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Sample records for ni cu pd

  1. 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.

  2. A Review of TiNiPdCu Alloy System for High Temperature Shape Memory Applications

    NASA Astrophysics Data System (ADS)

    Khan, M. Imran; Kim, Hee Young; Miyazaki, Shuichi

    2015-06-01

    High temperature shape memory alloys (HTSMAs) are important smart materials and possess a significant potential to improve many engineering systems. Many TiNi-based high temperature ternary alloy systems have been reported in literature including TiNiPd, TiNiPt, TiNiZr, TiNiAu, TiNiHf, etc. Some quaternary additions of certain elements in the above systems have been successful to further improve many important shape memory and mechanical properties. The success criteria for an HTSMA become strict in terms of its cyclic stability, maximum recoverable strain, creep resistance, and corrosion resistance at high temperatures. TiNiPdCu alloy system has been recently proposed as a promising HTSMA. Unique nanoscaled precipitates formed in TiNiPdCu-based HTSMAs are found to be stable at temperatures above 773 K, while keeping the benefits of ease of fabrication. It is expected that this alloy system possesses significant potential especially for the high temperature shape memory applications. Till now many research reports have been published on this alloy system. In the present work, a comprehensive review of the TiNiPdCu system is presented in terms of thermomechanical behavior, nanoscale precipitation mechanism, microstructural features, high temperature shape memory and mechanical properties, and the important parameters to control the high temperature performance of these alloys.

  3. Deformation-induced nanoscale mixing reactions in Cu/Ni and Ag/Pd multilayers

    SciTech Connect

    Wang, Z.; Perepezko, J. H.

    2013-11-04

    During the repeated cold rolling of Cu/Ni and Ag/Pd multilayers, a solid solution forms at the interfaces as nanoscale layer structure with a composition that replicates the overall multilayer composition. The interfacial mixing behavior was investigated by means of X-ray diffraction and scanning transmission electron microscopy. During deformation induced reaction, the intermixing behavior of the Cu/Ni and Ag/Pd multilayers is in contrast to thermally activated diffusion behavior. This distinct behavior can provide new kinetic pathways and offer opportunities for microstructure control that cannot be achieved by thermal processing.

  4. Analysis of the applicability of Ni, Cu, Au, Pt, and Pd nanoclusters for data recording

    NASA Astrophysics Data System (ADS)

    Redel', L. V.; Gafner, S. L.; Gafner, Yu. Ya.; Zamulin, I. S.; Goloven'ko, Zh. V.

    2017-02-01

    The applicability of individual Ni, Cu, Au, Pt, and Pd nanoclusters as data bits in next generation memory devices constructed on the phase-change carrier principle is studied. To this end, based on the modified tight-binding potential (TB-SMA), structure formation from the melt of nanoparticles of these metals to 10 nm in diameter was simulated by the molecular dynamics method. The effect of various crystallization conditions on the formation of the internal structures of Ni, Cu, Au, Pt, and Pd nanoclusters is studied. The stability boundaries of various crystalline isomers are analyzed. The obtained systematic features are compared for nanoparticles of copper, nickel, gold, platinum, and palladium of identical sizes. It is concluded that platinum nanoclusters of diameter D > 8 nm are the best materials among studied metals for producing memory elements based on phase transitions.

  5. Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) Alloys for the Hydrogen Separation Membrane.

    PubMed

    Nayebossadri, Shahrouz; Speight, John D; Book, David

    2017-01-25

    Self-supported fcc Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) alloys were studied as potential hydrogen purification membranes. The effects of small additions (1-2.6 at. %) of these elements on the structure, hydrogen solubility, diffusivity, and permeability were examined. Structural analyses by X-ray diffraction (XRD) showed the fcc phase for all alloys with induced textures from cold rolling. Heat treatment at 650 °C for 96 h led to the reorientation in all alloys except the Pd-Cu-Zr alloy, exhibiting the possibility to enhance the structural stability by Zr addition. Hydrogen solubility was almost doubled in the ternary alloys containing Y and Zr compared to Pd65.1Cu34.9 alloy at 300 °C. It was noted that hydrogen diffusivity is decreased upon additions of these elements compared to the Pd65.1Cu34.9 alloy, with the Pd-Cu-Zr alloy showing the lowest hydrogen diffusivity. However, the comparable hydrogen permeability of the Pd-Cu-Zr alloy with the corresponding binary alloy, as well as its highest hydrogen permeability among the studied ternary alloys at temperatures higher than 300 °C, suggested that hydrogen permeation of these alloys within the fcc phase is mainly dominated by hydrogen solubility. Hydrogen flux variations of all ternary alloys were studied and compared with the Pd65.1Cu34.9 alloy under 1000 ppm of H2S + H2 feed gas. Pd-Cu-Zr alloy showed superior resistance to the sulfur poisoning probably due to the less favorable H2S-surface interaction and more importantly slower rate of bulk sulfidation as a result of improved structural stability upon Zr addition. Therefore, Pd-Cu-Zr alloys may offer new potential hydrogen purification membranes with improved chemical stability and hydrogen permeation compared to the binary fcc Pd-Cu alloys.

  6. Hydrazine reduction of metal ions to porous submicro-structures of Ag, Pd, Cu, Ni, and Bi

    SciTech Connect

    Wang Yue; Shi Yongfang; Chen Yubiao; Wu Liming

    2012-07-15

    Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in glycerol-ethanol solution at room temperature or 120-180 Degree-Sign C. Phase purity, morphology, and specific surface area have been characterized. The reactions probably undergo three different mechanisms: simple reduction for Ag and Pd, coordination-then-reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. The reductant hydrazine also plays an important role to the formation of the porous submicro-structure. The reaction temperature influences the size of the constituent particles and the overall architecture of the submicro-structure so as to influence the surface area value. The as-prepared porous metals have shown the second largest surface area ever reported, which are smaller than those made by the reduction of NaBH{sub 4}, but larger than those made by hard or soft template methods. - Graphical abstract: Porous submicro-structures of Ag, Pd, Cu, Ni, and Bi with high surface area have been prepared by the reduction of hydrazine in the glycerol-ethanol solution at room temperature or 120-180 Degree-Sign C. The reactions undergo different mechanisms: simple reduction for Ag and Pd, coordination-then-reduction for Cu and Ni, and hydrolysis-then-reduction for Bi. Highlights: Black-Right-Pointing-Pointer Syntheses of porous Ag, Pd, Cu, Ni, and Bi with high surface area. Black-Right-Pointing-Pointer Ag and Pd undergo simple reduction. Black-Right-Pointing-Pointer Cu and Ni undergo coordination-then-reduction. Black-Right-Pointing-Pointer Bi undergoes hydrolysis-then-reduction. Black-Right-Pointing-Pointer The as-prepared metals have shown the second largest surface area ever reported.

  7. Oxidation Behavior of a Pd43Cu27Ni10P20 Bulk Metallic Glass and Foam in Dry Air

    NASA Astrophysics Data System (ADS)

    Kai, W.; Ren, I. F.; Barnard, B.; Liaw, P. K.; Demetriou, M. D.; Johnson, W. L.

    2010-07-01

    The oxidation behavior of both Pd43Cu27Ni10P20 bulk metallic glass (Pd4-BMG) and its amorphous foam containing 45 pct porosity (Pd4-AF) was investigated over the temperature range of 343 K (70 °C) to 623 K (350 °C) in dry air. The results showed that virtually no oxidation occurred in the Pd4-BMG at T < 523 K (250 °C), revealing the alloy’s favorable oxidation resistance in this temperature range. In addition, the oxidation kinetics at T ≥ 523 K (250 °C) followed a parabolic-rate law, and the parabolic-rate constants ( k p values) generally increased with temperature. It was found that the oxidation k p values of the Pd4-AF are slightly lower than those of the Pd4-BMG, indicating that the porous structure contributes to improving the overall oxidation resistance. The scale formed on the alloys was composed exclusively of CuO at T ≥ 548 K (275 °C), whose thickness gradually increased with increasing temperature. In addition, the amorphous structure remained unchanged at T ≤ 548 K (275 °C), while a triplex-phase structure developed after the oxidation at higher temperatures, consisting of Pd2Ni2P, Cu3P, and Pd3P.

  8. Characterization and Reactivity of Iron Nanoparticles Prepared with Added Cu, Pd, and Ni

    SciTech Connect

    Chun, Chan Lan; Baer, Donald R.; Matson, Dean W.; Amonette, James E.; Penn, Ryland L.

    2010-07-01

    The presence of a secondary metal on iron particles affects redox reactivity in engineered remediation systems. However, the structural characteristics of the metal additives and mechanism responsible for changes in reactivity have not been fully elucidated. Here, we synthesized iron nanoparticles with Cu, Pd, and Ni content ranging from 0-2 mol% via a solution deposition process (SDP), hydrogen reduction process (HRP), or hydrogen reduction of ferrihydrite coprecipitated with the metal cations (HRCO). Results from solid-state characterization show that the synthetic methods produced similar iron core/magnetite shell particles but produced substantial differences in terms of the distribution of the metal additive. In SDP, the metal additives were heterogeneous distributed on the surface of the particles. The metal additives were clearly discernable in TEM images as spherical nanoparticles (2-4 nm) on the HRP and HRCO particles. In addition, we hypothesize that the metal additive is also present as solute within the iron core of the HRCO particles. Kinetic batch experiments of carbon tetrachloride (CT) degradation were performed to quantitatively compare the redox reactivity of the particles. Overall, metal additives resulted in enhanced overall pseudo-first order rate constants of CT degradation (kO,CT) compared to that of the iron nanoparticles. For the bimetallic iron nanoparticles prepared by SDP and HRP, kO,CT increased with the concentration of metal additives. The values of chloroform yield (YCF) were independent of the identity and amount of metal additives. However, both kO,CT and YCF of the HRCO iron particles were significantly greater. Results suggest that it is the distribution of the metal additives that most strongly impacts reactivity and product distribution. For example, for materials with ca. 0.9 50 mol% Ni, reactivity and YCF varied substantially (HRCO>SDP>HRP), and HRCO-NiFe resulted in the lowest final chloroform concentration because the

  9. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

    NASA Astrophysics Data System (ADS)

    Porobova, Svetlana; Markova, Tat'jana; Klopotov, Vladimir; Klopotov, Anatoliy; Loskutov, Oleg; Vlasov, Viktor

    2016-01-01

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen's law.

  10. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

    SciTech Connect

    Porobova, Svetlana Loskutov, Oleg; Markova, Tat’jana; Klopotov, Vladimir; Klopotov, Anatoliy; Vlasov, Viktor

    2016-01-15

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen’s law.

  11. Site preference of ternary alloying additions to NiTi: Fe, Pt, Pd, Au, Al, Cu, Zr and Hf

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Atomistic modeling of the site substitution behavior of Pd in NiTi (J. Alloys and Comp. (2004), in press) has been extended to examine the behavior of several other alloying additions, namely, Fe, Pt, Au, Al, Cu, Zr and Hf in this important shape memory alloy. It was found that all elements, to a varying degree, displayed absolute preference for available sites in the deficient sublattice. How- ever, the energetics of the different substitutional schemes, coupled with large scale simulations indicate that the general trend in all cases is for the ternary addition to want to form stronger ordered structures with Ti.

  12. Oxidation-induced spin reorientation in Co adatoms and CoPd dimers on Ni/Cu(100)

    NASA Astrophysics Data System (ADS)

    Chen, K.; Beeck, T.; Fiedler, S.; Baev, I.; Wurth, W.; Martins, M.

    2016-04-01

    Ultrasmall magnetic clusters and adatoms are of strong current interest because of their possible use in future technological applications. Here, we demonstrate that the magnetic coupling between the adsorbates and the substrate can be significantly changed through oxidation. The magnetic properties of Co adatoms and CoPd dimers deposited on a remanently magnetized Ni/Cu(100) substrate have been investigated by x-ray absorption and x-ray magnetic circular dichroism spectroscopy at the Co L2 ,3 edges. Using spectral differences, pure and oxidized components are distinguished, and their respective magnetic moments are determined. The Co adatoms and the CoPd dimers are coupled ferromagnetically to the substrate, while their oxides, Co-O and CoPd-O, are coupled antiferromagnetically to the substrate. Along with the spin reorientation from the pure to the oxidized state, the magnetic moment of the adatom is highly reduced from Co to Co-O. In contrast, the magnetic moment of the dimer is of similar order for CoPd and CoPd-O.

  13. Microscopic analysis of the composition driven spin-reorientation transition in Ni(x)Pd(1-x)/Cu(001).

    PubMed

    Gottlob, Daniel M; Doğanay, Hatice; Nickel, Florian; Cramm, Stefan; Krug, Ingo P; Nemšák, Slavomír; Schneider, Claus M

    2015-12-01

    The spin-reorientation transition (SRT) in epitaxial NixPd1-x/Cu(001) is studied by photoemission microscopy utilizing the X-ray magnetic circular dichroism effect at the Ni L2,3 edge. In a composition/thickness wedged geometry, a composition driven SRT could be observed between 37 ML and 60 ML, and 0 and 38% of Pd. Microspectroscopy in combination with azimuthal sample rotation confirms a magnetization preference changing from the [001] to an in-plane easy axis. At this increased thickness, the domain patterns arrange comparable to SRTs in ultrathin films. The images document domains equivalent to a canted state SRT, at which an additional effect of in-plane anisotropies could be identified.

  14. An explanation of the differences in diffusivity of the components of the metallic glass Pd43Cu27Ni10P20

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.; Capaccioli, S.

    2013-03-01

    Bartsch et al. [Phys. Rev. Lett. 104, 195901 (2010), 10.1103/PhysRevLett.104.195901] reported measurements of the diffusivities of different components of the multi-component bulk metallic glass Pd43Cu27Ni10P20. The diffusion of the largest Pd and the smallest P was found to be drastically different. The Stokes-Einstein relation breaks down when considering the P constituent atom, while the relation is obeyed by the Pd atom over 14 orders of magnitude of change in Pd diffusivity. This difference in behavior of Pd and P poses a problem challenging for explanation. With the assist of a recent finding in metallic glasses that the β-relaxation and the diffusion of the smallest component are closely related processes by Yu et al. [Phys. Rev. Lett. 109, 095508 (2012), 10.1103/PhysRevLett.109.095508], we use the Coupling Model to explain the observed difference between P and Pd quantitatively. The same model also explains the correlation between property of the β-relaxation with fragility found in the family of (CexLa1-x)68Al10Cu20Co2 with 0 ≤ x ≤ 1.

  15. Diatomite-supported Pd-M (M=Cu, Co, Ni) bimetal nanocatalysts for selective hydrogenation of long-chain aliphatic esters.

    PubMed

    Huang, Changliang; Zhang, Hongye; Zhao, Yanfei; Chen, Sha; Liu, Zhimin

    2012-11-15

    Diatomite supported Pd-M (M=Cu, Co, Ni) bimetal nanocatalysts with various metal compositions were prepared and characterized by means of X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was demonstrated that the metal nanoparticles were uniformly distributed on the support, and their size was centered around 8 nm with a relatively narrow size distribution. The catalysts were used to catalyze hydrogenation of long-chain aliphatic esters, including methyl palmitate, methyl stearate, and methyl laurate. It was indicated that the all diatomite-supported Pd-based bimetal catalysts were active to the selective hydrogenation of long-chain esters to corresponding alcohols at 270°C, originated from the synergistic effect between the metal particles and the diatomite support. For the selective hydrogenation of methyl palmitate, Pd-Cu/diatomite with metal loading of 1% and Pd/Cu=3 displayed the highest performance, giving a 1-hexadecanol yield of 82.9% at the substrate conversion of 98.8%.

  16. Elaborated studies for the ligitional behavior of thiouracil derivative towards Ni(II), Pd(II), Pt(IV), Cu(II) and UO2 ² ions.

    PubMed

    Abou-Melha, Khlood Saad

    2012-11-01

    A synthesis of new thiouracil derivative was carried out and deliberately investigated. A new series of complexes was prepared using Ni(II), Pd(II), Pt(IV), Cu(II) and UO(2)(+2) ions. IR spectral data proposed the coordination mod of the ligand towards each metal ion and displays the binegative pentadentate mod as the maximum mod of coordination obtained with Ni(II) and Cu(II) complexes. (1)HNMR spectrum of UO(2)(+2) complex in comparing with the free ligand spectrum supports the binegative appearance of the coordinated ligand through the ionization of CO and CS groups. The electronic spectral data as well as the magnetic moment measurements are coincide with each others to propose the square-planar geometry with Ni(II), Pd(II) and Cu(II) complexes and octahedral geometry with the others. ESR spectrum of Cu(II) complex displays axially symmetric g tensor parameters with g(11)>g(⊥)>2.0023 indicating that the [Formula: see text] orbital as a ground state with the square-planar geometry. The TG analysis for all isolated complexes were carried out to assert about the presence of water molecules physically or chemically attached with the central atom. The biological study was carried out against different microorganisms as gram negative, gram positive and fungi. The comparable data display the relative priority of Ni(II) complex in comparing with others against all organisms but, the other complexes display activity by the same with the free ligand.

  17. Electrochemical performance and carbon deposition resistance of M-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells

    PubMed Central

    Li, Meng; Hua, Bin; Pu, Jian; Chi, Bo; Jian, Li

    2015-01-01

    Pd-, Cu-, Ni- and NiCu-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ anodes, designated as M-BZCYYb, were prepared by impregnating M-containing solution into BZCYYb scaffold, and investigated in the aspects of electrocatalytic activity for the reactions of H2 and CH4 oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (RΩ) and polarization (RP) losses of BZCYYb anode exposed to H2 or CH4, while Cu impregnation decreased only RΩ in H2 and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3 mol. % H2O) CH4 at 750°C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750°C for 12 h, and not observed in NiCu-BZCYYb exposed to dry CH4 at 750°C for 24 h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd doped CeO2 (LSCF-GDC) cathode was stable at 750°C in wet CH4 for 130 h, indicating that NiCu-BZCYYb is a promising anode for direct CH4 solid oxide fuel cells (SOFCs). PMID:25563843

  18. Coordination behavior of tetraaza [N4] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: Synthesis, spectroscopic characterization and anticancer activity

    NASA Astrophysics Data System (ADS)

    El-Boraey, Hanaa A.

    2012-11-01

    Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N4] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate dx2-y2 ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC50 = 25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.

  19. Crystallization of Zr2PdxCu1-x and Zr2NixCu1-x Metallic Glass

    SciTech Connect

    Xu, Min

    2008-01-01

    One interesting aspect of rretallic glasses is the numerous instances of the deviation of the phase selection from the amorphous state to thermodynamically stable phases during the crystallization process. Their devitrification pathways allow us to study the relationship between the original amorphous structure and their crystalline counter parts. Among the various factors of phase selections, size and electronic effects have been most extensively studied. Elucidating the phase selection process of a glassy alloy will be helpful to fill in the puzzle of the changes from disordered to ordered structures. In this thesis, Two model Zr2PdxCu1-x and Zr2NixCu1-x (x = 0, 0.25, 0.5, 0.75 and 1) glassy systems were investigated since: (1) All of the samples can be made into a homogenous metallic glass; (2) The atomic radii differ from Pd to Cu is by 11%, while Ni has nearly the identical atomic size compare to Cu. Moreover, Pd and Ni differ by only one valence electron from Cu. Thus, these systems are ideal to test the idea of the effects of electronic structure and size factors; (3) The small number of components in these pseudo binary systems readily lend themselves to theoretical modeling. Using high temperature X-ray diffraction (HTXRD) and thermal analysis, topological, size, electronic, bond and chemical distribution factors on crystallization selections in Zr2PdxCu1-x and Zr2NixCu1-x metallic glass have been explored. All Zr2PdxCu1-x compositions share the same Cu11b phase with different pathways of meta-stable, icosahedral quasicrystalline phase (i-phase), and C16 phase formations. The quasicrystal phase formation is topologically related to the increasing icosahedral short range order (SRO) with Pd content in Zr2PdxCu1-x system. Meta-stable C16 phase is competitive with

  20. {sup 45}Sc Solid State NMR studies of the silicides ScTSi (T=Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt)

    SciTech Connect

    Harmening, Thomas; Eckert, Hellmut; Fehse, Constanze M.; Sebastian, C. Peter; Poettgen, Rainer

    2011-12-15

    The silicides ScTSi (T=Fe, Co, Ni, Cu, Ru, Rh, Pd, Ir, Pt) were synthesized by arc-melting and characterized by X-ray powder diffraction. The structures of ScCoSi, ScRuSi, ScPdSi, and ScIrSi were refined from single crystal diffractometer data. These silicides crystallize with the TiNiSi type, space group Pnma. No systematic influences of the {sup 45}Sc isotropic magnetic shift and nuclear electric quadrupolar coupling parameters on various structural distortion parameters calculated from the crystal structure data can be detected. {sup 45}Sc MAS-NMR data suggest systematic trends in the local electronic structure probed by the scandium atoms: both the electric field gradients and the isotropic magnetic shifts relative to a 0.2 M aqueous Sc(NO{sub 3}){sub 3} solution decrease with increasing valence electron concentration and within each T group the isotropic magnetic shift decreases monotonically with increasing atomic number. The {sup 45}Sc nuclear electric quadrupolar coupling constants are generally well reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code. Highlights: Black-Right-Pointing-Pointer Arc-melting synthesis of silicides ScTSi. Black-Right-Pointing-Pointer Single crystal X-ray data of ScCoSi, ScRuSi, ScPdSi, and ScIrSi. Black-Right-Pointing-Pointer {sup 45}Sc solid state NMR of silicides ScTSi.

  1. Atomistic Modeling of Surface and Bulk Properties of Cu, Pd and the Cu-Pd System

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Garces, Jorge E.; Noebe, Ronald D.; Abel, Phillip; Mosca, Hugo O.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    The BFS (Bozzolo-Ferrante-Smith) method for alloys is applied to the study of the Cu-Pd system. A variety of issues are analyzed and discussed, including the properties of pure Cu or Pd crystals (surface energies, surface relaxations), Pd/Cu and Cu/Pd surface alloys, segregation of Pd (or Cu) in Cu (or Pd), concentration dependence of the lattice parameter of the high temperature fcc CuPd solid solution, the formation and properties of low temperature ordered phases, and order-disorder transition temperatures. Emphasis is made on the ability of the method to describe these properties on the basis of a minimum set of BFS universal parameters that uniquely characterize the Cu-Pd system.

  2. Synthesis, antimicrobial activity, structural and spectral characterization and DFT calculations of Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile.

    PubMed

    Mohamed, Tarek A; Shaaban, Ibrahim A; Farag, Rabei S; Zoghaib, Wajdi M; Afifi, Mahmoud S

    2015-01-25

    Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile (APC) have been synthesized and characterized using elemental analysis, magnetic susceptibility, mass spectrometry, infrared (4000-200 cm(-1)), UV-Visible (200-1100 nm), (1)H NMR and ESR spectroscopy as well as TGA analysis. The molar conductance measurements in DMSO imply non-electrolytic complexes, formulated as [M(APC)2Cl2] where M=Co(II), Ni(II), Cu(II) and Pd(II). The infrared spectra of Co(II), Ni(II) and Cu(II) complexes indicate a bidentate type of bonding for APC through the exocyclic amino and adjacent pyrimidine nitrogen as donors whereas APC coordinated to Pd(II) ion as a monodentated ligand via a pyrimidine nitrogen donor. The magnetic measurements and the electronic absorption spectra support distorted octahedral geometries for Co(II), Ni(II) and Cu(II) complexes however a square planar complex was favored for the Pd(II) complex (C2h skeleton symmetry). In addition, we carried out B3LYP and ω-B97XD geometry optimization at 6-31G(d) basis set except for Pd(II) where we implemented LanL2DZ/6-31G(d) combined basis set. The computational results favor all trans geometrical isomers where amino N, pyrimidine N and Cl are trans to each other (structure 1). Finally, APC and its divalent metal ion complexes were screened for their antibacterial activity, and the synthesized complexes were found to be more potent antimicrobial agents than APC against one or more microbial species.

  3. Synthesis, antimicrobial activity, structural and spectral characterization and DFT calculations of Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile

    NASA Astrophysics Data System (ADS)

    Mohamed, Tarek A.; Shaaban, Ibrahim A.; Farag, Rabei S.; Zoghaib, Wajdi M.; Afifi, Mahmoud S.

    2015-01-01

    Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile (APC) have been synthesized and characterized using elemental analysis, magnetic susceptibility, mass spectrometry, infrared (4000-200 cm-1), UV-Visible (200-1100 nm), 1H NMR and ESR spectroscopy as well as TGA analysis. The molar conductance measurements in DMSO imply non-electrolytic complexes, formulated as [M(APC)2Cl2] where M = Co(II), Ni(II), Cu(II) and Pd(II). The infrared spectra of Co(II), Ni(II) and Cu(II) complexes indicate a bidentate type of bonding for APC through the exocyclic amino and adjacent pyrimidine nitrogen as donors whereas APC coordinated to Pd(II) ion as a monodentated ligand via a pyrimidine nitrogen donor. The magnetic measurements and the electronic absorption spectra support distorted octahedral geometries for Co(II), Ni(II) and Cu(II) complexes however a square planar complex was favored for the Pd(II) complex (C2h skeleton symmetry). In addition, we carried out B3LYP and ω-B97XD geometry optimization at 6-31G(d) basis set except for Pd(II) where we implemented LanL2DZ/6-31G(d) combined basis set. The computational results favor all trans geometrical isomers where amino N, pyrimidine N and Cl are trans to each other (structure 1). Finally, APC and its divalent metal ion complexes were screened for their antibacterial activity, and the synthesized complexes were found to be more potent antimicrobial agents than APC against one or more microbial species.

  4. Theoretical insights into the energetics and electronic properties of MPt12 (M = Fe, Co, Ni, Cu, and Pd) nanoparticles supported by N-doped defective graphene

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Tian, Yu; Chen, Guangju; Zhao, Jingxiang

    2017-03-01

    Enhancing the catalytic activity and decreasing the usage of Pt catalysts has been a major target in widening their applications for developing proton-exchange membrane fuel cells. In this work, the adsorption energetics, structural features, and electronic properties of several MPt12 (M = Fe, Co, Ni, Cu, and Pd) nanoparticles (NPs) deposited on N-doped defective graphene were systemically explored by means of comprehensive density functional theory (DFT) computations. The computations revealed that the defective N-doped graphene substrate can provide anchoring site for these Pt-based alloying NPs due to their strong hybridization with the sp2 dangling bonds at the defect sites of substrate. Especially, these deposited MPt12 NPs exhibit reduced magnetic moment and their average d-band centers are shifted away from the Fermi level, as compared with the freestanding NPs, leading to the reduction of the adsorption energies of the O species. Thus, the defective N-doped graphene substrate not only enhances the stability of the deposited MPt12 NPs, but also endows them higher catalytic performance for the oxygen reduction reaction.

  5. Spectroscopic evaluation for VO(II), Ni(II), Pd(II) and Cu(II) complexes derived from thiosemicarbazide: A special emphasis on EPR study and DNA cleavage

    NASA Astrophysics Data System (ADS)

    El-Metwally, Nashwa M.; Al-Hazmi, Gamil A. A.

    2013-04-01

    Some thiosemicarbazide complexes were prepared and deliberately investigated by all allowed tools. The ligand coordinates as a mono negative bidentate towards VO(II) and Ni(II) as well as a neutral bidentate towards Pd(II) and Cu(II) ions. Electronic spectral data beside the magnetic measurements facilitate the structural geometry proposal. EPR spectra of Cu(II) and VO(II) complexes were recorded in their solid state. Spin Hamiltonian parameters and molecular orbital coefficient for Cu(II) and VO(II) complexes were calculated and supporting the octahedral geometry of Cu(II) complex and a square pyramidal for VO(II) one. The biological activity investigation was studied by the use of all prepared compounds. The VO(II) and Cu(II) complexes display the susceptible biotoxicity against a gram-positive bacterium. Also, Cu(II) complex displays the same toxicity against gram-negative bacteria used. The effect of all compounds on DNA were photographed. A successive degradation for the DNA target was observed with Pd(II) and Ni(II) complexes beside their original ligand.

  6. Micro-electrical discharge machining of 3D micro-molds from Pd40Cu30P20Ni10 metallic glass by using laminated 3D micro-electrodes

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Wu, Xiao-yu; Ma, Jiang; Liang, Xiong; Lei, Jian-guo; Wu, Bo; Ruan, Shuang-chen; Wang, Zhen-long

    2016-03-01

    For obtaining 3D micro-molds with better surface quality (slight ridges) and mechanical properties, in this paper 3D micro-electrodes were fabricated and applied to micro-electrical discharge machining (micro-EDM) to process Pd40Cu30P20Ni10 metallic glass. First, 100 μm-thick Cu foil was cut to obtain multilayer 2D micro-structures and these were connected to fit 3D micro-electrodes (with feature sizes of less than 1 mm). Second, under the voltage of 80 V, pulse frequency of 0.2MHZ, pulse width of 800 ns and pulse interval of 4200 ns, the 3D micro-electrodes were applied to micro-EDM for processing Pd40Cu30P20Ni10 metallic glass. The 3D micro-molds with feature within 1 mm were obtained. Third, scanning electron microscope, energy dispersive spectroscopy and x-ray diffraction analysis were carried out on the processed results. The analysis results indicate that with an increase in the depth of micro-EDM, carbon on the processed surface gradually increased from 0.5% to 5.8%, and the processed surface contained new phases (Ni12P5 and Cu3P).

  7. Mixed metal bis(mu-oxo) complexes with [CuM(mu-O)2]n+(M = Ni(III) or Pd(II)) cores.

    PubMed

    Aboelella, Nermeen W; York, John T; Reynolds, Anne M; Fujita, Koyu; Kinsinger, Christopher R; Cramer, Christopher J; Riordan, Charles G; Tolman, William B

    2004-08-07

    Two highly reactive heterodinuclear bis(mu-oxo) complexes were prepared by combining mononuclear peroxo species with reduced metal precursors at -80 degrees C and were identified by UV-vis, EPR/NMR, and resonance Raman spectroscopy, with corroboration in the case of the CuPd system from density functional calculations.

  8. A new approach for simultaneous determination of Co(II), Ni(II), Cu(II) and Pd(II) using 2-thiophenaldehyde-3-thiosemicarbazone as reagent by solid phase microextraction-high performance liquid chromatography.

    PubMed

    Kaur, Varinder; Aulakh, Jatinder Singh; Malik, Ashok Kumar

    2007-11-05

    A new method is proposed herein for the sorption, separation and simultaneous determination of Co(II), Ni(II), Cu(II) and Pd(II) using 2-thiophenaldehyde-3-thiosemicarbazone (TPTS) as a reagent by solid phase microextraction-high performance liquid chromatography-UV detection. The method is based upon the sorption of metal complexes on polydimethylsiloxane (PDMS) fiber from aqueous solution followed by desorption in the desorption chamber of solid phase microextraction-high performance liquid chromatography (SPME-HPLC) interface. Reversed phase high performance liquid chromatography using acetonitrile:water (65:35) as an eluent on a C18 column has been used to achieve the separation. The effects of agitation, addition of salts, extraction time and desorption time are examined to obtain optimized conditions. The detection limits for Co(II), Ni(II), Cu(II) and Pd(II) are 9, 6, 1 and 7 ng L(-1) based on 3sigma of blank response. The precision is calculated to be less than 3.5% (R.S.D.) for all species. A 10 time enhancement in the signal is observed for SPME when compared with direct analysis. The method is successfully applied to several synthetic mixtures without interference from other common metal ions such as Mo(VI), V(V), Ag(I), Sn(IV), Cd(II), Zn(II), Pb(II), Cr(III) and Cr(VI). The proposed method is tested for the determination of Co(II), Ni(II), Cu(II) and Pd(II) in alloys and water samples spiked with these metal ions.

  9. 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.

  10. CO-induced Pd segregation and the effect of subsurface Pd on CO adsorption on CuPd surfaces

    NASA Astrophysics Data System (ADS)

    Padama, A. A. B.; Villaos, R. A. B.; Albia, J. R.; Diño, W. A.; Nakanishi, H.; Kasai, H.

    2017-01-01

    We report results of our study on the adsorption of CO on CuPd surfaces with bulk stoichiometric and nonstoichiometric layers using density functional theory (DFT). We found that the presence of Pd atoms in the subsurface layer promotes the adsorption of CO. We also observed CO-induced Pd segregation on the CuPd surface and we attribute this to the strong CO-Pd interaction. Lastly, we showed that the adsorption of CO promotes Pd-Pd interaction as compared to the pristine surface which promotes strong Cu-Pd interaction. These results indicate that CO adsorption on CuPd surfaces can be tuned by taking advantage of the CO-induced segregation and by considering the role of subsurface Pd atoms.

  11. 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.

  12. Permeation hysteresis in PdCu membranes.

    PubMed

    Yuan, Lixiang; Goldbach, Andreas; Xu, Hengyong

    2008-10-09

    H 2 permeation hysteresis has been observed during cycling of a 3 mum thick supported PdCu membrane with approximately 50 atom % Pd through the fcc/bcc (face-centered cubic/body-centered cubic) miscibility gap between 723 and 873 K. Structural investigations after annealing of membrane fragments under H 2 at 823 K reveal retardation of the fcc(H) --> bcc(H) transition, which is attributed to the occurrence of metastable hydrogenated fcc PdCu(H) phases. The H(2) flux at 0.1 MPa H(2) pressure difference in the well-annealed bcc single phase regime below 723 K can be described by J(H2) = (1.3 +/- 0.2) mol.m (-2).s (-1) exp[(-11.1 +/- 0.6) kJ.mol (-1)/( RT)] and that in the fcc single phase regime above 873 K by J(H2) = (7 +/- 2) mol.m (-2).s (-1) exp[(-30.3 +/- 2.5) kJ.mol (-1)/( RT)].

  13. Intermetallic compounds of the heaviest elements and their homologs: The electronic structure and bonding of MM', where M =Ge, Sn, Pb, and element 114, and M'=Ni, Pd, Pt, Cu, Ag, Au, Sn, Pb, and element 114

    NASA Astrophysics Data System (ADS)

    Pershina, V.; Anton, J.; Fricke, B.

    2007-10-01

    Fully relativistic (four-component) density-functional theory calculations were performed for intermetallic dimers MM', where M =Ge, Sn, Pb, and element 114, and M'=group 10 elements (Ni, Pd, and Pt) and group 11 elements (Cu, Ag, and Au). PbM and 114M, where M are group 14 elements, were also considered. The results have shown that trends in spectroscopic properties—atomization energies De, vibrational frequencies ωe, and bond lengths Re, as a function of M', are similar for compounds of Ge, Sn, Pb, and element 114, except for De of PbNi and 114Ni. They were shown to be determined by trends in the energies and space distribution of the valence ns(M ') atomic orbitals (AOs). According to the results, element 114 should form the weakest bonding with Ni and Ag, while the strongest with Pt due to the largest involvement of the 5d(Pt) AOs. In turn, trends in the spectroscopic properties of MM' as a function of M were shown to be determined by the behavior of the np1/2(M ) AOs. Overall, De of the element 114 dimers are about 1eV smaller and Re are about 0.2a.u. larger than those of the corresponding Pb compounds. Such a decrease in bonding of the element 114 dimers is caused by the large SO splitting of the 7p orbitals and a decreasing contribution of the relativistically stabilized 7p1/2(114) AO. On the basis of the calculated De for the dimers, adsorption enthalpies of element 114 on the corresponding metal surfaces were estimated: They were shown to be about 100-150kJ/mol smaller than those of Pb.

  14. 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.

  15. Coordination of Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II) and Pt(II) with 2,5-hexanedione bis(thiosemicarbazone), HBTS: Crystal structure of cis-[Pd(HBTS)]Cl2 and 1-(2,5-dimethyl-1H-pyrrol-yl)-thiourea

    NASA Astrophysics Data System (ADS)

    Jeragh, Bakir; El-Asmy, Ahmed A.

    2014-09-01

    Metal complexes of Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pd2+ or Pt2+ with 2,5-hexanedione bis(thiosemicarbazone), HBTS; have been prepared and spectroscopically investigated. The empirical formulae of the complexes were suggested based on the elemental analysis. Single crystal of Pd(II) has been solved to be cis-form of square-planar geometry by the X-ray crystallography. 1H and 13C NMR spectra have been recorded for HBTS, Zn(II), Cd(II), Hg(II), Pd(II) and Pt(II) complexes, in DMSO-d6, showing the mode of chelation. The ligand acts as a neutral or a binegative tetradentate (N2S2) or neutral bidentate on the basis of FT-IR. The magnetic moments and electronic spectra provide information about the geometry of the complexes which supported by calculating the ligand field parameters for the Co(II) and Fe(III) complexes. The Ni(II) complex has subnormal magnetic moment (0.71 BM) indicative of a mixed stereochemistry of square-planar and tetrahedral structure. [Cu(HBTS-2H)] measured 0.93 BM indicating high interaction between the copper centers. The ligand may be ordered at the top of the spectrochemical series which giving high ligand field splitting energy (10Dq = 17,900 cm-1 for Co2+ complex). The mass spectra of some complexes proved their stable chemical formulae while the TGA depicts the degradation steps and the final residue. In evaporating the mother liquor during the preparation of HBTS, new compound is obtained naming 1-(2,5-dimethyl-1H-pyrrol-yl)thiourea and its crystal was solved.

  16. PdCu@Pd Nanocube with Pt-like Activity for Hydrogen Evolution Reaction.

    PubMed

    Li, Jing; Li, Feng; Guo, Si-Xuan; Zhang, Jie; Ma, Jiantai

    2017-02-27

    The electronic properties of metal surfaces can be modulated to weaken the binding energy of adsorbed H-intermediates on the catalyst surface, thus enhancing catalytic activity for the hydrogen evolution reaction (HER). Here we first prepare PdCu alloy nanocubes (NCs) by coreduction of Cu(acac)2 (acac = acetylacetonate) and Na2PdCl4 in the presence of oleylamine (OAm) and trioctylphosphine (TOP). The PdCu NC coated glassy carbon electrode is then anodized at a constant potential of 0.51 V vs Ag/AgCl at room temperature in 0.5 M H2SO4 solution for 10 s, which converts PdCu NCs into core@shell PdCu@Pd NCs that show much enhanced Pt-like activity for the HER and much more robust durability. The improvements in surface property and HER activity are rationalized based on strain and ligand effects that enhance the activity of the edge-exposed Pd atoms on core@shell PdCu@Pd structure. This work opens up a new perspective for simultaneously reducing metal Pd cost and achieving excellent performance toward the HER.

  17. Improved ethanol electrooxidation performance by shortening Pd-Ni active site distance in Pd-Ni-P nanocatalysts.

    PubMed

    Chen, Lin; Lu, Lilin; Zhu, Hengli; Chen, Yueguang; Huang, Yu; Li, Yadong; Wang, Leyu

    2017-01-10

    Incorporating oxophilic metals into noble metal-based catalysts represents an emerging strategy to improve the catalytic performance of electrocatalysts in fuel cells. However, effects of the distance between the noble metal and oxophilic metal active sites on the catalytic performance have rarely been investigated. Herein, we report on ultrasmall (∼5 nm) Pd-Ni-P ternary nanoparticles for ethanol electrooxidation. The activity is improved up to 4.95 A per mgPd, which is 6.88 times higher than commercial Pd/C (0.72 A per mgPd), by shortening the distance between Pd and Ni active sites, achieved through shape transformation from Pd/Ni-P heterodimers into Pd-Ni-P nanoparticles and tuning the Ni/Pd atomic ratio to 1:1. Density functional theory calculations reveal that the improved activity and stability stems from the promoted production of free OH radicals (on Ni active sites) which facilitate the oxidative removal of carbonaceous poison and combination with CH3CO radicals on adjacent Pd active sites.

  18. Improved ethanol electrooxidation performance by shortening Pd-Ni active site distance in Pd-Ni-P nanocatalysts

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Lu, Lilin; Zhu, Hengli; Chen, Yueguang; Huang, Yu; Li, Yadong; Wang, Leyu

    2017-01-01

    Incorporating oxophilic metals into noble metal-based catalysts represents an emerging strategy to improve the catalytic performance of electrocatalysts in fuel cells. However, effects of the distance between the noble metal and oxophilic metal active sites on the catalytic performance have rarely been investigated. Herein, we report on ultrasmall (~5 nm) Pd-Ni-P ternary nanoparticles for ethanol electrooxidation. The activity is improved up to 4.95 A per mgPd, which is 6.88 times higher than commercial Pd/C (0.72 A per mgPd), by shortening the distance between Pd and Ni active sites, achieved through shape transformation from Pd/Ni-P heterodimers into Pd-Ni-P nanoparticles and tuning the Ni/Pd atomic ratio to 1:1. Density functional theory calculations reveal that the improved activity and stability stems from the promoted production of free OH radicals (on Ni active sites) which facilitate the oxidative removal of carbonaceous poison and combination with CH3CO radicals on adjacent Pd active sites.

  19. X-ray study of Pd40Cu30Ni10P20 bulk metallic glass brazing filler for Ti-6Al-7Nb alloy

    SciTech Connect

    Miura, E.; Ice, Gene E; Specht, Eliot D; Pang, Judy; Kato, H.; Hisatsune, K.; Inoue, I.

    2007-01-01

    Crystalline precipitates in a bulk-metallic-glass (BMG) braze were investigated with an intense x-ray microbeam. The precipitates were found in the Pd{sub 40}Cu{sub 30}P{sub 20}Ni{sub 10} BMG braze matrix after joining crystalline Ti-6Al-7Nb. However, the role (if any) played by the precipitates in improving the mechanical bond of the BMG/crystalline joint is unknown. X-ray microdiffraction and microfluorescence measurements from small sample volumes were made with an {approx} 0.5 x 0.5 {micro}m2 beam. Spatially-resolved Laue diffraction and x-ray fluorescence measurements were made on several second-phase crystals within the BMG matrix. Although precipitate crystals with the observed compositions were anticipated to be predominantly hexagonal, one of the crystals was found to be cubic or tetragonal. The instrumentation includes capabilities for 3D depth-resolved measurements of crystal structure and for fluorescence analysis of elemental composition. Depth profiling gave information about the grain distribution and morphology in the BMG matrix.

  20. X-ray Study of Pd[subscript 40]Cu[subscript 30]Ni[subscript 10]P[subscript 20] Bulk Metallic Glass Brazing Filler For Ti-6Al-7Nb Alloy

    SciTech Connect

    Miura, E.; Ice, G.E.; Specht, E.D.; Pang, J.W.L.; Kato, H.; Hisatsune, K.; Inoue, A.

    2007-10-02

    Crystalline precipitates in a bulk-metallic-glass (BMG) braze were investigated with an intense x-ray microbeam. The precipitates were found in the Pd{sub 40}Cu{sub 30}P{sub 20}Ni{sub 10} BMG braze matrix after joining crystalline Ti-6Al-7Nb. However, the role (if any) played by the precipitates in improving the mechanical bond of the BMG/crystalline joint is unknown. X-ray microdiffraction and microfluorescence measurements from small sample volumes were made with an {approx} 0.5 x 0.5 {micro}m2 beam. Spatially-resolved Laue diffraction and x-ray fluorescence measurements were made on several second-phase crystals within the BMG matrix. Although precipitate crystals with the observed compositions were anticipated to be predominantly hexagonal, one of the crystals was found to be cubic or tetragonal. The instrumentation includes capabilities for 3D depth-resolved measurements of crystal structure and for fluorescence analysis of elemental composition. Depth profiling gave information about the grain distribution and morphology in the BMG matrix.

  1. Comparative reliability studies and analysis of Au, Pd-coated Cu and Pd-doped Cu wire in microelectronics packaging.

    PubMed

    Chong Leong, Gan; Uda, Hashim

    2013-01-01

    This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (Do) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, β of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.

  2. Cu--Pd--M hydrogen separation membranes

    DOEpatents

    Do{hacek over }an, Omer N; Gao, Michael C; Young, Rongxiang Hu; Tafen, De Nyago

    2013-12-17

    The disclosure provides an H2 separation membrane comprised of an allow having the composition Cu.Sub.(100-x-y)Pd.sub.xM.sub.y, where x is from about 35 to about 50 atomic percent and where y is from greater than 0 to about 20 atomic percent, and where M consists of magnesium, yttrium, aluminum, titanium, lanthanum, or combinations thereof. The M elements act as strong stabilizers for the B2 phase of the allow, and extend the critical temperature of the alloy for a given hydrogen concentration and pressure. Due to the phase stabilization and the greater temperature range over which a B2 phase can be maintained, the allow is well suited for service as a H2 separation membrane, particularly when applicable conditions are established or cycled above about 600.degree. C. over the course of expected operations. In certain embodiments, the B2 phase comprises at least 60 estimated volume percent of the allow at a steady-state temperature of 400.degree. C. The B2 phase stability is experimentally validated through HT-XRD.

  3. Physical Characterization of Cu-Ni-P Thin Films aiming at Cu/Cu-Ni-P Thermocouples

    NASA Astrophysics Data System (ADS)

    Tomachevski, F.; Sparvoli, M.; dos Santos Filho, S. G.

    2015-03-01

    Cu-Ni-P thin films have a high-thermoelectric power, which allows the fabrication of very sensitive heat-flux sensors based on planar technology. In this work, (100) silicon surfaces were pre-activated in a diluted hydrofluoric acid solution containing PdCl2. Following, Cu-Ni-P thin films were chemically deposited using an alkaline chemical bath containing 15 g/l NiSO4.6H2O; 0.2 g/l CuSO4.5H2O; 15 g/l Na2HPO2.H2O and 60 g/l Na3C6H5O7.2H2O at temperature of 80 °C where NH4OH was added until pH was 8.0. It was noteworthy that the stoichiometric percentages of Ni and Cu vary substantially for immersion times in the range of 1 to 3 min and they become almost stable at 50% and 35%, respectively, when the immersion time is higher than 3 min. In addition, the percentage of P remains almost constant around 1718 % for all the immersion times studied. On the other hand, the sheet resistance also varies substantially for immersion times in the range of 1 to 3 min. Based on the surface morphology, smaller grains with size in the range of 0.02 to 0.1 μm are initially grown on the silicon surface and exposed regions of silicon without deposits are also observed for immersion times in the range of 1 to 3min. Therefore, the discontinuities and non uniformities of the films are promoting, respectively, the observed behaviours of sheet resistance and stoichiometry.

  4. 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.

  5. Enhanced formic acid oxidation on Cu-Pd nanoparticles

    NASA Astrophysics Data System (ADS)

    Dai, Lin; Zou, Shouzhong

    Developing catalysts with high activity and high resistance to surface poisoning remains a challenge in direct formic acid fuel cell research. In this work, copper-palladium nanoparticles were formed through a galvanic replacement process. After electrochemically selective dissolution of surface Cu, Pd-enriched Cu-Pd nanoparticles were formed. These particles exhibit much higher formic acid oxidation activities than that on pure Pd nanoparticles, and they are much more resistant to the surface poisoning. Possible mechanisms of catalytic activity enhancement are briefly discussed.

  6. Numerical Prediction of the Thermodynamic Properties of Ternary Al-Ni-Pd Alloys

    NASA Astrophysics Data System (ADS)

    Zagula-Yavorska, Maryana; Romanowska, Jolanta; Kotowski, Sławomir; Sieniawski, Jan

    2016-01-01

    Thermodynamic properties of ternary Al-Ni-Pd system, such as exGAlNPd, µAl(AlNiPd), µNi(AlNiPd) and µPd(AlNiPd) at 1,373 K, were predicted on the basis of thermodynamic properties of binary systems included in the investigated ternary system. The idea of predicting exGAlNiPd values was regarded as calculation of values of the exG function inside a certain area (a Gibbs triangle) unless all boundary conditions, that is values of exG on all legs of the triangle are known (exGAlNi, exGAlPd, exGNiPd). This approach is contrary to finding a function value outside a certain area, if the function value inside this area is known. exG and LAl,Ni,Pd ternary interaction parameters in the Muggianu extension of the Redlich-Kister formalism were calculated numerically using the Excel program and Solver. The accepted values of the third component xx differed from 0.01 to 0.1 mole fraction. Values of LAlNiPd parameters in the Redlich-Kister formula are different for different xx values, but values of thermodynamic functions: exGAlNiPd, µAl(AlNiPd), µNi(AlNiPd) and µPd(AlNiPd) do not differ significantly for different xx values. The choice of xx value does not influence the accuracy of calculations.

  7. London penetration depth measurements in Ba (Fe1-xTx)2As2(T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors

    SciTech Connect

    Gordon, Ryan T.

    2011-01-01

    The London penetration depth has been measured in various doping levels of single crystals of Ba(Fe1-xTx)2As2 (T=Co,Ni,Ru,Rh,Pd,Pt,Co+Cu) superconductors by utilizing a tunnel diode resonator (TDR) apparatus. All in-plane penetration depth measurements exhibit a power law temperature dependence of the form Δλab(T) = CTn, indicating the existence of low-temperature, normal state quasiparticles all the way down to the lowest measured temperature, which was typically 500 mK. Several different doping concentrations from the Ba(Fe1-xTx)2As2 (T=Co,Ni) systems have been measured and the doping dependence of the power law exponent, n, is compared to results from measurements of thermal conductivity and specific heat. In addition, a novel method has been developed to allow for the measurement of the zero temperature value of the in-plane penetration depth, λab(0), by using TDR frequency shifts. By using this technique, the doping dependence of λab(0) has been measured in the Ba(Fe1-xCox)2As2 series, which has allowed also for the construction of the doping-dependent superfluid phase stiffness, ρs(T) = [λ(0)/λ(T)]2. By studying the effects of disorder on these superconductors using heavy ion irradiation, it has been determined that the observed power law temperature dependence likely arises from pair-breaking impurity scattering contributions, which is consistent with the proposed s±-wave symmetry of the superconducting gap in the dirty scattering limit. This hypothesis is supported by the measurement of an exponential temperature dependence of the penetration depth in the intrinsically clean LiFeAs, indicative of a nodeless superconducting gap.

  8. Magnetism and magnetic anisotropy of Ni xPd 1-x alloy

    NASA Astrophysics Data System (ADS)

    Tang, Z. B.; Tian, C. S.; Yin, L. F.; Dong, G. S.; Jin, Xiaofeng

    2007-03-01

    Single-crystalline Ni xPd 1-x thin films with a face-centered cubic structure for the whole stoichiometry 0⩽ x⩽1 have been achieved on Cu(1 0 0) via molecular beam epitaxy (MBE). The ferromagnetism shows up at x⩾0.25 at 300 K and the total magnetization decreases as the Pd concentration increases, which confirms our earlier first-principles calculations (Y.S. Shi, M.F. Wang, D. Qian, G.S. Dong, X.F. Jin, D.S. Wang, J. Magn. Magn. Mater. 277 (2004) 71). The magnetocrystalline anisotropy of Ni xPd 1-x is determined to be cubic with a negative K1, as measured by the magneto-optical Kerr effect (MOKE) technique with a rotating magnetic field (ROTMOKE).

  9. Enhanced hydrogenation and reduced lattice distortion in size selected Pd-Ag and Pd-Cu alloy nanoparticles

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R.; Kulriya, P. K.; Khan, S. A.

    2013-10-21

    Important correlation between valence band spectra and hydrogenation properties in Pd alloy nanoparticles is established by studying the properties of size selected and monocrystalline Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles. The X-ray photoelectron spectroscopy and elastic recoil detection analysis show that size induced Pd4d centroid shift is related to enhanced hydrogenation with H/Pd ratio of 0.57 and 0.49 in Pd-Ag and Pd-Cu nanoparticles in comparison to reported bulk values of 0.2 and 0.1, respectively. Pd-alloy nanoparticles show lower hydrogen induced lattice distortion. The reduced distortion and higher hydrogen reactivity of Pd-alloy nanoparticles is important for numerous hydrogen related applications.

  10. Unravelling the composition of the surface layers formed on Cu, Cu-Ni, Cu-Zn and Cu-Ni-Zn in clean and polluted environments

    NASA Astrophysics Data System (ADS)

    Awad, Nasser K.; Ashour, E. A.; Allam, Nageh K.

    2015-08-01

    The performance of copper and copper-based alloys in working environments is controlled by the composition of the layers formed on their surfaces. Herein, we report the detailed structural and compositional analyses of the layers formed on the surface of Cu, Cu-Ni, Cu-Zn and Cu-Ni-Zn upon their use in both NaCl and Na2S-polluted NaCl solutions. In clean NaCl environments, X-ray photoelectron spectroscopy (XPS) analysis revealed that Cu2O is the major compound formed over the surfaces of pure Cu and Cu-Ni, whereas mixed oxides/hydroxides were detected over the surfaces of Cu-Zn (Cu2O and ZnO) and Cu-Ni-Zn alloy (CuO, ZnO, Cu(OH)2 and Ni(OH)2). However, in Na2S- polluted NaCl environments, sulphide compounds (such as Cu2S) were detected on the surfaces of Cu-Ni and Cu-Zn. X-ray diffraction (XRD) analysis confirmed the XPS findings, where Cu2O was confirmed in case of Cu and CuO in case of Cu-Ni-Zn in pure NaCl solutions. However, in sulphide-polluted media, compounds such as Cu4(S2)2(CuS)2 were identified in case of Cu-Ni, and CuS in case of Cu-Zn. Further, the morphology of the surface of Cu-Ni-Zn tested in Na2S-polluted NaCl solution looks compact and has a wide band gap (4.47 eV) as revealed from the UV-vis absorption measurements. Therefore, the formation of mixed oxides/hydroxides and/or sulphides on the surface of Cu-Ni-Zn alloy is ultimately responsible for the enhancement of its dissolution resistance.

  11. 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.

  12. Cyclic polyvanadates incorporating template transition metal cationic species: synthesis and structures of hexavanadate [PdV6O18]4-, octavanadate [Cu2V8O24]4-, and decavanadate [Ni4V10O30(OH)2(H2O)6]4-.

    PubMed

    Kurata, Taisei; Uehara, Akira; Hayashi, Yoshihito; Isobe, Kiyoshi

    2005-04-04

    Three types of heteropolyvanadates, [(C2H5)4N]4[PdV6O18] (1), [(C2H5)4N]4[Cu2V8O24] (2), and [(C6H5)4P]4[Ni4V10O30(OH)2(H2O)6] (3), were synthesized through the reaction between the [VO3]- anion and metal template cations of Pd(II), Cu(II), and Ni(II). The X-ray crystal structures of 1 (a = 29.952(4) A, b = 12.911(2) A, and c = 13.678(2) A, orthorhombic, space group Pca2(1) with Z = 4), 2 (a = 13.740(1) A, b = 22.488(2) A, c = 18.505(2) A, and beta= 94.058(2) degrees , monoclinic, space group P2(1)/n with Z = 4), and 3 (a = 12.333(2) A, b = 16.208(4) A, c = 16.516(3) A, alpha = 112.438(3) degrees , beta = 94.735(3) degrees , and gamma = 104.749(3) degrees , triclinic, space group P with Z = 1) demonstrate that the metal cationic species induced cyclic [VO3](n-)n (n = 6, 8, 10) ring formation and the cations are incorporated in the rings themselves. In the metal inclusion products, the cyclic vanadates act as macrocyclic ligands, in which the metal cationic species act as the templates. The cyclic vanadate is composed of tetrahedral VO4 units that share corners and incorporates a metal cationic species in the center of the molecules. The bowl-shaped complex 1 includes a Pd2+ cation that is coordinated by the oxygen donors of a boatlike hexavanadate ring. The diamagnetic complex 1 was characterized via 51V and 17O NMR spectroscopy. Complex 2 involves an octavanadate ring and two Cu2+, which are located on both sides of the mean plane as defined by the eight oxygen atoms that bridge the vanadium atoms. In the case of complex 3, the di-mu-hydroxo-bridged Ni2+ dimer with capped Ni2+ aqua ions is formed by hydrolysis to form the decavanadate ring, in which two of the tetrahedral vanadate units are not bonded to the Ni2+ core but supported by hydrogen bonds through the aqua-ligand in the capped Ni2+ cation. Complexes 1-3 in solution were clearly identified by their characteristic isotope patterns using ESI-MS studies.

  13. Investigation of modification of hydrogenation and structural properties of LaNi{sub 5} intermetallic compound induced by substitution of Ni by Pd

    SciTech Connect

    Prigent, J.; Joubert, J.-M.; Gupta, M.

    2011-01-15

    The hydrogenation properties of the LaNi{sub 5} (CaCu{sub 5} type, hP6, P6/mmm) and Pd substituted derivatives LaNi{sub 5-x}Pd{sub x} compounds have been studied in the whole homogeneity range of the solid solution (0.25{<=}x{<=}1.5). The pressure versus hydrogen content isotherms show several plateaus and an increase of the plateau pressure as a function of palladium concentration. The volume increase of the Pd substituted alloys should have resulted in a lowering, and not an increase, of the plateau pressure, according to the conventional models based on the size effect. In order to elucidate the origin of this anomalous behavior, both an experimental and a theoretical ab initio electronic structure investigation have been carried out. Experimentally, the nature and the structural properties of the hydrides have been studied by both in situ and ex situ neutron diffraction. The crystal structures of the three hydride phases are reported (LaNi{sub 3.5}Pd{sub 1.5}D{sub 1.96}, filled-up CaCu{sub 5} type, P6/mmm; LaNi{sub 4}PdD{sub 2.72}, LaNi{sub 2}(Ni{sub 0.75}Pt{sub 0.25}){sub 3}H{sub 2.61} type, oI128, Ibam; LaNi{sub 4.75}Pd{sub 0.25}D{sub 5.67}, partly ordered CaCu{sub 5} type, P6mm). In addition, the phase diagram of LaNi{sub 5-x}Pd{sub x}-H system has been investigated. The electronic and thermodynamic properties of both intermetallic compounds and the hydrides have been studied by ab initio electronic structure calculations. The theoretical results are in good agreement with our experimental data, and show that electronic interactions play a major role in the hydrogenation behavior of these Pd substituted intermetallic compounds, and that these effects cannot be accounted for by a simplistic model based on the size effect alone. -- Graphical abstract: Phase diagram of the system LaNi{sub 5-x}Pd{sub x}-D{sub 2} (absorption) at 25 {sup o}C and 25 bar. Display Omitted

  14. How Deep and Hot was Earth's Magma Ocean? Combined Experimental Datasets for the Metal-silicate Partitioning of 11 Siderophile Elements - Ni, Co, Mo, W, P, Mn, V, Cr, Ga, Cu and Pd

    NASA Technical Reports Server (NTRS)

    Righter, Kevin

    2008-01-01

    variable oxygen fugacity. Preliminary results confirm that D(Ni) and D(Co) converge at pressures near 25-30 GPa and approximately 2200 K, and show that D(Pd) and D(Cu) become too low at the PT conditions of the deepest models. Furthermore, models which force fit V and Cr mantle concentrations by metal-silicate equilibrium overlook the fact that at early Earth mantle fO2, these elements will be more compatible in Mg-perovskite and (Fe,Mg)O than in metal. Thus an intermediate depth magma ocean, at 25-30 GPa, 2200 K, and at IW-2, can explain more mantle siderophile element concentrations than other models.

  15. Theoretical study of NH3 decomposition on Pd-Cu (1 1 1) and Cu-Pd (1 1 1) surfaces: A comparison with clean Pd (1 1 1) and Cu (1 1 1)

    NASA Astrophysics Data System (ADS)

    Jiang, Zhao; Qin, Pei; Fang, Tao

    2016-05-01

    The adsorption and successive dehydrogenation mechanisms of NH3 on Pd-Cu (1 1 1) and Cu-Pd (1 1 1) surfaces (the Pd atoms substitution of the first and second layers of Cu (1 1 1) surfaces) have been systematically investigated by density functional theory (DFT) method with a periodic slab model. All possible adsorption configurations of relevant intermediates on Pd-Cu (1 1 1) and Cu-Pd (1 1 1) surfaces are identified. It is revealed that the adsorption configurations and corresponding adsorption energies of adsorbates are slightly changed on Pd-Cu (1 1 1) and Cu-Pd (1 1 1) surfaces. The adsorption energies of NHx(x = 0-3) species exhibit the following trend: NH3 < NH2 < NH < N. Then, the minimum energy path for the complete dehydrogenation of NH3 into adsorbed N and H is identified to explore the dehydrogenation mechanisms on different surfaces. The highest energy barrier and reaction energy on Pd-Cu (1 1 1) surface are greatly reduced to 1.56 and 0.99 eV, implying that the complete dehydrogenation of NH3 on Pd-Cu (1 1 1) surface is favorable both kinetically and thermodynamically, namely, the doped-Pd atoms in the first layer are the reaction active center. Compared to that on clean Pd (1 1 1) and Cu (1 1 1) surfaces, it is found that the synergistic effect exits in different layers of catalyst surfaces. The calculated results show that the layer-substituted Pd atoms on the surface of Cu catalysts exhibit a better catalytic activity for NH3 dehydrogenation compared to the clean Cu (1 1 1) surface.

  16. Enhanced electrocatalytic performance of Pt monolayer on nanoporous PdCu alloy for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Hou, Linxi; Qiu, Huajun

    2012-10-01

    By selectively dealloying Al from PdxCu20-xAl80 ternary alloys in 1.0 M NaOH solution, nanoporous PdCu (np-PdCu) alloys with different Pd:Cu ratios are obtained. By a mild electrochemical dealloying treatment, the np-PdCu alloys are facilely converted into np-PdCu near-surface alloys with a nearly pure-Pd surface and PdCu alloy core. The np-PdCu near-surface alloys are then used as substrates to fabricate core-shell catalysts with a Pt monolayer as shell and np-PdCu as core by a Cu-underpotential deposition-Pt displacement strategy. Electrochemical measurements demonstrate that the Pt monolayer on np-Pd1Cu1 (Pt/np-Pd1Cu1) exhibits the highest Pt surface-specific activity towards oxygen reduction, which is ˜5.8-fold that of state-of-the-art Pt/C catalyst. The Pt/np-Pd1Cu1 also shows much enhanced stability with ˜78% active surface retained after 10,000 cycles (0.6-1.2 V vs. RHE). Under the same condition, the active surface of Pt/C drops to ˜28%.

  17. Porous bimetallic PdNi catalyst with high electrocatalytic activity for ethanol electrooxidation.

    PubMed

    Feng, Yue; Bin, Duan; Yan, Bo; Du, Yukou; Majima, Tetsuro; Zhou, Weiqiang

    2017-05-01

    Porous bimetallic PdNi catalysts were fabricated by a novel method, namely, reduction of Pd and Ni oxides prepared via calcining the complex chelate of PdNi-dimethylglyoxime (PdNi-dmg). The morphology and composition of the as-prepared PdNi were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Furthermore, the electrochemical properties of PdNi catalysts towards ethanol electrooxidation were also studied by electrochemical impedance spectrometry (EIS), cyclic voltammetry (CV) and chronoamperometry (CA) measurement. In comparison with porous Pd and commercial Pd/C catalysts, porous structural PdNi catalysts showed higher electrocatalytic activity and durability for ethanol electrooxidation, which may be ascribed to Pd and Ni property, large electroactive surface area and high electron transfer property. The Ni exist in the catalyst in the form of the nickel hydroxides (Ni(OH)2 and NiOOH) which have a high electron and proton conductivity enhances the catalytic activity of the catalysts. All results highlight the great potential application of the calcination-reduction method for synthesizing high active porous PdNi catalysts in direct ethanol fuel cells.

  18. First-principles investigation of the structural stability and electronic properties of Pd doped monoclinic Cu6Sn5 intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Shao, Wei-Quan; Lu, Wen-Cai; Chen, Sha-Ou

    2014-12-01

    Tri-layer Au/Pd/Ni(P) films have been widely used as surface finish over the Cu pads in high-end packaging applications. It was found that a thin (Cu,Pd)6Sn5 IMC layer was beneficial in effective reducing inter-diffusion between a Cu substrate and a solder, and therefore the growth of the IMC layer and the EM (electromigration) processes. In this study, the structural properties and phase stability of monoclinic Cu6Sn5-based structures with Pd substitutions were studied by using the first-principles method. The (Cu,Pd)6Sn5 structure with the 4e site substituted by Pd has the lowest heat of formation and is the most stable among (Cu,Pd)6Sn5 structures. Hybridization of Pd-d and Sn-p states is a dominant factor for stability improvement. Moreover, Pd atoms concentration corresponding to the most stable structure of (Cu,Pd)6Sn5 was found to be 1.69 %, which is consistent with the experimental results.

  19. [Mechanical properties of wiredrawn Ag-Pd-Cu alloys].

    PubMed

    Hasegawa, T; Miyagawa, Y; Nakamura, K

    1989-01-01

    Nine experimental Ag-Pd-Cu ternary alloys, containing 20-30 wt% Pd and 10-20 wt% Cu, were cast into rods 4.5 mm in diameter using an original vacuum/argon-pressure oxide-free casting technique. Test samples 2.0 mm in diameter were made from the rods by wire-drawing. After softening and hardening heat treatments, mechanical properties (modulus of elasticity, elastic limit, proof stress, tensile strength, elongation, and Vickers hardness) of the samples were measured to analyze the effects of composition and fifteen sets of correlations between the mechanical properties on the condition that few internal casting defects existed. After softening heat treatment, values of hardness and strength increased with increasing Cu and Pd contents, while they increased approximately with increasing Pd content after hardening heat treatment. After softening and hardening heat treatments, tensile strength ranged from 44.4 to 60.7 and from 68.1 to 89.1 kgf/mm2, respectively. Values of elongation were more than 10% even after hardening heat treatment. Fourteen out of fifteen correlation coefficients (r) were statistically significant (p less than 0.01). One of the regression lines derived was as follows. Tensile strength (kgf/mm2) = 9.1 +/- 0.305 Hv (r = 0.990) Moreover, the mechanical properties observed in this investigation were compared with those of ordinarily cast samples with the same compositions.

  20. Corrosion behavior of Pd-Cu and Pd-Co alloys in synthetic saliva.

    PubMed

    Goehlich, V; Marek, M

    1990-04-01

    Pd-based alloys are major alternatives to gold-based alloys for PFM applications. In electrolytes simulating oral fluids, these alloys exhibit electrode behavior similar to passivity of active metals, i.e., a potential region of almost constant current density up to a critical potential, above which the current increases. The objective of this study was to correlate the electrode behavior with the results of solution analyses and changes in the surface composition of the alloys. Binary alloys Pd-15 wt% Cu and Pd-19 wt% Co, as well as the pure components, were examined. Corrosion potentials vs. time, potentiodynamic anodic polarization curves, polarization resistances vs. time, and potentiostatic anodic charges were measured with synthetic saliva used as the electrolyte. The concentrations of Pd, Cu, and Co in the solution after various exposures were determined by atomic absorption. The surfaces of the alloys were examined by x-ray photoelectron spectroscopy before and after the exposures. The results show that selective dissolution of the less-noble components occurred on the surfaces of both alloys for all the exposures, leaving the surfaces highly enriched in Pd. This enrichment contributed to the potential changes and the passive-type behavior. Copper dissolved more than cobalt at longer exposures and higher potentials, in spite of its higher nobility. Dissolution of cobalt seemed to be limited by the formation of a surface film, which may be related to the transition character of this element.

  1. Electrodeposition of NiPd alloy from aqueous chloride electrolytes

    NASA Astrophysics Data System (ADS)

    Mech, K.; Wróbel, M.; Wojnicki, M.; Mech-Piskorz, J.; Żabiński, P.; Kowalik, R.

    2016-12-01

    Presented results describing properties of alloys deposited at potentiostatic conditions in Ni2+ - Pd2+ - Cl- - H2O system. Electrolysis parameters were defined based on results of thermodynamic analysis as well as voltammetry coupled with electrochemical quartz crystal microbalance (EQCM). Influence of electrode potential and electrolyte components concentration on alloy composition, morphology and its structure was investigated. Alloys were deposited at different Ni(II) and Pd(II) complexes concentrations. Results indicated possibilities of electrochemical synthesis of alloys of wide composition range. Deposits structure as well as crystallites size were discussed based on results of XRD measurements. Alloys composition was determined with the use of energy dispersive spectroscopy (EDS). Morphology of alloys was characterized with the use of scanning electron microscopy (SEM).

  2. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-03-28

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity.

  3. Electrodeposition of PdCu alloy and its application in methanol electro-oxidation

    NASA Astrophysics Data System (ADS)

    Hsieh, Ming-Wei; Whang, Thou-Jen

    2013-04-01

    This study demonstrates a simple electrodeposition method to fabricate the palladium-copper alloy on an ITO coated glass (PdCu/ITO) and its application in methanol electro-oxidation. Our approaches involve the co-reduction of Pd and Cu using triethanolamine (TEA) as a complexing agent in the electroplating bath and a Pd redox replacement of Cu on the surface of the as-prepared PdCu alloy. The phase structures, alloy compositions and morphologies of catalysts are determined by X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy, respectively. X-ray diffraction shows that the particle size of PdCu deposits shrink when the alloy is deposited in a TEA-contained solution. The electrocatalytic properties of PdCu alloys and Pd redox replacement modified PdCu alloys for methanol oxidation have been investigated by cyclic voltammetry. The PdCu alloy with atomic ratio of 20.5% Cu exhibits higher catalytic activity toward methanol oxidation compared with a pure Pd catalyst. PdCu alloys with smaller particle sizes associated with TEA agent and the surface confined Pd replacement are found to have enhanced catalytic performance in the electro-oxidation of methanol.

  4. 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.

  5. [Studies on Pd-Co-Ni dental casting ferromagnetic alloys. (Part I) (author's transl)].

    PubMed

    Harada, H

    1981-04-01

    Many attempts have been made to use magnets as denture retention. But the magnet, such as alnico, ferrite or Pt-Co magnet, is not sufficient for our daily works. Recently, by using the rare earth metal-cobalt magnet, especially Sm-Co magnet, clinicians have gained good results. But magnet, itself, is not good for use in the mouth. Because it is scarcely possible to shape the magnet into suitable forms, it is easy to be broken by masticatory pressure, and its corrosion resistance is not sufficient and so on. To improve these difficulties, Pd-Co-Ni casting alloys which have soft ferromagnetic properties have been developed in this paper. Some metals were added to the alloy to improve the castability of the ferromagnetic alloy. Magnetic properties, range of solidification temperature and castability were examined. As a result, it was found that (43 Pd-27 Co-30 Ni)-10 Au-0.1 Si and (43 Pd-27 Co-30 Ni)-5 Cu-0.1 Si alloy had most excellent properties.

  6. Global optimization of bimetallic cluster structures. I. Size-mismatched Ag-Cu, Ag-Ni, and Au-Cu systems.

    PubMed

    Rapallo, Arnaldo; Rossi, Giulia; Ferrando, Riccardo; Fortunelli, Alessandro; Curley, Benjamin C; Lloyd, Lesley D; Tarbuck, Gary M; Johnston, Roy L

    2005-05-15

    A genetic algorithm approach is applied to the optimization of the potential energy of a wide range of binary metallic nanoclusters, Ag-Cu, Ag-Ni, Au-Cu, Ag-Pd, Ag-Au, and Pd-Pt, modeled by a semiempirical potential. The aim of this work is to single out the driving forces that make different structural motifs the most favorable at different sizes and chemical compositions. Paper I is devoted to the analysis of size-mismatched systems, namely, Ag-Cu, Ag-Ni, and Au-Cu clusters. In Ag-Cu and Ag-Ni clusters, the large size mismatch and the tendency of Ag to segregate at the surface of Cu and Ni lead to the location of core-shell polyicosahedral minimum structures. Particularly stable polyicosahedral clusters are located at size N = 34 (at the composition with 27 Ag atoms) and N = 38 (at the composition with 32 and 30 Ag atoms). In Ag-Ni clusters, Ag32Ni13 is also shown to be a good energetic configuration. For Au-Cu clusters, these core-shell polyicosahedra are less common, because size mismatch is not reinforced by a strong tendency to segregation of Au at the surface of Cu, and Au atoms are not well accommodated upon the strained polyicosahedral surface.

  7. 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.

  8. 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.

  9. Catalytic oxidation of low-concentration CO at ambient temperature over supported Pd-Cu catalysts.

    PubMed

    Wang, Fagen; Zhang, Haojie; He, Dannong

    2014-01-01

    The CO catalytic oxidation at ambient temperature and high space velocity was studied over the Pd-Cu/MOx (MOx = TiO2 and AI203) catalysts. The higher Brunauer-Emmett-Teller area surface of the A1203 support facilitates the dispersion of Pd2+ species, and the presence of Cu2Cl(OH)3 accelerates the re-oxidation of Pd0 to Pd2+ over the Pd-Cu/Al203 catalyst, which contributed to better performance of CO catalytic oxidation. The poorer activity of the Pd-Cu/TiO2 catalyst was attributed to the lower dispersion of Pd2+ species because of the less surface area and the non-formation of Cu2CI(OH)3 species. The presence of saturated moisture showed a negative effect on CO conversion over the two catalysts. This might be because of the competitive adsorption, the formation of carbonate species and the transformation of Cu2CI(OH)3 to inactive CuCI over the Pd-Cu/AI2O3 catalyst, which facilitates the aggregation of PdO species over the Pd-Cu/TiO2 catalyst under the moisture condition.

  10. Effect of Pd precursor status on sonochemical surface activation in Cu electroless deposition

    NASA Astrophysics Data System (ADS)

    Kim, Kanghoon; Jin, Seonok; Kwon, Oh Joong

    2016-02-01

    Pd surface activation via a sonochemical approach was studied by varying Pd precursor status in the aqueous solution. By aging a K2PdCl6 activation solution overnight with added NH4OH, the chlorinated Pd complex was changed to an ammonia-based Pd complex. The Pd surface activation carried out with the NH4OH complexing agent resulted in improved surface condition following Cu electroless deposition. The Cu thin film deposited on a substrate sonochemically activated with the aged, ammonia-based Pd complex showed improved surface roughness and resistivity compared to that for Cu films deposited via two other precursors (chlorinated Pd complex and ammonia-based complex) without aging. In addition, nitrogen purging during sonochemical activation improved Cu film quality.

  11. Oxygen-induced Y surface segregation in a CuPdY ternary alloy

    SciTech Connect

    Tafen, D N.; Miller, J B.; Dogan, O N.; Baltrus, J P.; Kondratyuk, P

    2013-01-01

    We present a comprehensive theoretical and experimental study of the segregation behavior of the ternary alloy CuPdY in vacuum (i.e., the clean surface) and in the presence of oxygen. Theoretical prediction shows that for clean surface, yttrium will substitute first for Cu and then for Pd at the subsurface lattice site before segregating to the surface where it substitutes for Cu. XRD characterization of the surface of CuPdY indicates the presence of two major phases, B2 CuPd and Pd{sub 3}Y. In the presence of adsorbed oxygen, theory predicts that Y preferentially occupies surface sites due to its stronger oxygen affinity compared to Cu and Pd. XPS experiments confirm the computational results in the adsorbed oxygen case, showing that surface segregation of yttrium is induced by the formation of Y-oxides at the top-surface of the alloy.

  12. 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.

  13. X-ray diffraction study of thermal parameters of Pd, Pd-Ag and Pd-Ag-Cu alloys as hydrogen purification membrane materials

    NASA Astrophysics Data System (ADS)

    Pati, Subhasis; Jat, Ram Avtar; Mukerjee, S. K.; Parida, S. C.

    2016-03-01

    High temperature X-ray diffraction measurements were carried out for pure palladium and palladium-rich alloys of compositions Pd0.77Ag0.23 and Pd0.77Ag0.10Cu0.13 in the temperature range of 298-1023 K at an interval of 50 K. The lattice parameters, coefficient of thermal expansion and X-ray Debye temperature of these materials were calculated as a function of temperature from the XRD data. The lattice parameter of Pd0.77Ag0.23 alloy was found to be higher than that of palladium, whereas the lattice parameter of Pd0.77Ag0.10Cu0.13 was found to be lower than that of palladium in the temperature range of investigation. Further, the lattice parameters of both the palladium alloys show negative deviation from Vegard's law and the deviation was found to increase with increase in temperature. The average value of coefficient of linear thermal expansion was found to follow the trend: αT (Pd)>αT (Pd0.77Ag0.23)>αT (Pd0.77Ag0.10Cu0.13). The X-ray Debye temperatures of Pd0.77Ag0.23 and Pd0.77Ag0.10Cu0.13 alloys were calculated and found to be 225±10 and 165±10 K, respectively.

  14. Crystal structure of novel compounds in the systems Zr-Cu-Al, Mo-Pd-Al and partial phase equilibria in the Mo-Pd-Al system.

    PubMed

    Khan, Atta U; Rogl, P; Giester, G

    2012-02-28

    The crystal structures of three Al-rich compounds have been solved from X-ray single crystal diffractometry: τ(1)-MoPd(2-x)Al(8+x) (x = 0.067); τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) and τ(9)-ZrCu(1-x)Al(4) (x = 0.144). τ(1)-MoPd(2-x)Al(8+x) adopts a unique structure type (space group Pbcm; lattice parameters a = 0.78153(2), b = 1.02643(3) and c = 0.86098(2) nm), which can be conceived as a superstructure of the Mo(Cu(x)Al(1-x))(6)Al(4) type. Whereas Mo-atoms occupy the 4d site, Pd(2) occupies the 4c site, Al and Pd(1) atoms randomly share the 4d position and the rest of the positions are fully occupied by Al. A Bärnighausen tree documents the crystallographic group-subgroup relation between the structure types of Mo(Cu(x)Al(1-x))(6)Al(4) and τ(1). τ(7)-Zr(Cu(1-x)Al(x))(12) (x = 0.514) has been confirmed to crystallize with the ThMn(12) type (space group I4/mmm; lattice parameters a = 0.85243(2) and c = 0.50862(3) nm). In total, 4 crystallographic sites were defined, out of which, Zr occupies site 2a, the 8f site is fully occupied by Cu, the 8i site is entirely occupied by Al, but the 8j site turned out to comprise a random mixture of Cu and Al atoms. The compound τ(9)-ZrCu(1-x)Al(4) (x = 0.144) crystallizes in a unique structure type (space group P4/nmm; lattice parameters a = 0.40275(3) and c = 1.17688(4) nm) which exhibits full atom order but a vacancy (14.4%) on the 2c site, shared with Cu atoms. τ(9)-ZrCu(1-x)Al(4) is a superstructure of Cu with an arrangement of three unit cells of Cu in the direction of the c-axis. A Bärnighausen tree documents this relationship. The ZrCu(1-x)Al(4) type (n = 3) is part of a series of structures which follow this building principle: Cu (n = 1), TiAl(3) (n = 2), τ(5)-TiNi(2-x)Al(5) (n = 4), HfGa(2) (n = 6) and Cu(3)Pd (n = 7). A partial isothermal section for the Al-rich part of the Mo-Pd-Al system at 860 °C has been established with two ternary compounds τ(1)-MoPd(2-x)Al(8+x) and τ(2) (unknown structure). The

  15. Microstructure and Corrosion Behavior of the Cu-Pd-X Ternary Alloys for Hydrogen Separation Membranes

    SciTech Connect

    O.N. Dogan; M.C. Gao; B.H. Howard

    2012-02-26

    CuPd alloys are among the most promising candidate materials for hydrogen separation membranes and membrane reactor applications due to their high hydrogen permeability and better sulfur resistance. In order to reduce the Pd content and, therefore, the cost of the membrane materials, efforts have been initiated to develop CuPdM ternary alloys having a bcc structure. The advantages of having Pd as a hydrogen separation membrane are: (1) high hydrogen selectivity; and (2) high hydrogen permeability. The disadvantages are: (1) high cost; (2) hydrogen embrittlement ({alpha} {yields} {beta} Pd hydride); and (3) sulfur poisoning. Experiments (XRD, SEM/EDS) verified that Mg, Al, La, Y and Ti are promising alloying elements to expand the B2 phase region in Cu-Pd binary system. HT-XRD showed that the B2 to FCC transition temperatures for Cu-Pd-X (X = Mg, Al, La, Y and Ti) are higher than that of Cu-Pd binary alloys. While the Cu-50Pd alloy had the highest corrosion resistance to the H2S containing syngas, the Cu-Pd-Mg alloy had a comparable resistance.

  16. Selective Hydrogenation of Phenylacetylene on Bimetallic Cu-Pd and Cu-Pt Catalysts

    NASA Astrophysics Data System (ADS)

    Cladaras, George

    The development of selective catalysts has become a key concept in improving the efficiency of processes. Controlling the product distribution of a reaction can result in fewer by-products and reduce energy requirements for process equipment downstream. The selective hydrogenation of alkynes to alkenes is of major importance to industrial polymerization processes where alkyne/diene impurities can poison the polymerization catalyst and have an unwanted inhibiting effect on the growth of the polymer chain. In many circumstances, bimetallic catalysts have proved to have superior catalytic properties such as greater activity, selectivity or stability compared to their monometallic analogs. A study by the Sykes group (Chemistry, Tufts) in collaboration with our group has shown that in ultra-high vacuum (UHV), the addition of Pd minority species (0.01 ML) onto an otherwise inert Cu(111) single crystal surface can activate the Cu surface for selective hydrogenation reactions. This thesis work is an extension of the surface science study to the preparation of bimetallic catalysts at the nanoscale and their testing in hydrogenation reactions at ambient reaction conditions. The overall aim of this work was to develop single atom alloy Pd-Cu and Pt-Cu catalysts which are highly active and selective for the selective hydrogenation reaction of phenylacetylene to styrene. The bimetallic catalysts were prepared by a colloidal synthesis of Cu nanoparticles immobilized on gamma-alumina support and the precious metals as a minority species were deposited by galvanic replacement. The prepared materials and synthesis technique were characterized with electron microscopy (TEM), UV-Vis spectroscopy, X-Ray diffraction (XRD), temperature programmed reduction (TPR), BET surface area measurements, chemisorption experiments and X-ray photoelectron spectroscopy (XPS). The resulting catalysts can be described as gamma-Al2O3 supported Cu nanoparticles with a narrow size distribution. The Pt/Pd

  17. Development of Pd-Cu/hematite catalyst for selective nitrate reduction.

    PubMed

    Jung, Sungyoon; Bae, Sungjun; Lee, Woojin

    2014-08-19

    A new hematite-supported Pd-Cu bimetallic catalyst (Pd-Cu/hematite) was developed in order to actively and selectively reduce nitrate (NO3(-)) to nitrogen gas (N2). Four different iron-bearing soil minerals (hematite (H), goethite (G), maghemite (M), and lepidocrocite (L)) were transformed to hematite by calcination and used for synthesis of different Pd-Cu/hematite-H, G, M, and L catalysts. Their characteristics were identified using X-ray diffraction (XRD), specific surface area (BET), temperature programed reduction (TPR), transmission electron microscopy with energy dispersive X-ray (TEM-EDX), H2 pulse chemisorption, zeta-potential, and X-ray photoelectron spectroscopy (XPS). Pd-Cu/hematite-H exhibited the highest NO3(-) removal (96.4%) after 90 min, while a lower removal (90.9, 51.1, and 30.5%) was observed in Pd-Cu/hematite-G, M, and L, respectively. The results of TEM-EDX, and TPR analysis revealed that Pd-Cu/hematite-H possessed the closest contact distance between the Cu and Pd sites on the hematite surface among the different Pd-Cu/hematite catalysts. The high removal can be also attributed to the highly active metallic sites on its positively charged surface. The XPS analysis demonstrated that the amount of hydrogen molecules can have a pivotal function on NO3(-) removal and a ratio of nitrogen to hydrogen molecule (N:H) on the Pd sites can critically determine N2 selectivity.

  18. Pd-Cu/poly(o-Anisidine) nanocomposite as an efficient catalyst for formaldehyde oxidation

    SciTech Connect

    Hosseini, Sayed Reza; Raoof, Jahan-Bakhsh; Ghasemi, Shahram; Gholami, Zahra

    2016-08-15

    Highlights: • o-Anisidine monomer was electro-polymerized at the pCPE surface in acid medium. • Palladium/copper NPs were prepared by galvanic replacement method at the POA/pCPE. • Pd-Cu NPs showed excellent electrocatalytic activity towards formaldehyde oxidation. • The bimetallic Pd-Cu NPs/POA nanocomposite showed satisfactory long-term stability. - Abstract: In this work, for the first time, the electrocatalytic oxidation of formaldehyde in 0.5 M sulfuric acid solution at spherical bimetallic palladium-copper nanoparticles (Pd-Cu NPs) deposited on the poly (o-Anisidine) film modified electrochemically pretreated carbon paste electrode (POA/pCPE) has been investigated. Highly porous POA film prepared by electropolymerization onto the pCPE was used as a potent support for deposition of the Pd-Cu NPs. The Pd-Cu NPs were prepared through spontaneous and irreversible reaction via galvanic replacement between Pd{sup II} ions and the Cu{sup 0} particles. The prepared Pd-Cu NPs were characterized by scanning electron microscopy, energy dispersive spectroscopy and electrochemical methods. The obtained results showed that the utilization of Cu nanoparticles and pretreatment technique enhances the electrocatalytic activity of the modified electrode towards formaldehyde oxidation. The influence of several parameters on formaldehyde oxidation as well as stability of the Pd-Cu/POA/pCPE has been investigated.

  19. Effects of Stoichiometry on Transformation Temperatures and Actuator-Type Performance of NiTiPd and NiTiPdX High-Temperature Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Bigelow, Glen S.; Gaydosh, Darrell; Garg, Anita; Padula, Santo A., II; Noebe, Ronald D.

    2007-01-01

    High-temperature shape memory NiTiPd and NiTiPdX (X=Au, Pt, Hf) alloys were produced with titanium equivalent (Ti+Hf) compositions of 50.5, 50.0, 49.5, and 49.0 at.%. Thermo-mechanical testing in compression was used to evaluate the transformation temperatures, transformation strain, work output, and permanent deformation behavior of each alloy to study the effects of quaternary alloying and stoichiometry on high-temperature shape memory alloy behavior. Microstructural evaluation showed the presence of second phases for all alloy compositions. No load transformation temperatures in the stoichiometric alloys were relatively unchanged by Au and Pt substitutions, while the substitution of Hf for Ti causes a drop in transformation temperatures. The NiTiPd, NiTiPdAu and NiTiPdHf alloys exhibited transformation temperatures that were highest in the Ti-rich compositions, slightly lower at stoichiometry, and significantly reduced when the Ti equivalent composition was less than 50 at.%. For the NiTiPdPt alloy, transformation temperatures were highest for the Ti-rich compositions, lowest at stoichiometry, and slightly higher in the Ni-rich composition. When thermally cycled under constant stresses of up to 300 MPa, all of the alloys had transformation strains, and therefore work outputs, which increased with increasing stress. In each series of alloys, the transformation strain and thus work output was highest for stoichiometric or Ti-rich compositions while permanent strain associated with the constant-load thermal cycling was lowest for alloys with Ni-equivalent-rich compositions. Based on these results, basic rules for optimizing the composition of NiTiPd alloys for actuator performance will be discussed.

  20. Electronic and structural influence of Ni by Pd substitution on the hydrogenation properties of TiNi

    SciTech Connect

    Emami, Hoda; Souques, Raphaeel; Crivello, Jean-Claude; Cuevas, Fermin

    2013-02-15

    In Ti (Ni,Pd) compounds, the hydrogen capacity and the stability of their hydrides decreases when Ni is partially substituted by larger in size Pd atoms. To understand this peculiar behaviour, the crystal structure of TiNi{sub 1-x}Pd{sub x}D{sub y} (x=0.1, 0.3 and 0.5) deuterides and the stability of TiNi{sub 1-x}Pd{sub x} (0{<=}x{<=}0.5) intermetallics and their hydrides have been investigated by both neutron diffraction experiments and Density Functional Theory (DFT) calculations. Neutron diffraction shows that at x=0.1 and 0.3, deuterium absorption induces tetragonal distortion in intermetallics sublattice whereas at x=0.5 the cubic symmetry is preserved. The structural properties and the heat of formation of TiNi{sub 1-x}Pd{sub x} (0{<=}x{<=}0.5) intermetallics and their hydrides have been determined by DFT. These results show that Pd substitution increases the stability of the intermetallics and decreases the stability of the hydrides, which confirms the rule of reverse stability. - Graphical abstract: Crystal structure of Ti(Ni,Pd)Hy hydrides in the I4/mmm space group. Highlights: Black-Right-Pointing-Pointer Neutron Diffraction and DFT calculations have been done on TiNi{sub 1-x}Pd{sub x}H{sub y} compounds. Black-Right-Pointing-Pointer Electronic effect of Pd substitution governs the hydrogenation properties in TiNi. Black-Right-Pointing-Pointer The rule of reverse stability in intermetallics/hydrides is observed with Pd substitution. Black-Right-Pointing-Pointer The hydrogen atoms in the I4/mmm structure prefer to occupy the 16n site.

  1. Enhanced formic acid electro-oxidation reaction on ternary Pd-Ir-Cu/C catalyst

    NASA Astrophysics Data System (ADS)

    Chen, Jinwei; Zhang, Jie; Jiang, Yiwu; Yang, Liu; Zhong, Jing; Wang, Gang; Wang, Ruilin

    2015-12-01

    Aim to further reduce the cost of Pd-Ir for formic acid electro-oxidation (FAEO), the Cu was used to construct a ternary metallic alloy catalyst. The prepared catalysts are characterized using XRD, TGA, EDX, TEM, XPS, CO-stripping, cyclic voltammetry and chronoamperometry. It is found that the Pd18Ir1Cu6 nanoparticles with a mean size of 3.3 nm are highly dispersed on carbon support. Componential distributions on catalyst are consistent with initial contents. Electrochemical measurements show that the PdIrCu/C catalyst exhibits the highest activity for FAEO. The mass activity of Pd in Pd18Ir1Cu6/C at 0.16 V (vs. SCE) is about 1.47, 1.62 and 2.08 times as high as that of Pd18Cu6/C, Pd18Ir1/C and Pd/C, respectively. The activity enhancement of PdIrCu/C should be attributed to the weakened CO adsorption strength and the removal of adsorbed intermediates at lower potential with the addition of Cu and Ir.

  2. Magmatic Conduit Metallogenic System in Jinchuan Cu-Ni (PGE) Sulfide Deposit

    NASA Astrophysics Data System (ADS)

    Su, S.; Tang, Z.; Zhou, M.; Song, C.

    2014-12-01

    The Jinchuan Cu-Ni (PGE) sulfide deposit is located in the southwestern margin of North China Craton. Jinchuan ultramafic intrusion hosts the third largest magmatic Cu-Ni deposit in the world. There are mainly four orebodies, namely, orebody-58, orebody-24, orebody-1, and orebody-2, respectively from west to east in the deposit. The primary characteristics of Jinchuan Cu-Ni sulfide deposit are the following: (1) There is an obvious boundary between orebodys and country rocks, usually orebodys intruded into country rocks. (2) "sulfide melts" migrate and settle in the later stage of magma evolution. (3) Fluid Minerals Assemblages are found in the sulfide ores, there is Phl+Cc+Pn+Ccp+Po in orebody-2; Phl+Dol+AP+Pn+Ccp+Po in orebody-24; Q+Mag+AP+Pn+Ccp+Po in orebody-58. (4) Massive sulfides mainly occur in orebody-2, and its PGE content is very rare. Pt-Pd enrichment zones mainly occur in orebody-1; orebody-24 and orebody-58. Ir vs. Ru, Rh, Pt, Pd show positive relationship in orebody-2, but Ir vs. Ru, Rh show positive relationship, Ir vs. Pt, Pd exhibit negative relationship in orebody-1, orebody-24 and orebody-58. The modeling of Ir-Pd shows that the massive sulfide in orebody-2 maybe the origin of MSS. Pt-Pd enrichment zones in orebody-1 orebody-24 and orebody-58 are the relic liquid of monosulfide solid solution segregation; (5) Cu/Ni value is 1.24 in orebody-58, 1.56 in orebody-24, 1.83 in orebody-1, and 2.06 in orebody-2. These features imply that (1) "ore magma" or "melt-fluid bearing metal" formed in the staging chamber in depth; (2) "ore magma" might contain a lot of fluids; (3) "melt-fluid bearing metal" flow moves as a whole; (4) The moving direction of melt-fluid bearing metal flow is form west to east. The ores are enriched in Ni in the front, and enriched in Cu, Pt, Pd in the back of Jinchuan Magmatic Conduit Metallogenic System.

  3. An electrochemical and multispectroscopic study of corrosion of Ag-Pd-Cu-Au alloys.

    PubMed

    Niemi, L; Minni, E; Ivaska, A

    1986-06-01

    Corrosion of a multi-phase Ag-Pd-Cu-Au-based commercial dental casting alloy and a Cu-Pd-rich and Ag-rich single-phase alloy was studied by open-circuit potential measurements, atomic absorption spectrometry, and electron spectroscopy. The alloys were immersed in an artificial saliva solution for 24 hr while the open-circuit potentials of the alloys were measured. The potentials were found to stabilize at certain levels after a steep rise during the first hours of the experiment. Cu was found to dissolve considerably from the Cu-Pd-rich alloy, with simultaneous enrichment of Pd in the surface layer of the alloy. Ag dissolved slightly from the Ag-rich alloy, but both Cu and Ag were found to dissolve from the multi-phase alloy. Neither Pd nor Au dissolved from any of the alloys studied.

  4. Facile synthesis of Cu-Pd bimetallic multipods for application in cyclohexane oxidation

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuo-Qun; Huang, Jianliu; Zhang, Lan; Sun, Mei; Wang, You-Cheng; Lin, Yue; Zeng, Jie

    2014-10-01

    The synergy between Cu and Pd makes Cu-Pd bimetallic nanocrystals interesting materials for investigation. The scarcity of shapes of Cu-Pd bimetallic nanocrystals motivated us to explore highly branched structures, which may promote a wide range of applications. In this communication, we report a facile synthesis of Cu-Pd bimetallic multipods (19.2 ± 1.2 nm), on branches of which some high-index facets were exposed. Modification of reaction parameters concerning capping agents and reductant led to the formation of other shapes, including sphere-like nanocrystals (SNCs). When loaded onto TiO2, the as-prepared Cu-Pd bimetallic multipods exhibited excellent catalytic activity for the oxidation of cyclohexane by hydrogen peroxide and higher selectivity towards cyclohexanone than monometallic catalysts and SNCs/TiO2.

  5. H2 dissociation on individual Pd atoms deposited on Cu(111).

    PubMed

    Ramos, M; Martínez, A E; Busnengo, H F

    2012-01-07

    We present a Molecular Dynamics (MD) study based on Density Functional Theory (DFT) calculations for H(2) interacting with a Pd-Cu(111) surface alloy for low Pd coverages, Θ(Pd). Our results show, in line with recent experimental data, that single isolated Pd atoms evaporated on Cu(111) significantly increase the reactivity of the otherwise inert pure Cu surface. On top of substitutional Pd atoms in the Pd-Cu(111) surface alloy, the activation energy barrier for H(2) dissociation is smaller than the lowest one found on Cu(111) by a factor of two: 0.25 eV vs. 0.46 eV. Also in agreement with experiments, our DFT-MD calculations show that a large fraction of the dissociating H atoms efficiently spillover from Pd (i.e. the active sites), thanks to their extra kinetic energy due to the ~0.50 eV chemisorption exothermicity. Still, our DFT-MD calculations predict a dissociative sticking probability for low energy H(2) molecules that is much smaller than the estimated value from scanning tunneling microscopy experiments. Thus, further theoretical and experimental investigations are required for a complete understanding of H(2) dissociation on low-Θ(Pd) Pd-Cu(111) surface alloys.

  6. Carbon supported Pd-Ni-P nanoalloy as an efficient catalyst for ethanol electro-oxidation in alkaline media

    NASA Astrophysics Data System (ADS)

    Wang, Ye; Shi, Fei-Fei; Yang, Yao-Yue; Cai, Wen-Bin

    2013-12-01

    Carbon-supported well-dispersed Pd-Ni-P ternary catalyst targeted for ethanol oxidation reaction (EOR) in alkaline media is synthesized in a simple aqueous bath containing Pd(II) and Ni(II) salts with sodium hypophosphite as the reducing agent and the source for P and sodium citrate as the complexing agent. XRD analysis on the as-prepared Pd-Ni-P/C reveals that Ni shrinks while P expands the Pd lattice structure, and XPS measurement suggests different electronic effects of the two alloying elements on Pd. Cyclic voltammetry and chronoamperometry indicate that the Pd-Ni-P/C presents a remarkably higher electrocatalytic activity than the state-of-the-art Pd/C, Pd-P/C and Pd-Ni/C catalysts. This may be ascribed to the unique electronic, geometric and bifunctional effects involved in this ternary nanoalloy.

  7. Kinetics of crystal nucleation and growth in Pd(40)Ni(40)P(20) glass

    NASA Technical Reports Server (NTRS)

    Drehman, A. J.; Greer, A. L.

    1984-01-01

    Samples of Pd(40)Ni(40)P(20) glass, produced by cooling the melt at 1 or 800 K/s, are heated in a differential scanning calorimeter to determine the crystallization kinetics. Optical microscopy shows that eutectic crystallization proceeds both by growth from the surface of the samples and by the growth of spherical regions around preexisting nuclei in the interior. A modified Kissinger (1957) analysis is used to obtain the activation energy for crystal growth (3.49 eV). The steady state homogeneous nucleation frequency at 590 K is about 10 million/cu m per sec. This is estimated to be the maximum nucleation frequency: it is too low to account for the observed population of quenched-in nuclei, which are therefore presumed to be heterogeneous. The major practical obstacle to glass formation in this system is heterogeneous nucleation.

  8. Growth of Pt/Cu(100): An Atomistic Modeling Comparison with the Pd/Cu(100) Surface Alloy

    NASA Technical Reports Server (NTRS)

    Demarco, Gustavo; Garces, Jorge E.; Bozzolo, Guillermo

    2002-01-01

    The Bozzolo, Ferrante, and Smith (BFS) method for alloys is applied to the study of Pt deposition on Cu(100). The formation of a Cu-Pt surface alloy is discussed within the framework of previous results for Pd/Cu(100). In spite of the fact that both Pd and Pt share the same basic behavior when deposited on Cu, it is seen that subtle differences become responsible for the differences in growth observed at higher cover-ages. In agreement with experiment, all the main features of Pt/Cu(100) and Pd/Cu(100) are obtained by means of a simple modeling scheme, and explained in terms of a few basic ingredients that emerge from the BFS analysis.

  9. Th7 Fe3 -Type Related Structures in Pd(Pt)-Cu-B Systems: Pd6 CuB3 -A New Structure Type for Borides.

    PubMed

    Salamakha, Leonid P; Sologub, Oksana; Stöger, Berthold; Rogl, Peter F; Waas, Monika; Michor, Herwig; Bauer, Ernst

    2017-02-09

    A new member of the series of Th7 Fe3 -type derivative structures, h-(Pd0.86 Cu0.14 )7 B3 (≡Pd6.02 Cu0.98 B3 , unique structure type Pd6 CuB3 , space group P63 cm, a=12.9426(9) Å, c=4.8697(4) Å, single-crystal X-ray diffraction (XRD) data) was obtained from as cast alloys and alloys annealed at 600-650 °C. Further substitution of Cu by Pd led to formation of a Mn7 C3 -type structure, o-(Pd0.93 Cu0.07 )7 B3 (≡Pd6.51 Cu0.49 B3 , space group Pnma, a=4.8971(2) Å, b=7.5353(3) Å, c=12.9743(6) Å, single-crystal XRD). Isotypic LT h-(Pt0.70 Cu0.30 )7 B3 (≡Pt4.90 Cu2.10 B3 ) was observed in the Pt-Cu-B system as a low-temperature (LT) phase (T≤600 °C) (powder XRD), whereas the Th7 Fe3 -type (high-temperature (HT) h-(Pt0.73 Cu0.27 )7 B3 ≡Pt5.11 Cu1.89 B3 , space group P63 mc, a=7.4671(1) Å, c=4.9039(1) Å, powder XRD) proved to be stable at high temperature. The three structures are built of columns of face connected metal octahedra and columns of metal tetrahedra alternatingly fused by common faces and vertices. Boron atoms are found in trigonal prisms formed by metal atoms. The volumes of the three new Th7 Fe3 -type derivative borides relate as 1:2:3. Superconductivity was discovered for Pt4.9 Cu2.1 B3 (Pd6 CuB3 -type) and Pt5.1 Cu1.9 B3 (Th7 Fe3 -type) below 0.67 and 0.66 K, respectively. Despite the close value of the transition temperature the values of the upper critical field at 0 K differ as 0.37 T and 0.27 T for the two compounds.

  10. Superior hydrogen storage and electrochemical properties of Mg(x)Ni(100-x)/Pd films at room temperature.

    PubMed

    Liu, Tong; Cao, Yurong; Xin, Gongbiao; Li, Xingguo

    2013-10-07

    The Mg(x)Ni(100-x) films of 100 nm have been prepared by magnetron co-sputtering Mg and Ni targets, and a Pd layer of 10 nm was deposited on these films by magnetron sputtering a Pd target. Mg2Ni and MgNi2 are directly generated during the co-sputtering process in the Mg84Ni16/Pd and Mg48Ni52/Pd films. The hydrogen storage properties of the films under 0.1 MPa H2 at 298 K were investigated. The hydrogenation of the Mg84Ni16/Pd film saturates within 45 s and exhibits the faster absorption kinetics compared with Mg94Ni6/Pd and Mg48Ni52/Pd films. The electrochemical properties of the Mg(x)Ni(100-x)/Pd films were investigated in 6 M KOH with a three-electrode cell. The Mg84Ni16/Pd film can be activated just at the first cycle. The maximum discharge capacity of the Mg84Ni16/Pd film is 482.7 mAh g(-1), the highest among these films.

  11. Structure and Gas-Phase Thermochemistry of a Pd/Cu Complex: Studies on a Model for Transmetalation Transition States.

    PubMed

    Oeschger, Raphael J; Chen, Peter

    2017-01-25

    A heterobimetallic Pd(II)/Cu(I) complex was prepared and characterized by X-ray diffraction analysis. The crystal structure shows a remarkably short Pd-Cu bond and a trigonal ipso carbon atom. The Pd-Cu interaction, as determined by energy-resolved collision-induced dissociation cross-section experiments, models the net stabilizing energy of the Pd-Cu interaction in the transition state of the transmetalation step in Pd/Cu-catalyzed cross-coupling reactions. The bonding situation in the bimetallic dinuclear complex has been studied by atoms-in-molecules analysis.

  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. Catalytic reduction of 4-nitrophenol over Ni-Pd nanodimers supported on nitrogen-doped reduced graphene oxide.

    PubMed

    Liu, Lijun; Chen, Ruifen; Liu, Weikai; Wu, Jiamin; Gao, Di

    2016-12-15

    Catalytic reduction of toxic 4-nitrophenol to 4-aminophenol over magnetically recoverable nanocatalysts has attracted much attention. Herein, we report a Ni-Pd/NrGO catalyst through the growth of Ni-Pd nanodimers (NDs) on nitrogen-doped reduced graphene oxide (NrGO). The Ni-Pd NDs show a heterogeneous nanostructure with Ni and Pd subparts contacting with each other, remarkably different from the frequently-observed core/shell nanoparticles (NPs) or nanoalloy. The formation of Ni-Pd NDs follows an initial deposition of Pd NPs on the graphene and in-situ catalytic generation of Ni subparts over the newly-generated Pd NPs. The resulting Ni-Pd/NrGO exhibits a superior catalytic activity towards the reduction of 4-nitrophenol at room temperature with a high rate constant (3400s(-1)g(-1)) and a low activated energy (29.1kJmol(-1)) as compared to unsupported Ni-Pd NDs and supported monometallic catalysts. The conversion rate of 4-NP is calculated to be 99.5% and the percent yield (%) of 4-AP is as high as 99.1%. A synergistic catalysis mechanism is rationally proposed, which is ascribed to the electronic modification of Ni-Pd metals due to the strong metal/support interaction (SMSI) effect as well as the electron transfer between Ni and Pd. The hybrid catalyst shows soft ferromagnetic properties and can be magnetically separated and recycled without obvious loss of activity.

  14. Nitrate removal by Fe0/Pd/Cu nano-composite in groundwater.

    PubMed

    Liu, Hongyuan; Guo, Min; Zhang, Yan

    2014-01-01

    Nitrate pollution in groundwater shows a great threat to the safety of drinking water. Chemical reduction by zero-valent iron is being considered as a promising technique for nitrate removal from contaminated groundwater. In this paper, Fe0/Pd/Cu nano-composites were prepared by the liquid-phase reduction method, and batch experiments of nitrate reduction by the prepared Fe0/Pd/Cu nano-composites under various operating conditions were carried out. It has been found that nano-Fe0/Pd/Cu composites processed dual functions: catalytic reduction and chemical reduction. The introduction of Pd and Cu not only improved nitrate removal rate, but also reduced the generation of ammonia. Nitrate removal rate was affected by the amount of Fe0/Pd/Cu, initial nitrate concentration, solution pH, dissolved oxygen (DO), reaction temperature, the presence of anions, and organic pollutant. Moreover, nitrate reduction by Fe0/Pd/Cu composites followed the pseudo-first-order reaction kinetics. The removal rate of nitrate and total nitrogen were about 85% and 40.8%, respectively, under the reaction condition of Fe-6.0%Pd-3.0%Cu amount of 0.25 g/L, pH value of 7.1, DO of 0.42 mg/L, and initial nitrate concentration of 100 mg/L. Compared with the previous studies with Fe0 alone or Fe-Cu, nano-Fe-6%Pd-3%Cu composites showed a better selectivity to N2.

  15. 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.

  16. Corrosion behavior of Au and Ag modified Cu-Ni-Mn alloys.

    PubMed

    Wright, S R; Cocks, F H; Gettleman, L

    1980-04-01

    The linear electrochemical polarization method was used to provide quantitative in vitro measurements of corrosion rates as a function of exposure time for Cu-Ni-Mn, Cu-Ni-Mn-Au, Cu-Ni-Mn-Ag, and Cu-Ni-Mn-Au-Ag alloys in artificial saliva. Both Au and Ag additives to dental-cast Cu-Ni-Mn alloys lowered the corrosion rate significantly.

  17. Selective Cu4Pd alloy nanoparticles anchoring on amine functionalized graphite nanosheets and their use as reusable catalysts for a C-C coupling reaction with the sacrificial role of Cu for Pd-regeneration.

    PubMed

    Chakravarty, Amrita; De, Goutam

    2016-08-02

    A facile method for the synthesis of phase selective alloy nanoparticles (NPs), Cu4Pd and their in situ anchoring on the surface of amine functionalized graphite nanosheets (AFGNS) by solvothermal process has been demonstrated. It has been seen that upon adding CuCl2·H2O and PdCl2 into the reaction medium containing AFGNS, the -NH2 group initially helps to immobilize Cu(2+) ions from CuCl2·H2O. During the solvothermal reaction in presence of N,N-dimethylformamide (DMF; solvent cum reducing agent) Pd(2+) gets reduced first due to its higher reduction potential. These Pd NPs in turn help in the reduction of Cu(2+) to Cu in an epitaxial manner. Finally at high temperature and long reaction time Cu and Pd combine to form the Cu4Pd alloy NPs along with a small fraction of Cu NPs. The conditions to obtain Cu4Pd NPs have been optimized through controlled reactions. The as prepared Cu4Pd@AFGNS composite has been successfully used for Suzuki-Miyuara C-C coupling reaction with sufficiently high yield and reusability of up to five cycles. The progress of the reaction was monitored using a fluorimeter. Interestingly, it has been observed that the small fraction of the Cu NPs present in the system played a sacrificial role in regenerating metallic Pd NPs in the first and second reaction cycles, followed by Cu from the Cu4Pd alloy itself from the third cycle onwards which played the sacrificial role to regenerate Pd(0). A probable reaction mechanism of the catalytic reaction with Cu4Pd@AFGNS has been suggested.

  18. Au-segregated dealloying and Pd-induced clock reconstructing of Cu(001)

    NASA Astrophysics Data System (ADS)

    Shen, Y. G.; Yao, J.; O'Connor, D. J.; King, B. V.; MacDonald, R. J.

    1996-07-01

    The structure and growth of ultrathin Au and Pd films on Cu(001) have been studied by low-energy ion scattering (LEIS) and low-energy electron diffraction (LEED). Due to the existence of a kinetic pathway for intermixing, both Au and Pd are incorporated into the Cu(001) surface at room temperature, forming a 0953-8984/8/27/004/img1 surface alloy at a coverage of 0.5 monolayer (ML). At Au coverage near 1.2 ML, the surface layer is pure Au; this is caused by Au-induced segregation from the underlying 0953-8984/8/27/004/img1 layer to the surface. No second- and/or third-layer Au is evident. In contrast to this, for the Pd/Cu(001) case a 0953-8984/8/27/004/img3 clock reconstruction is formed after deposition of 1 ML Pd. The LEIS data, through comparisons with 3-D computer simulation, reveal a 0.25 Å lateral clockwise - anticlockwise displacement of the first-layer Pd atoms. A simple model for this clock reconstruction is proposed. The driving force behind the dealloying for the Cu - Au alloy and Pd-induced reconstructing for the Cu - Pd surface is also discussed.

  19. Solid phase metallurgy strategy to sub-5 nm Au-Pd and Ni-Pd bimetallic nanoparticles with controlled redox properties.

    PubMed

    Tang, Yu; Xu, Shaodan; Dai, Yihu; Yan, Xiaoqing; Li, Renhong; Xiao, Liping; Fan, Jie

    2014-01-07

    A solid phase metallurgy strategy is applied to synthesize Au-Pd and Ni-Pd bimetallic nanoparticles (BMNPs) with a tight sub-5 nm particle size distribution. The near-surface elemental composition and redox properties of Au-Pd BMNPs can be well tailored, which leads to an optimized catalytic performance in n-hexane combustion.

  20. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    SciTech Connect

    Cai, Fan; Yang, Lefu; Shan, Shiyao; Mott, Derrick; Chen, Bing H.; Luo, Jin; Zhong, Chuan-Jian

    2016-06-30

    Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with a Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Lastly, we discussed the implications of the results to the refinement of the preparation of the alloy nanocatalysts.

  1. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    DOE PAGES

    Cai, Fan; Yang, Lefu; Shan, Shiyao; ...

    2016-06-30

    Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with amore » Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Lastly, we discussed the implications of the results to the refinement of the preparation of the alloy nanocatalysts.« less

  2. Vibrations on Cu surfaces covered with Ni monolayer

    NASA Astrophysics Data System (ADS)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1999-08-01

    Vibrational modes on the Cu(100) and Cu(111) surfaces covered with a Ni monolayer have been calculated using the embedded-atom method. A detailed discussion of the dispersion relations and polarizations of adsorbate modes and surface phonons is presented. The dispersion of the Rayleigh phonon is in good agreement with the experimental EELS data. The changes in interatomic force constants are discussed.

  3. Magnetic interlayer coupling between Co films across Cu/Ni30Cu70/Cu(100) double quantum wells

    SciTech Connect

    Zhang, Z.D.; Choi, H.J.; Kawakami, R.K.; Escorcia-Aparicio, E.J.; Bowen, M.O.; Rotenberg, E.; Smith, N.V.; Qiu, Z.Q.

    1999-05-18

    Magnetic interlayer coupling between two Co layers across Cu/Ni 30 Cu 70 /Cu(100) was investigated by the surface magneto-optic Kerr effect. The Ni 30 Cu 70 layer at the center of the Cu layer was shown to shift the peak positions, rather than to change the strength, of the magnetic interlayer coupling. The density of states near the Fermi level was investigated by photoemission spectroscopy. We show that the peak-position shift in the magnetic interlayer coupling is associated with the quantum-well behavior in a symmetric double-quantum-well system. The phase accumulation model was applied to explain the results quantitatively.

  4. Microwave absorption of electroplated NiFeCu/Cu multilayers deposited directly on Si (100) substrates

    NASA Astrophysics Data System (ADS)

    Silva, B. G.; Gonzalez-Chavez, D. E.; Filho, J. Gomes; Sommer, R. L.

    2016-12-01

    We study the magnetic properties and broadband microwave absorption of electroplated NiFeCu/Cu multilayered thin films deposited directly on Si (100) substrates. We produced samples with 20 nm thick NiFeCu layers and Cu layer thickness tCu in the range 0-2.8 nm. Structural properties were studied by grazing incidence X-ray diffraction (GIXRD), while the composition and morphological aspects were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). GIXRD confirmed the cubic face centered FCC phase of NiFeCu with all diffraction peaks drifting toward lower angles with tCu. SEM images show the appearance of Cu islands instead of continuous Cu layers. A minimum coercive field of 1.4 Oe is obtained for tCu = 1.0 nm, while the ferromagnetic resonance linewidth exhibited 200 Oe constant values for tCu between 0.7 and 2.1 nm. The effective magnetization increases with tCu, possibly associated to the increase on Fe content as observed by EDX. The effective dynamic anisotropy behavior with tCu seems to be associated to the island structure observed in the films.

  5. Investigation of Pd-Modified Ag-CuO Air Braze Filler Metals

    SciTech Connect

    Darsell, Jens T.; Hardy, John S.; Kim, Jin Yong; Weil, K. Scott

    2006-01-10

    Palladium was added as a ternary component to a series of silver - copper oxide alloys in an effort to increase the use temperature of these materials for potential ceramic air brazing applications. Large portions of the silver component of the Ag-CuO system were substituted by palladium forming the following alloys: (100-y)[(100-z)Pd - (z)Ag] - (y)CuOx where y = 0 - 34 mol% CuOx, z = 50 - 100 mol% silver, and x = 0, 0.5, and 1, denoting copper metal, Cu2O, or CuO. From differential scanning calorimetry, it was determined that the addition of palladium causes an increase in the solidus and liquidus temperatures of the resulting Pd-Ag-CuO brazes. In general, the liquidus was found to increase by approximately 220°C for the (100-y)(25Pd - 75Ag) - (z)CuOx filler metal compositions relative to comparable Ag-CuOx alloys. Likewise, the solidus was found to increase for these alloys, respectively by 185°C and 60°C, respectively for CuOx contents of y = 0 - 1mol% and 4 - 10 mol%. For the (100-y)(50Pd - 50Ag) - (y)CuOx alloys, the solidus increased between 280 - 390°C over a copper oxide compositional range of x = 0 to 8 mol%. It was determined from sessile drop experiments that palladium causes an increase in the wetting angle for all of the samples tested. Alloy compositions of (100-y)(25Pd - 75Ag) - (y)CuOx displayed increased wetting angles of 5-20° relative to comparable binary compositions. (100-y)(50Pd - 50Ag) - (y)CuOx alloys exhibited an increase in contact angle of 10-60° and compositions containing less than 10 mol% CuOx were not able to wet the substrate. Scanning electron microscopy indicates that the microstructure of the braze consists of Ag-Pd solid solution with CuOx precipitates. In general, a reaction layer consisting of CuAlO2 forms adjacent to the alumina substrate. However, the formation of this layer is apparently hindered by the addition of large amounts of palladium, causing poor wetting behavior, as denoted by substantial porosity found along

  6. 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.

  7. 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.

  8. Spectral studies on sulfur poisoning of Pd/Mg6Ni by NEXAFS and XPS

    NASA Astrophysics Data System (ADS)

    Yagi, S.; Nambu, M.; Tsukada, C.; Ogawa, S.; Kutluk, G.; Namatame, H.; Taniguchi, M.

    2013-02-01

    We have studied on the hydrogen storage materials based on Mg-Ni alloy and fabricated the sample constructed with the Pd thin layer (TL) on Mg6Ni alloy substrate. The adsorption behavior of the dimethyl disulfide (DMS) molecules on the sample has been measured to reveal the sulfur poisoning of the Pd TL/Mg6Ni by means of XPS and Sulfur K-edge NEXAFS techniques. The chemisorbed DMS, methanethiolate (MT) and atomic S have been observed on the surface. Especially, it is clear that some atomic S has been oxidized by air and detected the adsorbate of the SO32- and SO42- species. During exposure to the atmosphere, most of the adsorbed DMS and MT adsorbates desorb from the Pd TL surface. We thus conclude the Pd TL might be able to prevent the hydrogen storage materials from the sulfur poisoning.

  9. Modified Ni-Cu catalysts for ethanol steam reforming

    SciTech Connect

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

    2013-11-13

    Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N{sub 2} adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

  10. Squeezing and stretching Pd thin films: A high-resolution STM study of Pd/Au(111) and Pd/Cu(111) bimetallics

    NASA Astrophysics Data System (ADS)

    Blecher, Mishan E.; Lewis, Emily A.; Pronschinske, Alex; Murphy, Colin J.; Mattera, Michael F. G.; Liriano, Melissa L.; Sykes, E. Charles H.

    2016-04-01

    Pd bimetallic alloys are promising catalysts, especially for heterogeneous reactions involving hydrogen, as they exhibit increased activity and reduced demand for expensive precious metals. Using scanning tunneling microscopy, we examine the structure of Pd thin films on Cu(111) and Au(111) and demonstrate compression and expansion, respectively, of the bulk Pd lattice constant in the film. The relative binding strength of H to the two surfaces, inferred via tip-induced diffusion barriers, suggests that the strain in these systems may alter adsorbate binding and corroborates well-known trends in d-band shifts calculated by the density functional theory. Modification to the topography and activity of Pd films based on the choice of substrate metal illustrates the value of bimetallic systems for designing less expensive, tunable catalysts.

  11. Magnetron sputtered Cu3N/NiTiCu shape memory thin film heterostructures for MEMS applications

    NASA Astrophysics Data System (ADS)

    Kaur, Navjot; Choudhary, Nitin; Goyal, Rajendra N.; Viladkar, S.; Matai, I.; Gopinath, P.; Chockalingam, S.; Kaur, Davinder

    2013-03-01

    In the present study, for the first time, Cu3N/NiTiCu/Si heterostructures were successfully grown using magnetron sputtering technique. Nanocrystalline copper nitride (Cu3N with thickness 200 nm) thin films and copper nanodots were subsequently deposited on the surface of 2-μm-thick NiTiCu shape memory thin films in order to improve the surface corrosion and nickel release properties of NiTiCu thin films. Interestingly, the phase transformation from martensite phase to austenite phase has been observed in Cu3N/NiTiCu heterostructures with corresponding change in texture and surface morphology of top Cu3N films. Field emission scanning electron microscopy and atomic force microscope images of the heterostructures reveals the formation of 20-nm-sized copper nanodots on NiTiCu surface at higher deposition temperature (450 °C) of Cu3N. Cu3N passivated NiTiCu films possess low corrosion current density with higher corrosion potential and, therefore, better corrosion resistance as compared to pure NiTiCu films. The concentration of Ni released from the Cu3N/NiTiCu samples was observed to be much less than that of pure NiTiCu film. It can be reduced to the factor of about one-ninth after the surface passivation resulting in smooth, homogeneous and highly corrosion resistant surface. The antibacterial and cytotoxicity of pure and Cu3N coated NiTiCu thin films were investigated through green fluorescent protein expressing E. coli bacteria and human embryonic kidney cells. The results show the strong antibacterial property and non cytotoxicity of Cu3N/NiTiCu heterostructure. This work is of immense technological importance due to variety of BioMEMS applications.

  12. Cu multiply twinned particle precipitation in low-temperature fired Ni-Zn-Cu ferrite

    NASA Astrophysics Data System (ADS)

    Fujimoto, Masayuki; Hoshi, Ken-Ichi; Nakazawa, Mutsuo; Sekiguchi, Shoichi

    1993-12-01

    Cu metal precipitates and truncated Cu metal multiply twinned particles (MTPs) were observed in low-temperature fired ferrite with a small excess of Ni-Zn-Cu chemical composition. The Cu metal precipitates suggest the existence of Cu solid solution and accelerated grain growth during the sintering accompanied with the formation of defect structures, such as oxygen vacancies in the ferrite spinel structure. The defect structure compensation during the cooling process after sintering results in Cu metal precipitation at the multiple grain junction.

  13. Cu Multiply Twinned Particle Precipitation in Low-Temperature Fired Ni-Zn-Cu Ferrite

    NASA Astrophysics Data System (ADS)

    Fujimoto, Masayuki; Hoshi, Ken-ichi; Nakazawa, Mutsuo; Sekiguchi, Shoichi

    1993-12-01

    Cu metal precipitates and truncated Cu metal multiply twinned particles (MTPs) were observed in low-temperature fired ferrite with a small excess of Ni-Zn-Cu chemical composition. The Cu metal precipitates suggest the existence of Cu solid solution and accelerated grain growth during the sintering accompanied with the formation of defect structures, such as oxygen vacancies in the ferrite spinel structure. The defect structure compensation during the cooling process after sintering results in Cu metal precipitation at the multiple grain junction.

  14. Precipitation Behavior of Thermo-Mechanically Treated Ti50Ni20Au20Cu10 High-Temperature Shape-Memory Alloy

    NASA Astrophysics Data System (ADS)

    Kayani, Saif Haider; Imran Khan, M.; Khalid, Fazal Ahmad; Kim, Hee Young; Miyazaki, Shuichi

    2016-03-01

    In the present work, precipitation behavior of TiNiAuCu-based high-temperature shape-memory alloys is studied. Two alloys with compositions Ti50Ni30Au20 and Ti50Ni20Au20Cu10 were prepared. After 30 % cold rolling, both alloys were then annealed at different temperatures. Formation of Cu-rich TiAuCu and Ti-rich Ti3Au precipitates was observed in Ti50Ni20Au20Cu10 alloy when annealed at different temperatures after cold deformation. It was noticed that prior cold deformation has significant effect on the precipitation behavior. A similar kind of precipitation behavior has been previously reported in TiNiPdCu alloys. Both TiAuCu and Ti3Au type precipitates were found to be deficient in Ni content which causes an increase in Ni content of the matrix and a small decrease in transformation temperatures of the Ti50Ni20Au20Cu10 alloy.

  15. Vibrational properties of Cu(100)-c(2×2)-Pd surface and subsurface alloys

    NASA Astrophysics Data System (ADS)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    2003-07-01

    Using interaction potentials from the embedded-atom method we investigated the structural and vibrational properties of a Cu(100)-c(2×2)-Pd surface alloy and an underlayer c(2×2) alloy with a mixed CuPd second layer. The calculated surface phonon frequencies are in agreement with the experimental values obtained by electron energy-loss spectroscopy. From the calculated local phonon densities of states we find that surface effects are most pronounced in the first two layers for both systems studied. The results also indicate a very strong Pd-Cu bonding accompanied by a weaker bonding of the Cu surface atoms to their nearest neighbors. This has considerable influence on the surface phonon frequencies.

  16. Ten metal complexes of vitamin B3/niacin: Spectroscopic, thermal, antibacterial, antifungal, cytotoxicity and antitumor studies of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), Pt(IV) and Au(III) complexes

    NASA Astrophysics Data System (ADS)

    Al-Saif, Foziah A.; Refat, Moamen S.

    2012-08-01

    Ten coordination compounds, namely Mn(NA)2Cl2·4H2O (1), Fe(NA)Cl3(H2O)2 (2), Co(NA)2(NO3)2·6H2O (3), Ni(NA)Cl2·5H2O (4), Cu(NA)Cl2·3H2O (5), Zn(NA)(NO3)2·H2O (6), Pd(NA)2Cl2·H2O (7), Cd(NA)Cl2·H2O (8), Pt(NA)2Cl4·5H2O (9) and Au(NA)Cl3 (10) were obtained by the reactions of the corresponding transition metal salts with vitamin B3/niacin (NA) in the presence of 1:4 (v:v) distilled water: methanol solvent at 70 °C for about 30 min, and their suggested structures were determined by elemental analyses, molar conductivity, (infrared, UV-vis) spectra, effective magnetic moment in Bohr magnetons, electron spin resonance (ESR), thermal analysis (TG), X-ray powder diffraction (XRD) as well as scanning electron microscopy (SEM). The results revealed that in complexes 1, 3, 7, and 9 both of two NA ligand coordinates one metal ion to form four or six coordinated structures, while in compound 10, one NA ligand coordinate to Au+++ ion to form a square-planar geometry with N-bonded pyridine ligand is suggested, and (2, 4, 5, 6 and, 8) complexes have 1:1 structures. Antimicrobial and antitumor activities were assessment against some kind of (G+ and G-) bacteria, fungi and breast carcinoma cells (MCF-7-cell line).

  17. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid

    PubMed Central

    Assaud, Loïc; Monyoncho, Evans; Pitzschel, Kristina; Allagui, Anis; Petit, Matthieu; Hanbücken, Margrit

    2014-01-01

    Summary Three-dimensionally (3D) nanoarchitectured palladium/nickel (Pd/Ni) catalysts, which were prepared by atomic layer deposition (ALD) on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4). Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects. PMID:24605281

  18. 3D-nanoarchitectured Pd/Ni catalysts prepared by atomic layer deposition for the electrooxidation of formic acid.

    PubMed

    Assaud, Loïc; Monyoncho, Evans; Pitzschel, Kristina; Allagui, Anis; Petit, Matthieu; Hanbücken, Margrit; Baranova, Elena A; Santinacci, Lionel

    2014-01-01

    Three-dimensionally (3D) nanoarchitectured palladium/nickel (Pd/Ni) catalysts, which were prepared by atomic layer deposition (ALD) on high-aspect-ratio nanoporous alumina templates are investigated with regard to the electrooxidation of formic acid in an acidic medium (0.5 M H2SO4). Both deposition processes, Ni and Pd, with various mass content ratios have been continuously monitored by using a quartz crystal microbalance. The morphology of the Pd/Ni systems has been studied by electron microscopy and shows a homogeneous deposition of granularly structured Pd onto the Ni substrate. X-ray diffraction analysis performed on Ni and NiO substrates revealed an amorphous structure, while the Pd coating crystallized into a fcc lattice with a preferential orientation along the [220]-direction. Surface chemistry analysis by X-ray photoelectron spectroscopy showed both metallic and oxide contributions for the Ni and Pd deposits. Cyclic voltammetry of the Pd/Ni nanocatalysts revealed that the electrooxidation of HCOOH proceeds through the direct dehydrogenation mechanism with the formation of active intermediates. High catalytic activities are measured for low masses of Pd coatings that were generated by a low number of ALD cycles, probably because of the cluster size effect, electronic interactions between Pd and Ni, or diffusion effects.

  19. Intermartensitic Transformation and Enhanced Exchange Bias in Pd (Pt) -doped Ni-Mn-Sn alloys

    NASA Astrophysics Data System (ADS)

    Dong, S. Y.; Chen, J. Y.; Han, Z. D.; Fang, Y.; Zhang, L.; Zhang, C. L.; Qian, B.; Jiang, X. F.

    2016-05-01

    In this work, we studied the phase transitions and exchange bias of Ni50‑xMn36Sn14Tx (T = Pd, Pt; x = 0, 1, 2, 3) alloys. An intermartensitic transition (IMT), not observed in Ni50Mn36Sn14 alloy, was induced by the proper application of negative chemical pressure by Pd(Pt) doping in Ni50‑xMn36Sn14Tx (T = Pd, Pt) alloys. IMT weakened and was suppressed with the increase of applied field; it also disappeared with further increase of Pd(Pt) content (x = 3 for Pd and x = 2 for Pt). Another striking result is that exchange bias effect, ascribed to the percolating ferromagnetic domains coexisting with spin glass phase, is notably enhanced by nonmagnetic Pd(Pt) addition. The increase of unidirectional anisotropy by the addition of Pd(Pt) impurities with strong spin-orbit coupling was explained by Dzyaloshinsky-Moriya interactions in spin glass phase.

  20. Intermartensitic Transformation and Enhanced Exchange Bias in Pd (Pt) -doped Ni-Mn-Sn alloys.

    PubMed

    Dong, S Y; Chen, J Y; Han, Z D; Fang, Y; Zhang, L; Zhang, C L; Qian, B; Jiang, X F

    2016-05-12

    In this work, we studied the phase transitions and exchange bias of Ni50-xMn36Sn14Tx (T = Pd, Pt; x = 0, 1, 2, 3) alloys. An intermartensitic transition (IMT), not observed in Ni50Mn36Sn14 alloy, was induced by the proper application of negative chemical pressure by Pd(Pt) doping in Ni50-xMn36Sn14Tx (T = Pd, Pt) alloys. IMT weakened and was suppressed with the increase of applied field; it also disappeared with further increase of Pd(Pt) content (x = 3 for Pd and x = 2 for Pt). Another striking result is that exchange bias effect, ascribed to the percolating ferromagnetic domains coexisting with spin glass phase, is notably enhanced by nonmagnetic Pd(Pt) addition. The increase of unidirectional anisotropy by the addition of Pd(Pt) impurities with strong spin-orbit coupling was explained by Dzyaloshinsky-Moriya interactions in spin glass phase.

  1. Intermartensitic Transformation and Enhanced Exchange Bias in Pd (Pt) -doped Ni-Mn-Sn alloys

    PubMed Central

    Dong, S. Y.; Chen, J. Y.; Han, Z. D.; Fang, Y.; Zhang, L.; Zhang, C. L.; Qian, B.; Jiang, X. F.

    2016-01-01

    In this work, we studied the phase transitions and exchange bias of Ni50−xMn36Sn14Tx (T = Pd, Pt; x = 0, 1, 2, 3) alloys. An intermartensitic transition (IMT), not observed in Ni50Mn36Sn14 alloy, was induced by the proper application of negative chemical pressure by Pd(Pt) doping in Ni50−xMn36Sn14Tx (T = Pd, Pt) alloys. IMT weakened and was suppressed with the increase of applied field; it also disappeared with further increase of Pd(Pt) content (x = 3 for Pd and x = 2 for Pt). Another striking result is that exchange bias effect, ascribed to the percolating ferromagnetic domains coexisting with spin glass phase, is notably enhanced by nonmagnetic Pd(Pt) addition. The increase of unidirectional anisotropy by the addition of Pd(Pt) impurities with strong spin-orbit coupling was explained by Dzyaloshinsky-Moriya interactions in spin glass phase. PMID:27170057

  2. Supercoducting property of Zr-Cu-Al-Ni-Nb alloys

    NASA Astrophysics Data System (ADS)

    Okai, D.; Motoyama, G.; Kimura, H.; Inoue, A.

    The superconducting property of Zr55Cu(30-X)Al10Ni5NbX alloys prepared by arc melting and liquid quenching methods was investigated by magnetic susceptibility measurements. The crystalline alloys with X = 0∼25 at.% prepared by arc melting method exhibited superconductivity with maximum Tc,on of 10.1 K. The alloys (X = 10∼23 at.%) with crystalline particles embedded in an amorphous structure, which were fabricated by melt spinning method, showed superconductivity with Tc,on of less than 4.0 K. The superconducting property of the Zr-Cu-Al-Ni-Nb alloys was attributed to superconducting phases of Zr2Cu, Zr2Ni, Zr65Al10Nb25 and Zr-Nb contained in the Zr-Cu-Al-Ni-Nb alloys. The melt-spun Zr55Cu(30-X)Al10Ni5NbX (X = 10∼20 at.%) alloys exhibited glass transition at 718∼743 K and were found to be superconducting metallic glasses.

  3. Metal/silicon interface formation - The Ni/Si and Pd/Si systems

    NASA Technical Reports Server (NTRS)

    Grunthaner, P. J.; Grunthaner, F. J.; Madhukar, A.; Mayer, J. W.

    1981-01-01

    The valence level spectra of the Ni/Si and Pd/Si systems have been investigated using high resolution X-ray photoelectron spectroscopy. Temperature dependence studies for Ni deposited on thin thermal SiO2 demonstrate the importance of metal aggregation effects in the interpretation of binding energies as chemical shifts. Temperature studies for the Ni/Si system indicate that substantial chemical interaction occurs at the interface at temperatures as low as 100 K. These studies also show the presence of Ni in interstitial voids in the Si near the interface. A comparative study of the core and valence band features for the Ni and Pd silicides provides many valuable insights and a self-consistent picture of the attendent valence charge redistribution and its influence on the observed chemical shifts.

  4. Transformation of sodium bicarbonate and CO2 into sodium formate over NiPd nanoparticle catalyst

    PubMed Central

    Wang, Mengnan; Zhang, Jiaguang; Yan, Ning

    2013-01-01

    The present research systematically investigated, for the first time, the transformation of sodium bicarbonate and CO2 into sodium formate over a series of Ni based metal nanoparticles (NPs). Ni NPs and eight NiM (M stands for a second metal) NPs were prepared by a facile wet chemical process and then their catalytic performance were evaluated in sodium bicarbonate hydrogenation. Bimetallic NiPd NPs with a composition of 7:3 were found to be superior for this reaction, which are more active than both pure Ni and Pd NPs. Hot filtration experiment suggested the NPs to be the truly catalytic active species and kinetic analysis indicated the reaction mechanism to be different than most homogeneous catalysts. The enhanced activity of the bimetallic nanoparticles may be attributed to their smaller size and improved stability. PMID:24790945

  5. Transformation of sodium bicarbonate and CO2 into sodium formate over NiPd nanoparticle catalyst.

    PubMed

    Wang, Mengnan; Zhang, Jiaguang; Yan, Ning

    2013-01-01

    The present research systematically investigated, for the first time, the transformation of sodium bicarbonate and CO2 into sodium formate over a series of Ni based metal nanoparticles (NPs). Ni NPs and eight NiM (M stands for a second metal) NPs were prepared by a facile wet chemical process and then their catalytic performance were evaluated in sodium bicarbonate hydrogenation. Bimetallic NiPd NPs with a composition of 7:3 were found to be superior for this reaction, which are more active than both pure Ni and Pd NPs. Hot filtration experiment suggested the NPs to be the truly catalytic active species and kinetic analysis indicated the reaction mechanism to be different than most homogeneous catalysts. The enhanced activity of the bimetallic nanoparticles may be attributed to their smaller size and improved stability.

  6. Spatial statistical and structural modeling of the Keivitsa Ni-Cu-PGE deposit, northern Finland

    NASA Astrophysics Data System (ADS)

    Parkkinen, J.

    2003-04-01

    The Keivitsa Ni-Cu-PGE deposit, located in the central Finnish Lapland, has been studied using Gemcom’s software to analyze and model Cu, S, Ni, and PGE (+Au) grade structures. Input data includes whole rock geochemistry, base metal geochemistry (Cu, Ni, S, 13102 assays averaging 0.15 %, 0.13 %, and 0.82 % correspondingly) and Platinum Group Element (PGE) and gold geochemistry (Pt, Pd, and Au, 4297 assays averaging 242 ppb, 159 ppb, and 81 ppb, correspondingly). Additionally, core geophysical data (specific gravity, 22098 determinations averaging 3.157) has been used in modeling. In the first phase Inverse Distance (ID2) was used for the interpolation of above assays as well as for specific gravity measurements, taken from core samples at 1m intervals. This occurred on horizontal planes and on N-S, E-W, and diagonally oriented vertical sections where also grade structures for PGE, Ni, Cu and S were outlined while making use of above interpolations and block models. Interpretation of geophysical data suggests sub-horizontal layering of the Keivitsa intrusion. Geochemical correlation modeling shows that the PGE have good spatial correlation with Ni and S, whereas Cu peaks are slightly shifted from the PGE maximum. A high PGE zone is trending almost S-N, with grade structures indicating pipe-like vertical bodies. The PGE-rich pipes, delimited by a cutoff grade 1 ppm PGE+Au, are about 30-50 m long and 10-30 m wide with a vertical depth of more than 400 m at most. The Pt/Pd ratio is 1.76 on an average and the average PGE + Au is 2.1 ppm within the pipes delineated with an one ppm cutoff grade. The PGE-rich zone may be a deep fault zone, having split the Ni-Cu deposit hosted by the Keivitsa olivine clino-pyroxenite into two segments plunging to the SE. The low grade Cu-Ni-sulfide dissemination extends approximately 1.0 km in the E-W direction and 0.6 km in the N-S direction with a thickness of about 500 m. The total resources at Keivitsa to a depth of 300 m are 112 Mt

  7. Local structure order in Pd78Cu6Si16 liquid

    DOE PAGES

    Yue, G. Q.; Zhang, Y.; Sun, Y.; ...

    2015-02-05

    The short-range order (SRO) in Pd78Cu6Si16 liquid was studied by high energy x-ray diffraction and ab initio molecular dynamics (MD) simulations. The calculated pair correlation functions at different temperatures agree well with the experimental results. The partial pair correlation functions from ab intio MD simulations indicate that Si atoms prefer to be uniformly distributed while Cu atoms tend to aggregate. By performing structure analysis using Honeycutt-Andersen index, Voronoi tessellation, and atomic cluster alignment method, we show that the icosahedron and face-centered cubic SRO increase upon cooling. The dominant SRO is the Pd-centered Pd9Si2 motif, namely the structure of which motifmore » is similar to the structure of Pd-centered clusters in the Pd9Si2 crystal. The study further confirms the existence of trigonal prism capped with three half-octahedra that is reported as a structural unit in Pd-based amorphous alloys. The majority of Cu-centered clusters are icosahedra, suggesting that the presence of Cu is benefit to promote the glass forming ability.« less

  8. Analysis of Surface and Bulk Behavior in Ni-Pd Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Rondald D.

    2003-01-01

    The most salient features of the surface structure and bulk behavior of Ni-Pd alloys have been studied using the BFS method for alloys. Large-scale atomistic simulations were performed to investigate surface segregation profiles as a function of temperature, crystal face, and composition. Pd enrichment of the first layer was observed in (111) and (100) surfaces, and enrichment of the top two layers occurred for (110) surfaces. In all cases, the segregation profile shows alternate planes enriched and depleted in Pd. In addition, the phase structure of bulk Ni-Pd alloys as a function of temperature and composition was studied. A weak ordering tendency was observed at low temperatures, which helps explain the compositional oscillations in the segregation profiles. Finally, based on atom-by-atom static energy calculations, a comprehensive explanation for the observed surface and bulk features will be presented in terms of competing chemical and strain energy effects.

  9. PdNi hollow nanoparticles for improved electrocatalytic oxygen reduction in alkaline environments.

    PubMed

    Wang, Meng; Zhang, Weimin; Wang, Jiazhao; Wexler, David; Poynton, Simon D; Slade, Robert C T; Liu, Huakun; Winther-Jensen, Bjorn; Kerr, Robert; Shi, Dongqi; Chen, Jun

    2013-12-11

    Palladium-nickel (PdNi) hollow nanoparticles were synthesized via a modified galvanic replacement method using Ni nanoparticles as sacrificial templates in an aqueous medium. X-ray diffraction and transmission electron microscopy show that the as-synthesized nanoparticles are alloyed nanostructures and have hollow interiors with an average particle size of 30 nm and shell thickness of 5 nm. Compared with the commercially available Pt/C or Pd/C catalysts, the synthesized PdNi/C has superior electrocatalytic performance towards the oxygen reduction reaction, which makes it a promising electrocatalyst for alkaline anion exchange membrane fuel cells and alkali-based air-batteries. The electrocatalyst is finally examined in a H2/O2 alkaline anion exchange membrane fuel cell; the results show that such electrocatalysts could work in a real fuel cell application as a more efficient catalyst than state-of-the-art commercially available Pt/C.

  10. The Influence of Size Effect on Sensitivity of Cu/CuNi Thin- film Thermocouple

    NASA Astrophysics Data System (ADS)

    Yang, Lihong; Zhao, Yuanshen; Feng, Cenming; Zhou, Hua

    In this paper, the influence of size effect on the sensitivity of Cu/CuNi thin-film thermocouple was studied through experiments and theoretical analysis. Cu/CuNi thin-film thermocouples with different thicknesses of 0.5 μm, 1.0 μm, 1.5 μm and 2.0 μm were fabricated on the substrate with SiO2 lining by means of reactive magnetron sputtering. After static calibration, the sensitivities of the thermocouples were obtained respectively of 46.49 μV/°C, 45.23 μ/°C, 44.56 μV/°C and 43.94 μV/°C. According to the experimental results, it can be seen that the sensitivity of Cu/CuNi thin-film thermocouple is higher than that of the bulk Cu/CuNi thermocouple, and the sensitivity S will increase with the reciprocal of the thickness 1/δ as long as the thickness of the film is greater than the critical value.

  11. Thermomechanical behavior and microstructural evolution of a Ni(Pd)-rich Ni24.3Ti49.7Pd26 high temperature shape memory alloy

    DOE PAGES

    Benafan, O.; Garg, A.; Noebe, R. D.; ...

    2015-04-20

    We investigated the effect of thermomechanical cycling on a slightly Ni(Pd)-rich Ni24.3Ti49.7Pd26 (near stochiometric Ni–Ti basis with Pd replacing Ni) high temperature shape memory alloy. Furthermore, aged tensile specimens (400 °C/24 h/furnace cooled) were subjected to constant-stress thermal cycling in conjunction with microstructural assessment via in situ neutron diffraction and transmission electron microscopy (TEM), before and after testing. It was shown that in spite of the slightly Ni(Pd)-rich composition and heat treatment used to precipitation harden the alloy, the material exhibited dimensional instabilities with residual strain accumulation reaching 1.5% over 10 thermomechanical cycles. This was attributed to insufficient strengthening ofmore » the material (insufficient volume fraction of precipitate phase) to prevent plasticity from occurring concomitant with the martensitic transformation. In situ neutron diffraction revealed the presence of retained martensite while cycling under 300 MPa stress, which was also confirmed by transmission electron microscopy of post-cycled samples. Neutron diffraction analysis of the post-thermally-cycled samples under no-load revealed residual lattice strains in the martensite and austenite phases, remnant texture in the martensite phase, and peak broadening of the austenite phase. The texture we developed in the martensite phase was composed mainly of those martensitic tensile variants observed during thermomechanical cycling. Presence of a high density of dislocations, deformation twins, and retained martensite was revealed in the austenite state via in-situ TEM in the post-cycled material, providing an explanation for the observed peak broadening in the neutron diffraction spectra. Despite the dimensional instabilities, this alloy exhibited a biased transformation strain on the order of 3% and a two-way shape memory effect (TWSME) strain of ~2%, at relatively high actuation temperatures.« less

  12. Studies on polishing of Ti and Ag-Pd-Cu-Au alloy with five dental abrasives.

    PubMed

    Hirata, T; Nakamura, T; Takashima, F; Maruyama, T; Taira, M; Takahashi, J

    2001-08-01

    Titanium (Ti) and Ag-Pd-Cu-Au alloy were examined for their polishing behaviour by conducting manually controlled polishing tests using five dental abrasives [carborundum point (CR) and silicone points (R1 and R2)] driven by a high torque micromotor with rotational speeds ranging from 2000 to 15 000 r.p.m. Polishing of Ti resulted in less volume of removal upon polishing, a rougher surface and larger loss of abrasives, compared with polishing of Ag-Pd-Cu-Au alloy. Polishing of Ti with a rotational speed of 15 000 r.p.m. led to the largest volume of removal upon polishing, whilst that of 10 000 r.p.m. produced the optimal volume for Ag-Pd-Cu-Au alloy. It was concluded that Ti was much more difficult to polish, requiring special care (e.g. frequent exchange of abrasives). Development of new abrasives for polishing Ti is required.

  13. Thermally enhanced perpendicular magnetic anisotropy behaviors of ultrathin [Co/Pd]n multilayers via NiOx capping layer

    NASA Astrophysics Data System (ADS)

    Chung, Woo Seong; Lee, Ja Bin; An, Gwang Guk; Yang, Seung Mo; Kim, Jae Hong; Hong, Jin Pyo

    2015-06-01

    We report the enhanced perpendicular magnetic anisotropy (PMA) features of ultrathin [Co/Pd]3 multilayers (MLs) employing a NiOx insertion layer at high annealing temperatures. Thermally enhanced PMA in [Co/Pd]3/NiOx (capping layer) MLs were achieved at a specific capping layer thickness, while no PMA responses were observed for a NiOx (buffer layer)/[Co/Pd]3 ML, regardless of NiOx thickness. X-ray diffraction observations, including rocking curves, identified the relatively different crystalline characteristics of the NiOx capping and buffer layers. Origin of the enhanced PMAs of [Co/Pd]3 MLs containing a NiOx capping layer is described based on the NiOx capping effect possibly providing additional Co/Oxide i-PMA under high-temperature annealing.

  14. Geochemistry of the Kalatongke Ni-Cu-(PGE) sulfide deposit, NW China: implications for the formation of magmatic sulfide mineralization in a postcollisional environment

    NASA Astrophysics Data System (ADS)

    Song, Xie-Yan; Li, Xiang-Ren

    2009-04-01

    The Kalatongke (also spelt as Karatungk) Ni-Cu-(platinum-group element, PGE) sulfide deposit, containing 33 Mt sulfide ore with a grade of 0.8 wt.% Ni and 1.3 wt.% Cu, is located in the Eastern Junggar terrane, Northern Xinjiang, NW China. The largest sulfide ore body, which occupies more than 50 vol.% of the intrusion Y1, is dominantly comprised of disseminated sulfide with a massive sulfide inner zone. Economic disseminated sulfides also occur at the base of the intrusions Y2 and Y3. The main host rock types are norite in the lower part and diorite in the upper part of each intrusion. Enrichment in large ion lithophile elements and depletion in heavy rare earth elements relative to mid-ocean ridge basalt indicate that the mafic intrusions were produced from magmas derived from a metasomatized garnet lherzolite mantle. The average grades of the disseminated ores are 0.6 wt.% Ni and 1.1 wt.% Cu, whereas those of the massive ores are 2 wt.% Ni and 8 wt.% Cu. The PGE contents of the disseminated ores (14-69 ppb Pt and 78-162 ppb Pd) are lower than those of the massive ores (120-505 ppb Pt and 30-827 ppb Pd). However, on the basis of 100% sulfide, PGE contents of the massive sulfides are lower than those of the disseminated sulfides. Very high Cu/Pd ratios (>4.5 × 104) indicate that the Kalatongke sulfides segregated from PGE-depleted magma produced by prior sulfide saturation and separation. A negative correlation between the Cu/Pd ratio and the Pd content in 100% sulfide indicates that the PGE content of the sulfide is controlled by both the PGE concentrations in the parental silicate magma and the ratio of the amount of silicate to sulfide magma. The negative correlations between Ir and Pd indicate that the massive sulfides experienced fractionation.

  15. Phase equilibria in the palladium-rich part of the Pd-Au-Cu-Sn quaternary system

    NASA Astrophysics Data System (ADS)

    Kareva, M. A.; Kabanova, E. G.; Zhmurko, G. P.; Kuznetsov, V. N.

    2017-02-01

    The solubility of tin in the phases of Pd-Au-Sn and Pd-Cu-Sn ternary systems and a Pd-Au-Cu-Sn quaternary system with a fixed Pd: Au: Cu ratio of 11.1: 1: 4.6 is studied via microstructural, X-ray diffraction, and energy dispersive analysis. It is found that a quaternary alloy in equilibrium with a solid solution based on Pd, Au, and Sn contains a τ1 compound with structure which is derivative of the In type. It contains 15 at % Sn and is a solid solution of the same compounds identified earlier in Pd-Au-Sn and Pd-Cu-Sn ternary systems. In addition, a quaternary alloy with a content of 20 at % Sn also contains a τ2 compound with the Pd2CuSn own type and can barely dissolve gold. The obtained data are used to construct a three-dimensional model of the Pd-rich part of the isothermal tetrahedron of the Pd-Au-Cu-Sn system and diagrams of the tin solubility isolines in palladium-rich alloys of the quaternary system at 500°C.

  16. Tensile strength and creep resistance in nanocrystalline Cu, Pd and Ag

    SciTech Connect

    Nieman, G.W.; Weertman, J.R. . Dept. of Materials Science and Engineering); Siegel, R.W. )

    1990-12-01

    Measurements of tensile strength and creep resistance have been made on bulk samples of nanocrystalline Cu, Pd and Ag consolidated from powders by cold compaction. Samples of Cu-Cu{sub 2}O have also been tested. Yield strength for samples with mean grains sizes of 5-80 nm and bulk densities on the order of 95% of theoretical density are increased 2--5 times over that measured in pure, annealed samples of the same composition with micrometer grain sizes. Ductility in the nanocrystalline Cu has exceeded 6% true strain, however, nanocrystalline Pd samples were much less ductile. Constant load creep tests performed at room temperature at stresses of >100 MPa indicate logarithmic creep. The mechanical properties results are interpreted to be due to grain size-related strengthening and processing flaw-related weakening. 26 refs., 2 figs.

  17. PdCuPt Nanocrystals With Multi-branches for Enzyme-free Glucose Detection

    SciTech Connect

    Fu, Shaofang; Zhu, Chengzhou; Song, Junhua; Engelhard, Mark H.; Xia, Haibing; Du, Dan; Lin, Yuehe

    2016-08-05

    By carefully controlling the synthesis condition, branched PtCu bimetallic templates were synthesized in aqueous solution. After the galvanic replacement reaction between PtCu templates and the Pt precursors, PdCuPt trimetallic nanocrystals with branched structures were obtained. Owing to the open structure and the optimized composition, the electrochemical experimental results reveal that the PdCuPt trimetallic nanocrystals exhibit high electrocatalytic activity, selectivity and stability for the oxidation of glucose in alkaline solution. In details, a sensitivity of 378 μA/mM/cm2 and a detection limit of 1.29 μM can be achieved. The good electrocatalytic performance should be attributed to the unique branched nanostructure as well as the synergistic effect among metals. The superior catalytic properties suggest that these nanocrystals are promising for enzyme-free detection of glucose.

  18. Effect of Cross-Interaction between Ni and Cu on Growth Kinetics of Intermetallic Compounds in Ni/Sn/Cu Diffusion Couples during Aging

    NASA Astrophysics Data System (ADS)

    Hong, K. K.; Ryu, J. B.; Park, C. Y.; Huh, J. Y.

    2008-01-01

    The solid-state, cross-interaction between the Ni layer on the component side and the Cu pad on the printed circuit board (PCB) side in ball grid array (BGA) solder joints was investigated by employing Ni(15 μm)/Sn(65 μm)/Cu ternary diffusion couples. The ternary diffusion couples were prepared by sequentially electroplating Sn and Ni on a Cu foil and were aged isothermally at 150, 180, and 200°C. The growth of the intermetallic compound (IMC) layer on the Ni side was coupled with that on the Cu side by the mass flux across the Sn layer that was caused by the difference in the Ni content between the (Cu1- x Ni x )6Sn5 layer on the Ni side and the (Cu1- y Ni y )6Sn5 layer on the Cu side. As the consequence of the coupling, the growth rate of the (Cu1- x Ni x )6 Sn5 layer on the Ni side was rapidly accelerated by decreasing Sn layer thickness and increasing aging temperature. Owing to the cross-interaction with the top Ni layer, the growth rate of the (Cu1- y Ni y )6Sn5 layer on the Cu side was accelerated at 150°C and 180°C but was retarded at 200°C, while the growth rate of the Cu3Sn layer was always retarded. The growth kinetic model proposed in an attempt to interpret the experimental results was able to reproduce qualitatively all of the important experimental observations pertaining to the growth of the IMC layers in the Ni/Sn/Cu diffusion couple.

  19. Ni-Supported Pd Nanoparticles with Ca Promoter: A New Catalyst for Low-Temperature Ammonia Cracking

    PubMed Central

    Polanski, Jaroslaw; Bartczak, Piotr; Ambrozkiewicz, Weronika; Sitko, Rafal; Siudyga, Tomasz; Mianowski, Andrzej; Szade, Jacek; Balin, Katarzyna; Lelątko, Józef

    2015-01-01

    In this paper we report a new nanometallic, self-activating catalyst, namely, Ni-supported Pd nanoparticles (PdNPs/Ni) for low temperature ammonia cracking, which was prepared using a novel approach involving the transfer of nanoparticles from the intermediate carrier, i.e. nano-spherical SiO2, to the target carrier technical grade Ni (t-Ni) or high purity Ni (p-Ni) grains. The method that was developed allows a uniform nanoparticle size distribution (4,4±0.8 nm) to be obtained. Unexpectedly, the t-Ni-supported Pd NPs, which seemed to have a surface Ca impurity, appeared to be more active than the Ca-free (p-Ni) system. A comparison of the novel PdNPs/Ni catalyst with these reported in the literature clearly indicates the much better hydrogen productivity of the new system, which seems to be a highly efficient, flexible and durable catalyst for gas-phase heterogeneous ammonia cracking in which the TOF reaches a value of 2615 mmolH2/gPd min (10,570 molNH3/molPd(NP) h) at 600°C under a flow of 12 dm3/h (t-Ni). PMID:26308929

  20. Spin Reorientation Transition in Magnetically Coupled Fe/Cu/Ni/Cu(001)

    NASA Astrophysics Data System (ADS)

    Choi, H. J.; Ling, W. L.; Wolfe, J. H.; Toyama, F.; Paik, S.; Bovensiepen, U.; Qiu, Z. Q.; Scholl, A.; Nolting, F.; Anders, S.

    2001-03-01

    We investigated Spin Reorientation Transition (SRT) of Fe film in Fe/Cu/Ni/Cu(001) where the Fe layer is magnetically coupled to the perpendicular magnetization of Ni with the interlayer coupling strength being controlled by the Cu thickness. With in situ surface magneto-optic Kerr effect measurement, we show that the Fe-Ni interlayer coupling results in an alternating alignment of the Fe magnetization with Cu thickness for Fe film thinner than the SRT thickness dR, but has no effect for Fe film thicker than dR. The SRT thickness dR, defined as the onset of in-plane magnetization, was found to be independent of the Fe-Ni interlayer coupling. Within the SRT pseudo-gap region, however, the magnetic remanence exhibits oscillatory behavior with Cu thickness with a periodicity exactly half of that in the oscillatory interlayer coupling. This result shows that the strip domains are severely modified by the strength of the Fe-Ni interlayer coupling. To provide more detailed information, element specific domain imaging was taken in this system using photoemission electron microscope at the Advanced Light Source of Lawrence Berkeley National Laboratory.

  1. Electrooxidation of ethylene glycol and glycerol on Pd-(Ni-Zn)/C anodes in direct alcohol fuel cells.

    PubMed

    Marchionni, Andrea; Bevilacqua, Manuela; Bianchini, Claudio; Chen, Yan-Xin; Filippi, Jonathan; Fornasiero, Paolo; Lavacchi, Alessandro; Miller, Hamish; Wang, Lianqin; Vizza, Francesco

    2013-03-01

    The electrooxidation of ethylene glycol (EG) and glycerol (G) has been studied: in alkaline media, in passive as well as active direct ethylene glycol fuel cells (DEGFCs), and in direct glycerol fuel cells (DGFCs) containing Pd-(Ni-Zn)/C as an anode electrocatalyst, that is, Pd nanoparticles supported on a Ni-Zn phase. For comparison, an anode electrocatalyst containing Pd nanoparticles (Pd/C) has been also investigated. The oxidation of EG and G has primarily been investigated in half cells. The results obtained have highlighted the excellent electrocatalytic activity of Pd-(Ni-Zn)/C in terms of peak current density, which is as high as 3300 A g(Pd)(-1) for EG and 2150 A g(Pd)(-1) for G. Membrane-electrode assemblies (MEA) have been fabricated using Pd-(Ni-Zn)/C anodes, proprietary Fe-Co/C cathodes, and Tokuyama A-201 anion-exchange membranes. The MEA performance has been evaluated in either passive or active cells fed with aqueous solutions of 5 wt % EG and 5 wt % G. In view of the peak-power densities obtained in the temperature range from 20 to 80 °C, at Pd loadings as low as 1 mg cm(-2) at the anode, these results show that Pd-(Ni-Zn)/C can be classified amongst the best performing electrocatalysts ever reported for EG and G oxidation.

  2. Pd/RGO modified carbon felt cathode for electro-Fenton removing of EDTA-Ni.

    PubMed

    Zhang, Zhen; Zhang, Junya; Ye, Xiaokun; Hu, Yongyou; Chen, Yuancai

    Ethylenediaminetetraacetic acid (EDTA) forms stable complexes with toxic metals such as nickel due to its strong chelation. The electro-Fenton (EF) process using a cathode made from palladium (Pd), reduced graphene oxide (RGO) and carbon felt, fed with air, exhibited high activities and stability for the removal of 10 mg L(-1) EDTA-Ni solution. Pd/RGO catalyst was prepared by one-pot synthesis; the scanning electron microscopy and X-ray diffraction analysis indicated nanoparticles and RGO were well distributed on carbon felt, forming three dimensional architecture with both large macropores and a mesoporous structure. The cyclic voltammetric results showed that the presence of RGO in Pd/RGO/carbon felt significantly increased the current response of two-electron reduction of O2 (0.45 V). The key factors influencing the removal efficiency of EDTA-Ni, such as pH, current and Fe(2+) concentration, were investigated. Under the optimum conditions, the removal efficiency of EDTA-Ni reached 83.8% after 100 min EF treatment. Mechanism analysis indicated that the introduction of RGO in Pd/RGO/carbon felt significantly enhanced the electrocatalytic activities by inducing •OH in the EF process; direct H2O2 oxidation still accounted for a large amount of EDTA-Ni removal efficiency.

  3. Ni doping on Cu surfaces: Reduced copper resistivity

    SciTech Connect

    Zheng, P. Y.; Deng, R. P.; Gall, D.

    2014-09-29

    The resistivity of 9.3-nm-thick epitaxial and polycrystalline Cu is reduced by 11%–13% when coated with 0.75 nm Ni. Sequential in situ and ex situ transport measurements show that this is due to electron surface scattering which exhibits a specularity p = 0.7 for the Cu-vacuum interface that transitions to completely diffuse (p = 0) when exposed to air. In contrast, Ni-coated surfaces exhibit partial specularity with p = 0.3 in vacuum and p = 0.15 in air, as Cu{sub 2}O formation is suppressed, leading to a smaller surface potential perturbation and a lower density of localized surface states, yielding less diffuse electron scattering.

  4. Nanocrystalline Pd:NiFe2O4 thin films: A selective ethanol gas sensor

    NASA Astrophysics Data System (ADS)

    Rao, Pratibha; Godbole, R. V.; Bhagwat, Sunita

    2016-10-01

    In this work, Pd:NiFe2O4 thin films were investigated for the detection of reducing gases. These films were fabricated using spray pyrolysis technique and characterized using X-ray diffraction (XRD) to confirm the crystal structure. The surface morphology was studied using scanning electron microscopy (SEM). Magnetization measurements were carried out using SQUID VSM, which shows ferrimagnetic behavior of the samples. These thin film sensors were tested against methanol, ethanol, hydrogen sulfide and liquid petroleum gas, where they were found to be more selective to ethanol. The fabricated thin film sensors exhibited linear response signal for all the gases with concentrations up to 5 w/o Pd. Reduction in optimum operating temperature and enhancement in response was also observed. Pd:NiFe2O4 thin films exhibited faster response and recovery characteristic. These sensors have potential for industrial applications because of their long-term stability, low power requirement and low production cost.

  5. Neutron spectroscopic factors of 55Ni hole-states from (p,d) transfer reactions

    NASA Astrophysics Data System (ADS)

    Sanetullaev, A.; Tsang, M. B.; Lynch, W. G.; Lee, Jenny; Bazin, D.; Chan, K. P.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Rogers, A. M.; Sun, Z. Y.; Youngs, M.; Charity, R. J.; Sobotka, L. G.; Famiano, M.; Hudan, S.; Shapira, D.; Peters, W. A.; Barbieri, C.; Hjorth-Jensen, M.; Horoi, M.; Otsuka, T.; Suzuki, T.; Utsuno, Y.

    2014-09-01

    Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu), one nucleon away from 56Ni, the N=Z=28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2 hole-state below Fermi energy.

  6. [Corrosion of Ag-Pd-Cu alloys in saline solution. Amount of released elements and electrochemical corrosion].

    PubMed

    Kitaoka, M

    1989-03-01

    The effect of the Pd content on corrosion and tarnish resistance in twelve experimental alloys was investigated. The alloys were prepared with a composition of Pd content from 20.1 to 30.1 at %. The composition of the alloys Ag-20% Pd, Ag-25% Pd and Ag-30% Pd was varied by adding Cu 5 wt%, 10 wt% and 15 wt% to each of them. The corrosion resistance was estimated by the amount of the released Ag, Cu and by electrochemical corrosion behavior in 0.86% NaCl solution at 37 degrees C. The tarnish resistance was assessed using a spectrophotometer. The test solutions included 0.86% NaCl solution, 0.1% Na2S solution and a mixture of 1.0% lactic acid and 0.1% Na2S, all at 37 degrees C, in sealed containers. The results are summarized as follows. The larger the amount of Pd in Ag-Pd binary alloys and Ag-Pd-Cu ternary alloys, the more stable was the release and the release rate of Ag, Cu and corrosion resistance increased in 0.86% NaCl solution. The addition of Cu to Ag-Pd binary alloys increased the release and release rate of Ag, but there was a shift of the rest potential in the noble direction. A relationship was found between the amount of Ag and Cu released from Ag-Pd-Cu ternary alloys. In this study, an increase in corrosion resistance was observed when the content of Pd in Ag-Pd binary alloys was 25 wt%. Furthermore, it was also observed that Ag-Pd-Cu ternary alloys need an additional 30 wt% Pd for corrosion resistance. Moreover, the addition of Cu must be kept lower than 10 wt%. The tarnish resistance of the twelve experimental alloys was good in 0.86% NaCl solution but was barely improved with increased in the Pd content in sulfide solution. The correlation between electrochemical corrosion behavior and tarnish resistance was not significant, but the correlation between the amount of Ag, Cu release from Ag-Pd-Cu ternary alloys and tarnish resistance was remarkable.

  7. Electrocatalytic hydrodehalogenation of atrazine in aqueous solution by Cu@Pd/Ti catalyst.

    PubMed

    Chen, Ya-Li; Xiong, Lu; Song, Xiang-Ning; Wang, Wei-Kang; Huang, Yu-Xi; Yu, Han-Qing

    2015-04-01

    Electrocatalytic hydrodehalogenation is a cost-effective approach to degrade halogenated organic pollutants in groundwater, and Pd-based catalysts have been found to be an efficient cathode material for this purpose. In this work, a novel Cu@Pd bimetallic catalyst loaded on Ti plate was prepared via combined electrodeposition and galvanic replacement for electrocatalytic hydrodehalogenation of atrazine, a typical halogenated pollutant. The obtained bimetallic catalyst with uniformly dispersed Pd nanoparticles possessed a large electrochemically active surface area of 572 cm2. The Cu@Pd/Ti cathode exhibited a higher electrocatalytic efficiency towards atrazine reduction than the individual Pd/Ti or Cu/Ti cathodes, and achieved up to 91.5% within 120 min under a current density of 1 mA cm(-2). Such an electrocatalytic reduction followed pseudo-first-order kinetics with a rate constant of 0.0214 min(-1). Atrazine was selectively transformed to dechlorinated atrazine, and its degradation pathway was identified. Current density was found to have a critical influence on the atrazine reduction due to the competitive hydrogen evolution reaction at a higher current density. The fabricated bimetallic catalyst also exhibited a good stability. This work provides an efficient and stable electrocatalyst for chlorinated contaminate removal and groundwater remediation.

  8. Design of Heusler Precipitation Strengthened NiTi- and PdTi-Base SMAs for Cyclic Performance

    NASA Astrophysics Data System (ADS)

    Frankel, Dana J.; Olson, Gregory B.

    2015-06-01

    For a wide range of actuation applications, the performance of NiTi-based shape memory alloys is limited by cyclic instability associated with accommodation slip. For medical applications, low-Ni compositions are also desirable. Increasing yield strength via precipitation of a coherent nanoscale Ni2TiAl-type Heusler phase from a supersaturated B2 matrix is an effective approach for eliminating slip in order to improve the stability of the functional response and increase the structural fatigue life. Quaternary additions that partition into the L21 Heusler phase, such as Zr or Pd, are favorable for reducing interphase misfit and maintaining coherency during aging. Phase relations and precipitation kinetics in quaternary Ni(TiZrAl), low-Ni (PdNi)(TiAl), and Ni-free (PdFe)(TiAl) systems are summarized from TEM and atom probe tomography data in the literature. Strengthening behavior during isothermal aging is compared in the NiTiZrAl and PdNiTiAl systems, and recent work characterizing a high-strength, low-Ni "Hybrid" (PdNi)(TiZrAl) alloy is presented. A systems design approach is taken in which an optimal microstructure for peak strengthening is identified while other property objectives such as transformation temperature, misfit, radiopacity, and biocompatibility are satisfied.

  9. Sulfur Tolerant Pd/Cu and Pd/Au Alloy Membranes for H2 Separation with High Pressure CO2 for Sequestration

    SciTech Connect

    Yi Hua Ma; Natalie Pomerantz; Chao-Huang Chen

    2008-09-30

    The effect of H{sub 2}S poisoning on Pd, Pd/Cu, and Pd/Au alloy composite membranes prepared by the electroless deposition method on porous Inconel supports was investigated to provide a fundamental understanding of the durability and preparation of sulfur tolerant membranes. X-ray photoelectron spectroscopy (XPS) studies showed that the exposure of pure Pd to 50 ppm H{sub 2}S/H{sub 2} mixtures caused bulk sulfide formation at lower temperatures and surface sulfide formation at higher temperatures. Lower temperatures, longer exposure times, and higher H{sub 2}S concentrations resulted in a higher degree of sulfidation. In a Pd membrane, the bulk sulfide formation caused a drastic irrecoverable H{sub 2} permeance decline and an irreparable loss in selectivity. Pd/Cu and Pd/Au alloy membranes exhibited permeance declines due to surface sulfide formation upon exposure to 50 ppm H{sub 2}S/H{sub 2} gas mixtures. However in contrast to the pure Pd membrane, the permeances of the Pd/Cu and Pd/Au alloy membranes were mostly recovered in pure H{sub 2} and the selectivity of the Pd alloy layers remained essentially intact throughout the characterization in H{sub 2}, He and H{sub 2}S/H{sub 2} mixtures which lasted several thousand hours. The amount of irreversible sulfur poisoning decreased with increasing temperature due to the exothermicity of H{sub 2}S adsorption. Longer exposure times increased the amount of irreversible poisoning of the Pd/Cu membrane but not the Pd/Au membrane. Pd/Au coupon studies of the galvanic displacement method showed that higher Au{sup 3+} concentrations, lower pH values, higher bath temperatures and stirring the bath at a rate of 200 rpm yielded faster displacement rates, more uniform depositions, and a higher Au content within the layers. While 400 C was found to be sufficient to form a Pd/Au alloy on the surface, high temperature X-ray diffraction (HTXRD) studies showed that even after annealing between 500-600 C, the Pd/Cu alloys could have

  10. 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.

  11. Electronic structure of disordered CuPd alloys by positron-annihilation 2D-ACAR

    SciTech Connect

    Smedskjaer, L.C.; Benedek, R.; Siegel, R.W.; Legnini, D.G.; Stahulak, M.D.; Bansil, A.

    1988-01-01

    We report 2D-ACAR experiments and KKR CPA calculations on alpha-phase single-crystal Cu/sub 1-x/Pd/sub x/ in the range x less than or equal to 0.25. The flattening of the Fermi surface near (110) with increasing x predicted by theory is confirmed by our experimental results. 16 refs., 2 figs.

  12. Highly efficient hydrogen generation from methanolysis of ammonia borane on CuPd alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Pengyao; Xiao, Zhengli; Liu, Zhaoyan; Huang, Jiale; Li, Qingbiao; Sun, Daohua

    2015-01-01

    A low-cost and facile route has been developed for the synthesis of monodisperse CuPd nanoparticles with tunable composition. (Scanning transmission electron microscopy-energy-dispersive x-ray spectroscopy) STEM-EDX results verified the structure of the alloy for the obtained nanoparticles. These CuPd nanoparticles supported on carbon were active catalysts for hydrogen generation from the methanolysis of ammonia borane (AB) at room temperature, and their activities were closely related with the compositions. Cu48Pd52 NPs exhibited the highest activity among the tested catalysts. Moreover, their activity can be further improved by thermal annealing at 300 °C under nitrogen flow, with a very high total turnover frequency value of 53.2 min-1. The reusability test indicated that the Cu48Pd52/C catalyst retains 86% of its initial activity and 100% conversion after 8 cycles. The catalyst, which features lost cost and high efficiency, may help move forward the practical application of AB as a sustainable hydrogen storage material.

  13. Highly selective PdCu/amorphous silica-alumina (ASA) catalysts for groundwater denitration.

    PubMed

    Xie, Yongbing; Cao, Hongbin; Li, Yuping; Zhang, Yi; Crittenden, John C

    2011-05-01

    Catalytic nitrate reduction is a promising technology in groundwater purification. In this study, PdCu bimetallic catalysts supported on an industrial amorphous silica-alumina (ASA) were synthesized and used to simulate catalytic removal of nitrate in groundwater. The catalysts exhibited very high activity and the highest catalytic selectivity toward N₂O and N₂ was 90.2%. The optimal Pd/Cu weight ratio was four. Relatively low reduction temperature was found benefit the catalytic stability and 300 °C was the appropriate reduction temperature during catalyst preparation. With an average particle size 5.4 nm, the metal particles were very uniformly distributed on the catalyst surface prepared with the codeposition method. This kept the catalyst more stable than the PdCu/Al₂O₂ catalyst with larger metal particles. According to XRD, TEM, and XPS results, the metals maintained zero-valence but aggregated by about 2 nm during the denitration reaction, which caused gradual deactivation of the catalysts. Little leaching of Cu and Pd from the catalyst might also have a slightly negative impact to the stability of the catalysts. A simple treatment was found to redistribute the particles on the deactivated catalysts, and high catalytic activity was recovered after this process.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  15. PdCu alloy nanoparticle-decorated copper nanotubes as enhanced electrocatalysts: DFT prediction validated by experiment

    NASA Astrophysics Data System (ADS)

    Wu, Dengfeng; Xu, Haoxiang; Cao, Dapeng; Fisher, Adrian; Gao, Yi; Cheng, Daojian

    2016-12-01

    In order to combine the advantages of both 0D and 1D nanostructured materials into a single catalyst, density functional theory (DFT) calculations have been used to study the PdCu alloy NP-decorated Cu nanotubes (PdCu@CuNTs). These present a significant improvement of the electrocatalytic activity of formic acid oxidation (FAO). Motivated by our theoretical work, we adopted the seed-mediated growth method to successfully synthesize the nanostructured PdCu@CuNTs. The new catalysts triple the catalytic activity for FAO, compared with commercial Pd/C. In summary, our work provides a new strategy for the DFT prediction and experimental synthesis of novel metal NP-decorated 1D nanostructures as electrocatalysts for fuel cells.

  16. Lithological and geochemical constraints on the magma conduit systems of the Huangshan Ni-Cu sulfide deposit, NW China

    NASA Astrophysics Data System (ADS)

    Deng, Yu-Feng; Song, Xie-Yan; Hollings, Pete; Chen, Lie-Meng; Zhou, Taofa; Yuan, Feng; Xie, Wei; Zhang, Dayu; Zhao, Bingbing

    2016-12-01

    Magmatic Ni-Cu sulfide deposits in northern Xinjiang, China, are associated with small mafic-ultramafic complexes, with the sulfide ores generally occurring in ultramafic rocks. The Huangshan deposit (up to 65 Mt of ore at 0.49% Ni and 0.31% Cu), one of the largest magmatic Ni-Cu deposits in northern Xinjiang, is composed of a layered sequence of lower websterite, lower lherzolite, websterite, norite-gabbro, gabbro, diorite, and gabbronorite, with sulfide mineralization mainly found in the lower lherzolite, lower websterite, and websterite. Systematic variations of the major oxides and trace elements suggest that the rocks of the Huangshan deposit are fractionated from the same parental magma, with the sharp contact and discontinuous trends of major oxide contents between different lithologies implying intrusion of four distinct stages of magma from a single deep-seated staging chamber. The reversals in olivine Fo contents and major oxides in the lower lherzolite were the result of inhomogeneity in olivine within the lower chamber. The Se/S ratios (63.1˜150 × 10-6) and the negative correlation between Se/S and δ34S (0.63˜2.42‰) of the sulfide ores suggest that a large contribution of crustal S caused the sulfide segregation. The sulfides in the lower lherzolite have lower Cu contents (1386-2200 ppm) and Cu/Pd ratios (2.31 × 105-1.36 × 106) relative to those in the mineralized lower websterite (Cu = 2300 to 18,700 ppm, and Cu/Pd = 6.65 × 105 to 2.73 × 106). A positive correlation between Pd/Ir and Ni/Ir for the vein-textured sulfides in the lower websterite likely reflects fractionated sulfides picked up by a new pulse of magma. In contrast, the restricted range of Pd/Ir ratios indicates that the PGE contents of the disseminated sulfides in the lower lherzolite resulted from reaction between the sulfides and new pulses of S-undersaturated magma.

  17. Precipitation in 9Ni-12Cr-2Cu maraging steels

    SciTech Connect

    Stiller, K.; Haettestrand, M.; Danoix, F.

    1998-11-02

    Two maraging steels with the compositions 9Ni-12Cr-2Cu-4Mo (wt%) and 9Ni-12Cr-2Cu and with small additions of Al and Ti were investigated using atom probe field ion microscopy. Tomographic atom probe investigations were performed to clarify the spatial distribution of elements in and close to the precipitates. Materials heat treated at 475 C for 5, 25 min, 1, 2, 4 and 400 h were analyzed. Precipitates in the Mo-rich material were observed already after 5 min of aging, while in the material without MO, precipitation started later. In both materials precipitation begins with the formation of Cu-rich particles which work as nucleation sites for a Ni-rich phase of type Ni{sub 3}(Ti,Al). A Mo-rich phase was detected in the Mo-rich steel after 2 h of aging. The distribution of alloying elements in the precipitates, their role in the precipitation process, and the mechanism of hardening in the two materials are discussed.

  18. Suppression of the spin pumping in Pd/Ni{sub 81}Fe{sub 19} bilayers with nano-oxide layer

    SciTech Connect

    Kim, Duck-Ho; Kim, Hong-Hyoun; You, Chun-Yeol

    2011-08-15

    We demonstrate that the spin pumping effect can be effectively suppressed with a nano-oxide layer. Spin pumping effect manifests itself by an enhancement of the Gilbert damping parameter in normal metal/ferromagnetic hetero-structures, while many spintronics devices prefer smaller damping parameter. Since the spin pumping effect is directly related with the spin dependent interface conductance, we can modify the spin pumping by altering the interface conductance with the nano-oxide layer. We prepared series of Pd/Ni{sub 81}Fe{sub 19} bilayers with different pausing time between Pd and Ni{sub 81}Fe{sub 19} depositions in order to control the interface conductance. The Gilbert damping parameters are determined from the line-width measurements in the ferromagnetic resonance spectra for each pausing time sample. They are 0.0490, 0.0296, 0.0278, and 0.0251 for 0, 6, 30, and 60 s pausing time, respectively. We find that the damping parameter of Pd/Ni{sub 81}Fe{sub 19} is almost recovered to one of the Cu/Ni{sub 81}Fe{sub 19} bilayer with 60 s pausing time, while the static magnetic properties are not noticeably changed.

  19. Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands

    PubMed Central

    Grabovyi, Gennadii A; Erzunov, Dmitry A; Kazantsev, Alexey V; Latyshev, Gennadij V; Averin, Alexei D; Beletskaya., Irina P

    2017-01-01

    Cu- and Pd-catalyzed arylation of aminocholanes has been described for the first time. While this Cu-catalyzed protocol provides high yields in reactions of aminocholanes with iodoarenes, Pd catalysis was found to be preferable for the reactions of aminocholanes with dichloroanthraquinones. UV–vis titration of bis(cholanylamino)anthraquinones with a series of cations demonstrated their high binding affinity to Cu2+, Al3+, and Cr3+.

  20. 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

  1. Wetting reaction of Sn-Ag based solder systems on Cu substrates plated with Au and/or Pd layer

    NASA Astrophysics Data System (ADS)

    Liu, C. Y.; Li, Jian; Vandentop, G. J.; Choi, W. J.; Tu, K. N.

    2001-05-01

    The wetting behavior of SnAg based Pb-free solders on Cu and Cu substrates plated with Au, Pd, and Au/Pd thin films have been studied. The wetting angle and kinetics of interfacial reaction were measured. The Au-plated substrates exhibit better wetting than the Pd-plated substrates. In the case of SnAg on Pd-plated Cu, SEM observation revealed that the solder cap was surrounded by an innerring of Cu-Sn compound and an outer ring of Pd-Sn compound. This implies that the molten SnAg solder had removed the Pd and wetted the Cu directly in the equilibrium state. The effects of pre-doping Cu in the SnAg solder on wetting behavior were also investigated. We found that wettability decreases with increasing Cu content in the solder. We also observed that the SnAgCu solders have a lower Cu consumption rate than the SnAg solder.

  2. 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.

  3. Understanding the enhanced catalytic activity of Cu1@Pd3(111) in formic acid dissociation, a theoretical perspective

    NASA Astrophysics Data System (ADS)

    He, Feng; Li, Kai; Xie, Guangyou; Wang, Ying; Jiao, Menggai; Tang, Hao; Wu, Zhijian

    2016-06-01

    The bimetallic Cu1@Pd3(111) catalyst has been synthesized recently and exhibits better catalytic activity and durability compared with pure Pd(111) as anode catalyst in direct formic acid fuel cells (DFAFCs). In this work, we studied the reaction mechanism of formic acid dissociation on both Pd(111) and Cu1@Pd3(111) by using the density functional method. Our calculations showed that the surface adsorption of the poisoning species CO on Cu1@Pd3(111) is weakened mainly by the strain effect rather than the Cusbnd Pd ligand effect. The Cu1@Pd3(111) can effectively promote the catalytic activity for formic acid dissociation by decreasing the barrier of CO2 formation from the preferential trans-COOH intermediate and increasing the barrier of CO formation from the reduction of CO2. We found that the H atom accumulation, electron accumulation and low electrode potential could accelerate the catalyst deactivation due to the contamination of the poisoning species CO. Furthermore, under low anode potential, the Cu1@Pd3(111) has better durability than pure Pd(111), which can be attributed to the unfavorable CO formation and the favorable CO desorption.

  4. Giant Magnetoresistance and Coercivity of electrodeposited multilayered FeCoNi/Cu and CrFeCoNi/Cu

    NASA Astrophysics Data System (ADS)

    Shakya, P.; Cox, B.; Davis, D.

    2012-02-01

    The effect of Cr addition on electrodeposited multilayered nanowires CrFeCoNi/Cu was investigated from a magnetic property perspective: current perpendicular to the plane-Giant Magnetoresistance (CPP-GMR) and Coercivity (BH loops). The magnetic behavior of multilayered nanowires of CrFeNiCo/Cu was also affected by the alloy deposition potential, alloy pulsing time (layer thickness) and number of bilayers. Furthermore, the addition of Cr influenced both the nanowires GMR and Coercivity. Cr addition to the ferromagnetic FeCoNi layer induced a reduction in the room temperature GMR from 10.64% to 5.62%; however, the magnetic saturation field decreased from 0.45 to 0.27 T. The increase in the number of bilayers, from 1000 to 2500, resulted in a higher GMR value, 14.56% with 0.35 T magnetic saturation field. Addition of Cr to the ferromagnetic layer decreased the coercivity from 0.015 to 0.0054 T. Low saturation field CPP-GMR nanowires showing low coercivity at room temperature opens a new door for magnetic sensing devices. To the best of our knowledge, this is the first study on electrodeposited CrFeCoNi/Cu multilayered nanowires.

  5. H2 dissociation on γ-Al2O3 supported Cu/Pd atoms: A DFT investigation

    NASA Astrophysics Data System (ADS)

    Wang, Hongtao; Chen, Lijuan; Lv, Yongkang; Ren, Ruipeng

    2014-01-01

    The density functional theory (DFT) was applied to investigate the promotion effects of single Cu and Pd atoms deposition on γ-Al2O3 surface for the adsorption and dissociation of H2 molecule, which is of importance for many catalysis reactions. Due to its strong Lewis acidity, the tri-coordinated surface Al site was identified to be the most preferable site for both Cu and Pd location. The inner surface electrons rearrangement from O to Al of alumina was found to be a key factor to stabilize the Cu/Pd adsorption configurations, rather than the total electrons transfer between Cu/Pd and the surface. It was found that the supported Cu and Pd atoms are more active for H2 dissociation than the clean γ-Al2O3 surface. The supported Pd is more active than Cu for H2 dissociation. In addition, the metal-support interaction of the γ-Al2O3 supported Cu/Pd atoms are more favored than the metal-metal interaction of the metal clusters for the H2 dissociated adsorption.

  6. Nanoporous microtubes obtained from a Cu-Ni metallic wire

    NASA Astrophysics Data System (ADS)

    Marano, Emanuele Francesco; Lussana, Danilo; Castellero, Alberto; Baricco, Marcello

    2016-03-01

    Nanoporous microtubes of a nickel-copper alloy were obtained from a Cu-44Ni-1Mn (wt%) commercial wire (200 μm diameter). A new synthesis method was established through three steps: 1) partial oxidation of the wire at 1173 K in air, 2) removal of the inner unoxidized core by chemical etching, 3) reduction in 10 bar hydrogen atmosphere. During oxidation, the segregation of Cu and Ni occurred because of their different diffusion coefficients in the corresponding oxides. As a consequence, pores were formed by Kirkendall effect and due to selective chemical etching of the different oxides. Additional porosity formed because of volume contraction during reduction with hydrogen. After reduction, the microtube shows a composition gradient from the inner wall (almost pure nickel) to the outer wall (almost pure copper). The process allowed to obtain microtubes with tuneable wall thickness and inner pores around 180 ± 80 nm. The morphological features developed suggest improved capillarity properties for applications in MEMS.

  7. Hardening behavior after high-temperature solution treatment of Ag-20Pd-12Au-xCu alloys with different Cu contents for dental prosthetic restorations.

    PubMed

    Kim, Yonghwan; Niinomi, Mitsuo; Hieda, Junko; Nakai, Masaaki; Cho, Ken; Fukui, Hisao

    2014-07-01

    Ag-Pd-Au-Cu alloys have been used widely for dental prosthetic applications. Significant enhancement of the mechanical properties of the Ag-20Pd-12Au-14.5Cu alloy as a result of the precipitation of the β' phase through high-temperature solution treatment (ST), which is different from conventional aging treatment in these alloys, has been reported. The relationship between the unique hardening behavior and precipitation of the β' phase in Ag-20Pd-12Au-xCu alloys (x=6.5, 13, 14.5, 17, and 20mass%) subjected to the high-temperature ST at 1123K for 3.6ks was investigated in this study. Unique hardening behavior after the high-temperature ST also occurs in Ag-20Pd-12Au-xCu alloys (x=13, 17, and 20) with precipitation of the β' phase. However, hardening is not observed and the β' phase does not precipitate in the Ag-20Pd-12Au-6.5Cu alloy after the same ST. The tensile strength and 0.2% proof stress also increase in Ag-20Pd-12Au-xCu alloys (x=13, 14.5, 17, and 20) after the high-temperature ST. In addition, these values after the high-temperature ST increase with increasing Cu content in Ag-20Pd-12Au-xCu alloys (x=14.5, 17, and 20). The formation process of the β' phase can be explained in terms of diffusion of Ag and Cu atoms and precipitation of the β' phase. Clarification of the relationship between hardening and precipitation of the β' phase via high-temperature ST is expected to help the development of more effective heat treatments for hardening in Ag-20Pd-12Au-xCu alloys.

  8. The adsorption of 1,3-butadiene on Pd/Ni multilayers: The interplay between spin polarization and chemisorption strength

    SciTech Connect

    Gomez, Guillermina; Belelli, Patricia G.; Cabeza, Gabriela F.; Castellani, Norberto J.

    2010-12-15

    The adsorption of 1,3-butadiene (BD) on the Pd/Ni(1 1 1) multilayers has been studied using the VASP method in the framework of the density functional theory (DFT). The adsorption on two different configurations of the Pd{sub n}/Ni{sub m}(1 1 1) systems were considered. The most stable adsorption sites are dependent on the substrate composition and on the inclusion or not of spin polarization. On Pd{sub 1}Ni{sub 3}(1 1 1) surface, di-{pi}-cis and 1,2,3,4-tetra-{sigma} adsorption structures are the most stable for non-spin polarized (NSP) and spin polarized (SP) levels of calculation, respectively. Conversely, on Pd{sub 3}Ni{sub 1}(1 1 1) surface, the 1,2,3,4-tetra-{sigma} adsorption structure is the most stable for both NSP and SP levels, respectively. The magnetization of the Pd atoms strongly modifies the adsorption energy of BD and its most stable adsorption mode. On the other hand, as a consequence of BD adsorption, the Pd magnetization decreases. The smaller adsorption energies of BD and 1-butene on the Pd{sub 1}Ni{sub 3}(1 1 1) surface than on Pd(1 1 1) can be associated to the strained Pd overlayer deposited on Ni(1 1 1). -- Graphical Abstract: The adsorption of 1,3-butadiene on Pd/Ni(1 1 1) multilayers was theoretically studied. The most stable adsorption site depends on the substrate composition and on the inclusion of spin polarization. Display Omitted

  9. Intermixing in Cu/Ni multilayers induced by cold rolling

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Perepezko, J. H.; Larson, D.; Reinhard, D.

    2015-04-01

    Repeated cold rolling was performed on multilayers of Cu60/Ni40 and Cu40/Ni60 foil arrays to study the details of driven atomic scale interfacial mixing. With increasing deformation, there is a significant layer refinement down to the nm level that leads to the formation of a solid solution phase from the elemental end members. Intriguingly, the composition of the solid solution is revealed by an oscillation in the composition profile across the multilayers, which is different from the smoothly varying profile due to thermally activated diffusion. During the reaction, Cu mixed into Ni preferentially compared to Ni mixing into Cu, which is also in contrast to the thermal diffusion behavior. This is confirmed by observations from X-ray diffraction, electron energy loss spectrum and atom probe tomography. The diffusion coefficient induced by cold rolling is estimated as 1.7 × 10-17 m2/s, which cannot be attributed to any thermal effect. The effective temperature due to the deformation induced mixing is estimated as 1093 K and an intrinsic diffusivity db, which quantifies the tendency towards equilibrium in the absence of thermal diffusion, is estimated as 6.38 × 10-18 m2/s. The fraction of the solid solution phase formed is illustrated by examining the layer thickness distribution and is described by using an error function representation. The evolution of mixing in the solid solution phase is described by a simplified sinusoid model, in which the amplitude decays with increased deformation level. The promoted diffusion coefficient could be related to the effective temperature concept, but the establishment of an oscillation in the composition profile is a characteristic behavior that develops due to deformation.

  10. Intermixing in Cu/Ni multilayers induced by cold rolling

    SciTech Connect

    Wang, Z.; Perepezko, J. H.; Larson, D.; Reinhard, D.

    2015-04-28

    Repeated cold rolling was performed on multilayers of Cu60/Ni40 and Cu40/Ni60 foil arrays to study the details of driven atomic scale interfacial mixing. With increasing deformation, there is a significant layer refinement down to the nm level that leads to the formation of a solid solution phase from the elemental end members. Intriguingly, the composition of the solid solution is revealed by an oscillation in the composition profile across the multilayers, which is different from the smoothly varying profile due to thermally activated diffusion. During the reaction, Cu mixed into Ni preferentially compared to Ni mixing into Cu, which is also in contrast to the thermal diffusion behavior. This is confirmed by observations from X-ray diffraction, electron energy loss spectrum and atom probe tomography. The diffusion coefficient induced by cold rolling is estimated as 1.7 × 10{sup −17} m{sup 2}/s, which cannot be attributed to any thermal effect. The effective temperature due to the deformation induced mixing is estimated as 1093 K and an intrinsic diffusivity d{sub b}, which quantifies the tendency towards equilibrium in the absence of thermal diffusion, is estimated as 6.38 × 10{sup −18} m{sup 2}/s. The fraction of the solid solution phase formed is illustrated by examining the layer thickness distribution and is described by using an error function representation. The evolution of mixing in the solid solution phase is described by a simplified sinusoid model, in which the amplitude decays with increased deformation level. The promoted diffusion coefficient could be related to the effective temperature concept, but the establishment of an oscillation in the composition profile is a characteristic behavior that develops due to deformation.

  11. Evaluation of the amalgamation reaction of experimental Ag-Sn-Cu alloys containing Pd using a mercury plating technique.

    PubMed

    Koike, Marie; Ferracane, Jack L; Fujii, Hiroyuki; Okabe, Toru

    2003-09-01

    A mercury plating technique was used to determine the phases forming on experimental Ag-Sn-Cu alloy powders (with and without Pd) exposed to electrolytically deposited mercury. Four series of alloy powders were made: a) 1.5% Pd with 10-14% Cu (CU series); b) 1.0% Pd with 10-14% Cu (1PD series); c) 1.5% Pd with different ratios of Ag3Sn (gamma) to Ag4Sn (beta) with 12% Cu (AGSN series); and d) 9-13% Cu with no Pd (NOPD series). Each powder was pressed on a freshly prepared amalgam specimen made from the same powder and metallographically polished until cross sections appeared; mercury was electroplated on the alloy particles. Alloy powders, amalgams and electroplated specimens were examined using XRD and SEM/EDS. XRD confirmed the presence of gamma2 in amalgams made from alloys with Cu < 13% or with Ag3Sn/Ag4Sn > 0.8. Specimens with moderately plated Hg showed gamma1 (Ag2Hg3) polyhedra and eta' Cu6Sn5, but not gamma2. This method effectively identifies alloys prone to forming gamma2.

  12. Diffusion properties of Cu(0 0 1)- c(2 × 2)-Pd surface alloys

    NASA Astrophysics Data System (ADS)

    Eremeev, S. V.; Rusina, G. G.; Chulkov, E. V.

    2007-09-01

    Structural and diffusion properties of a Cu(0 0 1)- c(2 × 2)-Pd surface and sub-surface ordered alloys are studied by using interaction potentials obtained from the embedded-atom method. The calculated diffusion energies are in agreement with observed kinetics of the surface alloy formation and confirm stability of the underlayer alloy. Activation energy of planar diffusion of palladium at the initial stage of the alloy formation as well as the activation energy of the overlayer-underlayer diffusion of the Pd atoms are in good agreement with those obtained by the scanning tunneling microscopy and low energy electron diffraction measurements, respectively.

  13. Carbon tolerance of Ni-Cu and Ni-Cu/YSZ sub-μm sized SOFC thin film model systems

    NASA Astrophysics Data System (ADS)

    Götsch, Thomas; Schachinger, Thomas; Stöger-Pollach, Michael; Kaindl, Reinhard; Penner, Simon

    2017-04-01

    Thin films of YSZ, unsupported Ni-Cu 1:1 alloy phases and YSZ-supported Ni-Cu 1:1 alloy solutions have been reproducibly prepared by magnetron sputter deposition on Si wafers and NaCl(001) single crystal facets at two selected substrate temperatures of 298 K and 873 K. Subsequently, the layer properties of the resulting sub-μm thick thin films as well as the tendency towards carbon deposition following treatment in pure methane at 1073 K has been tested comparatively. Well-crystallized structures of cubic YSZ, cubic NiCu and cubic NiCu/YSZ have been obtained following deposition at 873 K on both substrates. Carbon is deposited on all samples following the trend Ni-Cu (1:1) = Ni-Cu (1:1)/YSZ > pure YSZ, indicating that at least the 1:1 composition of layered Ni-Cu alloy phases is not able to suppress the carbon deposition completely, rendering it unfavorable for usage as anode component in sub-μm sized fuel cells. It is shown that surfaces with a high Cu/Ni ratio nevertheless prohibit any carbon deposition.

  14. Orthogonal Pd- and Cu-Based Catalyst Systems for the C- and N-Arylation of Oxindoles

    PubMed Central

    Altman, Ryan A.; Hyde, Alan M.; Huang, Xiaohua; Buchwald, Stephen L.

    2008-01-01

    In the cross-coupling reactions of unprotected oxindoles with aryl halides, Pd- and Cu-based catalyst systems displayed orthogonal chemoselectivity. A Pd/dialkylbiarylphosphine-based catalyst system chemoselectively arylated oxindole at the 3-position, while arylation occurred exclusively at the nitrogen using a Cu/diamine-based catalyst system. Computational examination of the relevant L1Pd(Ar)(oxindolate) and diamine-Cu-(oxindolate) species were performed to gain mechanistic insight into the controlling features of the observed chemoselectivity. PMID:18588302

  15. Photoelectron angular distributions of ultrathin Ni/Cu(001) films

    SciTech Connect

    Mankey, G.J.; Subramanian, K.; Stockbauer, R.L.; Kurtz, R.L.

    1996-12-31

    The authors present measurements of the evolution with film thickness of the 3d electronic states at the Fermi energy of ultrathin Ni films. The morphology and thickness of the films is determined from x-ray photoelectron spectroscopy, x-ray photoelectron diffraction and x-ray magnetic linear dichroism using synchrotron radiation. Photoelectron angular distributions were measured using an ellipsoidal mirror analyzer. Even at submonolayer Ni coverages, the 3d electronic states exhibit bulk-like properties. This is attributed to the short screening length of electrons in metals, the localization of the 3d electrons, the similarity of the Ni and Cu ion cores, and finally the interaction with the underlying fcc periodic potential.

  16. Hidden amorphous phase and reentrant supercooled liquid in Pd-Ni-P metallic glasses

    NASA Astrophysics Data System (ADS)

    Lan, S.; Ren, Y.; Wei, X. Y.; Wang, B.; Gilbert, E. P.; Shibayama, T.; Watanabe, S.; Ohnuma, M.; Wang, X.-L.

    2017-03-01

    An anomaly in differential scanning calorimetry has been reported in a number of metallic glass materials in which a broad exothermal peak was observed between the glass and crystallization temperatures. The mystery surrounding this calorimetric anomaly is epitomized by four decades long studies of Pd-Ni-P metallic glasses, arguably the best glass-forming alloys. Here we show, using a suite of in situ experimental techniques, that Pd-Ni-P alloys have a hidden amorphous phase in the supercooled liquid region. The anomalous exothermal peak is the consequence of a polyamorphous phase transition between two supercooled liquids, involving a change in the packing of atomic clusters over medium-range length scales as large as 18 Å. With further temperature increase, the alloy reenters the supercooled liquid phase, which forms the room-temperature glass phase on quenching. The outcome of this study raises a possibility to manipulate the structure and hence the stability of metallic glasses through heat treatment.

  17. Cu-Ni core-shell nanoparticles: structure, stability, electronic, and magnetic properties: a spin-polarized density functional study

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Wang, Xinyan; Liu, Jianlan; Yang, Yanhui

    2017-02-01

    Bimetallic core-shell nanoparticles (CSNPs) have attracted great interest not only because of their superior stability, selectivity, and catalytic activity but also due to their tunable properties achieved by changing the morphology, sequence, and sizes of both core and shell. In this study, the structure, stability, charge transfer, electronic, and magnetic properties of 13-atom and 55-atom Cu and Cu-Ni CSNPs were investigated using the density functional theory (DFT) calculations. The results show that Ni@Cu CSNPs with a Cu surface shell are more energetically favorable than Cu@Ni CSNPs with a Ni surface shell. Interestingly, three-shell Ni@Cu12@Ni42 is more stable than two-shell Cu13@Ni42, while two-shell Ni13@Cu42 is more stable than three-shell Cu@Ni12@Cu42. Analysis of Bader charge illustrates that the charge transfer increases from Cu core to Ni shell in Cu@Ni NPs, while it decreases from Ni core to Cu shell in Ni@Cu NPs. Furthermore, the charge transfer results that d-band states have larger shift toward the Fermi level for the Ni@Cu CSNPs with Cu surface shell, while the Cu@Ni CSNPs with Ni surface shell have similar d-band state curves and d-band centers with the monometallic Ni NPs. In addition, the Cu-Ni CSNPs possess higher magnetic moment when the Ni atoms aggregated at core region of CSNPs, while having lower magnetic moment when the Ni atoms segregate on surface region. The change of the Cu atom location in CSNPs has a weak effect on the total magnetic moment. Our findings provide useful insights for the design of bimetallic core-shell catalysts.

  18. Preparation and electrochemistry of Pd-Ni/Si nanowire nanocomposite catalytic anode for direct ethanol fuel cell.

    PubMed

    Miao, Fengjuan; Tao, Bairui; Chu, Paul K

    2012-04-28

    A new silicon-based anode suitable for direct ethanol fuel cells (DEFCs) is described. Pd-Ni nanoparticles are coated on Si nanowires (SiNWs) by electroless co-plating to form the catalytic materials. The electrocatalytic properties of the SiNWs and ethanol oxidation on the Pd-Ni catalyst (Pd-Ni/SiNWs) are investigated electrochemically. The effects of temperature and working potential limit in the anodic direction on ethanol oxidation are studied by cyclic voltammetry. The Pd-Ni/SiNWs electrode exhibits higher electrocatalytic activity and better long-term stability in an alkaline solution. It also yields a larger current density and negative onset potential thus boding well for its application to fuel cells.

  19. New approach to phosphinoalkynes based on Pd- and Ni-catalyzed cross-coupling of terminal alkynes with chlorophosphanes.

    PubMed

    Beletskaya, Irina P; Afanasiev, Vladimir V; Kazankova, Marina A; Efimova, Irina V

    2003-11-13

    [reaction: see text] The first example of direct phosphination of terminal alkynes with chlorophosphanes catalyzed by Ni or Pd complexes is described. Both aromatic and aliphatic terminal acetylenes undergo the coupling reaction to give corresponding coupling product in high yield.

  20. Corrosion resistance evaluation of Pd-free Ag-Au-Pt-Cu dental alloys.

    PubMed

    Fujita, Takeshi; Shiraishi, Takanobu; Takuma, Yasuko; Hisatsune, Kunihiro

    2011-01-01

    The corrosion resistance of nine experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.9% NaCl solution was investigated using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). CV measurements revealed that the breakdown potential (E(bd)) and zero current potential (E(zc)) increased with increasing Au/(Au+Ag) atomic ratio. Thus, the Au/(Au+Ag) atomic ratio, but not the Cu content, influenced the corrosion resistance of Ag-Au-Pt-Cu alloys. After the forward scan of CV, both optical and scanning electron microscope images showed that in all the experimental alloys, the matrix phase was corroded but not the second phase. From corrosion resistance viewpoint, the Ag-Au-Pt-Cu alloys seemed to be suitable for clinical application.

  1. Influence of surface topography on RBS measurements: case studies of (Cu/Fe/Pd) multilayers and FePdCu alloys nanopatterned by self-assembly

    NASA Astrophysics Data System (ADS)

    Krupinski, M.; Perzanowski, M.; Zabila, Y.; Zarzycki, A.; Marszałek, M.

    2017-03-01

    In this paper the influence of surface topography on Rutherford backscattering spectrometry (RBS) is discussed. (Cu/Fe/Pd) multilayers with total thickness of about 10 nm were deposited by physical vapor deposition on self-organized array of SiO2 nanoparticles with the size of 50 nm and 100 nm. As a reference, the multilayered systems were also prepared on flat substrates under the same conditions. After the deposition, morphology of the systems was studied by scanning electron microscopy (SEM), while chemical analysis was performed using Rutherford backscattering spectrometry. It was found that the RBS spectra and determined compositions for flat and patterned multilayers differ. The difference is discussed by taking into account the effect of additional inelastic scattering and energy straggling occurring due to developed topography of patterned systems. Then, the multilayers were annealed in 600 °C in order to obtain FePdCu alloy. The phenomenon of solid-state dewetting resulted in the formation of isolated alloy islands on the top of SiO2 nanoparticles. The SEM and RBS analysis were repeated showing correlation between the size distribution of obtained alloy islands and broadening of peaks appearing in RBS spectra. Invited talk at 8th International Workshop on Advanced Materials Science and Nanotechnology (IWAMSN2016), 8–12 November 2016, Ha Long City, Vietnam.

  2. Nanoalloying and phase transformations during thermal treatment of physical mixtures of Pd and Cu nanoparticles

    PubMed Central

    Mukundan, Vineetha; Yin, Jun; Joseph, Pharrah; Luo, Jin; Shan, Shiyao; Zakharov, Dmitri N; Zhong, Chuan-Jian; Malis, Oana

    2014-01-01

    Nanoscale alloying and phase transformations in physical mixtures of Pd and Cu ultrafine nanoparticles are investigated in real time with in situ synchrotron-based x-ray diffraction complemented by ex situ high-resolution transmission electron microscopy. The combination of metal–support interaction and reactive/non-reactive environment was found to determine the thermal evolution and ultimate structure of this binary system. At 300 °C, the nanoparticles supported on silica and carbon black intermix to form a chemically ordered CsCl-type (B2) alloy phase. The B2 phase transforms into a disordered fcc alloy at higher temperature (> 450 °C). The alloy nanoparticles supported on silica and carbon black are homogeneous in volume, but evidence was found of Pd surface enrichment. In sharp contrast, when supported on alumina, the two metals segregated at 300 °C to produce almost pure fcc Cu and Pd phases. Upon further annealing of the mixture on alumina above 600 °C, the two metals interdiffused, forming two distinct disordered alloys of compositions 30% and 90% Pd. The annealing atmosphere also plays a major role in the structural evolution of these bimetallic nanoparticles. The nanoparticles annealed in forming gas are larger than the nanoparticles annealing in helium due to reduction of the surface oxides that promotes coalescence and sintering. PMID:27877663

  3. Corrosion properties of Ag-Au-Cu-Pd system alloys containing indium.

    PubMed

    Hattori, Masayuki; Tokizaki, Teruhiko; Matsumoto, Michihiko; Oda, Yutaka

    2010-01-01

    In this study, the corrosion resistance of Ag-Au-Cu-Pd system alloys consisting of 5 or 10 mass% indium was evaluated. Levels of element release and tarnish were determined and electrochemical measurements performed. Results were compared with those for commercial silver-palladium-gold alloy. In terms of electrochemical behavior, the transpassive potential of these experimental alloys was 168-248mV. Experimental alloys with 25 mass% Au showed similar corrosion resistance to control gold-silver-palladium alloy. Amount of released elements was 14-130microg/cm(2) at 7 days, which is in the allowable range for dental alloys. Addition of indium to Ag-Au-Cu-10mass%Pd system alloys was effective in increasing resistance to tarnish and alloys containing 10 mass% of indium showed a minimal decrease in L(*) values after immersion. These findings indicate that 25Au-37.5Ag-15Cu-10Pd-2Zn-10In-0.5Ir alloy is applicable in dental practice.

  4. Thermal Stability of Cu/NiSi-Contacted p+n Shallow Junction

    NASA Astrophysics Data System (ADS)

    Wang, Chao-Chun; Lin, Hsin-Hung; Chen, Mao-Chieh

    2004-09-01

    The thermal stability of Cu/NiSi-contacted p+n shallow junction diodes was investigated with respect to their electrical characteristics and metallurgical reactions. The TaN/Cu/NiSi/p+n junction diode remained intact after 30 min thermal annealing at temperatures of up to 350°C. Upon annealing at 375°C, a marked increase in reverse bias leakage current occurred, and secondary ion mass spectrometry (SIMS) analysis indicated that Cu started to penetrate into the NiSi-contacted shallow junction region. After a higher temperature annealing at 425°C, a Cu3Si phase was formed. The failure of the TaN/Cu/NiSi/p+n junction diodes is attributed to the penetration of Cu through the NiSi layer into the junction region, leading to junction degradation by introducing deep-level trap states and the eventual formation of Cu3Si.

  5. 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.

  6. Reaction pathways of furfural, furfuryl alcohol and 2-methylfuran on Cu(111) and NiCu bimetallic surfaces

    SciTech Connect

    Xiong, Ke; Wan, Weiming; Chen, Jingguang G.

    2016-02-23

    Hydrodeoxygenation (HDO) is an important reaction for converting biomass-derived furfural to value-added 2-methylfuran, which is a promising fuel additive. In this work, the HDO of furfural to produce 2-methylfuran occurred on the NiCu bimetallic surfaces prepared on either Ni(111) or Cu(111). The reaction pathways of furfural were investigated on Cu(111) and Ni/Cu(111) surfaces using density functional theory (DFT) calculations, temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS) experiments. These studies provided mechanistic insights into the effects of bimetallic formation on enhancing the HDO activity. Specifically, furfural weakly adsorbed on Cu(111), while it strongly adsorbed on Ni/Cu(111) through an η2(C,O) configuration which led to the HDO of furfural on Ni/Cu(111). Lastly, the ability to dissociate H2 on Ni/Cu(111) is also an important factor for enhancing the HDO activity over Cu(111).

  7. Reaction pathways of furfural, furfuryl alcohol and 2-methylfuran on Cu(111) and NiCu bimetallic surfaces

    NASA Astrophysics Data System (ADS)

    Xiong, Ke; Wan, Weiming; Chen, Jingguang G.

    2016-10-01

    Hydrodeoxygenation (HDO) is an important reaction for converting biomass-derived furfural to value-added 2-methylfuran, which is a promising fuel additive. In this work, the HDO of furfural to produce 2-methylfuran occurred on the NiCu bimetallic surfaces prepared on either Ni(111) or Cu(111). The reaction pathways of furfural were investigated on Cu(111) and Ni/Cu(111) surfaces using density functional theory (DFT) calculations, temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) experiments. These studies provided mechanistic insights into the effects of bimetallic formation on enhancing the HDO activity. Specifically, furfural weakly adsorbed on Cu(111), while it strongly adsorbed on Ni/Cu(111) through an η2(C,O) configuration, which led to the HDO of furfural on Ni/Cu(111). The ability to dissociate H2 on Ni/Cu(111) is also an important factor for enhancing the HDO activity over Cu(111).

  8. Reaction pathways of furfural, furfuryl alcohol and 2-methylfuran on Cu(111) and NiCu bimetallic surfaces

    DOE PAGES

    Xiong, Ke; Wan, Weiming; Chen, Jingguang G.

    2016-02-23

    Hydrodeoxygenation (HDO) is an important reaction for converting biomass-derived furfural to value-added 2-methylfuran, which is a promising fuel additive. In this work, the HDO of furfural to produce 2-methylfuran occurred on the NiCu bimetallic surfaces prepared on either Ni(111) or Cu(111). The reaction pathways of furfural were investigated on Cu(111) and Ni/Cu(111) surfaces using density functional theory (DFT) calculations, temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS) experiments. These studies provided mechanistic insights into the effects of bimetallic formation on enhancing the HDO activity. Specifically, furfural weakly adsorbed on Cu(111), while it strongly adsorbed on Ni/Cu(111)more » through an η2(C,O) configuration which led to the HDO of furfural on Ni/Cu(111). Lastly, the ability to dissociate H2 on Ni/Cu(111) is also an important factor for enhancing the HDO activity over Cu(111).« less

  9. CO oxidation over sonochemically synthesized Pd-Cu/Al2O3 nanocatalyst used in hydrogen purification: effect of Pd loading and ultrasound irradiation time.

    PubMed

    Estifaee, Pooya; Haghighi, Mohammad; Mohammadi, Nima; Rahmani, Farhad

    2014-05-01

    The bimetallic Pd-Cu nanocatalysts with different Pd loadings and ultrasonic irradiation times were sonochemically synthesized and their activities toward CO oxidation were investigated. XRD, FESEM, TEM, BET, FTIR and TG-DTG techniques were employed in nanocatalysts characterization. XRD data confirmed formation of CuAl2O4 spinel with an average crystallite size of 4.9 nm. FESEM images revealed more uniform pattern and also fewer agglomerations were observed by increasing ultrasonic irradiation time. In agreement with FESEM result, TEM images depicted nanoparticles and uniform dispersion of active phase over alumina. BET surface analysis showed that increasing the Pd loading has no significant effect on surface area; whereas by increasing irradiation time the surface area increases slightly. Catalytic performance tests of synthesized samples showed that Pd(1.5%)-Cu(20%)/Al2O3 with 95 min ultrasonic irradiation time had the best activity over the course of reaction. In addition, increasing CO at feed composition revealed that among synthesized nanocatalysts with 0.5%, 1% and 1.5% of Pd, synthesized sample with 1.5% of Pd had the best low-temperature activity.

  10. Pt@Pd(x)Cu(y)/C core-shell electrocatalysts for oxygen reduction reaction in fuel cells.

    PubMed

    Cochell, T; Manthiram, A

    2012-01-17

    A series of carbon-supported core-shell nanoparticles with Pd(x)Cu(y)-rich cores and Pt-rich shells (Pt@Pd(x)Cu(y)/C) has been synthesized by a polyol reduction of the precursors followed by heat treatment to obtain the Pd(x)Cu(y)/C (1 ≤ x ≤ 3 and 0 ≤ y ≤ 5) cores and the galvanic displacement of Pd(x)Cu(y) with [PtCl(4)](2-) to form the Pt shell. The nanoparticles have also been investigated with respect to the oxygen reduction reaction (ORR) in proton-exchange-membrane fuel cells (PEMFCs). X-ray diffraction (XRD) analysis suggests that the cores are highly alloyed and that the galvanic displacement results in a certain amount of alloying between Pt and the underlying Pd(x)Cu(y) alloy core. Transmission electron microscopy (TEM) images show that the Pt@Pd(x)Cu(y)/C catalysts (where y > 0) have mean particle sizes of <8 nm. Compositional analysis by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) clearly shows Pt enrichment in the near-surface region of the nanoparticles. Cyclic voltammograms show a positive shift of as much as 40 mV for the onset of Pt-OH formation in the Pt@Pd(x)Cu(y)/C electrocatalysts compared to that in Pt/C. Rotating disk electrode (RDE) measurements of Pt@PdCu(5)/C show an increase in the Pt mass activity by 3.5-fold and noble metal activity by 2.5-fold compared to that of Pt/C. The activity enhancements in RDE and PEMFC measurements are believed to be a result of the delay in the onset of Pt-OH formation.

  11. The formation of the reacted interface for the Si/Cu/Pd system: An ultraviolet photoemission study

    NASA Astrophysics Data System (ADS)

    Abbati, I.; Carbone, C.; Ciucci, G.; Michelis, B. De; Fasana, A.; Mondini, R.

    1983-12-01

    Various coverage of Pd were deposited on substrates formed by few layers of Cu on Si (111) face at room temperature. Photoemission results show that the formation of Pd 2 Si-like compound is strongly inhibited by the presence of the Cu/Si interlayer and suggest that for the studied system the heat of formation of the compound is not the only parameter that controls the thickness of the intermixed region.

  12. The new class of superconducting quaternary R-T-B-C systems (R= rare earth, T = Ni, Pd)

    NASA Astrophysics Data System (ADS)

    Gupta, L. C.; Nagarajan, R.; Godart, C.; Dhar, S. K.; Mazumdar, Chandan; Hossain, Zakir; Levy-Clement, C.; Padalia, B. d.; Vijayaraghavan, R.

    1994-12-01

    Our discovery of superconductivity (SC) at an elevated temperature ( ∼12K ) in the system Y-Ni-B-C [1-4] has opened up an entirely new area of research in superconductivity in intermetallics. Our specific heat measurements show that YNi 2B 2C is strongly-coupled superconductor. SC and magnetism coexist, below 7K, in ErNi 2B 2C. From μ-SR studies, carried out on LuNi 2B 2C and TmNi 2B 2C, Ni-atoms are inferred to carry local moment. Substituents such as Th and Gd (at the Y-sites) and Fe and Co (at the Ni-sites) depress T c of YNi 2B 2C. Superconductivity is quenched in Y 0.9U 0.1Ni 2B 2C. In multiphase Y-Pd-B-C system (obtained by replacing Ni by Pd), we observe two SC-transitions, T c ∼ 22K and 10K. LuPd 4BC 0.2 has a minority SC-phase with T c ∼ 10 K. Microwave absorption has been used to study the temperature dependence of the lower critical field, H cl, in YPd 5B 3C 0.35. ThNi 2B 2C, a multiphase material, exhibits SC at ∼ 5K whereas two SC transitions are observed in ThPd 2B 2C (T c∼20K and 14K) and in ThPd 4BC. No SC is observed in U-based Ni-and Pd-borocarbides and in YT 2B 2C (T = Co, Rh, Ir and Os) down to 4.2K.

  13. Size-Dependent Disorder-Order Transformation in the Synthesis of Monodisperse Intermetallic PdCu Nanocatalysts.

    PubMed

    Wang, Chenyu; Chen, Dennis P; Sang, Xiahan; Unocic, Raymond R; Skrabalak, Sara E

    2016-06-28

    The high performance of Pd-based intermetallic nanocatalysts has the potential to replace Pt-containing catalysts for fuel-cell reactions. Conventionally, intermetallic particles are obtained through the annealing of nanoparticles of a random alloy distribution. However, this method inevitably leads to sintering of the nanoparticles and generates polydisperse samples. Here, monodisperse PdCu nanoparticles with the ordered B2 phase were synthesized by seed-mediated co-reduction using PdCu nanoparticle seeds with a random alloy distribution (A1 phase). A time-evolution study suggests that the particles must overcome a size-dependent activation barrier for the ordering process to occur. Characterization of the as-prepared PdCu B2 nanoparticles by electron microscopy techniques revealed surface segregation of Pd as a thin shell over the PdCu core. The ordered nanoparticles exhibit superior activity and durability for the oxygen reduction reaction in comparison with PdCu A1 nanoparticles. This seed-mediated co-reduction strategy produced monodisperse nanoparticles ideally suited for structure-activity studies. Moreover, the study of their growth mechanism provides insights into the size dependence of disorder-order transformations of bimetallic alloys at the nanoscale, which should enable the design of synthetic strategies toward other intermetallic systems.

  14. Abnormal magnetization behaviors in Sm-Ni-Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Yang, W. Y.; Zhang, Y. F.; Zhao, H.; Chen, G. F.; Zhang, Y.; Du, H. L.; Liu, S. Q.; Wang, C. S.; Han, J. Z.; Yang, Y. C.; Yang, J. B.

    2016-06-01

    The magnetization behaviors in Sm-Ni-Fe-Cu alloys at low temperatures have been investigated. It was found that the hysteresis loops show wasp-waisted character at low temperatures, which has been proved to be related to the existence of multi-phases, the Fe/Ni soft magnetic phases and the CaCu5-type hard magnetic phase. A smooth-jump behavior of the magnetization is observed at T>5 K, whereas a step-like magnetization process appears at T<5 K. The CaCu5-type phase is responsible for such abnormal magnetization behavior. The magnetic moment reversal model with thermal activation is used to explain the relation of the critical magnetic field (Hcm) to the temperature (T>5 K). The reversal of the moment direction has to cross over an energy barrier of about 6.6×10-15 erg. The step-like jumps of the magnetization below 5 K is proposed to be resulted from a sharp increase of the sample temperature under the heat released by the irreversible domain wall motion.

  15. Atomic-scale imaging and electronic structure determination of catalytic sites on Pd/Cu near surface alloys

    SciTech Connect

    Tierney, H.L.; Baber, A.E.; Sykes, E.C.H.

    2009-04-15

    Water-gas shift chemistry provides a useful method for producing hydrogen from coal; however, fuel cell applications demand that this hydrogen be free of impurities. Due to their unique properties, Pd/Cu alloys represent an import class of materials used for H purification membranes and also serve as the active metals in many heterogeneous catalysts. Little is known about how Pd and Cu interact electronically in these mixed systems and there is debate in the literature over the direction of charge transfer between the two species. This study used the differential conductance (dI/dV) spectroscopy capabilities of a low-temperature scanning tunneling microscope (STM) to investigate the atomic-scale electronic structure of Pd/Cu surface alloys. dI/dV spectroscopy gives a direct measure of the local density of states of surface sites with subnanometer precision. Results from this work demonstrate that individual, isolated Pd atoms in a Cu lattice are almost electronically identical to their host atoms. Over an energy range that spans 1 eV on either side of the Fermi level, the only significant electronic difference between isolated Pd and their host Cu atoms is that Pd atoms have a very slightly depleted electron density in the region of the Cu surface state maximum.

  16. PGE geochemistry and Re Os dating of massive sulfide ores from the Baimazhai Cu Ni deposit, Yunnan province, China

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoming; Wang, Shengwei; Sun, Weidong; Shi, Guiyong; Sun, Yali; Xiong, Dexin; Qu, Wenjun; Du, Andao

    2008-09-01

    The Baimazhai deposit in Yunnan Province is one of the largest Cu-Ni sulfide deposits hosted in mafic-ultramafic intrusions in China. Concentrations of platinum-group elements (PGE) in massive sulfide ores and host rocks from Baimazhai were determined by using inductively coupled plasma mass spectrometry (ICP-MS) following nickel sulfide fire assay pre-concentration. The results show that the total PGE (ΣPGE) are quite low, decreasing gradually from central massive ores (78.2-556 ppb) to olivine pyroxenite (0.472-67.0 ppb), gabbro (0.847 ppb) and, websterite (0.76-0.809). The intruded lamprophyre dykes also show low ΣPGE (2.98-4.07 ppb). The ΣPGE exhibit obvious positive correlations with Au, Ni and Cu contents. Primitive mantle normalized PGE patterns of the massive Cu-Ni ores are of the Pt-Pd type with relatively steep and trough-like patterns, which are similar to those of the host rocks. In addition, the Pt/Pd and Cu/Pd ratios of the massive sulfide ores are similar to those of olivine pyroxenite, gabbro and websterite. These characteristics suggest that sulfides in the massive ores are of magmatic origin, co-genetic with their host rocks. The relatively high Pt/Pd ratios of the Baimazhai massive sulfide ores (averaging 0.83) and their host rocks imply that the Baimazhai sulfides formed in a single sulfide saturation event, but not through multiple sulfide injections. High Ir contents (0.77-5.52 ppb, averaging 2.35 ppb) and dramatically variable Pd/Ir ratios (4.76-296, averaging 138) of the massive sulfide ores suggest that the Baimazhai sulfide ores might have suffered significant late stage hydrothermal alteration. The Baimazhai massive sulfide ores yield a Re-Os isochron age of 259 ± 20 Ma (MSWD = 0.025), which is the same as the major eruption stage of the Emeishan large igneous province and the Baimazhai intrusion, further supporting their magmatic origin. The initial 187Os/ 188Os value of 0.456 ± 0.026 indicates that crustal contamination has played

  17. 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.

  18. Correlation between Mechanical Behavior and Actuator-type Performance of Ni-Ti-Pd High-temperature Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Bigelow, Glen S.; Padula, Santo A., II; Garg, Anita; Noebe, Ronald D.

    2007-01-01

    High-temperature shape memory alloys in the NiTiPd system are being investigated as lower cost alternatives to NiTiPt alloys for use in compact solid-state actuators for the aerospace, automotive, and power generation industries. A range of ternary NiTiPd alloys containing 15 to 46 at.% Pd has been processed and actuator mimicking tests (thermal cycling under load) were used to measure transformation temperatures, work behavior, and dimensional stability. With increasing Pd content, the work output of the material decreased, while the amount of permanent strain resulting from each load-biased thermal cycle increased. Monotonic isothermal tension testing of the high-temperature austenite and low temperature martensite phases was used to partially explain these behaviors, where a mismatch in yield strength between the austenite and martensite phases was observed at high Pd levels. Moreover, to further understand the source of the permanent strain at lower Pd levels, strain recovery tests were conducted to determine the onset of plastic deformation in the martensite phase. Consequently, the work behavior and dimensional stability during thermal cycling under load of the various NiTiPd alloys is discussed in relation to the deformation behavior of the materials as revealed by the strain recovery and monotonic tension tests.

  19. Graphene as a diffusion barrier for isomorphous systems: Cu-Ni system

    NASA Astrophysics Data System (ADS)

    Roy, Apurba; Punith Kumar, M. K.; Srivastava, Chandan

    2016-02-01

    Electrochemical exfoliation technique using the pyrophosphate anion derived from tetra sodium pyrophosphate was employed to produce graphene. As-synthesized graphene was then drop dried over a cold rolled Cu sheet. Ni coating was then electrodeposited over bare Cu and graphene-Cu substrates. Both substrates were then isothermally annealed at 800 °C for 3 h. WDS analysis showed substantial atomic diffusion in annealed Ni-Cu sample. Cu-graphene-Ni sample, on the other hand, showed negligible diffusion illustrating the diffusion barrier property of the graphene coating.

  20. Cu-Ni-Fe anodes having improved microstructure

    DOEpatents

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

    A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu--Ni--Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

  1. Barrierless Cu-Ni-Mo Interconnect Films with High Thermal Stability Against Silicide Formation

    NASA Astrophysics Data System (ADS)

    Li, X. N.; Liu, L. J.; Zhang, X. Y.; Chu, J. P.; Wang, Q.; Dong, C.

    2012-12-01

    Cu-Ni-Mo alloys were investigated to increase thermal stability against silicide formation. The alloy compositions were chosen such that an insoluble element (Mo) solute was dissolved into Cu via a third element Ni which is soluble in both Cu and Ni. Thin-film Cu-Ni-Mo alloys were prepared by magnetron sputtering. The films with Mo/Ni ratio of 1/12 exhibited low electrical resistivities in combination with high thermal stabilities against silicide formation, in support of a tentative "cluster-plus-glue-atom" model for stable solid solutions. In particular, a (Mo1/13Ni12/13)0.3Cu99.7 sample reached a minimum resistivity of 2.6 μΩ cm after 400°C/1 h annealing and remained highly conductive with resistivities below 3 μΩ cm even after 400°C/40 h annealing. These alloys are promising candidates for future interconnect materials.

  2. Adsorption and dissociation of H2S on monometallic and monolayer bimetallic Ni/Pd(111) surfaces: A first-principles study

    NASA Astrophysics Data System (ADS)

    Li, Yi; Huang, Pan; Tao, Dandan; Wu, Juan; Qiu, Mei; Huang, Xin; Ding, Kaining; Chen, Wenkai; Su, Wenyue; Zhang, Yongfan

    2016-11-01

    Periodic density functional theory calculations have been performed to investigate the adsorption structures and dissociative reaction pathways for H2S molecule on Ni(111), Pd(111) and Ni/Pd(111) monolayer bimetallic surfaces with surface monolayer and subsurface monolayer structures. Our results indicate that, for the molecular adsorption mode, the introducing Pd atoms on Ni(111) can enhance the binding strength between H2S and the surface, while an opposite effect is achieved when the Ni monolayer is formed on Pd(111) surface. The decompositions of H2S molecule on all Ni/Pd(111) surfaces are exothermic, especially for the surfaces that the top layer is composed of Ni atoms. According to the predicted minimum energy paths that connect the molecular and dissociative states, two elementary steps are found for all Ni/Pd(111) metal surfaces, and the breaking of the first Hsbnd S bond is the rate-determining step for the H2S dissociation. Our results reveal that in most cases, the decomposition of H2S molecule on the monometallic and Ni/Pd(111) monolayer bimetallic surfaces is easy to happen. However, on the monolayer Ni-Pd(111) surface, there is a competition between the trapping-desorption channel and activated dissociation channel, which implies that depositing one monolayer Ni on a Pd(111) surface may help reducing sulfur poisoning by hindering the dissociation of H2S molecule.

  3. Reaction Mechanism and Mechanical Properties of the Flip-Chip Sn-3.0Ag-0.5Cu Solder Bump with Cu/Ni- xCu/Ti Underbump Metallization After Various Reflows

    NASA Astrophysics Data System (ADS)

    Peng, Chung-Nan; Duh, Jenq-Gong

    2009-12-01

    Ni underbump metallization (UBM) has been widely used as the diffusion barrier between solder and Cu pads. To retard the fast dissolution rate of Ni UBM, Cu was added into Ni thin films. The Ni-Cu UBM can provide extra Cu to the solders to maintain the Cu6Sn5 intermetallic compound (IMC) at the interface, which can thus significantly decrease the Ni dissolution rate. In this study, the Cu content of the sputtered Cu/Ni- xCu/Ti UBM was varied from 0 wt.% to 20 wt.%. Sn-3Ag-0.5Cu solder was reflowed with Cu/Ni-Cu/Ti UBM one, three, and five times. Reflow and cooling conditions altered the morphology of the IMCs formed at the interface. The amount of (Cu,Ni)6Sn5 increased with increasing Cu content in the Ni-Cu film. The Cu concentration of the intermetallic compound was strongly dependent on the composition of the Ni-Cu films. The results of this study suggest that Cu-rich Ni- xCu UBM can be used to suppress interfacial spalling and improve shear strength and pull strength of solder joints.

  4. Low temperature growth of graphene on Cu-Ni alloy nanofibers for stable, flexible electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Dong; Yin, Zong-You; Du, Ze-Hui; Yang, Yang; Zhu, Min-Min; Xie, Ling-Hai; Huang, Wei

    2014-04-01

    Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 °C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 Ω sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under an AC voltage of 200 V and frequency of 1300 Hz, the ACEL device emitted blue light at 496 nm with a brightness of 103 cd m-2.Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 °C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 Ω sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under

  5. Structure and magnetic properties of Ni/Cu/Fe/MgO(001) films.

    PubMed

    Lauhoff, G; Vaz, C A F; Bland, J A C

    2009-04-15

    The structural and magnetic properties of thin Ni films grown on Cu/Fe/MgO(001) and Cu/MgO(001) buffer layers are investigated and compared to those grown on Cu/Si(001). The use of an Fe seed layer a few monolayers thick leads to the epitaxial growth of high surface quality Cu(001) buffer layers on MgO(001), while Cu growth on the bare MgO(001) substrate results in polycrystalline films. Magneto-optic Kerr effect magnetometry shows that Ni films grown on Cu/Fe/MgO(001) exhibit dominant perpendicular magnetic anisotropy up to ∼90 Å, which is similar to that of Ni films grown on Cu/Si(001). The polycrystalline Ni films also exhibit perpendicular magnetic remanence, but with a dominant in-plane magnetization component.

  6. Giant magnetic coercivity in CaCu5-type SmNi3TSi (T=Mn-Cu) solid solutions

    NASA Astrophysics Data System (ADS)

    Yao, Jinlei; Yan, Xu; Morozkin, A. V.

    2015-12-01

    The effects of transition metal substitution for Ni on the magnetic properties of the CaCu5-type SmNi3TSi (T=Mn, Fe, Co, Cu) solid solutions have been investigated. SmNi3MnSi, SmNi3FeSi, SmNi3CoSi and SmNi3CuSi show ferromagnetic ordering at 125 K, 190 K, 46 K and 12 K and field induced transitions at 65 K, 110 K, 30 K and 6 K, respectively. The magnetocaloric effects of SmNi3TSi (T=Mn, Fe, Co, Cu) were calculated in terms of isothermal magnetic entropy change (ΔSm). The magnetic entropy ΔSm reaches value of -1.1 J/kg K at 130 K for SmNi3MnSi, -0.4 J/kg K at 180 K for SmNi3FeSi, -0.37 J/kg K at 45 K for SmNi3CoSi and -0.5 J/kg K at 12 K for SmNi3CuSi in field change of 0-50 kOe around the ferromagnetic ordering temperature. They show positive ΔSm of +2.4 J/kg K at 30 K for SmNi3MnSi, -2.6 J/kg K at 65 K for SmNi3FeSi, +0.73 J/kg K at 15 K for SmNi3CoSi and -0.5 J/kg K at 6 K for SmNi3CuSi in field change of 0-50 kOe around the metamagnetic-like transition temperature. Below the field induced transition temperature, SmNi3TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi3MnSi, 87 kOe at 40 K for SmNi3FeSi, 27 kOe at 20 K for SmNi3CoSi and 54 kOe at 5 K for SmNi3CuSi. Below the field induced transition temperature, SmNi3TSi (T=Mn, Fe, Co, Cu) exhibits giant magnetic coercivity of 80 kOe at 20 K for SmNi3MnSi, 87 kOe at 40 K for SmNi3FeSi, 27 kOe at 20 K for SmNi3CoSi and 54 kOe at 5 K for SmNi3CuSi.

  7. Ni nanoparticle catalyzed growth of MWCNTs on Cu NPs @ a-C:H substrate

    NASA Astrophysics Data System (ADS)

    Ghodselahi, T.; Solaymani, S.; Akbarzadeh Pasha, M.; Vesaghi, M. A.

    2012-11-01

    NiCu NPs @ a-C:H thin films with different Cu content were prepared by co-deposition by RF-sputtering and RF-plasma enhanced chemical vapor deposition (RF-PECVD) from acetylene gas and Cu and Ni targets. The prepared samples were used as catalysts for growing multi-wall carbon nanotubes (MWCNTs) from liquid petroleum gas (LPG) at 825 °C by thermal chemical vapor deposition (TCVD). By addition of Cu NPs @ a-C:H thin layer as substrate for Ni NPs catalyst, the density of the grown CNTs is greatly enhanced in comparison to bare Si substrate. Furthermore the average diameter of the grown CNTs decreases by decreasing of Cu content of Cu NPs @ a-C:H thin layer. However Cu NPs @ a-C:H by itself has no catalytic property in MWCNTs growth. Morphology and electrical and optical properties of Cu NPs @ a-C:H thin layer is affected by Cu content and each of them is effective parameter on growth of MWCNTs based on Ni NPs catalyst. Moreover, adding of a low amount of Ni NPs doesn't vary optical, electrical and morphology properties of Cu NPs @ a-C:H thin layer but it has a profound effect on its catalytic activity. Finally the density and diameter of MWCNTs can be optimized by selection of the Cu NPs @ a-C:H thin layer as substrate of Ni NPs.

  8. Synthetically Tuned Atomic Ordering in PdCu Nanoparticles with Enhanced Catalytic Activity toward Solvent-Free Benzylamine Oxidation.

    PubMed

    Marakatti, Vijaykumar S; Sarma, Saurav Ch; Joseph, Boby; Banerjee, Dipanjan; Peter, Sebastian C

    2017-02-01

    Synthesis of ordered compounds with nano size is of particular interest for tuning the surface properties with enhanced activity and selectivity toward various important industrial catalytic processes. In this work, we synthesized ordered PdCu nanoparticles as highly efficient catalyst for the solvent-free aerobic oxidation of benzylamine. The PdxCu1-x catalysts with different chemical compositions (x = 0, 0.25, 0.4, 0.5, 0.6, 0.75, 1) were prepared by polyol method using NaBH4 as a reducing agent and were well-characterized by X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) energy-dispersive analysis of X-rays, and X-ray absorption fine structure. The effect of different metal concentrations of Pd and Cu on the formation of PdxCu1-x nanoparticles was investigated. The XRD and TEM confirmed the formation of ordered PdCu intermetallic phase with body-centered cubic (BCC) structure for the synthetic composition of Pd/Cu = 1:1. For compositions x = 0, 0.25, 0.75, and 1, PdxCu1-x alloy with face-centered cubic (FCC) structure was observed, whereas mixed phase of BCC and FCC was observed for x = 0.4 and 0.6. The use of strong reducing agent (NaBH4) was essential to synthesize PdCu ordered phase compared to weak reducing agents such as oleylamine and ascorbic acid. The PdCu nanocatalyst with ordered structure (BCC) showed excellent catalytic activity compared to PdxCu1-x alloy nanoparticles with FCC structure. The atomic ordering in the PdCu intermetallic was the driving force for the enhancement in the catalytic activity with high benzylamine conversion of 94.0% and dibenzylimine selectivity of 92.2% compared to its monometallic and alloy counterparts. Moreover, ordered PdCu alloy showed good recyclability and activity toward the oxidation of different amines.

  9. Investigations on Cu2+-substituted Ni-Zn ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Amarjeet; Kumar, Vinod

    2016-11-01

    CuxNi(1-x)/2Zn(1-x)/2Fe2O4 (x = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700∘C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz-5 MHz. Temperature dependence of the dielectric constant of Cu0.1Ni0.45Zn0.45Fe2O4 was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz-5 MHz. It was found that the electrical conductivity decreases with increasing Cu2+ ion content while it increases with the increase in temperature.

  10. Ni/Pd-Decorated Carbon NFs as an Efficient Electrocatalyst for Methanol Oxidation in Alkaline Medium

    NASA Astrophysics Data System (ADS)

    Mohamed, Ibrahim M. A.; Khalil, Khalil Abdelrazek; Mousa, Hamouda M.; Barakat, Nasser A. M.

    2017-01-01

    In this study, Ni/Pd-decorated carbon nanofibers (NFs) were fabricated as an electrocatalyst for methanol oxidation. These NFs were synthesized based on carbonization of poly(vinyl alcohol), which has high carbon content compared to many polymers used to prepare carbon NFs. Typically, calcination of an electrospun mat composed of nickel acetate, palladium acetate, and poly(vinyl alcohol) can produce Ni/Pd-doped carbon NFs. The introduced NFs were characterized by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy, line TEM energy dispersive x-ray spectrometry, field emission scanning electron microscopy, and x-ray powder diffraction. These physicochemical characterizations are acceptable tools to investigate the crystallinity and chemistry of the fabricated Ni/Pd-carbon NFs. Accordingly, the prepared NFs were tested to enhance the economic and catalytic behavior of methanol electrooxidation. Experimentally, the obtained onset potential was small compared to many reported materials; 0.32 V (versus Ag/AgCl as a reference electrode). At the same time, the current density changed from 5.08 mA/cm2 in free methanol at 0.6 V to 12.68 mA/cm2 in 0.1 mol/L methanol, which can be attributed to the MeOH oxidation. Compared to nanoparticles, the NFs have a distinct effect on the electrocatalytic performance of material due to the effect of the one-dimensional structure, which facilitates the electron transfer. Overall, the presented work opens a new way for non-precious one-dimensional nanostructured catalysts for direct methanol fuel cell technology.

  11. Effects of Pd substitution on the thermoelectric and electronic properties of delafossite Cu{sub 1−x}Pd{sub x}FeO{sub 2} (x=0.01, 0.03 and 0.05)

    SciTech Connect

    Ruttanapun, Chesta

    2014-07-01

    Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} (x=0.01, 0.03 and 005) delafossite was prepared by solid state reactions and was calcined/sintered at 1050 °C. The effect of Pd{sup 2+} substitution for the Cu{sup 1+} sites on the thermoelectric and electronic properties of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} were investigated. The crystal structure, oxygen decomposition, thermoelectric and electronic properties were characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), Seebeck coefficient, electrical conductivity and thermal conductivity measurements. The characterization showed that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} formed a hexagonal delafossite structure with R3−m symmetry. The existence of Pd{sup 2+}, Cu{sup 1+}, Cu{sup 2+}, Fe{sup 3+}, Fe{sup 4+} and O was revealed from the XPS results. Confirmation of Pd{sup 2+} substitution for the Cu{sup 1+} sites occurred by increasing the c-axis in the lattice parameter with a Pd content. The O content intercalated at the center of the triangular Cu acted as a support to produce Cu{sup 2+} ions and was reduced with an increasing Pd content. The mixed valencies of Cu{sup 1+}/Cu{sup 2+} and Cu{sup 1+}/Pd{sup 2+} in the Cu layer changed the electrical conductivity and the Fe{sup 3+}/Fe{sup 4+} mixed valencies in the FeO{sub 6} layer caused the Seebeck coefficient to increase. Both the electrical conductivity and Seebeck coefficient for Pd contents of x=0.01 and 0.03 were higher than that of non-doped CuFeO{sub 2}. The low thermal conductivity of Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} resulted from the substitution of Pd, which has a large atomic mass, into structure. The Jonker plot indicated that the electronic properties displayed a degenerate density of states and that Cu{sub (1−x)}Pd{sub (x)}FeO{sub 2} was a semiconductor. A high ZT value of 0.055 was obtained for a Pd content of 0.03 at 950 K. The Pd{sup 2+} substitution for the Cu{sup 1+} sites influenced the thermoelectric

  12. The state and catalytic properties of (Ni + Pd)/SiO{sub 2} systems obtained by grafting organometallic complexes on the surface of SiO{sub 2}

    SciTech Connect

    Koval`chuk, V.I.; Chesnokov, N.V.; Naimushina, L.V.

    1995-05-01

    The adsorption and catalytic properties of Pd/SiO{sub 2}, Ni/SiO{sub 2}, and (Pd + Ni)/SiO{sub 2} samples obtained by grafting organometallic Pd and Ni compounds on the support surface are studied. Bimetallic Pd-Ni catalysts are shown to have an additive catalytic action in the hydrogenation of benzene. Synergistic effects are detected in the reactions of ethane hydrogenolysis, CO hydrogenation, and propylene hydroformylation. The obtained data show that the surface of bimetallic cluster particles becomes enriched with palladium atoms.

  13. Development of Ag-Pd-Au-Cu alloys for multiple dental applications. Part 2. Mechanical properties of experimental Ag-Pd-Au-Cu alloys containing Sn or Ga for ceramic-metal restorations.

    PubMed

    Goto, S; Nakai, A; Miyagawa, Y; Ogura, H

    2001-06-01

    Eighteen Ag-Pd-Au-Cu alloys, consisting of nine Ag-Pd-Au-Cu mother compositions (Pd: 20, 30 or 40%, Au: 20%, Cu: 10, 15 or 20%, Ag: balance) containing either 5% Sn or 5% Ga as an additive metal, were experimentally prepared. Tensile strength, proof stress, elongation, elastic modulus, and Vickers hardness of these alloys were evaluated to clarify the potential of these alloys for use as ceramic-metal restorations as well as the effects of the Pd and Cu contents on their mechanical properties. The tensile strength, proof stress, elongation, elastic modulus and Vickers hardness of the 18 experimental alloys were in the range of 410.0-984.0 MPa, 289.7-774.3 MPa, 2.2-23.7%, 81.3-123.0 GPa and 135.7-332.3 HV1, respectively. Ten of the 18 experimental alloys can be used for ultra-low fusing ceramics based on their proof stress, elastic modulus, elongation and hardness. Between the Ga- and Sn-added alloys, differences in tensile strength, proof stress, elongation and hardness were found at several Ag-Pd-Au-Cu compositions.

  14. Selective recovery of Cu, Zn, and Ni from acid mine drainage.

    PubMed

    Park, Sang-Min; Yoo, Jong-Chan; Ji, Sang-Woo; Yang, Jung-Seok; Baek, Kitae

    2013-12-01

    In Korea, the heavy metal pollution from about 1,000 abandoned mines has been a serious environmental issue. Especially, the surface waters, groundwaters, and soils around mines have been contaminated by heavy metals originating from acid mine drainage (AMD) and mine tailings. So far, AMD was considered as a waste stream to be treated to prevent environmental pollutions; however, the stream contains mainly Fe and Al and valuable metals such as Ni, Zn, and Cu. In this study, Visual MINTEQ simulation was carried out to investigate the speciation of heavy metals as functions of pH and neutralizing agents. Based on the simulation, selective pH values were determined to form hydroxide or carbonate precipitates of Cu, Zn, and Ni. Experiments based on the simulation results show that the recovery yield of Zn and Cu were 91 and 94 %, respectively, in a binary mixture of Cu and Zn, while 95 % of Cu and 94 % of Ni were recovered in a binary mixture of Cu and Ni. However, the recovery yield and purity of Zn and Ni were very low because of similar characteristics of Zn and Ni. Therefore, the mixture of Cu and Zn or Cu and Ni could be recovered by selective precipitation via pH adjustment; however, it is impossible to recover selectively Zn and Ni in the mixture of them.

  15. Variable mineralization processes during the formation of the Permian Hulu Ni-Cu sulfide deposit, Xinjiang, Northwestern China

    NASA Astrophysics Data System (ADS)

    Zhao, Yun; Xue, Chunji; Zhao, Xiaobo; Yang, Yongqiang; Ke, Junjun; Zu, Bo

    2016-08-01

    The Permian Hulu Ni-Cu sulfide deposit is located at the southern margin of the Central Asian Orogenic Belt (CAOB) in Northern Xinjiang, Northwestern China. The host intrusion of the Hulu deposit is composed of a layered mafic-ultramafic sequence and a dike-like unit. The layered sequence is composed of harzburgite, lherzolite, pyroxenite, gabbro, gabbrodiorite and diorite. The dike-like body comprises lherzolite and gabbro. Sulfide orebodies occur mainly within the harzburgite, pyroxenite and lherzolite at the base of the layered sequence and within the lherzolite in the dike-like body. Sulfide mineralization from the Hulu deposit shows significant depletion of PGE relative to Cu and Ni. These elements show good positive correlations with S in the sulfide mineralization from the dike-like unit but relatively weak correlations in the sulfide mineralization from the layered sequence. The sulfide mineralization from the layered unit shows excellent positive correlations between Ir and Os, Ru or Rh, and poor relationships between Ir and Pt or Pd. On the contrary, sulfide mineralization from the dike-like unit shows good correlations in the diagrams of Os, Ru, Rh, Pt and Pd against Ir. Both high Cu/Pd ratios (8855-481,398) and our modeling indicate that PGE depletion resulted from sulfide removal in a deep staging magma chamber. The evolved PGE-depleted magmas then ascended to the shallower magma chamber and became sulfide saturation due to crustal contamination. Both low Se/S ratios (33.5 × 10-6-487.5 × 10-6) and a negative correlation between Se/S and Cu/Pd ratios are consistent with the addition of crustal S. A large number of sulfide liquids segregated with minor crystallization of monosulfide solid solution (MSS) in the shallower magma chamber. When new magma pulses with unfractionated sulfide droplets entered the shallower magma chamber, the sulfide slurry containing crystallized MSS may be disrupted and mixed with the unfractionated sulfide droplets. The

  16. Interdiffusion in (fcc) Ni-Cr-X (X = Al, Si, Ge or Pd) Alloys at 700?aC

    SciTech Connect

    Garimella, N; Brady, Michael P; Sohn, Yong Ho

    2007-01-01

    Interdiffusion at 700 aC for Ni-22at.%Cr (fcc ^ phase) alloys with small additions of Al, Si, Ge, or Pd was examined using solid-to-solid diffusion couples. Rods of Ni-22at.%Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni-22at.%Cr-1.6at.%Pd alloys were cast using arc-melt and homogenized at 900 aC for 168 hours. The diffusion couples were assembled with alloy disks in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed at 700 XC for 720 hours. Experimental concentration profiles were determined from polished cross-sections by using electron probe microanalysis with pure standards of Ni, Cr, Al, Si, Ge and Pd. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the interdiffusional behavior of Ni-Cr-X alloys at 700 XC are presented in the light of the diffusional interactions and the formation of protective Cr2O3 scale.

  17. Nitrate reduction over a Pd-Cu/MWCNT catalyst: application to a polluted groundwater.

    PubMed

    Soares, Olivia Salomé G P; Orfão, José J M; Gallegos-Suarez, Esteban; Castillejos, Eva; Rodríguez-Ramos, Inmaculada; Pereira, Manuel Fernando R

    2012-01-01

    The influence of the presence of inorganic and organic matter during the catalytic reduction of nitrate in a local groundwater over a Pd-Cu catalyst supported on carbon nanotubes was investigated. It was observed that the catalyst performance was affected by the groundwater composition. The nitrate conversion attained was higher in the experiment using only deionized water as solvent than in the case of simulated or real groundwater. With exception of sulphate ions, all the other solutes evaluated (chloride and phosphate ions and natural organic matter) had a negative influence on the catalytic activity and selectivity to nitrogen.

  18. Characterization of Cu buffer layers for growth of L10-FeNi thin films

    NASA Astrophysics Data System (ADS)

    Mizuguchi, M.; Sekiya, S.; Takanashi, K.

    2010-05-01

    A Cu(001) layer was fabricated on a Au(001) layer to investigate the use of Cu as a buffer layer for growing L10-FeNi thin films. The epitaxial growth of a Cu buffer layer was observed using reflection high-energy electron diffraction. The flatness of the layer improved drastically with an increase in the substrate temperature although the layer was an alloy (AuCu3). An FeNi thin film was epitaxially grown on the AuCu3 buffer layer by alternate monatomic layer deposition and the formation of an L10-FeNi ordered alloy was expected. The AuCu3 buffer layer is thus a promising candidate material for the growth of L10-FeNi thin films.

  19. PdM nanoparticles (M = Ni, Co, Fe, Mn) with high activity and stability in formic acid oxidation synthesized by sonochemical reactions

    NASA Astrophysics Data System (ADS)

    Matin, Md. Abdul; Jang, Ji-Hoon; Kwon, Young-Uk

    2014-09-01

    Bimetallic alloy PdnM (n = 1 for M = Mn, Fe, and Co; n = 1, 2, and 3 for M = Ni) nanoparticles (NPs) are synthesized on carbon supports by sonochemical reactions of Pd(acac)2 (acac = acetylacetonate) with M(acac)2 (M = Ni, Co, Mn) or Fe(acac)3 in ethylene glycol. The NPs are characterized by powder X-ray diffractometry, transmission electron microscopy (TEM), and inductively coupled plasma-atomic emission spectroscopy to determine their crystal structures, particle sizes, morphology, and elemental compositions. Alloy formation of the NPs is proven by energy dispersive X-ray spectroscopy line profiles using scanning TEM. The electronic structures and the surface compositions of NPs are analyzed using X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, respectively. PdnM NPs are applied as electrocatalysts for formic acid oxidation. The incorporation of M in Pd reduces the poisoning by surface hydroxyl groups. Activities based on the current densities are in the order of PdNi > PdFe > PdCo > PdMn. Within the PdnNi series, the activity is in the order of PdNi > Pd2Ni > Pd3Ni. The PdnM NP electrocatalysts show higher activity by a factor of 2-3.5 and improved durability than similarly prepared Pd NP electrocatalyst.

  20. Electrochemical immunoassay for carcinoembryonic antigen based on signal amplification strategy of nanotubular mesoporous PdCu alloy.

    PubMed

    Cai, Yanyan; Li, He; Li, Yuyang; Zhao, Yanfang; Ma, Hongmin; Zhu, Baocun; Xu, Caixia; Wei, Qin; Wu, Dan; Du, Bin

    2012-01-01

    Interests in using nanoporous metals for biosensing applications have been increasing. Herein, nanotubular mesoporous PdCu (NM-PdCu) alloy is used to fabricate a novel label-free electrochemical immunosensor for cancer biomarker carcinoembryonic antigen (CEA). It operates through physisorption of anti-CEA on NM-PdCu and the mixture of sulfonated graphene sheets (HSO(3)-GS) and thionine (TH) functionalized glassy carbon electrode interface as the detection platform. In this study, chitosan (CS)-PdCu is bound very strongly to carcinoembryonic antibody (anti-CEA), because of the good electron conductivity, high surface area, and good biocompatibility. CS-PdCu is immobilized on electrodes by electrostatic interactions between the negatively charged sulfo group of HSO(3)-GS and the abundant positively charged amino groups of chitosan. TH acts as the redox probe. Under the optimized conditions, the electrochemical immunosensor exhibits a wide working range from 0.01 to 12 ng/mL with a low detection limit of 4.86 pg/mL. The accuracy, reproducibility, and stability of the immunosensor are acceptable. The assay is evaluated for real serum samples, receiving satisfactory results. The nanoporous metal materials-based immunoassay provides a promising approach in clinical application and thus represents a versatile detection method.

  1. 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.

  2. Carbon encapsulated nanoparticles of Ni, Co, Cu, and Ti

    NASA Astrophysics Data System (ADS)

    Jiao, Jun; Seraphin, Supapan

    1998-03-01

    Despite intensive research on the encapsulation of metal nanoparticles into carbon clusters deposited by arc discharge, the detailed pathways of the formation of these novel forms of materials remain unclear. The growth of a rich variety of morphologies is not well understood. Studies are reported here on the growth phenomena of different metals encapsulated into carbon cages that emphasize the effect of carbon and metal supply on the size of particles. Post-deposition annealing was introduced as a process that induces structural rearrangements, and thus enables changes in morphologies. A set of carbon encapsulated Ni, Co, Cu, and Ti particles were prepared by an arc discharge process modified in the geometry of the anode and flow pattern of helium or methane gas. The samples were then annealed under flowing argon gas. Three annealing temperatures were used (600, 900, and 1100 °C). Samples were characterized by transmission and scanning electron microscopy. Particles made under the same experimental conditions are of roughly the same size. When the supply of metal in the reactor space was increased by using a larger diameter of the metal pool, the average diameter of the particles is bigger than those of produced from the smaller metal pool. The thickness of the carbon cages of Ni and Co particles increased during the annealing. The carbon cages of Cu particles, however, did not change their thickness, while some carbon coatings of Ti particles disappeared under annealing. This suggests that the addition of layers for the Ni and Co cages results from a precipitation of carbon previously dissolved in the metal, while the much lower solubility of C in Cu prevents this possibility. The Ti of high reactivity, on the other hand, may further react with the available carbon under annealing to form TiC. It is suggested that annealing provides additional thermal energy that makes structural re-arrangement possible long after the initial deposition process was terminated

  3. Segregation and H2 transport rate control in body-centered cubic PdCu membranes.

    PubMed

    Yuan, Lixiang; Goldbach, Andreas; Xu, Hengyong

    2007-09-20

    The H2 permeation of a supported 2 microm thick Pd48Cu52 membrane was investigated between 373 and 909 K at DeltaP=0.1 MPa. The initial H2 flux was 0.3 mol.m(-2).s(-1) at 723 K with an ideal H2/N2 selectivity better than 5000. The membrane underwent a bcc-fcc (body-centered cubic to face-centered cubic) phase transition between 723 and 873 K resulting in compositional segregation. After reannealing at 723 K the alloy layer reverted to a bcc structure although a small fcc fraction remained behind. The mixed-phase morphology was analyzed combining X-ray diffraction with scanning electron microscopy-energy-dispersive spectroscopic analysis (SEM-EDS) measurements, which revealed micrometer-scale Cu-enriched bcc and Cu-depleted fcc domains. The H2 flux JH2 of the fcc Pd48Cu52 single phase layer prevailing above 873 K could be described by an Arrhenius law with JH2=(7.6+/-4.9) mol.m(-2).s(-1) exp[(-32.9+/-4.5) kJ.mol(-1)/(RT)]. The characterization of the H2 flux in the mixed-phase region required two Arrhenius laws, i.e., JH2=(1.35+/-0.14) mol.m(-2).s(-1) exp[(-10.3+/-0.5) kJ.mol(-1)/(RT)] between 523 and ca. 700 K and JH2=(56.1+/-9.3) mol.m(-2).s(-1) exp[(-25.3+/-0.6) kJ.mol(-1)/(RT)] below 454 K. The H2 flux exhibited a square root pressure dependence above 523 K, but the pressure exponent gradually increased to 0.77 upon cooling to 373 K. The activation energy and pressure dependence in the intermediate temperature range are consistent with a diffusion-limited H2 transport, while the changes of these characteristics at lower temperatures indicate a desorption-limited H2 flux. The prevalence of desorption as the permeation rate-limiting step below 454 K is attributed to the pairing of an extraordinarily high hydrogen diffusivity with a marginal hydrogen solubility in bcc PdCu alloys. These result in an acceleration of the bulk diffusion rate and a deceleration of the desorption rate, respectively, allowing the bulk diffusion rate to surpass the desorption rate up to

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

    PubMed Central

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

    2015-01-01

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

  5. Quantum valley Hall states and topological transitions in Pt(Ni, Pd)-decorated silicene: A first-principles study

    SciTech Connect

    Zhao, Bao; Zhang, Jiayong; Wang, Yicheng; Yang, Zhongqin

    2014-12-28

    The electronic states and topological behaviors of Pt(Ni, Pd)-decorated silicene are investigated by using an ab-initio method. All the three kinds of the adatoms prefer hollow sites of the silicene, guaranteeing the Dirac cones unbroken. The Pt(Ni, Pd)-decorated silicene systems all present quantum valley Hall (QVH) states with the gap opened exactly at the Fermi level. The gaps of the QVH states can be increased substantially by applying a positive electric field. Very fascinating phase transitions from QVH to quantum spin Hall (QSH) and then to QVH again are achieved in the Pt/Ni-decorated silicene when a negative electric field is applied. The QSH state in the Pd case with a negative electric field is, however, quenched because of relatively larger Rashba spin-orbit coupling (SOC) than the intrinsic SOC in the system. Our findings may be useful for the applications of silicene-based devices in valleytronics and spintronics.

  6. Hidden amorphous phase and reentrant supercooled liquid in Pd-Ni-P metallic glasses.

    PubMed

    Lan, S; Ren, Y; Wei, X Y; Wang, B; Gilbert, E P; Shibayama, T; Watanabe, S; Ohnuma, M; Wang, X-L

    2017-03-17

    An anomaly in differential scanning calorimetry has been reported in a number of metallic glass materials in which a broad exothermal peak was observed between the glass and crystallization temperatures. The mystery surrounding this calorimetric anomaly is epitomized by four decades long studies of Pd-Ni-P metallic glasses, arguably the best glass-forming alloys. Here we show, using a suite of in situ experimental techniques, that Pd-Ni-P alloys have a hidden amorphous phase in the supercooled liquid region. The anomalous exothermal peak is the consequence of a polyamorphous phase transition between two supercooled liquids, involving a change in the packing of atomic clusters over medium-range length scales as large as 18 Å. With further temperature increase, the alloy reenters the supercooled liquid phase, which forms the room-temperature glass phase on quenching. The outcome of this study raises a possibility to manipulate the structure and hence the stability of metallic glasses through heat treatment.

  7. Hidden amorphous phase and reentrant supercooled liquid in Pd-Ni-P metallic glasses

    PubMed Central

    Lan, S.; Ren, Y.; Wei, X. Y.; Wang, B.; Gilbert, E. P.; Shibayama, T.; Watanabe, S.; Ohnuma, M.; Wang, X. -L.

    2017-01-01

    An anomaly in differential scanning calorimetry has been reported in a number of metallic glass materials in which a broad exothermal peak was observed between the glass and crystallization temperatures. The mystery surrounding this calorimetric anomaly is epitomized by four decades long studies of Pd-Ni-P metallic glasses, arguably the best glass-forming alloys. Here we show, using a suite of in situ experimental techniques, that Pd-Ni-P alloys have a hidden amorphous phase in the supercooled liquid region. The anomalous exothermal peak is the consequence of a polyamorphous phase transition between two supercooled liquids, involving a change in the packing of atomic clusters over medium-range length scales as large as 18 Å. With further temperature increase, the alloy reenters the supercooled liquid phase, which forms the room-temperature glass phase on quenching. The outcome of this study raises a possibility to manipulate the structure and hence the stability of metallic glasses through heat treatment. PMID:28303882

  8. Comparative study on catalytic hydrodehalogenation of halogenated aromatic compounds over Pd/C and Raney Ni catalysts

    NASA Astrophysics Data System (ADS)

    Ma, Xuanxuan; Liu, Sujing; Liu, Ying; Gu, Guodong; Xia, Chuanhai

    2016-04-01

    Catalytic hydrodehalogenation (HDH) has proved to be an efficient approach to dispose halogenated aromatic compounds (HACs). Liquid-phase HDH of single and mixed halobenzenes/4-halophenols with H2 over 5% Pd/C and Raney Ni catalyst are investigated and compared. For liquid-phase HDH of single HACs, hydrogenolytic scission reactivity of C-X bonds decreases in order of C-Br > C-Cl > C-I > C-F over Pd/C catalyst, and in order of C-I > C-Br > C-Cl > C-F over Raney Ni catalyst. To clarify the reason why hydrogenolytic scission reactivity of C-X bonds over Pd/C and Raney Ni catalysts exhibits different trends, liquid-phase HDH of mixed HACs over Pd/C and Raney Ni catalysts were studied, and catalysts are characterized by SEM, EDX, and XRD techniques. It was found that the high adsorption of iodoarenes on Pd/C catalyst caused the HDH reactivity of iodoarenes to be lower than that of chloroarenes and bromoarenes in the HDH of single HACs. Moreover, the adsorption of in situ produced iodine ion (I‑) to catalyst surface would result in the decline of catalytic activity, which might be the main reason why the HDH reactivity of HACs in the presence of NaI is rather low.

  9. Comparative study on catalytic hydrodehalogenation of halogenated aromatic compounds over Pd/C and Raney Ni catalysts

    PubMed Central

    Ma, Xuanxuan; Liu, Sujing; Liu, Ying; Gu, Guodong; Xia, Chuanhai

    2016-01-01

    Catalytic hydrodehalogenation (HDH) has proved to be an efficient approach to dispose halogenated aromatic compounds (HACs). Liquid-phase HDH of single and mixed halobenzenes/4-halophenols with H2 over 5% Pd/C and Raney Ni catalyst are investigated and compared. For liquid-phase HDH of single HACs, hydrogenolytic scission reactivity of C-X bonds decreases in order of C-Br > C-Cl > C-I > C-F over Pd/C catalyst, and in order of C-I > C-Br > C-Cl > C-F over Raney Ni catalyst. To clarify the reason why hydrogenolytic scission reactivity of C-X bonds over Pd/C and Raney Ni catalysts exhibits different trends, liquid-phase HDH of mixed HACs over Pd/C and Raney Ni catalysts were studied, and catalysts are characterized by SEM, EDX, and XRD techniques. It was found that the high adsorption of iodoarenes on Pd/C catalyst caused the HDH reactivity of iodoarenes to be lower than that of chloroarenes and bromoarenes in the HDH of single HACs. Moreover, the adsorption of in situ produced iodine ion (I−) to catalyst surface would result in the decline of catalytic activity, which might be the main reason why the HDH reactivity of HACs in the presence of NaI is rather low. PMID:27113406

  10. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    SciTech Connect

    Weinelt, M.; Nilsson, A.; Wassdahl, N.

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  11. Oxidation resistance of graphene-coated Cu and Cu/Ni alloy.

    PubMed

    Chen, Shanshan; Brown, Lola; Levendorf, Mark; Cai, Weiwei; Ju, Sang-Yong; Edgeworth, Jonathan; Li, Xuesong; Magnuson, Carl W; Velamakanni, Aruna; Piner, Richard D; Kang, Junyong; Park, Jiwoong; Ruoff, Rodney S

    2011-02-22

    The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. In particular, graphene prevents the formation of any oxide on the protected metal surfaces, thus allowing pure metal surfaces only one atom away from reactive environments. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 °C in air for up to 4 h. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth.

  12. Transparent ITO/Ag-Pd-Cu/ITO multilayer cathode use in inverted organic solar cells

    SciTech Connect

    Kim, Hyo-Joong; Kim, Han-Ki; Lee, Hyun Hwi; Kal, Jinha; Hahn, Jungseok

    2015-10-15

    The characteristics of transparent ITO/Ag-Pd-Cu (APC)/ITO multilayer cathodes were investigated for use in inverted organic solar cells (IOSCs). The insertion of an APC interlayer into the ITO film effectively led to crystallization of the top ITO layer, unlike that in the Ag interlayer, and resulted in a low sheet resistance of 6.55 Ohm/square and a high optical transmittance of 84.14% without post annealing. In addition, the alloying of the Pd and Cu elements into Ag prevented agglomeration and oxidization of the metal interlayer and led to more stable ITO/APC/ITO films under ambient conditions. The microstructure and interfacial structure of the transparent ITO/APC/ITO cathode in the IOSCs were examined in detail by synchrotron X-ray scattering and high resolution transmission electron microscopy. Furthermore, we suggested a possible mechanism to explain the lower PCE of the IOSCs with an ITO/APC/ITO cathode than that of a reference IOSC with a crystalline ITO cathode using the external quantum efficiency of the IOSCs.

  13. Thermal Analysis of the Effect of Oxygen Contamination on Undercooling of Zr-Al-Ni-Cu, Cu-Zr-Ti, and Cu-Ni-Zr-Ti Metallic Glasses (Preprint)

    DTIC Science & Technology

    2009-04-01

    been done on systems other than Zr65Al7.5(Cu17.5Ni10). Zr55Al10(Cu30Ni5) was found to be less sensitive to oxygen content than Zr65Al7.5(Cu17.5Ni10...Zr11Ti34 by arc-melting each of the pure elements under a titanium - gettered atmosphere. Starting materials used were: Al pellets, 99.999%; Cu shot...produce 2-6 g alloyed ingots of each composition. Each ingot was flipped typically 4-5 times in a titanium -gettered, high-purity argon atmosphere

  14. Thermally enhanced perpendicular magnetic anisotropy behaviors of ultrathin [Co/Pd]{sub n} multilayers via NiO{sub x} capping layer

    SciTech Connect

    Chung, Woo Seong; Lee, Ja Bin; An, Gwang Guk; Yang, Seung Mo; Kim, Jae Hong; Hong, Jin Pyo

    2015-06-01

    We report the enhanced perpendicular magnetic anisotropy (PMA) features of ultrathin [Co/Pd]{sub 3} multilayers (MLs) employing a NiO{sub x} insertion layer at high annealing temperatures. Thermally enhanced PMA in [Co/Pd]{sub 3}/NiO{sub x} (capping layer) MLs were achieved at a specific capping layer thickness, while no PMA responses were observed for a NiO{sub x} (buffer layer)/[Co/Pd]{sub 3} ML, regardless of NiO{sub x} thickness. X-ray diffraction observations, including rocking curves, identified the relatively different crystalline characteristics of the NiO{sub x} capping and buffer layers. Origin of the enhanced PMAs of [Co/Pd]{sub 3} MLs containing a NiO{sub x} capping layer is described based on the NiO{sub x} capping effect possibly providing additional Co/Oxide i-PMA under high-temperature annealing.

  15. Speculation of equilibrium pressure of Ti36Zr40Ni20Pd4 icosahedral quasicrystal

    NASA Astrophysics Data System (ADS)

    Huang, Huogen; Chen, Liang

    2015-08-01

    Ti-Zr-Ni quasicrystals have been demonstrated to store a large number of hydrogen atoms, which implies strong potential application in hydrogen energy field for them. However, the desorption of hydrogen atoms in the quasicrystals is quite difficult, with the indication of high desorption temperature and slow desorption rate. The shortage limits their use in the field to a large extent. But this kind of quasicrystals might be used in nuclear fusion energy field, because tritium as a coral fuel for nuclear fusion needs tight storage. However, equilibrium pressure at room temperature of Ti-Zr-Ni quasicrystals, important for their application in fusion energy field, has not been clear yet. In this work, we designed a gas-solid reaction system with the pressure resolution of 10-8Pa and carried out hydrogen desorption investigation at different temperatures on Ti36Zr40Ni20Pd4 icosahedral quasicrystal. Based on three Pressure-Composition-Temperature desorption curves, we speculate according to Van't Hoff theory about hydrogen storage that its equilibrium pressure at room temperature could be at the magnitude of 10-6Pa, displaying good stability of hydrogen in the quasicrystal and also implying application prospects in fusion energy field for quasicrystals of this type.

  16. Structural and magnetic phase transitions in CeCu6-xTx (T = Ag,Pd)

    DOE PAGES

    Poudel, Lekhanath N.; De la cruz, Clarina; Payzant, E. Andrew; ...

    2015-12-15

    The structural and the magnetic properties of CeCu6-xAgx (0 ≤ x ≤ 0.85) and CeCu6-xPdx (0 ≤ x ≤ 0.4) have been studied using neutron diffraction, resonant ultrasound spectroscopy (RUS), x-ray diffraction measurements, and first principles calculations. The structural and magnetic phase diagrams of CeCu6-xAgx and CeCu6-xPdx as a function of Ag/Pd composition are reported. The end member, CeCu6, undergoes a structural phase transition from an orthorhombic (Pnma) to a monoclinic (P21/c) phase at 240 K. In CeCu6-xAgx, the structural phase transition temperature (Ts) decreases linearly with Ag concentration and extrapolates to zero at xS ≈ 0.1. The structural transitionmore » in CeCu6-xPdx remains unperturbed with Pd substitution within the range of our study. The lattice constant b slightly decreases with Ag/Pd doping, whereas a and c increase with an overall increase in the unit cell volume. Both systems, CeCu6-xAgx and CeCu6-xPdx, exhibit a magnetic quantum critical point (QCP), at x ≈ 0.2 and x ≈ 0.05, respectively. Near the QCP, long range antiferromagnetic ordering takes place at an incommensurate wave vector (δ1 0 δ2), where δ1 ~ 0.62, δ2 ~ 0.25, x = 0.125 for CeCu6-xPdx and δ1 ~ 0.64, δ2 ~ 0.3, x = 0.3 for CeCu6-xAgx. As a result, the magnetic structure consists of an amplitude modulation of the Ce moments which are aligned along the c axis of the orthorhombic unit cell.« less

  17. Influence of Cu Nanoparticles on Microstructure and Mechanical Properties of Sn0.7Ag0.5Cu-BiNi/Cu Solder Joint

    NASA Astrophysics Data System (ADS)

    Ban, G. F.; Sun, F. L.; Fan, J. J.; Liu, Y.; Cong, S. N.

    2017-02-01

    The influence of Cu nanoparticles addition on microstructure and mechanical properties of Sn0.7Ag0.5Cu-BiNi/Cu solder joint after reflow and isothermal aging has been investigated in this study. Experimental results indicate that the addition of Cu nanoparticles suppresses the growth of intermetallic compound (IMC) layer at the interface after reflow and aging. Moreover, the bulk solder appears with refined microstructure after adding Cu nanoparticles. In addition, solder joints containing Cu nanoparticles display higher microhardness due to the dispersive distribution of Cu nanoparticles as well as the refined IMC particles. The addition of 0.1% Cu nanoparticles can improve the microhardness by 16% compared with the noncomposite. However, the existing porosity in the solder exerts a negative effect on microhardness and shear strength. The mechanism of porosity formation has been discussed in detail. Porosity increases markedly with increasing Cu nanoparticles proportion.

  18. On the evolution of Cu-Ni-rich bridges of Alnico alloys with tempering

    NASA Astrophysics Data System (ADS)

    Fan, M.; Liu, Y.; Jha, Rajesh; Dulikravich, George S.; Schwartz, J.; Koch, C. C.

    2016-12-01

    Tempering is a critical step in Alnico alloy processing, yet the effects of tempering on microstructure have not been well studied. Here we report these effects, and in particular the effects on the Cu-Ni bridges. Energy-dispersive X-ray spectroscopy (EDS) maps and line scans show that tempering changes the elemental distribution in the Cu-Ni bridges, but not the morphology and distribution of Cu-bridges. The Cu concentration in the Cu-Ni bridges increases after tempering while other element concentrations decrease, especially Ni and Al. Furthermore, tempering sharpens the Cu bridge boundaries. These effects are primarily related to the large 2C44/(C11-C12) ratio for Cu, largest of all elements in Alnico. In addition, the Ni-Cu loops around the α1 phases become inconspicuous with tempering. The diffusion of Fe and Co to the α1 phase during tempering, which increases the difference of saturation magnetization between the α1 and α2 phases, is observed by EDS. In summary, α1, α2 and Cu-bridges are concentrated with their major elements during tempering which improves the magnetic properties. The formation of these features formed through elemental diffusion is discussed via energy theories.

  19. Hydrothermal remobilisation around a deformed and remobilised komatiite-hosted Ni-Cu-(PGE) deposit, Sarah's Find, Agnew Wiluna greenstone belt, Yilgarn Craton, Western Australia

    NASA Astrophysics Data System (ADS)

    Le Vaillant, Margaux; Saleem, Ahmad; Barnes, Stephen J.; Fiorentini, Marco L.; Miller, John; Beresford, Steve; Perring, Caroline

    2016-03-01

    The Sarah's Find nickel deposit, located 4.5 km north of the Mount Keith nickel mine, Western Australia, was chosen as a case study to investigate the nature and three-dimensional geometry of a geochemical halo created by the hydrothermal remobilisation of base metals and platinum group elements into the country rock surrounding a small massive Ni sulphide orebody. Portable and laboratory-based XRF analyses were carried out on samples from a shear zone localised along the basal komatiite-dacite contact that hosts the orebody. A geochemical halo was identified that extends along the shear zone up to 1780 m away from the massive sulphides, parallel to a prominent stretching lineation. Elevated Ni and Pd are associated with high As, Co, Cu and S. Palladium and Pt concentrations increase with proximity to massive sulphides (from 6 to 1190 ppb Pd). These anomalous concentrations reflect the presence of sulfarsenides and sulphides, either physically remobilised and forming veinlets close to the massive sulphides, or hydrothermally transported and redeposited within the foliation. In situ laser ablation ICP-MS indicates that Pd and Pt are hosted within these nickel sulfarsenides. This Ni-Co-As-Pd geochemical halo, observed around the Sarah's Find ore body, is interpreted as forming syn deformation, by the circulation of As-rich hydrothermal fluids dissolving base metals, Pd and Pt from the orebody and redepositing them along the sheared footwall contact. Similar Ni-Co-Pd-Pt-As geochemical haloes could potentially exist around any magmatic nickel sulphide mineral system that has undergone a phase of arsenic metasomatism and may be a generally applicable proximity indicator for nickel sulphides in hydrothermally altered terranes.

  20. Structural evolution in Ti-Cu-Ni metallic glasses during heating

    SciTech Connect

    Gargarella, P.; Pauly, S.; Stoica, M.; Kühn, U.; Vaughan, G.; Afonso, C. R. M.; Eckert, J.

    2015-01-01

    The structural evolution of Ti{sub 50}Cu{sub 43}Ni{sub 7} and Ti{sub 55}Cu{sub 35}Ni{sub 10} metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

  1. A 3D porous Ni-Cu alloy film for high-performance hydrazine electrooxidation

    NASA Astrophysics Data System (ADS)

    Sun, Ming; Lu, Zhiyi; Luo, Liang; Chang, Zheng; Sun, Xiaoming

    2016-01-01

    Structural design and catalyst screening are two most important factors for achieving exceptional electrocatalytic performance. Herein we demonstrate that constructing a three-dimensional (3D) porous Ni-Cu alloy film is greatly beneficial for improving the hydrazine oxidation reaction (HzOR) performance. A facile electrodeposition process is employed to synthesize a Ni-Cu alloy film with a 3D hierarchical porous structure. As an integrated electrode for HzOR, the Ni-Cu alloy film exhibits superior catalytic activity and stability to the Ni or Cu counterparts. The synthesis parameters are also systematically tuned for optimizing the HzOR performance. The excellent HzOR performance of the Ni-Cu alloy film is attributed to its high intrinsic activity, large electrochemical specific surface area, and 3D porous architecture which offers a ``superaerophobic'' surface to effectively remove the gas product in a small volume. It is believed that the Ni-Cu alloy film electrode has potential application in direct hydrazine fuel cells as well as other catalytic fields.Structural design and catalyst screening are two most important factors for achieving exceptional electrocatalytic performance. Herein we demonstrate that constructing a three-dimensional (3D) porous Ni-Cu alloy film is greatly beneficial for improving the hydrazine oxidation reaction (HzOR) performance. A facile electrodeposition process is employed to synthesize a Ni-Cu alloy film with a 3D hierarchical porous structure. As an integrated electrode for HzOR, the Ni-Cu alloy film exhibits superior catalytic activity and stability to the Ni or Cu counterparts. The synthesis parameters are also systematically tuned for optimizing the HzOR performance. The excellent HzOR performance of the Ni-Cu alloy film is attributed to its high intrinsic activity, large electrochemical specific surface area, and 3D porous architecture which offers a ``superaerophobic'' surface to effectively remove the gas product in a small

  2. Interdiffusion in ? (fcc) Ni-Cr-X (X=Al, Si, Ge or Pd) Alloys at 900?C

    SciTech Connect

    Garimella, N; Brady, Michael P; Sohn, Yong Ho

    2006-01-01

    Interdiffusion in Ni-Cr (fcc phase) alloys with small additions of Al, Si, Ge, or Pd was investigated using solid-to-solid diffusion couples. Ni-Cr-X alloys having compositions of Ni- 22at.%Cr, Ni-21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni- 22at.%Cr-1.6at.%Pd were manufactured by arc-casting. The diffusion couples were assembled in an Invar steel jig, encapsulated in Ar after several hydrogen purges, and annealed at 900 C in a three-zone tube furnace for 168 hours. Experimental concentration profiles were determined from polished cross-section of these couples by using electron probe microanalysis with pure element standards. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the diffusional behavior of Ni-Cr-X alloys are presented in the light of the diffusional interactions and the formation of a protective Cr2O3 scale

  3. Effect of Cu addition on the martensitic transformation of powder metallurgy processed Ti–Ni alloys

    SciTech Connect

    Kim, Yeon-wook; Choi, Eunsoo

    2014-10-15

    Highlights: • M{sub s} of Ti{sub 50}Ni{sub 50} powders is 22 °C, while M{sub s} of SPS-sintered porous bulk increases up to 50 °C. • M{sub s} of Ti{sub 50}Ni{sub 40}Cu{sub 20} porous bulk is only 2 °C higher than that of the powders. • Recovered stain of porous TiNi and TiNiCu alloy is more than 1.5%. - Abstract: Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 30}Cu{sub 20} powders were prepared by gas atomization and their transformation behaviors were examined by means of differential scanning calorimetry and X-ray diffraction. One-step B2–B19’ transformation occurred in Ti{sub 50}Ni{sub 50} powders, while Ti{sub 50}Ni{sub 30}Cu{sub 20} powders showed B2–B19 transformation behavior. Porous bulks with 24% porosity were fabricated by spark plasma sintering. The martensitic transformation start temperature (50 °C) of Ti{sub 50}Ni{sub 50} porous bulk is much higher than that (22 °C) of the as-solidified powders. However, the martensitic transformation start temperature (35 °C) of Ti{sub 50}Ni{sub 30}Cu{sub 20} porous bulk is almost the same as that (33 °C) of the powders. When the specimens were compressed to the strain of 8% and then unloaded, the residual strains of Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 30}Cu{sub 20} alloy bulks were 3.95 and 3.7%, respectively. However, these residual strains were recovered up to 1.7% after heating by the shape memory phenomenon.

  4. Investigation of Pd-Modified Ag-CuO Air Braze Filler Metals

    SciTech Connect

    Weil, K. Scott; Kim, Jin Yong; Hardy, John S.; Darsell, Jens T.

    2006-01-01

    This paper reports on the effects of palladium on the liquidus/solidus temperatures and wetting behavior of a series of Ag-CuOx air braze filler metals. Currently, the maximum operating temperature of the Ag-CuOx system is limited by its eutectic temperature of ~935°C. One strategy to increase the maximum operational temperature of this family of filler metals is to add a higher melting noble alloying element. In the current study, we examined the effects of palladium additions on the melting characteristics of the Ag-CuO materials and the wetting properties of the resulting air braze filler metals with respect to alumina. It was found that while the addition of Pd causes the anticipated increase in the melting temperature, it does so at a sacrifice in wetting properties. The extent of both effects and therefore the opportunity to trade-off the two properties in order to develop an optimized higher temperature air braze depends on concentrations of both the palladium and copper oxide.

  5. Vibrational states on vicinal surfaces of Al, Ag, Cu and Pd

    NASA Astrophysics Data System (ADS)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1998-10-01

    We present the calculation of vibrational modes and lattice relaxation for the (110), (211), (311), (511), (331) and (221) surfaces of Al, Ag, Cu and Pd. The surface phonon frequencies and polarizations are obtained for relaxed and unrelaxed surfaces using embedded atom model potentials. On all surfaces studied step-localized vibrational modes and surface states localized on terrace atoms are found. It is shown that as the terrace width increases so does the number of surface phonons. It is found that interlayer relaxation leads to a shift in the frequencies of the surface states and to a change in the number and localization. In particular, it may cause the appearance or disappearance of step modes. It is shown that the character of relaxation on vicinal surfaces is determined by the number of atoms on a terrace. A comparison of the results with the available experimental data for the Al(221), Cu(211), and Cu(511) surfaces indicates that there is a good agreement with the experimental data.

  6. Interfacial Microstructure Evolution and Shear Behavior of Au-Sn/Ni- xCu Joints at 350°C

    NASA Astrophysics Data System (ADS)

    Peng, J.; Wang, R. C.; Wang, M.; Liu, H. S.

    2017-04-01

    Interfacial reaction and shear behavior of the joints between Au-29Sn (at.%) solder and Ni- xCu ( x = 20 at.%, 40 at.%, 60 at.%, and 80 at.%) substrate alloys soldered at 350°C for various durations were investigated in this study. The results show that α(Au) is the common reaction product at the solder/substrate interfaces after a short-time reaction regardless of Cu content. As soldering goes on, another new Ni3Sn2 layer forms at the interface company with ordering of the α(Au) phase, AuCu I/Ni3Sn2 bi-layers formed at the Au-Sn/Ni-20Cu interface, or with AuCu III/Ni3Sn2 bi-layers at the Au-Sn/Ni-40Cu interface. If the content of Cu in the substrate is higher than 40 at.%, periodic layered structure and discontinuous Ni3Sn2 layers appear. In the couple of Au-Sn/Ni-60Cu, AuCu I + AuCu III/Ni3Sn2/α(Au) can be observed while AuCu3/Ni3Sn2/α(Au) forms in the couple of Au-Sn/Ni-80Cu. Shear fracture always occurs in the region near the Ni-20Cu substrate in Au-Sn/Ni-20Cu joints, whereas it appears in the reaction layer for the joint of higher Cu content. The shear strength of Au-Sn/Ni-60Cu and Au-Sn/Ni-80Cu joints achieves about 55 MPa as α(Au) phase forms but decreases remarkably due to pore formation after soldering for a long duration. Whereas, the shear strength of Au-Sn/Ni-40Cu joints can reach 62 MPa as the α(Au) phase forms at an early stage, and maintains above 52 MPa even soldered for a long duration because of the adequate thick α(Au) and AuCu III layer adjacent to substrate provides good bonding. The reason why the soldering joint of Au-Sn/Ni-40Cu possesses higher strength and a better stability exists is that high Ni concentration in α(Au) and the continuous Ni3Sn2 layer inhibit formation of Kirkendall pores.

  7. CuNi Nanoparticles Assembled on Graphene for Catalytic Methanolysis of Ammonia Borane and Hydrogenation of Nitro/Nitrile Compounds

    DOE PAGES

    Yu, Chao; Fu, Jiaju; Muzzio, Michelle; ...

    2017-01-12

    Here we report a solution phase synthesis of 16 nm CuNi nanoparticles (NPs) with the Cu/Ni composition control. These NPs are assembled on graphene (G) and show Cu/Ni composition-dependent catalysis for methanolysis of ammonia borane (AB) and hydrogenation of aromatic nitro (nitrile) compounds to primary amines in methanol at room temperature. Among five different CuNi NPs studied, the G-Cu36Ni64 NPs are the best catalyst for both AB methanolysis (TOF = 49.1 molH2 molCuNi-1 min-1 and Ea = 24.4 kJ/mol) and hydrogenation reactions (conversion yield >97%). In conclusion, the G-CuNi represents a unique noble-metal-free catalyst for hydrogenation reactions in a greenmore » environment without using pure hydrogen.« less

  8. New constraints on the origin of the Skaergaard intrusion Cu-Pd-Au mineralization: Insights from high-resolution X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Godel, Bélinda; Rudashevsky, Nikolay S.; Nielsen, Troels F. D.; Barnes, Stephen J.; Rudashevsky, Vladimir N.

    2014-03-01

    This contribution presents the first detailed three-dimensional (3D) in situ analysis of samples from the Platinova Reef using high-resolution X-ray computed tomography (HRXCT) and 3D image processing and quantification coupled with microscopic and mineralogical investigations. Our HRXCT analyses reveal the complex textural relationships between Cu-rich sulfides (bulk composition close to bornite), skaergaardite (PdCu), Au-rich phases, silicates and Fe-Ti oxides and provide unequivocal textural evidences, not observed previously. The association in 3D between Cu-rich sulfide globules, PdCu alloy and ilmenite is inconsistent with a hydrothermal origin of the Cu-Pd mineralization. In contrast, our results combined with phase diagrams strongly support a primary magmatic origin for the Cu-Pd mineralization where Cu and Pd-rich, Fe-poor sulfide liquid represents a cumulus phase that forms by in-situ nucleation. These sulfide droplets and attached skaergaardite grains were trapped during the formation and crystallization of the Fe-Ti oxides. Subsequent, post-cumulus processes led to the partial to total dissolution of the sulfide not entirely enclosed by the Fe-Ti oxides (i.e., not protected from reaction) leading to the observed variability in Cu and Pd composition at the aggregate (sulfide + PdCu) scale and to the occurrence of free PdCu alloys. In contrast to the PdCu alloy, gold-bearing minerals are never observed entirely enclosed within the Fe-Ti oxide. Two hypotheses can be envisaged for the formation of the gold enriched layer in the upper part of the section. Gold may have either precipitated from high-temperature late magmatic Cl-rich fluids. Alternatively, gold may have been enriched during fractional crystallization after sulfide had been suppressed from the liquidus after the Pd layer crystallized and then deposited along redox barriers.

  9. Electrical transport properties of amorphous Ni32Pd53P15 alloy

    NASA Astrophysics Data System (ADS)

    Prakruti, Chaudhari; Joshi, R. H.; Bhatt, N. K.; Thakore, B. Y.

    2015-08-01

    A ternary alloy containing nickel, palladium and phosphorous in amorphous form has been studied. The electrical transport properties viz. electrical resistivity, thermoelectrical power (TEP), thermal conductivity are computed using our recently proposed potential. In the present work, five screening functions have been employed to incorporate the exchange and correlation effects. The theoretical structure factors due to hard core fluid theory have been used in the calculations. The liquid alloy is studied as a function of its composition at temperature 294 K. The partial structure factors of the compound-forming Ni32Pd53P15 ternary alloy has been calculated by considering Hoshino's m-component hard-sphere mixture, which is based on Percus-Yevic equation of Hiroike.

  10. The coupled effect of grain size and solute on work hardening of Cu-Ni alloys

    NASA Astrophysics Data System (ADS)

    Shadkam, A.; Sinclair, C. W.

    2015-12-01

    A modified grain size-dependent model developed to capture the combined effects of solute and grain size on the work hardening behaviour of fine-grained Cu-Ni alloys is provided. This work builds on a recent model that attributes the grain size-dependent work hardening of fine-grained Cu to backstresses. In the case of Cu-Ni alloys, unlike commercially pure Cu, a grain size-dependent separation between the Kocks-Mecking curves develops, this being explained here based on an extra contribution from geometrically necessary dislocations in the solid solution alloy. This is corroborated by strain-rate sensitivity experiments.

  11. Effect of Thickness and Phosphorus Content on Au/Pd/Ni(P) Metal Finish of Printed Circuit Board

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Kai; Lin, Keh-Wen; Huang, Yu-Ming; Caparanga, Alvin R.; Leron, Rhoda B.; Li, Meng-Hui

    2013-08-01

    Electroless nickel/electroless palladium/immersion gold [Au/Pd/Ni(P) or ENEPIG] pads consisting of layers of Ni(P) (200 μin), pure palladium (Pd) or palladium phosphorus (PdP) (2 μin, 4 μin or 6 μin), and gold (Au) (2 μin or 4 μin) were prepared using two different processes (wire bonding and lead-free soldering). Each of these processes was done with zero- or two-time reflow. Different tests on solderability, wettability, wire-bonding capacity, and corrosion resistance were performed on different combinations of ENEPIG pads formed using different combinations of processes and conditions. Scanning electron microscopy was also performed to examine the surface characteristics of the pads. It was found that the ENEPIG pad sample with the 4- μin-thick Au and 4- μin-thick PdP layers possessed stable wire-bonding capacity and excellent lead-free solder reliability. In addition, the ENEPIG-PdP systems showed better corrosion resistance, which is attributed to the presence of the amorphous PdP layer protecting the nickel layer.

  12. Preparation of Cu-Ni/YSZ solid oxide fuel cell anodes using microwave irradiation

    NASA Astrophysics Data System (ADS)

    Islam, Shamiul; Hill, Josephine M.

    A microwave irradiation process is used to deposit Cu nanoparticles on the Ni/YSZ anode of an electrolyte-supported solid oxide fuel cell (SOFC). The reaction time in the microwave is only 15 s for the deposition of 6 wt% Cu (with respect to Ni) from a solution of Cu(NO 3) 2·3H 2O and ethylene glycol (HOCH 2CH 2OH). The morphology of the deposited Cu particles is spherical and the average size of the particles is less than 100 nm. The electrochemical performance of the microwave Cu-coated Ni/YSZ anodes is tested in dry H 2 and dry CH 4 at 1073 K, and the anodes are characterized with scanning electron microscopy, electrochemical impedance spectroscopy, and temperature-programmed oxidation. The results indicate that preparation of the anodes by the microwave technique produces similar performance trend as those reported for Cu-Ni/YSZ/CeO 2 anodes prepared by impregnation. Specifically, less carbon is formed on the Cu-Ni/YSZ than on conventional Ni/YSZ anodes when exposed to dry methane and the carbon that does form is more reactive.

  13. Spin densities for Ni, Pt_3Cr, and Pd_3Cr

    NASA Astrophysics Data System (ADS)

    Chau, Hung T.; Lu, Z. W.; Klein, Barry M.

    1997-03-01

    Recent ab-initio calculations^1 demonstrated that the L12 ordering in Pt_3Cr is a direct consequence of spin-polarization, i.e., magnetic moment formation in the L12 structure stabilizes it over its rival DO_22 structure (which is more stable in a non magnetic calculation). Here we present calculations of the magnetic structures of Pt_3Cr and Pd_3Cr in the L12 structure. We use fcc Ni calculations as a benchmark system since its magnetic structure has been well studied experimentally and theoretically. Our LSDA-calculated Ni magnetic structure factors are in good accord with experiment as well as with previous theoretical results. Our calculated magnetic structure factors for Pt_3Cr are in fair agreement with experiment.^2 The calculated local magnetic moment at the Pt site ( ~ 0) differs somewhat from the early experimental estimate of -0.27 μB ^2 but is, however, closer to the recent circular X-ray dichroism experimental value^3 of -0.1 μ_B. We also find that the contribution of the orbital polarization to the Pt-site local moment is negligible. We will also show magnetic structure factors of Pd_3Cr in the L12 structure, for which no experimental data are yet available for comparison. Work supported by a grant from Sandia National Laboratories ^1Z. W. Lu, B. M. Klein, A. Zunger, Phys. Rev. Lett. 75, 1320 (1995). ^2S. K. Burke, et al., J. of Magn. Magn. Mat. 15, 505 (1980). ^3H. Maruyama, et al, J. of Magn. Magn. Mat. 140, 43 (1995).

  14. Electroless deposition of NiCrB diffusion barrier layer film for ULSI-Cu metallization

    NASA Astrophysics Data System (ADS)

    Wang, Yuechun; Chen, Xiuhua; Ma, Wenhui; Shang, Yudong; Lei, Zhengtao; Xiang, Fuwei

    2017-02-01

    NiCrB films were deposited on Si substrates using electroless deposition as a diffusion barrier layer for Cu interconnections. Samples of the prepared NiCrB/SiO2/Si and NiCrB/Cu/NiCrB/SiO2/Si were annealed at temperatures ranging from 500 °C to 900 °C. The reaction mechanism of the electroless deposition of the NiCrB film, the failure temperature and the failure mechanism of the NiCrB diffusion barrier layer were investigated. The prepared samples were subjected to XRD, XPS, FPP and AFM to determine the phases, composition, sheet resistance and surface morphology of samples before and after annealing. The results of these analyses indicated that the failure temperature of the NiCrB barrier film was 900 °C and the failure mechanism led to crystallization and grain growth of the NiCrB barrier layer after high temperature annealing. It was found that this process caused Cu grains to reach Si substrate through the grain boundaries, and then the reaction between Cu and Si resulted in the formation of highly resistive Cu3Si.

  15. Properties of SiO2 grown on Ti, Co, Ni, Pd, and Pt silicides

    NASA Astrophysics Data System (ADS)

    Bartur, M.; Nicolet, M.-A.

    1984-01-01

    Successful utilization of silicides for VLSI applcations depends strongly on the formation of electrically insulating oxide on top of the silicide (1) . It is found that almost all silicides on a Si substrate can be oxidized to form an SiO2 layer on their surface. In this paper, we present some of the properties of such SiO2 layers formed on TiSi2, CoSi2, NiSi2, Pd2Si, and PtSi on a substrate following dry and wet oxidation. Electrical parameters that were investigated are the dielectric constant, dielectric strength (breakdown field), and pinhole density. The dielectric constant was found to be 3.49 ± 0.24, which is similar to the values reported for SiO2 grown on Si. The dielectric strength of the oxide layers depends on the polarity of the applied voltage, as is the case for oxide grown on poly-Si. Pinhole density in this oxide was also estimated and is less than 40 per cm2. The oxide density and stoichiometry were evaluated using Rutherford Backscattering Spectrometry (RBS) and DEKTAK, and compared to SiO2 grown on . The conclusion we have reached is that oxides grown on almost all the silicides investigated (except PdSi), hold promise for integrated circuit application. The main problem is the suicide roughness, induced by the thermal oxidation, that reduces the dielectric breakdown field.

  16. Electromigration effect upon the Sn-0.7 wt% Cu/Ni and Sn-3.5 wt% Ag/Ni interfacial reactions

    NASA Astrophysics Data System (ADS)

    Chen, Chih-ming; Chen, Sinn-wen

    2001-08-01

    This study investigates the effect of electromigration upon the interfacial reactions between the promising lead-free solders, Sn-Cu and Sn-Ag, with Ni substrate. Sandwich-type reaction couples, Sn-0.7 wt% Cu/Ni/Sn-0.7 wt% Cu and Sn-3.5 wt% Ag/Ni/Sn-3.5 wt% Ag, were reacted at 160, 180, and 200 °C for various lengths of time with and without the passage of electric currents. Without passage of electric currents through the couples, only one intermetallic compound Ni3Sn4 with ˜7 at. % Cu solubility was found at both interfaces of the Sn-0.7 wt% Cu/Ni couples. With the passage of an electric current of 500 A/cm2 density, the Cu6Sn5 phase was formed at the solder/Ni interface besides the Ni3Sn4 phase. Similar to those without the passage of electric currents, only the Ni3Sn4 phase was found at the Ni/solder interface. Directions of movement of electrons, Sn, and Cu atoms are the same at the solder/Ni interface, and the growth rates of the intermetallic layers were enhanced. At the Ni/solder interface, the electrons flow in the opposite direction of the Sn and Cu movement, and the growth rates of the intermetallic layers were retarded. Only the Ni3Sn4 phase was formed from the Sn-3.5 wt% Ag/Ni interfacial reaction with and without the passage of electric currents. Similar to the Sn-0.7 wt% Cu/Ni system, the movement of electrons enhances or retards the growth rates of the intermetallic layers at the solder/Ni and Ni/solder interfaces, respectively. Calculation results show the apparent effective charge za* decreases in magnitude with raising temperatures, which indicates the electromigration effect becomes insignificant at higher temperatures.

  17. Electrochemical Dealloying of PdCu3 Nanoparticles to Achieve Pt-like Activity for the Hydrogen Evolution Reaction.

    PubMed

    Jana, Rajkumar; Bhim, Anupam; Bothra, Pallavi; Pati, Swapan K; Peter, Sebastian C

    2016-10-20

    Manipulating the d-band center of the metal surface and hence optimizing the free energy of hydrogen adsorption (ΔGH ) close to the optimal adsorption energy (ΔGH =0) for hydrogen evolution reaction (HER), is an efficient strategy to enhance the activity for HER. Herein, we report a oleylamine-mediated (acting as the solvent, stabilizer, and reducing agent) strategy to synthesize intermetallic PdCu3 nanoparticles (NPs) without using any external reducing agent. Upon electrochemical cycling, PdCu3 transforms into Pd-rich PdCu (ΔGH =0.05 eV), exhibiting remarkably enhanced activity (with a current density of 25 mA cm(-2) at ∼69 mV overpotential) as an alternative to Pt for HER. The first-principle calculation suggests that formation of low coordination number Pd active sites alters the d-band center and hence optimal adsorption of hydrogen, leading to enhanced activity. This finding may provide guidelines towards the design and development of Pt-free highly active and robust electrocatalysts.

  18. Effect of Pd Additions on the Invariant Reactions in the Ag-CuOx System

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2006-02-01

    Palladium was added as a ternary component to a series of copper oxide-silver alloys in an effort increase the use temperature of these materials for potential ceramic brazing applications. Phase equilibria at low palladium and copper oxide concentrations in the Pd-CuOx-Ag system were determined experimentally using differential scanning calorimetry, microstructural analysis, and X-ray diffraction. Small additions of palladium were generally found to increase the temperature of the eutectic reaction present in the pseudobinary system, but have little effect on a higher temperature monotectic reaction. However once enough palladium was added (~5 mol%) to increase the new eutectic temperature to that of the original pseudobinary monotectic reaction, the pseudoternary monotectic temperature correspondingly began to move upward as well. The addition of palladium also forced the eutectic point to slightly lower silver concentrations, again causing a convergence with the former monotectic line.

  19. Topological Node-Line Semimetal and Dirac Semimetal State in Antiperovskite Cu3PdN.

    PubMed

    Yu, Rui; Weng, Hongming; Fang, Zhong; Dai, Xi; Hu, Xiao

    2015-07-17

    Based on first-principles calculation and effective model analysis, we propose that the cubic antiperovskite material Cu3PdN can host a three-dimensional (3D) topological node-line semimetal state when spin-orbit coupling (SOC) is ignored, which is protected by the coexistence of time-reversal and inversion symmetry. There are three node-line circles in total due to the cubic symmetry. Drumheadlike surface flat bands are also derived. When SOC is included, each node line evolves into a pair of stable 3D Dirac points as protected by C4 crystal symmetry. This is remarkably distinguished from the Dirac semimetals known so far, such as Na3Bi and Cd3As2, both having only one pair of Dirac points. Once C4 symmetry is broken, the Dirac points are gapped and the system becomes a strong topological insulator with (1;111) Z2 indices.

  20. Topological Node-Line Semimetal and Dirac Semimetal State in Antiperovskite Cu3PdN

    NASA Astrophysics Data System (ADS)

    Yu, Rui; Weng, Hongming; Fang, Zhong; Dai, Xi; Hu, Xiao

    2015-07-01

    Based on first-principles calculation and effective model analysis, we propose that the cubic antiperovskite material Cu3PdN can host a three-dimensional (3D) topological node-line semimetal state when spin-orbit coupling (SOC) is ignored, which is protected by the coexistence of time-reversal and inversion symmetry. There are three node-line circles in total due to the cubic symmetry. Drumheadlike surface flat bands are also derived. When SOC is included, each node line evolves into a pair of stable 3D Dirac points as protected by C4 crystal symmetry. This is remarkably distinguished from the Dirac semimetals known so far, such as Na3Bi and Cd3As2 , both having only one pair of Dirac points. Once C4 symmetry is broken, the Dirac points are gapped and the system becomes a strong topological insulator with (1;111) Z2 indices.

  1. Surface Segregation in a PdCu Alloy Hydrogen Separation Membrane

    SciTech Connect

    Miller, J.B.; Matranga, C.S.; Gellman, A.J.

    2007-06-01

    Separation of hydrogen from mixed gas streams is an important step for hydrogen generation technologies, including hydrocarbon reforming and coal/biomass gasification. Dense palladium-based membranes have received significant attention for this application because of palladium’s ability to dissociatively adsorb molecular hydrogen at its surface for subsequent transport of hydrogen atoms through its bulk. Alloying palladium with minor components, like copper, has been shown to improve both the membrane’s structural characteristics and resistance to poisoning of its catalytic surface [1]. Surface segregation—a composition difference between the bulk material and its surface—is common in alloys and can affect important surface processes. Rational design of alloy membranes requires that surface segregation be understood, and possibly controlled. In this work, we examine surface segregation in a polycrystalline Pd70Cu30 hydrogen separation membrane as a function of thermal treatment and adsorption of hydrogen sulfide.

  2. Synthesis and characterization of Pd@Pt-Ni core-shell octahedra with high activity toward oxygen reduction.

    PubMed

    Choi, Sang-Il; Shao, Minhua; Lu, Ning; Ruditskiy, Aleksey; Peng, Hsin-Chieh; Park, Jinho; Guerrero, Sandra; Wang, Jinguo; Kim, Moon J; Xia, Younan

    2014-10-28

    The oxygen reduction reaction (ORR) on the cathode of a polymer electrolyte fuel cell requires the use of a catalyst based on Pt, one of the most expensive metals on the earth. A number of strategies, including optimization of shape or facet, formation of alloys with other metals, and incorporation of a different metal into the core, have been investigated to enhance the activity of a Pt-based catalyst and thus reduce the loading of Pt. This article reports the synthesis and characterization of Pd@Pt-Ni core-shell octahedra with high activity toward ORR. The octahedra with an edge length of 8 nm were obtained by directly depositing thin, conformal shells of a Pt-Ni alloy on Pd octahedra of 6 nm in edge length. The key to the success of this synthesis is the use of an amphiphilic solvent to ensure good compatibility between the solvents typically used for the syntheses of Pd and Pt-Ni nanocrystals. The core-shell structure was confirmed by a number of techniques, including scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, in situ X-ray diffraction under H2 and He, and electrochemical measurements. Relative to the state-of-the-art Pt/C catalyst, the Pd@Pt-Ni/C catalyst showed mass and specific ORR activities enhanced by 12.5- and 14-fold, respectively. The formation of a core-shell structure helped increase the electroactive surface area in terms of Pt and thus the mass activity. During an accelerated durability test, the mass activity of the Pd@Pt-Ni/C catalyst only dropped by 1.7% after 10,000 cycles.

  3. Lack of dependence between intrinsic magnetic damping and perpendicular magnetic anisotropy in Cu(tCu)/[Ni/Co]N multilayers

    NASA Astrophysics Data System (ADS)

    Tang, Minghong; Li, Wei; Ren, Yang; Zhang, Zongzhi; Jin, Q. Y.

    2017-04-01

    The correlation between magnetic damping and perpendicular magnetic anisotropy has been investigated in Cu(tCu)/[Ni/Co]N multilayers by time-resolved magneto-optical Kerr effect. The uniaxial magnetic anisotropy constant Ku is varied in the range of 3.0-3.6 Merg/cm3 by tuning either multilayer repetition number N or Cu thickness tCu. It is found that the PMA strength Ku increases with the increase of N, while the damping constant α0 keeps nearly a constant of 0.025, implying the intrinsic damping is independent of the Ku tuned by N. In contrast, as tCu increases from 2.5 to 20 nm, the α0 value rises continuously up to 0.040, in spite of the rather weak enhancement in Ku and its non-monotonic variation behavior. We consider the constant α0 with N is due to the unchanged spin-orbit coupling strength at each Co/Ni interface, while the obvious enhancement in α0 with tCu results mainly from the increased degree of spin disordering at the rougher Cu/Ni interface.

  4. Multifunctional Pd/Ni-Co catalyst for hydrogen production by chemical looping coupled with steam reforming of acetic acid.

    PubMed

    Fermoso, Javier; Gil, María V; Rubiera, Fernando; Chen, De

    2014-11-01

    High yield of high-purity H2 from acetic acid, a model compound of bio-oil obtained from the fast pyrolysis of biomass, was produced by sorption-enhanced steam reforming (SESR). An oxygen carrier was introduced into a chemical loop (CL) coupled to the cyclical SESR process to supply heat in situ for the endothermic sorbent regeneration to increase the energy efficiency of the process. A new multifunctional 1 %Pd/20 %Ni-20 %Co catalyst was developed for use both as oxygen carrier in the CL and as reforming catalyst in the SESR whereas a CaO-based material was used as CO2 sorbent. In the sorbent-air regeneration step, the Ni-Co atoms in the catalyst undergo strong exothermic oxidation reactions that provide heat for the CaO decarbonation. The addition of Pd to the Ni-Co catalyst makes the catalyst active throughout the whole SESR-CL cycle. Pd significantly promotes the reduction of Ni-Co oxides to metallic Ni-Co during the reforming stage, which avoids the need for a reduction step after regeneration. H2 yield above 90 % and H2 purity above 99.2 vol % were obtained.

  5. Molecular Dynamics Simulation of the Phonon Conductivity in Cu-Ni Binary Alloy

    NASA Astrophysics Data System (ADS)

    Konishi, Yusuke; Fukushima, Tetsuya; Sato, Kazunori; Asai, Yoshihiro; Katayama-Yoshida, Hiroshi

    2014-03-01

    In 2010, a giant Peltier effect was observed in a Cu-Ni/Au junction. It is considered that this giant Peltier effect is caused by nano-scale phase separation formed in the sputtering process. The giant Peltier coefficient in the Cu-Ni/Au junction indicates the great Seebeck coefficient in Cu-Ni alloy. Although this alloy is a prospective thermoelectric material because of its great Seebeck coefficient, the low phonon thermal conductivity is also necessary for a large thermoelectric coefficient ZT. In order to find conditions for the low phonon conductivity, we calculate the thermal conductivity in Cu-Ni Alloy in various shapes with or without nanostructures by using nonequilibrium molecular dynamics simulation. In this simulation, we use a semi-empirical potential and the reverse nonequilibrium molecular dynamics method.

  6. Optimization of conductivity and strength in Cu-Ni-Si alloys by suppressing discontinuous precipitation

    NASA Astrophysics Data System (ADS)

    Han, Seung Zeon; Lee, Jehyun; Lim, Sung Hwan; Ahn, Jee Hyuk; Kim, Kwangho; Kim, Sangshik

    2016-11-01

    Cu-Ni-Si alloys with and without Ti were solution treated at 980 °C for 1 h and cooled by air cooling and water quenching, after which the specimens were aged at 500 °C. The two alloys showed different aging characteristics with different cooling rates during the aging process. The conductivity of all alloys increased during aging; for alloys that were water quenched, hardness increased at the early stage of aging and then drastically decreased. The air-cooled Cu-Ni-Si alloy without Ti also experienced an increase in hardness, which then decreased during aging, but the air-cooled Cu-Ni-Si alloy with Ti did not show a drastic decrease in hardness during prolonged aging. A combination of yield strength and conductivity of 820 MPa and 42% IACS, respectively, was achieved in the air-cooled Cu-Ni-Si-Ti alloy after solution treatment.

  7. Electrochemical aptasensor for the detection of adenosine by using PdCu@MWCNTs-supported bienzymes as labels.

    PubMed

    Wu, Dan; Ren, Xiang; Hu, Lihua; Fan, Dawei; Zheng, Yang; Wei, Qin

    2015-12-15

    A highly sensitive electrochemical adenosine aptasensor was fabricated by covalently immobilizing 3'-NH2-terminated capture probe (SSDNA1) and thionine (TH) on Au-GS modified glassy carbon electrode. 3'-SH-terminated adenosine aptamer (SSDNA2) was adsorbed onto palladium/copper alloyed supported on MWCNTs (PdCu@MWCNTs)-conjugated multiple bienzymes, glucose oxidase (GOx), and horseradish peroxidase (HRP) (SSDNA2/PdCu@MWCNTs/HRP/GOx). Then, it was immobilized onto the electrode surface through the hybridization between the adenosine aptamer and the capture probe. The signal was amplified based on the gradual electrocatalytic reduction of GOx-generated hydrogen peroxide by the multiple HRP through the mediating ability of the loaded multiple TH. However, the peak current of TH decreased in the presence of adenosine because the interaction between adenosine and its aptamer made SSDNA2/PdCu@MWCNTs/HRP/GOx release from the modified electrode. Various experimental parameters have been optimized for the detection of adenosine and tests for selectivity, reproducibility and stability have also been performed. Under the optimal condition, the proposed aptasensor displayed a wide linear range (10-400 nM) with the low detection limit (2.5 nM), which has been applied in human serum samples with satisfactory results. Thus, the combination of Au-GS as a sensor platform and PdCu@MWCNTs/HRP/GOx as labels can be a promising amplification strategy for highly sensitive adenosine detection.

  8. Low Pt-content ternary PdCuPt nanodendrites: an efficient electrocatalyst for oxygen reduction reaction

    SciTech Connect

    Fu, Shaofang; Zhu, Chengzhou; Song, Junhua; Zhang, Peina; Engelhard, Mark H.; Xia, Haibing; Du, Dan; Lin, Yuehe

    2017-01-01

    Dendritic nanostructures are capturing increasing attentions in electrocatalysis owing to their unique structural features and low density. Herein, we report for the first time bromide ions mediated synthesis of low-Pt-content PdCuPt ternary nanodendrites via galvanic replacement reaction between Pt precursor and PdCu template in aqueous solution. The experimental results show that the ternary PdCuPt nanodendrites present enhanced electrocatalytic performance for oxygen reduction reaction in acid solution compared with commercial Pt/C as well as some state-of-the-art catalysts. In details, the mass activity of the PdCuPt catalyst with optimized composition is 1.73 A/mgPt at 0.85 V vs RHE, which is 14 times higher than that of commercial Pt/C catalyst. Moreover, the long-term stability test demonstrates its better durability in acid solution. After 5k cycles, there is still 70% electrochemical surface area maintained. This method provides an efficient way to synthesize trimetallic alloys with controllable composition and specific structure for oxygen reduction reaction.

  9. Self-Supported 3D PdCu Alloy Nanosheets as a Bifunctional Catalyst for Electrochemical Reforming of Ethanol.

    PubMed

    Zhao, Xiaojing; Dai, Lei; Qin, Qing; Pei, Fei; Hu, Chengyi; Zheng, Nanfeng

    2017-03-01

    3D PdCu alloy nanosheets exhibit enhanced electrocatalytic activity toward hydrogen evolution reaction and ethanol oxidation reaction in alkaline media. Simultaneous hydrogen and acetate production via a solar-powered cell for ethanol reforming has been fabricated using the nanosheets as bifunctional electrocatalysts. The device is promising for the production of both hydrogen and value-added chemicals using renewable energy.

  10. Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells

    SciTech Connect

    Kim, Hyo-Joong; Seo, Ki-Won; Kim, Han-Ki; Noh, Yong-Jin; Na, Seok-In

    2014-09-01

    The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8 nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55 × 10{sup −5} Ω cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54 × 10{sup −3} Ω{sup −1}, comparable to those of the ITO/Ag/ITO multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag/ITO multilayer below 10 nm due to the flatness of the APC layer. The improved performance of the OSCs with ITO/APC/ITO multilayer electrodes indicates that the APC alloy interlayer prevents the agglomeration of the Ag-based metal interlayer and can decrease the thickness of the metal interlayer in the oxide-metal-oxide multilayer of high-performance OSCs.

  11. Cast-Replicated NiTiCu Foams with Superelastic Properties

    NASA Astrophysics Data System (ADS)

    Young, Marcus L.; DeFouw, John D.; Frenzel, Jan; Dunand, David C.

    2012-08-01

    Ni40Ti50Cu10 foams were replication cast into a porous SrF2 preform. This space holder is chemically stable in contact with liquid and solid Ni40Ti50Cu10, but can be removed by dissolution in nitric acid. A Ni40Ti50Cu10 foam with 60 pct porosity exhibits low stiffness (1 to 13 GPa) and large recoverable strains (~4 pct) during cyclical compression testing at 311 K (38 °C), within the superelastic range based on calorimetry results. This is the first time that replication casting is used to create an open foam of a NiTi-based shape-memory alloy, due to difficulties associated with the high reactivity and strong contamination tendency of the melt. Casting NiTi-based shape-memory alloy foams enable the economical production of porous actuators, energy absorbers, and biomedical implants with complex shapes.

  12. Calculation and measurement of helium generation and solid transmutations in Cu-Zn-Ni alloys

    SciTech Connect

    Greenwood, L.R.; Oliver, B.M.; Garner, F.A.; Muroga, T.

    1998-03-01

    A method was recently proposed by Garner and Greenwood that would allow the separation of the effects of solid and gaseous transmutation for Cu-Zn-Ni alloys. Pure copper produces zinc and nickel during neutron irradiation. {sup 63}Cu transmutes to {sup 64}Ni and {sup 64}Zn, in about a 2-to-1 ratio, and {sup 65}Cu transmutes to {sup 66}Zn. The {sup 64}Zn further transmutes to {sup 65}Zn which has been shown to have a high thermal neutron (n,{alpha}) cross-section. Since a three-step reaction sequence is required for natural copper, the amount of helium produced is much smaller than would be produced for the two-step, well-known {sup 58}Ni (n,{gamma}) {sup 59}Ni (n,{alpha}) reaction sequence. The addition of natural Zn and Ni to copper leads to greatly increased helium production in neutron spectra with a significant thermal component. Using a suitable Cu-Zn-Ni alloy matrix and comparative irradiation of thermal neutron-shielded and unshielded specimens, it should be possible to distinguish the separate influences of the solid and gaseous transmutants. Whereas helium generation rates have been previously measured for natural nickel and copper, they have not been measured for natural Zn or Cu-Ni-Zn alloys. The (N,{alpha}) cross section for {sup 65}Zn was inferred from helium measurements made with natural copper. By comparing helium production in Cu and Cu-Zn alloys, this cross section can be determined more accurately. In the current study, both the solid and helium transmutants were measured for Cu, Cu-5Ni, Cu-3.5Zn and Cu-5Ni-2Zn, irradiated in each of two positions in the HFIR JP-23 test. Highly accurate helium measurements were performed on these materials by isotope dilution mass spectrometry using a facility that was recently moved from Rockwell International to PNNL. It is shown that both the helium and solid transmutants for Cu-zn-Ni alloys can be calculated with reasonable certainty, allowing the development of a transmutation experiment as proposed by

  13. Allylic amination reactivity of Ni, Pd, and Pt heterobimetallic and monometallic complexes.

    PubMed

    Carlsen, Ryan W; Ess, Daniel H

    2016-06-14

    Transition metal heterobimetallic complexes with dative metal-metal interactions have the potential for novel fast reactivity. There are few studies that both compare the reactivity of different metal centers in heterobimetallic complexes and compare bimetallic reactivity to monometallic reactivity. Here we report density-functional calculations that show the reactivity of [Cl2Ti(N(t)BuPPh2)2M(II)(η(3)-methallyl)] heterobimetallic complexes for allylic amination follows M = Ni > Pd > Pt. This reactivity trend was not anticipated since the amine addition transition state involves M(II) to M(0) reduction and this could disadvantage Ni. Comparison of heterobimetallic complexes to the corresponding monometallic (CH2)2(N(t)BuPPh2)2M(II)(η(3)-methallyl) complexes reveals that this reactivity trend is due to the bimetallic interaction and that the bimetallic interaction significantly lowers the barrier height for amine addition by >10 kcal mol(-1). The impact of the early transition metal center on the amination addition barrier height depends on the late transition metal center. The lowest barrier heights for this reaction occur when late and early transition metal centers are from the same periodic table row.

  14. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, Xianghong; Peker, Atakan; Johnson, William L.

    1997-01-01

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM.sub.1-x Ti.sub.x).sub.a Cu.sub.b (Ni.sub.1-y Co.sub.y).sub.c wherein x is from 0.1 to 0.3, y.cndot.c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b.

  15. Dynamics of domain walls in Ti-Ni-Cu alloy

    NASA Astrophysics Data System (ADS)

    Liang, X. L.; Zhang, Z. F.; Liu, Q.; Shen, H. M.; Wang, Y. N.; Shi, P.; Chen, F. X.; Yang, D. Z.

    1999-12-01

    The internal friction for Ti-Ni-Cu shape memory alloys (SMAs) was measured in the Hz and kHz range. The peak temperature in the Hz range is independent of the measuring frequencies. Only in the tens of kHz range does the peak temperature shift with the frequencies, showing a thermally activated progress with icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/> = icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/>0e-B/Tc - T, characteristic of viscous motion of domain walls, instead of the Arrhenius relation. Taking into account the change of the density of the domain walls during the phase transformation, we modified the Q-1-formula by using a model of viscous motion of domain walls, obtaining a good result in agreement with the experimental data. Additionally, corresponding parameters, which play a key role in the shape memory effect, such as the viscosity coefficient and the effective pinning force constant, were obtained.

  16. Physically synthesized Ni-Cu nanoparticles for magnetic hyperthermia

    PubMed Central

    Bettge, Martin; Chatterjee, Jhunu; Haik, Yousef

    2004-01-01

    Background In this paper, a physical method to prepare copper-nickel alloy particles in the sub-micron range for possible self controlled magnetic hyperthermia treatment of cancer is described. It is reported that an increase in tumor temperature decreases the tumor resistance to chemo- and radiation therapies. Self controlled heating at the tumor site to avoid spot heating is managed by controlling the Curie temperature of the magnetic particles. The process described in this paper to produce the nanomagnetic particles allows for a large scale production of these particles. Methods The process used here is mainly composed of melting of the Cu-Ni mixture and ball milling of the resulted bulk alloy. Both mechanical abrasion and continuous grinding were used to break down the bulk amount into the desired particle size. Results It was found that the desired alloy is composed of 71% nickel and 29% copper by weight. It was observed that the coarse sand-grinded powder has a Curie temperature of 345 K and the fine ball-milled powder shows a temperature of 319 K – 320 K. Conclusion Self regulating magnetic hyperthermia can be achieved by synthesizing nanomagnetic particles with desired Curie temperature. In this study the desired range of Curie temperatures was obtained by combination of melting and ball milling of nickel-copper alloy. PMID:15132747

  17. Monitoring bacterial community shifts in bioleaching of Ni-Cu sulfide.

    PubMed

    He, Zhiguo; Zhao, Jiancun; Gao, Fengling; Hu, Yuehua; Qiu, Guanzhou

    2010-11-01

    The microbial ecology of the bioleaching of Ni-Cu sulfide is poorly understood and little effort has been made to handle the microbiological components of these processes. In this study, denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes fragments from bacteria was used to evaluate the changes of the bacterial community in the process of Ni-Cu sulfide bioleaching in a shaken flask system. The results revealed that the bacterial community was disturbed after the addition of Ni-Cu sulfide. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved sequences clustered together with the genera Acidithiobacillus and Leptospirillum. Multidimensional scaling (MDS) and cluster analysis of DGGE-banding patterns revealed that the process of Ni-Cu sulfide bioleaching in 46days was divided into three stages. During the bioleaching process of Ni-Cu sulfide, Leptospirillum was always dominant. The genera Acidithiobacillus was only detected at early and later stages of the bioleaching process. These results extend our knowledge on microbial dynamics in Ni-Cu sulfide bioleaching, a key issue required to improve commercial applications.

  18. A NiFeCu alloy anode catalyst for direct-methane solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhu, Huaiyu; Yang, Guangming; Park, Hee Jung; Jung, Doh Won; Kwak, Chan; Shao, Zongping

    2014-07-01

    In this study, a new anode catalyst based on a NiFeCu alloy is investigated for use in direct-methane solid oxide fuel cells (SOFCs). The influence of the conductive copper introduced into the anode catalyst layer on the performance of the SOFCs is systematically studied. The catalytic activity for partial oxidation of methane and coking resistance tests are proposed with various anode catalyst layer materials prepared using different methods, including glycine nitrate process (GNP), physical mixing (PM) and impregnation (IMP). The surface conductivity tests indicate that the conductivities of the NiFe-ZrO2/Cu (PM) and NiFe-ZrO2/Cu (IMP) catalysts are considerably greater than that of NiFe-ZrO2/Cu (GNP), which is consistent with the SEM results. Among the three preparation methods, the cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer performs best on CH4-O2 fuel, especially under reduced temperatures, because the coking resistance should be considered in real fuel cell conditions. The cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer also delivers an excellent operational stability using CH4-O2 fuel for 100 h without any signs of decay. In summary, this work provides new alternative anode catalytic materials to accelerate the commercialization of SOFC technology.

  19. Interfaces in La2NiO4- La2CuO4 superlattices

    NASA Astrophysics Data System (ADS)

    Smadici, S.; Lee, J. C. T.; Wang, S.; Abbamonte, P.; Logvenov, G.; Gozar, A.; Bozovic, I.

    2009-03-01

    Ni substitution on Cu sites in underdoped La2-xSrxCuO4 quickly restores Neel order. This was attributed to strong interaction between the Ni and doped holes. An open question was whether the additional Ni empty orbital or the different spin on Ni sites was at the origin of this strong interaction. We have addressed this problem with resonant soft x-ray scattering on a La2NiO4- La2CuO4 heterostructure. La2NiO4 and La2CuO4 have close lattice structures and electronic configurations. However, the x-ray scattering contrast between superlattice layers is greatly enhanced at soft x-ray resonant energies. Based on our measurements at the O K, La M, Cu L and Ni L edges a model of the charge, orbital and spin structures in these superlattices will be presented with a special emphasis on the interface region. This work was supported by Grants. DE-FG02- 06ER46285, DE-AC02-98CH10886, MA-509-MACA, DE-FG02-07ER46453 and DE-FG02-07ER46471.

  20. Interpretation of the Hume-Rothery electron concentration rule in the T2 Zn11 ( T=Ni , Pd, Co, and Fe) γ brasses based on first-principles FLAPW calculations

    NASA Astrophysics Data System (ADS)

    Asahi, R.; Sato, H.; Takeuchi, T.; Mizutani, U.

    2005-09-01

    The first-principles full-potential augmented plane wave (FLAPW) band calculations were performed for a series of T2Zn11 ( T=Ni , Pd, Co, and Fe) γ brasses to elucidate the Hume-Rothery electron concentration rule. The pseudogap is found immediately below the Fermi level EF in the Ni2Zn11 and Pd2Zn11γ brasses. A resulting gain in the electronic energy is attributed to their stabilization in the same way as in Cu5Zn8 and Cu9Al4 previously studied. However, the pseudogap is essentially shifted above EF in both Co2Zn11 and Fe2Zn11 . The Fourier analysis of the FLAPW wave function was made at the symmetry point N of the reduced Brillouin zone in the energy range involving the pseudogap. It is found that the plane wave giving rise to the largest Fourier component always resonates with the {330} and {411} zone planes to produce the pseudogap near EF . Moreover, a single-branch energy dispersion relation was constructed in the extended zone scheme by averaging the wave vector 2(k+G) having the largest Fourier component of the FLAPW wave function over selected electronic states in the Brillouin zone. The e/a value thus deduced is found to be close to 21/13=1.615 for Cu5Zn8 , Cu9Al4 , Ni2Zn11 , and Pd2Zn11γ brasses but to be only 1.4 and 1.3 for Co2Zn11 and Fe2Zn11 , respectively.

  1. Phase Evolution in the Pd-Ag-CuO Air Braze Filler Metal Alloy System

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2006-08-01

    Palladium was added as a ternary component to a series of copper oxide-silver alloys in an effort to increase the use temperature of these materials for potential ceramic air brazing applications. Phase equilibria in the ternary Pd-Ag-CuO system were investigated via differential scanning calorimetry (DSC) and a series of quenching experiments. Presented here are the latest findings on this system and a construction of the corresponding ternary phase diagram for low-to-moderate additions of palladium. The analysis included samples with higher palladium additions than were studied in the past, as well as an analysis of the composition-temperature trends in the Ag-CuO miscibility gap with palladium addition. It was found that the addition of palladium increases the solidus and liquidus and caused three phase zones to appear as expected by the phase rule. Furthermore, the palladium additions cause the miscibility gap boundary extending from the former binary eutectic to shift to lower silver-to-copper ratios.

  2. Characterization of Ternary NiTiPd High-Temperature Shape-Memory Alloys under Load-Biased Thermal Cycling

    NASA Technical Reports Server (NTRS)

    Bigelow, Glen S.; Padula, Santo A.; Noebe, Ronald D.; Garg, Anita; Gaydosh, Darrell

    2010-01-01

    While NiTiPd alloys have been extensively studied for proposed use in high-temperature shape-memory applications, little is known about the shape-memory response of these materials under stress. Consequently, the isobaric thermal cyclic responses of five (Ni,Pd)49.5Ti50.5 alloys with constant stoichiometry and Pd contents ranging from 15 to 46 at. pct were investigated. From these tests, transformation temperatures, transformation strain (which is proportional to work output), and unrecovered strain per cycle (a measure of dimensional instability) were determined as a function of stress for each alloy. It was found that increasing the Pd content over this range resulted in a linear increase in transformation temperature, as expected. At a given stress level, work output decreased while the amount of unrecovered strain produced during each load-biased thermal cycle increased with increasing Pd content, during the initial thermal cycles. However, continued thermal cycling at constant stress resulted in a saturation of the work output and nearly eliminated further unrecovered strain under certain conditions, resulting in stable behavior amenable to many actuator applications.

  3. Effects of Ni addition on the magnetostriction and microstructures of Fe70-xPd30Nix high-temperature ferromagnetic shape memory alloys

    NASA Astrophysics Data System (ADS)

    Lin, Yin-Chih; Lin, Chien-Feng

    2012-04-01

    This study investigated the effects of adding a third alloying element, Ni, to create Fe70-xPd30Nix (x = 2, 4, 6, and 8 at. % Ni) ferromagnetic shape memory alloys. The Ni replaced a portion of the Fe. The magnetostriction and microstructures of Fe70-xPd30Nix high-temperature ferromagnetic shape memory alloys were studied in detail. Investigation of the magnetostriction and microstructures indicated that the greater Ni amount in the Fe70-xPd30Nix alloys caused the less saturation magnetostriction at room temperature (RT); it was also observed that it was more difficult to generate an annealed recrystallization. However, greater Ni addition into the Fe70-xPd30Nix (x = 6 and 8 at. % Ni) alloys, the L10 + L1m twin phase decomposition into stoichiometric L10 + L1m + αbct structures could be suppressed when the alloys were aged at 500 °C for 100 h. The result was that the Fe70-xPd30Nix (x = 6 and 8 at. % Ni) alloys maintained a high magnetostriction and magnetostrictive susceptibility (Δλ‖s/ΔH) after the 500 °C/100 h aged treatment. This magnetic property of the Fe70-xPd30Nix (x = 6 and 8 at. % Ni) alloys is suitable for application in a high temperature (T > 500 °C) and high frequency environment.

  4. Kinetics and thermodynamics associated with Bi adsorption transitions at Cu and Ni grain boundaries

    SciTech Connect

    Tai, Kaiping; Feng, Lin; Dillon, Shen J.

    2013-05-21

    The grain boundary diffusivity of Au in Cu and Cu-Bi, and Cu in Ni and Ni-Bi are characterized by secondary ion mass spectroscopy depth profiling. Samples are equilibrated in a Bi containing atmosphere at temperatures above and below the onset of grain boundary adsorption transitions, sometimes called complexion transitions. A simple thermo-kinetic model is used to estimate the relative entropic contributions to the grain boundary energies. The results indicate that the entropy term plays a major role in promoting thermally and chemically induced grain boundary complexion transition.

  5. Single-Step Production of Nanostructured Copper-Nickel (CuNi) and Copper-Nickel-Indium (CuNiIn) Alloy Particles

    NASA Astrophysics Data System (ADS)

    Apaydın, Ramazan Oğuzhan; Ebin, Burçak; Gürmen, Sebahattin

    2016-07-01

    Nanostructured copper-nickel (CuNi) and copper-nickel-indium (CuNiIn) alloy particles were produced from aqueous solutions of copper, nickel nitrates and indium sulfate by hydrogen reduction-assisted ultrasonic spray pyrolysis. The effects of reduction temperatures, at 973 K, 1073 K, and 1173 K (700 °C, 800 °C, and 900 °C), on the morphology and crystalline structure of the alloy particles were investigated under the conditions of 0.1 M total precursor concentration and 0.5 L/min H2 volumetric flow rate. X-ray diffraction studies were performed to investigate the crystalline structure. Particle size and morphology were investigated by scanning electron microscope and energy-dispersive spectroscopy was applied to determine the chemical composition of the particles. Spherical nanocrystalline binary CuNi alloy particles were prepared in the particle size range from 74 to 455 nm, while ternary CuNiIn alloy particles were obtained in the particle size range from 80 to 570 nm at different precursor solution concentrations and reduction temperatures. Theoretical and experimental chemical compositions of all the particles are nearly the same. Results reveal that the precursor solution and reduction temperature strongly influence the particle size of the produced alloy particles.

  6. Catalytic activity of Pd-doped Cu nanoparticles for hydrogenation as a single-atom-alloy catalyst.

    PubMed

    Cao, Xinrui; Fu, Qiang; Luo, Yi

    2014-05-14

    The single atom alloy of extended surfaces is known to provide remarkably enhanced catalytic performance toward heterogeneous hydrogenation. Here we demonstrate from first principles calculations that this approach can be extended to nanostructures, such as bimetallic nanoparticles. The catalytic properties of the single-Pd-doped Cu55 nanoparticles have been systemically examined for H2 dissociation as well as H atom adsorption and diffusion, following the concept of single atom alloy. It is found that doping a single Pd atom at the edge site of the Cu55 shell can considerably reduce the activation energy of H2 dissociation, while the single Pd atom doped at the top site or in the inner layers is much less effective. The H atom adsorption on Cu55 is slightly stronger than that on the Cu(111) surface; however, a larger nanoparticle that contains 147 atoms could effectively recover the weak binding of the H atoms. We have also investigated the H atom diffusion on the 55-atom nanoparticle and found that spillover of the produced H atoms could be a feasible process due to the low diffusion barriers. Our results have demonstrated that facile H2 dissociation and weak H atom adsorption could be combined at the nanoscale. Moreover, the effects of doping one more Pd atom on the H2 dissociation and H atom adsorption have also been investigated. We have found that both the doping Pd atoms in the most stable configuration could independently exhibit their catalytic activity, behaving as two single-atom-alloy catalysts.

  7. Thin-layer chromatographic specification and separation of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations.

    PubMed

    Savasci, Sahin; Akçay, Mehmet; Ergül, Soner

    2010-07-01

    The M(PyDTC)(2) (M: Cu, Co, or Ni) and CuPyDTC complexes, prepared by reactions of ammonium pyrrolidinedithiocarbamate with metal nitrates, are examined for qualitative analysis, speciation, and mutual separation using thin-layer chromatography systems. These complexes and their mixtures are spotted to the activated and non-activated thin layers of silica gel 60GF(254) (Si-60GF(254)) with a 250-microm thickness. Toluene-dichloromethane mixtures (4:1, 1:1, 1:4 v/v) are used as mobile phases for running of the complexes. All of these chromatographic systems are successfully used for speciation of Cu(2+) and Cu(1+) cations. The best analytical separation for the qualitative analysis of corresponding metal cations and mutual separation of components in M(PyDTC)(2) and CuPyDTC complexes are obtained when using pure toluene-dichloromethane (1:1 v/v) on the activated layer. This study shows that it is possible to qualitatively analyze and satisfactorily separate a mixture of Cu(1+), Cu(2+), Ni(2+), and Co(2+) cations on cited chromatographic systems. These results may be also said for the adaptability or validity on column chromatography.

  8. Development of Cu alloy anode and separator coated with Al-Ni intermetallic compound

    SciTech Connect

    Toyokura, K.; Hoshino, K.; Yamamoto, M.

    1996-12-31

    Anode made of Cu alloy and separator coated with Al-Ni intermetallic compound have been developed for VCFC. Anode of Ni alloy is usually used. However, the alternative of cost lower than Ni alloy anode should be needed, because Ni is expensive. Cu is attractive as an anode material for VCFC because it is inexpensive and electrochemically noble. However, the creep resistance of Cu is not sufficient, compared with Ni alloy. In this study, strengthening due to oxide-dispersed microstructure has been developed in Cu-Ni-Al alloy with the two-step sintering process. A wet-seal technique has been widely applied for gas-sealing and supporting of electrolyte in MCFC. Since the wet-seal area is exposed to a severe corrosive environment, corrosion resistance of material for wet sealing is related with the cell performance. Al-Ni plating with post-heat treating for stainless steel has been investigated. Stainless steel substrate was plated with Al after being coated with Ni, then heat-treated at 750 {degrees}C for 1 hour in Ar gas atmosphere. Due to the treatment, Al-Ni intermetallic compound ( mainly Al3Ni2 ) layer is formed on stainless steel surface. The long-term immersion test was carried out till 14,500 hours in 62 mol% Li{sub 2}CO{sub 3}-38 mol% K{sub 2}CO{sub 3} at 650 {degrees}C under air-30%CO{sub 2} atmosphere, for the purpose of evaluating the corrosion resistance and thermal stability of Al-Ni intermetallic compound layer in actual generating with VCFC.

  9. Structure and phonon spectrum of a submonolayer Ni film on the surface of Cu(100)

    NASA Astrophysics Data System (ADS)

    Rusina, G. G.; Borisova, S. D.; Chulkov, E. V.

    2016-02-01

    The equilibrium atomic structure and the phonon spectra of a submonolayer (θ = 0.5 monolayer) Ni film deposited on the surface of Cu(100) are calculated using the potentials obtained by the embedded atom method. We consider atomic relaxation, the vibrational state density distribution on Ni and substrate atoms, and polarization of vibrational modes. Variation of the phonon spectrum upon segregation of Cu atoms on the film surface is considered. It is shown that mixing of vibrations of Ni adatoms with vibrations of substrate atoms occurs in the entire frequency range, leading to a frequency shift of the vibrational modes of the substrate and to the occurrence of new vibrational states atypical of a clean surface. The Cu(100)- c(2 × 2)-Ni structure is dynamically stabler when placed in the subsurface layer of the substrate.

  10. Effect of Ni and Pd Addition on Mechanical, Thermodynamic, and Electronic Properties of AuSn4-Based Intermetallics: A Density Functional Investigation

    NASA Astrophysics Data System (ADS)

    Tian, Yali; Zhou, Wei; Wu, Ping

    2016-08-01

    The effects of Ni and Pd addition on the mechanical, thermodynamic, and electronic properties of AuSn4-based intermetallic compounds (IMCs) have been investigated by first-principles calculations to reveal the essence of Au embrittlement. Three kinds of doped (namely Ni-doped, Pd-doped, and Ni/Pd-codoped) IMCs are considered in this work. The polycrystalline elastic properties are deduced from single-crystal elastic constants. It is found that the doped systems together with nondoped AuSn4 are all ductile phases. For Ni-doped AuSn4, the modulus, hardness, brittleness, Debye temperature, and minimum thermal conductivity increase with the Ni fraction, but this is not the case for the Pd-doped material, since Au0.75Pd0.25Sn4 is the more brittle phase. For Au0.5Pd0.25Ni0.25Sn4, the mechanical, thermodynamic, and electronic properties are similar to those of Au0.5Pd0.5Sn4.

  11. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, X.; Peker, A.; Johnson, W.L.

    1997-04-08

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3} K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM{sub 1{minus}x}Ti{sub x}){sub a} Cu{sub b} (Ni{sub 1{minus}y}Co{sub y}){sub c} wherein x is from 0.1 to 0.3, y{center_dot}c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b. 2 figs.

  12. Transition metal interaction and Ni-Fe-Cu-Si phases in silicon

    NASA Astrophysics Data System (ADS)

    Heuer, M.; Buonassisi, T.; Istratov, A. A.; Pickett, M. D.; Marcus, M. A.; Minor, A. M.; Weber, E. R.

    2007-06-01

    In the present article we characterize several intermetallic phases of the Cu-Ni-Fe-Si system found as precipitates in the misfit dislocation layer of intentionally contaminated and slowly cooled Si1-xGex/Si-heterostructures. The clusters showed a characteristic phase speciation into a Cu-rich part similar to Cu3Si and an Fe-Ni-Cu-Si phase similar to NiSi2. It is suggested that the precipitate formation of the investigated intermetallic silicides involves a homogeneous precursor phase at higher temperatures that later decomposes into the observed phases. Our results indicate that chemical reactions between metals and silicon during precipitation may reduce the lattice mismatch compared to single-metal precipitates, rendering mixed-metal-silicide precipitates more stable and energetically favorable.

  13. Thermomechanical behavior and microstructural evolution of a Ni(Pd)-rich Ni24.3Ti49.7Pd26 high temperature shape memory alloy

    SciTech Connect

    Benafan, O.; Garg, A.; Noebe, R. D.; Bigelow, G. S.; Padula, S. A.; Gaydosh, D. J.; Vaidyanathan, R.; Clausen, B.; Vogel, S. C.

    2015-04-20

    We investigated the effect of thermomechanical cycling on a slightly Ni(Pd)-rich Ni24.3Ti49.7Pd26 (near stochiometric Ni–Ti basis with Pd replacing Ni) high temperature shape memory alloy. Furthermore, aged tensile specimens (400 °C/24 h/furnace cooled) were subjected to constant-stress thermal cycling in conjunction with microstructural assessment via in situ neutron diffraction and transmission electron microscopy (TEM), before and after testing. It was shown that in spite of the slightly Ni(Pd)-rich composition and heat treatment used to precipitation harden the alloy, the material exhibited dimensional instabilities with residual strain accumulation reaching 1.5% over 10 thermomechanical cycles. This was attributed to insufficient strengthening of the material (insufficient volume fraction of precipitate phase) to prevent plasticity from occurring concomitant with the martensitic transformation. In situ neutron diffraction revealed the presence of retained martensite while cycling under 300 MPa stress, which was also confirmed by transmission electron microscopy of post-cycled samples. Neutron diffraction analysis of the post-thermally-cycled samples under no-load revealed residual lattice strains in the martensite and austenite phases, remnant texture in the martensite phase, and peak broadening of the austenite phase. The texture we developed in the martensite phase was composed mainly of those martensitic tensile variants observed during thermomechanical cycling. Presence of a high density of dislocations, deformation twins, and retained martensite was revealed in the austenite state via in-situ TEM in the post-cycled material, providing an explanation for the observed peak broadening in the neutron diffraction spectra. Despite the dimensional instabilities, this alloy exhibited a biased transformation strain on the order of 3% and a two-way shape memory effect (TWSME) strain of ~2%, at relatively high actuation

  14. DFT study of Hg adsorption on M-substituted Pd(1 1 1) and PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Jiancheng; Yu, Huafeng; Geng, Lu; Liu, Jianwen; Han, Lina; Chang, Liping; Feng, Gang; Ling, Lixia

    2015-11-01

    The adsorption of Hgn (n = 1-3) on the Au-, Ag-, Cu-substituted Pd(1 1 1) surfaces as well as the PdM/γ-Al2O3(1 1 0) (M = Au, Ag, Cu) surfaces has been investigated using spin-polarized density functional theory calculations. It is found that M-substituted Pd(1 1 1) surfaces show as good Hg adsorption capacity as the perfect Pd(1 1 1) at low Hg coverage, while the Hg adsorption capacity is only slightly weakened at high Hg coverage. On the basis of stepwise adsorption energies analysis, it is concluded that M-substituted Pd(1 1 1) surfaces can contribute to the binding of Hg atom on the surfaces at high Hg coverage. The electronic properties of the second metal atoms are the main factor contributes to the Hg adsorption capacity. Gas phase Pd2 shows better Hg adsorption capacity than Pd2/γ-Al2O3, while PdM/γ-Al2O3 can adsorb Hg more efficiently than bare PdM clusters. It suggests that the γ-Al2O3 support can enhance the activity of PdM for Hg adsorption and reduces the activity of Pd2. It is also found that Pd is the main active composition responsible for the interaction of mercury with the surface for PdM/γ-Al2O3 sorbent. Taking Hg adsorption capacity and economic costs into account, Cu addition is a comparatively good candidate for Hg capture.

  15. Diffusion bonding titanium to stainless steel using Nb/Cu/Ni multi-interlayer

    SciTech Connect

    Li Peng; Li Jinglong; Xiong Jiangtao; Zhang Fusheng; Raza, Syed Hamid

    2012-06-15

    By using Nb/Cu/Ni structure as multi-interlayer, diffusion bonding titanium to austenitic stainless steel has been conducted. The effects of bonding temperature and bonding time on the interfacial microstructure were analyzed by scanning electron microscope equipped with energy dispersive spectroscope, and the joint strength was evaluated by tensile test. The results showed that Ni atoms aggregated at the Cu-Nb interface, which promoted Cu solution in Nb. This phenomenon forms a Cu-Nb solution strengthening effect. However, such effect would decay by using long bonding time that dilutes Ni atom aggregation, or be suppressed by using high bonding temperature that embrittles the Cu-Nb interface due to the formation of large grown intermetallic compounds. The sound joint was obtained by promoted parameters as 850 Degree-Sign C for 30-45 min, under which a bonding strength around 300 MPa could be obtained. - Highlights: Black-Right-Pointing-Pointer Titanium was diffusion bonded to stainless steel using Nb/Cu/Ni multi-interlayer. Black-Right-Pointing-Pointer The effects of bonding parameters on microstructure and joint strength were studied. Black-Right-Pointing-Pointer Nickel aggregation promotes Cu solution in Nb which can strengthen the joint. Black-Right-Pointing-Pointer The sound joint with strength of around 300 MPa was obtained by promoted parameters.

  16. Highly Active Three-Dimensional NiFe/Cu2 O Nanowires/Cu Foam Electrode for Water Oxidation.

    PubMed

    Chen, Hu; Gao, Yan; Sun, Licheng

    2017-04-10

    Water splitting is of paramount importance for exploiting renewable energy-conversion and -storage systems, but is greatly hindered by the kinetically sluggish oxygen evolution reaction (OER). In this work, a three-dimensional, highly efficient, and durable NiFe/Cu2 O nanowires/Cu foam anode (NiFe/Cu2 O NWs/CF) for water oxidation in 1.0 m KOH was developed. The obtained electrode exhibited a current density of 10 mA cm(-2) at a uniquely low overpotential of η=215 mV. The average specific current density (js ) was estimated, on the basis of the electrocatalytically active surface area, to be 0.163 mA cm(-2) at η=310 mV. The electrode also displayed a low Tafel slope of 42 mV decade(-1) . Moreover, the NiFe/Cu2 O NWs/CF electrode could maintain a steady current density of 100 mA cm(-2) for 50 h at an overpotential of η=260 mV. The outstanding electrochemical performance of the electrode for the OER was attributed to the high conductivity of the Cu foam and the specific structure of the electrode with a large interfacial area.

  17. Heteronuclear transition metal diatomics - The bonding and electronic structure of ScNi, YNi, ScPd, and YPd

    NASA Technical Reports Server (NTRS)

    Faegri, Knut, Jr.; Bauschlicher, Charles W., Jr.

    1991-01-01

    High quality ab initio calculations show that ScNi, YNi, ScPd, and YPd all have 2Sigma(+) ground states in agreement with electron spin resonance experiments. For ScNi and YNi, this is expected based on the lowest atomic asymptote. For ScPd and YPd, the lowest atomic asymptote would give the order of stability 2Delta greater than 2Pi equal to about 2Sigma(+), but the calculations show that mixing in of the excited asymptotes preferentially lowers the 2Sigma(+) state. The calculations show that the quartet states are about 20-30 kcal/mol above the ground state, and therefore probably do not contribute significantly to the unexpected g(vertical) values found in experiment. Calculations of excited states for YPd reveal some strong transitions that should be amenable to spectroscopic studies.

  18. Clean Synthesis of an Economical 3D Nanochain Network of PdCu Alloy with Enhanced Electrocatalytic Performance towards Ethanol Oxidation.

    PubMed

    Liu, Jiawei; Huang, Zhao; Cai, Kai; Zhang, Huan; Lu, Zhicheng; Li, Tingting; Zuo, Yunpeng; Han, Heyou

    2015-12-01

    A one-pot method for the fast synthesis of a 3D nanochain network (NNC) of PdCu alloy without any surfactants is described. The composition of the as-prepared PdCu alloy catalysts can be precisely controlled by changing the precursor ratio of Pd to Cu. First, the Cu content changes the electronic structure of Pd in the 3D NNC of PdCu alloy. Second, the 3D network structure offers large open pores, high surface areas, and self-supported properties. Third, the surfactant-free strategy results in a relatively clean surface. These factors all contribute to better electrocatalytic activity and durability towards ethanol oxidation. Moreover, the use of copper in the alloy lowers the price of the catalyst by replacing the noble metal palladium with non-noble metal copper. The composition-optimized Pd80 Cu20 alloy in the 3D NNC catalyst shows an increased electrochemically active surface area (80.95 m(2)  g(-1) ) and a 3.62-fold enhancement of mass activity (6.16 A mg(-1) ) over a commercial Pd/C catalyst.

  19. Giant magnetoresistance of Co-Ni-Cu alloys produced by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Q.; Zhang, Z. D.; Xiao, Q. F.; Geng, D. Y.; Zhao, X. G.; Zhang, W. S.; You, C. Y.

    2003-05-01

    The structure, magnetic properties and magnetoresistance (MR) effect of Co20NixCu80-x alloys produced by mechanical alloying and subsequent annealing have been investigated. After milling for 5 h, a supersaturated solid solution forms for all the alloys. Co20NixCu80-x alloys annealed at 973 K for 30 min segregated into two-phases of fcc-Co and fcc-Cu. The maximum value for MR ratio, at room temperature is 4.7% at a field of 1.2 T, and at 5 K is 15% at a field of 2 T for Co20Cu80 annealed at 718 K for 30 min. The MR ratio of Co-Ni-Cu alloys decreases monotonically with increasing Ni content. The MR and its dependence on particle size are discussed.

  20. Ion irradiation induced element-enriched and depleted nanostructures in Zr-Al-Cu-Ni metallic glass

    SciTech Connect

    Chen, H. C.; Liu, R. D.; Yan, L. E-mail: zhouxingtai@sinap.ac.cn; Zhou, X. T. E-mail: zhouxingtai@sinap.ac.cn; Cao, G. Q.; Wang, G.

    2015-07-21

    The microstructural evolution of a Zr-Al-Cu-Ni metallic glass induced by irradiation with Ar ions was investigated. Under ion irradiation, the Cu- and Ni-enriched nanostructures (diameter of 30–50 nm) consisted of crystalline and amorphous structures were formed. Further, Cu- and Ni-depleted nanostructures with diameters of 5–20 nm were also observed. The formation of these nanostructures can be ascribed to the migration of Cu and Ni atoms in the irradiated metallic glass.

  1. The Influence of Cu on Metastable NiSn4 in Sn-3.5Ag- xCu/ENIG Joints

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    We have investigated the effect of small amounts of Cu on suppression of metastable βSn-NiSn4 eutectic growth in solder joints between Sn-3.5Ag- xCu solders and Ni-based substrates. For Sn-3.5Ag/electroless nickel immersion gold (ENIG) and Sn-3.5Ag/Ni solder joints we showed that the eutectic mixture contains βSn, Ag3Sn, and metastable NiSn4. It was found that addition of only 0.005 wt.% Cu to Sn-3.5Ag- xCu/ENIG or Sn-3.5Ag- xCu/Ni joints promoted formation of a stable βSn-Ni3Sn4 eutectic and that both Ni3Sn4 and NiSn4 occur in the eutectic at this Cu level. We also showed that for complete prevention of formation of metastable NiSn4 during eutectic solidification of the solder joint, addition of at least 0.3 wt.% Cu was required.

  2. Synthesis of Ni-Pd nanocubes and nanorods with high selectivity through a modified polyol process

    NASA Astrophysics Data System (ADS)

    Hokenek, Selma; Bennett, Crystal; Kuhn, John N.

    2013-07-01

    Shape controlled bimetallic nanoparticles are important for catalytic, electrocatalytic, optical, and magnetic applications. This effort describes the synthesis of monodisperse bimetallic nickel-palladium (Ni0.25Pd0.75) nanocubes and nanorods with a combined shape selectivity of over 85%. Composition of the synthesized nanoparticles was determined using STEM-EDX and XRD. The shape control was achieved through the use of poly-vinyl pyrrolidone (PVP) surfactant and solvated bromide ions in 1,5-propanediol under an inert argon atmosphere. The use of bromide ions facilitated the stabilization of (1 0 0) and (1 1 0) surface facets, yielding nanocubes and nanorods, respectively, while the polymeric capping agent prevented agglomeration. The influence of the bromide ions was verified by using TEM imaging to ascertain the shapes of the synthesized nanoparticles. The reduction temperature used in the synthesis (140 °C to 180 °C) and the bromide ion-to-metal precursor ratio (15:1 to 50:1) were varied to maximize the shape distribution towards nanocubes and nanorods and to regulate the nucleation and growth phases of the synthesis.

  3. Colloidal synthesis of Cu-ZnO and Cu@CuNi-ZnO hybrid nanocrystals with controlled morphologies and multifunctional properties.

    PubMed

    Zeng, Deqian; Gong, Pingyun; Chen, Yuanzhi; Zhang, Qinfu; Xie, Qingshui; Peng, Dong-Liang

    2016-06-02

    Metal-semiconductor hybrid nanocrystals have received extensive attention owing to their multiple functionalities which can find wide technological applications. The utilization of low-cost non-noble metals to construct novel metal-semiconductor hybrid nanocrystals is important and meaningful for their large-scale applications. In this study, a facile solution approach is developed for the synthesis of Cu-ZnO hybrid nanocrystals with well-controlled morphologies, including nanomultipods, core-shell nanoparticles, nanopyramids and core-shell nanowires. In the synthetic strategy, Cu nanocrystals formed in situ serve as seeds for the heterogeneous nucleation and growth of ZnO, and it eventually forms various Cu-ZnO hetero-nanostructures under different reaction conditions. These hybrid nanocrystals possess well-defined and stable heterostructure junctions. The ultraviolet-visible-near infrared spectra reveal morphology-dependent surface plasmon resonance absorption of Cu and the band gap absorption of ZnO. Furthermore, we construct a novel Cu@CuNi-ZnO ternary hetero-nanostructure by incorporating the magnetic metal Ni into the pre-synthesized colloidal Cu nanocrystals. Such hybrid nanocrystals possess a magnetic Cu-Ni intermediate layer between the ZnO shell and the Cu core, and exhibit ferromagnetic/superparamagnetic properties which expand their functionalities. Finally, enhanced photocatalytic activities are observed in the as-prepared non-noble metal-ZnO hybrid nanocrystals. This study not only provides an economical way to prepare high-quality morphology-controlled Cu-ZnO hybrid nanocrystals for potential applications in the fields of photocatalysis and photovoltaic devices, but also opens up new opportunities in designing ternary non-noble metal-semiconductor hybrid nanocrystals with multifunctionalities.

  4. Spin Crossover in Fe(II)-M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2-Substituted Pyrazines.

    PubMed

    Kucheriv, Olesia I; Shylin, Sergii I; Ksenofontov, Vadim; Dechert, Sebastian; Haukka, Matti; Fritsky, Igor O; Gural'skiy, Il'ya A

    2016-05-16

    Discovery of spin-crossover (SCO) behavior in the family of Fe(II)-based Hofmann clathrates has led to a "new rush" in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe(2+), square planar tetracyanometalates M(II)(CN)4(2-) (M(II) = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe(II) ion has a pseudo-octahedral coordination environment supported by four μ4-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M(II) = Ni (1), Pd (2), Pt (3); X = Me and M(II) = Ni (4), Pd (5)) or one 2X-pyrazine and one water molecule (X = I and M(II) = Ni (7), Pd (8), Pt (9)), or, alternatively, two distinct Fe(II) positions with either two pyrazines or two water molecules (X = Me and M(II) = Pt (6)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN6 units (1-6) display cooperative spin transition, while Fe(II) ions in N5O or N4O2 surrounding are high spin (HS). Structural changes in the nearest Fe(II) environment upon low-spin (LS) to HS transition, which include ca. 10% Fe-N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of 1-9 (see abstract figure). Effects of a pyrazine substituent and M(II) nature on the hyperfine parameters in both spin states are established.

  5. Interfacial microstructure between Sn-3Ag-xBi alloy and Cu substrate with or without electrolytic Ni plating

    NASA Astrophysics Data System (ADS)

    Hwang, Chi-Won; Lee, Jung-Goo; Suganuma, Katsuaki; Mori, Hirotaro

    2003-02-01

    The microstructure of the interfacial phase of Sn-3Ag-xBi alloy on a Cu substrate with or without electrolytic Ni plating was evaluated. Bismuth additions into Sn-Ag alloys do not affect interfacial phase formations. Without plating, η-Cu6Sn5/ɛ-Cu3Sn interfacial phases developed as reaction products in the as-soldered condition. The η-phase Cu6Sn5 with a hexagonal close-packed structure grows about 1-µm scallops. The ɛ-phase Cu3Sn with an orthorhombic structure forms with small 100-nm grains between η-Cu6Sn5 and Cu. For Ni plating, a Ni3Sn4 layer of monoclinic structure formed as the primary reaction product, and a thin η-Ni3Sn2 layer of hexagonal close-packed structure forms between the Ni3Sn4 and Ni layer. In the Ni layer, Ni-Sn compound particles of nanosize distribute by Sn diffusion into Ni. On the total thickness of interfacial reaction layers, Sn-3Ag-6Bi joints are thicker by about 0.9 µm for the joint without Ni plating and 0.18 µm for the joint with Ni plating than Sn-3Ag joints, respectively. The thickening of interfacial reaction layers can affect the mechanical properties of strength and fatigue resistance.

  6. Epitaxial Growth of Multimetallic Pd@PtM (M = Ni, Rh, Ru) Core-Shell Nanoplates Realized by in Situ-Produced CO from Interfacial Catalytic Reactions.

    PubMed

    Yan, Yucong; Shan, Hao; Li, Ge; Xiao, Fan; Jiang, Yingying; Yan, Youyi; Jin, Chuanhong; Zhang, Hui; Wu, Jianbo; Yang, Deren

    2016-12-14

    Pt-based multimetallic core-shell nanoplates have received great attention as advanced catalysts, but the synthesis is still challenging. Here we report the synthesis of multimetallic Pd@PtM (M = Ni, Rh, Ru) nanoplates including Pd@Pt nanoplates, in which Pt or Pt alloy shells with controlled thickness epitaxially grow on plate-like Pd seeds. The key to achieve high-quality Pt-based multimetallic nanoplates is in situ generation of CO through interfacial catalytic reactions associated with Pd nanoplates and benzyl alcohol. In addition, the accurate control in a trace amount of CO is also of great importance for conformal growth of multimetallic core-shell nanoplates. The Pd@PtNi nanoplates exhibit substantially improved activity and stability for methanol oxidation reaction (MOR) compared to the Pd@Pt nanoplates and commercial Pt catalysts due to the advantages arising from plate-like, core-shell, and alloy structures.

  7. Development of Ag-Pd-Au-Cu alloy for multiple dental applications. Part 1. Effects of Pd and Cu contents, and addition of Ga or Sn on physical properties and bond with ultra-low fusing ceramic.

    PubMed

    Goto, S; Miyagawa, Y; Ogura, H

    2000-09-01

    Ag-Pd-Au-Cu quaternary alloys consisting of 30-50% Ag, 20-40% Pd, 10-20% Cu and 20% Au (mother alloys) were prepared. Then 5% Sn or 5% Ga was added to the mother alloy compositions, and another two alloy systems (Sn-added alloys and Ga-added alloys) were also prepared. The bond between the prepared alloys and an ultra-low fusing ceramic as well as their physical properties such as the solidus point, liquidus point and the coefficient of thermal expansion were evaluated. The solidus point and liquidus point of the prepared alloys ranged from 802 degrees C to 1142 degrees C and from 931 degrees C to 1223 degrees C, respectively. The coefficient of thermal expansion ranged from 14.6 to 17.1 x 10(-6)/degrees C for the Sn- and Ga-added alloys. In most cases, the Pd and Cu contents significantly influenced the solidus point, liquidus point and coefficient of thermal expansion. All Sn- and Ga-added alloys showed high area fractions of retained ceramic (92.1-100%), while the mother alloy showed relatively low area fractions (82.3%) with a high standard deviation (20.5%). Based on the evaluated properties, six Sn-added alloys and four Ga-added alloys among the prepared alloys were suitable for the application of the tested ultra-low fusing ceramic.

  8. 63Cu nuclear magnetic resonance study of Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4): Ni-induced spin density oscillation and modification of the low energy spin fluctuations.

    PubMed

    Williams, G V M; Jurkutat, M; Rybicki, D; Haase, J

    2011-02-23

    We report the results from a (63)Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4). We find that Ni induces a magnetic broadening of the (63)Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from (63)Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the (63)Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni.

  9. Combinatorial PtSnM (M = Fe, Ni, Ru and Pd) nanoparticle catalyst library toward ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Almeida, T. S.; Van Wassen, A. R.; VanDover, R. B.; de Andrade, A. R.; Abruña, H. D.

    2015-06-01

    Electrode arrays containing 91 combinations of Pt-Sn-M (M = Fe, Ni, Pd, and Ru) were prepared by borohydride reduction of aqueous metal salts on carbon paper, and screened by fluorescence assay for activity as ethanol electrooxidation catalysts. Catalysts that showed high activity for this reaction were identified as being Pt(80)Sn(10)Fe(10), Pt(80)Sn(10)Ni(10), Pt(70)Sn(20)Pd(10), and Pt(70)Sn(10)Ru(20) (numbers in parenthesis indicate atomic percent). These were significantly more active than Pt or PtSn catalysts, also present in the electrode arrays. These 4 compositions were synthesized as nanoparticles and characterized physically and electrochemically. X-ray diffraction showed a Pt face-centered cubic (fcc) structure with an average crystallite size of about 2.0 nm for all catalysts. The electrochemical tests for the oxidation of ethanol revealed excellent electrocatalytic activity and single cell (fuel cell) power density for all four catalyst formulations. Fe-containing catalysts exhibited the highest activity (13 A gPt-1) and single-cell performance (50 mW cm-2) followed by Ni- and Pd-containing materials with similar results; electrocatalytic activity around 10 A gPt-1 and power densities of 43 mW cm-2. The lowest performance was observed for the Ru-containing catalyst. However, its single-cell performance (30 mW cm-2) was still comparable to that of the commercial PtSn-Etek electrocatalyst.

  10. Physical properties of the Ce2MAl7Ge4 heavy-fermion compounds (M=Co,Ir,Ni,Pd)

    DOE PAGES

    Ghimire, N. J.; Cary, S. K.; Eley, S.; ...

    2016-05-23

    Here, we report the synthesis, crystal structure, and characterization by means of single-crystal x-ray diffraction, neutron powder diffraction, and magnetic, thermal, and transport measurements of the new heavy-fermion compounds Ce2MAl7Ge4 (M=Co,Ir,Ni,Pd). These compounds crystallize in a noncentrosymmetric tetragonal space group Pmore » $$\\bar{4}$$21m, consisting of layers of square nets of Ce atoms separated by Ge-Al and M-Al-Ge blocks. Ce2CoAl7Ge4,Ce2IrAl7Ge4, and Ce2NiAl7Ge4 order magnetically below TM=1.8, 1.6, and 0.8 K, respectively. There is no evidence of magnetic ordering in Ce2PdAl7Ge4 down to 0.4 K. Furthermore, the small amount of entropy released in the magnetic state of Ce2MAl7Ge4 (M = Co, Ir, Ni) and the reduced specific heat jump at TM suggest a strong Kondo interaction in these materials. Ce2PdAl7Ge4 shows non-Fermi liquid behavior, possibly due to the presence of a nearby quantum critical point.« less

  11. Reliability Assessment and Activation Energy Study of Au and Pd-Coated Cu Wires Post High Temperature Aging in Nanoscale Semiconductor Packaging.

    PubMed

    Gan, C L; Hashim, U

    2013-06-01

    Wearout reliability and high temperature storage life (HTSL) activation energy of Au and Pd-coated Cu (PdCu) ball bonds are useful technical information for Cu wire deployment in nanoscale semiconductor device packaging. This paper discusses the influence of wire type on the wearout reliability performance of Au and PdCu wire used in fine pitch BGA package after HTSL stress at various aging temperatures. Failure analysis has been conducted to identify the failure mechanism after HTSL wearout conditions for Au and PdCu ball bonds. Apparent activation energies (Eaa) of both wire types are investigated after HTSL test at 150 °C, 175 °C and 200 °C aging temperatures. Arrhenius plot has been plotted for each ball bond types and the calculated Eaa of PdCu ball bond is 0.85 eV and 1.10 eV for Au ball bond in 110 nm semiconductor device. Obviously Au ball bond is identified with faster IMC formation rate with IMC Kirkendall voiding while PdCu wire exhibits equivalent wearout and or better wearout reliability margin compare to conventional Au wirebond. Lognormal plots have been established and its mean to failure (t50) have been discussed in this paper.

  12. Influence of structural parameters on magnetoresistive properties of CuFeNi melt spun ribbons.

    PubMed

    Cazottes, S; Danoix, F; Fnidiki, A; Lemarchand, D; Baricco, M

    2009-04-01

    The microstructure of Cu(80)Fe(10)Ni(10) (at%) granular ribbon was investigated by means of atom probe tomography (APT). A granular system is composed of magnetic precipitates embedded in a non-magnetic matrix. In this ribbon, the magnetic precipitates have a diameter smaller than 5nm in the as-spun state, and their crystallographic structure is very similar to the one of the matrix, which makes it difficult to characterize them using conventional techniques. Those data are of great importance to understand the magnetic and the transport behaviour of these ribbons. Using atom probe tomography, a 3D reconstruction of the microstructure of the as-spun and annealed ribbons was achieved and a precise characterization of the compositions of the two phases and of the composition profile at interfaces was carried out. In the as-spun state the composition of the matrix is Cu(89)Fe(3)Ni(8), the one of the precipitates is Cu(30)Fe(40)Ni(30). Upon annealing, the precipitates get enriched in iron. After annealing at 600 degrees C for 24h, the measured compositions are close to the one predicted by Thermocalc, with Cu(94)Fe(1)Ni(5) for the matrix and Cu(5)Fe(64)Ni(31) for the precipitates.

  13. Cytotoxicity Evaluation and Magnetic Characteristics of Mechano-thermally Synthesized CuNi Nanoparticles for Hyperthermia

    NASA Astrophysics Data System (ADS)

    Amrollahi, P.; Ataie, A.; Nozari, A.; Seyedjafari, E.; Shafiee, A.

    2015-03-01

    CuNi alloys are very well known, both in academia and industry, based on their wide range of applications. In the present investigation, the previously synthesized Cu0.5Ni0.5 nanoparticles (NPs) by mechano-thermal method were studied more extensively. Phase composition and morphology of the samples were studied by employing x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The Curie temperature ( T c) was determined by differential scanning calorimetry (DSC). In vitro cytotoxicity was studied through methyl-thiazolyl-tetrazolium (MTT) assay. XRD and FESEM results indicated the formation of single-phase Cu0.5Ni0.5. TEM micrographs showed that the mean particle size of powders is 20 nm. DSC results revealed that T c of mechano-thermally synthesized Cu0.5Ni0.5 is 44 °C. The MTT assay results confirmed the viability and proliferation of human bone marrow stem cells in contact with Cu0.5Ni0.5 NPs. In summary, the fabricated particles were demonstrated to have potential in low concentrations for cancer treatment applications.

  14. NiCu Alloy Nanoparticle-Loaded Carbon Nanofibers for Phenolic Biosensor Applications.

    PubMed

    Li, Dawei; Lv, Pengfei; Zhu, Jiadeng; Lu, Yao; Chen, Chen; Zhang, Xiangwu; Wei, Qufu

    2015-11-20

    NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs) were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac) and Nafion to form a novel biosensor. NiCuCNFs successfully achieved the direct electron transfer of Lac. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical properties of the biosensor. The finally prepared biosensor showed favorable electrocatalytic effects toward hydroquinone. The detection limit was 90 nM (S/N = 3), the sensitivity was 1.5 µA µM(-1), the detection linear range was 4 × 10(-7)-2.37 × 10(-6) M. In addition, this biosensor exhibited satisfactory repeatability, reproducibility, anti-interference properties and stability. Besides, the sensor achieved the detection of hydroquinone in lake water.

  15. Structural and magnetic properties of NiCuZn ferrite/SiO 2 nanocomposites

    NASA Astrophysics Data System (ADS)

    Praveena, K.; Sadhana, K.; Ramana Murthy, S.

    2011-08-01

    Ni0.53Cu0.12Zn0.35Fe2O4/SiO2 nanocomposites with different weight percentages of NiCuZn ferrite dispersed in silica matrix were prepared by microwave-hydrothermal method using tetraethylorthosilicate as a precursor of silica, and metal nitrates as precursors of NiCuZn ferrite. The structure and morphology of the composites were studied using X-ray diffraction and scanning electron microscopy. The structural changes in these samples were characterized using Fourier Transform Infrared Spectrometer in the range of 400-1500 cm-1. The bands in the range of 580-880 cm-1 show a slight increase in intensity, which could be ascribed to the enhanced interactions between the NiCuZnFe2O4 clusters and silica matrix. The effects of silica content and sintering temperature on the magnetic properties of Ni0.53Cu0.12Zn0.35Fe2O4/SiO2 nanocomposites have been studied using electron spin resonance and vibrating sample magnetometer.

  16. Tarnish resistance evaluation of experimental Pd-free Ag-Au-Pt-Cu dental alloys.

    PubMed

    Takuma, Yasuko; Shiraishi, Takanobu; Fujita, Takeshi; Hisatsune, Kunihiro

    2010-05-01

    This study evaluated the tarnish resistance of eight experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.1% Na(2)S aqueous solution at 37 degrees C. Color measurements of the plate samples were made using a computerized spectrophotometer before and after immersion in the test solution for up to 72 hours. Tarnish discoloration was evaluated using the color difference vector, DeltaE*, in the CIELAB color space. Microstructural observation of each sample through an optical microscope revealed the matrix phase as the major constituent and second-phase small grains in the matrix phase. Selective tarnish discoloration occurred in the matrix, and fractional area of the matrix to the whole surface area was influenced by the sum of Au and Ag concentrations. The DeltaE* value significantly decreased with increasing Au/(Au+Ag) atomic ratio. In conclusion, the Au/(Au+Ag) ratio in an alloy and the fractional area of the matrix were found to be primary and auxiliary factors affecting the tarnish resistance of the experimental alloys.

  17. Shock melting method to determine melting curve by molecular dynamics: Cu, Pd, and Al

    SciTech Connect

    Liu, Zhong-Li; Zhang, Xiu-Lu; Cai, Ling-Cang

    2015-09-21

    A melting simulation method, the shock melting (SM) method, is proposed and proved to be able to determine the melting curves of materials accurately and efficiently. The SM method, which is based on the multi-scale shock technique, determines melting curves by preheating and/or prepressurizing materials before shock. This strategy was extensively verified using both classical and ab initio molecular dynamics (MD). First, the SM method yielded the same satisfactory melting curve of Cu with only 360 atoms using classical MD, compared to the results from the Z-method and the two-phase coexistence method. Then, it also produced a satisfactory melting curve of Pd with only 756 atoms. Finally, the SM method combined with ab initio MD cheaply achieved a good melting curve of Al with only 180 atoms, which agrees well with the experimental data and the calculated results from other methods. It turned out that the SM method is an alternative efficient method for calculating the melting curves of materials.

  18. [Electrocatalytic reduction of nitrate from drinking water by porous titanium loaded Pd-Cu cathode].

    PubMed

    Fan, Jing-hua; Fan, Bin; Lu, Dao-qiang; Qu, Dan; Luan, Zhao-kun

    2006-06-01

    We investigated performances as well as influencing factors of electrocatalytic denitrification of a porous titanium loaded Pd-Cu (4:1) cathode, from drinking water. Up to 96.9% of NO3(-)-N may be reduced to N2 with electrocatalytic activity as 16.69 mg/ (g x h). The Nitrate reduction presented an apparent first order reaction at lower nitrate concentration, while a zero order reaction at higher nitrate concentration. Little nitrate reduction was observed when cell voltage (or current) was lower than 1.5 V (or 5 mA); the side reaction of ammonium production became noticeable if the cell voltage (or current) was higher than 4.2 V (or 30 mA). Both the activity and the selectivity were good at a neutral pH; at acidic pH, the activity increased while the selectivity decreased. Mass transfer in solution was found little effect on the reactions in the tests. Other anions such as ClO4-, HCO3-, Cl- did somewhat harms to NO3(-)-N removal with sequence of ClO4- < HCO3- < Cl-.

  19. Magnetic behavior of NiCu nanowire arrays: Compositional, geometry and temperature dependence

    SciTech Connect

    Palmero, E. M. Bran, C.; Real, R. P. del; Vázquez, M.; Magén, C.

    2014-07-21

    Arrays of Ni{sub 100−x}Cu{sub x} nanowires ranging in composition 0 ≤ x ≤ 75, diameter from 35 to 80 nm, and length from 150 nm to 28 μm have been fabricated by electrochemical co-deposition of Ni and Cu into self-ordered anodic aluminum oxide membranes. As determined by X-ray diffraction and Transmission Electron Microscopy, the crystalline structure shows fcc cubic symmetry with [111] preferred texture and preferential Ni or Cu lattice depending on the composition. Their magnetic properties such as coercivity and squareness have been determined as a function of composition and geometry in a Vibrating Sample Magnetometer in the temperature range from 10 to 290 K for applied magnetic fields parallel and perpendicular to the nanowires axis. Addition of Cu into the NiCu alloy up to 50% enhances both parallel coercivity and squareness. For the higher Cu content, these properties decrease and the magnetization easy axis becomes oriented perpendicular to the wires. In addition, coercivity and squareness increase by decreasing the diameter of nanowires which is ascribed to the increase of shape anisotropy. The temperature dependent measurements reflect a complex behavior of the magnetic anisotropy as a result of energy contributions with different evolution with temperature.

  20. Pd-M/C (M = Pd, Cu, Pt) Electrocatalysts for Oxygen Reduction Reaction in Alkaline Medium: Correlating the Electronic Structure with Activity.

    PubMed

    Castegnaro, Marcus V; Paschoalino, Waldemir J; Fernandes, Mauro R; Balke, Benjamin; M Alves, Maria C; Ticianelli, Edson A; Morais, Jonder

    2017-03-21

    The increasing global needs for clean and renewable energy have fostered the design of new and highly efficient materials for fuel cells applications. In this work, Pd-M (M = Pd, Cu, Pt) and Pt nanoparticles were prepared by a green synthesis method. The carbon-supported nanoparticles were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) in alkaline medium. A comprehensive electronic and structural characterization of these materials was achieved using X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Their electrochemical properties were investigated by cyclic voltammetry, while their activities for the ORR were characterized using steady-state polarization experiments. The results revealed that the bimetallic nanoparticles consist of highly crystalline nanoalloys with size around 5 nm, in which the charge transfer involving Pd and M atoms affects the activity of the electrocatalysts. Additionally, the samples with higher ORR activity are those whose d-band center is closer to the Fermi level.

  1. Ultrasensitive electrochemiluminescence detection of DNA based on nanoporous gold electrode and PdCu@carbon nanocrystal composites as labels.

    PubMed

    Yan, Mei; Zhang, Meng; Ge, Shenguang; Yu, Jinghua; Li, Meng; Huang, Jiadong; Liu, Su

    2012-07-21

    A sensitive electrochemiluminescence (ECL) DNA biosensor based on nanoporous gold (NPG) electrode and PdCu@carbon nanocrystals (CNCs) composites is developed. The CNCs were obtained simply by electrooxidation with abundant carboxyl groups at their surfaces. The NPG can be easily prepared by a selective dissolution of silver from silver-gold alloy in nitric acid, which has free-standing noble metal membranes with controllable three-dimensional (3D) porosity. The PdCu bimetallic nanocomposites with hierarchically hollow structures were fabricated through a simple replacement reaction using dealloyed nanoporous copper (NPC) as both a template and reducing agent. Structure characterization was obtained by means of transmission electron microscope (TEM) and scanning electron microscope (SEM) images. The PdCu@CNCs composites exhibit 6 times higher ECL intensity than the pure CNC-labeled reporter DNA. Taking advantage of dual-amplification effects of the developed probe, a limit of detection as low as 18 aM can be achieved and the assay exhibits excellent selectivity for single-mismatched DNA detection even in human serum. The proposed ECL based method should have wide applications in diagnosis of genetic diseases due to its simplicity, low cost, and high sensitivity at extremely low concentrations.

  2. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

    2015-04-01

    We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 °C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 °C, 700 °C, and 800 °C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 μm could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

  3. Competitive removal of Cu-EDTA and Ni-EDTA via microwave-enhanced Fenton oxidation with hydroxide precipitation.

    PubMed

    Lin, Qintie; Pan, Hanping; Yao, Kun; Pan, Yonggang; Long, Wei

    2015-01-01

    Ethylenediaminetetraacetic acid (EDTA) can form very stable complexes with heavy metal ions, greatly inhibiting conventional metal-removal technologies used in water treatment. Both the oxidation of EDTA and the reduction of metal ions in metal-EDTA systems via the microwave-enhanced Fenton reaction followed by hydroxide precipitation were investigated. The Cu(II)-Ni(II)-EDTA, Cu(II)-EDTA and Ni(II)-EDTA exhibited widely different decomplexation efficiencies under equivalent conditions. When the reaction reached equilibrium, the chemical oxygen demand was reduced by a microwave-enhanced Fenton reaction in different systems and the reduction order from high to low was Cu(II)-Ni(II)-EDTA ≈ Cu(II)-EDTA > Ni(II)-EDTA. The removal efficiencies of both Cu(2+) and Ni(2+) in Cu-Ni-EDTA wastewaters were much higher than those in a single heavy metal system. The degradation efficiency of EDTA in Cu-Ni-EDTA was lower than that in a single metal system. In the Cu-Ni-EDTA system, the microwave thermal degradation and the Fenton-like reaction created by Cu catalyzed H2O2 altered the EDTA degradation pathway and increased the pH of the wastewater system, conversely inhibiting residual EDTA degradation.

  4. Pressure-Free Bonding of Metallic Plates with Ni Affinity Layers Using Cu Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ishizaki, Toshitaka; Akedo, Kunio; Satoh, Toshikazu; Watanabe, Ryota

    2014-01-01

    This study investigated the pressure-free bonding of metallic plates using Cu nanoparticles capped by fatty acid and amine as the bonding material. The application of Ni layers to Cu plates prior to bonding significantly improved their adhesion to sintered Cu nanoparticles, resulting in higher strengths even without pressure compared to samples bonded using an ordinary Pb-rich solder at a similar temperature. The shear strength could be enhanced if the thickness of Ni layers was larger than 1 nm. The same effect was also observed when Al plates with Ni layers were bonded by Cu nanoparticles. In contrast, Ti, Mn, and Cr layers were found to be ineffective with regard to improving bond strength. Cu plates bonded by Cu nanoparticles capped by fatty acid and amine with different alkyl chain lengths from 6 to 18 showed an optimal strength with a length of 10, where the Cu particles were small enough to sinter effectively but not so small as to oxidize.

  5. Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

    2017-01-01

    Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.

  6. Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

    2016-10-01

    Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.

  7. Novel high-strength NiCuCoTiTa alloy with plasticity

    NASA Astrophysics Data System (ADS)

    Samal, Sumanta; Biswas, Krishanu

    2013-07-01

    The present investigation reports a novel Ni-Ti-based Ni48Cu10Co2Ti38Ta2 alloy, obtained by arc melting cum suction casting route under ultrahigh-purity Ar atmosphere. X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy (TEM) investigations reveal a microstructure consisting of nanostructured eutectic between cubic NiTi and hexagonal Ni3Ti with micron-scale NiTi and cubic Ti2Ni dendrites. Detailed TEM investigation indicates substantial reduction in the interlamellar spacing as the alloy chemistry changes from binary to quinary. The alloy shows a high compressive strength, 2 GPa, with high plasticity 13 %. Fractography surface of this new alloy reveals mixed mode of fracture. The results are discussed in light of the available literature on deformation of nanostructured eutectic with micron-sized dendrites in the microstructures.

  8. Necklace-like NiO-CuO Heterogeneous Composite Hollow Nanostructure: Preparation, Formation Mechanism and Structure Control.

    PubMed

    Xu, Shao Hui; Fei, Guang Tao; Ouyang, Hao Miao; Shang, Guo Liang; Gao, Xu Dong; Zhang, Li De

    2017-12-01

    Composite hollow nanostructure composed by transition metal oxides are promising materials in electrochemistry, catalyst chemistry and material science. In this contribution, necklace-like NiO-CuO heterogeneous composite hollow nanostructures were synthesized by annealing Ni/Cu superlattice nanowires in air. Two kinds of morphologies including CuO nanotube linked core-shell structures and CuO nanotube linked hollow structures were obtained. The structure can be tuned easily by adjusting the relative length of Cu segments in Ni/Cu superlattice nanowires and the annealing temperature. The relative diffusion amount of Cu to Ni segments was proved to be the key factor to influence the annealed sample morphology. The formation mechanism was discussed in detail based on Kirkendal effect and high temperature oxidation of alloy. We demonstrated that hollow structure or core-shell structure is related to whether the oxidation exists only in external sites or co-exists in external and internal sites during annealing.

  9. The As-Cu-Ni System: A Chemical Thermodynamic Model for Ancient Recycling

    NASA Astrophysics Data System (ADS)

    Sabatini, Benjamin J.

    2015-12-01

    This article is the first thermodynamically reasoned ancient metal system assessment intended for use by archaeologists and archaeometallurgists to aid in the interpretation of remelted/recycled copper alloys composed of arsenic and copper, and arsenic, copper, and nickel. These models are meant to fulfill two main purposes: first, to be applied toward the identification of progressive and regressive temporal changes in artifact chemistry that would have occurred due to recycling, and second, to provide thermodynamic insight into why such metal combinations existed in antiquity. Built on well-established thermodynamics, these models were created using a combination of custom-written software and published binary thermodynamic systems data adjusted to within the boundary conditions of 1200°C and 1 atm. Using these parameters, the behavior of each element and their likelihood of loss in the binaries As-Cu, As-Ni, Cu-Ni, and ternary As-Cu-Ni, systems, under assumed ancient furnace conditions, was determined.

  10. Geochemical partitioning of Cu and Ni in mangrove sediments: relationships with their bioavailability.

    PubMed

    Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita

    2015-04-15

    Sequential extraction study was performed to determine the concentrations of non-residual metal-complexes in the mangrove sediments from the Divar Island, (west coast of India). Accumulation of metal in the mangrove roots (from the same location) was determined and used as an indicator of bioavailability of metal. An attempt was made to establish a mechanistic linkage between the non-residual metal complexes and their bioavailability in the mangrove system. The non-residual fractions of Cu and Ni were mainly associated with Fe/Mn oxyhydroxide and organic phases in the sediments. A part of these metal fractions were bioavailable in the system. These two phases were the major controlling factors for Ni speciation and their bioavailability in the studied sediments. However, Cu was found to interact more strongly with the organic phases than Ni in the mangrove sediments. Organic phases in the mangrove sediments acted as buffer to control the speciation and bioavailability of Cu in the system.

  11. Ni, Cu, Au, and platinum-group element contents of sulphides associated with intraplate magmatism: A synthesis

    USGS Publications Warehouse

    Barnes, S.-J.; Zientek, M.L.; Severson, M.J.

    1997-01-01

    The tectonic setting of intraplate magmas, typically a plume intersecting a rift, is ideal for the development of Ni - Cu - platinum-group element-bearing sulphides. The plume transports metal-rich magmas close to the mantle - crust boundary. The interaction of the rift and plume permits rapid transport of the magma into the crust, thus ensuring that no sulphides are lost from the magma en route to the crust. The rift may contain sediments which could provide the sulphur necessary to bring about sulphide saturation in the magmas. The plume provides large volumes of mafic magma; thus any sulphides that form can collect metals from a large volume of magma and consequently the sulphides will be metal rich. The large volume of magma provides sufficient heat to release large quantities of S from the crust, thus providing sufficient S to form a large sulphide deposit. The composition of the sulphides varies on a number of scales: (i) there is a variation between geographic areas, in which sulphides from the Noril'sk - Talnakh area are the richest in metals and those from the Muskox intrusion are poorest in metals; (ii) there is a variation between textural types of sulphides, in which disseminated sulphides are generally richer in metals than the associated massive and matrix sulphides; and (iii) the massive and matrix sulphides show a much wider range of compositions than the disseminated sulphides, and on the basis of their Ni/Cu ratio the massive and matrix sulphides can be divided into Cu rich and Fe rich. The Cu-rich sulphides are also enriched in Pt, Pd, and Au; in contrast, the Fe-rich sulphides are enriched in Fe, Os, Ir, Ru, and Rh. Nickel concentrations are similar in both. Differences in the composition between the sulphides from different areas may be attributed to a combination of differences in composition of the silicate magma from which the sulphides segregated and differences in the ratio of silicate to sulphide liquid (R factors). The higher metal

  12. Facile synthesis of Pd-based bimetallic nanocrystals and their application as catalysts for methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Xi, Pinxian; Cao, Yang; Yang, Fengchun; Ma, Cai; Chen, Fengjuan; Yu, Sha; Wang, Shuai; Zeng, Zhengzhi; Zhang, Xin

    2013-06-01

    We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations.We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00912b

  13. A series of M(II)Cu(II)3 stars (M = Mn, Ni, Cu, Zn) exhibiting unusual magnetic properties.

    PubMed

    Mondal, Suraj; Mandal, Shuvankar; Carrella, Luca; Jana, Arpita; Fleck, Michel; Köhn, Andreas; Rentschler, Eva; Mohanta, Sasankasekhar

    2015-01-05

    The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two μ2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. The title compounds are rare or sole examples of stars having these metal-ion combinations. In the cases of 1, 3, and 4, the four metal ions form a centered isosceles triangle, while the four metal ions in 2 form a centered equilateral triangle. Both the variable-temperature magnetic susceptibility and variable-field magnetization (at 2-10 K) of 1-3 have been measured and simulated contemporaneously. While the Mn(II)Cu(II)3 compound 1 exhibits ferromagnetic interaction with J = 1.02 cm(-1), the Ni(II)Cu(II)3 compound 2 and Cu(II)Cu(II)3 compound 3 exhibit antiferromagnetic interaction with J = -3.53 and -35.5 cm(-1), respectively. Variable-temperature magnetic susceptibility data of the Zn(II)Cu(II)3 compound 4 indicate very weak antiferromagnetic interaction of -1.4 cm(-1), as expected. On the basis of known correlations, the magnetic properties of 1-3 are unusual; it seems that ferromagnetic interaction in 1 and weak/moderate antiferromagnetic interaction in 2 and 3 are possibly related to the distorted coordination environment of the peripheral copper(II) centers (intermediate between square-planar and tetrahedral). DFT calculations have been done to elucidate the magnetic properties. The DFT-computed J values are quantitatively (for 1) or qualitatively (for 2 and 3) matched

  14. Effect of additive metals, Sn, Ga, and In in Ag-Pd-Au-Cu alloys on initial bond strength of 4-META adhesive cement to these alloys.

    PubMed

    Goto, Shin-ichi; Churnjitapirom, Pornkiat; Miyagawa, Yukio; Ogura, Hideo

    2008-09-01

    The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au-Cu alloys consisted of 20%, 30% or 40% Pd, and 10%, 15% or 20% Cu, 20% Au, and Ag as balance. Besides, additive metals (Sn, Ga, and In) of 2% and 4% were added to these compositions. The addition of three additives, in general, increased the initial bond strength of the cement in comparison to the mother compositions (0% additives), although the degrees of effectiveness of the three additives were different and varied with their contents. Among these additives, a remarkable increase in bond strength was observed with the addition of In. The increase in Cu content, in many cases, resulted in an increase in bond strength at high Pd contents (30% and 40%), but a decrease at low Pd content (20%) in some cases. The positive effects of the three additives and Cu could be due to the formation of a suitable oxide layer for strong bonding with 4-META.

  15. Tensile strength of thermomechanically processed Cu-9Ni-6Sn alloys

    SciTech Connect

    Rhu, J.C.; Kim, S.S.; Jung, Y.C.; Han, S.Z.; Kim, C.J.

    1999-10-01

    The tensile properties of Cu-9Ni-6Sn alloys with different swaging amounts of 64, 77, and 95 pct, either solutionized and aged (S/A), were examined as a function of aging time. It was found that the aging response of Cu-9Ni-6Sn alloys varied greatly depending on the prior solution heat treatment before aging and/or different swaging amounts. The swaged S/A Cu-9Ni-6Sn alloys showed a multistage increase in tensile strength with respect to aging time, probably due to the sequential occurrence of spinodal decomposition, formation of metastable {gamma}{center{underscore}dot} precipitates, and recrystallization. The effect of different swaging amounts, ranging from 64 to 95 pct, was minimal on the aging response of S/A specimens. The prior cold working, however, appeared to favor the spinodal strengthening, comparing unswaged and swaged S/A Cu-9Ni-6Sn alloys. In 95 pct swaged D/A Cu-9Ni-6Sn alloys, the level of hardening was much less sensitive to aging time. A complex interaction between the reduction in dislocation density, the formation of equilibrium precipitates, and the reduction of Sn content in the Sn-rich segregates during an aging process is believed to be responsible for such a lean sensitivity. The increases in tensile strength of 64 and 77 pct swaged D/A Cu-9Ni-6Sn alloys were found to be much steeper than that in the 95 pct counterparts in the early and intermediate stages of aging, which is believed to be related to the relative contribution from work hardening and precipitation hardening to the strength level of D/A specimens.

  16. Facile Synthesis of Pt-/Pd-MODIFIED NiTi Electrode with Superior Electro-Catalytic Activities Toward Methanol, Ethanol and Ethylene Glycol Oxidation

    NASA Astrophysics Data System (ADS)

    He, Yongwei; Wang, Mei; Ma, Zizai; Li, Ruixue; Kundu, Manab; Ma, Guanshui; Lin, Naiming; Tang, Bin; Wang, Xiaoguang

    2016-11-01

    Surface functional modification of NiTi electrode with noble Pt and Pd metal has been successfully carried out by simple and cost effective electro-spark deposition technique (ESD). Thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and cyclic voltammetry (CV) have been carried out in order to investigate the structure, morphology, chemical composition and electrochemical behavior of the modified electrode surface. The modified Pt/NiTi and Pd/NiTi electrode surface exhibit a circular splash pattern with a tiny amount of Pt (˜5.30 at.% Pt) and Pd (˜5.71 at.% Pd) existence. The electrochemical results demonstrate that the Pt/NiTi and Pd/NiTi electrode possess an improved electro-catalytic activities toward methanol (MeOH), ethanol (EtOH) and ethylene glycol (EG) oxidation in alkaline media in comparison with the bare NiTi electrode. In acidic environments, the Pt/NiTi electrode exhibits even much better catalytic activities than the pure Pt sheet electrode due to the bi-functional mechanism. In the same way, the electro-catalytic activity of the modified Pd/NiTi electrode is also slightly larger than that of the pure Pd sheet electrode in alkaline environment. The electro-spark surface modification approach is rapid and environmentally-benign, being attractive to widen the application of traditional surface modification technique in the field of material surface/interface design and functionalization.

  17. Synthesis and characterization of NiFe{sub 2}O{sub 4}–Pd magnetically recyclable catalyst for hydrogenation reaction

    SciTech Connect

    Karaoğlu, E.; Özel, U.; Caner, C.; Baykal, A.; Summak, M.M.; Sözeri, H.

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Novel superparamagnetic NiFe{sub 2}O{sub 4}–Pd magnetically recyclable catalyst was fabricated through co-precipitation. ► It could be reused several times without significant loss in catalytic activity for hydrogenation reaction. ► No further modification of the NiFe{sub 2}O{sub 4}–Pd magnetically recyclable catalyst is necessary for utilization as catalyst. -- Abstract: Herein we report the fabrication and characterization magnetically recyclable catalysts of NiFe{sub 2}O{sub 4}–Pd nanocomposite as highly effective catalysts for reduction reactions in liquid phase. The reduction Pd{sup 2+} was accomplished with polyethylene glycol 400 (PEG-400) instead of sodium borohydride (NaBH{sub 4}) and NiFe{sub 2}O{sub 4} nanoparticles was prepared by sonochemically using FeCI{sub 3}·6H{sub 2}O and NiCl{sub 2}. The chemical characterization of the product was done with X-ray diffractometry, Infrared spectroscopy, transmission electron microscopy, UV–Vis spectroscopy, thermal gravimetry and inductively coupled plasma. Thus formed NiFe{sub 2}O{sub 4}–Pd MRCs showed a very high activity in reduction reactions of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase. It was found out that the catalytic activity of NiFe{sub 2}O{sub 4}–Pd MRCs on the reduction of 4-nitro aniline and 1,3-dinitrobenzene in liquid phase are between 99–93% and 98–93%, respectively. Magnetic character of this system allowed recovery and multiple use without significant loss of its catalytic activity. It is found that NiFe{sub 2}O{sub 4}–Pd MRCs showed very efficient catalytic activity and multiple usability.

  18. Effect of Cu doping on the resistive switching of NiO thin films

    SciTech Connect

    Li, Jian-Chang Hou, Xue-Yan; Cao, Qing

    2014-04-28

    Bipolar resistive switching is observed in the GaIn/Cu:NiO film/ITO device with active layer deposited by sol-gel spin-coating. The first-principles calculations indicate that Cu dopants with valence of +1 are located at the substitutional Ni sites rather than the interstitial ones. Cu doping introduces more oxygen vacancies in the film and increases the carrier mobility, however, excessive Cu dopants may assemble at the grain boundary resulting in larger set voltage. Current–voltage measurements indicate that the trap charge limited and space charge limited conduction dominate the high resistance state, while the low resistance state follows the Ohmic mechanism. The switching is attributed to the formation/rupture of oxygen vacancy filaments.

  19. Equation of State of an AlCoCrCuFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Li, Gong; Xiao, Daihong; Yu, Pengfei; Zhang, Lijun; Liaw, Peter K.; Li, Yanchun; Liu, Riping

    2015-08-01

    The pressure-volume (P-V) relationship of the AlCoCrCuFeNi high-entropy alloy (HEA) at room temperature has been studied using in situ high-pressure energy-dispersive x-ray diffraction with synchrotron radiation at high pressures. The equation of state of the AlCoCrCuFeNi HEA is determined by the calculation of the radial distribution function. The experimental results indicate that the HEA keeps a stable face-centered-cubic + body-centered-cubic structure in the experimental pressure range from 0 GPa to 24 GPa.

  20. Oxygen reduction on Ni, Ag, and Cu meniscus electrodes in molten carbonate

    SciTech Connect

    Ogura, Hiroyuki; Shirogami, Tamotsu

    1994-12-31

    The oxygen reduction pathways in molten carbonates have been investigated by analyzing the charge transfer resistances of the i-V curves on the meniscus electrodes of Ni, Cu, and Ag screens at 550 C. The electrochemical reduction pathways of oxygen at the meniscus electrode were found to be different depending on the electrode materials. For the Ni meniscus electrode system, the reactive material of charge transfer is the lithium doped nickel oxide, for the Ag system that is the silver oxide ion, and for the Cu system that is peroxide ion, respectively.

  1. First-principles investigation of structural and magnetic disorder in CuNiMnAl and CuNiMnSn Heusler alloys

    NASA Astrophysics Data System (ADS)

    Aron-Dine, S.; Pomrehn, G. S.; Pribram-Jones, A.; Laws, K. J.; Bassman, L.

    2017-01-01

    Two quaternary Heusler alloys, equiatomic CuNiMnAl and CuNiMnSn, are studied using density functional theory to understand their tendency for atomic disorder on the lattice and the magnetic effects of disorder. Disordered structures with antisite defects of atoms of the same and different sublattices are considered, with the level of atomic disorder ranging from 3% to 25%. Formation energies and magnetic moments are calculated relative to the ordered ground state and combined with a simple thermodynamical model to estimate temperature effects. We predict the relative levels of disordering in the two equiatomic alloys with good correlation to experimental x-ray diffraction results. The effect of swaps involving Mn is also discussed.

  2. Microstructure and Corrosion Resistance of Electrodeposited Ni-Cu-Mo Alloy Coatings

    NASA Astrophysics Data System (ADS)

    Meng, Xinjing; Shi, Xi; Zhong, Qingdong; Shu, Mingyong; Xu, Guanquan

    2016-11-01

    This paper deals with the electrodeposition of Ni-Cu-Mo ternary alloy coatings on low-carbon steel substrate from an aqueous citrate sulfate bath. The structures and microstructure of coatings were characterized by scanning electron microscopy and x-ray diffractometry. The corrosion resistance of coatings was investigated by potentiodynamic polarization (Tafel) and electrochemical impedance spectroscopy techniques. The results show that the Ni-Cu-Mo coatings are mainly composed of fcc-Ni phase and a small amount of NiCu phase. Ni-Cu-Mo coatings exhibit a nodular surface morphology, and the roughness of electroplated coating increases with the increasing of Na2MoO4·2H2O in the bath. The corrosion performance of the coatings is significantly affected by the Mo content of the alloy coating and their surface morphology. The coating prepared in bath containing 40 g/L Na2MoO4·2H2O has the highest corrosion resistance in 3.5 wt.% NaCl solution, while that prepared in bath containing 60 g/L (or more) Na2MoO4·2H2O shows a lower corrosion resistance due to the presence of microcracks on the coating surface.

  3. Electrodeposition mechanism and characterization of Ni-Cu alloy coatings from a eutectic-based ionic liquid

    NASA Astrophysics Data System (ADS)

    Wang, Shaohua; Guo, Xingwu; Yang, Haiyan; Dai, JiChun; Zhu, Rongyu; Gong, Jia; Peng, Liming; Ding, Wenjiang

    2014-01-01

    The electrodeposition mechanism, microstructures and corrosion resistances of Ni-Cu alloy coatings on Cu substrate were investigated in a choline chloride-urea (1:2 molar ratio) eutectic-based ionic liquid (1:2 ChCl-urea IL) containing nickel and copper chlorides. Cyclic voltammetry showed that the onset reduction potentials for Cu (∼-0.32 V) and for Ni (∼-0.47 V) were close to each other, indicating that Ni-Cu co-deposition could be easily achieved in the absence of complexing agent which was indispensable in aqueous plating electrolyte. Chronoamperometric investigations revealed that Ni-Cu deposits followed the three-dimensional instantaneous nucleation/growth mechanism, thus producing a solid solution. The compositions, microstructures and corrosion resistances of Ni-Cu alloy coatings were significantly dependent on the deposition current densities. Ni-Cu alloy coatings were α-Ni(Cu) solid solutions, and the coating containing ∼17.6 at.% Cu exhibited the best corrosion resistance because of its dense and crack-free structure.

  4. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application

    PubMed Central

    Li, H. F.; Qiu, K. J.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-01-01

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections. PMID:27897182

  5. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application.

    PubMed

    Li, H F; Qiu, K J; Zhou, F Y; Li, L; Zheng, Y F

    2016-11-29

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections.

  6. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application

    NASA Astrophysics Data System (ADS)

    Li, H. F.; Qiu, K. J.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-11-01

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections.

  7. Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy

    SciTech Connect

    Asghar, Z.

    2014-02-15

    The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an α-Al matrix. The strength at room temperature and at 300°C is studied as a function of solution treatment time at 490°C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300°C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300°C. - Highlights: • The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. • An imaging analysis procedure to segment phases with similar contrasts is presented. • 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. • AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.

  8. Au- and Pd-modified porous Co film supported on Ni foam substrate as the high performance catalysts for H2O2 electroreduction

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Cheng, Kui; Ye, Ke; Xiao, Xue; Guo, Fen; Wang, Guiling; Cao, Dianxue

    2014-07-01

    Non-noble metal film electrode (Co/Ni foam) modified with noble metals (Au and Pd) has been reported. Highly porous Co film is firstly prepared electrochemically on the commercial Ni foam substrate and in turn serves as a hard template and a redox inducer for modification by spontaneous deposition of Au or Pd. The electrodes (Au-modified Co/Ni foam and Pd-modified Co/Ni foam) are characterized by scanning electron microscopy equipped with energy dispersive X-ray spectrometer, and X-ray diffractometer. The catalytic performance of the 3D porous electrodes is evaluated by voltammetry and chronoamperometry. Results reveal that Au- and Pd-modified Co/Ni foam exhibit excellent catalytic performance and good stability for H2O2 electroreduction compared with Au and Pd particles supported on Ni foam, benefitting from the unique 3D structure which can ensure high utilization of catalyst and quick releases of gas bubbles produced by H2O2 decomposition from the electrode.

  9. Low-Temperature Sintering and Electromagnetic Properties of NiCuZn/CaTiO3 Composites

    NASA Astrophysics Data System (ADS)

    Yang, Haibo; Yang, Yanyan; Lin, Ying; Zhu, Jianfeng; Wang, Fen

    2012-04-01

    Dense CaTiO3/Ni0.37Cu0.20Zn0.43Fe1.92O3.88 (CTO/NiCuZn) composites were prepared by the conventional solid-state reaction method and sintered at 950°C. The phase compositions and surface morphologies of the composites were investigated using x-ray diffraction and scanning electron microscopy, respectively. The dielectric and magnetic properties of the composites were also investigated. The results show that the CTO/NiCuZn composites possess high dielectric constants and permeabilities, which can be used in high-frequency communications for capacitor-inductor integrating devices such as electromagnetic interference filters and antennas. With increasing NiCuZn concentration, the permeabilities of the CTO/NiCuZn composites increase, while the dielectric constants and cutoff frequencies decrease.

  10. Wetting and interface phenomena in the molten Sn/CuFeNiCoCr high-entropy alloy system

    NASA Astrophysics Data System (ADS)

    Ma, G. F.; Li, Z. K.; Ye, H.; He, C. L.; Zhang, H. F.; Hu, Z. Q.

    2015-11-01

    The wetting behavior and the interfacial characteristics of the molten Sn on a CuFeNiCoCr high-entropy alloy (HEA) substrate were investigated by the sessile drop method. Oxidation of the CuCoNiFeCr HEA surface inhibited the interaction between the molten Sn and the CuCoNiFeCr HEA substrate, leading to a very poor wetting at 573 K, 623 K and 673 K. However, the equilibrium contact angle decreased monotonously with the temperature increasing in the temperature range of 673-923 K. Moreover, the interfacial microstructure depended on temperature. An intermetallic compound existed at the interface between the molten Sn and the CuFeNiCoCr HEA substrate, and the interface thickness varied with the wetting temperature. The wetting process of the molten Sn on the CuFeNiCoCr HEA substrate consisted of three stages according to the wetting temperature.

  11. Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics

    PubMed Central

    Gravina, Marco Abdo; Canavarro, Cristiane; Elias, Carlos Nelson; Chaves, Maria das Graças Afonso Miranda; Brunharo, Ione Helena Vieira Portella; Quintão, Cátia Cardoso Abdo

    2014-01-01

    Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27ºC and 35ºC, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27ºC and 35ºC ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27ºC and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35ºC wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35ºC wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region. PMID:24713562

  12. The effect of intermetallic compound morphology on Cu diffusion in Sn-Ag and Sn-Pb solder bump on the Ni/Cu Under-bump metallization

    NASA Astrophysics Data System (ADS)

    Jang, Guh-Yaw; Duh, Jenq-Gong

    2005-01-01

    The eutectic Sn-Ag solder alloy is one of the candidates for the Pb-free solder, and Sn-Pb solder alloys are still widely used in today’s electronic packages. In this tudy, the interfacial reaction in the eutectic Sn-Ag and Sn-Pb solder joints was investigated with an assembly of a solder/Ni/Cu/Ti/Si3N4/Si multilayer structures. In the Sn-3.5Ag solder joints reflowed at 260°C, only the (Ni1-x,Cux)3Sn4 intermetallic compound (IMC) formed at the solder/Ni interface. For the Sn-37Pb solder reflowed at 225°C for one to ten cycles, only the (Ni1-x,Cux)3Sn4 IMC formed between the solder and the Ni/Cu under-bump metallization (UBM). Nevertheless, the (Cu1-y,Niy)6Sn5 IMC was observed in joints reflowed at 245°C after five cycles and at 265°C after three cycles. With the aid of microstructure evolution, quantitative analysis, and elemental distribution between the solder and Ni/Cu UBM, it was revealed that Cu content in the solder near the solder/IMC interface played an important role in the formation of the (Cu1-y,Niy)6Sn5 IMC. In addition, the diffusion behavior of Cu in eutectic Sn-Ag and Sn-Pb solders with the Ni/Cu UBM were probed and discussed. The atomic flux of Cu diffused through Ni was evaluated by detailed quantitative analysis in an electron probe microanalyzer (EPMA). During reflow, the atomic flux of Cu was on the order of 1016-1017 atoms/cm2sec in both the eutectic Sn-Ag and Sn-Pb systems.

  13. Characterization of Cu buffer layers for growth of L1{sub 0}-FeNi thin films

    SciTech Connect

    Mizuguchi, M.; Sekiya, S.; Takanashi, K.

    2010-05-15

    A Cu(001) layer was fabricated on a Au(001) layer to investigate the use of Cu as a buffer layer for growing L1{sub 0}-FeNi thin films. The epitaxial growth of a Cu buffer layer was observed using reflection high-energy electron diffraction. The flatness of the layer improved drastically with an increase in the substrate temperature although the layer was an alloy (AuCu{sub 3}). An FeNi thin film was epitaxially grown on the AuCu{sub 3} buffer layer by alternate monatomic layer deposition and the formation of an L1{sub 0}-FeNi ordered alloy was expected. The AuCu{sub 3} buffer layer is thus a promising candidate material for the growth of L1{sub 0}-FeNi thin films.

  14. Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.

    PubMed

    Colić, Miodrag; Rudolf, Rebeka; Stamenković, Dragoslav; Anzel, Ivan; Vucević, Dragana; Jenko, Monika; Lazić, Vojkan; Lojen, Gorazd

    2010-01-01

    Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but their biomedical application is still limited. The aim of this work was to compare the microstructure, corrosion and cytotoxicity in vitro of a Cu-Al-Ni SMA. Rapidly solidified (RS) thin ribbons, manufactured via melt spinning, were used for the tests. The control alloy was a permanent mould casting of the same composition, but without shape memory effect. The results show that RS ribbons are significantly more resistant to corrosion compared with the control alloy, as judged by the lesser release of Cu and Ni into the conditioning medium. These results correlate with the finding that RS ribbons were not cytotoxic to L929 mouse fibroblasts and rat thymocytes. In addition, the RS ribbon conditioning medium inhibited cellular proliferation and IL-2 production by activated rat splenocytes to a much lesser extent. The inhibitory effects were almost completely abolished by conditioning the RS ribbons in culture medium for 4 weeks. Microstructural analysis showed that RS ribbons are martensitic, with boron particles as a minor phase. In contrast, the control Cu-Al-Ni alloy had a complex multiphase microstructure. Examination of the alloy surfaces after conditioning by energy dispersive X-ray and Auger electron spectroscopy showed the formation of Cu and Al oxide layers and confirmed that the metals in RS ribbons are less susceptible to oxidation and corrosion compared with the control alloy. In conclusion, these results suggest that rapid solidification significantly improves the corrosion stability and biocompatibility in vitro of Cu-Al-Ni SMA ribbons.

  15. Dephasing of conduction electrons by magnetic impurities in Cu/Ni and Cu/Cr samples: Influence of spin-glass transition on the superconducting proximity effect

    NASA Astrophysics Data System (ADS)

    Sosnin, I.; Nugent, P.; Zou, J.; Petrashov, V. T.; Volkov, A. F.

    2006-07-01

    The dependence of the superconducting proximity effect on the amount of magnetic impurities in the normal part of Andreev interferometers has been studied experimentally. The dephasing rates obtained from fitting experimental data to quasiclassical theory of the proximity effect are consistent with the spin flip scattering from Cr impurities forming a local moment in the Cu host. In contrast, Ni impurities do not form a local moment in Cu and as a result there is no extra dephasing from Ni as long as Cu/Ni alloy remain paramagnetic.

  16. Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Shan; Cao, Fahe; Chang, Linrong; Zheng, JunJun; Zhang, Zhao; Zhang, Jianqing; Cao, Chunan

    2011-08-01

    High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density ( Icorr) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated.

  17. Hydrogen Induced Abrupt Structural Expansion at High Temperatures of a Ni32Nb28Zr30Cu10 Membrane for H2 Purification

    PubMed Central

    Palumbo, Oriele; Trequattrini, Francesco; Hulyalkar, Madhura; Sarker, Suchismita; Pal, Narendra; Chandra, Dhanesh; Flanagan, Ted; Dolan, Michael; Paolone, Annalisa

    2016-01-01

    Ni-Nb-Zr amorphous membranes, prepared by melt-spinning, show great potential for replacing crystalline Pd-based materials in the field of hydrogen purification to an ultrapure grade (>99.999%). In this study, we investigate the temperature evolution of the structure of an amorphous ribbon with the composition Ni32Nb28Zr30Cu10 (expressed in atom %) by means of XRD and DTA measurements. An abrupt structural expansion is induced between 240 and 300 °C by hydrogenation. This structural modification deeply modifies the hydrogen sorption properties of the membrane, which indeed shows a strong reduction of the hydrogen capacity above 270 °C. PMID:27879641

  18. Elevated Temperature Creep Properties of Conventional 50Au-50Cu and 47Au 50Cu-3Ni Braze Alloys

    SciTech Connect

    STEPHENS JR.,JOHN J.; SCHMALE,DAVID T.

    2000-12-18

    The elevated temperature creep properties of the 50Au-50Cu wt% and 47Au-50Cu-3Ni braze alloys have been evaluated over the temperature range 250-850 C. At elevated temperatures, i.e., 450-850 C, both alloys were tested in the annealed condition (2 hrs. 750 C/water quenched). The minimum strain rate properties over this temperature range are well fit by the Garofalo sinh equation. At lower temperatures (250 and 350 C), power law equations were found to characterize the data for both alloys. For samples held long periods of time at 375 C (96 hrs.) and slowly cooled to room temperature, an ordering reaction was observed. For the case of the 50Au-50Cu braze alloy, the stress necessary to reach the same, strain rate increased by about 15% above the baseline data. The limited data for ordered 47Au-50Cu-3Ni alloy reflected a,smaller strength increase. However, the sluggishness of this ordering reaction in both alloys does not appear to pose a problem for braze joints cooled at reasonable rates following brazing.

  19. Colloidal synthesis of Cu-ZnO and Cu@CuNi-ZnO hybrid nanocrystals with controlled morphologies and multifunctional properties

    NASA Astrophysics Data System (ADS)

    Zeng, Deqian; Gong, Pingyun; Chen, Yuanzhi; Zhang, Qinfu; Xie, Qingshui; Peng, Dong-Liang

    2016-06-01

    Metal-semiconductor hybrid nanocrystals have received extensive attention owing to their multiple functionalities which can find wide technological applications. The utilization of low-cost non-noble metals to construct novel metal-semiconductor hybrid nanocrystals is important and meaningful for their large-scale applications. In this study, a facile solution approach is developed for the synthesis of Cu-ZnO hybrid nanocrystals with well-controlled morphologies, including nanomultipods, core-shell nanoparticles, nanopyramids and core-shell nanowires. In the synthetic strategy, Cu nanocrystals formed in situ serve as seeds for the heterogeneous nucleation and growth of ZnO, and it eventually forms various Cu-ZnO hetero-nanostructures under different reaction conditions. These hybrid nanocrystals possess well-defined and stable heterostructure junctions. The ultraviolet-visible-near infrared spectra reveal morphology-dependent surface plasmon resonance absorption of Cu and the band gap absorption of ZnO. Furthermore, we construct a novel Cu@CuNi-ZnO ternary hetero-nanostructure by incorporating the magnetic metal Ni into the pre-synthesized colloidal Cu nanocrystals. Such hybrid nanocrystals possess a magnetic Cu-Ni intermediate layer between the ZnO shell and the Cu core, and exhibit ferromagnetic/superparamagnetic properties which expand their functionalities. Finally, enhanced photocatalytic activities are observed in the as-prepared non-noble metal-ZnO hybrid nanocrystals. This study not only provides an economical way to prepare high-quality morphology-controlled Cu-ZnO hybrid nanocrystals for potential applications in the fields of photocatalysis and photovoltaic devices, but also opens up new opportunities in designing ternary non-noble metal-semiconductor hybrid nanocrystals with multifunctionalities.Metal-semiconductor hybrid nanocrystals have received extensive attention owing to their multiple functionalities which can find wide technological applications

  20. Efficient addition of alcohols, amines and phenol to unactivated alkenes by Au(III) or Pd(II) stabilized by CuCl2.

    PubMed

    Zhang, Xin; Corma, Avelino

    2008-01-21

    The nucleophilic addition of alcohols, amines and phenol to unactivated alkenes catalyzed by cationic gold and palladium becomes limited due to the fast reduction into metallic gold under reaction conditions. The presence of CuCl2 retards the reduction of Au(III) and Pd", strongly increasing the turnover number of gold and palladium catalysts. It is shown that new Au(III)-CuCl2 and Pd(II)-CuCl2 catalysts are active and selective for the nucleophilic addition of alcohols, amines and phenol to unactivated alkenes.

  1. Cu/Pd-Catalyzed, Three-Component Click Reaction of Azide, Alkyne, and Aryl Halide: One-Pot Strategy toward Trisubstituted Triazoles.

    PubMed

    Wei, Fang; Li, Haoyu; Song, Chuanling; Ma, Yudao; Zhou, Ling; Tung, Chen-Ho; Xu, Zhenghu

    2015-06-05

    A Cu/Pd-catalyzed, three-component click reaction of azide, alkyne, and aryl halide has been developed. By using this Cu/Pd transmetalation relay catalysis, a variety of 1,4,5-trisubstituted 1,2,3-triazoles were quickly assembled in one step in high yields with complete regioselectivity, just like assembling Lego bricks. Notably, different from the well-established CuAAC click reactions only working on terminal alkynes, this reaction offers an alternative solution for the problem of the click reaction of internal alkynes.

  2. Preparation of SmNi5 and Sm(Ni,T)5 [T=Co,Fe] ordered alloy thin films on Cu(111) underlayers

    NASA Astrophysics Data System (ADS)

    Ohtake, Mitsuru; Yabuhara, Osamu; Nukaga, Yuri; Kirino, Fumiyoshi; Futamoto, Masaaki

    2010-05-01

    SmNi5 and Sm(Ni,T)5 [T =Co,Fe] epitaxial thin films with the c-axis perpendicular to the substrate surface are successfully prepared on Cu underlayers heteroepitaxially grown on MgO(111) single-crystal substrates. The nucleation behavior of SmNi5 and Sm(Ni,T)5 crystals on Cu(111) underlayers were investigated. The SmNi5 and the Sm(Ni,Co)5 films consist of two types of domains whose orientations are rotated around the film normal by 30° each other, whereas the Sm(Ni,Fe)5 film is a single crystal. The nucleation and the domain volume ratio seem to be controllable by adjusting the kind and the composition of transition metal elements.

  3. Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

    2015-02-01

    Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 °C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

  4. Comparative study on hydrogenation of propanal on Ni(111) and Cu(111) from density functional theory

    NASA Astrophysics Data System (ADS)

    An, Wei; Men, Yong; Wang, Jinguo

    2017-02-01

    Using propanal as a probe molecule, we have comparatively investigated hydrogenation of carbonyl (Cdbnd O) in short carbon-chain aldehyde on Ni(111) and Cu(111) by means of periodic density functional theory. Our focus is in particular on the differentiation of reaction route in sequential hydrogenation on Ni(111) and Cu(111) following Langmuir-Hinshelwood mechanism. Strong binding with alkoxy intermediates has great impact on altering reaction pathways on the two surfaces, where hydroxyl route via 1-hydroxyl propyl intermediate is dominant on Ni(111), but alkoxy route via propoxyl intermediate is more likely on Cu(111) due to a higher activiation barrier of initial hydrogenation in hydroxyl route. In comparison, hydrogenation of carbonyl on Ni(111) is kinetically much faster than that on Cu(111) as a result of much lower activation barrier in rate-determining step (i.e., 13.2 vs 26.8 kcal/mol) of most favorable reaction pathways. Furthermore, the discrepancy in calculated and experimental barriers can be well explained by using the concept of H-tunneling effect on bond forming with H atoms during sequential hydrogenation. The different features of electronic structure exhibited by the two metal surfaces provide insight into their catalytic behaviors.

  5. Dendritic Ni(Cu)-polypyrrole hybrid films for a pseudo-capacitor.

    PubMed

    Choi, Bit Na; Chun, Woo Won; Qian, Aniu; Lee, So Jeong; Chung, Chan-Hwa

    2015-11-28

    Dendritic Ni(Cu)-polypyrrole hybrid films are fabricated for a pseudo-capacitor in a unique morphology using two simple methods: electro-deposition and electrochemical de-alloying. Three-dimensional structures of porous dendrites are prepared by electro-deposition within the hydrogen evolution reaction (HER) at a high cathodic potential; the high-surface-area structure provides sufficient redox reactions between the electrodes and the electrolyte. The dependence of the active-layer thickness on the super-capacitor performance is also investigated, and the 60 μm-thick Ni(Cu)PPy hybrid electrode presents the highest performance of 659.52 F g(-1) at the scan rate of 5 mV s(-1). In the thicker layers, the specific capacitance became smaller due to the diffusion limitation of the ions in an electrolyte. The polypyrrole-hybridization on the porous dendritic Ni(Cu) electrode provides superior specific capacitance and excellent cycling stability due to the improvement in electric conductivity by the addition of conducting polypyrrole in the matrices of the dendritic nano-porous Ni(Cu) layer and the synergistic effect of composite materials.

  6. Positron annihilation process in Ni/sub c/Cu/sub 1-c/ alloys

    SciTech Connect

    Szotek, Z.; Gyorffy, B.L.; Stocks, G.M.; Temmerman, W.M.

    1982-01-01

    New, accurate, calculations of the electron momentum distribution function for the Cu/sub 60/Ni/sub 40/ random solid solution are presented and the role played by the positron wavefunction in determining the Angular Correlation of the Annihilation Radiation (ACAR) is discussed in quantitative terms.

  7. The vibrational spectra of the Ni(II) and Cu(II) complexes with oxamic hydrazide

    NASA Astrophysics Data System (ADS)

    Quaeyhaegens, Frank; Hofmans, Hendrik; Desseyn, H. O.

    The infrared-, Raman- and u.v./vis spectra as well as the thermal analysis ofthe Ni(II)and Cu(II) complexes with oxamic hydrazide (H 2NCOCONHNH 2) are discussed. We assume 2/1 planar complexes and a coordination via the four amide nitrogen atoms as visualised in Fig. 1.

  8. Magnetic properties of the Ni-Cu-Zn system doped with magnesium oxide

    NASA Astrophysics Data System (ADS)

    Hemeda, O. M.; Tawfik, A.; Hemeda, D. M.; Elsheekh, A. M.

    2015-09-01

    A series of ferrite samples, Ni0.1Cu0.2MgxZn0.7-x Fe2O4, (x=0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) has been prepared by the standard ceramic technique, sintered at 1200 °C for 2 h, and their crystalline structures were investigated by using X-ray diffraction. The IR spectra and the ESR spectra analysis have been studied. DC electrical resistivity, thermoelectric power, charge carriers concentration and charge carrier mobility have been calculated at different temperatures. The value of dc electrical resistivity reach minimum at x=0.35 and above this value the electrical resistivity start to increase. It is noticed that thermoelectric power α for the "Ni-Cu-Zn" system exhibits a positive sign indicating the majority carriers are holes without excluding the presence of electrons. Saturation magnetization Ms for the "Ni-Cu-Zn" system was calculated from M-H loop. It is noted that Ms decreases with Mg content up to x=0.55 and rapidly decrease above x>0.55 for the "Ni-Cu-Zn" system.

  9. The response of macrophages to a Cu-Al-Ni shape memory alloy.

    PubMed

    Colić, Miodrag; Tomić, Sergej; Rudolf, Rebeka; Anzel, Ivan; Lojen, Gorazd

    2010-09-01

    Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but little is known about their biocompatibility. The aim of this work was to study the response of rat peritoneal macrophages (PMØ) to a Cu-Al-Ni SMA in vitro, by measuring the functional activity of mitochondria, necrosis, apoptosis, and production of proinflammatory cytokines. Rapidly solidified (RS) thin ribbons were used for the tests. The control alloy was a permanent mold casting of the same composition, but without the shape memory effect. Our results showed that the control alloy was severely cytotoxic, whereas RS ribbons induced neither necrosis nor apoptosis of PMØ. These findings correlated with the data that RS ribbons are significantly more resistant to corrosion compared to the control alloy, as judged by the lesser release of Cu and Ni in the conditioning medium. However, the ribbons generated intracellular reactive oxygen species and upregulated the production of IL-6 by PMØ. These effects were almost completely abolished by conditioning the RS ribbons for 5 weeks. In conclusion, RS significantly improves the corrosion stability and biocompatibility of Cu-Al-Ni SMA. The biocompatibility of this functional material could be additionally enhanced by conditioning the ribbons in cell culture medium.

  10. Dendritic Ni(Cu)-polypyrrole hybrid films for a pseudo-capacitor

    NASA Astrophysics Data System (ADS)

    Choi, Bit Na; Chun, Woo Won; Qian, Aniu; Lee, So Jeong; Chung, Chan-Hwa

    2015-11-01

    Dendritic Ni(Cu)-polypyrrole hybrid films are fabricated for a pseudo-capacitor in a unique morphology using two simple methods: electro-deposition and electrochemical de-alloying. Three-dimensional structures of porous dendrites are prepared by electro-deposition within the hydrogen evolution reaction (HER) at a high cathodic potential; the high-surface-area structure provides sufficient redox reactions between the electrodes and the electrolyte. The dependence of the active-layer thickness on the super-capacitor performance is also investigated, and the 60 μm-thick Ni(Cu)PPy hybrid electrode presents the highest performance of 659.52 F g-1 at the scan rate of 5 mV s-1. In the thicker layers, the specific capacitance became smaller due to the diffusion limitation of the ions in an electrolyte. The polypyrrole-hybridization on the porous dendritic Ni(Cu) electrode provides superior specific capacitance and excellent cycling stability due to the improvement in electric conductivity by the addition of conducting polypyrrole in the matrices of the dendritic nano-porous Ni(Cu) layer and the synergistic effect of composite materials.

  11. Study of Metal-NH[subscript 3] Interfaces (Metal= Cu, Ni, Ag) Using Potentiostatic Curves

    ERIC Educational Resources Information Center

    Nunes, Nelson; Martins, Angela; Leitao, Ruben Elvas

    2007-01-01

    Experiment is conducted to determine the kinetic parameters of metal-solution interfaces. During the experiment the kinetic parameters for the interfaces Cu-NH[subscript 3], Ag-NH[subscript 3] and Ni-NH[subscript 3] is easily determined.

  12. Chemistry of Cu(acac){sub 2} on Ni(110) and Cu(110) surfaces: Implications for atomic layer deposition processes

    SciTech Connect

    Ma Qiang; Zaera, Francisco

    2013-01-15

    The thermal chemistry of copper(II)acetylacetonate, Cu(acac){sub 2}, on Ni(110) and Cu(110) single-crystal surfaces was probed under vacuum by using x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Some data for acetylacetone (Hacac, CH{sub 3}COCH{sub 2}COCH{sub 3}) adsorbed on Ni(110) are also reported as reference. Chemical transformations were identified in several steps covering a temperature range from 150 K to at least 630 K. The desorption of Hacac and a 3-oxobutanal (CH{sub 3}COCH{sub 2}CHO) byproduct was observed first at 150 and 180 K on Ni(110) and at 160 and 185 K on Cu(110), respectively. Partial loss of the acetylacetonate (acac) ligands and a likely change in adsorption geometry are seen next, with the possible production of HCu(acac), which desorbs at 200 and 235 K from the nickel and copper surfaces, respectively. Molecular Cu(acac){sub 2} desorption is observed on both surfaces at approximately 300 K, probably from recombination of Cu(acac) and acac surface species. The remaining copper atoms on the surface lose their remaining acac ligands to the substrate and become reduced directly to metallic copper. At the same time, the organic ligands follow a series of subsequent surface reactions, probably involving several C-C bond-scissions, to produce other fragments, additional Hacac and HCu(acac) in the gas phase in the case of the copper surface, and acetone on nickel. A significant amount of acac must nevertheless survive on the surface to high temperatures, because Hacac peaks are seen in the TPD at about 515 and 590 K and the C 1s XPS split associated with acac is seen up to close to 500 K. In terms of atomic layer deposition processes, this suggests that cycles could be design to run at such temperatures as long as an effective hydrogenation agent is used as the second reactant to remove the surface acac as Hacac. Only a small fraction of carbon is left behind on Ni after heating to 800 K, whereas more carbon

  13. Bioaccessibility of As, Cd, Cu, Ni, Pb, and Sb in toys and low-cost jewelry.

    PubMed

    Guney, Mert; Zagury, Gerald J

    2014-01-21

    Children can be exposed to toxic elements in toys and jewelry following ingestion. As, Cd, Cu, Ni, Pb, and Sb bioavailability was assessed (n = 24) via the in vitro gastrointestinal protocol (IVG), the physiologically based extraction test (PBET), and the European Toy Safety Standard protocol (EN 71-3), and health risks were characterized. Cd, Cu, Ni, and Pb were mobilized from 19 metallic toys and jewelry (MJ) and one crayon set. Bioaccessible Cd, Ni, or Pb exceeded EU migratable concentration limits in four to six MJ, depending on the protocol. Using two-phase (gastric + intestinal) IVG or PBET might be preferable over EN 71-3 since they better represent gastrointestinal physiology. Bioaccessible and total metal concentrations were different and not always correlated, indicating that bioaccessibility measurement may provide more accurate risk characterization. More information on impacts of multiple factors affecting metals mobilization from toys and jewelry is needed before recommending specific tests. Hazard index (HI) for Cd, Ni, or Pb were >1 for all six MJ exceeding the EU limits. For infants (6-12 mo old), 10 MJ had HI > 1 for Cd, Cu, Ni, or Pb (up to 75 for Cd and 43 for Pb). Research on prolonged exposure to MJ and comprehensive risk characterization for toys and jewelry exposure is recommended.

  14. Polymer-supported CuPd nanoalloy as a synergistic catalyst for electrocatalytic reduction of carbon dioxide to methane

    PubMed Central

    Zhang, Sheng; Kang, Peng; Bakir, Mohammed; Lapides, Alexander M.; Dares, Christopher J.; Meyer, Thomas J.

    2015-01-01

    Developing sustainable energy strategies based on CO2 reduction is an increasingly important issue given the world’s continued reliance on hydrocarbon fuels and the rise in CO2 concentrations in the atmosphere. An important option is electrochemical or photoelectrochemical CO2 reduction to carbon fuels. We describe here an electrodeposition strategy for preparing highly dispersed, ultrafine metal nanoparticle catalysts on an electroactive polymeric film including nanoalloys of Cu and Pd. Compared with nanoCu catalysts, which are state-of-the-art catalysts for CO2 reduction to hydrocarbons, the bimetallic CuPd nanoalloy catalyst exhibits a greater than twofold enhancement in Faradaic efficiency for CO2 reduction to methane. The origin of the enhancement is suggested to arise from a synergistic reactivity interplay between Pd–H sites and Cu–CO sites during electrochemical CO2 reduction. The polymer substrate also appears to provide a basis for the local concentration of CO2 resulting in the enhancement of catalytic current densities by threefold. The procedure for preparation of the nanoalloy catalyst is straightforward and appears to be generally applicable to the preparation of catalytic electrodes for incorporation into electrolysis devices. PMID:26668386

  15. Evaluation of high strength, high conductivity CuNiBe alloys for fusion energy applications

    SciTech Connect

    Zinkle, Steven J

    2014-06-01

    The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HPTM CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ~0.7 displacements per atom (dpa) at temperatures between 100 and 240 C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation increased with increasing irradiation temperature, with a uniform elongation of ~3.3% observed at 240 C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 C, and may be an attractive

  16. Ion irradiation induced nanocrystal formation in amorphous Zr 55Cu 30Al 10Ni 5 alloy

    NASA Astrophysics Data System (ADS)

    Carter, Jesse; Fu, E. G.; Martin, Michael; Xie, Guoqiang; Zhang, X.; Wang, Y. Q.; Wijesundera, D.; Wang, X. M.; Chu, Wei-Kan; McDeavitt, Sean M.; Shao, Lin

    2009-09-01

    Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr 55Cu 30Al 10Ni 5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 × 10 16 cm -2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5-10 nm and another with diameters of 50-100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings ( d-values) agree with the expectations for Cu 10Zr 7, NiZr 2 and CuZr 2 phases. We further discussed the possibility to form a substitutional intermetallic (Ni xCu 1-x)Zr 2 phase.

  17. Electro-oxidation of methanol in alkaline conditions using Pd-Ni nanoparticles prepared from organometallic precursors and supported on carbon vulcan

    NASA Astrophysics Data System (ADS)

    Manzo-Robledo, A.; Costa, Natália J. S.; Philippot, K.; Rossi, Liane M.; Ramírez-Meneses, E.; Guerrero-Ortega, L. P. A.; Ezquerra-Quiroga, S.

    2015-12-01

    Oxidation of low-molecular weight alcohols as energy sources using metal nanoparticles has attracted considerable interest for use as a power source in portable electronic devices. In this work, a series of mono- and bimetallic nanoparticles based on palladium and nickel (Pd, Pd90Ni10, Pd50Ni50, Pd10Ni90, and Ni) have been synthesized from organometallic precursors, namely tris(dibenzylideneacetone) dipalladium(0), Pd2(dba)3, and bis(1,5-cyclooctadiene)nickel(0), Ni(cod)2. Well-defined metal particles in the nanometric scale from 4.2 to 6.3 nm were observed by transmission electron microscopy. The as-prepared nanoparticles were mixed with a carbon Vulcan matrix (10 % wt. of the catalyst in turn) for investigation as electrocatalysts in methanol oxidation reaction (MOR) in alkaline conditions. The i- E profiles from cyclic voltammetry for the monometallic systems indicated a redox process attributed only to palladium or nickel, as expected. With the bimetallic nanomaterials, the redox process and the i- E characteristics are functions of the amount of nickel associated to palladium. From a fundamental point of view, it has been established that the OH ions' interfacial interaction and the MOR kinetics are affected by the presence of nickel (decreasing the faradic current) as supported by the current versus potential profiles obtained as a function of methanol concentration and with temperature variation.

  18. Preparation and electrical properties of Ni-Cu-Zn system doped with the magnesium oxide

    NASA Astrophysics Data System (ADS)

    Hemeda, O. M.; Tawfik, A.; Hemeda, D. M.; Elsheekh, A. M.

    2014-06-01

    A sery of ferrite samples, Ni0.1Cu0.2MgxZn0.7-xFe2O4, (x = 0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) have been prepared by the standard ceramic techniques, sintered at 1200°C for 2 h, and their crystalline structures were investigated by using X-ray diffraction, which confirmed the formation of Ni0.1Cu0.2MgxZn0.7-xFe2O4 phase. The presence of Mg content increases the crystallinity of the given ferrite which is considered as catalyst for the accomplishment of the solid state reaction. The lattice parameter and crystallite size were calculated from XRD. The cationic distribution was estimated from the theoretical values of lattice parameters. The IR spectra analysis has been studied. The dielectric constant for the ferrite system Ni-Cu-Zn gradually increases with temperature up to nearly Curie temperature and then increase sharply beyond the Tc. The Curie temperature obtained from the ´ ǎrepsilon versus T is in agreement with the Curie temperature obtained from other measurements. Dielectric loss tangent (tan δ) has the same behavior as dielectric constant (´ ǎrepsilon). A minimum value of dielectric loss tangent (tan δ) for the system "Ni-Cu-Zn" was observed at x = 0.45. Magnetic permeability has been studied. The dependence of initial permeability on temperature exhibit a peak which is called Hopkinson peak (HP) in the vicinity of Curie temperature and confirmed the phase purity of ferrite sample. The increasing of porosity and decreasing of grain size play an important role in decreasing μi. It is clear that the value of Tc is found to increase by increasing the concentration of diamagnetic substitution Mg for "Ni-Cu-Zn" system.

  19. Structural and magnetic phase transitions in CeCu6-xTx (T = Ag,Pd)

    SciTech Connect

    Poudel, Lekhanath N.; De la cruz, Clarina; Payzant, E. Andrew; Koehler, Michael R.; May, Andrew F.; Garlea, Vasile O.; Taylor, Alice E.; Parker, David S.; Cao, Huibo B.; McGuire, Michael A.; Tian, Wei; Matsuda, Masaaki; Jeen, Hyoung Jeen; Lee, Ho Nyung; Hong, Tao; Calder, Stuart A.; Lumsden, Mark D.; Zhou, Haidong; Keppens, Veerle; Mandrus, D.; Christianson, Andrew D.

    2015-12-15

    The structural and the magnetic properties of CeCu6-xAgx (0 ≤ x ≤ 0.85) and CeCu6-xPdx (0 ≤ x ≤ 0.4) have been studied using neutron diffraction, resonant ultrasound spectroscopy (RUS), x-ray diffraction measurements, and first principles calculations. The structural and magnetic phase diagrams of CeCu6-xAgx and CeCu6-xPdx as a function of Ag/Pd composition are reported. The end member, CeCu6, undergoes a structural phase transition from an orthorhombic (Pnma) to a monoclinic (P21/c) phase at 240 K. In CeCu6-xAgx, the structural phase transition temperature (Ts) decreases linearly with Ag concentration and extrapolates to zero at xS ≈ 0.1. The structural transition in CeCu6-xPdx remains unperturbed with Pd substitution within the range of our study. The lattice constant b slightly decreases with Ag/Pd doping, whereas a and c increase with an overall increase in the unit cell volume. Both systems, CeCu6-xAgx and CeCu6-xPdx, exhibit a magnetic quantum critical point (QCP), at x ≈ 0.2 and x ≈ 0.05, respectively. Near the QCP, long range antiferromagnetic ordering takes place at an incommensurate wave vector (δ1 0 δ2), where δ1 ~ 0.62, δ2 ~ 0.25, x = 0.125 for CeCu6-xPdx and δ1 ~ 0.64, δ2 ~ 0.3, x = 0.3 for CeCu6-xAgx. As a result, the magnetic structure consists of an amplitude modulation of the Ce moments which are aligned along the c axis of the orthorhombic unit cell.

  20. Calculation of the critical cooling rate for amorphous Pd/77.5/Si/16.5/Cu/6/

    NASA Technical Reports Server (NTRS)

    Steinberg, J.; Tyagi, S.; Lord, A. E., Jr.

    1981-01-01

    The viscosity of the molten alloy Pd(77.5)Si(16.5)Cu(6) has been determined from 744 to 1000 C using an oscillating cup viscometer. Using these data (together with other pertinent physical data available for this alloy) in existing crystallization theory indicates that it could be made amorphous at cooling rates as low as 5-10 K/sec. This analysis assumes strictly homogeneous nucleation. Containerless solidification will be one good testing ground for the results of this analysis.

  1. Integration of Kinetic Control and Lattice Mismatch To Synthesize Pd@AuCu Core-Shell Planar Tetrapods with Size-Dependent Optical Properties.

    PubMed

    Meng, Min; Fang, Zhicheng; Zhang, Chao; Su, Hongyang; He, Rong; Zhang, Renpeng; Li, Hongliang; Li, Zhi-Yuan; Wu, Xiaojun; Ma, Chao; Zeng, Jie

    2016-05-11

    Planar nanocrystals with multiple branches exhibit unique localized surface plasmon resonance properties and great promise in optical applications. Here, we report an aqueous synthesis of Pd@AuCu core-shell planar tetrapods through preferential overgrowth on Pd cubic seeds. The large lattice mismatch between the Pd core and the AuCu shell is the key to induce the formation of branches under sluggish reduction kinetics. Meanwhile, the capping effect of cetyltrimethylammonium chloride on the {100} facets of Pd cubes with an aspect ratio of 1.2 can determine the growth direction of AuCu branches to form a planar structure. Through simply varying the amounts of Pd cubic seeds, the sizes of products can be well-controlled in the range from 33 to 70 nm. With the manipulation of sizes, the peak position of in-plane dipole resonance can be adjusted from visible to near-infrared region. Due to the presence of tips and edges in the branches, planar tetrapods exhibited excellent surface-enhanced Raman scattering performance with an enhancement factor up to 9.0 × 10(3) for 70 nm Pd@AuCu planar tetrapods.

  2. Facile solvothermal synthesis of highly active and robust Pd1.87Cu0.11Sn electrocatalyst towards direct ethanol fuel cell applications

    NASA Astrophysics Data System (ADS)

    Jana, Rajkumar; Dhiman, Shikha; Peter, Sebastian C.

    2016-08-01

    Ordered intermetallic Pd1.87Cu0.11Sn ternary electrocatalyst has been synthesized by sodium borohydride reduction of precursor salts Pd(acac)2, CuCl2.2H2O and SnCl2 using one-pot solvothermal synthesis method at 220 °C with a reaction time of 24 h. To the best of our knowledge, here for the first time we report surfactant free synthesis of a novel ordered intermetallic ternary Pd1.87Cu0.11Sn nanoparticles. The ordered structure of the catalyst has been confirmed by powder x-ray diffraction, transmission electron microscopy (TEM). Composition and morphology of the nanoparticles have been confirmed through field emission scanning electron microscopy, energy-dispersive spectrometry and TEM. The electrocatalytic activity and stability of the ternary electrocatalyst towards ethanol oxidation in alkaline medium was investigated by cyclic voltammetry and chronoamperometry techniques. The catalyst is proved to be highly efficient and stable upto 500th cycle and even better than commercially available Pd/C (20 wt%) electrocatalysts. The specific and mass activity of the as synthesized ternary catalyst are found to be ∼4.76 and ∼2.9 times better than that of commercial Pd/C. The enhanced activity and stability of the ordered ternary Pd1.87Cu0.11Sn catalyst can make it as a promising candidate for the alkaline direct ethanol fuel cell application.

  3. Sulfides from Martian and Lunar Basalts: Comparative Chemistry for Ni Co Cu and Se

    SciTech Connect

    J Papike; P Burger; C Shearer; S Sutton; M Newville; Y Choi; A Lanzirotti

    2011-12-31

    Here Mars and Moon are used as 'natural laboratories' with Moon displaying lower oxygen fugacities ({approx}IW-1) than Mars ({approx}IW to FMQ). Moon has lower concentrations of Ni and Co in basaltic melts than does Mars. The major sulfides are troilite (FeS) in lunar basalts and pyrrhotite (Fe{sub 1-x}S) in martian basalts. This study focuses on the concentrations of Ni, Co, Cu, and Se. We chose these elements because of their geochemical importance and the feasibility of analyzing them with a combination of synchrotron X-ray fluorescence (SXRF) and electron microprobe (EPMA) techniques. The selenium concentrations could only be analyzed, at high precision, with SXRF techniques as they are <150 ppm, similar to concentrations seen in carbonaceous chondrites and interplanetary dust particles (IDPs). Nickel and Co are in higher concentrations in martian sulfides than lunar and are higher in martian olivine-bearing lithologies than olivine-free varieties. The sulfides in individual samples show very large ranges in concentration (e.g., Ni ranges from 50 000 ppm to <5 ppm). These large ranges are mainly due to compositional heterogeneities within individual grains due to diffusion and phase separation. Electron microprobe wavelength-dispersive (WDS) mapping of Ni, Co, and Cu show the diffusion trajectories. Nickel and Co have almost identical diffusion trajectories leading to the likely nucleation of pentlandite (Ni,Co,Fe){sub 9}S{sub 8}, and copper diffuses along separate pathways likely toward chalcopyrite nucleation sites (CuFeS{sub 2}). The systematics of Ni and Co in lunar and martian sulfides clearly distinguish the two parent bodies, with martian sulfides displaced to higher Ni and Co values.

  4. Performance of the nano-structured Cu-Ni (alloy) -CeO2 anode for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Minquan; Wang, Shaolan; Chen, Ting; Yuan, Chun; Zhou, Yucun; Wang, Shaorong; Huang, Jun

    2015-01-01

    In this work, copper and nickel oxides (CuO-NiO) powders with various mole ratios were synthesized by the glycine nitrate process (GNP) and the Cu-Ni alloy was obtained by reducing the CuO-NiO powders at 600 °C for 0.75 h. Furthermore, Cu1-xNix (alloy) -CeO2 impregnated YSZ anodes were fabricated by the impregnation method and the optimized anode composition was evaluated. It was found that the optimized mole ratio of Cu:Ni was 5:5, while the weight ratio of Cu-Ni alloy to CeO2 was 3:1. Additionally, impregnated anode with 40 wt % loading of Cu0.5Ni0.5 (alloy)-CeO2 exhibited the best performance and the polarization resistance of such anode was only 0.097, 0.115, 0.145 and 0.212 Ω cm2 at 750, 700, 650 and 600 °C, respectively. Finally, the performance of the optimized anode in methane (CH4) was investigated and the carbon deposition is greatly suppressed compared to the Ni-based anode.

  5. Tren centered tris-macrocycles as polytopic ligands for Cu(II) and Ni(II).

    PubMed

    Siegfried, Liselotte; McMahon, C Niamh; Kaden, Thomas A; Palivan, Cornelia; Gescheidt, Georg

    2004-07-21

    Two novel symmetric polytopic ligands L(1) and L(2) have been synthesized. They are composed of three 1,4,8,11-tetraazacyclotetradecane macrocycles which are connected to a central tren moiety via an ethylene and a trimethylene bridge, respectively. The complexation potential and the speciation diagrams of L(1) and L(2) towards Cu(2+) and Ni(2+) were determined by spectrophotometric and potentiometric titrations. Insight into the geometry of the Cu(2+) complexes is provided by UV-VIS and EPR spectroscopy. The simplified ligands L(3) and L(4) are utilized as references for an aminoethyl- and a tren-substituted tetraaza macrocycle to help assign the EPR spectra of the polytopic ligands L(1) and L(2). At a metal-to-ligand ratio of 3 : 1, the metal cations are preferentially bound to the tetraaza macrocycles of L(1) and L(2) in a square planar geometry. At high pH values, a nitrogen atom of the tren moiety in L(1) serves as an additional ligand in an axial position leading to a square pyramidal coordination around Cu(2+), whereas in L(2) no such geometry change is observed. At a metal-to-ligand ratio of 4 : 1, the additional metal cation resides in the central tren moiety of L(1) and L(2). However, in contrast to the typical trigonal bipyramidal geometry found in the [Cutren](2+) complex, the fourth Cu(2+) has a square pyramidal coordination caused by the interaction with the Cu(2+) cations in the macrocycles (as evidenced by EPR spectra). Since the sequence of metal complexation is such that the first three metal ions always bind to the three macrocycles of L(1) and L(2) and the fourth to the tren unit, it is possible to prepare heteronuclear complexes such as [Cu(3)NiL](8+) or [Ni(3)CuL](8+), which can be unambiguously identified by their spectral properties.

  6. Orthogonal Cu- and Pd-Based Catalyst Systems for the O- and N-Arylation of Aminophenols

    PubMed Central

    Maiti, Debabrata; Buchwald, Stephen L.

    2009-01-01

    O- or N-arylated aminophenol products constitute a common structural motif in various potentially useful therapeutic agents and/or drug candidates. We have developed a complementary set of Cu- and Pd-based catalyst systems for the selective O- and N-arylation of unprotected aminophenols using aryl halides. Selective O-arylation of 3- and 4-aminophenols is achieved with copper-catalyzed methods employing picolinic acid or CyDMEDA, trans-N,N′-dimethyl-1,2-cyclohexanediamine, respectively, as the ligand. The selective formation of N-arylated products of 3- and 4-aminophenols can be obtained with BrettPhos precatalyst, a biarylmonophosphine-based palladium catalyst. 2-Aminophenol can be selectively N-arylated with CuI, although no system for the selective O-arylation could be found. Coupling partners with diverse electronic properties and a variety of functional groups can be selectively transformed under these conditions. PMID:19899753

  7. Efficient and selective recovery of Ni, Cu, and Co from low-nickel matte via a hydrometallurgical process

    NASA Astrophysics Data System (ADS)

    Chen, Guang-ju; Gao, Jian-ming; Zhang, Mei; Guo, Min

    2017-03-01

    Low-nickel matte was intensively characterized, and Ni, Cu, and Co were determined to exist mainly as (Fe,Ni)9S8 and FeNi3, Cu5FeS4, and (Fe,Ni)9S8 and Fe3O4 (in isomorphic form), respectively. The efficient and selective extraction of Ni, Cu, and Co from the low-nickel matte in an (NH4)2S2O8/NH3·H2O solution system was studied. The effects of (NH4)2S2O8 and NH3·H2O concentrations, leaching time, and leaching temperature on the metal extraction efficiency were systematically investigated. During the oxidative ammonia leaching process, the metal extraction efficiencies of Ni 81.07%, Cu 93.81%, and Co 71.74% were obtained under the optimal conditions. The relatively low leaching efficiency of Ni was mainly ascribed to NiFe alloy deactivation in ammonia solution. By introducing an acid pre-leaching process into the oxidative ammonia leaching process, we achieved the high extraction efficiencies of 98.03%, 99.13%, and 85.60% for the valuable metals Ni, Cu, and Co, respectively, from the low-nickel matte.

  8. Weak hybridization and isolated localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd)

    NASA Astrophysics Data System (ADS)

    White, Benjamin; Yazici, Duygu; Ho, Pei-Chun; Kanchanavatee, Noravee; Pouse, Naveen; Friedman, Aaron; Maple, M. Brian

    2015-03-01

    Large Ce-Ce distances of 6.7-6.8 Åand weak hybridization between Ce 4 f and itinerant electron states act to promote stable localized magnetic moments in the compounds CeT2Cd20 (T = Ni, Pd), but also conspire to severely limit the strength of the Ruderman-Kittel-Kasuya-Yosida (RKKY) magnetic exchange interaction that couples them. As a consequence, measurements of electrical resistivity, performed on single-crystalline samples of these new Cd-based compounds down to 0.138 K, were unable to resolve any evidence for magnetic order. In this presentation, we will compare measurements of the physical properties of CeT2Cd20 (T = Ni, Pd) under ambient and applied pressures with the reported properties of the isostructural compounds CeT2X20 (T = transition metal; X = Al, Zn). We will use these comparisons to discuss the interplay of unit cell volume, hybridization, and the RKKY interaction and its role in establishing the ground states of the Ce-based ``1-2-20'' compounds. Sample synthesis and physical properties measurements were supported by the U.S. DOE under Grant No. DE-FG02-04-ER46105. Measurements of electrical resistivity below 1 K were supported by the NSF under Grants No. DMR-1206553 and No. DMR-1104544.

  9. Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers

    PubMed Central

    Calderón, Juan Carlos; Rios Ráfales, Miguel; Nieto-Monge, María Jesús; Pardo, Juan Ignacio; Moliner, Rafael; Lázaro, María Jesús

    2016-01-01

    In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM) images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2). From the CO oxidation at different temperatures, the activation energy Eact for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eap for the methanol oxidation was also determined finding—as a rate determining step—the COads diffusion to the OHads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies. PMID:28335315

  10. Ferromagnetic resonance study of Co/Pd/Co/Ni multilayers with perpendicular anisotropy irradiated with helium ions

    SciTech Connect

    Beaujour, J.-M. L.; Kent, A. D.; Tudosa, I.; Ravelosona, D.; Fullerton, E. E.

    2011-02-01

    We present a ferromagnetic resonance (FMR) study of the effect of helium ion irradiation on the magnetic anisotropy, the linewidth and the Gilbert damping of a Co/Ni multilayer coupled to Co/Pd bilayers. The perpendicular magnetic anisotropy decreases linearly with He ion fluence, leading to a transition to in-plane magnetization at a critical fluence of 5x10{sup 14} ions/cm{sup 2}. We find that the damping is nearly independent of fluence but the FMR linewidth at fixed frequency has a maximum near the critical fluence, indicating that the inhomogeneous broadening of the FMR line is a nonmonotonic function of the He ion fluence. Based on an analysis of the angular dependence of the FMR linewidth, the inhomogeneous broadening is associated with spatial variations in the magnitude of the perpendicular magnetic anisotropy. These results demonstrate that ion irradiation may be used to systematically modify the magnetic anisotropy and distribution of magnetic anisotropy parameters of Co/Pd/Co/Ni multilayers for applications and basic physics studies.

  11. Ferromagnetic resonance study of Co/Pd/Co/Ni multilayers with perpendicular anisotropy irradiated with helium ions

    NASA Astrophysics Data System (ADS)

    Beaujour, J.-M. L.; Kent, A. D.; Ravelosona, D.; Tudosa, I.; Fullerton, E. E.

    2011-02-01

    We present a ferromagnetic resonance (FMR) study of the effect of helium ion irradiation on the magnetic anisotropy, the linewidth and the Gilbert damping of a Co/Ni multilayer coupled to Co/Pd bilayers. The perpendicular magnetic anisotropy decreases linearly with He ion fluence, leading to a transition to in-plane magnetization at a critical fluence of 5×1014 ions/cm2. We find that the damping is nearly independent of fluence but the FMR linewidth at fixed frequency has a maximum near the critical fluence, indicating that the inhomogeneous broadening of the FMR line is a nonmonotonic function of the He ion fluence. Based on an analysis of the angular dependence of the FMR linewidth, the inhomogeneous broadening is associated with spatial variations in the magnitude of the perpendicular magnetic anisotropy. These results demonstrate that ion irradiation may be used to systematically modify the magnetic anisotropy and distribution of magnetic anisotropy parameters of Co/Pd/Co/Ni multilayers for applications and basic physics studies.

  12. Prediction of Reliable Metal-PH₃ Bond Energies for Ni, Pd, and Pt in the 0 and +2 Oxidation States

    SciTech Connect

    Craciun, Raluca; Vincent, Andrew J.; Shaughnessy, Kevin H.; Dixon, David A.

    2010-06-21

    Phosphine-based catalysts play an important role in many metal-catalyzed carbon-carbon bond formation reactions yet reliable values of their bond energies are not available. We have been studying homogeneous catalysts consisting of a phosphine bonded to a Pt, Pd, or Ni. High level electronic structure calculations at the CCSD(T)/complete basis set level were used to predict the M-PH₃ bond energy (BE) for the 0 and +2 oxidation states for M=Ni, Pd, and Pt. The calculated bond energies can then be used, for example, in the design of new catalyst systems. A wide range of exchange-correlation functionals were also evaluated to assess the performance of density functional theory (DFT) for these important bond energies. None of the DFT functionals were able to predict all of the M-PH3 bond energies to within 5 kcal/mol, and the best functionals were generalized gradient approximation functionals in contrast to the usual hybrid functionals often employed for main group thermochemistry.

  13. Ni-, Pd-, or Pt-catalyzed ethylene dimerization: a mechanistic description of the catalytic cycle and the active species.

    PubMed

    Roy, Dipankar; Sunoj, Raghavan B

    2010-03-07

    Two key mechanistic possibilities for group 10 transition metal [M(eta(3)-allyl)(PMe(3))](+) catalyzed (where M = Ni(II), Pd(II) and Pt(II)) ethylene dimerization are investigated using density functional theory methods. The nature of the potential active catalysts in these pathways is analyzed to gain improved insights into the mechanism of ethylene dimerization to butene. The catalytic cycle is identified as involving typical elementary steps in transition metal-catalyzed C-C bond formation reactions, such as oxidative insertion as well as beta-H elimination. The computed kinetic and thermodynamic features indicate that a commonly proposed metal hydride species (L(n)M-H) is less likely to act as the active species as compared to a metal-ethyl species (L(n)M-CH(2)CH(3)). Of the two key pathways considered, the active species is predicted to be a metal hydride in pathway-1, whereas a metal alkyl complex serves as the active catalyst in pathway-2. A metal-mediated hydride shift from a growing metal alkyl chain to the ethylene molecule, bound to the metal in an eta(2) fashion, is predicted to be the preferred route for the generation of the active species. Among the intermediates involved in the catalytic cycle, metal alkyls with a bound olefin are identified as thermodynamically stable for all three metal ions. In general, the Ni-catalyzed pathways are found to be energetically more favorable than those associated with Pd and Pt catalysts.

  14. Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers.

    PubMed

    Calderón, Juan Carlos; Rios Ráfales, Miguel; Nieto-Monge, María Jesús; Pardo, Juan Ignacio; Moliner, Rafael; Lázaro, María Jesús

    2016-10-18

    In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM) images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2). From the CO oxidation at different temperatures, the activation energy Eact for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eap for the methanol oxidation was also determined finding-as a rate determining step-the COads diffusion to the OHads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies.

  15. A study on the inhibition kinetics of bioaccumulation of Cu(II) and Ni(II) ions using Rhizopus delemar.

    PubMed

    Açikel, Unsal; Alp, Tuğba

    2009-09-15

    The microbial growth and simultaneous bioaccumulation of Cu(II) and Ni(II) ions during the growth of Rhizopus delemar in molasses medium was investigated in a batch system. The level of Cu(II) and Ni(II) bioaccumulation and microbial growth was dependent on pH, molasses sucrose concentration and initial Cu(II) and Ni(II) ion concentrations. An increase in initial total metal ion concentration inhibited both the growth rate of fungus and the bioaccumulation capacity. Lineweaver-Burk plot of Monod equation was used to study the inhibition kinetics of bioaccumulation of Cu(II) and Ni(II) and the intrinsic and apparent model parameters were evaluated in metals-free and metals-contaminated fermentation media. The maximum specific growth rate (micro(m)) and the Monod constant (K(s)) of microorganism in metals-free media were found as 0.405 L/h and 3.977 g/L, respectively. As micro(m) remained constant in the presence of increasing concentrations of Cu(II) and Ni(II) ions, the combined inhibition of Cu(II) and Ni(II) ions on the growth rate of R. delemar was found to be a competitive inhibition. The inhibition constants for Cu(II) and Ni(II) ions were determined as 56.71 mg Cu(II)/L and 47.44 mg Ni(II)/L. As the bioaccumulation of Cu(II) and Ni(II) ions was reduced by the presence of increasing concentrations of the other metal ion, compared with the single-metal systems, the individual action of Cu(II) and Ni(II) ions on the bioaccumulation of R. delemar was generally found to be antagonistic. On the other hand, the total combined effects of Cu(II) and Ni(II) ions on the bioaccumulation of R. delemar are thought to be synergistic since the total bioaccumulated metal ion quantities per unit mass of biomass were higher than those obtained in the growth media containing Cu(II) and Ni(II) ions alone at the same concentrations.

  16. Giant Peltier Effect in a Submicron-Sized Cu-Ni/Au Junction with Nanometer-Scale Phase Separation

    NASA Astrophysics Data System (ADS)

    Sugihara, Atsushi; Kodzuka, Masaya; Yakushiji, Kay; Kubota, Hitoshi; Yuasa, Shinji; Yamamoto, Atsushi; Ando, Koji; Takanashi, Koki; Ohkubo, Tadakatsu; Hono, Kazuhiro; Fukushima, Akio

    2010-06-01

    We observed a giant Peltier effect in a submicron Cu-Ni/Au junction. The Peltier coefficient was evaluated to be 480 mV at room temperature from the balance between Joule heating and the Peltier cooling effect in the junction, which is 40 times that expected from the Seebeck coefficients of bulk Au and Cu-Ni alloy. This giant cooling effect lowered the inner temperature of the junction by 160 K. Microstructure analysis with a three-dimensional atom probe suggested that the giant Peltier effect possibly originated from nanometer-scale phase separation in the Cu-Ni layer.

  17. Cu-Al-Ni Shape Memory Single Crystal Wires with High Transformation Temperature

    NASA Technical Reports Server (NTRS)

    Hautcoeur, Alain; Fouché, Florian; Sicre, Jacques

    2016-01-01

    CN-250X is a new material with higher performance than Nickel-Titanium Shape Memory Alloy (SMA). For space mechanisms, the main disadvantage of Nickel-Titanium Shape Memory Alloy is the limited transformation temperature. The new CN-250X Nimesis alloy is a Cu-Al-Ni single crystal wire available in large quantity because of a new industrial process. The triggering of actuators made with this Cu-Al-Ni single crystal wire can range from ambient temperature to 200 C in cycling and even to 250 C in one-shot mode. Another advantage of CN-250X is a better shape recovery (8 to 10%) than Ni-Ti (6 to 7%). Nimesis is the first company able to produce this type of material with its new special industrial process. A characterization study is presented in this work, including the two main solicitation modes for this material: tensile and torsion. Different tests measure the shape recovery of Cu-Al-Ni single crystals wires during heating from room temperature to a temperature higher than temperature of end of martensitic transformation.

  18. Microstructure and Precipitate's Characterization of the Cu-Ni-Si-P Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Tian, Baohong; Volinsky, Alex A.; Sun, Huili; Chai, Zhe; Liu, Ping; Chen, Xiaohong; Liu, Yong

    2016-04-01

    Microstructure of the Cu-Ni-Si-P alloy was investigated by transmission electron microscopy (TEM). The alloy had 551 MPa tensile strength, 226 HV hardness, and 36% IACS electrical conductivity after 80% cold rolling and aging at 450 °C for 2 h. Under the same aging conditions, but without the cold rolling, the strength, hardness, and electrical conductivity were 379 MPa, 216 HV, and 32% IACS, respectively. The precipitates identified by TEM characterization were δ-Ni2Si. Some semi-coherent spherical precipitates with a typical coffee bean contrast were found after aging for 48 h at 450 °C. The average diameter of the observed semi-coherent precipitates is about 5 nm. The morphology of the fracture surface was observed by scanning electron microscopy. All samples showed typical ductile fracture. The addition of P refined the grain size and increased the nucleation rate of the precipitates. The precipitated phase coarsening was inhibited by the small additions of P. After aging, the Cu-Ni-Si-P alloy can gain excellent mechanical properties with 804 MPa strength and 49% IACS conductivity. This study aimed to optimize processing conditions of the Cu-Ni-Si-P alloys.

  19. Structural transformations in Cu1.95Ni0.05S crystals

    NASA Astrophysics Data System (ADS)

    Nasirov, V. I.; Rzaeva, A. G.; Ibragimov, G. B.

    2016-12-01

    A solid solution of the Cu1.95Ni0.05S composition has been synthesized for the first time due to the partial replacement of Cu with Ni atoms in Cu2S. The polymorphic transformations in the polycrystalline samples in the temperature range of 300-1400 K have been investigated by X-ray diffraction and differential thermal analysis. It is established that, at room temperature, the synthesized Cu1.95Ni0.05S samples have an orthorhombic lattice with unit-cell parameters a = 26.50 Å, b = 15.39 Å, and c = 13.85 Å (sp. gr. Abm2). Heating to T = 379 ± 2 K leads to its transformation into a hexagonal lattice with parameters a = 3.960 Å and c = 6.78 Å (sp. gr. P63/ mmc). At 750 ± 2 K, the hexagonal modification is transformed into a cubic one with period a = 5.788 Å (sp. gr. Fm bar 3 m). The phase transition in this crystal is enantiotropic.

  20. Effect of Pd Interlayer on Electrochemical Properties of ENIG Surface Finish in 3.5 wt.% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Nam, N. D.; Bui, Q. V.; Nhan, H. T.; Phuong, D. V.; Bian, M. Z.

    2014-09-01

    The corrosion resistance of a multilayered (NiP-Pd-Au) coating with various thicknesses of palladium (Pd) interlayer deposited on copper by an electroless method was investigated using electrochemical techniques including potentiodynamic polarization and electrochemical impedance spectroscopy. In addition, the surface finish was examined by x-ray diffraction analysis and scanning electron microscopy, and the contact angle of the liquid-solid interface was recorded. The corrosion resistance of the copper substrate was considerably improved by Pd interlayer addition. Increase of the thickness of the Pd interlayer enhanced the performance of the Cu-NiP-Pd-Au coating due to low porosity, high protective efficiency, high charge-transfer resistance, and contact angle. These are attributed to the diffusion of layers in the Cu-NiP-Pd-Au coating acting as a physical barrier layer, leading to the protection provided by the coating.

  1. Joint effect of ferromagnetic and non-ferromagnetic cations for adjusting room temperature ferromagnetism of highly luminescent CuNiInS quaternary nanocrystals

    NASA Astrophysics Data System (ADS)

    Shen, Jin; Wang, Chunlei; Xu, Shuhong; Lv, Changgui; Zhang, Ruohu; Cui, Yiping

    2017-01-01

    In this work, highly luminescent quaternary CuNiInS nanocrystals (NCs) are put forward as a good prototype for investigating defect-induced room temperature ferromagnetism. A ferromagnetic Ni cation can preserve the strong luminescence of NCs without introducing intermediate energy levels in the center of the forbidden band. The strong luminescence of NCs is used as an indicator for monitoring the concentration of vacancy defects inside them, facilitating the investigation of the origin of room temperature ferromagnetism in CuNiInS NCs. Our results reveal that the patching of Cu vacancies ({{{{V}}}{{Cu}}}-) with Ni will result in bound magnetic polarons composed of both {{{{V}}}{{Cu}}}- and a substitution of Cu by Ni ({{{{Ni}}}{{Cu}}}+), giving rise to the room temperature ferromagnetism of CuNiInS NCs. Either the ferromagnetic Ni or the non-ferromagnetic Cu cation can tune the magnetism of CuNiInS NCs because of the change of bound magnetic polaron concentration at the altered concentration ratio of {{{{V}}}{{Cu}}}- and {{{{Ni}}}{{Cu}}}+.

  2. Modification of ZnO Thin Films by Ni, Cu, and Cd Doping*1

    NASA Astrophysics Data System (ADS)

    Jiménez-González, A. E.

    1997-02-01

    With the propose of investigating the effect of transition elements in ZnO thin films prepared by the Successive Ion Layer Adsorption and Reaction (SILAR) technique, the deposition solutions were chemically impurified with Ni, Cu, and Cd, as elements of the Ib, IIb, and VIIIa groups. X-ray fluorescence (XRF) analyses confirm that the impurification with Ni and Cu in fact took place but the impurification with Cd did not, while the XRD analyses show that foras preparedand Ni-impurified annealed films, the crystallites are almost oriented along thecaxis. The electrical properties of the ZnO films were also modified with the impurification. After annealing in air (450°C) the dark conductivity of the films was increased in the case of Ni and Cd impurification up to 1.80×10-3and 1.86×10-2[Ω cm]-1, respectively, but it decreased drastically in the case of Cu to 5.51×10-7[Ω cm]-1, as referred to the dark conductivity (1.86×10-4[Ω cm]-1) of the pure ZnO sample. The measured activation energy for the electrical conductivity of the modified ZnO thin films is 55 meV for the Ni modification, indicating the existence of donor levels. On the other hand, the Cu modification increases the activation energy up to 132 meV, which is higher than the activation energy for pure ZnO thin films (98 meV).

  3. Effects of Ga addition on the mechanical properties of 35Ag-30Pd-20Au-15Cu alloy.

    PubMed

    Yamanaka, Masahiko; Goto, Shin-ichi; Churnjitapirom, Pornkiat; Ogura, Hideo

    2002-12-01

    Ten 35Ag-30Pd-20Au-15Cu alloys containing 0.00, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50, 2.00, 4.00, or 6.00% Ga were experimentally prepared to investigate the effect of Ga on their mechanical properties in addition to their use for denture frameworks, connectors and clasps. The effect of Ga addition on the mechanical properties was marked with a significant increase in the tensile strength, 0.2% off-set proof stress (proof stress) and Vickers hardness observed at low Ga contents (0.25-2.00%). On the other hand, the elongation significantly decreased with the addition of Ga at all contents used in this study. The tensile strength, proof stress and Vickers hardness of the 35Ag-30Pd-20Au-15Cu alloys containing 0.25-2.00% Ga were in the range of 809-957 MPa, 669-857 MPa and 260-301 MPa, respectively. These values are similar to those of Co-Cr alloys, suggesting that 0.25-2.00% Ga alloys can be used for denture frameworks, clasps and connectors.

  4. Cu(II) and Pd(II) complexes of water soluble O-carboxymethyl chitosan Schiff bases: Synthesis, characterization.

    PubMed

    Baran, Talat; Menteş, Ayfer

    2015-08-01

    This study reports the synthesis of two new water soluble O-carboxymethyl chitosan Schiff bases (OCMCS-5 and OCMCS-6a) and their Cu(II) and Pd(II) complexes. Characterizations of these complexes were carried out with FTIR, elemental analysis, (13)C CPMAS, UV-vis, magnetic moment and molar conductivity techniques. The degrees of substitution (DS) for OCMCS-5a and OCMCS-6a were determined to be 0.48 and 0.44 in elemental analysis. The solubility test revealed that OCMCS-5a and OCMCS-6a dissolved thoroughly in water. The surface morphologies of chitosan (CS), OCMCS-5a, OCMCS-6a and their complexes were studied with SEM-EDAX. Thermal stability of the synthesized compounds was evaluated by TG/DTG and their crystallinity values were investigated with powder X-ray diffraction. Cu(II) and Pd(II) contents of the complexes were estimated with ICP-OES. The characterization studies demonstrated that the thermal stability and crystallinity values of the OCMCS-5a and OCMCS-6a were lower than those of CS.

  5. Investigation of interfacial reaction between Sn-Ag eutectic solder and Au/Ni/Cu/Ti thin film metallization

    NASA Astrophysics Data System (ADS)

    Park, J. Y.; Yang, C. W.; Ha, J. S.; Kim, C.-U.; Kwon, E. J.; Jung, S. B.; Kang, C. S.

    2001-09-01

    This paper reports the formation of intermetallic compounds in Au/Ni/Cu/Ti under-bump-metallization (UBM) structure reacted with Ag-Sn eutectic solder. In this study, UBM is prepared by evaporating Au(500 Å)/Ni(1000 Å)/Cu(7500 Å) /Ti (700 Å) thin films on top of Si substrates. It is then reacted with Ag-Sn eutectic solder at 260 C for various times to induce different stages of the interfacial reaction. Microstructural examination of the interface, using both chemical and crystallographic analysis, indicates that two types of intermetallic compounds are formed during the interfacial reaction. The first phase, formed at the intial stage of the reaction, is predominantly Ni3Sn4. At longer times the Ni3Sn4 phase transforms into (Cu, Ni)6Sn6, probably induced by interdiffusion of Cu and Ni. At this stage, the underlying Cu layer also reacts with Sn and forms the same phase, (Cu,Ni)6Sn5. As a result, the fully reacted interface is found to consist of two intermetallic layers with the same phase but different morphologies.

  6. Valorization of biosorbent obtained from a forestry waste: Competitive adsorption, desorption and transport of Cd, Cu, Ni, Pb and Zn.

    PubMed

    Cutillas-Barreiro, Laura; Paradelo, Remigio; Igrexas-Soto, Alba; Núñez-Delgado, Avelino; Fernández-Sanjurjo, María José; Álvarez-Rodriguez, Esperanza; Garrote, Gil; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel

    2016-09-01

    Bark from Pinus pinaster is one of the most abundant forestry wastes in Europe, and among the proposed technologies for its reutilization, the removal of heavy metals from wastewater has been gaining increasing attention. In this work, we have studied the performance of pine bark for heavy metal biosorption on competitive systems. Pb, Cu, Ni, Zn and Cd sorption and desorption at equilibrium were studied in batch experiments, whereas transport was studied in column experiments. Batch experiments were performed adding simultaneously different concentrations (0.08-3.15mM) of two or more metals in solution to pine bark samples. Column experiments were performed with 10mM solutions of two metals or a 5mM solution of the five metals. In general, the results under competitive conditions were different to those obtained in monoelemental experiments. The multi-metal batch experiments showed the adsorption sequence Pb≈Cu>Cd>Zn>Ni for lower metal doses, Pb>Cu>Cd>Zn>Ni for intermediate doses, and Pb>Cu>Cd≈Zn≈Ni for high metal doses. Desorption followed the sequence PbCu for the lowest metal doses, and Pb<Cu for the highest ones. The bi-metal batch experiments indicated that Cu and Pb suffered the highest retention, with high capacity to displace Cd, Ni and Zn from adsorption sites on pine bark. The transport experiments produced comparable results to those obtained in the batch experiments, with pine bark retention capacity following the sequence Pb>Cu>Zn>Cd>Ni. The presence of a second metal affected the transport of all the elements studied except Pb, and confirmed the strong influence of Pb and Cu on the retention of the other metals. These results can help to appropriately design decontamination systems using this forestry waste.

  7. Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers

    NASA Astrophysics Data System (ADS)

    Wei, Yajun; Akansel, Serkan; Thersleff, Thomas; Harward, Ian; Brucas, Rimantas; Ranjbar, Mojtaba; Jana, Somnath; Lansaker, Pia; Pogoryelov, Yevgen; Dumas, Randy K.; Leifer, Klaus; Karis, Olof; Åkerman, Johan; Celinski, Zbigniew; Svedlindh, Peter

    2015-01-01

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO2 substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100 Å, the thickness of the Cu spacer was varied from 5 to 50 Å. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3 erg/cm2 for the sample with a 5 Å Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications.

  8. Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers

    SciTech Connect

    Wei, Yajun Akansel, Serkan; Thersleff, Thomas; Brucas, Rimantas; Lansaker, Pia; Leifer, Klaus; Svedlindh, Peter; Harward, Ian; Celinski, Zbigniew; Ranjbar, Mojtaba; Dumas, Randy K.; Jana, Somnath; Pogoryelov, Yevgen; Karis, Olof; Åkerman, Johan

    2015-01-26

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO{sub 2} substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100 Å, the thickness of the Cu spacer was varied from 5 to 50 Å. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3 erg/cm{sup 2} for the sample with a 5 Å Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications.

  9. Microstructural changes to AlCu6Ni1 alloy after prolonged annealing at elevated temperature.

    PubMed

    Wierzbińska, M; Sieniawski, J

    2010-03-01

    This work presents results of microstructure examination of AlCu(6)Ni(1) aluminium alloy. The commercial AlCu(4)Ni(2)Mg(2) (M-309) alloy is widely used for elements of aircraft and automotive engines. Modification its chemical composition was aimed at improving the stability of mechanical properties of the alloy subjected to long-term exposure to high temperature. The alloy after standard T6 heat treatment (solution heat treated at 818 K/10 h/water quenched followed by ageing at 498 K/8 h/air cooled) was annealed for 150 h at elevated temperature of 573 K corresponding to the maximum value at which structural elements of jet piston engines made of aluminium alloys operate. It was found that applied heat treatment caused an increasing in the particles of hardening phase (theta'-Al(2)Cu) size. The significant growth of the length of theta'-Al(2)Cu precipitations was observed in particularly. Nevertheless, it did not strongly result in change of its shape - the 'crystallites' and 'rods' were still characteristic of hardening phase morphology. The phenomena of the growth of theta'-Al(2)Cu precipitates caused decreasing the mechanical properties of the alloy, what is the subject of further investigations by the authors.

  10. Chemical synthesis, structural, optical, magnetic characteristics and enhanced visible light active photocatalysis of Ni doped CuS nanoparticles

    NASA Astrophysics Data System (ADS)

    Subramanyam, K.; Sreelekha, N.; Amaranatha Reddy, D.; Murali, G.; Rahul Varma, K.; Vijayalakshmi, R. P.

    2017-03-01

    In this paper, we report systematic investigations on the effects of Ni doping on the structural, optical, magnetic and photocatalytic characteristics of CuS nanoparticles synthesized by simplistic wet chemical co-precipitation route via EDTA molecules as templates. XRD studies confirmed that accurate phase formation of synthesized nanoparticles and chemical composition were obtained by EDX. Magnetic measurements revealed that 3% Ni doped CuS nanoparticles show signs of good ferromagnetism at room temperature and transition of magnetic signs from ferromagnetic to paramagnetic nature by increasing the Ni dopant concentration in CuS host matrix. The photocatalytic degradation efficiency of the prepared pure and Ni doped CuS nanoparticles were evaluated as a function of simulated sunlight irradiation via RhB organic dye pollutant as a test molecule. Particularly, in the presence of 3% Ni doped CuS nanoparticles in pollutant solution 98.46% degradation efficiency was achieved within 60 min of sunlight irradiation; meanwhile bare CuS attained only 83.22%. Further, after five cycles 3% Ni doping CuS nanoparticles exhibit good photocatalytic stability with very negligible catalyst loss. We believe that the investigations in this study provides adaptable pathway for the synthesizing of various diluted magnetic semiconductor nanoparticles and their applications in spintronic devices as well as sunlight-driven photocatalysts intended for wastewater purification.

  11. NiFe/CoFe/Cu/CoFe/MnIr spin valves studied by ferromagnetic resonance

    NASA Astrophysics Data System (ADS)

    Timopheev, A. A.; Sobolev, N. A.; Pogorelov, Y. G.; Bunyaev, S. A.; Teixeira, J. M.; Cardoso, S.; Freitas, P. P.; Kakazei, G. N.

    2013-05-01

    Ion-beam deposited (Glass/Ta/NiFe/CoFe/Cu/CoFe/MnIr/Ta) spin valves (SVs) with a Cu-spacer thickness (tCu) varying from 14 to 28 Å have been studied by ferromagnetic resonance (FMR) and magnetoresistance (MR) measurements. With respect to the interlayer coupling strength between the free and fixed ferromagnetic layers, the samples have been divided in those with a weak coupling (for tCu > 16 Å) and a strong coupling regimes (for tCu ≤ 16 Å). The FMR behavior in these two regimes is quite different. For the weakly coupled series, there are two well-defined FMR peaks stemming from the free and fixed layers. Their in-plane angular dependences exhibit 180° and 360° symmetries, respectively. For the strongly coupled SVs, the resonance modes are hybridized and possess features of both layers simultaneously. The main coupling mechanism between the two layers, as concluded from the FMR and MR measurements, is the Néel "orange-peel" magnetostatic interaction, accompanied by a direct exchange due to pinholes in the Cu spacer for tCu < 17 Å.

  12. Superelasticity of Cu-Ni-Al shape-memory fibers prepared by melt extraction technique

    NASA Astrophysics Data System (ADS)

    Li, Dong-yue; Zhang, Shu-ling; Liao, Wei-bing; Geng, Gui-hong; Zhang, Yong

    2016-08-01

    In the paper, a melt extraction method was used to fabricate Cu-4Ni-14Al (wt%) fiber materials with diameters between 50 and 200 μm. The fibers exhibited superelasticity and temperature-induced martensitic transformation. The microstructures and superelasticity behavior of the fibers were studied via scanning electron microscopy (SEM) and a dynamic mechanical analyzer (DMA), respectively. Appropriate heat treatment further improves the plasticity of Cu-based alloys. The serration behavior observed during the loading process is due to the multiple martensite phase transformation.

  13. Hydrogen production by thermocatalytic decomposition of methane over Ni-Al and Ni-Cu-Al catalysts: Effect of calcination temperature

    NASA Astrophysics Data System (ADS)

    Echegoyen, Y.; Suelves, I.; Lázaro, M. J.; Moliner, R.; Palacios, J. M.

    Thermo catalytic decomposition of methane using Ni-Al and Ni-Cu-Al catalyst prepared by fusion of the corresponding nitrates is studied. The effects of catalyst calcination temperature on the hydrogen yields and the characteristics of the carbon obtained are studied. The role of copper has been also analyzed. Whatever the calcination temperature, all the catalysts show a high and almost constant hydrogen yield without catalyst deactivation after 8 h on stream, which confirms the good performance of this kind of catalysts. The presence of copper enhances the hydrogen production and the best results were obtained using catalysts calcined at 600 °C. Cu has a strong influence on the dispersion of Ni in the catalysts and inhibits NiO from the formation of nickel aluminate even at high calcinations temperatures, which facilitates the formation of the metallic Ni active phase during the subsequent catalyst reduction step. All catalysts tested promote the formation of very long filaments of carbon a few tens of nanometers in diameter and some micrometers long. The structural properties of these carbon filaments highly depend on the presence of Cu:Ni-Cu-Al catalysts promote the formation of a well-ordered graphitic carbon while Ni-Al catalysts enhance the formation of a rather turbostratic carbon.

  14. Improvement of mechanical and biological properties of TiNi alloys by addition of Cu and Co to orthodontic archwires.

    PubMed

    Phukaoluan, Aphinan; Khantachawana, Anak; Kaewtatip, Pongpan; Dechkunakorn, Surachai; Kajornchaiyakul, Julathep

    2016-09-01

    The purpose of this study was to investigate improved performances of TiNi in order to promote tooth movement. Special attention was paid to the effect on the clinical properties of TiNi of adding Cu and Co to this alloy. Ti49.4Ni50.6, Ti49Ni46Cu5 and Ti50Ni47Co3 (at %) alloys were prepared. Specimens were cold-rolled at 30% reduction and heat-treated at 400°C for 60min. Then, the test results were compared with two types of commercial archwires. The findings showed that superelasticity properties were confirmed in the manufactured commercial alloys at mouth temperature. The difference of stress plateau in TiNi, TiNiCo and commercial wires B at 25°C changed significantly at various testing temperatures due to the combination of martensite and austenite phases. At certain temperatures the alloys exhibited zero recovery stress at 2% strain and consequently produced zero activation force for moving teeth. The corrosion test showed that the addition of Cu and Co to TiNi alloys generates an increase in corrosion potential (Ecorr) and corrosion current densities (Icorr). Finally, we observed that addition of Cu and Co improved cell viability. We conclude that addition of an appropriate amount of a third alloying element can help enhance the performances of TiNi orthodontic archwires.

  15. Structure and magnetism of S = 1/2 kagome antiferromagnets NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2.

    PubMed

    Li, Yue-sheng; Zhang, Qing-ming

    2013-01-16

    We have successfully synthesized S = 1/2 kagome antiferromagnets MCu(3)(OH)(6)Cl(2) (M = Ni and Co) by a hydrothermal method with a rotating pressure vessel. Structural characterization shows that both compounds have similar crystal structure to ZnCu(3)(OH)(6)Cl(2) with R3m symmetry. As with ZnCu(3)(OH)(6)Cl(2), the compounds show no obvious hysteresis at 2 K. A spin-glass transition is found in both NiCu(3)(OH)(6)Cl(2) and CoCu(3)(OH)(6)Cl(2) at low temperatures (6.0 and 3.5 K respectively) by AC susceptibility measurements. This indicates no long-range magnetic order and a strong spin frustration. The substitution of Zn(2+) by magnetic ions Ni(2+) or Co(2+) effectively enhances the interlayer exchange coupling and changes the ground state of the kagome spin system.

  16. Characterization of ultrafine grained Cu-Ni-Si alloys by electron backscatter diffraction

    NASA Astrophysics Data System (ADS)

    Altenberger, I.; Kuhn, H. A.; Gholami, M.; Mhaede, M.; Wagner, L.

    2014-08-01

    A combination of rotary swaging and optimized precipitation hardening was applied to generate ultra fine grained (UFG) microstructures in low alloyed high performance Cu-based alloy CuNi3Si1Mg. As a result, ultrafine grained (UFG) microstructures with nanoscopically small Ni2Si-precipitates exhibiting high strength, ductility and electrical conductivity can be obtained. Grain boundary pinning by nano-precipitates enhances the thermal stability. Electron channeling contrast imaging (ECCI) and especially electron backscattering diffraction (EBSD) are predestined to characterize the evolving microstructures due to excellent resolution and vast crystallographic information. The following study summarizes the microstructure after different processing steps and points out the consequences for the most important mechanical and physical properties such as strength, ductility and conductivity.

  17. Calculation of Phonon Conductivity and Seebeck Coefficient in Cu-Ni Alloy

    NASA Astrophysics Data System (ADS)

    Konishi, Yusuke; Asai, Yoshihiro

    2015-03-01

    In recent years, thermoelectric materials have been attracting a lot of attention because they are expected to be applied for utilization of waste heat. Many kinds of materials are studied for this purpose; semiconductors, alloys, organic materials, etc. In 2010, a giant Peltier effect was observed in a Cu-Ni/Au junction. It is considered that this giant Peltier effect is caused by nano-scale phase separation formed in the sputtering process. Although this material is a great candidate for a thermoelectric material, we need to find the condition for a large thermoelectric coefficient that requires a large Seebeck coefficient, large electric conductivity, and small phonon conductivity. We calculated phonon conductivity in Cu-Ni alloy by using nonequilibrium molecular dynamics simulation and calculated Seebeck coefficients via ab-initio methods.

  18. Microstructural characterization of irradiated Fe-Cu-Ni-P model steels

    SciTech Connect

    Miller, M.K.; Hoelzer, D.T.; Ebrahimi, F.; Hawthorne, J.R.; Burke, M.G.

    1987-01-01

    The microstructure of Fe-Cu-Ni-P model pressure vessel steels after neutron irradiation and thermal aging has been characterized by atom probe field-ion microscopy and augmented by transmission electron microscopy. High densities of small, roughly spherical or disc shaped copper clusters/precipitates were observed in the neutron irradiated alloys that contained copper. Small spherical phosphorus clusters were observed in the irradiated copper-free alloys, and copper phosphides were observed in a high phosphorus Fe-Cu-Ni-P alloy. None of these clusters/precipitates were observed in the thermally aged materials. The increases in the tensile and yield strengths that were observed after neutron irradiation resulted from these clusters and other lattice defects. 14 refs., 8 figs., 2 tabs.

  19. Investigation on compressive behavior of Cu-35Ni-15Al alloy at high temperatures

    NASA Astrophysics Data System (ADS)

    Li, Cong; Chen, Jian; Li, Wei; Hu, Yongle; Ren, Yanjie; Qiu, Wei; He, Jianjun; Chen, Jianlin

    2014-09-01

    Microstructures and mechanical properties of Cu-35Ni-15Al alloy in cast and porous states were studied by scanning electron microscopy and compression tests. The influence of porosity, deformation temperature and loading rate on mechanical properties of the two kinds of alloys was investigated. The results show that the as cast alloy and porous alloys have almost the same phase constitution: Cu rich phase, Ni rich phase and K intermetallics. The yield strength of porous alloys increases continuously with decreasing porosity, the relationship between porosity and yield stress follows Gibson-Ashby equation. With decreasing deformation temperature, the yield strength of as cast alloy and porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend. After compression, the microstructure of as cast alloy is more uniform, and porous alloys are more prone to have localized deformations.

  20. Deformation behavior of Nb nanowires in TiNiCu shape memory alloy matrix

    DOE PAGES

    Jiang, Daqiang; Liu, Yinong; Yu, Cun; ...

    2015-08-18

    An in-situ nanowire Nb/TiNiCu composite is fabricated based on the concept of strain under-matching between a phase transforming matrix and high strength nanomaterials. The deformation behavior of the Nb nanowire was investigated by means of in-situ synchrotron X-ray diffraction when the TiNiCu matrix underwent different deformation modes. The maximum lattice strain of the Nb nanowires was about 5% when the matrix deformed via martensitic transformation or 1% when deforming plastically by dislocation slip. As a result, the Nb nanowires showed a lattice strain of 3.5% when the matrix deformed in the mixed mode of plastic deformation and martensitic transformation, whichmore » means that the occurrence of plastic deformation does not impede load transfer from the matrix to the nanowires.« less

  1. Deformation behavior of Nb nanowires in TiNiCu shape memory alloy matrix

    SciTech Connect

    Jiang, Daqiang; Liu, Yinong; Yu, Cun; Liu, Weilong; Yang, Hong; Jiang, Xiaohua; Ren, Yang; Cui, Lishan

    2015-08-18

    An in-situ nanowire Nb/TiNiCu composite is fabricated based on the concept of strain under-matching between a phase transforming matrix and high strength nanomaterials. The deformation behavior of the Nb nanowire was investigated by means of in-situ synchrotron X-ray diffraction when the TiNiCu matrix underwent different deformation modes. The maximum lattice strain of the Nb nanowires was about 5% when the matrix deformed via martensitic transformation or 1% when deforming plastically by dislocation slip. As a result, the Nb nanowires showed a lattice strain of 3.5% when the matrix deformed in the mixed mode of plastic deformation and martensitic transformation, which means that the occurrence of plastic deformation does not impede load transfer from the matrix to the nanowires.

  2. Properties of the Ti40Zr10Cu36Pd14 BMG Modified by Sn and Nb Additions

    NASA Astrophysics Data System (ADS)

    Sypien, Anna; Stoica, Mihail; Czeppe, Tomasz

    2016-03-01

    The results of investigation of the influence of additions of 2 and 3 at.% of Sn and simultaneously of Sn and 3 at.% Nb on microstructure and properties of the bulk metallic glasses of composition (Ti40Cu36- x Zr10Pd14Sn x )100- y Nb y are reported. It was found that the additions of Sn increased the temperatures of glass transition (T g), primary crystallization (T x ), melting, and liquidus as well as supercooled liquid range (Δ T) and glass forming ability (GFA). The nanohardness and elastic modulus decreased in alloys with 2 and 3 at.% Sn additions, revealing similar values. The 3 at.% Nb addition to the Sn-containing amorphous phase decreased as well all the T g, T x , T L, and T m temperatures as Δ T and GFA; however, relatively larger values of this parameters in alloys containing larger Sn content were preserved. In difference to the previously published results, in the case of the amorphous alloys containing small Nb and Sn additions, a noticeable amount of the quenched-in crystalline phases was not confirmed, at least of the micrometric sizes. In the case of the alloys containing Sn or both Sn and Nb, two slightly different amorphous phase compositions were detected, suggesting separation in the liquid phase. Phase composition of the alloys determined after amorphous phase crystallization was similar for all compositions. The phases Cu8Zr3, CuTiZr, and Pd3Zr were mainly identified in the proportions dependent on the alloy compositions.

  3. Structural, magnetic and dielectric study of Cu substituted NiZn ferrite nanorod

    NASA Astrophysics Data System (ADS)

    Das, Partha Sarathi; Singh, Gajendra Prasad

    2016-03-01

    The Cu2+ doped Ni0.5-xCuxZn0.5Fe2O4 (with x=0, 0.1, 0.2 and 0.3) ferrites of nanorods morphology was synthesized by glycine-nitrate auto-combustion method. The samples presents the diffraction peaks of cubic spinel crystal structure with Fd 3 ̅m space group. An average crystallite size of 47 nm is obtained for undoped Ni0.5Zn0.5Fe2O4. The Cu (x=0.1) doping is increased the crystallite size to 50 nm, thereafter, it is decreased to 42 and 38 nm at x=0.2 and 0.3 respectively. The lattice parameter is found to increase from 8.354 Å to 8.408 Å with increasing the Cu2+ content. The formation of ferrite phase is further confirmed by obtaining the active Raman mode peaks of A1g+Eg+3T2g bands in all samples. The bands are linked with the symmetric and asymmetric stretching as well as the symmetric bending. The Cu (x=0.1) doping showed 20% enhancement in coercivity, i.e. 105 Oe and 16% enhancement in saturation magnetization 87.16 emu/g compared to 87 Oe and 73.13 emu/g at x=0. The dielectric constant of 450 for the Cu (x=0) and 50 for Cu (x=0.1) is obtained at a constant frequency of 100 Hz. The dielectric loss as low as 0.05 is measured for Cu (x=0.1) at 1 MHz.

  4. CO₂ electroreduction at bare and Cu-decorated Pd pseudomorphic layers: catalyst tuning by controlled and indirect supporting onto Au(111).

    PubMed

    Januszewska, Aneta; Jurczakowski, Rafal; Kulesza, Pawel J

    2014-12-02

    We report here the results of electrochemical studies on CO2 electroreduction at multilayered catalyst composed of the monatomic layer of copper covering palladium overlayers (0.8-10 monolayers) deposited on the well-defined Au(111) surface. These multilayered systems were obtained by successive underpotential deposition steps: Pd on Au(111) as well as Cu on Pd/Au(111). Low index orientation of Au substrate was chosen to compare Pd overlayers with bulk Pd(111), which is known to reduce CO2 to CO adsorbates in acidic solutions. The process of CO2 electroreduction was studied by using classical transient electrochemical methods. Catalytic activity of bare Pd layers was investigated in acidic and neutral solutions. In the latter case, much higher activity of Pd overlayers was observed. The results showed that the palladium layer thickness significantly changed the catalytic activities of both bare Pd overlayers and the one Cu monolayer covered electrodes toward CO2 electroreduction. Results show that catalytic activity can be finely tuned by using the multilayered near-surface-alloy approach.

  5. A Novel Magnetically Recoverable Ni-CeO2-x/Pd Nanocatalyst with Superior Catalytic Performance for Hydrogenation of Styrene and 4-Nitrophenol.

    PubMed

    Jiang, Yi-Fan; Yuan, Cheng-Zong; Xie, Xiao; Zhou, Xiao; Jiang, Nan; Wang, Xin; Imran, Muhammad; Xu, An-Wu

    2017-02-28

    Metal/support nanocatalysts consisting of various metals and metal oxides not only retain the basic properties of each component, but also exhibit higher catalytic activity due to their synergistic effects. Herein, we report the creation of a highly efficient, long-lasting and magnetic recyclable catalyst, composed of magnetic nickel (Ni) nanoparticles (NPs), active Pd NPs and oxygen deficient CeO2-x support. These hybrid nanostructures composed of oxygen deficient CeO2-x and active metal nanoparticles could effectively facilitate diffusion of reactant molecules and active site exposure that can dramatically accelerate the reaction rate. Impressively, the rate constant k and k/m of 4-nitrophenol reduction over 61 wt%Ni-CeO2-x/0.1 wt%Pd catalyst are respectively 0.0479 s-1 and 2.1×104 min-1 g-1, and the reaction conversion shows negligible decline even after 20 cycles. Meanwhile, the optimal 61 wt%Ni-CeO2-x/3 wt%Pd catalyst manifests remarkable catalytic activity towards styrene hydrogenation with a high TOF of 6827 molstyrene molPd-1 h-1 and a selective conversion of 100% to ethylbenzene even after eight cycles. The strong metal-support interaction (SMSI) between Ni NPs, Pd NPs and oxygen deficient CeO2-x support is beneficial for superior catalytic efficiency and stability toward hydrogenation of styrene and 4-nitrophenol. Moreover, Ni species could boost the catalytic activity of Pd due to their synergistic effect and strengthen the interaction between reactant and catalyst, which seems responsible for the great enhancement of catalytic activity. Our findings provide a new perspective to develop other high-performance and magnetically recoverable nanocatalysts, which would be widely applied to a variety of catalytic reactions.

  6. Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn

    SciTech Connect

    Gineys, N.; Aouad, G.; Sorrentino, F.; Damidot, D.

    2011-11-15

    This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C{sub 3}S, C{sub 2}S, C{sub 3}A and C{sub 4}AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C{sub 3}S, 18% C{sub 2}S, 8% C{sub 3}A and 8% C{sub 4}AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO{sub 2}) and Sn reacted with lime to form a calcium stannate (Ca{sub 2}SnO{sub 4}). Cu changed the crystallisation process and affected therefore the formation of C{sub 3}S. Indeed a high content of Cu in clinker led to the decomposition of C{sub 3}S into C{sub 2}S and of free lime. Zn, in turn, affected the formation of C{sub 3}A. Ca{sub 6}Zn{sub 3}Al{sub 4}O{sub 15} was formed whilst a tremendous reduction of C{sub 3}A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

  7. A Mild One-Step Solvothermal Route to Metal Phosphides (Metal=Co, Ni, Cu)

    NASA Astrophysics Data System (ADS)

    Xie, Y.; Su, H. L.; Qian, X. F.; Liu, X. M.; Qian, Y. T.

    2000-01-01

    Nanocrystalline Co2P, Ni2P, and Cu3P were successfully prepared through a simple solvothermal process based on the direct reactions of metal halides with yellow phosphorus at rather mild temperatures (80-140°C) with ethylenediamine used as the solvent. XRD, XPS, and TEM were used to study the phases, compositions, and morphologies of the final products. A possible mechanism is proposed and the influential factors in the process are discussed in detail.

  8. Structure and energetics of high index Fe, Al, Cu and Ni surfaces using equivalent crystal theory

    NASA Technical Reports Server (NTRS)

    Rodriguez, Agustin M.; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

    Equivalent crystal theory (ECT) is applied to the study of multilayer relaxations and surface energies of high-index faces of Fe, Al, Ni, and Cu. Changes in interplanar spacing as well as registry of planes close to the surface and the ensuing surface energies changes are discussed in reference to available experimental data and other theoretical calculations. Since ECT is a semiempirical method, the dependence of the results on the variation of the input used was investigated.

  9. Investigation of the martensitic transformation of (Cu-Zn-Ni) shape memory alloys

    NASA Astrophysics Data System (ADS)

    Naat, N. A.; Mohammed, M. A.

    2017-02-01

    (Cu-Zn-Ni) shape memory alloy with different percent have been prepared by using high frequency induction furnace under argon atmosphere. All of the specimens obtained from this alloys were heated in furnace for (15 minutes at 865°C) for homogenization and quenched in iced-water. Comparisons has been made with data obtained via differential scanning calorimetry (DSC) and energy-dispersive X-ray spectroscopy (EDS). The metallographic analyses were carried out by using optical microscopy (OM).

  10. Bulk Properties of Ni3Al(gamma') With Cu and Au Additions

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1995-01-01

    The BFS method for alloys is applied to the study of 200 alloys obtained from adding Cu and Au impurities to a Ni3Al matrix. We analyze the trends in the bulk properties of these alloys (heat of formation, lattice parameter, and bulk modulus) and detect specific alloy compositions for which these quantities have particular values. A detailed analysis of the atomic interactions that lead to the preferred ordering patterns is presented.

  11. LACBED characterization of dislocations in Cu-Al-Ni shape memory alloys processed by powder metallurgy

    NASA Astrophysics Data System (ADS)

    Rodriguez, P. P.; Ibarra, A.; San Jean, J.; Morniro, J. P.; No, M. L.

    2003-10-01

    Powder metallurgy Cu-AI-Ni shape memory alloys show excellent thermomechanical properties, being the fracture behavior close to the one observed in single crystals. However, the microstructural mechanisms responsible of such behavior are still under study. In this paper we present the characterization of the dislocations present in these alloys by Large Angle Convergent Beam Electron Diffraction (LACBED) in two different stages of the elaboration process: after HIP compaction and after hot rolling.

  12. p-type Li, Cu-codoped NiOx hole-transporting layer for efficient planar perovskite solar cells.

    PubMed

    Liu, Ming-Hua; Zhou, Zheng-Ji; Zhang, Pan-Pan; Tian, Qing-Wen; Zhou, Wen-Hui; Kou, Dong-Xing; Wu, Si-Xin

    2016-10-31

    p-type inorganic hole transport materials of Li, Cu-codoped NiOx films were deposited using a simple solution-based process. The as-prepared films were used as hole selective contacts for lead halide perovskite solar cell. An enhanced power conversion efficiency of 14.53% has been achieved due to the improved electrical conductivity and optical transmittance of the Li, Cu-codoped NiOx electrode interlayer.

  13. Petrogenesis of the Ni-Cu-PGE sulfide-bearing Tamarack Intrusive Complex, Midcontinent Rift System, Minnesota

    NASA Astrophysics Data System (ADS)

    Taranovic, Valentina; Ripley, Edward M.; Li, Chusi; Rossell, Dean

    2015-01-01

    The Tamarack Intrusive Complex (TIC, 1105.6 ± 1.2 Ma) in NE Minnesota, was emplaced during the early stages of the development of the Midcontinent Rift System (MRS, "Early Stage": 1110-1106 Ma). Country rocks of the TIC are those of the Paleoproterozoic Thomson Formation, part of the Animikie Group including sulfide-bearing metasedimentary black shale. The magmatic system is composed of at least two principal mafic-ultramafic intrusive sequences: the sulfide-barren Bowl Intrusion in the south and the "dike" area intrusions in the north which host Ni-Cu-Platinum Group Elements (PGE) mineralization with up to 2.33% Ni, 1.24% Cu, 0.34 g/t Pt, 0.23 g/t Pd and 0.18 g/t Au. Two distinct intrusive units in the "dike" area are the CGO (coarse-grained olivine-bearing) Intrusion, a sub-vertical dike-like body, and the overlying sub-horizontal FGO (fine-grained olivine-bearing) Intrusion. Both intrusions comprise peridotite, feldspathic peridotite, feldspathic pyroxenite, melatroctolite and melagabbro. Massive sulfides are volumetrically minor and mainly occur as lenses emplaced into the country rocks associated with both intrusions. Semi-massive (net-textured) sulfides are distributed at the core of the CGO Intrusion, surrounded by a halo of the disseminated sulfides. Disseminated sulfides also occur in lenses along the base of the FGO Intrusion. Olivine compositions in the CGO Intrusion are between Fo89 and Fo82 and in the FGO Intrusion from Fo84 to Fo82. TIC intrusions have more primitive olivine compositions than that of olivine in the sheet-like intrusions in the Duluth Complex (below Fo70), as well as olivine from the smaller, conduit-related, Eagle and East Eagle Intrusions in Northern Michigan (Fo86 to Fo75). The FeO/MgO ratios of the CGO and FGO Intrusion parental magmas, inferred from olivine compositions, are similar to those of picritic basalts erupted during the early stages of the MRS formation. Trace element ratios differ slightly from other intrusions in the

  14. Determination of Co, Cu, Fe, Mn, Ni and V in diesel and biodiesel samples by ETV-ICP-MST.

    PubMed

    Chaves, Eduardo S; Lepri, Fábio G; Silva, Jessee S A; de Quadros, Daiane P C; Saint'Pierre, Tatiana D; Curtius, Adilson J

    2008-10-01

    This work presents the determination of Co, Cu, Fe, Mn, Ni and V in diesel and biodiesel samples by ETV-ICP MS using emulsion sample preparation. The emulsion composition was: 1.0 g of the diesel or biodiesel sample, 2.0 mL of a 5% m/v Triton X-100 solution, 0.5 mL of HNO3 and deionized water to a 10 mL final volume. The optimized parameters were mass of carrier/modifier (1.0 microg Pd), RF power (1100 W), carrier gas flow rate (0.95 L min(-1)) and inner ETV gas flow rate (0.15 L min(-1)). The determinations were performed against aqueous solutions using 10 microg L(-1) Rh as internal standard. The accuracy of the method was verified through the analysis of the NIST 1634c reference residual fuel oil, recovery tests and comparison of the results with those obtained by GF AAS. The results were in agreement according to the t-test at a 95% confidence level. The RSD values were lower than 20%, the recoveries were between 80 and 120% and the LOD values were in the order of ng g(-1), showing the good accuracy and sensitivity of the method.

  15. Thermal behavior of Ni- and Cu-containing plasma electrolytic oxide coatings on titanium

    NASA Astrophysics Data System (ADS)

    Rudnev, V. S.; Wybornov, S.; Lukiyanchuk, I. V.; Staedler, T.; Jiang, X.; Ustinov, A. Yu.; Vasilyeva, M. S.

    2012-09-01

    In this work the effect of thermal annealing on the surface composition, structure and catalytic activity in CO oxidation of NiO + CuO/TiO2/Ti composites is studied. The composites have been obtained by a plasma electrolytic oxidation (PEO) technique, followed by impregnation in a solution of nickel (II) and copper (II) salts and air annealing. The structures contain ˜20 at% Ni and ˜12 at% Cu. It has been shown that the additional air annealing of such structures at temperature above 750 °C results in phosphate crystallization in the coatings and decreasing of Cu concentration in the surface layers. A growth of filiform nanocrystals containing mainly oxygen compounds of nickel and titanium on the coating surface takes place at the temperatures above 700 °C. The nanocrystals have a diameter of 50-200 nm and lengths below 10 μm. Such changes result in decreasing of catalytic activity of the composites in CO oxidation. At the same time the ascertained regularities may be of interest for obtaining the Ni-containing oxide catalysts with an extended surface, perspective for usage in organic catalysis or for preparing oxide nanofibers.

  16. Microwave sintering versus conventional sintering of NiCuZn ferrites. Part I: Densification evolution

    NASA Astrophysics Data System (ADS)

    Zhu, Jianhua; Ouyang, Chenxin; Xiao, Shumin; Gao, Yongyi

    2016-06-01

    This work reports the recent study on the microwave sintering (MS) versus conventional sintering (CS) of NiCuZn ferrites, with particular interests in the densification evolution. NiCuZn ferrite powders were synthesized through the solid state reaction route. Densification behaviors of ferrite samples under the two types of thermal sources were monitored in real-time. Meanwhile, the influences of additives (1 wt% BSZ glass or 1 wt% Bi2O3) on the densifications were also investigated. Both constant heating rate (CHR) and master sintering curve (MSC) models were used to evaluate the sintering activation energy (Q). Results demonstrated that the microwave-enhanced diffusion mainly occurs at the intermediate sintering stage. The Q-value estimated by MSC method agreed well with that from CHR method. With the influence of microwave electromagnetic field, the activation energy of NiCuZn ferrites was decreased by roughly 100-150 kJ/mol. In addition, doping a small amount of additives could improve densification degree and reduce the minimal energy to activate diffusion mechanisms.

  17. Removal of Cu(II) and Ni(II) from aqueous solution by lignite-based humic acids

    SciTech Connect

    Arslan, G.; Cetin, S.; Pehlivan, E.

    2007-07-01

    The removal of Cu(II) and Ni(II) metal ions from an aqueous solution were investigated by using humic acids (HAs) in a batch arrangement. HAs were prepared by using alkaline extraction, following sedimentation and acidic precipitation from three Turkish lignites: Ilgin, Beysehir, and Ermenek. The interactions of Cu(II) and Ni(II) with solid HAs and influence of three parameters (initial metal concentration, solution pH and temperature) on the removal of metals were studied. Adsorption equilibrium was achieved in about 120 min for Cu(II) and Ni(II) ions. The sorption of Cu(II) and Ni(II) on the surface of HAs depended strongly on the pH, and increased with increasing pH and the initial concentration of metal. The sorption of Cu(II) was higher than that of Ni(II) for HAs. The equilibrium relationship between adsorbent and adsorbate is described by adsorption isotherms at a fixed temperature 35 {sup o}C, at pH about 4.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. Adsorption isotherms and kinetics data of Cu(II) and Ni(II) ions removed by HAs are presented and discussed.

  18. Phase equilibria of the Sn-Ag-Cu-Ni quaternary system at the sn-rich corner

    NASA Astrophysics Data System (ADS)

    Chen, Sinn-Wen; Chang, Cheng-An

    2004-10-01

    Knowledge of phase equilibria of the Sn-Ag-Cu-Ni quaternary system at the Sn-rich corner is important for the understanding of the interfacial reactions at the Sn-Ag-Cu/Ni contacts, which are frequently encountered in recent microelectronic products. Various Sn-Ag-Cu-Ni alloys were prepared and equilibrated at 250°C. The alloys were then quenched and analyzed. The phases were determined by metallography, compositional analysis, and x-ray diffraction (XRD) analysis. No quaternary phases were found. The isoplethal sections at 60at.%Sn, 70at.%Sn, 80at.%Sn, and 90at.%Sn at 250°C are determined. The phase equilibrium relationship was proposed based on the quaternary experimental results and the 250°C isothermal sections of the four constituent ternary systems, Sn-Ag-Cu, Sn-Ag-Ni, Sn-Cu-Ni, and Cu-Ag-Ni. Because there are no ternary phases in all these three systems, all the compounds are in fact binary compounds with various solubilities of the other two elements.

  19. Assessment of Ni, Cu, Zn and Pb levels in beach and dune sands from Havana resorts, Cuba.

    PubMed

    Díaz Rizo, Oscar; Buzón González, Fran; Arado López, Juana O

    2015-11-15

    Concentrations of nickel (Ni), copper (Cu), zinc (Zn) and lead (Pb) in beach and dune sands from thirteen Havana (Cuba) resorts were estimated by X-ray fluorescence analysis. Determined mean metal contents (in mg·kg(-1)) in beach sand samples were 28±12 for Ni, 35±12 for Cu, 31±11 for Zn and 6.0±1.8 for Pb, while for dune sands were 30±15, 38±22, 37±15 and 6.8±2.9, respectively. Metal-to-iron normalization shows moderately severe and severe enrichment by Cu. The comparison with sediment quality guidelines shows that dune sands from various resorts must be considered as heavily polluted by Cu and Ni. Almost in every resort, the Ni and Cu contents exceed their corresponding TEL values and, in some resorts, the Ni PEL value. The comparison with a Havana topsoil study indicates the possible Ni and Cu natural origin.

  20. Duplex Oxide Formation during Transient Oxidation of Cu-5%Ni(001) Investigated by In situ UHV-TEM and XPS

    SciTech Connect

    Yang, J.C.; Starr, D.; Kang, Y.; Luo, L.; Tong, X.; Zhou, G.

    2012-05-20

    The transient oxidation stage of a model metal alloy thin film was characterized with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and analytic high-resolution TEM. We observed the formations of nanosized NiO and Cu{sub 2}O islands when Cu-5a5%Ni(100) was exposed to oxygen partial pressure, pO{sub 2} = 1 x 10{sup -4} Torr and various temperatures in situ. At 350 C epitaxial Cu{sub 2}O islands formed initially and then NiO islands appeared on the surface of the Cu{sub 2}O island, whereas at 750 C NiO appeared first. XPS and TEM was used to reveal a sequential formation of NiO and then Cu{sub 2}O islands at 550 C. The temperature-dependant oxide selection may be due to an increase of the diffusivity of Ni in Cu with increasing temperature.

  1. Lattice-matched bimetallic CuPd-graphene nanocatalysts for facile conversion of biomass-derived polyols to chemicals.

    PubMed

    Jin, Xin; Dang, Lianna; Lohrman, Jessica; Subramaniam, Bala; Ren, Shenqiang; Chaudhari, Raghunath V

    2013-02-26

    A bimetallic nanocatalyst with unique surface configuration displays extraordinary performance for converting biomass-derived polyols to chemicals, with potentially much broader applications in the design of novel catalysts for several reactions of industrial relevance. The synthesis of nanostructured metal catalysts containing a large population of active surface facets is critical to achieve high activity and selectivity in catalytic reactions. Here, we describe a new strategy for synthesizing copper-based nanocatalysts on reduced graphene oxide support in which the catalytically active {111} facet is achieved as the dominant surface by lattice-match engineering. This method yields highly active Cu-graphene catalysts (turnover frequency = 33-114 mol/g atom Cu/h) for converting biopolyols (glycerol, xylitol, and sorbitol) to value-added chemicals, such as lactic acid and other useful co-products consisting of diols and linear alcohols. Palladium incorporation in the Cu-graphene system in trace amounts results in a tandem synergistic system in which the hydrogen generated in situ from polyols is used for sequential hydrogenolysis of the feedstock itself. Furthermore, the Pd addition remarkably enhances the overall stability of the nanocatalysts. The insights gained from this synthetic methodology open new vistas for exploiting graphene-based supports to develop novel and improved metal-based catalysts for a variety of heterogeneous catalytic reactions.

  2. Effects of Cd, Cu, Ni, and Zn on brown tide alga Aureococcus anophagefferens growth and metal accumulation.

    PubMed

    Wang, Bin; Axe, Lisa; Michalopoulou, Zoi-Heleni; Wei, Liping

    2012-01-03

    Trace metals play important roles in regulating phytoplankton growth and could influence algal bloom development. Laboratory studies were conducted to evaluate the influence of environmentally relevant concentrations of Cd, Cu, Ni, and Zn on Aureococcus anophagefferens bloom (brown tide) development. Results show that the elevated Ni(2+) concentrations, e.g. those of brown tide waters in the northeastern US, greatly stimulated A. anophagefferens growth (as compared to the control without Ni addition), yet, only low amounts of dissolved Ni were sequestered, thus leaving excessive Ni directly promoting A. anophagefferens blooms. The medium effective concentration EC(50) (Me(2+)) suggests A. anophagefferens has similar Cd sensitivity but much greater Cu tolerance as compared to cyanobacteria, as such, excessive Cu could indirectly promote A. anophagefferens blooms by inhibiting competitors such as Synechococcus sp. The effects of Ni and Cu promoting growth are consistent with the recent genomic study of this alga. In addition, Zn(2+) concentrations lower than those in brown tide waters enhance A. anophagefferens growth, but Zn sequestration in A. anophagefferens would not substantially reduce total dissolved Zn in these waters. Overall, this study, showing that excessive Cu and Ni likely promote brown tides, provides evidence for trace metal linkages in algal bloom development.

  3. Novel chiral magnetic domain wall structure in Fe/Ni/Cu(001) films.

    PubMed

    Chen, G; Zhu, J; Quesada, A; Li, J; N'Diaye, A T; Huo, Y; Ma, T P; Chen, Y; Kwon, H Y; Won, C; Qiu, Z Q; Schmid, A K; Wu, Y Z

    2013-04-26

    Using spin-polarized low energy electron microscopy, we discovered a new type of domain wall structure in perpendicularly magnetized Fe/Ni bilayers grown epitaxially on Cu(100). Specifically, we observed unexpected Néel-type walls with fixed chirality in the magnetic stripe phase. Furthermore, we find that the chirality of the domain walls is determined by the film growth order with the chirality being right handed in Fe/Ni bilayers and left handed in Ni/Fe bilayers, suggesting that the underlying mechanism is the Dzyaloshinskii-Moriya interaction at the film interfaces. Our observations may open a new route to control chiral spin structures using interfacial engineering in transition metal heterostructures.

  4. The nature of chemisorbed oxygen on Ni(100) and Cu(100)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Walch, S. P.; Bagus, P. S.; Brundle, C. R.

    1984-01-01

    Model calculations indicate two low-lying states for the interaction of O with Ni and Cu(100). The oxide state is approximately 1 eV more stable and its R(perpendicular) for Ni(100) is consistent with the experimental value for Ni(100), indicating only one type of stable chemisorption bond. This agrees with XPS (X-ray photoemission spectroscopy) and EXAFS (extended X-ray absorption fine structure) data for the observed LEED (low energy electron diffraction) structures. Interpretations of EELS (electron energy loss spectroscopy) data in terms of a radical state forthe p(2x2) and the oxide state for the c(2x2) structure must be seriously questioned.

  5. Growth of Graphene by Catalytic Dissociation of Ethylene on CuNi(111)

    NASA Astrophysics Data System (ADS)

    Tyagi, Parul; Mowll, Tyler; Robinson, Zachary; Ventrice, Carl

    2013-03-01

    Copper foil is one of the most common substrates for growing large area graphene films. The main reason for this is that Cu has a very low carbon solubility, which results in the self-termination of a single layer of graphene when grown using hydrocarbon precursors at low pressure. Our previous results on Cu(111) substrates has found that temperatures of at least 900 °C are needed to form single domain epitaxial films. By using a CuNi alloy, the catalytic activity of the substrate is expected to increase, which will allow the catalytic decomposition of the hydrocarbon precursor at lower temperatures. In this study, the growth of graphene by the catalytic decomposition of ethylene on a 90:10 CuNi(111) substrate was attempted. The growths were done in an ultra-high vacuum system by either heating the substrate to the growth temperature followed by introducing the ethylene precursor or by introducing the ethylene precursor and subsequently heating it to the growth temperature. The growth using the former method results in a two-domain epitaxial graphene overlayer. However, introducing the ethylene before heating the substrate resulted in considerable rotational disorder within the graphene film. This has been attributed to the deposition of carbon atoms on the surface at temperatures too low for the carbon to crystallize into graphene. This research was supported by the NSF (DMR-1006411).

  6. H2 production by the photocatalytic reforming of cellulose and raw biomass using Ni, Pd, Pt and Au on titania

    PubMed Central

    Jones, W.; Hardacre, C.; Bowker, M.

    2016-01-01

    Here, we report a method for sustainable hydrogen production using sunlight and biomass. It is shown that cellulose can be photoreformed to produce hydrogen, even in solid form, by use of metal-loaded titania photocatalysts. The experiments performed verified that the process is enabled by initial hydrolysis via glucose, which itself is shown to be efficiently converted to produce hydrogen by photocatalysis. Importantly, it is shown that not only precious metals such as Pt, Pd and Au can be used as the metal component, but also much more economic and less environmentally damaging Ni is effective. Even more importantly, we show for the first time, to the best our knowledge, that fescue grass as raw biomass can be effective for hydrogen production without significant pre-treatment. This provides additional benefits for the efficiency of biomass hydrogen production, because fewer processing steps for the raw material are required than in the production of purer forms of cellulose, for example. PMID:27493561

  7. A Strategy for Fabricating Porous PdNi@Pt Core-shell Nanostructures and Their Enhanced Activity and Durability for the Methanol Electrooxidation

    PubMed Central

    Liu, Xinyu; Xu, Guangrui; Chen, Yu; Lu, Tianhong; Tang, Yawen; Xing, Wei

    2015-01-01

    Three-dimensionally (3D) porous morphology of nanostructures can effectively improve their electrocatalytic activity and durability for various electrochemical reactions owing to big surface area and interconnected structure. Cyanogel, a jelly-like inorganic polymer, can be used to synthesize various three-dimensionally (3D) porous alloy nanomaterials owing to its double-metal property and particular 3D backbone. Here, 3D porous PdNi@Pt core-shell nanostructures (CSNSs) are facilely synthesized by first preparing the Pd-Ni alloy networks (Pd-Ni ANWs) core via cyanogel-reduction method followed by a galvanic displacement reaction to generate the Pt-rich shell. The as-synthesized PdNi@Pt CSNSs exhibit a much improved catalytic activity and durability for the methanol oxidation reaction (MOR) in the acidic media compared to the commercial used Pt black because of their specific structural characteristics. The facile and mild method described herein is highly attractive for the synthisis of 3D porous core-shell nanostructures. PMID:25557190

  8. Atomic and electronic structure of Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass from ab initio simulations

    SciTech Connect

    Kumar, Vijay; Fujita, T.; Chen, M. W.; Inoue, A.; Konno, K.; Matsuura, M.; Kawazoe, Y.

    2011-10-01

    The atomic structure of Pd{sub 40}Ni{sub 40}P{sub 20} bulk metallic glass has been simulated using an ab initio molecular dynamics method with projector-augmented wave pseudopotentials for electron-ion interaction and generalized gradient approximation for exchange-correlation energy. The calculated extended x-ray absorption fine structure (EXAFS) spectra of Pd-K and Ni-K edges, the mass density, and the electronic structure agree remarkably well with the available experimental data and the EXAFS spectra measured at the SPring-8 synchrotron radiation facility. Our results show that the atomic structure can be described in terms of P-centered polyhedra. There are no two P atoms that are nearest neighbors at this composition, and this could be a reason for the observed optimal P concentration of about 20 at.%. The neighboring polyhedra share metal (M) atoms and form a polar covalently bonded random network of P-M-P favoring certain angles. The remaining M atoms act as metallic glue with a tendency of nanoscale clustering of Pd-Pd and Ni-Ni atoms.

  9. Pd/In/Ni/Au contact to N-polar n-type GaN fabricated by laser lift-off

    NASA Astrophysics Data System (ADS)

    Ma, J.; Chen, Z. Z.; Jiang, S.; Jiao, Q. Q.; Li, J. Z.; Jiang, S. X.; Feng, Y. L.; Yu, T. J.; Zhang, G. Y.

    2015-04-01

    Pd/In/Ni/Au contacts to N-polar n-GaN were investigated to obtain low contact resistance and high thermal stability contacts. Two-step thermal annealing method was developed to form the PdIn and InGaN alloys successively, which were clarified by Auger electron spectroscopy and transmission electron microscopy measurements. The lowest specific contact resistivity was achieved as 5.4 × 10-5 Ω cm2 when the sample was annealed under 250 °C for 600 s and 500 °C for 30 s in N2 ambient in sequence. It was observed that Pd/In fusion was occurred at the first annealing step. The PdIn alloy can well act as the blocking layer to prevent the outdiffusion of Ga atoms from n-GaN and low work function material as well. The second annealing step led to some content InGaN formation. PdIn contact to InGaN may get a small Schottky barrier height and some effective electron accumulation at the GaN/InGaN interface, which decreases the specific contact resistivity of Pd/In/Ni/Au to N-polar n-GaN.

  10. Mechanism of phenol oxidation by heterodinuclear Ni Cu bis(μ-oxo) complexes involving nucleophilic oxo groups

    PubMed Central

    Kundu, Subrata; Miceli, Enrico; Farquhar, Erik R.

    2014-01-01

    Oxidation of phenols by heterodinuclear CuIII(μ-O)2NiIII complexes containing nucleophilic oxo groups occurs by both proton coupled electron transfer (PCET) and hydrogen atom transfer (HAT) mechanisms; the exact mechanism depends on the nature of the phenol as well as the substitution pattern of the ligand bound to Cu. PMID:24362244

  11. Validation of an air-liquid interface toxicological set-up using Cu, Pd, and Ag well-characterized nanostructured aggregates and spheres

    NASA Astrophysics Data System (ADS)

    Svensson, C. R.; Ameer, S. S.; Ludvigsson, L.; Ali, N.; Alhamdow, A.; Messing, M. E.; Pagels, J.; Gudmundsson, A.; Bohgard, M.; Sanfins, E.; Kåredal, M.; Broberg, K.; Rissler, J.

    2016-04-01

    Systems for studying the toxicity of metal aggregates on the airways are normally not suited for evaluating the effects of individual particle characteristics. This study validates a set-up for toxicological studies of metal aggregates using an air-liquid interface approach. The set-up used a spark discharge generator capable of generating aerosol metal aggregate particles and sintered near spheres. The set-up also contained an exposure chamber, The Nano Aerosol Chamber for In Vitro Toxicity (NACIVT). The system facilitates online characterization capabilities of mass mobility, mass concentration, and number size distribution to determine the exposure. By dilution, the desired exposure level was controlled. Primary and cancerous airway cells were exposed to copper (Cu), palladium (Pd), and silver (Ag) aggregates, 50-150 nm in median diameter. The aggregates were composed of primary particles <10 nm in diameter. For Cu and Pd, an exposure of sintered aerosol particles was also produced. The doses of the particles were expressed as particle numbers, masses, and surface areas. For the Cu, Pd, and Ag aerosol particles, a range of mass surface concentrations on the air-liquid interface of 0.4-10.7, 0.9-46.6, and 0.1-1.4 µg/cm2, respectively, were achieved. Viability was measured by WST-1 assay, cytokines (Il-6, Il-8, TNF-a, MCP) by Luminex technology. Statistically significant effects and dose response on cytokine expression were observed for SAEC cells after exposure to Cu, Pd, or Ag particles. Also, a positive dose response was observed for SAEC viability after Cu exposure. For A549 cells, statistically significant effects on viability were observed after exposure to Cu and Pd particles. The set-up produced a stable flow of aerosol particles with an exposure and dose expressed in terms of number, mass, and surface area. Exposure-related effects on the airway cellular models could be asserted.

  12. Giant magnetic coercivity in YNi4B-type SmNi3TB (T=Mn-Cu) solid solutions

    NASA Astrophysics Data System (ADS)

    Yao, Jinlei; Yan, Chang; Yapaskurt, V. O.; Morozkin, A. V.

    2016-12-01

    The effects of transition metal substitution for Ni on the magnetic properties of the YNi4B-type SmNi4B via SmNi3TB (T=Mn, Fe, Co, Cu) solid solutions have been investigated. SmNi4B, SmNi3MnB, SmNi3FeB, SmNi3CoB and SmNi3CuB show ferromagnetic ordering at 40 K, 210 K, 322 K, 90 K and 57 K and field sensitive metamagnetic-like transitions at 15 K, 100 K, 185 K, 55 K and 15 K in a magnetic field of 10 kOe, respectively. The magnetocaloric effects of SmNi3TB (T=Mn-Cu) were calculated in terms of isothermal magnetic entropy change (ΔSm). The magnetic entropy ΔSm reaches value of -0.94 J/kg K at 40 K for SmNi4B, -1.5 J/kg K at 205 K for SmNi3MnB, -0.54 J/kg K at 320 K for SmNi3FeB, -0.49 J/kg K at 90 K for SmNi3CoB and -0.54 J/kg K at 60 K for SmNi3CuB in field change of 0-50 kOe around the Curie temperature. They show positive ΔSm of +0.71 J/kg K at ~10 K for SmNi4B, +1.69 J/kg K at 30 K for SmNi3MnB, +0.89 J/kg K at 110 K for SmNi3FeB, +1.08 J/kg K at 25 K for SmNi3CoB and +1.12 J/kg K at 10 K for SmNi3CuB in field change of 0-50 kOe around the low temperature metamagnetic-like transition. Below the field induced transition temperature (change of magnetic structure), SmNi3TB (T=Mn-Cu) exhibits giant magnetic coercivity of 74 kOe at 5 K for SmNi4B, 69 kOe at 20 K (90 kOe at 10 K) for SmNi3MnB, 77 kOe at 60 K for SmNi3FeB, 88 kOe at 20 K for SmNi3CoB and 52 kOe at 5 K for SmNi3CuB.

  13. A Study on the Effect of Ni Dopping on Bi-Pb-Sr-Ca-Cu-O System

    NASA Astrophysics Data System (ADS)

    Tepe, M.; Abukay, D.

    1998-01-01

    The effect of Ni doping on superconductivity properties of the Bi1.7Pb0.3Sr2Ca2(Cu1-xNix)3Oy system has been investigated by means of x-ray diffraction, ac electrical resistance, ac magnetic susceptibility and critical current measurements. The volume fraction of the 2223 phase decreases with increasing Ni concentration. The zero-resistance temperature and the critical current density are suppressed with Ni substitution.

  14. Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

    NASA Astrophysics Data System (ADS)

    Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

    2014-10-01

    Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

  15. Electroless Ni-Cu-P/nano-graphite composite coatings for bipolar plates of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Kuo

    2012-12-01

    This study evaluates the effects of an electroless Ni-Cu-P/nano-graphite composite coating on the surface characteristics of anodized 5083 aluminum alloy, including electrical resistivity, corrosion resistance of the alloy in a simulated solution of 0.5 M H2SO4 + 2 ppm NaF in polymer electrolyte membrane fuel cells (PEMFCs). The co-deposition and adhesion of the composite coatings on a 5083 substrate are enhanced by an anodizing process. The electroless Ni-Cu-P plating solution is prepared by adding different CuSO4·5H2O concentrations into the electroless Ni-P plating solution and adding nano-graphite (15-40 nm) particles to form the Ni-Cu-P/nano-graphite composite coatings. Experimental results indicate that the electroless Ni-Cu-P/nano-graphite composite coating enhances the hardness, conductivity, corrosion resistance of the 5083 substrate in the corrosive solution. The anodizing treatment enhances the electroless composite coatings by providing better uniformity, density, and adhesion compared to substrate without anodizing treatment. The electroless Ni-Cu-P/nano-graphite composite coating deposited on the optimal anodized 5083 substrate at a low CuSO4·5H2O concentration of 0.25 g l-1 with 20 g l-1 nano-graphite added have the best surface structure, highest hardness, electrical conductivity and corrosion resistance. Therefore, this novel electroless Ni-Cu-P/nano-graphite composite-coated 5083 aluminum alloy has potential applications in bipolar plates of PEM fuel cells.

  16. Microstructural Evolution of Brazed CP-Ti Using the Clad Ti-20Zr-20Cu-20Ni Foil

    NASA Astrophysics Data System (ADS)

    Yeh, Tze-Yang; Shiue, Ren-Kae; Chang, Chenchung Steve

    2013-01-01

    Microstructural evolution of the clad Ti-20Zr-20Cu-20Ni foil brazed CP-Ti alloy has been investigated. For the specimen furnace brazed below 1143 K (870 °C), the joint is dominated by coarse eutectic and fine eutectoid structures. Increasing the brazing temperature above 1163 K (890 °C) results in disappearance of coarse eutectic structure, and the joint is mainly comprised of a fine eutectoid of (Ti,Zr)2Ni, Ti2Cu, Ti2Ni, and α-Ti.

  17. Evolution of morphology and structure with growth of thickness of condensed films of Pd-Cu on a surface with open porosity

    NASA Astrophysics Data System (ADS)

    Presnyakov, M. Yu.; Sladkopevtsev, B. V.; Belonogov, E. K.

    2016-12-01

    Cross sections obtained by the method of a focused ion beam and fractures of the PdCu/Al2O3 nanocomposite synthesized by magnetron sputtering (MS) of alloy-type target PdCu and condensation in vacuum on the surface of nanoporous Al2O3 produced by anodic oxidation of aluminum foil are investigated using the methods of high-resolution scanning electron microscopy implemented on the basis of a Helios 600i setup (FEI, United States). Regularities of the formation of the structure and morphology of crystallites of vacuum condensate of Pd-Cu solid solution with a thickness of 0.1-4 μm on a surface with open porosity are disclosed. Approaches to the formation of the gradient structures near a free surface are discussed, and the conditions of the initiation of MS mechanisms of the formation of discrete, porous, and anisotropic condensates are found. Approaches to nonselective filling of nanopores in a dielectric by metal clusters and forming of the gradient structure of the nanocomposite PdCu/Al2O3 are carried out.

  18. Catalytic reduction of nitrate in secondary effluent of wastewater treatment plants by Fe(0) and Pd-Cu/γ-Al2O3.

    PubMed

    Yun, Yupan; Li, Zifu; Chen, Yi-Hung; Saino, Mayiani; Cheng, Shikun; Zheng, Lei

    2016-01-01

    Total nitrogen, in which NO3(-) is dominant in the effluent of most wastewater treatment plants, cannot meet the requirements of the Chinese wastewater discharge standard (<15 mg/L), making nitrate (NO3(-)) elimination attract considerable attention. In this study, reductant iron (Fe(0)) and γ-Al2O3 supported palladium-copper bimetallic catalysts (Pd-Cu/γ-Al2O3) were innovatively used for the chemical catalytic reduction of nitrate in wastewater. A series of specific operational conditions (such as mass ratio of Pd:Cu, catalyst amounts, reaction time and pH of solution) were optimized for nitrate reduction in the artificial solution, and then the selected optimal conditions were further applied for investigating the nitrate elimination of secondary effluent of a wastewater treatment plant in Beijing, China. Results indicated that a better catalytic performance (74% of nitrate removal and 62% of N2 selectivity) could be obtained under the optimal condition: 5 g/L Fe(0), 3:1 mass ratio (Pd:Cu), 4 g/L catalyst, 2 h reaction time and pH 5.1. It is noteworthy to point out that nitrogen gas (N2) predominated in the byproducts without another system to treat ammonium and nitrite. Therefore, the chemical catalytic reduction combining Fe(0) with Pd-Cu/γ-Al2O3 could be regarded as a better alternative for nitrate removal in wastewater treatment.

  19. Bortnikovite, Pd4Cu3Zn, a new mineral species from the unique Konder placer deposit, Khabarovsk krai, Russia

    NASA Astrophysics Data System (ADS)

    Mochalov, A. G.; Tolkachev, M. D.; Polekhovsky, Yu. S.; Goryacheva, E. M.

    2007-08-01

    Bortnikovite, a new mineral species that is an intermetallic compound of Pd, Cu, and Zn with the simplified formula Pd4Cu3Zn has been detected at the unique Konder placer deposit in the Ayan-Maya district, Khabarovsk krai. The primary source of this placer is a concentrically zoned alkaline ultramafic massif. The X-ray diffraction pattern is indexed on the assumption of a tetragonal unit cell: a = 6.00 ± 0.02 Å and c = 8.50 ± 0.03 Å, V = 306 ± 0.01 Å3, Z = 3, probable space group P4/mmm. The calculated density is 11.16 g/cm3; the mean microhardness VHN is 368 kg/mm2. In reflected light, the new mineral is white with a slight grayish beige tint; bireflectance, anisotropy, and internal reflections are not observed. The reflectance spectrum belongs to the concave group of the anomalous type. The measured values of reflectance are as follows: 56.9 (470 nm), 61.7 (546 nm), 63.4 (589 nm), and 65.4% (650 nm). The new mineral is intergrown with isoferroplatinum, titanite, perovskite, V-bearing magnetite, bornite, and chlorite. The origin of bortnikovite is related to the effect of alkaline fluid on ultramafic rocks. The new mineral is named in honor of Professor Nikolai Stefanovich Bortnikov, a prominent mineralogist and researcher of ore deposits and a corresponding member of the Russian Academy of Sciences. Bortnikovite is the first platinum group mineral that contains Zn as a major mineralforming element.

  20. Pd/Cu-Catalyzed tandem head-to-tail dimerization/cycloisomerization of terminal ynamides for the synthesis of 5-vinyloxazolones.

    PubMed

    Tang, Luning; Huang, Hai; Xi, Yang; He, Guangke; Zhu, Hongjun

    2017-04-05

    An attractive and novel methodology involving Pd/Cu-catalyzed tandem head-to-tail dimerization/cycloisomerization of terminal ynamides for the synthesis of 3,5-disubstituted oxazolones was developed. Under Pd(PPh3)2Cl2/CuI cooperative catalyzed reaction conditions, it provided efficient access to 5-vinyloxazolones with exceptional functional group tolerance and good chemoselectivity. The control experiments demonstrated that Pd(PPh3)2Cl2 serves a key role in the dimerization of terminal ynamides and shows low catalytic activity in the intramolecular cyclization. Moreover, the hetero-Diels-Alder reaction of product 5-vinyloxazolones was also described, which provided polycyclic oxazolones in good yield.

  1. First-principles study of the mechanical properties of NiAl microalloyed by M (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd)

    NASA Astrophysics Data System (ADS)

    Zhang, Caili; Han, Peide; Li, Jinmin; Chi, Mei; Yan, Lingyun; Liu, Yanping; Liu, Xuguang; Xu, Bingshe

    2008-05-01

    Structural, electronic and elastic properties for NiAl with 4d alloying elements M (Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd) have been studied using the first-principles pseudopotential density functional method within a generalized gradient approximation. From the elastic constants, C11, C12, C44, bulk modulus B0, Young's modulus E, the shear modulus G, the ratios of shear modulus to bulk modulus G/B0, negative Cauchy pressure parameter (C12 - C44) and Poisson's ratio ν calculated after structural full relaxation, M (Tc, Ru, Rh, Pd) alloying addition in NiAl has been shown to increase the stiffness of NiAl and improve its ductility. The density of states and charge density contour involving alloying additions of Ru were further investigated to clarify the electronic causes of the alloying additions.

  2. Magnetism of coherent Co and Ni thin films on Cu(111) and Au(111) substrates: An ab initio study

    NASA Astrophysics Data System (ADS)

    Zelený, Martin; Dlouhý, Ivo

    2017-02-01

    We present an ab initio study of structural and magnetic properties of coherent Co and Ni thin films on Cu(111) and Au(111) substrates with thicknesses of up to 6 monolayers. All studied films on Cu(111) substrates prefer structures close their ground state (hcp for Co and fcc for Ni), whereas only the hcp stacking sequence has been found for both films on Au(111) substrates. All studied films exhibit instability of the first monolayer with respect to decomposition into 2-monolayer- or 3-monolayer-high islands, which is in agreement with experimental findings. All studied films are also ferromagnetic, nevertheless the Ni/Cu(111) films reduce their magnetic moments in the layer adjacent to the substrate due to a stronger Cu-Ni interaction at the interface. The magnetic anisotropy of a Co film does not depend on the film thickness: all the studied Co/Au(111) films exhibit a perpendicular magnetic anisotropy, whereas all the Co/Cu(111) films prefer in-plane magnetization. On the other hand, both Ni films change their preference for in-plane orientation of their easy axis to out-of-plane orientation at a critical thickness of 2 monolayers, however, the magnetic anisotropy energies for films thicker than 1 monolayer are smaller than 1 meV/Ni atom. These behaviors of magnetic anisotropy do not depend on the structure of the studied films.

  3. Ni interferes in the Cu-regulated transcriptional switch petJ/petE in Synechocystis sp. PCC 6803.

    PubMed

    Giner-Lamia, Joaquín; López-Maury, Luis; Florencio, Francisco J

    2016-10-01

    Plastocyanin (petE) plays an essential role in photosynthesis as an electron carrier between cytochrome b6 f and photosystem I, and in some cyanobacteria it can be replaced by the haem-containing protein, cytochrome c6 (petJ). In Synechocystis sp. PCC 6803, transcription of petE and petJ is activated and repressed, respectively, by Cu. Here, we show that Ni can act similarly to Cu in inducing petE and repressing petJ, thus leading to a partial switch between cytochrome c6 and plastocyanin. Transcription of these genes is only altered by Ni in Cu-depleted medium, and none of the Ni-dependent transcription factors described in Synechocystis, NrsR and InrS seem to be involved in this regulation. Finally, we show that plastocyanin is essential for growth under conditions of excess Ni.

  4. On the Mechanism of Pd(0)-Catalyzed, Cu(I) Carboxylate-Mediated Thioorganic-Boronic Acid Desulfitative Coupling. A Non-innocent Role for Carboxylate Ligand

    PubMed Central

    Musaev, Djamaladdin G.; Liebeskind, Lanny S.

    2009-01-01

    Computational studies of the mechanism of the Pd-catalyzed, Cu(I)-carboxylate-mediated desulfitative coupling of thioorganics with boronic acids have determined that the requisite Cu(I)-carboxylate plays multiple important roles. The Cu(I)-carboxylate enhances both the transmetalation and the C-C reductive elimination steps: it acts as a reactive transmetalation center and it provides a vital carboxylate ligand. The carboxylate ligand functions not only as an activator for the boronic acid, but it also displaces a phosphine ligand at the palladium center generating a catalytically competent mono-phosphine-palladium intermediate. PMID:20161122

  5. Ti-based glassy alloys in Ti-Cu-Zr-Sn system

    NASA Astrophysics Data System (ADS)

    Wang, ZengRui; Dong, DanDan; Qiang, JianBing; Wang, Qing; Wang, YingMin; Dong, Chuang

    2013-07-01

    Bulk amorphous formation in Ti-Cu-based multicomponent alloys, free of Ni, Pd and Be elements, were studied using the cluster-plus-glue-atom model. The basic cluster formula was revealed as [Ti9Cu6]Cu3 to explain the best binary glass forming composition Ti50Cu50=Ti9Cu9, where the CN14 rhombi-dodecahedron Ti9Cu6 was the principal cluster in the devitrification phase CuTi. This basic cluster formula was further alloyed with Zr and Sn and a critical glass forming ability was reached at (Ti7.2Zr1.8)(Cu8.72Sn0.28) and (Ti7.2Zr1.8)(Cu8.45Sn0.55) up to 5 mm in diameter by suction casting, which was the largest in Ti-Cu-based and Ni-, Pd- and Be-free alloys.

  6. Geological and petrological aspects of Ni-Cu-PGE mineralization in the early Paleoproterozoic Monchegorsk layered mafic-ultramafic complex, Kola Peninsula

    NASA Astrophysics Data System (ADS)

    Sharkov, E. V.; Chistyakov, A. V.

    2014-05-01

    The Early Paleoproterozoic Monchegorsk Complex comprises two independent large layered mafic-ultramafic intrusions: the Monchegorsk pluton and the Main Range massif formed about 2.50 and 2.46 Ga ago, respectively. They are composed of similar cumulates, though they differ somewhat in the isotopic parameters of rocks, cumulate stratigraphy and derived from siliceous high-Mg series melts that arose in the same large long-living volcanic center. The economic syngenetic Ni-Cu-PGE sulfide mineralization related to the earlier Monchegorsk pluton is represented by two types of ores. The first type, pertaining to fractionation of the primary melt, is opposite to the reef formed due to injection of a special ore-bearing melt into the solidifying intrusive chamber. The primary magmatic mineralization is largely composed of Ni-Fe-Cu sulfides and Pd-Pt sulfides, bismuthides, and tellurides. Only small PGE and probably chromite occurrences are related to the Main Range massif. In the Mid-Paleoproterozoic (2.0-1.9 Ga), the complex was transformed into a collage of tectonic blocks confined to the regional fault zone. The Monchegorsk pluton was retained better, and only rocks of its southern framework were involved into tectonic and metamorphic reworking with the formation of economic metamorphic low-sulfide PGE mineralization with widespread Pd and Pt telluro-bismuthides, arsenides, stannides, antimonides, and selenides. The ore formation was accompanied by PGE redistribution and segregation of lenticular orebodies with diffuse contours. Thus, the Monchegorsk ore cluster is characterized by juxtaposition of unaltered primary magmatic deposits and those formed as a result of their metamorphism and distinguished from the former by structure and composition. The comparative study of these deposits opens up new possibilities for comprehending ore-forming processes in the same situations.

  7. β-Decay half-lives of 76,77Co, 79,80Ni, and 81Cu: experimental indication of a doubly magic 78Ni.

    PubMed

    Xu, Z Y; Nishimura, S; Lorusso, G; Browne, F; Doornenbal, P; Gey, G; Jung, H-S; Li, Z; Niikura, M; Söderström, P-A; Sumikama, T; Taprogge, J; Vajta, Zs; Watanabe, H; Wu, J; Yagi, A; Yoshinaga, K; Baba, H; Franchoo, S; Isobe, T; John, P R; Kojouharov, I; Kubono, S; Kurz, N; Matea, I; Matsui, K; Mengoni, D; Morfouace, P; Napoli, D R; Naqvi, F; Nishibata, H; Odahara, A; Sahin, E; Sakurai, H; Schaffner, H; Stefan, I G; Suzuki, D; Taniuchi, R; Werner, V

    2014-07-18

    The half-lives of 20 neutron-rich nuclei with Z=27-30 have been measured at the RIBF, including five new half-lives of (76)Co(21.7(-4.9)(+6.5) ms), (77)Co(13.0(-4.3)(+7.2) ms), (79)Ni(43.0(-7.5)(+8.6) ms), (80)Ni(23.9(-17.2)(+26.0) ms), and (81)Cu(73.2 ± 6.8 ms). In addition, the half-lives of (73-75)Co, (74-78)Ni, (78-80)Cu, and (80-82)Zn were determined with higher precision than previous works. Based on these new results, a systematic study of the β-decay half-lives has been carried out, which suggests a sizable magicity for both the proton number Z = 28 and the neutron number N=50 in (78)Ni.

  8. β-Decay Half-Lives of Co76,77, Ni79,80, and Cu81: Experimental Indication of a Doubly Magic Ni78

    NASA Astrophysics Data System (ADS)

    Xu, Z. Y.; Nishimura, S.; Lorusso, G.; Browne, F.; Doornenbal, P.; Gey, G.; Jung, H.-S.; Li, Z.; Niikura, M.; Söderström, P.-A.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Watanabe, H.; Wu, J.; Yagi, A.; Yoshinaga, K.; Baba, H.; Franchoo, S.; Isobe, T.; John, P. R.; Kojouharov, I.; Kubono, S.; Kurz, N.; Matea, I.; Matsui, K.; Mengoni, D.; Morfouace, P.; Napoli, D. R.; Naqvi, F.; Nishibata, H.; Odahara, A.; Şahin, E.; Sakurai, H.; Schaffner, H.; Stefan, I. G.; Suzuki, D.; Taniuchi, R.; Werner, V.

    2014-07-01

    The half-lives of 20 neutron-rich nuclei with Z =27-30 have been measured at the RIBF, including five new half-lives of Co76(21.7-4.9+6.5 ms), Co77(13.0-4.3+7.2 ms), Ni79(43.0-7.5+8.6 ms), Ni80(23.9-17.2+26.0 ms), and Cu81(73.2±6.8 ms). In addition, the half-lives of Co73-75, Ni74-78, Cu78-80, and Zn80-82 were determined with higher precision than previous works. Based on these new results, a systematic study of the β-decay half-lives has been carried out, which suggests a sizable magicity for both the proton number Z =28 and the neutron number N=50 in Ni78.

  9. Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

    NASA Astrophysics Data System (ADS)

    Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

    2014-12-01

    Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 °C to 809 °C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

  10. Structural transformations in high-capacity Li2Cu0.5Ni0.5O2 cathodes

    DOE PAGES

    Ruther, Rose E.; Pandian, Amaresh Samuthira; Yan, Pengfei; ...

    2017-03-09

    Cathode materials that can cycle >1 Li+ per transition metal are of substantial interest for increasing the overall energy density of lithium-ion batteries. Li2Cu0.5Ni0.5O2 has a very high theoretical capacity of ~500 mAh/g assuming both Li+ ions are cycled reversibly. The Cu2+/3+ and Ni2+/3+/4+ redox couples are also at high voltage, which could further boost the energy density of this system. Despite such promise, Li2Cu0.5Ni0.5O2 undergoes irreversible phase changes during charge (delithiation) that result in large first-cycle irreversible loss and poor long-term cycling stability. Oxygen evolves before the Cu2+/3+ or Ni3+/4+ transitions are accessed. In this contribution, X-ray diffraction, transmissionmore » electron microscopy (TEM), and transmission X-ray microscopy combined with X-ray absorption near edge structure (TXM–XANES) are used to follow the chemical and structural changes that occur in Li2Cu0.5Ni0.5O2 during electrochemical cycling. Li2Cu0.5Ni0.5O2 is a solid solution of orthorhombic Li2CuO2 and Li2NiO2, but the structural changes more closely mimic the changes that the Li2NiO2 endmember undergoes. Li2Cu0.5Ni0.5O2 loses long-range order during charge, but TEM analysis provides clear evidence of particle exfoliation and the transformation from orthorhombic to a partially layered structure. Linear combination fitting and principal component analysis of TXM–XANES are used to map the different phases that emerge during cycling ex situ and in situ. Lastly, significant changes in the XANES at the Cu and Ni K-edges correlate with the onset of oxygen evolution.« less

  11. Thermochemistry of YBa(2)Cu(3-x)M(x)O(y) (M=Ni,Zn)

    SciTech Connect

    Licci, Francesca; Navrotsky, Alexandra; Rodriguez, Mark A.

    1999-07-14

    Many studies have investigated the behavior of transition metal dopants in the YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} 123 superconductors. Much of this research has focused on the effects of metal ions such as Co, Fe, Zn, Ni when they are substituted for the copper ions at Cu(1) and Cu(2) sites, commonly referred to as the chain and plane sites, respectively. Trivalent ions such as Co{sup +3} and Fe{sup +3}have been shown to behave similarly in their substitution effects, displaying site preference on the Cu(1) site [3-8]. This site preference has been established with the use of techniques such as neutron diffraction and Moessbauer spectroscopy [4,5]. Thermogravimetry, electron diffraction, and analysis of lattice parameters as a function of dopant also yield results consistent with those of the structural studies with respect to the chain site preference of both Co and Fe [3,4,6-8]. The very fast convergence of a and b lattice parameters to that of the tetragonal structure, occurring at x = 0.3 Co dopant (i.e. YBa{sub 2}Cu{sub 2.7}Co{sub 0.3}O{sub 7{minus}{delta}}) for high-oxygen-content samples, coupled with information derived from diffuse scattering and oxidation behavior of these samples, has been described in detail by several authors in terms of the Co and Fe ions creating ''microchains'' at Cu(1) sites within the 123 compound [4,7-8]. The Cu(1) site dopants decrease T{sub c} at a rate of 2 to 5 K/at. %, varying to some extent with site preference [4,9].

  12. Microstructure, Melting and Wetting Properties of Pd-Ag-CuO Air Braze on Alumina

    SciTech Connect

    Darsell, Jens T.; Hardy, John S.; Kim, Jin Yong Y.; Weil, K. Scott

    2005-03-19

    A reactive air brazing (RAB) technique utilizing silver-copper oxide (Ag-CuO) alloys has previously been developed for joining ceramics components used in high temperature devices ranging from oxygen separation membranes, gas turbines and combustion engines. The application of the Ag-CuO system as a brazing material is limited by its solidus and liquidus temperatures, which are known to be in the range of 935 C and 967 C. Some joined ceramic components may be used in devices, which require further processing steps, or may be used in applications, that exceed these temperatures. It has been found that the addition of palladium to the silver copper oxide system will increase solidus and liquidus temperatures of the resulting alloy. In our work, we are studying the effects of palladium addition on the wetting properties of Ag-CuO braze system on alumina. Quality of brazing is evaluated through microstructural analysis and bending strength of brazed joints created with alumina. The presentation will include processing, and characterization of Ag-CuO brazed system with and without palladium addition on alumina.

  13. Containerless electromagnetic levitation melting of Cu-Fe and Ag-Ni alloys

    NASA Technical Reports Server (NTRS)

    Abbaschian, G. J.; Ethridge, E. C.

    1983-01-01

    The feasibility of producing silver or copper alloys containing finely dispersed nickel or iron particles, respectively, by utilizing containerless electromagnetic levitation casting techniques was investigated. A levitation coil was designed to successfully levitate and melt a variety of alloys including Nb-Ge, Cu-Fe, Fe-C, and Ag-Ni. Samples of 70 Cu-30 Fe and 80 Ag-20 Ni (atomic %), prepared by mechanical pressing of the constituent powders, were levitated and heated either to the solid plus liquid range of the alloys or to the fully liquid region. The samples were then solidified by passing helium gas into the bell jar or they were dropped into a quenching oil. The structure of the samples which were heated to the solid plus liquid range consists of uniform distribution of Fe or Ni particle in their respective matrices. A considerable amount of entrapped gas bubbles were contained. Upon heating for longer periods or to higher temperatures, the bubbles coalesced and burst, causing the samples to become fragmented and usually fall out of the coil.

  14. Montmorillonite-supported Pd0, Fe0, Cu0 and Ag0 nanoparticles: Properties and affinity towards CO2

    NASA Astrophysics Data System (ADS)

    Bouazizi, Nabil; Barrimo, Diana; Nousir, Saadia; Ben Slama, Romdhane; Roy, René; Azzouz, Abdelkrim

    2017-04-01

    This study reports the carbon dioxide (CO2) adsorption on montmorillonite (NaMt) incorporating Cu0, Fe0, Pd0 and Ag0 as metallic nanoparticles (MNPs). The changes in structural, textural, morphological and adsorption properties of the resulting materials (NaMt-MNPs) were investigated. Electron microscopy and X-ray diffraction showed that dispersion of fine MNPs occurs mainly within the interlayer space of NaMt, producing a slight structure expansion. This was accompanied by a visible enhancement of the affinity towards CO2, as supported by thermal programmed desorption measurements. NaMt-MNPs displayed high CO2 retention capacity (CRC) of ca. 657 μmol/g for NaMt-Cu as compared to NaMt. This was explained in terms of increased number of available adsorption sites due to enlarged interlayer spaces caused by MNP insertion. The differences in CO2 adsorption capacities clearly demonstrate the key role of MNPs in improving the surface properties and adsorption capacity. The results reported herein open new prospects for clay supported metal nanoparticles as efficient adsorbents for CO2.

  15. Phase evolution, microstructure and mechanical properties of equi-atomic substituted TiZrHfNiCu and TiZrHfNiCuM (M = Co, Nb) high-entropy alloys

    NASA Astrophysics Data System (ADS)

    Park, Hae Jin; Na, Young Sang; Hong, Sung Hwan; Kim, Jeong Tae; Kim, Young Seok; Lim, Ka Ram; Park, Jin Man; Kim, Ki Buem

    2016-07-01

    In this study, alloys with composition of equi-atomic substituted TiZrHfNiCu, TiZrHfNiCuCo, and TiZrHfNiCuNb high-entropy alloys (HEAs) were produced by suction casting method. The effects of addition elements on phase composition, microstructure and mechanical behaviors of the HEA were studied. The suction casted Ti20Zr20Hf20Ni20Cu20 HEA exhibits single C14 Laves phase (MgZn2-type) with fine homogeneous microstructure. When Co or Nb elements are added, morphologies are slightly modulated toward well-developed dendritic microstructure, phase constitutions are significantly changed from single Laves phase to mixed multi-phases as well as mechanical properties are also altered with increased plasticity and high strength. It is believed that modulated mechanical properties are mainly ascribed to the change of phase constitution and crystalline structure, together with the microstructural characteristics. This clearly reveals that the selection and addition of supplementary elements based on the formation rule for HEAs play an important role on the evolution of phase, microstructural morphology and mechanical properties of Ti20Zr20Hf20Ni20Cu20 HEA.

  16. Alteration of platinum-group minerals and dispersion of platinum-group elements during progressive weathering of the Aguablanca Ni-Cu deposit, SW Spain

    NASA Astrophysics Data System (ADS)

    Suárez, Saioa; Prichard, Hazel M.; Velasco, Francisco; Fisher, Peter C.; McDonald, Iain

    2010-04-01

    The distribution, mineralogy and mobility of the platinum-group elements (PGE) in the surface environment are poorly understood. This study of the lower, less altered and upper, more altered gossan, overlying the Aguablanca Ni-Cu-(PGE) magmatic deposit (Spain), has shown that the platinum-group minerals (PGM) are progressively oxidised and dispersed into iron oxides that form the gossan. A combination of the characterization of PGE in host PGM, using a scanning electron microscope, and measurement of PGE at lower concentrations in host iron oxides, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), has for the first time allowed the total distribution of the PGE within a gossan to be documented. This study has revealed a complete in situ alteration and dispersion sequence of the PGM including (1) breakdown of both the more stable Pt-arsenides, Pt/Pd-tellurides and the less stable bismuthotellurides, (2) formation of partially oxidised PGM, (3) development of a wide range of oxidised Pt- and Pd-bearing phases, (4) subsequent formation of Fe-PGE-oxides and PGE-hydroxides, (5) incorporation of PGE into ferruginous supergene products and lastly (6) concentration of PGE at the edges of veins and iron oxides. Dispersion of Pd is greater than for the other PGE with Pd being widely distributed throughout the iron oxides. This oxidising environment produced PGE-oxides rather than PGE-alloys, also commonly found in the surface environment, especially in placers. These results provide critical evidence for the stages of mineralogical change from PGE host mineralogy in magmatic ores to surface weathering producing PGE-oxides.

  17. Epitaxial (111) films of Cu, Ni, and Cu{sub x}Ni{sub y} on {alpha}-Al{sub 2}O{sub 3} (0001) for graphene growth by chemical vapor deposition

    SciTech Connect

    Miller, David L.; Keller, Mark W.; Shaw, Justin M.; Chiaramonti, Ann N.; Keller, Robert R.

    2012-09-15

    Films of (111)-textured Cu, Ni, and Cu{sub x}Ni{sub y} were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of {alpha}-Al{sub 2}O{sub 3}(0001) at temperatures of 250 Degree-Sign C to 650 Degree-Sign C. The films were then annealed at 1000 Degree-Sign C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by 60 Degree-Sign . The in-plane epitaxial relationship for all films was [110]{sub metal}||[1010]{sub Al{sub 2O{sub 3}}}. Reactive sputtering of Al in O{sub 2} before metal deposition resulted in a single in-plane orientation over 97% of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al{sub 2}O{sub 3} interface, confirmed the epitaxial relationship, and showed that formation of the 60 Degree-Sign twin grains was associated with features on the Al{sub 2}O{sub 3} surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and Cu{sub x}Ni{sub y} films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO{sub 2} films, but still showed thickness variations on a much smaller length scale than the distance between grains.

  18. Origin of ultra-nickeliferous olivine in the Kevitsa Ni-Cu-PGE-mineralized intrusion, northern Finland

    NASA Astrophysics Data System (ADS)

    Yang, Sheng-Hong; Maier, Wolfgang D.; Hanski, Eero J.; Lappalainen, Markku; Santaguida, Frank; Määttä, Sanna

    2013-07-01

    The 2,058 ± 4 Ma mafic-ultramafic Kevitsa intrusion is located in the Central Lapland greenstone belt, northern Finland. It is hosted by a Paleoproterozoic volcano-sedimentary sequence that contains komatiitic volcanic rocks and sulfide- and graphite-rich black schists. Economic Ni-Cu-(PGE) sulfide mineralization occurs in the middle part of the ultramafic lower unit of the intrusion. Two main types of ore are distinguished, "normal" and "Ni-PGE" ores. The normal ore is characterized by ~2 to 6 vol% disseminated sulfides and average Ni and Cu grades of 0.3 and 0.42 wt %, respectively (Ni/Cu < 1). The Ni-PGE ore has broadly similar sulfide contents, but a higher Ni grade and lower Cu grade. As a result, the Ni/Cu ratio reaches 15, much higher than in the normal ore. The Ni-PGE ores occur as irregular, discontinuous, lense-like bodies in the ultramafic rocks. Notably, the olivines in the Ni-PGE ore contain extremely high Ni contents of up to 14,000 ppm, which is significantly higher than the Ni content of olivine in other mafic-ultramafic igneous rocks globally (up to ~5,000 ppm) and in harmony with the associated Ni-rich sulfide assemblage containing pentlandite, millerite and pyrite. Microprobe mapping of olivine from the Ni-PGE ore suggests relatively low and homogeneous S contents and homogeneous distribution of Ni, Mg, Fe, which is inconsistent with the presence of sulfide inclusions in the olivine grains, or diffusion of Ni from interstitial sulfides into the olivine grains. We therefore conclude that Ni substitutes for Mg in the olivine lattice. The clinopyroxenes from the Ni-PGE ore also have unusually high Ni concentrations reaching 1,500 ppm and show a positive correlation with the nickel content of the associated olivine. The Nicpx/Niolivine is ~0.1 to 0.2 corresponding to high T partitioning of Ni between clinopyroxene and olivine. K D of 20 can account for the partitioning of nickel between olivine and the sulfide phase, consistent with magmatic

  19. Microstructure, thermal, and mechanical properties of nanostructured Cu-9.5Ni-4.0Sn-7.5P

    NASA Astrophysics Data System (ADS)

    Li, J.; Wang, T. M.

    1995-04-01

    Nanostructured Cu-9.5Ni-4.0Sn-7.5P samples represent a polycrystal microstructure of nanometer-sized α-Cu and Cu3P crystallites for crystallite sizes less than 20 nm and of nanometer-sized α-Cu, Cu3P, and Ni2P crystallites for crystallite sizes greater than 20 nm. The specific heat values between 300 K and 400 K for the nanostructured sample with crystallite size of 10 nm are about 20% higher than for the amorphous sample and about 40% higher than for the coarse-grained sample. The hardness of the nanostructured sample with crystallite size of 10 nm is 30% higher than that of the amorphous sample and 110% higher than that of the coarse-grained sample. The variation in hardness with the crystallite size for the nanostructured samples follows the Hall-Petch relationship.

  20. Effects of interfacial roughness on the planar Hall effect in NiFe/Cu/IrMn multilayers

    NASA Astrophysics Data System (ADS)

    Li, Xu-Jing; Feng, Chun; Chen, Xi; Liu, Yang; Liu, Yi-Wei; Li, Ming-Hua; Yu, Guang-Hua

    2015-02-01

    This paper reports that the planar Hall effect in NiFe/Cu/IrMn multilayers was strongly influenced by the Cu spacer thickness ( t Cu), which was due to the variation of interfacial roughness. With t Cu increasing, a peculiar change of planar Hall voltage was observed. The reason for the voltage behaviors was that the interfacial roughness influenced the spin-asymmetry of spin-polarized electrons in ferromagnetic metals. The diffuse scattering to the electrons turned to specular scattering when the interface became flat, leading to the variation of resistivity change (Δ ρ). As the increase in t Cu, the extremum field was reduced because of the weaken exchange coupling between NiFe and IrMn layers.

  1. Quaternary PtMnCuX/C (X = Fe, Co, Ni, and Sn) and PtMnMoX/C (X = Fe, Co, Ni, Cu and Sn) alloys catalysts: Synthesis, characterization and activity towards ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Ammam, Malika; Easton, E. Bradley

    2012-10-01

    In this account, two series of quaternary PtMnCuX/C (X = Fe, Co, Ni, and Sn) and PtMnMoX/C (X = Fe, Co, Ni, Cu and Sn) alloys catalysts have been synthesized and characterized by ICP, XRD, XPS, TEM and cyclic voltammetry. XRD spectra of each series illustrated that PtMnCuX/C (X = Fe, Co and Ni) and PtMnMoX/C (X = Fe, Co, Ni and Cu) alloys have been formed without significant free Mn, Cu, Mo or X co-catalysts. For PtMnCuSn/C and PtMnMoSn/C, in addition to alloy formation, significant free Sn-oxides are present in each catalyst. Cyclic voltammetry and chronoamperometry revealed that all quaternary showed superior electrocatalytic activity towards ethanol oxidation compared to the ternary precursor. Also, shift of the onset potential of ethanol oxidation towards less positive values were also recorded with the quaternary alloys, demonstrating a facilitated oxidation with the quaternary alloys compared to ternary alloy precursor. The magnitude of the gain in potential depend on the alloy composition and PtMnMoSn/C was found to be the best of all synthetized quaternary alloys with an onset potential of ethanol oxidation of only 0.059 V vs. Ag/AgCl.

  2. Corrosion aspects of Ni-Cr-Fe based and Ni-Cu based steam generator tube materials

    NASA Astrophysics Data System (ADS)

    Dutta, R. S.

    2009-09-01

    This paper reviews corrosion related issues of Ni-Cr-Fe based (in a general sense) and Ni-Cu based steam generator tube materials for nuclear power plants those have been dealt with for last more than four decades along with some updated information on corrosion research. The materials include austenitic stainless steels (SSs), Alloy 600, Monel 400, Alloy 800 and Alloy 690. Compatibility related issues of these alloys are briefly discussed along with the alloy chemistry and microstructure. For austenitic SSs, stress corrosion cracking (SCC) behaviour in high temperature aqueous environments is discussed. For Alloy 600, intergranular cracking in high temperature water including hydrogen-induced intergranular cracking is highlighted along with the interactions of material in various environments. In case of Monel 400, intergranular corrosion and pitting corrosion at ambient temperature and SCC behaviour at elevated temperature are briefly described. For Alloy 800, the discussion covers SCC behaviour, surface characterization and microstructural aspects of pitting, whereas hydrogen-related issues are also highlighted for Alloy 690.

  3. Fabrication and testing of a CoNiCu/Cu CPP-GMR nanowire-based microfluidic biosensor

    NASA Astrophysics Data System (ADS)

    Bellamkonda, Ramya; John, Tom; Mathew, Bobby; DeCoster, Mark; Hegab, Hisham; Davis, Despina

    2010-02-01

    Giant magneto resistance (GMR)-based microfluidic biosensors are used in applications involving the detection, analysis, enumeration and characterization of magnetic nano-particles attached to biological mediums such as antibodies and DNA. Here we introduce a novel multilayered CoNiCu/Cu nanowire GMR-based microfluidic biosensor. The current perpendicular to the plane of multilayers (CPP)-nanowires GMR was used as the core sensing material in the biosensor which responds to magnetic fields depending on the concentration and the flow velocity of bio-nano-magnetic fluids. The device was tested with different control solutions such as DI-water, mineral oil, phosphate buffered saline (PBS), ferrofluid, polystyrene superparamagnetic beads (PSB) and Dynabeads sheep anti-rabbit IgG. The nanowire array resistance decreased with an increase in the ferrofluid concentration, and a maximum 15.8% relative GMR was observed for the undiluted ferrofluid. The sensor was also responding differently to various ferrofluid flow rates. The GMR device showed variation in the output signal when the PSB and Dynabeads of different dilutions were pumped through it. When the tests were performed with pulsing potentials (150 mV and 200 mV), an increased GMR response was identified at higher voltages for PSB and Dynabeads sheep anti-rabbit IgG.

  4. NMR shielding and spin-rotation constants in XCO (X = Ni, Pd, Pt) molecules

    NASA Astrophysics Data System (ADS)

    Demissie, Taye B.; Jaszuński, Michał; Malkin, Elena; Komorovský, Stanislav; Ruud, Kenneth

    2015-07-01

    Ab initio nonrelativistic and four-component relativistic DFT (density functional theory) methods are combined to study the spin-rotation and absolute nuclear magnetic resonance (NMR) shielding constants of group 10 transition metal monocarbonyls. Good agreement is obtained between the calculated and available experimental data for the spin-rotation constants and shielding spans for PdCO and PtCO. These data allow us to determine accurate absolute chemical shielding constants for all the nuclei, as well as for the unknown spin-rotation constants. We compare the four-component shielding constants with those obtained from the spin-orbit zeroth-order regular approximation, together with an assessment of the performance of different basis sets. For the first time, relativistically optimised basis sets for the heavy atoms used in the four-component calculations are shown to give converged results for both magnetic properties studied. We dedicate this article to the memory of Professor Nicholas C. Handy.

  5. Approach to study of Cu, Ni and Zn content in soil for ecotoxicological risk assessment

    NASA Astrophysics Data System (ADS)

    Boluda, R.; Marimon, L.; Gil, C.; Roca-Pérez, L.

    2009-04-01

    Current Spanish legislation on contaminated soils defines contaminated soil as "that whose characteristics have been negatively altered by the presence of dangerous human-derived chemical components whose concentration is such that it is an unacceptable risk for human health or the environment and has been expressly declared as such by legal ruling". Regarding heavy metals, the Spanish Autonomous Communities will promote measures to obtain generic reference values to declare a soil to be contaminated. In the Valencian Community, these reference values still do not exist. So if the protection of ecosystems is considered a priority to declare a soil to be contaminated and to assess the level of risk, emergency toxicity tests and seed growth in land plants are resorted to, or tests with aquatic organisms or other experiments with leached soils obtained by standard procedures are carried out. We studied the toxic effects of calcareous contaminated soils by Cu, Ni and Zn on marine bacterium Vibrio fisheri (MicrotoxR test assay) (1) and on barley (Hordeum vulgare L.) in plate (germination index) (2) and pot (UNE 77301) (3) experiments for the purpose of establishing the Cu, Ni and Zn concentrations in soil which may lead to toxicity in order to observe, therefore, whether there is any likelihood of these pollutants coming into contact with any receptor and if adverse effects exist for living beings and the environment. The results showed significant differences among the three types of tests done but, in all cases, the concentrations needed to reflect toxicity effect on organisms were around 20 -70 (Cu and Ni) to 1000 (Zn) times higher than the levels of the control soils. The sensitivity order of the bio-assay was: (1) < (3) < (2). We would like to thank Spanish government-MICINN for partial funding and support (MICINN, project CGL2006-09776).

  6. Photoemission Electron Microscopy Study of Ultrathin FeNi Alloy Films on Cu(111)

    NASA Astrophysics Data System (ADS)

    Sato, Yu; Johnson, Tracey; Giacomo, Jason; Chiang, Shirley; Zhu, Xiangdong; Land, Donald; Nolting, Frithjof; Scholl, Andreas

    2002-03-01

    We are studying the system of FeNi/Cu(111) to understand and control the surface/interface magnetism relevant to the application of the giant magnetoresistive effect to magnetic recording heads. We used the Photoemission Electron Microscope (PEEM2) at the Advanced Light Source to observe the domain structures of the alloy films. PEEM has the unique capability of imaging the film's magnetic structure with high spatial resolution and elemental specificity. At two different thicknesses, we have made sixteen samples and studied the dependence of magnetic structure on varying Fe concentration and substrate quality. Samples with higher Fe content were non-magnetic at room temperature. We speculate this is a structure-driven effect related to the "Invar effect" in the bulk alloy. The PEEM images clearly show that Fe and Ni form a good alloy and have the same domain structures with their magnetization aligned. Further, we find a strong thickness and concentration dependence of the magnetic domain structures.

  7. Development of mechanical stress in CuNi(Mn) films during temperature ramping: Related mechanisms

    SciTech Connect

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

    1998-12-31

    This paper focuses on the development of biaxial stress in Cu{sub 0.57}Ni{sub 0.42}Mn{sub 0.01} thin films during annealing in Ar and, for comparison, in vacuum. Besides stress-temperature measurements also resistance-temperature investigations as well as chemical and microstructural characterization by Auger electron spectroscopy, scanning and transmission electron microscopy, and X-ray diffraction were carried out. To explain the stress evolution, atomic rearrangement (excess-vacancy annihilation, grain-boundary relaxation, and shrinkage of grain-boundary voids) and oxidation were considered. Up to 250--300 C grain-boundary relaxation was found to be the dominating process. A sharp transition from compressive to tensile stress between 300 C and 380 C is explained by the formation of a NiO surface layer.

  8. Remarkable ligand effect in Ni- and Pd-catalyzed bisthiolation and bisselenation of terminal alkynes: solving the problem of stereoselective dialkyldichalcogenide addition to the C triple chemical bond C Bond.

    PubMed

    Ananikov, Valentine P; Gayduk, Konstantin A; Beletskaya, Irina P; Khrustalev, Victor N; Antipin, Mikhail Yu

    2008-01-01

    We have developed two new catalytic systems based on Ni and Pd complexes to solve the challenging problem of dialkyldichalcogenide (Alk2E2; E=S, Se) addition to alkynes. A comparative study of two catalytic systems-Ni/PMe2Ph and Pd/PCy2Ph-has revealed that the Ni catalyst is superior with respect to high catalytic activity and more general scope relative to the Pd system. A novel synthetic methodology was developed for the preparation of (Z)-bis(alkylthio)alkenes and (Z)-bis(alkylseleno)alkenes from terminal alkynes with excellent stereoselectivity and high yields.

  9. Imprinting topological domain structure in epitaxial Ni/Fe/Co/Cu(001)

    NASA Astrophysics Data System (ADS)

    Tan, Ali; Li, Jia; Qiu, Zi Qiang; Arenholz, Elke; Scholl, Andreas; Hwang, Chanyong

    2015-03-01

    A vortex state can be stabilized in magnetic thin films by reducing the lateral dimension of the thin film such that the shape anisotropy imposes flux-closure on the magnetic domains. In the language of skyrmions, a vortex state has a topological skyrmion charge Q = +/- 1 / 2 , with vorticity w = + 1 and helicity γ = +/- π / 2 . By tuning the interlayer coupling strength, various domain structures can be imprinted on an adjacent ferromagnetic layer. We investigated domain imprinting by cobalt (Co) vortices on nickel (Ni) layer through a face-centered-cubic (fcc) iron (Fe) interlayer in a Ni/Fe(wedge)/Co(disks)/Cu(001) trilayer system. Using element-specific X-ray Magnetic Circular Dichroism, we observed a strong antiferromagnetic IEC for 5 ML thick Fe interlayer. From the domain images of each elements obtained using Photoemission Electron Microscopy (PEEM), we observed that the relative strength of the bilinear and biquadratic exchange coupling changes as a function of Fe interlayer thickness, leading to non-collinear coupling between Ni and Co around 5.5 ML of Fe. The resulting Ni domain structures have topological skyrmion charge Q = +/- 1 / 2 , with vorticity w = + 1 but varying helicity γ.

  10. Characteristics of the Energetic Micro-initiator Through Integrating Al/Ni Nano-multilayers with Cu Film Bridge

    NASA Astrophysics Data System (ADS)

    Zhang, Yuxin; Jiang, Hongchuan; Zhao, Xiaohui; Yan, Yichao; Zhang, Wanli; Li, Yanrong

    2017-01-01

    An energetic micro-initiator through integrating Al/Ni nano-multilayers with Cu film bridge was investigated in this study. The Cu film bridge was initially fabricated with wet etching, and Al/Ni nano-multilayers were alternately deposited on the surface of Cu film bridge by magnetron sputtering. The periodic layer structure of Al/Ni nano-multilayers was verified by scanning electron microscopy. The exothermic reaction in Al/Ni nano-multilayers can be initiated with onset reaction temperature as low as 503 K, and the total reaction heat is about 774.6 J/g. This energetic micro-initiator exhibited improved performances with lower threshold voltage, smaller initiation energy, and higher explosion temperature compared with Cu film bridge. An extra violent explosion phenomenon with longer duration time and larger quantities of ejected product particles was detected on this energetic micro-initiator by high-speed camera. Overall, the electric explosion performances of Cu film bridge can be improved evidently with the integration of Al/Ni nano-multilayers.

  11. Brazing microstructure of Ti-6Al-6V-2Sn with Ti-Zr-Cu-Ni filler metal

    SciTech Connect

    Hsieh, K.C.; Kao, P.W.; Shu, M.F.

    1994-12-31

    Titanium and its alloys have been widely used in the aerospace industry since they have high specific strength and high corrosion resistance. The brazing of titanium is beneficial to join many contact areas simultaneously without severe distortion. The purpose of this study is to investigate the brazing microstructures under different brazing conditions with several Ti-Zr-Cu-Ni filler alloys. In our previous studies, the brazing microstructure of Ti-6Al-4V with Ti-Cu-Ni filler metal have been reported. Since Ti-6Al-6V-2Sn alloy has lower b-transus, the Ti-Cu-Ni filler alloy cannot successfully apply the brazing work. Several Ti-Zr-Cu-Ni alloys were prepared in powder form and pre-alloy form to perform the brazing of Ti-6Al-6V-2Sn at 870{degrees}C. The brazing microstructures are examined under optical metallograph, scanning electron microscopy (SEM), and X-ray analysis. The contents of this report include (1) DTA and phase analysis of Ti-Zr-Cu-Ni filler metals, (2) the brazing microstructure, and (3) the shear test result.

  12. Effect of physical properties of Cu-Ni-graphite composites on tribological characteristics by grey correlation analysis

    NASA Astrophysics Data System (ADS)

    Wang, Yiran; Gao, Yimin; Sun, Liang; Li, YeFei; Zheng, Baochao; Zhai, Wenyan

    Cu-Ni-graphite composites are intended for using as switch slide baseplates materials in high-speed railways industrials. The tribological characteristics of Cu-Ni-graphite composites with different graphite content were affected by physical properties and were generated variation correspondingly. It is difficult to study the correlation degree between tribological characteristics and physical properties by the means of experiments. However, grey correlation analysis (GCA) is a suitable mathematic method for researching the correlation with each factor. In this study, Cu-Ni-graphite composites were prepared by powder metallurgy and the correlation degree between tribological characteristics (Cu-Ni-graphite composites slid against U75V steel) and physical properties were calculated by GCA method. The results showed that through the calculating by GCA method, compared with physical properties of Cu-Ni-graphite composites, the most effective way to reduce the friction coefficient is to improve the relative density as well as the increasing of hardness can also bring down the friction coefficient usefully. The best way to reduce wear rate is the increasing of work of rupture and flexural strength, when these two properties have a small amount of ascension, the wear rate would be rapidly decreasing. The GCA results could help to improve materials' performance and give reasonable advices to the following studies.

  13. [Study on the chemical form and extraction rate of Cr, Cu, Fe, Mn, Ni and Zn in tea].

    PubMed

    Gao, G; Tao, R

    2000-07-01

    The content of Cr, Cu, Fe, Mn, Ni and Zn in the tea commonly available in China market were measured by inductivity coupled plasma-optical emission spectrometry (ICP-OES). The extraction rates of the six elements in tea leachate were measured. The solubilitied were 39.8% for Cr, 42.5% for Cu, 8.6% for Fe, 45.5% for Mn, 87.1% for Ni and 71.0% for Zn. The process of making tea leachate affects the elements extraction rates. The content of the microelements in tea leave extracts decreases gradually with the processing. About 80% of Cr, Cu, Mn, Ni and Zn and 60% of Fe were in the first infusion of tea. Moreover, the chemical forms of six elements were determined. The ratios of organic to inorganic forms were 0.33 for Cr, 0.022 for Cu, 0.18 for Fe, 0.002 for Mn, 0.01 for Ni and 0.18 for Zn. It is concluded that the six elements from the tea infusion extracted from 5 g tea are too little to meet the recommend dietary allowance (RDA). Therefore, tea is not a rich food source of Cr, Cu, Fe, Mn, Ni and Zn.

  14. Non-isothermal Characterization of the Precipitation Hardening of a Cu-11Ni-19Zn-1Sn Alloy

    NASA Astrophysics Data System (ADS)

    Donoso, E.; Diánez, M. J.; Criado, J. M.; Espinoza, R.; Mosquera, E.

    2017-03-01

    The precip