Sample records for cu ag ni

  1. Photoelectron spectroscopy of mixed metal cluster anions: NiCu?, NiAg?, NiAg?2, and Ni2Ag?

    Microsoft Academic Search

    St. J. Dixon-Warren; R. F. Gunion; W. C. Lineberger

    1996-01-01

    Negative ion photoelectron spectra of NiCu?, NiAg?, NiAg?2, and Ni2Ag? are presented for electron binding energies up to 3.5 eV. The metal cluster anions were prepared in a cold cathode dc discharge flowing afterglow source. The dimer spectra exhibit three low lying electronic states; the ground electronic states are vibrationally resolved. The dimer electron affinities are determined to be EA(NiCu)=0.889±0.010

  2. Impurity-impurity interactions in Cu, Ni, Ag, and Pd

    Microsoft Academic Search

    T. Hoshino; W. Schweika; R. Zeller; P. H. Dederichs

    1993-01-01

    We present systematic ab initio calcultions for the interaction energies of impurity pairs in Cu, Ni, Ag, and Pd. The calculations are based on local-density theory and apply the Korring-Kohn-Rostoker Green's-function method for spherical potentials. The full nonspherical charge density is used to calculate the double-counting contributions to the total energy. In particular, we calculate the nearest- and next-nearest-neighbor interaction

  3. Laser ablation deposition of Cu-Ni and Ag-Ni films: Nonconservation of alloy composition and film microstructure

    NASA Astrophysics Data System (ADS)

    van Ingen, R. P.; Fastenau, R. H. J.; Mittemeijer, E. J.

    1994-08-01

    Laser ablation depositon was used to grow polcrystalline Cu-Ni and Ag-Ni thin films on amorphous substrates at room temperature. X-ray diffraction was employed to determine the phases present and the residual macrostress and to analyze the structure imperfection in terms of crystallite size and microstrain. For confirmation and complementary microstructural data transmission electron microscopy was applied. Analysis of the gross compositon was achieved by electron probe microanalysis and x-ray fluorescence. The films contained substantially less Cu and Ag than the targets, which was caused by preferential scattering of ablated Cu and Ag species upon incidence at the growing films. The Cu-Ni films were entirely composed of a Cu(x) Ni(1-x) solid solution. The Ag-Ni films were composed of a Ag(x) Ni(1-x) solid solution and of pure Ag and pure Ni. The nonequilibrium Ag(x) Ni(1-x) solid solution could contain up to 44 at. % Ag. The residual macrostress in the Cu-Ni films was compressive, whereas it was tensile in the Ag-Ni films. The occurrence of these stresses could be interpreted as due to the combined effects of atomic peening and cooling after depositon and, in the case of the Ag-Ni films, of stress relaxation by particle decomposition of the Ag(x) Ni (1-x) solid solution during film growth. The microstrains in the Ag(x) Ni(1-x) solid solutions were higher than in similarly prepared pure elemental Ag and Ni films. Compositional inhomogeneity of the Ag(x) Ni(1-x) solid solution crystallites contributed in particular to this effect. The strain-free lattice parameters of the solid solutions were found to be in fair agreement with those predicted by Vegard's law.

  4. Computer Simulation of Misfit Dislocation Mobility in Cu/Ni and Cu/Ag Interfaces

    SciTech Connect

    Kurtz, Richard J.; Hoagland, Richard G.; Heinisch, Howard L.

    2001-03-22

    The mobility of misfit dislocations in semicoherent Cu/Ni and Cu/Ag interfaces is determined by molecular dynamics and elastic band simulation methods. Cube-on-cube oriented Cu/Ni and Cu/Ag systems were studied with the interfaces parallel to (010). Core structures of misfit dislocations in semicoherent interfaces are found to be quite different in these systems. In Cu/Ni the misfits have very narrow cores in the plane of the interface. Consequently, the shear stress to move these dislocations is large, ~1.1 GPa. The core width and hence the misfit mobility can be changed by placing the misfit away from the chemical interface. Placement of the misfit one atom layer into the Cu increased the core width almost a factor of four and lowered the threshold shear stress to 0.4 GPa. The misfit dislocations in Cu/Ag interfaces, on the other hand, are wide and therefore are much more mobile. The threshold shear stress for misfit movement in Cu/Ag is very low, ~0.03 GPa.

  5. Creep Behavior of Lead-Free Sn-Ag-Cu + Ni-Ge Solder Alloys

    NASA Astrophysics Data System (ADS)

    Hidaka, N.; Watanabe, H.; Yoshiba, M.

    2009-05-01

    We developed a new lead-free solder alloy, an Sn-Ag-Cu base to which a small amount of Ni and Ge is added, to improve the mechanical properties of solder alloys. We examined creep deformation in bulk and through-hole (TH) form for two lead-free solder alloys, Sn-3.5Ag-0.5Cu-Ni-Ge and Sn-3.0Ag-0.5Cu, at elevated temperatures, finding that the creep rupture life of the Sn-3.5Ag-0.5Cu-Ni-Ge solder alloy was over three times better than that of the Sn-3.0Ag-0.5Cu solder at 398 K. Adding Ni to the solder appears to make microstructural development finer and more uniform. The Ni added to the solder readily combined with Cu to form stable intermetallic compounds of (Cu, Ni)6Sn5 capable of improving the creep behavior of solder alloys. Moreover, microstructural characterization based on transmission electron microscopy analyses observing creep behavior in detail showed that such particles in the Sn-3.5Ag-0.5Cu-Ni-Ge solder alloy prevent dislocation and movement.

  6. Study of interaction between Cu-Sn and Ni-Sn interfacial reactions by Ni-Sn3.5Ag-Cu sandwich structure

    Microsoft Academic Search

    S. J. Wang; C. Y. Liu

    2003-01-01

    The interaction between Cu-Sn and Ni-Sn interfacial reactions in a soldering system has been studied using a Ni-Sn3.5Ag-Cu\\u000a sandwich structure. A layer of Cu-Sn intermetallic compound was observed at the interface of the Ni foil after 30 sec of reflowing.\\u000a Two stages of the Cu-Sn compound growth on the Ni side were observed: (1) in the first minute of reflow,

  7. Phase Stability in 3d-5d (NiPt and CuAu) and 3d-4d (NiPd and CuAg) Systems

    Microsoft Academic Search

    Durga Paudyal; Abhijit Mookerjee

    2004-01-01

    We show the differences in the stability of 3d-5d (NiPt and CuAu) and 3d-4d (NiPd and CuAg) alloys arise mainly due to relativistic corrections. The magnetic properties of disordered NiPd and NiPt alloys also differ due to these corrections which lead to increase in the separation between s-d bands of 5d elements in these alloys. For the magnetic case we

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

    SciTech Connect

    Wang, Z.; Perepezko, J. H., E-mail: perepezk@engr.wisc.edu [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, Wisconsin 53706 (United States)

    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.

  9. Stacking-fault energies for Ag, Cu, and Ni from empirical tight-binding potentials and L. J. Lewis

    E-print Network

    Entel, P.

    Stacking-fault energies for Ag, Cu, and Ni from empirical tight-binding potentials R. Meyer and L, Canada (Dated: July 12, 2002) The intrinsic stacking-fault energies and free energies for Ag, Cu, and Ni comparisons between metals with high and low stacking-fault energies. Moreover, the effect of stacking faults

  10. Cu-Au, Ag-Au, Cu-Ag, and Ni-Au intermetallics: First-principles study of temperature-composition phase diagrams and structures

    Microsoft Academic Search

    V. Ozolins; C. Wolverton; Alex Zunger

    1998-01-01

    The classic metallurgical systems-noble-metal alloys-that have formed the benchmark for various alloy theories are revisited. First-principles fully relaxed general-potential linearized augmented plane-wave (LAPW) total energies of a few ordered structures are used as input to a mixed-space cluster expansion calculation to study the phase stability, thermodynamic properties, and bond lengths in Cu-Au, Ag-Au, Cu-Ag, and Ni-Au alloys. (i) Our theoretical

  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. Embedded-atom-method effective-pair-interaction study of the structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions

    Microsoft Academic Search

    Mark Asta; Stephen M. Foiles

    1996-01-01

    The structural and thermodynamic properties of Cu-Ni, Cu-Ag, and Au-Ni solid solutions have been studied using a computational approach which combines an embedded-atom-method (EAM) description of alloy energetics with a second-order-expansion (SOE) treatment of compositional and displacive disorder. It is discussed in detail how the SOE approach allows the EAM expression for the energy of a substitutional alloy to be

  13. Cu-Au, Ag-Au, Cu-Ag and Ni-Au intermetallics: First-principles study of phase diagrams and structures

    Microsoft Academic Search

    V. Ozolinÿs; C. Wolverton; Alex Zunger

    1997-01-01

    The classic metallurgical systems -- noble metal alloys -- that have formed\\u000athe benchmark for various alloy theories, are revisited. First-principles fully\\u000arelaxed general potential LAPW total energies of a few ordered structures are\\u000aused as input to a mixed-space cluster expansion calculation to study the phase\\u000astability, thermodynamic properties and bond lengths in Cu-Au, Ag-Au, Cu-Ag and\\u000aNi-Au alloys.

  14. Mechanical Deformation Behavior of Sn-Ag-Cu Solders with Minor Addition of 0.05 wt.% Ni

    NASA Astrophysics Data System (ADS)

    Hammad, A. E.; El-Taher, A. M.

    2014-11-01

    The aim of the present work is to develop a comparative evaluation of the microstructural and mechanical deformation behavior of Sn-Ag-Cu (SAC) solders with the minor addition of 0.05 wt.% Ni. Test results showed that, by adding 0.05Ni element into SAC solders, generated mainly small rod-shaped (Cu,Ni)6Sn5 intermetallic compounds (IMCs) inside the ?-Sn phase. Moreover, increasing the Ag content and adding Ni could result in the change of the shape and size of the IMC precipitate. Hence, a significant improvement is observed in the mechanical properties of SAC solders with increasing Ag content and Ni addition. On the other hand, the tensile results of Ni-doped SAC solders showed that both the yield stress and ultimate tensile strengths decrease with increasing temperature and with decreasing strain rate. This behavior was attributed to the competing effects of work hardening and dynamic recovery processes. The Sn-2.0Ag-0.5Cu-0.05Ni solder displayed the highest mechanical properties due to the formation of hard (Cu,Ni)6Sn5 IMCs. Based on the obtained stress exponents and activation energies, it is suggested that the dominant deformation mechanism in SAC (205)-, SAC (0505)- and SAC (0505)-0.05Ni solders is pipe diffusion, and lattice self-diffusion in SAC (205)-0.05Ni solder. In view of these results, the Sn-2.0Ag-0.5Cu-0.05Ni alloy is a more reliable solder alloy with improved properties compared with other solder alloys tested in the present work.

  15. High temperature aging study of intermetallic compound formation of Sn3.5Ag and Sn4.0Ag0.5Cu solders on electroless Ni (P) metallization

    Microsoft Academic Search

    Peng Sun; Cristina Andersson; Xicheng Wei; Zhaonian Cheng; Zonghe Lai; Dongkai Shangguan; Johan Liu

    2006-01-01

    The Sn-3.5Ag and Sn-4.0Ag-0.5Cu solders on electroless Ni-immersion Au metallization exhibited different interfacial morphology after high temperature storage (HTS) testing at 150degC. Ni3Sn4 intermetallic compounds (IMCs) were found in the Sn-Ag system, while in the Sn-Ag-Cu system, spalling grains of (Cu,Ni)6Sn5 IMC were observed after long aging, along with a thick (Ni,Cu)3Sn4 IMC layer which adheres to the P rich

  16. Investigation of interfacial reaction between SnAg eutectic solder and Au\\/Ni\\/Cu\\/Ti thin film metallization

    Microsoft Academic Search

    J. Y. Park; C. W. Yang; J. S. Ha; C.-U. Kim; E. J. Kwon; S. B. Jung; C. S. Kang

    2001-01-01

    This paper reports the formation of intermetallic compounds in Au\\/Ni\\/Cu\\/Ti under-bump-metallization (UBM) structure reacted\\u000a with Ag-Sn eutectic solder. In this study, UBM is prepared by evaporating Au(500 ?)\\/Ni(1000 ?)\\/Cu(7500 ?) \\/Ti (700 ?) thin\\u000a films on top of Si substrates. It is then reacted with Ag-Sn eutectic solder at 260 C for various times to induce different\\u000a stages of the

  17. Effect of Ni layer thickness and soldering time on intermetallic compound formation at the interface between molten Sn3.5Ag and Ni\\/Cu substrate

    Microsoft Academic Search

    Won Kyoung Choi; Hyuck Mo Lee

    1999-01-01

    The binary eutectic Sn-3.5wt.%Ag alloy was soldered on the Ni\\/Cu plate at 250C, the thickness of the Ni layer changing from\\u000a 0 through 2 and 4 m to infinity, and soldering time changing from 30 to 120 s at intervals of 30 s. The infinite thickness\\u000a was equivalent to the bare Ni plate. The morphology, composition and phase identification of

  18. Embedded-atom-method functions for the fcc metals Cu, Ag, Au, Ni, Pd, Pt, and their alloys

    Microsoft Academic Search

    S. M. Foiles; M. I. Baskes; M. S. Daw

    1986-01-01

    A consistent set of embedding functions and pair interactions for use with the embedded-atom method (M.S. Daw and M. I. Baskes, Phys. Rev. B 29, 6443 (1984)) have been determined empirically to describe the fcc metals Cu, Ag, Au, Ni, Pd, and Pt as well as alloys containing these metals. The functions are determined empirically by fitting to the sublimation

  19. Electromigration of Sn37Pb and Sn3Ag1.5Cu\\/Sn3Ag0.5Cu composite flip-chip solder bumps with Ti\\/Ni(V)\\/Cu under bump metallurgy

    Microsoft Academic Search

    Yi-Shao Lai; Kuo-Ming Chen; Chin-Li Kao; Chiu-Wen Lee; Ying-Ta Chiu

    2007-01-01

    We examine electromigration fatigue reliability and morphological patterns of Sn–37Pb and Sn–3Ag–1.5Cu\\/Sn–3Ag–0.5Cu composite solder bumps in a flip–chip package assembly with Ti\\/Ni(V)\\/Cu UBM. The flip–chip test vehicle was subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4A\\/150°C, 0.5A\\/150°C, 0.6A\\/125°C, 0.6A\\/135°C, and 0.6A\\/150°C. The electrothermal coupling analysis was employed to investigate the current crowding

  20. The Maximum Fluidity Length of Solidifying Sn-Cu-Ag-Ni Solder Alloys

    NASA Astrophysics Data System (ADS)

    Gourlay, C. M.; Read, J.; Nogita, K.; Dahle, A. K.

    2008-01-01

    During wave soldering, it is important that a solder is able to flow easily to fill joints and to drain away to leave tidy fillets. The maximum fluidity length ( L f) is a simple measure of the flow behavior of solidifying alloys, defined as the distance a cooling and solidifying alloy can flow in a constant cross-section before the developing microstructure arrests flow. This paper explores the influence of alloy composition on L f in Sn-rich Sn-Cu-Ag-Ni alloys with compositions relevant to wave soldering. Significant differences in L f are measured among candidate lead-free solder alloys, which are discussed with respect to the phase diagrams and the mode of solidification.

  1. Low-energy electron elastic scattering from Mn, Cu, Zn, Ni, Ag, and Cd atoms

    SciTech Connect

    Felfli, Z.; Msezane, A. Z. [Department of Physics and Center for Theoretical Studies of Physical Systems, Clark Atlanta University, Atlanta, Georgia 30314 (United States); Sokolovski, D. [School of Mathematics and Physics, Queen's University of Belfast, Belfast, BT7 1NN (United Kingdom); Department of Chemical Physics, University of the Basque Country, Leioa (Spain)

    2011-05-15

    Electron elastic total cross sections (TCSs) for ground and excited Mn, Cu, Zn, Ni, Ag, and Cd atoms have been investigated in the electron-impact energy range 0 {<=}E{<=} 1 eV. The near-threshold TCSs for both the ground and excited states of these atoms are found to be characterized by Ramsauer-Townsend minima, shape resonances, and extremely sharp resonances corresponding to the formation of stable bound negative ions. The recently developed Regge-pole methodology where the crucial electron-electron correlations are embedded is employed for the calculations. From close scrutiny of the imaginary parts of the complex angular momenta, we conclude that these atoms form stable weakly bound ground and excited negative ions as Regge resonances through slow electron collisions. The extracted electron binding energies from the elastic TCSs of these atoms are contrasted with the available experimental and theoretical values.

  2. Interfacial intermetallic compound growth and shear strength of low-silver SnAgCuBiNi/Cu lead-free solder joints

    NASA Astrophysics Data System (ADS)

    Wei, Guo-qiang; Wang, Lei; Peng, Xin-qiang; Xue, Ming-yang

    2013-09-01

    The growth rule of the interfacial intermetallic compound (IMC) and the degradation of shear strength of Sn-0.8Ag-0.5Cu-2.0Bi-0.05Ni (SACBN)/Cu solder joints were investigated in comparison with Sn-3.0Ag-0.5Cu (SAC305)/Cu solder joints aging at 373, 403, and 438 K. The results show that (Cu1- x ,Ni x )6Sn5 phase forms between the SACBN solder and Cu substrate during soldering. The interfacial IMC thickens constantly with the aging time increasing, and the higher the aging temperature, the faster the IMC layer grows. Compared with the SAC305/Cu couple, the SACBN/Cu couple exhibits a lower layer growth coefficient. The activation energies of IMC growth for SACBN/Cu and SAC305/Cu couples are 111.70 and 82.35 kJ/mol, respectively. In general, the shear strength of aged solder joints declines continuously. However, SACBN/Cu solder joints exhibit a better shear strength than SAC305/Cu solder joints.

  3. Kinetics of interface reaction and intermetallics growth of Sn3.5Ag0.7Cu\\/Au\\/Ni\\/Cu system under isothermal aging

    Microsoft Academic Search

    X. Q. Shi; H. F. Kwan; S. M. L. Nai; G. H. Lim

    2004-01-01

    In this study, lap-shear lead-free sol- der joint specimens were prepared with opti- mized soldering reflow parameters and isother- mal aging tests were carried out on the speci- mens in order to investigate the effects of aging temperature and time on the growth of intermet- allic compound in Sn-3.5Ag-0.7Cu\\/Au\\/Ni\\/Cu sys- tem. Based on the theory of diffusion couple, a new

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

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Shi, Yong-Fang; Chen, Yu-Biao; Wu, Li-Ming

    2012-07-01

    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 °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 NaBH4, but larger than those made by hard or soft template methods.

  5. Why are the 3d-5d compounds CuAu and NiPt stable, whereas the 3d-4d compounds CuAg and NiPd are not

    Microsoft Academic Search

    Ligen Wang; Alex Zunger

    2003-01-01

    We show that the existence of stable, ordered 3d-5d intermetallics CuAu and NiPt, as opposed to the unstable 3d-4d isovalent analogs CuAg and NiPd, results from relativity. First, in shrinking the equilibrium volume of the 5d element, relativity reduces the atomic size mismatch with respect to the 3d element, thus lowering the elastic packing strain. Second, in lowering the energy

  6. Creep Properties of Sn-1.0Ag-0.5Cu Lead-Free Solder with Ni Addition

    NASA Astrophysics Data System (ADS)

    Che, F. X.; Zhu, W. H.; Poh, Edith S. W.; Zhang, X. R.; Zhang, Xiaowu; Chai, T. C.; Gao, S.

    2011-03-01

    In this work, tensile creep tests for Sn-1.0Ag-0.5Cu-0.02Ni solder have been conducted at various temperatures and stress levels to determine its creep properties. The effects of stress level and temperature on creep strain rate were investigated. Creep constitutive models (such as the simple power-law model, hyperbolic sine model, double power-law model, and exponential model) have been reviewed, and the material constants of each model have been determined based on experimental results. The stress exponent and creep activation energy have been studied and compared with other researchers' results. These four creep constitutive models established in this paper were then implemented into a user-defined subroutine in the ANSYS™ finite-element analysis software to investigate the creep behavior of Sn-1.0Ag-0.5Cu-0.02Ni solder joints of thin fine-pitch ball grid array (TFBGA) packages for the purpose of model comparison and application. Similar simulation results of creep strain and creep strain energy density were achieved when using the different creep constitutive models, indicating that the creep models are consistent and accurate.

  7. Effect of Isothermal Aging on the Long-Term Reliability of Fine-Pitch Sn-Ag-Cu and Sn-Ag Solder Interconnects With and Without Board-Side Ni Surface Finish

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Kyu; Duh, Jeng-Gong

    2014-11-01

    The combined effects on long-term reliability of isothermal aging and chemically balanced or unbalanced surface finish have been investigated for fine-pitch ball grid array packages with Sn-3.0Ag-0.5Cu (SAC305) (wt.%) and Sn-3.5Ag (SnAg) (wt.%) solder ball interconnects. Two different printed circuit board surface finishes were selected to compare the effects of chemically balanced and unbalanced structure interconnects with and without board-side Ni surface finish. NiAu/solder/Cu and NiAu/solder/NiAu interconnects were isothermally aged and thermally cycled to evaluate long-term thermal fatigue reliability. Weibull plots of the combined effects of each aging condition and each surface finish revealed lifetime for NiAu/SAC305/Cu was reduced by approximately 40% by aging at 150°C; less degradation was observed for NiAu/SAC305/NiAu. Further reduction of characteristic life-cycle number was observed for NiAu/SnAg/NiAu joints. Microstructure was studied, focusing on its evolution near the board and package-side interfaces. Different mechanisms of aging were apparent under the different joint configurations. Their effects on the fatigue life of solder joints are discussed.

  8. Reactions of Sn-3.5Ag-Based Solders Containing Zn and Al Additions on Cu and Ni(P) Substrates

    NASA Astrophysics Data System (ADS)

    Kotadia, H. R.; Mokhtari, O.; Bottrill, M.; Clode, M. P.; Green, M. A.; Mannan, S. H.

    2010-12-01

    In this study we consider the effect of separately adding 0.5 wt.% to 1.5 wt.% Zn or 0.5 wt.% to 2 wt.% Al to the eutectic Sn-3.5Ag lead-free solder alloy to limit intermetallic compound (IMC) growth between a limited volume of solder and the contact metallization. The resultant solder joint microstructure after reflow and high-temperature storage at 150°C for up to 1000 h was investigated. Experimental results confirmed that the addition of 1.0 wt.% to 1.5 wt.% Zn leads to the formation of Cu-Zn on the Cu substrate, followed by massive spalling of the Cu-Zn IMC from the Cu substrate. Growth of the Cu6Sn5 IMC layer is significantly suppressed. The addition of 0.5 wt.% Zn does not result in the formation of a Cu-Zn layer. On Ni substrates, the Zn segregates to the Ni3Sn4 IMC layer and suppresses its growth. The addition of Al to Sn-3.5Ag solder results in the formation of Al-Cu IMC particles in the solder matrix when reflowed on the Cu substrate, while on Ni substrates Al-Ni IMCs spall into the solder matrix. The formation of a continuous barrier layer in the presence of Al and Zn, as reported when using solder baths, is not observed because of the limited solder volumes used, which are more typical of reflow soldering.

  9. Formation of quasi-free graphene on the Ni(111) surface with intercalated Cu, Ag, and Au layers

    NASA Astrophysics Data System (ADS)

    Shikin, A. M.; Adamchuk, V. K.; Rieder, K.-H.

    2009-11-01

    This paper reports on a study by angle-resolved photoelectron and low-energy electron energy loss spectroscopy of graphene monolayers, which are produced by propylene cracking on the Ni(111) surface, followed by intercalation of Cu, Ag, and Au atoms between the graphene monolayer and the substrate, for various thicknesses of deposited metal layers and annealing temperatures. It has been shown that the spectra of valence-band ? states and of phonon vibrational modes measured after intercalation become similar to those characteristic of single-crystal graphite with weak interlayer coupling. Despite the strong coupling of the graphene monolayer to the substrate becoming suppressed by intercalation of Cu and Ag atoms, the ? state branch does not reach at the K point of the Brillouin zone the Fermi level, with the graphene coating itself breaking up partially to form graphene domains. At the same time after intercalation of Au atoms, the electronic band structure approaches the closest to that of isolated graphene, with linear ?-state dispersion near the K point of the Brillouin zone, and the point of crossing of the filled, (?), with empty, (?*), states lying in the region of the Fermi level, which makes this system a promising experimental model of the quasi-free graphene monolayer.

  10. Electrical surface and catalytic properties of NiO as influenced by doping with CuO and Ag 2O

    Microsoft Academic Search

    A. M. Turky

    2003-01-01

    The effects of Ag2O- and CuO-doping of NiO on its electrical, surface and catalytic properties were investigated. The dopants concentrations were 0.25–1.00mol% Ag2O and 1–4mol% CuO. Pure and doped solids were subjected to heat treatment at 300–700°C. The techniques employed were XRD, surface excess oxygen determination, dc conductivity measurements, N2 adsorption at ?196°C and catalytic decomposition of H2O2 at 25–45°C.The

  11. Alleviating coking in ethanol steam reforming by co-loading binary oxides Ni-M (M=Ag, Cu, Mn) on peony-like ceria

    NASA Astrophysics Data System (ADS)

    Xian, C. N.; Li, J. G.; Li, H.; Chen, L. Q.; Sun, J.; Lee, J. S.

    2011-06-01

    Previously, hydrothermally prepared mesoporous peony-like ceria (PCO) material was shown to exhibit superior catalytic properties for CO oxidation and ethanol reforming. Ni supported PCO had been shown to have high activity for ethanol steam reforming at low temperature. In this work, Ag, Cu and Mn is co-loaded with Ni on PCO catalysts by impregnation method. The catalysts were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and a combined thermogravimetry, differential scanning calorimetry, and mass spectrometry (TG-DSC-MS). It was found that all the catalysts gave 100% ethanol conversion above ca. 300°C and exhibited similar H2 yield. It is found that the severe coking problem for the Ni-loaded PCO catalyst was alleviated significantly if Ag, Cu or Mn is co-loaded. Among them, the addition of Mn is the most effective in reducing carbon formation.

  12. Electronic theory for phase stability of nine AB binary alloys, with A=Ni, Pd, or Pt and B=Cu, Ag, or Au

    Microsoft Academic Search

    Satoshi Takizawa; Kiyoyuki Terakura; Tetsuo Mohri

    1989-01-01

    By performing the local-density-functional band calculations, we analyzed the phase stability of nine binary-alloy systems which are composed of Ni, Pd, or Pt as one element and Cu, Ag, or Au as the other. Most of the qualitative aspects of the phase diagrams of these systems are reproduced successfully. It is pointed out that the relativistic effect plays a crucial

  13. Ag-Cu System

    NSDL National Science Digital Library

    Kattner, Ursula

    2003-01-01

    The information provided for the Ag-Cu System consists of five parts: - Diagram: The diagram shows the calculated phase diagram of the system. - Status: The source and status of the analytical description of the Gibbs energies of the phases. - Additional Assessments: Bibliographic information for alternate thermodynamic descriptions. - Invariant Equilibria: Table with the calculated invariant equilibria of the system. The table lists the phases involved in the reaction, phase compositions and reaction temperature. - Phases: Table with the phases of the system. The table lists the crystal structure, common names of the phases and the model used for the thermodynamic description. Thermodynamic databases allow the compact storage of phase equilibria information in the form of Gibbs energy functions for each phase. The thermodynamic description of each phase in the binary system is derived from the assessment of the available phase equilibria and thermochemical data. The calculated phase diagram of the Ag-Cu system is presented.

  14. Interfacial Reactions of Sn, Sn-3.0Ag-0.5Cu, and Sn-9Zn Lead-Free Solders with Fe-42Ni Substrates

    NASA Astrophysics Data System (ADS)

    Yen, Yee-Wen; Hsieh, Yu-Ping; Jao, Chien-Chung; Chiu, Chao-Wei; Li, Yi-Shan

    2014-01-01

    Interfacial reactions between Sn, Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC), and Sn-9 wt.%Zn (SZ) lead-free solders and Fe-42 wt.%Ni (alloy 42) substrates at 240°C, 255°C, and 270°C were investigated in this study. FeSn2, (Fe,Ni, Cu)Sn2, and (Ni,Fe)5Zn21 phases were formed, respectively, at the interface in the Sn/alloy 42, SAC/alloy 42, and SZ/alloy 42 couples. As the reaction time and temperature were increased, the layered intermetallic compound (IMC) assumed two distinct structures, i.e., a thicker layer and a pillar-shaped IMC, in all couples. The IMC thickness of these couples increased with the increase of reaction time and temperature. The IMC thickness was also proportional to the square root of the reaction time. The interfacial reaction mechanism of these couples was diffusion controlled.

  15. Comparing three approaches in extending biotic ligand models to predict the toxicity of binary metal mixtures (Cu-Ni, Cu-Zn and Cu-Ag) to lettuce (Lactuca sativa L.).

    PubMed

    Liu, Yang; Vijver, Martina G; Peijnenburg, Willie J G M

    2014-10-01

    Metals are always found in the environment as mixtures rather than as solitary elements. However, effect models such as biotic ligand models (BLMs) are usually derived for toxicity prediction of single metals. Our study aimed at predicting mixture toxicity of Cu-Ni, Cu-Zn and Cu-Ag combinations to lettuce (Lactucasativa L.) by combining BLMs with three toxicity indexes: the toxic unit, the overall amounts of metal ions bound to the biotic ligands and the toxic equivalency factor. The accumulation of metal ions at the biotic ligands was used to determine the toxic potency of metals alone or in combination. On the basis of parameters derived from toxicity assessment of individual metals, these three extended BLMs appeared to be all acceptable (p<0.0001) in assessing toxicity of diverse metal mixtures. The BLM-based approaches integrated competition between metal ions in assessing mixture toxicity and showed different predictive ability for each metal combination. The outcome of modeling suggested that the combined toxicity depends on the specific components of the metal mixtures. The best developed models assist in identifying the type of underlying toxic mechanisms of diverse metal mixtures in terrestrial plants. PMID:25048917

  16. Direct determination of traces of Ag, Cd, Pb, Bi, Cr, Mn, Co, Ni, Li, Be, Cu and Sb in environmental waters and geological materials by simultaneous multi-element graphite furnace atomic absorption spectrometry with Zeeman-effect background correction

    Microsoft Academic Search

    J. G. Sen Gupta; J. L. Bouvier

    1995-01-01

    A method was developed for direct determination of minor and trace amounts of Cr, Mn, Cu, Ni, Co, Li, Pb, Cd, Bi, Sb, Be and Ag in silicate rock, lake and stream sediments using a microwave oven dissolution method and a multi-element graphite furnace atomic absorption spectrometer equipped with a Zeeman-effect background correction device. The measurement technique was also suitable

  17. Structural and magnetic characterization of electrodeposited Ni-Cu/Cu and Fe-Ni-Cu/Cu multilayer

    NASA Astrophysics Data System (ADS)

    Hedayati, Kambiz

    2015-03-01

    In this research, Ni-Cu/Cu and Fe-Ni-Cu/Cu multilayers were electrodeposited on Au/Cr/glass substrate. The XRD pattern of Ni-Cu/Cu multilayer indicates satellite peaks of Ni-Cu and Cu bilayers. The EDX results had shown that the Ni content increased with increasing magnetic layers in both Ni-Cu/Cu and Fe-Ni-Cu/Cu multilayers. The AFM images had shown that increasing the magnetic and nonmagnetic layers leads to increasing surface roughness. The VSM of samples obtained the coercivity by increasing magnetic layer thickness and by decreasing the addition of Fe to Ni-Cu/Cu multilayers.

  18. Frequency-Dependent Low Cycle Fatigue of Sn1Ag0.1Cu(In/Ni) Solder Joints Subjected to High-Frequency Loading

    NASA Astrophysics Data System (ADS)

    Wong, E. H.; Seah, S. K. W.; Shim, V. P. W.

    2014-02-01

    The low-cycle-fatigue characteristics of solder joints, formed by reflowing Sn98.8/Ag1.0/Cu0.1/In0.05/Ni0.02 solder over electroless nickel immersion gold-plated copper pads, were investigated by dynamic cyclic bending of printed circuit boards (PCBs). The PCB strain amplitudes were varied from 1.2 × 10-3 to 2.4 × 10-3 and the flexural frequencies ranged from 30 Hz to 150 Hz, to simulate drop impact-induced PCB resonant frequencies. A trend of drastically decreasing fatigue life with cyclic frequency was observed, in contrast with previous reports indicating the reverse; this is attributed to the different failure mechanisms activated. A systematic procedure involving optimization followed by transformation was used to condense the strain-frequency-life data into a master curve expressed in strain-life space.

  19. Microstructural Development and Mechanical Properties for Reactive Air Brazing of ZTA to Ni Alloys using Ag-CuO Braze Alloys

    SciTech Connect

    Prevost, Erica; DeMarco, A.Joseph; MacMichael, Beth; Joshi, Vineet V.; Meier, Alan; Hoffman, John W.; Walker, William J.

    2014-12-01

    Reactive air brazing (RAB) is a potential joining technique to join metal alloys to ceramics for a variety of applications. In the current study, nickel (Ni) alloys were heat treated to form an oxide layer prior to RAB joining to zirconia toughened alumina (ZTA). The Ni alloys evaluated were Nicrofer 6025 HT, Inconel 600, Inconel 693, Haynes 214 and Inconel 601. The ZTA studied had compositions of 0 to 15 wt% zirconia and 0 to 14 wt% glass. Four point-bend tests were performed to evaluate the joint strength of ZTA/ZTA and ZTA/nickel alloys brazed with Ag-2wt% CuO braze alloys. It was determined that the joint strength is not a function of the ZTA composition, but that the strength is a strong function of the chemistry and microstructure of the oxide layer formed on the nickel alloy. It was determined that an increase in the aluminum content of the Ni alloy resulted in an increase of the thickness of alumina in the oxide layer and was directly proportional to the bond strength with the exception of Inconel 601 which exhibited relatively high joint strengths even though it had a relatively low aluminum content.

  20. Hydrogen dissociation and diffusion on transition metal (= Ti, Zr, V, Fe, Ru, Co, Rh, Ni, Pd, Cu, Ag)-doped Mg(0001) surfaces

    NASA Astrophysics Data System (ADS)

    Pozzo, M.; Alfè, D.

    2009-02-01

    The kinetics of hydrogen absorption by magnesium bulk is affected by two main activated processes: the dissociation of the H2 molecule and the diffusion of atomic H into the bulk. In order to have fast absorption kinetics both activated processed need to have a low barrier. Here we report a systematic ab initio density functional theory investigation of H2 dissociation and subsequent atomic H diffusion on TM (= Ti, V, Zr, Fe, Ru, Co, Rh, Ni, Pd, Cu, Ag)-doped Mg(0001) surfaces. The calculations show that doping the surface with TMs on the left of the periodic table eliminates the barrier for the dissociation of the molecule, but the H atoms bind very strongly to the TM, therefore hindering diffusion. Conversely, TMs on the right of the periodic table do not bind H, however, they do not reduce the barrier to dissociate H2 significantly. Our results show that Fe, Ni and Rh, and to some extent Co and Pd, are all exceptions, combining low activation barriers for both processes, with Ni being the best possible choice.

  1. Method Development for Simultaneous Determination of Transition (Au, Ag, Cd, Cu, Mn, Ni, Pb, Zn) and Noble (Pd, Pt, Rh) Metal Volatile Species by Microwave-Induced Plasma Spectrometry Using Ultrasonic Micronebulizer Dual Capillary Sample Introduction System

    Microsoft Academic Search

    Henryk Matusiewicz; Mariusz Slachcinski

    2010-01-01

    The commercial ultrasonic nebulizer NOVA-DUO (Optolab, Warsaw, Poland) has been evaluated for the simultaneous determination of transition (Au, Ag, Cd, Cu, Mn, Ni, Pb, Zn) and noble (Pd, Pt, Rh) volatile metal species by microwave induced plasma–optical emission spectrometry (MIP-OES). Simultaneous mixing and nebulization of the two solutions (acidified sample and reductant) on the piezoelectric transducer, with the possibility of

  2. Electromechanical switching behavior of individual molecular complexes of Cu and Ni on NaCl-covered Cu(111) and Ag(111)

    NASA Astrophysics Data System (ADS)

    Walch, Hermann; Leoni, Thomas; Guillermet, Olivier; Langlais, Véronique; Scheuermann, Andrew; Bonvoisin, Jacques; Gauthier, Sébastien

    2012-08-01

    In a combined scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc-AFM) study, we characterize the reversible switching between two stable states of an organometallic complex, namely, bis-dibenzoylmethanato-copper [Cu(dbm)2] adsorbed on an insulating thin film. The switching is due to the transfer of an electron between the STM tip and the molecule, accompanied by a conformational change, i.e., a transition from a square-planar to a tetrahedral geometry. Evidence is given by STM topography and spectroscopy and nc-AFM electrostatic force measurements. Similar experiments conducted on bis-dibenzoylmethanato-nickel [Ni(dbm)2] show that this complex does not switch under comparable experimental conditions. We discuss these findings within the framework of crystal-field theory, stating that the occupation of the d orbitals determines the favored coordination geometry of a complex. Accordingly, only the copper complex can undergo a conformational change that facilitates stable storing of the additional electron.

  3. On the cerium valence in ternary compounds CeMSb 2 and CeM?Bi 2; M=Mn,Fe,Co,Ni,Cu,Zn,Pd,Ag,Au and M'=Ni,Cu,Zn,Ag

    Microsoft Academic Search

    H Flandorfer; O Sologub; C Godart; K Hiebl; A Leithe-Jasper; P Rogl; H Noël

    1996-01-01

    Ternary compounds CeMSb2 and CeM?Bi2 have been synthesized by arc melting followed by a heat treatment at 400, 600 or 800°C for 300 h. Bismuth-containing compounds have been observed for the first time. From X-ray powder diffractometry all compounds were found to be isotypic with ZrCuSi2-type. In CeMn0.9Sb2, the manganese sublattice orders ferromagnetically at T?130 K, and the cerium sublattice

  4. Ag-Bi-Cu System

    NSDL National Science Digital Library

    Kattner, Ursula

    2003-01-01

    The information provided for the Ag-Bi-Cu System consists of five parts: - Diagram: The diagram shows the calculated liquidus projection. Shown are the isotherms and lines of two-fold saturation. - Status: The analytical descriptions of the Gibbs energies of the constituent binaries are combined for each phase and used to predict the multicomponent system. - Sources: Bibliographic information for the thermodynamic descriptions. - Invariant Equilibria: Table with the calculated invariant equilibria of the system. The table lists the phases involved in the reaction, phase compositions and reaction temperature. - Phases: Table with the phases of the system. The table lists the crystal structure, common names of the phases and the model used for the thermodynamic description. Thermodynamic databases allow the compact storage of phase equilibria information in form of Gibbs energy functions for each phase. There are basicly two types of thermodynamic descriptions of a ternary system: (1) extrapolated, i.e., the analytical descriptions of constituent binaries are combined and used to predict the multicomponent system, (2) assessed, i.e., the thermodynamic description is derived from the assessment of the available ternary phase equilibria and thermochemical data. If experimental data were only available or considered for part of the system then a partial assessment is possible. The calculated phase diagram of the Ag-Bi-Cu system is presented.

  5. Ag-Cu-Pb System

    NSDL National Science Digital Library

    Kattner, Ursula

    2003-01-01

    The information provided for the Ag-Cu-Pb System consists of five parts: - Diagram: The diagram shows the calculated liquidus projection. Shown are the isotherms and lines of two-fold saturation. - Status: The analytical descriptions of the Gibbs energies of the constituent binaries are combined for each phase and used to predict the multicomponent system. - Sources: Bibliographic information for the thermodynamic descriptions. - Invariant Equilibria: Table with the calculated invariant equilibria of the system. The table lists the phases involved in the reaction, phase compositions and reaction temperature. - Phases: Table with the phases of the system. The table lists the crystal structure, common names of the phases and the model used for the thermodynamic description. Thermodynamic databases allow the compact storage of phase equilibria information in form of Gibbs energy functions for each phase. There are basicly two types of thermodynamic descriptions of a ternary system: (1) extrapolated, i.e., the analytical descriptions of constituent binaries are combined and used to predict the multicomponent system, (2) assessed, i.e., the thermodynamic description is derived from the assessment of the available ternary phase equilibria and thermochemical data. If experimental data were only available or considered for part of the system then a partial assessment is possible. The calculated phase diagram of the Ag-Cu-Pb system is presented.

  6. Ag-Cu-Sn System

    NSDL National Science Digital Library

    Kattner, Ursula

    2003-01-01

    The information provided for the Ag-Cu-Sn System consists of five parts: - Diagrams: The diagrams show the calculated projection of the liquidus. Shown are the isotherms and lines of two-fold saturation. The first diagram shows the liquidus projection for the entire system, the second diagram shows an enlargement of the Sn-rich part of the system. - Status: The analytical descriptions of the Gibbs energies of the constituent binaries are combined for each phase and used to predict the multicomponent system. - Sources: Bibliographic information for the thermodynamic descriptions. - Invariant Equilibria: Table with the calculated invariant equilibria of the system. The table lists the phases involved in the reaction, phase compositions and reaction temperature. - Phases: Table with the phases of the system. The table lists the crystal structure, common names of the phases and the model used for the thermodynamic description. Thermodynamic databases allow the compact storage of phase equilibria information in form of Gibbs energy functions for each phase. There are basicly two types of thermodynamic descriptions of a ternary system: (1) extrapolated, i.e., the analytical descriptions of constituent binaries are combined and used to predict the multicomponent system, (2) assessed, i.e., the thermodynamic description is derived from the assessment of the available ternary phase equilibria and thermochemical data. If experimental data were only available or considered for part of the system then a partial assessment is possible. The calculated phase diagram of the Ag-Cu-Sn system is presented.

  7. Spectroscopic (IR, Raman, UV, 1H and 13C NMR) and microbiological studies of Fe(III), Ni(II), Cu(II), Zn(II) and Ag(I) picolinates

    NASA Astrophysics Data System (ADS)

    Kalinowska, M.; Borawska, M.; ?wis?ocka, R.; Piekut, J.; Lewandowski, W.

    2007-05-01

    The FT-IR, Raman spectra of picolinic acid as well as Fe(III), Zn(II), Cu(II), Ni(II) and Ag(I) picolinates were registered, assigned and compared. Some regularities in the spectra of studied picolinates within the regions: 1650-1340 cm -1 [ ?(CC) ar, ?as(COO -), ?s(COO -)]; 1300-1020 cm -1 [ ?(CH)]; 780-620 cm -1 [ ?(CH), ?(CCC)] were found. 1H and 13C NMR spectra for picolinic acid, Zn(II) and Ag(I) picolinates were recorded and studied as well. Moreover the UV spectra of picolinic and picolinates were registered and compared. The influence of Ag(I), Zn(II), Ni(II), Cu(II) and Fe(III) on the electronic system of picolinic acid was investigated. The microbiological activity of picolinates against two species of bacteria: Escherichia coli, Bacillus subtilis as well as two species of yeasts: Saccharomyces cerevisiae and Hansenula anomala was also studied.

  8. The metallurgical behaviour during brazing of Ni-base alloy Inconel 600 to Si 3 N 4 with Ag71Cu27Ti2 filler metal

    Microsoft Academic Search

    J. H. Chen; G. Z. Wang; K. Nogi; M. Kamai; N. Sato; N. Iwamoto

    1993-01-01

    Detailed observations were carried out on the metallurgical behaviour of joint-brazing of nickel based alloy Inconel 600 to Si3N4 with Ag71Cu27Ti2 filler metal, with emphasis on the interface between the filler metal and the Inconel 600 and the effects of nickel which was the predominant element in the base metal. Based on the experimental results, the mechanism of bonding Inconel

  9. The influence of the nonmagnetic metal spacer Bi, Ag and Cu on the properties of the multilayer films

    Microsoft Academic Search

    Minghua Li; Guanghua Yu; Fengwu Zhu; Wuyan Lai

    2006-01-01

    Ta\\/NiFe\\/Bi(Ag, Cu)\\/FeMn\\/Ta and Ta\\/NiFeI\\/FeMn\\/Bi(Ag, Cu)\\/NiFeII\\/Ta films were prepared by magnetic sputtering. The texture of films was examined by X-ray diffraction (XRD). The dependence\\u000a of the H\\u000a ex1 between NiFeI\\/FeMn films and the H\\u000a ex2 between FeMn\\/NiFeII on the Bi, Ag and Cu thickness was studied in Ta\\/NiFeI\\/FeMn\\/Bi(Ag, Cu)\\/NiFeII\\/Ta. The experimental results show that the H\\u000a e1 ranged from 130 to

  10. Nonequilibrium microstructures for ag-ni nanowires.

    PubMed

    Rai, Rajesh K; Srivastava, Chandan

    2015-04-01

    This work illustrates that a variety of nanowire microstructures can be obtained either by controlling the nanowire formation kinetics or by suitable thermal processing of as-deposited nanowires with nonequilibrium metastable microstructure. In the present work, 200-nm diameter Ag-Ni nanowires with similar compositions, but with significantly different microstructures, were electrodeposited. A 15 mA deposition current produced nanowires in which Ag-rich crystalline nanoparticles were embedded in a Ni-rich amorphous matrix. A 3 mA deposition current produced nanowires in which an Ag-rich crystalline phase formed a backbone-like configuration in the axial region of the nanowire, whereas the peripheral region contained Ni-rich nanocrystalline and amorphous phases. Isothermal annealing of the nanowires illustrated a phase evolution pathway that was extremely sensitive to the initial nanowire microstructure. PMID:25655641

  11. Partial and integral enthalpies of mixing of liquid Ag–Al–Cu and Ag–Cu–Zn alloys

    Microsoft Academic Search

    Victor T. Witusiewicz; Ulrike Hecht; Stephan Rex; Ferdinand Sommer

    2002-01-01

    The partial enthalpies of mixing of the components of liquid ternary Ag–Al–Cu (T=1252±5 K) and Ag–Cu–Zn (T=1068–1113 K) alloys have been determined using a high-temperature isoperibolic calorimeter. Measurements were performed starting from both pure Al and Zn and from binary liquid Ag–Cu alloys along sections with constant Ag:Cu ratios 1:3, 1:1, 3:1 (Ag–Al–Cu system) and 2:3, 3:2 (Ag–Cu–Zn system). The

  12. Metal carboxylate formation during indoor atmospheric corrosion of Cu, Zn, and Ni

    Microsoft Academic Search

    Dan Persson; C. Leygraf

    1995-01-01

    Chemical analyses of surface films and corrosion products formed on pure Cu, Zn, Ni, and Ag samples exposed up to 12 months in various mild indoor environments have been performed by infrared reflection-absorption spectroscopy (IRAS) and X-ray photoelectron spectroscopy. The analyses reveal metal carboxylates to be the main ingredients on the surface of Cu, Zn, and Ni. Other ions, such

  13. Measured fast-neutron activation cross sections of Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti at 10. 3 and 14. 8 MeV and for the continuum neutron spectrum produced by 7MeV deuterons on a thick Be-metal target

    Microsoft Academic Search

    J. W. Meadows; D. L. Smith; L. R. Greenwood; R. C. Haight; Y. Ikeda; C. Konno

    1991-01-01

    Four identical sample packets containing elemental Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti have been irradiated in three distinct accelerator neutron fields, at Argonne National Laboratory and Los Alamos National Laboratory, USA, and Japan Atomic Energy Research Institute, Tokai, Japan, under the auspices of an International Atomic Energy Agency Coordinated Research Program to investigate the production of long-lived

  14. Measured fast-neutron activation cross sections of Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti at 10.3 and 14.8 MeV and for the continuum neutron spectrum produced by 7MeV deuterons on a thick Be-metal target

    Microsoft Academic Search

    J. W. Meadows; D. L. Smith; L. R. Greenwood; R. C. Haight; Y. Ikeda; C. Konno

    1991-01-01

    Four identical sample packets containing elemental Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti have been irradiated in three distinct accelerator neutron fields, at Argonne National Laboratory and Los Alamos National Laboratory, USA, and Japan Atomic Energy Research Institute, Tokai, Japan, under the auspices of an International Atomic Energy Agency Coordinated Research Program to investigate the production of long-lived

  15. Optical properties and electronic structures of d- and f-electron metals and alloys, Ag-In, Ni-Cu, AuGa sub 2 , PtGa sub 2 ,. beta. prime -NiAl,. beta. prime -CoAl, CeSn sub 3 , and LaSn sub 3

    SciTech Connect

    Kim, Kwang Joo.

    1990-10-17

    Optical properties and electronic structures of disordered Ag{sub 1- x}In{sub x}(x = 0.0, 0.04, 0.08, 0.12) and Ni{sub 1-x}Cu{sub x} (x = 0.0, 0.1, 0.3, 0.4) alloys and ordered AuGa{sub 2}, PtGa{sub 2}, {beta}{prime}-NiAl, {beta}{prime}-CoAl, CeSn{sub 3}, and LaSn{sub 3} have been studied. The complex dielectric functions have been determined for Ag{sub 1-x}In{sub x}, Ni{sub 1-x}Cu{sub x}, AuGa{sub 2}, and PtGa{sub 2} in the 1.2--5.5 eV region and for CeSn{sub 3} and LaSn{sub 3} in the 1.5--4.5 eV region using spectroscopic ellipsometry. Self-consistent relativistic band calculations using the linearized-augmented-plane-wave method have been performed for AuGa{sub 2}, PtGa{sub 2}, {beta}{prime}-NiAl, {beta}{prime}-CoAl, CeSn{sub 3}, and LaSn{sub 3} to interpret the experimental optical spectra.

  16. Effects of temperature, silicate melt composition, and oxygen fugacity on the partitioning of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide phases and silicate melt

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audétat, Andreas

    2015-08-01

    In order to assess the role of sulfide in controlling the ore metal budgets and fractionation during magmatic genesis and differentiation, the partition coefficients (D) of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide liquid (SL), monosulfide solid solution (MSS), and basaltic to rhyolitic melts (SM) were determined at 900-1200 °C, 0.5-1.5 GPa, and oxygen fugacity (fO2) ranging from ?FMQ-2 to FMQ+3, in a piston-cylinder apparatus. The DSL/SM values range from 0.4 to 2 for V, 0.5 to 3 for Mn, 80 to 580 for Co, 2300 to 18,000 for Ni, 800 to 4600 for Cu, 1 to 11 for Zn, 20 to 180 for As, 4 to 230 for Mo, 450 to 1600 for Ag, 5 to 24 for Sn, 10 to 80 for Sb, 0.03 to 0.16 for W, 2000 to 29,000 for Au, 24 to 170 for Pb, and 830 to 11,000 for Bi; whereas the DMSS/SM values range from 0.04 to 10 for V, 0.5 to 10 for Mn, 70 to 2500 for Co, 650 to 18,000 for Ni, 280 to 42,000 for Cu, 0.1 to 80 for Zn, 0.2 to 30 for As, 1 to 820 for Mo, 20 to 500 for Ag, 0.2 to 220 for Sn, 0.1 to 40 for Sb, 0.01 to 24 for W, 10 to 2000 for Au, 0.03 to 6 for Pb, and 1 to 350 for Bi. Both DMSS/SM and DSL/SM values generally increase with decreasing temperature or decreasing FeOtot content in silicate melt, except for Mo, DMSS/SM and DSL/SM of which show a clear decrease with decreasing temperature. At given temperature and FeOtot content, high oxygen fugacity appears to lead to a significant decrease in DMSS/SM of Au, Bi, Mo, and potentially As. The partitioning data obtained experimentally in this study and previous studies were fitted to an empirical equation that expresses the DMSS/SM and/or DSL/SM of a given element as a function of temperature, oxygen fugacity, and FeOtot content of the silicate melt: log (DSL/SMorDMSS/SM = d + a · 10, 000 / T + b · (?FMQ) + c · log (FeOmelt) in which T is temperature in K, FeOmelt denotes wt% FeOtot in silicate melt, and ?FMQ denotes log fO2 relative to the fayalite-magnetite-quartz (FMQ) oxygen buffer. The application of this equation to natural samples of basaltic to rhyolitic composition yields DMSS/SM and DSL/SM values that agree with the measured values within ±0.5 log units for most of the elements, indicating the validity of the application of this equation to natural systems. Our partitioning data imply that sulfide liquid saturation in low-temperature intermediate to felsic melts causes a strong depletion in Cu, Au, Bi, and potentially Ag in the silicate melt, whereas MSS saturation may cause a depletion in Cu and potentially Au. Other elements including W, Zn, As, Mo, Sn, Sb, and Pb are much less or not affected by the saturation of sulfide liquid or MSS. These results place important constrains on the potential of magmas in forming porphyry-type ore deposits and the origin of the observed variability in metal ratios in porphyry-type ore deposits.

  17. Adhesive strength and tensile fracture of Ni particle enhanced Sn–Ag composite solder joints

    Microsoft Academic Search

    H. T. Lee; Y. H. Lee

    2006-01-01

    This study forms composite solders by adding 0.5–3wt% of Ni particles in situ to Sn–3.5wt%Ag lead-free solder. Cu\\/solder\\/Cu specimens are prepared by dipping two Cu rods into a solder bath to produce a solder joint. Some of the joint specimens are retained in the as-soldered condition, while the others are aged at 150°C for 100, 200, 400, or 500h, respectively.

  18. High-Reliability Low-Ag-Content Sn-Ag-Cu Solder Joints for Electronics Applications

    NASA Astrophysics Data System (ADS)

    Shnawah, Dhafer Abdulameer; Said, Suhana Binti Mohd; Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum; Che, Fa Xing

    2012-09-01

    Sn-Ag-Cu (SAC) alloy is currently recognized as the standard lead-free solder alloy for packaging of interconnects in the electronics industry, and high- Ag-content SAC alloys are the most popular choice. However, this choice has been encumbered by the fragility of the solder joints that has been observed in drop testing as well as the high cost of the Ag itself. Therefore, low-Ag-content SAC alloy was considered as a solution for both issues. However, this approach may compromise the thermal-cycling performance of the solders. Therefore, to enhance the thermal-cycling reliability of low-Ag-content SAC alloys without sacrificing their drop-impact performance, alloying elements such as Mn, Ce, Ti, Bi, In, Sb, Ni, Zn, Al, Fe, and Co were selected as additions to these alloys. However, research reports related to these modified SAC alloys are limited. To address this paucity, the present study reviews the effect of these minor alloying elements on the solder joint reliability of low-Ag-content SAC alloys in terms of thermal cycling and drop impact. Addition of Mn, Ce, Bi, and Ni to low-Ag-content SAC solder effectively improves the thermal-cycling reliability of joints without sacrificing the drop-impact performance. Taking into consideration the improvement in the bulk alloy microstructure and mechanical properties, wetting properties, and growth suppression of the interface intermetallic compound (IMC) layers, addition of Ti, In, Sb, Zn, Al, Fe, and Co to low-Ag-content SAC solder has the potential to improve the thermal-cycling reliability of joints without sacrificing the drop-impact performance. Consequently, further investigations of both thermal-cycling and drop reliability of these modified solder joints must be carried out in future work.

  19. Ni-Cu ion exchange observed for Ni(II)-porphyrins on Cu(111).

    PubMed

    Doyle, Catherine M; Cunniffe, John P; Krasnikov, Sergey A; Preobrajenski, Alexei B; Li, Zheshen; Sergeeva, Natalia N; Senge, Mathias O; Cafolla, Attilio A

    2014-04-01

    A Ni-Cu ion exchange has been observed for (5,15-dibromo-10,20-diphenylporphyrinato)nickel(II) (NiDBrDPP) and (5,10,15,20-tetrakis(4-bromophenyl)porphyrinato)nickel(II) (NiTBrPP) on Cu(111). The ion exchange proceeds at a faster rate for the NiDBrDPP/Cu(111) system compared to NiTBrPP/Cu(111). This is explained in terms of the macrocycle-substrate distance and the distortions that occur when the molecules are deposited on the Cu(111) surface. PMID:24548915

  20. Magnetic properties of YbTGe (T=Rh, Cu, Ag)

    Microsoft Academic Search

    K. Katoh; Y. Mano; K. Nakano; G. Terui; Y. Niide; A. Ochiai

    2004-01-01

    The magnetic properties of ternary equiatomic YbTGe (T=Rh, Cu, Ag) compounds have been investigated. YbRhGe is a new antiferromagnet with TN=7K which crystallizes in the orthorhombic TiNiSi-type structure. In YbCuGe, with the hexagonal LiGaGe-type structure, ferromagnetic ordering with a magnetic moment of 0.7?B\\/Yb occurs below 8K. On the other hand, in YbAgGe with the hexagonal ZrNiAl-type structure, the magnetic susceptibilities

  1. K-italic-shell ionization cross sections for Al, Ti, V, Cr, Fe, Ni, Cu, and Ag by protons and oxygen ions in the energy range 0. 3--6. 4 MeV

    SciTech Connect

    Geretschlaeger, M.; Benka, O.

    1986-08-01

    Absolute K-italic-shell ionization cross sections have been measured for thin targets of Al, Ti, and Cu for protons in the energy range 0.3--2.0 MeV and for thin targets of Ti, V, Cr, Fe, Ni, Cu, and Ag for oxygen ions in the energy range 1.36--6.4 Mev. The experimental results are compared to the perturbed-stationary-state (PSS) approximation with energy-loss (E), Coulomb (C), and relativistic (R) corrections, i.e., the ECPSSR approximation (Brandt and Lapicki), to the semiclassical approximation (Laegsgaard, Andersen, and Lund), and to a theory for direct Coulomb ionization of the 1s-italicsigma molecular orbital (Montenegro and Sigaud (MS)). The proton results agree within 3% with empirical reference cross sections. Also, the ECPSSR provides best overall agreement for protons. For oxygen ions, ECPSSR and MS predict experimental results satisfactorily for scaled velocities xi> or =0.4. For lower scaled velocities, the experimental cross sections become considerably higher than theoretical predictions for Coulomb ionization. This deviation increases with increasing Z-italic/sub 1//Z/sub 2/; it cannot be explained by electron transfer to the projectile or by ionization due to target recoil atoms.

  2. Self-Diffusion of small Ag and Ni islands on Ag(111) and Ni(111) using the self-learning kinetic Monte Carlo method

    NASA Astrophysics Data System (ADS)

    Islamuddin Shah, Syed; Nandipati, Giridhar; Kara, Abdelkader; Rahman, Talat S.

    2012-02-01

    We have applied a modified Self-Learning Kinetic Monte Carlo (SLKMC) method [1] to examine the self-diffusion of small Ag and Ni islands, containing up to 10 atom, on the (111) surface of the respective metal. The pattern recognition scheme in this new SLKMC method allows occupancy of the fcc, hcp and top sites on the fcc(111) surface and employs them to identify the local neighborhood around a central atom. Molecular static calculations with semi empirical interatomic potential and reliable techniques for saddle point search revealed several new diffusion mechanisms that contribute to the diffusion of small islands. For comparison we have also evaluated the diffusion characteristics of Cu clusters on Cu(111) and compared results with previous findings [2]. Our results show a linear increase in effective energy barriers scaling almost as 0.043, 0.051 and 0.064 eV/atom for the Cu/Cu(111), Ag/Ag(111), and Ni/Ni(111) systems, respectively. For all three systems, diffusion of small islands proceeds mainly through concerted motion, although several multiple and single atom processes also contribute. [1] Oleg Trushin et al. Phys. Rev. B 72, 115401 (2005) [2] Altaf Karim et al. Phys. Rev. B 73, 165411 (2006)

  3. A Study of Nanostructured Cu-Ag Composites

    Microsoft Academic Search

    Charney Anchilyn Davy

    2010-01-01

    It is desirable to use nanostructured composites to produce high-strength, high-conductive materials for magnet development. In this research, severe plastic deformation (e ? 2.0) is used to produce nanostructured Cu-Ag composites in an off-eutectic (Cu-16at%Ag) and an eutectic (Cu-60at%Ag) composite. These two compositions are chosen in order to obtain a better understanding of the off-eutectic microstructure which is comprised of

  4. Phase diagram of AuCu-Ag pseudobinary alloy

    Microsoft Academic Search

    K. Udoh; M. Ohta; K. Oki; K. Hisatsune

    2001-01-01

    The phase diagram of the AuCu-Ag pseudobinary alloy was determined by means of transmission electron microscopy (TEM). By\\u000a tetrahedron approximation of a cluster variation method, an isothermal section was obtained theoretically to reproduce the\\u000a AuCu-Ag pseudobinary phase diagram. As a result, the Au-Cu-Ag ternary phase diagram was also determined.

  5. Interfacial reactions in Ag-Sn\\/Cu couples

    Microsoft Academic Search

    Sinn-Wen Chen; Yee-Wen Yen

    1999-01-01

    Interfacial reactions between Sn-3.5 wt.%Ag, Sn-25 wt.%Ag, and Sn-74 wt.%Ag alloys with Cu substrate at 240C and 450C have\\u000a been studied here by examining the reaction couples. It is found that Sn is the fastest diffusion species among the three\\u000a elements during the reaction, while Ag is the slowest. The reaction path is liquid\\/?\\/?1\\/Cu for the Sn-3.5 wt.%Ag\\/Cu couples reacted

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

    SciTech Connect

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

    2014-01-14

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

  7. Tensile testing of free-standing Cu, Ag and Al thin films and Ag\\/Cu multilayers

    Microsoft Academic Search

    Haibo Huang; F. SPAEPEN

    2000-01-01

    Free standing polycrystalline thin films with a strong ?111? texture were tested in uniaxial tension. Studied were electron-beam deposited Ag, Cu and Al films, and Ag\\/Cu multilayers consisting of alternating Ag and Cu layers of equal thickness, between 1.5 nm and 1.5 ?m (bilayer repeat length, ?, between 3 nm and 3 ?m). The films had a total thickness of about 3 ?m. A thin

  8. Interfacial reactions and shear strengths between Sn-Ag-based Pb-free solder balls and Au\\/EN\\/Cu metallization

    Microsoft Academic Search

    Sang-Won Kim; Jeong-Won Yoon; Seung-Boo Jung

    2004-01-01

    The morphological and compositional evolutions of intermetallic compounds (IMCs) formed at three Pb-free solder\\/electroless\\u000a Ni-P interface were investigated with respect to the solder compositions and reflow times. The three Pb-free solder alloys\\u000a were Sn3.5Ag, Sn3.5Ag0.75Cu, and Sn3Ag6Bi2In (in wt.%). After reflow reaction, three distinctive layers, Ni3Sn4 (or Ni-Cu-Sn for Sn3.5Ag0.75Cu solder), NiSnP, and Ni3P, were formed on the electroless Ni-P

  9. Embedded Atom Method Potential for Ni-Cu Alloys and Its Applications for Ni, Cu growth on Cu(111)

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2012-02-01

    We developed a semi-empirical, many-body type model potential to investigate static and dynamic properties of Ni-Cu alloys. The formalism is based on the embedded atom method with improved optimization techniques. The Ni-Cu alloy potential was determined by fitting to data on lattice parameters, cohesive energies for L10, L11, L12, and L13 phases, together with vacancy formation energies, bulk modulus and elastic properties for L12, L13 phases. Our preliminary calculations for energy barriers for the diffusing Ni and Cu atoms on Cu(111) based on the nudged elastic band method are found to be consistent with the available experimental and other theoretical results. Our ultimate goal is to describe the varying characteristics in growing islands of pure Cu, Ni atoms and mixed Ni-Cu combinations on Cu(111) [S. Pons et al., Surf. Sci., 511, 449, (2002)].

  10. Thermodynamic description of the Cu–Ag–Zr system

    Microsoft Academic Search

    X. C. He; H. Wang; H. S. Liu; Z. P. Jin

    2006-01-01

    Based on the CALPHAD method, the Ag–Zr and Ag–Cu systems have been assessed thermodynamically. The excess Gibbs energy of the solution phases in the Cu–Ag–Zr system was modeled assuming random mixing of components. The ternary phase was defined as a stoichiometric compound due to the lack of efficient thermodynamic data. At first, parameters capable of describing all phases in the

  11. Electronic theory of the alloy phase stability of Cu-Ag, Cu-Au, and Ag-Au systems

    Microsoft Academic Search

    K. Terakura; T. Oguchi; T. Mohri; K. Watanabe

    1987-01-01

    It is demonstrated that electronic structure calculations using the local-density approximation with density-functional theory accounts for the distinctly different behaviors in the equilibrium phase diagrams among Cu-Ag, Cu-Au, and Ag-Au alloy systems. A detailed microscopic analysis is made based on the prescription proposed by Connolly and Williams.

  12. Reactions between oxides and Ag-sheathed Bi2Sr2CaCu2Ox conductors

    NASA Astrophysics Data System (ADS)

    Wesolowski, D. E.; Rikel, M. O.; Jiang, J.; Arsac, S.; Hellstrom, E. E.

    2005-07-01

    We studied reactions between Ag-sheathed Bi2Sr2CaCu2Ox (2212) conductors and a variety of oxides. We identified two intrinsic reactions: solid-state diffusion of a metallic species from the 2212 melt through the Ag sheath to react with an oxide, and direct reaction between Ag and an oxide. The dominant species that diffused through the Ag sheath was Cu because its solubility in Ag and diffusivity through Ag under 2212 melt processing conditions are the highest of the BSCCO metallic species. Al2O3, CeO2, pure SiO2, Y2O3, ZrO2, CaZrO3, and SrZrO3 were identified as non-reactive when heat treated in contact with Ag-sheathed 2212 tape. Fe2O3, MgO, and NiO reacted with Cu that diffused through Ag during the heat treatment. Cr2O3 and SiO2-based Pyrex glass reacted directly with Ag in the sheath during the heat treatment, which can create cracks and pinholes in the Ag sheath through which liquid can flow. Based on thermodynamic estimates, we calculated the Cu concentration in Ag at the 2212/Ag interface at 900 °C and 1 bar O2 to be between 0.15 and 0.22 at.%, which is consistent with 0.19 ± 0.02 at.% deduced from the experimentally measured diffusion flux.

  13. Temperature dependent effects during Ag deposition on Cu(110)

    SciTech Connect

    Taylor, T.N.; Muenchausen, R.E.; Hoffbauer, M.A.; Denier van der Gon, A.W.; van der Veen, J.F. (Los Alamos National Lab., NM (USA); FOM-Instituut voor Atoom-en Molecuulfysica, Amsterdam (Netherlands))

    1989-01-01

    The composition, structure, and morphology of ultrathin films grown by Ag deposition on Cu(110) were monitored as a function of temperature using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and medium energy ion scattering (MEIS). Aligned backscattering measurements with 150 keV He ions indicate that the Ag resides on top of the Cu and there is no significant surface compound formation. Measurements with LEED show that the Ag is initially confined to the substrate troughs. Further deposition forces the Ag out of the troughs and results in a split c(2 {times} 4) LEED pattern, which is characteristic of a distorted Ag(111) monolayer template. As verified by both AES and MEIS measurements, postmonolayer deposition of Ag on Cu(110) at 300K leads to a pronounced 3-dimensional clustering. Ion blocking analysis of the Ag clusters show that the crystallites have a (110)-like growth orientation, implying that the Ag monolayer template undergoes a rearrangement. These data are confirmed by low temperature LEED results in the absence of clusters, which indicate that Ag multilayers grow from a Ag--Cu interface where the Ag is captured in the troughs. Changes observed in the film structure and morphology are consistent with a film growth mechanism that is driven by overlayer strain response to the substrate corrugation. 16 refs., 4 figs.

  14. Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2O3; Sn;

    E-print Network

    Garmestani, Hamid

    Acetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In; Fe; Pb; Ni; NiO, Ni2O3; Sn; SnO2; Ti; Zn Hydrofluoric Acid (HF): GaAs; Ni; SiO2; Ti Nitric Acid (HNO3): C; Cu; GaAs; In; Fe; Pb; Ni; Ag; Pd; Pt; Sn; Ti; Zn; ZnO Phosphoric Acid (H3PO4): Al; Cu; GaAs; Ga

  15. Reactions and spreading in the Cu--Ag system

    Microsoft Academic Search

    Sharps

    1978-01-01

    Sessile drop experiments were conducted using several liquid and solid compositions selected from the Cu--Ag phase diagram. Reactions between the solid and the liquid lead to spreading; a number of chemical nonequilibrium conditions were established using the various compositions. The Cu liquidus drop on the Cu solidus at 900°C was in equilibrium assuming that the drop did not melt so

  16. Synthesis and characterization of Ag-Co-Ni nanowires.

    PubMed

    Rai, R K; Singh, M Pratap; Srivastava, C

    2014-09-01

    This work provides an electrodeposition-based methodology for synthesizing multicomponent nanowires containing Ag, Co and Ni atoms. Nanowire morphology was obtained by using an anodic alumina membrane with cylindrical pores of ? 200-nm diameter. Structural, compositional and magnetic characterization revealed that the as-synthesized nanowires adopted a core-shell microstructure. The core (axial region) contained pure Ag phase volumes with a plate-like morphology oriented perpendicular to the nanowire axis. The shell (peripheral region) contained pure Ag nanoparticles along with superparamagnetic Co and Ni rich clusters. PMID:24956929

  17. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  18. On the elastic moduli of nanocrystalline Fe, Cu, Ni, and Cu--Ni alloys prepared by mechanical milling\\/alloying

    Microsoft Academic Search

    T. D. Shen; C. C. Koch; T. Y. Tsui; G. M. Pharr

    1995-01-01

    The Young`s moduli of nanocrystalline, Fe, Cu, Ni, and Cu--Ni alloys prepared by mechanical milling\\/alloying have been measured by the nanoindentation technique. The results indicate that the Young`s moduli of nanocrystalline Cu, Ni, and Cu--Ni alloys with a grain size ranging from 17 to 26 nm are similar to those of the corresponding polycrystals. The dependence of Young`s modulus of

  19. Magnetic phase transition in Co/Cu/Ni/Cu(100) and Co/Fe/Ni/Cu(100).

    PubMed

    Won, C; Wu, Y Z; Scholl, A; Doran, A; Kurahashi, N; Zhao, H W; Qiu, Z Q

    2003-10-01

    Magnetic phase transitions in coupled magnetic sandwiches of Cu/Co/Cu/Ni/Cu(100) and Cu/Co/Fe/Ni/Cu(100) are investigated by photoemission electron microscopy. Element-specific magnetic domains are taken at room temperature to reveal the critical thickness at which the magnetic phase transition occurs. The results show that a coupled magnetic sandwich undergoes three types of magnetic phase transitions depending on the two ferromagnetic films' thickness. A phase diagram is constructed and explained in the process of constructing Monte Carlo simulations, which corroborate the experimental results. PMID:14611550

  20. Wetting process and interfacial characteristic of Sn-3.0Ag-0.5Cu on different substrates at temperatures ranging from 503 K to 673 K

    NASA Astrophysics Data System (ADS)

    Zang, Likun; Yuan, Zhangfu; Xu, Hongyan; Xu, Bingsheng

    2011-03-01

    Wetting process and interfacial characteristic of Sn-3.0Ag-0.5Cu have been investigated at temperatures ranging from 503 K to 673 K on Cu, Ni, stainless steel and quartz, respectively. The reactive wetting behavior of Sn-3.0Ag-0.5Cu melt alloy on Cu and Ni substrates were investigated. Contact angles decrease as exponential decay and equilibrium contact angles decrease between the solder and Cu, Ni substrates monotonously with the temperature increasing. The configuration of the triple line of Sn-3.0Ag-0.5Cu/Cu is discussed by the description of equilibrium. The calculated results based on experimental values of tension balances along each of the three interfaces at this final state show good agreement with theoretical analysis. Intermetallics of the Sn-3.0Ag-0.5Cu/Ni interface are identified as (Cu, Ni) 6Sn 5 adjacent to the solder and Ni 3Sn 4 adjacent to the Ni substrate, respectively. The contact angles between Sn-3.0Ag-0.5Cu and quartz, stainless steel substrates were measured to be greater than 90°, which means non-wetting, in the temperature range from 503 K to 673 K. Liquid-solid interfacial energy between the solder and different substrates are obtained based on the surface tension of molten solder and equilibrium contact angles at different temperatures. These results are of practical interest for composite lead-free solders preparations and joining of Sn-3.0Ag-0.5Cu to various substrates.

  1. Surface Segregation in Cu-Ni Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

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

  2. Size effect on the stability of Cu–Ag nanoalloys

    Microsoft Academic Search

    Julibeth M. Martinez De La Hoz; Rafael Callejas Tovar; Perla B. Balbuena

    2009-01-01

    Classical molecular dynamics (MD) simulations are used to study the phase stability of Cu–Ag nanoalloys based on the analysis of their thermodynamic mixing properties for both random and core-shell clusters as functions of nanoparticle size, temperature and composition. At 298 K, results for nanoalloys of increasing size at fixed composition suggest that alloying Cu and Ag is thermodynamically feasible only for

  3. Misfit dislocations in epitaxial Ni/Cu bilayer and Cu/Ni/Cu trilayer thin films.

    SciTech Connect

    Misra, A. (Amit); Hoagland R. G. (Richard G.); Nastasi, Michael Anthony,; Kung, H. (Harriett); Hirth, John Price,; Yamamoto, T. (Tadashi)

    2001-01-01

    Misfit dislocations at the interfaces of bilayer (Ni/Cu) and trilayer (Cu/Ni/Cu) thin films are examined by plan-view TEM observation. In the bilayers, the spacing of misfit dislocations is measured as a fiinction of nickel layer thickness. The critical thickness, at which misfit dislocations start to appear with the loss of coherency, was found to be about 2 nm. The spacing of the misfit dislocations decreases with increasing nickel layer thickness and reaches a plateau at the thickness of 30 nm. The minimum spacing is observed to be about 20 nm. g {center_dot} b analysis of the cross-grid of misfit dislocations revealed 90{sup o} Lomer dislocations of <110>{l_brace}001{r_brace} type lying in the (001) interface plane at the relatively large thickness of nickel layer, but 60{sup o} glide dislocations of <110>{l_brace}111{r_brace} type at the relatively small thickness of nickel layer. In the trilayers, misfit dislocations formed at both interfaces. The spacing of the misfit dislocation is in agreement with that of the bilayers with similar nickel layer thickness. The misfit dislocation arrays at the two interfaces, having the same line directions, are 60{sup o} dislocations with edge components with opposite signs but are displaced with respect to each other in the two different interface planes. This suggests that the strain field of the dislocations has a strong influence on the position of the misfit dislocations at the subsequent interface.

  4. A comparative study of microstructure and mechanical properties among Cu\\/Sn\\/Cu, Ni\\/Sn\\/Ni and Cu\\/Sn\\/Ni solder joints

    Microsoft Academic Search

    Bo Wang; Fengshun Wu; Yiping Wu; Bing An; Hui Liu; Jian Zou

    2011-01-01

    Purpose – The purpose of this paper is to identify the solder joint with optimal mechanical properties among Cu\\/Sn\\/Cu, Ni\\/Sn\\/Ni and Cu\\/Sn\\/Ni solder joints. Design\\/methodology\\/approach – Solder joints with the same specimen shape were prepared by reflow. The microstructures were observed and analyzed by scanning electron microscopy and tensile testing was carried out to investigate the mechanical properties. Findings –

  5. Nanoindentation characterization of Ni–Cu–Sn IMC layer subject to isothermal aging

    Microsoft Academic Search

    Luhua Xu; John H. L. Pang

    2006-01-01

    Lead-free Sn–Ag–Cu(SAC) solder joint on Cu–OSP and ENIG subject to thermal testing leads to IMC growth and causes corresponding reliability concerns at the interface. Modulus and hardness of these IMCs were characterized by Nanoindentation CSM from plan view in this study. A plan-view IMC surface was prepared by deep etching and slight polishing method. When SAC\\/Ni(Au) solder joint were subject

  6. Structure of the ophiolite-hosted Outokumpu Cu-Co-Zn-Ni-Ag-Au sulfide ore district revealed by combined 3D modelling and 2D high-resolution seismic reflection data

    NASA Astrophysics Data System (ADS)

    Saalmann, Kerstin; Laine, Eevaliisa

    2015-04-01

    The Outokumpu district within the North Karelia Schist Belt in eastern Finland hosts Cu-Co-Zn-Ni-Ag-Au sulfide deposits which are associated with Palaeoproterozoic ophiolitic metaperidotites that were tectonically interleaved with allochthonous metaturbidites. Extensive metasomatism of the peridotites produced a rim of quartz-carbonate-calc-silicate rocks, grouped as the Outokumpu assemblage (OKA). A tectonic history comprising various phases of folding and shearing followed by several faulting events dismembered the metaperidotites so that ore bodies cannot be easily followed along strike. Future exploration has to expand the search into deeper areas and consequently requires better knowledge of the subsurface geology. In order to unravel the complex structure 3D geologic models of different scales have been built using a variety of information: geological maps, aeromagnetic and gravity maps, digital terrain models, mine cross sections, drill core logs combined with observations from underground mine galleries, structural measurements, and data from seismic survey lines. The latter have been used to detect upper crustal-scale structures and have been reprocessed for our purpose. The models reveal that the ore body has formed during remobilisation of a proto-ore and is closely related to thrust zones that truncate the OKA. Later faults dismembered the ore explaining the variable depth of the different ore bodies along the Outokumpu ore zone. On a larger scale, at least four km-scale thrust sheets separated by major listric shear zones (curved dislocations in the seismic lines) can be recognized, each internally further imbricated by subordinate shear zones containing a number of lens-shape bodies of probably OKA rocks. Thrust stacking was followed by at least 3 stages of faulting that divided the ore belt into fault-bounded blocks with heterogeneous displacements: (i) NW-dipping faults with unresolved kinematics, (ii) reverse faulting along c.50°-60° SE-dipping faults , (iii) SW-NE to SSW-NNE striking faults which may have formed at an earlier stage and have been reactivated. The specific Outokumpu alteration assemblage around metaperidotite bodies combined with shear zones acting as pathways for fluids are the main vectors to mineralization. Seismic reflection data do not provide a simple tool to directly detect the sites of Outokumpu assemblage bodies at depth but they identify strong reflector zones which are characteristic for though not exclusive to the assemblage. Our approach shows that 3D modelling combining surface geology and geophysical data and a good knowledge about the structural evolution substantially improves the interpretation of reflectors and their assignments to rock units of interest. It thus enhances the chances for locating potentially economic bodies at depth and allows delineating target areas for detailed exploration.

  7. Les minéralisations Cu_(Ni_Bi_U_Au_Ag) d'Ifri (district du Haut Seksaoua, Maroc) : apport de l'étude texturale au débat syngenèse versus épigenèseThe Cu_(Ni_Bi_U_Au_Ag) mineralization of Ifri ('Haut Seksaoua' district, Morocco): contribution of a textural study to the discussion syngenetic versus epigenetic

    NASA Astrophysics Data System (ADS)

    Barbanson, Luc; Chauvet, Alain; Gaouzi, Aziz; Badra, Lakhifi; Mechiche, Mohamed; Touray, Jean Claude; Oukarou, Sa??d

    2003-11-01

    The Cu ore of Ifri is a chalcopyrite stockwork hosted by Cambrian formations and was until now interpreted as a syngenetic massive sulphide deposit. Textural studies highlight two generations of pyrite early (Py I) and late (Py II) with respect to the regional deformation. The chalcopyrite stockwork overprinted Py II, outlining the epigenetic nature of the Cu mineralization. Regarding the origin of Cu-depositing fluids, the presence in the stockwork paragenesis of an U, W, Sn association and preliminary Pb/Pb dating of a brannerite belonging to this association suggest a contribution of the Tichka granite. To cite this article: L. Barbanson et al., C. R. Geoscience 335 (2003).

  8. Structure and thermal stability of AgCu chiral nanoparticles

    NASA Astrophysics Data System (ADS)

    Bochicchio, D.; Ferrando, R.

    2012-05-01

    The structure and thermal stability of AgCu core-shell chiral nanoparticles is investigated by means of global optimization searches and molecular-dynamics simulations within an atomistic model. The most energetically stable structures are searched for depending on the number N Ag of Ag atoms in the outer shell. Both icosahedral and C5 symmetry structures are considered. The thermal stability of the structures is studied for magic sizes and compositions by analyzing the melting transition. It is found that chiral shells are the most favourable in a wide range of N Ag and that the structures present a notable thermal stability.

  9. EBSD Investigation of Cu-Sn IMC Microstructural Evolution in Cu/Sn-Ag/Cu Microbumps During Isothermal Annealing

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Hsu, L. H.; Wang, N. K.; Ho, C. E.

    2014-01-01

    The microstructural evolution of Cu/Sn-Ag (~5 ?m)/Cu Cu-bump-on-line (CuBOL) joints during isothermal annealing at 180°C was examined using a field-emission scanning electron microscope equipped with an electron backscatter diffraction (EBSD) system. Cu6Sn5 and Cu3Sn were the two key intermetallic compound (IMC) species that appeared in the CuBOL joints. After annealing for 24 h (= t), the solder had completely converted to Cu-Sn IMCs, forming an "IMC" joint with Cu/Cu3Sn/Cu6Sn5/Cu3Sn/Cu structure. EBSD analyses indicated that the preferred orientation of the hexagonal Cu6Sn5 (?) was , while the preferred orientation was (100) for the monoclinic Cu6Sn5 structure (?'). Upon increasing t to 72 h, Cu6Sn5 entirely transformed into Cu3Sn, and the IMC joint became Cu/Cu3Sn/Cu accordingly. Interestingly, the grain size and crystallographic orientation of Cu3Sn displayed location dependence. Detailed EBSD analyses in combination with transmission electron microscopy on Cu3Sn were performed in the present study. This research offers better understanding of crystallographic details, including crystal structure, grain size, and orientation, for Cu6Sn5 and Cu3Sn in CuBOL joints after various annealing times.

  10. Perpendicularly magnetized spin filtering Cu/Ni multilayers

    SciTech Connect

    Shirahata, Yasuhiro; Wada, Eiji; Itoh, Mitsuru; Taniyama, Tomoyasu, E-mail: taniyama.t.aa@m.titech.ac.jp [Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2014-01-20

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

  11. Magnetoresistance in spin-valves with antiferromagnetic NiO\\/CuO\\/NiO trilayers

    Microsoft Academic Search

    S. S. Lee; D. G. Hwang; C. M. Park; K. A. Lee

    1997-01-01

    Magnetoresistance and exchange coupling in spin-valve films using antiferromagnetic NiO\\/CuO\\/NiO trilayers were investigated. The exchange coupling field Hex and MR ratio in the NiO300 Å \\/CuO300 Å\\/NiO300 Å\\/NiFe50 Å\\/Cu20 Å\\/NiFe50 Å films were almost constant values of 100 Oe and 4.5% despite of the variation of the inserted CuO thickness, however, the coercive field Hc increased from 80 Oe to

  12. Injection synthesis of Ni-Cu@Au-Cu nanowires with tunable magnetic and plasmonic properties.

    PubMed

    Zeng, Deqian; Chen, Yuanzhi; Lu, Aolin; Li, Meng; Guo, Huizhang; Wang, Junbao; Peng, Dong-Liang

    2013-12-21

    A facile nonaqueous injection method has been developed for the construction of one-dimensional nanostructure consisting of a magnetic alloy (Ni-Cu) core and a plasmonic alloy (Au-Cu) shell. The obtained Ni-Cu@Au-Cu nanowires exhibit tunable optical and magnetic properties. PMID:24177016

  13. An embedded-atom potential for the Cu Ag system

    Microsoft Academic Search

    P. L. Williams; Y. Mishin; J. C. Hamilton

    2006-01-01

    A new embedded-atom method (EAM) potential has been constructed for Ag by fitting to experimental and first-principles data. The potential accurately reproduces the lattice parameter, cohesive energy, elastic constants, phonon frequencies, thermal expansion, lattice-defect energies, as well as energies of alternate structures of Ag. Combining this potential with an existing EAM potential for Cu, a binary potential set for the

  14. Pb-free Sn-Ag-Cu ternary eutectic solder

    DOEpatents

    Anderson, I.E.; Yost, F.G.; Smith, J.F.; Miller, C.M.; Terpstra, R.L.

    1996-06-18

    A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217 C and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid ``mushy`` zone) relative to the eutectic melting temperature (e.g. up to 15 C above the eutectic melting temperature). 5 figs.

  15. The role of interfaces in NiFe/Cu/NiFe spin values

    NASA Astrophysics Data System (ADS)

    Nozières, J. P.; Speriosu, V. S.; Gurney, B. A.; Dieny, B.; Lefakis, H.; Huang, T. C.

    1993-03-01

    A sharp decrease of the giant magnetoresistance amplitude by interface roughening is observed in NiFe/Cu/NiFe/FeMn spin valves, which we attribute to the presence of high resistivity, compositionally intermixed regions at the NiFe/Cu interfaces. These results show that interfacial spin independent scattering must be included in the theory of GMR.

  16. Dynamic viscosities of pure tin and Sn-Ag, Sn-Cu, and Sn-Ag-Cu eutectic melts

    NASA Astrophysics Data System (ADS)

    Rozhitsina, E. V.; Gruner, S.; Kaban, I.; Hoyer, W.; Sidorov, V. E.; Popel', P. S.

    2011-02-01

    The dynamic viscosities of the melts of pure tin and eutectic Sn-Ag, Sn-Cu, and Sn-Ag-Cu alloys are studied in heating followed by cooling, and the maximum heating temperature was 1200°C. An irreversible decrease in the viscosity is found in the temperature range 800-1000°C in the polytherms of all melts. This finding is related to the loss of a local order in a melt and can be used to develop temperature regimes for the production of lead-free solders.

  17. Nature of anodic dissolution of Cu--Zn, Ag--Zn, and Ag--Cd alloys

    Microsoft Academic Search

    I. K. Marshakov; V. S. Bolychev; O. P. Potapova

    1973-01-01

    By the rotating disc ring electrode method the dissolution mechanism of ; alloys of the Cu-- Zn, Ag-- Zn, and Ag-- Cd system in 0.5 N NaCl, 0.1 N Hâ; SOâ, 0.1 N HCl, and 0.1 N KNOâ was studied. Th e results obtained ; were compared with the anode behavior of the system. These systems give a series ;

  18. Intermetallic compound layer growth at the interface between Sn–Cu–Ni solder and Cu substrate

    Microsoft Academic Search

    Jeong-Won Yoon; Young-Ho Lee; Dae-Gon Kim; Han-Byul Kang; Su-Jeong Suh; Cheol-Woong Yang; Chang-Bae Lee; Jong-Man Jung; Choong-Sik Yoo; Seung-Boo Jung

    2004-01-01

    Phase analysis and growth kinetics of intermetallic compound (IMC) layers formed between low cost Sn–Cu–Ni solder for wave soldering and Cu substrate by solid state isothermal aging were examined at temperatures between 80 and 150°C for 0 to 60 days. The IMC layer was composed of two phases; Cu6Sn5 (also (Cu,Ni)6Sn5) adjacent to the solder, Cu3Sn adjacent to the copper.

  19. Synthesis and characterization of Ni/Ag nanocomposite for surface enhanced Raman scattering measurement

    NASA Astrophysics Data System (ADS)

    Manoj, K.; Gayathri, S.; Jayabal, P.; Ramakrishnan, V.

    2015-06-01

    Ni nanoflowers were successfully synthesized by wet chemical method using hydrazine hydrate as reducing agent. Ni/Ag nanocomposite was prepared by simple redox-transmetalation reaction by using the synthesized Ni nanoflowers and silver nitrate as precursors. The x-ray diffraction pattern revealed the formation of face centered cubic crystal structured Ni nanostructure and Ni/Ag nanocomposite. Scanning electron micrograph was used to study the surface morphology of Ni nanoflowers and Ni/Ag nanocomposite. The energy dispersive x-ray spectrometry analysis showed the purity of the prepared samples. The synthesized Ni/Ag nanocomposite was made into film and used as surface enhanced Raman scattering (SERS) substrate for probing the SERS signal of methylene blue molecule. The Ni/Ag nanocomposite showed significantly stronger Raman signal than the bare glass substrate.

  20. The Ag–Cu–Ge ternary phase diagram

    Microsoft Academic Search

    Els Nagels; J. Van Humbeeck; L. Froyen

    2009-01-01

    The Ag–Cu–Ge phase diagram is not very well elaborated. In this work an attempt is made to validate the phase diagram in the area of the ternary eutectic and to decide whether it is a suitable model system for solidification experiments. The different steps in the solidification sequence are separately discussed and analysed. It is shown that an optimization of

  1. Precipitations in a dental Ag-Pd-Cu-Au alloy.

    PubMed

    Herø, H; Jørgensen, R; Sørbrøden, E; Suoninen, E

    1982-05-01

    The structure of a dental Ag-PD-Cu-Au alloy has been studied after centrifugal casting and various heat treatments. By transmission electron microscopy, a high density of small fct particles, assumed to be PdCu, was observed, but, in addition, finely-spaced rods of approximately equal to 0.05 micrometer (500 A) diameter with an fcc structure precipitated on the [100] planes of the matrix were found. On the basis of their structure and the pertaining lattice parameter, these rods are assumed to be Cu-rich. They could also be observed by scanning electron microscopy, but not at annealing temperatures lower than 425 degrees C. PMID:6953095

  2. Exchange bias field and coercivity of [NiFe/NiFeCuMo/NiFe]/FeMn multilayers

    NASA Astrophysics Data System (ADS)

    Choi, Jong-Gu; Hwang, Do-Guwn; Lee, Sang-Suk; Rhee, Jang-Roh

    2013-06-01

    The exchange bias field ( H EX ) and the coercivity ( H C ) of the intermediate, super-soft magnetic NiFeCuMo layer were investigated for different thicknesses of the bottom NiFe layer. The H EX of the triple-pinned NiFe (4 nm)/NiFeCuMo ( t NiFeCuMo = 1 nm)/NiFe (4 nm)/FeMn multilayer has a maximum value of 77 Oe, which is more than that of a single-pinned NiFe (8 nm)/FeMn layer (42 Oe). A multilayer system with the NiFeCuMo layer inserted between the pinned and the free NiFe layers can be used as a giant magnetoresistive spin-valve device for biosensors with improved magnetic sensitivity.

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

    SciTech Connect

    Witusiewicz, V.T.; Sommer, F.

    2000-04-01

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

  4. Measured fast-neutron activation cross sections of Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti at 10.3 and 14.8 MeV and for the continuum neutron spectrum produced by 7-MeV deuterons on a thick Be-metal target

    SciTech Connect

    Meadows, J.W.; Smith, D.L.; Greenwood, L.R. [Argonne National Lab., IL (United States); Haight, R.C. [Los Alamos National Lab., NM (United States); Ikeda, Y.; Konno, C. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Reactor Engineering

    1991-12-31

    Four identical sample packets containing elemental Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti have been irradiated in three distinct accelerator neutron fields, at Argonne National Laboratory and Los Alamos National Laboratory, USA, and Japan Atomic Energy Research Institute, Tokai, Japan, under the auspices of an International Atomic Energy Agency Coordinated Research Program to investigate the production of long-lived radionuclides for fusion waste disposal applications. Final experimental results are presented here for 13 distinct reactions which ultimately lead to production of the following activities: Ag-106m,108m; Co-60g; Cr-51; Eu-150g, -152g; Hf-175,-179m2; Mn-54; Sc-46g,-47,-48; Tb-158g. The neutron fluence standard used was Ni-58(n,p)Co-58. The measured data include differential cross section values at 10.3 and 14.8 MeV, and integral cross sections for the continuum neutron spectrum produced by 7-MeV deuterons incident on a thick Be-metal target. The U-238(n,f) cross section was also measured at 10.3 MeV as a consistency check on the experimental technique. Some of the results of this study are compared with corresponding values from earlier work at Argonne and from ENDF/B-6. 134 refs., 1 fig., 9 tabs.

  5. Measured fast-neutron activation cross sections of Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti at 10. 3 and 14. 8 MeV and for the continuum neutron spectrum produced by 7-MeV deuterons on a thick Be-metal target

    SciTech Connect

    Meadows, J.W.; Smith, D.L.; Greenwood, L.R. (Argonne National Lab., IL (United States)); Haight, R.C. (Los Alamos National Lab., NM (United States)); Ikeda, Y.; Konno, C. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Dept. of Reactor Engineering)

    1991-01-01

    Four identical sample packets containing elemental Ag, Cu, Eu, Fe, Hf, Ni, Tb and Ti have been irradiated in three distinct accelerator neutron fields, at Argonne National Laboratory and Los Alamos National Laboratory, USA, and Japan Atomic Energy Research Institute, Tokai, Japan, under the auspices of an International Atomic Energy Agency Coordinated Research Program to investigate the production of long-lived radionuclides for fusion waste disposal applications. Final experimental results are presented here for 13 distinct reactions which ultimately lead to production of the following activities: Ag-106m,108m; Co-60g; Cr-51; Eu-150g, -152g; Hf-175,-179m2; Mn-54; Sc-46g,-47,-48; Tb-158g. The neutron fluence standard used was Ni-58(n,p)Co-58. The measured data include differential cross section values at 10.3 and 14.8 MeV, and integral cross sections for the continuum neutron spectrum produced by 7-MeV deuterons incident on a thick Be-metal target. The U-238(n,f) cross section was also measured at 10.3 MeV as a consistency check on the experimental technique. Some of the results of this study are compared with corresponding values from earlier work at Argonne and from ENDF/B-6. 134 refs., 1 fig., 9 tabs.

  6. Magnetic properties of YbTGe (T=Rh, Cu, Ag)

    NASA Astrophysics Data System (ADS)

    Katoh, K.; Mano, Y.; Nakano, K.; Terui, G.; Niide, Y.; Ochiai, A.

    2004-01-01

    The magnetic properties of ternary equiatomic YbTGe (T=Rh, Cu, Ag) compounds have been investigated. YbRhGe is a new antiferromagnet with TN=7 K which crystallizes in the orthorhombic TiNiSi-type structure. In YbCuGe, with the hexagonal LiGaGe-type structure, ferromagnetic ordering with a magnetic moment of 0.7 ?B/Yb occurs below 8 K. On the other hand, in YbAgGe with the hexagonal ZrNiAl-type structure, the magnetic susceptibilities along the a- and c-axis follow the Curie-Weiss law with trivalent Yb at high temperatures. No feature of some kind of phase transition is found above 1.2 K. The electrical resistivity along the a- and c-axis shows metallic behavior. The ratio of the specific heat to temperature increases remarkably below 10 K and shows a large value of 570 mJ/molK 2 at 1.6 K which indicates a heavy-fermion nature of YbAgGe.

  7. Thermal fatigue properties of lead-free solders on Cu and NiP under bump metallurgies

    Microsoft Academic Search

    Charles Zhang; Jong-Kai Lin; Li Li

    2001-01-01

    Three Pb-free solders, SnCu0.7, SnAg3.8Cu0.7 and SnAg3.5 were evaluated on both electroless NiP and electroplated Cu under bump metallurgies (UBM) for flip chip applications. Eutectic SnPb37 solder was also evaluated as a baseline comparison with the Pb-free solders. Test dice with a size of 12.6×7.5 mm2 were direct flip chip attached to test boards with variety of solder alloy\\/UBM combinations.

  8. Mechanical properties of pure Ni and Ni-alloy substrate materials for Y Ba Cu O coated superconductors

    NASA Astrophysics Data System (ADS)

    Clickner, C. C.; Ekin, J. W.; Cheggour, N.; Thieme, C. L. H.; Qiao, Y.; Xie, Y.-Y.; Goyal, A.

    2006-06-01

    Mechanical properties of rolling-assisted, biaxially-textured substrates (RABiTS) and substrates for ion-beam assisted deposition (IBAD) coated superconductors are measured at room temperature, 76, and 4 K. Yield strength, Young's modulus, and the proportional limit of elasticity are determined, tabulated and compared. Results obtained are intended to serve as a database of mechanical properties of substrates having the same anneal state and texture as those incorporated in the general class of RE-Ba-Cu-O coated conductor composites (RE = rare earth). The RABiTS materials measured are pure Ni, Ni-13at.%Cr, Ni-3at.%W-2at.%Fe, Ni-10at.%Cr-2at.%W, and Ni-5at.%W. The IBAD substrate materials included Inconel 625 and Hastelloy C-276. The Ni alloys are substantially stronger and show higher strains at the proportional limit than those of pure Ni. Substrates fully coated with buffer layers, ?1 ?m of Y-Ba-Cu-O, and 3-5 ?m of Ag have similar mechanical properties (at 76 K) as the substrate alone. Somewhat surprisingly, plating an additional 30-40 ?m of Cu stabilizer onto high-yield-strength (690 MPa) Hastelloy coated conductors ˜100 ?m thick, reduces the overall yield strength of the composite structure by only about 10-12% at 76 K and 12-14% at room temperature; this indicates that the Cu layer, despite its relatively soft nature, contributes significantly to the overall strength of even high-strength coated conductors.

  9. Effects of cooling speed on microstructure and tensile properties of Sn–Ag–Cu alloys

    Microsoft Academic Search

    K. S Kim; S. H Huh; K Suganuma

    2002-01-01

    The microstructures and tensile properties of three typical Sn–Ag–Cu alloys, Sn–3.0wt.%Ag–0.5wt.%Cu, Sn–3.5wt.%Ag–0.7wt.%Cu and Sn–3.9wt.%Ag–0.6wt.%Cu, prepared under three different cooling conditions were evaluated after casting. The microstructures of all rapidly cooled specimens consisted of the eutectic phase of ?-Sn with fine fibrous Ag3Sn dispersion surrounding primary ?-Sn grains. The slowly cooled Sn–3.5Ag–0.7Cu and Sn–3.9Ag–0.6Cu alloys exhibited additional large primary Ag3Sn platelets,

  10. Photoluminescence of SrS:Cu,Ag and SrS 1- xSe x:Cu,Ag thin films

    NASA Astrophysics Data System (ADS)

    Poelman, D.; Wauters, D.; Van Meirhaeghe, R. L.; Cardon, F.

    2000-01-01

    The photoluminescence (PL) of SrS:Cu,Ag and SrS 1- xSe x:Cu,Ag thin films has been investigated. The influence of rapid thermal annealing conditions and Cu dopant concentration on the PL intensity has been studied. The PL emission spectrum was measured as a function of both Cu concentration and temperature. An unexpected PL intensity peak was observed around a temperature of 54 K.

  11. Theoretical studies of diatomic and triatomic systems containing the group IB atoms Cu, Ag, and Au

    NASA Technical Reports Server (NTRS)

    Walch, Stephen P.; Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.

    1986-01-01

    Selected portions of the ground state potential energy surfaces of the Cu3, Ag3, AgCu2, and AuCu2 trimers are studied at the single-reference singles plus doubles configuration interaction and couple pair functional levels correlating 33 electrons. The calculations use the effective core potentials of Hay and Wadt (1985) to replace the deep core levels. The Cu3 and Ag3 molecules are found to have 2B2 obtuse-angled ground states, with low-lying 2A1 acute-angled excited states. The AgCu2 and AuCu2 molecules have 2A1 acute-angled ground states. The Cu3 molecule has a smaller 3d population than Ag3, and Cu3 has a smaller s electron density in the open-shell orbital than does Ag3, in agreement with recent ESR experiments.

  12. Application of cluster-plus-glue-atom model to barrierless Cu–Ni–Ti and Cu–Ni–Ta films

    SciTech Connect

    Li, Xiaona, E-mail: lixiaona@dlut.edu.cn; Ding, Jianxin; Wang, Miao; Dong, Chuang [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, Dalian 116024 (China); Chu, Jinn P. [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China)

    2014-11-01

    To improve the thermal stability of copper and avoid its diffusion into surrounding dielectrics or interfacial reactions with them, the authors applied the cluster-plus-glue-atom model to investigate barrierless Cu–Ni–M (M?=?Ti or Ta) seed layers. The dissolution of the third element (Ti or Ta) in the Cu lattice with the aid of Ni significantly improved the thermal stability of the Cu seed layer. The appropriate M/Ni (M?=?Ti or Ta) ratio was selected to obtain a low resistivity: the resistivity was as low as 2.5??? cm for the (Ti{sub 1.5/13.5}Ni{sub 12/13.5}){sub 0.3}Cu{sub 99.7} film and 2.8??? cm for the (Ta{sub 1.1/13.1}Ni{sub 12/13.1}){sub 0.4}Cu{sub 99.6} film after annealing at 500?°C for 1?h. After annealing at 500?°C for 40?h, the two films remained stable without forming a Cu{sub 3}Si compound. The authors confirmed that the range of applications of the cluster-plus-glue-atom model could be extended. Therefore, a third element M with negative enthalpies of mixing with both Cu and Ni could be selected, under the premise that the mixing enthalpy of M–Ni is more negative than that of M–Cu.

  13. A plastic Zr–Cu–Ag–Al bulk metallic glass

    Microsoft Academic Search

    X. Wang; Q. P. Cao; Y. M. Chen; K. Hono; C. Zhong; Q. K. Jiang; X. P. Nie; L. Y. Chen; J. Z. Jiang

    2011-01-01

    An intrinsically plastic Zr53.8Cu31.6Ag7.0Al7.6 bulk metallic glass with large bending and compressive plastic strains was fabricated. Through transmission electron microscopy, three-dimensional atom probe and anomalous small-angle X-ray scattering techniques, the possibility of plasticity induced by microstructural and chemical inhomogeneity was ruled out in the as-cast alloy. The plasticity can change dramatically in a narrow composition range, even though all the

  14. In situ growth and characterization of Ag and Cu nanowires

    Microsoft Academic Search

    X. Ding; G. Briggs; W. Zhou; Q. Chen; L.-M. Peng

    2006-01-01

    Nanowires of Ag and Cu have been produced from metal-loaded zeolites and micropore-containing mesoporous silica SBA-15 in situ inside the electron microscope. The structures of the nanowires have been characterized by using high-resolution electron microscopy and the compositions have been examined by energy dispersive x-ray spectroscopy. The growth of single-crystal nanowires was controlled by the electron beam density. The growth

  15. Thermodynamic modelling of the Ag-Cu-Ti ternary system Olivier Dezellus1

    E-print Network

    Boyer, Edmond

    : Calphad; braze alloys; phase diagram; Ag-Cu-Ti 1 Introduction The Ag-Cu binary consists in a simple-Ti binary and the existence of a miscibility gap in the liquid phase. For applications, the knowledge FCC Figure 1: Calculated Ag-Ti phase diagram, using thermodynamic assessment by Arroyave [4

  16. Preparation of Ni-based multilayered tape and its potential application for the coating of YBa 2Cu 3O 7- ?

    NASA Astrophysics Data System (ADS)

    Guo, Hansheng; Zhou, M. L.; Liu, D. M.; Zuo, T. Y.; Zhou, Y. L.; Wang, R. P.; Pan, S. H.; Wang, H. H.

    2000-07-01

    Pd and Ag were successively vacuum-deposited on textured Ni-alloys to form multilayered tapes, Ni-alloy/Pd (2000 Å)/Ag. Pole-figure analysis and orientation density function (ODF) calculations show that, with the aid of a Pd buffer layer, Ag can grow epitaxially to inherit the cubic texture, {100}<001>, of the Ni-alloy substrates. However, Ag deposited directly on the Ni substrate forms a polycrystalline film without preferred orientation. This fact suggests that Pd, which is soluble in both Ni and Ag, is an indispensable medium for the epitaxial growth of Ag on Ni. Instead, Ag is insoluble in Ni; it is the site-equivalent for Ag depositing at the initial stage; thus, no epitaxy can be expected. The application of multilayered tapes for the coating of YBa 2Cu 3O 7- ? (YBCO) superconductor was examined by the use of pulsed laser deposition (PLD). It was found that the thickness of the Ag layer and the substrate temperature during PLD are the main factors affecting the properties of YBCO films.

  17. High thermally stable Ni /Ag(Al) alloy contacts on p-GaN

    NASA Astrophysics Data System (ADS)

    Chou, C. H.; Lin, C. L.; Chuang, Y. C.; Bor, H. Y.; Liu, C. Y.

    2007-01-01

    Ag agglomeration was found to occur at Ni /Ag to p-GaN contacts after annealing at 500°C. This Ag agglomeration led to the poor thermal stability showed by the Ni /Ag contacts in relation to the reflectivity and electrical properties. However, after alloying with 10at.% Al by e-gun deposition, the Ni /Ag(Al) p-GaN contacts were found to effectively retard Ag agglomeration thereby greatly enhancing the thermal stability. Based on the x-ray photoelectron spectroscopy analysis, the authors believe that the key for the retardation of Ag agglomeration was the formation of ternary Al-Ni-O layer at p-GaN interface.

  18. Yb(Cu,T) 5 and Yb(Cu,T) 4.5 solid solutions (T = Ag, Au, Pd)

    Microsoft Academic Search

    M. Giovannini; R. Pasero; S. De Negri; A. Saccone

    2008-01-01

    The binary Yb–Cu phase diagram was re-investigated in the Cu-rich part. Starting from this region, solid solutions formed by substitution of Cu by Ag, Au, and Pd have been investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). A competition in compound formation between Yb(Cu,T)5 (T=Ag, Au, Pd), cubic AuBe5-type and its monoclinic superstructure

  19. Electrocatalytic oxidation of methanol on Ni and NiCu alloy modified glassy carbon electrode

    Microsoft Academic Search

    I. Danaee; M. Jafarian; F. Forouzandeh; F. Gobal; M. G. Mahjani

    2008-01-01

    Nickel and nickel–copper alloy modified glassy carbon electrodes (GC\\/Ni and GC\\/NiCu) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of ?\\/? crystallographic forms of the nickel oxyhydroxide

  20. Spin pumping and inverse Rashba-Edelstein effect in NiFe/Ag/Bi and NiFe/Ag/Sb

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Jungfleisch, Matthias B.; Jiang, Wanjun; Pearson, John E.; Hoffmann, Axel

    2015-05-01

    The Rashba effect is an interaction between the spin and the momentum of electrons induced by the spin-orbit coupling in surface or interface states. We measured the inverse Rashba-Edelstein effect via spin pumping in Ag/Bi and Ag/Sb interfaces. The spin current is injected from the ferromagnetic resonance of a NiFe layer towards the Rashba interfaces, where it is further converted into a charge current. Using spin pumping theory, we quantify the conversion parameter of spin to charge current to be 0.11 ± 0.02 nm for Ag/Bi and a factor of ten smaller for Ag/Sb. The relative strength of the effect is in agreement with spectroscopic measurements and first principles calculations. We also vary the interlayer materials to study the voltage output in relation to the change of the effective spin mixing conductance. The spin pumping experiment offers a straight-forward approach of using spin current as an efficient probe for detecting interface Rashba splitting.

  1. L'EFFET PHOTODILECTRIQUE OBTENU AVEC ZnS(Cu, Co) ET ZnS(Cu. Ni) Par JEAN ROUX,

    E-print Network

    Paris-Sud XI, Université de

    813 L'EFFET PHOTODIÉLECTRIQUE OBTENU AVEC ZnS(Cu, Co) ET ZnS(Cu. Ni) Par JEAN ROUX, Laboratoire de are concerned with ZnS(Cu), ZnS(Cu, Ni), and ZnS(Cu, Co). At a given frequency, the measurements of the real is much more important with Ni. Further experiments with ZnS(Cu, Co) show that the main phenomenon

  2. Interlayer segregation of Cu atoms in Ta/NiFe/Cu/NiFe/FeMn/Ta spin-valve multilayers and its influence on magnetic properties

    NASA Astrophysics Data System (ADS)

    Yu, G. H.; Li, M. H.; Zhu, F. W.; Li, Q. K.; Zhang, Y.; Chai, C. L.; Jiang, H. W.; Lai, W. Y.

    2002-03-01

    Experimental results show that the exchange coupling field (Hex) of NiFe/FeMn for Ta/NiFe/FeMn/Ta multilayers is higher than that for spin-valve multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta. In order to find out the reason, the composition and chemical states at the surface of Ta(12 nm)/NiFe(7 nm), Ta(12 nm)/NiFe(7 nm)/Cu(4 nm), and Ta(12 nm)/NiFe(7 nm)/Cu(3 nm)/NiFe(5 nm) were studied using x-ray photoelectron spectroscopy. The results show that no elements from lower layers float out or segregate to the surface in the first and second samples. However, Cu atoms segregate to the surface of Ta(12 nm)/NiFe(7 nm)/Cu(3 nm)/NiFe(5 nm) multilayers, i.e., Cu atoms segregate to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. We believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors which causes the exchange coupling field (Hex) of Ta/NiFe/Cu/NiFe/FeMn/Ta to be weaker than that of Ta/NiFe/FeMn/Ta.

  3. A novel multifunctional NiTi/Ag hierarchical composite

    NASA Astrophysics Data System (ADS)

    Hao, Shijie; Cui, Lishan; Jiang, Jiang; Guo, Fangmin; Xiao, Xianghui; Jiang, Daqiang; Yu, Cun; Chen, Zonghai; Zhou, Hua; Wang, Yandong; Liu, Yuzi; Brown, Dennis E.; Ren, Yang

    2014-06-01

    Creating multifunctional materials is an eternal goal of mankind. As the properties of monolithic materials are necessary limited, one route to extending them is to create a composite by combining contrasting materials. The potential of this approach is neatly illustrated by the formation of nature materials where contrasting components are combined in sophisticated hierarchical designs. In this study, inspired by the hierarchical structure of the tendon, we fabricated a novel composite by subtly combining two contrasting components: NiTi shape-memory alloy and Ag. The composite exhibits simultaneously exceptional mechanical properties of high strength, good superelasticity and high mechanical damping, and remarkable functional properties of high electric conductivity, high visibility under fluoroscopy and excellent thermal-driven ability. All of these result from the effective-synergy between the NiTi and Ag components, and place the composite in a unique position in the properties chart of all known structural-functional materials providing new opportunities for innovative electrical, mechanical and biomedical applications. Furthermore, this work may open new avenues for designing and fabricating advanced multifunctional materials by subtly combining contrasting multi-components.

  4. A novel multifunctional NiTi/Ag hierarchical composite

    PubMed Central

    Hao, Shijie; Cui, Lishan; Jiang, Jiang; Guo, Fangmin; Xiao, Xianghui; Jiang, Daqiang; Yu, Cun; Chen, Zonghai; Zhou, Hua; Wang, Yandong; Liu, YuZi; Brown, Dennis E.; Ren, Yang

    2014-01-01

    Creating multifunctional materials is an eternal goal of mankind. As the properties of monolithic materials are necessary limited, one route to extending them is to create a composite by combining contrasting materials. The potential of this approach is neatly illustrated by the formation of nature materials where contrasting components are combined in sophisticated hierarchical designs. In this study, inspired by the hierarchical structure of the tendon, we fabricated a novel composite by subtly combining two contrasting components: NiTi shape-memory alloy and Ag. The composite exhibits simultaneously exceptional mechanical properties of high strength, good superelasticity and high mechanical damping, and remarkable functional properties of high electric conductivity, high visibility under fluoroscopy and excellent thermal-driven ability. All of these result from the effective-synergy between the NiTi and Ag components, and place the composite in a unique position in the properties chart of all known structural-functional materials providing new opportunities for innovative electrical, mechanical and biomedical applications. Furthermore, this work may open new avenues for designing and fabricating advanced multifunctional materials by subtly combining contrasting multi-components. PMID:24919945

  5. 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.

  6. Structural and magnetic properties of Cu Ni Cr spinel oxides

    NASA Astrophysics Data System (ADS)

    Tovar, M.; Torabi, R.; Welker, C.; Fleischer, F.

    2006-11-01

    The compounds CuCr 2O 4 and NiCr 2O 4 crystallize at room temperature in a tetragonal distorted spinel structure, s.g. I4 1/amd, with axes ratio c/ a<1 and >1, respectively. The distortion is caused by the Jahn-Teller ions Cu 2+ and Ni 2+ which flatten or elongate their surrounding oxygen tetrahedron. CuCr 2O 4 and NiCr 2O 4 form a complete solid solution series Cu 1-xNi xCr 2O 4 where for 0.825< x<0.875 members with orthorhombic symmetry were found. Using neutron powder diffraction and thermal analysis methods several members of the solid solution series were investigated. On cooling, all samples showed a temperature-dependent crystallographic phase transition from cubic to tetragonal symmetry between 865 K (CuCr 2O 4) and 310 K (NiCr 2O 4). The phase Cu 0.15Ni 0.85Cr 2O 4 undergoes a second crystallographic transition to orthorhombic symmetry, space group Fddd, at T=300 K. The neutron diffraction experiments as well as SQUID measurements reveal magnetic ordering of the ions between 150 and 50 K which partially occurs as a two-step mechanism.

  7. Morphology and electrochemical behavior of Ag–Cu nanoparticle-doped amalgams

    Microsoft Academic Search

    Kwok-Hung Chung; Li-Yin Hsiao; Yu-Sheng Lin; Jenq-Gong Duh

    2008-01-01

    The aim of this study was to introduce Ag–Cu phase nanopowder as an additive to improve the corrosion behavior of dental amalgams. A novel Ag–Cu nanopowder was synthesized by the precipitation method. An amalgam alloy powder (World-Cap®) was added and mixed with 5wt.% and 10wt.% of Ag–Cu nanopowders, respectively, to form experimental amalgam alloy powders. The original alloy powder was

  8. Characterization and device performance of (AgCu)(InGa)Se2 absorber layers

    SciTech Connect

    Hanket, Gregory; Boyle, Jonathan H.; Shafarman, William N.

    2009-06-08

    The study of (AgCu)(InGa)Se2 absorber layers is of interest in that Ag-chalcopyrites exhibit both wider bandgaps and lower melting points than their Cu counterparts. (AgCu)(InGa)Se2 absorber layers were deposited over the composition range 0 < Ag/(Ag+Cu) < 1 and 0.3 < Ga/(In+Ga) < 1.0 using a variety of elemental co-evaporation processes. Films were found to be singlephase over the entire composition range, in contrast to prior studies. Devices with Ga content 0.3 < Ga/(In+Ga) <0.5 tolerated Ag incorporation up to Ag/(Ag+Cu) = 0.5 without appreciable performance loss. Ag-containing films with Ga/(In+Ga) = 0.8 showed improved device characteristics over Cu-only control samples, in particular a 30-40% increase in short-circuit current. An absorber layer with composition Ag/(Ag+Cu) = 0.75 and Ga/(In+Ga) = 0.8 yielded a device with VOC = 890 mV, JSC = 20.5mA/cm2, fill factor = 71.3%, and ? = 13.0%.

  9. 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. [Department of Applied Physics, Birla Institute of Technology Mesra, Ranchi, Jharkhand 835215 (India)

    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.

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

    SciTech Connect

    Devletian, J.H.; Gao, Y.P.; Wood, W.E. [Oregon Graduate Inst. of Science and Technology, Portland, OR (United States)

    1996-12-31

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

  11. Surface composition of ternary cu-ag-au alloys: part i. experimental results

    Microsoft Academic Search

    M. A. Hoffmann; P. Wynblatt

    1991-01-01

    The enthalpies and entropies of segregation for silver and gold, along with equilibrium surface composition measurements on\\u000a three Cu-Ag-Au ternary specimens, are reported and discussed. The experimentally studied compositions were Cu-0.3 at. pct\\u000a Ag-2.1 at. pct Au, Cu-0.55 at. pct Ag-6.5 at. pct Au, and Cu-1.09 at. pct Ag-6.9 at. pct Au. The experimental enthalpies of\\u000a segregation, entropies of segregation,

  12. Microstructure and Mechanical Properties of Cu-Ag-Zr Alloy

    NASA Astrophysics Data System (ADS)

    Krishna, S. Chenna; Tharian, K. Thomas; Pant, Bhanu; Kottada, Ravi S.

    2013-12-01

    The Cu-3Ag-0.5Zr alloy was produced by vacuum induction melting and subsequently processed through hot forging and rolling. Detailed microstructural characterization of solution-treated (ST) specimen shows three types of phases: Cu matrix, zirconium-rich phase, and Cu-Ag-Zr intermetallic phase. Transmission electron microscopy studies together with energy-dispersive x-ray spectroscopy analysis established the presence of Zr-rich large particles in the ST condition. Aging at 450 °C for 4.5 h after solution treatment resulted in the formation of uniformly distributed fine spherical silver precipitates with an average diameter of 9.0 ± 2.0 nm. Consequently, room temperature yield strength (YS) and ultimate tensile strength (UTS) of the aged specimen increased by 110% and 15%, respectively, compared to those of 120 and 290 MPa of the ST specimen. At elevated temperature, the YS decreased to 146 and 100 MPa at 540 and 640 °C, respectively, for the aged sample. On the contrary, the YS increased to 140 MPa at 540 °C, and thereafter a decrease was observed with a value of 105 MPa at 640 °C for the ST sample. This decrease in YS at higher temperatures is attributed to coarsening of precipitates and dissolution of the precipitates, whereas an increase in YS is attributed to in-situ aging of the samples.

  13. Annealing effect of ultrathin Ag films on Ni/Pt(111)

    SciTech Connect

    Su, C.W.; Yo, H.Y.; Chen, Y.J.; Shern, C.S. [Department of Physics, National Taiwan Normal University, 88, Section 4, Ting-Chou Road, Taipei 116, Taiwan (China) and Department of Applied Physics, National Chiayi University, 300, University Road, Chiayi 600, Taiwan (China); Department of Physics, National Taiwan Normal University, 88, Section 4, Ting-Chou Road, Taipei 116, Taiwan (China)

    2005-06-15

    The epitaxial growth and alloy formation of Ag-capped layer on Ni/Pt(111) surface were investigated using Auger electron spectroscopy, ultraviolet photoelectron spectroscopy, and low-energy electron diffraction. The growth of Ag on one ML Ni/Pt(111) transforms from layer-by-layer mode into three-dimensional island mode after the growth of one atomic monolayer of Ag. The starting temperature for the alloy formation of Ni-Pt is dependent of the thickness of Ni films. The interface compositions after the high-temperature annealing were studied with the depth-profile analysis of Ar ion sputtering.

  14. Study of oxygen reduction mechanism on Ag modified1 Sm1.8Ce0.2CuO4 cathode for solid oxide fuel cell2

    E-print Network

    Paris-Sud XI, Université de

    SOFCs [1], [2], [3] and [4]. Layered perovskite34 oxides with K2NiF4-type structure were extensively], [14] and [15]. Among these37 oxides, Ln2CuO4 materials were found to exhibit excellent performance conductivity and relatively49 low cost. Numerous works have been performed on the Ag-added perovskite cathodes

  15. Interlayer segregation of Cu atoms in Ta\\/NiFe\\/Cu\\/NiFe\\/FeMn\\/Ta spin-valve multilayers and its influence on magnetic properties

    Microsoft Academic Search

    G. H. Yu; M. H. Li; F. W. Zhu; Q. K. Li; Y. Zhang; C. L. Chai; H. W. Jiang; W. Y. Lai

    2002-01-01

    Experimental results show that the exchange coupling field (Hex) of NiFe\\/FeMn for Ta\\/NiFe\\/FeMn\\/Ta multilayers is higher than that for spin-valve multilayers Ta\\/NiFe\\/Cu\\/NiFe\\/FeMn\\/Ta. In order to find out the reason, the composition and chemical states at the surface of Ta(12 nm)\\/NiFe(7 nm), Ta(12 nm)\\/NiFe(7 nm)\\/Cu(4 nm), and Ta(12 nm)\\/NiFe(7 nm)\\/Cu(3 nm)\\/NiFe(5 nm) were studied using x-ray photoelectron spectroscopy. The results show

  16. Critical thermodynamic evaluation and optimization of the Ag–Zr, Cu–Zr and Ag–Cu–Zr systems and its applications to amorphous Cu–Zr–Ag alloys

    Microsoft Academic Search

    Dae Hoon Kang; In-Ho Jung

    2010-01-01

    A complete literature review, critical evaluation and thermodynamic modeling of the phase diagrams and thermodynamic properties of all solid and liquid phases in the Ag–Zr, Cu–Zr and Ag–Cu–Zr systems at 1 bar total pressure are presented. Optimized model equations for the thermodynamic properties of all phases were obtained which reproduce all available thermodynamic and phase equilibrium data within experimental error limits

  17. Optical properties of Ni and Cu nanowire arrays and Ni/Cu superlattice nanowire arrays.

    PubMed

    Zhang, Yaya; Xu, Wen; Xu, Shaohui; Fei, Guangtao; Xiao, Yiming; Hu, Jiaguang

    2012-01-01

    : In this study, Ni and Cu nanowire arrays and Ni/Cu superlattice nanowire arrays are fabricated using standard techniques such as electrochemical deposition of metals into porous anodic alumina oxide templates having pore diameters of about 50 nm. We perform optical measurements on these nanowire array structures. Optical reflectance (OR) of the as-prepared samples is recorded using an imaging spectrometer in the wavelength range from 400 to 2,000 nm (i.e., from visible to near-infrared bandwidth). The measurements are carried out at temperatures set to be 4.2, 70, 150, and 200 K and at room temperature. We find that the intensity of the OR spectrum for nanowire arrays depends strongly on the temperature. The strongest OR can be observed at about T?=?200 K for all samples in visible regime. The OR spectra for these samples show different features in the visible and near-infrared bandwidths. We discuss the physical mechanisms responsible for these interesting experimental findings. This study is relevant to the application of metal nanowire arrays as optical and optoelectronic devices. PMID:23067299

  18. Modified Ni-Cu catalysts for ethanol steam reforming

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    Three Ni-Cu catalysts, having different Cu content, supported on ?-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 (N2 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.

  19. Diffusion bonding of commercially pure Ni using Cu interlayer

    SciTech Connect

    Rahman, A.H.M.E., E-mail: a.rahman@my.und.edu; Cavalli, M.N.

    2012-07-15

    The concentration dependence of diffusivity in a multi-component diffusion system makes it complicated to predict the concentration profiles of diffusing species. This so called chemical diffusivity can be expressed as a function of thermodynamic and kinetic data. DICTRA software can calculate the concentration profiles using appropriate mobility and thermodynamic data. It can also optimize the diffusivity data using experimental diffusivity data. Then the optimized diffusivity data is stored as mobility data which is a linear function of temperature. In this work, diffusion bonding of commercially pure Ni using Cu interlayers is reported. The mobility parameters of Ni-Cu alloy binary systems were optimized using DICTRA/Thermocalc software from the available self-, tracer and chemical diffusion coefficients. The optimized mobility parameters were used to simulate concentration profiles of Ni-Cu diffusion joints using DICTRA/Thermocalc software. The calculated and experimental concentration profiles agreed well at 1100 Degree-Sign C. Agreement between the simulated and experimental profiles was less good at 1050 Degree-Sign C due to the grain boundary contribution to the overall diffusion. - Highlights: Black-Right-Pointing-Pointer The concentration profiles of Cu in Ni-Cu diffusion joints are modeled. Black-Right-Pointing-Pointer Interdiffusion coefficients in Ni-Cu system are optimized. Black-Right-Pointing-Pointer Optimized interdiffusion coefficients are expressed as mobility parameters. Black-Right-Pointing-Pointer Simulated profiles are comparable with experimental profiles.

  20. Modified Ni-Cu catalysts for ethanol steam reforming

    SciTech Connect

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania)] [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania); Katona, G.; Muresan, L. [Univ. Babes Bolyai, Fac. Chem. and Chem. Eng.,11 Arany Janos, 400028, Cluj-Napoca (Romania)] [Univ. Babes Bolyai, Fac. Chem. and Chem. Eng.,11 Arany Janos, 400028, Cluj-Napoca (Romania); Lazar, M. D., E-mail: diana.lazar@itim-cj.ro [65-103 Donath Street (Romania)

    2013-11-13

    Three Ni-Cu catalysts, having different Cu content, supported on ?-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.

  1. Magnetization behaviour in ultrathin Co/Cu/Ni/Cu(001) trilayers.

    PubMed

    Zasada, I

    2011-01-01

    The magnetization of ultrathin multilayer systems depends in a very sensitive way on their composition. We consider the temperature dependence of magnetization and its orientation in three types of trilayers: 2ML Co/2ML Cu/4ML Ni/Cu(001), 1ML Co/2ML Cu/4ML Ni/Cu(001) and 1ML Co/2ML Cu/3ML Ni/Cu(001). The composition of each system leads to different interdependence of ordering temperatures characterizing the ferromagnetic films. It is shown that in all cases the sublayer magnetizations change gradually their directions as a function of temperature. The use of Néel sublattices concept in Valenta approach allows us to present all dependences in a layer resolved mode which leads to the conclusion that the spin reorientation process runs through non collinear magnetic superstructures. PMID:21446429

  2. Thermal and Microstructural Analysis of the Y–Ba–Cu–O\\/Ag Equilibrium Around the Critical Composition YBa2Cu3Ox\\/Ag 35 mass%

    Microsoft Academic Search

    G. A. Costa; P. Mele

    2001-01-01

    We studied the Y–Ba–Cu–O\\/Ag equilibrium diagram in oxygen atmosphere around the composition YBa2Cu3Ox\\/Ag35 mass%. We found a high thermal effect: the peritectic decomposition temperature of Y-123 phase is lowered from 1040\\u000a to 940C. We demonstrate here that the nature of the phenomenon is not chemical. We explained it as the result of a mechanical\\u000a segregation of Y-123 decomposition products from

  3. Synthesis of 3D Printable Cu-Ag Core-Shell Materials: Kinetics of CuO Film Removal

    NASA Astrophysics Data System (ADS)

    Hong, Seongik; Kim, Namsoo

    2015-03-01

    In this research, Cu-Ag core-shell particles were synthesized as a functional and 3D printable material. Using the solid-liquid method, Cu-Ag core-shell particles were simply synthesized, and different particle sizes of 100 nm and 2 ?m were used to confirm the size effect in the synthesis and reaction control of the Cu-Ag core-shell particles. In addition, highly viscous Cu-Ag core-shell particle paste was also prepared, and its electrical conductivity was measured. As a result, the reaction rate in the case of the 2 ?m Cu particles was controlled by film diffusion, whereas for the 100 nm Cu particles, the reaction rate was controlled by CuO film produced before reacting with Ag ions in solution, and limited by chemical reaction control. Through the solid-liquid method, dendrite-shaped Cu-Ag core-shell particles were formed. Also, the electrical conductivity increased with increasing sintering temperature and core-shell particle concentration.

  4. Fabrication of Cu-Ag core-shell bimetallic superfine powders by eco-friendly reagents and structures characterization

    SciTech Connect

    Zhao Jun [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Yi Fu Building 4th Floor, Wuhan 430070 (China); Zhang Dongming, E-mail: zhangdongming71@hotmail.com [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Yi Fu Building 4th Floor, Wuhan 430070 (China); Zhao Jie [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Yi Fu Building 4th Floor, Wuhan 430070 (China)

    2011-09-15

    Superfine bimetallic Cu-Ag core-shell powders were synthesized by reduction of copper sulfate pentahydrate and silver nitrate with eco-friendly ascorbic acid as a reducing agent and cyclodextrins as a protective agent in an aqueous system. The influence of Ag/Cu ratio on coatings was investigated. Ag was homogeneously distributed on the surface of Cu particles at a mole ratio of Ag/Cu=1. FE-SEM showed an uniformity of Ag coatings on Cu particles. Antioxidation of Cu particles was improved by increasing Ag/Cu ratio. TEM-EDX and UV-vis spectra also revealed that Cu cores were covered by Ag nanoshells on the whole. The surface composition analysis by XPS indicated that only small parts of Cu atoms in the surface were oxidized. It was noted that the hindrance of cyclodextrins chemisorbed on particles plays an important role in forming high quality and good dispersity Cu-Ag (Cu-Ag) core-shell powders. - Graphical abstract: Mechanism of fabricating Cu-Ag particles with good dispersibility using {beta}-CDs as a protective agent was studied because of its special structure. Highlights: > Green supramolecular {beta}-CD used as a protective agent and ascorbic acid(Vc) as a reducing agent to fabricate Cu-Ag powders. > Particles are monodisperse and the diameter is close to nanoscale(100-150 nm). > Resistance of Cu particles to oxidation was higher. > Formation mechanism explained.

  5. Determination of Anand parameters for SnAgCuCe solder

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Xue, Songbai; Gao, Lili; Zeng, Guang; Sheng, Zhong; Chen, Yan; Yu, Shenglin

    2009-10-01

    A unified viscoplastic constitutive model, Anand equations, was used to represent the inelastic deformation behavior for Sn3.8Ag0.7Cu/Sn3.8Ag0.7 Cu0.03Ce solders in surface mount technology. The Anand parameters of the constitutive equations for the SnAgCu and SnAgCuCe solders were determined from separated constitutive relations and experimental results. Non-linear least-squares fitting was selected to determine the model constants. Comparisons were then made with experimental measurements of the stress-inelastic strain curves: excellent agreement was found. The model accurately predicted the overall trend of steady-state stress-strain behavior of SnAgCu and SnAgCuCe solders for the temperature ranges from -55 to 125 °C and for the strain rate range from 1% s-1 to 0.01% s-1. It is concluded that the Anand model can be applied to represent the inelastic deformation behavior of solders at high homologous temperatures and can be recommended for finite element simulation of the stress-strain response of lead-free soldered joints. Based on the Anand model, the investigations of thermo-mechanical behavior of SnAgCu and SnAgCuCe soldered joints in fine pitch quad flat package by the finite element code have been done under thermal cyclic loading, and it is found that the reliability of the SnAgCuCe soldered joints is better than that of the SnAgCu soldered joints.

  6. Effect of Ni content on the corrosion behavior of Cu–Ni alloys in neutral chloride solutions

    Microsoft Academic Search

    Waheed A. Badawy; Khaled M. Ismail; Ahlam M. Fathi

    2005-01-01

    The effect of systematic increase of Ni content on the electrochemical behavior of the Cu–Ni alloys in neutral chloride solutions was investigated. The pitting corrosion behavior of Cu–Ni alloys with different Ni contents, namely, 5, 10, 30 and 65mass% Ni, in a stagnant 0.6moldm?3 NaCl solution of pH 7.0 was studied. The effect of chloride ion concentration on the electrochemical

  7. Strain-induced magnetocrystalline anisotropy in Ni on Cu(001)

    SciTech Connect

    Wu, R.; Chen, L. [Department of Physics Astronomy, California State University, Northridge, California 91330-8268 (United States)] [Department of Physics Astronomy, California State University, Northridge, California 91330-8268 (United States); Freeman, A.J. [Department of Physics Astronomy, Northwestern University, Evanston, Illinois 60208-3112 (United States)] [Department of Physics Astronomy, Northwestern University, Evanston, Illinois 60208-3112 (United States)

    1997-04-01

    The origin of the observed perpendicular magnetic anisotropy (PMA) in Ni/Cu(001) for thick Ni layers is investigated using the {ital ab initio} full potential linearized augmented plane wave method. With the aid of the state tracking and torque approaches, very stable results are obtained for the magnetocrystalline anisotropy (MCA) energies for both the Ni/Cu(001) overlayer systems and the distorted bulk fct Ni. We find that the PMA is due mainly to the strain induced bulk contribution rather than to interfacial hybridization. The calculated value of the bulk MCA energy, 65 {mu}eV/atom, is very close to recent experimental data extrapolated to zero temperature, 70 {mu}eV/atom. {copyright} {ital 1997 American Institute of Physics.}

  8. Spin trimers in Ca3Cu2Ni(PO4)4

    NASA Astrophysics Data System (ADS)

    Ghosh, M.; Ghoshray, K.

    2012-07-01

    The nature of spin trimer and 3d spin dynamics in Ca3Cu2Ni(PO4)4 is studied using 31P NMR measurements. The data are obtained by replacing one of the Cu ions by a Ni ion in the one dimensional spin trimer compound Ca3Cu3(PO4)4. The NMR spectrum suggests the presence of two types of magnetically inequivalent phosphorous atoms, as in the parent compound. This reveals the presence of only one type of trimer, Cu2-Ni-Cu2, rather than of three types, Cu2-Cu1-Cu2, Cu2-Cu1-Ni and Ni-Cu1-Ni, as indicated by neutron scattering. Hence, the ground state of Ca3Cu2Ni(PO4)4 appears to be a quintet. These results also explain the magnetic susceptibility behavior, which indicates no reduction in the net spin of the trimer in Ca3Cu2Ni(PO4)4, as expected for JNi-Cu = -0.85 meV compared to the value JCu-Cu = -4.74 meV derived from neutron scattering. The spin lattice relaxation rate suggests that the three magnon mediated scattering process dominant in Ca3Cu3(PO4)4 is reduced in Ca3Cu2Ni(PO4)4.

  9. Cellular Energy Allocation to Assess the Impact of Nanomaterials on Soil Invertebrates (Enchytraeids): The Effect of Cu and Ag

    PubMed Central

    Gomes, Susana I. L.; Scott-Fordsmand, Janeck J.; Amorim, Mónica J. B.

    2015-01-01

    The effects of several copper (Cu) and silver (Ag) nanomaterials were assessed using the cellular energy allocation (CEA), a methodology used to evaluate the energetic status and which relates with organisms’ overall condition and response to toxic stress. Enchytraeus crypticus (Oligochatea), was exposed to the reproduction effect concentrations EC20/50 of several Cu and Ag materials (CuNO3, Cu-Field, Cu-Nwires and Cu-NPs; AgNO3, Ag NM300K, Ag-NPs Non-coated and Ag-NPs PVP-coated) for 7 days (0-3-7d). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (Ec) integrated to obtain the CEA. Results showed that these parameters allowed a clear discrimination between Cu and Ag, but less clearly within each of the various materials. For Cu there was an increase in Ec and protein budget, while for Ag a decrease was observed. The results corroborate known mechanisms, e.g., with Cu causing an increase in metabolic rate whereas Ag induces mitochondrial damage. The various Cu forms seem to activate different mechanisms with size and shape (e.g., Cu-NPs versus Cu-Nwires), causing clearly different effects. For Ag, results are in line with a slower oxidation rate of Ag-NMs in comparison with Ag-salt and hence delayed effects. PMID:26086707

  10. Cellular Energy Allocation to Assess the Impact of Nanomaterials on Soil Invertebrates (Enchytraeids): The Effect of Cu and Ag.

    PubMed

    Gomes, Susana I L; Scott-Fordsmand, Janeck J; Amorim, Mónica J B

    2015-01-01

    The effects of several copper (Cu) and silver (Ag) nanomaterials were assessed using the cellular energy allocation (CEA), a methodology used to evaluate the energetic status and which relates with organisms' overall condition and response to toxic stress. Enchytraeus crypticus (Oligochatea), was exposed to the reproduction effect concentrations EC20/50 of several Cu and Ag materials (CuNO3, Cu-Field, Cu-Nwires and Cu-NPs; AgNO3, Ag NM300K, Ag-NPs Non-coated and Ag-NPs PVP-coated) for 7 days (0-3-7d). The parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption (Ec) integrated to obtain the CEA. Results showed that these parameters allowed a clear discrimination between Cu and Ag, but less clearly within each of the various materials. For Cu there was an increase in Ec and protein budget, while for Ag a decrease was observed. The results corroborate known mechanisms, e.g., with Cu causing an increase in metabolic rate whereas Ag induces mitochondrial damage. The various Cu forms seem to activate different mechanisms with size and shape (e.g., Cu-NPs versus Cu-Nwires), causing clearly different effects. For Ag, results are in line with a slower oxidation rate of Ag-NMs in comparison with Ag-salt and hence delayed effects. PMID:26086707

  11. Strain-induced magnetization reorientation in epitaxial Cu/Ni/Cu rings

    E-print Network

    Corredor, E. C.

    The role of the strain state in epitaxial (001)-oriented Cu/Ni(14 nm)/Cu rings is investigated using a combination of magnetic force microscopy and finite-element calculations. Rings with an external diameter of 3 and 2 ...

  12. Magnetic Properties of Cd Substituted Ni-Cu Ferrites

    NASA Astrophysics Data System (ADS)

    Belavi, P. B.; Chavan, G. N.; Bammannavar, B. K.; Naik, L. R.; Kotnala, R. K.

    2011-07-01

    Cadmium substituted Ni-Cu Ferrites with the general formula Ni0.95-xCdxCu0.05Fe2O4 (x = 0.1, 0.2 and 0.3) were prepared by the standard double sintering ceramic method. The existences of single phase formation with crystalline size of 25-38 nm were confirmed from XRD measurements. The magnetic properties such as saturation magnetization (Ms) and Magnetic moment (?B) were studied by VSM analysis. The existence of multidomain (MD) particles in the samples was revealed from the small values of Mr/Ms.

  13. Assessment of the aluminum-rich corner of the Al–Cu–Mg–(Ag) phase diagram

    Microsoft Academic Search

    B. M. Gable; A. W. Zhu; G. J. Shiflet; E STARKEJR

    2008-01-01

    The thermodynamic expressions for the phases found in the aluminum-rich corner of the Al–Cu–Mg–(Ag) system were evaluated and refined to develop a self-consistent database. Microstructural characterization and thermal analysis aided in revising published thermodynamic data for the Al–Cu–Mg and Al–Cu–Mg–Ag systems. To represent the presence of silver an additional interaction energy term was formulated for the S phase, which was

  14. New bulk glassy alloys in Cu-Zr-Ag ternary system prepared by casting and milling

    Microsoft Academic Search

    D. Janovszky; K. Tomolya; M. Sveda; J. Solyom; A. Roosz

    2009-01-01

    The thermal stability, crystallization behaviour and glass forming ability of Cu-Zr-Ag system have been investigated on the basis of a ternary phase diagram. We altered the concentration of the alloys from the Cu58Zr42 to the concentration of the deep eutectic point of the Cu-Zr-Ag ternary system and we calculated the glass forming ability parameters. This paper summerises the results of

  15. Effects of grain cluster size on coercivity and giant magnetoresistance of NiFe/Cu/CoFe/Cu/NiFe pseudo spin valves

    NASA Astrophysics Data System (ADS)

    Bae, Seongtae; Li, Jianguang; Judy, Jack H.; Zurn, Shayne

    2000-11-01

    The effects of grain cluster size on the coercivity (Hc) and giant magnetoresistance in NiFe/Cu/CoFe/Cu/NiFe pseudo spin valves for magnetic random access memory devices has been investigated as a function of the Ar sputtering gas pressure which affects the interfacial roughness and magnetic coercivity differences. It is found that the grain cluster size induced by the differences in the kinetic energy of the sputtered adatoms at different gas pressure plays a crucial role in determining the Hc of NiFe/CoFe bilayers and magnetic interlayer coupling in Si/NiFe/Cu/CoFe/Cu/NiFe pseudo spin valves.

  16. Effect of Ag addition on the structures of intermetallic compounds and the adhesion strength of the Sn–9Zn– xAg\\/Cu interface

    Microsoft Academic Search

    Tao-Chih Chang; Moo-Chin Wang; Min-Hsiung Hon

    2003-01-01

    The effect of Ag addition on the structures of the intermetallic compounds (IMCs) and the adhesion strength of the Sn–9Zn–xAg solder alloy\\/Cu interface has been investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, transmission electron microscopy and electron diffraction. The XRD patterns show that the ?-Cu6Sn5, ??-Cu6Sn5 and Cu5Zn8 are found at the Sn–9Zn–xAg\\/Cu interface. The Ag3Sn formed

  17. Size effect model on kinetics of interfacial reaction between Sn-xAg-yCu solders and Cu substrate

    NASA Astrophysics Data System (ADS)

    Huang, M. L.; Yang, F.

    2014-11-01

    The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu6Sn5 grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu6Sn5 obeys a t1/3 law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed.

  18. Stress corrosion of Cu Zn and Cu Zn Ni alloys: The role of dealloying

    Microsoft Academic Search

    Arvind Parthasarathi; Ned W. Polan

    1982-01-01

    Evidence is presented to demonstrate the occurrence of strain induced dealloying during stress corrosion of Cu-Zn alloys with\\u000a 15-30 pct Zn and a Cu-28 pct Zn-12 pct Ni alloy. The binary Cu-Zn alloys cracked intergranularly in the ammoniacal solutions\\u000a used, whereas cracking was transgranular in the ternary alloy. Dealloying was thus found to be a common feature of both modes

  19. Tribological performance of Cu?Ni alloy nanoparticles synthesized using a pulsed-wire evaporation method

    Microsoft Academic Search

    Jeongseok Oh; Changkyu Rhee

    2008-01-01

    Cu?Ni alloy nanoparticles were produced using a pulsed-wire evaporation method in Ar gas. The synthesized Cu?Ni alloy nanoparticles\\u000a had an average size of 150 nm, were spherical in shape and agglomerated. We investigated the tribological propeties of dispersion-stabilized\\u000a Cu?Ni alloy nanoparticles when used as a solid lubricant in oil at ambient temperature. The sedimentation behavior of Cu?Ni\\u000a alloy nanoparticles in

  20. Structure and solid solution properties of Cu-Ag nanoalloys.

    PubMed

    Atanasov, Ivailo; Ferrando, Riccardo; Johnston, Roy L

    2014-07-01

    The nanoparticle phase diagram of an immiscible system is studied at the atomic level. Cu-Ag clusters with sizes 1000 and 2000 atoms, resulting from a global minimum search and belonging to icosahedral and crystalline structural motifs, are considered. We present the statistical analysis of the effect of temperature on the solubility of the two elements based on Metropolis Monte Carlo importance sampling. Our results suggest that the relevance of bulk phase diagrams to nanoparticles is limited to cases where the internal stress distribution does not deviate very much from uniform (e.g. sufficiently large crystalline clusters). In the general case, the principal interdependence between partial phase compositions and the overall cluster composition in nanoparticle phase diagrams need to be taken into account. PMID:24918748

  1. Structure and solid solution properties of Cu-Ag nanoalloys

    NASA Astrophysics Data System (ADS)

    Atanasov, Ivailo; Ferrando, Riccardo; Johnston, Roy L.

    2014-07-01

    The nanoparticle phase diagram of an immiscible system is studied at the atomic level. Cu-Ag clusters with sizes 1000 and 2000 atoms, resulting from a global minimum search and belonging to icosahedral and crystalline structural motifs, are considered. We present the statistical analysis of the effect of temperature on the solubility of the two elements based on Metropolis Monte Carlo importance sampling. Our results suggest that the relevance of bulk phase diagrams to nanoparticles is limited to cases where the internal stress distribution does not deviate very much from uniform (e.g. sufficiently large crystalline clusters). In the general case, the principal interdependence between partial phase compositions and the overall cluster composition in nanoparticle phase diagrams need to be taken into account.

  2. Do Ni/Cu and Cu/Ni alloys have different catalytic performances towards water-gas shift? A density functional theory investigation.

    PubMed

    Huang, Yu Cheng; Zhou, Tao; Liu, Hai; Ling, ChongYi; Wang, SuFan; Du, Jin Yan

    2014-08-25

    Density functional calculations were preformed to investigate whether adding Ni into a Cu surface (denoted as Cu/Ni) or adding Cu into a Ni surface (Ni/Cu) is more efficient for catalyzing the water-gas shift (WGS)? The reactions of water dissociation and monoxide dissociation were selected to assess the activity and selectivity towards WGS, respectively. Our results show that Ni-atom modification of surfaces is thermodynamically favorable for both reactions. Kinetically, compared with pure Cu, water dissociation is greatly facilitated on Ni-modified surfaces, and the activity is insensitive to the Ni concentration; however, monoxide dissociation is not well-promoted on one Ni-atom-modified surfaces, but two Ni-atom modification can notably decrease the dissociation barriers. Overall, on the basis of these results, we conclude that 1) the catalytic performance of bimetallic metals is superior to monometallic ones; 2) at the same Ni concentration on the surface, Cu/Ni and Ni/Cu alloys have almost the same performance towards WGS; and 3) to acquire high WGS performance, the surface Ni atoms should either be low in concentration or highly dispersed. PMID:25044560

  3. Preparation and structural analysis of an Ag\\/NiO strained-layer superlattice

    Microsoft Academic Search

    Tetsuo Kado

    1995-01-01

    A new superlattice composed of Ag and NiO has been grown epitaxially on MgO(001) substrates by electron beam evaporation in ultrahigh vacuum. The samples were characterized by x-ray diffraction and cross-sectional high resolution transmission electron microscopy. Two component materials have different crystal structures; Ag has face-centered cubic structure and NiO has NaCl-type structure. Lattice mismatch between them is about 2%,

  4. Magnetite composition in Ni-Cu-PGE deposits worldwide: application to mineral exploration

    E-print Network

    Magnetite composition in Ni-Cu-PGE deposits worldwide: application to mineral exploration Emilie October 2013 Accepted 13 May 2014 Available online 21 May 2014 Keywords: Magnetite Ni Cu Sulfides Mineral in the exploration of ore deposits. Magnetite is a common accessory mineral in magmatic Ni­Cu­Platinum-Group Element

  5. Polyicosahedricity: icosahedron to icosahedron of icosahedra growth pathway for bimetallic (Au?Ag) and trimetallic (Au?Ag?M; M ? Pt, Pd, Ni) supraclusters; synthetic strategies, site preference, and stereochemical principles

    Microsoft Academic Search

    Boon K. Teo; Hong Zhang

    1995-01-01

    In this review, syntheses and structural systematics of a series of vertex-sharing polyicosahedral clusters containing group 11 (Au,Ag,Cu) and group 10 (Pt,Pd,Ni) metals are discussed. This particular series of clusters follows a well-defined growth pathway in which the basic building block is the 13-atom centered icosahedron. The design rule is vertex sharing and the cluster “grows” by successive additions of

  6. Surfactant Assisted Electrodeposition of Nanostructured CoNiCu Alloys

    NASA Astrophysics Data System (ADS)

    Hanafi, I.; Daud, A. R.; Radiman, S.; Ghani, M. H. A.; Budi, S.

    2013-04-01

    In order to obtain a desirable deposition thickness, nanostructured ternary CoNiCu alloys have been electrodeposited from salt solutions containing Co2+, Ni2+ and Cu2+ in the presence of a neutral surfactant alkyl polyglucoside (APG). Electrodeposition of CoNiCu was carried out in a three-electrode cell with indium-tin oxide (ITO) on glass plate, platinum wire and saturated calomel electrode (SCE) as working electrode, counter electrode and reference electrode, respectively. The nanostructured alloys were characterized by means of atomic force microscopy (AFM) and supported by field emission scanning electron microscopy (FESEM). The nanostructured CoNiCu alloys prepared in sulphate solutions in the presence of APG produced a thinner layer of nanoparticles of the alloys compared with the one deposited in the absence of APG. For a fixed deposition time, 160s and at an applied potential of - 875mV (SCE) the layer thickness was about 56 nm for electrodepositionin the presence of 3.25 wt.% APG and about 110 nm without APG. Only a small increase in thickness was observed when the potential was increased to more negative values i.e. - 875 to - 950 mV(SCE).

  7. Plasmon-enhanced photocatalytic properties of nano Ag@AgBr on single-crystalline octahedral Cu2O (1 1 1) microcrystals composite photocatalyst

    NASA Astrophysics Data System (ADS)

    Liu, Li; Lin, Shuanglong; Hu, Jinshan; Liang, Yinghua; Cui, Wenquan

    2015-03-01

    A new composite photocatalyst Ag@AgBr/Cu2O was prepared by loading Ag@AgBr on (1 1 1) facts of octahedral Cu2O substrate via a facile precipitation in situ photoreduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis), nitrogen sorption and the photoelectrochemical measurements. The results show that Ag@AgBr nanoparticles are well-dispersed on Cu2O nanoparticles with narrow size distributions and controllable sizes from 10 to 30 nm. TEM results of the as-synthesized Ag@AgBr/Cu2O nanocomposite revealed that Ag@AgBr nanoparticles were attached to the surface of octahedral Cu2O. Photocatalytic degradation of methylene blue (MB) was carried out to evaluate the photocatalytic activity of Ag@AgBr/Cu2O under visible-light irradiation. The Ag@AgBr/Cu2O composite showed stronger visible light absorption capacity and higher photocatalytic activity than pure Cu2O. The Ag@AgBr (15 wt.%)/Cu2O sample presented the best photocatalytic activity, degrading 93.28% MB after irradiation for 90 min, due to their high surface area (18.499 m2 g-1), the Crystal effect of Cu2O and surface plasmon resonance of Ag NPs. Meanwhile, phenol was degraded to further prove the degradation ability of Ag@AgBr/Cu2O. In addition, the quenching effect was examined in the photocatalytic reaction process of MB. Active h+, Br0 and the resulting rad O2- played the major roles for the dye degradation, while rad OH was verified to be insignificant. Based on the experimental results, a photocatalytic mechanism for organics degradation over Ag@AgBr/Cu2O photocatalysts was proposed. The electronic interactions were systematically studied and confirmed by the photoelectrochemical measurements.

  8. Growth and characterization of graphene on CuNi substrates

    NASA Astrophysics Data System (ADS)

    Tyagi, Parul

    Graphene is a single layer of sp2 bonded carbon atoms that crystallizes in the honeycomb structure. Because of its true two-dimensional structure, it has very unique electrical properties, including a very high carrier mobility that is symmetric for holes and electrons. To realize these unique properties, it is important to develop a method for growing graphene films with uniform thickness and low defect density. One of the most popular methods of growth is by chemical vapor deposition on Cu substrates, because it is self-limited. However many applications require the growth of graphene films that are more than one atomic layer thick. In this research project, the growth of graphene on CuNi substrates has been studied. The presence of Ni in the alloy results in an increase in the catalytic activity of the surface. This results in lower deposition pressures than for pure Cu and also increases the carbon solubility, which allows the growth of films that are more than one atomic layer thick. Two types of substrates were used for the growth of the graphene films: CuNi foils with an alloy composition of 90:10 and 70:30 Cu-Ni by weight and a CuNi(111) single crystal with a composition of 90:10 by weight. For the 70:30 substrates, it was very difficult to control the graphene thickness. On the other hand, the controlled growth of graphene films that were more than one layer thick was achieved on the 90:10 substrates. The growth morphology and the crystal structure of graphene grown on the CuNi(111) surface was determined by performing these studies in an ultra-high vacuum chamber to achieve very high purity conditions. The low energy electron diffraction analysis of the graphene films showed that the graphene films always nucleated in more than one rotational orientation with respect to the substrate. The growth was achieved at temperatures as low as 500 °C, which is much lower in temperature than for Cu substrates. Scanning electron microscopy analysis of the graphene overlayer grown at 900 °C showed that the formation of graphene proceeds by a layer plus island (Stranski-Krastanov) growth mode.

  9. A study of the ternary phase diagrams of Al–Co with Cu, Ag and Au

    Microsoft Academic Search

    S. Mi; B. Grushko; C. Dong; K. Urban

    2003-01-01

    Phase equilibria were studied in the Al–AlAg3–AlCo system at 670 and 900°C, and in the Al–Al2Au–AlCo system at 900 and 1000°C. The 900°C isothermal section of Al–Cu–Co was specified for Al–AlCo–AlCu. In contrast to Al–Cu–Co, no ternary phases were observed in the systems Al–Ag–Co and Al–Au–Co. The solubility of Ag and Au in M-Al13Co4 reaches ?1.5 at.%, and in the

  10. A study of the transient liquid phase bonding process applied to a Ag\\/Cu\\/Ag sandwich joint

    Microsoft Academic Search

    Isaac Tuah-Poku; M. Dollar; T. B. Massalski

    1988-01-01

    Transient liquid phase (TLP) bonding is a process currently used for joining heat resistant alloys, for example nickel- and\\u000a cobalt-based superalloys. It involves the formation of a liquid layer between two adjoining pieces and the formation of a\\u000a solid bond as the liquid disappears during annealing at a suitable constant temperature. In the present study, a model Ag\\/Cu\\/Ag\\u000a sandwich joint

  11. Interfacial Microstructure and Growth Kinetics of Intermetallic Compound Layers in Sn4 wt.%Ag\\/Cu-X (X = Zn, Ag, Sn) Couples

    Microsoft Academic Search

    H. F. Zou; Q. K. Zhang; Z. F. Zhang

    2011-01-01

    In the current study, the interfacial microstructures of Sn-Ag\\/Cu-X alloy (X = Ag, Sn or Zn) couples were investigated. The experimental results confirm that addition of Ag or Zn can effectively suppress the growth of the Cu3Sn layer, while addition of Sn accelerates the growth of the Cu3Sn layer. Meanwhile, the formation of voids is effectively suppressed by alloying the

  12. 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...

  13. Nanoscale duplex oxide growth during early stages of oxidation of Cu-Ni(100).

    SciTech Connect

    Zhou, G.; Fong, D. D.; Wang, L.; Fuoss, P. H.; Baldo, P. M.; Thompson, L. J.; Eastman, J. A.; Materials Science Division; State Univ. of New York; Univ. of Illinois

    2009-10-01

    A combination of real-time in situ synchrotron x-ray diffraction and ex situ transmission electron microscopy is utilized to investigate the early stages of oxidation of Cu-Ni(100). Sequential formation of NiO and Cu{sub 2}O oxides was observed by increasing oxygen partial pressure, and the Cu{sub 2}O phase was identified to form preferentially on top of NiO nanoislands. The origin of this unexpected phenomenon is attributed to localized enrichment of Cu atoms accompanied with NiO growth, which thermodynamically drives the nanoscale Cu{sub 2}O/NiO duplex oxide growth.

  14. Revision of the thermodynamic descriptions of the Cu–O, Ag–O, Ag–Cu–O, Bi–Sr–O, Bi–Ca–O, Bi–Cu–O, Sr–Cu–O, Ca–Cu–O and Sr–Ca–Cu–O systems

    Microsoft Academic Search

    Bengt Hallstedt; Ludwig J. Gauckler

    2003-01-01

    We have revised the thermodynamic descriptions of several subsystems of the Ag–Bi–Sr–Ca–Cu–O system. In the Cu–O system the description of the liquid phase was changed to remove an inverted miscibility gap at high temperature and to get a better fit of the CuO liquidus. Also the dissolution model for O in fcc-Cu and fcc-Ag was changed from substitutional to interstitial.

  15. Effects of the crystallographic orientation of Sn on the electromigration of Cu/Sn?Ag?Cu/Cu ball joints

    SciTech Connect

    Lee, Kiju; Kim, Keun-Soo; Tsukada, Yutaka; Suganuma, Katsuaki; Yamanaka, Kimihiro; Kuritani, Soichi; Ueshima, Minoru (Senju); (Kyocera); (Espec); (Osaka)

    2011-11-17

    Electromigration behavior and fast circuit failure with respect to crystallographic orientation of Sn grains were examined. The test vehicle was Cu/Sn-3.0 wt% Ag-0.5 wt% Cu/Cu ball joints, and the applied current density was 15 kA/cm{sup 2} at 160 C. The experimental results indicate that most of the solder bumps show different microstructural changes with respect to the crystallographic orientation of Sn grains. Fast failure of the bump occurred due to the dissolution of the Cu circuit on the cathode side caused by the fast interstitial diffusion of Cu atoms along the c-axis of the Sn grains when the c-axis was parallel to the electron flow. Slight microstructural changes were observed when the c-axis was perpendicular to the electron flow. In addition, Cu{sub 6}Sn{sub 5} intermetallic compound (IMC) was formed along the direction of the c-axis of the Sn grains instead of the direction of electron flow in all solder ball joints.

  16. Introduction of antibacterial function into biomedical TiNi shape memory alloy by the addition of element Ag.

    PubMed

    Zheng, Y F; Zhang, B B; Wang, B L; Wang, Y B; Li, L; Yang, Q B; Cui, L S

    2011-06-01

    A new kind of biomedical shape memory TiNiAg alloy with antibacterial function was successfully developed in the present study by the introduction of pure Ag precipitates into the TiNi matrix phase. The microstructure, mechanical property, corrosion resistance, ion release behavior in simulated body fluid, cytotoxicity and antibacterial properties were systematically investigated. The typical microstructural feature of TiNiAg alloy at room temperature was tiny pure Ag particles (at submicrometer or micrometer scales with irregular shape) randomly distributed in the TiNi matrix phase. The presence of Ag precipitates was found to result in a slightly higher tensile strength and larger elongation of TiNiAg alloy in comparison with that of TiNi binary alloy. Furthermore, a maximum shape recovery strain of ?6.4% was obtained with a total prestrain of 7% in the TiNiAg alloy. In electrochemical and immersion tests, TiNiAg alloy presented good corrosion resistance in simulated body fluid, comparable with that of CP Ti and TiNi alloy. The cytotoxicity evaluation revealed that TiNiAg alloy extract induced slight toxicity to cells, but the viability of experimental cells was similar to or higher than that of TiNi alloy extract. In vitro bacterial adhesion study indicated a significantly reduced number of bacteria (S. aureus, S. epidermidis and P. gingivalis) on the TiNiAg alloy plate surface when compared with that on TiNi alloy plate surface, and the corresponding antibacterial mechanism for the TiNiAg alloy is discussed. PMID:21316493

  17. Characterization of Cu3P phase in Sn3.0Ag0.5Cu0.5P/Cu solder joints

    NASA Astrophysics Data System (ADS)

    Chen, Jian-xun; Zhao, Xing-ke; Zou, Xu-chen; Huang, Ji-hua; Hu, Hai-chun; Luo, Hai-lian

    2014-01-01

    This article reports the effects of phosphorus addition on the melting behavior, microstructure, and mechanical properties of Sn3.0Ag0.5Cu solder. The melting behavior of the solder alloys was determined by differential scanning calorimetry. The interfacial microstructure and phase composition of solder/Cu joints were studied by scanning electron microscopy and energy dispersive spectrometry. Thermodynamics of Cu-P phase formation at the interface between Sn3.0Ag0.5Cu0.5P solder and the Cu substrate was characterized. The results indicate that P addition into Sn3.0Ag0.5Cu solder can change the microstructure and cause the appearance of rod-like Cu3P phase which is distributed randomly in the solder bulk. The Sn3.0Ag0.5Cu0.5P joint shows a mixture of ductile and brittle fracture after shear testing. Meanwhile, the solidus temperature of Sn3.0Ag0.5Cu solder is slightly enhanced with P addition.

  18. Complete miscibility between different crystallographic structures: Monte Carlo simulations of Cu-Ag deposited on Cu(001)

    Microsoft Academic Search

    I. Braems; F. Berthier; J. Creuze; R. Tétot; B. Legrand

    2006-01-01

    Monte Carlo simulations of an AgcCu1-c monolayer deposited onto Cu(001) show that complete miscibility of two elements adopting different crystallographic structures can be observed in the surface, while experimental bulk phase diagrams preclude a similar phenomenon in the bulk. While the deposited pure Ag monolayer is pseudohexagonal and the pure Cu monolayer is square and pseudomorphic, for intermediate concentrations at

  19. Optical and quantum efficiency analysis of (Ag,Cu)(In,Ga)Se2 absorber layers

    SciTech Connect

    Boyle, Jonathan; Hanket, Gregory; Shafarman, William

    2009-06-09

    (Ag,Cu)(In,Ga)Se2 thin films have been deposited by elemental co-evaporation over a wide range of compositions and their optical properties characterized by transmission and reflection measurements and by relative shift analysis of quantum efficiency device measurements. The optical bandgaps were determined by performing linear fits of (?h?)2 vs. h?, and the quantum efficiency bandgaps were determined by relative shift analysis of device curves with fixed Ga/(In+Ga) composition, but varying Ag/(Cu+Ag) composition. The determined experimental optical bandgap ranges of the Ga/(In+Ga) = 0.31, 0.52, and 0.82 groups, with Ag/(Cu+Ag) ranging from 0 to 1, were 1.19-1.45 eV, 1.32-1.56 eV, and 1.52-1.76 eV, respectively. The optical bowing parameter of the different Ga/(In+Ga) groups was also determined.

  20. New bulk glassy alloys in Cu-Zr-Ag ternary system prepared by casting and milling

    NASA Astrophysics Data System (ADS)

    Janovszky, D.; Tomolya, K.; Sveda, M.; Solyom, J.; Roosz, A.

    2009-01-01

    The thermal stability, crystallization behaviour and glass forming ability of Cu-Zr-Ag system have been investigated on the basis of a ternary phase diagram. We altered the concentration of the alloys from the Cu58Zr42 to the concentration of the deep eutectic point of the Cu-Zr-Ag ternary system and we calculated the glass forming ability parameters. This paper summerises the results of the procedure during which Cu-Zr-Ag amorphous alloys with different Ag content (0-25%) were prepared by casting and ball-milling. Wedge-shaped samples were prepared from the ingots by centrifugal casting into copper mold. The supercooled liquid region (?Tx) exceeded 75K. Following the characterization of the cast alloys, master alloys of identical composition were milled in a Fritsch Pulverisette 2 ball-mill. The powders, milled for various periods of time were analysed by XRD in order to define the amorphous fraction.

  1. 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.

  2. Transmission electron microscope investigations on Cu-Ag alloys produced by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Kormout, K. S.; Yang, B.; Pippan, R.

    2014-08-01

    Cu-Ag alloys in three different compositions (Cu - 25/50/75wt% Ag) were produced by powder consolidation followed by high-pressure torsion. Deformation was performed till a saturation regime was reached. The generated microstructures were investigated by transmission electron microscopy and vary from ultra-fine grained to nanocrystalline to even partially amorphous structures. Vickers hardness measurements show a strong increase in hardness compared with the pure metals, annealing at 130°C leads to an additional increase in hardness.

  3. Energy straggling for medium-energy H sup + beams penetrating Cu, Ag, and Pt

    Microsoft Academic Search

    Y. Kido; T. Koshikawa

    1991-01-01

    The electronic-energy-straggling values for 50--250-keV H{sup +} beams penetrating Cu, Ag, and Pt have been measured using backscattering. The Cu, Ag, and Pt layers with a thickness of about 30 nm were deposited onto Si, SiOâ, AlâOâ, and ZrOâ substrates with electron beams or by sputtering. The uniformity and grain growth of the thin films were observed by cross-section transmission

  4. Structure-properties relationship in reactively sputtered Ag-Cu-O films

    Microsoft Academic Search

    C. Petitjean; D. Horwat; J. F. Pierson

    2009-01-01

    Ag-Cu-O films were deposited on glass substrates by pulsed dc sputtering of a silver-copper target (Ag50Cu50) in reactive Ar-O2 mixtures. The film chemical composition was estimated by x-ray energy dispersive spectrometry and the structure was studied by x-ray diffraction (XRD). Optical properties (reflectance and transmittance) and room temperature electrical resistivity were evaluated using spectrophotometry and the four point probe method,

  5. First principles studies of the geometric and electronic structure of nanoalloy Ag27Cu7

    Microsoft Academic Search

    M. Alcantara Ortigoza; T. S. Rahman

    2007-01-01

    We present first-principles calculations of the structure and electronic density of states (DOS) for the perfect core-shell Ag27Cu7 nanocluster. Our results show an expansion of 0.4 A in the diameter of the cluster compared with previous results^*. From the projected DOS we conclude that the 34-atom cluster has only 2 non-equivalent Cu atoms (core) and 4 non-equivalent Ag atoms (shell),

  6. Spectroscopy of microcrystals in the CuI-AgI system

    SciTech Connect

    Voll, V.A.; Barmasov, A.V.; Struts, A.V. [St. Petersburg State Univ., Petrodvorets (Russian Federation)

    1994-06-01

    Using comparative analysis of the absorption and luminescence spectra of samples with different compositions, we studied the effect of the preparation procedure on the structure of composite CuI-AgI microcrystals formed in the gelatin matrix. The resonance character of excitation and its localization at the substrate/epitax interface were established. The most probable composition of the thermally stable photolytic centers as a function of the relative content of Cu and Ag was discussed.

  7. A Study of Plasma-Cleaned Ag-Plated Cu Leadframe Surfaces

    Microsoft Academic Search

    Wuhu Li

    2010-01-01

    In this study, an Ar plasma was employed to remove the antitarnish layer on Ag-plated Cu leadframe surfaces using various\\u000a process powers and times. Measurements of the contact angle, field-emission scanning electron microscopy, x-ray photoelectron\\u000a spectroscopy, and time-of-flight secondary-ion mass spectrometry were employed to characterize both the Ag and Cu surfaces\\u000a before and after plasma cleaning. The antitarnish layer on

  8. MSXalpha calculation of the electronic structure of Cu + and Ag + ions in lithium chloride single crystal

    Microsoft Academic Search

    B. Moine; H. Chermette; C. Pedrini

    1986-01-01

    The multiple-scattering X? method applied to an embedded (MCl6)5? cluster (M=Ag,Cu) is used to describe the electronic structure of Ag+ and Cu+ in the LiCl crystal. Several calculations have been performed with different impurity–ligand distances in order to reach the equilibrium distance. The vibrational energy of the breathing mode is deduced from the total energy variation of the cluster vs

  9. Total sputtering yield of Ag\\/Cu alloys for low energy argon ions

    Microsoft Academic Search

    K. W. Pierson; J. L. Reeves; T. D. Krueger; C. D. Hawes; C. B. Cooper

    1996-01-01

    Measurement of the total sputtering yields of Ag\\/Cu two-phase alloy targets for normally incident 200 and 100 eV Ar+ ions have been performed. The dose was approximately 1019 ions and the target temperature was held at about 20°C. A graph of total sputtering yield versus Ag\\/Cu (at.%) composition is “V-shaped” with the yield of all compositions being lower than either

  10. Total sputtering yield of Ag\\/Cu alloys for low energy argon ions

    Microsoft Academic Search

    K. W. Pierson; J. L. Reeves; T. D. Krueger; C. D. Hawes; C. B. Cooper

    1996-01-01

    Measurement of the total sputtering yields of Ag\\/Cu two-phase alloy targets for normally incident 200 and 100 eV Ar+ ions have been performed. The dose was approximately 1019 ions and the target temperature was held at about 20°C. A graph of total sputtering yield versus Ag\\/Cu (at.%) composition is 'V-shaped' with the yield of all compositions being lower than either

  11. Local structure of disordered Au-Cu and Au-Ag alloys

    NASA Astrophysics Data System (ADS)

    Frenkel, A. I.; Machavariani, V. Sh.; Rubshtein, A.; Rosenberg, Yu.; Voronel, A.; Stern, E. A.

    2000-10-01

    X-ray-absorption fine structure (XAFS) and x-ray-diffraction (XRD) measurements of disordered alloys AuxCu1-x and Au0.5Ag0.5 prepared by melt spinning were performed. In the Au0.5Ag0.5 alloy, no significant local deviations of the atoms from the average fcc lattice were detected while in AuxCu1-x alloys, significant deviations of atoms from the average fcc lattice were found. Mean-square vibrations of the Cu-Cu distances revealed by the XAFS in AuxCu1-x alloys indicate the weakening of contact between Cu atoms in the dilute limit. Our computer simulation for AuxCu1-x clusters of 105 atoms reproduces the main features of both the XAFS and XRD data.

  12. Details on the formation of Ti2Cu3 in the Ag-Cu-Ti system in the temperature range 790-860 C

    E-print Network

    Boyer, Edmond

    , stability, ternary phase diagram, experimental study 1. Introduction Alloys of the Ag-Cu-Ti ternary system is a titanium base alloy [2, 3], a thorough knowledge of the phase diagram of the Ag-Cu-Ti system is needed compositions containing 40 at% of copper (28 wt%Cu, binary eutectic alloy with a melting point at 780 °C

  13. Preparation, optical and non-linear optical power limiting properties of Cu, CuNi nanowires

    SciTech Connect

    Udayabhaskar, R.; Karthikeyan, B., E-mail: bkarthik@nitt.edu [Department of Physics, National Institute of Technology, Tiruchirappalli 620 015 (India); Ollakkan, Muhamed Shafi [Light and Matter Physics Group, Raman Research Institute, Bangalore 560 080 (India)] [Light and Matter Physics Group, Raman Research Institute, Bangalore 560 080 (India)

    2014-01-06

    Metallic nanowires show excellent Plasmon absorption which is tunable based on its aspect ratio and alloying nature. We prepared Cu and CuNi metallic nanowires and studied its optical and nonlinear optical behavior. Optical properties of nanowires are theoretically explained using Gans theory. Nonlinear optical behavior is studied using a single beam open aperture z-scan method with the use of 5?ns Nd: YAG laser. Optical limiting is found to arise from two-photon absorption.

  14. The discontinuous surface transition in the Cu(111)(Ag) binary segregating system

    Microsoft Academic Search

    J. Y Wang; J du Plessis; J. J Terblans; G. N van Wyk

    1999-01-01

    The discontinuous transition in the Ag equilibrium surface concentration as a function of temperature for a Cu(111) 0.20at% Ag sample is presented in this paper. The criteria for observing this type of transition are derived, and an expression for the critical bulk concentration, above which no transition is observed, is found. The experimental equilibrium surface concentration values are fitted by

  15. Magnetic properties of Ni-Cu-Mn ferrite system

    NASA Astrophysics Data System (ADS)

    Roumaih, Kh.

    2011-10-01

    Three groups according to the substitution of Cu 2+ and Mn 3+ in the system Ni 1-xCu xFe 2-yMn yO 4 ferrite with x = 0.2, 0.5, 0.8, and y varying from 0.0 to 1.0 in steps of 0.25 are prepared by solid state reactions. The phases of the Ni 1-xCu xFe 2-yMn yO 4 ferrite have been confirmed by X-ray diffraction (XRD). The results demonstrate that all of the synthesized materials are spinel with cubic unit cell and the lattice constant increased with increases of the Cu and Mn ions for all samples. The hyperfine interaction was studied by the Mössbauer spectroscopy at room temperature for all samples. The spectra of all samples show two well-resolved Zeeman patterns corresponding to A- and B-sites. The hyperfine field decreases with increasing Cu and Mn ions concentration. The Curie temperature, TC, was calculated from the temperature dependence of magnetization curves. The hysteresis curve recorded at room temperature shows that the samples are ferrimagnetic materials. The cation distribution was estimated from the results of Mössbauer spectroscopy and magnetic measurements.

  16. Structural and permeation kinetic correlations in PdCuAg membranes.

    PubMed

    Zhao, Lingfang; Goldbach, Andreas; Bao, Chun; Xu, Hengyong

    2014-12-24

    Addition of Ag is a promising way to enhance the H2 permeability of sulfur-tolerant PdCu membranes for cleanup of coal-derived hydrogen. We investigated a series of PdCuAg membranes with at least 70 atom % Pd to elucidate the interdependence between alloy structure and H2 permeability. Membranes were prepared via sequential electroless plating of Pd, Ag, and Cu onto ceramic microfiltration membranes and subsequent alloying at elevated temperatures. Alloy formation was complicated by a wide miscibility gap in the PdCuAg phase diagram at the practically feasible operation temperatures. X-ray diffraction showed that the lattice constants of the fully alloyed ternary alloys obey Vegard's law closely. In general, H2 permeation rates increased with increasing Ag and decreasing Cu content of the membranes in the investigated temperature range. Detailed examination of the permeation kinetics revealed compensation between activation energy and pre-exponential factor of the corresponding H2 permeation laws. The origin of this effect is discussed. Further analysis showed that the activation energy for H2 permeation decreases overall with increasing lattice constant of the ternary alloy. The combination of these correlations results in a structure-function relationship that will facilitate rational design of PdCuAg membranes. PMID:25496043

  17. Dielectric behaviour of Ni substituted Cu nano-ferrite

    NASA Astrophysics Data System (ADS)

    Parashar, Jyoti; Saxena, V. K.; Jyoti, Bhatnagar, Deepak; Sharma, K. B.

    2015-06-01

    Dielectric properties such as dielectric constant and dielectric loss factor tan ? are reported for Ni substituted Cu ferrite having formula Cu1-xNixFe2O4 prepared by sol-gel auto combustion method. The variation of real part of dielectric constant and dielectric loss tan ? with frequency are measured in the frequency range 1000 Hz to 120 MHz at room temperature. The real part of dielectric constant (?') decreases with the increase in frequency. The relation of tan ? with frequency shows relaxation spectra. Dielectric constant as a function of temperature is studied at different temperatures ranging from 303 K to 623 K.

  18. Superhydrophobic surfaces via electroless displacement of nanometric Cu layers by Ag +

    NASA Astrophysics Data System (ADS)

    Brenier, R.; Ramos, S. M. M.; Montchanin, M.

    2009-05-01

    This paper explores the possibility of making hydrophobic and superhydrophobic surfaces from electroless displacement of Cu by Ag +, in the case where Cu oxidation is limited owing to Cu layers of nanometric thicknesses. The morphology of the Ag layers is studied by scanning electron microscopy for Cu thicknesses between 10 and 80 nm. The mapping of the elemental content of the layers by electron dispersive X-ray analysis also has been used to clarify the particle growing by diffusion limited aggregation. It is shown that the average size and the shape complexity of the Ag particles increase with the Cu thickness. The addition of dimethyl sulfoxide in the Ag + aqueous solution improves the surface homogeneity, increases the particle density and decreases their sizes. The wetting behaviour of the surfaces, after grafting with octadecanethiol, has been studied from measurements of the contact angles of a drop of water. According to the thickness of the initial Cu layer and the morphology of the Ag layer, contact angles range between 110° and 154°. Superhydrophobic surfaces are obtained from 80 nm thick Cu layers.

  19. Corrosion Behavior of Pb-Free Sn-1Ag-0.5Cu- XNi Solder Alloys in 3.5% NaCl Solution

    NASA Astrophysics Data System (ADS)

    Mohanty, Udit Surya; Lin, Kwang-Lung

    2013-04-01

    Potentiodynamic polarization techniques were employed in the present study to investigate the corrosion behavior of Pb-free Sn-1Ag-0.5Cu- XNi solder alloys in 3.5% NaCl solution. Polarization studies indicated that an increase in Ni content from 0.05 wt.% to 1 wt.% in the solder alloy shifted the corrosion potential ( E corr) towards more negative values and increased the linear polarization resistance. Increased addition of Ni to 1 wt.% resulted in significant increase in the concentration of both Sn and Ni oxides on the outer surface. Secondary-ion mass spectrometry and Auger depth profile analysis revealed that oxides of tin contributed primarily towards the formation of the passive film on the surface of the solder alloys containing 0.05 wt.% and 1 wt.% Ni. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) established the formation of a Sn whisker near the passive region of the solder alloy obtained from the polarization curves. The formation of Sn whiskers was due to the buildup of compressive stress generated by the increase in the volume of the oxides of Sn and Ni formed on the outer surface. The presence of Cl- was responsible for the breakdown of the passive film, and significant pitting corrosion in the form of distinct pits was noticed in Sn-1Ag-0.5Cu-0.5Ni solder alloy after the polarization experiment.

  20. Elastic Moduli of (Ni,Cu)3Sn4 Ternary Alloys from First-Principles Calculations

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Qu, Jianmin

    2010-11-01

    Based on first-principles calculations, the effect of Cu solubility on the elastic moduli of Ni3Sn4-based intermetallic compound (IMC) is investigated. It is found that the stiffness tensor of a (Ni,Cu)3Sn4 single crystal is anisotropic, and the presence of Cu in the crystal compound reduces the moduli of (Ni,Cu)3Sn4 due to reduced hybridization between Ni and Sn states. Furthermore, our results show that higher Cu concentration in the (Ni,Cu)3Sn4-based IMCs leads to thermodynamically less stable compounds. Based on the single-crystal results, the elastic properties of polycrystalline (Ni,Cu)3Sn4 are also obtained.

  1. On the Role of Ni in Cu Precipitation in Multicomponent Steels

    NASA Astrophysics Data System (ADS)

    Liu, Qingdong; Gu, Jianfeng; Liu, Wenqing

    2013-10-01

    The nature of Cu precipitation in quench-tempered multicomponent high-strength low-alloy steels is characterized by atom probe tomography. The detected nanometer sized Ni-rich clusters act as preferential nucleation sites for Cu-rich clusters, and Ni segregation at the Cu-rich precipitate/matrix heterophase interface contribute to fast growth of Cu precipitates. Molecular dynamics simulation indicates that local Ni clustering at atomic scale significantly quickens the solute diffusion. The initial Ni composition has a profound effect on the nature of Cu precipitation.

  2. Corrosion investigation of Cu–Ni tube desalination plant

    Microsoft Academic Search

    K. Abouswa; F. Elshawesh; O. Elragei; A. Elhood

    2007-01-01

    Copper-based alloy tubes (i.e. Cu–Ni) are extensively used in desalination plants. This is in order to complete the heating and evaporating process for the seawater and to obtain distillate water that can be used in the steam generation plant and as drinking water. A number of these tubes were found to suffer from severe localized corrosion at 6 o’clock position

  3. Stress and oxidation in CuNi thin films

    Microsoft Academic Search

    W. Brückner; S Baunack

    1999-01-01

    The stress evolution of a 400 nm thick Cu0.57Ni0.42Mn0.01 resistive film on oxidized silicon substrate was investigated during a thermal cycle to 550°C using a laser-optical substrate-curvature technique. Cycle-stop-prepared samples were used to clarify the correlation between stress development and oxidation, especially by concentration-depth profiling using Auger electron spectroscopy. In the stress curve, the striking feature associated with oxidation is

  4. Adaptive Crystal Structures: CuAu and NiPt

    Microsoft Academic Search

    M. Sanati; L. G. Wang; Alex Zunger

    2003-01-01

    We discover that Au-rich Cu1-xAux and Pt-rich Ni1-xPtx contain a composition range in which there is a quasicontinuum of stable, ordered ``adaptive structures'' made of (001) repeat units of simple structural motifs. This is found by searching ˜3×106 different fcc configurations whose energies are parametrized via a ``cluster expansion'' of first-principles-calculated total energies of just a few structures. This structural

  5. Emission spectral characteristics of Cu, Ag, Zn, and Cd neutral atoms in a glow discharge

    Microsoft Academic Search

    Yuhui Zhao; Gary Horlick

    2006-01-01

    Detailed spectra highlighting the neutral atom emission characteristics (i.e. I lines) for Cu, Zn, Ag and Cd in a glow discharge device are presented in this study. A particular focus is the presentation of spectra that document the many high excitation energy neutral atom lines that are observed in these spectra. For Cu, several spectral lines originating from levels close

  6. The phase diagrams of M 2X?SiX 2 (M is Cu, Ag; X is S, Se)

    Microsoft Academic Search

    Mahadevan Venkatraman; Roger Blachnik; Andreas Schlieper

    1995-01-01

    The phase diagrams of Cu2S?SiS2, Ag2S?SiS2 and Ag2Se?SiSe2 were investigated by DTA and X-ray methods. The system Cu2S?SiS2 contains two compounds: Cu2SiS3 and Cu8SiS6. The compound Cu6Si2S7 does not exist. The phase diagram of Ag2S?SiS2 is characterized by the presence of two ternary compounds: Ag8SiS6 and Ag10Si3S11. The Ag2Se?SiSe2 system contains only Ag8SiSe6, which forms a eutectic on either side.

  7. Enhancement of light reflectance and thermal stability in Ag-Cu alloy contacts on p-type GaN

    NASA Astrophysics Data System (ADS)

    Son, Jun Ho; Jung, Gwan Ho; Lee, Jong-Lam

    2008-07-01

    The mechanism for thermally stable Ag-Cu alloy Ohmic contact on p-type GaN was investigated. Ag-Cu contact showed lower contact resistivity as low as 8.6×10-6?cm2, higher reflectance of 84% at 460nm, and better thermal stability than Ag contact after annealing in air ambient. The formation of Ag-Ga solid solution lowered the contact resistivity. Additionally the formation of Cu oxide suppresses the Ag oxidation and increases the work function of the Ag-Cu contact via decreasing the Schottky barrier height for hole injection. Precipitation of Cu oxide at grain boundaries suppresses the Ag agglomeration, leading to enhanced light reflectance as well as thermal stability.

  8. Energetics of the formation of Cu–Ag core–shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Chandross, Michael

    2014-10-01

    This work presents molecular dynamics and Monte Carlo simulations aimed at developing an understanding of the formation of core–shell Cu–Ag nanoparticles. The effects of surface and interfacial energies were considered and used to form a phenomenological model that calculates the energy gained upon the formation of a core–shell structure from two previously distinct, non-interacting nanoparticles. In the majority of cases, the core–shell structure was found to be energetically favored. Specifically, the difference in energy as a function of the radii of the individual Cu and Ag particles was examined, with the assumption that a core–shell structure forms. In general, it was found that the energetic gain from forming such a structure increased with increasing size of the initial Ag particle. This result was interpreted as a result of the reduction in surface energy. For two separate particles, both Cu and Ag contribute to the surface energy; however, for a core–shell structure, the only contribution to the surface energy is from the Ag shell and the Cu contribution is changed to a Cu–Ag interfacial energy, which is always smaller.

  9. Phase diagrams of the Cu 1.95 (Ag 2)Te-ZnTe(CdTe) quasibinary systems and liquidus surfaces of the Cu 1.95 (Ag 2)Te-ZnTe-CdTe quasiternary systems

    Microsoft Academic Search

    L. I. TRISHCHUK; G. S. OLIYNYK; V. M. TOMASHYK

    Phase diagrams of the quasibinary systems Cu 1.95 (Ag 2)Te-ZnTe, Cu 1.95 (Ag 2)Te-CdTe and the vertical sections Cu 1.95 (Ag 2)Te-Zn xCd 1-xTe ( ? = 0.2, 0.4, 0.6 and 0.8) have been constructed usi ng methods of physico-chemical analysis. The liquidus surfaces of the quasiternary systems Cu 1.95 Te-ZnTe-CdTe and Ag 2Te-ZnTe-CdTe have been determined based on experimental

  10. Effects of Cu contents in Pb-free solder alloys on interfacial reactions and bump reliability of Pb-free solder bumps on electroless NiP under-bump metallurgy

    Microsoft Academic Search

    Young-Doo Jeon; Kyung-Wook Paik; Adreas Ostmann; Herbert Reichl

    2005-01-01

    Using the screen-printed solder-bumping technique on the electroless plated Ni-P under-bump metallurgy (UBM) is potentially\\u000a a good method because of cost effectiveness. As SnAgCu Pb-free solders become popular, demands for understanding of interfacial\\u000a reactions between electroless Ni-P UBMs and Cu-containing Pb-free solder bumps are increasing. It was found that typical Ni-Sn\\u000a reactions between the electroless Ni-P UBM and Sn-based solders

  11. Interfacial Phenomena in Al/Al, Al/Cu, and Cu/Cu Joints Soldered Using an Al-Zn Alloy with Ag or Cu Additions

    NASA Astrophysics Data System (ADS)

    Pstru?, Janusz; Gancarz, Tomasz

    2014-05-01

    The studies of soldered joints were carried out in systems: Al/solder/Al, Al/solder/Cu, Cu/solder/Cu, where the solder was (Al-Zn)EUT, (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Ag and (Al-Zn)EUT with 0.5, 1.0, and 1.5 at.% of Cu addition. Brazing was performed at 500 °C for 3 min. The EDS analysis indicated that the composition of the layers starting from the Cu pad was CuZn, Cu5Zn8, and CuZn4, respectively. Wetting tests were performed at 500 °C for 3, 8, 15, and 30 min, respectively. Thickness of the layers and their kinetics of growth were measured based on the SEM micrographs. The formation of interlayers was not observed from the side of Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed.

  12. BaCuO 2 - Ag interaction: a central feature in the densification of Ag - Y 1Ba 2Cu 3O 7-? composites

    NASA Astrophysics Data System (ADS)

    Fiscina, Jorge E.; González Oliver, Carlos J. R.; Esparza, Daniel A.

    1994-12-01

    Dilatometric and DTA / TGA measurements (in O 2 atmosphere) on Ag-123 composites indicate that silver affects dramatically the two principal reactions that provoke the unstabilization of Y 1Ba 2Cu 3O 7-?. These are the precipitation of 011 phase plus Yttrium rich liquid (900-930°C), and the peritectic reaction triggered by 011 fusion (980-1040°C). Silver increases, upon initial heating, the partial decomposition of 123 phase (ER). For pre-peritectic temperatures higher than the Ag?AgO eutectic temperature, it interacts with 011 phase for developing a “re-assembling mechanism”. A modified 123 phase named 123 ? is formed, containing doping levels of Ag, possibly as a layer of 123 ? around 123 grains. SEM / EDAX analysis show the superficial nature of the re-assembling phenomena.

  13. Evidence that NiNi acetyl-CoA synthase is active and that the CuNi enzyme is not.

    PubMed

    Seravalli, Javier; Xiao, Yuming; Gu, Weiwei; Cramer, Stephen P; Antholine, William E; Krymov, Vladimir; Gerfen, Gary J; Ragsdale, Stephen W

    2004-04-01

    The bifunctional CO dehydrogenase/acetyl-CoA synthase (CODH/ACS) plays a central role in the Wood-Ljungdahl pathway of autotrophic CO(2) fixation. One structure of the Moorella thermoacetica enzyme revealed that the active site of ACS (the A-cluster) consists of a [4Fe-4S] cluster bridged to a binuclear CuNi center with Cu at the proximal metal site (M(p)) and Ni at the distal metal site (M(d)). In another structure of the same enzyme, Ni or Zn was present at M(p). On the basis of a positive correlation between ACS activity and Cu content, we had proposed that the Cu-containing enzyme is active [Seravalli, J., et al. (2003) Proc. Natl. Acad. Sci. U.S.A. 100, 3689-3694]. Here we have reexamined this proposal. Enzyme preparations with a wider range of Ni (1.6-2.8) and Cu (0.2-1.1) stoichiometries per dimer were studied to reexamine the correlation, if any, between the Ni and Cu content and ACS activity. In addition, the effects of o-phenanthroline (which removes Ni but not Cu) and neocuproine (which removes Cu but not Ni) on ACS activity were determined. EXAFS results indicate that these chelators selectively remove M(p). Multifrequency EPR spectra (3-130 GHz) of the paramagnetic NiFeC state of the A-cluster were examined to investigate the electronic state of this proposed intermediate in the ACS reaction mechanism. The combined results strongly indicate that the CuNi enzyme is inactive, that the NiNi enzyme is active, and that the NiNi enzyme is responsible for the NiFeC EPR signal. The results also support an electronic structure of the NiFeC-eliciting species as a [4Fe-4S](2+) (net S = 0) cluster bridged to a Ni(1+) (S = (1)/(2)) at M(p) that is bridged to planar four-coordinate Ni(2+) (S = 0) at M(d), with the spin predominantly on the Ni(1+). Furthermore, these studies suggest that M(p) is inserted during cell growth. The apparent vulnerability of the proximal metal site in the A-cluster to substitution with different metals appears to underlie the heterogeneity observed in samples that has confounded studies of CODH/ACS for many years. On the basis of this principle, a protocol to generate nearly homogeneous preparations of the active NiNi form of ACS was achieved with NiFeC signals of approximately 0.8 spin/mol. PMID:15049702

  14. Reaction of Liquid Sn-Ag-Cu-Ce Solders with Solid Copper

    NASA Astrophysics Data System (ADS)

    Chriaštel'Ová, J.; Rízeková Trnková, L.; Pocisková Dimová, K.; Ožvold, M.

    2011-09-01

    Small amounts of the rare-earth element Ce were added to the Sn-rich lead-free eutectic solders Sn-3.5Ag-0.7Cu, Sn-0.7Cu, and Sn-3.5Ag to improve their properties. The microstructures of the solders without Ce and with different amounts (0.1 wt.%, 0.2 wt.%, and 0.5 wt.%) of Ce were compared. The microstructure of the solders became finer with increasing Ce content. Deviation from this rule was observed for the Sn-Ag-Cu solder with 0.2 wt.% Ce, and for the Sn-0.7Cu eutectic alloy, which showed the finest microstructure without Ce. The melting temperatures of the solders were not affected. The morphology of intermetallic compounds (IMC) formed at the interface between the liquid solders and a Cu substrate at temperatures about 40°C above the melting point of the solder for dipping times from 2 s to 256 s was studied for the basic solder and for solder with 0.5 wt.% Ce addition. The morphology of the Cu6Sn5 IMC layer developed at the interface between the solders and the substrate exhibited the typical scallop-type shape without significant difference between solders with and without Ce for the shortest dipping time. Addition of Ce decreased the thickness of the Cu6Sn5 IMC layer only at the Cu/Sn-Ag-Cu solder interface for the 2-s dipping. A different morphology of the IMC layer was observed for the 256-s dipping time: The layers were less continuous and exhibited a broken relief. Massive scallops were not observed. For longer dipping times, Cu3Sn IMC layers located near the Cu substrate were also observed.

  15. Synthesis of Cu–Ni Alloy Powder Directly from Metal Salts Solution

    Microsoft Academic Search

    Choong-Hwan Jung; Hee-Gyoun Lee; Chan-Joong Kim; S. B. Bhaduri

    2003-01-01

    Cu–Ni alloy powders were synthesized directly from metal nitrate solution. Combustion, ultrasonic mist combustion and ultrasonic pyrolysis processes were applied and Cu–Ni alloy powder was successfully synthesized by mist combustion and ultrasonic pyrolysis of nitrate salts in a reducing atmosphere. X-ray diffraction data showed that the copper and the nickel atoms were completely mixed. For Cu–Ni alloy powder prepared by

  16. Availability and toxicity of Cu and Ni to Scots pine in different soils

    Microsoft Academic Search

    Tiina M. Nieminen; Liisa Ukonmaanaho; Nicole Rausch; William Shotyk

    2006-01-01

    We compared the phytoavailability and within plant mobility of Cu and Ni, as well as the plant mortality, in two contrasting substrates: intact smelter-polluted podzol soil profiles and artificially Cu-Ni contaminated quartz-sand media. Both the uptake and the root-to-shoot transport of Cu and Ni by pine seedlings were clearly higher in the artificially contaminated quartz-sand. No pine mortality took place

  17. Annealing effect on magnetoresistance in NiO-Co-Cu based spin valves

    Microsoft Academic Search

    A. M. Zhang; X. S. Wu; L. Sun; Y. X. Wang; M. Lu; A. Hu; S. S. Jiang; Z. J. Chen; X. Chen; M. H. Sun; Z. H. Wu

    2005-01-01

    We have fabricated two sets of NiO-Co-Cu based spin valves by the magnetosputtering technique with different deposition parameters. Magnetoresistance (MR) measurements show that the MR value for the NiO layer under the bottom of Co\\/Cu\\/Co spin valve (BSV) is larger than that for the NiO layer at the top of Co\\/Cu\\/Co (TSV). The MR value of BSV decreases with increasing

  18. Monolithic CuO–NiO aerogels via an epoxide addition route

    Microsoft Academic Search

    Andrew M. Shobe; Simerjeet K. Gill

    2010-01-01

    In this report we demonstrate the synthesis of monolithic mixed copper(II)–nickel(II) (Cu–Ni) oxide aerogels using the epoxide addition method. This single step synthetic method provides a straightforward route to synthesize highly porous CuO–NiO materials composed of nanometer sized particles. Control of the particle size and gel morphology is achieved by simple changes in the initial synthetic conditions. The as-synthesized Cu–Ni

  19. Nanoscale duplex oxide growth during early stages of oxidation of Cu-Ni(100)

    Microsoft Academic Search

    Zhou Guangwen; Dillon D. Fong; Paul H. Fuoss; Peter M. Baldo; Loren J. Thompson; Jeffrey A. Eastman; Wang Liang

    2009-01-01

    A combination of real-time in situ synchrotron x-ray diffraction and ex situ transmission electron microscopy is utilized to investigate the early stages of oxidation of Cu-Ni(100). Sequential formation of NiO and CuO oxides was observed by increasing oxygen partial pressure, and the CuO phase was identified to form preferentially on top of NiO nanoislands. The origin of this unexpected phenomenon

  20. Surface phase interactions in the NiO-CuO system from electrical conductivity data

    Microsoft Academic Search

    A. A. Dulov; L. A. Abramova; E. Z. Golosman; V. N. Efremov; V. I. Yakerson

    1988-01-01

    Using the thermovacuum electrical conductivity (TVC) curve method, we have shown that in the NiO-CuO system obtained from metal hydroxocarbonates, for a CuO content of 5 wt % heat treatment at 400\\/degrees\\/C in air leads to formation of an NiO type phase, hypothetically a surface solid solution of CuO in an NiO matrix, which due to migration of copper oxide

  1. Occasional ``long-range'' nonequilibrium body-centered-cubic structures in NiFe/Cu spin valves

    E-print Network

    Lederman, David

    characterization of the microstructure of sputtered NiFe/Cu giant magnetoresistance spin valves Cu/FeMn for fcc Cu, FeMn, and NiFe spin-valve components . This epitaxial growth yields an apparent Kurdjumov Fourier transform analysis reveals that in some of the columnar grains the Cu, FeMn, and NiFe layers take

  2. Comparison of Sn-Ag-Cu Solder Alloy Intermetallic Compound Growth Under Different Thermal Excursions for Fine-Pitch Flip-Chip Assemblies

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Liu, Xi; Chow, Justin; Wu, Yi Ping; Sitaraman, Suresh K.

    2013-08-01

    The intermetallic compound (IMC) evolution in Cu pad/Sn-Ag-Cu solder interface and Sn-Ag-Cu solder/Ni pad interface was investigated using thermal shock experiments with 100- ?m-pitch flip-chip assemblies. The experiments show that low standoff height of solder joints and high thermomechanical stress play a great role in the interfacial IMC microstructure evolution under thermal shock, and strong cross-reaction of pad metallurgies is evident in the intermetallic growth. Furthermore, by comparing the IMC growth during thermal aging and thermal shock, it was found that thermal shock accelerates IMC growth and that kinetic models based on thermal aging experiments underpredict IMC growth in thermal shock experiments. Therefore, new diffusion kinetic parameters were determined for the growth of (Cu,Ni)6Sn5 using thermal shock experiments, and the Cu diffusion coefficient through the IMC layer was calculated to be 0.2028 ?m2/h under thermal shock. Finite-element models also show that the solder stresses are higher under thermal shock, which could explain why the IMC growth is faster and greater under thermal shock cycling as opposed to thermal aging.

  3. Surface and catalytic properties of Co, Ni and Cu binary oxide systems

    Microsoft Academic Search

    H. G. El-Shobaky

    2004-01-01

    NiO\\/CuO, CuO\\/NiO, Co3O4\\/NiO, NiO\\/Co3O4, CuO\\/Co3O4 and Co3O4\\/CuO systems having equimolar ratios of transition metal oxides were prepared. These solids were obtained by wet impregnation method using the corresponding nitrates and carbonate salts followed by calcination at 300–750°C. The crystalline phases produced at different calcination temperatures were characterized by XRD investigation. The surface and catalytic properties of the calcined products of

  4. Fracture of Sn-Ag-Cu Solder Joints on Cu Substrates. II: Fracture Mechanism Map

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Huang, Z.; Dutta, I.; Sidhu, R.; Renavikar, M.; Mahajan, R.

    2012-02-01

    A methodology to construct fracture mechanism maps for Sn-3.8%Ag-0.7%Cu (SAC387) solder joints attached to Cu substrates has been developed. The map, which delineates the operative mechanisms of fracture along with corresponding joint fracture toughness values, is plotted in a space described by two microstructure-dependent parameters, with the abscissa describing the interfacial intermetallic compound (IMC) and the ordinate representing the strain-rate-dependent solder yield strength. The plot space encompasses the three major mechanisms by which joints fail, namely (i) cohesive fracture of solder, (ii) cleavage fracture of interfacial intermetallic compounds (IMC), and (iii) fracture of the solder-IMC interface. Line contours of constant fracture toughness values, as well as constant fraction of each of the above mechanisms, are indicated on the plots. The plots are generated by experimentally quantifying the dependence of the operative fracture mechanism(s) on the two microstructure-dependent parameters (IMC geometry and solder yield strength) as functions of strain rate, reflow parameters, and post-reflow aging. Separate maps are presented for nominally mode I and equi-mixed mode loading conditions (loading angle ? = 0° and 45°, respectively). The maps allow rapid assessment of the operative fracture mechanism(s) along with estimation of the expected joint fracture toughness value for a given loading condition (strain rate and loading angle) and joint microstructure without conducting actual tests, and may serve as a tool for both prediction and microstructure design.

  5. High-temperature internal oxidation of Ag/1.2at.% Mg and Ag/0.25at.% Mg-0.25at.% Ni.

    SciTech Connect

    Balachandran, U.; Goretta, K. C.; McNallan, M. J.; Park, J.-H.; Prorok, B. C.

    1999-09-08

    High-temperature oxygen diffusion and internal oxidation in Ag, Ag/1.2 at.% Mg (Ag-Mg), and Ag/0.25 at.% Mg-0.25 at.% Ni (Ag-Mg-Ni) have been studied, mostly in air and 8% O{sub 2}, at 450-835 C. The focus of the studies was on thermogravimetric analysis, microhardness tests, and optical and electron microscopy observations of grain growth and its inhibition by oxidation. The internal oxidation of both alloys exhibited nearly identical activation energies (0.81 eV for Ag-Mg and 0.83 eV for Ag-Mg-Ni) and rate constants. The maximum O content of both alloys was superstoichiometric (e.g., O/Mg > 1.0) and the maximum O/Mg ratios were higher at lower temperatures than at higher temperatures (e.g., 1.25 at 500 C and 1.05 at 800 C). Diffusion of O in pure Ag was {approx}60 times faster at 825 C and {approx}400 times faster at 500 C than internal oxidation of either of the Ag alloys. Grain growth of both alloys and of the Ag was quantified between 450-800 C and related to internal oxidation.

  6. Ferromagnetic resonance in compositionally modulated Cu-Ni thin films

    NASA Astrophysics Data System (ADS)

    Dillon, J. F., Jr.; Gyorgy, E. M.; Rupp, L. W., Jr.; Yafet, Y.; Testardi, L. R.

    1981-03-01

    Ferromagnetic resonance at 12 GHz has been studied in some of the same compositionally modulated CuNi films on which magnetization measurements were reported recently. The best samples, e.g., a film designated [20?10]880 (i.e, 880 repetitions of [20Å Cu on 10Å Ni]) show the 295 K resonance behavior expected for a magnetic material with an easy plane uniaxial anisotropy and a line width ?H˜103 Oe. As T is lowered the quantity Drf.?4?M+2K/M extracted from the line position data using Kittel's equations increases roughly linearly with decreasing T. For [10?10] 2440, Drf goes from ˜4 kOe at 295 K to ˜20 kOe at 80 K. This low temperature value agrees with that obtained from He temperature magnetization curves. A remarkable result of the magnetization measurements was the fact that Ddc at 4.2 K was essentially the same for [10?10], [20?10], and [40?10] samples. In striking contrast, the microwave values at 80 K decrease markedly with increasing thickness of the Cu layers. Simple averaging of the resonance equations has not led to an explanation of this difference.

  7. Enhanced photocatalytic performance of sandwiched ZnO@Ag@Cu2O nanorod films: the distinct role of Ag NPs in the visible light and UV region

    NASA Astrophysics Data System (ADS)

    Ren, Shoutian; Zhao, Guoliang; Wang, Yingying; Wang, Benyang; Wang, Qiang

    2015-03-01

    Sandwiched ZnO@Ag@Cu2O nanorod films were synthesized by successive electrodeposition, magnetron sputtering and the second electrodeposition. The as-synthesized composites were characterized by x-ray diffraction patterns, field emission scanning electron microscopy, low- and high-resolution transmission electron microscopy and a UV–vis spectrophotometer. Their photocatalytic performance was estimated by the degradation of a methyl orange solution under UV or visible-light irradiation, respectively. In the visible region, due to localized surface plasmon resonance absorption of Ag NPs, ZnO@Ag@Cu2O showed a significantly enhanced photocatalytic performance. The enhancement factor of Ag NPs on the catalytic performance of ZnO@Ag@Cu2O was estimated as a function of the Cu2O deposition time, and the corresponding enhancement mechanism was also evaluated by the monochromatic photocatalytic experiment and discrete dipole approximation simulation. In the UV region, due to the formation of a Schottky junction (e.g. Ag/ZnO, Ag/Cu2O), a limited enhanced photocatalytic performance was also realized for ZnO@Ag@Cu2O photocatalysts.

  8. Enhanced photocatalytic performance of sandwiched ZnO@Ag@Cu?O nanorod films: the distinct role of Ag NPs in the visible light and UV region.

    PubMed

    Ren, Shoutian; Zhao, Guoliang; Wang, Yingying; Wang, Benyang; Wang, Qiang

    2015-03-27

    Sandwiched ZnO@Ag@Cu2O nanorod films were synthesized by successive electrodeposition, magnetron sputtering and the second electrodeposition. The as-synthesized composites were characterized by x-ray diffraction patterns, field emission scanning electron microscopy, low- and high-resolution transmission electron microscopy and a UV-vis spectrophotometer. Their photocatalytic performance was estimated by the degradation of a methyl orange solution under UV or visible-light irradiation, respectively. In the visible region, due to localized surface plasmon resonance absorption of Ag NPs, ZnO@Ag@Cu2O showed a significantly enhanced photocatalytic performance. The enhancement factor of Ag NPs on the catalytic performance of ZnO@Ag@Cu2O was estimated as a function of the Cu2O deposition time, and the corresponding enhancement mechanism was also evaluated by the monochromatic photocatalytic experiment and discrete dipole approximation simulation. In the UV region, due to the formation of a Schottky junction (e.g. Ag/ZnO, Ag/Cu2O), a limited enhanced photocatalytic performance was also realized for ZnO@Ag@Cu2O photocatalysts. PMID:25742195

  9. VARIATION DE L'NERGIE D'ANISOTROPIE MAGNTIQUE DU Ni ET DES ALLIAGES Ni-Cu, EN FONCTION DE LA TEMPRATURE

    E-print Network

    Boyer, Edmond

    5 VARIATION DE L'ÉNERGIE D'ANISOTROPIE MAGNÉTIQUE DU Ni ET DES ALLIAGES Ni-Cu, EN FONCTION DE LA théorie de la variation de l'énergie d'anisotropie magnétique du Ni et des alliages Ni-Cu en fonction de et des alliages Ni-Cu. L'énergie d'anisotropie Ek d'un cristal magné- tique s'exprime habituellement

  10. Improvement on the microstructure stability, mechanical and wetting properties of Sn–Ag–Cu lead-free solder with the addition of rare earth elements

    Microsoft Academic Search

    D. Q Yu; J Zhao; L Wang

    2004-01-01

    Ternary lead-free solder alloys Sn–Ag–Cu were considered as the potential alternatives to lead–tin alloys comparing with other solders. In this paper, microstructure and mechanical properties of Sn–2.5Ag–0.7Cu, Sn–3.5Ag–0.7Cu, Sn–3.5Ag–0.7Cu–0.1RE, and Sn–3.5Ag–0.7Cu–0.25RE alloys were researched. Coarse ?-Sn grains were formed in Sn–2.5Ag–0.7Cu and Sn–3.5Ag–0.7Cu alloys and bulky Ag3Sn intermetallics were found in Sn–3.5Ag–0.7Cu alloy. With the addition of trace rare earth

  11. On the influence of non-protective CuO on high-temperature oxidation of Cu-rich Cu-Ni based alloys

    SciTech Connect

    Haugsrud, R. [Univ. of Oslo (Norway)] [Univ. of Oslo (Norway)

    1999-12-01

    A number of copper-rich Cu-Ni alloys were oxidized from 750 to 1,000 C at different oxygen pressures. The oxide scales formed consist of an outer copper oxide layer and an inner porous layer where internal oxide-derived NiO particles are dispersed in a copper oxide matrix. The copper oxide may be both single-phase CuO and a two-phase (CuO + Cu{sub 2}O). At the lower part of the temperature range, the oxidation kinetics and oxide morphology depend strongly upon the formation of CuO. The CuO layer is nonprotective and further oxidation of Cu{sub 2}O, forming CuO, therefore changes the oxidation from being approximately parabolic to having a breakaway-like behavior. The relative thickness of nonprotective CuO increases with increasing NiO and reflects that the solid-state flux of copper across the Cu{sub 2}O decreases due to a barrier effect of the NiO particles and porosity in the oxide and NiO particles in the alloy. The beneficial effect of Ni in reducing the oxidation rate is lost due to the extensive formation of nonprotective CuO.

  12. Shape effect of Ag-Ni binary nanoparticles on catalytic hydrogenation aided by surface plasmons.

    PubMed

    Kim, Chanyeon; Kwon, Yongwoo; Lee, Hyunjoo

    2015-07-16

    Ag-Ni binary nanoparticles with different shapes (snowman and core-shell) were synthesized by modulating the lattice strain. In the catalytic hydrogenation of 4-nitrophenol, a significant enhancement of the reaction rate was observed for the snowman shape in comparison with the core-shell shape under light irradiation. PMID:26138663

  13. Dependence of the coercive field on the Cu overlayer thickness in thin Co/Cu(001) and Ni/Cu(001) fcc epitaxial films

    SciTech Connect

    Vaz, C. A. F.; Bland, J. A. C.

    2001-06-01

    We have studied the effect of the Cu overlayer thickness t{sup Cu} on the coercive field H{sub c} of epitaxial ultrathin fcc Co/Cu(001) and Ni/Cu(001) films by magneto-optic Kerr effect magnetometry. The Cu/40 Aa Ni/Cu(001) system shows perpendicular magnetic anisotropy (PMA) for the whole t{sup Cu} range studied (20{endash}180 Aa) with H{sub c} showing a large, linear increase with t{sup Cu} (from {similar_to}280 to {similar_to}360 Oe). On the other hand, the Cu/36 Aa Co/Cu(001) structure has dominant in-plane anisotropy and in contradistinction with the Ni case the coercive field decreases rapidly with t{sup Cu} (from 140 Oe for t{sup Cu}=20Aa to {similar_to}90 Oe at t{sup Cu}{similar_to}180Aa). The variation in coercivity is described in terms of the magnetoelastic energy contribution to the magnetic anisotropy induced by the Cu overlayers (via strain). In particular, the increase in the H{sub c} of Ni is attributed to an increase in the PMA while the relation between the magnetic anisotropy and coercivity in the case of Co remains unclear. {copyright} 2001 American Institute of Physics.

  14. Magnetic anisotropy in epitaxial Py/FeMn/Cu(001) and Py/FeMn/Ni/Cu(001) films

    NASA Astrophysics Data System (ADS)

    Tan, A.; Li, J.; Jenkins, C. A.; Arenholz, E.; Scholl, A.; Hwang, C.; Qiu, Z. Q.

    2013-09-01

    Py/FeMn/Cu(001) and Py/FeMn/Ni/Cu(001) films were grown and studied as a function of both the FeMn and the Ni thicknesses using rotating magneto-optic Kerr effect and x-ray magnetic circular dichroism. For Py/FeMn/Cu(001), we find that the FeMn antiferromagnetic order switches the sign of the Py fourfold magnetic anisotropy but has little effect on the step-induced uniaxial magnetic anisotropy. For Py/FeMn/Ni/Cu(001), we find that out-of-plane Ni magnetization has little effect on the Py magnetic anisotropy, but in-plane Ni magnetization enhances the Py magnetic anisotropy in the region just above antiferromagnetic transition thickness. The underlying mechanism could be attributed to the FeMn 3Q spin structure.

  15. The influence of Ni additions on the relative stability of ? and ?' Cu6Sn5

    NASA Astrophysics Data System (ADS)

    Schwingenschlögl, U.; Di Paola, C.; Nogita, K.; Gourlay, C. M.

    2010-02-01

    We investigate how 5 at. % Ni influences the relative stability of ? and ?' Cu6Sn5. Synchrotron x-ray diffraction shows that, while Cu6Sn5 exists as ?' at 25 and 150 °C and transforms to ? on heating to 200 °C, Cu5.5Ni0.5Sn5 is best fit to ? throughout 25-200 °C. Our first principles calculations predict that ?' is stable at T =0 K in both Cu6Sn5 and Cu5.5Ni0.5Sn5, but that the energy difference is substantially reduced from 1.21 to 0.90 eV per 22 atom cell by the Ni addition. This effect is attributed to Ni developing distinct bonding to both Cu and Sn in the ? phase.

  16. Tunable synthesis of hierarchical NiCo2O4 nanosheets-decorated Cu/CuOx nanowires architectures for asymmetric electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Kuang, Min; Zhang, Yu Xin; Li, Tong Tao; Li, Kai Feng; Zhang, Sheng Mao; Li, Gang; Zhang, Wei

    2015-06-01

    We demonstrate a facile and tunable preparative strategy of porous NiCo2O4 nanosheets-decorated Cu-based nanowires hybrids as high-performance supercapacitor electrodes. A fast faradic reaction has been realized by inducing elementary copper core in the composite, which assists in high electric conductivity of the cell and creates intimate channels for fast charge collection and electron transfer. As a result, this hybrid composite electrode displays high specific capacitance (578 F g-1 at current density of 1.0 A g-1) and rate capability (80.1% capacitance retention from 1 A g-1 to 10 A g-1). Additionally, asymmetric device is constructed from NiCo2O4/Cu-based NWs and activated graphene (AG) with an operation potential from 0 to 1.4 V. The asymmetric device exhibits an energy density of 12.6 Wh kg-1 at a power density of 344 W kg-1 and excellent long-term cycling stability (only 1.8% loss of its initial capacitance after 10,000 cycles). These attractive findings suggest that such unique NiCo2O4/Cu-based NWs hybrid architecture is promising for electrochemical applications as efficient electrode material.

  17. Nanostructured YbAgCu4 for potential cryogenic thermoelectric cooling

    NASA Astrophysics Data System (ADS)

    Koirala, Machhindra; Wang, Hui; Pokharel, Mani; Opeil, Cyril; Ren, Zhifeng

    2015-03-01

    We have studied thermoelectric properties of nanostructured YbAgCu4 for cryogenic temperature range. Nanostructured YbAgCu4 has been prepared using arc melting method followed by ball milling and hot pressing process. Thermal conductivity of the nanostructured samples has been reduced at 42 K by 30-50 % compared to the previously reported value. A high power factor of 131 ?W m-1 K-2 has been obtained at 22 K. A peak dimensionless figure of merit ZT of 0.11 has been achieved at 42 K. With the variation of Cu-Ag composition, the temperature of peak ZT can be tuned, which could be useful for the preparation of segmented legs. The method of nanostructuring can be implemented with different heavy fermions for obtaining high power factor with reduced thermal conductivity.

  18. Plasmon-exciton induced transparency in plexcitonic Ag-CuCl-coated nanowires and associated arrays

    NASA Astrophysics Data System (ADS)

    Jiang, ShuMin; Xie, QiuYue; Wu, DaJian

    2015-05-01

    The plasmon-exciton couplings in Ag-CuCl-coated nanowires (ACNWs) have been investigated by using the scattering theory and the finite element method. It is found with increasing the shell thickness that the dipole plasmon resonance of the Ag nanowire can be tuned through the exciton resonance in the CuCl shell. The strong coupling between the plasmon resonance in the Ag nanowire and the exciton resonance in the CuCl shell leads to two new hybridized plexcitonic modes. The dispersion curves of the plexcitonic modes in the ACNWs are studied, and the obtained splitting energy is about 88 meV. We further find that the destructive interference between the plasmon and exciton resonances results in the plasmon-exciton induced transparency. As the TE wave propagates through the ACNW array, an extraordinary transmittance can be found in the ACNW array at the scattering dip of the ACNW.

  19. CAPILLARY PRESSURE AND PHONONS IN Ag, Au, Cu AND Ni

    E-print Network

    Duisburg-Essen, Universität

    of attention by materials scientists ­ see e.g. Science 271, no. 5271 (1996). Due to their high surface of the particle and is the surface stress. While in the case of a liquid, the surface stress is isotropic. In this case the surface stress becomes anisotropic and it is no longer equal to the surface tension (Nozi

  20. NMR study of Cu2Se and Cu1.98Ag0.2Se superionic conductors

    NASA Astrophysics Data System (ADS)

    Sirusi Arvij, Ali; Ross, Joseph H., Jr.; Ballikaya, Sedat; Uher, Ctirad

    2015-03-01

    Cu2Se and Cu1.98Ag0.2Se are well known as superionic conductors and recently as thermoelectric materials due to observation of high ZT. We will report NMR of these compounds. Our results include indications of glassy anharmonic behavior at low temperatures, Cu ionic motion which becomes initiated near 90K, and motional narrowing near the phase transition at high temperatures as well as modified dynamics observed in the Ag-doped sample. NMR is particularly well suited to probe low frequency dynamics and at low temperatures the relaxation rate indicates anharmonic rattling behavior similar to what has been observed in other thermoelectric materials. A 90K change in the NMR spectra corresponds to the recently observed transport anomaly and indicates that the slow motion of Cu ions is initiated at this temperature and eventually becomes liquid-like at higher temperatures. We detect fast ionic motion in Cu2Se starting at 140K whereas in the Ag-doped compound this onset shifts to a higher temperature around 300K. At high temperatures the spectra become motionally narrowed, and we will discuss the narrowing and shifts in terms of activated carrier density and ionic motion. This work was supported by the Robert A. Welch Foundation.

  1. ? hyperons in 2 A GeV Ni + Cu collisions

    NASA Astrophysics Data System (ADS)

    EOS Collaboration; Justice, M.; Albergo, S.; Bieser, F.; Brady, F. P.; Caccia, Z.; Cebra, D. A.; Chacon, A. D.; Chance, J. L.; Choi, Y.; Costa, S.; Elliott, J. B.; Gilkes, M. L.; Hauger, J. A.; Hirsch, A. S.; Hjort, E. L.; Insolia, A.; Keane, D.; Kintner, J. C.; Lisa, M. A.; Liu, H.; Matis, H. S.; McGrath, R.; McMahan, M.; McParland, C.; Olson, D. L.; Partlan, M. D.; Porile, N. T.; Potenza, R.; Rai, G.; Rasmussen, J. O.; Ritter, H. G.; Romanski, J.; Romero, J. L.; Russo, G. V.; Scharenberg, R. P.; Scott, E. A.; Shao, Y.; Srivastava, B. K.; Symons, T. J. M.; Tincknell, M.; Tuvè, C.; Wang, S.; Warren, P. G.; Weerasundara, D.; Wieman, H. H.; Wienold, T.; Wolf, K.

    1998-11-01

    A sample of ?'s produced in 2 A GeV 58Ni + natCu collisions has been obtained with the EOS Time Projection Chamber at the Bevalac. Low background in the invariant mass distribution allows for the unambiguous demonstration of ? directed flow. The ? mT spectrum at mid-rapidity has the characteristic shoulder-arm shape of particles undergoing radial transverse expansion. A linear dependence of ? multiplicity on impact parameter is observed, from which a total ?+?0 production cross section of 112+/-24 mb is deduced. Detailed comparisons with the ARC and RVUU models are made.

  2. 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.

  3. 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 ? 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 ? 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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06246e

  4. An embedded-atom potential for the Cu–Ag system

    Microsoft Academic Search

    P L Williams; Y Mishin; J C Hamilton

    2006-01-01

    A new embedded-atom method (EAM) potential has been constructed for Ag by fitting to experimental and first-principles data. The potential accurately reproduces the lattice parameter, cohesive energy, elastic constants, phonon frequencies, thermal expansion, lattice-defect energies, as well as energies of alternate structures of Ag. Combining this potential with an existing EAM potential for Cu, a binary potential set for the

  5. Giant Magnetoresistance at Low Fields in Discontinuous NiFe-Ag Multilayer Thin Films.

    PubMed

    Hylton, T L; Coffey, K R; Parker, M A; Howard, J K

    1993-08-20

    A series of sputtered multilayers of Ni(80)Fe(20)-Ag was prepared to examine the giant magnetoresistance effect before and after annealing. For a wide range of NiFe and Ag thicknesses, no giant magnetoresistance was observed in the unannealed films. After annealing, a large, negative magnetoresistance was observed of order 4 to 6% in applied fields of order 5 to 10 oersteds at room temperature. The appearance of giant managetoresistance is concurrent with the breakup of the NiFe layers, which is attributable to a magnetostatic interaction that favors local antiparallel alignment of the moments in adjacent layers. These structures may be of significant practical importance as sensors that require large changes in resistance at low fields, such as magnetoresistive heads used in magnetic recording systems. PMID:17739621

  6. Surface phase interactions in the NiO-CuO system from electrical conductivity data

    SciTech Connect

    Dulov, A.A.; Abramova, L.A.; Golosman, E.Z.; Efremov, V.N.; Yakerson, V.I.

    1988-12-01

    Using the thermovacuum electrical conductivity (TVC) curve method, we have shown that in the NiO-CuO system obtained from metal hydroxocarbonates, for a CuO content of 5 wt % heat treatment at 400/degrees/C in air leads to formation of an NiO type phase, hypothetically a surface solid solution of CuO in an NiO matrix, which due to migration of copper oxide to the surface at 600/degrees/C is transformed to a CuO type phase (a solid solution of NiO in a CuO matrix). When the CuO content in the system is raised to 23%, a heating temperature of 400/degrees/C proves to be enough to form the CuO-based solid solution. For pure oxides and solid solutions, we observe the effect of anionic modification, due to residual carbonates and leading to stabilization of the phases.

  7. Martensitic transformation behavior in Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys

    SciTech Connect

    Jang, Jai-young; Chun, Su-jin; Kim, Nam-suk; Cho, Jeung-won; Kim, Jae-hyun [School of Materials Science and Engineering, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Yeom, Jong-taek [Light Metal Division, Korea Institute of Materials Science (KIMS), Changwon 642-831 (Korea, Republic of); Kim, Jae-il [Materials Science and Engineering, University of Dong-A, Hadan-dong, Saha-gu, Busan 604-714 (Korea, Republic of); Nam, Tae-hyun, E-mail: tahynam@gnu.ac.kr [School of Materials Science and Engineering, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

    2013-12-15

    Graphical abstract: - Highlights: • Ag, In and Sn were soluble in TiNi matrix, while Sb, Te, Tl, Pb and Bi were not. • The B2-R-B19?transformation occurred in Ti-Ni-(Ag, In, Sn) alloys. • Solid solution hardening was essential for inducing the B2-R transformation. - Abstract: The microstructures and transformation behaviors of Ti–Ni–X (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys were investigated using electron probe micro-analysis (EPMA), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Micro Vickers hardness tests. All specimens consisted of Ti–Ni matrices and second phase particles. Ag, In and Sn were soluble in Ti–Ni matrices with a limited solubility (?1.0 at%), while Sb, Te, Tl, Pb and Bi were not soluble. Two-stage B2-R-B19? transformation occurred in Ti–48.8Ni–1.2Ag, Ti–49.0Ni–1.0In and Ti–49.0Ni–1.0Sn alloys, while one-stage B2-B19? transformation occurred in Ti–49.0Ni–1.0Ag, Ti–49.0Ni–1.0Sb, Ti–49.0Ni–1.0Te, Ti–49.0Ni–1.0Pb and Ti–49.0Ni–1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19? transformation (Hv 250–368) was much larger than that (Ni–X (X = non-transition elements) alloys.

  8. Formation of Intermetallics in Sn-0.9Cu and Sn-0.7Cu-0.08Ni Solders

    NASA Astrophysics Data System (ADS)

    Ventura, Tina; Cho, Young-Hee; Kong, Chun; Dahle, Arne K.

    2011-06-01

    A study of the crystallography and composition of the constituent intermetallics in a binary eutectic Sn-0.9Cu and a ternary Sn-0.7Cu-0.08Ni solder alloy was carried out by systematic transmission electron microscopy. The results are analyzed and discussed in relation to the phase diagrams available in the literature. The intermetallic phases formed at different stages during solidification are present in different sizes and morphologies and also appear to exhibit different crystallographic properties and composition. The fine eutectic intermetallic in the Ni-containing alloy could not be matched with any of the known intermetallics in the ternary Sn-Cu-Ni system.

  9. Thermophysical Properties of Sn-Ag-Cu Based Pb-Free Solders

    NASA Astrophysics Data System (ADS)

    Kim, Sok Won; Lee, Jaeran; Jeon, Bo-Min; Jung, Eun; Lee, Sang Hyun; Kang, Kweon Ho; Lim, Kwon Taek

    2009-06-01

    Lead-tin (Pb-Sn) alloys are the dominant solders used for electronic packaging because of their low cost and superior properties required for interconnecting electronic components. However, increasing environmental and health concerns over the toxicity of lead, combined with global legislation to limit the use of Pb in manufactured products, have led to extensive research and development studies of lead-free solders. The Sn-Ag-Cu ternary eutectic alloy is considered to be one of the promising alternatives. Except for thermal properties, much research on several properties of Sn-Ag-Cu alloy has been performed. In this study, five Sn-xAg-0.5Cu alloys with variations of Ag content x of 1.0 mass%, 2.5 mass%, 3.0 mass%, 3.5 mass%, and 4.0 mass% were prepared, and their thermal diffusivity and specific heat were measured from room temperature to 150 °C, and the thermal conductivity was calculated using the measured thermal diffusivity, specific heat, and density values. Also, the linear thermal expansion was measured from room temperature to 170 °C. The results show that Sn-3.5Ag-0.5Cu is the best candidate because it has a maximum thermal conductivity and a low thermal expansion, which are the ideal conditions to be a proper packaging alloy for effective cooling and thermostability.

  10. Details on the Formation of Ti 2 Cu 3 in the Ag-Cu-Ti System in the Temperature Range 790 to 860 °C

    Microsoft Academic Search

    J. Andrieux; O. Dezellus; F. Bosselet; M. Sacerdote-Peronnet; C. Sigala; R. Chiriac; J. C. Viala

    2008-01-01

    Silver-copper-titanium (Ag-Cu-Ti) ternary alloys are often used as active braze alloys for joining ceramics to metals at temperatures\\u000a ranging from 780 °C (the melting point of the Ag-Cu eutectic) up to 900 °C. When Ti\\/Ag-Cu joints are brazed at low temperature\\u000a (near 800 °C), the intermetallic compound Ti2Cu3 (tetragonal, P4\\/nmm, a = 0.313 nm, c = 1.395 nm) is systematically missing from the interface reaction layer sequence. An experimental

  11. Room temperature solid-state transformation from Ag{sub 2}Cu{sub 2}O{sub 3} to Ag{sub 2}Cu{sub 2}O{sub 4} by ozone oxidation

    SciTech Connect

    Munoz-Rojas, D. [Institut de Ciencia de Materials (CSIC), Campus UAB, Bellaterra 08193 (Spain); Fraxedas, J. [Institut de Ciencia de Materials (CSIC), Campus UAB, Bellaterra 08193 (Spain); Gomez-Romero, P. [Institut de Ciencia de Materials (CSIC), Campus UAB, Bellaterra 08193 (Spain); Casan-Pastor, N. [Institut de Ciencia de Materials (CSIC), Campus UAB, Bellaterra 08193 (Spain)]. E-mail: nieves@icmab.es

    2005-01-15

    The mixed silver-copper oxide, Ag{sub 2}Cu{sub 2}O{sub 4} has been previously synthesized by electrochemical oxidation of suspensions of the precursor Ag{sub 2}Cu{sub 2}O{sub 3} and also by direct oxidation/coprecipitation of soluble salts. This work shows how the transformation from Ag{sub 2}Cu{sub 2}O{sub 3} to Ag{sub 2}Cu{sub 2}O{sub 4} can take place in solid state at room temperature by ozonization of the precursor. The final phase is overstoichiometric in oxygen but shows the same structural features of the firstly described phase Ag{sub 2}Cu{sub 2}O{sub 4}. The maximum content of oxygen achieved is 4.34 per unit formula.

  12. Crystallization Behavior and Corrosion Resistance of Cu 50 Zr 40 Ag 10 Amorphous Alloy

    Microsoft Academic Search

    Cancan LiYan; Yan Wang; Haoran Geng

    In this study, Cu50Zr40Ag10 amorphous alloy ribbons were prepared by a single roller melt-spinning method. The crystallization behavior of the Cu50Zr40Ag10 amorphous alloy has been investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC), transmission\\u000a electron microscopy (TEM) and high resolution TEM (HRTEM). Moreover, the polarization and passivation behaviors of the as-quenched\\u000a and as-annealed amorphous alloy have been studied in

  13. Properties of lead-free solder SnAgCu containing minute amounts of rare earth

    Microsoft Academic Search

    Zhigang Chen; Yaowu Shi; Zhidong Xia; Yanfu Yan

    2003-01-01

    Because of excellent wetting and mechanical properties, SnAgCu solder alloys have been regarded as the most promising Pb-free\\u000a substitutes for the SnPb solder. The Sn-3.8Ag-0.7Cu solder has garnered attention because of its creep resistance. However,\\u000a under the drives of increasingly finer pitch design and severe service conditions, novel lead-free solders with higher creep\\u000a performance may be needed. Adding a surface-active

  14. Compositional characterization of Cu-rich phase particles present in as-cast Al-Cu-Mg(-Li) alloys containing Ag

    SciTech Connect

    Mukhopadhyay, A.K. [Defence Metallurgical Research Lab., Hyderabad (India)

    1999-07-01

    The effects of small additions of Ag on the aging of wrought Al-Cu-Mg(-Li) alloys, involving widespread nucleation of Cu-rich {Omega} (and T{sub 1}) phase precipitates, are known. This article examines the influence of small additions of Ag on the nature of Cu-rich {theta}-Al{sub 2}Cu, S-Al{sub 2}CuMg, and T{sub 1}-Al{sub 2}CuLi phases present in appropriate as-cast Al-Cu, Al-Cu-Mg, and Al-Cu-Li-Mg alloys. Using a combination of light microscopy, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA), it is shown that neither independent nor combined additions of Ag and Mg to the binary Al-Cu alloy after the composition of the {theta} phase; however, there are differences in the ways the {theta} phase is evolved in Al-Cu-Mg alloys with and without Ag. Ag additions to the Al-Cu-Mg alloy result in the formation of an Al-Cu-Mg-based ternary phase, having a Cu content similar to that of the {theta} phase and containing small amounts of Mg; rapid rates of cooling cause the retention of this phase in the as-cast alloy. Relatively large amounts of both Ag and Mg are always located in the peripheral regions of such a phase. This phase is readily replaced by {theta} phase upon annealing at 450 C. The S phase of the ternary Al-Cu-Mg system is identified in this alloy and is found to dissolve small amounts of Ag. In the case of the Al-Cu-Li-Mg-Ag alloy, two major changes are observed; both Ag and Mg are always present in relatively large amounts in the peripheral regions of the T{sub 1} phase, and the S-phase particles are once again found to dissolve small amounts of Ag. These results are discussed in light of the known compositional features of the precipitates formed in the artificially aged Al-Cu-Mg(-Li)-Ag alloys, to reveal that examination of phases present in the as-cast microstructure is a contributory step toward determining the locations of trace alloy additions in the phase precipitates of interest.

  15. Global optimization and oxygen dissociation on polyicosahedral Ag32Cu6 core-shell cluster for alkaline fuel cells

    PubMed Central

    Zhang, N.; Chen, F. Y.; Wu, X.Q.

    2015-01-01

    The structure of 38 atoms Ag-Cu cluster is studied by using a combination of a genetic algorithm global optimization technique and density functional theory (DFT) calculations. It is demonstrated that the truncated octahedral (TO) Ag32Cu6 core-shell cluster is less stable than the polyicosahedral (pIh) Ag32Cu6 core-shell cluster from the atomistic models and the DFT calculation shows an agreeable result, so the newfound pIh Ag32Cu6 core-shell cluster is further investigated for potential application for O2 dissociation in oxygen reduction reaction (ORR). The activation energy barrier for the O2 dissociation on pIh Ag32Cu6 core-shell cluster is 0.715?eV, where the d-band center is ?3.395?eV and the density of states at the Fermi energy level is maximal for the favorable absorption site, indicating that the catalytic activity is attributed to a maximal charge transfer between an oxygen molecule and the pIh Ag32Cu6 core-shell cluster. This work revises the earlier idea that Ag32Cu6 core-shell nanoparticles are not suitable as ORR catalysts and confirms that Ag-Cu nanoalloy is a potential candidate to substitute noble Pt-based catalyst in alkaline fuel cells. PMID:26148904

  16. Neutron diffraction determination of the nuclear spin ordering in Cu and Ag at nano- and subnano-K temperatures (invited)

    Microsoft Academic Search

    M. Steiner; A. Metz; K. Siemensmeyer; O. V. Lounasmaa; J. T. Tuoriniemi; K. K. Nummila; R. T. Vuorinen; K. N. Clausen; K. Lefmann; F. B. Rasmussen

    1996-01-01

    The spontaneous nuclear spin ordering in the simple diamagnetic metals Cu and Ag has been studied by neutron diffraction using the spin dependent part of the nuclear cross section. Simple antiferromagnetic ordering of type I has been found in zero field for these fcc-systems below 60 and 560 pK for Cu and Ag, respectively. The ordering in an applied field

  17. Density functional theory studies of sulfur binding on Pd, Cu and Ag and their alloys

    NASA Astrophysics Data System (ADS)

    Alfonso, Dominic R.; Cugini, Anthony V.; Sholl, David S.

    2003-11-01

    We present gradient corrected density functional theory calculations on the adsorption of sulfur on pure Pd(1 1 1), Cu(1 1 1) and Ag(1 1 1) surfaces as well as on PdCu 3(1 1 1), Pd 3Cu(1 1 1), PdCu(1 1 0), PdAg 3(1 1 1) and Pd 3Ag(1 1 1) surfaces. Sulfur forms strong bonds with all the surfaces and favors hollow sites in every case. The binding energies on the pure metals show considerable variation and follow the trend: E bind( Pd(1 1 1))>E bind( Cu(1 1 1))>E bind( Ag(1 1 1)) . On the alloy surfaces, the adsorption energies in general are weaker in comparison to adsorption on the Pd(1 1 1) surface but the reduction in binding is not large. The strong interaction of sulfur with these surfaces arises from rehybridization of the p-states of the adsorbate with the substrate sp- and d-bands. We confirm that there is nearly a linear correlation between the binding energies of S on similar adsorption sites and the d-band center of surface atoms whose structure remain close to their bulk-truncated position.

  18. Photoemission study of the Bi 2CaSr 2Cu 2O 8 superconductor with Cu, Ag and Au overlayers

    NASA Astrophysics Data System (ADS)

    Bernhoff, H.; Qvarford, M.; Söderholm, S.; Nyholm, R.; Karlsson, U. O.; Lindau, I.; Flodström, A. S.

    1993-12-01

    In this paper, we present a photoemission study of the interaction of Cu, Ag and Au with clean single-crystal Bi 2CaSr 2Cu 2O 8 superconductor surfaces. Both the valence-band and the Bi 5d, O 1s and Sr 3d core levels were monitored for all overlayers. Cu, Ag and Au were deposited as consecutively thicker layers starting with a third of a monolayer and progressing in steps up to a deposition in the range of eight monolayers. Comparing the results for the different overlayers reveals the Ag overlayers to be less reactive than Au which causes the formation of metallic Bi on cleaved Bi 2CaSr 2Cu 2O 8 surface. Cu is shown to be the most reactive of the three metals. The Au and Ag overlayers display an island-growth mode, while Cu grows in a layer-by-layer fashion.

  19. Relationships between mechanical strength and electrical conductivity for Cu Ag filamentary microcomposites

    NASA Astrophysics Data System (ADS)

    Liu, J. B.; Zhang, L.; Meng, L.

    2007-03-01

    Cu Ag filamentary microcomposites with various Ag contents, alloying additions and ingot annealing processes were prepared by vacuum casting and cold drawing. The strength and conductivity were measured at different drawing strain degrees. High conductivity tends to connect to low strength for the microcomposites with different Ag content, alloying addition and annealing process. Increasing Ag concentration, adding constituents Zr and Cr, or using low ingot annealing temperature can improve the strength but impair the conductivity. Alloying additions or ingot annealing processes affect the relationships between the strength and conductivity more significantly than that of Ag concentration. The strengthening benefit is mainly from interface obstacle and dispersive precipitation while conducting loss is mainly from lattice distortion and interface scattering. An approximate expression to predict the relationships between the strength and conductivity is deduced from the interface strengthening and scattering model.

  20. 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. PMID:23754100

  1. Giant magnetoresistance and interlayer coupling in Cu(111)\\/Ag67Co33 granular multilayers

    Microsoft Academic Search

    Yuansu Luo; Michael Moske; Andrea Kaeufler; Tilmann Lorenz; Konrad Samwer

    1997-01-01

    Cu\\/AgCo layered granular structures were prepared to study their field transport properties in comparison to their microstructure. The superlattices of the samples were characterized by x-ray diffraction. A combination of random and antiparallel alignments of magnetic particles is discovered expressing an oscillation of interlayer coupling similar to conventional multilayers. The weak antiferromagnetic coupling across thin Cu spacer layers between interfacial

  2. PHASE RELATIONS IN THE SYSTEM Au Cu Ag AT LOW TEMPERATURES, BASED ON NATURAL ASSEMBLAGES

    Microsoft Academic Search

    JOHN KNIGHT; CRAIG H. B. LEITCH

    2001-01-01

    The composition of some 85 particles of native gold from the 15 Mile rodingite in serpentinite showing in the Coquihalla gold district and the Wheaton Creek placer in the Dease Lake district, British Columbia, falls mainly within the Cu-rich portion of the Au-Ag-Cu phase diagram. The particles display a variety of textures, including exsolution-induced textures. The textures and phase compositions

  3. Composition and stability of Omega phase in an Al-Cu-Mg-Ag Alloy

    Microsoft Academic Search

    Y. C. Chang; J. M. Howe

    1993-01-01

    Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to determine the stability and composition of the Omega phase in an Al-Cu-Mg-Ag alloy. It is shown that the Omega. phase can nucleate at isothermal aging temperatures up to 470 °C in the alpha + theta phase region of the Al-Cu phase diagram. Furthermore, Omega precipitates formed by aging

  4. Composition and stability of ? phase in an Al-Cu-Mg-Ag Alloy

    Microsoft Academic Search

    Y. C. Chang; J. M. Howe

    1993-01-01

    Transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to determine the stability\\u000a and composition of the ? phase in an Al-Cu-Mg-Ag alloy. It is shown that the ?. phase can nucleate at isothermal aging temperatures\\u000a up to 470 °C in the ? + ? phase region of the Al-Cu phase diagram. Furthermore, ? precipitates formed by aging

  5. Effects of surface topology and texture on exchange anisotropy in NiFe\\/Cu\\/NiFe\\/FeMn spin valves

    Microsoft Academic Search

    C.-M. Park; K.-I. Min; K. H. Shin

    1996-01-01

    We have investigated the effects of texture and interfacial roughness on the exchange anisotropy in NiFe\\/Cu\\/NiFe\\/FeMn spin valves with different buffer layers (no buffer, Cu, or FeMn) on Si(100) or Si(111) substrates by magnetron sputtering. The crystalline structure, surface topology, and exchange anisotropy field (Hex) were characterized. The exchange anisotropy was established all in (111), (200), and (220) textured samples

  6. Bulk mechanical alloying of Cu–Ag and Cu\\/Zr two-phase microstructures by accumulative roll-bonding process

    Microsoft Academic Search

    S. Ohsaki; S. Kato; N. Tsuji; T. Ohkubo; K. Hono

    2007-01-01

    Cu–Ag eutectic alloy and multilayered stacked sheets of Cu\\/Zr were repeatedly cold-rolled by the accumulative roll-bonding (ARB) process as attempts of bulk mechanical alloying. Both ARB-processed two-phase microstructures were deformed into a very fine lamellar structure with a spacing of several nm. The Cu–Ag sheets were deformed by a number of multiple shear bands after two cycles of ARB. Intermixing

  7. XPS, Ssims, Tga, FTIR, and SEM Studies of Catalytic Pyrolysis of Methane Over Ni:Cu\\/Al and Ni:Cu:K\\/AlMODIFIED Supported Nano-Catalysts

    Microsoft Academic Search

    Syed Tajammul Hussain; Asima Siddiqa

    2011-01-01

    The surface interaction of Ni:Cu\\/Al- and Ni:Cu:K\\/Al-modified catalyst has been studied using X-ray photo electron studies (XPS), static secondary ion mass spectrometry (SSIMS), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and temperature programmed desorption (TPD). These techniques revealed that during catalytic studies of methane conversion to carbon nano tubes and hydrogen, the active metals are

  8. Ferromagnetic Dy-Ni and antiferromagnetic Dy-Cu couplings in single-molecule magnets [Dy2Ni] and [Dy2Cu].

    PubMed

    Okazawa, Atsushi; Nogami, Takashi; Nojiri, Hiroyuki; Ishida, Takayuki

    2008-11-01

    The exchange couplings in [{Dy(hfac)3}2Cu(dpk)2] and [{Dy(hfac)3}2Ni(dpk)2(py)2] (Hdpk = di-2-pyridyl ketoxime) were precisely evaluated by high-frequency electron paramagnetic resonance and pulsed-field magnetization studies, giving J(Dy-Cu)/kB = -0.126 K and J(Dy-Ni)/kB = +0.031 K. PMID:18844348

  9. Effect of surface structure on the catalytic behavior of Ni:Cu\\/Al and Ni:Cu:K\\/Al catalysts for methane decomposition

    Microsoft Academic Search

    S. Tajammul Hussain; Sheraz Gul; Muhammed Mazhar; Dalaver H. Anjum; Faical Larachi

    2008-01-01

    Methane decomposition using nickel, copper, and aluminum (Ni:Cu\\/Al) and nickel, copper, potassium, and aluminum (Ni:Cu:K\\/Al) modified nano catalysts has been investigated for carbon fibers, hydrogen and hydrocarbon production. X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectrometry (SSIMS), thermal gravimetric analysis (TGA), Fourier transform infrared (FT-IR), secondary electron microscopy\\/X-ray energy dispersive (SEM-EDX), and temperature programmed desorption (TPD) were used to

  10. Magnetoresistance of ion-beam deposited Co/Cu/Co and NiFe/Co/Cu/Co/NiFe spin valves

    NASA Astrophysics Data System (ADS)

    Slaughter, J. M.; Chen, E. Y.; Tehrani, S.

    1999-04-01

    Giant magnetoresistance (GMR) films produced by ion-beam deposition (IBD) have been studied much less than material produced by other techniques such as magnetron or diode sputtering. Although the process control aspects that are unique to IBD seem ideal for such work, the reported MR values for IBD material are often lower and the material resistivities higher than for conventional sputter-deposited films. We have used a carefully optimized ion-beam process to produce high-quality spin valves of Co/Cu/Co and NiFe/Co/Cu/Co/NiFe. The MR characteristics were studied as a function of the layer thickness for structures that were top pinned with FeMn and bottom-pinned structures grown on NiO. Using a 25 Å thick Cu layer, the MR of top-pinned Co/Cu/Co reached 8.4% over a fairly wide range of top and bottom Co thickness. In contrast, the MR of such films grown on NiO exhibited a strong dependence on the thickness of both Co layers and peaked at 9.9%. The thickness dependence is strong evidence for specular scattering effects at the external interfaces, although it is at least partly an indirect result of the weak exchange bias provided by the NiO in some samples. The symmetric spin valve structure, NiO/Co/Cu/Co/Cu/Co/FeMn, produced our highest MR of 12.1%. The NiFe/Co/Cu/Co/NiFe structures we studied were not optimized for maximum MR, but instead had much different top and bottom NiFe thicknesses as is appropriate in pseudospin-valve material for memory elements. Spin valves of this type had a maximum MR of 7.2%.

  11. Phase equilibria in the CuT1S(Se)AgT1S(Se) systems

    Microsoft Academic Search

    L. T. Un; M. B. Babanly; A. A. Kuliev

    1986-01-01

    The authors use DTA, XPA (CuK \\/SUB alpha\\/ -radiation) and also microhardness measurements to study the nature of interactions in the CuT1S(Se)-AgTiS(Se) system. The phase diagrams of the quasibinary systems are constructed and it is established that the CuT1Se-AgT1Se system is of the eutectic type with limited ranges of solid solutions based on the starting compounds. In the system CuT1S-AgT1S,

  12. Cu x Ni 1? x alloy nanoparticles embedded SiO 2 films: synthesis and structure

    Microsoft Academic Search

    Sourav Pramanik; Sudipto Pal; Sandip Bysakh; Goutam De

    2011-01-01

    Cu–Ni fcc alloy nanoparticles (NPs) of tunable atomic ratios were generated in SiO2 films. The films were prepared using the Cu(NO3)2 and Ni(NO3)2 co-doped inorganic–organic hybrid silica sols by single dipping. Transparent, crack-free, glassy SiO2 films of 310 ± 10 nm in thickness embedded with high mol percent of Cu–Ni alloy NPs were yielded after annealing at 750 °C\\u000a in 10% H2-90% Ar atmosphere.

  13. New cross-sections and intercomparison of proton monitor reactions on Ti, Ni and Cu

    Microsoft Academic Search

    S. Takács; F. Tárkányi; M. Sonck; A. Hermanne

    2002-01-01

    The excitation functions of proton induced reactions on Ti, Ni and Cu were studied using activation method on stacks made of thin metallic foil targets with natural isotopic composition. Since titanium, nickel and copper are ideal target material with respect to their availability, physical, mechanical and chemical properties the use of the natTi(p,x)48V, natNi(p,x)57Ni, natCu(p,x)62Zn, natCu(p,x)63Zn and natCu(p,x)65Zn processes are

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

    SciTech Connect

    Kim, W.; Jin, E.; Wu, J.; Park, J.; Arenholz, E.; Scholl, A.; Hwang, C.; Qiu, Z.

    2010-02-10

    Single crystalline Fe/NiO bilayers were epitaxially grown on Ag(001) and on MgO(001), and investigated by Low Energy Electron Diffraction (LEED), Magneto-Optic Kerr Effect (MOKE), and X-ray Magnetic Linear Dichroism (XMLD). We find that while the Fe film has an in-plane magnetization in both Fe/NiO/Ag(001) and Fe/NiO/MgO(001) systems, the NiO spin orientation changes from in-plane direction in Fe/NiO/Ag(001) to out-of-plane direction in Fe/NiO/MgO(001). These two different NiO spin orientations generate remarkable different effects that the NiO induced magnetic anisotropy in the Fe film is much greater in Fe/NiO/Ag(001) than in Fe/NiO/MgO(001). XMLD measurement shows that the much greater magnetic anisotropy in Fe/NiO/Ag(001) is due to a 90{sup o}-coupling between the in-plane NiO spins and the in-plane Fe spins.

  15. Potential-Controlled Step Flow to 3D Step Decoration Transition: Ni Electrodeposition on Ag(111)

    NASA Astrophysics Data System (ADS)

    Morin, S.; Lachenwitzer, A.; Magnussen, O. M.; Behm, R. J.

    1999-12-01

    A novel growth effect, the potential-controlled transition from 2D step-flow growth \\(-0.69 VAg/AgCl\\) to (i) selective growth of 3D admetal islands at substrate steps \\(-0.73 V\\) and (ii) 3D island growth on steps and substrate terraces \\(-0.85 V\\), is demonstrated for Ni electrodeposition on Ag(111). The nucleation and growth process apparently proceeds via direct deposition from the solution at step sites and can be rationalized by a kinetically controlled multilayer growth process, where the higher layer nucleation rate increases more with overpotential than does the 2D growth rate.

  16. Comparison between Ag (I) and Ni (II) removal from synthetic nuclear power plant coolant water by iron oxide nanoparticles

    PubMed Central

    2013-01-01

    The impact of effective parameters such as iron oxide nanoparticles dosage, contact time and solution pH was optimized for removal of Ag(I) and Ni(II) in the nuclear cooling system and the best conditions were compared. Nearly complete removal (97%) of Ni(II) and Ag(I) were obtained at adsorbent dosage of 40 and 20 g/L, respectively. Experiments showed that 4 hours was a good choice as optimum contact time for two ions removal. The effective parameter was pH, so that maximum removal efficiency was obtained for Ag(I) in acidic pH=3 and for Ni(II) in basic pH=10. It seems that removal of Ag(I) was controlled by adsorption-reduction mechanism, but Ni(II) could place only adsorption. Langmuir and Freundlich model was more suitable for nickel and silver removal by this adsorbent, respectively. Ag(I) and Ni(II) removal efficiency trend by this adsorbent is similar at periods but different in the concentrations, pHs and equilibrium model. The obtained results were very promising, as both Ag(I) and Ni(II) were effectively removed from synthetic wastewater and there was a possibility to remove Ag(I) very fast. Hence, the idea of using nanoparticles for application of metal ions removal from wastewaters seems to be very efficient and quite promising. PMID:24499654

  17. Effect of protein adsorption on the corrosion behaviour of 70Cu-30Ni alloy in artificial seawater

    E-print Network

    Effect of protein adsorption on the corrosion behaviour of 70Cu-30Ni alloy in artificial seawater workability. Cu- Ni alloys are preferred in marine environments because of their corrosion resistance due behaviour of 70Cu-30Ni (wt. %) alloy in static artificial seawater and on the chemical composition of oxide

  18. Temperature dependence of magnetic behaviour in very fine grained, spark plasma sintered NiCuZn Ferrites

    E-print Network

    Boyer, Edmond

    Temperature dependence of magnetic behaviour in very fine grained, spark plasma sintered NiCu spark plasma sintering technique, a family of very fine grained, fully dense NiCuZn ferrites have been focus on NiCuZn Ferrites which show wider frequency bandwidth and quite lower initial permeability

  19. The behaviour of Cu x Ni ( x = 10 to 40 wt%) alloys in alkaline solutions containing chloride ions

    Microsoft Academic Search

    I. Milošev; M. Metikoš-Hukovi?

    1997-01-01

    An electrochemical study in combination with microscopic investigation and photopotential measurements was performed for Cu-xNi alloys (x = 10 to 40 wt%) and Cu and Ni metals in slightly alkaline solution, pH = 9.2. Cu-xNi alloys behave similarly to copper metal. The general composition of the passive layer can be described by an outer CuOCu(OH)2 layer overlying a Cu2O barrier

  20. On the nature of the second phase particles present in an as-cast Al-Cu-Mg-Ag alloy

    SciTech Connect

    Mukhopadhyay, A.K. [Defence Metallurgical Research Lab., Hyderabad (India)] [Defence Metallurgical Research Lab., Hyderabad (India)

    1999-08-20

    Examination of phases present in the as-cast microstructure of age hardenable Al alloys has always provided important information regarding the nature of the precipitates that may form in such alloys during artificial aging. Considerable commercial interest has been shown in recent years in Al-Cu-Mg alloys containing trace addition of Ag. One of the major difficulties involved in the evaluation of the chemistry of the phase precipitates, using conventional micro analytical techniques, is their very small sizes. The difficulties experienced in providing conclusive evidence for the presence of Ag within the small rods of S precipitates formed in an Al-Cu-Mg-Ag alloy has been known in this regard. According to the ternary Al-Cu-Mg phase diagram, phases based on both {theta}(Al{sub 2}Cu) and S(Al{sub 2}CuMg) would be present (as solidification products) in the as-cast Al-Cu-Mg-Ag alloys of commercial interest. Analysis of coarse particles of S present in the as-cast Al-Cu-Mg-Ag alloys would provide decisive information regarding the presence of Ag within the S phase. In this paper, using light microscopy, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA), results on the compositional analysis of the second phase particles present in an as-cast Al-Cu-Mg-Ag alloy are described. Emphasis is given on the determination of the locations of the trace alloy additions within the phase particles of interest.

  1. 3D Epitaxy of Graphene nanostructures in the Matrix of Ag, Al and Cu

    NASA Astrophysics Data System (ADS)

    Salamanca-Riba, Lourdes; Isaacs, Romaine; Wuttig, Manfred; Lemieux, Melburne; Hu, Liangbing; Iftekhar, Jaim; Rashkeev, Sergey; Kukla, Maija; Rabin, Oded; Mansour, Azzam

    2015-03-01

    Graphene nanostructures in the form ribbons were embedded in the lattice of metals such as Ag, Cu, and Al in concentrations up to 36.4 at.%, 21.8 at% and 10.5 at.%, respectively. These materials are called covetics. Raman scattering from Ag and Al covetics indicate variations in the intensity of peaks at ~ 1,300 cm-1 and 1,600 cm-1 with position on the sample. These peaks are associated with the D (defects) and G (graphite E2g mode) peaks of graphitic carbon with sp2 bonding and reveal various degrees of imperfections in the graphene layers. First principles calculations of the dynamic matrix of Ag and Al covetics show bonding between C and the metal. EELS mapping of the C-K edge and high resolution lattice images show that the graphene-like regions form ribbons with epitaxial orientation with the metal lattice of Ag and Al. The temperature dependences of the resistivites of Ag and Cu covetics are similar to those of the pure metals with only slight increase in resistivity. Films of Cu covetic deposited by e-beam evaporation and PLD show higher transmittance and resistance to oxidation than pure metal films of the same thickness indicating that copper covetic films can be used for transparent electrodes. Funded by DARPA/ARL Grant No. W911NF-13-1-0058, and ONR Award No N000141410042.

  2. Mixed-sputter deposition of Ni-Ti-Cu shape memory films

    Microsoft Academic Search

    P. Krulevitch; P. B. Ramsey; D. M. Makowiecki; A. P. Lee; M. A. Northrup; G. C. Johnson

    1996-01-01

    Ni-Ti-Cu shape memory films were mixed-sputter deposited from separate nickel, titanium, and copper targets, providing increased compositional flexibility. Shape memory characteristics, examined for films with 7 at.% Cu and 41–51 at.% Ti, were determined with temperature-controlled substrate-curvature measurements, and the microstructure was studied with transmission electron microscopy. The Ni-Ti-Cu films were found to have shape memory properties comparable with bulk

  3. Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

    NASA Astrophysics Data System (ADS)

    Fang, Gu; Chen, Chih-chi

    2015-07-01

    Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

  4. Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

    NASA Astrophysics Data System (ADS)

    Fang, Gu; Chen, Chih-chi

    2015-04-01

    Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

  5. Effects of Li content on precipitation in Al-Cu-(Li)-Mg-Ag-Zr alloys

    SciTech Connect

    Huang, B.P.; Zheng, Z.Q. [Central South Univ. of Technology, Changsha (China). Dept. of Materials Science and Engineering] [Central South Univ. of Technology, Changsha (China). Dept. of Materials Science and Engineering

    1998-01-06

    Although much attention has been paid to Al-Cu-Li-Mg-Ag-Zr alloys, there are sparse reports about the influence of Li on precipitation in these alloys. The aim of the present study is to determine the effects of Li on modifying precipitation in a baseline aluminum alloy 2195 and the accompanying variants with 0--1.6 wt.% Li.

  6. Effects of Li Content on Precipitation in Al-Cu-(Li)-Mg-Ag-Zr Alloys

    Microsoft Academic Search

    Bi-Ping Huang; Zi-Qiao Zheng

    1998-01-01

    Although much attention has been paid to Al-Cu-Li-Mg-Ag-Zr alloys, there are sparse reports about the influence of Li on precipitation in these alloys. The aim of the present study is to determine the effects of Li on modifying precipitation in a baseline aluminum alloy 2195 and the accompanying variants with 0--1.6 wt.% Li.

  7. Short-range ferromagnetism in alloy ribbons of Fe-Cr-Si-Nb-(Ag, Cu)

    NASA Astrophysics Data System (ADS)

    Thanh, P. Q.; Hoa, N. Q.; Chau, N.; Huu, C. X.; Ngo, D.-T.; Phan, T. L.

    2014-04-01

    We have studied the magnetic properties of two amorphous alloy ribbons Fe72Cr6Si4Nb5B12Ag1 (FCSNB-Ag) and Fe72Cr6Si4Nb5B12Cu1 (FCSNB-Cu), prepared by using a melt-spinning technique. Magnetization ( M) measurements for various temperatures ( T) and magnetic fields ( H) indicate that ferromagnetic-paramagnetic (FM-PM) phase transitions take place in FCSNB-Ag and FCSNB-Cu at Curie temperatures ( T C ) of about 308.3 K and 322.5 K, respectively. Analyses of M - H data at different temperatures in the vicinity of the FM-PM phase transition based on the modified Arrott plot method and scaling hypothesis yielded the exponent values of ? = 0.369± 0.005, ? = 1.359± 0.005 and ? = 4.7± 0.1 for FCSNB-Ag, and ? = 0.376± 0.002, ? = 1.315 ± 0.006 and ? = 4.5± 0.1 for FCSNB-Cu. Compared with the values from theoretical models, these values are close to those expected for the 3D Heisenberg model, demonstrating the existence of short-range FM order in the amorphous alloy ribbons.

  8. THE TWO-DIMENSIONAL VALENCE ELECTRONIC STRUCTURE OF A MONOLYAER OF Ag ON Cu(00l)

    SciTech Connect

    Tobin, J.G.; Robey, S.W.; Shirley, D.A.

    1985-05-01

    The metal overlayer system c(10x2)Ag/Cu(001) was studied at coverages near one monolayer with angle-resolved photoemission. The observed spectroscopic features indicate a two-dimensional d-band electronic structure that can be interpreted using a model with planar, hexagonal symmetry in which crystal field effects dominate over spin-orbit effects.

  9. Twin boundaries with 9R zone in Cu and Ag studied by quantitative HRTEM

    Microsoft Academic Search

    D. Hofmann; F. Ernst

    1995-01-01

    When highly inclined against the {111} plane of the coherent twin boundary, ?3 tilt boundaries in Cu or Ag have a complex structure. As the boundary plane approaches the symmetrical {211} orientation, the grain boundaries decompose into two phase boundaries. Between these phase boundaries the metal adopts a rhombohedral crystal structure, denoted as 9R. Not the {211}-oriented boundary, but a

  10. Diffusion induced grain boundary migration in Au-Cu and Au-Ag thin films

    Microsoft Academic Search

    J. D. Pan

    1980-01-01

    Diffusion induced grain boundary migration was studied by employing Au-Cu and Au-Ag thin film specimens. The results support the conclusion that this phenomenon is widespread and that it can lead to boundary migration and bulk composition change under conditions where neither is expected. Two approaches were employed to study this phenomenon. In the first approach polycrystalline gold thin films were

  11. Effect of the Vibrational Modes on the Ag-Cu Phase Diagram

    Microsoft Academic Search

    Su-Qing Duan; Xian-Geng Zhao; Shao-Jun Liu; Ben-Kun Ma

    2000-01-01

    We calculated the vibrational free energies of the selected ordered compounds in the Ag-Cu system by using two kinds of methods: (1) calculating the phonon dispersion and density of states and the consequently vibrational free energies by using the method of ab initio inverted interatomic potentials and dynamic matrix; (2) the vibrational free energies determined by a Debye-Grüneisen approximation. The

  12. Surface segregation near the temperature of bulk phase separation: Incomplete wetting in Cu(Ag) alloys

    Microsoft Academic Search

    G. Tréglia; B. Legrand; J. Eugène; B. Aufray; F. Cabané

    1991-01-01

    Surface segregation in alloys should present drastic modifications near a bulk phase transition. In particular, when the phase diagram exhibits a miscibility gap, one can wonder to what extent surface segregation could be viewed as the first step towards bulk phase separation. We show, in the particular case of very dilute Cu(Ag) alloys, that the actual situation is even more

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

    PubMed

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

    2014-05-21

    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 ? 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). PMID:24733262

  14. Abundances of Ag and Cu in mantle peridotites and the implications for the behavior of chalcophile elements in the mantle

    NASA Astrophysics Data System (ADS)

    Wang, Zaicong; Becker, Harry

    2015-07-01

    Silver abundances in mantle peridotites and the behavior of Ag during high temperature mantle processes have received little attention and, as a consequence, the abundance of Ag in the bulk silicate Earth (BSE) has been poorly constrained. In order to better understand the processes that fractionate Ag and other chalcophile elements in the mantle, abundances of Ag and Cu in mantle peridotites from different geological settings (n = 68) have been obtained by isotope dilution ICP-MS methods. In peridotite tectonites and in a few suites of peridotite xenoliths which display evidence for variable extents of melt depletion and refertilization by silicate melts, Ag and Cu abundances show positive correlations with moderately incompatible elements such as S, Se, Te and Au. The mean Cu/Ag in fertile peridotites (3500 ± 1200, 1s, n = 38) is indistinguishable from the mean Cu/Ag of mid ocean ridge basalts (MORB, 3600 ± 400, 1s, n = 338) and MORB sulfide droplets. The constant mean Cu/Ag ratios indicate similar behavior of Ag and Cu during partial melting of the mantle, refertilization and magmatic fractionation, and thus should be representative of the Earth's upper mantle. The systematic fractionation of Cu, Ag, Au, S, Se and Te in peridotites and basalts is consistent with sulfide melt-silicate melt partitioning with apparent partition coefficients of platinum group elements (PGE) > Au ? Te > Cu ? Ag > Se ? S. Because of the effects of secondary processes, the abundances of chalcophile elements, notably S, Se, but also Cu and the PGE in many peridotite xenoliths are variable and lower than in peridotite massifs. Refertilization of peridotite may change abundances of chalcophile and lithophile elements in peridotite massifs, however, this seems to mostly occur in a systematic way. Correlations with lithophile and chalcophile elements and the overlapping mean Cu/Ag ratios of peridotites and ocean ridge basalts are used to constrain abundances of Ag and Cu in the BSE at 9 ± 3 (1s) ng/g and 30 ± 6 ?g/g (1s), respectively. The very different extent of depletion of Ag and Cu in the BSE cannot be explained by low pressure-temperature core formation if currently available metal-silicate partitioning data are applied.

  15. Surface modification processes during methane decomposition on Cu-promoted Ni–ZrO2 catalysts

    PubMed Central

    Wolfbeisser, Astrid; Klötzer, Bernhard; Mayr, Lukas; Rameshan, Raffael; Zemlyanov, Dmitry; Bernardi, Johannes; Rupprechter, Günther

    2015-01-01

    The surface chemistry of methane on Ni–ZrO2 and bimetallic CuNi–ZrO2 catalysts and the stability of the CuNi alloy under reaction conditions of methane decomposition were investigated by combining reactivity measurements and in situ synchrotron-based near-ambient pressure XPS. Cu was selected as an exemplary promoter for modifying the reactivity of Ni and enhancing the resistance against coke formation. We observed an activation process occurring in methane between 650 and 735 K with the exact temperature depending on the composition which resulted in an irreversible modification of the catalytic performance of the bimetallic catalysts towards a Ni-like behaviour. The sudden increase in catalytic activity could be explained by an increase in the concentration of reduced Ni atoms at the catalyst surface in the active state, likely as a consequence of the interaction with methane. Cu addition to Ni improved the desired resistance against carbon deposition by lowering the amount of coke formed. As a key conclusion, the CuNi alloy shows limited stability under relevant reaction conditions. This system is stable only in a limited range of temperature up to ~700 K in methane. Beyond this temperature, segregation of Ni species causes a fast increase in methane decomposition rate. In view of the applicability of this system, a detailed understanding of the stability and surface composition of the bimetallic phases present and the influence of the Cu promoter on the surface chemistry under relevant reaction conditions are essential. PMID:25815163

  16. Localized depth distribution in the bombarded surface of Ag?Cu alloy

    NASA Astrophysics Data System (ADS)

    Wang, Wenmin; Wang, Zhenxia; Lu, Rongrong; Zhu, Fuying; Wu, Xiankang; Guo, Yingmei; Zhu, Jieqing

    1995-09-01

    Combined with electron microbeam techniques such as scanning electron microscopy and electron-induced X-ray emission, a helium microbeam is used to study the effect of Ar + ion bombardment on the surface of a binary alloy Ag 37Cu 63 by particle-induced X-ray emission and Rutherford backscattering. A pronounced change of the surface concentration and depth profile has been found at both Cu-enriched solid solution micro-region and Ag-enriched eutectic mixture micro-region on the alloy surface due to ion bombardment. The preferential sputtering of Ag and bombardment-induced surface segregation is suggested to be attributed to the composition change in the near-surface regions. A superposition of depth distributions determined from different micro-phase-regions is experimentally confirmed.

  17. 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, E-mail: imdlhkkim@khu.ac.kr [Department of Advanced Materials Engineering for Information and Electronics, Kyung-Hee University, 1 Seocheon-dong, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Noh, Yong-Jin; Na, Seok-In [Graduate School of Flexible and Printable Electronics, Chonbuk National University, 664-14, Deokjin-dong, Jeonju-si, Jeollabuk-do 561-756 (Korea, Republic of)

    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} ? cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54?×?10{sup ?3} ?{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.

  18. The investigation of giant magnetoimpedance effect in meander NiFe/Cu/NiFe film

    NASA Astrophysics Data System (ADS)

    Zhou, Zhimin; Zhou, Yong; Cao, Ying

    In this paper, the meander NiFe/Cu/NiFe film is fabricated by MEMS technique and the giant magnetoimpedance (GMI) effects in both transverse and longitudinal directions are studied in the frequency range of 0.1-40 MHz. Upon increasing the magnetic field from 0 to 150 Oe, the effects in both directions show the single peak variation tendency, which is attributed to the deflection of anisotropy from the transverse direction. Compared with the GMI peak values of 11.2% and 3.0% in a longitudinal straight-line section, the GMI effects in meander structure are greatly improved and it could be up to 37% and 16.7% for the longitudinal and transverse results, respectively. The external inductance resulted from the meander shape is mainly responsible for the improvement.

  19. 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.

  20. Rapid direct conversion of Cu2-xSe to CuAgSe nanoplatelets via ion exchange reactions at room temperature.

    PubMed

    Moroz, N A; Olvera, A; Willis, G M; Poudeu, P F P

    2015-06-01

    The use of template nanostructures for the creation of photovoltaic and thermoelectric semiconductors is becoming a quickly expanding synthesis strategy. In this work we report a simple two-step process enabling the formation of ternary CuAgSe nanoplatelets with a great degree of control over the composition and shape. Starting with hexagonal nanoplatelets of cubic Cu2-xSe, ternary CuAgSe nanoplatelets were generated through a rapid ion exchange reaction at 300 K using AgNO3 solution. The Cu2-xSe nanoplatelet template and the final CuAgSe nanoplatelets were analyzed by electron microscopy and X-ray diffraction (XRD). It was found that both the low temperature pseudotetragonal and the high temperature cubic forms of CuAgSe phase were created while maintaining the morphology of the Cu2-xSe nanoplatelet template. Thermal and electronic transport measurements of hot-pressed pellets of the synthesized CuAgSe nanoplatelets showed a drastic reduction in the thermal conductivity and a sharp transition from n-type (S = -45 ?V K(-1)) to p-type (S = +200 ?V K(-1)) semiconducting behavior upon heating above the structural transition from the low temperature orthorhombic to the high temperature super-ionic cubic phase. This simple reaction process utilizing a template nanostructure matrix represents an energy efficient, cost-efficient, and versatile strategy to create interesting materials with lower defect density and superior thermoelectric performance. PMID:25965176

  1. Electron affinities and ionization energies of Cu and Ag delafossite compounds: A hybrid functional study

    NASA Astrophysics Data System (ADS)

    Miao, Mao-Sheng; Yarbro, Sam; Barton, Phillip T.; Seshadri, Ram

    2014-01-01

    Using density functional theory with a hybrid functional, we calculate the ionization energies and electron affinities of a series of delafossite compounds (AMO2: A =Cu, Ag; M =B, Al, Ga, In, Sc). The alignments of the valence band maximum and the conduction band minimum, which directly relate to the ionization energies and electron affinities, were obtained by calculations of supercell slab models constructed in a nonpolar orientation. Our calculations reveal that the ionization energy decreases with an increasing atomic number of group-III elements, and thus suggest an improved p-type doping propensity for heavier compounds. For keeping both a low ionization energy and a band gap of sufficient size, CuScO2 is superior to the Cu-based group-III delafossites. By analyzing the electronic structures, we demonstrate that the compositional trend of the ionization energies and electron affinities is the result of a combined effect of d-band broadening due to Cu(Ag)-Cu(Ag) coupling and a repositioning of the d-band center.

  2. Site-dependent magnetism of Ni adatoms on MgO/Ag(001)

    NASA Astrophysics Data System (ADS)

    Albertini, Oliver R.; Liu, Amy Y.; Jones, Barbara A.

    2015-06-01

    We examine the adsorption of a single Ni atom on a monolayer of MgO on a Ag substrate using DFT and DFT +U computational approaches. We find that the electronic and magnetic properties vary considerably across the three binding sites of the surface. Two of the binding sites are competitive in energy, and the preferred site depends on the strength of the on-site Coulomb interaction U . These results can be understood in terms of the competition between bonding and magnetism for surface adsorbed transition metal atoms. Comparisons are made with a recent experimental and theoretical study of Co on MgO/Ag, and implications for scanning tunneling microscopy experiments on the Ni system are discussed.

  3. Neutron Time of Flight phonon spectra of Cu2O and Ag2O powders

    NASA Astrophysics Data System (ADS)

    Winn, Barry; Hagen, Mark; Shapiro, Steve

    2009-03-01

    Negative thermal expansion materials cuprite (Cu2O) and Ag2O share the same structure (space group Pn3m). Here, we report inelastic neutron time of flight measurements of room temperature powder samples of each system, using the Pharos chopper spectrometer at LANSCE, at up to 100 meV energy transfer. For Cu2O, high energy optical phonons are observed between 60 and 80 meV, while for Ag2O, these phonons are observed between 50 and 70 meV. Results are compared to previous work, and to recent neutron triple axis spectrometer results for Cu2O, and their relevance to negative thermal expansion is discussed.

  4. Growth and structural properties of CuAg and CoPt bimetallic nanoparticles.

    PubMed

    Langlois, Cyril; Alloyeau, Damien; Le Bouar, Yann; Loiseau, Annick; Oikawa, Tetsuo; Mottet, Christine; Ricolleau, Christian

    2008-01-01

    Core/shell CuAg and alloyed CoPt have been synthesized using two vapor phase deposition techniques. For CuAg prepared by Thermal Evaporation (TE), the size and the morphology of the Cu cores are the key parameters to promote the formation of the core/shell arrangement. For CoPt synthesized by Pulsed Laser Deposition (PLD), the growth kinetics of nanoparticles, depending on the deposition rate, the substrate nature and the temperature, controls the nanoparticle morphology. The competition between the growth and the ordering kinetics governs the nanoparticle structure. By reducing the growth kinetics, as-grown L1(0) ordered nanoparticles are obtained according to the bulk phase diagram. PMID:18447027

  5. Thermoelectric properties of molten Bi2Te3, CuI, and AgI

    NASA Astrophysics Data System (ADS)

    Nishikawa, Kazutaka; Takeda, Yasuhiko; Motohiro, Tomoyoshi

    2013-01-01

    To achieve large figure of merit (ZT) and superior thermal durability at high temperatures, we have investigated thermoelectric properties of molten Bi2Te3, CuI, and AgI up to 1173 K. Molten Bi2Te3 was found to have large electrical conductivity between 1800 and 2000 (? ? cm)-1. Molten CuI and AgI, however, exhibited small electrical conductivity less than 1 (? ? cm)-1, nevertheless they show very large Seebeck coefficients over 800 ?V/K. We estimated thermal conductivity using Wiedemann Franz law and the model established by Regel et al. [Phys. Status Solidi A 5, 13 (1971)]. The evaluated ZT for CuI is over 0.1.

  6. Electrochemical detection of Cu2+ through Ag nanoparticle assembly regulated by copper-catalyzed oxidation of cysteamine.

    PubMed

    Cui, Lin; Wu, Jie; Li, Jie; Ge, Yanqiu; Ju, Huangxian

    2014-05-15

    A highly sensitive and selective electrochemical sensor was developed for the detection of Cu(2+) by the assembly of Ag nanoparticles (AgNPs) at dithiobis[succinimidylpropionate] encapsulated Au nanoparticles (DSP-AuNPs), which was regulated by copper-catalyzed oxidation of cysteamine (Cys). The electrochemical sensor was constructed by layer-by-layer modification of glassy carbon electrode with carbon nanotubes, poly(amidoamine) dendrimers and DSP-AuNPs. In the absence of Cu(2+), Cys could bind to the surface of citrate-stabilized AgNPs via Ag-S bond, thus AgNPs could be assembled on the sensor surface through the reaction between DSP and Cys. In contrast, the copper-catalyzed oxidation of Cys by dissolved oxygen in the presence of Cu(2+) inhibited the Cys-induced aggregation of AgNPs, leading to the decrease of the electrochemical stripping signal of AgNPs. Under the optimized conditions, this method could detect Cu(2+) in the range of 1.0-1000 nM with a detection limit of 0.48 nM. The proposed Cu(2+) sensor showed good reproducibility, stability and selectivity. It has been satisfactorily applied to determine Cu(2+) in water samples. PMID:24389390

  7. High conductivity in hydrothermally grown AgCuO(2) single crystals verified using focused-ion-beam-deposited nanocontacts.

    PubMed

    Muñoz-Rojas, David; Córdoba, Rosa; Fernández-Pacheco, Amalio; De Teresa, José María; Sauthier, Guillaume; Fraxedas, Jordi; Walton, Richard I; Casañ-Pastor, Nieves

    2010-12-01

    The silver-copper mixed oxide AgCuO(2) (also formulated as Ag(2)Cu(2)O(4)) possesses a peculiar electronic structure in which both Ag and Cu are partially oxidized, with the charge being delocalized among the three elements in the oxide. Accordingly, a quasi-metallic behavior should be expected for this oxide, and indeed bulk transport measurements show conductivity values that are orders of magnitude higher than for other members of this novel oxide family. The presence of silver makes thermal sintering an inadequate method to evaluate true conductivity, and thus such measurements were performed on low density pellets, giving an underestimated value for the conductivity. In the present work we present a new synthetic route for AgCuO(2) based on mild hydrothermal reactions that has yielded unprecedented large AgCuO(2) single-crystals well over 1 ?m in size using temperatures as low as 88 °C. We have used a dual beam instrument to apply nanocontacts to those crystals, allowing the in situ measurement of transport properties of AgCuO(2) single crystals. The results show a linear relationship between applied current and measured voltage. The conductivity values obtained are 50 to 300 times higher than those obtained for bulk low density AgCuO(2) pellets, thus confirming the high conductivity of this oxide and therefore supporting the delocalized charge observed by spectroscopic techniques. PMID:21049939

  8. Theoretical study of Cu x Ag 1? x I alloys

    Microsoft Academic Search

    B. Amrani; F. El Haj Hassan; R. Khenata; H. Akbarzadeh

    2009-01-01

    We have performed first-principles calculations using full potential linearized augmented plane wave (FP-LAPW) method within density functional theory (DFT) to investigate the fundamental properties of CuxAg1?xI alloys. We used both GGA96 [J.P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 77 (1996) 3865.] and EVGGA [E. Engel, S.H. Vosko, Phys. Rev. B. 47 (1993) 13164.] generalized gradient approximations of the

  9. Anisotropic Magnetoresistance in single-crystalline Ag/NiO/Fe3O4/MgO(001) sample

    NASA Astrophysics Data System (ADS)

    Li, Jia; Sucipt Tan, Ali; Son, Jim; Jin, Eric; Qiu, Zi Q.

    2012-02-01

    Anisotropic Magnetoresistance (AMR) is a well-known phenomenon in ferromagnetic (FM) materials that the resistivity exhibit different values as the electric current flows parallel and perpendicular to the magnetization direction, respectively. Recognizing that the AMR depends on the spin axis rather than spin direction, we propose that AMR effect should also exist in antiferromagnetic (AFM) materials. In this presentation, we will report the AMR effect in single crystalline Ag/Fe3O4/NiO/MgO(001) films in which the electrical current is mainly carried by the nonmagnetic Ag film. By changing the FM Fe3O4 magnetization direction with an external magnetic field, the AFM NiO spin axis direction can be changed through the Fe3O4/NiO coupling. We observe a non-zero AMR effect in Ag and that the AMR value depends sensitively on the Ag thickness, suggesting that the observed AMR comes from the spin-dependent NiO/Ag interfacial scattering. Moreover, the magnitude of the AMR effect at 1nm thick Ag in Ag/Fe3O4/NiO/MgO(001) is comparable to the AMR value from single Fe film.

  10. Effect of Cu interfacial layer thickness on spin-injection efficiency in NiFe/Cu/graphene spin valves

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Wang, Ying; Wu, Baolei; Wu, Yihong

    2013-05-01

    The spin injection efficiency in NiFe/Cu/graphene spin-valves has been investigated systematically with emphasis on the Cu thickness effect. An optimum Cu thickness is found to be around 2.5 nm for which spin injection efficiency up to 8.4% has been measured. With a further increase of Cu thickness, the efficiency decreases to 3.6%-3.8% at 3.5 nm and is hardly measureable at 5 nm and beyond. The decrease is discussed in the context of enhanced spin-flip scattering at the NiFe/Cu interface and grain boundaries in the polycrystalline Cu as well as current shunting induced lengthening of travelling distance of electrons inside Cu. On the other hand, a further reduction of Cu thickness below 2.5 nm results in pinholes which also lowers the spin-injection efficiency. In addition to the Cu thickness, another factor which affects the spin signal is the DC bias voltage. The non-local magnetoresistance is highest when measured under zero-bias condition and becomes smaller when a DC bias is applied. The reduction of efficiency correlates well with the decrease in Cu-graphene contact resistance, which is consistent with the non-ohmic nature of Cu-graphene interface. Hanle spin precession curves were measured at different back gate biases from which the spin relaxation length was determined to be 1.6 ?m-2.7 ?m.

  11. Synthesis and study of a 10% Ni doped (YBa sub 2 Cu sub 3 minus x Ni sub x O sub y ) high T sub c superconductor

    SciTech Connect

    Saini, N.L.; Srivastava, P.; Sharma, R.K.; Garg, K.B. (Rajasthan Univ., Jaipur (India). Dept. of Physics); Dwevedi, G.L. (Mineral Physics Div., Geological Survey of India, Jaipur (IN))

    1990-01-01

    This study is based on the authors hypothesis that predicts the possibility of Y-Ba-Ni-O superconductor. A comparative study of Y-Ba-Cu-O and 10% Ni doped Y-Ba-Cu-O (having T{sub c} as high as 84 K) is presented. Resistivity, XRD, oxygen content and Cu-K-XANES measurements are reported.

  12. Influence of Dopant on Growth of Intermetallic Layers in Sn-Ag-Cu Solder Joints

    NASA Astrophysics Data System (ADS)

    Li, G. Y.; Bi, X. D.; Chen, Q.; Shi, X. Q.

    2011-02-01

    The interfacial interaction between Cu substrates and Sn-3.5Ag-0.7Cu- xSb ( x = 0, 0.2, 0.5, 0.8, 1.0, 1.5, and 2.0) solder alloys has been investigated under different isothermal aging temperatures of 100°C, 150°C, and 190°C. Scanning electron microscopy (SEM) was used to measure the thickness of the intermetallic compound (IMC) layer and observe the microstructural evolution of the solder joints. The IMC phases were identified by energy-dispersive x-ray spectroscopy (EDX) and x-ray diffractometry (XRD). The growth of both the Cu6Sn5 and Cu3Sn IMC layers at the interface between the Cu substrate and the solder fits a power-law relationship with the exponent ranging from 0.42 to 0.83, which suggests that the IMC growth is primarily controlled by diffusion but may also be influenced by interface reactions. The activation energies and interdiffusion coefficients of the IMC formation of seven solder alloys were determined. The addition of Sb has a strong influence on the growth of the Cu6Sn5 layer, but very little influence on the formation of the Cu3Sn IMC phase. The thickness of the Cu3Sn layer rapidly increases with aging time and temperature, whereas the thickness of the Cu6Sn5 layer increases slowly. This is probably due to the formation of Cu3Sn at the interface between two IMC phases, which occurs with consumption of Cu6Sn5. Adding antimony to Sn-3.5Ag-0.7Cu solder can evidently increase the activation energy of Cu6Sn5 IMC formation, reduce the atomic diffusion rate, and thus inhibit excessive growth of Cu6Sn5 IMCs. This study suggests that grain boundary pinning is one of the most important mechanisms for inhibiting the growth of Cu6Sn5 IMCs in such solder joints when Sb is added.

  13. The manufacturing of an electroplated Ni layer on textured Cu substrate for Cu-based HTS coated conductors

    NASA Astrophysics Data System (ADS)

    Zhou, Y. X.; Sun, L.; Chen, X.; Fang, H.; Putman, P. T.; Salama, K.

    2005-01-01

    A sharp cube textured Ni overlayer on Cu substrates has been developed for the manufacturing of long-length RABiTS-based coated conductor tapes. Using a low-cost, non-vacuum and easily scalable technique of electroplating, smooth, crack-free and continuous Ni overlayers were deposited on cube textured Cu substrates without any intermediate layers. In addition, sharp cube textured Sm-doped CeO2 buffer layers have been grown on the Ni-plated Cu substrates using pulsed laser deposition and found to exhibit in-plane and out-of-plane FWHM values of 6.50° and 5.25°, respectively. This electroplating process promises an efficient route for manufacturing Cu-based HTS coated conductors.

  14. Surface and interfacial tension of the Ni-Fe-S, Ni-Cu-S, and fayalite slag systems

    Microsoft Academic Search

    S. W. Ip; J. M. Toguri

    1993-01-01

    The surface tensions of the Ni-Fe-S system together with the Ni-Cu-S and fayalite-type slag systems were measured using the\\u000a sessile drop technique. Drop images were obtained by X-ray radiography. For the Ni3S2-FeS pseudo-binary system, the surface tension of the matte increased with matte grade and showed a positive deviation from\\u000a ideality with matte grade. This suggests that Ni3S2 dominates in

  15. Light heavy-fermions in Zn and Ni doped 123 Cu-O superconductors

    Microsoft Academic Search

    S. T. Ting; Y. Gao; C. S. Jee; S. Rahman; J. E. Crow; T. Mihalisin; G. H. Myer; I. Perez; R. E. Salomon; P. Schlottmann; J. Schwegler

    1990-01-01

    The temperature dependence of the specific heat C(T) has been measured for YBa2(Cu1-xMx)3O7 (YBCO) with M = Zn and Ni and 1.2Ni predominantely occupy the lattice at Cu-sites located in the CuO2 planes. The crystal structure remains orthorhombic for the concentrations studied, i.e., x<0.15 and the oxygen content is independent of Zn and Ni doping. Zn

  16. Formation of quasicrystals in bulk glass forming Zr-Cu-Ni-Al alloys

    Microsoft Academic Search

    U. Köster; J. Meinhardt; S. Roos; R. Busch

    1997-01-01

    Zr65Cu17.5Ni10Al7.5 as well as Zr69.5Cu12Ni11Al7.5 belong to the best glass forming alloys known. Transmission electron microscopy (TEM) and X-ray analysis of samples annealed above the glass transition temperature exhibit the formation of quasicrystalline microstructures. The metastable icosahedral phase is primitive with a quasilattice constant a = 0.253 nm; its composition is close to Zr69.5Cu12Ni11Al7.5. The growth of spherical shaped quasicrystals

  17. Effect of Cr on the corrosion resistance of Cu–6Ni–4Sn alloys

    Microsoft Academic Search

    W. S. Jeon; C. C. Shur; J. G. Kim; S. Z. Han; Y. S. Kim

    2008-01-01

    The corrosion characteristics of Cu–6% Ni–4% Sn–x% Cr alloys in an acid-chloride solution (0.1M H2SO4+0.0056M NaCl) at pH 1.2, were studied as a function of the chromium content. Three kinds of Cu–6% Ni–4% Sn–x% Cr alloys were prepared by melting and casting, followed by thermomechanical treatments. The corrosion behavior of the Cu–6% Ni–4% Sn–x% Cr alloys was investigated using electrochemical

  18. The early stage dissolution of Ni and the nucleation of Ni-Sn intermetallic compound at the interface during the soldering of Sn-3.5Ag on a Ni substrate

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Wei; Lin, Kwang-Lung

    2010-09-01

    The early stage soldering reaction, reflow for 5 s at 250 °C followed by a liquid nitrogen quench, of Sn-3.5Ag on an electroplated Ni substrate gives rise to a Ni dissolution zone, an amorphous Ni-Sn diffusion zone, and nuclei of NiSn intermetallic compound within the interfacial region. The nucleation of NiSn takes place at the interface between the dissolution zone and the amorphous diffusion zone as well as within the amorphous Ni-Sn diffusion zone, producing 10 nm nanocrystallites. High resolution transmission electron microscope observations indicate that NiSn is the preliminary intermetallic compound that forms during the soldering reaction.

  19. Introduction of antibacterial function into biomedical TiNi shape memory alloy by the addition of element Ag

    E-print Network

    Zheng, Yufeng

    Introduction of antibacterial function into biomedical TiNi shape memory alloy by the addition alloy Ion release Biocompatibility Antibacterial property a b s t r a c t A new kind of biomedical shape memory TiNiAg alloy with antibacterial function was successfully devel- oped in the present study

  20. Occasional ``long-range'' nonequilibrium body-centered-cubic structures in NiFe\\/Cu spin valves

    Microsoft Academic Search

    H. Geng; J. W. Heckman; W. P. Pratt; J. Bass; F. J. Espinosa; S. D. Conradson; D. Lederman; M. A. Crimp

    1999-01-01

    We describe conventional and high-resolution transmission electron microscopy (HRTEM) characterization of the microstructure of sputtered NiFe\\/Cu giant magnetoresistance spin valves (Cu\\/FeMn\\/NiFe\\/Cu\\/NiFe) sandwiched between thick Nb contact layers. Six spin valves, sputtered at different temperatures, three with thin (3 nm) and three with thick (24 and 30 nm) NiFe layers, were studied. All of the spin-valve layers were smooth and continuous,

  1. A cervelleite-like mineral and other Ag-Cu-Te-S minerals [Ag 2 CuTeS and (Ag,Cu) 2 TeS] in gold-bearing veins in metamorphic rocks of the Cycladic Blueschist Unit, Kallianou, Evia Island, Greece

    Microsoft Academic Search

    Panagiotis Christos Voudouris; Paul G. Spry; Gregory Aarne Sakellaris; Constantinos Mavrogonatos

    2011-01-01

    A cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [Ag2CuTeS, (Ag,Cu)2TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated\\u000a marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults\\u000a are discordant to syn-metamorphic structures and formed during ductile to brittle deformation

  2. Microstructure of columnar crystallites in Ni80Fe20/Cu magnetic multilayers

    NASA Astrophysics Data System (ADS)

    Sun, H. P.; Zhang, Z.; Wang, W. D.; Jiang, H. W.; Lai, W. Y.

    2000-03-01

    We have used electron microscopy to investigate the microstructure of Ni80Fe20/Cu magnetic multilayers which were synthesized by dc magnetron sputtering. Columnar structure was found in the specimen with and without giant magnetoresistance (GMR). All the columnar crystallites (CCs) originate from the Fe buffer layer on silicon wafer or glass substrate and penetrate though all the multilayers up to the surface of the film. The lateral size of the CCs ranges from 10 to 30 nm. Cross-sectional high-resolution electron microscopy study shows that the CCs are single-crystal-like with fcc structure resulting from the epitaxial growth of NiFe and Cu sublayers. Electron diffraction contrast imaging and electron energy filtered elemental mapping confirmed that multilayer nature is maintained throughout the entire NiFe/Cu film. Grain boundaries between CCs can be the most likely place where NiFe or Cu bridging will occur. Columnar structure was also found in a Ta/NiFe/Cu/NiFe/FeMn/Ta spin valve film. The possible influence of the columnar crystalline structure on the GMR related problems is discussed. The microstructure results revealed in this article provide useful information for the GMR property investigation of NiFe/Cu based metallic multilayers.

  3. Processing and aging characteristics of eutectic Sn3.5Ag solder reinforced with mechanically incorporated Ni particles

    Microsoft Academic Search

    F. Guo; J. Lee; S. Choi; J. P. Lucas; T. R. Bieler; K. N. Subramanian

    2001-01-01

    Composite solders offer improved properties compared to non-composite solders. Ni reinforced composite solder was prepared\\u000a by mechanically dispersing 15 vol.% of Ni particles into eutectic Sn-3.5Ag solder paste. The average size of the Ni particle\\u000a reinforcements was approximately 5 microns. The morphology, size and distribution of the reinforcing phase were characterized\\u000a metallographically. Solid-state isothermal aging study was performed on small

  4. Improved Wetting Characteristics in TiO2–Modified Ag-CuO Air Braze Filler Metals

    SciTech Connect

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

    2006-01-01

    In this paper we report on the results of a series of sessile drop experiments designed to examine the effect of TiO2 on the wetting behavior of Ag-CuO air braze filler metals. It was found that TiO2 concentrations as small as 0.5 mol% can significantly decrease the contact angle of Ag-CuO on alumina over a compositional range of 1 – 34mol% CuO. The effect appears to maximize at a copper oxide concentration of ~4 mol% CuO regardless of the titania content.

  5. Transport properties and lithium insertion study in the p-type semi-conductors AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2}

    SciTech Connect

    Sauvage, F. [Department of Chemistry and Materials Research Center, Northwestern University, Evanston, IL 60208-3113 (United States)], E-mail: frederic.sauvage@u-picardie.fr; Munoz-Rojas, D. [Instituto de Ciencia de Materiales de Barcelona, CSIC, Campus UAB, 08193 Bellaterra, Barcelona (Spain)], E-mail: davidmunozrojas@gmail.com; Poeppelmeier, K.R. [Department of Chemistry and Materials Research Center, Northwestern University, Evanston, IL 60208-3113 (United States); Casan-Pastor, N. [Instituto de Ciencia de Materiales de Barcelona, CSIC, Campus UAB, 08193 Bellaterra, Barcelona (Spain)

    2009-02-15

    The transport properties and lithium insertion mechanism into the first mixed valence silver-copper oxide AgCuO{sub 2} and the B-site mixed magnetic delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} were investigated by means of four probes DC measurements combined with thermopower measurements and in situ XRD investigations. AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} display p-type conductivity with Seebeck coefficient of Q=+2.46 and +78.83 {mu}V/K and conductivity values of {sigma}=3.2x10{sup -1} and 1.8x10{sup -4} S/cm, respectively. The high conductivity together with the low Seebeck coefficient of AgCuO{sub 2} is explained as a result of the mixed valence state between Ag and Cu sites. The electrochemically assisted lithium insertion into AgCuO{sub 2} shows a solid solution domain between x=0 and 0.8Li{sup +} followed by a plateau nearby 1.7 V (vs. Li{sup +}/Li) entailing the reduction of silver to silver metal accordingly to a displacement reaction. During the solid solution, a rapid structure amorphization was observed. The delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} also exhibits Li{sup +}/Ag{sup +} displacement reaction in a comparable potential range than AgCuO{sub 2}; however, with a prior narrow solid solution domain and a less rapid amorphization process. AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} provide a discharge gravimetric capacity of 265 and 230 mA h/g above 1.5 V (vs. Li{sup +}/Li), respectively, with no evidence of a new defined phases. - Graphical abstract: Investigation on the transport properties of AgCuO{sub 2} and the new B-site mixed Delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} shows a p-type conductivity of {sigma}=3.2x10{sup -1} and 1.8x10{sup -4} S/cm, respectively. The high conductivity, as a result from a high charge carrier density in AgCuO{sub 2} supports the existence of a mixed valence state between silver and copper. A particular emphasis is also placed on the electrochemical lithium insertion properties into these two materials by in situ XRD measurements to better insight on the Li{sup +} insertion mechanism and also scrutinize possible new compounds electrochemically accessible in the Li-Ag-Cu system.

  6. Creation of microstructured surfaces using Cu-Ni composite electrodeposition and their application to superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Bae, Kong Myeong; Jung, Kyung Kuk; Jeong, Ji Hwan; Ko, Jong Soo

    2014-01-01

    This research analyzed the influence of the electrodeposition ratio of Cu-Ni on the creation of microstructure in Cu-Ni composite electrodeposition, and identified the microstructure generation mechanism with respect to the Cu-Ni electrodeposition ratio. The concentration of CuSO4 in the electrodeposition solution was varied to 0.00, 0.02, 0.04 M to control the electrodeposition ratio of Cu, and the applied voltage was varied to voltages of -0.9, -1.2, -1.5 V, which were applied to control the electrodeposition ratio of Ni. In the composite electrodeposition, Cu ions precipitated intensively at the top of the structure with a short ion diffusion length, and the Ni ions precipitated regularly throughout the entire area charge transferred. Therefore, the structure showed vertically oriented growth when Cu electrodeposition was dominant, and the structure showed isotropic growth when Ni electrodeposition was dominant. On the other hand, Cu ions precipitation concentration at the tip of the grown structure intensified as the height of the structure increased. Therefore, when a structure grows above a certain height, the excess Cu ions precipitate at the top of the grown structure and a cluster structure composed of spherical Cu particles develops. The microstructure produced in the electrodeposition solution with the CuSO4 concentration of 0.04 M had such a high structure generation density and aspect ratio that it was modified to a superhydrophobic surface with a contact angle higher than 150°, and it manifested an excellent self-cleaning ability.

  7. Texture and Microstructure in High Strength Cu-Ag Conductors for DC Magnets National High Magnetic Field Laboratory

    E-print Network

    Weston, Ken

    -deformation of the two phases in nanometer scales via severe plastic deformations. The microstructure shows in the longitudinal section for the CuAg sheet. Copper phase ODF for the rolled sheet at 2 = 5°, 50°, and 85°. The red

  8. 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., E-mail: brmehta@physics.iitd.ac.in [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Govind [Surface Physics Group, National Physical Laboratory (CSIR), New Delhi 110012 (India)

    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.

  9. Efficient enhancement of hydrogen production by Ag/Cu2O/ZnO tandem triple-junction photoelectrochemical cell

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Ren, Feng; Shen, Shaohua; Fu, Yanming; Chen, Chao; Liu, Chang; Xing, Zhuo; Liu, Dan; Xiao, Xiangheng; Wu, Wei; Zheng, Xudong; Liu, Yichao; Jiang, Changzhong

    2015-03-01

    Highly efficient semiconductor photoelectrodes for solar hydrogen production through photocatalytic water splitting are a promising and challenge solution to solve the energy problems. In this work, Ag/Cu2O/ZnO tandem triple-junction photoelectrode was designed and prepared. An increase of 11 times of photocurrent is achieved in the Ag/Cu2O/ZnO photoelectrode comparing to that of the Cu2O film. The high performance of the Ag/Cu2O/ZnO film is due to the optimized design of the tandem triple-junction structure, where the localized surface Plasmon resonance of Ag and the hetero-junctions efficiently absorb solar energy, produce, and separate electron-hole pairs in the photocathode.

  10. Shape memory and superelasticity in polycrystalline Cu-Al-Ni microwires

    E-print Network

    Chen, Ying

    We report a strategy to significantly improve the ductility and achieve large superelastic and shape memory strains in polycrystalline Cu–Al–Ni shape memory alloys that are normally brittle. We use a liquid-phase (Taylor) ...

  11. Effect of Solute Clusters on Stress Relaxation Behavior in Cu-Ni-P Alloys

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Saxey, David W.; Marquis, Emmanuelle A.; Shishido, Hisao; Sumino, Yuya; Cerezo, Alfred; Smith, George D. W.

    2009-12-01

    In this study, the ultrafine structures in Cu-P and Cu-Ni-P alloys have been characterized using a three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM), and the stress relaxation behavior of these alloys has been explored. The results show that low-temperature annealing greatly improved the stress relaxation performance, especially in the Cu-Ni-P alloys. The presence of Ni-P clusters in the Cu-Ni-P alloys has been revealed. The overall improvement in properties has been analyzed in terms of variations in the dislocation density and solute atom cluster density within these materials. It is shown that clusters with small average spacing give rise to significant improvements in the stress relaxation performance, without requiring significant change in the dislocation density.

  12. 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.

  13. Microstructure and Strengthening Mechanisms of Highly Textured Cu/Ni Multilayers 

    E-print Network

    Liu, Yue

    2011-10-21

    In this thesis, I planned to fabricate Cu/Ni metallic multilayers with equal layer thicknesses on different substrates by using magnetic sputtering technique. My objective was to characterize the texture, structure and hardness, in order to study...

  14. Impact-Triggered, Conduit-Type Ni-Cu Mineralisation, Norite Belt, Maniitsoq Structure, West Greenland

    NASA Astrophysics Data System (ADS)

    Garde, A. A.; Pattison, J.; Kokfelt, T.; McDonald, I.; Secher, K.

    2013-09-01

    There are TWO different types of impact-related, magmatic Ni-Cu (-PGE) deposits: the upper-crustal Sudbury type exsolved from the impact melt sheet, and the lower-crustal Maniitsoq type exsolved from contaminated mantle melts.

  15. Electrodeposited NiFeCu/Cu multilayers: Effect of Fe ion concentration on properties

    NASA Astrophysics Data System (ADS)

    Kuru, Hilal; Kockar, Hakan; Alper, Mursel

    2015-01-01

    A series of 125[NiFeCu(3 nm)/Cu(1 nm)] multilayers were electrodeposited on strong (110) textured Cu substrates from electrolytes containing different Fe ion concentrations under potentiostatic control. The compositional analysis by energy dispersive X-ray spectroscopy demonstrated that as the Fe ion concentration in the electrolyte is increased, the Fe content of the multilayers increased. X-ray diffraction measurements indicated that all samples exhibited a face-centred cubic structure with a strong (110) texture as their substrates. The surface images obtained by scanning electron microscopy disclosed that all films have smooth surfaces. Magnetoresistance measurements were carried out at room temperature with magnetic fields up to ±12 kOe. All samples exhibited giant magnetoresistance (GMR) and the maximum GMR value of 5% was obtained in the multilayer grown from the electrolyte containing 0.0036 M Fe ion concentration. The GMR magnitude changed depending on the film contents arising from the variation of the Fe ion concentration in the electrolyte. The magnetic properties studied with the vibrating sample magnetometer showed that the saturation magnetisation changed, and the coercivities decreased with varying Fe ion concentration in the electrolyte. The changes observed in the properties were ascribed to the variations observed in the film composition caused by the Fe ion concentration of the electrolyte.

  16. Nanostructured YbAgCu4 for potentially cryogenic thermoelectric cooling.

    PubMed

    Koirala, Machhindra; Wang, Hui; Pokharel, Mani; Lan, Yucheng; Guo, Chuanfei; Opeil, Cyril; Ren, Zhifeng

    2014-09-10

    We have studied the thermoelectric properties of nanostructured YbAgCu4 materials. A high power factor of ?131 ?W cm(-1) K(-2) has been obtained at 22 K for nanostructured samples prepared by ball milling the arc melted ingot into nanopowder and hot pressing the nanopowder. The implementation of nanostructuring method decreased the thermal conductivity at 42 K by 30-50% through boundary scattering comparing with the previously reported value of polycrystalline YbAgCu4. A peak dimensionless thermoelectric figure-of-merit, ZT, of 0.11 has been achieved at 42 K, which may find potential applications for cryogenic cooling below 77 K. The nanostructuring approach can be extended to other heavy Fermion materials to achieve high power factor and low thermal conductivity and ultimately higher ZT. PMID:25079115

  17. Possible Mesozoic age of Ellenville Zn-Pb-Cu(Ag) deposit, Shawangunk Mountains, New York

    USGS Publications Warehouse

    Friedman, J.D.; Conrad, J.E.; McKee, E.H.; Mutschler, F.E.; Zartman, R.E.

    1994-01-01

    Ore textures, epithermal open-space filling of Permian structures of the Alleghanian orogeny, and largely postorogenic mineralization of the Ellenville, New York, composite Zn-Pb-Cu(Ag) vein system, provide permissive evidence for post-Permian mineralization. Isochron ages determined by 40Ar/39Ar laser-fusion techniques for K-bearing liquid inclusions in main-stage quartz from the Ellenville deposit additionally suggest a Mesozoic time of mineralization, associated with extensional formation of the Newark basin. The best 40Ar/39Ar total-fusion age range is 165 ?? 30 to 193 ?? 35 Ma. The Mesozoic 40Ar/39Ar age agrees with that of many other dated northern Appalachian Zn-Pb-Cu(Ag) deposits with near-matching lead isotope ratios, and adds new evidence of Jurassic tectonism and mineralization as an overprint to Late Paleozoic tectonism at least as far north as Ellenville (lat. 41??43???N). ?? 1994 Springer-Verlag.

  18. Magnetic field effect on autocatalysis: Ag and Cu in concentrated nitric acid.

    PubMed

    Rhen, F M F; Coey, J M D

    2006-03-30

    The partial suppression of corrosion of Ag and Cu in concentrated nitric acid solution by a magnetic field of up to 5 T was studied. The corrosion current density of these metals was found to diminish with magnetic field and rotation speed in a rotating disk electrode experiment. The suppression of corrosion is associated with removal of the catalyst HNO(2) from the electrode and passivation of the electrode surface. The Lorentz force was identified as the driving force responsible for the partial suppression of corrosion. A model based on the partial areas associated with active and passive regions on Ag and Cu electrodes is introduced to explain the dependence of the current density on the applied magnetic field. PMID:16553445

  19. Thermodynamic Description of the Quaternary Ag-Cu-In-Sn System

    NASA Astrophysics Data System (ADS)

    Gierlotka, Wojciech

    2012-01-01

    Due to new regulations, the classic Sn-37Pb (wt.%) solder must be replaced by lead-free material. There are many alloys that could be used instead of this classic lead solder, including quaternary Ag-Cu-In-Sn alloy. The CALPHAD method was used for thermodynamic description of this quaternary system. Good agreement between calculation and available experimental information was found. Solidification of the promising lead-free solder Sn-1.5Ag-0.7Cu-9.5In (wt.%) was performed using the Scheil approach, and good agreement between this calculation and differential thermal analysis results was found. The obtained set of Gibbs energy functions can be used in the future for expanding the quaternary system to high-order ones.

  20. High damping capacity due to two-step phase transformation in Ni–Ti, Ni–Ti–Cu, and Fe–Cr–Mn alloys

    Microsoft Academic Search

    N Igata; N Urahashi; M Sasaki; Y Kogo

    2003-01-01

    In high damping materials, phase transformation is one of the most effective mechanisms. In this study, both Ni–Ti or Ni–Ti–Cu alloy and Fe–Cr–Mn alloy were investigated. Ni–Ti and Ni–Ti–Cu alloy were made by lamination and diffusion process and the phase transformation were B2?B19? in the former and B2?B19?B19? in the latter. The damping capacity was higher in B19 than in

  1. Nearly Constant Electrical Resistance over Large Temperature Range in Cu3NMx (M = Cu, Ag, Au) Compounds

    PubMed Central

    Lu, Nianpeng; Ji, Ailing; Cao, Zexian

    2013-01-01

    Electrical resistance is a material property that usually varies enormously with temperature. Constant electrical resistivity over large temperature range has been rarely measured in a single solid. Here we report the growth of Cu3NMx (M = Cu, Ag, Au) compound films by magnetron sputtering, aiming at obtaining single solids of nearly constant electrical resistance in some temperature ranges. The increasing interstitial doping of cubic Cu3N lattice by extra metal atoms induces the semiconductor-to-metal transition in all the three systems. Nearly constant electrical resistance over 200?K, from room temperature downward, was measured in some semimetallic Cu3NMx samples, resulting from opposite temperature dependence of carrier density and carrier mobility, as revealed by Hall measurement. Cu3NAgx samples have the best performance with regard to the range of both temperature and doping level wherein a nearly constant electrical resistance can be realized. This work can inspire the search of other materials of such a quality. PMID:24169599

  2. Creep and Mechanical Properties of Cu6Sn5 and (Cu,Ni)6Sn5 at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Mu, Dekui; Huang, Han; McDonald, Stuart D.; Nogita, Kazuhiro

    2013-02-01

    Cu6Sn5 is the most common and important intermetallic compound (IMC) formed between Sn-based solders and Cu substrates during soldering. The Cu6Sn5 IMC exhibits significantly different thermomechanical properties from the solder alloys and the substrate. The progress of high-density three-dimensional (3D) electrical packaging technologies has led to increased operating temperatures, and interfacial Cu6Sn5 accounts for a larger volume fraction of the fine-pitch solder joints in these packages. Knowledge of creep and the mechanical behavior of Cu6Sn5 at elevated temperatures is therefore essential to understanding the deformation of a lead-free solder joint in service. In this work, the effects of temperature and Ni solubility on creep and mechanical properties of Cu6Sn5 were investigated using energy-dispersive x-ray spectroscopy and nanoindentation. The reduced modulus and hardness of Cu6Sn5 were found to decrease as temperature increased from 25°C to 150°C. The addition of Ni increased the reduced modulus and hardness of Cu6Sn5 and had different effects on the creep of Cu6Sn5 at room and elevated temperatures.

  3. Formation of a phase separating bulk metallic glass in Cu 40Zr 40Al 10Ag 10 alloy

    Microsoft Academic Search

    Qingsheng Zhang; Wei Zhang; Guoqiang Xie; Akihisa Inoue

    2008-01-01

    The Cu40Zr40Al10Ag10 glassy alloy prepared by different methods was investigated using X-ray diffraction, differential scanning calorimetry and transmission electron microscopy. The bulk sample prepared by copper mold casting exhibits the same XRD pattern and DSC scan as the ribbon sample prepared by melt spinning. TEM shows a homogenous and non-contrast pattern for the Cu40Zr40Al10Ag10 ribbon sample. However, it was found

  4. TL and EPR studies of Cu, Ag and P doped Li2B4O7 phosphor

    Microsoft Academic Search

    N. Can; T. Karali; P. D. Townsend; F. Yildiz

    2006-01-01

    Key characteristics of a newly prepared tissue-equivalent, highly sensitive thermoluminescence dosimeter, Li2B4O7:Cu,Ag,P, are presented. The material was developed at the Institute of Nuclear Sciences, Belgrade, in the form of sintered pellets. A new preparation procedure has greatly increased the sensitivity of the basic copper activated lithium borate and the glow curve of Li2B4O7 : Cu,Ag,P consists of a well-defined main

  5. Template synthesis of M\\/M 2S (M = Ag, Cu) hetero-nanowires by electrochemical technique

    Microsoft Academic Search

    Changhao Liang; Kazuya Terabe; Tsuyoshi Hasegawa; Masakazu Aono

    2006-01-01

    Metal chalcogenide-based mixed ionic–electronic conductors such as Ag2S and Cu2S can be specifically architected for application in nanoelectronic devices. We present a template-confined synthesis of metal chalcogenide (e.g., Ag2S, Cu2S) nanowires for mixed conductor-based nanoelectronics. First, the metal nanowire array was electroplated into pores of a porous alumina membrane. Anodic polarization was then used to transform the metal into the

  6. Phase equilibria and the related properties of Sn-Ag-Cu based Pb-free solder alloys

    Microsoft Academic Search

    I. Ohnuma; M. Miyashita; K. Anzai; X. J. Liu; H. Ohtani; R. Kainuma; K. Ishida

    2000-01-01

    We have recently developed a thermodynamic database for micro-soldering alloys which consists of the elements Pb, Bi, Sn,\\u000a Sb, Cu, Ag, Zn, and In. In this paper, the phase equilibria and the related thermodynamic properties of the Sn-Ag-Cu base\\u000a alloys are presented using this database, alloy systems being one of the promising candidates for Pb-free solders. The isothermal\\u000a section diagrams

  7. Characterization and optimization of Ni and Cu sorption from aqueous solution by Chlorella vulgaris

    Microsoft Academic Search

    Surya Kant Mehta; Jai Prakash Gaur

    2001-01-01

    Sorption of Ni and Cu by Chlorella vulgaris showed the second-order rate kinetics. Change in biomass concentration altered the kinetic parameters of sorption. When biomass concentration was increased from 5 to 1000 mg l?1, the initial rates of sorption of Ni and Cu were reduced by about five- and three-times, respectively. The metal sorption capacity of the test alga was

  8. Effect of Cu surface segregation on properties of NiFe\\/FeMn bilayers

    Microsoft Academic Search

    M. H Li; J. W Cai; G. H Yu; H. W Jiang; W. Y Lai; F. W Zhu

    2002-01-01

    The films of NiFe\\/FeMn with Ta and Ta\\/Cu buffer layers were prepared by magnetron sputtering. Results show that the exchange bias field of NiFe\\/FeMn films with Ta\\/Cu buffer is lower than that of the films with Ta buffer. The crystalline texture, surface roughness and element distribution of these two sets of samples were examined, and there is no apparent difference

  9. Effects of Ni buffer layer on giant magnetoresistance in Co\\/Cu\\/Co sandwich

    Microsoft Academic Search

    Tie Li; Hong-Lie Shen; Qin-Wo Shen; Shi-Chang Zou; Koichi Tsukamoto; Mamoru Okutomi

    2001-01-01

    In order to increase the sensitivity of Co\\/Cu\\/Co sandwiches, different thickness Ni layers were used as buffer layer. It was found that in the Co 55Å\\/Cu 35Å\\/Co 55Å sandwiches with different thickness Ni buffer layers, MR ratios between 3.5% and 5.6% could be obtained, and the coercive forces were about 12Oe. Hence, the maximum field sensitivity could be enhanced to

  10. Effect of chloride concentration range on the corrosion resistance of Cu–xNi alloys

    Microsoft Academic Search

    I. Milošev; M. Metikoš-hukovi?

    1999-01-01

    The anodic behaviour of Cu–xNi alloys and Cu and Ni metals was studied in slightly alkaline solutions containing Cl--ions in the concentration range from 0.01 to 2.0moldm-3. The morphology and composition of the surface films formed by anodic polarization were analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). On the basis of quasi-potentiodynamic polarization data, Ec

  11. Crossover from in-plane to perpendicular magnetization in ultrathin Ni\\/Cu(001) films

    Microsoft Academic Search

    B. Schulz; K. Baberschke

    1994-01-01

    The easy axis of magnetization in Ni\\/Cu(001) films exhibits a crossover from in-plane to perpendicular orientation with increasing film thickness. This reorientation at ~=7 monolayers, observed by ferromagnetic resonance, is substantially different from previous findings for Fe and Co films and can be extrapolated from thin-film data. The artificial lattice structure of Ni on Cu yields within magnetoelasticity theory a

  12. A Study of the Adsorption of Ni(II) and Cu(II) by Clay Minerals

    Microsoft Academic Search

    M. H. Koppelman; J. G. DILLARD

    1977-01-01

    The adsorption of Ni(II) and Cu(II) on to the clay minerMs kaolinite, chlorite, and illite has been investigated. The quantity of Ni(II) at pH 6 and Cu(II) at pH 5 adsorbed has been found to vary in the manner chlorite > illite > kaolinite. Examination of the mode of bonding of the metal ions to the clay minerals using X-ray

  13. Microstructure-property relationships in Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 2

    NASA Technical Reports Server (NTRS)

    Langan, T. J.; Pickens, J. R.

    1991-01-01

    The microstructure and mechanical properties of the ultrahigh strength Al-Cu-Li-Ag-Mg alloy, Weldalite (tm) 049, were studied. Specifically, the microstructural features along with tensile strength, weldability, Young's modulus and fracture toughness were studied for Weldalite (tm) 049 type alloys with Li contents ranging from 1.3 to 1.9 wt. pct. The tensile properties of Weldalite 049 and Weldalite 049 reinforced with TiB2 particles fabricated using the XD (tm) process were also evaluated at cryogenic, room, and elevated temperatures. In addition, an experimental alloy, similar in composition to Weldalite 049 but without the Ag+Mg, was fabricated. The microstructure of this alloy was compared with that of Weldalite 049 in the T6 condition to assess the effect of Ag+Mg on nucleation of strengthening phases in the absence of cold work.

  14. Possible Mesozoic age of Ellenville Zn-Pb-Cu(Ag) deposit, Shawangunk Mountains, New York

    Microsoft Academic Search

    J. D. Friedman; J. E. Conrad; E. H. McKee; F. E. Mutschler; R. E. Zartman

    1994-01-01

    Ore textures, epithermal open-space filling of Permian structures of the Alleghanian orogeny, and largely postorogenic mineralization of the Ellenville, New York, composite Zn-Pb-Cu(Ag) vein system, provide permissive evidence for post-Permian mineralization. Isochron ages determined by 40Ar\\/39Ar laser-fusion techniques for K-bearing liquid inclusions in main-stage quartz from the Ellenville deposit additionally suggest a Mesozoic time of mineralization, associated with extensional formation

  15. [Determination of Ag, Cu, Zn and Cd in silver brazing filler metals by ICP-AES].

    PubMed

    Yang, X

    1997-06-01

    A method of simultaneous and direct determination for Ag, Cu, Zn and Cd in silver brazing filler metals by ICP-AES is reported. The spectral interferences and effect of acidity have been investigated. Working conditions were optimized. The method has been applied to the analysis of silver brazing filler metals with RSD of 4-7% and recovery of 94-105%. This method was accurate, simple and rapid. PMID:15810223

  16. Anatomy of porphyry-related Au-Cu-Ag-Mo mineralised systems: Some exploration implications

    Microsoft Academic Search

    Greg Corbett

    Summary Analyses of exploration and mining case studies as well as magmatic arc geothermal systems have facilitated an understanding of the implications to explorationists of the anatomy of porphyry related Au-Cu-Mo-Ag mineralising systems. Deeply eroded magmatic source rocks tend to host sub economic mineralisation, which may become focused in the highly prospective in overlying apophyses to spine-like polyphasal intrusions. Buried

  17. Board-level reliability of lead-free SnAgCu solder joint

    Microsoft Academic Search

    Jian-Shu Wu; Shan-Pu Yu; I-Hsuan Peng; Jong-Lih Wang; B. Chung

    2002-01-01

    Due to environmental concerns, the need for lead-free solutions in electronic components and systems is receiving increasing attention within the semiconductor and electronics industries. Sn-Ag-Cu systems are some of the more promising materials to replace the eutectic Sn-Pb solder. In this paper, a chip scale package assembled on board test and a notebook motherboard surface mount assembly were used to

  18. Oscillations of giant magnetoresistance in Cu\\/AgCo granular multilayers

    Microsoft Academic Search

    Y. Luo; M. Moske; A. Käufler; T. Lorenz; K. Samwer

    1997-01-01

    A novel granular multilayer structure consisting of magnetic granular AgCo layers and non-magnetic Cu spacer layers is introduced to study their magnetotransport properties. The results are similar to those obtained from both conventional multilayers and granular single-films, but with a notable enhancement of low-field sensitivity compared to these structures. This can be attributed to a weak antiferromagnetic coupling across the

  19. Thermodynamic modeling of the Cu–Ag–Au system using the cluster\\/site approximation

    Microsoft Academic Search

    W. Cao; Y. A. Chang; J. Zhu; S. Chen; W. A. Oates

    2007-01-01

    The cluster\\/site approximation (CSA), which takes short-range order (SRO) into account in a computationally efficient manner in configurational entropy calculations on alloys, has been used to describe the fcc-type phases in the Cu–Ag–Au system. The CSA-calculated phase diagrams and thermodynamic properties are in good agreement with the available experimental data. Importantly, this CSA description requires no reciprocal interaction parameters as

  20. Stress-induced and atomic ordering in 18-carat Au–Cu–Ag alloys

    Microsoft Academic Search

    John Hennig; Daniele Mari; Robert Schaller

    2009-01-01

    Atomic ordering and stress-induced ordering (Zener relaxation) were studied in a series of 18-carat (75wt%) yellow gold alloys (Au–Cu–Ag) by means of isothermal mechanical spectroscopy with a forced torsion pendulum at low frequencies. In the high-temperature solid solution, the Zener peak increases critically according to a Curie–Weiss type law when approaching the transition temperature to the ordered phase from above,

  1. Investigation of the ternary phase diagram of mechanically alloyed FeCuAg

    Microsoft Academic Search

    N. S. Cohen; E. Ahlswede; J. D. Wicks; Q. A. Pankhurst

    1997-01-01

    The structural and magnetic properties of mechanically alloyed Fe - Cu - Ag at room temperature have been investigated using 0953-8984\\/9\\/15\\/016\\/img1 Mössbauer spectroscopy, x-ray diffraction and differential scanning calorimetry. The elements are naturally immiscible, but through prolonged and energetic ball milling (70 hours at 600 rpm) one can make metastable alloys, the structure of which depends on the elemental composition.

  2. First-principles calculation of the Ag-Cu phase diagram

    Microsoft Academic Search

    J. M. Sanchez; J. P. Stark; V. L. Moruzzi

    1991-01-01

    Total-energy band calculations based on the augmented-spherical-wave method are used to determine the binding curves of the elements and of selected compounds in the Ag-Cu system. The calculated total energies, together with vibrational free energies determined by a Debye-Grüneisen analysis of the binding curves and configurational entropies determined by the cluster variation method, are used to calculate the solid-state portion

  3. Developing a lead-free solder alloy Sn-Bi-Ag-Cu by mechanical alloying

    Microsoft Academic Search

    C. M. L. Wu; M. L. Huang; J. K. L. Lai; Y. C. Chan

    2000-01-01

    A new lead free alloy, Sn-6Bi-2Ag-0.5Cu, has been developed by mechanical alloying and has great potential as a lead-free solder system. Initial trials on the manufacture of solder joints with this alloy revealed that a high quality bond with copper could be formed. Its melting range of 193.87°C to 209.88°C is slightly higher than that of eutectic tin-lead solder. Examination

  4. Cyclic stress-strain characteristics of Ti?Ni and Ti?Ni?Cu shape memory alloys

    Microsoft Academic Search

    B. Strnadel; S. Ohashi; H. Ohtsuka; T. Ishihara; S. Miyazaki

    1995-01-01

    The authors have examined the responses of three types of Ti?Ni and three types of Ti?Ni?Cu shape memory alloys in a pseudoelastic state to mechanical cycling in hard cycles with a constant emax and in soft cycles with a constant ?max. It was found that the transformation stress of the B2 parent phase into martensite and the hysteresis (or the

  5. Comparative internal friction and modulus evolutions in Ni-Ti and Ni-Ti-Cu shape memory alloys

    Microsoft Academic Search

    K. Goubaa; M. Masse; G. Bouquet

    1992-01-01

    Internal friction and modulus measurements are performed for the purpose of a comparative study between the structural evolutions occurring, under the effect of the temperature, in two kinds of shape memory alloys: Ni-Ti and Ni-Ti-Cu. Modulus evolutions giving information about the changes in the relative percentages of martensitic and B2 high temperature phases, are useful for the determination of ``start''

  6. Itinerant-Electron Theory of Pressure Effects on Ferromagnetic Transition Temperatures: Ni and Ni-Cu Alloys

    Microsoft Academic Search

    N. D. Lang; H. Ehrenreich

    1968-01-01

    The rate of change of Curie temperature with pressure is calculated for Ni and Ni-Cu alloys by considering the pressure-induced shift of the pole in the uniform static spin susceptibility. The short-range Hamiltonian of Hubbard, Kanamori, and Gutzwiller is employed to describe the interactions among d electrons and, following Kanamori, these interactions are treated in the t approximation. The spin

  7. Structure and texture of filamentous carbons produced by methane decomposition on NI and NI-CU catalysts

    Microsoft Academic Search

    V. B. Fenelonov; A. Yu. Derevyankin; L. G. Okkel; L. B. Avdeeva; V. I. Zaikovskii; E. M. Moroz; A. N. Salanov; N. A. Rudina; V. A. Likholobov; Sh. K. Shaikhutdinov

    1997-01-01

    Adsorption methods, mercury porosimetry, electron and tunneling microscopy, and diffraction techniques were used to study filamentous carbon produced by methane decomposition on coprecipitated Ni\\/alumina and Ni-Cu\\/alumina catalysts. The porous structure of carbons was generally classified as follows: 1) micropores on the filament surface; 2) mesopores produced by filament surface roughness; 3) meso- and macropores in dense and loosely packed regions

  8. Electromigration induced Kirkendall void growth in Sn-3.5Ag/Cu solder joints

    SciTech Connect

    Jung, Yong; Yu, Jin, E-mail: jinyu@kaist.ac.kr [Department of Materials Science and Engineering, Electronic Packaging Laboratory, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2014-02-28

    Effects of electric current flow on the Kirkendall void formation at solder joints were investigated using Sn-3.5Ag/Cu joints specially designed to have localized nucleation of Kirkendall voids at the Cu{sub 3}Sn/Cu interface. Under the current density of 1?×?10{sup 4}?A/cm{sup 2}, kinetics of Kirkendall void growth and intermetallic compound thickening were affected by the electromigration (EM), and both showed the polarity effect. Cu{sub 6}Sn{sub 5} showed a strong susceptibility to the polarity effect, while Cu{sub 3}Sn did not. The electromigration force induced additional tensile (or compressive) stress at the cathode (or anode), which accelerated (or decelerated) the void growth. From the measurements of the fraction of void at the Cu{sub 3}Sn/Cu interface on SEM micrographs and analysis of the kinetics of void growth, the magnitude of the local stress induced by EM was estimated to be 9?MPa at the anode and ?7 MPa at the cathode.

  9. Band-structure anomalies of the chalcopyrite semiconductors CuGaX2 versus AgGaX2 (X=S and Se) and their alloys

    E-print Network

    Gong, Xingao

    Band-structure anomalies of the chalcopyrite semiconductors CuGaX2 versus AgGaX2 (X=S and Se-principles calculations for the structural and electronic properties of chalcopyrite semiconductors AgGaS2, AgGaSe2, Cu of the chalcopyrites relative to their binary analogs. The origin of the band structure anomalies observed

  10. Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial Ag–Cu nanoparticles

    SciTech Connect

    Taner-Camc?, Merve; Suzer, Sefik, E-mail: suzer@fen.bilkent.edu.tr [Department of Chemistry, Bilkent University, 06800 Ankara (Turkey)

    2014-03-15

    Ultrathin films consisting of polyelectrolyte layers prepared by layer-by-layer deposition technique and containing also Ag and Cu nanoparticles exhibit superior antibacterial activity toward Escherichia coli. These films have been investigated with XPS measurements under square wave excitation at two different frequencies, in order to further our understanding about the chemical/physical nature of the nanoparticles. Dubbed as dynamical XPS, such measurements bring out similarities and differences among the surface structures by correlating the binding energy shifts of the corresponding XPS peaks. Accordingly, it is observed that the Cu2p, Ag3d of the metal nanoparticles, and S2p of cysteine, the stabilizer and the capping agent, exhibit similar shifts. On the other hand, the C1s, N1s, and S2p peaks of the polyelectrolyte layers shift differently. This finding leads us the claim that the Ag and Cu atoms are in a nanoalloy structure, capped with cystein, as opposed to phase separated entities.

  11. Hydrothermal ethanol conversion on Ag, Cu, Au/TiO2

    NASA Astrophysics Data System (ADS)

    Mai, Do Tkhyui; Mikhalenko, I. I.; Pylinina, A. I.

    2014-10-01

    The effect UV irradiation and silver, copper, and gold ions (M z+) supported on titania (anatase) have on the activity of M/TiO2 samples in ethanol conversion at 150-400°C is examined. After UV irradiation, the yields of acetaldehyde and ethylene increase for TiO2 and Ag/TiO2 samples, while the activity of Cu2+/TiO2 decreases. The activation energy of ethanol dehydration declines in the order TiO2 > Au3+ > Cu2+ > Ag+ and correlates linearly with a reduction in the radius of M z+ in crystal. The number of acidic sites on a M/TiO2 surface titrated via pyridine adsorption grows upon the introduction of M. Unlike Cu2+/TiO2, these sites are not activated after the irradiation of TiO2, Ag+/TiO2, and Au3+/TiO2. According to IR spectral data on adsorbed pyridine, all samples contain Lewis and Brönsted acidic sites.

  12. 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.

  13. Intermetallic Formation and Fluidity in Sn-Rich Sn-Cu-Ni Alloys

    NASA Astrophysics Data System (ADS)

    Gourlay, C. M.; Nogita, K.; Read, J.; Dahle, A. K.

    2010-01-01

    This paper investigates the phase equilibria and solidification behavior of Sn-Cu-Ni alloys with compositions in the range of 0 wt.% to 1.5 wt.% Cu and 0 wt.% to 0.3 wt.% Ni. The isothermal section at 268°C in the Sn-rich corner was determined. No evidence for a ternary phase was found, and the section is in good agreement with past experimental studies that report wide solubility ranges for (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4. The vacuum fluidity test was applied to compositions that are liquid at 268°C to map the variation in microstructure and flow behavior with composition in this system. Significant variations in fluidity length were measured among the Sn-Cu-Ni alloys, and the variations correlate with the microstructure that develops during solidification. The generated fluidity map enables the selection of Sn-Cu-Ni solder compositions that exhibit good fluidity behavior during solidification and form near-eutectic microstructures.

  14. Temperature Dependence Of Core Loss In Cobalt Substituted Ni-Zn-Cu A. Lucas 1,2

    E-print Network

    Paris-Sud XI, Université de

    1 Temperature Dependence Of Core Loss In Cobalt Substituted Ni-Zn-Cu Ferrites A. Lucas 1,2 , R dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead to a compensation of the magneto- crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on the cobalt

  15. 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.

  16. Complete oxidation of methane over Ag- and Cu-modified cerium and zirconium oxides

    NASA Astrophysics Data System (ADS)

    Kundakovic, Ljiljana

    Low temperature oxidation of methane is an area in catalysis that, despite the large number of catalytic systems studied, does not yet have an adequate solution. The exhaust gas from natural gas burning devices (gas turbines and natural gas vehicles), contains unconverted methane which is emitted into the atmosphere (currently unregulated). Methane is the most refractory of all hydrocarbons, and its activation requires temperatures higher than the typical exhaust temperatures (350-400sp°C). In this work, ceria- and zirconia-supported Ag and CuO catalysts were studied for the complete oxidation of methane. Catalysts were typically tested under excess oxygen and high space velocity (72,000 hsp{-1}). The reaction kinetics were measured over selected catalysts. Hsb2- and CHsb4- TPR and oxygen uptake measurements were used to characterize the catalyst reduction properties. XRD, STEM/EDX and HRTEM were used to characterize the catalyst structure. The oxidation state of various active species present was identified by XPS and UV-VIS DR spectrometry. Ceria- and zirconia-supported Ag and CuO catalysts are very active and stable catalysts for the complete oxidation of carbon monoxide and methane. When ceria is used as an active catalyst support, its activity depends strongly on its structure. Nanocrystalline ceria, stabilized by dopants such as La or Zr, is highly reducible and structurally defective. Our results indicate that surface oxygen species present under reaction conditions are the active sites for methane activation. Activity in the complete oxidation of methane is related to ceria crystal size and reducibility of surface oxygen species. The addition of a transition metal (Ag) or a metal oxide (CuO) in low amounts increases the low temperature reducibility of ceria and enhances the catalyst oxidation activity. On the other hand, both Ag and CuO are active catalysts for the complete oxidation of methane. These were studied separately on inert zirconia support. A strong correlation of the transition metal/metal oxide state and dispersion with the catalyst activity was observed. Isolated Ag ions and small Ag nanoparticles (<5 nm) are both poor catalysts for the complete oxidation of methane. The turnover frequency for methane oxidation was increased by an order of magnitude as the Ag particle size increased from 5 to 10 nm, as seen by HRTEM. Similar catalytic behavior was found in copper oxide-containing zirconia. Small copper clusters (few nm) which are highly defective and do not have the identity of CuO are less active than larger CuO particles for the complete oxidation of methane. In view of the importance of surface oxygen species in methane activation, the observed structure sensitivity of methane oxidation in both the supported metal (Ag) and metal oxide (CuOx) systems is discussed in terms of oxygen adsorption on the metal and reduction properties of the metal oxide, respectively.

  17. High salinity volatile phases in magmatic Ni-Cu-platinum group element deposits

    NASA Astrophysics Data System (ADS)

    Hanley, J. J.; Mungall, J. E.

    2004-12-01

    The role of "deuteric" fluids (exsolved magmatic volatile phases) in the development of Ni-Cu-PGE (platinum group element) deposits in mafic-ultramafic igneous systems is poorly understood. Although considerable field evidence demonstrates unambiguously that fluids modified most large primary Ni-Cu-PGE concentrations, models which hypothesize that fluids alone were largely responsible for the economic concentration of the base and precious metals are not widely accepted. Determination of the trace element composition of magmatic volatile phases in such ore-forming systems can offer considerable insight into the origin of potentially mineralizing fluids in such igneous environments. Laser ablation ICP-MS microanalysis allows researchers to confirm the original metal budget of magmatic volatile phases and quantify the behavior of trace ore metals in the fluid phase in the absence of well-constrained theoretical or experimental predictions of ore metal solubility. In this study, we present new evidence from major deposits (Sudbury, Ontario, Canada; Stillwater Complex, Montana, U.S.A.) that compositionally distinct magmatic brines and halide melt phases were exsolved from crystallizing residual silicate melt and trapped within high-T fluid conduits now comprised of evolved rock compositions (albite-quartz graphic granite, orthoclase-quartz granophyre). Petrographic evidence demonstrates that brines and halide melts coexisted with immiscible carbonic phases at the time of entrapment (light aliphatic hydrocarbons, CO2). Brine and halide melt inclusions are rich in Na, Fe, Mn, K, Pb, Zn, Ba, Sr, Al and Cl, and homogenize by either halite dissolution at high T ( ˜450-700° C) or by melting of the salt phase (700-800° C). LA-ICPMS analyses of single inclusions demonstrate that high salinity volatile phases contained abundant base metals (Cu, Fe, Sn, Bi) and precious metals (Pt, Pd, Au, Ag) at the time of entrapment. Notably, precious metal concentrations in the inclusions are comparable to and often exceed the economic concentrations of the metals within the ores themselves. As a consequence of these results, current genetic models must be revised to consider the role played by hydrous saline melts and magmatic brines in deposit development, and the potential for interaction and competition between sulfide liquids (or PGE-bearing sulfide minerals) and hydrosaline volatiles for available PGE and Au in a crystallizing mafic igneous system must be critically evaluated.

  18. Low-Temperature Growth of Carbon Nanofiber by Thermal Chemical Vapor Deposition Using CuNi Catalyst

    NASA Astrophysics Data System (ADS)

    Aoki, Katsunori; Yamamoto, Tetsurou; Furuta, Hiroshi; Ikuno, Takashi; Honda, Shinichi; Furuta, Mamoru; Oura, Kenjiro; Hirao, Takashi

    2006-06-01

    Thermal-CVD was carried out for the low-temperature growth of carbon nanofibers (CNFs) using a CuNi alloy catalyst film with a thickness of 5 nm on Si in a gas mixture of C2H2 and He (C2H2/He=3/12 sccm). The experimental results obtained using the CuNi alloy catalyst film were compared with those obtained using the Fe, Ni, and FeNi catalyst films with the same thickness of 5 nm. It was shown that an amorphous CNF with a diameter of 20 nm can be grown even at 400 °C using the CuNi catalyst film, but not using the Fe, Ni and FeNi catalysts. A reduction in the growth temperature of CNFs was considered to be achieved using small CuNi catalyst particles with a comparatively smaller surface energy than FeNi catalyst particles.

  19. Influence of contact geometry and current on effective erosion of Cu-Cr, Ag-WC, and Ag-Cr vacuum contact materials

    Microsoft Academic Search

    Michael Bruce Schulman; Paul G. Slade; Leslie D. Loud; Wangpei Li

    1999-01-01

    Effective ac erosion rates were measured for Cu-Cr, Ag-WC, and Ag-Cr butt-type contacts in vacuum contactors, using half-cycle current pulses of 450-600 A rms. The polarity was changed for each operation to ensure uniform effects for both contacts. The contacts parted during the rising current, with the full gap set to 10-30% of the contact diameter. The effective linear volume

  20. Photocatalytic performances and activities of Ag-doped CuFe{sub 2}O{sub 4} nanoparticles

    SciTech Connect

    Zhu, Zhengru, E-mail: zhengruzhu@gmail.com [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China); State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Xinyong; Zhao, Qidong [State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Yonghua; Sun, Caizhi; Cao, Yongqiang [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China)

    2013-08-01

    Graphical abstract: - Highlights: • CuFe{sub 2}O{sub 4} nanocrystals were synthesized by a co-precipitation method. • Ag/CuFe{sub 2}O{sub 4} catalyst was prepared by the wetness impregnation strategy. • The structural properties of Ag/CuFe{sub 2}O{sub 4} were investigated by XRD, TEM, DRS, and XPS techniques. • Ag/CuFe{sub 2}O{sub 4} has higher photocatalytic activity. - Abstract: In this work, CuFe{sub 2}O{sub 4} nanoparticles were synthesized by a chemical co-precipitation route. The Ag/CuFe{sub 2}O{sub 4} catalyst was prepared based on the CuFe{sub 2}O{sub 4} nanoparticles by the incipient wetness impregnation strategy, which showed excellent photoelectric property and catalytic activity. The structural properties of these samples were systematically investigated by X-ray powder diffraction (XRD), transmission electronic microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) techniques. The photo-induced charge separation in the samples was demonstrated by surface photovoltage (SPV) measurement. The photocatalytic degradation of 4-CP by the Ag/CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4} samples were comparatively studied under xenon lamp irradiation. The results indicate that the Ag/CuFe{sub 2}O{sub 4} sample exhibited the higher efficiency for the degradation of 4-CP.

  1. Nanostructure, interfaces, and magnetic properties in giant magnetoresistive NiO-Co-Cu-based spin valves

    E-print Network

    Chopra, Harsh Deep

    -biased antiferromagnetic-ferromagnetic system such as FeMn-NiFe. In addition to the contribution to pinning by exchange an . In the present study, dc-magnetron sputtered NiO-Co- Cu-based top and symmetrical spin valves were investigated

  2. Characterization of carbon nanofibers grown over Ni and Ni-cu catalysts.

    PubMed

    Echegoyen, Y; Suelves, I; Lázaro, M J; Moliner, R; Palacios, J M; Müller, J O; Su, D; Schlögl, R

    2009-07-01

    Carbon nanofibers were obtained by thermo-catalytic decomposition of methane at 700 degrees C over Ni and Ni-Cu catalysts prepared by different methods (co-precipitation, impregnation and fusion) and using either Al or Mg as textural promoter. Characterization of the carbon thus obtained was performed by N2 adsorption isotherms (BET surface area), temperature programmed desorption (TPD), temperature programmed oxidation (TPO), X-ray diffraction, Raman spectrometry, and electron microscopy SEM and TEM. The carbon obtained possesses high crystallinity and poor surface chemistry. The crystallinity is enhanced when using Mg as textural promoter and in the presence of copper. SEM and TEM examinations show that the fibers have fishbone structure and they grow generally from one nickel particle (tip growing) although there are some bidirectional growing. Copper-doping lead to the formation of thicker filaments and promotes the formation of bamboo-like structures. Catalyst particles higher than 100 nm do not promote the formation of nanofibers and the carbon deposits as uniform coatings. PMID:19916425

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

    DOEpatents

    Lin, Xianghong (Pasadena, CA); Peker, Atakan (Pasadena, CA); Johnson, William L. (Pasadena, CA)

    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.

  4. Effect of partial substitution of Ni and Zn for Cu in CaBaLaCu 3O 7-? superconductor

    NASA Astrophysics Data System (ADS)

    Gunasekaran, R. A.; Gopalakrishnan, I. K.; Yakhmi, J. V.; Iyer, R. M.; Tomy, C. V.; Malik, S. K.

    1991-09-01

    Superconducting behaviour of the tetragonal superconductor CaBaLaCu 3O 7-? ( Tc = 70 K) has been studied as a function of substitution of Ni and Zn for Cu. Both electrical resistivity and AC susceptibility measurements show that Tc decreases monotonically with increasing concentration of the substituent ion, within the composition range where the samples remain single phase, although Zn suppresses Tc more strongly than Ni for equivalent concentrations. It is argued that the suppression of Tc in this system cannot be explained by the Abrikosov-Gorkov mechanism alone.

  5. Mechanism of phenol oxidation by heterodinuclear Ni Cu bis(?-oxo) complexes involving nucleophilic oxo groups

    PubMed Central

    Kundu, Subrata; Miceli, Enrico; Farquhar, Erik R.

    2014-01-01

    Oxidation of phenols by heterodinuclear CuIII(?-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

  6. Mechanism of phenol oxidation by heterodinuclear Ni Cu bis(?-oxo) complexes involving nucleophilic oxo groups.

    PubMed

    Kundu, Subrata; Miceli, Enrico; Farquhar, Erik R; Ray, Kallol

    2014-03-21

    Oxidation of phenols by heterodinuclear Cu(III)(?-O)2Ni(III) 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

  7. Electrodeposition of high corrosion resistance Cu\\/Ni–P coating on AZ91D magnesium alloy

    Microsoft Academic Search

    Shan Zhang; Fahe Cao; Linrong Chang; Junjun Zheng; Zhao Zhang; Jianqing Zhang; Chunan Cao

    2011-01-01

    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

  8. Magnetic properties of high permeability NiFeMo\\/Cu composite wires

    Microsoft Academic Search

    H. L. Seet; X. P. Li; H. J. Neo; K. S. Lee

    2008-01-01

    The objective of this study is to obtain an optimized layer of NiFeMo in terms of magnetic properties, by electrodeposition, for the application of magnetic sensors. In this study, supermalloy material, NiFeMo, was deposited onto 20?m in diameter copper wires by direct current electrodeposition. Various composition ratios of NiFeMo\\/Cu composite wires were obtained by varying the electrolyte solution concentration and

  9. Optical behavior and structural property of CuAlS? and AgAlS? wide-bandgap chalcopyrites.

    PubMed

    Ho, Ching-Hwa; Pan, Chia-Chi

    2014-08-01

    Single crystals of CuAlS? and AgAlS? were grown by chemical vapor transport method using ICl? as the transport. The as-grown CuAlS? crystals reveal transparent and light-green color. Most of them possess a well-defined (112) surface. The AgAlS? crystals essentially show transparent and white color in vacuum. As the AgAlS? was put into the atmosphere, the crystal surface gradually darkened and became brownish because of the surface reaction with humidity or hydrogen gas. After a long-term chemical reaction process, the AgAlS? will transform into a AgAlO? oxide with yellow color. From x-ray diffraction measurements, both CuAlS? and AgAlS? as-grown crystals show single-phase and isostructural to a chalcopyrite structure. The (112) face is more preferable for the formation of the chalcopyrite crystals. The energies of interband transitions of the CuAlS? and AgAlS? were determined accurately by thermoreflectance measurements in a wide energy range of 2-6 eV. The valence-band electronic structures of CuAlS? and AgAlS? have been detailed and characterized using polarized-thermoreflectance measurements in the temperature range between 30 and 300 K. The band-edge transitions belonging to the E(?) and E(?) polarizations have been, respectively, identified. The band edge of AgAlS? is near 3.2 eV while that of AgAlS? is about 3.5 eV. On the basis of the experimental analyses, optical and sensing behaviors of the chalcopyrite crystals have been realized. PMID:25090358

  10. Enhancement of anammox performance by Cu(II), Ni(II) and Fe(III) supplementation.

    PubMed

    Chen, Hui; Yu, Jin-Jin; Jia, Xiu-Ying; Jin, Ren-Cun

    2014-12-01

    This study explored the influence of metal ion addition on specific anaerobic ammonium oxidation activity (SAA). Batch assays were used to demonstrate the enhancement of the SAA upon the addition of Cu2+, Ni2+ and Fe3+. The SAA was enhanced by 41.0% when the Cu2+ concentration was below 1 mg L?1, while it was improved by 63.5% at Ni2+ concentrations below 1.74 mg L?1. An enhancement of 533.2% was obtained when 3.68 mg L?1 Fe3+ was supplied. The effects of Fe3+, Cu2+ and Ni2+ on the SAA were analyzed and optimized by a response surface methodology, which demonstrated that the interaction between Fe3+ and Cu2+ was significant and that 6.61 mg Fe3+ L?1, 1.18 mg Cu2+ L?1 and 1.11 mg Ni2+ L?1 were the optimal values for metal dosing. Subsequently, an Fe3+–Cu2+–Ni2+ continuous test was carried out under optimal conditions and revealed that the addition of Fe3+, Cu2+ and Ni2+ could stimulate the reactor potential at ambient temperature. The maximum nitrogen removal rate (NRR) of the test reactor was 52.8% higher than that of the control reactor (8.1 versus 5.3 kg N m?3 d?1). Moreover, a continuous test conducted by adding Fe3+ achieved an average nitrogen removal efficiency and maximum NRR of 67.4% and 4.9 kg N m?3 d?1, respectively, while the corresponding values of the control test were 64.7% and 4.1 kg N m?3 d?1, respectively. Altogether, appropriate dosages of Cu2+, Ni2+ and Fe3+ can significantly enhance the SAA and improve the reactor capacity at ambient temperature. PMID:25461925

  11. Element-specific study of epitaxial NiO/Ag/CoO/Fe films grown on vicinal Ag(001) using photoemission electron microscopy

    SciTech Connect

    Meng, Y.; Li, J.; Tan, A.; Jin, E.; Son, J.; Park, J. S.; Doran, A.; Young, A. T.; Scholl, A.; Arenholz, E.; Wu, J.; Hwang, C.; Zhao, H. W.; Qiu, Z. Q.

    2011-01-10

    NiO/Ag/CoO/Fe single crystalline films are grown epitaxially on a vicinal Ag(001) substrate using molecular beam epitaxy and investigated by photoemission electron microscopy. We find that after zero-field cooling, the in-plane Fe magnetization switches from parallel to perpendicular direction of the atomic steps of the vicinal surface at thinner CoO thickness but remains in its original direction parallel to the steps at thicker CoO thickness. CoO and NiO domain imaging result shows that both CoO/Fe and NiO/CoO spins are perpendicularly coupled, suggesting that the Fe magnetization switching may be associated with the rotatable-frozen spin transition of the CoO film.

  12. Rapid direct conversion of Cu2-xSe to CuAgSe nanoplatelets via ion exchange reactions at room temperature

    NASA Astrophysics Data System (ADS)

    Moroz, N. A.; Olvera, A.; Willis, G. M.; Poudeu, P. F. P.

    2015-05-01

    The use of template nanostructures for the creation of photovoltaic and thermoelectric semiconductors is becoming a quickly expanding synthesis strategy. In this work we report a simple two-step process enabling the formation of ternary CuAgSe nanoplatelets with a great degree of control over the composition and shape. Starting with hexagonal nanoplatelets of cubic Cu2-xSe, ternary CuAgSe nanoplatelets were generated through a rapid ion exchange reaction at 300 K using AgNO3 solution. The Cu2-xSe nanoplatelet template and the final CuAgSe nanoplatelets were analyzed by electron microscopy and X-ray diffraction (XRD). It was found that both the low temperature pseudotetragonal and the high temperature cubic forms of CuAgSe phase were created while maintaining the morphology of the Cu2-xSe nanoplatelet template. Thermal and electronic transport measurements of hot-pressed pellets of the synthesized CuAgSe nanoplatelets showed a drastic reduction in the thermal conductivity and a sharp transition from n-type (S = -45 ?V K-1) to p-type (S = +200 ?V K-1) semiconducting behavior upon heating above the structural transition from the low temperature orthorhombic to the high temperature super-ionic cubic phase. This simple reaction process utilizing a template nanostructure matrix represents an energy efficient, cost-efficient, and versatile strategy to create interesting materials with lower defect density and superior thermoelectric performance.The use of template nanostructures for the creation of photovoltaic and thermoelectric semiconductors is becoming a quickly expanding synthesis strategy. In this work we report a simple two-step process enabling the formation of ternary CuAgSe nanoplatelets with a great degree of control over the composition and shape. Starting with hexagonal nanoplatelets of cubic Cu2-xSe, ternary CuAgSe nanoplatelets were generated through a rapid ion exchange reaction at 300 K using AgNO3 solution. The Cu2-xSe nanoplatelet template and the final CuAgSe nanoplatelets were analyzed by electron microscopy and X-ray diffraction (XRD). It was found that both the low temperature pseudotetragonal and the high temperature cubic forms of CuAgSe phase were created while maintaining the morphology of the Cu2-xSe nanoplatelet template. Thermal and electronic transport measurements of hot-pressed pellets of the synthesized CuAgSe nanoplatelets showed a drastic reduction in the thermal conductivity and a sharp transition from n-type (S = -45 ?V K-1) to p-type (S = +200 ?V K-1) semiconducting behavior upon heating above the structural transition from the low temperature orthorhombic to the high temperature super-ionic cubic phase. This simple reaction process utilizing a template nanostructure matrix represents an energy efficient, cost-efficient, and versatile strategy to create interesting materials with lower defect density and superior thermoelectric performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01451d

  13. Phase transformations in Cu-Sn alloys containing Ni, Al, Ge, and In

    Microsoft Academic Search

    M. I. Zakharova; G. N. Dudchenko

    1981-01-01

    After quenching from 700‡C and aging, Cu-Sn alloys containing Ni and Al were found to have a precipitation of?-solid solution, with a DO3 type of ordering, of metastable a',O, and d' phases. It was established that theO phase has an O4 type of ordering while the a' phase has the Cu3Ti type. Observations revealed that Cu-Sn-Al alloys contained two phases,

  14. Multiatomic resonant photoemission spectroscopy on CuO and NiO: Observation of antiresonant behavior

    Microsoft Academic Search

    M. Finazzi; G. Ghiringhelli; O. Tjernberg; L. Duò; A. Tagliaferri; P. Ohresser; N. B. Brookes

    2000-01-01

    The intensity of the O 1s core photoemission peak has been measured for CuO and NiO as the photon energy is scanned across the L3 absorption edge of the metal ion. In CuO, the O 1s peak shows a typical antiresonant behavior, with a sizable decrease of its cross section at photon energies below the Cu L3 threshold. No detectable

  15. Contact angle measurements of SnAg and Sn-Cu lead-free solders on copper substrates

    Microsoft Academic Search

    Mario F. Arenas; Viola L. Acoff

    2004-01-01

    In this study, the contact angles of four lead-free solders, namely, Sn-3.5Ag, Sn-3.5Ag-4.8Bi, Sn-3.8Ag-0.7Cu, and Sn-0.7Cu (wt.%), were measured on copper substrates at different temperatures. Measurements were performed using the sessile-drop method. Contact angles ranging from 30° to 40° after wetting under vacuum with no fluxes and between 10° and 30° with rosin mildly activated (RMA) and rosin activated (RA)

  16. Contact angle measurements of SnAg and Sn-Cu lead-free solders on copper substrates

    Microsoft Academic Search

    Mario F. Arenas; Viola L. Acoff

    2004-01-01

    In this study, the contact angles of four lead-free solders, namely, Sn-3.5Ag, Sn-3.5Ag-4.8Bi, Sn-3.8Ag-0.7Cu, and Sn-0.7Cu\\u000a (wt.%), were measured on copper substrates at different temperatures. Measurements were performed using the sessile-drop method.\\u000a Contact angles ranging from 30° to 40° after wetting under vacuum with no fluxes and between 10° and 30° with rosin mildly\\u000a activated (RMA) and rosin activated (RA)

  17. Mixed-sputter deposition of Ni-Ti-Cu shape memory films

    SciTech Connect

    Krulevitch, P.; Ramsey, P.B.; Makowiecki, D.M.; Lee, A.P.; Northrup, M.A. [Lawrence Livermore National Lab., CA (United States); Johnson, G.C. [California Univ., Berkeley, CA (United States). Dept. of Mechanical Engineering

    1994-05-01

    Ni-Ti-Cu shape memory films were mixed-sputter deposited from separate nickel, titanium, and copper targets, providing increased compositional flexibility. Shape memory characteristics, examined for films with 7 at. % Cu and 41--51 at. % Tl, were determined with temperature controlled substrate curvature measurements, and microstructure was studied with transmission electron microscopy. The Ni-Ti-Cu films were found to have shape memory properties comparable to bulk materials, with transformation temperatures between 20 and 62{degree}C, a 10--13{degree}C hysteresis, and up to 330 MPa recoverable stress.

  18. Martensite transformation hystereses for CuAlNiMnTi shape-memory alloys

    Microsoft Academic Search

    Yi Jun Du; Feixia Chen; Fengting Wang; D. Z. Yang

    1992-01-01

    Cu-base shape-memory alloys are gradually taking the dominant position for applications instead of expensive, difficult-to-fabricate NiTi shape-memory alloys. However, the scope of application has been limited due to their poor thermal stability. Many series of Cu-base alloys have been developed for different uses. CuA1NiMnTi shape-memory alloys, for the purpose of meeting the requirements of higher-temperature-range uses and higher elastic modulus,

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

    SciTech Connect

    Tai, Kaiping; Feng, Lin; Dillon, Shen J. [Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States)

    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.

  20. Electrochemical performance and carbon deposition resistance of M-BaZr?.?Ce?.?Y?.?Yb?.?O??? (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells.

    PubMed

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

    2015-01-01

    Pd-, Cu-, Ni- and NiCu-BaZr?.?Ce?.?Y?.?Yb?.?O??? 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 H? and CH? oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (R?) and polarization (RP) losses of BZCYYb anode exposed to H? or CH?, while Cu impregnation decreased only R? in H? and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3?mol. % H?O) CH? 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 CH? at 750°C for 24?h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La?.?Sr?.?Co?.?Fe?.?O???-Gd doped CeO? (LSCF-GDC) cathode was stable at 750°C in wet CH? for 130?h, indicating that NiCu-BZCYYb is a promising anode for direct CH? solid oxide fuel cells (SOFCs). PMID:25563843

  1. Polycrystalline oxides formation during transient oxidation of (001) Cu-Ni binary alloys studied by in situ TEM and XRD.

    SciTech Connect

    Yang, J. C.; Li, Z. Q.; Sun, L.; Zhou, G. W.; Eastman, J. A.; Fong, D. D.; Fuoss, P. H.; Baldo, P. M.; Rehn, L. E.; Thompson, L. J.; Materials Science Division; Univ.of Pittsburgh; State Univ. of New York at Binghamton

    2009-01-01

    The nucleation and growth of Cu{sub 2}O and NiO islands due to oxidation of Cu{sub x}Ni{sub 1-x} (001) films were monitored, at various temperatures, by in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM) and in situ synchrotron X-ray diffraction (XRD). In remarkable contrast to our previous observations of Cu and Cu-Au oxidation, irregular-shaped polycrystalline oxide islands formed with respect to the Cu-Ni alloy film, and an unusual second oxide nucleation stage was noted. In situ XRD experiments revealed that NiO formed first epitaxially, then other orientations appeared, and finally polycrystalline Cu{sub 2}O developed as the oxidation pressure was increased. The segregation of Ni and Cu towards or away, respectively, from the alloy surface during oxidation could disrupt the surface and cause polycrystalline oxide formation.

  2. Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling

    SciTech Connect

    Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele; Antonio Pignedoli, Carlo; Patscheider, Joerg; Jeurgens, Lars P. H. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Antusek, Andrej [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); Faculty of Materials Science and Technology, Slovak University of Technology in Bratislava, Paulinska 16, 917 24 Trnava (Slovakia); Parlinska-Wojtan, Magdalena [Empa, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf (Switzerland); University of Rzeszow, Institute of Physics, ul. Rejtana 16a, 35-959 Rzeszow (Poland); Bissig, Vinzenz [Kirsten Soldering AG, Hinterbergstrasse 32, CH-6330 Cham (Switzerland)

    2012-10-29

    Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

  3. Investigation of the thermoelectric properties of La2CuO4 ceramics with the addition of Ag

    NASA Astrophysics Data System (ADS)

    Zhu, Chunhui; Gong, Jing; Li, Zhuangzhi; Zhou, Hongjuan; Tang, Guide

    2015-01-01

    La2AgxCuO4 (x=0, 0.01, 0.02, 0.05, 0.10, 0.15) polycrystalline ceramics have been synthesized using a solid state reaction method, and their thermoelectric properties measured in the temperature range 10-380 K. The resistivities and Seebeck coefficients of these samples tend to decrease, while the thermal conductivities first decrease then increase as the Ag dose rises. Consequently, the dimensionless thermoelectric figure of merit, ZT, first increases then decreases with increasing Ag content. The maximum ZT values for each sample appear at about 300 K and shift towards lower temperatures with the addition of Ag. At 308 K, the La2CuO4 ceramic with the addition of 5% molar Ag gave the maximum ZT value, 0.018, obtained in this work. This is nearly twice as large as that for pure La2CuO4.

  4. Process and properties of electroless Ni-Cu-P-ZrO{sub 2} nanocomposite coatings

    SciTech Connect

    Ranganatha, S. [Department of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta 577451, Shimoga, Karnataka (India)] [Department of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta 577451, Shimoga, Karnataka (India); Venkatesha, T.V., E-mail: drtvvenkatesha@yahoo.co.uk [Department of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta 577451, Shimoga, Karnataka (India); Vathsala, K. [Nanotribology Laboratory, Mechanical engineering department, Indian Institute of Science, Bangalore (India)] [Nanotribology Laboratory, Mechanical engineering department, Indian Institute of Science, Bangalore (India)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The Ni-P and Ni-P-Cu-ZrO{sub 2} coatings were produced by electroless technique. Black-Right-Pointing-Pointer The influence of copper and ZrO{sub 2} nanoparticles on Ni-P was studied. Black-Right-Pointing-Pointer Surface morphology, structure and electrochemical behavior were evaluated. Black-Right-Pointing-Pointer The Ni-Cu-P-ZrO{sub 2} and Ni-P-ZrO{sub 2} coatings are more resistant to corrosion than Ni-P. Black-Right-Pointing-Pointer Introduction of Cu and ZrO{sub 2} in the matrix aids to the enhancement of microhardness. -- Abstract: Electroless Ni-Cu-P-ZrO{sub 2} composite coating was successfully obtained on low carbon steel matrix by electroless plating technique. Coatings with different compositions were obtained by varying copper as ternary metal and nano sized zirconium oxide particles so as to obtain elevated corrosion resistant Ni-P coating. Microstructure, crystal structure and composition of deposits were analyzed by SEM, EDX and XRD techniques. The corrosion behavior of the deposits was studied by anodic polarization, Tafel plots and electrochemical impedance spectroscopy (EIS) in 3.5% sodium chloride solution. The ZrO{sub 2} incorporated Ni-P coating showed higher corrosion resistance than plain Ni-P. The introduction of copper metal into Ni-P-ZrO{sub 2} enhanced the protection ability against corrosion. The influence of copper metal and nanoparticles on microhardness of coatings was evaluated.

  5. Performance of density functional methods. Some difficult cases for small systems containing Cu, Ag, or Au.

    PubMed

    Sierraalta, Anibal; Añez, Rafael; Alejos, Paola

    2013-03-28

    Twenty-six density functional theory (DFT) methods were tested in conjunction with three different effective core potentials (ECPs) and their corresponding valence basis sets, for studying the behavior of DFT methods in small systems containing Cu, Ag, or Au where it is well-known that some functionals fail. The DFT results were compared with those obtained with post Hartree-Fock methods: second-order many-body perturbation theory (MP2), coupled cluster singles-doubles (CCSD), and coupled cluster singles-doubles with perturbative triples, CCSD(T). Calculations were carried for M3 (M = Cu, Ag, Au); M4(-), (M = Cu, Ag) and [H2O-Cu](+2). The comparison of the DFT calculated values with the Post Hartree-Fock values showed that, in general, all generalized gradient approximation (GGA) type functionals fail to describe these systems. The hybrid GGA functionals (H-GGA) showed a better behavior; however, when the Lee-Yang-Parr (LYP) exchange-correlation functional was used, wrong results were obtained. The results with the hybrid meta (HM-GGA) functionals, as in the case of H-GGAs, showed that, to obtain similar results to MP2 or CCSD(T), it is necessary to have a high Hartree-Fock exchange percentage. Spurious results obtained with the H-GGA or HM-GGA methods can be eliminated increasing the Hartree-Fock exchange percentage in the H-GGA or HM-GGA type functionals. Among the different functionals tested, the BB1K and MPWB1K functionals showed the best agreement with the MP2 and CCSD(T) results. PMID:23465056

  6. Influence of carbon nanotube on the structure evolution of Ni-Cu alloy nanorod

    NASA Astrophysics Data System (ADS)

    Guo, J.-Y.; Xu, C.-X.; Yang, C.; Dai, J.; Li, Z.-H.

    2011-02-01

    A Monte Carlo method has been performed to simulate the structure evolution of Ni-Cu alloy nanorods encapsulated in the carbon nanotube and removed from the carbon nanotube. The Sutton-Chen many-body potential and Lennard-Jones potential are used to describe the metal-metal and metal-carbon interactions, respectively. The studies show that all Ni-Cu atoms in carbon nanotube are arranged in a series of concentric cylindrical layers even they have different fractions, and Cu atoms are apt to stay at the surface layers. If the carbon nanotube was removed, Ni-Cu alloy nanorod would turn into a cluster with nickel core and copper shell. The physical origin for such structure formation and evolution toward core-shell motifs are discussed. The bond pair analysis shows that the nanorods and clusters are amorphous structures dominated by the rhombohedral structure and mixed up with some local short-range order.

  7. Effect of Gold Content on the Reliability of SnAgCu Solder Joints

    Microsoft Academic Search

    Jianbiao Pan; Julie Silk; Mike Powers; Patrick Hyland

    2011-01-01

    Electroplated Ni\\/Au over Cu is a popular metal- lization for printed circuit board finish as well as for component leads, especially wire-bondable high-frequency packages, where the gold thickness requirement for wire bonding is high. The general understanding is that less than 3 wt% of Au is acceptable in SnPb solder joints. However, little is known about the effect of Au

  8. An XPS and AES study of the free corrosion of Cu, Ni and Zn-based alloys in synthetic sweat

    Microsoft Academic Search

    S Colin; E Beche; R Berjoan; H Jolibois; A Chambaudet

    1999-01-01

    This paper deals with the investigations into the behaviour during free corrosion of Cu\\/Zn\\/Ni, Cu\\/Ni\\/Zn and Ni\\/Cu alloys in a synthetic sweat medium by means of surface analyses. For the three alloys studied, our experimental results indicate the presence of a corrosion layer, the thickness of which increases with the increase of the copper content of the alloy. The corrosion

  9. The cycling of Ni, Zn, Cu in the system “mine tailings–ground water–plants”: A case study

    Microsoft Academic Search

    Nikolay V. Sidenko; Elena I. Khozhina; Barbara L. Sherriff

    2007-01-01

    The comparative behaviour of Ni, Cu and Zn in the system “mine tailings–ground water–plants” has been investigated at the Ni–Cu mine site operated by INCO Ltd. Thompson Operations, Thompson, Manitoba. Oxidation of sulphide minerals causes the release of metals from exposed tailings containing Ni ?2000ppm, Cu ?150ppm and Zn ?100ppm to the ground water, which contains 350mg\\/LNi, 0.007mg\\/LCu, and 1.6mg\\/LZn.

  10. Fractional crystallization of anhydrous sulfide liquid in the system Fe-Ni-Cu-S, with application to magmatic sulfide deposits

    Microsoft Academic Search

    Michael E. Fleet; Yuanming Pan

    1994-01-01

    Phase relations for coexisting monosulfide solid solution [(Fe,Ni)] 1- x S; mss] and sulfide liquid have been determined in the Fe-rich portion of the anhydrous quaternary System Fe-Ni-Cu-S at 52.5 and 50.0 at% S, 850-1050°C and low pressure. Equations for the complex dependence of the mss solidus, sulfide liquidus and distribution coefficients for exchange of Ni\\/Cu and Fe\\/Cu on temperature,

  11. Effect of Mechanical Alloying Parameters on the Formation of Ni-Cu Solid Solution Coating on the Ni Balls

    NASA Astrophysics Data System (ADS)

    Farahbakhsh, Iman; Zakeri, Alireza; Manikandan, Palavesamuthu; Tanaka, Shigeru; Hokamoto, Kazuyuki

    2011-01-01

    Mechanical alloying is a viable technique to produce coatings of limited thickness on a solid substrate. Elemental copper powder was mechanically alloyed with nickel balls in a planetary ball mill under various milling times and rotation speeds. The mutual diffusion of the elements during milling which led to the formation of a Ni-Cu solid solution and the creation of Ni-Cu coating on the surface of Ni balls was studied. The maximum hardness of the coating increased to threefold (HV0.01594) that of the substrate. Micro-structural characterization of the coating surface using optical microscope, scanning electron microscope (SEM), and electron probe micro-analyzer (EPMA) indicates that, by using appropriate processing conditions, a thick, fully-dense coating can be metallurgically bonded to the nickel balls. X-ray diffraction (XRD) results revealed the formation of nanocrystalline solid solutions.

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

    SciTech Connect

    Li Peng [State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072 (China); Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072 (China); Li Jinglong, E-mail: lijinglg@nwpu.edu.cn [Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072 (China); Xiong Jiangtao; Zhang Fusheng; Raza, Syed Hamid [Shaanxi Key Laboratory of Friction Welding Technologies, Northwestern Polytechnical University, Xi'an 710072 (China)

    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.

  13. Ag-Cu catalysts for ethylene epoxidation: Selectivity and activity descriptors

    NASA Astrophysics Data System (ADS)

    Nguyen, Ngoc Linh; de Gironcoli, Stefano; Piccinin, Simone

    2013-05-01

    Ag-Cu alloy catalysts for ethylene epoxidation have been shown to yield higher selectivity towards ethylene oxide compared to pure Ag, the unique catalyst employed in the industrial process. Previous studies showed that under oxidizing conditions Cu forms oxide layers on top of Ag. Using first-principles atomistic simulations based on density functional theory, we investigate the reaction mechanism on the thin oxide layer structures and establish the reasons for the improved selectivity. We extend the range of applicability of the selectivity descriptor proposed by Kokalj et al. [J. Catal. 254, 304 (2008)], 10.1016/j.jcat.2008.01.008, based on binding energies of reactants, intermediates, and products, by refitting its parameters so as to include thin oxide layer catalysts. We show that the selectivity is mainly controlled by the relative strength of the metal-carbon vs. metal-oxygen bonds, while the height of the reaction barriers mostly depend on the binding energy of the common oxametallacycle intermediate.

  14. Studies of the Ag/Cu(110) bimetallic interface using optical second-harmonic generation

    SciTech Connect

    Muenchausen, R.E.; Hoffbauer, M.A.; Taylor, T.N.

    1989-01-01

    Optical second harmonic generation (SHG) has recently been shown to be a sensitive, real-time, in situ probe for studying interfaces under many different environments. With regard to atomically clean well-characterized surfaces, SHG has been shown to be sensitive to submonolayer coverages of adsorbates, the structural symmetry or molecular arrangement on the surface, and the surface reordering observed during laser induced melting and recrystallization. Previous SHG studies of bimetallic systems have focused on alkali metal adsorption onto transition metal substrates. In these systems the observed SH response is enhanced by a factor of one thousand upon alkali adsorption, due to the large charge transfer to the substrate. We have chosen to study the growth of Ag overlayers on an atomically clean and well-characterized Cu(110) surface. The Ag overlayer growth on this substrate is known to have some interesting temperature dependent behavior that is typical for systems in which significant three-dimensional clustering is known to be important. Cu and Ag, while electronically similar, are immiscible near room temperature, hence there is no significant surface or bulk alloy formation. 16 refs., 4 figs., 1 tab.

  15. The reactions between electroless Ni-Cu-P Deposit and 63Sn37Pb flip chip solder bumps during reflow

    Microsoft Academic Search

    Chun-Jen Chen; Kwang-Lung Lin

    2000-01-01

    This study investigates the interfacial reactions between electroless Ni-Cu-P deposit and 63Sn-37Pb solder bumps under various\\u000a reflow conditions. The morphology of the intermetallic compounds formed at the Ni-Cu-P\\/Sn-Pb interface changes with respect\\u000a to reflow cycle, reflow temperature, and reflow time. The (Ni,Cu)3Sn4 compounds with three different morphologies of fine grain, whisker, and polygonal grain form at the Ni-Cu-P\\/Sn-Pb interface\\u000a after

  16. Wetting and Soldering Behavior of Eutectic Au-Ge Alloy on Cu and Ni Substrates

    NASA Astrophysics Data System (ADS)

    Leinenbach, C.; Valenza, F.; Giuranno, D.; Elsener, H. R.; Jin, S.; Novakovic, R.

    2011-07-01

    Au-Ge-based alloys are interesting as novel high-temperature lead-free solders because of their low melting point, good thermal and electrical conductivity, and high corrosion resistance. In the present work, the wetting and soldering behavior of the eutectic Au-28Ge (at.%) alloy on Cu and Ni substrates have been investigated. Good wetting on both substrates with final contact angles of 13° to 14° was observed. In addition, solder joints with bond shear strength of 30 MPa to 35 MPa could be produced under controlled conditions. Cu substrates exhibit pronounced dissolution into the Au-Ge filler metal. On Ni substrates, the NiGe intermetallic compound was formed at the filler/substrate interface, which prevents dissolution of Ni into the solder. Using thin filler metal foils (25 ?m), complete consumption of Ge in the reaction at the Ni interface was observed, leading to the formation of an almost pure Au layer in the soldering zone.

  17. 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.

  18. Fabrication of a micrometer Ni-Cu alloy column coupled with a Cu micro-column for thermal measurement

    NASA Astrophysics Data System (ADS)

    Lin, J. C.; Chang, T. K.; Yang, J. H.; Jeng, J. H.; Lee, D. L.; Jiang, S. B.

    2009-01-01

    Micrometer Ni-Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAGE) process in the citrate bath. The surface morphology and chemical composition of the micro-columns were determined by copper concentration in the bath and by the electrical bias of MAGE. When fabricated in a bath of dilute copper (i.e. 4 mM) at lower voltages (e.g. 3.8 and 4.0 V), the alloy micro-columns revealed uniform diameter and smooth appearance. The alloy composition demonstrated an increase in the wt% ratio of Ni/Cu from 75/25, 80/20, 83/17 to 87/13 with increasing electrical bias from 3.8, 4.0, 4.2 to 4.4 V. However, it decreases from 75/25, 57/43 to 47/53 with increasing copper concentration from 4, 8 to 12 mM in the bath. Citrate plays a role in forming complexes with nickel and copper at similar reduction potentials, thus reducing simultaneously to Ni-Cu alloy. The mechanism for fabricating alloy micro-columns could be delineated on the basis of cathodic polarization of the complexes. A couple of micro-columns were fabricated using MAGE in constructing a pure copper micro-column on the top of a Ni/Cu (at 47/53) alloy micro-column. This micro-thermocouple provides a satisfactory measurement with good sensitivity and precision.

  19. Molecular-dynamics study of the Ni{sub 60}Ag{sub 40} binary alloy glass transition

    SciTech Connect

    Pryadilshchikov, A. Yu., E-mail: alexeypr@inbox.ru; Kosilov, A. T.; Evteev, A. V.; Levchenko, E. V. [Voronezh State Technical University (Russian Federation)

    2007-12-15

    Features in the evolution of the atomic structure of the Ni{sub 60}Ag{sub 40} alloy upon quenching from a liquid disordered state were revealed within the molecular-dynamics method using many-particle potentials of interatomic interaction, calculated within the embedded atom method. It was shown that the structural stabilization of the amorphous Ni{sub 60}Ag{sub 40} phase during the glass transition occurs due to the formation of a percolation cluster of interpenetrating and contacting icosahedra with nickel and silver atoms at vertices and preferentially nickel atoms at centers.

  20. Runaway lattice-mismatched interface in an atomistic simulation of femtosecond laser irradiation of Ag film-Cu substrate system

    NASA Astrophysics Data System (ADS)

    Wu, Chengping; Thomas, Derek A.; Lin, Zhibin; Zhigilei, Leonid V.

    2011-09-01

    The atomic mixing and structural transformations in a Ag film-Cu substrate system irradiated by a femtosecond laser pulse are investigated in a simulation performed with a model that couples the classical molecular dynamics method with a continuum-level description of the laser excitation and subsequent relaxation of the conduction-band electrons. The higher strength of the electron-phonon coupling in Cu compared to Ag results in preferential sub-surface heating and melting of the Cu substrate. The melting is followed by fast cooling and rapid resolidification occurring under conditions of strong undercooling below the equilibrium melting temperatures of Cu and Ag. The rapid resolidification results in a complex structure of the interfacial region, where the lattice-mismatched interface is separated from the Ag-Cu mixing region by an intermediate pseudomorphic bcc Cu layer that grows epitaxially on the (001) face of the fcc Ag film during the final stage of the resolidification process. The new lattice-mismatched interface has a three-dimensional structure consisting of a periodic array of stacking fault pyramids outlined by stair-rod partial dislocations. The intermediate bcc layer and the stacking fault pyramid structure of the mismatched interface are likely to present a strong barrier for dislocation propagation, resulting in the effective hardening of the layered structure treated by the laser irradiation. The concentration profiles in the atomic mixing region are substantially wider compared to the width of the equilibrium Cu-Ag interface and have a pronounced asymmetric shape that reflects the preferential melting of the Cu substrate.

  1. Al2O3/SUS304 Brazing via AgCuTi-W Composite as Active Filler

    NASA Astrophysics Data System (ADS)

    Su, Cherng-Yuh; Zhuang, Xie-Zongyang; Pan, Cheng-Tang

    2014-03-01

    Alumina ceramic (?-Al2O3) was brazed to stainless steel (SUS304) using an Ag-Cu-Ti + W composite filler and a traditional active brazing filler alloy (CuSil-ABA). Then, the effects of the presence of W particles and of the brazing parameters on the microstructures and mechanical properties of the brazed joints were investigated. The maximum tensile strength of the joints obtained using Ag-Cu-Ti + W composite filler was 13.2 MPa, which is similar to that obtained using CuSil-ABA filler (13.5 MPa). When the joint was brazed at 930 °C for 30 min, the tensile strengths decreased for both kinds of fillers, although the strength was slightly higher for the Ag-Cu-Ti + W composite filler than for the Ag-Cu-Ti filler. The interfacial microstructure results show that the Ti reacts with W to form a Ti-W-O compound in the brazing alloy. When there are more W particles in the brazing alloy, the thickness of the Ti X O Y reaction layer near the alumina ceramic decreases. Moreover, W particles added to the brazing alloy can reduce the coefficient of thermal expansion of the brazing alloy, which results in lower residual stress between the Al2O3 and SUS304 in the brazing joints and thus yields higher tensile strengths as compared to those obtained using the CuSil-ABA brazing alloy.

  2. 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. PMID:21411886

  3. Cu-NMR spectra in UCu4Ni uncover site disorder

    NASA Astrophysics Data System (ADS)

    Bernal, O. O.; Rose, D. A.; Wu, Hsin-Ju; Chiang, M.; MacLaughlin, D. E.; Stewart, G. R.; Kim, J. S.

    2012-12-01

    Cu-NMR measurements in a random powder of UCu4Ni reveal two types of spectral lines for each of the two isotopes of naturally abundant Cu in the material. These lines, which we label L1 and L2, point to the existence of two inequivalent Cu sites in the sample. We present a study of the NMR line shape in UCu4Ni at three different frequencies (in the range from 40-70 MHz) and two temperature values (10 K and 150 K), that allow us to assign the lines to particular Cu sites. L1 is strongly broadened as the frequency decreases, but changes less with increasing temperature. In contrast, the width of L2 grows in proportion to frequency and decreases noticeably with increasing temperature. This behavior indicates that the crystallographic site corresponding to L1 is exposed to electric field gradients and has lower point symmetry than the site corresponding to L2, which displays some anisotropy but no discernible quadrupole effects. By comparison with the Cu-NMR spectra in UCu4Pd, where only one type of Cu-NMR line has been observed clearly, we can associate L1 with Cu(16e) nuclei: Cu nuclei sitting at the 16e site (Wyckoff notation) in the AuBe5 structure of the parent compound UCu5. This leaves L2 as originating from Cu(4c) nuclei; i.e., those sitting at the 4c site of the same structure. Unlike in UCu4Pd, the appearance of signal from Cu(4c) nuclei in the Ni compound is clear evidence of site disorder in UCu4Ni.

  4. M atom (M = Cu, Ag and Au) interaction with Ag and Au substrates: a first-principles study using cluster and slab models.

    PubMed

    Nigam, Sandeep; Majumder, Chiranjib

    2010-11-01

    Using state-of-the-art first-principles calculations we report the interaction of M atoms (M = Cu, Ag and Au) with small Ag(n), Au(n) clusters (n = 3 and 6) and periodic Ag(111) and Au(111) surfaces. All calculations were performed using the plane wave pseudo-potential approach under the spin polarized version of the generalized gradient approximation scheme. The result shows that the equilibrium geometry of all MAg(3) and MAu(3) clusters favor a planar rhombus structure. From the charge distribution analysis of MAg(n)/MAu(n) clusters it is found that, while Cu and Ag donates electronic charge towards the host clusters, the Au atom acts as an acceptor, thus creating charge polarization in the system. The difference in orbital decomposed charges before and after the M interaction reveals that enhanced s-d hybridization is responsible for keeping the MAu(6) cluster planar, and increased p-orbital participation induces three-dimensional configurations in MAg(6) clusters. The optimization of M atom deposition on the Ag(111) and Au(111) surfaces shows that M atoms prefer to adsorb on the threefold fcc site over other well-defined sites. From the orbital decomposed charge analysis it is inferred that, although there is significant difference in the absolute magnitude of the interaction energy between M atoms and the Ag or Au substrates, the nature of chemical bonding is similar for the finite size clusters as well as in slab models. PMID:21403323

  5. Investigating Quantum Oscillations in the Thermal Coefficient of Resistivity of Ultra-thin Ag Capping Layers on Cu for IC Interconnect Applications

    NASA Astrophysics Data System (ADS)

    Tatem, Elroy

    As the semiconductor industry continues to scale feature sizes, scattering from phonons, surfaces, and grain boundaries result in an increase of metal interconnect resistivity in state-of-the-art integrated circuits (ICs). The interconnect chapter of the 2011 International Technology Roadmap for Semiconductors (ITRS) stated that there are currently no manufacturable solutions in the near term for suitable Cu replacements. Previous studies of thin Ag films deposited on Cu demonstrated oscillations in the electron-phonon interactions within the bilayer system. This thesis investigates oscillations in the resistive properties of the Ag/Cu bilayer system and discusses the applicability of these oscillations to the resistivity challenges facing metal-based IC interconnects. Ag/Cu bilayer films were prepared by physical vapor deposition (PVD). The films were characterized by measuring the electrical resistance of the films at various temperatures and calculating the thermal coefficient of resistance (TCR) for various Ag capping layer thicknesses. Films were further characterized by atomic force microscopy (AFM), Rutherford backscattering (RBS), and scanning electron microscopy (SEM). Patterned Ag-capped Cu lines were fabricated, which exhibited resistive behavior similar to that of the Ag/Cu films. Compared to bare Cu, the resistances of Ag-capped Cu lines and films were lower and exhibited a reduced dependence on temperature. Smaller thermal coefficients of resistivity were also observed for Ag-capped Cu films and patterned lines when compared to Cu alone.

  6. Molecular self-assembly at nanometer scale modulated surfaces: trimesic acid on Ag(111), Cu(111) and Ag/Cu(111).

    PubMed

    Baviloliaei, Mahdi Sadeghzadeh; Diekhöner, Lars

    2014-06-21

    The balance between molecule-molecule and molecule-surface interactions is a determining factor in the creation of well-ordered organic networks formed by self-assembly on crystalline metal surfaces. We have used a scanning tunneling microscope under ultrahigh vacuum conditions to study the molecular self-assembly of trimesic acid on a surface that is modulated on a comparable nanometer scale as the size of the molecules. This is made of one layer of silver grown on a Cu(111) surface where it forms a periodic reconstruction. It is shown that the self-assembly of trimesic acid at room temperature, where intermolecular interactions are taking place via hydrogen bonds, is strongly disturbed due to the modulated substrate and the spatially varying potential imposed on the molecules. Annealing to 350 K partly deprotonates the molecules and changes the intermolecular interactions to stronger ionic hydrogen bonds. This reduces the influence of the modulated substrate and allows the molecules to self-assemble into long-range ordered networks on the surface. Comparisons are made to self-assembly on the flat surfaces of Ag(111) and Cu(111), where we always find well-ordered molecular networks. PMID:24776919

  7. Effects of FeCo magnetic nanoparticles on microstructure of Sn-Ag-Cu alloys

    NASA Astrophysics Data System (ADS)

    Xu, Siyang; Habib, Ashfaque H.; Prasitthipayong, Anya; McHenry, Michael E.

    2013-05-01

    Sn-Ag-Cu (SAC) alloys have been regarded as the most promising candidates for lead-free solders in the electronic packaging industry. We prepared SAC solder-FeCo magnetic nanoparticles (MNPs) composite paste with different MNP concentration and used AC magnetic fields localized heating to cause their reflow. Differential scanning calorimetry results show a reduced undercooling of the composite paste with the addition of MNPs. Transmission electron microscope prove that the FeCo MNPs are distributed in Sn matrix of the reflowed solder composites. Optical micrographs show a decrease in the amount of primary Ag3Sn and ?-Sn dendrites, and an increase in the amount of eutectic microconstituents with increasing MNPs. The addition of FeCo MNPs is considered to promote the solidification of ?-Sn by providing more heterogeneous nucleation sites at a relatively low undercooling, which results in the microstructural refinement in the as-prepared solder joints.

  8. Periplasmic multilamellar membranous structures in Nicotiana tabacum L. pollen grains treated with Ni²? or Cu²?.

    PubMed

    Polevova, Svetlana; Breygina, Maria; Matveyeva, Natalie; Yermakov, Igor

    2014-11-01

    Essential trace elements Ni(2+) and Cu(2+) can block pollen germination without causing cell death. Mechanisms of this effect remain unclear. Using TEM, we studied the effects of Ni(2+) or Cu(2+) treatment on the ultrastructure of the aperture regions in tobacco pollen preparing to germinate in vitro, since in these zones, the main fluxes of water, ions, and metabolites cross the plasmalemma. Neither Ni(2+) nor Cu(2+) altered the cytoplasm ultrastructure, but both affected the reorganization of apertural periplasm during pollen activation. Numerous multilamellar membranous structures continuous with the plasma membrane could be seen in hydrated but not yet activated pollen. When the normal activation was completed, the structures disappeared and the plasmalemma became smooth. In the presence of 1 mM Ni(2+) or 100 ?M Cu(2+), these structures preserved its original appearance. It is assumed to be the storage form for the membrane material, which is to provide an initial phase of the pollen tube growth. Ni(2+) and Cu(2+) affect the utilization of these membranes, thereby, blocking the pollen germination. PMID:24802108

  9. Thermal conductivity of La 2 CuO 4 , La 2 NiO 4 , and Nd 2 CuO 4 in the semiconducting and metallic phases

    Microsoft Academic Search

    C. G. S. Pillai; A. M. George

    1986-01-01

    Thermal conductivity of polycrystalline La2CuO4, La2NiO4, and Nd2CuO4 was measured in the temperature range 300–1000 K. No anomaly in thermal conductivity has been observed during the semiconductor-to-metal transition of La2NiO4 or in the metallic phases of La2CuO4 and La2NiO4. A change of slope has been found, however, in the thermal conductivity of La2CuO4 at the crystallographic transition. The thermal conductivity

  10. TEMPS DE VOL DES NEUTRONS SPECTROSCOPIE DE Wr, 53Mn,"Fe, 59Ni,59Cu,"Cu, (j5Zn

    E-print Network

    Boyer, Edmond

    . Abstract. - Using the Oak Ridge 5.5 MeV Van de Graaff pulsed proton beam, S'Cr, 53Mn, "Fe, 59Ni and 65CuTEMPS DE VOL DES NEUTRONS SPECTROSCOPIE DE Wr, 53Mn,"Fe, 59Ni,59Cu,"Cu, (j5Zn PAR TEMPS-DEVOL DES,s MeV du laboratoire d'Oak Ridge, les niveaux de 53Mn, 55Fe, SgNi et 65Cu ont été étudiés par temps

  11. Structural and optical properties of (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin film alloys

    SciTech Connect

    Boyle, J. H.; Shafarman, W. N.; Birkmire, R. W. [Institute of Energy Conversion, University of Delaware, 451 Wyoming Road, Newark, Delaware 19716 (United States); Department of Materials Science and Engineering, University of Delaware, 201 DuPont Hall, Newark, Delaware 19716 (United States); McCandless, B. E. [Institute of Energy Conversion, University of Delaware, 451 Wyoming Road, Newark, Delaware 19716 (United States)

    2014-06-14

    The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin films were characterized over the entire compositional range at a fixed (Cu?+?Ag)/(In?+?Ga) ratio. Films deposited at 550?°C on bare and molybdenum coated soda-lime glass by elemental co-evaporation in a single-stage process with constant incident fluxes exhibit single phase chalcopyrite structure, corresponding to 122 spacegroup (I-42d) over the entire compositional space. Unit cell refinement of the diffraction patterns show that increasing Ag substitution for Cu, the refined a{sub o} lattice constant, (Ag,Cu)-Se bond length, and anion displacement increase in accordance with the theoretical model proposed by Jaffe, Wei, and Zunger. However, the refined c{sub o} lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.

  12. Rotationally anisotropic second-harmonic generation studies of the structure and electronic properties of bimetallic interfaces, Ag on Cu(110)

    SciTech Connect

    Hoffbauer, M.A.; McVeigh, V.J.

    1990-01-01

    Rotationally anisotropic surface second-harmonic generation (SHG) has been measured from a clean, well-ordered Cu(110) single-crystal surface as a function of both surface temperature and Ag coverage. For the clean Cu(110) surface, the temperature dependence of the SH response at a fixed azimuthal angle can be correlated with a surface phase transformation. A large decrease in the rotationally anisotropic SH response as a function of surface temperature can be related to changes in the surface disorder. The results are compared with other studies of Cu(110) surface structure using both x-ray and He-atom scattering. The rotationally anisotropic SH response has also been measured as a function of Ag coverage with the Cu(110) surface temperature fixed at 300 K. The results closely follow the formation of an ordered Ag(111)-like overlayer, the nucleation of three-dimensional Ag nanoclusters (<20 {angstrom} thick) that enhance the anisotropic SH response, and the subsequent growth of a {approximately}10 monolayer thick Ag film. Variations in the rotationally anisotropic SH response as a function of Ag coverage are used to separate the resonant surface electronic contributions to the nonlinear susceptibility of the interface. 22 refs., 4 figs.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  14. Ni-B amorphous alloy nanoparticles modified nanoporous Cu toward ethanol oxidation in alkaline medium

    NASA Astrophysics Data System (ADS)

    Zhang, Shu-Jin; Zheng, Yi-Xiong; Yuan, Lin-Shan; Zhao, Li-Hua

    2014-02-01

    Nanoporous Cu (NPC) prepared by dealloying CuZn alloy is used as an economic substrate for the fabrication of Ni-B alloy (Ni-B/NPC) by ultrasonic-assisted electroless technique. The results of scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrate the NPC has a bicontinuous network structure and the Ni-B/NPC alloy is amorphous structure with highly dispersed nanoparticles. Electrochemical performances are measured by cyclic voltammetry (CV), chronoamperometry (CA) and linear sweep voltammetry (LSV). The results suggest that the Ni-B/NPC electrode prepared for 5 min shows the highest electrochemical activity and its redox species coverage and proton diffusion coefficient are remarkably improved compared with the bulk Ni. Ethanol oxidation at the Ni-B/NPC electrode suggests the onset oxidation potential has a negative shift of 52 mV and the oxidation peak current increases by 19.4 times, and apparent activation energy decreases 4.75-30.60 kJ mol-1 at the same potential, in comparison with the bulk Ni. Additionally, the reaction rate constant for ethanol oxidation at the Ni-B/NPC electrode is improved by about one order of magnitude relative to the reported value. Finally, the Ni-B/NPC electrode has a stable redox behavior after complete activation and superior catalytic stability for ethanol oxidation.

  15. Doping effect of Ag nanoparticles on critical current of YBa 2Cu 3O 7-? bulk superconductor

    NASA Astrophysics Data System (ADS)

    Farbod, Mansoor; Batvandi, Mohammad Reza

    2011-02-01

    The objective of this work is to investigate the effect of Ag nanoparticles on critical current of YBa 2Cu 3O 7-? (YBCO) superconductor. Ag nanoparticles with different particle sizes from 30 to 1000 nm were prepared through the chemical reduction of AgNO 3 in an alcohol solution. Then, samples of YBCO superconductors were doped by 1 and 2 wt.% of Ag nanoparticles with different sizes. Samples were characterized with XRD, SEM and EDX measurements. Critical current measurements were performed using a standard four-probe technique at liquid nitrogen temperature. The results showed by increasing of Ag nanoparticles up to 700 nm the J c increases, but decreases by further increase in Ag particles size. The critical current enhancement is attributed to the improved connectivity between the grain boundaries and better crystallization of the grains.

  16. Magnetic behavior of NiCu nanowire arrays: Compositional, geometry and temperature dependence

    SciTech Connect

    Palmero, E. M., E-mail: epalmero@icmm.csic.es; Bran, C.; Real, R. P. del; Vázquez, M. [Institute of Materials Science of Madrid, CSIC, Madrid 28049 (Spain); Magén, C. [Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragón (INA)-ARAID and Department of Condensed Matter Physics, University of Zaragoza, Zaragoza 50018 (Spain)

    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??m 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.

  17. Analysis of the reaction between 60Sn-40Pb solder with a Pd-Pt-Ag-Cu-Au alloy

    NASA Astrophysics Data System (ADS)

    Frear, D. R.; Michael, J. R.; Hlava, P. F.

    1993-02-01

    We present the results of a metallurgical study of a 35Pd-30Ag-14Cu-10Au10Pt-1Zn (wt. %) alloy soldered with 60Sn-40Pb for glass-to-metal sealing applications. Mechanical tests were performed on the Pd-Ag-Cu-Au-Pt-Zn alloy and showed that it retains ductility, with an increase in strength, after heat treatments that simulate the glass-to-metal sealing temperature profile. Wetting characteristics of the alloy with 60Sn-40Pb solder were found to be adequate for pin joining applications. The formation and growth of the interfacial interme-tallic between 60Sn-40Pb and the Pd-Ag-Cu-Au-Pt-Zn alloy were characterized. The matrix of the intermetallic layer consists of PdSn4 with platinum and gold substituting for the palladium in the crystal structure. Also present were precipitates of Cu3Sn and Ag3Sn. Nano-indentation hardness tests showed that the intermetallic layer has mechanical properties similar to the base metal while retaining good ductility. The intermetallic was also found to have good wettability under solder reflow conditions. We conclude from these tests that the Pd-Ag-Cu-Au-Pt-Zn alloy is a suitable option as a pin material for glass-to-metal sealing applications.

  18. Five-fold twinned Pd2NiAg nanocrystals with increased surface Ni site availability to improve oxygen reduction activity.

    PubMed

    Liu, Suli; Zhang, Qinghua; Li, Yafei; Han, Min; Gu, Lin; Nan, Cewen; Bao, Jianchun; Dai, Zhihui

    2015-03-01

    The synthesis of highly active oxygen reduction reaction (ORR) catalysts with good durability and low cost is highly desirable but still remains a significant challenge. In this work, we present the synthesis of five-fold twinned Pd2NiAg nanocrystals (NCs) with a Ni-terminal surface which exhibit excellent electrocatalytic performance for ORR in alkaline media, even better than the performance of the commercial Pt/C catalyst. Using high-angle annular-dark-field imaging together with density functional theory calculations, it is found that the surfaces of the five-fold twinned Pd2NiAg NCs exhibit an unusual valence electron density. The maximum catalytic activity originates from the increased availability of surface Ni sites in five-fold twinned Pd2NiAg NCs and the features of twinned structural defects. This study provides an explanation of the enhanced ORR from the special structure of this novel material, which opens up new avenues for the design of novel classes of electrocatalysts for fuel cells and metal-air batteries. PMID:25626352

  19. A coherent phase diagram of the [(AuCu)0.86Ag0.14]1-XPtX pseudobinary section in Au-Cu-Ag-Pt quaternary system.

    PubMed

    Sakrana, A A; Tanaka, Y; Udoh, K; Hisatsune, K; Atsuta, M; Yasuda, K

    1997-12-01

    In order to determine a coherent phase diagram of the [(AuCu)0.86Ag0.14]1-XPtX pseudobinary system, phase identifications and analyses of the microstructural configurations were performed by means of transmission electron microscopy. Various phase regions were detected in the coherent phase diagram as follows; (1) alpha 0 (fcc) single phase region, (2) two-phase region (alpha 1 + alpha 2), (3) AuCu I (L10) + alpha 0, (4) AuCu I + alpha 2, (5) AuCu II (L10-S) + alpha 2, (6) AuCu I + AuCu II + alpha 2, (7) AuCu I single phase region. Microstructural features of these regions relating to the phase transformations were described. PMID:9555253

  20. Oxidation of ethyl acetate by a high performance nanostructure (Ni, Mn)Ag\\/ZSM-5 bimetallic catalysts and development of an artificial neural networks predictive modeling

    Microsoft Academic Search

    Azadeh Jodaei; Darush Salari; Ali Niaei; Masumeh Khatamian; Seyed Ali Hosseini

    2011-01-01

    The catalytic oxidation of ethyl acetate in low concentration was investigated over mono-metallic Ag\\/ZSM5 and bimetallic (Ni, Mn)-Ag\\/ZSM-5 catalysts. Catalytic studies were carried out in a catalytic fixed bed reactor under atmospheric pressure. The sequence of catalytic activity was as follows: Ni-Ag-ZSM-5 > Mn-Ag-ZSM-5 > Ag-ZSM-5 > H-ZSM-5. The catalysts were characterized by ICP-AES, X-ray diffraction (XRD), low temperature nitrogen

  1. Effects of oxygen partial pressure on the crystallization of amorphous Bi-Sr-Ca-Cu-O and Bi-Sr-Ca-Cu-O + Ag

    NASA Astrophysics Data System (ADS)

    Kramer, M. J.; Margulies, L.; Arrasmith, S. R.; Dennis, K. W.; Lang, J. C.; McCallum, R. W.; Gallagher, P. K.

    1994-07-01

    The temperatures and pathways of crystallization for amorphous Bi-Sr-Ca-Cu-O are strongly dependent on oxygen partial pressure (P(sub O(2))), the oxidation state of the glass, and the presence of Ag. Reducing the P(sub O(2)) from 1 to 0 bar lowers the onset of melting 100 deg C, but does not change the onset of crystallization. Decreasing P(sub O(2)) does inhibit the formation of (CaSr)CuO3 (011). Although Ag appears to be immiscible in Bi-Sr-Ca-Cu-O, finely distributed Ag lowers the onset of melting by 20 to 35 C, depending on P(sub O(2)). In oxygen-deficient glass, two exotherms are observed upon heating.

  2. Thermal and structural characterization of Cu-Al-Mn-X (Ti, Ni) shape memory alloys

    NASA Astrophysics Data System (ADS)

    Canbay, C. Aksu; Genc, Z. Karagoz; Sekerci, M.

    2014-05-01

    In this study, the Cu-Al-Mn-X (X = Ni, Ti) shape memory alloys at the range of 10-12 at.% of aluminum and 4-5 at.% manganese were produced by arc melting. We have investigated the effects of the alloying elements on the transformation temperatures, and the structural and the magnetic properties of the quaternary Cu-Al-Mn-X (X = Ni, Ti) shape memory alloys. The evolution of the transformation temperatures was studied by differential scanning calorimetry with different heating and cooling rates. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the aluminum and manganese content, and it was observed that the nickel addition into the Cu-Al-Mn system decreased the transformation temperature although Ti addition caused an increase in the transformation temperatures. The effect of the nickel and the titanium on the thermodynamic parameters such as enthalpy and entropy values was investigated. The structural changes of the samples were studied by X-ray diffraction measurements and by optical microscope observations at room temperature. It is evaluated that the element Ni has been completely soluble in the matrix, and the main phase of the Cu-Al-Mn-Ni sample is martensite, and due to the low solubility of the Ti, the Cu-Al-Mn-Ti sample has precipitates, and a martensite phase at room temperature. The magnetic properties of the Cu-Al-Mn, Cu-Al-Mn-Ni and Cu-Al-Mn-Ti samples were investigated, and the effect of the nickel and the titanium on the magnetic properties was studied.

  3. Nanosize metal alloy particle formation in Ag and Cu sequentially implanted silica

    SciTech Connect

    Zuhr, R.A. [Oak Ridge National Lab., TN (United States); Magruder, R.H. III; Anderson, T.A.; Wittig, J.E. [Vanderbilt Univ., Nashville, TN (United States)

    1993-12-01

    A series of high purity silica samples were sequentially implanted with Ag and Cu ions at energies such that the depth distributions for each of the ions overlap. The samples were characterized by RBS, TEM and optical spectroscopy. Optical response was found to be dependent on order of sequential implantation as well as relative concentration of implanted elements. The changes in the optical response are attributed to composition changes of the metal colloids that are formed as a result of alloying of the sequentially implanted metal ions, as well as to changes in the size the colloids.

  4. Oxidation of carbon monoxide over Cu and Ag-NaY catalysts with aqueous hydrogen peroxide

    Microsoft Academic Search

    Zeinhom Mohamed El-Bahy; Zeinhom Mohamed

    2007-01-01

    A novel oxidation reaction of CO with aqueous H2O2 over Cu-NaY (2–15wt%) and Ag-NaY (5–15wt%) catalysts has been achieved at low temperatures (55–70°C) using a flow mode system. The employed catalysts were prepared by the incipient wetness impregnation of NaY zeolite (Si\\/Al=5.6, surface area=910m2\\/g) with an aqueous solution of known concentrations of copper acetate and silver nitrate. Solids were subjected

  5. Developing a lead-free solder alloy Sn-Bi-Ag-Cu by mechanical alloying

    Microsoft Academic Search

    C. M. L. Wu; M. L. Huang; J. K. L. Lai; Y. C. Chan

    2000-01-01

    A new lead free alloy, Sn-6Bi-2Ag-0.5Cu, has been developed by mechanical alloying and has great potential as a lead-free\\u000a solder system. Initial trials on the manufacture of solder joints with this alloy revealed that a high quality bond with copper\\u000a could be formed. Its melting range of 193.87°C to 209.88°C is slightly higher than that of eutectic tin-lead solder. Examination

  6. The synthesis and characterization of nanocrystalline Cu- and Ag-based multinary sulfide semiconductors

    SciTech Connect

    An Changhua; Tang Kaibin; Shen Guozhen; Wang Chunrui; Huang Liying; Qian Yitai

    2003-04-30

    The novel polygonal flake like Ag{sub 8}SnS{sub 6} crystal, Cu{sub 2}FeSnS{sub 4} flaky, and well-dispersed Cu{sub 2}CoSnS{sub 4} nanoparticles were successfully prepared via a convenient hydrothermal reaction route at relatively low temperature, which was avoiding the use of high temperature treatments or toxic organic solvents. The products were characterized by means of X-ray powder diffraction (XRD), transmission electronic microscopy (TEM), X-ray photoelectronic spectra (XPS) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). It was found that the reaction temperature played a key role for the formation of the target products.

  7. Study of dislacation Ni-Cu interface interaction with Peierls-Nabarro model

    NASA Astrophysics Data System (ADS)

    Xiao, Wei; Ghoniem, Nasr

    2005-03-01

    Metallic multi-layered structures have received increasingly interest in the past few years because of their unusual and interesting mechanical properties and high strength-to-weight ratio. The mechanical properties of an interface are determined, in large part, by the nature of the chemical bonding at the interface, which may be significantly different from that within either of the materials meeting at the interface. The resistance of interfaces to dislocation transmission is a fundamental quantity that often serves to control strength in plastically deforming multiphase materials. We have generalized an multi-scale approach based on semi-discrete variational generalized Peierls-Nabarro (SVGPN) for the pure Cu, Ni, and the (001) Ni-Cu interface have calculated from ab initio calculations. Various dislocation properties, such as the core width, energy, the Peierls stress, the dissociation behavior are investigated and compared to those of pure Cu and Ni hosts. Supported by US Air Force grant 0205GDD417.

  8. Cu-Ni nano-alloy: mixed, core-shell or Janus nano-particle?

    PubMed

    Guisbiers, Grégory; Khanal, Subarna; Ruiz-Zepeda, Francisco; Roque de la Puente, Jorge; José-Yacaman, Miguel

    2014-12-21

    Bimetallic nanoparticles like Cu-Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core-shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu-Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu-Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists. PMID:25360574

  9. Ferromagnetic resonance study of Permalloy/Cu/Co/NiO spin valve system

    NASA Astrophysics Data System (ADS)

    Ben Youssef, J.; Layadi, A.

    2010-09-01

    Ferromagnetic resonance, in 7 to 18 GHz frequency range, is used to investigate a series of rf sputtered Permalloy (Py)/Cu/Co trilayers and Py/Cu/Co/NiO spin valve system. The experimental data, frequency versus applied magnetic field, agree quit well with the theoretical model. The magnetic coupling between Py and Co is found to be ferromagnetic with effective magnetic coupling parameter values increasing from 0.05 to 0.1 erg/cm2 as the interlayer Cu thickness decreases from 10 to 2 nm. While the magnetic coupling leads to a decrease in the resonance fields, HR, of the modes, the exchange anisotropy at the Co/NiO interface shifts the mode upwards. However the shift is more important for the optical mode than for the acoustic one. Hysteresis curves, qualitatively, confirm the ferromagnetic coupling. The antiferromagnetic NiO layer leads to a slight increase in the coercive field.

  10. Nanoscale patterning of Zr-Al-Cu-Ni metallic glass thin films deposited by magnetron sputtering.

    PubMed

    Sharma, Parmanand; Zhang, Wei; Amiya, Kenji; Kimura, Hisamichi; Inoue, Akihisa

    2005-03-01

    Completely glassy thin films of Zr-Al-Cu-Ni exhibiting a large super-cooled liquid region (deltaTx = 95 K), very smooth surface (Ra = 0.65 nm), and an extremely high value of Vicker's hardness (Hv = 940), as compared to bulk Zr-Al-Cu-Ni metallic glass, were deposited by radiofrequency magnetron sputtering. Nanoscale patterning ability of Zr-Al-Cu-Ni metallic glass thin films was demonstrated by a focused ion beam etching. The capability to write nanometer-scale patterns (line width approximately 12 nm) opens up a variety of possibilities for fabricating nanomolds for imprint lithography, and a wide range of two- or three-dimensional components for future nanoelectromechanical systems. PMID:15913248

  11. Elastic properties of Cu-Al-Ni shape memory alloys studied by dynamic mechanical analysis

    NASA Astrophysics Data System (ADS)

    Graczykowski, B.; Biskupski, P.; Mroz, B.; Mielcarek, S.; Nó, M. L.; San Juan, J.

    2010-01-01

    The elastic properties of Cu-Al-Ni single crystals have been studied during forward and reverse martensitic transformation by dynamic mechanical analysis. Measurements were performed for two alloys, occurring in austenitic (Cu-14%Al-4%Ni) and martensitic (Cu-13.7%Al-3%Ni) phases at room temperature. Investigation of elastic and damping properties was performed for several frequencies of the oscillating force. Evolution of damping in cooling/heating measurements gave information about internal friction during forward and reverse martensitic phase transformations. Characteristic temperatures of martensitic transformation were determined by dynamic mechanical analysis and compared with optical micrographs of samples' surfaces and with previous results from differential scanning calorimetry. In addition, comparison of elastic properties in pure austenitic and martensitic phase during ageing was made. The paper presents a step-by-step analysis of experimental results showing the causes which lead to observed changes of elastic properties at martensitic transformation or with time.

  12. Nucleation behavior of bulk Ni-Cu alloy and pure Sb in High magnetic fields

    NASA Astrophysics Data System (ADS)

    Liu, Tie; Wang, Qiang; Liu, Feng; Li, Guojian; He, Jicheng

    2011-04-01

    The effect of high magnetic fields on the nucleation behavior of Ni-90 at%Cu alloys and pure Sb were investigated. It was found that the undercooling of both Ni-90 at%Cu alloys and pure Sb before nucleation was increased by the application of a high magnetic field of 11.5 T. An obvious grain refinement was observed in the Ni-90 at%Cu alloys solidified in the high magnetic field. Such grain refinement could be linked to the increase of the undercooling. The increase in the undercooling in the high magnetic field was attributed to the suppressing effect of the Lorentz force on the convection in the melt. Such suppressing effect could delay the formation of oxides which were responsible for the heterogeneous nucleation of the materials.

  13. Research papers Distribution of platinum-group and chalcophile elements in the Aguablanca NiCu

    E-print Network

    of these elements in the deposit. The BMS (pyrrhotite, pentlandite, chalcopyrite and minor pyrite) occur as semi-massive, disseminated and minor chalcopyrite-veined ores. On the basis of whole rock metal abundances and BMS mineralogy to minor Cu-rich sulfide liquid in the form of chalcopyrite veinlets with relatively Pd-, Au- and Ag

  14. On the lamellar compounds CuBiP(2)Se(6), AgBiP(2)Se(6) and AgBiP(2)S(6). Antiferroelectric phase transitions due to cooperative Cu(+) and Bi(3+) ion motion.

    PubMed

    Gave, Matthew A; Bilc, Daniel; Mahanti, S D; Breshears, Jean D; Kanatzidis, Mercouri G

    2005-07-25

    CuBiP(2)Se(6), AgBiP(2)Se(6), and AgBiP(2)S(6) were prepared from the corresponding elements. CuBiP(2)Se(6) and AgBiP(2)Se(6) crystallize in the space group R with a = 6.5532(16) A and c = 39.762(13) A for CuBiP(2)Se(6) and a = 6.6524(13) A and c = 39.615(15) A for AgBiP(2)Se(6). AgBiP(2)S(6) crystallizes in the triclinic space group P with a = 6.3833(13) A, b = 7.1439(14) A, c = 9.5366(19) A, alpha = 91.89(3) degrees , beta = 91.45(3) degrees , gamma = 94.05(3) degrees . CuBiP(2)Se(6) was found to exhibit a temperature-dependent antiferroelectric ordering of the Cu(+) and Bi(3+) ions in the lattice. An intermediate and a fully ordered structure were refined at 173 and 97 K, respectively. Electronic band and total energy calculations at the DFT level clearly suggest that the antiferroelectric model is energetically favored over the paraelectric and hypothetical ferrielectric models. This phase transition can be classified as a second-order Jahn-Teller distortion. The antiferroelectric state of CuBiP(2)Se(6) is an indirect gap semiconductor. The compounds were characterized with differential thermal analysis and solid-state UV/vis diffuse reflectance spectroscopy. Generalized implications regarding the expected ferroelectric behavior of compounds in the CuMP(2)Se(6) system (M = trivalent metal) are discussed. PMID:16022528

  15. Ni-Cu tetracarbide carbonyls with vacant Ni(CO) fragments as borderline compounds between molecular and quasi-molecular clusters.

    PubMed

    Bernardi, Alessandro; Ciabatti, Iacopo; Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Zacchini, Stefano

    2013-01-14

    The reaction of [Ni(9)C(CO)(17)](2-) with [Cu(CH(3)CN)(4)][BF(4)] (1.1-1.5 equiv.) afforded the first Ni-Cu carbide carbonyl cluster, i.e., [H(2)Ni(30)C(4)(CO)(34){Cu(CH(3)CN)}(2)](4-) ([H(2)1](4-)). This has been crystallised in a pure form with miscellaneous [NR(4)](+) (R = Me, Et) cations, as well as co-crystallised with [H(2)Ni(29)C(4)(CO)(33){Cu(CH(3)CN)}(2)](4-) ([H(2)2](4-)) which differs from [H(2)1](4-) by a missing Ni(CO) fragment. By increasing the [Cu(CH(3)CN)(4)](+)/[Ni(9)C(CO)(17)](2-) ratio to 1.7-1.8, the closely related [H(2)Ni(30)C(4)(CO)(35){Cu(CH(3)CN)}(2)](2-) ([H(2)3](2-)), [H(2)Ni(29)C(4)(CO)(34){Cu(CH(3)CN)}(2)](2-) ([H(2)4](2-)), and [H(2)Ni(29)C(4)(CO)(32)(CH(3)CN)(2){Cu(CH(3)CN)}(2)](2-) ([H(2)5](2-)) dianions have been obtained. Replacement of Cu-bonded CH(3)CN with p-NCC(6)H(4)CN afforded, after protonation of the tetra-anion, mixtures of [H(3)Ni(30)C(4)(CO)(34){Cu(NCC(6)H(4)CN)}(2)](3-) ([H(3)6](3-)) and [H(3)Ni(29)C(4)(CO)(33){Cu(NCC(6)H(4)CN)}(2)](3-) ([H(3)7](3-)). The species 1-7 display a common Ni(28)C(4)Cu(2) core and differ for the charge, the presence of additional Ni atoms, the number and nature of the ligands, even though they are obtained under similar experimental conditions and often in mixtures. Their nature in solution has been investigated via FT-IR, chemical and electrochemical methods. Electrochemical studies, besides confirming the poly-hydride nature of these clusters, show that they undergo different redox processes with features of chemical reversibility, and this might be taken as proof of the incipient metallisation of their metal cores. PMID:23069730

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

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R. [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)] [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Kulriya, P. K.; Khan, S. A. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)] [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    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.

  17. Effect of filler metal composition on the strength of yttria stabilized zirconia joints brazed with Pd-Ag-CuOx

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2008-09-08

    The Ag-CuOx system is of interest to be used to be used as an air braze filler metal for joining high temperature electrochemical devices. Previous work has shown that the melting temperatures can be increased by adding palladium to Ag-CuOx and it is expected that this may aid high temperature stability. This work compares the room temperature bend strength of joints made between yttria-stabilized zirconia (YSZ) air brazed using Ag-CuOx without palladium and with 5 and 15mol% palladium additions. It has been found that in general palladium decreases joint strength, especially in low copper oxide compositions filler metals. At high copper oxide contents, brittle fracture through both copper oxide rich phases and the YSZ limits joint strength.

  18. The potential availability of P, Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in urban particulate matter

    Microsoft Academic Search

    K. R. Lum; J. S. Betteridge; R. R. Macdonald

    1982-01-01

    NBS urban particulate matter, SRM 1648, has been analyzed by a sequential extraction procedure to determine the chemical forms of P, AI, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. High proportions of P, Cd, Co, Cu, Ni, Pb and Zn were found to be in soluble and\\/or exchangeable forms which are potentially readily bioavailable.

  19. Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic glasses

    E-print Network

    Zheng, Yufeng

    Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic June 2010 The corrosion properties of two Zr-based bulk metallic glass, Zr41Ti14Cu12Ni10Be23 LM1 and Zr Institute of Physics. doi:10.1063/1.3429591 Corrosion of metallic materials in general depends on several

  20. Electrostatic Levitation Processing of Zr-Nb-Ni-Cu-Al Bulk Metallic Glass Forming Alloys

    Microsoft Academic Search

    Charles C. Hays; Jan Schroers; William L. Johnson; Ulrich Geyer

    2000-01-01

    The bulk glass forming ability in the Zr-Nb-Cu-Ni-Al alloy system is well established. This alloy system has been investigated by our group in recent electrostatic levitation (ESL) experiments conducted at the NASA Marshall Space Flight Center Electrostatic Levitation facility. We have identified a composition, Zr_(58.5).Nb_(2.8).Cu_(15.6).Ni_(12.8).Al_(10.3)., that exhibits a substantially improved glass forming ability. This alloy is easily vitrified by standard

  1. Antiferromagnetic phase in Zn and Ni-doped CuGeO 3

    Microsoft Academic Search

    Naoki Koide; Yoshitaka Sasago; Takatsugu Masuda; Kunimitsu Uchinokura

    1996-01-01

    The magnetic susceptibility of single crystals Cu1?x\\u000a M\\u000a x\\u000a GeO3 (M=Zn, Ni) were investigated to study the effects of impurities on the inorganic spin-Peierls material CuGeO3. We succeeded in the growth of Zn-doped single crystals with 0.007?x?0.09 and Ni-doped ones withx=0.033. We determined temperature vsx phase diagram of the Zn-doped single crystals, which is almost identical to that of the

  2. Effect of silver concentration on electric and magnetic properties of HTS composites YBa2Cu3Ox-Ag

    Microsoft Academic Search

    V. I. Dotsenko; I. F. Kislyak; P. P. Pal’-Val’; L. N. Pal’-Val’; V. D. Natsik

    1993-01-01

    The resistive and magnetic properties of the composites YBa2Cu3Ox-Ag are investigated in a wide range of silver concentration (c=0–100%). It is found that the concentration dependences of the critical temperature Tcz and the critical density Jc are nonmonotonic, the peak values being attained for c=5–15 vol.% Ag. A quantitative and qualitative correlation between the Jc(c) and the concentration dependence Jcj(c)

  3. M atom (M = Cu, Ag and Au) interaction with Ag and Au substrates: a first-principles study using cluster and slab models

    NASA Astrophysics Data System (ADS)

    Nigam, Sandeep; Majumder, Chiranjib

    2010-11-01

    Using state-of-the-art first-principles calculations we report the interaction of M atoms (M = Cu, Ag and Au) with small Agn, Aun clusters (n = 3 and 6) and periodic Ag(111) and Au(111) surfaces. All calculations were performed using the plane wave pseudo-potential approach under the spin polarized version of the generalized gradient approximation scheme. The result shows that the equilibrium geometry of all MAg3 and MAu3 clusters favor a planar rhombus structure. From the charge distribution analysis of MAgn/MAun clusters it is found that, while Cu and Ag donates electronic charge towards the host clusters, the Au atom acts as an acceptor, thus creating charge polarization in the system. The difference in orbital decomposed charges before and after the M interaction reveals that enhanced s-d hybridization is responsible for keeping the MAu6 cluster planar, and increased p-orbital participation induces three-dimensional configurations in MAg6 clusters. The optimization of M atom deposition on the Ag(111) and Au(111) surfaces shows that M atoms prefer to adsorb on the threefold fcc site over other well-defined sites. From the orbital decomposed charge analysis it is inferred that, although there is significant difference in the absolute magnitude of the interaction energy between M atoms and the Ag or Au substrates, the nature of chemical bonding is similar for the finite size clusters as well as in slab models.

  4. Mechanical Characterization of Lead-Free Sn-Ag-Cu Solder Joints by High-Temperature Nanoindentation

    NASA Astrophysics Data System (ADS)

    Lotfian, S.; Molina-Aldareguia, J. M.; Yazzie, K. E.; Llorca, J.; Chawla, N.

    2013-06-01

    The reliability of Pb-free solder joints is controlled by their microstructural constituents. Therefore, knowledge of the solder microconstituents' mechanical properties as a function of temperature is required. Sn-Ag-Cu lead-free solder alloy contains three phases: a Sn-rich phase, and the intermetallic compounds (IMCs) Cu6Sn5 and Ag3Sn. Typically, the Sn-rich phase is surrounded by a eutectic mixture of ?-Sn, Cu6Sn5, and Ag3Sn. In this paper, we report on the Young's modulus and hardness of the Cu6Sn5 and Cu3Sn IMCs, the ?-Sn phase, and the eutectic compound, as measured by nanoindentation at elevated temperatures. For both the ?-Sn phase and the eutectic compound, the hardness and Young's modulus exhibited strong temperature dependence. In the case of the intermetallics, this temperature dependence is observed for Cu6Sn5, but the mechanical properties of Cu3Sn are more stable up to 200°C.

  5. Resistivity and Magnetoresistance of Dilute Solutions of Cr in Cu-Ni Alloys

    Microsoft Academic Search

    C. F. Eagen; S. Legvold

    1972-01-01

    The electrical resistivity from 1.3 to 100 K and the longitudinal magnetoresistance from 0 to 85 kOe at 4.2 K were measured on Cu-Ni (Cr) alloys with Ni concentrations of 0, 6, 13, and 23 at.% and Cr concentrations of 0, 125, 300, 600, and 1200 at. ppm. All Cr-bearing samples were observed to exhibit resistivity minima. The difference in

  6. A parallel study of Ni@Si 12 and Cu@Si 12 nanoclusters

    Microsoft Academic Search

    A. D. Zdetsis; E. N. Koukaras; C. S. Garoufalis

    2009-01-01

    The Ni@Si12 and Cu@Si12 clusters are studied in parallel within the framework of the density functional theory using the hybrid functional of Becke-Lee,\\u000a Parr and Yang (B3LYP), emphasizing the differences and similarities in structural and electronic properties. The dominant\\u000a structures for both clusters are a distorted hexagonal structure of Cs symmetry and a distorted octahedral structure of D2d. For Ni@Si12

  7. The Partition Coefficients of Components in Cu-Ni-Mn Alloys

    NASA Astrophysics Data System (ADS)

    Bazhenov, V. E.; Pikunov, M. V.; Cheverikin, V. V.

    2015-02-01

    Dendritic microsegregation was calculated using a Scheil-based solidification model for three alloys: 50.1 pct Cu-25.8 pct Ni-24.1 pct Mn; 42.4 pct Cu-25.4 pct Ni-32.2 pct Mn; 34.3 pct Cu-26.2 pct Ni-39.5 pct Mn. The dendritic microsegregation in these alloys was investigated using energy-dispersive X-ray analysis. It was shown by calculation and experimental methods that in all three alloys, the partition coefficient ( k) of manganese passes through the value k Mn = 1. This is shown by the presence of two maxima on the manganese concentration profile in the dendritic cell. It was calculated that the copper partition coefficient in these alloys should also pass through the value k Cu = 1; however, this has not been confirmed experimentally. The possible reason for this may be because of the inaccuracies in the phase diagram of the Cu-Ni-Mn system that was used and also in the difference of the copper and manganese diffusion coefficients in the alloy.

  8. Magnetic behavior of NiCu nanowire arrays: Compositional, geometry and temperature dependence

    NASA Astrophysics Data System (ADS)

    Palmero, E. M.; Bran, C.; del Real, R. P.; Magén, C.; Vázquez, M.

    2014-07-01

    Arrays of Ni100-xCux nanowires ranging in composition 0 ? x ? 75, diameter from 35 to 80 nm, and length from 150 nm to 28 ?m 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.

  9. Synthesis and properties of one-dimensional Ni(II) and Ni(II)Cu(II) complexes linked by hydrogen bond

    Microsoft Academic Search

    Cui Jianzhong; Shi Wei; Cheng Peng; Liao Daizheng; Yan Shiping; Jiang Zonghui; Wang Genglin; Yao Xinkan; Wang Honggen

    2002-01-01

    Four dithiooxalato (Dto) bridged one-dimensional Ni(ll) and Ni(ll)Cu(ll) complexes (Me6[14]dieneN4)Ni2(Dto)2) (1), (Me6[14]dieneN4)CuNi(Dto)2 (2), (Me6[14]aneN4)Ni2(Dto)2 (3), and (Me6[14]aneN4)CuNi(Dto)2 (4), were synthesized. These complexes have been characterized by elemental analysis, IR, UV and ESR spectra. The crystal structure\\u000a of complex3 was determined. It crystallizes in the monoclinic system, space group C2\\/c with a = 2. 2425(4) nm,b = 1.0088(2) nm,c= 1.4665(3) nm,

  10. 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.

  11. Background suppressed measurements of the Low Energy CVV Auger transitions in Cu and Ag(100)

    NASA Astrophysics Data System (ADS)

    Shastry, K.; Mukherjee Mukherjee, S.; Kalaskar, S.; Hulbert, S. L.; Bartynski, B. R.; Weiss, A. H.

    2010-10-01

    Low energy Auger lineshapes are difficult to measure because they sit on a large background due to secondary electrons arising from loss processes unrelated to the Auger mechanism. Auger photoelectron coincidence spectroscopy (APECS) was used to the spectrum of the MVV and NVV Auger peaks and associated low energy tails (LETs) in Cu and Ag (100) respectively. The backgrounds due to secondary electrons unrelated to the auger process were suppressed by measuring the Auger spectra in coincidence with the M and N core levels. The APECS measurements reveal a well formed Auger peak at 40 and 60 eV for Cu and Ag respectively accompanied by a significant Auger related intensity in the low energy region. Spectra obtained using APECS are compared with Positron Annihilation Induced Auger Electron Spectroscopy (PAES) measurements which also show a large LET. The LET is discussed in terms of extrinsic mechanisms in which the electrons from the peak lose energy as they propagate to the sample surface and intrinsic mechanisms in which multi- electron auger processes distribute the energy gained by filling of the core hole to multiple electrons.

  12. Nucleation promotion of Sn-Ag-Cu lead-free solder alloys via micro alloying

    NASA Astrophysics Data System (ADS)

    Mao, Jie

    Sn-Ag-Cu (SAC) alloy system is widely accepted as a viable Pb-free alternative to Sn-Pb alloys for microelectronics packaging applications. Compared with its Pb-containing predecessor SAC alloys tend to have coarse grain structure, which is believed to be caused by high undercooling prior to nucleation. This work explores the possibility of modifying the nucleation process and reducing the undercooling of SAC alloys via introducing minor alloying elements. The mechanisms through which effective alloying elements influenced the nucleation process of SAC alloys are investigated with microstructural and chemical analyses. Minor alloying elements (Mn and Zn) are found promoting beta-Sn nucleation and reducing the undercooling of SAC. Manganese promotes beta-Sn primary phase nucleation through the formation of MnSn2 intermetallic compound. Experimental results in this work support the claim by previous researchers that zinc promotes beta-Sn primary phase nucleation through the formation of zinc oxide. In addition to nucleation, this work also assesses the microstructural impact of minor elements on Sn-Ag-Cu based alloys. Methods have been developed to quantify and compare microstructural impacts of minor elements and efficiently study their partitioning behaviors. LA-ICPMS was introduced to SAC alloy application to efficiently study partitioning behaviors of minor elements.

  13. Muon Localization in Transition Metal Oxides: NiO, CoO and CuO

    Microsoft Academic Search

    Steven Maples; Wayne Dawson; Carel Boekema; Kusuo Nishiyama

    1998-01-01

    Transition metal oxides form the basis for many unique phenomena in magnetism, superconductivity and ferroelectricity. CuO forms the framework structure of the majority of the high-temperature superconductors. The experimental results of recent muon spin rotation measurements in antiferromagnetic CuO, CoO, and NiO have been modeled using a combination of potential energy calculations and magnetic dipole calculation. Based upon this model,

  14. A Pd-Cu-Ni Ternary Alloyed Membrane on Porous Nickel Support Prepared by Sputtering and Copper Reflow

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Won; Um, Ki-Youn; Kim, Heung-Gu; Lee, In-Seon; Kim, Sang-Ho; Park, Jong-Soo; Ryi, Shin-Kun; Cho, Sung-Ho

    2005-01-01

    We propose a ternary, Pd-Cu-Ni, alloyed membrane on porous nickel support that dramatically enhances the hydrogen selectivity by using sputtering and copper reflow. Porous nickel support made by sintering shows strong resistance to hydrogen embrittlement and thermal fatigue. To improve the hydrogen selectivity of the membrane, fabricated the layer sequence of Cu/Pd/Ni on porous nickel support replaced that of conventional Pd/Cu/Ni and then reflow was performed at 700°C. Consequently, copper was reflowed unilaterally into Pd/Ni layer, thereby avoiding delamination by the interlayered copper and enabling infinite hydrogen selectivity because of extremely dense coatings.

  15. Graphitic carbon nitride solid nanofilms for selective and recyclable sensing of Cu2+ and Ag+ in water and serum.

    PubMed

    Huang, Heqin; Chen, Rui; Ma, Jiale; Yan, Li; Zhao, Yingqi; Wang, Yu; Zhang, Wenjun; Fan, Jun; Chen, Xianfeng

    2014-12-18

    Herein we report the fabrication of g-C3N4 nanofilms and their application as a solid fluorescence sensor. The as-prepared films are capable of convenient, sensitive, selective, rapid and recyclable sensing of Cu(2+) and Ag(+) in water and serum, indicating the sensor's potential application in disease diagnosis. Attractively, our sensor is able to differentiate Cu(2+) and Ag(+) by making use of their different adsorption and desorption kinetics during the interaction with g-C3N4 nanofilms. PMID:25350907

  16. Silver tracer diffusion in oriented Ag/Cu interphase boundaries and correlation to the boundary structure

    SciTech Connect

    Sommer, J.; Herzig, C. [Univ. Muenster (Germany). Inst. fuer Metallforschung] [Univ. Muenster (Germany). Inst. fuer Metallforschung; Muschik, T.; Gust, W. [Max-Planck Inst. fuer Metallforschung, Stuttgart (Germany)] [Max-Planck Inst. fuer Metallforschung, Stuttgart (Germany)

    1996-01-01

    Radiotracer experiments were performed on oriented Ag/Cu bicrystals to study the influence of the interphase boundary (IB) structure on the material transport along the interfaces. Tracer diffusion of {sup 110m}Ag was measured along (011) IBs in the [100] and [01{bar 1}] directions and along (111) IBs in the [01{bar 1}] and [{bar 2}11] directions in the temperature range 593--882 K. It is demonstrated for cube-on-cube orientations how the interfacial structure is reflected in the diffusion behavior. It was found that the Ag diffusion along anisotropic misfit dislocation arrays in (011) IBs is anisotropic and fastest along channels of rapid diffusion. A scatter in the diffusion data for (011) IBs indicates that their structure, quite in contrast to morphologically stable (111) interfaces, depends on the thermal history of the specimens. This is interpreted as a result of microfaceting of the morphologically unstable (011) IBs. Furthermore, the influence of interdiffusion across the interface on the diffusion along the interface is discussed.

  17. Corrosion resistance of Cu–Zr–Al–Y and Zr–Cu–Ni–Al–Nb bulk metallic glasses

    Microsoft Academic Search

    Daniela Zander; Beate Heisterkamp; Isabella Gallino

    2007-01-01

    Electrochemical tests of amorphous Cu46Zr42Al7Y5 in comparison to amorphous Zr58.5Cu15.6Ni12.8Al10.3Nb2.8 (Vit106a) were conducted by potentiodynamic polarization at room temperature in 0.001–0.1M NaClaq (pH 8). The influence of corrosion on the surface topography was studied by X-ray diffraction and SEM. Electrochemical measurements indicate a good corrosion resistance of both bulk metallic glasses in NaCl solutions with low molarity at pH 8

  18. Studies on Compton scattering of the Fe-C, Fe-Cu and Ni-Cu binary powder mixtures.

    PubMed

    Luo, Guang; Hu, Xianquan

    2013-09-01

    Nowadays the Compton scattering is widely applied in various fields. In the present paper, we explore the Compton scattering effects on the binary powder mixture scatterers. By using the Compton scattering theory, we obtain an approximate linear relationship between the scattered photon counts and the contents of the binary powder mixture scatterer. This relationship has been confirmed by conducting the Compton scattering experiments of the binary powder mixture series such as the Fe-C, Fe-Cu and Ni-Cu scatterers. Moreover, we make a discussion on the experimental errors. The Compton scattering method is helpful for measuring the contents of the binary powder mixtures. PMID:23774322

  19. Effect of trace organic compounds on the corrosion of Cu/Ni alloys in sulfide polluted seawater

    SciTech Connect

    Reda, M.R.; Al-Hajji, J.N. (Kuwait Univ., Sufat (Kuwait))

    1993-05-01

    Trace organic complexing agents were investigated to check their ability to reduce the relatively high corrosion rates of Cu/Ni alloys in sulfide polluted seawater. It is found that an organic complexing agent such as fuchsin in the concentration range of 5 ppm is an excellent inhibitor against uniform and localized attack for 70/30 Cu/Ni alloy in 2 ppm sulfide polluted seawater. Another metal complexing agent, SSA (5-sulfosalicylic acid), was found to be effective for the 90/10 Cu/Ni alloy against enhanced attack by sulfide polluted seawater while it was ineffective for 70/30 Cu/Ni alloy. EDTA (ethylene diaminetetraacetic acid disodium salt) was found to be ineffective for both Cu/Ni alloys when used by itself in the concentration range of 5 ppm. A mechanism is proposed to explain the effectiveness of the various selected trace organic complexing agents on the corrosiveness of sulfide polluted seawater.

  20. Combinatorial screening of ternary NiO-Mn2O3-CuO composition spreads

    NASA Astrophysics Data System (ADS)

    Kukuruznyak, D. A.; Ahmet, P.; Chikyow, T.; Yamamoto, A.; Ohuchi, F. S.

    2005-08-01

    We describe the screening of large combinatorial oxide libraries for their electric transport characteristics. Complete ternary composition spreads of NiO-Mn2O3-CuO oxide alloys were deposited onto conducting Nb-doped SrTiO3 substrates using the combinatorial pulsed laser deposition technique. Resistance-temperature relations for each composition in the spread were determined using a custom-designed scanning probe. Ternary and binary electrically conducting alloys are located around Ni0.45Cu0.75Mn1.65O4 (the lowest resistance point) and CuMn2O4 compositions, respectively. The temperature sensitivities of the compositions Ni0.3Cu0.3Mn2.4O4,Cu0.84Mn2.16O4, and Cu1.35Mn1.65O4 were 5.0%/°C, 3.5%/°C, and 3.0%/°C, respectively. From this screening we propose compounds for thin-film negative temperature coefficient thermistors with standardized characteristics.

  1. Study of the Interface Microstructure of Sn-Ag-Cu Lead-Free Solders and the Effect of Solder Volume on Intermetallic Layer Formation.

    E-print Network

    Ekere, Ndy

    -fine pitch flip-chip applications. Key words: Lead-free soldering, tin-silver-copper alloys, intermetallic that the Sn- Ag-Cu alloy is one of the promising lead-free alloys currently being evaluated by industryStudy of the Interface Microstructure of Sn-Ag-Cu Lead-Free Solders and the Effect of Solder Volume

  2. Comparison of Extensive Thermal Cycling Effects on Microstructure Development in Micro-alloyed Sn-Ag-Cu Solder Joints

    SciTech Connect

    Anderson, Iver E.; Boesenberg, Adam; Harringa, Joel; Riegner, David; Steinmetz, Andrew; Hillman, David

    2011-09-28

    Pb-free solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic have promise for widespread adoption across assembly conditions and operating environments, but enhanced microstructural control is needed. Micro-alloying with elements such as Zn was demonstrated for promoting a preferred solidification path and joint microstructure earlier in simple (Cu/Cu) solder joints studies for different cooling rates. This beneficial behavior now has been verified in reworked ball grid array (BGA) joints, using dissimilar SAC305 (Sn-3.0Ag-0.5Cu, wt.%) solder paste. After industrial assembly, BGA components joined with Sn-3.5Ag-0.74Cu-0.21Zn solder were tested in thermal cycling (-55 C/+125 C) along with baseline SAC305 BGA joints beyond 3000 cycles with continuous failure monitoring. Weibull analysis of the results demonstrated that BGA components joined with SAC + Zn/SAC305 have less joint integrity than SAC305 joints, but their lifetime is sufficient for severe applications in consumer, defense, and avionics electronic product field environments. Failure analysis of the BGA joints revealed that cracking did not deviate from the typical top area (BGA component side) of each joint, in spite of different Ag3Sn blade content. Thus, SAC + Zn solder has not shown any advantage over SAC305 solder in these thermal cycling trials, but other characteristics of SAC + Zn solder may make it more attractive for use across the full range of harsh conditions of avionics or defense applications.

  3. Reactive Wetting Processes and Triple-Line Configuration of Sn-3.5Ag on Cu Substrates at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Zang, Likun; Yuan, Zhangfu; Cao, Zhanmin; Matsuura, Hiroyuki; Tsukihashi, Fumitaka

    2012-08-01

    Reactive wetting processes of molten Sn-3.5Ag on Cu substrates at elevated temperatures were investigated by the sessile drop method. Equilibrium contact angles of Sn-3.5Ag on Cu substrates are 36.5°, 32.9°, 25.25°, and 32.1° at 523 K, 573 K, 623 K, and 673 K, respectively, indicating that the contact angle does not decrease monotonically with increasing temperature. It is also found that the maximal triple-line mobility does not increase linearly with temperature. The complicated temperature effects on the equilibrium contact angles and triple-line mobility are attributable to the fact that Cu substrates dissolve easily in the liquid solder, hindering solder spreading. A description of the equilibrium state helped explain the triple-line region of the Sn-3.5Ag/Cu joint. The calculated results, based on the experimental values of tension balances along each of the three interfaces, show good agreement with the theoretical analysis. The present results are of practical interest for composite lead-free solder preparations and joining of Sn-3.5Ag to Cu substrates.

  4. Fracture of Sn-Ag-Cu Solder Joints on Cu Substrates: I. Effects of Loading and Processing Conditions

    NASA Astrophysics Data System (ADS)

    Huang, Z.; Kumar, P.; Dutta, I.; Pang, J. H. L.; Sidhu, R.; Renavikar, M.; Mahajan, R.

    2012-02-01

    During service, microcracks form inside solder joints, making microelectronic packages highly prone to failure on dropping. Hence, the fracture behavior of solder joints under drop conditions at high strain rates and under mixed-mode conditions is a critically important design consideration for robust joints. This study reports on the effects of joint processing and loading conditions on the microstructure and fracture response of Sn-3.8%Ag-0.7%Cu (SAC387) solder joints attached to Cu substrates. The impact of parameters which control the microstructure (reflow condition, aging) as well as loading conditions (strain rate and loading angle) are explicitly studied. A methodology based on the calculation of the critical energy release rate, G C, using compact mixed-mode (CMM) samples was developed to quantify the fracture toughness of the joints under conditions of adhesive (i.e., interface-related) fracture. In general, higher strain rate and increased mode-mixity resulted in decreased G C. G C also decreased with increasing dwell time at reflow temperature, which produced a thicker intermetallic layer at the solder-substrate interface. Softer solders, produced by slower cooling following reflow, or post-reflow aging, showed enhanced G C. The sensitivity of the fracture toughness to all of the aforementioned parameters reduced with an increase in the mode-mixity. Fracture mechanisms, elucidating the effects of the loading conditions and process parameters, are briefly highlighted.

  5. Ag Doping Effects of GdBa2Cu3O7-? Films by Low Fluorine MOD Method

    NASA Astrophysics Data System (ADS)

    Sun, M. J.; Qiu, W. B.; Liu, Z. Y.; Bai, C. Y.; Guo, Y. Q.; Cai, C. B.

    2014-05-01

    A series of Ag-doped GdBaCuO superconducting films were prepared by low fluorine MOD process on buffered Hastelloy substrates. The effects of Ag doping on the microstructures and superconducting properties of GdBCO thin films were investigated. It was found that an optimum addition of about 5 mol % Ag lead to better c-axis orientation and surface microstructure of the resultant films. Meanwhile, the pyrolysis process shortened and the superconducting performance is improved with a wide available window.

  6. Characterization of Cu buffer layers for growth of L1{sub 0}-FeNi thin films

    SciTech Connect

    Mizuguchi, M.; Sekiya, S.; Takanashi, K. [Institute of Materials Science, Tohoku University, Aoba-ku, Sendai 980-8577 (Japan)

    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.

  7. The Stellar Commodity Market: Cu, Ag, And Au In The Sun And Solar-type Stars

    NASA Astrophysics Data System (ADS)

    Wahlgren, Glenn Michael; Carpenter, K. G.; Nave, G.

    2010-01-01

    The elements copper, silver and gold occupy the same column of the periodic table and share the property that their only stable isotopes are odd-numbered, which implies a need for hyperfine structure data when analyzing their spectral lines. A comparison of their solar photospheric abundances with the standard meteoritic element abundances shows that for two of them (Ag, Au) the differences are as large as or larger than the sum of the uncertainties. With some exceptions, the study of the chemical composition of most stars stops at the end of the iron group of elements. Heavier elements are typically not analyzed, often due to the lack of accurate atomic line data. While the post iron-group elements make a small contribution to the total abundance one can argue that, for many reasons, life on earth would not be the same without copper, silver and gold. We first revisit the abundances of these elements in the solar photosphere, accounting for the revisions in atomic data since these elements were last analyzed in the photosphere. The hyperfine structure of Cu I and Ag I is included in our synthetic spectrum calculations. The spectra Cu I and Cu II are of current interest to us for the determination of hfs constants based on our new laboratory Fourier transform spectrometer data. We then determine the abundances for these elements in the high-resolution spectra for a sample of solar-like stars, obtained from on-line data bases, using synthetic spectrum techniques. The analysis aims to determine the abundance dispersion of these elements in solar-like stars in the solar neighborhood. Some of these stars are known to possess exo-planets, and the abundances of these elements will be correlated with host star metallicity. In general, we aim to encourage a more extensive use of the periodic table for stellar astrophysics.

  8. Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.

    PubMed

    Coli?, Miodrag; Rudolf, Rebeka; Stamenkovi?, Dragoslav; Anzel, Ivan; Vucevi?, Dragana; Jenko, Monika; Lazi?, 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. PMID:19540942

  9. Runaway lattice-mismatched interface in an atomistic simulation of femtosecond laser irradiation of Ag film–Cu substrate system

    Microsoft Academic Search

    Chengping Wu; Derek A. Thomas; Zhibin Lin; Leonid V. Zhigilei

    2011-01-01

    The atomic mixing and structural transformations in a Ag film–Cu substrate system irradiated by a femtosecond laser pulse\\u000a are investigated in a simulation performed with a model that couples the classical molecular dynamics method with a continuum-level\\u000a description of the laser excitation and subsequent relaxation of the conduction-band electrons. The higher strength of the\\u000a electron–phonon coupling in Cu compared to

  10. 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.

  11. Microstructure and phase transformation of Ni46Mn33Ga17Cu4xZrx alloys

    E-print Network

    Zheng, Yufeng

    Microstructure and phase transformation of Ni46Mn33Ga17Cu4ÀxZrx alloys B. Tian a , F. Chen a , Y October 2013 Accepted 12 November 2013 Available online 20 November 2013 Keywords: Metals and alloys transformation of Ni46Mn33Ga17Cu4ÀxZrx (x¼0, 2, and 4) alloys. The substitution of Cu by Zr changed the alloy

  12. ac susceptibility of thermally annealed and neutron irradiated Cu-Ni alloys

    NASA Technical Reports Server (NTRS)

    Catchings, R. M., III; Borg, R. J.; Violet, C. E.

    1985-01-01

    Thermal annealing and high-flux neutron irradiation are used to vary the degree of short-range atomic order in Cu-Ni alloys of composition 40, 50, and 60 at. pct Ni. The magnetic state is measured by ac magnetic susceptibility measurements. It is shown that annealing at 350 C causes significant changes in the susceptibility of all the samples. In the 50 and 60 at. pct Ni samples, the transition is broadened and extended to higher temperatures, while the 40 at. pct Ni sample changes from a paramagnetic system to a weakly ferromagnetic system. The neutron irradiation, in contrast to the thermal treatment, causes the development of smaller size cluster formations. The irradiated 60 at. pct Ni sample exhibits no change in the shape of its susceptibility curve from that of the quenched sample, whereas, the 40 pct alloy is changed, by irradiation, from a paramagnetic system to a spin-glass system.

  13. Ni Impurity Effect on Antiferromagnetic Order in Hole-doped La2-xSrxCuO4

    NASA Astrophysics Data System (ADS)

    Hiraka, H.; Machi, T.; Watanabe, N.; Itoh, Y.; Matsuda, M.; Yamada, K.

    2005-08-01

    The doping effect of magnetic impurities on the lightly hole-doped antiferromagnetic state was investigated by neutron diffraction techniques using single crystals of La1.99Sr0.01Cu1-yNiyO4 (0.01? y ? 0.10). Dilute Ni-doping between y=0.02 and 0.05 dramatically changes the Q-dependence of the antiferromagnetic Bragg intensity, corresponding to a switch of spin structure from the La2CuO4 type (Cu type) to the La2NiO4 type (Ni type) triggered by a spin rotation in CuO2 planes. Upon Ni-doping, the Néel temperature (TN) increases and rapidly approaches that of nondoped La2CuO4 in the Cu-type phase due to the strong localization of doped carriers, whereas TN gradually decreases in the Ni-type phase. More interestingly, between the Cu- and Ni-type structures, there exists an intermediate region where the spin direction is between those of Cu- and Ni-types. In this region, we found an unusual temperature dependence of magnetic intensities, which suggests a temperature dependence of the spin direction. These unusual behaviors are discussed in terms of doped carrier itinerancy.

  14. Layer-by-layer surfactant-induced growth of Ag on Cu( 1 1 1 ): an impact collision ion scattering spectroscopy and scanning tunnelling microscopy study

    Microsoft Academic Search

    Kenji Umezawa; Tsuyoshi Tatsuta; Shigemitsu Nakanishi; Kaoru Ojima; Masamichi Yoshimura; Kazuyuki Ueda; Walter M. Gibson

    2003-01-01

    We have investigated the structure of Ag\\/Sb\\/Cu(111) surfaces by using time-of-flight impact collision ion scattering spectroscopy. Also, scanning tunneling microscopy measurements were used in studies of the topmost layers of thin film heteroepitaxy systems at room temperature. It was found that on a surface pre-covered with a 0.2 and 0.4 ML of deposited Sb, the (1) Ag(111)[112?]\\/\\/Cu(111)[112?] versus (2) Ag(111)

  15. Formation of interfacial microstructure in brazing of Si3/N4/ with Ti-activated Ag-Cu filler alloys

    NASA Astrophysics Data System (ADS)

    Paulasto, M.; Kivilahti, J. K.

    1995-04-01

    In an attempt to understand the role of titanium in active brazing of ceramics, the formation of microstructures when silicon nitride is brazed with AgCuTi was investigated using thermodynamic analysis. SEM/EPMA and SIMS techniques were employed in the characterization of the phases formed. At brazing temperatures, AgCuTi filler was to found to be divided into liquid L1 and L2. The (Cu,Ti)-rich L2 gathered at the Si3N4 interface and reacted with it to form Ti-Cu-Si-N compound. The product proved to be the general product regardless of the copper content of Cu and Ti-containing brazes for the reason that Ti, although of high concentration, appeared to have lower activity than Cu. In the case of AgTi filler, in which Ti is the only reactive element, the product formed was similar to the product obtained from the typical reaction of Ti and Si3N4.

  16. Chemical Stability of (Ag,Cu)2Se: a Historical Overview

    NASA Astrophysics Data System (ADS)

    Brown, David R.; Day, Tristan; Caillat, Thierry; Snyder, G. JeffREY

    2013-07-01

    Recent work on Cu2- x Se has caused strong interest in this material due to its high reported peak zT (1.5) and the reduction of thermal conductivity through the mechanism of liquid-like suppression of heat capacity. In the 1960s, 3M patented Cu1.97Ag0.03Se as "TPM-217." Over the following decade it was tested and developed by the 3M Corporation, at the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory, Teledyne Energy Systems, and the General Atomics Corporation for use as a next-generation thermoelectric material. During these tests, extreme problems with material loss through Se vaporization and chemical reactions between the material and the device contacts were found. These problems were especially severe while operating under conditions of high iL/A. As a result, the material system was abandoned. The results of these reports are discussed. A simple test of degradation of Cu2Se under conditions of applied current and thermal gradient was performed and showed results compatible with the work done by General Atomics.

  17. An experimental investigation of ionic transport properties in CuI-Ag{sub 2}WO{sub 4} and CuI-Ag{sub 2}CrO{sub 4} mixed systems

    SciTech Connect

    Suthanthiraraj, S. Austin [Department of Energy, University of Madras, Guindy Campus, Chennai 600 025 (India)]. E-mail: suthan98@yahoo.com; Premchand, Y. Daniel [Department of Energy, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2004-11-01

    The phenomenon of ionic transport in the case of two different mixed systems (CuI){sub (1-x)}-(Ag{sub 2}WO{sub 4}){sub x}(0.15=CuI){sub (1-y)}-(Ag{sub 2}CrO{sub 4}){sub y}(0.15=CuI){sub 0.45}-(Ag{sub 2}WO{sub 4}){sub 0.55} and 1.1x10{sup -4}Scm{sup -1} in the case of (CuI){sub 0.55}-(Ag{sub 2}CrO{sub 4}){sub 0.45} at room temperature has been discussed in terms of the observed characteristics.

  18. STUDIES OF BISMUTH ALLOYS. II. DISTRIBUTION OF SMALL ADDITIONS OF Cu, Ag, OR Au BETWEEN SOLID AND LIQUID PHASES IN Bi-Cu, Bi-Ag, AND Bi-Au

    Microsoft Academic Search

    M. W. Nathans; M. Leider

    1961-01-01

    The distribution of small amounts of radioactive Cu, Ag, and Au between ; precipitates of these elements and their solutions in Bi was investigated at ; different temperatures by sampling the liquid. In all cases the Doerner-Hoskins ; law was obeyed. Appioximate distribution ratios were calculated and plotted ; against 1\\/T. Extrapolation to the melting temperature of the major component

  19. Grain boundary fracture in CuAlNi shape memory alloys

    Microsoft Academic Search

    A. Creuziger; W. C. Crone

    2008-01-01

    A series of polycrystalline CuAlNi shape memory alloy (SMA) samples were prepared to observe the deformation and fracture behavior under load. Observations were made of the phase transformation initiated from a notch and the interactions with nearby grain boundaries. A variety of different behaviors were observed. The grain boundaries of each of the samples were analyzed to determine the dependence

  20. The response of macrophages to a Cu-Al-Ni shape memory alloy.

    PubMed

    Coli?, Miodrag; Tomi?, 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. PMID:20008088