Dissociation probabilities calculated at a surface temperature of 300 K showed higher reactivity at lower collision energies compared to that of the static surface case, underlining the importance of lattice motion in enhancing reactivity. Mode selective behavior is similar on all the surfaces. Molecules with one-quantum of vibrational excitation in the symmetric stretch, at lower energies (up to 0.45 eV), are more reactive on Ni(110) than the Ni(100) and Ni(111) surfaces. But, the dissociation probabilities approach saturation on all the surfaces at higher incident energy values. Ultimately, Ni(110) is found to be highly reactive toward water dissociation among the low-index nickel surfaces owing to a low reaction barrier resulting from the openness and corrugation of the surface. These results show that the mode-selective behavior does not vary with different crystal facets of Ni qualitatively, but there is a significant quantitative effect.« less

  9. Water dissociation on Ni(100), Ni(110), and Ni(111) surfaces: Reaction path approach to mode selectivity

    NASA Astrophysics Data System (ADS)

    Seenivasan, H.; Jackson, Bret; Tiwari, Ashwani K.

    2017-02-01

    A comparative study of mode-selectivity of water dissociation on Ni(100), Ni(110), and Ni(111) surfaces is performed at the same level of theory using a fully quantum approach based on the reaction path Hamiltonian. Calculations show that the barrier to water dissociation on the Ni(110) surface is significantly lower compared to its close-packed counterparts. Transition states for this reaction on all three surfaces involve the elongation of one of the O-H bonds. A significant decrease in the symmetric stretching and bending mode frequencies near the transition state is observed in all three cases and in the vibrational adiabatic approximation, excitation of these softened modes results in a significant enhancement in reactivity. Inclusion of non-adiabatic couplings between modes results in the asymmetric stretching mode showing a similar enhancement of reactivity as the symmetric stretching mode. Dissociation probabilities calculated at a surface temperature of 300 K showed higher reactivity at lower collision energies compared to that of the static surface case, underlining the importance of lattice motion in enhancing reactivity. Mode selective behavior is similar on all the surfaces. Molecules with one-quantum of vibrational excitation in the symmetric stretch, at lower energies (up to ˜0.45 eV), are more reactive on Ni(110) than the Ni(100) and Ni(111) surfaces. However, the dissociation probabilities approach saturation on all the surfaces at higher incident energy values. Overall, Ni(110) is found to be highly reactive toward water dissociation among the low-index nickel surfaces owing to a low reaction barrier resulting from the openness and corrugation of the surface. These results show that the mode-selective behavior does not vary with different crystal facets of Ni qualitatively, but there is a significant quantitative effect.

  10. NiCd battery electrodes

    NASA Technical Reports Server (NTRS)

    Holleck, G.; Turchan, M.; Hopkins, J.

    1972-01-01

    The objective of this research program was to develop and evaluate electrodes for a negative limited nickel-cadmium cell and to prove its feasibility. The program consisted of three phases: (1) the development of cadmium electrodes with high hydrogen overvoltage characteristics, (2) the testing of positive and negative plates, and (3) the fabrication and testing of complete negative limited NiCd cells. The following electrode structures were manufactured and their physical and electrochemical characteristics were evaluated: (1) silver sinter-based Cd electrodes, (2) Teflon-bonded Cd electrodes, (3) electrodeposited Cd sponge, and (4) Cd-sinter structures. All cadmium electrode structures showed a sharp increase in potential at the end of charge, with the advent of hydrogen evolution occurring at approximately -1.3 V versus Hg/HgO. The hydrogen advent potentials on pure cadmium structures were 50 to 70 mV more cathodic than those of their silver-containing counterparts.

  11. Stability of Ni-yttria stabilized zirconia anodes based on Ni-impregnation

    NASA Astrophysics Data System (ADS)

    Klemensø, Trine; Thydén, Karl; Chen, Ming; Wang, Hsiang-Jen

    Sintering of Ni is a key stability issue for Ni-YSZ anodes, and especially infiltration based electrodes. The potential of MgO, Al 2O 3, TiO 2, CeO 2 and Ce 0.90Gd 0.10O 1.95 (CGO10) as sintering inhibitors was investigated for infiltrated Ni based anode structures. The structures were prepared from tape cast porous YSZ layers that were impregnated with Ni to form an electronic percolating phase. The Ni-YSZ structure was subsequently impregnated with the inhibitor candidate, and the stability of the structure was evaluated from conductivity measurements. Lower conductivity degradation rates were observed for samples infiltrated with the inhibitor candidates, and the best inhibitor effect was seen with higher loadings of CGO10, and CeO 2 showed similar potential. The degradation in conductivity was not visibly reflected in the microstructure as Ni coarsening in any of the cases. An adverse effect of MgO, TiO 2 and Al 2O 3 was reduced conductivity, possibly due to reaction with Ni and the formation of higher resistive phases. The Ni-infiltrated anodes were shown to have better initial electrochemical performance at 650 °C than conventionally produced Ni-YSZ anodes, but still very poor stability, and further improvement of the inhibitor approach is necessary before applying the Ni-infiltrated anodes in SOFCs.

  12. Nonenzymatic Glucose Sensor Based on In Situ Reduction of Ni/NiO-Graphene Nanocomposite

    PubMed Central

    Zhang, Xiaohui; Zhang, Zheng; Liao, Qingliang; Liu, Shuo; Kang, Zhuo; Zhang, Yue

    2016-01-01

    Ni/NiO nanoflower modified reduced graphene oxide (rGO) nanocomposite (Ni/NiO-rGO) was introduced to screen printed electrode (SPE) for the construction of a nonenzymatic electrochemical glucose biosensor. The Ni/NiO-rGO nanocomposite was synthesized by an in situ reduction process. Graphene oxide (GO) hybrid Nafion sheets first chemical adsorbed Ni ions and assembled on the SPE. Subsequently, GO and Ni ions were reduced by hydrazine hydrate. The electrochemical properties of such a Ni/NiO-rGO modified SPE were carefully investigated. It showed a high activity for electrocatalytic oxidation of glucose in alkaline medium. The proposed nonenzymatic sensor can be utilized for quantification of glucose with a wide linear range from 29.9 μM to 6.44 mM (R = 0.9937) with a low detection limit of 1.8 μM (S/N = 3) and a high sensitivity of 1997 μA/mM∙cm−2. It also exhibited good reproducibility as well as high selectivity. PMID:27792199

  13. Theoretical study of the Pb adsorption on Ni, Cr, Fe surfaces and on Ni based alloys

    NASA Astrophysics Data System (ADS)

    Bonnet, Marie-Laure; Costa, Dominique; Protopopoff, Elie; Marcus, Philippe

    2017-12-01

    Adsorption of Pb atoms on the Ni(111), Ni(100), Fe(110), and Cr(110) metallic surfaces was studied theoretically within an ab initio density functional theory approach (DFT). (√3 × √3)R30° super structures for Ni(111), and (2 × 2) for the other surfaces, corresponding to the saturation state, were considered. The preferred adsorption sites are found to be ternary sites for Ni(111), Fe(110), Cr(110) and quaternary sites for Ni(100). Adsorption on Fe and Cr is less exothermic than on Ni, by 0.16 and 0.33 eV/mol respectively. Adsorption on model surfaces of Ni based alloys was also investigated. It was found that the energy of adsorption depends mostly on the chemical composition of the ternary site, and can be described by a linear combination of the energies of adsorption on the pure metals. The nature of the second nearest neighbour of the adsorbed Pb atom has no significant influence on the adsorption energy. Average energies of adsorption were calculated in two cases: the limit of low coverage, and the saturation. The energies of adsorption of Pb at saturation on nickel base alloy surface representative of alloy 600 (Ni-15Cr-8Fe) and alloy 690 (Ni-30Cr-8Fe) were calculated to be 0.07 and 0.11 eV lower than on pure Ni respectively.

  14. Ni 3+ adsorbate dynamics on a NiO(0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Karakasidis, Theodoros E.; Vamvakopoulos, E.

    2006-05-01

    We present results concerning the dynamical behavior of a Ni 3+ adsorbate on a NiO(0 0 1) surface obtained by molecular dynamics simulations. In a first place, we examined at low temperature the position of the Ni 3+ ion as an adatom on the surface and the corresponding modification of its local environment as reflected on the pair-wise radial distribution function. The calculation of the vibrational properties of the adatom by means of the phonon local density of states (LDOS) shows that there is an anisotropic behavior both in the two principal in-plane directions as well as in the direction normal to the surface in accordance with the structural results. We compare the phonon LDOS of the Ni 3+ adatom with the corresponding results for the Ni 2+ adatom and the Ni 2+ surface cations. Static energetic calculations are indicative that the exchange of the Ni 3+ ion with a surface Ni 2+ ion could be favorable. Such a behavior is confirmed by results observed at temperatures higher than 700 K where the Ni 3+ adsorbate is located on a substitutional position on the surface and not on adatom position. The exchange takes place through simple or double exchange mechanisms. The structural and dynamical behavior of the Ni 3+ ion at the substitution position was investigated in the temperature range 700-2000 K through the calculation of the pair distribution function, the relaxed interlayer relative position (RIRP), mean-square displacements (MSDs) and phonon LDOS. Results show that in comparison with the Ni 2+ surface ions the Ni 3+ ion at substitution position is more tightly bound especially in the direction normal to the surface as is indicated by the local structure and the contraction it presents as well as its phonon LDOS. As temperature increases the binding of the Ni 3+ ion becomes less important as reflected on the physical properties mentioned above.

  15. 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

  16. Effect of thermomechanical pre-treatment on short- and long-term Ni release from biomedical NiTi.

    PubMed

    Freiberg, Katharina E; Bremer-Streck, Sibylle; Kiehntopf, Michael; Rettenmayr, Markus; Undisz, Andreas

    2014-05-01

    The effect of annealing and deformation on short-term (21days) and long-term (8months) Ni release from biomedical NiTi wires is studied. The deformation of annealed NiTi wires causes cracking and flaking of the surface oxide layer. Flaking of oxide particles does not uncover the Ni-rich layer underneath the surface oxide layer, since at sites where flaking occurs, a thin (∼25nm) layer of oxide remains on top of this Ni-rich layer. The number of cracks in the oxide and Ni-rich layer, respectively, increases with deformation, and intercrystalline crack propagation into the Ni-rich layer and the NiTi bulk is observed. In plastically deformed wires, the cracks may remain opened, providing access of immersion liquid to these zones. Characteristics and quantity of short-term Ni release are significantly affected by the pre-deformation, resulting in an up to 2 times higher total Ni release within the first 21days of deformed compared to annealed wires. Pre-deformation does not significantly influence long-term Ni release; all annealed and deformed samples exhibit similar long-term Ni release rates. The source of Ni during short-term release is the Ni contained in the surface zone of the oxide layer. For high pre-deformation, the Ni-rich layer is a second source for Ni. This second source is also the cause for Ni release in long-term immersion experiments.

  17. 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

  18. Ni nanoparticles prepared by simple chemical method for the synthesis of Ni/NiO-multi-layered graphene by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ali, Mokhtar; Remalli, Nagarjuna; Gedela, Venkataramana; Padya, Balaji; Jain, Pawan Kumar; Al-Fatesh, Ahmed; Rana, Usman Ali; Srikanth, Vadali V. S. S.

    2017-02-01

    A new chemical method was used to obtain a high yield of nickel nanoparticles (Ni-NPs). The effect of solvent (distilled water, ethylene glycol, and ethanol) and surfactant (oleic acid and polyvinyl pyrrolidinone) on the morphology and crystallinity of the synthesized Ni-NPs has been investigated. The experimental results revealed that among the solvents mentioned above, ethanol gives the best results in terms of complete reduction, controlled morphology and size distribution of Ni-NPs. The surfactants played an important role in impeding the agglomeration and surface oxidation of Ni-NPs. The surfactants also affected the morphology of the Ni-NPs. The synthesized Ni-NPs are found to be quite stable in air. The best of the synthesized Ni-NPs were effectively used as catalysts for the synthesis of Ni/NiO-multi-layered graphene using catalytic chemical vapor deposition technique.

  19. 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

  20. 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.

  1. Fine Structure in Multi-Phase Zr8Ni21-Zr7Ni10-Zr2Ni7 Alloy Revealed by Transmission Electron Microscope

    PubMed Central

    Shen, Haoting; Bendersky, Leonid A.; Young, Kwo; Nei, Jean

    2015-01-01

    The microstructure of an annealed alloy with a Zr8Ni21 composition was studied by both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The presence of three phases, Zr8Ni21, Zr2Ni7, and Zr7Ni10, was confirmed by SEM/X-ray energy dispersive spectroscopy compositional mapping and TEM electron diffraction. Distribution of the phases and their morphology can be linked to a multi-phase structure formed by a sequence of reactions: (1) L → Zr2Ni7 + L’; (2) peritectic Zr2Ni7 + L’ → Zr2Ni7 + Zr8Ni21 + L”; (3) eutectic L” → Zr8Ni21 + Zr7Ni10. The effect of annealing at 960 °C, which was intended to convert a cast structure into a single-phase Zr8Ni21 structure, was only moderate and the resulting alloy was still multi-phased. TEM and crystallographic analysis of the Zr2Ni7 phase show a high density of planar (001) defects that were explained as low-energy boundaries between rotational variants and stacking faults. The crystallographic features arise from the pseudo-hexagonal structure of Zr2Ni7. This highly defective Zr2Ni7 phase was identified as the source of the broad X-ray diffraction peaks at around 38.4° and 44.6° when a Cu-K was used as the radiation source. PMID:28793460

  2. Research of surface-oxidation epitaxy of NiO films on cube textured Ni tapes

    NASA Astrophysics Data System (ADS)

    Shi, D. Q.; Ionescu, M.; McKinnon, J.; Chen, W. M.; Dou, S. X.

    2002-05-01

    Thin films of NiO were fabricated in air by surface-oxidation epitaxy (SOE) on biaxially-textured Ni substrate, for use as buffer layers for YBCO coated conductors. The surface-oxidation conditions such as the temperature and the reaction time, as well as the cooling rate, play a determining role in the process of epitaxial growth of the NiO layer. A continuous, biaxially-aligned textured NiO layer, was obtained for a 10 min oxidation in air at 1120 °C, and a cooling rate of 150 K/h. The roughness of the NiO layer is mostly controlled by a coarsening of some NiO grains.

  3. Triclinic Ni[sub 2]Al phase in 63. 1 atomic percent NiAl

    SciTech Connect

    Murthy, A.S.; Goo, E. . Dept. of Materials Science and Engineering)

    1994-01-01

    Transmission electron microscopy (TEM) studies on the 63.1 at pct NiAl specimens aged in the L1[sub 0] phase indicate the presence of localized regions consisting of very high-density twins along with precipitates of Ni[sub 2]Al stoichiometry. In regions representative of the 7R phase, it is observed that the ordered Ni[sub 2]Al phase exists in lattice correspondence with the 7R phase. Based on the electron-diffraction results, the crystal structure of this Ni[sub 2]Al phase is determined to be triclinic, belonging to the space group P[bar 1]. This new Ni[sub 2]Al phase alternatively may be viewed as a periodically microtwinned monoclinic Ni[sub 2]Al phase, existing in coherence with the matrix L1[sub 0] phase that is also periodically microtwinned.

  4. 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.

  5. Multi-stage martensitic transformation in Ni-rich NiTi shape memory alloys

    NASA Astrophysics Data System (ADS)

    Wang, Xiebin; Verlinden, Bert; Kustov, Sergey

    Precipitation hardening is an effective way to improve the functional stability of NiTi shape memory alloys. The precipitates, mainly Ni4Ti3, could be introduced by aging treatment in Ni-rich NiTi alloys. However, the presence of Ni4Ti3 precipitates could disturb the transformation behavior, resulting in the multi-stage martensitic transformation (MMT). With the presence of MMT, it is difficult to control the transformation behavior, and thus limits the applicability of NiTi alloys. In this work, previous efforts on explaining the observed MMT are summarized. The difficulties in developing a unified explanation are discussed, and a possible way to avoid the MMT is proposed.

  6. 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.

  7. Crystallographic Orientation Effect on Electromigration in Ni-Sn Microbump

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Ting; Chen, Chih-Hao; Chakroborty, Subhendu; Wu, Albert T.

    2017-09-01

    This article addresses the reliability challenges regarding electromigration in developing three-dimensional integrated circuits (3D-ICs). The line-type sandwich structure of Ni/Sn3.5Ag(15 μm)/Ni was used to simulate microbumps to examine the reliability of electromigration in 3D-IC technology. The solder strip of Ni/Sn3.5Ag(15 μm)/Ni was stressed with a current density of 1.0 × 104 A/cm2 at 150°C. The current stressing enhanced the reaction between the solder and Ni to form Ni3Sn4, which occupied the entire joint and transformed into a Ni/Ni3Sn4/Ni structure when the solder was completely consumed. Electron backscatter diffraction was used to analyze the crystallographic characteristics of Sn and Ni3Sn4 as related to the electromigration effect. The results indicated that the crystallographic orientation of Sn plays a significant role in the Ni/Sn3.5Ag/Ni, whereas the orientation of Ni3Sn4 is the dominant factor of diffusion behavior in the Ni/Ni3Sn4/Ni.

  8. Crystallographic Orientation Effect on Electromigration in Ni-Sn Microbump

    NASA Astrophysics Data System (ADS)

    Huang, Yi-Ting; Chen, Chih-Hao; Chakroborty, Subhendu; Wu, Albert T.

    2017-07-01

    This article addresses the reliability challenges regarding electromigration in developing three-dimensional integrated circuits (3D-ICs). The line-type sandwich structure of Ni/Sn3.5Ag(15 μm)/Ni was used to simulate microbumps to examine the reliability of electromigration in 3D-IC technology. The solder strip of Ni/Sn3.5Ag(15 μm)/Ni was stressed with a current density of 1.0 × 104 A/cm2 at 150°C. The current stressing enhanced the reaction between the solder and Ni to form Ni3Sn4, which occupied the entire joint and transformed into a Ni/Ni3Sn4/Ni structure when the solder was completely consumed. Electron backscatter diffraction was used to analyze the crystallographic characteristics of Sn and Ni3Sn4 as related to the electromigration effect. The results indicated that the crystallographic orientation of Sn plays a significant role in the Ni/Sn3.5Ag/Ni, whereas the orientation of Ni3Sn4 is the dominant factor of diffusion behavior in the Ni/Ni3Sn4/Ni.

  9. 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.

  10. Pt redistribution during Ni(Pt) silicide formation

    SciTech Connect

    Demeulemeester, J.; Smeets, D.; Vantomme, A.; Van Bockstael, C.; Detavernier, C.; Comrie, C. M.; Barradas, N. P.; Vieira, A.

    2008-12-29

    We report on a real-time Rutherford backscattering spectrometry study of the erratic redistribution of Pt during Ni silicide formation in a solid phase reaction. The inhomogeneous Pt redistribution in Ni(Pt)Si films is a consequence of the low solubility of Pt in Ni{sub 2}Si compared to NiSi and the limited mobility of Pt in NiSi. Pt further acts as a diffusion barrier and resides in the Ni{sub 2}Si grain boundaries, significantly slowing down the Ni{sub 2}Si and NiSi growth kinetics. Moreover, the observed incorporation of a large amount of Pt in the NiSi seeds indicates that Pt plays a major role in selecting the crystallographic orientation of these seeds and thus in the texture of the resulting Ni{sub 1-x}Pt{sub x}Si film.

  11. 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.

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    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°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°C are found to be 0.0178 and 0.0279mV/°C, respectively.

  15. 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.

  16. 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.

  17. 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.

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

    DOE PAGES

    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

  19. Electron Probe Microanalysis of Ni Silicides Using Ni-L X-Ray Lines.

    PubMed

    Llovet, Xavier; Pinard, Philippe T; Heikinheimo, Erkki; Louhenkilpi, Seppo; Richter, Silvia

    2016-12-01

    We report electron probe microanalysis measurements on nickel silicides, Ni5Si2, Ni2Si, Ni3Si2, and NiSi, which were done in order to investigate anomalies that affect the analysis of such materials by using the Ni L3-M4,5 line (Lα). Possible sources of systematic discrepancies between experimental data and theoretical predictions of Ni L3-M4,5 k-ratios are examined, and special attention is paid to dependence of the Ni L3-M4,5 k-ratios on mass-attenuation coefficients and partial fluorescence yields. Self-absorption X-ray spectra and empirical mass-attenuation coefficients were obtained for the considered materials from X-ray emission spectra and relative X-ray intensity measurements, respectively. It is shown that calculated k-ratios with empirical mass attenuation coefficients and modified partial fluorescence yields give better agreement with experimental data, except at very low accelerating voltages. Alternatively, satisfactory agreement is also achieved by using the Ni L3-M1 line (Lℓ) instead of the Ni L3-M4,5 line.

  20. Metal-insulator transition in Au-NiO-Ni dual Schottky nanojunctions.

    PubMed

    Sun, Jia-Lin; Zhao, Xingchen; Zhu, Jia-Lin

    2009-11-11

    Ni nanowire arrays were fabricated through electrochemical deposition on a template. After a nanoscale NiO layer was formed on the top of the nanowires, a layer of Au paint was coated on the top of the nanowire arrays to construct Au-NiO-Ni dual Schottky nanojunctions, and the structure was characterized at different scales. Within a small range of voltages, extraordinary current jumps were observed at room temperature and at 77 K. The resistance switch effect can be repeated at room temperature, while switching is irreversible at low temperature. The significant change in resistance of the samples does not require doping and may find future applications.

  1. 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.

  2. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    SciTech Connect

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J.; Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th.; Delimitis, A.; Poulopoulos, P.; Fumagalli, P.; Politis, C.

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  3. Comparative study of the dissociation energies of Ni2 and Ni2(+)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Langhoff, Stephen R.

    1992-01-01

    Computations at the internally contracted averaged coupled-pair-functional level of theory yield a dissociation energy (Do) for Ni2(+) that is 0.17 eV larger than that of Ni2. This finding is consistent with the collision-induced dissociation experiments of Lian, Su, and Armentrout, but rules out the results from the resonant two-photon dissociation experiments of Lessen and Brucat, which predict that the Do value of Ni2(+) is about 1 eV larger than that of Ni2.

  4. Graphene Growth and Defects on Ni(111)

    NASA Astrophysics Data System (ADS)

    Batzill, Matthias; Lahiri, Jayeeta

    2011-03-01

    Using scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES) we have investigated the growth of graphene on Ni(111) surfaces by carbon segregation from the bulk. We reveal two distinct growth modes for graphene growth. Between 480 and 650 C graphene forms on clean Ni(111) and below 480 C graphene grows by an in-plane conversion of a surface carbide phase. This is the first time that graphene formation is observed by transformation of a surface carbide. STM indicates that a lattice-matched, one-dimensional in-plane domain boundary between graphene and the carbide forms and graphene grows by replacing Ni-atoms with carbon at this interface. In addition to the growth of graphene we will also briefly discuss atomic-scale defects that can be synthesized in Ni-supported graphene. In particular we emphasize the formation of an extended line-defect with metallic properties.

  5. Liquidus Projections of Sn-Co-Ni and Sn-Rich Sn-Ag-Co-Ni Systems

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-wen; Chen, Tung-Kai; Hsu, Chia-ming; Chang, Jui-shen; Pan, Kevin

    2014-07-01

    Alloys based on Sn and Sn-Ag are commonly used as Pb-free solders, and Ni is frequently used in barrier layers. Co has been studied as a possible alloying element in both solders and barrier layers. Thus, the Sn-Co-Ni and Sn-Ag-Co-Ni alloy systems are important for electronic soldering. Forty-nine Sn-Co-Ni alloys and 24 Sn-rich Sn-Ag-Co-Ni alloys were prepared. The primary solidification phases of these as-cast alloys were determined, and based on these results and the available phase diagrams of the constituent systems, the liquidus projections of Sn-Co-Ni ternary and Sn-Ag-Co-Ni quaternary systems at 90 at.% and 95 at.% Sn were determined. In the Sn-Co-Ni system, no ternary compound was found; (Ni,Co)3Sn2 and (Ni,Co) are continuous solid solutions, and there are eight kinds of primary solidification phases: Sn, CoSn3, CoSn2, CoSn, (Ni,Co)3Sn2, (Ni,Co), Ni3Sn, and Ni3Sn4. In the 90 at.% and 95 at.% Sn isoplethal sections of the Sn-Ag-Co-Ni liquidus projection, the primary solidification phases are CoSn2, CoSn, Ni3Sn4, and Ag3Sn.

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

    USDA-ARS?s Scientific Manuscript database

    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...

  7. Magnetic Properties of ni Nanowires Grown in Mesoporous Silicon Templates

    NASA Astrophysics Data System (ADS)

    Dolgiy, A. L.; Redko, S. V.; Yanushkevich, K. I.

    2013-05-01

    Magnetic properties of Ni nanowires electrochemically deposited into pores of mesoporous silicon template under the stationary galvanostatic regime were investigated by measuring the temperature dependence (77-700 K) of the specific magnetization σ. The measured σ values were lower with respect to that of bulk Ni. The Curie temperature, TC, derived from σ(T) for low deposition times of Ni was less (575 K) than that for bulk Ni (630 K). This is caused by dimensional effects of Ni nanoparticles.

  8. 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.

  9. Domain structure and magnetization process of a giant magnetoimpedance geometry FeNi/Cu/FeNi(Cu)FeNi/Cu/FeNi sensitive element

    NASA Astrophysics Data System (ADS)

    Kurlyandskaya, G. V.; Elbaile, L.; Alves, F.; Ahamada, B.; Barrué, R.; Svalov, A. V.; Vas'kovskiy, V. O.

    2004-09-01

    The magnetization process and the magnetic domains of the FeNi (100 nm)/Cu (2.5 nm)/FeNi (100 nm)/Cu (480 nm)/FeNi (100 nm)/Cu (2.5 nm)/FeNi (100 nm) structure were studied. This geometry consists of two FeNi/Cu/FeNi trilayers with a thick in the direction perpendicular to the plane of the sensitive element and narrow in the direction of the flowing current Cu electrode in the centre. Ferromagnet/conductor/ferromagnet is the typical geometry of magnetoimpedance thin-film-based sensitive elements used to detect small magnetic fields. Multilayered structures were prepared by rf-sputtering in a magnetic field of 100 Oe applied perpendicular to the Cu electrode in order to induce transverse magnetic anisotropy. The magnetic measurements and magnetic domain structure observations were made in magnetic fields applied one at a time parallel or perpendicular to the Cu electrode. Different magnetization processes with non-homogeneous rotations in the first case and dominant multiple nucleation and merging of domains in the second one were observed.

  10. 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.

  11. 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. © 2013 Elsevier Ltd. All rights reserved.

  12. Phase Offsets in the Critical-Current Oscillations of Josephson Junctions Based on Ni and Ni-(Ni81Fe19)xNby Barriers

    NASA Astrophysics Data System (ADS)

    Baek, B.; Schneider, M. L.; Pufall, M. R.; Rippard, W. H.

    2017-06-01

    We measure and compare the critical-current oscillation characteristics of Josephson junctions as a function of Ni thickness in different barrier structures. The characteristics dependent on the relative Ni thickness, such as the presence of nodes and the oscillation period, are consistent with a conventional, clean-limit magnetic Josephson-junction model. However, the oscillation phases have different offsets in the Ni thickness between single Ni and Ni - (Ni81Fe19)xNby -based barriers, which cannot be explained by the bulk exchange field effect alone. This effect does not originate from the ferromagnetism in (Ni81Fe19)xNby nor is it cumulative with an additional (Ni81Fe19)xNby layer. Our results present clear evidence that a nonmagnetic layer can affect the superconducting spin phase across the junction as strongly as the conventional exchange field effect.

  13. 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.

  14. Synthesis and characterizations of Ni-NiO nanoparticles on PDDA-modified graphene for oxygen reduction reaction

    PubMed Central

    2014-01-01

    We are presenting our recent research results about the Ni-NiO nanoparticles on poly-(diallyldimethylammonium chloride)-modified graphene sheet (Ni-NiO/PDDA-G) nanocomposites prepared by the hydrothermal method at 90°C for 24 h. The Ni-NiO nanoparticles on PDDA-modified graphene sheets are measured by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) pattern for exploring the structural evidence to apply in the electrochemical catalysts. The size of Ni-NiO nanoparticles is around 5 nm based on TEM observations. The X-ray diffraction (XRD) results show the Ni in the (012), (110), (110), (200), and (220) crystalline orientations, respectively. Moreover, the crystalline peaks of NiO are found in (111) and (220). The thermal gravimetric analysis (TGA) result represents the loading content of the Ni metal which is about 34.82 wt%. The electron spectroscopy for chemical analysis/X-ray photoelectron spectroscopy (ESCA/XPS) reveals the Ni0 to NiII ratio in metal phase. The electrochemical studies with Ni-NiO/PDDA-G in 0.5 M aqueous H2SO4 were studied for oxygen reduction reaction (ORR). PMID:25246863

  15. 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.

  16. 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.

  17. 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.

  18. Enhanced Electrocatalytic Activity for Water Splitting on NiO/Ni/Carbon Fiber Paper.

    PubMed

    Zhang, Ruoyu; Wei, Hehe; Si, Wenjie; Ou, Gang; Zhao, Chunsong; Song, Mingjun; Zhang, Cheng; Wu, Hui

    2016-12-28

    Large-scale growth of low-cost, efficient, and durable non-noble metal-based electrocatalysts for water splitting is crucial for future renewable energy systems. Atomic layer deposition (ALD) provides a promising route for depositing uniform thin coatings of electrocatalysts, which are useful in many technologies, including the splitting of water. In this communication, we report the growth of a NiO/Ni catalyst directly on carbon fiber paper by atomic layer deposition and report subsequent reduction and oxidation annealing treatments. The 10-20 nm NiO/Ni nanoparticle catalysts can reach a current density of 10 mA·cm(-2) at an overpotential of 189 mV for hydrogen evolution reactions and 257 mV for oxygen evolution reactions with high stability. We further successfully achieved a water splitting current density of 10 mA·cm(-2) at 1.78 V using a typical NiO/Ni coated carbon fiber paper two-electrode setup. The results suggest that nanoparticulate NiO/Ni is an active, stable, and noble-metal-free electrocatalyst, which facilitates a method for future water splitting applications.

  19. 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.

  20. Adios El Niño, Hello La Niña?

    NASA Image and Video Library

    2010-06-22

    This image from NASA European Ocean Surface Topography Mission/Jason-2 shows that the moderate El Niño of the past year has officially bowed out, leaving his cool sibling, La Niña, poised to potentially take the equatorial stage.

  1. Orbital and spin physics in LiNiO2 and NaNiO2

    NASA Astrophysics Data System (ADS)

    Reitsma, Albert J. W.; Feiner, Louis Felix; Oles, Andrzej M.

    2005-05-01

    We derive a spin-orbital Hamiltonian for a triangular lattice of eg orbital degenerate (Ni3+) transition-metal ions interacting via 90° superexchange involving (O2-) anions, taking into account the onsite Coulomb interactions on both the anions and the transition metal ions. The derived interactions in the spin-orbital model are strongly frustrated, with the strongest orbital interactions selecting different orbitals for pairs of Ni ions along the three different lattice directions. In the orbital-ordered phase, favoured in mean field theory, the spin-orbital interaction can play an important role by breaking the U(1) symmetry generated by the much stronger orbital interaction and restoring the three-fold symmetry of the lattice. As a result, the effective magnetic exchange is non-uniform and includes both ferromagnetic and antiferromagnetic spin interactions. Since ferromagnetic interactions still dominate, this offers yet insufficient explanation for the absence of magnetic order and the low-temperature behaviour of the magnetic susceptibility of stoichiometric LiNiO2. The scenario proposed to explain the observed difference in the physical properties of LiNiO2 and NaNiO2 includes small covalency of Ni-O-Li-O-Ni bonds inducing weaker interplane superexchange in LiNiO2, insufficient to stabilize orbital long-range order in the presence of stronger intraplane competition between superexchange and Jahn-Teller coupling.

  2. Eutectic superalloys strengthened by delta Ni3Cb lamellae, and gamma prime, Ni3Al precipitates.

    NASA Technical Reports Server (NTRS)

    Lemkey, F. D.; Thompson, E. R.

    1972-01-01

    Bivariant eutectic alloys, located on a liquidus surface within the Ni-Cb-Cr-Al quaternary, were identified which permitted the production of aligned delta Ni3Cb lamellae within a nichrome matrix containing the fcc precipitate gamma prime Ni3Al. The volume fraction of delta and gamma prime could be varied significantly by compositional changes. After directional solidification certain alloys possessed improved ductility and corrosion resistance with respect to the Ni3Al-Ni3Cb eutectic, while their values of tensile and creep strength approached or exceeded those for the Ni3Al-Ni3Cb pseudobinary system. The mechanical properties of the directionally solidified alloy, Ni-19.7 wt % Cb-6.0 wt % Cr-2.5 wt % Al, were evaluated. Its longitudinal strength in tension and creep was found to be superior to all advanced nickel base superalloys. It is thus demonstrated that useful properties for gas turbine airfoil applications can be achieved by reinforcing a strong and tough gamma nichrome matrix containing precipitated gamma prime by a strong lamellar intermetallic compound having greater strength at elevated temperature.

  3. Preferential diffusion in concentrated solid solution alloys: NiFe, NiCo and NiCoCr

    DOE PAGES

    Zhao, Shijun; Osetsky, Yuri; Zhang, Yanwen

    2017-02-13

    In single-phase concentrated solid-solution alloys (CSAs), including high entropy alloys (HEAs), remarkable mechanical properties are exhibited, as well as extraordinary corrosion and radiation resistance compared to pure metals and dilute alloys. But, the mechanisms responsible for these properties are unknown in many cases. In this work, we employ ab initio molecular dynamics based on density functional theory to study the diffusion of interstitial atoms in Ni and Ni-based face-centered cubic CSAs including NiFe, NiCo and NiCoCr. We model the defect trajectories over >100 ps and estimate tracer diffusion coefficients, correlation factors and activation energies. Furthermore, we found that the diffusionmore » mass transport in CSAs is not only slower than that in pure components, i.e. sluggish diffusion, but also chemically non-homogeneous. The results obtained here can be used in understanding and predicting the atomic segregation and phase separation in CSAs under irradiation conditions.« less

  4. Hydride reactivity of Ni(II)-X-Ni(II) entities: mixed-valent hydrido complexes and reversible metal reduction.

    PubMed

    Gehring, Henrike; Metzinger, Ramona; Herwig, Christian; Intemann, Julia; Harder, Sjoerd; Limberg, Christian

    2013-01-28

    After the lithiation of PYR-H(2) (PYR(2-) =[{NC(Me)C(H)C(Me)NC(6)H(3)(iPr)(2)}(2)(C(5)H(3)N)](2-)), which is the precursor of an expanded β-diketiminato ligand system with two binding pockets, its reaction with [NiBr(2) (dme)] led to a dinuclear nickel(II)-bromide complex, [(PYR)Ni(μ-Br)NiBr] (1). The bridging bromide ligand could be selectively exchanged for a thiolate ligand to yield [(PYR)Ni(μ-SEt)NiBr] (3). In an attempt to introduce hydride ligands, both compounds were treated with KHBEt(3). This treatment afforded [(PYR)Ni(μ-H)Ni] (2), which is a mixed valent Ni(I)-μ-H-Ni(II) complex, and [(PYR-H)Ni(μ-SEt)Ni] (4), in which two tricoordinated Ni(I) moieties are strongly antiferromagnetically coupled. Compound 4 is the product of an initial salt metathesis, followed by an intramolecular redox process that separates the original hydride ligand into two electrons, which reduce the metal centres, and a proton, which is trapped by one of the binding pockets, thereby converting it into an olefin ligand on one of the Ni(I) centres. The addition of a mild acid to complex 4 leads to the elimination of H(2) and the formation of a Ni(II)Ni(II) compound, [(PYR)Ni(μ-SEt)NiOTf] (5), so that the original Ni(II) (μ-SEt)Ni(II) X core of compound 3 is restored. All of these compounds were fully characterized, including by X-ray diffraction, and their molecular structures, as well as their formation processes, are discussed.

  5. 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.

  6. Exchange coupling and noncollinear magnetic states in Ni/Fen/Ni(1 0 0) multilayers

    NASA Astrophysics Data System (ADS)

    Malonda-Boungou, B. R.; Stojić, N.; Binggeli, N.; M'Passi-Mabiala, B.

    2015-01-01

    The Ni interlayer exchange coupling (IEC) and the atomic-scale magnetic configurations in fcc Ni /Fen /Ni (1 0 0) multilayers, with ultrathin Fe spacers, are investigated using first-principles density-functional theory including the noncollinear spin formalism. The trends with changing Fe thickness (n) between 3 and 5 monolayers (MLs) are examined. For n = 3 and 4 MLs, we find the ground state to display antiferromagnetic IEC between the Ni films, while for the 5-ML Fe spacer, the IEC changes into ferromagnetic. Upon reversal of the magnetization alignment, from antiparallel to parallel, between the Ni films with 3- and 4-ML thick Fe spacer, we find noncollinear magnetic configurations in the Fe layer as the lowest-energy states, which are related to the magnetic instability towards noncollinear solutions in bulk γ -Fe.

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

    DOE PAGES

    Samolyuk, German D.; Xue, Haizhou; Bei, Hongbin; ...

    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 effects 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 in Ni.

  8. Fabrication and Characterization of Ni-P-CoNiCrAlY Composite Coatings

    NASA Astrophysics Data System (ADS)

    Heydari, H.; Monirvaghefi, S. M.; Hadipour, Ali

    2017-03-01

    In this study, Ni-P-CoNiCrAlY composite coatings were deposited on 310 stainless steel. The surface morphology and cross-sectional observations were carried out using scanning electron microscopy and optical microscopy. The high-temperature corrosion of all coatings was evaluated by cyclic oxidation method. According to the results, the amounts of CoNiCrAlY particles co-deposited in all samples coated at pH = 4.7 were higher than that of those produced at pH = 6.7. Also, the surface roughness of all composite coatings coated at pH = 6.7 is lower than the coatings produced at pH = 4.7. The Ni-P-(3 g/l) CoNiCrAlY deposit produced at pH = 6.7 had the best corrosion resistance among other coatings.

  9. Synthesis and tuning the exchange bias in Ni-NiO nanoparticulate systems

    NASA Astrophysics Data System (ADS)

    Sharma, S. K.; Vargas, J. M.; Knobel, M.; Pirota, K. R.; Meneses, C. T.; Kumar, Shalendra; Lee, C. G.; Pagliuso, P. G.; Rettori, Carlos

    2010-05-01

    We report studies on exchange bias effects in Ni-NiO nanoparticles with different particle diameters/distributions and concentration of metallic nickel, which vary from 0% to 32%. The exchange bias field, Hex, depends strongly upon both particle size and the concentration of metallic Ni, being maximum (˜2.2 kOe) at 5 K for the sample with almost negligible concentration of metallic Ni, whereas the corresponding value for the sample with highest concentration of metallic Ni (˜32±5.0%) is about 0.07 kOe. The structural features of the samples have been investigated thoroughly by using the Reitveld refinement of x-ray diffraction data and high resolution transmission electron microscopy, where as the magnetic properties using superconducting quantum interference device magnetometer.

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

    SciTech Connect

    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 effects 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 in Ni.

  11. 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.

  12. Fabrication and Characterization of Ni-P-CoNiCrAlY Composite Coatings

    NASA Astrophysics Data System (ADS)

    Heydari, H.; Monirvaghefi, S. M.; Hadipour, Ali

    2017-02-01

    In this study, Ni-P-CoNiCrAlY composite coatings were deposited on 310 stainless steel. The surface morphology and cross-sectional observations were carried out using scanning electron microscopy and optical microscopy. The high-temperature corrosion of all coatings was evaluated by cyclic oxidation method. According to the results, the amounts of CoNiCrAlY particles co-deposited in all samples coated at pH = 4.7 were higher than that of those produced at pH = 6.7. Also, the surface roughness of all composite coatings coated at pH = 6.7 is lower than the coatings produced at pH = 4.7. The Ni-P-(3 g/l) CoNiCrAlY deposit produced at pH = 6.7 had the best corrosion resistance among other coatings.

  13. Influence of He-ion irradiation on thin NiMn/FeNi exchange bias films

    NASA Astrophysics Data System (ADS)

    Cantelli, V.; von Borany, J.; Grenzer, J.; Fassbender, J.; Kaltofen, R.; Schumann, J.

    2006-04-01

    Using synchrotron x-ray diffraction and reflectivity, we studied the transition from the paramagnetic NiMn phase to the chemically ordered, antiferromagnetic L10 phase of NiMn/Fe19Ni81 thin films deposited on a Si/SiO2 substrate as a function of the annealing temperature. The transformation to a dominating L10-ordered NiMn film takes place between 300 and 400 °C irrespective of the irradiation. This is also consistent with magnetization reversal measurements of the corresponding permalloy layers. The benefit of the ion irradiation is a reduction of the mosaicity for both the NiMn and the permalloy film, and a smoothening of internal interfaces.

  14. Influence of He-ion irradiation on thin NiMn/FeNi exchange bias films

    SciTech Connect

    Cantelli, V.; Borany, J. von; Grenzer, J.; Fassbender, J.; Kaltofen, R.; Schumann, J.

    2006-04-15

    Using synchrotron x-ray diffraction and reflectivity, we studied the transition from the paramagnetic NiMn phase to the chemically ordered, antiferromagnetic L1{sub 0} phase of NiMn/Fe{sub 19}Ni{sub 81} thin films deposited on a Si/SiO{sub 2} substrate as a function of the annealing temperature. The transformation to a dominating L1{sub 0}-ordered NiMn film takes place between 300 and 400 deg. C irrespective of the irradiation. This is also consistent with magnetization reversal measurements of the corresponding permalloy layers. The benefit of the ion irradiation is a reduction of the mosaicity for both the NiMn and the permalloy film, and a smoothening of internal interfaces.

  15. Nanoscale η-NiSi formation via ion irradiation of Si/Ni/Si

    NASA Astrophysics Data System (ADS)

    Banu, Nasrin; Satpati, Biswarup; Bhukta, Anjan; Dev, B. N.

    2017-01-01

    Nickel monosilicide (NiSi) has emerged as an excellent material of choice for source-drain contact applications below 45 nm node complementary metal-oxide-semiconductor technology. We have investigated the formation of nanoscale NiSi by ion irradiation of Si (˜5 nm)/Ni(˜15 nm)/Si, grown in an ultrahigh vacuum environment. Irradiation was carried out at room temperature with 1 MeV Si+ ions. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were employed for analysis. With increasing ion fluence, ion beam mixing occurs and more and more Si is incorporated into the Ni layer, and this layer gets amorphized. At an even higher fluence, a recrystallized uniform nickel monosilicide (η-NiSi) layer is formed. Several planar spacings of different Miller indices of η-NiSi have been observed in XRD and TEM. Additionally, an interesting amorphization and recrystallization behavior has been observed in the substrate Si with increasing ion fluence. To our knowledge, this has never been observed in ion irradiation of bare Si in decades of work in this area. This kind of amorphization/recrystallization in Si is apparently Ni-induced. Irradiation displaces Ni and produces a distribution of Ni in amorphized Si. Irradiation at a higher fluence produces two recrystallized Si bands in amorphous Si with concomitant accumulation of Ni at the amorphous/crystalline interfaces. On a further increase in irradiation fluence, the recrystallized Si bands again pass through amorphization and recrystallization. The total thickness of recrystallized, as well as amorphous Si, shows an oscillatory behavior as a function of ion fluence.

  16. 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.

  17. Structural and magnetic properties of Ni-Zn and Ni-Zn-Co ferrites

    NASA Astrophysics Data System (ADS)

    Knyazev, A. V.; Zakharchuk, I.; Lähderanta, E.; Baidakov, K. V.; Knyazeva, S. S.; Ladenkov, I. V.

    2017-08-01

    Ni-Zn and Ni-Zn-Co ferrite powders with nominal compositions Ni0.5Zn0.5Fe2O4 and Ni0.5Zn0.3Co0.2Fe2O4 were prepared by the solid-state reaction synthesis with periodic regrinding during the calcination at 1073 K. The structure of Ni0.5Zn0.5Fe2O4 and Ni0.5Zn0.3Co0.2Fe2O4 was refined assuming space group F d-3m. Scanning electron microscopy revealed the average sizes of the crystalline ferrite particles are 130-630 nm for Ni0.5Zn0.5Fe2O4 and 140-350 nm for Ni0.5Zn0.3Co0.2Fe2O4. The room temperature saturation magnetizations are 59.7 emu/g for Ni0.5Zn0.5Fe2O4 and 57.1 emu/g for Ni0.5Zn0.3Co0.2Fe2O4. The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. The Curie temperature tends to increase upon Zn substitution by Co, as well. The temperature dependences of magnetization measured using zero-field cooled and field cooled protocols exhibit large spin frustration and spin-glass-like behavior.

  18. 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.

  19. The first principle study of Ni2ScGa and Ni2TiGa

    NASA Astrophysics Data System (ADS)

    Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat; Iyigör, Ahmet; Candan, Abdullah

    2014-10-01

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni2TiGa and Ni2ScGa alloys in the cubic L21 structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C11, C12 and C44. We calculated elastic constants in L21 structure for Ni2TiGa and Ni2ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni2TiGa, Ni 3d states and Sc 3d states for Ni2ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni2TiGa, 0.76 states/eV Cell for Ni2ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L21 phase is unstable since the phonon calculations have imagine modes.

  20. 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.

  1. Ultrafine NiO particles induce cytotoxicity in vitro by cellular uptake and subsequent Ni(II) release.

    PubMed

    Horie, Masanori; Nishio, Keiko; Fujita, Katsuhide; Kato, Haruhisa; Nakamura, Ayako; Kinugasa, Shinichi; Endoh, Shigehisa; Miyauchi, Arisa; Yamamoto, Kazuhiro; Murayama, Hideki; Niki, Etsuo; Iwahashi, Hitoshi; Yoshida, Yasukazu; Nakanishi, Junko

    2009-08-01

    Nickel oxide (NiO) is one of the important industrial materials used in electronic substrates and for ceramic engineering. Advancements in industrial technology have enabled the manufacture of ultrafine NiO particles. On the other hand, it is well-known that nickel compounds exert toxic effects. The toxicity of nickel compounds is mainly caused by nickel ions (Ni(2+)). However, the ion release properties of ultrafine NiO particles are still unclear. In the present study, the influences of ultrafine NiO particles on cell viability were examined in vitro to obtain fundamental data for the biological effects of ultrafine green NiO and ultrafine black NiO. Ultrafine NiO particles showed higher cytotoxicities toward human keratinocyte HaCaT cells and human lung carcinoma A549 cells than fine NiO particles and also showed higher solubilities in culture medium (Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum) than fine NiO particles. In particular, the concentration of Ni(2+) released into the culture medium by ultrafine green NiO was 150-fold higher than that released by fine green NiO. The concentrations of Ni(2+) released by both types of NiO particles in an aqueous solution containing amino acids were remarkably higher than those released by NiO particles in water. Moreover, we prepared a uniform and stable dispersion of ultrafine black NiO in culture medium and examined its influence on cell viability in comparison with that of NiCl(2), a soluble nickel compound. A medium exchange after 6 h of exposure resulted in a loss of cytotoxicity in the cells exposed to NiCl(2), whereas cytotoxicity was retained in the cells exposed to NiO. Transmission electron microscope observations revealed uptake of both ultrafine and fine NiO particles into HaCaT cells. Taken together, the present results suggest that the intracellular Ni(2+) release could be an important factor that determines the cytotoxicity of NiO. Ultrafine NiO is more cytotoxic than fine

  2. A new Ni12 cluster based on polyoxometalate ligands.

    PubMed

    Zhang, Hong-Mei; Li, Yang-Guang; Lu, Ying; Clérac, Rodolphe; Zhang, Zhi-Ming; Wu, Qiong; Feng, Xiao-Jia; Wang, En-Bo

    2009-12-07

    A new Ni(12) cluster based on polyoxometalate ligands [Ni(12)(OH)(9)WO(4)(W(7)O(26)(OH))(PW(9)O(34))(3)](25-) (1) has been assembled in aqueous solution containing [PW(9)O(34)](9-), WO(4)(2-), and NiCl(2) x 6 H(2)O. The Ni(12) core in 1 shows a unique three-petal flower-shaped structure composed of three Ni(4) cubane units. Magnetic investigation indicates the presence of dominantly ferromagnetic interactions within the Ni(12) core.

  3. Microstructure and martensitic transformation of Ni-Ti-Pr alloys

    NASA Astrophysics Data System (ADS)

    Zhao, Chunwang; Zhao, Shilei; Jin, Yongjun; Guo, Shaoqiang; Hou, Qingyu

    2017-09-01

    The effect of Pr addition on the microstructure and martensitic transformation behavior of Ni50Ti50- x Pr x ( x = 0, 0.1, 0.3, 0.5, 0.7, 0.9) alloys were investigated experimentally. Results show that the microstructures of Ni-Ti-Pr alloys consist of the NiTi matrix and the NiPr precipitate with the Ti solute. The martensitic transformation start temperature decreases gradually with the increase in Pr fraction. The stress around NiPr precipitates is responsible for the decrease in martensitic transformation temperature with the increase in Pr fraction in Ni-Ti-Pr alloys.

  4. Coexistence of ferromagnetism and superconductivity in Ni/Bi bilayers.

    PubMed

    LeClair, P; Moodera, J S; Philip, J; Heiman, D

    2005-01-28

    In spite of a lack of superconductivity in bulk crystalline Bi, thin film Bi deposited on thin Ni underlayers are strong-coupled superconductors below approximately 4 K. We unambiguously demonstrate that by tuning the Ni thickness the competition between ferromagnetism and superconductivity in the Ni/Bi can be tailored. For a narrow range of Ni thicknesses, the coexistence of both a superconducting energy gap and conduction electron spin polarization are visible within the Ni side of the Ni/Bi bilayers, independent of any particular theoretical model. We believe that this represents one of the clearest observations of superconductivity and ferromagnetism coexisting.

  5. Comparison in the Oxidation and Corrosion Behavior of Aluminum and Alumina-Reinforced Ni/Ni-Co Alloy Coatings

    NASA Astrophysics Data System (ADS)

    Srivastava, Meenu; Balaraju, J. N.; Ravisankar, B.; Grips, V. K. William

    2013-02-01

    In this study, a comparison in the oxidation and corrosion behavior of Ni/Ni-Co aluminum and alumina-reinforced electrodeposited composites has been made. The developed coatings were characterized for the morphology, structure, microhardness, oxidation, and corrosion resistance. It was found that the incorporation of Al particles in NiCo matrix is higher (9 wt pct) compared to Ni matrix (1 wt pct). In the case of aluminum oxide particles, about 5 and 7 wt pct had been obtained in Ni and NiCo matrices respectively. The difference in the surface morphology was observed with respect to metallic (Al) and inert ceramic (Al2O3) particle incorporation. X-ray diffraction studies showed the presence of predominant Ni (200) reflection in the coatings. Also, peaks corresponding to Al and Al2O3 particles were present. The Ni/NiCo-Al coatings exhibited higher microhardness values at 1273 K (1000 °C) compared to alumina-reinforced coatings, indicating better thermal stability of the former coatings. The NiAl coating showed one and two orders of magnitude improved oxidation resistance compared to NiCoAl and Ni/NiCo-Al2O3 coatings, respectively. It was observed that the Ni-Al composite coating exhibited poor corrosion resistance in 3.5 pct NaCl solution compared to the other coatings studied.

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

    PubMed

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

    2013-01-04

    [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(-1) of the Ni-A state shifted to 1971, 2086 and 2098 cm(-1) in the Ni-AL state. The g-values of g(x)=2.30, g(y)=2.23 and g(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.

  7. Initial surface silicidation on Ni(110)

    NASA Astrophysics Data System (ADS)

    Fukuda, T.; Kishida, I.; Umezawa, K.

    2017-05-01

    Initial silicide formation on a Ni(110) surface was studied by scanning tunneling microscopy (STM) in an ultrahigh vacuum. Less than 0.5 ML of Si deposition initiated a Si-Ni mixed layer by displacing substrate Ni, and dark sites were formed in the STM images. A 0.5 ML-Si deposited surface showed that Si and Ni were alternately aligned in a close-packed [ 1 1 bar 0 ] row whereas Si pairs aligned along the [ 001 ] direction forming p(1×2), obliquely aligned forming c(2×2), or even straightly-and-obliquely aligned forming c(4×2) superstructures. A first-principles total energy calculation showed that the p(1×2) and c(4×2) structures had almost the same energy while the c(2×2) structure gave 13 meV/1×1 higher energy. Because a Si-Si bond in the close-packed [ 1 1 bar 0 ] row is energetically unfavorable, Si deposition of more than 0.5 ML did not further replace the substrate Ni, but silicide islands were nucleated along with a trench structure.

  8. 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.

  9. Exchange bias beyond the superparamagnetic blocking temperature of the antiferromagnet in a Ni-NiO nanoparticulate system

    NASA Astrophysics Data System (ADS)

    Roy, Aparna; De Toro, J. A.; Amaral, V. S.; Muniz, P.; Riveiro, J. M.; Ferreira, J. M. F.

    2014-02-01

    We report magnetic and exchange bias studies on Ni-NiO nanoparticulate systems synthesized by a two-step process, namely, chemical reduction of a Ni salt followed by air annealing of the dried precipitate in the temperature range 400-550 °C. Size of Ni and NiO crystallites as estimated from X-ray diffraction line broadening ranges between 10.5-13.5 nm and 2.3-4 nm, respectively. The magneto-thermal plots (M-T) of these bi-magnetic samples show a well developed peak in the vicinity of 130 K. This has been identified as the superparamagnetic blocking temperature "TB" of NiO. Interestingly, all samples exhibit exchange bias even above their respective NiO blocking temperatures, right up to 300 K, the maximum temperature of measurement. This is in contrast to previous reports since exchange bias requires the antiferromagnetic NiO to have a stable direction of its moment in order to pin the ferromagnet (Ni) magnetization, whereas such stability is unlikely above TB since the NiO is superparamagnetic, its moment flipping under thermal activation. Our observation is elucidated by taking into account the core-shell morphology of the Ni-NiO nanoparticles whereby clustering of some of these nanoparticles connects their NiO shells to form extended continuous regions of NiO, which because of their large size remain blocked at T > TB, with thermally stable spins capable of pinning the Ni cores and giving rise to exchange bias. The investigated samples may thus be envisaged as being constituted of both isolated core-shell Ni-NiO nanoparticles as well as clustered ones, with TB denoting the blocking temperature of the NiO shell of the isolated particles.

  10. Exchange bias beyond the superparamagnetic blocking temperature of the antiferromagnet in a Ni-NiO nanoparticulate system

    SciTech Connect

    Roy, Aparna E-mail: aparnaroy15@gmail.com; Ferreira, J. M. F.; De Toro, J. A.; Muniz, P.; Riveiro, J. M.; Amaral, V. S.

    2014-02-21

    We report magnetic and exchange bias studies on Ni-NiO nanoparticulate systems synthesized by a two-step process, namely, chemical reduction of a Ni salt followed by air annealing of the dried precipitate in the temperature range 400–550 °C. Size of Ni and NiO crystallites as estimated from X–ray diffraction line broadening ranges between 10.5–13.5 nm and 2.3–4 nm, respectively. The magneto-thermal plots (M-T) of these bi-magnetic samples show a well developed peak in the vicinity of 130 K. This has been identified as the superparamagnetic blocking temperature “T{sub B}” of NiO. Interestingly, all samples exhibit exchange bias even above their respective NiO blocking temperatures, right up to 300 K, the maximum temperature of measurement. This is in contrast to previous reports since exchange bias requires the antiferromagnetic NiO to have a stable direction of its moment in order to pin the ferromagnet (Ni) magnetization, whereas such stability is unlikely above T{sub B} since the NiO is superparamagnetic, its moment flipping under thermal activation. Our observation is elucidated by taking into account the core-shell morphology of the Ni-NiO nanoparticles whereby clustering of some of these nanoparticles connects their NiO shells to form extended continuous regions of NiO, which because of their large size remain blocked at T > T{sub B}, with thermally stable spins capable of pinning the Ni cores and giving rise to exchange bias. The investigated samples may thus be envisaged as being constituted of both isolated core-shell Ni-NiO nanoparticles as well as clustered ones, with T{sub B} denoting the blocking temperature of the NiO shell of the isolated particles.

  11. Enhanced cycle performance of a Na/NiCl2 battery based on Ni particles encapsulated with Ni3S2 layer

    NASA Astrophysics Data System (ADS)

    Ao, Xin; Wen, Zhaoyin; Hu, Yingying; Wu, Tian; Wu, Xiangwei; He, Qiming

    2017-02-01

    Nickel particles with different contents of Ni3S2 surface layer were prepared for their application as cathode materials in Na/NiCl2 batteries. The surface modification of nickel particles is found to prevent their growth and battery degradation during cycling. The optimum level of surface modification was determined by electrochemical tests and morphology characterization. Excessive Ni3S2 layer seems to cause particle aggregation resulting in low reversible capacity. The capacity of the cell with optimum level of Ni3S2 surface modification layer after 50 cycles is about 4 times greater than that without Ni3S2 surface modification layer.

  12. 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.

  13. 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.

  14. Ternary Ni-Co-F Nanocrystals Based Supercapacitors.

    PubMed

    Li, Xudong; Ding, Rui; Shi, Wei; Xu, Qilei; Liu, Enhui

    2017-03-14

    The ternary nickel cobalt fluorides (Ni-Co-F) nanocrystals have been solvothermally constructed for supercapacitors' positive electrode materials. The optimal Ni-Co-F (Ni/Co=2:1) has showed lightly chemical shifts in the X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS) compared with the bare Ni-F and Co-F. The Ni-Co-F (Ni/Co=2:1) has demonstrated typical square nanocrystal morphology together with mesoporous surface structure from transmission electron microscopy (TEM) observations and nitrogen sorption measurements. Due to the stronger synergistic effect of Ni and Co redox species originated from the richer Ni, Co surface electroactive sites, the Ni-Co-F (Ni/Co=2:1) has showed superior performances of specific capacitance, rate capability and charge transfer kinetics (564 F g-1 at 1 A g-1, 418 F g-1 at 16 A g-1, 449 Ω) than all the other Ni-Co-F candidates, moreover, the activated carbon (AC)//Ni-Co-F (Ni/Co=2:1) asymmetric capacitor designed through the charge-balance has delivered superior energy and power densities (18.4 Wh kg-1, 6.64 kW kg-1) together with longer cycle life (77% retention after 10,000 cycles at 4 A g-1).

  15. Nanoindentation of NiAl and Ni3Al crystals on (100), (110), and (111) surfaces: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Seymour, Richard; Hemeryck, Anne; Nomura, Ken-ichi; Wang, Weiqiang; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2014-04-01

    Molecular dynamics simulations were performed to study the nanoindentation of NiAl and Ni3Al crystals on three surfaces: (100), (110), and (111). The calculated load-displacement curves show discrete drops at certain indentation depths, indicating dislocation bursts during indentation. The hardness values for the two materials were found to depend significantly on the indented crystallographic plane: the (100) surface is the softest for NiAl and the hardest for Ni3Al. We also found distinctive deformation activities in the subsurface region in Ni3Al crystals, while dislocation loops propagate deep into the substrate in NiAl systems.

  16. Crystalline/amorphous Ni/NiO core/shell nanosheets as highly active electrocatalysts for hydrogen evolution reaction

    NASA Astrophysics Data System (ADS)

    Yan, Xiaodong; Tian, Lihong; Chen, Xiaobo

    2015-12-01

    Novel crystalline/amorphous core/shell Ni/NiO nanosheets have shown a high electrocatalytic activity in hydrogen evolution reaction (HER). In 1 M KOH, they display an HER current of 5 mA cm-2 at an overpotential of 110 mV with a good stability. It is proposed that their excellent HER performance is achieved through the synergistic effect between the Ni core and the amorphous NiO shell, where the Ni core can reduce the resistance and the amorphous NiO shell can accelerate both Volmer and Heyrovsky processes to drive HER at low overpotentials.

  17. Microstructure evolution of electroless Ni P and Ni Cu P deposits on Cu in the presence of additives

    NASA Astrophysics Data System (ADS)

    Lin, Kwang-Lung; Chang, Yu-Lan; Huang, Chiao-Chan; Li, Fang-I.; Hsu, Jen-Che

    2001-09-01

    The microstructures of electroless Ni-P and Ni-Cu-P deposits were investigated in the presence of thiourea and saccharin with AFM. The phosphorus contents and crystallinity of the deposits were investigated. Saccharin was found to refine the nodular structure of the Ni-Cu-P deposit, while not affecting the P% of the Ni-P and Ni-Cu-P deposits. On the other hand, thiourea was found to affect the P% and surface roughness of the Ni-P deposit. Thiourea does not exhibit nodular refining effect on the deposit.

  18. The acceleration intermediate phase (NiS and Ni3S2) evolution by nanocrystallization in Li/NiS2 thermal batteries with high specific capacity

    NASA Astrophysics Data System (ADS)

    Jin, Chuanyu; Zhou, Lingping; Fu, Licai; Zhu, Jiajun; Li, Deyi; Yang, Wulin

    2017-06-01

    The intermediate phase of NiS2 is thought to be a bottleneck currently to improve the overall performance of Li/NiS2 thermal batteries because of its low conductivity and close formation enthalpy between NiS2 and the intermediate phase (NiS, Ni3S2, etc). For improving the discharge performances of Li/NiS2 thermal batteries, the nano NiS2 with an average size of 85 ± 5 nm is designated as a cathode material. The electrochemical measurements show that the specific capacity of nano NiS2 cathode is higher than micro NiS2. The nano NiS2 cathode exhibits excellent electrochemical performances with high specific capacities of 794 and 654 mAh g-1 at current density of 0.1 and 0.5 A cm-2 under a cut-off voltage of 0.5 V, respectively. These results show that the rapid intermediate phase evolution from the nanocrystallization can obviously enhance use efficiency of NiS2 and improve discharge performances of thermal batteries.

  19. Mechanical properties of CuNi films

    SciTech Connect

    Brueckner, W.; Macionczyk, F.; Reiss, G. |

    1997-05-01

    CuNi alloys are widely used for precision resistors and thermocouples. Recently, they have been applied to low resistance thin film components. The mechanical properties of resistive CuNi films sputtered on both silicon wafers and flexible Kapton foils are important for reliability and lifetime of resistors. Studies of stress-temperature dependence and stress relaxation, stress-strain measurements and scanning scratch tests were performed to investigate film stresses, elastic properties, plastic flow, stress for crack initiation and film adhesion. The growth and annealing stresses were found to be tensile and can be seen as the reason for resistance degradation by stress relaxation due to plastic flow. The strains for crack initiation of 0.2% to 0.7% depending on film thickness and annealing restrict the application in resistors on flexible substrates. The film adhesion can be improved by a NiCr base-layer.

  20. Fully gapped superconductivity in Ni-pnictide superconductors BaNi2As2 and SrNi2P2

    NASA Astrophysics Data System (ADS)

    Kurita, N.; Ronning, F.; Miclea, C. F.; Tokiwa, Y.; Bauer, E. D.; Subedi, A.; Singh, D. J.; Sakai, H.; Thompson, J. D.; Movshovich, R.

    2011-01-01

    We have performed low-temperature specific heat C and thermal conductivity κ measurements on the Ni-pnictide superconductors BaNi2As2 (Tc = 0.7K) and SrNi2P2 (Tc = 1.4K). The temperature dependences C(T) and κ(T) of the two compounds are similar to the results of a number of s-wave superconductors. Furthermore, the concave field responses of the residual κ for BaNi2As2 rules out the presence of nodes on the Fermi surfaces. We postulate that fully gapped superconductivity could be universal for Ni-pnictide superconductors. Specific heat data on Ba0.6La0.4Ni2As2 shows a mild suppression of Tc and Hc2 relative to BaNi2As2.

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

    DOE PAGES

    Gong, Ming; Zhou, Wu; Kenney, Michael James; ...

    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

  2. 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

    2015-10-05

    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.

  3. A theoretical study of CH x chemisorption on the Ni(100) and Ni(111) surfaces

    NASA Astrophysics Data System (ADS)

    Siegbahn, Per E. M.; Panas, Itai

    1990-12-01

    Cluster model calculations have been performed for CH x, x = 0-3, chemisorbed on Ni(100) and Ni(111). The predicted chemisorption energies, at the present level of theory, based on bond-prepared clusters for Ni(100) are for carbon 150 kcal/mol, for CH 136 kcal/mol, for CH 2 91 kcal/mol and for CH 3 46 kcal/mol. The corresponding energies for Ni(111) are for CH 120 kcal/mol, for CH 2 88 cal/mol and for CH 3 49 kcal/mol. These chemisorption energies lead to similar stabilities for all CH x fragments on both Ni(100) and Ni(111). Large basis sets and multi-reference correlation treatments are found to be very important in particular for the multiply bonded species. The vibrational C-H stretching frequencies predicted for CH x on Ni(111) are for CH 3054 cm -1 (2980 cm -1), for CH 2 3204 cm -1 and for CH 3 2709 cm -1 (2680 cm -1), where the available experimental values are given in parent The predicted ionization spectra of adsorbed CH x are also in general agreement with experimental findings.

  4. Radiation damage buildup and dislocation evolution in Ni and equiatomic multicomponent Ni-based alloys

    NASA Astrophysics Data System (ADS)

    Levo, E.; Granberg, F.; Fridlund, C.; Nordlund, K.; Djurabekova, F.

    2017-07-01

    Single-phase multicomponent alloys of equal atomic concentrations (;equiatomic;) have proven to exhibit promising mechanical and corrosion resistance properties, that are sought after in materials intended for use in hazardous environments like next-generation nuclear reactors. In this article, we investigate the damage production and dislocation mobility by simulating irradiation of elemental Ni and the alloys NiCo, NiCoCr, NiCoFe and NiFe, to assess the effect of elemental composition. We compare the defect production and the evolution of dislocation networks in the simulation cells of two different sizes, for all five studied materials. We find that the trends in defect evolution are in good agreement between the different cell sizes. The damage is generally reduced with increased alloy complexity, and the dislocation evolution is specific to each material, depending on its complexity. We show that increasing complexity of the alloys does not always lead to decreased susceptibility to damage accumulation under irradiation. We show that, for instance, the NiCo alloy behaves very similarly to Ni, while presence of Fe or Cr in the alloy even as a third component reduces the saturated level of damage substantially. Moreover, we linked the defect evolution with the dislocation transformations in the alloys. Sudden drops in defect number and large defect fluctuations from the continuous irradiation can be explained from the dislocation activity.

  5. Easy access to Ni3N- and Ni-carbon nanocomposite catalysts.

    PubMed

    Clavel, Guylhaine; Molinari, Valerio; Kraupner, Alexander; Giordano, Cristina

    2014-07-14

    In the search for alternative materials to current expensive catalysts, Ni has been addressed as one of the most promising and, on this trail, its corresponding nitride. However, nickel nitride is a thermally unstable compound, and therefore not easy to prepare especially as nanoparticles. In the present work, a sol-gel-based process (the urea glass route) is applied to prepare well-defined and homogeneous Ni3N and Ni nanoparticles. In both cases, the prepared crystalline nanoparticles (∼25 nm) are dispersed in a carbon matrix forming interesting Ni3N- and Ni-based composites. These nanocomposites were characterised by means of several techniques, such as XRD, HR-TEM, EELS, and the reaction mechanism was investigated by TGA and IR and herein discussed. The catalytic activity of Ni3N is investigated for the first time, to the best of our knowledge, for hydrogenation reactions involving H2, and here compared to the one of Ni. Both materials show good catalytic activities but, interestingly, give a different selectivity between different functional groups (namely, nitro, alkene and nitrile groups).

  6. Atomistic structure of the coherent Ni/Ni[sub 3]Al interface

    SciTech Connect

    Farkas, D. . Dept. of Materials Science and Engineering); Campos, M.F. de; Souze, R.M. de; Goldenstein, H. . Dept. de Metalurgia)

    1994-02-01

    Most Ni-based superalloys are strengthened by the presence of coherent precipitates of an ordered fcc bases phase, known as [gamma][prime]. This phase is basically Ni[sub 3]Al. The precipitates are coherent up to a certain size and they present a cubic shape with faces oriented in the (100) planes of both matrix and precipitate. The detailed atomistic structure of this interface has not been studied. Interest in the use of ordered intermetallic compounds as possible structural materials has resulted in a large amount of work in Ni[sub 3]Al and in particular, the development of interatomic potentials for the Ni-Al system using the embedded atom technique. These potentials have been employed in the simulation of a variety of defects in Ni[sub 3]Al, including dislocation cores, grain boundaries and free surfaces. However, there is no simulation of the Ni/Ni[sub 3]Al interface structure using the embedded atom method. The objective of the present work is to carry out such a simulation. Besides the practical importance of the interface in superalloys, it is the simplest type of interface that can be modeled and it is a good starting point for interface work using the embedded atom technique.

  7. 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.

  8. Zn,Ni ferrite/NiO nanocomposite powder obtained from acetylacetonato complexes

    NASA Astrophysics Data System (ADS)

    Vucinic-Vasic, M.; Antic, B.; Kremenovic, A.; Nikolic, A. S.; Stoiljkovic, M.; Bibic, N.; Spasojevic, V.; Colomban, Ph

    2006-10-01

    The results on the synthesis, microstructure, structure and DC magnetization studies of nanocomposite Zn,Ni ferrite/NiO powder obtained by thermal decomposition of acetylacetonato complexes are reported in this paper. According to the results obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES) element analysis and multiphase Rietveld refinement, the three samples made are composed of spinel-ferrite (86.7% 96.7%) and NiO (3.3% 13.3%) phases. The compositions of the spinel-ferrite (SP) phase in the investigated samples, S1 S3, are Zn0.72Ni0.24Fe1.98O4, Zn0.56Ni0.29Fe2.07O4 and Zn0.40Ni0.40Fe2.10O4, respectively. Due to the cation deficiency in spinels, created vacancies induce a partial change in the cation valence, \\mathrm {Ni^{2+}} \\to \\mathrm {Ni^{3+}} . The vacancy distribution is found to be random at 8a and 16d cation sites, except in sample S3, where all vacancies are over octahedral sites. The x-ray line broadening due to crystallite size effect is found to be isotropic for all spinels, while the x-ray line broadening due to the strain effect is anisotropic. A correlation between the Zn2+ occupancy of the tetrahedral site and the 650 cm-1 Raman peak intensities is shown. The observed coercivity decrease and shift in hysteresis loop in the samples are caused by the interaction between spinel and NiO phase. The results of M(H) measurements point to the properties of an ensemble of interacting nanoparticles. High saturation magnetization values and superparamagnetic behaviour at room temperature point to the technological significance of the title compounds.

  9. Ni Foam-Ni3 S2 @Ni(OH)2 -Graphene Sandwich Structure Electrode Materials: Facile Synthesis and High Supercapacitor Performance.

    PubMed

    Wang, Xiaobing; Hu, Jiangjiang; Su, Yichang; Hao, Jin; Liu, Fanggang; Han, Shuang; An, Jian; Lian, Jianshe

    2017-03-23

    A novel Ni foam-Ni3 S2 @Ni(OH)2 -graphene sandwich-structured electrode (NF-NN-G) with high areal mass loading (8.33 mg cm(-2) ) has been developed by sulfidation and hydrolysis reactions. The conductivity of Ni3 S2 and Ni(OH)2 were both improved. The upper layer of Ni(OH)2 , covered with a thin graphene film, is formed in situ from the surface of the lower layer of Ni3 S2 , whereas the Ni3 S2 grown on Ni foam substrate mainly acts as a rough support bridging the Ni(OH)2 and Ni foam. The graphene stabilized the Ni(OH)2 and the electrochemical properties were effectively enhanced. The as-synthesized NF-NN-G-5mg electrode shows a high specific capacitance (2258 F g(-1) at 1 A g(-1) or 18.81 F cm(-2) at 8.33 mA cm(-2) ) and an outstanding rate property (1010 F g(-1) at 20 Ag(-1) or 8.413 F cm(-2) at 166.6 mA cm(-2) ). This result is around double the capacitance achieved in previous research on Ni3 S2 @Ni(OH)2 /3DGN composites (3DGN=three-dimensional graphene network). In addition, the as-fabricated NF-NN-G-5mg composite electrode has an excellent cycle life with no capacitance loss after 3000 cycles, indicating a potential application as an efficient electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Selective laser ionisation of radionuclide 63Ni

    NASA Astrophysics Data System (ADS)

    Tsvetkov, G. O.; D'yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Firsov, V. A.; Panchenko, V. Ya.

    2017-02-01

    We report a search for a scheme of selective laser stepwise ionisation of radionuclide 63Ni by radiation of a dye laser pumped by a copper vapour laser. A three-stage scheme is found with ionisation through an autoionising state (AIS): 3d 84s2 3F4(E = 0) → 3d 94p 1Fo3(31030.99 cm-1) → 3d 94d 2[7/2]4(49322.56 cm-1) → AIS(67707.61 cm-1) which, by employing saturated radiation intensities provides the ionisation selectivity of above 1200 for 63Ni.

  11. NiCo₂O₄-Based Supercapacitor Nanomaterials.

    PubMed

    Wang, Chenggang; Zhou, E; He, Weidong; Deng, Xiaolong; Huang, Jinzhao; Ding, Meng; Wei, Xianqi; Liu, Xiaojing; Xu, Xijin

    2017-02-15

    In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo₂O₄ fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo₂O₄ utilized as the supercapacitor electrodes.

  12. Ionizing Radiation Effects in Ni Nanotubes

    NASA Astrophysics Data System (ADS)

    Shlimas, D.; Kozlovsky, A.; Shumskaya, A.; Kaniukov, E.; Ibragimova, M.; Zdorovets, M.; Kadyrzhanov, K.

    2017-01-01

    Polycrystalline nickel nanotubes with diameter of 380 nm and wall thickness 95 nm were synthesized by electrochemical method using PET track-etched membranes with thickness of 12 μm. A comprehensive study of the structural, morphological and electrical characteristics of Ni nanotubes irradiated with C+13 ions with energy 1.75 MeV/nucleon and fluence ranging from 109 to 5 × 1011 cm-2 was carried out. The ability of modification of structural parameters such as lattice parameter and the average size of crystallites and conductivity of Ni nanotubes by irradiation was shown.

  13. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    NASA Astrophysics Data System (ADS)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace

    2017-02-01

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of 100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix.

  14. 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.

  15. 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.

  16. Structural study of radiolytic catalysts Ni-Ce/Al2O3 and Ni-Pt/Al2O3

    NASA Astrophysics Data System (ADS)

    Seridi, F.; Chettibi, S.; Keghouche, N.; Beaunier, P.; Belloni, J.

    2017-01-01

    Ni-Ce and Ni-Pt bimetallic catalysts supported over α-Al2O3 are synthesized by using co-impregnation method, and then reduced, each via radiolytic process or thermal H2-treatment. For Ni-Ce/Al2O3, the structural study reveals that Ce is alloyed with Ni as Ce2Ni7 nanoparticles in the radiation-reduced catalysts, while it segregates to the surface in the form of CeO2 in the H2-reduced catalysts. For Ni-Pt/Al2O3 radiolytic catalysts, Ni, Pt, NiPt and Ni3Pt nanoparticles, which size is 3.5 nm, are observed. When the radiation-reduced samples are tested in the benzene hydrogenation, they both display high conversion rate. However, the Ni-Pt/Al2O3 is more efficient than Ni-Ce/Al2O3. The performance of the catalysts is correlated with the high dispersion of the metal and the presence of intermetallic Ni-Pt and Ni-Ce phases. It is compared to that of other radiolytic monometallic/oxide catalysts of the literature.

  17. Anomalous self-reduction of layered double hydroxide (LDH): from α-Ni(OH)2 to hexagonal close packing (HCP) Ni/NiO by annealing without a reductant.

    PubMed

    Ge, X; Gu, C D; Wang, X L; Tu, J P

    2015-01-21

    The traditional concept that nickel layered double hydroxide (Ni LDH, also known as α-Ni(OH)2) converts to NiO after annealing has been taken without doubt and utilized to fabricate NiO for years. This work reports that an anomalous self-reduction phenomenon can occur for Ni LDH synthesized from an ionic liquid system.

  18. NiO Nanofibers as a Candidate for a Nanophotocathode

    PubMed Central

    Macdonald, Thomas J.; Xu, Jie; Elmas, Sait; Mange, Yatin J.; Skinner, William M.; Xu, Haolan; Nann, Thomas

    2014-01-01

    p-type NiO nanofibers have been synthesized from a simple electrospinning and sintering procedure. For the first time, p-type nanofibers have been electrospun onto a conductive fluorine doped tin oxide (FTO) surface. The properties of the NiO nanofibers have been directly compared to that of bulk NiO nanopowder. We have observed a p-type photocurrent for a NiO photocathode fabricated on an FTO substrate.

  19. 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.

  20. 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

  1. 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.

  2. Transient Behavior of Ni@NiOx Functionalized SrTiO3 in Overall Water Splitting

    PubMed Central

    2017-01-01

    Transients in the composition of Ni@NiOx core–shell co-catalysts deposited on SrTiO3 are discussed on the basis of state-of-the-art continuous analysis of photocatalytic water splitting, and post-XPS and TEM analyses. The formation of excessive hydrogen (H2:O2 ≫ 2) in the initial stages of illumination demonstrates oxidation of Ni(OH)2 to NiOOH (nickel oxyhydroxide), with the latter catalyzing water oxidation. A disproportionation reaction of Ni and NiOOH, yielding Ni(OH)2 with residual embedded Ni, occurs when illumination is discontinued, which explains repetitive transients in (excess) hydrogen and oxygen formation when illumination is reinitiated. PMID:28405491

  3. Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions.

    PubMed

    Robotin, B; Ispas, A; Coman, V; Bund, A; Ilea, P

    2013-11-01

    This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model.

  4. On the orientations of abnormally grown grains in nanocrystalline Ni and Ni-Fe.

    PubMed

    Klement, U; da Silva, M; Skrotzki, W

    2008-06-01

    The scanning electron microscopy-based electron backscatter diffraction technique has been used to determine grain orientations of abnormally grown grains upon annealing in nanocrystalline Ni and Ni-20 at.% Fe electrodeposits. The results show that in nanocrystalline Ni and Ni-Fe, the first grown grains that can be detected are 411 oriented with respect to the normal direction (411//ND). Upon annealing, further grain growth occurs and the dominant orientation of the abnormally growing grains changes from 411//ND to 111//ND. Twinning is found to be the mechanism responsible for the orientation change and is for the first time described in connection with abnormal grain growth in nanocrystalline materials. This means that well-known models for the formation of annealing twins (initially introduced in connection with recrystallization) also seem to apply in nanocrystalline materials.

  5. Ferroelectric strain modulation of antiferromagnetic moments in Ni/NiO ferromagnet/antiferromagnet heterostructures

    NASA Astrophysics Data System (ADS)

    Zhang, Yu-Jun; Chen, Jia-Hui; Li, Liang-Liang; Ma, Jing; Nan, Ce-Wen; Lin, Yuan-Hua

    2017-05-01

    Electric field manipulation of magnetic properties has attracted a lot of research interest recently in solid-state physics. However, ferroelectric strain modulation of antiferromagnetic (AFM) layer is rarely studied in ferromagnet/antiferromagnet/ferroelectric heterostructures. In this paper, we prepared a Ni/NiO(001) heterostructure on ferroelectric Pb (Mg1/3N b2 /3 ) 0.7T i0.3O3(001 ) substrates and observed an out-of-plane electric field modulation of exchange bias and magnetic anisotropy in the Ni layer. The exchange bias was easily eliminated by an electric field cycle, which was due to the AFM domain switching induced by piezoelectric strain in the NiO layer. Synchrotron x ray linear dichroism results confirmed the AFM moment alignment induced by ferroelectric strain as well. Our work showed a promising strategy to manipulate AFM moments and domains, serving the blooming AFM spintronics.

  6. Optical, magnetic, and microwave properties of Ni/NiO nanoparticles

    NASA Astrophysics Data System (ADS)

    Rostamnejadi, Ali; Bagheri, Saber

    2017-04-01

    In this research, the optical, magnetic, and microwave properties of NiO and Ni/NiO nanoparticles have been studied. The absorbance spectra of the samples show the electronic d-d excitations with energy band gap of about 3.8 eV. The magnetization measurement confirms the existence of ferromagnetic phase at room temperature, which could be originated from the uncompensated surface spins or ferromagnetic clusters in the antiferromagnetic ground state of NiO nanoparticles. The microwave parameters such as ac conductivity, skin depth, electric and magnetic loss tangents, attenuation constant, and reflection loss have been calculated. While both magnetic and dielectric relaxation processes have been observed in the complex permeability and permittivity, the microwave absorption is mainly attributed to the dielectric relaxation processes.

  7. 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.

  8. 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.

  9. 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.

  10. Bottom and top AF/FM interfaces of NiFe/FeMn/NiFe trilayers

    NASA Astrophysics Data System (ADS)

    Nascimento, V. P.; Passamani, E. C.; Alvarenga, A. D.; Biondo, A.; Pelegrini, F.; Saitovitch, E. Baggio

    2008-01-01

    X-ray reflectivity analyses were performed in the Si/WTi (7 nm)/NiFe (30 nm)/FeMn (13 nm)/NiFe (10 nm)/WTi (7 nm) exchange-biased system prepared by magnetron sputtering under three different argon working pressures. Layer-by-layer analyses were realized in order to obtain the interfacial roughness parameters quantitatively. For a fixed argon pressure, the root-mean-square roughness (including the atomic grading) of the upper (FeMn/NiFe) interface are greater than that for the lower one in all studied samples. Argon working pressure also has severe influence over the NiFe/FeMn interfaces, being more pronounced at the upper interfaces.

  11. Epitaxial fabrication of two-dimensional NiSe2 on Ni(111) substrate

    NASA Astrophysics Data System (ADS)

    Shao, Yan; Song, Shiru; Wu, Xu; Qi, Jing; Lu, Hongliang; Liu, Chen; Zhu, Shiyu; Liu, Zhongliu; Wang, Jiaou; Shi, Dongxia; Du, Shixuan; Wang, Yeliang; Gao, H.-J.

    2017-09-01

    Two-dimensional (2D) transition metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, and catalysis. A high-quality 2D film of NiSe2, a TMD material, is grown epitaxially by a single step direct selenization of a Ni(111) substrate. X-ray photoemission spectroscopy, low-energy electron diffraction, scanning tunneling microscopy, and density functional theory calculations are combined to confirm the formation and structure of the film, revealing a (√3 × √3) superlattice of the NiSe2 film formed on the (√7 × √7) superlattice of the substrate. Fabrication of this 2D NiSe2 film opens opportunities to research its applications, especially for electrocatalysis and energy storage devices.

  12. El Niño in a changing climate.

    PubMed

    Yeh, Sang-Wook; Kug, Jong-Seong; Dewitte, Boris; Kwon, Min-Ho; Kirtman, Ben P; Jin, Fei-Fei

    2009-09-24

    El Niño events, characterized by anomalous warming in the eastern equatorial Pacific Ocean, have global climatic teleconnections and are the most dominant feature of cyclic climate variability on subdecadal timescales. Understanding changes in the frequency or characteristics of El Niño events in a changing climate is therefore of broad scientific and socioeconomic interest. Recent studies show that the canonical El Niño has become less frequent and that a different kind of El Niño has become more common during the late twentieth century, in which warm sea surface temperatures (SSTs) in the central Pacific are flanked on the east and west by cooler SSTs. This type of El Niño, termed the central Pacific El Niño (CP-El Niño; also termed the dateline El Niño, El Niño Modoki or warm pool El Niño), differs from the canonical eastern Pacific El Niño (EP-El Niño) in both the location of maximum SST anomalies and tropical-midlatitude teleconnections. Here we show changes in the ratio of CP-El Niño to EP-El Niño under projected global warming scenarios from the Coupled Model Intercomparison Project phase 3 multi-model data set. Using calculations based on historical El Niño indices, we find that projections of anthropogenic climate change are associated with an increased frequency of the CP-El Niño compared to the EP-El Niño. When restricted to the six climate models with the best representation of the twentieth-century ratio of CP-El Niño to EP-El Niño, the occurrence ratio of CP-El Niño/EP-El Niño is projected to increase as much as five times under global warming. The change is related to a flattening of the thermocline in the equatorial Pacific.

  13. A new 1 --> infinity [Ni7] cluster in LaNi7In6 and distorted bcc indium cubes in LaNiIn4.

    PubMed

    Kalychak, Y M; Zaremba, V I; Galadzhun, Y V; Miliyanchuk, K Y; Hoffmann, R D; Pöttgen, R

    2001-12-17

    LaNiIn4 and LaNi7In, were prepared by reaction of the elements in an arc melting furnace and subsequent annealing at 870 K for five weeks. Both compounds were investigated by X-ray diffraction on powders and single crystals and the structures were refined from single-crystal data: Cmcm, a = 448.2(1), b = 1689.5(4). c = 722.1(1) pm, wR2 = 0.0340, 472 F2 values, 24 variables for LaNiIn4, and Ibam, a = 806.6(2). b = 924.8(2). c = 1246.5(2) pm. wR2 = 0.0681. 726 F2 values and 40 variables for LaNi7In,. LaNiIn4 adopts the YNiAl4-type structure. The nickel and indium atoms form a three-dimensional infinite [NiIn4] polyanion in which the lanthanum atoms fill distorted hexagonal channels. No Ni-Ni contacts occur. The indium substructure consists of distorted bcc-like indium cubes. LaNi7In6 crystallizes with a peculiar new structure type. The nickel atoms build a 1 --> infinity [Ni7] cluster unit with Ni-Ni distances ranging from 249 to 269 pm. The cluster units are enveloped by indium atoms. These larger units show an orthorhombic rod packing with the lanthanum atoms filling the space between the rods. Several nickel clusters in ternary rare earth metal nickel indides and the structural relations of the LaNi7In6 structure with the cubic NaZn13 type are discussed.

  14. Electronic structure of cyclohexane on Ni(111)

    NASA Astrophysics Data System (ADS)

    Huber, W.; Zebisch, P.; Bornemann, T.; Steinrück, H.-P.

    1990-12-01

    Mono- and multilayers of cyclohexane adsorbed on a Ni(111) surface have been studied by angle resolved UV photoelectron spectroscopy (ARUPS) using linearly polarized synchrotron radiation, temperature programmed desorption (TPD) and low energy electron diffraction (LEED). Cyclohexane is molecularly adsorbed on Ni(111) at temperatures below 200 K and desorbs without dehydrogenation. Desorption from the first layer exhibits zeroth-order desorption behavior indicative of desorption from two-dimensional islands. The first layer exhibits a well ordered ( 7 × 7)R19.1° LEED structure starting at coverages of 0.04 ML up to the saturation coverage of 0.143 ML, also indicative of island formation. For cyclohexane in the first layer the binding energies of the various molecular levels are, apart from an overall shift to smaller values by 0.7 eV, within ± 0.1 eV identical to those of condensed cyclohexane. This absence of chemical shifts indicates that there is only very weak (if any) chemical interaction between cyclohexane and the Ni(111) surface. From the normal emission ARUPS spectra and symmetry selection rules we conclude that the symmetry of cyclohexane adsorbed on Ni(111) is lower than C 3v. This is attributed to a slightly inclined adsorption geometry with intramolecular C 3v symmetry of the adsorbed molecules.

  15. nière's Disease

    MedlinePlus

    ... tubes and sacs (membranous labyrinth) filled with endolymph. Credit: NIH/NIDCD The symptoms of Ménière’s disease are ... fluid to prevent dizziness. Location of endolymphatic sac Credit: NIH/NIDCD Surgery. Surgery may be recommended when ...

  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. Coatings on NiTi Alloy

    NASA Astrophysics Data System (ADS)

    Kei, C. C.; Yu, Y. S.; Racek, J.; Vokoun, D.; Šittner, P.

    2014-07-01

    Atomic layer deposition is introduced as a method suitable for preparation of Al2O3 layers on the surface of NiTi medical devices such as stents because of the excellent thickness control and conformal protective coating on complex structures. The corrosion properties of NiTi plates with Al2O3 coatings of various thicknesses in an environment similar to that occurring in the human body were studied using open circuit potential, potentiostatic electrochemical impedance spectroscopy, and cyclic polarization tests. It shows that the layer thickness plays a key role in the inhibition of corrosion. The thinner layers are more diffuse and make it easier for anodic reaction of passive NiTi with protective TiO2 underneath of Al2O3, while the thicker layers have the barrier effect with local pores initiating pitting corrosion. The results of our electrochemical experiments consistently show that corrosion properties of thick Al2O3 coatings on NiTi plate are inferior compared to the thin layers.

  18. 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.

  19. Martensitic transformation of the Ni[sub 2]Al phase in 63. 1 at. % NiAl

    SciTech Connect

    Murthy, A.S.; Goo, E. . Dept. of Materials Science and Engineering)

    1993-07-01

    Electron diffraction and high resolution electron microscopy of 63.1 at.% NiAl have shown that the metastable hexagonal Ni[sub 2]Al precipitate, coherent in the B2 matrix phase, transforms concurrently with the martensitic transformation of the B2 NiAl matrix to the L1[sub 0] phase. The Ni[sub 2]Al precipitate that is coherent with the L1[sub 0] phase in monoclinic.

  20. Ni K-Edge XANES Analyses of Residual Ni Catalyst in Carbon Nanofiber Using Full Multiple Scattering Theory

    SciTech Connect

    Ushiro, Mayuko; Ohminami, Kenryo; Nagamatsu, Shin-ichi; Fujikawa, Takashi; Asakura, Kiyotaka

    2007-02-02

    Residual Ni species after Ni removal treatment of carbon nanofibers have been investigated by use of XAFS analyses. Most of the Ni impurities are in Ni monomer which is located on defects in carbon nanofibers. The XAFS analyses combined with the multiple scattering theory give useful information on nano-structures of small amount species. Molecular orbital calculation also support the results from the XAFS analyses.

  1. Short-range order and stability in Gd-Ni and Y-Ni systems

    SciTech Connect

    Colinet, C.; Pasturel, A.; Buschow, K.H.J.

    1987-11-01

    We present experimental determinations of the enthalpies of formation of various amorphous and crystalline alloys in the Gd-Ni and Y-Ni systems. For the amorphous alloys, crystallization enthalpy is studied by means of differential scanning calorimetry. The enthalpy effects observed in amorphous alloys point to the occurrence of chemical short-range order. This manifestation is analyzed using microscopic calculations of chemical short-range order based on a tight-binding Hamiltonian.

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

    SciTech Connect

    Warren, Oden 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 (1x1) and (1x2) 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.

  3. 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.

  4. 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.

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

    SciTech Connect

    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 (similar to 800 mA h g(-1) after similar to 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.

  6. 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

  7. 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.

  8. 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.

  9. Study of the magnetic microstructure of Ni/NiO nanogranular samples above the electric percolation threshold by magnetoresistance measurements.

    PubMed

    Del Bianco, L; Spizzo, F; Tamisari, M; Calbucci, M; Allia, P

    2012-08-01

    Magnetoresistance measurements have been exploited to gain information on the magnetic microstructure of two Ni/NiO nanogranular materials consisting of Ni nanocrystallites (mean size of the order of 10 nm) embedded in a NiO matrix and differing in the amount of metallic Ni, ~33 and ~61 vol%. The overall conductance of both samples is metallic in character, indicating that the Ni content is above the percolation threshold for electric conductivity; the electric resistivity is two orders of magnitude smaller in the sample with higher Ni fraction (10(-5) Ωm against 10(-3) Ωm). An isotropic, spin-dependent magnetoresistance has been measured in the sample with lower Ni content, whereas both isotropic and anisotropic magnetoresistance phenomena coexist in the other material. This study, associated with magnetization loop measurements and the comparison with the exchange bias effect, allows one to conclude that in the sample with lower Ni content neither the physical percolation of the Ni nanocrystallites nor the magnetic percolation (i.e., formation of a homogeneous ferromagnetic network) are achieved; in the other sample physical percolation is reached while magnetic percolation is still absent. In both behaviors, a key role is played by the NiO matrix, which brings about a magnetic nanocrystallite/matrix interface exchange energy term and rules both the direct exchange interaction among Ni nanocrystallites and the magnetotransport properties of these nanogranular materials.

  10. 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

  11. NiSn4 Formation in As-Soldered Ni-Sn and ENIG-Sn Couples

    NASA Astrophysics Data System (ADS)

    Belyakov, S. A.; Gourlay, C. M.

    2012-12-01

    Most research on Sn-Ni solder reactions has focused on the interfacial reactions with the substrate, whereas the microstructure which develops above the intermetallic layers has not been studied in detail. This paper shows that nonequilibrium NiSn4 forms during solidification of the bulk solder in Sn-Ni and Sn-electroless nickel immersion gold (ENIG) solder reactions. With both substrates, the bulk solder solidified to contain Sn-NiSn4 eutectic and primary Ni3Sn4 crystals, and the interfacial layers contained a Ni3Sn4 reaction layer on the Sn side. It is found that Cu, present from dissolution of Cu through cracks in the ENIG layer, promotes the formation of Sn-Ni3Sn4 eutectic. Thus, Sn-ENIG couples contained both Sn-NiSn4 and Sn-Ni3Sn4 eutectic. It is further shown that NiSn4 is not stable at soldering temperatures and that, during isothermal holding at 270°C to 220°C, NiSn4 transforms into Ni3Sn4 and liquid or β-Sn.

  12. 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

  13. Structure relaxation and crystallization of the CoW-CoNiW-NiW electrodeposited alloys

    PubMed Central

    2014-01-01

    The structure of electrolytically deposited nanocrystalline alloys of the CoW-CoNiW-NiW systems under low-temperature heating was investigated by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), and analytical methods such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Structural relaxation and crystallization were investigated at temperatures of 200°C to 300°C. The structural and compositional inhomogeneities were found in the CoW-CoNiW-NiW alloys, while the local changes in composition were found to reach 18 at.%. Nanocrystals in the alloys grew most intensely in the presence of a free surface, and we found their nuclei density to range from 2 × 1023 /m3 to 3 × 1023 /m3. It was determined that the local diffusion coefficient ranged from 0.9 to 1.7 10−18 m2/s, which could be explained by the prevalence of surface diffusion. The data gathered in these investigations can be used to predict the thermal stability of CoW-CoNiW-NiW alloys. PMID:24506913

  14. 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

    2016-04-06

    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.

  15. Cathodic stripping voltammetry of nickel: sonoelectrochemical exploitation of the Ni(III)/Ni(II) couple.

    PubMed

    Davis, James; Vaughan, D Huw; Stirling, David; Nei, Lembit; Compton, Richard G

    2002-07-19

    The exploitation of the Ni(III)/Ni(II) transition as a means of quantifying the concentration of nickel within industrial samples was assessed. The methodology relies upon the reagentless electrodeposition of Ni onto a glassy carbon electrode and the subsequent oxidative conversion of the metallic layer to Ni(III). The analytical signal is derived from a cathodic stripping protocol in which the reduction of the Ni(III) layer to Ni(II) is monitored through the use of square wave voltammetry. The procedure was refined through the introduction of an ultrasonic source which served to both enhance the deposition of nickel and to remove the nickel hydroxide layer that results from the measurement process. A well-defined stripping peak was observed at +0.7 V (vs. Agmid R:AgCl) with the response found to be linear over the range 50 nM to 1 muM (based on a 30 s deposition time). Other metal ions such as Cu(II), Mn(II), Cr(III), Pb(II), Cd(II), Zn(II), Fe(III) and Co(II) did not interfere with the response when present in hundred fold excess. The viability of the technique was evaluated through the determination of nickel within a commercial copper nickel alloy and validated through an independent comparison with a standard ICP-AES protocol.

  16. 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.

  17. Influence of Ni on Martensitic Phase Transformations in NiTi Shape Memory Alloys

    SciTech Connect

    Frenzel, J.; George, Easo P; Dlouhy, A.; Somsen, Ch.; Wagner, M. F.-X; Eggeler, G.

    2010-01-01

    High-precision data on phase transformation temperatures in NiTi, including numerical expressions for the effect of Ni on M{sub S}, M{sub F}, A{sub S}, A{sub F} and T{sub 0}, are obtained, and the reasons for the large experimental scatter observed in previous studies are discussed. Clear experimental evidence is provided confirming the predictions of Tang et al. 1999 regarding deviations from a linear relation between the thermodynamic equilibrium temperature and Ni concentration. In addition to affecting the phase transition temperatures, increasing Ni contents are found to decrease the width of thermal hysteresis and the heat of transformation. These findings are rationalized on the basis of the crystallographic data of Prokoshkin et al. 2004 and the theory of Ball and James. The results show that it is important to document carefully the details of the arc-melting procedure used to make shape memory alloys and that, if the effects of processing are properly accounted for, precise values for the Ni concentration of the NiTi matrix can be obtained.

  18. Epitaxial NiWO4 films on Ni(110): Experimental and theoretical study of surface stability

    NASA Astrophysics Data System (ADS)

    Doudin, N.; Pomp, S.; Blatnik, M.; Resel, R.; Vorokhta, M.; Goniakowski, J.; Noguera, C.; Netzer, F. P.; Surnev, S.

    2017-05-01

    Despite the application potential of nickel tungstate (NiWO4) in heterogeneous catalysis, humidity and gas sensing, etc, its surfaces have essentially remained unexplored. In this work, NiWO4 nanoparticles and films with the wolframite structure have been grown via a solid-state reaction of (WO3)3 clusters and a NiO(100) film on a Ni(110) crystal surface and characterized by a variety of experimental techniques, including x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM) and x-ray diffraction (XRD), combined with ab-initio density functional theory (DFT) calculations. NiWO4 grows initially as three-dimensional (3D) crystalline nanoparticles displaying mainly two crystalline facets vicinal to the (100) surface, which merge with increasing the (WO3)3 coverage into a quasi-continuous epitaxial film. The DFT results provide an account of the energetics of NiWO4 low index surfaces and highlight the role of faceting in the stabilization of extended polar (100) terraces. These combined experimental and theoretical results show that interaction with a metal substrate and vertical confinement may stabilize oxide nano-objects with high energy facets, able to enhance their reactivity.

  19. Structure relaxation and crystallization of the CoW-CoNiW-NiW electrodeposited alloys

    NASA Astrophysics Data System (ADS)

    Pustovalov, Evgeny V.; Modin, Evgeny B.; Voitenko, Oleg V.; Fedorets, Aleksander N.; Dubinets, Aleksander V.; Grudin, Boris N.; Plotnikov, Vladimir S.; Grabchikov, Sergey S.

    2014-02-01

    The structure of electrolytically deposited nanocrystalline alloys of the CoW-CoNiW-NiW systems under low-temperature heating was investigated by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), and analytical methods such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Structural relaxation and crystallization were investigated at temperatures of 200°C to 300°C. The structural and compositional inhomogeneities were found in the CoW-CoNiW-NiW alloys, while the local changes in composition were found to reach 18 at.%. Nanocrystals in the alloys grew most intensely in the presence of a free surface, and we found their nuclei density to range from 2 × 1023 /m3 to 3 × 1023 /m3. It was determined that the local diffusion coefficient ranged from 0.9 to 1.7 10-18 m2/s, which could be explained by the prevalence of surface diffusion. The data gathered in these investigations can be used to predict the thermal stability of CoW-CoNiW-NiW alloys.

  20. Cold Spray Deposition of Ni and WC-Reinforced Ni Matrix Composite Coatings

    NASA Astrophysics Data System (ADS)

    Alidokht, S. A.; Vo, P.; Yue, S.; Chromik, R. R.

    2017-09-01

    Ni-WC composites are ideal protective coatings against wear and are often fabricated using laser cladding and thermal spray processes, but the high temperatures of these processes result in decarburization, which deteriorates the performance of the coating. Cold spray has the potential to deposit Ni-WC composite coatings and retain the composition of the initial WC feedstock. However, the insignificant plastic deformation of hard WC particles makes it difficult to build up a high WC content coating by cold spray. By using three different WC powder sizes, the effect of feedstock powder size on WC retention was tested. To improve WC retention, a WC/Ni composite powder in mixture with Ni was also sprayed. Microstructural characterization, including the deformed structure of Ni splats, retention, distribution, and fragmentation of WC, was performed by scanning electron microscopy. An improvement in WC retention was achieved using finer WC particles. Significant improvement in WC particles retention was achieved using WC/Ni composite powder, with the WC content in the coating being close to that of the feedstock.

  1. Constitution of the Sr-Ni-O system

    SciTech Connect

    Zinkevich, M. . E-mail: zinkevich@mf.mpg.de

    2005-09-15

    The constitution of the Sr-Ni-O system was studied experimentally for the first time. Samples were prepared either from SrCO{sub 3} and NiO or from Sr(NO{sub 3}){sub 2} and Ni(NO{sub 3}){sub 2}.6H{sub 2}O and characterized by high-temperature X-ray powder diffraction, scanning electron microscopy, thermogravimetric and differential thermal analyses. In the SrO-NiO quasibinary system an eutectic reaction: liquid-bar SrO+NiO was found to occur at 1396+/-5{sup o}C, while the homogeneity range of terminal solid solutions is negligible. Thermodynamic calculations using the regular solution model for the liquid and rocksalt-type phases were employed to predict liquidus and solidus curves. Three ternary compounds, SrNiO{sub 2.5}, Sr{sub 5}Ni{sub 4}O{sub 11}, and Sr{sub 9}Ni{sub 7}O{sub 21} were observed in the samples prepared from nitrate solutions, but only Sr{sub 9}Ni{sub 7}O{sub 21} was proved to be thermodynamically stable in air up to 1030+/-6{sup o}C. When heating in air, SrNiO{sub 2.5} and Sr{sub 5}Ni{sub 4}O{sub 11} were found to transform irreversibly into a mixture of Sr{sub 9}Ni{sub 7}O{sub 21} and NiO. Isothermal section of the SrO-NiO-O subsystem, which represents phase equilibria at 950-1030{sup o}C as well as an isobaric section of the Sr-Ni-O system in air were constructed.

  2. 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.

  3. The accumulation of Ni in serpentines and garnierites from the Falcondo Ni-laterite deposit (Dominican Republic) elucidated by means of μXAS

    NASA Astrophysics Data System (ADS)

    Roqué-Rosell, Josep; Villanova-de-Benavent, Cristina; Proenza, Joaquín A.

    2017-02-01

    Ni-bearing serpentines and garnierites (Ni-bearing Mg-phyllosilicates) are the main Ni ores in the Falcondo Ni-laterite deposit (Dominican Republic). In the present paper a set of garnierite samples and the associated Ni-bearing serpentines with characteristic mineral compositions and textures, from the saprolite horizon, were studied by EMPA, μXRF and μXAS. The ultimate goal is to elucidate, for the first time, the Fe speciation and the Ni local environment of saprolite ores from Ni-laterites of the Dominican Republic. The chemical composition of the minerals has been obtained by means of EMPA and the Ni, Fe and Cr elemental maps obtained by μXRF allowed distinguishing the saprolite fragments containing Ni-bearing serpentines and Fe oxyhydroxides from the garnierite veins. The Fe K-edge μXANES demonstrated that Fe in the Ni-poor primary serpentine is mostly in the Fe2+ form, whereas in the Ni-bearing serpentine constituting the bulk of the saprolite and in the Fe-bearing garnierite Type I Fe was in the form of Fe3+. In parallel, the local environment of Ni determined by means of Ni K-edge μEXAFS confirmed that in Ni-poor primary serpentines Ni formed a homogeneous Ni-Mg solid solution, in garnierites formed Ni-Ni clusters, and in Ni-bearing secondary serpentines Ni was found in Ni-Mg and Ni-Ni mixed sites. This paper explains the accumulation of Ni, the speciation of Fe in garnierites with various mineral compositions and in Ni-bearing serpentines from the saprolite horizon in Ni-laterite deposits.

  4. Selective oxidation of cube textured Ni and Ni-Cr substrate for the formation of cube textured NiO as a component buffer layer for REBa 2Cu 3O 7+ x (REBCO) coated conductors

    NASA Astrophysics Data System (ADS)

    Lockman, Z.; Goldacker, W.; Nast, R.; deBoer, B.; MacManus-Driscoll, J. L.

    2002-08-01

    Thermal oxidation of cube textured, pure Ni and Ni-Cr tapes was undertaken under different oxidation conditions to form cube textured NiO for the use as a first component of buffer layer for the coated conductor. Cube textured NiO was formed on pure Ni after oxidising for more than 130 min in O 2 at 1250 °C. The oxide thickness was >30 μm. Much shorter oxidation times (20-40 min, NiO thickness of ∼5 μm) and lower temperature (1050 °C) were required to form a similar texture on Ni-Cr foils. In addition, NiO formed on Ni-13%Cr was more highly textured than Ni-10%Cr. A Cr 2O 3 inner layer and NiO outer layer was formed on the Ni-Cr alloys.

  5. 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.

  6. 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.

  7. Thin NiTi Films Deposited on Graphene Substrates

    NASA Astrophysics Data System (ADS)

    Hahn, S.; Schulze, A.; Böhme, M.; Hahn, T.; Wagner, M. F.-X.

    2017-03-01

    We present experimental results on the deposition of Nickel Titanium (NiTi) films on graphene substrates using a PVD magnetron sputter process. Characterization of the 2-4 micron thick NiTi films by electron microscopy, electron backscatter diffraction, and transmission electron microscopy shows that grain size and orientation of the thin NiTi films strongly depend on the type of combination of graphene and copper layers below. Our experimental findings are supported by density functional theory calculations: a theoretical estimation of the binding energies of different NiTi-graphene interfaces is in line with the experimentally determined microstructural features of the functional NiTi top layer.

  8. 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.

  9. Properties of electroless Ni-W-P amorphous alloys

    SciTech Connect

    Zhang Bangwei |; Hu Wangyu; Zhang Qinglong; Qu Xuanyuan

    1996-08-01

    This paper describes work performed to determine some of the properties of the electroless Ni-W-P amorphous deposits. Phosphorus contents were varied up to 32 at.%, and the amorphous structure was found to be present at phosphorus contents above 5 at.%. Irrespective of P content, all the deposits exhibits excellent adhesion to metallic substrates. The addition of even small amounts of W provided greatly increased hardness compared with the plain Ni-P deposits. The wettability properties of the Ni-W-P deposits were found to be comparable to those of Ni-P and N-B-P deposits but inferior to those of Ni-B deposits.

  10. Anion promoted Ni-underpotential deposition on Au(111)

    NASA Astrophysics Data System (ADS)

    Bubendorff, J. L.; Cagnon, L.; Costa-Kieling, V.; Bucher, J. P.; Allongue, P.

    1997-07-01

    In situ scanning tunneling microscopy (STM) and cyclic voltammetry show that a Ni monolayer can be deposited from a sulfamate solution on Au(111) at positive potentials with respect to the Nernst potential of the {Ni}/{Ni2+} couple. This process is specific to H 2NSO -3 anions since it could not be observed in the presence of sulfates. High resolution STM images suggest that the Ni layer builds up on the surface due to a complexation of Ni 2+ by the sulfamate adlayer on the gold surface.

  11. Thin NiTi Films Deposited on Graphene Substrates

    NASA Astrophysics Data System (ADS)

    Hahn, S.; Schulze, A.; Böhme, M.; Hahn, T.; Wagner, M. F.-X.

    2016-12-01

    We present experimental results on the deposition of Nickel Titanium (NiTi) films on graphene substrates using a PVD magnetron sputter process. Characterization of the 2-4 micron thick NiTi films by electron microscopy, electron backscatter diffraction, and transmission electron microscopy shows that grain size and orientation of the thin NiTi films strongly depend on the type of combination of graphene and copper layers below. Our experimental findings are supported by density functional theory calculations: a theoretical estimation of the binding energies of different NiTi-graphene interfaces is in line with the experimentally determined microstructural features of the functional NiTi top layer.

  12. Properties of Highly Crystalline NiO and Ni Nanoparticles Prepared by High-temperature Oxidation and Reduction

    SciTech Connect

    Feygenson, M.; Kou, A.; Kreno, L.E.; Tiano, A.L.; Patete, J.M.; Zhang, F.; Kim, M.S.; Solovyov, V.; Wong, S.S.; Aronson, M.C.

    2010-01-26

    We describe here the use of high-temperature oxidation and reduction to produce highly crystalline nanoparticles of Ni and NiO. Starting with an amorphous Ni powder, we demonstrate that oxidation at 900 C produces faceted NiO nanocrystals with sizes ranging from 20 to 60 nm. High-resolution transmission electron microscopy measurements indicate near-perfect atomic order, truncated by (200) surfaces. Magnetization measurements reveal that the Neel temperature of these NiO nanoparticles is 480 K, substantially reduced by finite-size effects from the bulk value of 523 K. The magnetization of these faceted NiO nanoparticles does not saturate in fields as large as 14 T while a loop offset is observed which increases from 1000 Oe at 300 K to its maximum value of 3500 Oe at 50 K. We have used high-temperature reduction to transform the faceted NiO nanoparticles into highly ordered Ni nanoparticles, with a Curie temperature of 720 K and blocking temperatures in excess of 350 K. Subsequent efforts to reoxidize these Ni nanoparticles into the core-shell morphology found that the Ni nanoparticles are much more resistant to oxidation than the original Ni powder, perhaps due to the relative crystalline perfection of the former. At 800 C, an unusual surface roughening and subsequent instability was observed, where 50-nm-diameter NiO rods grow from the Ni surfaces. We have demonstrated that high-temperature oxidation and reduction in Ni and NiO are both reversible to some extent and are highly effective for creating the highly crystalline nanomaterials required for applications such as exchange-bias devices.

  13. Microstructure and properties of Cu-Ti-Ni alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Wang, Xian-hui; Guo, Ting-ting; Zou, Jun-tao; Yang, Xiao-hong

    2015-11-01

    The effects of Ni addition and aging treatments on the microstructure and properties of a Cu-3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu-3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu-3Ti-1Ni and Cu-3Ti-5Ni alloy was 300°C for 2 h and 450°C for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu-3Ti-1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu-3Ti-5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β'-Ni3Ti and β'-Cu4Ti precipitate from the Cu matrix during aging of the Cu-3Ti-5Ni alloy and that some residual NiTi phase remains. The increased electrical conductivity is ascribed to the formation of NiTi, β'-Ni3Ti, and β'-Cu4Ti phases.

  14. 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.

  15. Spectroscopic investigation of Ni speciation in hardened cement paste.

    PubMed

    Vespa, M; Dähn, R; Grolimund, D; Wieland, E; Scheidegger, A M

    2006-04-01

    Cement-based materials play an important role in multi-barrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. Cement is used to condition and stabilize the waste materials and to construct the engineered barrier systems (container, backfill, and liner materials) of repositories for radioactive waste. In this study, Ni uptake by hardened cement paste has been investigated with the aim of improving our understanding of the immobilization process of heavy metals in cement on the molecular level. X-ray absorption spectroscopy (XAS) coupled with diffuse reflectance spectroscopy (DRS) techniques were used to determine the local environment of Ni in cement systems. The Ni-doped samples were prepared at two different water/cement ratios (0.4, 1.3) and different hydration times (1 hour to 1 year) using a sulfate-resisting Portland cement. The metal loadings and the metal salts added to the system were varied (50 up to 5000 mg/kg; NO3(-), SO4(2-), Cl-). The XAS study showed that for all investigated systems Ni(ll) is predominantly immobilized in a layered double hydroxide (LDH) phase, which was corroborated by DRS measurements. Only a minor extent of Ni(ll) precipitates as Ni-hydroxides (alpha-Ni(OH)2 and beta-Ni(OH)2). This finding suggests that Ni-Al LDH, rather than Ni-hydroxides, is the solubility-limiting phase in the Ni-doped cement system.

  16. Synthesis and characterization of T[Ni(CN){sub 4}].2pyz with T=Fe, Ni; pyz=pyrazine: Formation of T-pyz-Ni bridges

    SciTech Connect

    Lemus-Santana, A.A.; Rodriguez-Hernandez, J.; Gonzalez, M.; Demeshko, S.; Avila, M.; Knobel, M.; Reguera, E.

    2011-08-15

    The formation of T-pyz-Ni bridges (pyz=pyrazine) in the T[Ni(CN){sub 4}].2pyz series is known for T=Mn, Zn, Cd and Co but not with T=Fe, Ni. In this contribution the existence of such bridges also for T=Fe, Ni is discussed. The obtained pillared solids, T[Ni(CN){sub 4}].2pyz, were characterized from XRD, TG, UV-Vis, IR, Raman, Moessbauer and magnetic data. Their crystal structures were refined in the orthorhombic Pmna space group from XRD powder patterns. The structural behavior of these solids on cooling down to 77 K was also studied. In the 180-200 K temperature range the occurrence of a structural transition to a monoclinic structure (P2{sub 1}/c space group) was observed. No temperature induced spin transition was observed for Fe[Ni(CN){sub 4}].2pyz. The iron (II) was found to be in high spin electronic state and this configuration is preserved on cooling down to 2 K. The magnetic data indicate the occurrence of a low temperature weak anti-ferromagnetic interaction between T metal centers within the T[Ni(CN){sub 4}] layer. In the paramagnetic region for Ni[Ni(CN){sub 4}].2pyz, a reversible temperature induced spin transition for the inner Ni atom was detected. - Graphical abstract: Rippled sheets structure for the pillared solids T[Ni(CN){sub 4}].2pyz. The pyrazine molecule is found forming T-pyz-Ni bridges between neighboring layers. Highlights: > Pillared 2D solids. > Inorganic-organic solids. > Assembling of molecular blocks. > From 1D and 2D building blocks to 3D solids.

  17. Crystal structure of Tb5Ni2In4 and Y5Ni2In4, and magnetic properties of Dy5Ni2In4

    NASA Astrophysics Data System (ADS)

    Provino, A.; Mudryk, Y.; Paudyal, D.; Smetana, V.; Manfrinetti, P.; Pecharsky, V. K.; Gschneidner, K. A.; Corbett, J. D.

    2012-04-01

    The crystal structure of the R5Ni2In4 intermetallic compounds was earlier reported for R = Ho, Er, Tm, and Lu (Lu5Ni2In4-type, oP22, Pbam); more recently the isostructural phases Dy5Ni2In4 and Sc5Ni2In4 have also been identified. Three inequivalent crystallographic sites are occupied by the R atoms in these compounds. We have synthesized and characterized Dy5Ni2In4 and the two new isotypic compounds Tb5Ni2In4 and Y5Ni2In4. So far, none of the physical properties have been reported on any of these phases; in this article we report on the physical properties of the Dy5Ni2In4 and the crystal structure of Tb5Ni2In4 and Y5Ni2In4 compounds. Measurements of the magnetic properties performed on Dy5Ni2In4 show a ferromagnetic-like ordering with a TC ≈105 K, followed by multiple magnetic orderings at lower temperatures. The fit of the inverse susceptibility in the paramagnetic state follows the Curie-Weiss law, where μeff. = 10.3 μB/Dy-atom (close to theoretical value of 10.64 μB for the free ion Dy3+) and a positive paramagnetic Curie temperature θp = 58 K. Ni atoms are most likely to be nonmagnetic. The heat capacity also shows three peaks: a large one at 103 K and two weaker at 12 and 8 K, respectively; the in-field heat capacity data corroborate these results, suggesting ferromagnetic and antiferromagnetic orderings at the temperature of 103 and 12 K, respectively. Low temperature x-ray diffraction has shown that the compound does not undergo any structural change down to 5 K.

  18. Metal-semiconductor interfacial reactions - Ni/Si system

    NASA Technical Reports Server (NTRS)

    Cheung, N. W.; Grunthaner, P. J.; Grunthaner, F. J.; Mayer, J. W.; Ullrich, B. M.

    1981-01-01

    X-ray photoelectron spectroscopy and channeling measurements with MeV He-4(+) ions have been used to probe the structure of the interface in the Ni/Si system. It is found that reactions occur where Ni is deposited on Si at 10 to the -10th torr: Si atoms are displaced from lattice sites, the Ni atoms are in an Si-rich environment, and the Ni/Si interface is graded in composition. Composition gradients are present at both interfaces in the Si/Ni2/Si/Ni system. For the Ni-Si system, cooling the substrate to 100 K slows down the reaction rate. The temperature dependence of the interfacial reactivity indicates the kinetic nature of metal-semiconductor interfaces.

  19. 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.

  20. Metal-semiconductor interfacial reactions - Ni/Si system

    NASA Technical Reports Server (NTRS)

    Cheung, N. W.; Grunthaner, P. J.; Grunthaner, F. J.; Mayer, J. W.; Ullrich, B. M.

    1981-01-01

    X-ray photoelectron spectroscopy and channeling measurements with MeV He-4(+) ions have been used to probe the structure of the interface in the Ni/Si system. It is found that reactions occur where Ni is deposited on Si at 10 to the -10th torr: Si atoms are displaced from lattice sites, the Ni atoms are in an Si-rich environment, and the Ni/Si interface is graded in composition. Composition gradients are present at both interfaces in the Si/Ni2/Si/Ni system. For the Ni-Si system, cooling the substrate to 100 K slows down the reaction rate. The temperature dependence of the interfacial reactivity indicates the kinetic nature of metal-semiconductor interfaces.

  1. The dissociation of H2 on the Ni(100) surface

    NASA Technical Reports Server (NTRS)

    Siegbahn, P. E. M.; Blomberg, M. R. A.; Bauschlicher, C. W., Jr.

    1984-01-01

    The dissociation of H2 on the (100) surface of Ni is investigated using a cluster model. The mechanism for dissocation of H2 directly above a Ni atom has little to no barrier and involves the Ni 3d electrons; elimination of the Ni 3d interaction with the H2 increases the barrier to more than 50 kcal/mol. The dissociation at the bridge site, treated without the Ni 3d interaction, leads to a barrier of about 30 kcal/mol, leading to the conclusion that the dissociation of H2 at any site on a Ni(100) surface requires strong 3d participation. The results are quantitatively different if the Ni 4p orbitals are not included. The effects of cluster size on the results are also discussed.

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

    SciTech Connect

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

    2016-07-15

    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: Gd{sub 5}Ni{sub 2}Sb (Mo{sub 5}SiB{sub 2}-type), Gd{sub 5}NiSb{sub 2} (Yb{sub 5}Sb{sub 3}-type), GdNiSb (MgAgAs-type), Gd{sub 3}Ni{sub 6}Sb{sub 5} (Y{sub 3}Ni{sub 6}Sb{sub 5}-type), and GdNi{sub 0.72}Sb{sub 2} (HfCuSi{sub 2}-type). At investigated temperature the Lu-Ni-Sb system is characterized by formation of the LuNiSb (MgAgAs-type), Lu{sub 5}Ni{sub 2}Sb (Mo{sub 5}SiB{sub 2}-type), and Lu{sub 5}Ni{sub 0.56}Sb{sub 2.44} (Yb{sub 5}Sb{sub 3}-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. - Graphical abstract: Crystal structure model and electron localization function of Lu{sub 5}Ni{sub 2}Sb. Display Omitted - Highlights: • Gd-Ni-Sb and Lu-Ni-Sb phase diagrams were constructed at 873 K. • GdNiSb and LuNiSb are characterized by disordered crystal structure. • Crystal structure optimization with DFT calculations confirmed crystal structure disorder in GdNiSb and LuNiSb.

  3. 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.

  4. Thermodynamic characterization of Ni3TeO6, Ni2Te3O8 and NiTe2O5

    NASA Astrophysics Data System (ADS)

    Dawar, Rimpi; Babu, R.; Ananthasivan, K.; Anthonysamy, S.

    2017-09-01

    Measurement of vapour pressure of TeO2(g) over the biphasic mixture Ni3TeO6 (s) + NiO(s) in the temperature range 1143-1272 K was carried out using transpiration-thermogravimetric technique (TTG). Gibbs energy of formation of Ni3TeO6 was obtained from the temperature dependence of vapour pressure of TeO2 (g) generated by the incongruent vapourisation reaction, Ni3TeO6 (s) → NiO(s) + TeO2 (g) + 1/2 O2 in the temperature range 1143-1272 K. An isoperibol type drop calorimeter was used to measure the enthalpy increments of Ni3TeO6, Ni2Te3O8 and NiTe2O5. Thermodynamic functions viz., heat capacity, entropy and Gibbs energy functions of these compounds were derived from the experimentally measured enthalpy increment values. Third-law analysis was carried out to ascertain absence of temperature dependent systematic errors in the measurement of vapour pressure of TeO2 (g). A value of -1265.1 ± 1.5 kJ mol-1 was obtained for ΔHf,298Ko (Ni3TeO6) using third-law analysis.

  5. Enthalpies of Formation of (Cu,Ni)3Sn, (Cu,Ni)6Sn5-HT and (Ni,Cu)3Sn2-HT.

    PubMed

    Schmetterer, C; Rodriguez-Hortala, M; Flandorfer, H

    Standard enthalpies of formation of ternary phases in the Cu-Ni-Sn system were determined along sections at 25, 41 and 45.5 at.% Sn applying tin solution drop calorimetry. Generally, the interaction of Ni with Sn is much stronger than that of Cu with Sn. Along all sections the enthalpy of formation changes almost linearly with the mutual substitution of Cu and Ni within the respective homogeneity ranges. Thus no additional ternary interaction promoting the formation of further Cu-Ni-Sn phases can be assumed. The results are discussed and compared with literature values relevant to this system.

  6. Two new [Ni(tren)2]2+ complexes: [Ni(tren)2]Cl2 and [Ni(tren)2]WS4.

    PubMed

    Ellermeier, Jan; Stähler, Ralph; Bensch, Wolfgang

    2002-02-01

    Both title compounds, bis[tris(2-aminoethyl)amine]nickel(II) dichloride, [Ni(tren)(2)]Cl(2), (I), and bis[tris(2-aminoethyl)amine]nickel(II) tetrathiotungstate, [Ni(tren)(2)]WS(4), (II), contain the [Ni(tren)(2)](2+) cation [tren is tris(2-aminoethyl)amine, C(6)H(18)N(4)]. The tren molecule acts as a tridentate ligand around the central Ni atom, with the remaining primary amine group not bound to the central atom. In (I), Ni(2+) is located on a centre of inversion surrounded by one crystallographically independent tren molecule. In the [Ni(tren)(2)](2+) cation of (II), the Ni atom is bound to two crystallographically independent tren molecules. The Ni atoms in the [Ni(tren)(2)](2+) complexes are in a distorted octahedral environment consisting of six N atoms from the chelating tren molecules. The counter-ions are chloride anions in (I) and the tetrahedral [WS(4)](2-) anion in (II). Hydrogen bonding is observed in both compounds.

  7. Structural evolution of NiAg heterogeneous alloys upon annealing

    NASA Astrophysics Data System (ADS)

    Proux, O.; Mimault, J.; Revenant-Brizard, C.; Regnard, J. R.; Mevel, B.

    1999-01-01

    NiAg heterogeneous alloys were studied by x-ray diffraction and x-ray absorption spectroscopy at the Ni K-edge using a total electron yield detection. In the as-deposited 0953-8984/11/1/013/img8 alloys of 0.10 and 0.15 Ni atomic fraction, most of the Ni atoms are in substitutional sites in the Ag matrix. At higher Ni concentration, the Ni atoms outside the Ag-rich phase become numerous enough to group together in small clusters. An important disorder in the neighbourhood of Ni atoms is demonstrated. At low annealing temperature (up to 0953-8984/11/1/013/img9C), in 0953-8984/11/1/013/img10 and 0953-8984/11/1/013/img11, some Ni atoms are still present in substitutional sites in the Ag matrix and the small Ni particles are under strain. A very short-range order exists in this state. After a 0953-8984/11/1/013/img9C annealing, the Ni particles grow, and the Ag-rich phase remains in a steady structural state. After a higher annealing (0953-8984/11/1/013/img13C), the local Ni atomic environment becomes well ordered and typical of the pure Ni FCC phase. The Ag-rich crystallites are impoverished in Ni atoms and grow with elimination of defects. Ni grains are generally smaller than 1 nm for as-deposited alloys and reach several nanometres after a 0953-8984/11/1/013/img13C annealing for 10 min.

  8. 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

  9. 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.

  10. 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.

  11. Epitaxial oxidation of Ni-V biaxially textured tapes

    NASA Astrophysics Data System (ADS)

    Petrisor, T.; Boffa, V.; Celentano, G.; Ciontea, L.; Fabbri, F.; Galluzzi, V.; Gambardella, U.; Mancini, A.; Rufoloni, A.; Varesi, E.

    2002-08-01

    The epitaxial oxidation of the (0 0 1)[1 0 0] textured Ni 100- xV x tapes was studied because of the practical interest of NiO as a first buffer layer for the YBCO based coated conductors. The study revealed that the oxidation of the Ni-V alloy is rather complex, the less noble V being internally oxidized, while Ni undergoes an external oxidation. Moreover, the formation of the NiVO 3 and of Ni 7V 5O 17 compounds have negative effects on the epitaxial oxidation and on the surface morphology, as well. The role of vanadium on the epitaxial oxidation of Ni-V alloy has not been fully understood yet. The optimum conditions for the epitaxial oxidation have been found to be: 700NiO films obtained under these conditions have a good out-of-plane and in-plane orientation, with a full-width-half-maximum of about 6.5° and 9.5°, respectively. The in-plane epitaxial relationship is [1 0 0]NiO∥[1 1 0]Ni-V. The as-obtained films have a compact and crack-free morphology, with grain sizes ranging from 30 to 300 nm. Nevertheless, the NiO films grown on (1 1 3) oriented grains or on twins are polycrystalline with a bright aspect, exhibiting a spongeous morphology. Epitaxial YBCO/CeO 2/NiO/Ni-V structures grown on the NiO template have a critical current density of about 0.6 MA/cm 2 at 77 K and zero magnetic field.

  12. 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.

  13. Preparation of Ni-YSZ Cermet through Reduction of NiO-YSZ Ceramic for SOFC Anode

    NASA Astrophysics Data System (ADS)

    Baity, P. S. N.; Budiana, B.; Suasmoro, S.

    2017-07-01

    Research on the synthesis of Nickel-Yttria Stabilized Zirconia (Ni-YSZ) cermet for Solid Oxide Fuel Cell (SOFC) anode has been performed. The preparation was carried out through the reduction process of the Nickel Oxide-Yttria stabilized Zirconia (NiO-YSZ) ceramic. NiO and YSZ were prepared separately, the NiO powder was prepared by calcination of CH4Ni3O7.xH2O at 500°C for 3 hours, while YSZ powder was prepared by calcination of 7mol% Y2O3 and 93mol% ZrO2 mixture at 1350°C for an hour. The NiO-YSZ ceramic preparation was carried outby mixing of YSZ and NiO powder with natural white starch by weight ratio NiO: YSZ: natural white starch = 4:6:1 followed by sintering at 1200°C for 4 hours. The completion of reduction process of NiO-YSZ ceramic was performed at 1000°C in flowing Argon (Ar) containing 10% Hydrogen (H2) up to 4 hours. The characterisations include thermogravimetric analysis (TGA), XRD, SEM-EDX and Impedance Analyzer meter. The synthesised Ni-YSZ cermet at composition 33wt% Ni and 67wt% YSZ, shows relative density 70% and electrical conductivity 10-2 S/cm at 700°C, it qualifies as anode for SOFC.

  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.

  15. Role of Ni-tolerant Bacillus spp. and Althea rosea L. in the phytoremediation of Ni-contaminated soils.

    PubMed

    Khan, Waheed Ullah; Yasin, Nasim Ahmad; Ahmad, Sajid Rashid; Ali, Aamir; Ahmed, Shakil; Ahmad, Aqeel

    2017-05-04

    In our current study, four nickel-tolerant (Ni-tolerant) bacterial species viz, Bacillus thuringiensis 002, Bacillus fortis 162, Bacillus subtilis 174, and Bacillus farraginis 354, were screened using Ni-contaminated media. The screened microbes exhibited positive results for synthesis of indole acetic acid (IAA), siderophore production, and phosphate solubilization. The effects of these screened microbes on Ni mobility in the soil, root elongation, plant biomass, and Ni uptake in Althea rosea plants grown in Ni-contaminated soil (200 mg Ni kg(-1)) were evaluated. Significantly higher value for water-extractable Ni (38 mg kg(-1)) was observed in case of Ni-amended soils inoculated with B. subtilis 174. Similarly, B. thuringiensis 002, B. fortis 162, and B. subtilis 174 significantly enhanced growth and Ni uptake in A. rosea. The Ni uptake in the shoots and roots of B. subtilis 174-inoculated plants enhanced up to 1.7 and 1.6-fold, respectively, as compared to that in the un-inoculated control. Bacterial inoculation also significantly improved the root and shoot biomass of treated plants. The current study presents a novel approach for bacteria-assisted phytoremediation of Ni-contaminated areas.

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

    DOE PAGES

    Liu, Bin; Yuan, Fenglin; Jin, Ke; ...

    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

  17. 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.

  18. Facile synthesis of self-supported Ni2P nanosheet@Ni sponge composite for high-rate battery

    NASA Astrophysics Data System (ADS)

    Shi, F.; Xie, D.; Zhong, Y.; Wang, D. H.; Xia, X. H.; Gu, C. D.; Wang, X. L.; Tu, J. P.

    2016-10-01

    To meet the requirements for high-rate battery with desirable performance, a self-supported Ni2P@Ni sponge electrode is synthesized via simple steps, in which the Ni sponge substrate is synthesized by a one-pot hydrothermal method and the Ni2P nanosheets grown on the novel substrate are converted from Ni(OH)2 via a phosphorization reaction. This hybrid composite combines the 3D porous structure of Ni sponge and high capacity of Ni2P nanosheets, which exhibits lightweight, flexible and highly-conductive properties, resulting in an excellent specific capacity of 430.3 mAh g-1 at a current density of 1 A g-1 and remaining as high as 77.0% capacity even at 40 A g-1. More importantly, the Ni2P@Ni sponge//C cell exhibits the maximum energy density of 182.1 W h kg-1 at a power density of 205 W kg-1 along with superior capacity retention of 85.2% after 3000 cycles. It is suggested that the Ni2P nanosheet@ Ni sponge composite is a promising electrode material for high-rate batteries.

  19. Microwave assisted synthesis and characterization of Ni/NiO nanoparticles as electrocatalyst for methanol oxidation in alkaline solution

    NASA Astrophysics Data System (ADS)

    Arunachalam, Prabhakarn; Ghanem, Mohamed A.; Al-Mayouf, Abdullah M.; Al-shalwi, Matar; Hamed Abd-Elkader, Omar

    2017-02-01

    Nickel/Nickel oxide (Ni/NiO) nanoparticles catalyst is prepared by microwave-assisted liquid-phase deposition using ethylene glycol (EG) and water mixture under atmospheric conditions. The physicochemical characterizations of the catalyst carried out by surface area analyzer, x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), electron microscopes measurements suggest the formation of crystalline nanoparticles structure of NiO. The surface area of Ni/NiO prepared using EG/water mixture reaches 70 m2 g-1 which is 2-fold enhsancement in surface area in comparison with NiO prepared in pure EG and an order of magnitude higher than that of bulk nickel prepared in pure water. The methanol electro-oxidation activity of the Ni/NiO nanoparticles obtained in EG/water mixture displayed more than 4-fold increase in oxidation current at 1.7 V versus RHE in comparison with NiO nanoparticles obtained in EG and 20-fold increase compared to bulk nickel catalyst concord with the enhancement of electro-active surface area. The results show the Ni/NiO nanoparticles produced by microwave assisted synthesis has superior activity for methanol oxidation in alkaline solution over the other nickel based catalysts and has potential for mass production.

  20. Magnetic-field-tuned charge density wave in SmNiC2 and NdNiC2

    NASA Astrophysics Data System (ADS)

    Lei, Hechang; Wang, Kefeng; Petrovic, C.

    2017-02-01

    We report magnetic field tuned competition between magnetic order and charge density wave (CDW) states in SmNiC2 and NdNiC2 polycrystals. The destruction of CDW can be observed not only in SmNiC2 below ferromagnetic (FM) but also in NdNiC2 below antiferromagnetic (AFM) transition temperature. Moreover, the CDW states near magnetic transition temperatures can be tuned by the magnetic field for both compounds. Magnetic-field induced FM state in NdNiC2 is more effective in weakening the CDW than the AFM state at temperatures near Neel temperature T N but both ordering states have the same effect on CDW below T N. The interplay between magnetic and CDW states in SmNiC2 and NdNiC2 may be different, suggesting that these materials are good models to study correlations between magnetic and CDW wave order.

  1. 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.

  2. Fe-Ni-bearing serpentines from the saprolite horizon of Caribbean Ni-laterite deposits: new insights from thermodynamic calculations

    NASA Astrophysics Data System (ADS)

    Villanova-de-Benavent, Cristina; Domènech, Cristina; Tauler, Esperança; Galí, Salvador; Tassara, Santiago; Proenza, Joaquín A.

    2016-10-01

    Fe-Ni-bearing serpentine from the saprolite horizon is the main Ni ores in hydrous silicate-type Ni laterites and formed by chemical weathering of partially serpentinized ultramafic rocks under tropical conditions. During lateritization, Mg, Si, and Ni are leached from the surface and transported downwards. Fe2+ is oxidized to Fe3+ and fixed as insoluble Fe-oxyhydroxides (mostly goethite) that incorporate Ni. This Ni is later leached from goethite and incorporated in secondary serpentine and garnierite. As a result, a serpentine-dominated saprolite horizon forms over the ultramafic protolith, overlapped by a Fe-oxyhydroxide-dominated limonite horizon. The serpentine from the protolith (serpentine I) is of hydrothermal origin and yields similar Ni (0.10-0.62 wt.% NiO) and lower Fe (mostly 1.37-5.81 wt.% FeO) concentrations than the primary olivine. In contrast, Fe-Ni-bearing serpentine from the saprolite (serpentine II) shows significantly higher and variable Fe and Ni contents, typically ranging from 2.23 to 15.59 wt.% Fe2O3 and from 1.30 to 7.67 wt.% NiO, suggesting that serpentine get enriched in Fe and Ni under supergene conditions. This study presents detailed mineralogical, textural, and chemical data on this serpentine II, as well as new insights by thermodynamic calculations assuming ideal solution between Fe-, Ni- and Mg-pure serpentines. The aim is to assess if at atmospheric pressure and temperature Fe-Ni-bearing serpentine can be formed by precipitation. Results indicate that the formation of serpentine II under atmospheric pressure and temperature is thermodynamically supported, and pH, Eh, and the equilibrium constant of the reaction are the parameters that affect the results more significantly.

  3. 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.

  4. Positron annihilation in solid and liquid Ni

    SciTech Connect

    Fluss, M.J.; Smedskjaer, L.C.; Chakraborty, B.; Chason, M.K.

    1982-03-01

    New techniques have been developed for the study of metals via positron annihilation which provide for the in-situ melting of the samples and subsequent measurements via Doppler broadening of positron-annihilation radiation. Here we report these metods currently in use at our laboratory; ion implantation of /sup 58/Co and the use of Al/sub 2/O/sub 3/ crucibles for in-situ melting followed by the decomposition of the Doppler-broadened spectrum into a parabolic and a Gaussian component. Our earliest results obtained for pure Ni in the polycrystalline solid and in the liquid state are compared. An interesting similarity is reported for the distributions of the high-momentum (Gaussian) component for positrons annihilating in vacancies at high temperatures and those annihilating in liquid Ni.

  5. 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.

  6. Gamow-Teller decays near 78Ni

    NASA Astrophysics Data System (ADS)

    Grzywacz, Robert; Alshudifat, Mohammad; Madurga, Miguel; Rykaczewski, Krzysztof; Gross, Carl

    2015-10-01

    Decays of neutron-rich nuclei close to 78Ni such as 82,83Zn and 82,83Ga produced in proton-induced fission of 238U were studied at the Holifield Radioactive Ion Beam Facility. New gamma-ray transitions were identified and level schemes, which include states at high excitation energies were constructed. The high energy levels were populated through allowed Gamow-Teller decays of the 78Ni components of the wave function, and were interpreted with new shell model calculations. This work is supported in part under US DOE Grants DE-AC05-00OR22725, DE-FG02-96ER40983, DE-AC05-06OR23100, and DE-FG05-88ER40407, DE-FG52-08NA28552; in part by the Polish Ministry of Science and Higher Education, Grant No. 2011/01/B/ST2/02476.

  7. 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.

  8. Incoherent Ag islands growth on Ni(100)

    NASA Astrophysics Data System (ADS)

    Marie, J. B.; Braems, I.; Bellec, A.; Chacon, C.; Creuze, J.; Girard, Y.; Gueddani, S.; Lagoute, J.; Repain, V.; Rousset, S.

    2017-02-01

    Growth of two-dimensional superstructure and island morphologies of silver atoms evaporated on a nickel (100) surface are studied by scanning tunneling microscopy. Near-equilibrium islands form at moderate annealing temperature (lower than 500 K) and present two kinds of morphologies. While they share a common monolayer c(2×8) superstructure, two distinct populations of islands coexist: rounded islands grown on the surface and spindle-shaped islands grown inside the Ni surface. The latter present a clear saturation of their density with increasing coverage. These shapes are mostly dominated by boundary energies as confirmed by a simple two-dimensional Wulff model whose parameters are derived using molecular statics simulations. Further annealing to 700 K leads to long Ag strips decorating the Ni step edges.

  9. Strengthening of NiAl Matrix Composites

    DTIC Science & Technology

    1991-10-01

    OISTRiBUTION/A VAI LABILITY OF REPORT E2i. OEC LASSIF ICAT iON/OOWNGRADING SCHEDULE FERFCRMING ORGANIZATION REPORT NUMBERIS) 5. MONITORING... ORGANIZATION REPORT NUMOERiS, I’ ML-1991-1 6. NIAME Of PERFORMING ORGANIZATION 0. OFFICE SYMBOL 74. NAME OF MONITORING ORGANIZATION 6 DORESS (C.I. State and Z...34.N AME~ OF-FUNDING/SPONSORING Go. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION~ NI..,M8ER ORGANIZATION III applicable) Office of Naval

  10. Characterisation of a Zn / Ni Plating Bath

    DTIC Science & Technology

    2009-09-03

    rate as effectively as its hydroxide11. This network of crack visible in the Zn/Ni corroded surface is probably due to internal stress caused by in...ions are transported to the cathode / electrolyte surface. At this point, the mass transfer limitations will restrict the current to the so-called...Millet, J.P., Mazille, H., Marchandise , D. and Cuntz, J.M., Surface and Coating Technology, 2000, 123, 164

  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.

  12. Breakdown of antiferromagnet order in polycrystalline NiFe/NiO bilayers probed with acoustic emission

    NASA Astrophysics Data System (ADS)

    Lebyodkin, M. A.; Lebedkina, T. A.; Shashkov, I. V.; Gornakov, V. S.

    2017-07-01

    Magnetization reversal of polycrystalline NiFe/NiO bilayers was investigated using magneto-optical indicator film imaging and acoustic emission techniques. Sporadic acoustic signals were detected in a constant magnetic field after the magnetization reversal. It is suggested that they are related to elastic waves excited by sharp shocks in the NiO layer with strong magnetostriction. Their probability depends on the history and number of repetitions of the field cycling, thus testifying the thermal-activation nature of the long-time relaxation of an antiferromagnetic order. These results provide evidence of spontaneous thermally activated switching of the antiferromagnetic order in NiO grains during magnetization reversal in ferromagnet/antiferromagnet (FM/AFM) heterostructures. The respective deformation modes are discussed in terms of the thermal fluctuation aftereffect in the Fulcomer and Charap model which predicts that irreversible breakdown of the original spin orientation can take place in some antiferromagnetic grains with disordered anisotropy axes during magnetization reversal of exchange-coupled FM/AFM structures. The spin reorientation in the saturated state may induce abrupt distortion of isolated metastable grains because of the NiO magnetostriction, leading to excitation of shock waves and formation of plate (or Lamb) waves.

  13. 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.

  14. Microstructure of the native oxide layer on Ni and Cr-doped Ni nanoparticles.

    PubMed

    Wang, Chong-Min; Baer, Donald R; Bruemmer, Stephen M; Engelhard, Mark H; Bowden, Mark E; Sundararajan, Jennifer A; Qiang, You

    2011-10-01

    Most metallic nanoparticles exposed to air at room temperature will be instantaneously oxidized and covered by an oxide layer. In most cases the true structural nature of the oxide layer formed at this stage is hard to determine. As shown previously for Fe and other nanoparticles, the nature of the oxides form on the particles can vary with particle size and nature of the oxidation process. In this paper, we report the morphology and structural features of the native oxide layer on 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 approximately 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.

  15. Spontaneous magnetization in Ni-Al and Ni-Fe layered double hydroxides.

    PubMed

    Coronado, Eugenio; Galán-Mascarós, José R; Martí-Gastaldo, Carlos; Ribera, Antonio; Palacios, Elías; Castro, Miguel; Burriel, Ramón

    2008-10-06

    Layered double hydroxides containing paramagnetic Ni (II) and diamagnetic/paramagnetic Al (III)/Fe (III) ions have been prepared and characterized. Ni 2Al(OH) 6(NO 3). nH 2O ( 1), Ni 2Fe(OH) 6(NO 3). nH 2O ( 2), Ni 2Fe(OH) 6(C 6H 8O 4) 0.5. nH 2O ( 3), and Ni 2Fe(OH) 6(C 10H 16O 4) 0.5. nH 2O ( 4) were prepared by coprecipitation at controlled pH as polycrystalline materials with the typical brucite-like structure, with alternating layers of hydroxide and the corresponding anions, which determine the interlayer separation. Magnetic studies show the appearance of spontaneous magnetization between 2 and 15 K for these compounds. Interestingly, the onset temperature for spontaneous magnetization follows a direct relationship with interlayer separation, since this is the only magnetic difference between compounds 2, 3, and 4. Magnetic and calorimetric data indicate that long-range magnetic ordering is not occurring in any of these materials, but rather a freezing of the magnetic system in 3D due to the magnetic disorder and competing intra- and interlayer interactions. Thus, these hydrotalcite-like magnetic materials can be regarded as spin glasses.

  16. Fundamental reflectivity and electronic structure of NiBr2 and NiCl2 insulators

    NASA Astrophysics Data System (ADS)

    Pollini, I.; Thomas, J.; Jezequel, G.; Lemonnier, J. C.; Mamy, R.

    1983-01-01

    The fundamental reflectivity of NiBr2 and NiCl2 has been measured over the energy range 2-11 eV from 300 to 30 K with the use of synchrotron radiation. The imaginary part of the dielectric constant ɛ2 has been determined at 30 K by means of the Kramers-Kronig technique. The structure in the complex optical spectra of nickel halides is interpreted in terms of charge-transfer transitions, orbital promotions, excitons, and direct allowed interband transitions at the symmetry points Γ, Z, and F, and along symmetry lines Λ, B, and Γ-L of the Brillouin zone. The energy gap is assigned to Γ-3-->Γ+1 transitions at the zone center, both in NiBr2 (7.90 eV) and NiCl2 (8.70 eV). Finally, the interpretation of the satellite exciton at 6.5 eV in NiBr2 (30 K) is discussed.

  17. 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.

  18. Effect of deposition technique of Ni on the perpendicular magnetic anisotropy in Co/Ni multilayers

    NASA Astrophysics Data System (ADS)

    Akbulut, S.; Akbulut, A.; Özdemir, M.; Yildiz, F.

    2015-09-01

    The perpendicular magnetic anisotropy (PMA) of Si/Pt 3.5/(Co 0.3/Ni 0.6)n /Co 0.3/ Pt 3 (all thicknesses are nm) multilayers were investigated for two different sample sets by using ferromagnetic resonance (FMR) and magnetooptic Kerr effect (MOKE) techniques. In the first sample set all layers (buffer, cap, Co and Ni) were grown by magnetron sputtering technique while in the second sample set Ni sub-layers were grown by molecular beam epitaxy (MBE) at high vacuum. Apart from deposition technique of Ni, all other parameters like thicknesses and growth rates of each layers are same for both sample sets. Multilayers in these two sample sets display PMA in the as grown state until a certain value of bilayer repetition (n) and the strength of PMA decreases with increasing n. Magnetic easy axis's of the multilayered samples switched from film normal to the film plane when n is 9 and 5 for the first and second sample sets, respectively. The reason for that, PMA was decreased due to increasing roughness with increasing n. This was confirmed by X Ray Reflectivity (XRR) measurements for both sample sets. Moreover, in the first sample set coercive field values are smaller than the second sample set, which means magnetic anisotropy is lower than the latter one. This stronger PMA is arising due to existence of stronger Pt (111) and Co/Ni (111) textures in the second sample set.

  19. Study of Ni/Fe nanotube properties

    NASA Astrophysics Data System (ADS)

    Kozlovskiy, A.; Zhanbotin, A.; Zdorovets, M.; Manakova, I.; Ozernoy, A.; Kadyrzhanov, K.; Rusakov, V.

    2015-12-01

    In this paper, we describe the synthesis, structure, and magnetic properties of Fe/Ni nanotubes fabricated in polyethylene-terephthalate (PET) ion-track membrane. Fe/Ni nanotubes were electrochemically deposited into PET membrane with cylindrical holes of diameter 111 ± 3 nm. Scanning electron microscopy, X-ray diffraction and Mössbauer analysis were used to determine the physical properties of the obtained nanostructures. It was found that the samples were single phase and had face-centered cubic structure with lattice parameter a = 2.866 ± 0.0008 Å. It was assumed that the observed phase was a solid solution of iron substitution in nickel. According to Mössbauer data, the hyperfine field amounts to 337.75 ± 0.4 kOe. Energy-dispersive X-ray spectroscopy data show a metal ratio in the nanotubes of around Ni20/Fe80. The magnetic domains have sizes close to the thickness of nanotube wall with their magnetization vector oriented at an angle of 37.9 ± 1.1° to the axis of the nanotubes.

  20. NiTi superelasticity via atomistic simulations

    NASA Astrophysics Data System (ADS)

    Chowdhury, Piyas; Ren, Guowu; Sehitoglu, Huseyin

    2015-12-01

    The NiTi shape memory alloys (SMAs) are promising candidates for the next-generation multifunctional materials. These materials are superelastic i.e. they can fully recover their original shape even after fairly large inelastic deformations once the mechanical forces are removed. The superelasticity reportedly stems from atomic scale crystal transformations. However, very few computer simulations have emerged, elucidating the transformation mechanisms at the discrete lattice level, which underlie the extraordinary strain recoverability. Here, we conduct breakthrough molecular dynamics modelling on the superelastic behaviour of the NiTi single crystals, and unravel the atomistic genesis thereof. The deformation recovery is clearly traced to the reversible transformation between austenite and martensite crystals through simulations. We examine the mechanistic origin of the tension-compression asymmetries and the effects of pressure/temperature/strain rate variation isolatedly. Hence, this work essentially brings a new dimension to probing the NiTi performance based on the mesoscale physics under more complicated thermo-mechanical loading scenarios.

  1. 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.

  2. Damping capacity of TiNi-based shape memory alloys

    NASA Astrophysics Data System (ADS)

    Rong, L. J.; Jiang, H. C.; Liu, S. W.; Zhao, X. Q.

    2007-07-01

    Damping capacity is another primary characteristic of shape memory alloys (SMA) besides shape memory effect and superelasticity. Damping behavior of Ti-riched TiNi SMA, porous TiNi SMA and a novel TiNi/AlSi composite have been investigated using dynamic mechanical analyzer (DMA) in this investigation. All these alloys are in martensitic state at room temperature and thus possess the high potential application value. Ti 50.2Ni 49.8 SMA has better damping capacity in pure martensitic state and phase transformation region due to the motion of martensite twin interface. As a kind of promising material for effective dampers and shock absorbing devices, porous TiNi SMA can exhibit higher damping capacity than the dense one due to the existence of the three-dimensioned connecting pore structure. It is found that the internal friction of porous TiNi SMA mainly originates from microplastic deformation and mobility of martensite interface and increases with the increase of the porosity. A novel TiNi/AlSi composite has been developed successfully by infiltrating AlSi alloy into the open pores of porous TiNi alloy with 60% porosity through compression casting. It shows the same phase transformation characteristics as the porous TiNi alloy. The damping capacity of the composite has been increased and the compressive strength has been also promoted remarkably. Suggestions for developing higher damping alloys based on TiNi shape memory alloy are proposed in this paper.

  3. 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).

  4. Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al3Ni2@Al nanoparticles as a high microwave absorption material

    NASA Astrophysics Data System (ADS)

    Pang, Yu; Xie, Xiubo; Li, Da; Chou, Wusheng; Liu, Tong

    2017-03-01

    The Al3Ni2@Al nanoparticles (NPs) were prepared from Ni45Al55 master alloy by hydrogen plasma-metal reaction method, and were subsequently dealloyed to produce porous Ni@NiO NPs of 36 nm. The pore size ranges from 0.7 to 1.6 nm, leading to large specific surface area of 69.5 m2/g and big pore volume of 0.507 cc/g. The saturation magnetization (MS) and coercivity (HC) of the microporous Ni@NiO NPs are 11.5 emu/g and 5.2 Oe. They exhibit high microwave absorption performance with a minimum reflection coefficient (RC) of -86.9 dB and an absorption bandwidth of 2.6 GHz (RC≤-10 dB) at thickness of 4.5 mm. The enhanced microwave absorption properties are attributed to the synergistic effect of the magnetic Ni core and dielectric NiO shell, and the micropore architecture. The NPs with micropore morphology and core/shell structure open a new way to modify the microwave absorption performance.

  5. Predictive Modeling of the Constitutive Response of Precipitation Hardened Ni-Rich NiTi

    NASA Astrophysics Data System (ADS)

    Cox, A.; Franco, B.; Wang, S.; Baxevanis, T.; Karaman, I.; Lagoudas, D. C.

    2017-03-01

    The effective thermomechanical response of precipitation hardened near-equiatomic Ni-rich NiTi alloys is predicted on the basis of composition and heat treatment using a microscale-informed model. The model takes into account the structural effects of the precipitates (precipitate volume fraction, elastic properties, elastic mismatch between the precipitates and the matrix, and coherency stresses due to the lattice mismatch between the precipitates and the matrix) on the reversible martensitic transformation under load as well as the chemical effects resulting from the Ni-depletion of the matrix during precipitate growth. The post-aging thermomechanical response is predicted based on finite element simulations on representative microstructures, using the response of the solutionized material and time-temperature-martensitic transformation temperature maps. The predictions are compared with experiments for materials of different initial compositions and heat treatments and reasonably good agreement is demonstrated for relatively low precipitate volume fractions.

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

    DOE PAGES

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; ...

    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

  7. Predictive Modeling of the Constitutive Response of Precipitation Hardened Ni-Rich NiTi

    NASA Astrophysics Data System (ADS)

    Cox, A.; Franco, B.; Wang, S.; Baxevanis, T.; Karaman, I.; Lagoudas, D. C.

    2017-01-01

    The effective thermomechanical response of precipitation hardened near-equiatomic Ni-rich NiTi alloys is predicted on the basis of composition and heat treatment using a microscale-informed model. The model takes into account the structural effects of the precipitates (precipitate volume fraction, elastic properties, elastic mismatch between the precipitates and the matrix, and coherency stresses due to the lattice mismatch between the precipitates and the matrix) on the reversible martensitic transformation under load as well as the chemical effects resulting from the Ni-depletion of the matrix during precipitate growth. The post-aging thermomechanical response is predicted based on finite element simulations on representative microstructures, using the response of the solutionized material and time-temperature-martensitic transformation temperature maps. The predictions are compared with experiments for materials of different initial compositions and heat treatments and reasonably good agreement is demonstrated for relatively low precipitate volume fractions.

  8. 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.

  9. Single crystal EPR study of the Ni center of NiFe hydrogenase

    NASA Astrophysics Data System (ADS)

    Geßner, Ch.; Trofanchuk, O.; Kawagoe, K.; Higuchi, Y.; Yasuoka, N.; Lubitz, W.

    1996-07-01

    EPR spectra of single crystals of NiFe hydrogenase from Desulfovibrio vulgaris Miyazaki F were evaluated and yielded the g-tensors of the Ni center for two different states of enzyme. The g-values associated with these states are identical to those measured in frozen solutions for the ready (NiB) and the unready (NiA) form of the Ni center. Directions of the g-tensor axes were determined relative to the crystal symmetry axes. The obtained changes of g-values and tensor axes orientations between NiA and NiB can be explained by a structural difference involving modification of a cysteine sulfur ligand.

  10. 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.

  11. Magnetic Excitations in the Stacked Quantum Magnets NaNiO2 and LiNiO2

    NASA Astrophysics Data System (ADS)

    Clancy, J. P.; Gaulin, B. D.; Ruff, J. P. C.; Ross, K. A.; van Gastel, G. J.; Abernathy, D. L.; Stone, M. B.

    2009-03-01

    NaNiO2 and LiNiO2 are isostructural stacked triangular lattice quantum magnets, in which magnetism is conventionally thought to arise due to spin 1/2 moments carried by Ni^3+ ions. Surprisingly, while NaNiO2 undergoes a cooperative Jahn-Teller transition at 480K and magnetically orders below TN ˜ 23K, LiNiO2 undergoes a glass transition at Tg ˜ 9K and remains disordered down to the lowest measured temperatures. The absence of long-range magnetic order in LiNiO2 has been attributed to either geometric frustration caused by mixing of the Li and Ni sublattices, or orbital degeneracy due to the absence of a coherent Jahn-Teller distortion. We have performed time of flight neutron scattering measurements on polycrystalline samples of NaNiO2 and LiNiO2 using the wide Angular-Range Chopper Spectrometer (ARCS) at the SNS. Our measurements reveal previously unobserved magnetic excitations at relatively high energy transfers, which we associate with ferromagnetic spin waves mediated by in-plane interactions. We also find evidence of critical scattering in NaNiO2 near the magnetic phase transition at TN. These results will be compared with previous measurements collected using the DCS at NIST.

  12. 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.

  13. Ni-based composite microstructures fabricated by femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles

    NASA Astrophysics Data System (ADS)

    Tamura, Kenki; Mizoshiri, Mizue; Sakurai, Junpei; Hata, Seiichi

    2017-06-01

    Ni-based composite micropatterns were fabricated by the femtosecond laser reductive sintering of NiO/Cr mixed nanoparticles. A NiO/Cr mixed nanoparticle solution including ethylene glycol and polyvinylpyrrolidone was irradiated with focused femtosecond laser pulses. The X-ray diffraction spectra of the fabricated micropatterns indicated that NiO nanoparticles were well reduced under atmospheric conditions in the laser scanning speed range of 5-15 mm/s. In contrast, micropatterns including NiO were formed at a laser scanning speed of 1 mm/s, indicating that the reduced Ni was reoxidized by overheating. These results were supported by those of energy-dispersive X-ray spectrometry analysis and the electrical resistivity of the micropatterns. The compositions such as Ni, NiO, Cr2O3, and Ni-Cr in the fabricated micropatterns depended on laser scanning speed. The selective fabrication of a ferromagnetic free microgear from the substrate and an axis fixed on the substrate was demonstrated by controlling the laser scanning speed. The fabrication process for Ni-based composite microstructures is useful for the fabrication of ferromagnetic microdevices.

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

    NASA Astrophysics Data System (ADS)

    Li, Wei; Liu, Ping; Zhang, Ke; Ma, Fengcang; Liu, Xinkuan; Chen, Xiaohong; He, Daihua

    2014-08-01

    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.

  15. 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

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

    PubMed

    Li, Wei; Liu, Ping; Zhang, Ke; Ma, Fengcang; Liu, Xinkuan; Chen, Xiaohong; He, Daihua

    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.

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

    PubMed

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

    2014-06-07

    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.

  18. 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.

  19. 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.

  20. 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.

  1. Electronic, magnetic and Fermi properties investigates on quaternary Heusler NiCoCrAl, NiCoCrGa and NiFeCrGa

    NASA Astrophysics Data System (ADS)

    Wei, Xiao-Ping; Zhang, Ya-Ling; Chu, Yan-Dong; Sun, Xiao-Wei; Sun, Ting; Guo, Peng; Deng, Jian-Bo

    2015-07-01

    Using the full-potential local-orbital minimum-basis method within the framework of density functional theory, we study the electronic, magnetic and Fermi properties of three quaternary Heusler compounds: NiCoCrAl, NiCoCrGa and NiFeCrGa. Results identify that these compounds are half-metallic ferromagnets with integer spin magnetic moment, and their spin moments follow the Slater-Pauling rule. Accordingly, the origin of gap and magnetic moment are also discussed. In addition, the Fermi surface is further plotted to explore the behavior of electronic states in the vicinity of Fermi level for these compounds. Finally, we argue the influence of tetragonal deformation on electronic and magnetic properties. Meanwhile, the possible L21 disorder is also discussed for NiCoCrAl and NiCoCrGa.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  4. Atomistic Modeling of Pd Site Preference in NiTi

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Mosca, Hugo O.

    2004-01-01

    An analysis of the site subsitution behavior of Pd in NiTi was performed using the BFS method for alloys. Through a combination of Monte Carlo simulations and detailed atom-by-atom energetic analyses of various computational cells, representing compositions of NiTi with up to 10 at% Pd, a detailed understanding of site occupancy of Pd in NiTi was revealed. Pd subsituted at the expense of Ni in a NiTi alloy will prefer the Ni-sites. Pd subsituted at the expense of Ti shows a very weak preference for Ti-sites that diminishes as the amount of Pd in the alloy increases and as the temperature increases.

  5. Elemental Mapping of NiTi with EFTEM

    SciTech Connect

    Wittig, J. E.; Bentley, James; Evans, Neal D; Somsen, Ch.; Eggeler, G.

    2005-01-01

    Martensitic transformations in Ni-rich NiTi shape memory alloys take place as multistage transformations. In Ni-rich alloys with an austenitic B2 matrix, coherent Ni{sub 4}Ti{sub 3} precipitates form from thermo-mechanical processing and affect the sequence of the martensitic transformation. Any composition inhomogenieties that develop during the evolution of the Ni{sub 4}Ti{sub 3} precipitates will have a large influence on the multistage martensitic transformations, since the martensite start temperature, M{sub s}, is strongly dependent on the Ni concentration of the matrix. Since concentration differences on the order of 0.5 at% are sufficient to influence the transformation, providing sufficiently accurate concentration profiles for meaningful structure-property correlations is a challenging experiment. This investigation employs elemental mapping by energy-filtered transmission electron microscopy (EFTEM) to attempt to measure the concentration profiles at these precipitate-matrix interfaces.

  6. Selective interaction of Ni with an MHC-bound peptide.

    PubMed Central

    Romagnoli, P; Labhardt, A M; Sinigaglia, F

    1991-01-01

    T cells generally recognize foreign antigens as peptides associated with self-molecules encoded by genes of the major histocompatibility complex (MHC). However, T cells which are specific for non-peptidic haptens have been described, in particular in patients with contact sensitivity reactions to metals such as nickel (Ni). Previously, we isolated MHC class II-restricted Ni-specific T cell clones from patients with Ni allergy. The experiments reported here examine the molecular basis for the interaction between Ni and peptide-MHC complexes. We find that Ni alters a T cell response to a peptide and show that Ni interacts with this peptide to alter its antigenicity rather than its ability to bind to MHC molecules. These findings hold implications for a model of hapten recognition by T cells. PMID:2026136

  7. Preparation of high-permeability NiCuZn ferrite.

    PubMed

    Hu, Jun; Yan, Mi

    2005-06-01

    Appropriate addition of CuO/V2O5 and the reduction of the granularity of the raw materials particle decrease the sintering temperature of NiZn ferrite from 1200 degrees C to 930 degrees C. Furthermore, the magnetic properties of the NiZn ferrite prepared at low temperature of 930 degrees C is superior to that of the NiZn ferrite prepared by sintering at high temperature of 1200 degrees C because the microstructure of the NiZn ferrite sintered at 930 degrees C is more uniform and compact than that of the NiZn ferrite sintered at 1200 degrees C. The high permeability of 1700 and relative loss coefficient tandelta/mu(i) of 9.0x10(-6) at 100 kHz was achieved in the (Ni0.17Zn0.63Cu0.20)Fe1.915O4 ferrite.

  8. Effect of Polyethylene Glycol on the NiO Photocathode

    NASA Astrophysics Data System (ADS)

    Li, Shengjun; Chen, Zeng; Kong, Wenping; Jia, Xiyang; Cai, Junhao; Dong, Shaokang

    2017-08-01

    In this study, a uniform nanoporous NiO film, with a thickness of up to 2.6 μm, was prepared using polyethylene glycol (PEG). The addition of PEG significantly decreased the cracks in the NiO film and prevented the peeling of the NiO film from a fluorine-doped tin oxide substrate. The NiO cathode was prepared using CdSeS quantum dots (QDs) as the sensitizer, with an optimized photoelectric conversion of 0.80%. The optimized QD-sensitized NiO films were first assembled with the TiO2 anode to prepared QD-sensitized p-n-type tandem solar cells. The open circuit voltage was greater than that obtained using the separated NiO cathode or TiO2 anode.

  9. 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.

  10. Effect of Polyethylene Glycol on the NiO Photocathode.

    PubMed

    Li, Shengjun; Chen, Zeng; Kong, Wenping; Jia, Xiyang; Cai, Junhao; Dong, Shaokang

    2017-08-17

    In this study, a uniform nanoporous NiO film, with a thickness of up to 2.6 μm, was prepared using polyethylene glycol (PEG). The addition of PEG significantly decreased the cracks in the NiO film and prevented the peeling of the NiO film from a fluorine-doped tin oxide substrate. The NiO cathode was prepared using CdSeS quantum dots (QDs) as the sensitizer, with an optimized photoelectric conversion of 0.80%. The optimized QD-sensitized NiO films were first assembled with the TiO2 anode to prepared QD-sensitized p-n-type tandem solar cells. The open circuit voltage was greater than that obtained using the separated NiO cathode or TiO2 anode.

  11. Body-centered-cubic Ni and its magnetic properties.

    PubMed

    Tian, C S; Qian, D; Wu, D; He, R H; Wu, Y Z; Tang, W X; Yin, L F; Shi, Y S; Dong, G S; Jin, X F; Jiang, X M; Liu, F Q; Qian, H J; Sun, K; Wang, L M; Rossi, G; Qiu, Z Q; Shi, J

    2005-04-08

    The body-centered-cubic (bcc) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bcc Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52+/-0.08 micro(B)/atom. The cubic magnetocrystalline anisotropy of bcc Ni is determined to be +4.0x10(5) ergs x cm(-3), as opposed to -5.7x10(4) ergs x cm(-3) for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bcc Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation.

  12. 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.

  13. Microstructures in rapidly solidified Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Jayaraman, N.; Tewari, S. N.; Hemker, K. J.; Glasgow, T. K.

    1985-01-01

    Ni-Mo alloys of compositions ranging from pure Ni to Ni-40 at % Mo were rapidly solidified by Chill Block Melt Spinning in vacuum and were examined by optical metallography, X-ray diffraction and transmission electron microscopy. Rapid solidification resulted in an extension of molybdenum solubility in nickel from 28 to 37.5 at %. A number of different phases and microstructures were seen at different depths (solidification conditions) from the quenched surface of the melt spun ribbons.

  14. Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes

    SciTech Connect

    Qiao, Ruimin; Wray, L. Andrew; Kim, Jung -Hyun; Pieczonka, Nicholas P. W.; Harris, Stephen J.; Yang, Wanli

    2015-11-11

    The LiNi0.5Mn1.5O4 spinel is an appealing cathode material for next generation rechargeable Li-ion batteries due to its high operating voltage of ~4.7 V (vs Li/Li+). Although it is widely believed that the full range of electrochemical cycling involves the redox of Ni(II)/(IV), it has not been experimentally clarified whether Ni(III) exists as the intermediate state or a double-electron transfer takes place. Here, combined with theoretical calculations, we show unambiguous spectroscopic evidence of the Ni(III) state when the LiNi0.5Mn1.5O4 electrode is half charged. This provides a direct verification of single-electron-transfer reactions in LiNi0.5Mn1.5O4 upon cycling, namely, from Ni(II) to Ni(III), then to Ni(IV). Additionally, by virtue of its surface sensitivity, soft X-ray absorption spectroscopy also reveals the electrochemically inactive Ni2+ and Mn2+ phases on the electrode surface. Our work provides the long-awaited clarification of the single-electron transfer mechanism in LiNi0.5Mn1.5O4 electrodes. Furthermore, the experimental results serve as a benchmark for further spectroscopic characterizations of Ni-based battery electrodes.

  15. 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.

  16. 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.

  17. Crystallization Behaviour of Amorphous Al-Ni-Nd Alloy

    SciTech Connect

    Goegebakan, Musa; Guendes, Alaaddin

    2007-04-23

    In this study, crystallization behaviour of rapidly solidified Al85Ni5Nd10 alloy has been investigated by differential scanning calorimetry (DSC). Continuous heating DSC trace of amorphous Al85Ni5Nd10 alloy consisted of three exothermic peaks. This indicated that; crystallization of amorphous Al85Ni5Nd10 alloy during continous heating takes places in three stages. Before the first exothermic peak, a glass transition temperature was observed.

  18. 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

  19. Microstructures in rapidly solidified Ni-Mo alloys

    NASA Technical Reports Server (NTRS)

    Jayaraman, N.; Tewari, S. N.; Hemker, K. J.; Glasgow, T. K.

    1986-01-01

    Ni-Mo alloys of compositions ranging from pure Ni to Ni-40 at. percent Mo were rapidly solidified by Chill Block Melt Spinning in vacuum and were examined by optical metallography, X-ray diffraction and transmission electron microscopy. Rapid solidification resulted in an extension of molybdenum solubility in nickel from 28 to 37.5 at. percent. A number of different phases and microstructures were seen at different depths (solidification conditions) from the quenched surface of the melt spun ribbons.

  20. Prompt proton decay and deformed bands in Ni56

    NASA Astrophysics Data System (ADS)

    Johansson, E. K.; Rudolph, D.; Andersson, L.-L.; Torres, D. A.; Ragnarsson, I.; Andreoiu, C.; Baktash, C.; Carpenter, M. P.; Charity, R. J.; Chiara, C. J.; Ekman, J.; Fahlander, C.; Hoel, C.; Pechenaya, O. L.; Reviol, W.; Du Rietz, R.; Sarantites, D. G.; Seweryniak, D.; Sobotka, L. G.; Yu, C. H.; Zhu, S.

    2008-06-01

    High-spin states in the doubly magic N=Z nucleus Ni56 have been investigated with three fusion-evaporation reaction experiments. New γ-ray transitions are added, and a confirmation of a previously suggested prompt proton decay from a rotational band in Ni56 into the ground state of Co55 is presented. The rotational bands in Ni56 are discussed within the framework of cranked Nilsson-Strutinsky calculations.

  1. Enhanced noble gas adsorption in Ag@MOF-74Ni.

    PubMed

    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) by 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. Comparison of three Ni-Hard I alloys

    SciTech Connect

    Dogan, Omer N.; Hawk, Jeffrey A.; Rice, J.

    2004-09-01

    This report documents the results of an investigation which was undertaken to reveal the similarities and differences in the mechanical properties and microstructural characteristics of three Ni-Hard I alloys. One alloy (B1) is ASTM A532 class IA Ni-Hard containing 4.2 wt. pct. Ni. The second alloy (B2) is similar to B1 but higher in Cr, Si, and Mo. The third alloy (T1) also falls in the same ASTM specification, but it contains 3.3 wt. pct. Ni. The alloys were evaluated in both as-cast and stress-relieved conditions except for B2, which was evaluated in the stress-relieved condition only. While the matrix of the high Ni alloys is composed of austenite and martensite in both conditions, the matrix of the low Ni alloy consists of a considerable amount of bainite, in addition to the martensite and the retained austenite in as cast condition, and primarily bainite, with some retained austenite, in the stress relieved condition. It was found that the stress relieving treatment does not change the tensile strength of the high Ni alloy. Both the as cast and stress relieved high Ni alloys had a tensile strength of about 350 MPa. On the other hand, the tensile strength of the low Ni alloy increased from 340 MPa to 452 MPa with the stress relieving treatment. There was no significant difference in the wear resistance of these alloys in both as-cast and stressrelieved conditions.

  3. PH-Sensitive Ni(CH)2-Based microelectrochemical transistors

    NASA Astrophysics Data System (ADS)

    Natan, Michael J.; Belanger, D.; Carpenter, M. K.; Wrighton, Mark S.

    1986-11-01

    Properties of arrays of closely spaced (1.2 micron) Au or Pt microelectrodes (approx. 2 micron wide x 50 micron long x 0.1 micron high) coated with cathodically grown films of Ni(OH)2 are reported. Electrical connection of microelectrodes by Ni(OH)2 was verified by cyclic voltammetry. The ratio of anodic charge to cathodic charge in cyclic voltammograms for the Ni(OH)2 = NiO(OH) interconversion exceeds one. However, it is shown that excess charge in the anodic cyclic voltammetric wave for oxidation of Ni(OH)2 does not affect the conductivity of Ni(OH)2 films. The steady state resistance of Ni(OH)2 connecting two microelectrodes has been measured as a function of potential from 0 V to 0.7 V vs. SCE, and was typically found to vary from approx. 10 to the minus 7th power to approx. 0.0001 ohms. The measured resistance corresponds to a resistivity of approximately 30 ohm-cm in the oxidized state. The decrease in resistance is caused by electrochemical oxidation of insulating Ni (OH)2 to conducting NiO (OH). At fixed drain voltage, VD, the gate current, IG, and the drain current, ID, can be measured simultaneously as the gate voltage, VG, is varied at a given frequency.

  4. Biocompatilibity-related surface characteristics of oxidized NiTi.

    PubMed

    Danilov, Anatoli; Tuukkanen, Tuomas; Tuukkanen, Juha; Jämsä, Timo

    2007-09-15

    In the present study, we examined the effect of NiTi oxidation on material surface characteristics related to biocompatibility. Correspondence between electron work function (EWF) and adhesive force predicted by electron theory of adsorption as well as the effect of surface mechanical stress on the adhesive force were studied on the nonoxidized and oxidized at 350, 450, and 600 degrees C NiTi alloy for medical application. The adhesive force generated by the material surface towards the drops of alpha-minimal essential medium (alpha-MEM) was used as a characteristic of NiTi adsorption properties. The study showed that variations in EWF and mechanical stress caused by surface treatment were accompanied by variations in adhesive force. NiTi oxidation at all temperatures used gave rise to decrease in adhesive force and surface stress values in comparison to the nonoxidized state. In contrary, the EWF value revealed increase under the same condition. Variations in surface oxide layer thickness and its phase composition were also followed. The important role of oxide crystallite size in EWF values within the range of crystallite dimensions typical for NiTi surface oxide as an instrument for the fine regulation of NiTi adsorption properties was demonstrated. The comparative oxidation of pure titanium and NiTi showed that the effect of Ni on the EWF value of NiTi surface oxide is negligible.

  5. Cation distribution and mixing thermodynamics in Fe/Ni thiospinels

    NASA Astrophysics Data System (ADS)

    Haider, Saima; Grau-Crespo, Ricardo; Devey, Antony J.; de Leeuw, Nora H.

    2012-07-01

    The structural analogy between Ni-doped greigite minerals (Fe3S4) and the (Fe, Ni)S clusters present in biological enzymes has led to suggestions that these minerals could have acted as catalysts for the origin of life. However, little is known about the distribution and stability of Ni dopants in the greigite structure. We present here a theoretical investigation of mixed thiospinels (Fe1-xNix)3S4, using a combination of density functional theory (DFT) calculations and Monte Carlo simulations. We find that the equilibrium distribution of the cations deviates significantly from a random distribution: at low Ni concentrations, Ni dopants are preferably located in octahedral sites, while at higher Ni concentrations the tetrahedral sites become much more favourable. The thermodynamic mixing behaviour between greigite and polydymite (Ni3S4) is dominated by the stability field of violarite (FeNi2S4), for which the mixing enthalpy exhibits a deep negative minimum. The analysis of the free energy of mixing shows that Ni doping of greigite is very unstable with respect to the formation of a separate violarite phase. The calculated variation of the cubic cell parameter with composition is found to be non-linear, exhibiting significant deviation from Vegard’s law, but in agreement with experiment.

  6. Ni cycling in mangrove sediments from New Caledonia

    NASA Astrophysics Data System (ADS)

    Noël, Vincent; Morin, Guillaume; Juillot, Farid; Marchand, Cyril; Brest, Jessica; Bargar, John R.; Muñoz, Manuel; Marakovic, Grégory; Ardo, Sandy; Brown, Gordon E.

    2015-11-01

    Covering more than 70% of tropical and subtropical coastlines, mangrove intertidal forests are well known to accumulate potentially toxic trace metals in their sediments, and thus are generally considered to play a protective role in marine and lagoon ecosystems. However, the chemical forms of these trace metals in mangrove sediments are still not well known, even though their molecular-level speciation controls their long-term behavior. Here we report the vertical and lateral changes in the chemical forms of nickel, which accumulates massively in mangrove sediments downstream from lateritized ultramafic deposits from New Caledonia, where one of nature's largest accumulations of nickel occurs. To accomplish this we used Ni K-edge Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy data in combination with microscale chemical analyses using Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM-EDXS). After Principal Component and Target Transform analyses (PCA-TT), the EXAFS data of the mangrove sediments were reliably least-squares fitted by linear combination of 3-components chosen from a large model compound spectral database including synthetic and natural Ni-bearing sulfides, clay minerals, oxyhydroxides, and organic complexes. Our results show that in the inland salt flat Ni is hosted in minerals inherited from the eroded lateritic materials, i.e. Ni-poor serpentine (44-58%), Ni-rich talc (20-31%), and Ni-goethite (18-24%). In contrast, in the hydromorphic sediments beneath the vegetated Avicennia and Rhizophora stands, a large fraction of Ni is partly redistributed into a neoformed smectite pool (20-69% of Ni-montmorillonite), and Ni speciation significantly changes with depth in the sediment. Indeed, Ni-rich talc (25-56%) and Ni-goethite (15-23%) disappear below ∼15 cm depth in the sediment and are replaced by Ni-sorbed pyrite (23-52%) in redox-active intermediate depth layers and by pyrite (34-55%) in the deepest

  7. The role of boron in ductilizing Ni3Al

    NASA Technical Reports Server (NTRS)

    Vedula, K.; Shabel, B. S.; Khadkikar, P. S.

    1987-01-01

    Ductilization of Ni3Al at room temperature by microalloying with boron has been primarily attributed to the increased grain boundary cohesion in the presence of boron. However, another aspect of the role played by boron in ductilizing Ni3Al is revealed when the Hall-Petch relationships for Ni3Al and B-doped Ni3Al are compared. A shallower slope for the B-doped Ni3Al compared to that for Ni3Al indicates a reduced resistance to slip propagation across grain boundaries, and therefore reduced stress concentration at boundaries, in the presence of boron. This comparison of Hall-Petch relationships was carried out by generating data for powder processed B-doped Ni3Al at various grain sizes and by compiling data for Ni3Al from the literature. In addition, the room temperature fracture of B-doped Ni3Al has been shown to initiate along certain grain boundaries. The fracture eventually occurs by transgranular ductile tearing.

  8. An investigation of the oxidized Ni/InAs interface

    NASA Astrophysics Data System (ADS)

    Venter, A.; Botha, J. R.; Swart, H. C.; Naidoo, S.; Olivier, E. J.

    2009-12-01

    Ni was resistively deposited onto bulk InAs and subsequently oxidized in an O 2 atmosphere. The anneal temperature and time were 450 °C and 2.5 h, respectively. X-ray diffraction of the oxidized Ni/InAs sample revealed the formation of In 3Ni 2 and In 2O 3 on the front suggesting inter diffusion of In, Ni and O. NiO was not detected by X-ray diffraction. In a preliminary study, using glass as a substrate, NiO readily formed when using these oxidation parameters. Conductivity measurements of the oxidized Ni/InAs surface revealed a conducting front and insulating rear surface while TEM of the Ni/InAs interface revealed an intermediate amorphous diffusion zone between the “oxidized” Ni layer and the bulk InAs. A closer investigation of the intermediate layer supports the X-ray diffraction results, suggesting compound formation due to diffusion of oxygen and nickel into the substrate, and out-diffusion of In and As from the bulk of the sample. AES was used to further elucidate these results.

  9. NiO nanoparticle-based urea biosensor.

    PubMed

    Tyagi, Manisha; Tomar, Monika; Gupta, Vinay

    2013-03-15

    NiO nanoparticles (NiO-NPs) have been exploited successfully for the fabrication of a urea biosensor. A thin film of NiO nanoparticles deposited on an indium tin oxide (ITO) coated glass substrate serves as an efficient matrix for the immobilisation of urease (Ur), the specific enzyme for urea detection. The prepared bioelectrode (Ur/NiO-NP/ITO/glass) is utilised for urea sensing using cyclic voltammetry and UV-visible spectroscopy. NiO nanoparticles act as electro-catalytic species that are based on the shuttling of electrons between Ni(2+) and Ni(3+) in the octahedral site and result in an enhanced electrochemical current response. The prepared bioelectrode (Ur/NiO-NPs/ITO/glass) exhibits a high sensitivity of 21.3 μA/(mM (*) cm(2)) and a good linearity in a wide range (0.83-16.65 Mm) of urea concentrations with fast response time of 5s. The low value of the Michaelis-Menten constant (K(m)=0.34 mM) indicates the high affinity of Ur towards the analyte (urea). The high catalytic activity, along with the redox behaviour of NiO-NPs, makes it an efficient matrix for the realisation of a urea biosensor.

  10. 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.

  11. 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.

  12. Safflorite, (Co,Ni,Fe)As2, isomorphous with marcasite

    PubMed Central

    Yang, Hexiong; Downs, Robert T.; Eichler, Carla

    2008-01-01

    Safflorite, a naturally occurring cobalt-nickel-iron diarsenide (Co,Ni,Fe)As2, possesses the marcasite-type structure, with cations (M = Co + Ni + Fe) at site symmetry 2/m and As anions at m. The MAs6 octa­hedra share two edges, forming chains parallel to c. The chemical formula for safflorite should be expressed as (Co,Ni,Fe)As2, rather than the end-member format CoAs2, as its structure stabilization requires the simultaneous inter­action of the electronic states of Co, Ni, and Fe with As2 2− dianions. PMID:21201568

  13. Low-temperature CO oxidation on Ni(111) and on a Au/Ni(111) surface alloy.

    PubMed

    Knudsen, Jan; Merte, Lindsay R; Peng, Guowen; Vang, Ronnie T; Resta, Andrea; Laegsgaard, Erik; Andersen, Jesper N; Mavrikakis, Manos; Besenbacher, Flemming

    2010-08-24

    From an interplay between scanning tunneling microscopy, temperature programmed desorption, X-ray photoelectron spectroscopy, and density functional theory calculations we have studied low-temperature CO oxidation on Au/Ni(111) surface alloys and on Ni(111). We show that an oxide is formed on both the Ni(111) and the Au/Ni(111) surfaces when oxygen is dosed at 100 K, and that CO can be oxidized at 100 K on both of these surfaces in the presence of weakly bound oxygen. We suggest that low-temperature CO oxidation can be rationalized by CO oxidation on O(2)-saturated NiO(111) surfaces, and show that the main effect of Au in the Au/Ni(111) surface alloy is to block the formation of carbonate and thereby increase the low-temperature CO(2) production.

  14. Process development for Ni-Cr-ThO2 and Ni-Cr-Al-ThO2 sheet

    NASA Technical Reports Server (NTRS)

    Cook, R. C.; Norris, L. F.

    1973-01-01

    A process was developed for the production of thin gauge Ni-Cr-ThO2 sheet. The process was based on the elevated temperature deposition of chromium onto a wrought Ni-2%ThO2 sheet and subsequent high temperature diffusion heat treatments to minimize chromium concentration gradients within the sheet. The mechanical properties of the alloy were found to be critically dependent on those of the Ni-2%ThO2 sheet. A similar process for the production of a Ni-Cr-Al-ThO2 alloy having improved oxidation resistance was investigated but the non-reproducible deposition of aluminum from duplex Cr/Al packs precluded successful scale-up. The mechanical properties of the Ni-Cr-Al-ThO2 alloys were generally equivalent to the best Ni-Cr-ThO2 alloy produced in the programme.

  15. Structural stability and mechanical property of Ni(111)-graphene-Ni(111) layered composite: A first-principles study

    NASA Astrophysics Data System (ADS)

    Rong, Ximing; Chen, Jun; Li, Jing-Tian; Zhuang, Jun; Ning, Xi-Jing

    2015-12-01

    A first-principles calculation of the structural stability and mechanical property of Ni(111)-graphene-Ni(111) layered composite was presented. Three different structural models were considered, and the most stable interfacial structure had been determined with top-fcc structure in both sides of graphene. Stretching calculations demonstrate that the tensile stress of the composite can reach twice of that of pure Ni in the ranges of 0-0.2 strain. The Young’s modulus in triaxial directions are 384 (x), 362 (y), and 303 (z) GPa for the Ni(111)-graphene-Ni(111) structure, and 212 (x), 251 (y), and 273 (z) GPa for pure single-crystal Ni(111).

  16. Asymmetric impact of Atlantic Multidecadal Oscillation on El Niño and La Niña characteristics

    NASA Astrophysics Data System (ADS)

    Sung, Mi-Kyung; An, Soon-Il; Kim, Baek-Min; Kug, Jong-Seong

    2015-06-01

    The long-lasting cold surface conditions of North Atlantic, i.e., the negative phase of Atlantic Multidecadal Oscillation (AMO), can intensify the El Niño-Southern Oscillation through the enhanced air-sea coupling under the increased central-to-eastern tropical Pacific mean sea surface temperature. However, the impact of warmer mean sea surface temperature (SST) is more efficient in the intensifying El Niño than La Niña, because of the nature of the exponential growth of atmospheric convection to SST change. Moreover, the farther eastward shift of the atmospheric convection during the negative AMO leads to the stronger El Niño due to the longer delayed negative feedback by oceanic waves. Therefore, the AMO mainly influences the El Niño intensity rather than La Niña intensity.

  17. Anomalous Halo Formation in an Arc-Melted ScNi-Sc₂Ni Off-Eutectic Binary Alloy.

    PubMed

    Wang, Kai; Wei, Ming; Zhang, Lijun

    2016-07-18

    Diverse non-equilibrium eutectic structures have attracted numerous experimental and theoretical studies. One special type is the formation of a halo of one phase around a primary dendrite of another phase. In our experiments, it was occasionally observed that ScNi halos grow as dendritic morphology around the primary Sc 2 Ni dendrites in an arc-melted ScNi-Sc 2 Ni off-eutectic binary alloy. The formation of this anomalous halo structure was then well reproduced by employing quantitative phase-field simulations. Based on the phase-field simulation, It was found that (i) the large undercooling and growth velocity of the ScNi phase during solidification causes the formation of halos; and (ii) the released latent heat induces the recalescence phenomenon, and changes the solidification sequence largely, resulting in the anomalous halo structure in the Sc-34 at % Ni alloy.

  18. First-Principles Study of Substitution of Cu and Au for Ni in Ni3Sn2

    NASA Astrophysics Data System (ADS)

    Tian, Yali; Wu, Ping; Lu, Zhengxiong

    2017-01-01

    The effects of substitution of Cu and Au for Ni on the mechanical, thermodynamic and electronic properties of two different Ni3Sn2 structures are investigated by first-principles calculations. Cu atom at Ni2 site and Au atom at Ni1 site of the η phase lead to the thermodynamic stable structure. For the λ phase, Au atom can only replace the Ni1 site. Substitution causes the decrease of the polycrystalline elastic modulus and the Debye temperature. The degree of anisotropy along Z axis decreases dramatically for η phase, but it increases along Y axis for λ phase after substitution. The Ni3Sn2-based intermetallics are all ductile; the η phase is more ductile than the λ phase. The electronic density of states manifest an energy gap appearing in η phase and the effective mass of the η phase is lower than λ phase.

  19. Effects of Ni Deposition on the Electrochemical Properties of CNT/Ni Electrode and Its Application for Glucose Sensing.

    PubMed

    Zhu, Zhigang; Chen, Cheng; Zhu, Xiangrong; Xie, Rongsi; Flewitt, Andrew J; Milne, William I

    2015-04-01

    A low density CNT forest was fabricated by plasma enhanced chemical vapor deposition, and Ni nanoclusters were well distributed on the sidewall and on top of CNT forest by magnetron sputtering. The Ni deposition time plays an important role in electrochemical properties of the CNT/Ni electrodes, and the optimized deposition time is 150 to 240 s. Cyclic voltammetry and chronoamperometry were used to evaluate the catalytic activities of the CNT/Ni electrodes. The sensitivity of the glucose sensor based on a Ni24OS electrode is able to reach 1433 µA mM(-1) cm(-2), which is much higher than that found using a NiOS electrode.

  20. Microscale Interface Synthesis of Ni-B Amorphous Nanoparticles from NiSO4 by Sodium Borohydride Reduction in Microreactor

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Peng, Jinhui; Meng, Binfang; Li, Wei; Liu, Bingguo; Luo, Huilong

    2016-09-01

    Amorphous nanoparticles have attracted a large amount of interest due to their superior catalytic activity and unique selectivity. The Ni-B amorphous nanoparticles were synthesized from aqueous reduction of NiSO4 by sodium borohydride in microscale interface at room temperature. The size, morphology, elemental compositions, and the chemical composition on the surface of Ni-B amorphous nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). All the results showed that the synthesized particles are Ni-B amorphous nanoparticles with uniform in size distribution and having good dispersion. The mean particle diameter of Ni-B amorphous nanoparticles was around 9 nm. The present work provides an alternative synthesis route for the Ni-B amorphous nanoparticles.

  1. Replacement of Ni by Mn in High-Ni-Containing Austenitic Cast Steels used for Turbo-Charger Application

    NASA Astrophysics Data System (ADS)

    Jung, Seungmun; Jo, Yong Hee; Jeon, Changwoo; Choi, Won-Mi; Lee, Byeong-Joo; Oh, Yong-Jun; Kim, Gi-Yong; Jang, Seongsik; Lee, Sunghak

    2017-02-01

    High-temperature tensile properties of austenitic cast steels fabricated by replacing Ni by Mn in a 20 wt pct Ni-containing steel were investigated. In a steel where 8 wt pct Ni was replaced by 9.2 wt pct of Mn, 17.4 and 9.8 pct of ferrite existed in equilibrium phase diagrams and actual microstructures, respectively, because a role of Mn as an austenite stabilizer decreased, and led to deterioration of high-temperature properties. When 2 to 6 wt pct Ni was replaced by 2.3 to 6.9 wt pct Mn, high-temperature properties were comparable to those of the 20 wt pct Ni-containing steel because ferrites were absent, which indicated the successful replacement of 6 wt pct Ni by Mn, with cost reduction of 27 pct.

  2. Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

    NASA Astrophysics Data System (ADS)

    Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; Barnett, Scott A.; Wang, Jun

    2016-02-01

    The coarsening of Ni in Ni-yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.

  3. Magnetic ordering of YPd2Si-type HoNi2Si and ErNi2Si compounds

    NASA Astrophysics Data System (ADS)

    Morozkin, A. V.; Isnard, O.; Nirmala, R.; Quezado, S.; Malik, S. K.

    2016-12-01

    Magnetic properties of YPd2Si-type HoNi2Si and ErNi2Si were investigated via neutron diffraction and magnetisation measurements. HoNi2Si and ErNi2Si show ferromagnetic-like ordering at TC of 9 K and 7 K, respectively. The paramagnetic Weiss temperatures are 9 K and 11 K and the effective magnetic moments are 10.76 μB/fu and 9.79 μB/fu for HoNi2Si and ErNi2Si compounds, respectively. The HoNi2Si and ErNi2Si are soft ferromagnets with saturation magnetization of 8.1 μB/fu and 7.5 μB/fu, respectively at 2 K and in field of 140 kOe. The isothermal magnetic entropy change, ΔSm, has a maximum value of -15.6 J/kg·K at 10 K for HoNi2Si and -13.9 J/kg·K at 6 K for ErNi2Si for a field change of 50 kOe. Neutron diffraction study in zero applied field shows mixed ferromagnetic-antiferromagnetic ordering of HoNi2Si at 9 K and its magnetic structure is a sum of a-axis ferromagnetic Fa, b-axis antiferromagnetic AFb and c-axis antiferrromagnetic AFc components of Pn‧a21‧={1, mx‧/[1/2, 1/2, 1/2], 2y‧/[0, 1/2, 0], mz/[1/2, 0, 1/2]} magnetic space group and propagation vector K0=[0, 0, 0]. The holmium magnetic moment reaches a value of 9.23(9) μB at 1.5 K and the unit cell of HoNi2Si undergoes isotropic contraction around the temperature of magnetic transition.

  4. Eutectic superalloys strengthened by sigma, Ni3CB lamellae and gamma prime, Ni3Al precipitates

    NASA Technical Reports Server (NTRS)

    Lemkey, F. D.

    1973-01-01

    By means of a screening and solidification optimization study of certain alloys located on the gamma-sigma liquidus surface within the Ni-Cb-Cr-Al system, alloys with high temperature properties superior to those of all known superalloys were defined. One alloy, Ni - 19.7w/o Cb - 6.0w/o Cr - 2.5w/o Al, directionally solidified at 3 cm/hr met or exceeded each program goal. A second alloy, Ni-21.75 w/o Cb-2.55 w/o Al, although deficient in its inherent oxidation resistance, met the other program goals and combined a remarkable insensitivity of composite microstructure to solidification parameters with excellent low temperature toughness. This investigation demonstrated that useful properties for gas turbine airfoil application have been achieved by reinforcing a strong and tough gamma solid solution matrix containing precipitated gamma prime by a lamellar intermetallic compound Ni3 Cb having greater strength at elevated temperature.

  5. Deformation twinning in ordered alloys transformation induced ductility in intermetallics. [TiNi; NiAl

    SciTech Connect

    Goo, E.

    1992-09-01

    Intermetallics, which are ordered alloys, have excellent high temperature strength. Unfortunately a universal problem facing intermetallics is the lack of ductility. This program attempted to look at some novel solutions for enhancing ductility in intermetallics. Deformation twinning has been demonstrated in TiNi to be responsible for its ductility. This was a surprising result since twinning was not believed to occur readily in ordered alloys. Furthermore the twinning occurred on a (114) plane which had not been previously observed. Research into determining the mechanisms for twinning in ordered alloy and understanding how twinning enhances the ductility of intermetallic was studied. Martensitic transformations in many intermetallics also provides a possible means of enhancing ductility. The detwinning of martensite twins or transformation induced martensite provides a mechanism for accommodating large strains. It is known that a metastable martensitic phase may be created by quenching a non-stoichiometric NiAl alloy. This presents the potential of substantial ductility in NiAl. Investigation of the martensitic phase transformation and its effect on the ductility of NiAl alloys was investigated.

  6. NiTi and NiTi-TiC composites. Part 3: Shape-memory recovery

    SciTech Connect

    Fukami-Ushiro, K.L.; Dunand, D.C.

    1996-01-01

    The transformation behavior of near-equiatomic NiTi containing 0, 10, and 20 vol pct TiC particulates is investigated by dilatometry. Undeformed composites exhibit a macroscopic transformation strain larger than predicted when assuming that the elastic transformation mismatch between the matrix and the particulates is unrelaxed, indicating that the mismatch is partially accommodated by matrix twinning during transformation. The thermal recovery behavior of unreinforced NiTi which was deformed primarily by twinning in the martensite phase shows that plastic deformation by slip increases with increasing prestrain, leading to (1) a decrease of the shape-memory strain on heating, (2) an increase of the two-way shape-memory strain on cooling, (3) a widening of the temperature interval over which the strain recovery occurs on heating, and (4) an increase of the transformation temperature hysteresis. For NiTi composites, the recovery behavior indicates that most of the mismatch during mechanical deformation between the TiC particulates and the NiTi matrix is relaxed by matrix twinning. However, some relaxation takes place by matrix slip, resulting in the following trends with increasing TiC content at constant prestrain: (1) decrease of the shape-memory strain on heating, (2) enhancement of the two-way shape-memory strain on cooling, and (3) broadening of the transformation interval on heating.

  7. Phosphine-functionalized NHC Ni(ii) and Ni(0) complexes: synthesis, characterization and catalytic properties.

    PubMed

    Rull, S G; Rama, R J; Álvarez, E; Fructos, M R; Belderrain, T R; Nicasio, M C

    2017-06-13

    Two families of nickel complexes bearing chelating diphenylphosphine-functionalized NHC ligands [Ni(II)(ArNHCPPh2)(allyl)]Cl 1a (Ar = Mes); 1b, (Ar = 2,6-iPr2-C6H3) and [Ni(0)(ArNHCPPh2)(alkene)] 2a (Ar = 2,6-iPr2-C6H3, alkene = styrene); 2b (Ar = 2,6-iPr2-C6H3, alkene = diethyl fumarate) have been prepared and fully characterized. VT-NMR experiments in solution reveal that the allyl derivatives 1a-b are stereochemically nonrigid. The solid-state structure of the Ni(0) derivative 2b is also reported. These complexes display interesting catalytic properties in various cross-coupling reactions. The precatalyst [Ni(0)(ArNHCPPh2)(styrene)] 2a was found to be the most active system. The bulkiness of the N-substituent on the imidazole ring and the low oxidation state of the metal center in 2a accounted for its enhanced catalytic performance. This system catalyzed effectively the coupling of (hetero)aryl chlorides with a range of nucleophiles including Grignard reagents, boronic acids, secondary amines and indoles.

  8. A sulfur segregation study of PWA 1480, NiCrAl, and NiAl alloys

    NASA Technical Reports Server (NTRS)

    Jayne, D. T.; Smialek, J. L.

    1993-01-01

    Some nickel based superalloys show reduced oxidation resistance from the lack of an adherent oxide layer during high temperature cyclic oxidation. The segregation of sulfur to the oxide-metal interface is believed to effect oxide adhesion, since low sulfur alloys exhibit enhanced adhesion. X ray Photoelectron Spectroscopy (XPS) was combined with an in situ sample heater to measure sulfur segregation in NiCrAl, PWA 1480, and NiAl alloys. The polished samples with a 1.5 to 2.5 nm (native) oxide were heated from 650 to 1100 C with hold times up to 6 hr. The sulfur concentration was plotted as a function of temperature versus time at temperature. One NiCrAl sulfur study was performed on the same casting used by Browning to establish a base line between previous Auger Electron Spectroscopy (AES) results and the XPS results of this study. Sulfur surface segregation was similar for PWA 1480 and NiCrAl and reached a maximum of 30 at% at 800 to 850 C. Above 900 C the sulfur surface concentration decreased to about 3 at% at 1100 C. These results are contrasted to the minimal segregation observed for low sulfur hydrogen annealed materials which exhibit improved scale adhesion.

  9. Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

    NASA Astrophysics Data System (ADS)

    Briggs, Samuel A.; Barr, Christopher M.; Pakarinen, Janne; Mamivand, Mahmood; Hattar, Khalid; Morgan, Dane D.; Taheri, Mitra; Sridharan, Kumar

    2016-10-01

    Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni4+ ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy.

  10. Dynamic properties of liquid Ni revisited

    NASA Astrophysics Data System (ADS)

    del Rio, B. G.; González, L. E.; González, D. J.

    2017-08-01

    Liquid Ni has previously been studied by different approaches such as molecular dynamics simulations and experimental techniques including inelastic neutron and X-ray scattering. Although some puzzling results, such as the shape of the sound dispersion curve for q ≤ 1.0 Å-1, have already been sorted out, there still persist some discrepancies, among different studies, for greater q-values. We have performed ab initio simulation calculations which show how those differences can be reconciled. Moreover, we have found that the transverse current spectral functions have some features which, so far, had previously been shown by high pressure liquid metals.

  11. Antibacterial effects of laser ablated Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Shamaila, S.; Wali, H.; Sharif, R.; Nazir, J.; Zafar, N.; Rafique, M. S.

    2013-10-01

    The interaction of nickel nanoparticles with Escherichia coli (E. coli) bacteria has been studied. The nickel nanoparticles have been fabricated by continuous wave laser ablation of nickel target and their properties are studied using different characterization techniques. The antibacterial activity of nickel nanoparticles was checked against E. coli bacteria. Escherichia coli were cultured in nutrients broth and different concentrations of nickel nanoparticles were added to bacterial culture solution to investigate the interaction of nickel nanoparticles with bacteria and to check toxicity of the nickel nanoparticles against E. coli. The fabricated Ni nanoparticles have exhibited considerable antimicrobial activity against E. coli.

  12. Giant monopole strength in {sup 58}Ni

    SciTech Connect

    Lui, Y.-W.; Clark, H. L.; Youngblood, D. H.

    2000-06-01

    The strength distribution of the giant monopole resonance in {sup 58}Ni has been measured from E{sub x}=10 to 35 MeV using small-angle scattering of 240-MeV {alpha} particles. E0 strength corresponding to 74{sub -12}{sup +22}% of the E0 EWSR was found between E{sub x}=12.0 and 31.1 MeV with a centroid of 20.30{sub -0.14}{sup +1.69} MeV. (c) 2000 The American Physical Society.

  13. Notch effects on room temperature tensile and bend properties of Ni3Al and Ni3Al+B

    NASA Technical Reports Server (NTRS)

    Khadkikar, P. S.; Rigney, J. D.; Lewandowski, J. J.; Vedula, K.

    1989-01-01

    The notched mechanical properties of Ni3Al and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Tensile tests performed using double-notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3Al+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

  14. Ni ion release, osteoblast-material interactions, and hemocompatibility of hafnium-implanted NiTi alloy.

    PubMed

    Zhao, Tingting; Li, Yan; Zhao, Xinqing; Chen, Hong; Zhang, Tao

    2012-04-01

    Hafnium ion implantation was applied to NiTi alloy to suppress Ni ion release and enhance osteoblast-material interactions and hemocompatibility. The auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscope results showed that a composite TiO(2)/HfO(2) nanofilm with increased surface roughness was formed on the surface of NiTi, and Ni concentration was reduced in the superficial surface layer. Potentiodynamic polarization tests displayed that 4 mA NiTi sample possessed the highest E(br) - E(corr), 470 mV higher than that of untreated NiTi, suggesting a significant improvement on pitting corrosion resistance. Inductively coupled plasma mass spectrometry tests during 60 days immersion demonstrated that Ni ion release rate was remarkably decreased, for example, a reduction of 67% in the first day. The water contact angle increased and surface energy decreased after Hf implantation. Cell culture and methyl-thiazol-tetrazolium indicated that Hf-implanted NiTi expressed enhanced osteoblasts adhesion and proliferation, especially after 7 days culture. Hf implantation decreased fibrinogen adsorption, but had almost no effect on albumin adsorption. Platelets adhesion and activation were suppressed significantly (97% for 4 mA NiTi) and hemolysis rate was decreased by at least 57% after Hf implantation. Modified surface composition and morphology and decreased surface energy should be responsible for the improvement of cytocompatibility and hemocompatibility. Copyright © 2011 Wiley Periodicals, Inc.

  15. Low temperature diffusion coefficients in the Fe-Ni and FeNiP systems: Application to meteorite cooling rates

    NASA Technical Reports Server (NTRS)

    Dean, D. C.; Goldstein, J. I.

    1984-01-01

    The interdiffusion coefficient of FeNi in fcc taenite (gamma) of Fe-Ni and Fe-Ni-0.2 P alloys was measured as a function of temperature between 600 and 900 C. This temperature range is directly applicable to the nucleation and growth of the Widmanstatten pattern in iron meteorites and metal regions of stony and stony-iron meteorites. Diffusion couples were made from FeNi or FeNiP alloys which ensured that the couples were in the taenite phase at the diffusion temperature. The presence or absence of grain boundary diffusion was determined by measuring the Ni profile normal to the existing grain boundaries with the AEM. Ignoring any variation of interdiffusion coefficient with composition, the measured data was plotted versus the reciprocal of the diffusion temperature. The FeNi data generally follow the extrapolated Goldstein, et al. (1965) data from high temperatures. The FeNiP data indicates that small additions of P (0.2 wt%) cause a 3 to 10 fold increase in the FeNi interdifussion coefficient increasing with decreasing temperature. This increase is about the same as that predicted by Narayan and Goldstein (1983) at the Widmanstatten growth temperature.

  16. Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

    SciTech Connect

    Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J.

    2013-06-21

    We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 Multiplication-Sign 10{sup -9} s) at lower energies. Microstructural studies, conducted by X-ray diffraction ({theta}-2{theta} and {phi} techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO<111 > Double-Vertical-Line Double-Vertical-Line c-YSZ<001> and in-plane NiO<110> Double-Vertical-Line Double-Vertical-Line c-YSZ<100>. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min{sup -1} for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies

  17. The application of electrochemical impedance spectroscopy for characterizing the degradation of Ni(OH)2/NiOOH electrodes

    NASA Technical Reports Server (NTRS)

    Macdonald, Digby D.

    1989-01-01

    The use of wide-band electrochemical impedance spectroscopy is described for characterizing the degradation of porous Ni(OH)2/NiOOH electrodes in concentrated KOH electrolyte solutions. The impedance spectra are interpreted in terms of a finite electrical transmission line and the changes in the components of the electrical analog are followed as a function of cycle number. The degradation of the capacity of rolled and bonded Ni(OH)2/NiOOH electrodes is caused by rupture of ohmic contacts within the active mass and by restructuring which results in a decrease in the number of active pores.

  18. Low temperature diffusion coefficients in the Fe-Ni and FeNiP systems: Application to meteorite cooling rates

    NASA Technical Reports Server (NTRS)

    Dean, D. C.; Goldstein, J. I.

    1984-01-01

    The interdiffusion coefficient of FeNi in fcc taenite (gamma) of Fe-Ni and Fe-Ni-0.2 P alloys was measured as a function of temperature between 600 and 900 C. This temperature range is directly applicable to the nucleation and growth of the Widmanstatten pattern in iron meteorites and metal regions of stony and stony-iron meteorites. Diffusion couples were made from FeNi or FeNiP alloys which ensured that the couples were in the taenite phase at the diffusion temperature. The presence or absence of grain boundary diffusion was determined by measuring the Ni profile normal to the existing grain boundaries with the AEM. Ignoring any variation of interdiffusion coefficient with composition, the measured data was plotted versus the reciprocal of the diffusion temperature. The FeNi data generally follow the extrapolated Goldstein, et al. (1965) data from high temperatures. The FeNiP data indicates that small additions of P (0.2 wt%) cause a 3 to 10 fold increase in the FeNi interdifussion coefficient increasing with decreasing temperature. This increase is about the same as that predicted by Narayan and Goldstein (1983) at the Widmanstatten growth temperature.

  19. Tunability of exchange bias in Ni@NiO core-shell nanoparticles obtained by sequential layer deposition

    DOE PAGES

    D'Addato, Sergio; Spadaro, Maria Chiara; Luches, Paola; ...

    2015-01-01

    Films of magnetic Ni@NiO core–shell nanoparticles (NPs, core diameter d ≅ 12 nm, nominal shell thickness variable between 0 and 6.5 nm) obtained with sequential layer deposition were investigated, to gain insight into the relationships between shell thickness/morphology, core-shell interface, and magnetic properties. Different values of NiO shell thickness ts could be obtained while keeping the Ni core size fixed, at variance with conventional oxidation procedures where the oxide shell is grown at the expense of the core. Chemical composition, morphology of the as-produced samples and structural features of the Ni/NiO interface were investigated with x-ray photoelectron spectroscopy and microscopymore » (scanning electron microscopy, transmission electron microscopy) techniques, and related with results from magnetic measurements obtained with a superconducting quantum interference device. The effect of the shell thickness on the magnetic properties could be studied. The exchange bias (EB) field Hbias is small and almost constant for ts up to 1.6 nm; then it rapidly grows, with no sign of saturation. This behavior is clearly related to the morphology of the top NiO layer, and is mostly due to the thickness dependence of the NiO anisotropy constant. The ability to tune the EB effect by varying the thickness of the last NiO layer represents a step towards the rational design and synthesis of core–shell NPs with desired magnetic properties.« less

  20. Compressive strength of directionally solidified NiAl-NiAlNb intermetallics at 1200 and 1300 K

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

    Results are presented from measurements of 1200 K and 1300 K compressive properties of two directionally solidified NiAl-NiAlNb compositions (in at. pct): Ni-41.75Al-16.5Nb (eutectic composition) and Ni-47.5Al-8.9Nb-1.3C (Al-rich composition). Results showed that the strength of the eutectic was a factor of 2 greater than that of the Al-rich composition. However, the analysis of the compressive stress-strain data indicated that the deformation mechanism was the same in both materials.

  1. Ni biogeochemical cycle through geological time: insights from Ni isotope variations in modern and ancient marine metallifereous deposits

    NASA Astrophysics Data System (ADS)

    Gueguen, B.; Rouxel, O.; Ponzevera, E.; Sorensen, J. V.; Toner, B.; Bekker, A.

    2011-12-01

    Studies of isotopic composition of transition metals such as Fe, Cu, Zn, and Mo as biogeochemical tracers became popular recently. Since Ni is ubiquitous in marine metallifereous deposits and its concentration in water column is coupled to that of nutrients, it has a potential as a biogeochemical tracer. Isotopic analyses were performed on a Neptune MC-ICP-MS using a double-spike correction method for instrumental mass bias. Deep-sea ferromanganese crusts have been used to establish a record of seawater over the last 60 Myr. Our results show that Fe-Mn crusts from both Atlantic and Pacific oceans are systematically enriched in heavy isotopes relative to Bulk Silicate Earth with δ60/58Ni values ranging from 0.30 to 1.80% (2se = 0.04%). In contrast, Iron Formations (IF) with ages ranging from 3.8 to 0.7 Gyr display a wider range of values with a striking negative Ni isotope excursion down to -2.46% (2se = 0.03%) in Neoproterozoic IF. Although correlation between Ni isotope compositions, Ni concentrations and BIFs ages seems to be lacking, several Ni isotope excursions to either positive or negative Ni isotope values are notable prior to 2.4 Gyr. Methanogens were likely abundant in Precambrian water column until they retreated to pore waters and local environments once the oceans were oxygenated after the Great Oxidation Event (GOE). They preferentially uptake light Ni isotopes leaving isotopically heavier Ni in oceans. Our Ni isotope record of Precambrian IF does not show a unidirectional change across the GOE implying that Ni isotope composition of the Archean oceans was not dominated by this metabolism. Preliminary Ni adsorption experiments on Fe-Mn oxy-hydroxides show a maximum fractionation factor between the mineral phase and aqueous solution of -1.00% (2se = 0.03%). Hence, isotopic variations in Fe-Mn crusts and IF cannot be simply explained by adsorption processes, but require changes in composition of either Ni sources (local or global) to seawater (e

  2. A scanning tunnelling microscopy study of C and N adsorption phases on the vicinal Ni(100) surfaces Ni(810) and Ni(911)

    NASA Astrophysics Data System (ADS)

    Driver, S. M.; Toomes, R. L.; Woodruff, D. P.

    2016-04-01

    The influence of N and C chemisorption on the morphology and local structure of nominal Ni(810) and Ni(911) surfaces, both vicinal to (100) but with [001] and [ 01 1 bar ] step directions, respectively, has been investigated using scanning tunnelling microscopy (STM) and low energy electron diffraction. Ni(911) undergoes substantial step bunching in the presence of both adsorbates, with the (911)/N surface showing (411) facets, whereas for Ni(810), multiple steps 2-4 layers high are more typical. STM atomic-scale images show the (2 × 2)pg 'clock' reconstruction on the (100) terraces of the (810) surfaces with both C and N, although a second c(2 × 2) structure, most readily reconciled with a 'rumpling' reconstruction, is also seen on Ni(810)/N. On Ni(911), the clock reconstruction is not seen on the (100) terraces with either adsorbate, and these images are typified by protrusions on a (1 × 1) mesh. This absence of clock reconstruction is attributed to the different constraints imposed on the lateral movements of the surface Ni atoms adjacent to the up-step edge of the terraces with a [ 01 1 bar ] step direction.

  3. Exchange bias magnetism in films of NiFe/(Ni,Fe)O nanocrystallite dispersions

    SciTech Connect

    Hsiao, C.-H.; Chi, C.-C.; Wang, S.; Ouyang, H.; Desautels, R. D.; Lierop, J. van; Lin, K.-W.; Lin, T.-L.

    2014-05-07

    Ni{sub 3}Fe/(Ni,Fe)O thin films having a nanocrystallite dispersion morphology were prepared by a reactive ion beam-assisted deposition technique. The crystallite sizes of these dispersion-based films were observed to decrease from 8.4 ± 0.3 nm to 3.4 ± 0.3 nm as the deposition flow-rate increased from 2.78% to 7.89% O{sub 2}/Ar. Thin film composition was determined using selective area electron diffraction images and Multislice simulations. Through a detailed analysis of high resolution transmission electron microscopy images, the nanocrystallites were determined to be Ni{sub 3}Fe (a ferromagnet), NiO, and FeO (both antiferromagnets). It was determined that the interfacial molar Ni{sub 3}Fe ratio in the nanocrystallite dispersions increased slightly at first, then decreased as the oxygen content was increased; at 7.89% O{sub 2}/Ar, the interfacial molar ratio was essentially zero (only NiO and FeO remained). For nanocrystallite dispersion films grown with O{sub 2}/Ar flow-rate greater than 7.89%, no interfacial (intermixed) Ni{sub 3}Fe phase was detected, which resulted in no measurable exchange bias. Comparing the exchange bias field between the nanocrystallite dispersion films at 5 K, we observed a decrease in the magnitude of the exchange bias field as the nanocrystallite size decreased. The exchange bias coupling for all samples measured set in at essentially the same temperature (i.e., the exchange bias blocking temperature). Since the ferromagnetic/anti-ferromagnetic (FM/AFM) contact area in the nanocrystallite dispersion films increased as the nanocrystallite size decreased, the increase in the magnitude of the exchange bias could be attributed to larger regions of defects (vacancies and bond distortions) which occupied a significant portion of the FM/AFM interfaces in the nanocrystallite dispersion films.

  4. The design of underwater superoleophobic Ni/NiO microstructures with tunable oil adhesion

    NASA Astrophysics Data System (ADS)

    Zhang, Enshuang; Cheng, Zhongjun; Lv, Tong; Li, Li; Liu, Yuyan

    2015-11-01

    Controlling oil adhesion in water is a fundamental issue in many practical applications for surfaces. Currently, almost all studies on underwater oil adhesion control are concentrated on regulating surface chemistry on polymer surfaces, and structure-dependent underwater oil adhesion is still rare, especially on inorganic materials. Herein, we report a series of underwater superoleophobic Ni/NiO surfaces with controlled oil adhesions by combining electro-deposition and heating techniques. The adhesive forces between an oil droplet and the surfaces can be adjusted from an extremely low (less than 1 μN) to a very high value (about 60 μN), and the tunable effect can be attributed to different wetting states that result from different microstructures on the surfaces. Moreover, the oil-adhesion controllability for different types of oils was also analyzed and the applications of the surface including oil droplet transportation and self-cleaning were discussed. The results reported herein provide a new feasible method for fabrication of underwater superoleophobic surfaces with controlled adhesion, and improve the understanding of the relationship between surface microstructures, adhesion, and the fabrication principle of tunable oil adhesive surfaces.Controlling oil adhesion in water is a fundamental issue in many practical applications for surfaces. Currently, almost all studies on underwater oil adhesion control are concentrated on regulating surface chemistry on polymer surfaces, and structure-dependent underwater oil adhesion is still rare, especially on inorganic materials. Herein, we report a series of underwater superoleophobic Ni/NiO surfaces with controlled oil adhesions by combining electro-deposition and heating techniques. The adhesive forces between an oil droplet and the surfaces can be adjusted from an extremely low (less than 1 μN) to a very high value (about 60 μN), and the tunable effect can be attributed to different wetting states that result from

  5. Phase equilibria, formation, crystal and electronic structure of ternary compounds in Ti-Ni-Sn and Ti-Ni-Sb ternary systems

    NASA Astrophysics Data System (ADS)

    Romaka, V. V.; Rogl, P.; Romaka, L.; Stadnyk, Yu.; Melnychenko, N.; Grytsiv, A.; Falmbigl, M.; Skryabina, N.

    2013-01-01

    The phase equilibria of the Ti-Ni-Sn and Ti-Ni-Sb ternary systems have been studied in the whole concentration range by means of X-ray and EPM analyses at 1073 K and 873 K, respectively. Four ternary intermetallic compounds TiNiSn (MgAgAs-type), TiNi2-xSn (MnCu2Al-type), Ti2Ni2Sn (U2Pt2Sn-type), and Ti5NiSn3 (Hf5CuSn3-type) are formed in Ti-Ni-Sn system at 1073 K. The TiNi2Sn stannide is characterized by homogeneity in the range of 50-47 at% of Ni. The Ti-Ni-Sb ternary system at 873 K is characterized by formation of three ternary intermetallic compounds, Ti0.8NiSb (MgAgAs-type), Ti5Ni0.45Sb2.55 (W5Si3-type), and Ti5NiSb3 (Hf5CuSn3-type). The solubility of Ni in Ti0.8NiSb decreases number of vacancies in Ti site up to Ti0.91Ni1.1Sb composition.

  6. Ternary Pd-Ni-P hybrid electrocatalysts derived from Pd-Ni core-shell nanoparticles with enhanced formic acid oxidation activity.

    PubMed

    Liang, Xin; Liu, Bo; Zhang, Juntao; Lu, Siqi; Zhuang, Zhongbin

    2016-09-25

    Ternary Pd-Ni-P hybrid electrocatalysts were synthesized through low temperature phosphidation of Pd-Ni core-shell nanoparticles. They show enhanced formic acid electro-oxidation activity compared to Pd, Pd-Ni and Pd-P nanoparticles, which is ascribed to the synergistic effect of the Ni and P components with Pd.

  7. Fe-Ni-C system at high pressure

    NASA Astrophysics Data System (ADS)

    Narygina, O.; Dubrovinsky, L.; McCammon, C.; Frost, D.; Miyajima, N.; Prakapenka, V.

    2008-12-01

    Apart from being technologically important, FeNi alloys introduce particularly interest to the material sciences as well as to the geosciences. It is generally accepted that the Earth's core is predominantly composed by FeNi alloy with 10-15 wt% Ni. The certain amount of the light element(s) is also known to be presented in the Core. A number of candidates for the light component have been proposed, including sulphur, oxygen, hydrogen and carbon. In favor of the last one the following arguments can be listed (i) high cosmic abundance, (ii) chemical affinity to iron even at low pressures and (iii) capability of lowering the density of molten iron. Although there is quite a bit of experimental and theoretical results on high pressure high temperature behavior of the system Fe-C, there is still lack of information about the phase relations in Fe-Ni- C system at elevated pressures and temperatures. Therefore we provided a series of compression experiments on the system Fe-Ni-C at pressures up to 53 GPa in temperature range 300 - 2600 K (combining diamond anvil cell and large volume press techniques) in order to investigate phase diagram of Fe-Ni system and the influence of carbon on the phase relations in the system at elevated pressures and temperatures. We observed that dissolution of even 1 wt% carbon in FeNi alloys with 10, 15 and 22 wt% Ni leads to dramatic changes in the system: presence of carbon stabilizes fcc-structured FeNi through the redistribution of nickel. Combining Mössbauer spectroscopy, XRD, TEM and chemical analyses by microprobe and SEM techniques we detected the formation of Ni-poor and Ni-enriched phases, with different elastic and structural properties.

  8. Morphology and composition of Ni-Co electrodeposited powders

    SciTech Connect

    Maksimovic, V.M.; Lacnjevac, U.C.; Stoiljkovic, M.M.; Pavlovic, M.G.; Jovic, V.D.

    2011-12-15

    The morphology, phase and chemical composition of Ni-Co alloy powders electrodeposited from an ammonium sulfate-boric acid containing electrolyte with different ratio of Ni/Co ions were investigated. The ratios of Ni/Co ions were 1/1, 1/2 and 1/3. The morphology, chemical composition and phase composition of the electrodeposited alloy powders were investigated using AES, SEM, EDS and XRD analysis. Composition of the electrolyte, i.e. the ratio of Ni/Co concentrations was found to influence both, the alloy phase composition and the morphology of Ni-Co alloy powders. At the highest ratio of Ni/Co = 1/1 concentrations typical 2D fern-like dendritic particles were obtained. With a decrease of Ni/Co ions ratio among 2D fern-like dendrites, 3D dendrites and different agglomerates were obtained. X-ray diffraction studies showed that the alloy powders mainly consisted of the face-centered cubic {alpha}-nickel phase and hexagonal close-packed {epsilon}-cobalt phase and minor proportions of face-centered cubic {alpha}-cobalt phase. The occurrence of the latter phase was observed only in the alloy powder with the higher cobalt concentration in electrolyte. The electrodeposition of Ni-Co powders occurred in an anomalous manner. - Highlights: Black-Right-Pointing-Pointer Ni-Co alloys powders were successfully electrodeposited. Black-Right-Pointing-Pointer Composition of the electrolyte (Ni/Co ions ratio) was found to influence on morphology of powders. Black-Right-Pointing-Pointer The electrodeposition of Ni-Co powders occurred in an anomalous manner.

  9. Methanethiol chemistry on TiO 2-supported Ni clusters

    NASA Astrophysics Data System (ADS)

    Ozturk, O.; Park, J. B.; Black, T. J.; Rodriguez, J. A.; Hrbek, J.; Chen, D. A.

    2008-10-01

    The thermal decomposition of methanethiol on Ni clusters grown on TiO 2(1 1 0) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). On all of the Ni surfaces investigated, methane and hydrogen were observed as gaseous products in the TPD experiments, and the only sulfur-containing species that desorbed from the surface was methanethiol itself at low temperatures. The two pathways for methanethiol reaction were hydrodesulfurization to produce methane and nonselective decomposition, which leaves atomic carbon and sulfur on the surface. From high resolution XPS studies, methyl thiolate was identified as the surface intermediate for reaction on TiO 2 and on all of the Ni surfaces investigated, similar to what is observed on single-crystal Ni surfaces. However, the binding sites for methyl thiolate on the 1 ML (monolayer) Ni clusters were different from those on the Ni clusters at coverages of 2.5 ML and higher, based on the S(2p) binding energies for methyl thiolate. No distinct changes in activity or selectivity were observed for the smaller Ni clusters grown at low coverage compared to the more film-like Ni surfaces other than what could be accounted for by changes in total surface area. Interactions between the Ni clusters and the TiO 2 support had two main effects on chemical activity. First, carbon was oxidized by oxygen from the TiO 2 lattice to produce CO at temperatures above 800 K. Second, annealing induced encapsulation of the Ni clusters by reduced TiO x and chemisorbed oxygen. At 800 K, the Ni clusters were totally encapsulated, resulting in a complete loss of methanethiol activity; partial encapsulation at 700 K caused a smaller decrease in activity accompanied by increased oxidation of carbon by lattice oxygen.

  10. Methanethiol Chemistry on TiO2-Supported Ni Clusters

    SciTech Connect

    Ozturk,O.; Park, J.; Black, T.; Rodriguez, J.; Hrbek, J.; Chen, D.

    2008-01-01

    The thermal decomposition of methanethiol on Ni clusters grown on TiO2(1 1 0) was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). On all of the Ni surfaces investigated, methane and hydrogen were observed as gaseous products in the TPD experiments, and the only sulfur-containing species that desorbed from the surface was methanethiol itself at low temperatures. The two pathways for methanethiol reaction were hydrodesulfurization to produce methane and nonselective decomposition, which leaves atomic carbon and sulfur on the surface. From high resolution XPS studies, methyl thiolate was identified as the surface intermediate for reaction on TiO2 and on all of the Ni surfaces investigated, similar to what is observed on single-crystal Ni surfaces. However, the binding sites for methyl thiolate on the 1 ML (monolayer) Ni clusters were different from those on the Ni clusters at coverages of 2.5 ML and higher, based on the S(2p) binding energies for methyl thiolate. No distinct changes in activity or selectivity were observed for the smaller Ni clusters grown at low coverage compared to the more film-like Ni surfaces other than what could be accounted for by changes in total surface area. Interactions between the Ni clusters and the TiO2 support had two main effects on chemical activity. First, carbon was oxidized by oxygen from the TiO2 lattice to produce CO at temperatures above 800 K. Second, annealing induced encapsulation of the Ni clusters by reduced TiOx and chemisorbed oxygen. At 800 K, the Ni clusters were totally encapsulated, resulting in a complete loss of methanethiol activity; partial encapsulation at 700 K caused a smaller decrease in activity accompanied by increased oxidation of carbon by lattice oxygen.

  11. FeNi-based magnetoimpedance multilayers: Tailoring of the softness by magnetic spacers

    NASA Astrophysics Data System (ADS)

    Svalov, A. V.; Fernandez, E.; Garcia-Arribas, A.; Alonso, J.; Fdez-Gubieda, M. L.; Kurlyandskaya, G. V.

    2012-04-01

    The microstructure and magnetic properties of sputtered permalloy films and FeNi(170 nm)/X/FeNi(170 nm) (X = Co, Fe, Gd, Gd-Co) sandwiches were studied. Laminating of the thick FeNi film with various spacers was done in order to control the magnetic softness of FeNi-based multilayers. In contrast to the Co and Fe spacers, Gd and Gd-Co magnetic spacers improved the softness of the FeNi/X/FeNi sandwiches. The magnetoimpedance responses were measured for [FeNi/Ti(6 nm)]2/FeNi and [FeNi/Gd(2 nm)]2/FeNi multilayers in a frequency range of 1-500 MHz: for all frequencies under consideration the highest magnetoimpedance variation was observed for [FeNi/Gd(2 nm)]2/FeNi multilayers.

  12. Strengthening by Substitutional Solutes and the Temperature Dependence of the Flow Stress in Ni3Al

    DTIC Science & Technology

    1989-05-26

    stoichiometric composition in polycrystalline Ni3AI and Ni3Ga. 29 Fig. 3.1 The Ni-Al binary-alloy phase diagram in vacinity of Ni3A1 phase, as verified in...I <I- iai / I I- I I I I000 - - II 21 25 29 33 37 ATOMIC % Al Fig. 3.1 The Ni-Al binary-alloy phase diagram in vacinity of Ni3Al phase, as verified

  13. Surface Composition of NiPd Alloys

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D.; Khalil, Joe; Bozzolo, Guillermo; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Surface segregation in Ni-Pd alloys has been studied using the BFS method for alloys. Not only does the method predict an oscillatory segregation profile but it also indicates that the number of Pd-enriched surface planes can vary as a function of orientation. The segregation profiles were computed as a function of temperature, crystal face, and composition. Pd enrichment of the first layer is observed in (111) and (100) surfaces, and enrichment of the top two layers occurs for (110) surfaces. In all cases, the segregation profile shows oscillations that are actually related to weak ordering tendencies in the bulk. An atom-by-atom analysis was performed to identify the competing mechanisms leading to the observed surface behaviors. Large-scale atomistic simulations were also performed to investigate the temperature dependence of the segregation profiles as well as for analysis of the bulk structures. Finally, the observed surface behaviors are discussed in relation to the bulk phase structure of Ni-Pd alloys, which exhibit a tendency to weakly order.

  14. El Niño rides again

    NASA Astrophysics Data System (ADS)

    Friebele, Elaine

    Another weather-disrupting El Niño may be brewing in the Pacific Ocean, according to ocean measurements taken by NASA instruments on two orbiting satellites. Sea-surface height measurements taken by the radar altimeter on board the joint U.S.-French TOPEX/Poseidon satellite and wind data collected by the NASA scatterometer on Japan's Advanced Earth Observing Satellite (ADEOS) have been used together for the first time to predict changing weather conditions in the tropical Pacific Ocean.El Niño occurs when steady westward blowing trade winds weaken and reverse direction, moving the mass of warm water near Australia eastward to the coast of South America. The displacement of the warm water mass alters the atmospheric jet stream and weather patterns around the world. The TOPEX/Poseidon satellite uses an altimeter to bounce radar signals off the ocean's surface to make precise measurements of the distance between the satellite and sea surface. Researchers then map the barely perceptible hills and valleys of the sea surface by combining these data with measurements pinpointing the satellite's exact location in space.

  15. Ultrathin Silver Films on Ni(111)

    SciTech Connect

    Meyer, A.; Flege, J; Rettew, R; Senanayake, S; Schmidt, T; Alamgir, F; Falta, J

    2010-01-01

    The growth and atomic structure of ultrathin silver films on Ni(111) was investigated by low-energy electron microscopy and diffraction (LEEM/LEED) as well as intensity-voltage [I(V)]-LEEM in the growth temperature range between 470 and 850 K. We find that silver grows in a Stranski-Krastanov mode with a two monolayer thin wetting layer which takes on a p(7 x 7) reconstruction at temperatures lower than 700 K and a ({radical}52 x {radical}52)R13.9{sup o} reconstruction at higher temperatures. The occurrence of the two distinct reconstructions is shown to have profound implications for the growth characteristics of films exhibiting thicknesses of one and two monolayers. The nanoscale I(V) characteristics of the films were analyzed by means of multiple-scattering calculations based on dynamical LEED theory. Furthermore, the vertical interatomic spacing at the interface between the Ag film and the Ni substrate was determined to (2.8 {+-} 0.1) {angstrom} for all film thicknesses (<13 ML) while the uppermost silver layer relaxes by about (4 {+-} 1)% toward the crystal.

  16. Ultrathin Silver Films on Ni(111)

    SciTech Connect

    Flege, J.I.; Senanayake, S.; Meyer, A.; Rettew, R.E.; Schmidt, T.; Alamgir, F.M.; Falta, J.

    2010-08-16

    The growth and atomic structure of ultrathin silver films on Ni(111) was investigated by low-energy electron microscopy and diffraction (LEEM/LEED) as well as intensity-voltage [I(V)]-LEEM in the growth temperature range between 470 and 850 K. We find that silver grows in a Stranski-Krastanov mode with a two monolayer thin wetting layer which takes on a p(7 x 7) reconstruction at temperatures lower than 700 K and a ({radical}52 x {radical}52)R13.9{sup o} reconstruction at higher temperatures. The occurrence of the two distinct reconstructions is shown to have profound implications for the growth characteristics of films exhibiting thicknesses of one and two monolayers. The nanoscale I(V) characteristics of the films were analyzed by means of multiple-scattering calculations based on dynamical LEED theory. Furthermore, the vertical interatomic spacing at the interface between the Ag film and the Ni substrate was determined to (2.8 {+-} 0.1) {angstrom} for all film thicknesses (<13 ML) while the uppermost silver layer relaxes by about (4 {+-} 1)% toward the crystal.

  17. Monolayer dispersion of NiO in NiO/Al2O3 catalysts probed by positronium atom

    NASA Astrophysics Data System (ADS)

    Zhang, H. J.; Chen, Z. Q.; Wang, S. J.

    2012-01-01

    NiO/Al2O3 catalysts with different NiO loadings were prepared by impregnation method. The monolayer dispersion capacity of NiO is determined to be about 9 wt.% through XRD quantitative phase analysis. Positron lifetime spectra measured for NiO/Al2O3 catalysts comprise two long and two short lifetime components, where the long lifetimes τ3 and τ4 correspond to ortho-positronium (o-Ps) annihilation in microvoids and large pores, respectively. With increasing loading of NiO from 0 to 9 wt.%, τ4 drops drastically from 88 to 38 ns. However, when the NiO loading is higher than 9 wt.%, τ4 shows a slower decrease. Variation of λ4 (1/τ4) as a function of the NiO content can be well fitted by two straight lines with different slopes. The relative intensity of τ4 also shows a fast decrease followed by a slow decrease for the NiO content lower and higher than 9 wt.%, respectively. The coincidence Doppler broadening measurements reveal a continuous increase of S parameter with increasing NiO loading up to 9 wt.% and then a decrease afterwards. This is due to the variation in intensity of the narrow component contributed by the annihilation of para-positronium (p-Ps). Our results show that the annihilation behavior of positronium is very sensitive to the dispersion state of NiO on the surface of γ-Al2O3. When the NiO loading is lower than monolayer dispersion capacity, spin conversion of positronium induced by NiO is the dominant effect, which causes decrease of the longest lifetime and its intensity but increase of the narrow component intensity. After the NiO loading is higher than monolayer dispersion capacity, the spin conversion effect becomes weaker and inhibition of positronium formation by NiO is strengthened, which results in decrease of both the long lifetime intensity and the narrow component intensity. The reaction rate constant is determined to be (1.50 ± 0.04) × 1010 g mol-1s-1 and (3.43 ± 0.20) × 109 g mol-1 s-1 for NiO content below and above

  18. Monolayer dispersion of NiO in NiO/Al2O3 catalysts probed by positronium atom.

    PubMed

    Zhang, H J; Chen, Z Q; Wang, S J

    2012-01-21

    NiO/Al(2)O(3) catalysts with different NiO loadings were prepared by impregnation method. The monolayer dispersion capacity of NiO is determined to be about 9 wt.% through XRD quantitative phase analysis. Positron lifetime spectra measured for NiO/Al(2)O(3) catalysts comprise two long and two short lifetime components, where the long lifetimes τ(3) and τ(4) correspond to ortho-positronium (o-Ps) annihilation in microvoids and large pores, respectively. With increasing loading of NiO from 0 to 9 wt.%, τ(4) drops drastically from 88 to 38 ns. However, when the NiO loading is higher than 9 wt.%, τ(4) shows a slower decrease. Variation of λ(4) (1/τ(4)) as a function of the NiO content can be well fitted by two straight lines with different slopes. The relative intensity of τ(4) also shows a fast decrease followed by a slow decrease for the NiO content lower and higher than 9 wt.%, respectively. The coincidence Doppler broadening measurements reveal a continuous increase of S parameter with increasing NiO loading up to 9 wt.% and then a decrease afterwards. This is due to the variation in intensity of the narrow component contributed by the annihilation of para-positronium (p-Ps). Our results show that the annihilation behavior of positronium is very sensitive to the dispersion state of NiO on the surface of γ-Al(2)O(3). When the NiO loading is lower than monolayer dispersion capacity, spin conversion of positronium induced by NiO is the dominant effect, which causes decrease of the longest lifetime and its intensity but increase of the narrow component intensity. After the NiO loading is higher than monolayer dispersion capacity, the spin conversion effect becomes weaker and inhibition of positronium formation by NiO is strengthened, which results in decrease of both the long lifetime intensity and the narrow component intensity. The reaction rate constant is determined to be (1.50 ± 0.04) × 10(10) g mol(-1) s(-1) and (3.43 ± 0.20) × 10(9) g mol(-1) s(-1

  19. Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

    DOE PAGES

    Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; ...

    2016-02-25

    The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors.more » Here in this paper, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. In conclusion, the finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less

  20. Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

    SciTech Connect

    Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; Barnett, Scott A.; Wang, Jun

    2016-02-25

    The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here in this paper, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. In conclusion, the finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.

  1. A Classroom Activity: Tracking El Niño

    ERIC Educational Resources Information Center

    Ribbe, Joachim

    2016-01-01

    This paper aims to introduce an activity for teachers to assist in meeting learning outcomes as defined in the earth and environmental science units of the Australian Curriculum. The focus of the classroom tasks is on a global ocean feature referred to as El Niño. This phenomenon is part of the El Niño Southern Oscillation, which is largely…

  2. Solid state SiC/Ni alloy reaction

    NASA Astrophysics Data System (ADS)

    Jackson, M. R.; Mehan, R. L.; Davis, A. M.; Hall, E. L.

    1983-02-01

    The solid state reaction between silicon carbide and a model superalloy consisting of 70 at. pct Ni, 20 at. pct Cr, and 10 at. pct Al was studied between 700 °C and 1150 °C for times ranging from “0” hours to 330 hours. Reaction couples consisting of SiC/Ni, SiC/Cr, and SiC/NiCr were also studied. The reactions were carried out in air with the materials, in the shape of discs, maintained in contact under a pressure of 7 MPa. A reaction was detected with SiC and the model alloy at all temperatures studied, and the reaction was diffusion controlled with an activation energy of 184 kJ/mole. In the ceramic the reaction was dominated by the diffusion of Ni into the ceramic forming a banded structure consisting of alternating layers of δ-Ni2Si and a two phase mixture of graphite and δ. On the metal side, the reaction was very dependent on the presence of alloying elements, with pure Ni reacting to the greatest extent, followed by the binary NiCr alloy, and finally by NiCrAl. The growth and presence of the phases detected in these reactions is consistent with phase equilibria concepts.

  3. A Classroom Activity: Tracking El Niño

    ERIC Educational Resources Information Center

    Ribbe, Joachim

    2016-01-01

    This paper aims to introduce an activity for teachers to assist in meeting learning outcomes as defined in the earth and environmental science units of the Australian Curriculum. The focus of the classroom tasks is on a global ocean feature referred to as El Niño. This phenomenon is part of the El Niño Southern Oscillation, which is largely…

  4. Anodic electrodeposition of NiTSPP from aqueous basic media.

    PubMed

    Pérez-Morales, Marta; Muñoz, Eulogia; Martín-Romero, María T; Camacho, Luis

    2005-06-07

    The oxidative electrodeposition of NiTSPP (tetrakis(4-sulfonatophenyl) Ni porphyrin) on ITO electrode from 0.1 M NaOH aqueous solution has been studied, and UV-visible and reflection FTIR spectroscopies have been used to analyze the composition of such film. By use of UV-vis spectroscopy, small absorbance of the film and an almost nulling effect on the Soret band of the porphyrin along the Ni(III)/Ni(II) redox process were observed. The reflection FTIR spectroscopy detected the presence of Ni-OH groups in the reduced film and as well the state of the porphyrin molecules as radical cation. Moreover, the porphyrin has been quantified by means of the area of the vibration bands assigned to the sulfonate groups by using as reference a Langmuir-Blodgett film containing a known surface concentration of NiTSPP. These results lead us propose the formation of a conductor salt by electrocrystallization, with stoichiometries TSPP/Ni(II)(OH)2 and TSPP/Ni(III)OOH, for its reduced and oxidized forms, respectively. In these two forms, the porphyrin rings will be present as radical cation, which may be stabilized through its dimerization or polymerization.

  5. Porous NiTi surfaces for biomedical applications

    NASA Astrophysics Data System (ADS)

    Huan, Z.; Fratila-Apachitei, L. E.; Apachitei, I.; Duszczyk, J.

    2012-04-01

    In this study, the NiTi shape memory alloy was surface modified by plasma electrolytic oxidation (PEO) in Na3PO4 with the aim to produce porous NiTi surfaces for biomedical applications. The oxidation was performed potentiostatically and the characteristics of the resultant surfaces were compared with those obtained in NaAlO2/NaPO2H2 under similar conditions. Surfaces with sub-micron sized pores could be produced in Na3PO4 electrolyte at 300 V. The process was accompanied by intense gas evolution and enhanced thermal effects relative to the NaAlO2/NaPO2H2 electrolyte. The EDS analyses revealed the presence of O, Ti, P, Ni, and a Ni/Ti atomic ratio of 0.4 suggesting preferential oxidation of titanium during the process and depletion of Ni from the surface. No crystalline oxide phases were detected by X-ray diffraction (XRD). By comparison, the layers formed in NaAlO2/NaPO2H2 consisted of crystalline Al2O3 and the Ni/Ti atomic ratio was 0.74. Following oxidation, the wettability and surface free energy of NiTi increased significantly. The findings of this study indicate that the PEO process shows potential for expanding the biofunctionality of NiTi.

  6. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOEpatents

    Gschneidner, K.A. Jr.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd{sub 0.54}Er{sub 0.46})AlNi alloys having a relatively constant {Delta}Tmc over a wide temperature range. 16 figs.

  7. Synthesis and electrochemical properties of NiO nanospindles

    SciTech Connect

    Zhou, Hai; Lv, Baoliang; Xu, Yao; Wu, Dong

    2014-02-01

    Graphical abstract: NiO nanospindles with a different electrochemical activity as compared to those previous reports were synthesized via an agglomeration–dissolution–recrystallization growth process without the addition of any surfactant. - Highlights: • NiO nanospindles were synthesized without the addition of any surfactant. • The agglomeration–dissolution–recrystallization growth process was used to explain the precursors’ formation process of the spindle-like NiO. • As-obtained spindle-like NiO showed a different electrochemical activity as compared to those previous reports. - Abstract: NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometer in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.

  8. Lanthanide Al-Ni base Ericsson cycle magnetic refrigerants

    DOEpatents

    Gschneidner, Jr., Karl A.; Takeya, Hiroyuki

    1995-10-31

    A magnetic refrigerant for a magnetic refrigerator using the Ericsson thermodynamic cycle comprises DyAlNi and (Gd.sub.0.54 Er.sub.0.46)AlNi alloys having a relatively constant .DELTA.Tmc over a wide temperature range.

  9. The Definition of El Niño.

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.

    1997-12-01

    A review is given of the meaning of the term El Niño and how it has changed in time, so there is no universal single definition. This needs to be recognized for scientific uses, and precision can only be achieved if the particular definition is identified in each use to reduce the possibility of misunderstanding. For quantitative purposes, possible definitions are explored that match the El Niños identified historically after 1950, and it is suggested that an El Niño can be said to occur if 5-month running means of sea surface temperature (SST) anomalies in the Niño 3.4 region (5°N-5°S, 120°-170°W) exceed 0.4°C for 6 months or more. With this definition, El Niños occur 31% of the time and La Niñas (with an equivalent definition) occur 23% of the time. The histogram of Niño 3.4 SST anomalies reveals a bimodal character. An advantage of such a definition is that it allows the beginning, end, duration, and magnitude of each event to be quantified. Most El Niños begin in the northern spring or perhaps summer and peak from November to January in sea surface temperatures.

  10. Spin Seebeck effect through antiferromagnetic NiO

    NASA Astrophysics Data System (ADS)

    Prakash, Arati; Brangham, Jack; Yang, Fengyuan; Heremans, Joseph P.

    2016-07-01

    We report temperature-dependent spin Seebeck measurements on Pt/YIG bilayers and Pt/NiO/YIG trilayers, where YIG (yttrium iron garnet, Y3F e5O12 ) is an insulating ferrimagnet and NiO is an antiferromagnet at low temperatures. The thickness of the NiO layer is varied from 0 to 10 nm. In the Pt/YIG bilayers, the temperature gradient applied to the YIG stimulates dynamic spin injection into the Pt, which generates an inverse spin Hall voltage in the Pt. The presence of a NiO layer dampens the spin injection exponentially with a decay length of 2 ± 0.6 nm at 180 K. The decay length increases with temperature and shows a maximum of 5.5 ± 0.8 nm at 360 K. The temperature dependence of the amplitude of the spin Seebeck signal without NiO shows a broad maximum of 6.5 ± 0.5 μV/K at 20 K. In the presence of NiO, the maximum shifts sharply to higher temperatures, likely correlated to the increase in decay length. This implies that NiO is most transparent to magnon propagation near the paramagnet-antiferromagnet transition. We do not see the enhancement in spin current driven into Pt reported in other papers when 1-2 nm NiO layers are sandwiched between Pt and YIG.

  11. The 50 Ah NiH2 CPV qualification tests

    NASA Technical Reports Server (NTRS)

    Garner, J. C.; Barnes, Wilbert L.; Hickman, Gary L.

    1995-01-01

    In 1992, the Naval Research Laboratory (NRL) started a program to qualify a large diameter common pressure vessel (CPV) nickel-hydrogen (NiH2) batteries for use on future Navy/NRL spacecraft electrical power subsystems. NRL's involvement with the qualification of CPV NiH2 batteries dates back to 1988 when COMSAT and Johnson Controls, Inc. initiated a joint effort to fly the first ever NiH2 CPV in space. A later NRL-JCI cooperative research and development agreement led to the launch of a space experiment in 1993 and to the use of a single NiH2 CPV battery on the BMDO Clementine spacecraft in 1994. NRL initiated procurement of two, 50 Ah CPV NiH2 batteries in the Fall of 1992. The two batteries were delivered to NRL in June 1994. NiH2 CPV batteries have almost 2x the specific energy (Wh/kg) of nickel cadium batteries and 2x the energy density (Wh/l) of individual pressure vessel NiH2 CPV's. This presentation discusses the results of electrical and mechanical qualification tests conducted at NRL. The tests included electrical characterization, standard capacity, random vibration, peak load, and thermal vacuum. The last slides of the presentation show initial results from the life cycle tests of the second NiH2 CPV battery at 40% depth of discharge and a temperature of 10 C.

  12. NiO (bunsenite) is not available to Alyssum species

    USDA-ARS?s Scientific Manuscript database

    Some species of the genus Alyssum are capable of accumulating up to 30 g kg-1 DW Ni in their leaves when grown on serpentine soils where these species are endemic. The unique ability of Alyssum species to hyperaccumulate high concentration of Ni stimulated basic research toward a better understandi...

  13. Phase transformation of NiTi alloys during vacuum sintering

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Kuang

    2017-05-01

    The aim of this study is to ascertain the Phase transformation of NiTi alloys during vacuum sintering. NiTi shape memory alloys (SMA) of atomic ratio 1:1 were prepared through press forming and vacuum sintering with the mixture of Ni and Ti powders. Different samples were prepared by changing the sintering time and the sintering temperature. Phase and porosity of the samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that in the process of sintering NiTi2 and Ni3Ti phases are formed firstly and then transform into NiTi phase. The quantity of NiTi2 and Ni3Ti phases gradually decreased but not eliminate completely with increase of sintering time. The porosity of specimen sintering at 900°C decreases slightly with increase of sintering time. With increase of sintering time the porosity of specimen sintering at 1050°C decreased firstly and then increased because of generation rich titanium liquid in the process of sintering.

  14. A structurally rigid bis(amido) ligand framework in low-coordinate Ni(I), Ni(II), and Ni(III) analogues provides access to a Ni(III) methyl complex via oxidative addition.

    PubMed

    Lipschutz, Michael I; Yang, Xinzheng; Chatterjee, Ruchira; Tilley, T Don

    2013-10-16

    A structurally persistent bis-amido ligand framework capable of supporting nickel compounds in three different oxidation states has been identified. A highly unusual, isolable Ni(III) alkyl species has been prepared and characterized via a rare example of a two-electron oxidative addition of MeI to Ni(I).

  15. Ni-Co oxide formation with Cu assisted method on Ni foam: Unexpected higher areal capacitance of inner layer with naturally formed nanotubes

    NASA Astrophysics Data System (ADS)

    Shi, Diwen; Zhang, Liuyang; Gong, Hao

    2017-09-01

    Ni Foam substrate directly serves as the Ni source for the final Ni-Co oxide product with a Cu assisted chemical method. Especially, after shaking off top layer of Ni-Co oxide grown on Ni Foam, the sample unexpectedly exhibits a greatly enhanced areal capacitance from 4.17 to 11.44 F cm-2 (1 mA cm-2). Finer structures including oxide nanotubes are interestingly found underneath the top layer, which may account for this extraordinary phenomenon.

  16. Using DR52c/Ni(2+) mimotope tetramers to detect Ni(2+) reactive CD4(+) T cells in patients with joint replacement failure.

    PubMed

    Zhang, Yan; Wang, Yang; Anderson, Kirsten; Novikov, Andrey; Liu, Zikou; Pacheco, Karin; Dai, Shaodong

    2017-09-15

    T cell mediated hypersensitivity to nickel (Ni(2+)) is one of the most common causes of allergic contact dermatitis. Ni(2+) sensitization may also contribute to the failure of Ni(2+) containing joint implants, and revision to non-Ni(2+) containing hardware can be costly and debilitating. Previously, we identified Ni(2+) mimotope peptides, which are reactive to a CD4(+) T cell clone, ANi2.3 (Vα1, Vβ17), isolated from a Ni(2+) hypersensitive patient with contact dermatitis. This T cell is restricted to the major histocompatibility complex class II (MHCII) molecule, Human Leukocyte Antigen (HLA)-DR52c (DRA, DRB3*0301). However, it is not known if Ni(2+) induced T cell responses in sensitized joint replacement failure patients are similar to subjects with Ni(2+) induced contact dermatitis. Here, we generated DR52c/Ni(2+) mimotope tetramers, and used them to test if the same Ni(2+) T cell activation mechanism could be generalized to Ni(2+) sensitized patients with associated joint implant failure. We confirmed the specificity of these tetramers by staining of ANi2.3T cell transfectomas. The DR52c/Ni(2+) mimotope tetramer detected Ni(2+) reactive CD4(+) T cells in the peripheral blood mononuclear cells (PBMC) of patients identified as Ni(2+) sensitized by patch testing and a positive Ni(2+) LPT. When HLA-typed by a DR52 specific antibody, three out of four patients were DR52 positive. In one patient, Ni(2+) stimulation induced the expansion of Vβ17 positive CD4(+) T cells from 0.8% to 13.3%. We found that the percentage of DR52 positivity and Vβ17 usage in Ni(2+) sensitized joint failure patients are similar to Ni sensitized skin allergy patients. Ni(2+) independent mimotope tetramers may be a useful tool to identify the Ni(2+) reactive CD4(+) T cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Effects of P/Ni ratio and Ni content on performance of γ-Al2O3-supported nickel phosphides for deoxygenation of methyl laurate to hydrocarbons

    NASA Astrophysics Data System (ADS)

    Zhang, Zhena; Tang, Mingxiao; Chen, Jixiang

    2016-01-01

    γ-Al2O3-supported nickel phosphides (mNi-Pn) were prepared by the TPR method and tested for the deoxygenation of methyl laurate to hydrocarbons. The effects of the P/Ni ratio (n = 1.0-2.5) and Ni content (m = 5-15 wt.%) in the precursors on their structure and performance were investigated. Ni/γ-Al2O3 was also studied for comparison. It was found that the formation of AlPO4 in the precursor inhibited the reduction of phosphate and so the formation of nickel phosphides. With increasing the P/Ni ratio and Ni content, the Ni, Ni3P, Ni12P5 and Ni2P phases orderly formed, accompanying with the increases of their particle size and the amount of weak acid sites (mainly due to P-OH group), while the CO uptake and the amount of medium strong acid sites (mainly related to Ni sites) reached maximum on 10%Ni-P1.5. In the deoxygenation reaction, compared with Ni/γ-Al2O3, the mNi-Pn catalysts showed much lower activities for decarbonylation, Csbnd C hydrogenolysis and methanation due to the ligand and ensemble effects of P. The conversion and the selectivity to n-C11 and n-C12 hydrocarbons achieved maximum on 10%Ni-P 2.0 for the 10%Ni-Pn catalysts and on 8%Ni-P2.0 for the mNi-P2.0 catalysts, while the turnover frequency (TOF) of methyl laurate mainly increased with the P/Ni ratio and Ni content. We propose that TOF was influenced by the nickel phosphide phases, the catalyst acidity and the particle size as well as the synergetic effect between the Ni site and acid site. Again, the hydrodeoxygenation pathway of methyl laurate was promoted with increasing P/Ni ratio and Ni content, ascribed to the phase change in the order of Ni, Ni3P, Ni12P5 and Ni2P in the prepared catalysts.

  18. Creep and Toughness of Cryomilled NiAl Containing Cr

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel; Aikin, Beverly; Salem, Jon

    2000-01-01

    NiAl-AlN + Cr composites were produced by blending cryomilled NiAl powder with approx. 10 vol % Cr flakes. In comparison to the as-consolidated matrices, hot isostatically pressed Cr-modified materials did not demonstrate any significant improvement in toughness. Hot extruded NiAl-AlN+10.5Cr, however, possessed a toughness twice that determine for the base NiAl-AlN alloy. Measurement of the 1200 to 1400 K plastic flow properties revealed that the strength of the composites was completely controlled by the properties of the NiAl-AlN matrices. This behavior could be successfully modeled by the Rule-of-Mixtures, where load is shed from the weak Cr to the strong matrix.

  19. Physical and mechanical metallurgy of NiAl

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D.; Bowman, Randy R.; Nathal, Michael V.

    1994-01-01

    Considerable research has been performed on NiAl over the last decade, with an exponential increase in effort occurring over the last few years. This is due to interest in this material for electronic, catalytic, coating and especially high-temperature structural applications. This report uses this wealth of new information to develop a complete description of the properties and processing of NiAl and NiAl-based materials. Emphasis is placed on the controlling fracture and deformation mechanisms of single and polycrystalline NiAl and its alloys over the entire range of temperatures for which data are available. Creep, fatigue, and environmental resistance of this material are discussed. In addition, issues surrounding alloy design, development of NiAl-based composites, and materials processing are addressed.

  20. Very early warning of next El Niño.

    PubMed

    Ludescher, Josef; Gozolchiani, Avi; Bogachev, Mikhail I; Bunde, Armin; Havlin, Shlomo; Schellnhuber, Hans Joachim

    2014-02-11

    The most important driver of climate variability is the El Niño Southern Oscillation, which can trigger disasters in various parts of the globe. Despite its importance, conventional forecasting is still limited to 6 mo ahead. Recently, we developed an approach based on network analysis, which allows projection of an El Niño event about 1 y ahead. Here we show that our method correctly predicted the absence of El Niño events in 2012 and 2013 and now announce that our approach indicated (in September 2013 already) the return of El Niño in late 2014 with a 3-in-4 likelihood. We also discuss the relevance of the next El Niño to the question of global warming and the present hiatus in the global mean surface temperature.

  1. Magnetic interactions in NiO at ultrahigh pressure

    SciTech Connect

    Potapkin, Vasily; Dubrovinsky, Leonid; Sergueev, I.; Ekholm, M.; Kantor, Innokenty; Bessas, D.; Bykova, E.; Prakapenka, V.; Hermann, Raphael P.; Rueffer, Rudolf; Cerantola, V.; Jonsson, H. J. M.; Olovsson, W.; Mankovsky, S.; Ebert, H.; Abrikosov, I. A.

    2016-05-24

    Here, magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV M ssbauer transition of 61Ni. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to ~24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distorted sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa.

  2. Permeability studies on 3D Ni foam/graphene composites

    NASA Astrophysics Data System (ADS)

    Yang, Zhuxian; Chen, Hongmei; Wang, Nannan; Xia, Yongde; Zhu, Yanqiu

    2017-09-01

    This study investigates the permeability of new 3D Ni foam/graphene composites (Ni foam covered with graphene) using compressed air, Ar and N2 as the probe gases. The results show that the introduction of graphene on the surface of Ni foam via in situ chemical vapour deposition is not detrimental to the permeability of the composites; on the contrary, in some cases it improves permeability. A modified Ergun-type correlation has been proposed, which represents very well the permeability of the Ni foam/graphene composites, especially at flow rates higher than 0.3 m s-1. Further studies show that graphene also helps to improve the thermal conductivity of the composite. These results suggest that the graphene involvement will make the Ni foam/graphene composite a good candidate for potential applications such as filters or heat exchangers suitable for working under harsh conditions such as at high temperatures, in corrosive environments, etc.

  3. Benzimidazole based ratiometric and colourimetric chemosensor for Ni(II)

    NASA Astrophysics Data System (ADS)

    Sarkar, Deblina; Pramanik, Ajoy Kumar; Mondal, Tapan Kumar

    2016-01-01

    A highly sensitive and selective benzimidazole based colourimetric chemosensor (HL) for the efficient detection of Ni2 + has been reported. The synthesized chemosensor HL is highly efficient in detecting Ni2 + over other metal ions that commonly coexist with Ni2 + in physiological and environmental samples. HL also shows distinct color change from orange yellow to blue visible under the naked eye due to specific binding with Ni2 +. This color change corresponds to a large red shift of the UV-Vis spectrum from 403 nm to 600 nm with a distinct isosbestic point at around 500 nm. The cation sensing property of the receptor HL has been examined by UV-Vis spectroscopy. Electronic structure of the HL-Ni2 + complex and sensing mechanism has been interpreted by DFT and TDDFT calculations.

  4. Structural and oxidation properties of CoNi nanowires

    NASA Astrophysics Data System (ADS)

    Aguilera-Granja, Faustino; Montejano-Carrizales, Juan Martin; Vogel, Eugenio E.

    2016-06-01

    Nanocylinders made out of CoNi alloys offer interesting properties which are dependent on the proportion of the constituent elements, the preparation methods and the thermal history of the sample. In the present paper we calculate the structural and electronic properties of Co1- x Ni x alloys at subnanoscopic level. SIESTA program is used to relax the structures following standard protocols. Relative positions of the minority atoms (Ni) are varied aiming to find the lowest energy configurations. It is found that Ni atoms minimize energy at surface positions mainly at the ends of the cylinders. The implications of this result in the magnetic properties of the systems are discussed. The work is continued to study the oxidation properties of the different possible surface compositions. It is found that surfaces of Ni are more resistant to oxidation than Co ones. The combination of the two previous results can lead to cylinders with high magnetic coercivity and relatively high resistance to oxidation.

  5. NiTi superelastic orthodontic archwires with polyamide coating.

    PubMed

    Bravo, L A; de Cabañes, A González; Manero, J M; Rúperez, E; Gil, F Javier

    2014-02-01

    Twenty orthodontic archwires with 55.2% Ni and 44.8% Ti (% weight) were subjected to a dipping treatment to coat the NiTi surface by a polyamide polymer. It has been selected a Polyamide 11 due to its remarkable long lasting performance. The transformation temperatures as well as the transformation stresses of the NiTi alloy were determined in order to know whether the coating process can alter its properties. The adhesive wear tests have been demonstrated that the wear rates as well as the dynamic friction coefficients μ of polymer coated wires are much lower than metallic wires. The corrosion studies have shown that the use of this polymer, as coating, seals the NiTi surface to prevent corrosion and the release of nickel ions. The average decrease of Ni ions release due to this coating is around 85%.

  6. Nanocrystalline NiAl Coating Prepared by HVOF Thermal Spraying

    NASA Astrophysics Data System (ADS)

    Enayati, M. H.; Karimzadeh, F.; Tavoosi, M.; Movahedi, B.; Tahvilian, A.

    2011-03-01

    Nanocrystalline NiAl intermetallic powder was prepared by mechanical alloying (MA) of Ni50Al50 powder mixture and then deposited on low carbon steel substrates by high velocity oxy fuel (HVOF) thermal spray technique using two sets of spraying parameters. X-ray diffraction (XRD), scanning electron microscopy (SEM), transition electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness test were used to characterize the prepared powders and coatings. The MA of Ni50Al50 powder mixture led to the formation of NiAl intermetallic compound. The resulting powder particles were three dimensional in nature with irregular morphology and a crystallite size of ~10 nm. This powder was thermally sprayed by HVOF technique to produce coating. The deposited coating had a nanocrystalline structure with low oxide and porosity contents. The hardness of coatings was in the range of 5.40-6.08 GPa, which is higher than that obtained for NiAl coating deposited using conventional powders.

  7. Structure and function of [NiFe] hydrogenases.

    PubMed

    Ogata, Hideaki; Lubitz, Wolfgang; Higuchi, Yoshiki

    2016-11-01

    Hydrogenases catalyze the reversible conversion of molecular hydrogen to protons and electrons via a heterolytic splitting mechanism. The active sites of [NiFe] hydrogenases comprise a dinuclear Ni-Fe center carrying CO and CN(-) ligands. The catalytic activity of the standard (O2-sensitive) [NiFe] hydrogenases vanishes under aerobic conditions. The O2-tolerant [NiFe] hydrogenases can sustain H2 oxidation activity under atmospheric conditions. These hydrogenases have very similar active site structures that change the ligand sphere during the activation/catalytic process. An important structural difference between these hydrogenases has been found for the proximal iron-sulphur cluster located in the vicinity of the active site. This unprecedented [4Fe-3S]-6Cys cluster can supply two electrons, which lead to rapid recovery of the O2 inactivation, to the [NiFe] active site.

  8. Benzimidazole based ratiometric and colourimetric chemosensor for Ni(II).

    PubMed

    Sarkar, Deblina; Pramanik, Ajoy Kumar; Mondal, Tapan Kumar

    2016-01-15

    A highly sensitive and selective benzimidazole based colourimetric chemosensor (HL) for the efficient detection of Ni(2+) has been reported. The synthesized chemosensor HL is highly efficient in detecting Ni(2+) over other metal ions that commonly coexist with Ni(2+) in physiological and environmental samples. HL also shows distinct color change from orange yellow to blue visible under the naked eye due to specific binding with Ni(2+). This color change corresponds to a large red shift of the UV-Vis spectrum from 403 nm to 600 nm with a distinct isosbestic point at around 500 nm. The cation sensing property of the receptor HL has been examined by UV-Vis spectroscopy. Electronic structure of the HL-Ni(2+) complex and sensing mechanism has been interpreted by DFT and TDDFT calculations.

  9. Deoxyribonucleic acid (DNA)-Ni-nanostrands composites for EMI shielding

    NASA Astrophysics Data System (ADS)

    Ouchen, Fahima; Wilson, Benjamin G.; Yaney, Perry P.; Salour, Michael M.; Grote, James G.

    2016-09-01

    In this study, we demonstrated the use of DNA-CTMA (DC) in combination with Nickel Nanostrands (NiNs) for application in Electromagnetic Interference (EMI) shielding. The addition of NiNs fillers to DC led to films with higher shielding effectiveness (SE) than when Silver nanoparticles were used. An enhanced EMI shielding effectiveness (SE) was also achieved by the fabrication of the DC-NiNs shielding film structure in a layered architecture. Very thin layer of Guanine ( 60 nm) were inserted between layers of DNA-NiNs ( 100um each) to total a thickness of 500um of the shielding film. An increase of the SE by 6-8 dB for the layered structure as compared to the bulk thick film with NiNs loadings up to 10 wt%. At higher loadings (>10 wt. %), a significant physical degradation of the films was observed for all films regardless of the thickness or the process of fabrication.

  10. Spinodal Decomposition of Ni-Nb-Y metallic Glasses

    SciTech Connect

    Mattern, Norbert; G, Goerigk; Vainio, U; Miller, Michael K; Gemming, T; Eckert, J

    2009-01-01

    Phase-separated Ni-Nb-Y metallic glasses were prepared by rapid quenching from the melt. The early stages of decomposition were characterized in Ni-Nb-Y alloys with Ni contents of more than 60 at.%. Strongly correlated chemical fluctuations with a nanometer length scale were found to exist in the as-quenched state. The observed fluctuation lengths range from 5 to 12 nm, depending on the actual composition of the glass. The 'frozen-in' early stages of decomposition occur in the deeply undercooled melt due to the reduction in the critical temperature of liquid-liquid phase separation with Ni content. Annealing of the phase-separated Ni{sub 70}Nb{sub 15}Y{sub 15} glass below the crystallization temperature leads to an increase in the amplitude of the fluctuations. However, the wavelength was unchanged, which provides evidence for the spinodal character of the decomposition.

  11. High temperature dispersion strengthening of NiAl

    NASA Technical Reports Server (NTRS)

    Sherman, M.; Vedula, K.

    1986-01-01

    A potential high temperature strengthening mechanism for alloys based on the intermetallic compound NiAl was investigated. This study forms part of an overall program at NASA Lewis Research Center for exploring the potential of alloys based on NiAl for high temperature applications. An alloy containing 2.26 at% Nb and produced by hot extrusion of blended powders was examined in detail using optical and electron microscopy. Interdiffusion between the blended Nb and NiAl powders results in the formation of intermediate phases. A fine dispersion of precipitates of a hexagonal, ordered NiAlNb phases in a matrix of NiAl can be produced and this results in strengthening of the alloy by interfering with dislocation motion at high temperature. These precipitates are, however, found to coarsen during the high temperature (1300 K) deformation at slow strain rates and this may impose some limitatioins on the use of this strengthening mechanism.

  12. Magnetic interactions in NiO at ultrahigh pressure

    DOE PAGES

    Potapkin, Vasily; Dubrovinsky, Leonid; Sergueev, I.; ...

    2016-05-24

    Here, magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV M ssbauer transition of 61Ni. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to ~24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distortedmore » sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa.« less

  13. Magnetic interactions in NiO at ultrahigh pressure

    SciTech Connect

    Potapkin, Vasily; Dubrovinsky, Leonid; Sergueev, I.; Ekholm, M.; Kantor, Innokenty; Bessas, D.; Bykova, E.; Prakapenka, V.; Hermann, Raphael P.; Rueffer, Rudolf; Cerantola, V.; Jonsson, H. J. M.; Olovsson, W.; Mankovsky, S.; Ebert, H.; Abrikosov, I. A.

    2016-05-24

    Here, magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV M ssbauer transition of 61Ni. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to ~24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distorted sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa.

  14. Microwave absorption properties of Ni/(C, silicides) nanocapsules

    PubMed Central

    2012-01-01

    The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the ‘core/shell’ interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon. PMID:22548846

  15. Photosensitivity of the Ni-n-GaAs Schottky barriers

    SciTech Connect

    Melebaev, D.; Melebaeva, G. D.; Rud', V. Yu. Rud', Yu. V.

    2009-01-15

    The method of chemical deposition is used to form the structures with the Ni-n-GaAs Schottky barrier. The thickness of the Ni layers with a specular outer surface was varied within the range of 150-220 A. It was experimentally observed for the first time that photosensitivity of the obtained barriers with the semitransparent Ni layers illuminated is practically absent in the Fowler region of the spectrum at hv = 0.9-1.5 eV. This circumstance is related mainly to the fact that, in this case, the Ni layer side of the structure was illuminated, and radiation with the photon energy hv < 1.3 eV was effectively reflected from the nickel surface. It is established that the developed Ni-n-GaAs structures can be used as high-efficiency wide-band photoconverters of both visible and ultraviolet radiation.

  16. Effect of polarity on Ni/InN interfacial reactions

    SciTech Connect

    Kragh-Buetow, K. C.; Weng, X.; Readinger, E. D.; Wraback, M.; Mohney, S. E.

    2013-01-14

    Ni films on (0001) and (0001) InN exhibited different reaction kinetics upon annealing at 673K. Structural and chemical analysis using grazing incidence X-ray diffraction, transmission electron microscopy, and X-ray energy dispersive spectrometry indicated that an interfacial reaction did not occur between the Ni film and the In-polar (0001) InN layer. However, the N-polar face reacted with Ni to form the Ni{sub 3}InN{sub x} ternary phase with an anti-perovskite structure. The difference in reactivity for Ni on In-face and N-face InN indicates that polarity alters the reaction and may also affect interactions between other metals and group III-nitride semiconductors.

  17. Evolution of Ni3X Precipitation Kinetics, Morphology and Spatial Correlations in Binary Ni-X Alloys Aged Under Externally Applied Stress

    SciTech Connect

    Ardell, Alan J

    2006-02-07

    Coarsening of Ni3Al, Ni3Ga, Ni3Ge and Ni3Si precipitates in aged binary single-crystal Ni-Al, Ni-Ga, Ni-Ge and Ni-Si alloys under applied compressive stress was measured experimentally over the temperature range 600 to 700 °C. Experiments were also performed on binary Ni-Al single crystals deformed in tension at 640°C. The orientation of the crystals was [100] in all the experiments. Compared to the kinetics of coarsening in unstressed alloys, coarsening was slightly slower in specimens aged under compression and slightly faster in specimens aged in tension. The effect of applied stress on morphology and spatial correlation was also measured and found to be small. Ni3Al precipitates of a given size generally tended to become more non-equiaxed and their interfaces more planar, with increasing compressive stress. Ni3Ge precipitates behaved differently, becoming more spherical in specimens aged under compression. The effect of applied stress on kinetics is attributed to the influence of elastic deformation on diffusion. A model was developed that predicts slightly slower diffusion under compression and slightly faster diffusion in tension. The elastic constants of single crystals of Ni-Al, Ni-Si, Ni-Ga and Ni-Ge solid solutions were measured from room temperature to about 1100 K using resonant ultrasound spectroscopy.

  18. Supercapacitor studies on Ni/NiO nanocomposites synthesized by humble sol-gel route with variation of Ni2+: CA ratio

    NASA Astrophysics Data System (ADS)

    Das, Himadri Tanaya; Elumulai, P.

    2017-05-01

    The Ni/NiO nanocomposites were prepared by citrate-assisted humble sol-gel method with key variation of metal nitrate and citric acid. A series of samples were obtained and characterized by X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscope (SEM) and UV-VIS spectroscopy. All samples were tested by cyclic voltammetry (CV) and galvanostatic charge-discharge studies. Excitingly, the Ni/ NiO composite resulted from 1:1 ratio exhibited a highest specific capacitance of 350 F g-1 at 0.5 Ag-1 with excellent stability and coulombic efficiency. This investigation has opened a wide window for exploring other transition metal-oxides systems, such that potential nanocomposites can be generated for energy storage applications.

  19. Hydrides of CeNi/sub 5/, MmNi/sub 5/, Ca/sub 0/ /sub 2/(Ce/sub 0/ /sub 65/Mm/sub 0/ /sub 35/)/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Ce/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Mm/sub 0/ /sub 8/Ni/sub 5/, and mixed CeNi/sub 5//MmNi/sub 5/

    SciTech Connect

    Lakner, J.F.; Chow, T.S.

    1982-09-01

    Six intermetallic alloys (CeNi/sub 5/, MmNi/sub 5/, Ca/sub 0/ /sub 2/(Ce/sub 0/ /sub 65/Mm/sub 0/ /sub 35/)/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Ce/sub 0/ /sub 8/Ni/sub 5/, Ca/sub 0/ /sub 2/Mm/sub 0/ /sub 8/Ni/sub 5/, and a mixed alloy, CeNi/sub 5//MmNi/sub 5/) were investigated with respect to their suitability to provide high hydrogen capacity and their potential for use in providing substantial hydrogen pressure at both low and high temperatures. A second phase of our investigation dealt with ball-milling and hydriding and dehydriding cycles to produce fine particles for use in hydride powder transfer studies. A summary of several Van't Hoff plots is also included for hydride-forming alloys.

  20. First-principles study of Ni-Al intermetallic compounds under various temperature and pressure

    NASA Astrophysics Data System (ADS)

    Wen, Zhiqin; Zhao, Yuhong; Hou, Hua; Tian, Jinzhong; Han, Peide

    2017-03-01

    The pressure dependence behaviors of structural and mechanical properties as well as the effect of temperature on thermodynamic properties of Ni-Al ordered intermetallic compounds (i. e. Ni3Al, Ni5Al3, NiAl, Ni2Al3 and NiAl3) are investigated in details by implementing first-principles calculations. The calculated lattice parameters, bulk modulus and its pressure derivative are well in agreement with available experimental and theoretical values at zero pressure. All the compounds are mechanically stable with pressure going up to 50 GPa, and the volume change resistance of nickel aluminum alloys can be improved by increasing pressure and Ni concentration. The shear deformation resistance, elastic stiffness and microhardness of nickel aluminum alloys can be strengthened by increasing the content of Ni5Al3 and Ni2Al3, and pressure can also enhance these properties of Ni5Al3, NiAl and Ni2Al3. The ductility of Ni3Al, Ni5Al3 and NiAl can be improved by increasing pressure, while brittle nature turns into ductile nature in 20-30 GPa and 10-20 GPa for Ni2Al3 and NiAl3, respectively. Furthermore, the elastic anisotropy of Ni3Al, Ni5Al3, Ni2Al3 and NiAl3 enhances with pressure, while NiAl shows few change with pressure increasing. In addition, Ni3Al is the most sensitive to pressure change among considered compounds. Finally, the Debye temperature, linear thermal expansion coefficient and heat capacity of these compounds are calculated using the quasi-harmonic Debye model in pressure ranging from 0 to 50 GPa and temperature ranging from 0 to 1200 K to elucidate the relationships between thermodynamic parameters and temperature under various pressure. The results are helpful insights into the study of nickel aluminum alloys.

  1. Synthesis and cyclic oxidation behavior of a (Ni, Pt) Al coating on a desulfurized Ni-base superalloy

    SciTech Connect

    Zhang, Y.; Lee, W.Y.; Haynes, J.A.; Wright, I.G.; Pint, B.A.; Cooley, K.M.; Liaw, P.K.

    1999-10-01

    The influences of sulfur impurities and Pt incorporation on the scale adhesion behavior of aluminide coatings were studied and compared. Low-sulfur NiAl coatings were prepared on a desulfurized, yttrium-free, single-crystal Ni-based superalloy by a modified version of a conventional aluminizing procedure based on chemical vapor deposition. The sulfur level in the resulting NiAl coatings was measured to be less than {approximately}0.5 ppmw by glow-discharge mass spectroscopy. Platinum-modified aluminide coatings were synthesized by first electroplating a thin layer of Pt({approximately}7 {micro}m) on the superalloy, followed by the same low-sulfur aluminizing procedure. The measured sulfur content in the (Ni,Pt)Al coating was substantially higher than that of the low-sulfur NiAl coating due to contamination during the Pt electroplating process. A very adherent {alpha}-Al{sub 2}O{sub 3} scale formed on the grain surfaces of the low-sulfur NiAl coating during cyclic oxidation testing at 1,150 C, but scale spallation eventually occurred over many of the NiAl grain boundaries. In contrast, despite the higher level of sulfur in the (NI,Pt)Al coating, a very adherent scale was formed over both the coating grain surfaces and grain boundaries during thermal cycling. These results suggest that Pt additions can mitigate the detrimental influence of sulfur on scale adhesion.

  2. Grain boundary character distribution of CuNiSi and FeNi alloys processed by severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Azzeddine, H.; Baudin, T.; Helbert, A. L.; Brisset, F.; Larbi, F. Hadj; Tirsatine, K.; Kawasaki, M.; Bradai, D.; Langdon, T. G.

    2015-04-01

    In this work the Grain Boundary Character Distribution (GBCD) in general and the relative proportion of low-Σ CSL (Coincidence Site Lattice) grain boundaries are determined through EBSD in Cu-2.5Ni-0.6Si (wt.%) and Fe-36Ni (wt.%) alloys after processing by high-pressure torsion, equal- channel angular pressing and accumulative roll bonding.

  3. Effect of mono- and bimetallic nanoparticles Fe, Ni, & Fe/Ni based on carbon nanocomposites on electrocatalytic properties of anodes

    NASA Astrophysics Data System (ADS)

    Ranabhat, K.; Pylinina, A. I.; Skripkin, K. S.; Sofronova, E. A.; Revina, A. A.; Kasatkin, V. E.; Patrikeev, L. N.; Lapshinsky, V. A.

    2016-10-01

    The optical properties of metallic Fe nanoparticles (NPs), Ni NPs and bimetallic Fe/Ni NPs produced under radiolysis in anaerobic condition based on a chemical reduction in the presence of oxygen and quercetin in reversed micellar solutions, and electrokinetic properties of nanoparticles carbon-based nanocomposites were studied. The possibility of the preparation of coating using different nanocomposites with anomalous electrocatalytic is addressed.

  4. Effect of NiO inserted layer on spin-Hall magnetoresistance in Pt/NiO/YIG heterostructures

    SciTech Connect

    Shang, T.; Zhan, Q. F. Yang, H. L.; Zuo, Z. H.; Xie, Y. L.; Liu, L. P.; Zhang, S. L.; Zhang, Y.; Li, H. H.; Wang, B. M.; Li, Run-Wei; Wu, Y. H.; Zhang, S.

    2016-07-18

    We investigate spin-current transport with an antiferromagnetic insulator NiO thin layer by means of the spin-Hall magnetoresistance (SMR) over a wide range of temperature in Pt/NiO/Y{sub 3}Fe{sub 5}O{sub 12} (Pt/NiO/YIG) heterostructures. The SMR signal is comparable to that without the NiO layer as long as the temperature is near or above the blocking temperature of the NiO, indicating that the magnetic fluctuation of the insulating NiO is essential for transmitting the spin current from the Pt to YIG layer. On the other hand, the SMR signal becomes negligibly small at low temperature, and both conventional anisotropic magnetoresistance and the anomalous Hall resistance are extremely small at any temperature, implying that the insertion of the NiO has completely suppressed the Pt magnetization induced by the YIG magnetic proximity effect (MPE). The dual roles of the thin NiO layer are, to suppress the magnetic interaction or MPE between Pt and YIG, and to maintain efficient spin current transmission at high temperature.

  5. Amorphous Ni-B alloy nanoparticle film on Ni foam: rapid alternately dipping deposition for efficient overall water splitting

    NASA Astrophysics Data System (ADS)

    Liang, Yanhui; Sun, Xuping; Asiri, Abdullah M.; He, Yuquan

    2016-03-01

    It is highly attractive, but still remains challenging, to develop noble metal-free bifunctional electrocatalysts efficient for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media. In this letter, we describe the rapid electroless deposition of amorphous Ni-B nanoparticle film on Ni foam (Ni-B/Ni foam) by alternative dipping of Ni foam into Ni precursor and reducing solutions. This Ni-B/Ni foam acts as an efficient and durable 3D catalytic electrode for water splitting, affording 100 mA cm-2 at 360 mV overpotential for the OER and 20 mA cm-2 at 125 mV overpotential for the HER in 1.0 M KOH, and its two-electrode electrolyzer demands a cell voltage of 1.69 V to afford 15 mA cm-2 water-splitting current. Moreover, the catalyst loading can be easily tuned and this alternately dipping deposition technique works universally for other conductive substrates.

  6. Effects of Cr and Ni on Interdiffusion and Reaction between U and Fe-Cr-Ni Alloys

    SciTech Connect

    K. Huang; Y. Park; L. Zhou; K.R. Coffey; Y.H. Sohn; B.H. Sencer; J. R. Kennedy

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe–15 wt.%Cr or Fe–15 wt.%Cr–15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe–Cr–Ni exhibited a similar temperature dependence, while the U vs. Fe–Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases – lower growth rate at lower temperature but higher growth rate at higher temperature.

  7. Electromagnetic properties of Fe53Ni47 and Fe53Ni47/Cu granular composite materials in the microwave range

    NASA Astrophysics Data System (ADS)

    Massango, Herieta; Tsutaoka, Takanori; Kasagi, Teruhiro

    2016-09-01

    The electromagnetic proprieties of Fe53Ni47 granular composite materials and Fe53Ni47/Cu hybrid granular composites have been studied by measuring the relative complex permeability and permittivity spectra as well as the ac electrical conductivity. In the Fe53Ni47 composite, the variation of the ac conductivity at 1 kHz with the particle volume content shows an insulator-metal transition at the percolation threshold at 61 vol% particle content. A negative permeability spectrum due to the magnetic resonance in Fe53Ni47 particles was observed in the 85 vol% composite. Meanwhile, the negative permittivity spectrum caused by the plasmoinc state of the percolated Fe53Ni47 particle clusters appears at 90 vol%. The Fe53Ni47/Cu hybrid composite containing 85 vol% of Fe53Ni47/Cu hybrid particle as filers shows the percolative metallic properties; the ac conductivity increases with increasing the Cu particle volume fraction in the Fe53Ni47/Cu particle system. The negative permittivity spectrum appears above the Cu particle volume fraction of 0.16; the double negative characteristic was observed at that of 0.20 and 0.24 hybrid composites in the frequency range from 300 MHz to 1.8 GHz in the absence of the external magnetic field.

  8. Controlled synthesis of mesoporous β-Ni(OH){sub 2} and NiO nanospheres with enhanced electrochemical performance

    SciTech Connect

    Xing, Shengtao; Wang, Qian; Ma, Zichuan; Wu, Yinsu; Gao, Yuanzhe

    2012-09-15

    Highlights: ► Uniform mesoporous β-Ni(OH){sub 2} and NiO nanospheres with hierarchical structures were synthesized by a simple complexation–precipitation method. ► Both ammonia and citrate played an important role for the formation of mesoporous nanospheres. ► β-Ni(OH){sub 2} and NiO nanospheres showed excellent capacitive properties due to their mesoporous structures and larger surface areas. -- Abstract: Uniform mesoporous β-Ni(OH){sub 2} and NiO nanospheres with hierarchical structures were synthesized by a facile complexation–precipitation method. The effects of ammonia and citrate on the structure and morphology of the products were thoroughly investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption measurements. The results indicated that ammonia played an important role for the formation of flowerlike spheres assembled from nanosheets. The addition of citrate could remarkably reduce the particle sizes and increase the specific surface areas of flowerlike spheres. A possible formation mechanism based on the experimental results was proposed to understand their growing procedures. β-Ni(OH){sub 2} and NiO nanospheres prepared with the addition of citrate showed excellent capacitive properties due to their mesoporous structures and large surface areas, suggesting the importance of controlled synthesis of hierarchical nanostructures for their applications.

  9. Effects of Cr and Ni on interdiffusion and reaction between U and Fe-Cr-Ni alloys

    NASA Astrophysics Data System (ADS)

    Huang, K.; Park, Y.; Zhou, L.; Coffey, K. R.; Sohn, Y. H.; Sencer, B. H.; Kennedy, J. R.

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe-15 wt.%Cr or Fe-15 wt.%Cr-15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe-Cr-Ni exhibited a similar temperature dependence, while the U vs. Fe-Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases - lower growth rate at lower temperature but higher growth rate at higher temperature.

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

    USDA-ARS?s Scientific Manuscript database

    The occurrence of nickel (Ni) deficiency of pecan [Carya illinoinensis (Wangenh.) K. Koch] in orchards is an increasingly common problem. There is uncertainty regarding the primary cause of the problem, as orchard soils have plenty of Ni. The influence of essential micronutrients on the endogenous...

  11. Effects of Ni content on nanocrystalline Fe-Co-Ni ternary alloys synthesized by a chemical reduction method

    NASA Astrophysics Data System (ADS)

    Chokprasombat, Komkrich; Pinitsoontorn, Supree; Maensiri, Santi

    2016-05-01

    Magnetic properties of Fe-Co-Ni ternary alloys could be altered by changing of the particle size, elemental compositions, and crystalline structures. In this work, Fe50Co50-xNix nanoparticles (x=10, 20, 40, and 50) were prepared by the novel chemical reduction process. Hydrazine monohydrate was used as a reducing agent under the concentrated basic condition with the presence of poly(vinylpyrrolidone). We found that the nanoparticles were composed of Fe, Co and Ni with compositions according to the molar ratio of the metal sources. Interestingly, the particles were well-crystalline at the as-prepared state without post-annealing at high temperature. Increasing Ni content resulted in phase transformation from body centered cubic (bcc) to face centered cubic (fcc). For the fcc phase, the average particle size decreased when increased the Ni content; the Fe50Ni50 nanoparticles had the smallest average size with the narrowest size distribution. In additions, the particles exhibited ferromagnetic properties at room temperature with the coercivities higher than 300 Oe, and the saturation magnetiation decreased with increasing Ni content. These results suggest that the structural and magnetic properties of Fe-Co-Ni alloys could be adjusted by varying the Ni content.

  12. Static atomic displacements of Sn in disordered NiAs/Ni 2In type HT-Ni 1+ δSn

    NASA Astrophysics Data System (ADS)

    Leineweber, A.; Oeckler, O.; Zachwieja, U.

    2004-03-01

    The crystal structures of the intermediate solid solution HT (high temperature) Ni 1+ δSn with δ=0.28, 0.52 and 0.61 (refined Ni contents) have been analyzed in detail by X-ray diffraction on single crystals. The previously reported basic atomic arrangement, i.e., a NiAs/Ni 2In structure type ( P6 3/ mmc, Ni(1) on 2 a, 0 0 0, Ni(2) with an occupancy δ on 2 d, {2}/{3} {1}/{3} {1}/{4}, and Sn on 2 c, {1}/{3} {2}/{3} {1}/{4}), is confirmed. However, strong anisotropic atomic displacements occur for Sn within the a- b plane of the hexagonal unit cell, which require a Gram-Charlier expansion of the probability density function of Sn in order to obtain a good fit to the diffraction data. Direction, magnitude and the concentration dependence of the displacements can be interpreted in terms of the geometrical requirements of the different local atomic configurations in the planes z=±1/4, so that the displacements can be identified as static ones.

  13. Reinspecting two types of El Niño: a new pair of Niño indices for improving real-time ENSO monitoring

    NASA Astrophysics Data System (ADS)

    Hu, Chundi; Yang, Song; Wu, Qigang; Zhang, Tuantan; Zhang, Chengyang; Li, Yana; Deng, Kaiqiang; Wang, Teng; Chen, Junwen

    2016-12-01

    This study reinspects the dominant modes of different types of El Niño from the perspectives of monthly mean and seasonality using a combined technique referred as RC-REOF. Several features have been revealed. (1) The explained variances of eastern Pacific (EP) El Niño and central Pacific (CP) El Niño are comparable, in the ranges of 33-43 and 23-28 %, respectively. (2) This feature is more in line with the frequent occurrence of CP El Niño compared to the result from orthogonal EOF analysis in which El Niño Modoki explains a smaller variance of 11-12 %. (3) Both special patterns of EP El Niño and CP El Niño are of equatorial asymmetry that is often overlooked previously by the traditional Niño indices. Based on the features captured by the two leading RC-REOF modes, the authors propose a new pair of Niño indices referred to as Niño3b and Niño4b that have the following advantages: (1) simple calculation, (2) robust and stable relationship with the EP/CP El Niño modes, (3) more representative for Pacific decadal signals, (4) easier to distinguish ENSO types, and (5) without restriction by orthogonality, and others. The Niño3b and Niño4b indices are potentially useful for both scientific research and real-time monitoring of the two types of El Niño. Besides, an index namely Niño3.4b is also introduced to describe the hybrid ENSO events, with relatively equal covariance to EP El Niño and CP El Niño and with larger covariance at decadal time scale than index Niño3.4.

  14. Nucleation and Growth of Tetrataenite (FeNi) in Meteorites

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Williams, D. B.; Zhang, J.

    1992-07-01

    The mineral tetrataenite (ordered FeNi) has been observed in chondrites, stony irons, and iron meteorites (1). FeNi is an equilibrium phase in the Fe-Ni phase diagram (Figure 1) and orders to tetrataenite at ~320 degrees C (2). The phase forms at temperatures at or below the eutectoid temperature (~400 degrees C) where taenite (gamma) transforms to kamacite (alpha) plus FeNi (gamma"). An understanding of the formation of tetrataenite can lead to a new method for determining cooling rates at low temperatures (<400 degrees C) for all types of meteorites. In a recent study of plessite in iron meteorites (3), two transformation sequences for the formation of tetrataenite were observed. In either sequence, during the cooling process, the taenite (gamma) phase initially undergoes a diffusionless transformation to a martensite (alpha, bcc) phase without a composition change. The martensite then decomposes either above or below the eutectoid temperature (~400 degrees C) during cooling or upon subsequent reheating. During martensite decomposition above the eutectoid, the taenite (gamma) phase nucleates by the reaction alpha(sub)2 ---> alpha + gamma and grows under volume diffusion control. The Ni composition of the taenite increases continuously following the equilibrium gamma/alpha + gamma boundary while the Ni composition of the kamacite matrix decreases following the alpha/alpha + gamma phase boundary (2), see Figure 1. Below the eutectoid temperature, the precipitate composition follows the equilibrium gamma"/alpha + gamma" boundary and reaches ~52 wt% Ni, the composition of FeNi, gamma". The kamacite (alpha) matrix composition approaches ~4 to 5 wt% Ni. The ordering transformation starts at ~320 degrees C forming the tetrataenite phase. During martensite decomposition below the eutectoid temperature, FeNi should form directly by the reaction alpha2 --> alpha + gamma" (FeNi). If this transformation sequence occurs, then the composition of kamacite and tetrataenite

  15. Characterization and leaching of NiCd and NiMH spent batteries for the recovery of metals.

    PubMed

    Pietrelli, L; Bellomo, B; Fontana, D; Montereali, M

    2005-01-01

    Since NiMH and NiCd batteries are still used in the electronic devices market, a treatment and recycling plant has many advantages both from the environmental and the economic points of view. Unfortunately, there is no relationship between shape, size and chemical composition of spent batteries, consequently the characterization and the leaching method of the starting material becomes an important step of the overall treatment process in choosing the best conditions for the selective separation of the metals by hydrometallurgy. Leaching at 20 degrees C with H(2)SO(4) 2M for about 2h seems to be a good solution in terms of cost and efficiency for both battery types. The hydroxide compounds can be readily leached while Ni present as metallic form requires more aggressive conditions due to kinetic constraints. In this paper, the characterization of NiMH and NiCd spent batteries and the results of leaching tests in different conditions are reported.

  16. Enhanced Dry Reforming of Methane on Ni and Ni-Pt Catalysts Synthesized by Atomic Layer Deposition

    SciTech Connect

    Gould, Troy D.; Montemore, Matthew M.; Lubers, Alia M.; Ellis, Lucas D.; Weimer, Alan; Falconer, John L.; Medlin, James W.

    2015-02-25

    Atomic layer deposition (ALD) was used to deposit Ni and Pt on alumina supports to form monometallic and bimetallic catalysts with initial particle sizes of 1–2.4 nm. The ALD catalysts were more active (per mass of metal) than catalysts prepared by incipient wetness (IW) for dry reforming of methane (DRM), and they did not form carbon whiskers during reaction due to their sufficiently small size. Catalysts modified by Pt ALD had higher rates of reaction per mass of metal and inhibited coking, whereas NiPt catalysts synthesized by IW still formed carbon whiskers. Temperature-programmed reduction of Ni catalysts modified by Pt ALD indicated the presence of bimetallic interaction. Density functional theory calculations suggested that under reaction conditions, the NiPt surfaces form Ni-terminated surfaces that are associated with higher DRM rates (due to their C and O adsorption energies, as well as the CO formation and CH4 dissociation energies).

  17. Embedded Atom Method Potential for Ni-Cu Alloys and Its Applications for Ni, Cu growth on Cu(111)

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2012-02-01

    We developed a semi-empirical, many-body type model potential to investigate static and dynamic properties of Ni-Cu alloys. The formalism is based on the embedded atom method with improved optimization techniques. The Ni-Cu alloy potential was determined by fitting to data on lattice parameters, cohesive energies for L10, L11, L12, and L13 phases, together with vacancy formation energies, bulk modulus and elastic properties for L12, L13 phases. Our preliminary calculations for energy barriers for the diffusing Ni and Cu atoms on Cu(111) based on the nudged elastic band method are found to be consistent with the available experimental and other theoretical results. Our ultimate goal is to describe the varying characteristics in growing islands of pure Cu, Ni atoms and mixed Ni-Cu combinations on Cu(111) [S. Pons et al., Surf. Sci., 511, 449, (2002)].

  18. Shape memory behavior of single crystal and polycrystalline Ni-rich NiTiHf high temperature shape memory alloys

    NASA Astrophysics Data System (ADS)

    Saghaian, Sayed M.

    NiTiHf shape memory alloys have been receiving considerable attention for high temperature and high strength applications since they could have transformation temperatures above 100 °C, shape memory effect under high stress (above 500 MPa) and superelasticity at high temperatures. Moreover, their shape memory properties can be tailored by microstructural engineering. However, NiTiHf alloys have some drawbacks such as low ductility and high work hardening in stress induced martensite transformation region. In order to overcome these limitations, studies have been focused on microstructural engineering by aging, alloying and processing. Shape memory properties and microstructure of four Ni-rich NiTiHf alloys (Ni50.3Ti29.7Hf20, Ni50.7Ti 29.3Hf20, 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. The effects of the heat treatments on the transformation characteristics and microstructure of the Ni-rich NiTiHf shape memory alloys have been investigated. Transformation temperatures are found to be highly annealing temperature dependent. Generation of nanosize precipitates (˜20 nm in size) after three hours aging at 450 °C and 550 °C improved the strength of the material, resulting in a near perfect dimensional stability under high stress levels (> 1500 MPa) with a work output of 20-30 J cm- 3. Superelastic behavior with 4% recoverable strain was demonstrated at low and high temperatures where stress could reach to a maximum value of more than 2 GPa after three hours aging at 450 and 550 °C for alloys with Ni great than 50.3 at. %. Shape memory properties of polycrystalline Ni50.3Ti29.7 Hf20 alloys were studied via

  19. Electrochemical kinetic performances of electroplating Co-Ni on La-Mg-Ni-based hydrogen storage alloys

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Tao, Yang; Ke, Dandan; Ma, Yufei; Han, Shumin

    2015-12-01

    Electroplating Co-Ni treatment was applied to the surface of the La0.75Mg0.25Ni3.48 alloy electrodes in order to improve the electrochemical and kinetic performances. The Scanning electron microscope-Energy dispersive spectroscopy and X-ray diffraction results showed that the electrodes were plated with a homogeneous Co-Ni alloy film. The alloy coating significantly improved the high rate dischargeability of the alloy electrode, and the HRD value increased to 57.5% at discharge current density 1875 mA/g after the Co-Ni-coating. The exchange current density I0, the limiting current density IL and the oxidation peak current also increased for the coated alloy. The improvement of overall electrode performances was attributed to an enhancement in electro-catalytic activity and conductivity at the alloy surface, owing to the precipitation of the Co-Ni layer.

  20. High coercive field and magnetization reversal in core-shell cum nanotwin driven Ni/NiO nanospheres.

    PubMed

    Okram, Gunadhor S; Soni, Ajay; Adroja, D T; Lalla, N P; Shripathi, T

    2011-03-01

    We report here nanotwin-core-shell Ni(core)NiO(shell) spheres of average size 25 nm prepared through polyol method. They exhibit high coercive field at 2 K, sharp peak at approximately 20 K in magnetization curve and magnetization reversal. Interestingly, exchange bias due to antiferromagnetic NiO shell is absent. Among other possibilities, anisotropy variations due to particle size distribution and twinning associated with disorder appear to play an important role. Further, magnetic interactions of twinned bigger spheres, which may also act as superferrimagnetic-like Ni multilayer cores, with superparamagnetic Ni of smaller spheres, might be the additional causes. These nanostructures therefore seem to have potential interest in memory effect.

  1. Structural Electronic and Magnetic Properties of Quasi-1D Quantum Magnets [Ni(HF2)(pyz)2]X (pyz = pyrazine; X = PF6- SbF6-) Exhibiting Ni-FHF-Ni and Ni-pyz-Ni Spin Interactions

    SciTech Connect

    J Manson; S Lapidus; P Stephens; P Peterson; K Carreiro; H Southerland; T Lancaster; S Blundell; A Steele; et al.

    2011-12-31

    [Ni(HF{sub 2})(pyz){sub 2}]X {l_brace}pyz = pyrazine; X = PF{sub 6}{sup -} (1), SbF{sub 6}{sup -} (2){r_brace} were structurally characterized by synchrotron X-ray powder diffraction and found to possess axially compressed NiN{sub 4}F{sub 2} octahedra. At 298 K, 1 is monoclinic (C2/c) with unit cell parameters, a = 9.9481(3), b = 9.9421(3), c = 12.5953(4) {angstrom}, and {beta} = 81.610(3){sup o} while 2 is tetragonal (P4/nmm) with a = b = 9.9359(3) and c = 6.4471(2) {angstrom} and is isomorphic with the Cu-analogue. Infinite one-dimensional (1D) Ni-FHF-Ni chains propagate along the c-axis which are linked via {mu}-pyz bridges in the ab-plane to afford three-dimensional polymeric frameworks with PF{sub 6}{sup -} and SbF{sub 6}{sup -} counterions occupying the interior sites. A major difference between 1 and 2 is that the Ni-F-H bonds are bent (157{sup o}) in 1 but are linear in 2. Ligand field calculations (LFT) based on an angular overlap model (AOM), with comparison to the electronic absorption spectra, indicate greater {pi}-donation of the HF{sub 2}{sup -} ligand in 1 owing to the bent Ni-F-H bonds. Magnetic susceptibility data for 1 and 2 exhibit broad maxima at 7.4 and 15 K, respectively, and {lambda}-like peaks in dxT/dT at 6.2 and 12.2 K that are ascribed to transitions to long-range antiferromagnetic order (TN). Muon-spin relaxation and specific heat studies confirm these TN's. A comparative analysis of x vs T to various 1D Heisenberg/Ising models suggests moderate antiferromagnetic interactions, with the primary interaction strength determined to be 3.05/3.42 K (1) and 5.65/6.37 K (2). However, high critical fields of 19 and 37.4 T obtained from low temperature pulsed-field magnetization data indicate that a single exchange constant (J1D) alone is insufficient to explain the data and that residual terms in the spin Hamiltonian, which could include interchain magnetic couplings (J), as mediated by Ni-pyz-Ni, and single-ion anisotropy (D), must be considered

  2. Active Pt3Ni (111) Surface of Pt3Ni Icosahedron for Oxygen Reduction.

    PubMed

    Zhu, Jianbing; Xiao, Meiling; Li, Kui; Liu, Changpeng; Zhao, Xiao; Xing, Wei

    2016-11-09

    Highly active, durable oxygen reduction reaction (ORR) electrocatalysts are extremely important for fuel cell applications. Herein, we provide an efficient way to synthesis of activity Pt3M icosahedra by the one-pot hydrothermal method in the presence of glucosamine which can well adjust the reduction rate of Pt(4+) and efficiently control the morphology of final catalysts. Compared to Pt/C, the Pt3Ni icosahedra show 32-fold and 12-fold enhancement in specific and mass activity, respectively. Furthermore, robust durability was also observed in the accelerated durability test. Thus, this Pt3Ni icosahedron is found among the best Pt-based ORR catalysts, moreover, the findings also demonstrate how to mimic active extended surfaces in nanoscale.

  3. Strain-mediated multiferroic control of spontaneous exchange bias in Ni-NiO heterostructures

    NASA Astrophysics Data System (ADS)

    Domann, John P.; Sun, Wei-Yang; Schelhas, Laura T.; Carman, Greg P.

    2016-10-01

    This paper presents the measurement of strain-mediated multiferroic control of spontaneous exchange bias (SEB) in magnetostrictive nickel/nickel oxide (Ni/NiO) bilayers on ferroelectric lead magnesium niobate-lead titanate (PMN-PT). Electric field control of a positive to negative exchange bias shift was measured, with an overall shift of 40.5 Oe, corresponding to a 325% change. Observed changes in coercivity are also reported and provide insight into the role of competing anisotropies in these structures. The findings in this paper provide evidence that magnetoelastic anisotropy can be utilized to control spontaneous exchange bias (SEB). This control of SEB is accomplished by modifying a bulk anisotropy (magnetoelasticity) that adjusts the mobility of interfacial anti-ferromagnetic spins and, therefore, the magnitude of the exchange bias. The demonstrated magnetoelastic control of exchange bias provides a useful tool in the creation of future magnetoelectric devices.

  4. K{sup 0} and {lambda} production in Ni+Ni collisions near threshold

    SciTech Connect

    Merschmeyer, M.; Herrmann, N.; Benabderrahmane, M. L.; Cordier, E.; Mangiarotti, A.; Pelte, D.; Xiao, Z. G.; Lopez, X.; Andronic, A.; Hartmann, O. N.; Hildenbrand, K. D.; Koczon, P.; Leifels, Y.; Reisdorf, W.; Schuettauf, A.; Bastid, N.; Crochet, P.; Barret, V.; Dupieux, P.

    2007-08-15

    New results concerning the production of neutral strange particles, K{sup 0} and {lambda} in Ni+Ni collisions at 1.93A GeV, measured with the FOPI detector at GSI Darmstadt, are presented. Rapidity density distributions and Boltzmann slope parameter distributions are measured in nearly the full phase space of the reaction. The observables are compared to existing K{sup +} and proton data. While the K{sup 0} data agree with previously reported K{sup +} measurements, the {lambda} distributions show a different behavior relative to that of protons. The strangeness balance and the production yield per participating nucleon as a function of the centrality of the reaction are discussed, for the first time at GSI Schwerionen Synchrotron (SIS) energies.

  5. Magnetoresistance behavior of Ni80Fe20/Ru/Ni80Fe20 nanostripes

    NASA Astrophysics Data System (ADS)

    Lupo, P.; Liu, X. M.; Adeyeye, A. O.

    2015-07-01

    We present a systematic investigation on the effects of interlayer coupling on the magnetoresistance (MR) behavior of Ni80Fe20/Ru(/Ni80Fe20 trilayer nanostripes (NSs) as a function of temperature T . By changing from 0.8 nm to 1.7 nm, either a ferromagnetic or an antiferromagnetic (AFM) type of interlayer coupling was achieved, leading to a markedly different MR behavior. We observed that the MR response is a superimposition of AMR and GMR effects, and it is significantly dependent on temperature. For AFM coupled NSs, there is a transition from a pure AFM state to a reversed spin-flop phase due to enhanced ferromagnetic pin-hole coupling at low T. Our experimental results are in good agreement with micromagnetic simulations.

  6. The behavior of Ni 2+ on calcite surfaces

    NASA Astrophysics Data System (ADS)

    Hoffmann, U.; Stipp, S. L. S.

    2001-11-01

    Transport of Ni 2+ in the geosphere plays a role in the formation of ore deposits as well as in the dispersion of contaminants in the environment. Some elements (Cd 2+, Zn 2+, Na +, K +, and Cl -) are known to diffuse in calcite at the rate of nanometers in months, so questions arose about the ability of Ni 2+ to move away from adsorption sites at the surface into the bulk. Nickel incorporation into calcite is limited by its high dehydration enthalpy and by its ligand field hindrance to entering the distorted octahedra of calcite, but evidence exists that calcite can tolerate several percent Ni 2+ in the structure. Cleaved samples of Iceland spar were exposed for 1 minute to solutions of 10 -3 M and 10 -2 M Ni(ClO 4) 2, the solution was physically removed and the samples were examined using the surface sensitive techniques: X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and Atomic Force Microscopy (AFM). XPS and TOF-SIMS showed that Ni 2+ was adsorbed while AFM confirmed that dissolution was taking place. The sample was stored in air and relative surface concentration and physical morphology were monitored for 2 years. Trends in the chemical data suggested statistically significant loss of surface Ni 2+ with time, but the decrease was very close to the limits for significance. AFM images demonstrated that surface topography of the Ni-exposed samples is modified by spontaneous recrystalization in the water layer adsorbed from air in exactly the same way that clean calcite surfaces typically rearrange. This process could bury a small amount of Ni 2+ in the bulk, explaining the very weak loss. Limited burial of Ni 2+ within the near-surface could renew calcite adsorption sites, thus increasing uptake capacity. Evidence indicates that surface recrystalization occurs even in very dry environments (<5% humidity). This means that burial could play a role in Ni 2+ mobility in unsaturated groundwater regimes or in fractures

  7. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect

    Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat; İyigör, Ahmet; Candan, Abdullah

    2014-10-06

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

  8. Effect of Mg substitution on crystal structure and hydrogenation of Ce2Ni7-type Pr2Ni7

    NASA Astrophysics Data System (ADS)

    Iwase, Kenji; Mori, Kazuhiro; Terashita, Naoyoshi; Tashiro, Suguru; Suzuki, Tetsuya

    2017-03-01

    The effect of Pr being substituted by Mg in Pr2Ni7 with a Ce2Ni7-type structure was investigated by X-ray diffraction (XRD) and pressure-composition (P-C) isotherm measurements. The maximum hydrogen capacity of Pr2Ni7 reached 1.24 H/M in the first absorption process. However, 0.61 H/M hydrogen remained in the sample after the first desorption and the reversible hydrogen capacity decreased to 0.63 H/M. Severe peak broadening was observed in the XRD profile of Pr2Ni7H5.4 after the first P-C isotherm cycle. The metal sublattice of Pr2Ni7H5.4 is deformed and changes from the Ce2Ni7-type structure to a lower symmetry during hydrogenation, with no detection of an amorphous phase. Pr1.5Mg0.5Ni7 consists of two phases: 80% Gd2Co7-type and 20% PuNi3-type phases. Mg substitution leads to the relative stability of the Gd2Co7-type and PuNi3-type structures. The Gd2Co7-type and PuNi3-type structures are retained after the P-C isotherm. The reversible hydrogen capacity reached 1.05 H/M. The structural change during the hydrogen absorption-desorption cycle and the hydrogenation characteristics are changed by Mg atoms replacing Pr in the MgZn2-type cell.

  9. Structure, stability and magnetic properties of (NiAl)n(n≤6) clusters

    NASA Astrophysics Data System (ADS)

    Wen, Jun-Qing; Zhang, Jian-Min; Chen, Guo-Xiang; Zhang, Xiao-Zhen; Wen, Zhen-Yi

    2016-09-01

    In this paper, density functional theory with generalized gradient approximation (GGA) for the exchange-correlation potential has been used to calculate the energetically global-minimum geometries and electronic states of (NiAl)n(n≤6) clusters. Full structural optimizations, analysis of energy and frequency calculation are performed. The most stable structures of (NiAl)n clusters are all three-dimensional structures except NiAl. The average bond lengths of (NiAl)n clusters are larger than that of Ni2n, and are smaller than that of Al2n. The binding energy per atom of Ni2n and (NiAl)n has the same change trend, and that are larger than that of Al2n. Stability analysis shows that Ni8, (NiAl)2 and Al10 clusters have higher relative stability than other clusters. Mulliken analysis indicates that charges always transfer from Al atoms to Ni atoms, and the average charges of transfer from Al atoms to Ni atoms have a maximum at (NiAl)6, implying the strong interaction between Al and Ni atoms in (NiAl)6. The average atomic magnetic moments of (NiAl)n are smaller than that of true Ni2n. The analysis of the static polarizability shows that the electronic structures of (NiAl)n clusters tend to be compact with the increase of atoms.

  10. Formation of alternating interfacial layers in Au-12Ge/Ni joints

    PubMed Central

    Lin, Shih-kang; Tsai, Ming-yueh; Tsai, Ping-chun; Hsu, Bo-hsun

    2014-01-01

    Au-Ge alloys are promising materials for high-power and high-frequency packaging, and Ni is frequently used as diffusion barriers. This study investigates interfacial reactions in Au-12Ge/Ni joints at 300°C and 400°C. For the reactions at 300°C, typical interfacial morphology was observed and the diffusion path was (Au) + (Ge)/NiGe/Ni5Ge3/Ni. However, an interesting phenomenon – the formation of (Au,Ni,Ge)/NiGe alternating layers – was observed for the reactions at 400°C. The diffusion path across the interface was liquid/(Au,Ni,Ge)/NiGe/···/(Au,Ni,Ge)/NiGe/Ni2Ge/Ni. The periodic thermodynamic instability at the NiGe/Ni2Ge interface caused the subsequent nucleation of new (Au,Ni,Ge)/NiGe pairs. The thermodynamic foundation and mechanism of formation of the alternating layers are elaborated in this paper. PMID:24690992

  11. Preparation of Ni-Sn alloys by an electroless-deposition method

    SciTech Connect

    Shimauchi, Hidenori; Ozawa, Susumu; Tamura, Keiu; Osaka, Tetsuya . Dept. of Applied Chemistry)

    1994-06-01

    Ni-Sn alloy is expected for as a functional material, because of its excellent corrosion resistance, wear resistance, and solderability. Electroless-deposited Ni-Sn alloy films were investigated to increase tin content in the deposit. The maximum tin contents of electroless Ni-Sn-P and Ni-Sn-B were ca. 30 atom percent (a/o) and 42 a/o, respectively. The maximum tin contents in the case of Ni-Sn-B was nearly equal to that of electrodeposited Ni-Sn alloy already reported. The crystallinity of Ni-Sn-P and Ni-Sn-B alloys was raised up with an increase in tin content. The corrosion resistance of Ni-Sn-P and Ni-Sn-B alloys was between that of amorphous and crystalline electroless-deposited Ni-P. Codeposition of tin into Ni-P films improved solderability, but into the Ni-B films, the solderability of Ni-Sn-B films situated in the region between those of Ni-P and NiB, because the solderability of NiB is higher.

  12. Controlled growth of Cu-Ni nanowires and nanospheres for enhanced microwave absorption properties

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxia; Dong, Lifeng; Zhang, Baoqin; Yu, Mingxun; Liu, Jingquan

    2016-03-01

    Copper is a good dielectric loss material but has low stability, whereas nickel is a good magnetic loss material and is corrosion resistant but with low conductivity, therefore Cu-Ni hybrid nanostructures have synergistic advantages as microwave absorption (MA) materials. Different Cu/Ni molar ratios of bimetallic nanowires (Cu13@Ni7, Cu5@Ni5 and Cu7@Ni13) and nanospheres (Cu13@Ni7, Cu5@Ni5 and Cu1@Ni3) have been successfully synthesized via facile reduction of hydrazine under similar reaction conditions, and the morphology can be easily tuned by varying the feed ratio or the complexing agent. Apart from the concentrations of Cu2+ and Ni2+, the reduction parameters are similar for all samples to confirm the effects of the Cu/Ni molar ratio and morphology on MA properties. Ni is incorporated into the Cu-Ni nanomaterials as a shell over the Cu core at low temperature, as proved by XRD, SEM, TEM and XPS. Through the complex relative permittivity and permeability, reflection loss was evaluated, which revealed that the MA capacity greatly depended on the Cu/Ni molar ratio and morphology. For Cu@Ni nanowires, as the molar ratio of Ni shell increased the MA properties decreased accordingly. However, for Cu@Ni nanospheres, the opposite trend was found, that is, as the molar ratio of the Ni shell increased the MA properties increased.

  13. Ni/metal hydride secondary element

    DOEpatents

    Bauerlein, Peter

    2005-04-19

    A Ni/metal hydride secondary element having a positive nickel hydroxide electrode, a negative electrode having a hydrogen storage alloy, and an alkaline electrolyte, the positive electrode, provided with a three-dimensional metallic conductive structure, also contains an aluminum compound which is soluble in the electrolyte, in addition to nickel hydroxide and cobalt oxide. The aluminum compound is aluminum hydroxide and/or aluminum oxide, and the mass of the aluminum compound which is present in the positive bulk material mixture is 0.1 to 2% by weight relative to the mass of the nickel hydroxide which is present. In combination with aluminum hydroxide or aluminum oxide, the positive electrode further contains lanthanoid oxidic compounds Y.sub.2 O.sub.3, La.sub.2 O.sub.3 and Ca(OH).sub.2, as well as mixtures of these compounds.

  14. NiCd battery electrodes, C-150

    NASA Technical Reports Server (NTRS)

    Holleck, G.

    1971-01-01

    A research program to develop and evaluate electrodes for a nongassing negative limited nickel-cadmium cell is described. The concept of the negative limited cell and its implications on electrode structure are discussed. The key element is the development of a cadmium electrode with high hydrogen overvoltage. For this, Teflon-bonded Cd electrodes and silver-sinter based Gc electrodes were manufactured and in preliminary experiments their physical and electrochemical characteristics were evaluated. Hydrogen evolution on cadmium was found to occur approximately 100 mV more cathodic than on silver. Both electrode structures exhibit a fairly sharp potential rise at the end of the charging cycle and the advent of gas evolution occurs at potentials between -1.2 and -1.3 V versus a Hg/HgO reference electrode. These results are compared with conventional Ni-sinter based Cd electrodes.

  15. Final Viking NiCd battery conditioning

    SciTech Connect

    Britting, A.

    1983-08-01

    The Viking Lander Monitor Mission (VLMM) is well beyond its planned 90-day landed Mars mission. It has been an established NASA goal to maintain an American presence on Mars for as long as possible. With healthy subsystems, the mission could conceivably last until December 5, 1994. At that time the radioisotope thermoelectric generator (RTG) power source output power would be marginal for support of the system electrical loads and for battery maintenance. The antenna pointing coefficients will also expire at that time, resulting in telecommunication system shutdown. Recently three of the four, 8 ampere-hour (AH) nickel-cadmium (NiCd) batteries onboard Viking Lander 1 (VL-1) have indicated signs of significant loss of energy storage capacity. An intensive program of deep-discharge battery reconditioning was begun in January 1982 in an attempt to return the batteries to levels of capacity approaching early mission values.

  16. Nanostructurization of Fe-Ni Alloy

    NASA Astrophysics Data System (ADS)

    Danilhenko, Vitaliy E.

    2017-03-01

    Data about an effect of cyclic γ-α-γ martensitic transformations on the structure state of reverted austenite Fe-31.7 wt.% Ni-0.06 wt.% C alloy are presented. The effect of multiple direct γ-α and reverse α-γ martensitic transformations on fragmentation of austenitic grains has been investigated by electron microscopy and X-ray diffraction methods. An ultrafine structure has been formed by nanofragmentation inside the initial austenite grains due to the successive misorientation of their crystal lattice. Austenite was nanofragmented as a result of multiple γ-α-γ martensitic transformations. Slow heating of the nanofragmented alloy at a rate below 2 °C/s results in nanograin refinement of the structure by multiplication of the reverted γ-phase orientations. The conditions of structure refinement up to ultrafine and nanocrystalline levels as a result of both shear and diffusion mechanisms of reverse α-γ transformation are determined.

  17. Electronic ground state of Ni2+

    NASA Astrophysics Data System (ADS)

    Zamudio-Bayer, V.; Lindblad, R.; Bülow, C.; Leistner, G.; Terasaki, A.; v. Issendorff, B.; Lau, J. T.

    2016-11-01

    The 9/2 4Φ ground state of the Ni2+ diatomic molecular cation is determined experimentally from temperature and magnetic-field-dependent x-ray magnetic circular dichroism spectroscopy in a cryogenic ion trap, where an electronic and rotational temperature of 7.4 ±0.2 K was reached by buffer gas cooling of the molecular ion. The contribution of the spin dipole operator to the x-ray magnetic circular dichroism spin sum rule amounts to 7 Tz =0.17 ± 0.06 μB per atom, approximately 11% of the spin magnetic moment. We find that, in general, homonuclear diatomic molecular cations of 3d transition metals seem to adopt maximum spin magnetic moments in their electronic ground states.

  18. Can Ni phosphides become viable hydroprocessing catalysts?

    SciTech Connect

    Soled, S.; Miseo, S.; Baumgartner, J.; Guzman, J.; Bolin, T.; Meyer, R.

    2015-05-15

    We prepared higher surface area nickel phosphides than are normally found by reducing nickel phosphate. To do this, we hydrothermally synthesized Ni hydroxy phosphite precursors with low levels of molybdenum substitution. The molybdenum substitution increases the surface area of these precursors. During pretreatment in a sulfiding atmosphere (such as H2S/H2) dispersed islands of MoS2 segregate from the precursor and provide a pathway for H2 dissociation that allows reduction of the phosphite precursor to nickel phosphide at substantially lower temperatures than in the absence of MoS2. The results reported here show that to create nickel phosphides with comparable activity to conventional supported sulfide catalysts, one would have to synthesize the phosphide with surface areas exceeding 400 m2/g (i.e. with nanoparticles less than 30 Å in lateral dimension).

  19. Ni/TiO2 Ultraviolet Detector

    NASA Astrophysics Data System (ADS)

    Mohamadzade Lajvardi, Mehdi; Jahangiri, Mojtaba

    2016-03-01

    The fabrication technology of solid-state photon detectors based on semiconductors other than silicon is yet to mature, but their recent progress opens new possibilities. Such devices are especially attractive for ultraviolet radiation level measurements because semiconductor materials with band gaps larger than 3.0 eV can be used as “visible-blind” detectors, the operation of which do not require using visible light filters. Here, fabrication and characterization of a UV detector based on nickel/titanium dioxide Schottky junction is reported. The operation of the device is described based on the photoelectric mechanism taking place in the carrier- depleted oxide adjacent to the Ni layer. Simplicity of fabrication, cost-effectiveness and fast response are the positive features of the device. These features of the device are compared with those of the previously reported Ag/TiO2 UV detectors.

  20. Stereo-epitaxial growth of single-crystal Ni nanowires and nanoplates from aligned seed crystals

    NASA Astrophysics Data System (ADS)

    Lee, Hyoban; Yoo, Youngdong; Kang, Taejoon; Lee, Jiyoung; Kim, Eungwang; Fang, Xiaosheng; Lee, Sungyul; Kim, Bongsoo

    2016-05-01

    Epitaxially grown anisotropic Ni nanostructures are promising building blocks for the development of miniaturized and stereo-integrated data storage kits because they can store multiple magnetic domain walls (DWs). Here, we report stereo-epitaxially grown single-crystalline Ni nanowires (NWs) and nanoplates, and their magnetic properties. Vertical and inclined Ni NWs were grown at the center and edge regions of c-cut sapphire substrates, respectively. Vertical Ni nanoplates were grown on r-cut sapphire substrates. The morphology and growth direction of Ni nanostructures can be steered by seed crystals. Cubic Ni seeds grow into vertical Ni NWs, tetrahedral Ni seeds grow into inclined Ni NWs, and triangular Ni seeds grow into vertical Ni nanoplates. The shapes of the Ni seeds are determined by the interfacial energy between the bottom plane of the seeds and the substrates. The as-synthesized Ni NWs and nanoplates have blocking temperature values greater than 300 K at 500 Oe, verifying that these Ni nanostructures can form large magnetic DWs with high magnetic anisotropy properties. We anticipate that epitaxially grown Ni NWs and nanoplates will be used in various types of 3-dimensional magnetic devices.Epitaxially grown anisotropic Ni nanostructures are promising building blocks for the development of miniaturized and stereo-integrated data storage kits because they can store multiple magnetic domain walls (DWs). Here, we report stereo-epitaxially grown single-crystalline Ni nanowires (NWs) and nanoplates, and their magnetic properties. Vertical and inclined Ni NWs were grown at the center and edge regions of c-cut sapphire substrates, respectively. Vertical Ni nanoplates were grown on r-cut sapphire substrates. The morphology and growth direction of Ni nanostructures can be steered by seed crystals. Cubic Ni seeds grow into vertical Ni NWs, tetrahedral Ni seeds grow into inclined Ni NWs, and triangular Ni seeds grow into vertical Ni nanoplates. The shapes of the Ni

  1. Superconductivity in the Ni based ternary carbide LaNiC 2

    NASA Astrophysics Data System (ADS)

    Lee, W. H.; Zeng, H. K.; Yao, Y. D.; Chen, Y. Y.

    1996-02-01

    Electrical-resistivity, magnetic-susceptibility and specific-heat data reveal that the bulk phase transition at 2.63 ∼ 2.86 K (10 ∼ 90% values) in LaNiC 2 is to a superconducting ground state. The normal-state specific-heat data can be fitted to the expression Cn = γT+ βT3 (3 K< T<7 K) by a least-quares analysis, where γ = 7.83 mJ/mol K 2 and β = 0.0635 mJ/mol K 4, resulting in Debye temperature θD = 496 K. A special emphasis is on the specific heat in the superconducting state below 1.6 K; Cs is not exponential but has a power-law form: Cs ≈ 3.5( γTc)( T/ Tc) 3. According to the observed specific-heat data, we suggest that LaNiC 2 belongs to a nonconventional BCS superconductor. In addition, LaNiC 2 is the first nickel-based ternary-carbide superconductor.

  2. Evidence of nickel (Ni) efflux in Ni-tolerant ectomycorhizal Pisolithus albus isolated from ultramafic soil.

    PubMed

    Majorel, Clarisse; Hannibal, Laure; Ducousso, Marc; Lebrun, Michel; Jourand, Philippe

    2014-10-01

    Nickel (Ni)-tolerant ectomycorrhizal Pisolithus albus was isolated from extreme ultramafic soils that are naturally rich in heavy metals. This study aimed to identify the specific molecular mechanisms associated with the response of P. albus to nickel. In presence of high concentration of nickel, P. albus Ni-tolerant isolate showed a low basal accumulation of nickel in its fungal tissues and was able to perform a metal efflux mechanism. Three genes putatively involved in metal efflux were identified from the P. albus transcriptome, and their overexpression was confirmed in the mycelium that was cultivated in vitro in the presence of nickel and in fungal tissues that were sampled in situ. Cloning these genes in yeast provided significant advantages in terms of nickel tolerance (+ 31% Ni EC50) and growth (+ 83% μ) compared with controls. Furthermore, nickel efflux was also detected in the transformed yeast cells. Protein sequence analysis indicated that the genes encoded a P-type-ATPase, an ABC transporter and a major facilitator superfamily permease (MFS). This study sheds light on a global mechanism of metal efflux by P. albus cells that supports nickel tolerance. These specific responses to nickel might contribute to the fungal adaptation in ultramafic soil.

  3. Preparation of electrodeposited Mo-Ni coating and its spectral properties.

    PubMed

    Liu, Xiao-Zhen; Xiong, Li-Ping; Liu, Xiao-Zhou; Chen, Jie; Luo, Yi-Fan; Sun, Ying

    2014-04-01

    Mo-Ni coatings were prepared on Ni alloy by electrodeposition method. The properties of microhardness, wear weight loss and friction coefficients, and thermal expansion of the coatings were investigated, respectively. Mo-Ni coatings were characterized with inductively coupled plasma-atomic emission spectroscopy (ICP-AES), energy-dispersive analyses of X-ray (EDAX), scanning electron microcopy (SEM), and X-ray diffraction (XRD) techniques, respectively. Mo-Ni coating shows higher microhardness, lower wear weight loss and friction coefficient compared with those of Ni alloy. The microhardness of Mo-Ni coating is as high as 518 HV, which is 72.67% higher than that of the Ni alloy (300 HV). The wear weight losses of Mo-Ni coating is 1.94 times lower than that of Ni alloy. The friction coefficient of Ni alloy and Mo-Ni coating are 0.640 and 0.559 respectively. The physical thermal expansion curve of Ni alloy has two the peaks in the ranges of 100-120 and 570-640 degrees C respectively; and that of Ni alloy+Mo-Ni coating has one the peaks in the ranges of 570-640 degrees C. The peak of the physical thermal expansion curve of Ni alloy+Mo-Ni coating in the ranges of 570-640 degrees C is much smaller than that of the Ni alloy. Because the part of nickel was replaced by molybdenum in the Ni lattice, molybdenum decreases the lattices transformation of nickel (bcc --> fcc). The reason for the formation of the small peak of the physical thermal expansion curve of Ni alloy+Mo-Ni coating in the ranges of 595-625 degrees C is the changes of MoNi4 and MoNi from the semi-crystalline structure to the crystalline structure respectively.

  4. Atomic data for astrophysics: Ni XI

    NASA Astrophysics Data System (ADS)

    Del Zanna, G.; Storey, P. J.; Badnell, N. R.

    2014-06-01

    We present a new large-scale R-matrix scattering calculation for electron collisional excitation of Ni xi, carried out with the intermediate-coupling frame transformation method. The target includes all the main configurations up to n = 4, and is a significant improvement over earlier R-matrix (only three n = 3 configurations) and distorted-wave (DW) calculations. We find significant enhancements in the collision strengths of many of the strong transitions to the n = 3,4 levels. They are due to the resonances that arise within the present large-scale target. This results in significant increases in the predicted intensities of the UV and visible forbidden lines within the 3s23p53d configuration, the strong EUV lines that result from the decays of the 3s23p53d levels to the ground state, and the decays from the n = 4 levels, which are visible in the soft X-rays. We find good agreement between predicted and observed line intensities in the EUV. With the present atomic data, lines from Ni xi can reliably be used for plasma diagnostics. We also revise some level energies and suggest a few new possible identifications. The full dataset (energies, transition probabilities and rates) are only available in electronic form at our APAP website (http://www.apap-network.org) as well as at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/566/A123

  5. Durability of Ni anodes during reoxidation cycles

    NASA Astrophysics Data System (ADS)

    Ettler, M.; Timmermann, H.; Malzbender, J.; Weber, A.; Menzler, N. H.

    Anodes manufactured from NiO- and yttria-stabilized zirconia (Y 2O 3 doped ZrO 2, YSZ) powders are today's state of the art for solid oxide fuel cells (SOFCs) because they are easy to manufacture and have high performance in both anode-supported and electrolyte-supported cells. However, such cells can show significant degradation or fail completely if nickel is reoxidized during high-temperature operation even though it can be reduced again. Tests with stacks and systems have shown that system shutdown procedures, accidental air entry due to component failure or controlled air feed to the anode side as a result of operational necessities may occur and result in the reoxidation of the metallic nickel. This reoxidation is not only associated with a volume expansion, but also with significant structural changes in the anode microstructure, generating stresses in the anode itself, as well as in the electrolyte. These stresses can exceed the stability of the components, potentially promoting crack growth, which leads to degradation of the SOFC or complete failure. This problem has been addressed by a number of contributions in the literature over the last decade, but interest is increasing, particularly because SOFC systems are being discussed for transport and mobile applications requiring new system specifications. The most critical problem to be overcome is the tolerance of a large number of intentional redox cycles due to system requirements during operating lifetime. This article gives an overview of the various approaches to the redox problem by summarizing many of the contributions, starting with a basic understanding of the underlying physicochemical processes of Ni reduction and oxidation and ending at stack-level results, leading finally to their combination with recent findings. It aims to elaborate reliable results and open questions on this topic considering the mechanical and electrochemical aspects of the problem.

  6. Phase equilibria, formation, crystal and electronic structure of ternary compounds in Ti-Ni-Sn and Ti-Ni-Sb ternary systems

    SciTech Connect

    Romaka, V.V.; Rogl, P.; Romaka, L.; Stadnyk, Yu.; Melnychenko, N.; Grytsiv, A.; Falmbigl, M.; Skryabina, N.

    2013-01-15

    The phase equilibria of the Ti-Ni-Sn and Ti-Ni-Sb ternary systems have been studied in the whole concentration range by means of X-ray and EPM analyses at 1073 K and 873 K, respectively. Four ternary intermetallic compounds TiNiSn (MgAgAs-type), TiNi{sub 2-x}Sn (MnCu{sub 2}Al-type), Ti{sub 2}Ni{sub 2}Sn (U{sub 2}Pt{sub 2}Sn-type), and Ti{sub 5}NiSn{sub 3} (Hf{sub 5}CuSn{sub 3}-type) are formed in Ti-Ni-Sn system at 1073 K. The TiNi{sub 2}Sn stannide is characterized by homogeneity in the range of 50-47 at% of Ni. The Ti-Ni-Sb ternary system at 873 K is characterized by formation of three ternary intermetallic compounds, Ti{sub 0.8}NiSb (MgAgAs-type), Ti{sub 5}Ni{sub 0.45}Sb{sub 2.55} (W{sub 5}Si{sub 3}-type), and Ti{sub 5}NiSb{sub 3} (Hf{sub 5}CuSn{sub 3}-type). The solubility of Ni in Ti{sub 0.8}NiSb decreases number of vacancies in Ti site up to Ti{sub 0.91}Ni{sub 1.1}Sb composition. - Graphical abstract: Isothermal section of the Ti-Ni-Sn phase diagram and DOS distribution in hypothetical TiNi{sub 1+x}Sn solid solution. Highlights: Black-Right-Pointing-Pointer Ti-Ni-Sn phase diagram was constructed at 1073 K. Black-Right-Pointing-Pointer Four ternary compounds are formed: TiNiSn, TiNi{sub 2-x}Sn, Ti{sub 2}Ni{sub 2}Sn, and Ti{sub 5}NiSn{sub 3}. Black-Right-Pointing-Pointer Three ternary compounds exist in Ti-Ni-Sb system at 873 K. Black-Right-Pointing-Pointer The TiNi{sub 2}Sb compound is absent.

  7. NiCo2O4 nanosheets in-situ grown on three dimensional porous Ni film current collectors as integrated electrodes for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Guo, Ying; Zhao, Bo; Yu, Shuhui; Yang, Hai-Peng; Lu, Daniel; Fu, Xian-Zhu; Sun, Rong; Wong, Ching-Ping

    2015-07-01

    Three dimensional interconnected hierarchical porous Ni films are easily fabricated as effective current collectors through hydrogen bubble template electrochemical deposition. The binder-free integrated electrodes of spinel NiCo2O4 nanosheets directly coated the three dimensional porous Ni films are facilely obtained through successively electrochemical co-deposition of Ni/Co alloy layer then followed by subsequent annealing at 350 °C in air. Compared with NiCo2O4 nanosheets on smooth Ni foil or porous NiO/Ni film electrodes, the porous NiCo2O4/Ni integrated film electrodes for supercapacitors demonstrate remarkably higher area specific capacitance. The porous NiCo2O4/Ni film electrodes also exhibit excellent rate capability and cycling stability. The super electrochemical capacitive performances are attributed to the unique integrated architecture of NiCo2O4 nanosheets in-situ grown on three dimensional continuous hierarchical porous Ni collector collectors, which could provide large electrode-electrolyte interface area, high active sites, low contact resistance between current collector and active materials, fast electron conduction and ion/electrolyte diffusion.

  8. Comparison of the magnetic properties of metastable hexagonal close-packed Ni nanoparticles with those of the stable face-centered cubic Ni nanoparticles.

    PubMed

    Jeon, Yoon Tae; Moon, Je Yong; Lee, Gang Ho; Park, Jeunghee; Chang, Yongmin

    2006-01-26

    We report the first magnetic study of pure and metastable hexagonal close-packed (hcp) Ni nanoparticles (sample 1). We also produced stable face-centered cubic (fcc) Ni nanoparticles, as mixtures with the hcp Ni nanoparticles (samples 2 and 3). We compared the magnetic properties of the hcp Ni nanoparticles with those of the fcc Ni nanoparticles by observing the evolution of magnetic properties from those of the hcp Ni nanoparticles to those of the fcc Ni nanoparticles as the number of fcc Ni nanoparticles increased from sample 1 to sample 3. The blocking temperature (T(B)) of the hcp Ni nanoparticles is approximately 12 K for particle diameters ranging between 8.5 and 18 nm, whereas those of the fcc Ni nanoparticles are 250 and 270 K for average particle diameters of 18 and 26 nm, respectively. The hcp Ni nanoparticles seem to be antiferromagnetic for T < T(B) and paramagnetic for T > T(B). This is very different from the fcc Ni nanoparticles, which are ferromagnetic for T < T(B) and superparamagnetic for T > T(B). This unusual magnetic state of the metastable hcp Ni nanoparticles is likely related to their increased bond distance (2.665 angstroms), compared to that (2.499 angstroms) of the stable fcc Ni nanoparticles.

  9. NiCoO2 flowers grown on the aligned-flakes coated Ni foam for application in hybrid energy storage

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyang; Zhao, Huilin; Zhou, JingKuo; Xue, Ruinan; Gao, Jianping

    2016-10-01

    Many NiCoO2 flowers with an average diameter of about 4 μm were grown on the NiCoO2 flakes coated Ni foam (denoted as NiCoO2/Ni foam) through a simple hydrothermal method and confirmed by scanning and transmission electron microscopies, X-ray diffraction and X-ray photoelectron spectrum measurements. The NiCoO2/Ni foam with high specific area and porosity was directly used as the working electrode without any binders. The measured specific capacitance of NiCoO2 grown on Ni foam is 756 F/g at 0.75 A/g using a three-electrode setup in 1 M KOH. Considering the high capacity of NiCoO2 and the good stability of rGO, the NiCoO2/Ni foam//rGO hybrid supercapacitor combining NiCoO2/Ni foam and rGO shows very good properties, such as high specific capacitance (82 F/g at 2 A/g based on the total mass of active materials), high energy density (25.7 Wh/kg at 1500 W/kg based on the total mass of active materials), good stability (about 90% capacitance retention after 2000-cycle at 100 mV/s), and low charge ion transfer resistance.

  10. From one to three dimensions: corrugated ∞(1)[NiGe] ribbons as a building block in alkaline earth metal Ae/Ni/Ge phases with crystal structure and chemical bonding in AeNiGe (Ae = Mg, Sr, Ba).

    PubMed

    Hlukhyy, Viktor; Siggelkow, Lisa; Fässler, Thomas F

    2013-06-17

    The new equiatomic nickel germanides MgNiGe, SrNiGe, and BaNiGe have been synthesized from the elements in sealed tantalum tubes using a high-frequency furnace. The compounds were investigated by X-ray diffraction both on powders and single crystals. MgNiGe crystallizes with TiNiSi-type structure, space group Pnma, Z = 4, a = 6.4742(2) Å, b = 4.0716(1) Å, c = 6.9426(2) Å, wR2 = 0.033, 305 F(2) values, 20 variable parameters. SrNiGe and BaNiGe are isotypic and crystallize with anti-SnFCl-type structure (Z = 4, Pnma) with a = 5.727(1) Å, b = 4.174(1) Å, c = 11.400(3) Å, wR2 = 0.078, 354 F(2) values, 20 variable parameters for SrNiGe, and a = 5.969(4) Å, b = 4.195(1) Å, c = 11.993(5) Å, wR2 = 0.048, 393 F(2) values, 20 variable parameters for BaNiGe. The increase of the cation size leads to a reduction of the dimensionality of the [NiGe] polyanions. In the MgNiGe structure the nickel and germanium atoms build a ∞(3)[NiGe] network with magnesium atoms in the channels. In SrNiGe and BaNiGe the ∞(1)[NiGe] ribbons are separated by strontium/barium atoms, whereas in the known CaNiGe structure the ribbons are fused to two-dimmensional atom slabs. The crystal chemistry and chemical bonding in AeNiGe (Ae = Mg, Ca, Sr, Ba) are discussed. The experimental results are reconciled with electronic structure calculations performed using the tight-binding linear muffin-tin orbital (TB-LMTO-ASA) method.

  11. Effects of Dimethylamine Borane in Electroless Ni-B Plating.

    PubMed

    Rha, Sa-Kyun; Baek, Seung-Deok; Lee, Youn-Seoung

    2015-10-01

    By electroless plating in a pH 7 bath at 50 °C, Ni-B alloy films with nano-crystallite size (3-6 nm) were formed on screen printed Ag paste. According to the addition of DMAB (dimethylamine borane), the boron concentration in the Ni-B alloy films increased systematically from <1 at.% to ~10 at.%, and the crystallite size of the Ni-B alloy films decreased gradually. The crystal/electronic structures of the Ni-B alloys were studied using XAS (X-ray absorption spectroscopy), XRD, etc., with changes of boron contents. In the crystalline structure, the ordering of fcc type was broken upon alloying and then the samples with additions of 0.5 M and 1 M DMAB had amorphous-like structures with decreases of crystallite size. In the electronic structure, the unoccupied d states of the Ni sites were filled as the B concentration increased upon alloying. From the electronegativity rule and the broken orderging upon alloying, we can suggest that an overall charge transfer occurs from the Ni sites toward the alloying B sites with intra-atomic charge redistribution, leading to an increased occupancy of the Ni 3d states in the alloys.

  12. Preparation of electrodeposited Zn-Ni-B alloy coatings

    NASA Astrophysics Data System (ADS)

    Sakai, Taro; Kamimoto, Yuki; Ichino, Ryoichi

    2016-01-01

    We prepared Zn-Ni-B alloys with high Zn content and high corrosion resistance. The composition of the alloys was controlled by potentiostatic electrolysis. In the electroplating bath, dimethylamineborane was used as the B source. The characterization of the alloys and corrosion resistance evaluation were carried out by X-ray diffraction (XRD) analysis, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Tafel plots, and cyclic corrosion tests. All films were categorized into three groups on the basis of the results of XRD analysis, and it was found by TEM analysis that the Ni-B-type showed an amorphous structure. The Ni-B-type could contain up to 50.6 mol % Zn and showed similar or better anticorrosion properties than the amorphous Ni-B films. In the Ni-B-type, the higher the Zn content, the higher the corrosion resistance. The Zn-Ni-B alloys had almost the same electrochemical corrosion resistance and Zn content as the Zn-Ni-P alloys.

  13. Porous NiTi for bone implants: A review

    PubMed Central

    Bansiddhi, A.; Sargeant, T.D.; Stupp, S.I.; Dunand, D.C.

    2011-01-01

    NiTi foams are unique among biocompatible porous metals because of their high recovery strain (due to the shape-memory or superelastic effects) and their low stiffness facilitating integration with bone structures. To optimize NiTi foams for bone implant applications, two key areas are under active study: synthesis of foams with optimal architectures, microstructure and mechanical properties; and tailoring of biological interactions through modifications of pore surfaces. This article reviews recent research on NiTi foams for bone replacement, focusing on three specific topics: (i) surface modifications designed to create bio-inert porous NiTi surfaces with low Ni release and corrosion, as well as bioactive surfaces to enhance and accelerate biological activity; (ii) In vitro and in vivo biocompatibility studies to confirm the long-term safety of porous NiTi implants; and (iii) biological evaluations for specific applications, such as in intervertebral fusion devices and bone tissue scaffolds. Possible future directions for bio-performance and processing studies are discussed that could lead to optimized porous NiTi implants. PMID:18348912

  14. Electronic and structural properties of binary Pt-Ni nanoclusters

    NASA Astrophysics Data System (ADS)

    Pérez, Luis A.; Garzón, Ignacio L.

    2007-03-01

    The lowest energy structures of binary (PtNi3)n, (Pt3Ni)n, and (PtNi)m nanoclusters, with n=3-10 and m=3-20, modeled by the many-body Gupta potential, were obtained by using a genetic-symbiotic algorithm. These structures were further relaxed with DFT-GGA. In agreement with the experimental evidence, segregation is observed in these clusters, where the Ni atoms are mainly found in the cluster core and the Pt atoms on the cluster surface. Furthermore, it has been experimentally found that the (Pt3Ni)n nanoalloys present a higher catalytic activity for the N2O + H2 reaction at low temperatures than the other compositions [1], while the contrary trend is observed in the case of the oxidation of carbon monoxide in the presence of hydrogen, where the (PtNi3)n nanoparticles present a higher catalytic activity than the other ones. In order to understand these tendencies in the catalytic activity, we performed an analysis of the surface electronic structure of the bimetallic Pt-Ni nanoclusters with the mentioned compositions, by means of first-principles density functional calculations. Acknowledgments: This work was supported by CONACyT No. 43414-F. [1] Arenas-Alatorre J, Avalos-Borja M, Diaz G J. Phys. Chem. B 109, 2371 (2005).

  15. Unusual reaction of [NiFe]-hydrogenases with cyanide.

    PubMed

    Hexter, Suzannah V; Chung, Min-Wen; Vincent, Kylie A; Armstrong, Fraser A

    2014-07-23

    Cyanide reacts rapidly with [NiFe]-hydrogenases (hydrogenase-1 and hydrogenase-2 from Escherichia coli) under mild oxidizing conditions, inhibiting the electrocatalytic oxidation of hydrogen as recorded by protein film electrochemistry. Electrochemical, EPR, and FTIR measurements show that the final enzyme product, formed within a second (even under 100% H2), is the resting state known as Ni-B, which contains a hydroxido-bridged species, Ni(III)-μ(OH)-Fe(II), at the active site. "Cyanide inhibition" is easily reversed because it is simply the reductive activation of Ni-B. This paper brings back into focus an observation originally made in the 1940s that cyanide inhibits microbial H2 oxidation and addresses the interesting mechanism by which cyanide promotes the formation of Ni-B. As a much stronger nucleophile than hydroxide, cyanide binds more rapidly and promotes oxidation of Ni(II) to Ni(III); however, it is quickly replaced by hydroxide which is a far superior bridging ligand.

  16. Synthesis of FeCoNi nanoparticles by galvanostatic technique

    SciTech Connect

    Budi, Setia; Hafizah, Masayu Elita; Manaf, Azwar

    2016-06-17

    Soft magnetic nanoparticles of FeCoNi have been becoming interesting objects for many researchers due to its potential application in electronic devices. One of the most promising methods for material preparation is the electrodeposition which capable of growing nanoparticles alloy directly onto the substrate. In this paper, we report our electrodeposition studies on nanoparticles synthesis using galvanostatic electrodeposition technique. Chemical composition of the synthesized FeCoNi was successfully controlled through the adjustment of the applied currents. It is revealed that the content of each element, obtained from quantitative analysis using atomic absorption spectrometer (AAS), could be modified by the adjustment of current in which Fe and Co content decreased at larger applied currents, while Ni content increased. The nanoparticles of Co-rich FeCoNi and Ni-rich FeCoNi were obtained from sulphate electrolyte at the range of applied current investigated in this work. Broad diffracted peaks in the X-ray diffractograms indicated typical nanostructures of the solid solution of FeCoNi.

  17. Reaction synthesis of Ni-Al based particle composite coatings

    SciTech Connect

    SUSAN,DONALD F.; MISIOLEK,WOICECK Z.; MARDER,ARNOLD R.

    2000-02-11

    Electrodeposited metal matrix/metal particle composite (EMMC) coatings were produced with a nickel matrix and aluminum particles. By optimizing the process parameters, coatings were deposited with 20 volume percent aluminum particles. Coating morphology and composition were characterized using light optical microscopy (LOM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). Differential thermal analysis (DTA) was employed to study reactive phase formation. The effect of heat treatment on coating phase formation was studied in the temperature range 415 to 1,000 C. Long-time exposure at low temperature results in the formation of several intermetallic phases at the Ni matrix/Al particle interfaces and concentrically around the original Al particles. Upon heating to the 500--600 C range, the aluminum particles react with the nickel matrix to form NiAl islands within the Ni matrix. When exposed to higher temperatures (600--1,000 C), diffusional reaction between NiAl and nickel produces ({gamma})Ni{sub 3}Al. The final equilibrium microstructure consists of blocks of ({gamma}{prime})Ni{sub 3}Al in a {gamma}(Ni) solid solution matrix, with small pores also present. Pore formation is explained based on local density changes during intermetallic phase formation and microstructural development is discussed with reference to reaction synthesis of bulk nickel aluminides.

  18. Corrosion of NiTi Wires with Cracked Oxide Layer

    NASA Astrophysics Data System (ADS)

    Racek, Jan; Šittner, Petr; Heller, Luděk; Pilch, Jan; Petrenec, Martin; Sedlák, Petr

    2014-07-01

    Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO2 surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB-SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.

  19. Mesoscale assembly of NiO nanosheets into spheres

    SciTech Connect

    Zhang Meng; Yan Guojin; Hou Yonggai; Wang Chunhua

    2009-05-15

    NiO solid/hollow spheres with diameters about 100 nm have been successfully synthesized through thermal decomposition of nickel acetate in ethylene glycol at 200 deg. C. These spheres are composed of nanosheets about 3-5 nm thick. Introducing poly(vinyl pyrrolidone) (PVP) surfactant to reaction system can effectively control the products' morphology. By adjusting the quantity of PVP, we accomplish surface areas-tunable NiO assembled spheres from {approx}70 to {approx}200 m{sup 2} g{sup -1}. Electrochemical tests show that NiO hollow spheres deliver a large discharge capacity of 823 mA h g{sup -1}. Furthermore, these hollow spheres also display a slow capacity-fading rate. A series of contrastive experiments demonstrate that the surface area of NiO assembled spheres has a noticeable influence on their discharge capacity. - Graphical abstract: The mesoscale assembly of NiO nanosheets into spheres have been achieved by a solvothermal method. N{sub 2} adsorption/desorption isotherms show the S{sub BET} of NiO is tunable. NiO spheres show large discharge capacity and slow capacity-fading rate.

  20. Porous NiTi for bone implants: a review.

    PubMed

    Bansiddhi, A; Sargeant, T D; Stupp, S I; Dunand, D C

    2008-07-01

    NiTi foams are unique among biocompatible porous metals because of their high recovery strain (due to the shape-memory or superelastic effects) and their low stiffness facilitating integration with bone structures. To optimize NiTi foams for bone implant applications, two key areas are under active study: synthesis of foams with optimal architectures, microstructure and mechanical properties; and tailoring of biological interactions through modifications of pore surfaces. This article reviews recent research on NiTi foams for bone replacement, focusing on three specific topics: (i) surface modifications designed to create bio-inert porous NiTi surfaces with low Ni release and corrosion, as well as bioactive surfaces to enhance and accelerate biological activity; (ii) in vitro and in vivo biocompatibility studies to confirm the long-term safety of porous NiTi implants; and (iii) biological evaluations for specific applications, such as in intervertebral fusion devices and bone tissue scaffolds. Possible future directions for bio-performance and processing studies are discussed that could lead to optimized porous NiTi implants.