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1

Solid-state reactions between Ni and SnAgCu solders with different Cu concentrations  

Microsoft Academic Search

It had been reported that, during the reflow of the SnAgCu solders over the Ni-bearing surface finishes, a slight variation in Cu concentration produced different reaction products at the interface. In this study, we extended our earlier efforts to investigate whether this strong Cu concentration dependency also existed for the solid-state aging reaction between the SnAgCu solders and Ni. Specifically,

W. C. Luo; C. E. Ho; J. Y. Tsai; Y. L. Lin; C. R. Kao

2005-01-01

2

Effects of Intermetallics on the Reliability of Tin Coated Cu, Ag, and Ni Parts  

Microsoft Academic Search

The temperature dependence of the growth rates of intermetallic compounds in the Cu-Sn, Ag-Sn and Ni-Sn systems was determined between 100C and 213C for Sn-dipped and Sn-plated samples. Below 175C the fastest growing intermetallic compound was Ag3Sn. The Ni-Sn compoknd, Ni3Sn, was the slowest growing phase below 150C, but the fastest growing phase above 175C. The two Cu-Sn intermetallic phases,

Dennis Olsen; Richard Wright; Howard Berg

1975-01-01

3

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

Microsoft Academic Search

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,

S. J. Wang; C. Y. Liu

2003-01-01

4

Liquid and solid state interfacial reactions of SnAgCu and SnInAgCu solders with NiP under bump metallization  

Microsoft Academic Search

In this study, interfacial reactions of electroless Ni(P) metallization of the ball-grid-array (BGA) substrate with the Sn-4 Ag-0.5 Cu (SAC405), Sn-3 Ag-0.5 Cu (SAC305) and Sn-9 In-3.5 Ag-0.5 Cu (SIAC) (wt.%) solder alloy were investigated, focusing on identification of the intermetallic compound (IMC) phases, the IMC growth rates and the consumption rate of the metallization layer at various liquid and

Ahmed Sharif; Y. C. Chan

2006-01-01

5

Oxygen reduction on Ni, Ag, and Cu meniscus electrodes in molten carbonate  

SciTech Connect

The oxygen reduction pathways in molten carbonates have been investigated by analyzing the charge transfer resistances of the i-V curves on the meniscus electrodes of Ni, Cu, and Ag screens at 550 C. The electrochemical reduction pathways of oxygen at the meniscus electrode were found to be different depending on the electrode materials. For the Ni meniscus electrode system, the reactive material of charge transfer is the lithium doped nickel oxide, for the Ag system that is the silver oxide ion, and for the Cu system that is peroxide ion, respectively.

Ogura, Hiroyuki; Shirogami, Tamotsu [Suzuka National Coll. of Technology (Japan). Dept. of Materials Science and Engineering

1994-12-31

6

Quasicrystals and nano-quasicrystals in annealed ZrAlNiCuAg metallic glasses  

Microsoft Academic Search

Quasicrystals and nano-quasicrystals are observed in annealed Zr65Al7.5Ni10Cu12.5Ag5 and Zr65Al7.5Ni10Cu7.5Ag10 metallic glasses. Through systematic transmission electron microscopy (TEM) analyses, selected area electron diffraction (SAED) and nano-beam electron diffraction (NBED) patterns corresponding to five-, three- and twofold rotational symmetry are obtained, demonstrating that the precipitated phases in the first stage devitrification of the alloys are icosahedral quasicrystalline phases. The discovery of

M. W Chen; A Inoue; T Zhang; A Sakai; T Sakurai

2000-01-01

7

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

SciTech Connect

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.

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

8

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

E-print Network

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

Entel, P.

9

Effects of Bi and Ni addition on wettability and melting point of Sn0.3Ag0.7Cu Low-Ag Pb-free solder  

Microsoft Academic Search

Bi and Ni were added to Sn-0.3Ag-0.7Cu low-Ag solder, to fabricate new low-Ag solders, Sn-0.3Ag-0.7Cu-XBi (X= 1.0, 3.0, 4.5) and Sn-0.3Ag-0.7Cu-XNi (X=0.05, 0.10, 0.15). Melting point tests were carried out with DSC (differential scanning calorimetry) instrument. Wettability tests were conducted on a wetting balance instrument. Test results of the two new solders were compared with that of Sn-0.3Ag-0.7Cu respectively to

Y. Liu; F. L. Sun; T. L. Yan; W. G. Hu

2008-01-01

10

Study of Metal-NH[subscript 3] Interfaces (Metal= Cu, Ni, Ag) Using Potentiostatic Curves  

ERIC Educational Resources Information Center

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.

Nunes, Nelson; Martins, Angela; Leitao, Ruben Elvas

2007-01-01

11

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

NASA Astrophysics Data System (ADS)

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

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

2003-02-01

12

Containerless electromagnetic levitation melting of Cu-Fe and Ag-Ni alloys  

NASA Technical Reports Server (NTRS)

The feasibility of producing silver or copper alloys containing finely dispersed nickel or iron particles, respectively, by utilizing containerless electromagnetic levitation casting techniques was investigated. A levitation coil was designed to successfully levitate and melt a variety of alloys including Nb-Ge, Cu-Fe, Fe-C, and Ag-Ni. Samples of 70 Cu-30 Fe and 80 Ag-20 Ni (atomic %), prepared by mechanical pressing of the constituent powders, were levitated and heated either to the solid plus liquid range of the alloys or to the fully liquid region. The samples were then solidified by passing helium gas into the bell jar or they were dropped into a quenching oil. The structure of the samples which were heated to the solid plus liquid range consists of uniform distribution of Fe or Ni particle in their respective matrices. A considerable amount of entrapped gas bubbles were contained. Upon heating for longer periods or to higher temperatures, the bubbles coalesced and burst, causing the samples to become fragmented and usually fall out of the coil.

Abbaschian, G. J.; Ethridge, E. C.

1983-01-01

13

Microstructural evolution in the Sn-Cu-Ni and Pb-Sn solder joints with Cu and Pt-Ag metallized Al2O3 substrate  

Microsoft Academic Search

The growth mechanism of intermetallics between solders and metallized substrates, after thermal aging, are investigated. The solders used in this study are unleaded Sn-Cu-Ni solder and eutectic Pb-Sn solder. The Pt-Ag\\/Al2O3, Cu block and the electroless Cu\\/Pt-Ag\\/Al2O3 are employed as the metallized substrates. Microstructure evolution of the interfacial morphology, elemental, and phase distribution are probed with the aid of electron-probe

C. C. Young; J. G. Duh; S. Y. Tsai

2001-01-01

14

Intermetallic reactions between lead-free SnAgCu solder and Ni(P)\\/Au surface finish on PWBs  

Microsoft Academic Search

Due to its toxicity, Pb is likely to be eliminated eventually from electronic products and, therefore, it is important to understand and control the compatibility of the Sn-Ag-Cu solder alloys with Ni(P)\\/Au metallizations. Transmission electron microscopy and scanning electron microscopy were employed to analyze the interfacial microstructure. The intermetallic compound Cu6Sn5, containing a small amount of dissolved Ni, was found

K. Zeng; V. Vuorinen; J. K. Kivilahti

2001-01-01

15

Effect of NiP Thickness on the Tensile Strength of Cu\\/Electroless NiP\\/Sn3.5Ag Solder Joint  

Microsoft Academic Search

Tensile strength and fracture behavior of thermally aged Cu\\/electroless Ni-P\\/Sn-3.5Ag solder joint were investigated for three different Ni-P thicknesses (3.9, 7.3, and 9.9mum) to examine the mechanical reliability of the solder joint. The tensile testing results showed that Ni-P thickness influences the solder joint strength considerably. In the case of thin Ni-P, the tensile strength decreased with increase in aging

Aditya Kumar; Zhong Chen

2006-01-01

16

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

SciTech Connect

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

Wang Yue; Shi Yongfang; Chen Yubiao [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Wu Liming, E-mail: liming_wu@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2012-07-15

17

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

Microsoft Academic Search

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

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

2001-01-01

18

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

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

Won Kyoung Choi; Hyuck Mo Lee

1999-01-01

19

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

Microsoft Academic Search

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

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

1986-01-01

20

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

Microsoft Academic Search

We examine electromigration fatigue reliability and morphological patterns of Sn37Pb and Sn3Ag1.5Cu\\/Sn3Ag0.5Cu composite solder bumps in a flipchip package assembly with Ti\\/Ni(V)\\/Cu UBM. The flipchip test vehicle was subjected to test conditions of five combinations of applied electric currents and ambient temperatures, namely, 0.4A\\/150C, 0.5A\\/150C, 0.6A\\/125C, 0.6A\\/135C, and 0.6A\\/150C. The electrothermal coupling analysis was employed to investigate the current crowding

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

2007-01-01

21

Preparation of Ag-Ni-Cu Composite Material by Ultrasonic Arc Spray Forming and Accumulative Roll Bonding and the Evolution of Its Microstructure  

NASA Astrophysics Data System (ADS)

We prepared a layered composite material by subjecting a deposition billet of AgNiCu15-5 formed by ultrasonic arc spray forming (UASF) to extrusion at 773 K (500 C), rolling at 673 K (400 C), and accumulative roll bonding (ARB). The evolution of the microstructure of the formed AgNiCu15-5 strips was analyzed through X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive spectrometry. The deposition billet had a rapid solidification microstructure consisting of ?-Ni particles dispersed in ?-Ag matrix. ARB significantly refined the microstructure of the AgNiCu15-5 samples. There was no further decrease in the grain size after the 9th ARB cycle. Thus, UASF combined with extrusion and ARB is suitable for producing high-performance AgNiCu15-5-based electrical contact materials efficiently and economically.

Zhang, Ke; Qin, Guo-Yi; Xu, Si-Yong; Guo, Jin-Xin; Ma, Guang

2015-02-01

22

Influence of solid-state interfacial reactions on the tensile strength of Cu\\/electroless NiP\\/Sn3.5Ag solder joint  

Microsoft Academic Search

Tensile strength and fracture behavior of Cu\\/electroless NiP\\/Sn3.5Ag (wt.% Ag) solder joint were investigated under high-temperature solid-state aging. The aging results showed that the Ni3Sn4 intermetallic phase grows at the electroless NiP\\/Sn3.5Ag interface, along with the transformation of the underlying electroless NiP layer into Ni3P compound. However, after complete consumption of the electroless NiP layer, a ternary NiSnP compound also

Aditya Kumar; Zhong Chen

2006-01-01

23

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

SciTech Connect

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.

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

24

Wettability and interfacial reactions between the molten Sn3.0 wt%Ag0.5 wt%Cu solder (SAC305) and NiCo alloys  

Microsoft Academic Search

This study examines the wetting properties and interfacial reactions between molten Sn3.0wt%Ag0.5wt%Cu solder and NiCo alloys to evaluate NiCo alloys as alternative diffusion barrier layer materials in flip chip packaging for Cu\\/low k integrated circuits. The wetting properties of NiCo alloys with Sn3.0wt%Ag0.5wt%Cu solder are better than the currently used Ni7wt%V. With increased Co, the surface roughness of NiCo alloys

Yue-ting Chen; Ya-ting Chan; Chih-chi Chen

2010-01-01

25

Microstructural evolution in the Sn-Cu-Ni and Pb-Sn solder joints with Cu and Pt-Ag metallized Al 2 O 3 substrate  

Microsoft Academic Search

The growth mechanism of intermetallics between solders and metallized substrates, after thermal aging, are investigated. The\\u000a solders used in this study are unleaded Sn-Cu-Ni solder and eutectic Pb-Sn solder. The Pt-Ag\\/Al2O3, Cu block and the electroless Cu\\/Pt-Ag\\/Al2O3 are employed as the metallized substrates. Microstructure evolution of the interfacial morphology, elemental, and phase distribution\\u000a are probed with the aid of electron-probe

C. C. Young; J. G. Duh; S. Y. Tsai

2001-01-01

26

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

NASA Astrophysics Data System (ADS)

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.

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

2012-07-01

27

Influence of Pd Concentration on the Interfacial Reaction and Mechanical Reliability of the Ni\\/Sn-Ag-Cu-xPd System  

Microsoft Academic Search

The interfacial reaction between Ni and Sn-3Ag-0.5Cu-xPd alloys (x = 0 wt.% to 1 wt.%) at 250C and the mechanical reliability of the solder joints were investigated in this study. The reaction and the resulting mechanical properties were both strongly dependent on the Pd concentration. When x was low (<=0.2 wt.%), the reaction product at the Ni\\/Sn-Ag-Cu-xPd interface was a

C. E. Ho; L. H. Hsu; S. W. Lin; M. A. Rahman

2011-01-01

28

Interfaces in lead-free solder alloys: Enthalpy of formation of binary AgSn, CuSn and NiSn intermetallic compounds  

Microsoft Academic Search

Standard enthalpies of formation were determined for a number of binary intermetallic compounds in the systems AgSn, CuSn, and NiSn by means of solution calorimetry in liquid Sn in a Calvet-type microcalorimeter. For the pure elements Ag, Cu, and Ni, the limiting partial enthalpies of mixing as well as the enthalpies of solution at infinite dilution in Sn were measured

H. Flandorfer; U. Saeed; C. Luef; A. Sabbar; H. Ipser

2007-01-01

29

Influence of Pd Concentration on the Interfacial Reaction and Mechanical Reliability of the Ni\\/Sn-Ag-Cu- x Pd System  

Microsoft Academic Search

The interfacial reaction between Ni and Sn-3Ag-0.5Cu-xPd alloys (x=0wt.% to 1wt.%) at 250C and the mechanical reliability of the solder joints were investigated in this study. The reaction\\u000a and the resulting mechanical properties were both strongly dependent on the Pd concentration. When x was low (?0.2wt.%), the reaction product at the Ni\\/Sn-Ag-Cu-xPd interface was a layer of (Cu,Ni)6Sn5. An increase

C. E. Ho; L. H. Hsu; S. W. Lin; M. A. Rahman

30

Effect of Ni-Coated Carbon Nanotubes on the Corrosion Behavior of Sn-Ag-Cu Solder  

NASA Astrophysics Data System (ADS)

In this study, the effect of Ni-coated carbon nanotubes (Ni-CNTs) on the corrosion resistance of 95.8Sn-3.5Ag-0.7Cu (SAC) solder at ambient temperature in 3.5 wt.% NaCl solution was investigated using the potentiodynamic polarization method. The corrosion products were analyzed by field-emission scanning electron microscopy (S4800), energy-dispersive spectroscopy, and x-ray diffraction. The results showed that addition of Ni-CNTs enhanced the corrosion resistance of the SAC solder and that increasing the content of Ni-CNTs made the effect more evident. The mechanism of the corrosion resistance improvement is the formation of a compact corrosion layer of Ni-CNTs that provides an inert physical barrier to the initiation and development of corrosion. Furthermore, in the corrosion microcell produced by the Ni-CNTs dispersed in the SAC solder, the Ni-CNTs act as a third phase (electrode) which contributes to reducing the galvanic corrosion between Sn anode and Ag3Sn cathode. Hence, the corrosion resistance of the composite solders was improved.

Han, Y. D.; Chen, L.; Jing, H. Y.; Nai, S. M. L.; Wei, J.; Xu, L. Y.

2013-12-01

31

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

SciTech Connect

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 cast in the form of a generalized lattice-gas Hamiltonian containing effective pair interactions with arbitrary range. Furthermore, we show how the SOE-EAM method can be combined with either mean-field or Monte Carlo statistical mechanics techniques in order to calculate short-range-order (SRO) parameters, average nearest-neighbor bond lengths, and alloy thermodynamic properties which include contributions from static displacive relaxations and dynamic atomic vibrations. We demonstrate that the contributions to alloy heats of mixing arising from displacive relaxations can be sizeable, and that the neglect of these terms can lead to large overestimations of calculated phase-transition temperatures. The effects of vibrational free-energy contributions on the results of composition-temperature phase diagram calculations are estimated to be relatively small for the phase-separating alloy systems considered in this study. It is shown that within the SOE approach displacive effects can act only to displace the peak in the Fourier-transformed SRO parameter away from Brillouin-zone-boundary special points and towards the origin. Consistent with this result, we show that the unusual SRO observed in diffuse scattering experiments for Au-Ni solid solutions can be understood as arising from a competition between chemical and displacive driving forces which favor ordering and clustering, respectively. {copyright} {ital 1996 The American Physical Society.}

Asta, M.; Foiles, S.M. [Computational Materials Science Department, Sandia National Laboratories, P.O. Box 939, MS 9163, Livermore, California 94551-0939 (United States)] [Computational Materials Science Department, Sandia National Laboratories, P.O. Box 939, MS 9163, Livermore, California 94551-0939 (United States)

1996-02-01

32

Fabrication of Cu-Ni mixed phase layer using DC electroplating and suppression of Kirkendall voids in Sn-Ag-Cu solder joints  

NASA Astrophysics Data System (ADS)

A solderable layer concurrently containing Cu-rich and Ni-rich phases (mixed-phase layer, MPL) was fabricated by direct current electroplating under varying process conditions. Current density was considered as the main parameter to adjust the microstructure and composition of MPL during the electroplating process, and deposit thickness were evaluated as functions of plating time. As a result, it was observed that the coral-like structure that consisted of Cu-rich and Ni-rich phases grew in the thickness direction. The most desirable microstructure was obtained at a relatively low current density of 0.4 mA/cm2. In other words, the surface was the smoothest and defect-free at this current density. The electroplating rate was slightly enhanced with an increase in current density. Investigations of its solid-state reaction properties, including the formation of Kirkendall voids, were also carried out after reflow soldering with Sn-3.0 Ag-0.5 Cu solder balls. In the solid-state aging experiment at 125C, Kirkendall voids at the normal Sn-3.0 Ag-0.5 Cu solder/Cu interface were easily formed after just 240 h. Meanwhile, the presence of an intermetallic compound (IMC) layer created in the solder/MPL interface indicated a slightly lower growth rate, and no Kirkendall voids were observed in the IMC layer even after 720 h.

Chee, Sang-Soo; Lee, Jong-Hyun

2014-05-01

33

Atomic size and chemical effects on the local order of Zr2M ( M=Co , Ni, Cu, and Ag) binary liquids  

NASA Astrophysics Data System (ADS)

First-principles molecular dynamics simulations are performed to investigate the atomic size and chemical effects on the short-range order (SRO) in superheated and undercooled Zr-based metallic liquids, Zr2M ( M=Co , Ni, Cu, and Ag). We demonstrate that the local atomic structures in liquids are quite sensitive to the atomic size ratio and the electronic interactions between component elements. The large negative heats of mixing for Zr-M do not favor icosahedral SRO in these binary liquids, contrary to the common belief. Full icosahedral structure units are few in the superheated liquids, although the number of icosahedral clusters increases upon undercooling. Comparing Zr2Co , Zr2Ni , and Zr2Cu , all of which have very similar atomic size ratios, we find that the degree of local icosahedral order increases with decreasing interaction strength between the d electrons in Zr-Co, Zr-Ni, and Zr-Cu. A comparison of Zr2Cu and Zr2Ag alloys shows that the degree of icosahedral order increases much more in Zr2Ag than in Zr2Cu with decreasing temperature. The difference in atomic sizes of Cu and Ag may account for the subtle discrepancy in the evolution of short-range ordering in undercooled Zr2Cu and Zr2Ag liquids.

Huang, Li; Wang, C. Z.; Hao, S. G.; Kramer, M. J.; Ho, K. M.

2010-01-01

34

Detailed Phase Evolution of a Phosphorous-Rich Layer and Formation of the Ni-Sn-P Compound in Sn-Ag-Cu\\/Electroplated NiP Solder Joints  

Microsoft Academic Search

The interfacial microstructure of Sn-3Ag-0.5Cu\\/Ni-P with various phosphorous contents was investigated by analytical transmission\\u000a electron microscopy (TEM) and field-emission electron probe microanalysis (FE-EPMA). As the Ni-Sn-P compound was formed between\\u000a the solder matrix and Ni-P under bump metallization (UBM), the so-called phosphorous-rich layer was transformed to a series\\u000a of layer compounds, including Ni3P, Ni12P5, and Ni2P. The relationship between Ni-Sn-P

Yung-Chi Lin; Kai-Jheng Wang; Jenq-Gong Duh

2010-01-01

35

Interfacial reactions of SnCu and SnPbAg solder with Au\\/Ni during extended time reflow in ball grid array packages  

Microsoft Academic Search

Lead-free solders with high Sn content cause excessive interfacial reactions at the interface with under-bump metallization during reflow. The interface formed after reflow affects the reliability of the solder joint. For this paper, we investigated the interfacial reactions of Sn0.7Cu and Sn36Pb2Ag solder on electrolytic Ni layer for different reflow times. The traditionally used Sn36Pb2Ag solder was used as a

M. N. Islam; Y. C. Chan; A. Sharif

2004-01-01

36

Interfacial reaction between Sn3.0Ag0.5Cu liquid solder and NixZn novel UBM layers  

Microsoft Academic Search

This work aims to investigate the interfacial reaction under liquid reactions of Sn3.0Ag0.5Cu (SAC305) joints with NixZn films by sputtering. The surface roughness and residual stress of the NixZn film, which was regarded to an under bump metallization (UBM), were evaluated using atomic force microscope (AFM) and the curvature measurement. The X-ray diffractometry (XRD) was used to further identify microstructures.

Hsiu-Min Lin; Jenq-Gong Duh

37

The germanides ScTGe (T=Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au) - Structure and 45Sc solid state NMR spectroscopy  

NASA Astrophysics Data System (ADS)

The germanides ScTGe (T=Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au) were obtained in X-ray pure form by arc-melting of the elements. The structures of the members with T=Co, Ni, Cu, Rh, Pd, Ag, Ir, and Pt were refined on the basis of single crystal X-ray diffractometer data. The germanides with T=Cu, Ru, Pd, Ag crystallize with the hexagonal ZrNiAl type structure, space group P 6 bar 2m and those with T=Co, Ni, Rh, Ir, Pt adopt the orthorhombic TiNiSi type. ScAuGe is isotypic with NdPtSb. All germanides exhibit single scandium sites. A simple systematization of the structure type according to the valence electron concentration is not possible. The 45Sc solid state NMR parameters (Knight shifts and nuclear electric quadrupole coupling constants) of those members crystallizing in the TiNiSi structure show systematic trends as a function of valence electron concentration number. Furthermore, within each T-group the Knight shift decreases with increasing atomic number; this correlation also includes previously published results on the isotypic silicide family. The 45Sc quadrupolar interaction tensor components are generally well-reproduced by quantum mechanical electric field gradient calculations using the WIEN2k code.

Heying, Birgit; Haverkamp, Sandra; Rodewald, Ute Ch; Eckert, Hellmut; Peter, Sebastian C.; Pttgen, Rainer

2015-01-01

38

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)

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. 300C 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.

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

2011-06-01

39

The study of the interfacial reaction between Sn\\/Ni\\/Cu substrates of PTH components and Sn-xAg-xCu solder pastes after performing Wave-Soldering process  

Microsoft Academic Search

The experimental samples mainly are the assembled OSP PCB with the Plated-Through-Hole (PTH) components which leads are manufactured with Sn\\/Ni\\/Cu substrates and the soldering process is Wave-Soldering (W\\/S) with two kinds of lead-free SAC solder bars categorized as Sn-3.0wt%Ag-0.5wt%Cu (SAC305) and Sn-0.3wt%Ag-0.7wt%Cu (SC0307). In addition, the test conditions are defined that the experimental temperatures are set at 100C, 150C, and

Lee Chieng-Hong; Tsai Hui-Chuan; Liao Meng-Chieh

2010-01-01

40

A new class of amorphous cathode active material LixMyPOz (M=Ni, Cu, Co, Mn, Au, Ag, Pd)  

NASA Astrophysics Data System (ADS)

A new class of amorphous cathode active material LixMyPOz (LiMPO) is proposed. The materials are sputter deposited to thin film form by Li3PO4 together with metal or metal oxide targets. Among several materials tested as thin-film battery, working material found are M=Ni, Cu, Co, Mn, Au, Ag, Pd. The property is intensively studied for LixCuyPOz (LiCuPO) and LixNiyPOz (LiNiPO). Those materials shows wide composition margin such as composition y between 1 and 3, and high capacity for LiNiPO with maximum value of 330mAhg-1. The capability to charge and discharge at high rate is shown up to 30C. This preliminary report reveals its high potentiality for further optimization.

Sabi, Yuichi; Sato, Susumu; Hayashi, Saori; Furuya, Tatsuya; Kusanagi, Susumu

2014-07-01

41

Microstructural and mechanical properties of SnAgCu lead-free solders with minor addition of Ni and\\/or Co  

Microsoft Academic Search

The effects of minor additives, that is, Co and Ni, on the microstructural and mechanical properties of Sn3.0mass%Ag0.5mass%Cu\\u000a (SAC305) bulk solder were investigated. The addition of Co and\\/or Ni resulted in microstructural changes of the SAC305 solder,\\u000a such as the formation of new intermetallic compounds (IMCs) and the refinement of grain size, as well as the suppression of\\u000a undercooling. The

Fangjie Cheng; Hiroshi Nishikawa; Tadashi Takemoto

2008-01-01

42

Effect of Bath Life of Ni(P) on the Brittle-Fracture Behavior of Sn-3.0Ag-0.5Cu/ENIG  

NASA Astrophysics Data System (ADS)

The effect of bath life of Ni(P) on the brittle-fracture behavior of Sn-3.0 wt.%Ag-0.5 wt.%Cu (SAC)/electroless nickel immersion gold (ENIG) was evaluated in this study. The bath lives of Ni(P) for the ENIG surface finish in this study were varied from 0 to 3 metal turnover (MTO), which were indirectly indicative of Ni(P) bath life, with "0 MTO" denoting the as-make-up state and "3 MTO" denoting almost waste plating solution. The SAC/ENIG sample when Ni(P) was plated in the 3 MTO bath (3 MTO sample) had thicker (Cu,Ni)6Sn5 and P-rich layers than when Ni(P) was plated in the 0 MTO bath (0 MTO sample). The brittle-fracture behavior of the 0 and 3 MTO samples was evaluated by use of a igh-speed shear (HSS) test with a strain rate of 0.1-2.0 m/s. The shear strength of the 0 MTO sample was higher than that of the 3 MTO sample. The incidence of brittle fracture increased as the bath life of Ni(P) of ENIG (= MTO of Ni(P)) increased. Observation by transmission electron microscopy (TEM) revealed nano-sized voids (or particles) in the Ni-Sn-P layer. As the MTO of the Ni(P) increased, the number of nano-sized voids in the Ni-Sn-P layer of the SAC/ENIG interface increased. The poor brittle-fracture behavior of the 3 MTO sample originated from the weak interface at the thick P-rich layer and from the large nano-sized voids.

Seo, Wonil; Kim, Kyoung-Ho; Bang, Jung-Hwan; Kim, Mok-Soon; Yoo, Sehoon

2014-09-01

43

The Shear Strength and Fracture Behavior of Sn-Ag- xSb Solder Joints with Au/Ni-P/Cu UBM  

NASA Astrophysics Data System (ADS)

This study investigates the effects of Sb addition on the shear strength and fracture behavior of Sn-Ag-based solders with Au/Ni-P/Cu underbump metallization (UBM) substrates. Sn-3Ag- xSb ternary alloy solder joints were prepared by adding 0 wt.% to 10 wt.% Sb to a Sn-3.5Ag alloy and joining them with Au/Ni-P/Cu UBM substrates. The solder joints were isothermally stored at 150C for up to 625 h to study their microstructure and interfacial reaction with the UBM. Single-lap shear tests were conducted to evaluate the mechanical properties, thermal resistance, and failure behavior. The results show that UBM effectively suppressed intermetallic compound (IMC) formation and growth during isothermal storage. The Sb addition helped to refine the Ag3Sn compounds, further improving the shear strength and thermal resistance of the solders. The fracture behavior evolved from solder mode toward the mixed mode and finally to the IMC mode with increasing added Sb and isothermal storage time. However, SnSb compounds were found in the solder with 10 wt.% Sb; they may cause mechanical degradation of the solder after long-term isothermal storage.

Lee, Hwa-Teng; Hu, Shuen-Yuan; Hong, Ting-Fu; Chen, Yin-Fa

2008-06-01

44

Multi-stage Ag-Bi-Co-Ni-U and Cu-Bi vein mineralization at Wittichen, Schwarzwald, SW Germany: geological setting, ore mineralogy, and fluid evolution  

NASA Astrophysics Data System (ADS)

The Wittichen Co-Ag-Bi-U mining area (Schwarzwald ore district, SW Germany) hosts several unconformity-related vein-type mineralizations within Variscan leucogranite and Permian to Triassic redbeds. The multistage mineralization formed at the intersection of two fault systems in the last 250 Ma. A Permo-Triassic ore stage I with minor U-Bi-quartz-fluorite mineralization is followed by a Jurassic to Cretaceous ore stage II with the main Ag and Co mineralization consisting of several generations of gangue minerals that host the sub-stages of U-Bi, Bi-Ag, Ni-As-Bi and Co-As-Bi. Important ore minerals are native elements, Co and Ni arsenides, and pitchblende; sulphides are absent. The Miocene ore stage III comprises barite with the Cu-Bi sulfosalts emplectite, wittichenite and aikinite, and the sulphides anilite and djurleite besides native Bi, chalcopyrite, sphalerite, galena and tennantite. The mineral-forming fluid system changed from low salinity (<5 wt.% NaCl) at high temperature (around 300C) in Permian to highly saline (around 25 wt.% NaCl + CaCl2) at lower temperatures (50-150C) in Triassic to Cretaceous times. Thermodynamic calculations and comparison with similar mineralizations worldwide show that the Mesozoic ore-forming fluid was alkaline with redox conditions above the hematite-magnetite buffer. We suggest that the precipitation mechanism for native elements, pitchblende and arsenides is a decrease in pH during fluid mixing processes. REE patterns in fluorite and the occurrence of Bi in all stages suggest a granitic source of some ore-forming elements, whereas, e.g. Ag, Co and Ni probably have been leached from the redbeds. The greater importance of Cu and isotope data indicates that the Miocene ore stage III is more influenced by fluids from the overlying redbeds and limestones than the earlier mineralization stages.

Staude, Sebastian; Werner, Wolfgang; Mordhorst, Teresa; Wemmer, Klaus; Jacob, Dorrit E.; Markl, Gregor

2012-03-01

45

Direct measurements of irradiation-induced creep in micropillars of amorphous Cu56Ti38Ag6, Zr52Ni48, Si, and SiO2  

NASA Astrophysics Data System (ADS)

We report in situ measurements of irradiation-induced creep on amorphous (a-) Cu56Ti38Ag6, Zr52Ni48, Si, and SiO2. Micropillars 1 ?m in diameter and 2 ?m in height were irradiated with 2 MeV heavy ions during uniaxial compression at room temperature. The creep measurements were performed using a custom mechanical testing apparatus utilizing a nanopositioner, a silicon beam transducer, and an interferometric laser displacement sensor. We observed Newtonian flow in all tested materials. For a-Cu56Ti38Ag6, a-Zr52Ni48, a-Si, and Kr+ irradiated a-SiO2 irradiation-induced fluidities were found to be nearly the same, ?3 GPa-1 dpa-1, whereas for Ne+ irradiated a-SiO2 the fluidity was much higher, 83 GPa-1 dpa-1. A fluidity of 3 GPa-1 dpa-1 can be explained by point-defect mediated plastic flow induced by nuclear collisions. The fluidity of a-SiO2 can also be explained by this model when nuclear stopping dominates the energy loss, but when the electronic stopping exceeds 1 keV/nm, stress relaxation in thermal spikes also contributes to the fluidity.

zerin, Sezer; Kim, Hoe Joon; Averback, Robert S.; King, William P.

2015-01-01

46

Phase Equilibria in the Ag-Ni-Sn System: Isothermal Sections  

Microsoft Academic Search

The ternary system Ag-Ni-Sn is one of the constituents of the quaternary system Ag-Cu-Ni-Sn, which is of interest for the\\u000a investigation of the interactions of Ag-Cu-Sn solder alloys with Ni as a substrate. Until now, only limited research has been\\u000a done on the Ag-Ni-Sn system, especially in the (Ag,Ni)-rich part, most probably due to experimental difficulties caused by\\u000a the monotectic

Clemens Schmetterer; Hans Flandorfer; Klaus W. Richter; Herbert Ipser

2007-01-01

47

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

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

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

2014-10-01

48

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

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

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

1995-01-01

49

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

NASA Astrophysics Data System (ADS)

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.

Hedayati, Kambiz

2015-03-01

50

Reaction kinetics of Pb-Sn and SnAg solder balls with electroless NiP\\/Cu pad during reflow soldering in microelectronic packaging  

Microsoft Academic Search

Detailed microstructural studies were carried out to compare the reaction kinetics of Pb-Sn solder and Sn-Ag solder with electroless Ni-P layer for different reflow times. It was found that Sn-Ag solder reacts at a faster rate with the electroless Ni-P layer to form a Ni-Sn intermetallic compound (IMC) and hence a P-rich layer is formed quickly by expellation of the

M. O. Alam; Y. C. Chan; K. C. Hung

2002-01-01

51

Mechanical properties of the high-entropy alloy Ag0.5CoCrCuFeNi at temperatures of 4.2-300 K  

NASA Astrophysics Data System (ADS)

The plastic deformation behavior of the high-entropy alloy Ag0.5CoCrCuFeNi produced in an argon-arc melt is studied for the first time at low temperatures (down to 4.2 K). Lowering the temperature from 300 to 4.2 K leads to an increase in the nominal yield strength from 450 to 750 MPa while the degree of plasticity of the alloy remains on the order of 30% over the entire range. The strain rate sensitivity is measured for deformations ? 2% by strain rate cycling. Assuming thermally activated plasma deformation, the activation volume for movement of dislocations is calculated for ? 2% and is found to vary from 122b3 at 300 K to 35b3 at 30 K, where b is the Burgers vector.

Laktionova, M. A.; Tabchnikova, E. D.; Tang, Z.; Liaw, P. K.

2013-07-01

52

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  

Microsoft Academic Search

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

M. Geretschlaeger; O. Benka

1986-01-01

53

K-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  

Microsoft Academic Search

Absolute K-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

M. Geretschlger; O. Benka

1986-01-01

54

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

SciTech Connect

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.

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

2014-12-01

55

Application of activated M/ZnO (M?=?Mn, Co, Ni, Cu, Ag) in photocatalytic degradation of diazo textile coloring dye.  

PubMed

Activated ZnO powder has been prepared by procedures involving first its dissolution in nitric acid, then simultaneous treatment by adding NH4OH and CO2 bubbling leading to precipitation as Zn(OH)CO3 (ZH) and further thermal decomposition of ZH at 400 C. The gas evolution leads to formation of pores and increase in the specific surface area. Chemically activated M/ZnO powders doped with Mn, Co, Ni, Cu, and Ag have been obtained by the impregnation method. The samples have been characterized by ultraviolet-visible (UV-Vis) spectroscopy, diffuse reflectance (DR) UV-Vis, X-ray diffraction (XRD), single point Brunauer-Emmet-Teller (BET), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) methods. The experiments have shown that metal-doped activated ZnO powders possess higher photocatalytic activities in oxidative discoloration of model contaminant textile coloring dye Reactive Black 5 in slurry reactor compared to that of the pure ZnO. The XRD and XPS data have shown the presence of defects, nonstoichiometricity implying the formation of solid solutions. Copper-doped (1.5 wt%) activated ZnO (Cu(2+) replaces Zn(2+)) is outstanding in its photocatalytic performance in discoloration of the dye due to the higher specific surface area and improved charge carrier separation. PMID:24996938

Milenova, K; Avramova, I; Eliyas, A; Blaskov, V; Stambolova, I; Kassabova, Nikoleta

2014-11-01

56

An investigation of temperature influence on the SAC305 soldering on Cu-Ni-Au substrate  

Microsoft Academic Search

In the present paper, the intermetallic compound (IMC) thickness as a function of annealing temperature has been carefully investigated. It is observed that the IMC ingredients along the Sn3.5Ag0.5Cu (SAC305) solder on the Cu-Ni-Ag substrate are (Ni, Cu)3Sn4 and (Cu, Ni)6Sn5 after IR-reflow process. Based on the measurement of IMC thickness and ball shear force, the following conclusions have been

Hsiang-Chen Hsu; Yu-Ming Wan; Chi-Hau Haung; Shen-Li Fu

2011-01-01

57

Molecular-dynamics studies of the thermal properties of the solid and liquid fcc metals Ag, Au, Cu, and Ni using many-body interactions  

NASA Astrophysics Data System (ADS)

Molecular-dynamics (MD) simulations of pure Ag, Au, Cu, and Ni are reported. The NPT (isobaric-isothermal) MD method is used in order to reveal the behavior of these metals at various temperatures in the solid as well as in the liquid state. According to the embedded-atom method [M. S. Daw and M. I. Baskes, Phys. Rev. B 29, 6443 (1984)] the interactions in metals are assumed to be composed of the pair component (caused by cores overlapping) and the cohesive many-body term (gluing term). The scheme for the empirical N-body potentials derivation proposed by Ackland et al. [G. J. Ackland, G. Tichy, V. Vitek, and M. W. Finnis, Philos. Mag A 56, 735 (1987)] is used. The potential parameters have been derived exclusively on the basis of the room-temperature properties (the equilibrium lattice constant, elastic constants, the cohesive energy, the stacking-fault energy, the unrelaxed vacancy-formation energy, and the volume-pressure dependency). The various quantities describing the temperature-dependent behavior of the simulated systems (thermal-expansion coefficients of solids and liquids, specific heats of solids and liquids, the volume change on melting, and the enthalpy of melting) as well as the radial distribution functions at various temperatures are derived. Generally, satisfactory agreement with the experimental data is achieved.

Holender, Janusz M.

1990-04-01

58

Partitioning of V, Mn, Co, Ni, Cu, Zn, As, Mo, Ag, Sn, Sb, W, Au, Pb, and Bi between sulfide phases and hydrous basanite melt at upper mantle conditions  

NASA Astrophysics Data System (ADS)

The partitioning of 15 major to trace metals between monosulfide solid solution (MSS), sulfide liquid (SL) and mafic silicate melt (SM) was determined in piston-cylinder experiments performed at 1175-1300 C, 1.5-3.0 GPa and oxygen fugacities ranging from 3.1 log units below to 1.0 log units above the quartz-fayalite-magnetite fO2 buffer, which conditions are representative of partial melting in the upper mantle in different tectonic settings. The silicate melt was produced by partial melting of a natural, amphibole-rich mantle source rock, resulting in hydrous (5 wt% H2O) basanitic melts similar to low-degree partial melts of metasomatized mantle, whereas the major element composition of the starting sulfide (52 wt% Fe; 39 wt% S; 7 wt% Ni; 2 wt% Cu) was similar to the average composition of sulfides in this environment. SL/SM partition coefficients are high (?100) for Au, Ni, Cu, Ag, Bi, intermediate (1-100) for Co, Pb, Sn, Sb (As, Mo), and low (?1) for the remaining elements. MSS/SM partition coefficients are generally lower than SL/SM partition coefficients and are high (?100) for Ni, Cu, Au, intermediate (1-100) for Co, Ag (Bi, Mo), and low (?1) for the remaining elements. Most sulfide-silicate melt partition coefficients vary as a function of fO2, with Mo, Bi, As (W) varying by a factor >10 over the investigated fO2 range, Sb, Ag, Sn (V) varying by a factor of 3-10, and Pb, Cu, Ni, Co, Au, Zn, Mn varying by a factor of 3-10. The partitioning data were used to model the behavior of Cu, Au, Ag, and Bi during partial melting of upper mantle and during fractional crystallization of primitive MORB and arc magmas. Sulfide phase relationships and comparison of the modeling results with reported Cu, Au, Ag, and Bi concentrations from MORB and arc magmas suggest that: (i) MSS is the dominant sulfide in the source region of arc magmas, and thus that Au/Cu ratios in the silicate melt and residual sulfides may decrease with increasing degree of partial melting, (ii) both MSS and sulfide liquid are precipitated during fractional crystallization of MORB, and (iii) fractional crystallization of arc magmas is strongly dominated by MSS.

Li, Yuan; Audtat, Andreas

2012-11-01

59

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

NASA Astrophysics Data System (ADS)

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.

Walch, Hermann; Leoni, Thomas; Guillermet, Olivier; Langlais, Vronique; Scheuermann, Andrew; Bonvoisin, Jacques; Gauthier, Sbastien

2012-08-01

60

Cu-Ni-Sn: A Key System for Lead-Free Soldering  

Microsoft Academic Search

Being the most complex constituent of the quaternary system Ag-Cu-Ni-Sn, the ternary system Cu-Ni-Sn is the key system for\\u000a the investigation of the interactions of Ag-Cu-Sn solder alloys with Ni as a contact material. Although this system has been\\u000a thoroughly studied in the literature, there are still many uncertainties left. In the present work, a study of the phase equilibria

C. Schmetterer; H. Flandorfer; Ch. Luef; AA Kodentsov; H. Ipser

2009-01-01

61

The interfacial reaction between Sn-Zn-Ag-Ga-Al solders and metallized Cu substrates  

NASA Astrophysics Data System (ADS)

The interfacial interaction between the Sn-8.55Zn-0.5Ag-0.5Ga-0.1Al solder and three kinds of metallized substrates (Cu, Cu/Au, and Cu/Ni-P/Au) does not form the Cu-Sn intermetallic compound (IMC). Continuous Cu-Zn and discontinuous Ag-Zn interfacial IMC layers formed between the Cu and Sn-Zn-Ag-Ga-Al solder, while Cu-Zn and Au-Al-Zn IMCs formed on the Cu/Au substrate. Only the Au-Al-Zn IMC formed at the interface when the electroless Ni-P deposit was the diffusion barrier between Cu and the Au surface layer.

Chuang, Chiang-Ming; Hung, Hui-Tzu; Liu, Pei-Chi; Lin, Kwang-Lung

2004-01-01

62

Novel nanoporous binary AgNi electrocatalysts for hydrazine oxidation  

Microsoft Academic Search

From an aqueous mixture of Ag(I)-EDTA complex and Ni(II) nitrate, silver and nickel particles were co-deposited on the surface\\u000a of titanium substrates by the hydrothermal method using hydrazine hydrate as a reduction agent. The prepared titanium-supported\\u000a nano-scale Ag and Ag-Ni particles (nano Ag\\/Ti, nano Ag86Ni14\\/Ti, nano Ag77Ni23\\/Ti, and nano Ag74Ni26\\/Ti) exhibit nanoporous 3D network textures. Their electrocatalytic activity towards hydrazine

Qingfeng Yi; Lei Li; Wenqiang Yu; Xiaoping Liu; Zhihua Zhou; Huidong Nie

2010-01-01

63

Interfacial Reactions Between Cu-Ag Alloy Substrates and Sn  

NASA Astrophysics Data System (ADS)

Interfacial reactions between Sn and Cu- xAg alloys ( x = 0 at.%, 11.1 at.%, 33.3 at.%, and 50 at.%) were investigated. The as-prepared Cu-Ag alloys displayed a microstructure composed of a proeutectic (Cu) phase and a eutectic (Cu) + (Ag) structure, where the fraction of the eutectic structure increased with increasing Ag content. At 200C and 250C, reactions to form Cu6Sn5 and Cu3Sn phase occurred at the Sn/Cu-Ag interface, and also inside the Cu-Ag substrate along the (Ag)/(Cu) interphase interface. The penetrated growth behavior by way of the (Ag)/(Cu) interphase interface accelerated the growth rate of the intermetallic compounds and the consumption of the Cu-Ag substrates. A comparison between conventional Sn/Cu and Sn/Cu-Ag systems indicated that addition of Ag to Cu had a significant accelerating effect on the Sn/Cu- xAg interfacial reaction to form Cu6Sn5.

Yang, Teng-Kai; Lin, Chih-Fan; Chen, Chih-Ming

2015-01-01

64

Deformation behavior of (Cu, Ag)Sn intermetallics by nanoindentation  

Microsoft Academic Search

Nanoindentation is an important technique for probing the mechanical behavior of materials at small length scales. In this study, nanoindentation was used to extract the elastic and plastic properties of Cu, Sn3.5Ag solder, Ag3Sn, and intermetallics in Cu\\/SnAg solder joints including Cu6Sn5, and Cu3Sn. The elastic and plastic properties of Cu, Sn3.5Ag solder, Ag3Sn, Cu6Sn5, and Cu3Sn were measured and

X. Deng; N. Chawla; K. K. Chawla; M. Koopman

2004-01-01

65

Intermetallic compound formation between Sn3.5Ag solder and Ni-based metallization during liquid state reaction  

Microsoft Academic Search

Ni and its alloys possess a lower reaction rate with Sn than Cu and Cu alloys. Ni-based under bump metallization (UBM) therefore receives considerable attention from the microelectronic packaging industry for the popular flipchip applications. In this work, we study the interfacial reaction of electroless NiP (EN) alloy and Ni UBMs with Sn3.5Ag solder. Morphology and growth kinetics of the

Min He; Wee Hua Lau; Guojun Qi; Zhong Chen

2004-01-01

66

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

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.

Kim, Kwang Joo.

1990-10-17

67

Analytical performance of a lab-made concomitant metal analyzer to generate volatile species of Ag, Au, Cd, Cu, Ni, Sn and Zn using 8-hydroxyquinoline as a reaction media.  

PubMed

This study evaluated the main parameters affecting Ag, Au, Cd, Cu, Ni, Sn and Zn vapor generation using a lab-made concomitant metal analyzer (CMA) as a reaction chamber and gas-liquid separator. The modifier used in the reaction media was 8-hydroxyquinoline, and Inductively-Coupled Plasma Optical Emission Spectrometry was used as detection technique. The performance of the lab-made concomitant analyzer was compared with the performance of a continuous flow gas-liquid separator and of a cyclonic spray chamber. Standards were prepared in acid media and included 1 mg L(-1) of Co as a catalyzer. The optimum concentrations of the reagents in the standards were: 450 mg L(-1) of 8-hydroxyquinoline and 0.4 M nitric acid. The optimum concentration of sodium borohydride to generate the vapors was 2.25% (w/v) (prepared in 0.4% (w/v) NaOH). The volatile species were swept from the CMA to the torch by an argon flow of 0.6 mL min(-1). The use of the CMA led to an improvement of the detection limits for some elements compared to conventional nebulization: 1.1 ?g L(-1) for Ag, 7.0 ?g L(-1) for Au and 4.3 ?g L(-1) for Sn. The limit of detection for Cu was 1.4 ?g L(-1) and for Ni 22.5 ?g L(-1). The direct mixing of the reagents on the spray chamber was not effective for Cd and Zn; a deviation of the linearity was observed for these elements. PMID:23141310

Villanueva-Alonso, Julia; Pea-Vzquez, Elena; Bermejo-Barrera, Pilar

2012-10-15

68

Adhesive strength and tensile fracture of Ni particle enhanced SnAg composite solder joints  

Microsoft Academic Search

This study forms composite solders by adding 0.53wt% of Ni particles in situ to Sn3.5wt%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 150C for 100, 200, 400, or 500h, respectively.

H. T. Lee; Y. H. Lee

2006-01-01

69

Retardation of spalling by the addition of Ag in SnZnBi solder with the Au\\/Ni metallization  

Microsoft Academic Search

The work presented in this paper focuses on the role of Ag addition in the Sn8%Zn3%Bi solder on the shear strengths and the interfacial reactions with Au\\/Ni\\/Cu pad metallization in ball grid array (BGA) applications. SnZnBi(Ag) solder alloys were kept in molten condition (240C) on the Au\\/electrolytic Ni\\/Cu bond pads for different time periods ranging from 1 to 60min. After

A. Sharif; Y. C. Chan

2007-01-01

70

Ag/Ni/Ag Multilayer Reflector for GaN-Based Vertical Light-Emitting Diode  

NASA Astrophysics Data System (ADS)

We investigate the effect of Ni insertion on the electrical and thermal properties of Ag-based reflectors for GaN-based light emitting diodes (LEDs). It is shown that after annealing at 500 C, the surface of Ag only sample becomes significantly roughened due to agglomeration, whereas the surface of Ni-inserted Ag sample get roughened with elongated Ag hillocks on an 100-nm-thick Ag film. The Ni-inserted Ag contacts show higher reflectance (at 460 nm) than the Ag only sample after annealing at 500 C. The 500-C-annealed Ni-inserted Ag samples exhibit lower specific contact resistance than the annealed Ag only contacts. LEDs fabricated with the 500-C-annealed Ni-inserted Ag contact give lower forward-bias voltage and series resistance as compared to those of LEDs with the 500-C-annealed Ag only contact. The LEDs with the 500-C-annealed Ni-inserted Ag contact exhibit 18% higher light output power (at 20 mA) than the LEDs with the Ag only contacts annealed at 500 C. Based on the X-ray photoelectron spectroscopy and scanning electron microscopy results, the temperature dependence of the electrical characteristics of the Ni-inserted Ag contacts is described and discussed.

Yum, Woong-Sun; Jeon, Joon-Woo; Sung, Jun-Suk; Jin, Sungho; Seong, Tae-Yeon

2013-05-01

71

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

PubMed

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

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

72

Two phase microstructure for Ag-Ni nanowires  

NASA Astrophysics Data System (ADS)

In the present study, electrodeposition technique was used to produce Ag-Ni nanowires. Ag-Ni system shows extremely high bulk immiscibility. Nanowire morphology was achieved by employing an anodic alumina membrane having pores of 200 nm diameter. Microstructure of as-deposited wire was composed of nano-sized solid solution structured Ag-Ni nanoparticles embedded in a matrix of pure Ag phase. It is proposed that the two phase microstructure resulted from an initial formation of solid solution structured nanoparticles in the alumina template pore followed by nucleation of pure Ag phase over the particles which eventually grew to form the matrix phase.

Srivastava, Chandan; Rai, Rajesh Kumar

2013-03-01

73

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

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.

Geretschlaeger, M.; Benka, O.

1986-08-01

74

Characteristics of intermetallics and micromechanical properties during thermal ageing of SnAgCu flip-chip solder interconnects  

Microsoft Academic Search

Sn3.8wt.% Ag0.7wt.% Cu solder was applied to Al1wt.% Cu bond pads with an electroless nickel (NiP) interlayer as an under bump metallisation (UBM). The microstructure and micromechanical properties were studied after ageing at 80C and 150C. Two types of intermetallic compounds (IMCs) were identified by electron back-scattered diffraction (EBSD), these being a (Cu, Ni)6Sn5 formed at the solderUBM interface and

Dezhi Li; Changqing Liu; Paul P. Conway

2005-01-01

75

Mechanically reinforced {1 1 0} ?1 1 0? textured Ag\\/Ni-alloys composite substrates for low-cost coated conductors  

Microsoft Academic Search

New, reinforced {110}?110? textured Ag\\/Ni-alloys composite ribbons were developed as possible substrates for coated conductors without any buffer layer. The texture quality and tensile strength were investigated. A new technique to bond the Ag and Ni or alloy layers through a Cu foil was presented. The Ag\\/Ni-alloys composite ribbons were fabricated by choosing proper sintering processing to bond the different

Hongli Suo; Jean-Yves Genoud; Paola Caracino; Sergio Spreafico; Michael Schindl; Eric Walker; Ren Flkiger

2002-01-01

76

Effect of Ag micro-particles content on the mechanical strength of the interface formed between SnZn binary solder and Au\\/Ni\\/Cu bond pads  

Microsoft Academic Search

In this study, addition of Ag micro-particles with a content in the range between 0 and 4wt.% to a SnZn eutectic solder, were examined in order to understand the effect of Ag additions on the microstructural and mechanical properties as well as the thermal behavior of the composite solder formed. The shear strengths and the interfacial reactions of SnZn micro-composite

S. K. Das; A. Sharif; Y. C. Chan; N. B. Wong; W. K. C. Yung

2009-01-01

77

Polarity Effect in a Sn3Ag0.5Cu/Bismuth Telluride Thermoelectric System  

NASA Astrophysics Data System (ADS)

This study investigates electromigration in Bi2Te3 thermoelectric (TE) material systems and the effectiveness of the diffusion barrier under current. The Peltier effect on the interfacial reaction was decoupled from the effect of electromigration. After connecting p- and n-type Bi2Te3 to Sn3Ag0.5Cu (SAC305) solders, different current densities were applied at varying temperatures. The Bi2Te3 samples were fabricated by the spark plasma sintering technique, and an electroless nickel-phosphorous (Ni-P) layer was deposited at the solder/TE interfaces. The experimental results confirm the importance of the Ni diffusion barrier in joint reliability. Intermetallic compound layers (Cu,Ni)6Sn5 and NiTe formed at the solder/Ni-P and Ni-P/substrate interfaces, respectively. The experimental results indicate that the mechanism of NiTe and (Cu,Ni)6Sn5 compound growth was dominated by the Peltier effect at high current density. When the current density was low, the growth of NiTe was affected by electromigration but the changes of thickness for (Cu,Ni)6Sn5 were not obvious.

Chien, P. Y.; Yeh, C. H.; Hsu, H. H.; Wu, Albert T.

2014-01-01

78

Chemistry of Bonds Between Metals Bridged by Thiocyanate and Azide Ions Part I. MM' or 2(N3)2(NCS)2.2py [M = MN(II), Fe(II), Ni(II), Co(II), Cu(II), or Zn(II); M'? Ag(I), Hg(II) or Tl(I);  

Microsoft Academic Search

A new series of complexes of the type MM'1 or 2(N3)2(NCS)22py [M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II); M'? Ag(I), Hg(II) or Tl(I);] have been synthesised by the reactions of M(N3)2(py)2 with Ag2(SCN)2, Hg(SCN)2 or Tl2(SCN)2. These complexes have been characterised by elemental analysis, molar conductance, magnetic moment, infrared and electronic spectral studies. The structures proposed by these

S. B. Sharma

1990-01-01

79

Magnetic interactions in Ni-Cu/Cu superlattice nanowire arrays  

NASA Astrophysics Data System (ADS)

The remanent magnetization of Ni-Cu/Cu superlattice nanowires was investigated. Arrays of superlattice nanowires were prepared by template deposition through polycarbonate nanoporous membranes using a single electrolyte bath. The thicknesses of the nickel-rich layers (tNi) and copper layers (tCu) were independently controlled by monitoring the current during deposition. The wire diameter was determined by transmission electron microscopy imaging to be 80 nm. A study of the remanent magnetization at 20 K for a range of values of tNi and tCu reveals the existence of magnetic interactions within each array. It is noted that for an array with tNi of 200 , the strength of the interactions decreases with increasing tCu, indicating that the interactions are taking place between nickel layers. However the interaction strength appears to reach a minimum level, beyond which an increase in tCu does not correspond to a decrease in the interaction strength observed. A minimum interaction level is also observed for an array with tNi of 50 , for all values of tCu investigated.

Robinson, A.; Schwarzacher, W.

2003-05-01

80

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

NASA Astrophysics Data System (ADS)

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)].

Onat, Berk; Durukanoglu, Sondan

2012-02-01

81

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

Microsoft Academic Search

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

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

2004-01-01

82

Les minralisations Cu---(Ni---Bi---U---Au---Ag) d'Ifri (district du Haut Seksaoua, Maroc) : apport de l'tude  

E-print Network

developed in 100 m-sized stratabound lens-shaped breccia with a coarse-grain white dolomite matrix. This `white dolomite breccia' underlies black shales and grades both laterally and at the footwall into the lower carbonate shales (Fig. 1). The `white dolomite breccia' is the favourite host of the Cu stockwork

Boyer, Edmond

83

Barrier properties of thin Au\\/NiP under bump metallization for Sn3.5Ag solder  

Microsoft Academic Search

Electroless NiP with a thin layer of immersion gold has been considered as a promising under bump metallization (UBM) for low-cost flipchip technology. However, the presence of P in electroless NiP causes complicated interfacial reactions, which affect the reliability of solder joint. In this work, barrier properties of thin Au\\/NiP UBM between Cu substrate and Sn3.5Ag solder were investigated during

Aditya Kumar; Min He; Zhong Chen

2005-01-01

84

Cu and Ni solubility in high-temperature aqueous fluids  

NASA Astrophysics Data System (ADS)

Copper and nickel are generally associated in magmatic sulfide ores formed by immiscibility in mafic and ultramafic magmas. In contrast, hydrothermal Cu-Ni deposits are uncommon and these elements usually occur in separate Cu-Fe-sulfide and Ni-Co-Ag-Bi-As-S mineralizations. Among the porphyry-type deposits formed at high temperatures to about 700 C, there are many copper but no nickel deposits [1], pointing to a higher solubility of Cu relative to Ni in aqueous fluids at such conditions. The aim of this study is to measure the solubilities of Cu and Ni sulfides in high-temperature hydrothermal fluids in-situ using synchrotron-radiation micro-X-ray fluorescence spectrometry. Synthetic CuS or NiS crystals were partly dissolved in aqueous NaCl, NaCl+HCl, or CaCl2 solutions at temperatures of 400 to 600 C and pressures between 70 and 900 MPa using a modified hydrothermal diamond-anvil cell with a recess in one diamond [2]. Consecutive XRF spectra of the fluid in the recess were collected in a confocal mode to exclude signal contributions from the crystals in the sample chamber [3]. Equilibrium was assumed if the determined concentrations of the dissolved metals indicated that a steady state was attained. The measured dissolved Cu concentrations ranged between 22 ppm at 70 MPa, 500 C and 235 ppm at 306 MPa, 600 C in 0.5 to 1.6 m NaCl solutions. We observed a decrease in Cu concentration with increasing pressure at constant temperature, and for 1.6 m NaCl an increase by a factor of two along an isochore from 120 MPa, 500 C to 306 MPa, 600 C. Higher Cu solubilities were determined in more concentrated solutions. A preliminary run with a more acidic NaCl+HCl solution (pH ~1) revealed a dramatic increase in the dissolved Cu concentration to 7898 ppm at 170 MPa, 500 C. The measured dissolved Ni concentrations ranged between 3 ppm at 200 MPa, 500 C in a 1 m NaCl solution and 33 ppm at 411 MPa, 500 C in a 0.75 m CaCl2 solution. A solubility maximum at 500 C along an isochore was observed for both solutions. The Ni solubility increased with pressure at constant temperature. Experiments with aqueous CaCl2 solutions resulted in higher dissolved Ni concentrations compared to NaCl solutions at similar pressure-temperature conditions. Our experiments suggest that the solubility of Cu and Ni in aqueous fluids is mainly governed by fluid composition. For both elements, solubility increased in more chlorine-rich fluids, which could reflect metal-chlorine complexation. Preliminary results for Cu indicate a strong dependence of the solubility on the pH of the fluid. A contrasting solubility behavior of Cu and Ni was observed with increasing pressure, which might be one reason for the difference in hydrothermal ore deposit formation. [1] Barnes (1979) Geochemistry of hydrothermal ore deposits, Wiley. [2] Schmidt and Rickers (2003) Am. Mineral. 88, 288-292. [3] Wilke el al. (2010) J. Synchrotron Rad. 17, 669-675.

Watenphul, A.; Scholten, L.; Beermann, O.; Kavner, A.; Alraun, P.; Falkenberg, G.; Newville, M.; Lanzirotti, A.; Schmidt, C.

2013-12-01

85

Novel investigation on nanostructure Ni-P-Ag composite coatings  

NASA Astrophysics Data System (ADS)

In this research, silver particles with different contents were co-deposited within Ni-P coating on AISI 1045 steel samples by electroless plating process and then Ni-P-Ag composite coatings were heat treated at 400 C for 1 h. The concentration of silver particles in Ni-P metallic matrix was determined by using scanning electron microscopy (SEM) and image analysis software. The phase transformation of deposits was analyzed by X-ray diffraction (XRD) and differential thermal analysis (DTA). Also, the mechanical properties of coatings were evaluated by microhardness and indentation tests. The results showed that the content of silver particles and heat treatment have the great effects on hardness and mechanical properties of Ni-P-Ag electroless composite coatings. Also, heat treatment can lead only to phase transformation in metallic matrix of nanostucture Ni-P-Ag composite coatings.

Alirezaei, S.; Vaghefi, S. M. Monir; rgen, M.; Saatchi, A.; Kazmanli, K.

2012-11-01

86

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

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

87

Surface Segregation in Cu-Ni Alloys  

NASA Technical Reports Server (NTRS)

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.

Good, Brian; Bozzolo, Guillermo; Ferrante, John

1993-01-01

88

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

Microsoft Academic Search

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

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

1995-01-01

89

Influence of Ni on Cu precipitation in FeCuNi ternary alloy by an atomic study  

NASA Astrophysics Data System (ADS)

The early aging Cu precipitations in Fe3%Cu and Fe3%Cu4%Ni ternary alloys are investigated by molecular dynamics (MD) simulations. The results show that the average size of Cu clusters in Fe3%Cu4%Ni alloy is larger than that in Fe3%Cu alloy. The diffusion of Cu is accelerated by Ni according to the mean square displacement (MSD). Furthermore, the whole formation process of Cu-rich clusters is analyzed in detail, and it is found that the presence of Ni promotes small Cu-rich clusters to be combined into big ones. Ni atoms prefer to stay at the combination positions of small clusters energetically due to a large number of the first nearest neighbor CuNi interactions, which is verified by first-principles calculations based on density functional theory (DFT).

Zhu, Lu-Shan; Zhao, Shi-Jin

2014-06-01

90

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

SciTech Connect

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.

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

2001-01-01

91

Wetting interaction between Sn-Zn-Ag solders and Cu  

Microsoft Academic Search

The wetting interaction of Sn-(7.19)Zn-(03)Ag solders with Cu was investigated from 230C to 300C. The wetting time, wetting\\u000a forces, and activation energy of the wetting reaction were studied. The wetting time decreases with increasing temperature\\u000a and increases with Ag content. The wetting force exhibits a disproportional correlation to temperature rise, while no trend\\u000a was observed with respect to Ag content.

Kwang-Lung Lin; Chia-Ling Shih

2003-01-01

92

Infrared Brazing Ti50Ni50 and Invar Using Ag-Based Filler Foils  

NASA Astrophysics Data System (ADS)

Infrared brazing Ti50Ni50 and Invar using BAg-8 and Cusil-ABA foils was investigated. The Ag-Cu eutectic matrix dominates both brazed joints. The maximum shear strengths of the brazed joints using BAg-8 and Cusil-ABA fillers are 158 and 249 MPa. Failure of interfacial Fe2Ti/Ni3Ti reaction layers is responsible for the BAg-8 joint. In contrast, the Cusil-ABA brazed joint is fractured along the interfacial Fe2Ti intermetallic compound. Both fractographs are characterized with cleavage dominated fracture.

Shiue, R. K.; Chang, Y. H.; Wu, S. K.

2013-10-01

93

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

Microsoft Academic Search

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

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

2011-01-01

94

Nanoindentation characterization of NiCuSn IMC layer subject to isothermal aging  

Microsoft Academic Search

Lead-free SnAgCu(SAC) solder joint on CuOSP 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

Luhua Xu; John H. L. Pang

2006-01-01

95

Les minralisations Cu_(Ni_Bi_U_Au_Ag) d'Ifri (district du Haut Seksaoua, Maroc) : apport de l'tude texturale au dbat syngense versus pigenseThe 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)

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).

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

2003-11-01

96

Magnetic anisotropy of epitaxial Cu/Ni/Cu nanolines  

NASA Astrophysics Data System (ADS)

Continuous nickel films grown pseudoepitaxially between copper layers have been shown to have strong perpendicular magnetic anisotropy due to large magnetoelastic and interface magnetocrystalline anisotropy energies. These Cu/Ni/Cu films with tNi=6.9 nm have been patterned into lines approximately 200 nm wide using interferometric lithography and ion milling. Torque magnetometer measurements show the anisotropy of the nanolines to be significantly different from that of the continuous films. The magnetoelastic anisotropy (favoring perpendicular magnetization) decreases in the patterned films due to strain relaxation at the line edges. Although the anisotropy change for this line width is most likely due to shape anisotropy, we anticipate observation of magnetoelastic anisotropy due to strain relief at the edges of the lines at narrower line widths in future work.

Lyons, E. S.; O'Handley, R. C.; Ross, C. A.

2004-06-01

97

Ultraviolet-visible absorption, Raman, vibration spectra of pure silver and Ag-Cu clusters: A density functional theory study  

NASA Astrophysics Data System (ADS)

The UV-visible absorption spectra of Agn and Agn-1Cu1 (n=2-8, 13, 20, 32) clusters were investigated in the framework of TD-DFT using LC-?PBE (?=0.40) and the Raman and vibration spectra of Agn and Agn-1Cu1 (n=2-8, 13, 20, 32, 55) clusters were calculated by the DFT/GGA/PBE. The UV-visible absorption, Raman, vibration spectra of pure silver and Ag-Cu clusters are related with their sizes, compositions and structures. Blueshifts are obviously observed as following: from Ag2 to Ag3, from Ag4 to Ag13, from Ag20 to Ag32, from Ag1Cu1 to Ag2Cu1, from Ag3Cu1 to Ag4Cu1, from Ag5Cu1 to Ag12Cu1, from Ag19Cu1 to Ag31Cu1, and from Agn to Agn-1Cu1 (n=2-8, 20, 32); redshifts obviously appear as following changes: from Ag3 to Ag4 and from Ag13 to Ag20, from Ag2Cu1 to Ag3Cu1, from Ag4Cu1 to Ag5Cu1, from Ag13Cu1 to Ag19Cu1, and from Ag13 to Ag12Cu1. On the whole, the wavelengths of the maximum Raman peaks of pure Ag and Ag-Cu clusters lower with increasing cluster size; the intensities of the maximum Raman peaks of pure Ag and Ag-Cu clusters are weakly wavy as clusters change from Ag2 to Ag8, from Ag1Cu1 to Ag7Cu1, then, they (except Ag12Cu1) gradually strengthen with increasing cluster size, however, the intensity of Ag12Cu1 is larger than that of Ag19Cu1. The wavenumbers and intensities of the maximum vibration peaks of pure Ag and Ag-Cu clusters fluctuate with increasing cluster size. The calculated vibrational and Raman spectroscopy of pure Ag and Ag-Cu clusters may be helpful in determining sizes and structures of experimental clusters.

Li, Weiyin; Chen, Fuyi

2014-10-01

98

Perpendicularly magnetized spin filtering Cu/Ni multilayers  

NASA Astrophysics Data System (ADS)

Spin filtering at perpendicular magnetized Cu/Ni multilayer/GaAs(001) interfaces is demonstrated at remanence using optical spin orientation method. [Cu(9 nm)/Ni(tNi nm)]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 tNi = 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.

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

2014-01-01

99

Perpendicularly magnetized spin filtering Cu/Ni multilayers  

SciTech Connect

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.

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

100

Microstructure and Interfacial Reactions During Vacuum Brazing of Stainless Steel to Titanium Using Ag-28 pct Cu Alloy  

NASA Astrophysics Data System (ADS)

Microstructural evolution and interfacial reactions during vacuum brazing of grade-2 Ti and 304L-type stainless steel (SS) using eutectic alloy Ag-28 wt pct Cu were investigated. A thin Ni-depleted zone of -Fe(Cr, Ni) solid solution formed on the SS-side of the braze zone (BZ). Cu from the braze alloy, in combination with the dissolved Fe and Ti from the base materials, formed a layer of ternary compound , adjacent to Ti in the BZ. In addition, four binary intermetallic compounds, CuTi, CuTi, CuTi and CuTi formed as parallel contiguous layers in the BZ. The unreacted Ag solidified as islands within the layers of CuTi and CuTi. Formation of an amorphous phase at certain locations in the BZ could be revealed. The -Ti(Cu) layer, formed due to diffusion of Cu into Ti-based material, transformed to an -Ti + CuTi eutectoid with lamellar morphology. Tensile test showed that the brazed joints had strength of 112 MPa and failed at the BZ. The possible sequence of events that led to the final microstructure and the mode of failure of these joints were delineated.

Laik, A.; Shirzadi, A. A.; Sharma, G.; Tewari, R.; Jayakumar, T.; Dey, G. K.

2015-02-01

101

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

PubMed

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

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

2013-12-21

102

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

103

Effect of small Sn-Ag-Cu additions on structure and properties of Sn-Zn-Bi solder\\/BGA during as-soldered and as-aged conditions  

Microsoft Academic Search

Sn-8Zn-3Bi solder balls with different weight percentages of Sn-Ag-Cu addition were bonded to Au\\/Ni metallized Cu pads, and the effect of multiple reflow and aging on impact reliability was investigated. In the Sn-Ag-Cu content Sn-Zn-Bi solder joints, the AgZn3 intermetallic compound layer was clearly observed at the interfaces and its thickness increased with an increase the number of reflow cycles

Asit Kumar Gain; Y. C. Chan; Ahmed Sharif; W. K. C. Yung

2009-01-01

104

Photoemission from Ag, Cu, and CsI  

SciTech Connect

Photoemission characteristics of three different cathodes, CsI, Ag film and Cu were investigated. CsI, upon irradiation by 213 nm, 10ps laser pulse yields a quantum efficiency of 4% at O.2[mu]J input energy. The saturation mechanism observed at higher input energies require further investigation. Ag film, upon irradiation by 630 nm, 300 fs laser emit prompt photoelectrons after absorbing 2 photons. There was no evidence of optical damage of the film up to 10[sup 11] W/cm[sup 2]. At low intensities, photoemission from Cu is a simple [nu]-e[sup [minus

Srinivasan-Rao, T.; Fischer, J.; Tsang, T.

1992-06-01

105

Synthesis of Cu core Ag shell nanoparticles using chemical reduction method  

NASA Astrophysics Data System (ADS)

A simple chemical reduction method is used to prepare colloidal bimetallic CuAg coreshell (Cu@Ag) nanoparticles. Polyvinyl pyrrolidone (PVP) was used as capping agent, and ascorbic acid (C6H8O6) and sodium borohydride (NaBH4) were used as reducing agents. The obtained Cu@Ag nanoparticles were characterized by powder x-ray diffraction (XRD), transmission electron microscopy (TEM) and UVvis spectrophotometry. The influence of [Ag]/[Cu] molar ratios on the formation of Ag coatings on the Cu particles was investigated. From the TEM results we found that the ratio [Ag+]/[Cu2+] = 0.2 is the best for the stability of Cu@Ag nanoparticles with an average size of 22 nm. It is also found out that adding ammonium hydroxide (NH4OH) makes the obtained Cu@Ag nanoparticles more stable over time when pure deionized water is used as solvent.

Chinh Trinh, Dung; Dung Dang, Thi My; Khanh Huynh, Kim; Fribourg-Blanc, Eric; Chien Dang, Mau

2015-01-01

106

Constitutive Modeling of Sn\\/Ag and Sn\\/Ag\\/Cu Solder Alloys  

Microsoft Academic Search

In this paper, we report some results from a recent study on developing constitutive laws suitable for Sn\\/Ag and Sn\\/Ag\\/Cu based solder materials. Extensive thermomechanical testing has been conducted on these lead-free solder alloys under various temperature (-55C-150C) and strain rate (10-7\\/s-10-1\\/s), subjected to both monotonic and cyclic loading. The experimental data are then used to develop a viscoplastic constitutive

Min Pei; Jianmin Qu

2006-01-01

107

Thermal stability of barrierless Cu-Ni-Sn films  

NASA Astrophysics Data System (ADS)

To increase the thermal stability against interface reaction, barrierless Cu-Ni-Sn seed layers, with compositions formulated according to the cluster-plus-glue-atom model for stable solid solutions, was investigated in this paper. In this model, Sn is dissolved in Cu via Ni which is soluble both with Cu and with Sn, and the stable solid solution is formulated as [Sn-Ni12]Cux, where the Sn-centered [Sn-Ni12] octahedral clusters are embedded in an FCC Cu matrix of x atoms. Cu-Ni-Sn films with various Ni/Sn ratios were deposited onto the Si(1 0 0) substrate by magnetron sputtering and were characterized for microstructure and for electrical resistivity. The (Sn1.1/13.1Ni12/13.1)0.3Cu99.7 (at.%) film, with its Ni/Sn composition ratio being close to the ideal 12/1 value of the model, showed the minimum electrical resistivity of 2.7 ?? cm on 500 C/1 h annealing among all the samples. The resistivity maintained as low as 2.8 ?? cm even after 400 C/40 h annealing. No Cu silicide was observed by XRD and TEM in this sample, though a minute amount of fine Cu-Sn compound precipitates was present. The superior diffusion inhibiting effect was attributed to Sn in solid solution via intermediate of Ni.

Li, X. N.; Wang, M.; Zhao, L. R.; Bao, C. M.; Chu, J. P.; Dong, C.

2014-04-01

108

Intermetallic compound layer growth at the interface between SnCuNi solder and Cu substrate  

Microsoft Academic Search

Phase analysis and growth kinetics of intermetallic compound (IMC) layers formed between low cost SnCuNi solder for wave soldering and Cu substrate by solid state isothermal aging were examined at temperatures between 80 and 150C 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.

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

109

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

; Cu; Ag; Ti; GaAs; GaN Sulfuric Acid (H2SO4): C; Cu; GaAs; Fe; Pb; Ni; Ti Aqua Regia (3 HCl : 1 HNO3 : hydrofluoric acid (49%, aq) HNO3 : nitric acid (70%, aq) H2SO4 : sulfuric acid (96%, aq) H3PO4 : phosphoricAcetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In

Garmestani, Hamid

110

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

PubMed

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

Her, H; Jrgensen, R; Srbrden, E; Suoninen, E

1982-05-01

111

Non-local first-principles calculations in Cu-Au, Ag-Au and Cu-Ag  

NASA Astrophysics Data System (ADS)

Cu-Au is the prototypical alloy system used to exemplify ordering and compound formation, and serves as a testbed for all new alloy theory methods. Yet, despite the importance of this system, conventional density functional theory (DFT) calculations with semi-local approximations (GGA) have two dramatic failures in describing the energies of this system: 1) DFT predicts incorrect ordered ground states for Au-rich compositions, and 2) DFT formation energies of the observed Cu3Au and CuAu compounds are nearly a factor of two smaller in magnitude than experimental values. Here, we show how modern extensions of DFT based on non-local interactions can rectify both of these failures. Using the self-consistent non-local HSE06 functional, the formation energies of Cu3Au and CuAu are -71 and -91 meV/atom, respectively, which are in excellent agreement with the experimental measurements. The semi-local GGA predicted CuAu2 is not a stable phase in the HSE06 calculations, and CuAu3 with the L12 structure is theoretically predicted as a stable phase. For Ag-Au, both semi-local GGA and non-local HSE06 functionals give similar formation energies. The electronic structures are used to explain these different phenomena in Cu-Au and Ag-Au.

Zhang, Yongsheng; Kresse, Georg; Wolverton, Christopher

2013-03-01

112

Wetting interaction between Pb-free Sn-Zn series solders and Cu, Ag substrates  

Microsoft Academic Search

This study investigated the wetting behavior of Cu and Ag with pure Sn and several Sn-Zn solders, including Sn-9Zn (abbreviated as Sn-Zn), Sn-8.55Zn-0.5Al (abbreviated as Sn-Al), and Sn-8.55Zn-0.5Ag-0.1Al-0.5Ga (abbreviated as Sn-Zn-Ag-Al-Ga). Results show that Sn-Zn solders exhibit better wettability with both Cu and Ag than pure Sn. The primary interfacial intermetallics in Sn-Zn are (Ag,Cu)Zn rather than (Ag,Cu)Sn. By way

Kwang Lung Lint; Pei Chi Liu; Jenn Ming Song

2004-01-01

113

Effects of Ni cladding layers on suppression of Ag agglomeration in Ag-based Ohmic contacts on p-GaN  

NASA Astrophysics Data System (ADS)

We investigate effects of Ni cladding layers on suppression of Ag agglomeration in Ag contacts on p-GaN using high-resolution x-ray diffraction. In the annealed Ag contact, Ag (100) grains disappear and agglomerate to form a selectively epitaxial growth of Ag (111). An ultrathin Ni contact layer (10 ) below Ag film plays a role to epitaxially grow (111) Ag films on GaN, leading to the suppression of Ag agglomeration. A 20--thick Ni overlayer effectively acts as a passivation layer to prevent the surface diffusion of Ag atoms during annealing, leading to high light reflectance and low contact resistivity.

Son, Jun Ho; Song, Yang Hee; Yu, Hak Ki; Lee, Jong-Lam

2009-08-01

114

Effects of cooling speed on microstructure and tensile properties of SnAgCu alloys  

Microsoft Academic Search

The microstructures and tensile properties of three typical SnAgCu alloys, Sn3.0wt.%Ag0.5wt.%Cu, Sn3.5wt.%Ag0.7wt.%Cu and Sn3.9wt.%Ag0.6wt.%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 Sn3.5Ag0.7Cu and Sn3.9Ag0.6Cu alloys exhibited additional large primary Ag3Sn platelets,

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

2002-01-01

115

Intermetallic compound growth on Ni, Au\\/Ni, and Pd\\/Ni substrates with Sn\\/Pb, Sn\\/Ag, and Sn solders [PWBs  

Microsoft Academic Search

The growth mechanism of the Ni3Sn4 intermetallic compound (IMC) during aging was studied with three different solders (100Sn, Sn-3.5Ag, and Sn-37Pb) on three different substrates (Ni, Ni\\/Au, and Ni\\/Pd), at the temperatures of 75, 100, 125, and 160C from 1 to 36 days. The growth rates of Ni3Sn 4 with Sn on Ni and Ni\\/Au substrates were similar, growing to

Howard D. Blair; Tsung-Yu Pan; John M. Nicholson

1998-01-01

116

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

117

Atomistic simulation of CuNi precipitates hardening in ?-iron  

NASA Astrophysics Data System (ADS)

In this paper, we investigated the interaction of an edge dislocation with Cu precipitates with a spherical geometry and with CuNi precipitates that possess a Cu core with an outer Ni shell, commonly observed in reactor pressure vessel (RPV) steels. We applied molecular dynamics techniques to explore the critical stress required to unpin the dislocation (CSRUD), the breakaway dislocation line shape when the dislocation leaves the precipitates and the transition of Cu atoms within precipitates. The results indicate that the CSRUD of the CuNi precipitates with a diameter less than 2.38?nm is larger than that of Cu precipitates that contain the same number of Cu atoms, while for a diameter larger than 2.38?nm, the CSRUD of CuNi precipitates is weaker, which is related to the bcc to fcc-like or hcp-like atoms transformation in precipitates. The dislocations interact with Cu and CuNi precipitates via the cut mechanism.

Lv, Guocai; Zhang, Hao; He, Xinfu; Yang, Wen; Su, Yanjing

2015-03-01

118

Application of cluster-plus-glue-atom model to barrierless CuNiTi and CuNiTa films  

SciTech Connect

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 CuNiM (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 MNi is more negative than that of MCu.

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

119

Effect of nano-patterning on anisotropy of Cu/Ni/Cu nanolines  

NASA Astrophysics Data System (ADS)

Cu/Ni/Cu films grown epitaxially on Si have shown perpendicular magnetic anisotropy over a wide range of Ni thicknesses. Using interferometric lithography and ion milling, epitaxial and polycrystalline Cu/Ni/Cu films were patterned into large area arrays of parallel lines with widths of 100 and 200 nm. The effect of patterning on the anisotropy of Cu/Ni/Cu with tNi=6.9 and 20.6 nm was determined from M-H loops measured by vibrating sample magnetometry. The nanolines show significantly reduced tendency toward perpendicular magnetization and increased energy favoring magnetization across the linewidth. These results are interpreted in terms of magnetoelastic energy changes due to relaxation of misfit strain upon patterning and shape anisotropy.

Lyons, E. S.; O'Handley, Robert C.; Ross, C. A.

2006-04-01

120

Thermodynamic properties of metastable Ag-Cu alloys  

NASA Astrophysics Data System (ADS)

The enthalpies of formation of metastable fcc Ag-Cu solid solutions, produced by ball milling of elemental powders, were determined by differential scanning calorimetry. Experimental thermodynamic data for these metastable alloys and for the equilibrium phases are compared with both calculation of phase diagrams (CALPHAD) and atomistic simulation predictions. The atomistic simulations were performed using the free-energy minimization method (FEMM). The FEMM determination of the equilibrium Ag-Cu phase diagram and the enthalpy of formation and lattice parameters of the metastable solid solutions are in good agreement with the experimental measurements. CALPHAD calculations made in the same metastable regime, however, significantly overestimate the enthalpy of formation. Thus, the FEMM is a viable alternative approach for the calculation of thermodynamic properties of equilibrium and metastable phases, provided reliable interatomic potentials are available. The FEMM is also capable of determining such properties as the lattice parameter which are not available from CALPHAD calculations.

Najafabadi, R.; Srolovitz, D. J.; Ma, E.; Atzmon, M.

1993-09-01

121

Photoemission from Ag, Cu, and CsI  

SciTech Connect

Photoemission characteristics of three different cathodes, CsI, Ag film and Cu were investigated. CsI, upon irradiation by 213 nm, 10ps laser pulse yields a quantum efficiency of 4% at O.2{mu}J input energy. The saturation mechanism observed at higher input energies require further investigation. Ag film, upon irradiation by 630 nm, 300 fs laser emit prompt photoelectrons after absorbing 2 photons. There was no evidence of optical damage of the film up to 10{sup 11} W/cm{sup 2}. At low intensities, photoemission from Cu is a simple {nu}-e{sup {minus}} interaction, the nonlinearity of the process depending strongly on trace impurities. At higher intensities, there appears to be a change in the emission mechanism.

Srinivasan-Rao, T.; Fischer, J.; Tsang, T.

1992-06-01

122

Plastic behavior of Cu/Ni multilayers  

SciTech Connect

In order to study the plasticity in Cu-Ni multilayers deposited on single crystals of nanoindentation measurements, and by the transmission of well characterized dislocations from the underlying substrate by tensile deformation of Cu single crystals. Various multilayers were deposited by physical vapor deposition with layer thicknesses varying between 1,000 and 20 Angstroms (for a total thickness between 0.8 and 1 {micro}m). Two types of experiments were designed. The first one aimed at injecting, in a controlled way, some dislocations from the substrate into the multilayers; the second type of experiment concerned the structure of the multilayer surface after having plastically pushed the material away from a nanoindenter. This communication reports the results from the nanoindentation measurements, as well as the observations of slip on the surface. The authors observed through the injection of dislocations by nanoindentation that the multilayers increase in strength with refinement of the layer structure but at thicknesses below 35 {angstrom} exhibits a softening behavior. Also observation of the upheaval around the nanoindent showed an evolution from slip lines to more spread plasticity with refinement of the layer structure.

Verdier, M.; Hawley, M.; Nastasi, M.; Kung, H. [Los Alamos National Lab., NM (United States); Niewczas, M. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering; Embury, J.D. [Los Alamos National Lab., NM (United States)]|[McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

1998-12-31

123

Effect of high magnetic field on the morphology of (Cu, Ni) 6Sn 5 at Sn0.3Ni\\/Cu interface  

Microsoft Academic Search

The effect of high magnetic field on the microstructure of (Cu, Ni)6Sn5 intermetallic compound layer in Sn0.3Ni\\/Cu couples at 250C was examined. The applied magnetic field changed the morphology of outer (Cu, Ni)6Sn5 crystals on the Sn side from faceted shape to stick shape. The high magnetic field affected the crystal orientations of (Cu, Ni)6Sn5 and reduced the Ni content

Cong-qian Cheng; Jie Zhao; Yang Xu

2009-01-01

124

A coupled numerical and experimental study on thermo-mechanical fatigue failure in SnAgCu solder joints  

Microsoft Academic Search

In ball grid array (BGA) packages, solder balls are exposed to cyclic thermo-mechanical strains arising from the thermal mismatch between package components. Since fatigue cracks in solder balls are observed generally at the chip side junction, dedicated fatigue experiments are conducted using eutectic SnAgCu- Ni\\/Au specimens in order to mechanically characterize the bonding interface. Sn based solders are prone to

M. Erinc; P. J. G. Schreurs; M. G. D. Geers

2007-01-01

125

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

NASA Astrophysics Data System (ADS)

Ag agglomeration was found to occur at Ni /Ag to p-GaN contacts after annealing at 500C. 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.

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

2007-01-01

126

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

SciTech Connect

Ag agglomeration was found to occur at Ni/Ag to p-GaN contacts after annealing at 500 degree sign 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 10 at. % 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.

Chou, C. H.; Lin, C. L.; Chuang, Y. C.; Bor, H. Y.; Liu, C. Y. [Department of Chemical and Materials Engineering, National Central University, Jhong-Li, 32001, Taiwan (China); Materials and Electro-Optical Research Division, Chung Shan Institute of Science and Technology, Longtan, 32546 (China); Institute of Materials Science and Engineering, National Central University, Jhong-Li, 32001, Taiwan (China)

2007-01-08

127

Correlation between interfacial microstructure and shear behavior of SnAgCu solder ball joined with SnZnBi paste  

Microsoft Academic Search

Sn8Zn3Bi solder paste was applied as a medium to joint Sn3.2Ag0.5Cu solder balls and Cu\\/Ni\\/Au metallized ball grid array\\u000a substrates at 210C. SnAgCu joints without SnZnBi addition were also conducted for comparison. The shear behavior of\\u000a the specimens was investigated after multiple reflow and thermal aging. For each strength test, more than 40 solder balls\\u000a were sheared. The shear strength

Po-Cheng Shih; Kwang-Lung Lin

2007-01-01

128

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

SciTech Connect

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.

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

2010-06-09

129

Cross-interaction effect in the Ni\\/Sn\\/Cu solder joints  

Microsoft Academic Search

The mutual interaction between Sn\\/Ni and Sn\\/Cu interfacial reactions in a Ni\\/Sn\\/Cu sandwich solder joint structure has been discussed in this present work. The major interfacial reaction product on the Sn\\/Cu interface was Cu6Sn5 phase, while on the Sn\\/Ni interface, a ternary (Cu,Ni)6Sn5 compound layer was formed, instead of the typical Ni-Sn compound phase. On the other hand, an asymmetrical

H. W. Tseng; S. J. Wang; C. Y. Liu

2009-01-01

130

A novel multifunctional NiTi/Ag hierarchical composite  

NASA Astrophysics Data System (ADS)

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.

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

131

A novel multifunctional NiTi/Ag hierarchical composite  

PubMed Central

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

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

132

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

133

Preparation of high-permeability NiCuZn ferrite.  

PubMed

Appropriate addition of CuO/V2O5 and the reduction of the granularity of the raw materials particle decrease the sintering temperature of NiZn ferrite from 1200 degrees C to 930 degrees C. Furthermore, the magnetic properties of the NiZn ferrite prepared at low temperature of 930 degrees C is superior to that of the NiZn ferrite prepared by sintering at high temperature of 1200 degrees C because the microstructure of the NiZn ferrite sintered at 930 degrees C is more uniform and compact than that of the NiZn ferrite sintered at 1200 degrees C. The high permeability of 1700 and relative loss coefficient tandelta/mu(i) of 9.0x10(-6) at 100 kHz was achieved in the (Ni0.17Zn0.63Cu0.20)Fe1.915O4 ferrite. PMID:15909348

Hu, Jun; Yan, Mi

2005-06-01

134

Preparation of high-permeability NiCuZn ferrite*  

PubMed Central

Appropriate addition of CuO/V2O5 and the reduction of the granularity of the raw materials particle decrease the sintering temperature of NiZn ferrite from 1200 C to 930 C. Furthermore, the magnetic properties of the NiZn ferrite prepared at low temperature of 930 C is superior to that of the NiZn ferrite prepared by sintering at high temperature of 1200 C because the microstructure of the NiZn ferrite sintered at 930 C is more uniform and compact than that of the NiZn ferrite sintered at 1200 C. The high permeability of 1700 and relative loss coefficient tan?/?i of 9.010?6 at 100 kHz was achieved in the (Ni0.17Zn0.63Cu0.20)Fe1.915O4 ferrite. PMID:15909348

Hu, Jun; Yan, Mi

2005-01-01

135

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

SciTech Connect

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%.

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

2009-06-08

136

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

SciTech Connect

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.

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

137

Cooling rate, pad finish effects on mechanical behavior of SnAgCu alloys  

Microsoft Academic Search

Microstructure of lead free solder joints possesses a complex morphology owing to nonequilibrium solidification [16]. We reported the creep and monotonic behavior of Sn-Pb, Sn3.8Ag0.7Cu, Sn3.0Ag0.5Cu, and Sn1.0Ag0.5Cu alloys in our earlier research [2, 3, 10, 12, 18]. The behavioral impact of the microstructrual changes due to pad finish and cooling rate on micron-scale SnAgCu joints were studied to a

S. Chavali; Y. Singh; G. Subbarayan; A. Bansal; M. Ahmad

2011-01-01

138

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

PubMed Central

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

2012-01-01

139

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

PubMed

: 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

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

2012-01-01

140

Modified Ni-Cu catalysts for ethanol steam reforming  

SciTech Connect

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 150-350C, 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 350C 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 150C amorphous carbon was evidenced, while at 350C crystalline, filamentous carbon is formed.

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

141

Diffusion bonding of commercially pure Ni using Cu interlayer  

SciTech Connect

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.

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

2012-07-15

142

Modified Ni-Cu catalysts for ethanol steam reforming  

NASA Astrophysics Data System (ADS)

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 150-350C, 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 350C 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 150C amorphous carbon was evidenced, while at 350C crystalline, filamentous carbon is formed.

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

2013-11-01

143

HPLC characterization of Ag+ and Cu+ metal exchange reactions with Zn- and Cd-metallothioneins.  

PubMed

Anion exchange HPLC methods were developed to study the metal exchange reactions of ZnMT and CdMT with Ag+ and Cu+. The kinetics of these reactions revealed the existence of a slow interprotein metal redistribution process that follows initial rapid displacement of metal from Zn7MT or Cd7MT by Ag+ or Cu+. Kinetically-favored products of the reaction of Ag+ with Zn7MT in the presence of Chelex resin include Zn4Ag6MT and Ag12MT. Subsequent slow reaction between Zn7MT and Ag12MT leads to the thermodynamically-favored product, Zn4Ag6MT. Analogous behavior was observed for Cd7MT titrated with Ag+ and Zn7MT with Cu+. The use of Chelex resin to remove unbound metal ions was found to influence the reactions of Zn7MT and Cd7MT with Ag+. Upon addition of Ag+ to Zn7MT in the absence of Chelex, a Ag18MT species forms as the kinetically-favored product in addition to Zn4Ag6MT and Ag12MT. Subsequently, Ag18MT was found to donate Ag+ to Zn7MT and Zn4Ag6MT via slow interprotein metal exchange reactions. Chelex resin influences the titration reaction either by limiting formation of Ag18MT and/or by binding the positively charged Ag18MT species and removing it from solution. The formation of Ag18MT in the absence of Chelex explains why more than 12 equiv of Ag+ is required to displace all of the Zn2+ or Cd2+ from Zn7MT and Cd7MT. The HPLC methods developed in this study allow homogeneous preparations to be made of metal-hybrid MT species containing Ag+ in the beta-domain and Cd2+ or Zn2+ in the alpha-domain. PMID:8909291

Li, H; Otvos, J D

1996-11-01

144

Kinetic analysis of the interfacial reactions in Ni\\/Sn\\/Cu sandwich structures  

Microsoft Academic Search

The mutual interaction between Sn\\/Ni and Sn\\/Cu interfacial reactions in a Ni\\/Sn\\/Cu sandwich sample has been studied. The major\\u000a interfacial reaction product on the Cu side was Cu6Sn5, while on the Ni side, a ternary (Cu,Ni)6Sn5 compound layer was formed. We found that the growth kinetics of the interfacial compound layers on both sides reached a steady\\u000a state in the

S. J. Wang; C. Y. Liu

2006-01-01

145

Kinetic analysis of the interfacial reactions in Ni\\/Sn\\/Cu sandwich structures  

Microsoft Academic Search

The mutual interaction between Sn\\/Ni and Sn\\/Cu interfacial reactions in a Ni\\/Sn\\/Cu sandwich sample has been studied. The major interfacial reaction product on the Cu side was Cu6Sn5, while on the Ni side, a ternary (Cu,Ni)6Sn5 compound layer was formed. We found that the growth kinetics of the interfacial compound layers on both sides reached a steady state in the

S. J. Wang; C. Y. Liu

2006-01-01

146

Sn-Ag-Cu and Sn-Cu solders: Interfacial reactions with platinum  

NASA Astrophysics Data System (ADS)

The interfacial reaction and intermetallic formation at the interface between tin solders containing a small amount of copper with platinum were investigated in this study. Sn-0.7Cu and Sn-1.7Cu solders were reacted with platinum by dipping Pt/Ti/Si specimens into the molten solder at 260C. Sn-3.8Ag-0.7Cu solder was reacted with platinum by reflowing solder paste on a Pt/Ti/Si substrate at 250C. PtSn4 intermetallic formed in all specimens while Cu6Sn5 interfacial intermetallic was not observed at the solder/platinum interfaces in any specimens. A parabolic relationship existed between the thickness of the Pt-Sn intermetallic and reaction time, which indicates the intermetallic formation in the solder/platinum interface is diffusion controlled.

Kim, Tae Hyun; Kim, Young-Ho

2004-06-01

147

Vacancy Generation and Adsorption of Cu Atom at Ag(1 1 1) Surface during Diffusion of Cu-TRIMER  

NASA Astrophysics Data System (ADS)

In this paper, the vacancy generation at (1 1 1) surface of silver (Ag) and the adsorption of copper (Cu) atom in the vacant site at Ag(1 1 1) surface has been studied using molecular dynamics (MD) simulation technique. The run of micro-canonical constant energy (NVE) ensemble results the generation of vacancy at 700 K in the presence of Cu-trimer, and its migration is observed toward the island as a result of self-diffusion of the surface layer atom. The energy of vacancy generation at Ag surface is found to be Ev = 1.078 eV, in the presence of Cu-trimer. The popped-up Ag adatom combines with Cu-trimer, making a mixed-tetramer (Cu3-Ag island). The adsorption energy of the Cu-atom among the mixed-tetramer island into the substitutional site is Es = -0.813 eV, leaving a mixed-trimer (Cu2-Ag island) at Ag(1 1 1). Moreover, the presence of the island creates some anharmonic effects like dislocations and fissures at the surface. These dislocations and fissures show a trend of attraction to each other and also migrate toward the island, during the time evolution of the system.

Shah, Zulfiqar Ali; Hayat, Sardar Sikandar; Rehman, Z.; Rahman, Sardar Siddique; Bouafia, Farida

2014-07-01

148

Study on synthesis of ultrafine Cu-Ag core-shell powders with high electrical conductivity  

NASA Astrophysics Data System (ADS)

Cu-Ag composite powders with high electrical conductivity were synthesized by electroless plating of silver sulfate, copper powders with eco-friendly sodium citrate as reducing agent, dispersant and chelating agent in an aqueous system. The influences of sodium citrate/Ag ratio on Ag coatings of Cu powders were investigated. Ag was formed a dense coating on the surface of Cu powders at a molar ratio of sodium citrate/Ag = 0.07/1. SEM showed an uniformity of Ag coatings on Cu powders. SEM-EDX also revealed that Cu cores were covered by Ag shells on the whole. The surface composition analysis by XPS indicated that without Cu or Ag atoms in the surface were oxidized. The resistivity measurements of Cu-Ag paste shows that they have closer resistivity as the pure silver paste's after 250 C for 30 min heat-treatment (2.55 10-4 ? cm) and 350 C for 30 min heat-treatment (1.425 10-4 ? cm).

Peng, Yu-hsien; Yang, Chih-hao; Chen, Kuan-ting; Popuri, Srinivasa R.; Lee, Ching-Hwa; Tang, Bo-Shin

2012-12-01

149

Order parameter by instantaneous normal mode analysis for melting behaviour of cluster Ag17Cu2  

E-print Network

Order parameter by instantaneous normal mode analysis for melting behaviour of cluster Ag17Cu2 Pin of the cluster. We also use the instantaneous normal mode (INM) analysis to dissect dynamics of the cluster-type molecular dynamics simulations with the Gupta potential for bimetallic cluster Ag17Cu2 from T=0 to 1500K

150

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

NASA Astrophysics Data System (ADS)

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.

Hong, Seongik; Kim, Namsoo

2015-03-01

151

Enhanced low temperature thermoelectric performance of Ag-doped BiCuSeO  

NASA Astrophysics Data System (ADS)

We investigated the physical properties of the silver doped layered oxyselenides BiCu1-xAgxSeO (x = 0-0.4), which crystallize in an unusual intergrowth structure with [Cu2Se2]2- and [Bi2O2]2+ layers. The total thermal conductivity is decreased because the heavier Ag doping in BiCuSeO lattice decreased the lattice thermal conductivity. The undoped BiCuSeO exhibits a semiconducting behavior, and the Ag-doped BiCuSeO performs much improved electrical conductivity. Although Ag-doping causes a decreasing Seebeck coefficient, the significant increase of the electrical conductivity compensates the moderate decrease of the Seebeck coefficient, which leads to the strongly improved power factor values. Finally, the figure of merit is improved and reaches a maximum 0.07 at 300 K for the sample BiCu0.7Ag0.3SeO.

Tan, S. G.; Lei, Hechang; Shao, D. F.; Lv, H. Y.; Lu, W. J.; Huang, Y. N.; Liu, Y.; Yuan, B.; Zu, L.; Kan, X. C.; Song, W. H.; Sun, Y. P.

2014-08-01

152

Oxygen reduction reaction on Cu-doped Ag cluster for fuel-cell cathode.  

PubMed

The development of fuel cells as clean-energy technologies is largely limited by the prohibitive cost of the noble-metal catalysts needed for catalyzing the oxygen reduction reaction (ORR) in fuel cells. A fundamental understanding of catalyst design principle that links material structures to the catalytic activity can accelerate the search for highly active and abundant bimetallic catalysts to replace platinum. Here, we present a first-principles study of ORR on Ag12Cu cluster in alkaline environment. The adsorptions of O2, OOH, and OH on Cu-doped Ag13 are stronger than on Ag13. The d-band centers of adsorption sites show the Cu-doping makes d-electrons transferred to higher energy state, and improves O2 dissociation. ORR processes on Ag12Cu and Ag13 indicate Cu-doping can strongly promote ORR, and ORR process can be better preformed on Ag12Cu than on Ag13. For four-electron transfer, the effective reversible potential is 0.401 V/RHE on Ag12Cu in alkaline medium. PMID:25227449

Ma, Wenqiang; Chen, Fuyi; Zhang, Nan; Wu, Xiaoqiang

2014-10-01

153

Magnetic Properties of Cd Substituted Ni-Cu Ferrites  

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

154

Magnetoresistance in Co-Ni-Cu glass coated microwires  

NASA Astrophysics Data System (ADS)

Considerable magneto-resistance (MR) is found in Co29Ni25Mn1Cu45 microwires. Magnetization curves, magnetic field dependence of MR and coercivity, Hc, in as-prepared and annealed Co29Ni25Mn1Cu45 microwires are quite different. Roughly monotonic decay of MR with magnetic field above 1000Oe is observed in as-prepared microwires. Annealed sample exhibits a maximum and considerable hysteresis on magnetic field dependence of MR. The position of this maximum correlates well with the values of coercivity, Hc, obtained from magnetization curves.

Zhukov, A.; Luna, C.; Martinez, J. L.; Zhukova, V.; Vzquez, M.

2004-05-01

155

Spin trimers in Ca3Cu2Ni(PO4)4  

NASA Astrophysics Data System (ADS)

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.

Ghosh, M.; Ghoshray, K.

2012-07-01

156

Effects of Electromigration on Interfacial Reactions in the Ni/Sn-Zn/Cu Solder Interconnect  

NASA Astrophysics Data System (ADS)

Electromigration in the Ni/Sn-Zn/Cu solder interconnect was studied with an average current density of 3.51 104 A/cm2 for 168.5 h at 150C. When the electrons flowed from the Ni side to the Cu side, uniform layers of Ni5Zn21 and Cu5Zn8 were formed at the Ni/Sn-Zn and Cu/Sn-Zn interfaces. However, upon reversing the current direction, where electron flow was from the Cu side to the Ni side, a thicker Cu6Sn5 phase replaced the Ni5Zn21 phase at the Ni/Sn-Zn interface, whereas at the Cu/Sn-Zn interface, a thicker ?-CuZn phase replaced the Cu5Zn8 phase.

Zhang, X. F.; Guo, J. D.; Shang, J. K.

2009-03-01

157

The connective tissue response to Ti, NiCr and AgPd alloys.  

PubMed

The aim of the study was to compare the connective tissue response of Lewis rats to Ti, NiCr and AgPd alloys. It was found that implants were covered by collagen-rich, well vascularized capsules. Titanium was covered by the thinnest capsule (57 20 ?m) and AgPd alloy was covered by the thickest capsule (239 50 ?m). The PCNA+ cell prevalence in the capsules was lower for titanium than for AgPd and NiCr. Mast cells formed a gradient to a depth of 1200 ?m only for titanium implants. Cells with brown to black silver granules in the cytoplasm were observed close to AgPd implants. The results suggest that titanium implants induce a weaker connective tissue response than implants made from NiCr and AgPd alloys. PMID:21071336

?ukomska-Syma?ska, Monika; Brzezi?ski, Piotr M; Zieli?ski, Andrzej; Soko?owski, Jerzy

2010-09-30

158

Effects of Electromigration on Interfacial Reactions in the Ni\\/Sn-Zn\\/Cu Solder Interconnect  

Microsoft Academic Search

Electromigration in the Ni\\/Sn-Zn\\/Cu solder interconnect was studied with an average current density of 3.51 104 A\\/cm2 for 168.5 h at 150C. When the electrons flowed from the Ni side to the Cu side, uniform layers of Ni5Zn21 and Cu5Zn8 were formed at the Ni\\/Sn-Zn and Cu\\/Sn-Zn interfaces. However, upon reversing the current direction, where electron flow was from

X. F. Zhang; J. D. Guo; J. K. Shang

2009-01-01

159

Electron microscopy of Ag-(Ni-O) core-shell nanowires.  

PubMed

This report provides information about an electrodeposition-based two-step synthesis methodology for producing core-shell Ag-(Ni-O) nanowires and their detailed structural and compositional characterization using electron microscopy technique. Nanowires were produced by employing anodic alumina templates with a pore diameter of 200 nm. In the first step of the synthesis process, nanocrystalline Ni-O was electrodeposited in a controlled manner such that it heterogeneously nucleated and grew only on the template pore walls without filling the pores from bottom upwards. This alumina template with pore walls coated with Ni-O was then utilized as a template during the electrodeposition of Ag in the second step. Electrodeposited Ag filled the template pores to finally produce Ag-(Ni-O) core-shell nanowires with an overall diameter of 200 nm. PMID:24957127

Singh, M Pratap; M Y, Rekha; Raghupathy, Y; Srivastava, C

2014-09-01

160

HRTEM studies of amorphous ZrNiTiCu nanocrystalline composites.  

PubMed

Ball milling of easy glass forming Ti(25)Zr(17)Ni(29)Cu(29) alloys lead to the formation of an amorphous structure accompanied by a substantial increase of powder microhardness. The powders show clear glass transition effect and a few stage crystallization starting above 500 degrees C. High-resolution transmission electron microscope technique allowed identifying nanocrystalline inclusions as Cu(12)NiTi(7) within the amorphous powder. The amorphous powders mixed with nanocrystalline iron or silver powders were hot pressed to form composites. A narrow 200 nm broad intermediate single-phase layer at the amorphous-phase/iron interface containing all elements present in the composite was identified using transmission electron microscope and high-angle annular dark field detector techniques. scanning transmission electron microscopy energy dispersive spectroscopy line profile showed gradual change of composition within the intermediate zone. Amorphous phase contains small nanocrystals of size close to 10 nm identified using High-resolution transmission electron microscope as Cu(12)NiTi(7.) Compression tests have shown better plasticity of composites than in the case of pure hot-pressed amorphous powder; furthermore, high elastic limit of composites and the ultimate compression stress of about 1800 MPa for composites containing 20% Fe and near 700 MPa for those with 20% Ag. PMID:20500372

Dutkiewicz, J; Lity?ska-Dobrzy?ska, L; Kovacova, A; Molnarova, M; Rogal, L; Maziarz, W

2010-03-01

161

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

PubMed

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

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

2014-08-25

162

Joint strength and interfacial microstructure between SnAgCu and SnZnBi solders and Cu substrate  

Microsoft Academic Search

In the present research, in order to fundamentally investigate the strength and interfacial microstructure of the joints between Sn3.5Ag0.7Cu (SAC) and Sn8Zn3Bi (SZB) solders and Cu, examinations using the standardized solder joint specimen for measuring the shear strength were performed. The effects of the addition of Ag, Bi and Pb to the solders, which are the ingredients of possible lead

Akio Hirose; Hiroto Yanagawa; Eiichi Ide; Kojiro F Kobayashi

2004-01-01

163

Structural and magnetic properties of nano-crystalline Ag + doped NiFe 2O 4  

NASA Astrophysics Data System (ADS)

Ni ferrite nanoparticles were prepared using citrate method. XRD pattern revealed the formation of the samples as synthesized in the spinel cubic structure. Silver doping effect on the magnetic properties of Ni ferrite was investigated. The lattice parameter was slightly increased while the values of the Curie temperature decreased with increasing Ag content. The magnetic susceptibility was measured using Faraday's method and the calculated magnetic constants were reported. The data showed that ?M and effective magnetic moment decrease with increasing Ag content.

Ahmed, M. A.; El-Dek, S. I.; El-Kashef, I. M.; Helmy, N.

2011-05-01

164

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

165

Mantle-derived magmas and magmatic Ni-Cu-(PGE) deposits N.T. Arndt1  

E-print Network

Mantle-derived magmas and magmatic Ni-Cu-(PGE) deposits N.T. Arndt1 , C.M. Lesher2 and G 94303, USA, czamrandg@earthlink.net Abstract Magmatic Fe-Ni-Cu platinum-group element (PGE) sulfide are most capable of forming Ni-Cu- (PGE) deposits, whereas lower-temperature, volatile-rich alkali picrites

Paris-Sud XI, Universit de

166

Microstructure and Strengthening Mechanisms of Highly Textured Cu/Ni Multilayers  

E-print Network

strengthening mechanisms and nanotwins in the Cu/Ni multilayers. Sputtered, highly textured (111) and (100) Cu/Ni multilayers with individual layer thickness, h, vary from 1 to 200 nm. At greater h, X-ray diffraction (XRD) patterns of Cu and Ni (100 or 111...

Liu, Yue

2011-10-21

167

Industrial Cu-Ni alloys for HTS coated conductor tape. A Girard1,2,3  

E-print Network

preparation The two non-magnetic copper-nickel alloys studied, with composition Cu55Ni45 and Cu70Ni30 from. Copper rich Cu-Ni alloys have been textured with the RABiTS method in order to get non-magnetic and cost, depending on the nickel content of the alloy. Finally both samples, rolled and annealed under

Boyer, Edmond

168

Kinetics of Facile Bilayer Island Formation for Ag on NiAl(110)  

NASA Astrophysics Data System (ADS)

STM studies reveal that deposition of Ag on NiAl(110) at 127 K and above leads to bilayer-by-bilayer growth of a nearly-strain-free film with Ag(110) structure [1]. This growth mode is attributed to Quantum Size Effects (QSE) associated with electron confinement in the Ag film. Our focus here is on analysis the initial nucleation and growth of bilayer Ag(110) islands on NiAl(110) which is facile even at 127K despite requiring uphill transport of Ag. DFT analysis for supported Ag films determines adatom adsorption energies (which display QSE), interaction energies, and various relevant diffusion barriers. Kinetic Monte Carlo simulation of an atomistic lattice-gas model incorporating these energies highlights the role of strongly anisotropic interactions in facilitating bilayer island formation. [1] B. Unal et al., Phys. Rev. B 76 (2007) 195410.

Evans, J. W.; Han, Yong; Liu, D.-J.; Unal, Baris; Qin, F.; Jin, D.; Jenks, C. J.; Thiel, P. A.

2008-03-01

169

Sol-gel auto-combustion synthesis of totally immiscible NiAg alloy  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Chemically synthesized immiscible NiAg alloy nanoparticles without protecting matrix. Black-Right-Pointing-Pointer A chemical method providing both a nonequilibrium thermal process and a good mixing of precursors. Black-Right-Pointing-Pointer Observation of extinction planes in NiAg alloy. -- Abstract: Immiscible crystalline NiAg alloy was successfully synthesized by the newly developed sol-gel auto-combustion method. The structure and composition were examined by X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). All evidence supports that homogeneous NiAg alloy with FCC structure was synthesized. The differential thermal analysis and thermogravimetry (DTA-TG) measurement shows that the alloy has a good thermal stability until 315 Degree-Sign C. Unusually some extinction planes are observed in the XRD pattern and HRTEM images. The random distribution of atoms and the large difference between Ni and Ag atom form factors should be regarded as the main reasons for the observation of the extinction planes. The quenching like nonequilibrium thermal process in the combustion is taken as the key factor in the synthesis of immiscible alloy. And the addition of ethylene glycol in the precursors is found to benefit the formation of NiAg alloy.

Jiang, Yuwen [National Laboratory of Microstructure and Department of Physics, Nanjing University, Nanjing 210093 (China)] [National Laboratory of Microstructure and Department of Physics, Nanjing University, Nanjing 210093 (China); Yang, Shaoguang, E-mail: sgyang@nju.edu.cn [National Laboratory of Microstructure and Department of Physics, Nanjing University, Nanjing 210093 (China)] [National Laboratory of Microstructure and Department of Physics, Nanjing University, Nanjing 210093 (China); Hua, Zhenghe; Gong, Jiangfeng; Zhao, Xiaoning [National Laboratory of Microstructure and Department of Physics, Nanjing University, Nanjing 210093 (China)] [National Laboratory of Microstructure and Department of Physics, Nanjing University, Nanjing 210093 (China)

2011-12-15

170

Cu-Ni nanoparticle-decorated graphene based photodetector  

NASA Astrophysics Data System (ADS)

We report a simple and straight forward approach for the synthesis of Cu-Ni graphene hybrid nano-composites. These nano-composites have been characterized using AFM, XRD, FTIR spectroscopy and HRTEM. The characterization data clearly shows uniform decoration of Cu-Ni nanoparticles on graphene layers. A thin film of these nano-composites was found to exhibit unique electrical and photoresponse properties, which may be attributed to photothermoelectric and photovoltaic effects. The photocurrent measurements indicate superior light absorption and long lifetime of this device.We report a simple and straight forward approach for the synthesis of Cu-Ni graphene hybrid nano-composites. These nano-composites have been characterized using AFM, XRD, FTIR spectroscopy and HRTEM. The characterization data clearly shows uniform decoration of Cu-Ni nanoparticles on graphene layers. A thin film of these nano-composites was found to exhibit unique electrical and photoresponse properties, which may be attributed to photothermoelectric and photovoltaic effects. The photocurrent measurements indicate superior light absorption and long lifetime of this device. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00916a

Kumar, Anil; Husale, Sudhir; Srivastava, A. K.; Dutta, P. K.; Dhar, Ajay

2014-06-01

171

High-performance NiO/Ag/NiO transparent electrodes for flexible organic photovoltaic cells.  

PubMed

Transparent electrodes with a dielectric-metal-dielectric (DMD) structure can be implemented in a simple manufacturing process and have good optical and electrical properties. In this study, nickel oxide (NiO) is introduced into the DMD structure as a more appropriate dielectric material that has a high conduction band for electron blocking and a low valence band for efficient hole transport. The indium-free NiO/Ag/NiO (NAN) transparent electrode exhibits an adjustable high transmittance of ?82% combined with a low sheet resistance of ?7.6 ?sq(-1) and a work function of 5.3 eV after UVO treatment. The NAN electrode shows excellent surface morphology and good thermal, humidity, and environmental stabilities. Only a small change in sheet resistance can be found after NAN electrode is preserved in air for 1 year. The power conversion efficiencies of organic photovoltaic cells with NAN electrodes deposited on glass and polyethylene terephthalate (PET) substrates are 6.07 and 5.55%, respectively, which are competitive with those of indium tin oxide (ITO)-based devices. Good photoelectric properties, the low-cost material, and the room-temperature deposition process imply that NAN electrode is a striking candidate for low-cost and flexible transparent electrode for efficient flexible optoelectronic devices. PMID:25148532

Xue, Zhichao; Liu, Xingyuan; Zhang, Nan; Chen, Hong; Zheng, Xuanming; Wang, Haiyu; Guo, Xiaoyang

2014-09-24

172

Growth and characterization of graphene on CuNi substrates  

NASA Astrophysics Data System (ADS)

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.

Tyagi, Parul

173

Paleomagnetism of the Mt Isa Zn-Pb-Cu-Ag and George Fisher Zn-Pb-Ag deposits, Australia  

Microsoft Academic Search

Paleomagnetic results are reported for the Mt Isa ZnPbCuAg and George Fisher ZnPbAg black-shale-hosted deposits in northwestern Queensland, Australia. Both deposits are hosted in greenschist facies carbonaceous and dolomitic siltstones, mudstones and shales of the ca 1655 Ma Urquhart Shale Formation of the Mt Isa Group. Lead model ages for both deposits are ca 1655 Ma, and an ArAr biotite

K. Kawasaki; D. T. A. Symons

2011-01-01

174

Ni doping on Cu surfaces: Reduced copper resistivity  

NASA Astrophysics Data System (ADS)

The resistivity of 9.3-nm-thick epitaxial and polycrystalline Cu is reduced by 11%-13% when coated with 0.75 nm Ni. Sequential in situ and ex situ transport measurements show that this is due to electron surface scattering which exhibits a specularity p = 0.7 for the Cu-vacuum interface that transitions to completely diffuse (p = 0) when exposed to air. In contrast, Ni-coated surfaces exhibit partial specularity with p = 0.3 in vacuum and p = 0.15 in air, as Cu2O formation is suppressed, leading to a smaller surface potential perturbation and a lower density of localized surface states, yielding less diffuse electron scattering.

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

2014-09-01

175

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

Microsoft Academic Search

The solid-state, cross-interaction between the Ni layer on the component side and the Cu pad on the printed circuit board (PCB) side in ball grid array (BGA) solder joints was investigated by employing Ni(15 mum)\\/Sn(65 mum)\\/Cu ternary diffusion couples. The ternary diffusion couples were prepared by sequentially electroplating Sn and Ni on a Cu foil and were aged isothermally at

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

2008-01-01

176

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

Microsoft Academic Search

The solid-state, cross-interaction between the Ni layer on the component side and the Cu pad on the printed circuit board\\u000a (PCB) side in ball grid array (BGA) solder joints was investigated by employing Ni(15?m)\\/Sn(65?m)\\/Cu ternary diffusion couples. The ternary diffusion couples were prepared by sequentially electroplating Sn and Ni on a\\u000a Cu foil and were aged isothermally at 150, 180,

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

2008-01-01

177

Adsorption of Cu, Ag, and other metals on Fe-oxides as a control on elemental composition of stratiform and red bed copper deposits  

SciTech Connect

In low-temperature red bed and stratiform Cu deposits like Zambia-Zaire, Kupferschiefer, and Redstone, Cu is accompanied by various combinations of Ag, Co, Pb and Zn, and appears to be emplaced during diagenesis. Red bed sediments near deposits in Pennsylvania and beneath the Redstone deposit are strongly depleted in Cu but show little change in Pb, Zn, Ni and Co. Formation of cuprous chloride complexes under slightly reducing conditions allow solubility of Cu, but these solutions also transport Pb, Zn, Ni and Co. The effect of adsorption by Fe-oxides in the red beds as a control on metal ratios has been tested by experiments on 0.5 ppm Cu, Ag, Pb, Zn, Ni and Co with 0.8 g/1 goethite at 25/sup 0/C in 1 M NaCl. Under oxidized conditions (air),the pH values above which more than 50% of the metals are adsorbed are: Cu 5.0, Pb 5.5, Zn 6.5, Co 7.5, Ni 7.8, and Ag > 9. For more reduced conditions near the Fe/sup 2 +/-goethite boundary, the 50% adsorption values for Pb, Zn, Co, Ni and Ag are decreased by 0.5 to 1 pH unit, perhaps because of competition with Fe/sup 2 +/, but Cu (as CuCl/sub 2//sup -/ and CuCl/sub 3//sup 2 -/) shows adsorption of only about 20% at pH 5, 25% at pH 6, 35% at pH 7, and 100% at pH 8. At 50/sup 0/C, adsorption at pH 5 and 6 is about 10% and 20%, respectively, for Cu. By changes in Eh, pH, temperature, and molality of Cl and other species such as SO/sub 4/, CO/sub 3/, Ca, and Mg, it appears that various combinations of metals can be mobilized or left immobile. The time of mobilization and nature of Fe-oxide may also be critical.

Rose, A.W.; Bianchi, G.C.

1985-01-01

178

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

SciTech Connect

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.

Zhou Guangwen [Department of Mechanical Engineering and Multidisciplinary Program in Materials Science and Engineering, State University of New York, Binghamton, New York 13902 (United States); Fong, Dillon D.; Fuoss, Paul H.; Baldo, Peter M.; Thompson, Loren J.; Eastman, Jeffrey A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Wang Liang [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

2009-10-01

179

Nanogranular Fe-Cu-Ag thin films: structure, microstructure and giant magnetoresistance.  

PubMed

Fe(x)Cu(y)Ag(z) granular thin films with several compositions were prepared by dc magnetron sputtering. These films consist of small Fe magnetic particles embedded in a nonmagnetic CuAg matrix. Structure, microstructure, morphology and magnetotransport properties were studied. The compositions of these samples were determined by energy-dispersive X-ray analysis. X-ray diffraction results showed strong Ag(111) peaks and broad Cu(111) peaks in all the samples. The variation of the (111) lattice spacings indicates a partial intermixing of Fe, Cu and Ag atoms. Microstructural studies using transmission electron microscopy (TEM) on a selected sample showed only Ag reflections and no reflection from Cu and Fe. Both XRD and TEM studies did not reveal any diffraction peak due to Fe and Cu for this sample. The fitting of the experimental grain size data obtained from TEM micrograph to the lognormal distribution function has allowed an estimation of the average grain diameter of 3.7 nm. The surface image of the Fe22Ag78 film observed using a scanning electron microscope showed the presence of droplet like Ag particles on the film surface. The Cu substitution results in smooth films without any Ag particles on the surface. Surface morphology by atomic force microscopy shows that the Fe39Cu13Ag48 film has a surface roughness of 0.75 nm. Finally, we have obtained a maximum giant magnetoresistance ratio of 3.2% in these films measured at 300 K for an in-plane magnetic field of 20 kOe. PMID:18681032

Rout, S; Kumar, M Senthil; Bhattacharya, S; Aswal, D K; Gupta, S K

2008-06-01

180

Thermal analysis of metastable Fe-Cu-Ag prepared by mechanical alloying  

NASA Astrophysics Data System (ADS)

The thermal properties of metastable Fe-Cu-Ag alloys have been investigated using differential scanning calorimetry, complementing an earlier x-ray diffraction and Mssbauer spectroscopy study. Samples were mechanically alloyed under nitrogen in a high-energy ball mill for 70 hours. DSC and x-ray data on milled and unmilled elemental powders show that Fe sustains more lattice distortion than Cu or Ag, with an rms strain of order 0.6%. In the equimolar binary alloys Fe-Cu, Fe-Ag and Cu-Ag the presence of DSC exotherms below 0953-8984/10/7/014/img6 is found to correspond to a gradual decomposition of the alloy, while exotherms above 0953-8984/10/7/014/img6 denote recrystallization and grain growth. The absence of low-temperature DSC exotherms in Fe-Ag confirms phase segregation in this granular alloy. In equimolar Fe-Cu-Ag, DSC curves after successive heat treatments indicate a highly disordered state, with fine-scale residual crystallinity. Heating promotes the decomposition of this metastable state into polycrystalline and segregated Fe, Cu and Ag.

Pankhurst, Q. A.; Cohen, N. S.; Odlyha, M.

1998-02-01

181

Formation of high reflective Ni/Ag/Ti/Au contact on p-GaN  

NASA Astrophysics Data System (ADS)

A metallization scheme of Ni/Ag/Ti/Au has been developed for obtaining high reflective contacts on p-type GaN. In order to find optimal conditions to get a high reflectivity, we studied samples with various Ni thicknesses, annealing temperatures and annealing times. By annealing at 500 C for 5 min in an O 2 ambient, a reflectivity as high as 94% was obtained from Ni/Ag/Ti/Au (1/120/120/50 nm). The effects of Ti layers on the suppression of Ag agglomeration were investigated by using Auger electron spectroscopy (AES). From AES depth profiles, it is clear that Ti acts as a diffusion barrier to prevent Au atoms from diffusing into the Ag layer, which is important in the formation of high reflectivity.

Jiang, Fang; Cai, Li-E.; Zhang, Jiang-Yong; Zhang, Bao-Ping

2010-07-01

182

Cross-Interaction in Cu/Sn/Co/Sn/Ni and Cu/Sn-Co/Co/Sn- Co/Ni Couples  

NASA Astrophysics Data System (ADS)

In this study we examined cross-interactions of Cu/Co and Co/Ni by use of Cu/Sn/Co/Sn/Ni and Cu/Sn-0.04 wt.% Co/Co/Sn-0.04 wt.% Co/Ni couples. In the Cu/Sn/Co couple, Cu can diffuse through the pure Sn solder, and the (Cu, Co)6Sn5 phase is formed at the Co side. The rate of consumption of Co decreases in the presence of Cu. Adding 0.04 wt.% Co to the pure Sn solder blocks diffusion of Cu; the (Cu, Co)6Sn5 phase at the Co side is not observed, and the rate of Co consumption is increased. In the Co/Sn/Ni couple, no noticeable Co and Ni diffusion is observed. When 0.04 wt.% Co is added, the ternary (Ni, Co)Sn4 phase is formed at the Ni side. These results indicate Co is an effective barrier to diffusion of Cu which can be used in flip chip packaging of Cu/low- k chips.

Chen, Chih-chi; Tseng, Yan-lun

2015-03-01

183

Ni/Ag as low resistive ohmic contact to p-type AlGaN for UV LEDs  

NASA Astrophysics Data System (ADS)

Reflective (thick) and semi-transparent (thin) Ni/Ag/Ni contacts were prepared on GaInN-based light-emitting diodes (LEDs) and p-GaN/p-Al0.15Ga0.85N layer sequences. A light output power enhancement of 41% and forward voltage reduction of 0.59 V were obtained compared to a Ni/Au contact for LEDs emitting at 400 nm with thick p-GaN contact layers. The specific contact resistance of the Ni/Ag/Ni contacts on p-GaN/p-Al0.15Ga0.85N with varying p-GaN thickness (5-20 nm) were determined by transmission line method and compared to Ni/Au contacts. Low resistive ohmic contacts were obtained for a p-GaN thickness of less than 10 nm. The p-GaN layer can be completely omitted for the reflective Ni/Ag/Ni contact. In addition, reflection and transmission of the Ni/Ag/Ni metallization schemes were investigated in the ultra-violet spectral range. Thick Ni/Ag/Ni and thin Ni/Ag/Ni covered by Al are promising to serve as reflective contacts for ultra-violet LEDs. The former for wavelength around 350 nm and the latter for wavelengths below 350 nm.

Passow, T.; Gutt, R.; Maier, M.; Pletschen, W.; Kunzer, M.; Schmidt, R.; Wiegert, J.; Luick, D.; Liu, S.; Khler, K.; Wagner, J.

2010-02-01

184

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

SciTech Connect

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

Stiller, K.; Haettestrand, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics] [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics; Danoix, F. [Univ. de Rouen, Mont Saint Aignan (France). Lab. de Microscopie Ionique] [Univ. de Rouen, Mont Saint Aignan (France). Lab. de Microscopie Ionique

1998-11-02

185

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

SciTech Connect

(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.

Boyle, Jonathan; Hanket, Gregory; Shafarman, William

2009-06-09

186

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

NASA Astrophysics Data System (ADS)

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.

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

2009-01-01

187

Structure and giant magnetoresistance of granular Ag-Co and AgNi alloys grown epitaxially on MgO(100)  

Microsoft Academic Search

We describe the structural and magnetoresistive properties of Ag-Co and Ag-Ni granular alloys that were grown epitaxially on MgO(100) substrates. With substrate temperatures in the range 300-400 C and up to 25 vol% of the ferromagnetic constituent (Co or Ni) x-ray analyses showed that the Ag matrices were elastically strained (by stretching at the interface with the substrate), but had

D. J. Kubinski; H. Holloway

1995-01-01

188

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

SciTech Connect

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.

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

2009-03-08

189

A highly sensitive non-enzymatic glucose sensor based on bimetallic Cu-Ag superstructures.  

PubMed

Bimetallic Cu-Ag superstructures were successfully fabricated for the first time by using the natural leaves as reducing agent through a facile one-step hydrothermal process. Morphology, structure and composition of the Cu-Ag superstructures were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES), respectively. The results reveal that the Cu-Ag superstructure is bimetallic nanocomposite constructed by nanoparticles with low Ag content and shows a rough surface and porous flexural algae-like microstructure. By using a three-dimensional nickel foam as the scaffold, a novel non-enzymatic glucose sensor based on Cu-Ag nanocomposites has been fabricated and applied to non-enzymatic glucose detection. The as-prepared Cu-Ag nanocomposites based glucose sensor displays distinctly enhanced electrocatalytic activity compared to those obtained with pure Cu nanomaterials prepared with a similar procedure, revealing a synergistic effect of the matrix Cu and the doped Ag. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy indicate that the Cu-Ag superstructures based glucose sensor displays a fascinating sensitivity up to 7745.7 ?A mM(-1) cm(-2), outstanding detection limit of 0.08 ?M and fast amperometric response (<2 s) for glucose detection. Furthermore, the sensor also exhibits significant selectivity, excellent stability and reproducibility, as well as attractive feasibility for real sample analysis. Because of its excellent electrochemical performance, low cost and easy preparation, this novel electrode material is a promising candidate in the development of non-enzymatic glucose sensor. PMID:25113052

Li, Hua; Guo, Chun-Yan; Xu, Cai-Ling

2015-01-15

190

Shear Strength and Microstructure of Sn-3Ag-0.5Cu Solder Joints  

NASA Astrophysics Data System (ADS)

Sn-Ag-Cu based solders have been studied extensively as they show great promise for use in electronics assembly and packaging industry as alternatives to Sn-Pb based solders. As a further test of the reliability of these solders, the shear strength of single lap shear Sn-Ag-Cu solder joints was investigated. The microstructures of the solder joints and the fracture surfaces were examined using SEM.

Ekpenuma, Sylvester; He, Min; Acoff, Viola

2006-11-01

191

Accommodation of the misfit strain surrounding (III) precipitates [omega] in Al-Cu-Mg-(Ag)  

SciTech Connect

In this paper, [omega] phase in Al-Cu-Mg and Al-Cu-Mg-Ag is examined to determine the influence of silver addition on the [omega] precipitate structure and the effect of the large misfit normal to the [omega] plate habit plane on the interfacila structure. Using electron diffraction and HREM, no difference in [omega] structure could be discerned between the two alloys with and without Ag additions.

Fonda, R.W.; Shiflet, G.J. (Virginia Univ., Charlottesville, VA (United States). Dept. of Materials Science); Cassada, W.A. (Reynolds Metals Co., Richmond, VA (United States))

1992-10-01

192

Fatigue Crack Propagation Behavior of SnAgCu Solder Interconnects  

Microsoft Academic Search

Lead-free solders are replacing traditional lead-rich solders in the electronic industry. In the present study, the fatigue crack growth behavior of Sn-Ag-Cu solder interconnect has been investigated. An approach based on phase transformation theory and fracture mechanics was applied to predict fatigue crack propagation in a Sn-Ag-Cu interconnect, which consists of solder and intermetallic layers. Fatigue experiments were carried out

Yao Yao; Brent A. Fiedler; Leon M. Keer; Morris E. Fine

2009-01-01

193

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

SciTech Connect

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.

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

194

Ag-nanoparticles-decorated NiO-nanoflakes grafted Ni-nanorod arrays stuck out of porous AAO as effective SERS substrates.  

PubMed

NiO-nanoflakes (NiO-NFs) grafted Ni-nanorod (Ni-NR) arrays stuck out of the porous anodic aluminum oxide (AAO) template are achieved by a combinatorial process of AAO-confined electrodeposition of Ni-NRs, selectively etching part of the AAO template to expose the Ni-NRs, wet-etching the exposed Ni-NRs in ammonia to obtain Ni(OH)2-NFs grafted onto the cone-shaped Ni-NRs, and annealing to transform Ni(OH)2-NFs in situ into NiO-NFs. By top-view sputtering, Ag-nanoparticles (Ag-NPs) are decorated on each NiO-NFs grafted Ni-NR (denoted as NiO-NFs@Ni-NR). The resultant Ag-NPs-decorated NiO-NFs@Ni-NR (denoted as Ag-NPs@NiO-NFs@Ni-NR) arrays exhibit not only strong surface-enhanced Raman scattering (SERS) activity but also reproducible SERS-signals over the whole array. It is demonstrated that the strong SERS-activity is mainly ascribed to the high density of sub-10 nm gaps (hot spots) between the neighboring Ag-NPs, the semiconducting NiO-NFs induced chemical enhancement effect, and the lightning rod effect of the cone-shaped Ni-NRs. The three-level hierarchical nanostructure arrays stuck out of the AAO template can be utilized to probe polychlorinated biphenyls (PCBs, a kind of global environmental hazard) with a concentration as low as 5 10(-6) M, showing promising potential in SERS-based rapid detection of organic environmental pollutants. PMID:24419246

Zhou, Qitao; Meng, Guowen; Huang, Qing; Zhu, Chuhong; Tang, Haibin; Qian, Yiwu; Chen, Bin; Chen, Bensong

2014-02-28

195

Large-scale synthesis of Ni Ag core shell nanoparticles with magnetic, optical and anti-oxidation properties  

NASA Astrophysics Data System (ADS)

The large-scale synthesis and characterization of Ni-core/Ag-shell (Ni@Ag) nanoparticles by the successive hydrazine reduction of nickel chloride and silver nitrate in ethylene glycol using polyethyleneimine (PEI) as a protective agent are described. The resultant Ni@Ag nanoparticles had a mean core diameter of 6.2 nm and a shell thickness of 0.85 nm, without significant change in the nickel concentration of 0.25-25 mM for the Ag coating. Also, both Ni cores and Ag nanoshells had an fcc structure and PEI was capped on the particle surface. X-ray photoelectron spectroscopy analysis confirmed that the Ni cores were fully covered by Ag nanoshells. In addition, the Ni@Ag nanoparticles exhibited a characteristic absorption band at 430 nm and were nearly superparamagnetic. Based on the weight of Ni cores, the saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) were obtained as 17.2 emu g-1, 4.0 emu g-1 and 81 Oe, respectively. Furthermore, the resultant Ni@Ag nanoparticles exhibited better anti-oxidation properties than Ni nanoparticles did due to the protection of the Ag nanoshells.

Lee, Chung-Che; Chen, Dong-Hwang

2006-07-01

196

Effect of sintering temperature on structural and magnetic properties of NiCuZn and MgCuZn ferrites  

NASA Astrophysics Data System (ADS)

The low temperature microwave sintered NiCuZn and MgCuZn ferrites with compositions Ni 0.35Cu 0.05Zn 0.60Fe 2O 4 and Mg 0.35Cu 0.05Zn 0.60Fe 2O 4 were synthesized by conventional mixed oxide method. NiCuZn and MgCuZn ferrite samples obtained showed better sintered densities at 950 and 900 C, respectively. The scanning electron micrographs of both the ferrite samples appear to be very much similar. The magnitude of initial permeability of MgCuZn ferrite samples is found to be obviously higher than those of NiCuZn ferrite samples at all sintering temperatures. This is mainly due to the fact that MgCuZn ferrite has smaller magnetocrystalline anisotropy constant and magnetostrictive constant. NiCuZn ferrites have higher saturation magnetization than MgCuZn ferrites, which is due to the higher magnetic moment of NiCuZn ferrites. Our results indicate that the microwave sintering method seems to be a potential technique in the MLCI technology.

Penchal Reddy, M.; Madhuri, W.; Venkata Ramana, M.; Ramamanohar Reddy, N.; Siva Kumar, K. V.; Murthy, V. R. K.; Siva Kumar, K.; Ramakrishna Reddy, R.

2010-10-01

197

Microstructural and superconductive studies of Ag-YBa 2 Cu 3 O 7?x composites  

Microsoft Academic Search

Composites of Ag-YBa2Cu3O7-x were synthesized and carefully characterized for crystal structure and microstructure by X-ray diffraction, optical microscopy, SEM, TEM, and EDAX techniques in order to investigate the effect of Ag additions on the superconducting properties of 123 compounds. The a.c. susceptibility data show thatTc (onset) of 123+Ag composites vary between 90.2 and 91.8 K. TheJc values we measured for

H. R. Khan; T. L. Francavilla; R. A. Hein; C. S. Pande; S. B. Qadri; R. J. Soulen; S. A. Wolf

1990-01-01

198

Hydrogen evolution reaction measurements of dealloyed porous NiCu  

PubMed Central

Porous metals are of interest for their high surface area and potential for enhanced catalytic behavior. Electrodeposited NiCu thin films with a range of compositions were electrochemically dealloyed to selectively remove the Cu component. The film structure, composition, and reactivity of these samples were characterized both before and after the dealloying step using scanning electron microscopy, energy-dispersive spectroscopy, and electrochemical measurements. The catalytic behavior of the dealloyed porous Ni samples towards the hydrogen evolution reaction was measured and compared to that of the as-deposited samples. The dealloyed samples were generally more reactive than their as-deposited counterparts at low overpotentials, making the dealloying procedure a promising area of exploration for improved hydrogen evolution catalysts. PMID:24341569

2013-01-01

199

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

NASA Astrophysics Data System (ADS)

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.

Mohanty, Udit Surya; Lin, Kwang-Lung

2013-04-01

200

Power consumption reduction scheme of magnetic microactuation using electroplated Cu-Ni nanocomposite  

NASA Astrophysics Data System (ADS)

This letter presents a power consumption reduction scheme of magnetic microactuation using Cu-Ni nanocomposite film which is electroplated in alkaline noncyanide based Ni colloidal copper plating solution at 40C. The superconducting quantum interference device magnetometer measurements show that Cu film is modified from diamagnetism to ferromagnetism via the incorporation of Ni ferromagnetic nanoparticles into itself to form a Cu-Ni nanocomposite film. A magnetic microactuator made of the nanocomposite can have about 9% performance improvement in terms of actuation enlargement. In other words, the coil made of the Cu-Ni nanocomposite can exhibit better power efficiency for the same output displacement.

Huang, Yu Wen; Chao, Tzu-Yuan; Chen, C. C.; Cheng, Y. T.

2007-06-01

201

Effects of Electromigration on Interfacial Reactions in the Ni\\/Sn-Zn\\/Cu Solder Interconnect  

Microsoft Academic Search

Electromigration in the Ni\\/Sn-Zn\\/Cu solder interconnect was studied with an average current density of 3.51נ104A\\/cm2 for 168.5h at 150C. When the electrons flowed from the Ni side to the Cu side, uniform layers of Ni5Zn21 and Cu5Zn8 were formed at the Ni\\/Sn-Zn and Cu\\/Sn-Zn interfaces. However, upon reversing the current direction, where electron flow was\\u000a from the Cu side to

X. F. Zhang; J. D. Guo; J. K. Shang

2009-01-01

202

Rapid dechlorination of chlorophenols in aqueous solution by [Ni|Cu] microcell.  

PubMed

The [Ni|Cu] microcell was prepared by mixing the Ni(0) and Cu(0) particles. The composition and crystal form were characterized by X-ray diffraction (XRD) and scanning electron microscope. The results evidenced the zero-valence metals Ni and Cu were exposed on the surface of particles mixture. The [Ni|Cu] microcell was employed to decompose chlorophenols in aqueous solution by reductive dechlorination. The dechlorination rates of chlorophenols by [Ni|Cu] were >10 times faster than those by [Fe|Cu], [Zn|Cu], [Sn|Cu], and [Fe|Ni] mixtures under the same conditions. [Ni|Cu] is different from other zero valent metals (ZVMs) in that it performed the best at neutral pH. The main products of chlorophenol dechlorination were cyclohexanol and cyclohexanone. The reduction kinetics was between pseudo zero-order and first-order, depending on the pH, concentration, and temperature. These results, combined with electrochemical analysis, suggested that Ni(0) acted as a reductant and catalyst in dechlorination reaction. The H* corridor mechanism from Ni(0) to Cu(0) was also proposed based on hydrogen spillover. The inhibition on the release of Ni(2+) by adding natural organic matters and adjusting pH was investigated. PMID:22305601

Yin, Lifeng; Dai, Yunrong; Niu, Junfeng; Bao, Yueping; Shen, Zhenyao

2012-03-30

203

Mo (W,V)?Cu (Ag)?S(Se) cluster compounds  

Microsoft Academic Search

This review summarizes the preparation, skeletal structure, reactions, spectroscopic properties and non-linear optical properties of Mo(W,V)?Cu(Ag)?S(Se) cluster compounds; 190 such compounds belong to 23 structural types; 25 reactions are classified into ligand substitution, addition and decomposition reactions. Recently, some Mo(W)?Cu(Ag)?S clusters were found to exhibit strong non-linear optical properties; the optical limiting threshold measured for [(PPh3)4Ag4Mo2S8] is one order of

Hong-Wei Hou; Xin-Quan Xin; Shu Shi

1996-01-01

204

Electromigration in Cu-Cored Sn-3.5Ag-0.7Cu Solder Interconnects Under Current Stressing  

NASA Astrophysics Data System (ADS)

The effect of electromigration in Cu-cored Sn-3.5Ag-0.7Cu solder interconnects under current stressing was investigated. After current stressing at a density of 2 104 A/cm2, some Cu6Sn5 intermetallic compounds accumulated abnormally on the surface of the solder interconnect. The abnormal accumulation phenomenon was explained by the mechanism that thermomigration dominated the migration process. Furthermore, some Cu6Sn5 extrusions appeared on the cathode-side surface of the solder interconnect due to the compressive stresses induced by electromigration and thermomigration.

Sa, Xianzhang; Zhou, Wei; Wu, Ping

2014-04-01

205

Cathodic peeling damage of Cu6Sn5 phase in Cu/SnAg3.0Cu0.5/Cu bridge interconnections under current stressing  

NASA Astrophysics Data System (ADS)

The cathodic interfacial damage behavior that has been attributed to electromigration is serious but has often been confused with thermomigration damage in solder interconnections. In this paper, after the effects of the non-uniform temperature distribution of Cu/SnAg3.0Cu0.5/Cu bridge joints are decoupled from the effects of the current stress, the microstructural evolution of the cathodic Cu6Sn5 phase is investigated under an average current density of 7.12 107 A.m-2 for 0-350 h. The results show that the interfacial Cu6Sn5 peels rather than dissolving completely at the cathode, because of both adhesion degradation at the Cu6Sn5/Cu interface and sustained cathodic stresses. This unrecorded peeling behavior will contribute to the rapid formation of interfacial voids and will thus dramatically increase the risk of interfacial failure. Fortunately, by restricting the intergranular diffusion and enhancing the bond strengths between adjacent Cu6Sn5 grains, an aging pre-treatment of the solder joints is found to be an effective way to slow down the Cu6Sn5 peeling process and achieve robust solder interconnections.

Zhang, Z. H.; Cao, H. J.; Li, M. Y.; Wang, Y.; Liu, Z. Q.

2014-08-01

206

Ag-Cu and As-Sb exchange energies in tetrahedrite-tennantite fahlores  

NASA Astrophysics Data System (ADS)

Fahlerz group sulfosalts having the general structural formula (Ag, Cu) III6[(Ag, Cu) 2/3(Fe, Zn) 1/3] IV6(As, Sb) 4S 13 have been equilibrated with the assemblage electrum + pyrite + chalocopyrite in reversed exchange experiments. Control of log ( as) at -6.0 was maintained by abundant FeS 2 + (Fe .05Zn .95)S and minimum vapor space. Reversal brackets demonstrate that the Ag/(Ag + Cu) and As/(As + Sb) ratios in this sulfosalt are strongly correlated, at a fixed composition of coexisting electrum. Evaluated in the context of the thermochemical model of SACKet al. (1987), these results indicate that the molar Gibbs energy of the reciprocal reaction Ag10Fe2Sb4S13 + Cu10Fe2As4S13Ag10Fe2As4S13 + Cu10Fe2Sb4S13, ( ? ?034) is 12.25 1.92 kilocalories. This provides a crucial missing parameter for the thermodynamic calculations we have developed earlier. This model is applied to calculation of end-member activities; integration with studies of hydrothermal fluids in ore-forming systems is planned.

Ebel, Denton S.; Sack, Richard O.

1989-09-01

207

Ag-doped CuGaSe 2 as a precursor for thin film solar cells  

NASA Astrophysics Data System (ADS)

For the preparation of p-CuGaSe 2 thin film absorbers, powder of single-phase CuGaSe 2 with defined optical and electrical properties is required as precursor material for solar cells. The motivation for this work was that thin films shall be produced by a chemical vapour transport method using iodine as transport agent. Here we report on an optimised synthesis method of this precursor material and discuss the effect of Ag-doping using Ag, AgSe 2 and AgJ as dopants. Crystalline material was characterised by intensity-dependent photoluminescence (PL), X-ray diffraction (XRD) and time resolved microwave conductivity (TRMC). PL-measurements at T=10 K of undoped CuGaSe 2 show a dominating emission at E=1.67 eV which is attributed to a free-to-bound transition where the acceptor bound state is assigned to copper vacancies. Ag-doped samples showed a dominating emission at E=1.61 eV which is attributed to a donor acceptor pair-transition with copper vacancies as acceptors and selenium vacancies as donors. XRD-measurements showed good single-phase quality of CuGaSe 2. TRMC-measurements reveal an increase of the hole mobility of Ag-doped material compared to undoped CuGaSe 2.

Weiss, T.; Birkholz, M.; Saad, M.; Bleyhl, S.; Kunst, M.; Jger-Waldau, A.; Lux-Steiner, M. Ch.

1999-03-01

208

Magnetoelastic stress in Cu/Ni/Cu/Si(100) epitaxial thin films  

NASA Astrophysics Data System (ADS)

The magnetoelastic (ME) stresses for a series of Cu/Ni(tNi)/Cu/Si(001) epitaxial films are reported. The direct measurement of the stresses in the (001) plane allows determination of the irreducible ME stress Beff?,2 that accounts for the breaking of the in-plane square symmetry. Beff?,2 has been determined as a function of the applied magnetic field (15kOe) and the temperature (300-10K) for tNi ranging from 5 to 15nm . The temperature dependence of Beff?,2 is proportional to the square power of the reduced magnetization and the 0K value increases with the internal stress. These experimental observations are explained considering the tetragonal distortion of the nickel caused by the epitaxial strain that the copper lattice introduces in the nickel layers.

Ciria, M.; Arnaudas, J. I.; Del Moral, A.; O'Handley, R. C.

2004-08-01

209

Alloy Catalyst in a Reactive Environment: The Example of Ag-Cu Particles for Ethylene Epoxidation  

NASA Astrophysics Data System (ADS)

Combining first-principles calculations and in situ photoelectron spectroscopy, we show how the composition and structure of the surface of an alloy catalyst is affected by the temperature and pressure of the reagents. The Ag-Cu alloy, recently proposed as an improved catalyst for ethylene epoxidation, forms a thin Cu-O surface oxide, while a Ag-Cu surface alloy is found not to be stable. Several possible surface structures are identified, among which the catalyst surface is likely to dynamically evolve under reaction conditions.

Piccinin, Simone; Zafeiratos, Spiros; Stampfl, Catherine; Hansen, Thomas W.; Hvecker, Michael; Teschner, Detre; Bukhtiyarov, Valerii I.; Girgsdies, Frank; Knop-Gericke, Axel; Schlgl, Robert; Scheffler, Matthias

2010-01-01

210

Electronic structure of Ag2Cu2O4. Evidence of oxidized silver and copper and internal charge delocalization.  

PubMed

The electronic structure of the recently isolated silver copper oxide Ag(2)Cu(2)O(4) is analyzed along with its precursor Ag(2)Cu(2)O(3) and similar binary oxides, Ag(2)O, AgO, CuO, and NaCuO(2), using X-ray photoemission (XPS) and X-ray absorption (XAS) measurements. The results for Ag(2)Cu(2)O(4) reveal an electronic distribution in which silver and copper share a delocalized valence scheme with both metals in formal oxidation states larger than the usual Ag(I) and Cu(II). Only one type of crystallographic silver or copper is found, but disorder-strain parameters are considerable and the possibilities of thermal disorder, atomic motion, oxygen contribution, mixed valence, and internal charge delocalization are considered. Classical coordination descriptions for oxidized silver are revisited in terms of this new internal charge delocalization framework found for the electronic structure. PMID:16851685

Muoz-Rojas, D; Subas, G; Fraxedas, J; Gmez-Romero, P; Casa-Pastor, N

2005-04-01

211

Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films  

NASA Astrophysics Data System (ADS)

A key property of multicomponent bioactive nanostructured Ti(C,N)-based films doped with Ca, P, and O (TiCaPCON) that can be improved further is their antibacterial effect that should be achieved without compromising the implant bioactivity and biocompatibility. The present work is focused on the study of structure, chemical, mechanical, tribological, and biological properties of Ag- and Cu-doped TiCaPCON films. The films with Ag (0.4-4 at.%) and Cu (13 at.%) contents were obtained by simultaneous sputtering of a TiC0.5-Ca3(PO4)2 target and either an Ag or a Cu target. The film structure was studied using X-ray diffraction, transmission and scanning electron microscopy, energy dispersive X-ray spectroscopy, glow discharge optical emission spectroscopy, and Raman-shift and IR spectroscopy. The films were characterized in terms of their hardness, elastic modulus, dynamic impact resistance, friction coefficient and wear rate (both in air and normal saline), surface wettability, electrochemical behavior and Ag or Cu ion release in normal saline. Particular attention was paid to the influence of inorganic bactericides (Ag and Cu ions) on the bactericidal activity against unicellular yeast fungus Saccharomyces cerevisiae and gram-positive bacteria Lactobacillus acidophilus, as well as on the attachment, spreading, actin cytoskeleton organization, focal adhesions, and early stages of osteoblastic cell differentiation. The obtained results show that the Ag-doped films are more suitable for the protection of metallic surfaces against bacterial infection compared with their Cu-doped counterpart. In particular, an excellent combination of mechanical, tribological, and biological properties makes Ag-doped TiCaPCON film with 1.2 at.% of Ag very attractive material for bioengineering and modification of load-bearing metal implant surfaces.

Shtansky, D. V.; Batenina, I. V.; Kiryukhantsev-Korneev, Ph. V.; Sheveyko, A. N.; Kuptsov, K. A.; Zhitnyak, I. Y.; Anisimova, N. Yu.; Gloushankova, N. A.

2013-11-01

212

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

NASA Astrophysics Data System (ADS)

Transient liquid phase (TLP) bonding is a process currently used for joining heat resistant alloys, for example nickel- and cobalt-based superalloys. It involves the formation of a liquid layer between two adjoining pieces and the formation of a solid bond as the liquid disappears during annealing at a suitable constant temperature. In the present study, a model Ag/Cu/Ag sandwich joint associated with a simple eutectic phase diagram was used to study the different stages of this process. The results confirm that the TLP bonding is a diffusional process occurring in clearly distinctive stages. The two most important stages are the widening and homogenization of the previously dissolved liquid interlayer, and the subsequent solidification and shrinking of the interlayer. Whereas the former stage involves diffusional processes both in the liquid phase and in the adjoining solids, the latter is controlled mainly by the diffusion in the solid phase. A modeling approach has been explored which shows that in most eutectic systems there exists an optimal bonding temperature corresponding to the shortest time needed for complete solidification. The results of a study on a Ag/Ag-20 wt pct Cu/Ag sandwich joint provide evidence that the use of an alloy close to the eutectic composition as an interlayer material shortens the TLP process substantially.

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

1988-03-01

213

Microwave-absorbing characteristics of epoxy resin composites containing nanoparticles of NiZn- and NiCuZn-ferrites  

NASA Astrophysics Data System (ADS)

NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni 0.5 Zn 0.5Fe 2O 4 (NiZn) and Ni 0.35Cu 0.15Zn 0.5Fe 2O 4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu/g (NiZn) to 91 emu/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range of 1 MHz-1.8 GHz. Reflection losses ( RL) for both samples were calculated from complex permeability and permittivity. Cu substitution in NiZn-ferrite enhances permeability and RL. In order to explore microwave-absorbing properties in X-band, magnetic nanoparticles were mixed with an epoxy resin to be converted into a microwave-absorbing composite and microwave behaviors of both materials were studied using a microwave vector network analyzer from 7.5 to 13.5 GHz. Cu substitution diminishes absorption intensity in the range 11.5-12.5 GHz.

Aphesteguy, J. C.; Damiani, Abel; DiGiovanni, Dalmas; Jacobo, S. E.

2009-10-01

214

Distribution of Ag in Cu-sulfides in Kupferschiefer deposit, SW Poland  

NASA Astrophysics Data System (ADS)

The Cu-Ag Kupferschiefer deposit located at the Fore-Sudetic Monocline (SW Poland) is a world class deposit of stratabound type. The Cu-Ag mineralization in the deposit occurs in the Permian sedimentary rocks (Rotliegend and Zechstein) in three lithological types of ore: the dolomite, the black shale and the sandstone. Silver, next to copper, is the most important element in the Kupferschiefer deposit (Salamon 1979; Piestrzy?ski 2007; Pieczonka 2011). Although occurrence of the Ag-minerals such as native silver, silver amalgams, stromeyerite, jalpaite and mckinstryite, silver is mainly present in the deposit due to isomorphic substitutions in Cu-minerals such as chalcocite, bornite, tennantite, covellite and chalcopyrite. The aim of the study was to define distribution of silver in Cu-minerals and correlate occurrence of Ag-enriched Cu-sulfides with native silver and silver amalgams. Identification of minerals and textural observation were performed using field emission scanning electron microscope. Analyzes of chemical composition of Cu-sulfides were performed utilizing electron microprobe. Silver concentration in Cu sulfides ranges from 0.1 to 10.4 wt.% in chalcocite, 0.2-15.8 wt.% in bornite, 0.1-2.9 wt.% in tennantite, 0.05-0.3 wt.% in chalcopyrite and ca. 0.4 wt.% in covellite. In general, distribution of silver in Cu-minerals is irregular, as indicated by high variations of Ag concentration in each mineral. Content of Ag in Cu-sulphides, in samples where native silver and silver amalgams are not found, is lower than in samples, where native silver and silver amalgams are noted. The chemical analyzes of Ag-bearing Cu-minerals indicate decrease of Cu content in minerals with high Ag concentration. In such case, decrease of Fe content is also noted in bornite. Lack of micro-inclusions of the native silver or silver amalgams in the Cu-minerals indicates that presence of Ag is mainly related to the isomorphic substitutions. This is in agreement with previous reports on high Ag content reaching 49 wt.% Ag in bornite and 1.8 wt.% Ag in chalcocite occurring due to Ag substitution in Cu-minerals without modification of their crystallographic structure (Salamon 1979; Bana? et al 2007; Kucha 2007; Piestrzy?ski 2007, Pieczonka 2011). Acknowledgements. This work was supported by the National Science Centre research grant (No 2011/03/N/ST10/04619). References: Kucha H and Mayer W (2007) Geochemistry. [In:] Piestrzy?ski A (Ed) Monografia KGHM Polska Mied? SA., pp 197-207 (In Polish) Pieczonka J (2011) Factors controlling distribution of ore minerals within copper deposit, Fore-Sudetic Monocline, SW Poland. 195 pp (In Polish) Piestrzy?ski A (2007) Ore minerals. [In:] Piestrzy?ski A (Ed) Monografia KGHM Polska Mied? SA., pp 167-197 (in Polish) Salamon W (1979) Occurrence of the Ag and Mo in the Zechstein sediments of the Fore-Sudetic Monocline. Prace Mineralogiczne, PAN 62, pp 1-52 (In Polish)

Kozub, Gabriela A.

2014-05-01

215

Effects of composition and sintering temperature on properties of NiZn and NiCuZn ferrites  

NASA Astrophysics Data System (ADS)

Effects of composition and sintering temperature on grain size, porosity and magnetic properties of the NiZn and NiCuZn ferrites were investigated. It was found that the lowest power loss could be obtained with the equimolar composition for both NiZn and NiCuZn ferrites, which could be attributed to the lowest porosity. A slight deficiency or excess of Fe 2O 3 content had no pronounced influence on saturation magnetic flux density ( Bs) in our testing range. However, a slight excess of Fe 2O 3 was effective to improve the initial permeability, which could be attributed to decrease of the magnetocrystalline anisotropy. With the increase of sintering temperature, the initial permeability and power loss of the NiZn and NiCuZn ferrites had different development trend, which could be explained by the different variation trend of the grain size and porosity. Power losses of the NiCuZn ferrite samples were lower than that of the NiZn ferrite samples at any sintering temperature. Synthetically, the NiCuZn ferrites had a better performance than the NiZn ferrites in power field use.

Su, Hua; Zhang, Huaiwu; Tang, Xiaoli; Jing, Yulan; Liu, Yingli

2007-03-01

216

Interaction behavior between the additives and Sn in Sn3.0Ag0.5Cu-based solder alloys and the relevant joint solderability  

Microsoft Academic Search

The minor element Co\\/Ni was adopted to study the microstructural evolution of Sn3.0Ag0.5Cu (SAC305) lead-free solder alloy. The 0.2 mass% Co addition induced the formation of CoSn2 in the cast SAC305 solder. After the storage at 300C for 24h and the subsequent cooling, a new CoSn3-based phase containing small amount of Cu was generated while the initial CoSn2 disappeared. No

Fangjie Cheng; Feng Gao; Hiroshi Nishikawa; Tadashi Takemoto

2009-01-01

217

Low temperature spin dynamics in Cr7Ni-Cu-Cr7Ni coupled molecular rings  

SciTech Connect

Proton Nuclear Magnetic Resonance (NMR) relaxation measurements have been performed down to very low temperature (50?mK) to determine the effect of coupling two Cr7 Ni molecular rings via a Cu 2+ ion. No difference in the spin dynamics was found from nuclear spin lattice relaxation down to 1.5?K. At lower temperature, the 1H-NMR line broadens dramatically indicating spin freezing. From the plot of the line width vs. magnetization, it is found that the freezing temperature is higher (260?mK) in the coupled ring with respect to the single Cr7 Ni ring (140?mK).

Bordonali, L.; Furukawa, Y.; Mariani, M.; Sabareesh, K. P.; Garlatti, E.; Carretta, S.; Lascialfari, A.; Timco, G.; Winpenny, R. E.; Borsa, F.

2014-05-07

218

High-permeability and high-Curie temperature NiCuZn ferrite  

Microsoft Academic Search

High-permeability and high-Curie temperature NiCuZn ferrite was developed for use in telecommunication. In the development process, attention was focused on the amount of CuO contained in NiZn ferrite and a small additive of MoO3 added in the NiCuZn ferrite. It was confirmed that the initial permeability of the core increased and the Curie temperature only decreased a little with 4mol%

Hua Su; Huaiwu Zhang; Xiaoli Tang; Xinyuan Xiang

2004-01-01

219

Hydrogen production by ethanol steam reforming over CuNi supported catalysts  

Microsoft Academic Search

In the present work, CuNi supported catalysts were tested in ethanol steam reforming reaction. Two commercial amorphous solids (SiO2 and ?-Al2O3) and three synthesized materials (MCM-41, SBA-15 and ZSM-5 nanocrystalline) were used as support. A series of CuNi\\/SiO2 catalysts with different Cu and Ni content were also prepared. It was found that aluminium containing supports favour ethanol dehydration to ethylene

A. J. Vizcano; A. Carrero; J. A. Calles

2007-01-01

220

Synthesis of CuNi Alloy Powder Directly from Metal Salts Solution  

Microsoft Academic Search

CuNi alloy powders were synthesized directly from metal nitrate solution. Combustion, ultrasonic mist combustion and ultrasonic pyrolysis processes were applied and CuNi 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 CuNi alloy powder prepared by

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

2003-01-01

221

Electroless NiCuP plating onto open cell stainless steel foam  

Microsoft Academic Search

Metallic foams with a high fraction of porosity, low density and high energy absorption capacity, are a rapidly emerging class of novel ultralightweight materials for various engineering applications. Development of these materials with NiCuP coatings is expected to widespread their industrial utilizations. This article aims to apply NiCuP coatings onto open cell stainless steel foams from NiP bath containing CuSO45H2O

A. Abdel Aal; M. Shehata Aly

2009-01-01

222

Calcium alginate encapsulated Ni/Fe nanoparticles beads for simultaneous removal of Cu (II) and monochlorobenzene.  

PubMed

Calcium alginate encapsulated Ni/Fe bimetallic nanoparticles beads (CA-Ni/Fe beads) were synthesized to simultaneously remove Cu (II) and monochlorobenzene (MCB) from aqueous solution. SEM, EDS, and XRD analyses confirmed that Ni/Fe bimetallic nanoparticles were not oxidized and successfully encapsulated by calcium alginate (CA). The experiments showed that the encapsulation process improved the simultaneous removal efficiency of Cu (II) and MCB, from 83.9% to 86.7% for Cu (II) and 94.7% to 99.1% for MCB compared with bare Ni/Fe nanoparticles after 120min treatment. Furthermore, the removal efficiency of Cu (II) and MCB increased with higher temperature, calcium alginate: Ni/Fe ratios and pH. Pseudo-second-order model for adsorption and pseudo-first-order model for the reduction process fitted the simultaneous removal of Cu (II) and MCB using CA-Ni/Fe beads. Based on the above results, it could be concluded that the simultaneous removal was a two-step process: firstly, the adsorption of Cu (II) and MCB on the CA-Ni/Fe beads; and secondly, reduction of Cu (II) and dehalogenation of MCB by Ni/Fe in CA-Ni/Fe beads. Finally, the efficiency of regenerated CA-Ni/Fe beads was tested using synthesized wastewater which showed a satisfactory removal efficiency of Cu (II) and MCB maintained at 83.8% and 91.7% after three times' regeneration. PMID:25700214

Kuang, Ye; Du, Jianhua; Zhou, Rongbing; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2015-06-01

223

Synthesis and characterization of Ag/Cu/HAP with platelet morphology.  

PubMed

As a useful starting material in coating technology and preparation of HAP/polymers composites the platelet Ag/Cu/HAP was prepared using the solid solution of HAP reacting with the mix-solution of silver and copper nitrate. Its composition, microstructure and properties were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and anti-bacterial or bacteriostatic tests. The results demonstrate that the prepared Ag/Cu/HAP crystal is mainly comprised of HAP phase with little whitelockite and silver phosphate, stable up to 600 degrees C and takes a platelet shape. At 750 degrees C, it is partially changed into whitelockite, calcium copper phosphate, silver oxide and silver phosphate. The platelet Ag/Cu/HAP crystal has a preferential orientation of a-axis below 600 degrees C, above which the growth in a-axis is greatly inhibited. The Ag/Cu/HAP has good crystallinity at 600 degrees C and is the most effective powder in resisting bacteria among the HAP powders investigated. The platelet Ag/Cu/HAP crystal can be good starting materials to make antibacterial polymers/HAP composites and HAP coatings. PMID:19020958

Yang, Hui; Xiao, Bingjuan; Xu, Ke-Wei

2009-03-01

224

Preparation and optical properties of silica Ag-Cu alloy core-shell composite colloids  

SciTech Connect

The silica Ag-Cu alloy core-shell composite colloids have been successfully synthesized by an electroless plating approach to explore the possibility of modifying the plasmon resonance at the nanoshell surface by varying the metal nanoshell composition for the first time. The surface plasmon resonance of the composite colloids increases in intensity and shifts towards longer, then shorter wavelengths as the Cu/Ag ratio in the alloy shell is increased. The variations in intensity of the surface plasmon resonance with the Cu/Ag ratio obviously affect the Raman bands of the silica colloid core. The report here may supply a new technique to effectively modify the surface plasmon resonance. - Graphical abstract: The silica Ag-Cu alloy core-shell colloids have been successfully synthesized to explore the possibility of modifying the surface plasmon resonance (SPR) by varying the metal nanoshell composition for the first time. Varying the Cu/Ag ratio of the alloy nanoshell has obvious influences on the SPR of the composite colloids and the Raman bands of the amorphous silica core.

Zhang Jianhui [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China)], E-mail: zhangjh@nju.edu.cn; Liu Huaiyong [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China); Wang Zhenlin [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China); Ming Naiben [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China)

2007-04-15

225

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)

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.

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

2013-08-01

226

Investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al alloy with Ag and Mn additions  

SciTech Connect

The investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al, Cu-11%Al-3%Ag, Cu-11%Al-10%Mn and Cu-11%Al-10%Mn-3%Ag alloys was made using microhardness measurements, differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersion X-ray spectroscopy and magnetic moment change with applied field measurement. The results indicated that the Mn addition changes the phase stability range, the microhardness values and makes undetectable the eutectoid reaction in annealed Cu-11%Al and Cu-11%Al-3%Ag alloys while the presence of Ag does not modify the phase transformation sequence neither microhardness values of the annealed Cu-11%Al and Cu-11%Al-10%Mn alloys, but it increases the magnetic moment of this latter at about 2.7 times and decreases the rates of eutectoid and peritectoid reactions of the former. - Highlights: Black-Right-Pointing-Pointer The microstructure of Cu-Al alloy is modified in the Ag presence. Black-Right-Pointing-Pointer ({alpha} + {gamma}) phase is stabilized down to room temperature when Ag is added to Cu-Al alloy. Black-Right-Pointing-Pointer Ag-rich phase modifies the magnetic characteristics of Cu-Al-Mn alloy.

Silva, R.A.G., E-mail: galdino.ricardo@gmail.com [Departamento de Ciencias Exatas e da Terra-UNIFESP, Diadema-SP (Brazil)] [Departamento de Ciencias Exatas e da Terra-UNIFESP, Diadema-SP (Brazil); Paganotti, A.; Gama, S. [Departamento de Ciencias Exatas e da Terra-UNIFESP, Diadema-SP (Brazil)] [Departamento de Ciencias Exatas e da Terra-UNIFESP, Diadema-SP (Brazil); Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A. [Instituto de Quimica - UNESP, Araraquara-SP (Brazil)] [Instituto de Quimica - UNESP, Araraquara-SP (Brazil)

2013-01-15

227

Noble metals (Ag, Au) nanoparticles addition effects on superconducting properties of CuTl-1223 phase  

NASA Astrophysics Data System (ADS)

Low anisotropic (Cu0.5Tl0.5) Ba2Ca2Cu3O10 - ? (CuTl-1223) high temperature superconducting phase was synthesized by solid-state reaction, silver (Ag) nanoparticles were prepared by sol-gel method and gold (Au) nanoparticles were extracted from colloidal solution. We added Ag and Au nanoparticles in CuTl-1223 matrix separately with same concentration during the final sintering process to get (M)x/CuTl-1223; M = Ag nanoparticles or Au nanoparticles (x = 0 and 1.0 wt.%) nano-superconductor composites. We investigated and compared the effects of these noble metals nanoparticles addition on structural, morphological and superconducting transport properties of CuTl-1223 phase. The crystal structure of the host CuTl-1223 superconducting phase was not affected significantly after the addition of these nanoparticles. The enhancement of superconducting properties was observed after the addition of both Ag and Au nanoparticles, which is most probably due to improved inter-grains weak-links and reduction of defects such as oxygen deficiencies, etc. The reduction of normal state room temperature resistivity is the finger prints of the reduction of barriers and facilitation to the carriers transport across the inter-crystallite sites due to improved inter-grains weak-links. The greater improvement of superconducting properties in Ag nanoparticles added samples is attributed to the higher conductivity of silver as compared to gold, which also suits for practical applications due to lower cost and easy synthesis of Ag nanoparticles as compared to Au nanoparticles.

Jabbar, Abdul; Mumtaz, Muhammad; Nadeem, Kashif

2015-03-01

228

Hydrolysis of PNPP Catalyzed by Cu (II), Ni (II) Schiff Base Complexes in CTAB Micellar Solution  

Microsoft Academic Search

The kinetics of hydrolysis of p?nitrophenyl picolinate(PNPP) catalyzed by metallomicelles formed from Cu (II), Ni (II) Schiff base complexes (CuL, NiL) and CTAB micelle were investigated in the pH range of 6.09.0 at 30C. For the Cu (II) Schiff base complex CuL, the apparent rate constants (kobsd) of PNPP hydrolysis initially increased with the increasing pH of reaction media, then

Min Li; Dong Kou; Juan Du

2007-01-01

229

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

PubMed

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

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

2015-03-27

230

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)

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 UVvis 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.

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

2015-03-01

231

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

E-print Network

5 VARIATION DE L'NERGIE D'ANISOTROPIE MAGNTIQUE DU Ni ET DES ALLIAGES Ni-Cu, EN FONCTION DE LA thorie de la variation de l'nergie d'anisotropie magntique du Ni et des alliages Ni-Cu en fonction de et des alliages Ni-Cu. L'nergie d'anisotropie Ek d'un cristal magn- tique s'exprime habituellement

Boyer, Edmond

232

Formation of Ti-Zr-Cu-Ni bulk metallic glasses  

NASA Astrophysics Data System (ADS)

Formation of bulk metallic glass in quaternary Ti-Zr-Cu-Ni alloys by relatively slow cooling from the melt is reported. Thick strips of metallic glass were obtained by the method of metal mold casting. The glass forming ability of the quaternary alloys exceeds that of binary or ternary alloys containing the same elements due to the complexity of the system. The best glass forming alloys such as Ti34Zr11Cu47Ni8 can be cast to at least 4-mm-thick amorphous strips. The critical cooling rate for glass formation is of the order of 250 K/s or less, at least two orders of magnitude lower than that of the best ternary alloys. The glass transition, crystallization, and melting behavior of the alloys were studied by differential scanning calorimetry. The amorphous alloys exhibit a significant undercooled liquid region between the glass transition and first crystallization event. The glass forming ability of these alloys, as determined by the critical cooling rate, exceeds what is expected based on the reduced glass transition temperature. It is also found that the glass forming ability for alloys of similar reduced glass transition temperature can differ by two orders of magnitude as defined by critical cooling rates. The origins of the difference in glass forming ability of the alloys are discussed. It is found that when large composition redistribution accompanies crystallization, glass formation is enhanced. The excellent glass forming ability of alloys such as Ti34Zr11Cu47Ni8 is a result of simultaneously minimizing the nucleation rate of the competing crystalline phases. The ternary/quaternary Laves phase (MgZn2 type) shows the greatest ease of nucleation and plays a key role in determining the optimum compositions for glass formation.

Lin, X. H.; Johnson, W. L.

1995-12-01

233

Morphology of Cu2S-CdS and Ag2S-CdS Nanorod Heterostructures  

NASA Astrophysics Data System (ADS)

A partial cation exchange has been used to synthesize Cu2S-CdS and Ag2S-CdS nanocrystal heterostructures, with two very different morphologies. Cu^+ cation exchange takes place preferentially at the ends of CdS nanorods, Cu2S segments grow into the nanorod from both ends. Ag^+ exchange is non-selective, Ag2S islands nucleate and grow over the entire surface of the nanorod. This leads to very different patterns, striped Ag2S-CdS superlattice with several equidistant Ag2S segments in a CdS nanorod, and an asymmetric Cu2S-Cds heterostructure with Cu2S segments at the ends of the CdS nanorod. We use first-principles calculations to obtain formation energies of the different epitaxial interfaces between Cu(Ag)2S and different facets of CdS nanorods. Comparison of chemical and elastic contributions to the interface formation energy for the Cu(Ag)2S-CdS shows that the relative stability of the interfaces determines the nucleation of Cu(Ag)2S and the resulting morphology. Furthermore, since two end facets of CdS nanorod are not crystallographically equivalent a controlled asymmetric nucleation of Cu2S can occur.

Demchenko, Denis; Sadtler, Bryce; Zheng, Haimei; Alivisatos, A. Paul; Wang, Lin-Wang

2009-03-01

234

On the discontinuous precipitation reaction and solute redistribution in a Cu-15%Ni-8%Sn alloy  

SciTech Connect

Optical and transmission electron microscopy studies have been undertaken in order to clarify some morphological aspects of the discontinuous precipitation (DP) reaction in a Cu-15Ni-8Sn (wt.%) alloy in the temperature range 800-950 K. The DP reaction proceeds in the ternary Cu-Ni-Sn system relatively fast (in binary Cu-Ni alloy is not present) with typical morphological features like change of growth direction, appearance and disappearance of solute-rich {gamma} lamellae. A fine continuous precipitation of single Ni and Sn-rich phase was also evidenced within the solute-depleted {alpha} lamellae. An energy-dispersive X-ray analysis showed the level of partitioning of the alloying elements. Most of the Ni and Sn is located in the {gamma} lamellae. However, the formula of the {gamma} lamellae is still close to (Cu{sub 3}Sn), which indicates that some Cu atoms are replaced by Ni.

Alili, B.; Bradai, D. [Houari Boumediene University of Sciences and Technology, BP 32 El-Alia, Algiers (Algeria); Zieba, P. [Houari Boumediene University of Sciences and Technology, BP 32 El-Alia, Algiers (Algeria)], E-mail: nmzieba@imim-pan.krakow.pl

2008-10-15

235

Cu-Ni-Fe anodes having improved microstructure  

DOEpatents

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.

Bergsma, S. Craig; Brown, Craig W.

2004-04-20

236

Kerr rotation in Cu, Ag, and Au driven by spin accumulation and spin-orbit coupling  

NASA Astrophysics Data System (ADS)

We measure transient spin accumulation in Cu, Ag, and Au by time-resolved magneto-optical Kerr effect. The transient spin current is generated by ultrafast demagnetization of a ferromagnetic [Co/Pt] layer, and spin accumulates in an adjacent normal metal, Cu, Ag, or Au by spin diffusion. The magnitude of the Kerr rotation is described by an off-diagonal conductivity tensor that is proportional to spin accumulation and spin-orbit coupling. From comparisons between observed Kerr rotations and calculated spin accumulations, we determine the strength of spin-orbit coupling of conduction electrons in Cu, Ag, and Au to be 0.02, 0.01, and 0.12 eV , respectively.

Choi, Gyung-Min; Cahill, David G.

2014-12-01

237

Spectroscopic data and Stark broadening of Cu I and Ag I spectral lines: Selection and analysis  

NASA Astrophysics Data System (ADS)

Optical emission and linear laser absorption spectroscopy techniques were used in investigation of plasma with copper and silver admixture. The method of selection of spectral lines and spectroscopic data with the aim of diagnostics of multicomponent air plasma with two metal vapors admixture was developed. Energy level populations behavior on the Boltzmann plot were used for Cu I and Ag I spectroscopic data selection. In this way the selection of spectroscopic data for some of Cu I and Ag I lines was realized. Stark broadening parameters of Cu I and Ag I were examined. Experimentally obtained temperature and electron density radial distributions were used in the calculation of plasma composition in the assumption of local thermodynamic equilibrium. Linear laser absorption spectroscopy was used to examine the state of plasma.

Babich, I. L.; Boretskij, V. F.; Veklich, A. N.; Semenyshyn, R. V.

2014-10-01

238

Strain and magnetic anisotropy of epitaxial Ni/Cu(001) nanostructures  

NASA Astrophysics Data System (ADS)

The magnetic anisotropy of isolated epitaxial Ni/Cu(001) nanostructure on Si(001) has been studied together with structural characterization. The strain of the Ni nanostructure is released such that the perpendicular strain of nanostructure with tNi=10 nm decreases to -0.48% from -1.17% of film with the same thickness. Because of this, strain becomes the main factor in determining magnetic anisotropy of Ni/Cu nanostructure in the investigated Ni thickness range (tNi=4.5-10 nm).

Lee, S. G.; Shin, S. W.; Jang, J. W.; Hwang, H. M.; Jang, H. K.; Lee, J.; Lee, J. H.; Song, J. H.; Choi, J.-Y.; Lee, H. S.

2006-04-01

239

Structural, magnetic and transport properties of NiFe ?Ag( 1-?) heterogeneous alloys  

NASA Astrophysics Data System (ADS)

We carried out a comprehensive study of structural, magnetic and electrotransport properties of as-deposited and annealed (Ni 80Fe 20) ?Ag( 1-?) heterogenous alloys prepared by sputtering. The NiFe atomic concentration was varied between 15% and 40%. These alloys consist of small magnetic particles (Ni 80Fe 20) embedded in a nonmagnetic matrix (Ag). The structures of these alloys were investigated by X-ray diffraction, scanning electron microscopy and high-resolution cross-section transmission electron microscopy. The magnetic measurements were made using SQUID magnetometry and ferromagnetic resonance. Magnetoresistance was measured with a conventional four-point probe between 1.5 K and room temperature in field range 0-6T. Three contributions to the magnetoresistance of these granular alloys have been clearly identified: the spin-valve (or giant) magnetoresistance as in multilayers, scattering on magnetic fluctuations (as in any ferromagnetic metal around its magnetic ordering temperature), and anisotropic magnetoresistance. These three contributions have their own dependences on the size of the magnetic particles, on the degree of intermixing between Ni 80Fe 20 and Ag, and on temperature. We discuss the different shapes and amplitudes of magnetoresistance versus Ni 80Fe 20 concentration or temperature and their evolution upon annealing in terms of the relative roles of these three contributions. The magnetoresistance in multilayers (current in-plane or perpendicular to the plane) and granular alloys are also compared.

Dieny, B.; Teixeira, S. R.; Rodmacq, B.; Cowache, C.; Auffret, S.; Redon, O.; Pierre, J.

1994-02-01

240

Orbital Degeneracy Removed by Charge Order in Triangular Antiferromagnet AgNiO2  

NASA Astrophysics Data System (ADS)

We report a high-resolution neutron diffraction study on the orbitally degenerate spin-1/2 hexagonal metallic antiferromagnet AgNiO2. A structural transition to a tripled unit cell with expanded and contracted NiO6 octahedra indicates 33 charge order on the Ni triangular lattice. This suggests charge order as a possible mechanism of lifting the orbital degeneracy in the presence of charge fluctuations, as an alternative to the more usual Jahn-Teller distortions. A novel magnetic ground state is observed at low temperatures with the electron-rich S=1 Ni sites arranged in alternating ferromagnetic rows on a triangular lattice, surrounded by a honeycomb network of nonmagnetic and metallic Ni ions. We also report first-principles band-structure calculations that explain microscopically the origin of these phenomena.

Wawrzy?ska, E.; Coldea, R.; Wheeler, E. M.; Mazin, I. I.; Johannes, M. D.; Srgel, T.; Jansen, M.; Ibberson, R. M.; Radaelli, P. G.

2007-10-01

241

Effect of transition metals on the interfacial reactions in electroless Ni(P)solder interconnections  

Microsoft Academic Search

The effect of transition metal (TM) additive of Ni, Co or Zn on the interfacial reactions of the solder joints between Sn-Ag-Cu (SAC) solder and the Cu\\/Ni(P)\\/Au substrate was investigated, especially when subsequent to multi-reflowing. (Cu,Ni)6Sn5 formed at the interface of all the joints but the SAC-Ni of which the interfacial compound was (Ni,Cu)6Sn5. The interfacial compounds of the SAC-Co

Yao-Ren Liu; Jenn-Ming Song I; Yi-Shao Lai; Ying-Ta Chiu; Wei-Ting Chen

2008-01-01

242

Martensitic transformation behavior in TiNiX (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys  

SciTech Connect

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 TiNiX (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 TiNi matrices and second phase particles. Ag, In and Sn were soluble in TiNi 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 Ti48.8Ni1.2Ag, Ti49.0Ni1.0In and Ti49.0Ni1.0Sn alloys, while one-stage B2-B19? transformation occurred in Ti49.0Ni1.0Ag, Ti49.0Ni1.0Sb, Ti49.0Ni1.0Te, Ti49.0Ni1.0Pb and Ti49.0Ni1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19? transformation (Hv 250368) was much larger than that (NiX (X = non-transition elements) alloys.

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

243

Thermal cycling aging effects on SnAgCu solder joint microstructure, IMC and strength  

Microsoft Academic Search

Thermal cycling aging studies on a lead-free 95.5Sn3.8Ag0.7Cu solder joint were investigated. Soldered lap joint specimens were fabricated by a solder reflow process using a 95.5Sn3.8Ag0.7Cu solder sphere, no-clean flux on FR4 substrate parts. Characterization of the solder joint microstructure, intermetallic compound (IMC) and shear strength was conducted. Studies on the effects of thermal aging on IMC thickness and residual

John H. L. Pang; T. H. Low; B. S. Xiong; Xu Luhua; C. C. Neo

2004-01-01

244

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

245

Fabrication and photocatalytic activities in visible and UV light regions of Ag@TiO2 and NiAg@TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Completely discrete Ag@TiO2 and NiAg@TiO2 nanoparticles were prepared by the hydrazine reduction of Ag+/Ni2+ ions and the subsequent sol-gel coating of TiO2 in an aqueous solution of CTAB. TEM analysis revealed that their core diameters were 6.55 1.20 and 7.57 1.33 nm, respectively, and their shell thicknesses were 2.59 and 2.80 nm, respectively. By the analyses of EDX, UV-vis absorption spectra, FTIR spectra, and zeta potential, their core-shell structure, crystal structure, optical properties, and surface state were demonstrated. In addition to exhibiting significant absorption in the visible light region, it was noted that they had lower zeta potentials than TiO2 nanoparticles, which favored the adsorption of positively charged organic compounds on the particle surface and thereby increased the photocatalytic reaction rate. By measuring the photocatalytic degradation rate of rhodamine B, Ag@TiO2 and NiAg@TiO2 nanoparticles were demonstrated to possess significantly higher photocatalytic activities than TiO2 nanoparticles in the visible light region because of the formation of Schottky barrier banding at the core-shell interface as well as the excitation of photogenerated electrons from the surface of Ag or NiAg cores to the conduction band of TiO2 shells. Although NiAg@TiO2 nanoparticles had lower photocatalytic activity than Ag@TiO2 nanoparticles owing to weaker surface plasmon resonance, they could be recovered magnetically from the treated solutions. Under UV light illumination, the photocatalytic activities of Ag@TiO2 and NiAg@TiO2 nanoparticles were lower than that of TiO2 nanoparticles because of the lower TiO2 content and the transfer of photogenerated electrons from TiO2 shells to Ag or NiAg cores, which also acted as the new recombination centers of photoinduced electrons and holes and hence led to a decrease in the photocatalytic activity.

Chuang, Haw-Yeu; Chen, Dong-Hwang

2009-03-01

246

Magnetic behavior of 3d impurities in Cu, Ag, and Au: First-principles calculations of orbital moments  

Microsoft Academic Search

We perform first-principles calculations to investigate the behavior of orbital moments (OM's) of 3d impurities in Cu, Ag, and Au. Previous calculations for Fe impurities in Ag and Au indicate that in Ag, where the d band is located at lower energies, the Fe impurity has a significant OM, while in Au, where the shallower d band hybridizes strongly with

S. Frota-Pessa

2004-01-01

247

Glass Forming Ability in Pr-(Cu, Ni)-Al Alloys  

E-print Network

Glass forming ability (GFA) in the Pr-rich Pr-(Cu, Ni)-Al alloys at or near the eutectic points was systematically studied. It was found that the GFA in the pseudo-ternary alloys of Pr-(Cu, Ni)-Al is higher than that of ...

Zhang, Yong

248

Fundamental studies of high-temperature corrosion reactions. Sixth annual progress report. [Cu-6% Ni  

SciTech Connect

Research was conducted on the sulfidation of pure Mo by sulfur gases at 700 to 950/sup 0/C and on the in-situ oxidation of metals and alloys in the hot-stage SEM. Results on the in-situ oxidation of Cu, Ni, Fe, and Cu-6% Ni up to 930/sup 0/C are reported in detail. 21 figures.

Rapp, R.A.

1981-02-01

249

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

PubMed

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

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

2013-12-01

250

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

Microsoft Academic Search

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

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

1997-01-01

251

Magnetic Cu-Ni (core-shell) nanoparticles in a one-pot reaction under microwave irradiation.  

PubMed

We successfully prepared face-centered cubic (fcc) Cu-Ni (core-shell) nanoparticles by intramolecular reduction of formate complexes of Cu(2+) and Ni(2+) with long-chain amine ligands in a one-pot reaction within an extremely short time realized only under microwave irradiation. Observation by an HAADF-STEM technique showed that the nanostructure in one particle consisted of a Ni-rich shell and a Cu-rich core. Cu(4)Ni(6) nanoparticles with an average size of 11.7 nm were comprised of a Cu core with a diameter of ca. 6.0 nm, a Ni shell ca. 1.6 nm thick and a 0.9 nm thick interlayer of mixed Cu-Ni alloy between the Cu core and the Ni shell. Both the oxidation characteristics and the magnetic properties were dramatically affected by the molar ratios of Cu : Ni in the Cu-Ni nanoparticles. The magnetization of Cu(3)Ni(7) and Cu(4)Ni(6) comprised of a diamagnetic Cu-rich core, ferromagnetic Ni-rich shell and antiferromagnetic NiO-rich layer on the particle surface showed an exchange bias (209 and 143 Oe, respectively). PMID:20644753

Yamauchi, Tomohisa; Tsukahara, Yasunori; Sakata, Takao; Mori, Hirotaro; Yanagida, Takeshi; Kawai, Tomoji; Wada, Yuji

2010-04-01

252

Interfacial reaction of Pb-Sn solder and SnAg solder with electroless Ni deposit during reflow  

Microsoft Academic Search

The interfaces between electroless Ni-P deposit and Pb-Sn solder and Sn-Ag solder were formed by reflowing for different time\\u000a periods to examine their microstructures and microchemistry. It was found that the Pb-Sn solder interface is more stable than\\u000a the Sn-Ag solder interface. Sn-Ag solder reacts quickly with the electroless Ni-P deposit and forms nonadherent Ni-Sn intermetallic\\u000a compounds (IMCs). Pb-Sn solder

M. O. Alam; Y. C. Chan; K. C. Hung

2002-01-01

253

Magnetic properties of NiCuZn ferrites with addition of tungsten trioxide  

NASA Astrophysics Data System (ADS)

The effect of WO 3 addition on the properties of NiCuZn ferrite, (Ni 0.2Cu 0.2Zn 0.6O) 1.02(Fe 2O 3) 0.98, has been investigated in this study. The enhanced electrical and magnetic properties obtained from WO 3 addition into NiCuZn ferrites were also shown in this study. Q-factor at 10 MHz of NiCuZn ferrites increased at higher electrical resistivity, but no significant change in initial permeability. The resonance frequency of those NiCuZn ferrites was shifted to a higher range, which means relaxation time was also decreased over 0.6 wt% of WO 3 content.

Park, Kwang-Soo; Nam, Joong-Hee; Oh, Jae-Hee

2001-05-01

254

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

Microsoft Academic Search

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

S. Takcs; F. Trknyi; M. Sonck; A. Hermanne

2002-01-01

255

High-permeability and high-Curie temperature NiCuZn ferrite  

NASA Astrophysics Data System (ADS)

High-permeability and high-Curie temperature NiCuZn ferrite was developed for use in telecommunication. In the development process, attention was focused on the amount of CuO contained in NiZn ferrite and a small additive of MoO 3 added in the NiCuZn ferrite. It was confirmed that the initial permeability of the core increased and the Curie temperature only decreased a little with 4 mol% CuO content. This was mainly attributed to the presence of Cu ions activating the sintering processes in ferrites and leading to increase in density; the decrease of magnetocrystalline anisotropy constant also does some contribution. By optimizing the MoO 3 additive, the initial permeability could get a sharp increase because of enhancement of grain size. As a result, we were able to develop the NiCuZn ferrite with a permeability of 2480 and Curie temperature of around 118 C.

Su, Hua; Zhang, Huaiwu; Tang, Xiaoli; Xiang, Xinyuan

2004-12-01

256

The microstructure of eutectic Au-Sn solder bumps on Cu\\/electroless Ni\\/Au  

Microsoft Academic Search

In this work we studied the initial microstructure and microstructural evolution of eutectic Au-Sn solder bumps on Cu\\/electroless Ni\\/Au. The solder bumps were 150 160 m in diameter and 45 50 m tall, reflowed on Cu\\/electroless Ni\\/Au, and then aged at 200C for up to 365 days. In addition, Au-Ni-Sn-alloys were made and analyzed to help identify the phases that

H. G. Song; J. P. Ahn; J. W. Morris

2001-01-01

257

Perpendicular magnetization and exchange bias in epitaxial Cu\\/Ni\\/ Fe50 Mn50 thin films  

Microsoft Academic Search

The perpendicular magnetic anisotropy has been achieved in epitaxial Cu\\/Ni thin films deposited by magnetron sputtering. A thin Fe50Mn50 layer deposited on top of the Ni layer induces perpendicular exchange bias arising from the interface exchange coupling. The hysteresis loops, the ferromagnetic thickness dependence, and the angular dependence of the exchange bias in as-deposited and field-cooled Cu\\/Ni\\/Fe50Mn50 trilayer thin films

Haiwen Xi; T. F. Ambrose; T. J. Klemmer; R. van de Veerdonk; J. K. Howard; Robert M. White

2005-01-01

258

Characterization of Ni 63Cu 9Fe 8P 20 glass forming alloy  

Microsoft Academic Search

Quaternary Ni63Cu9Fe8P20 alloy was prepared using 99.95wt% Ni, 99.95wt% Cu, 99.95wt% Fe and NiP master alloy. The precursors were induction melted in quartz tubes under vacuum (10?2bar). The microstructure of the alloy was investigated by the use of a light microscope, scanning electron microscope (SEM) with energy dispersive spectroscope (EDS). Analysis of morphology was carried out and volume fraction of

Krzysztof Ziewiec

2005-01-01

259

Drop reliability study of PBGA assemblies with SAC305, SAC105 and SAC105Ni solder ball on Cu-OSP and ENIG surface finish  

Microsoft Academic Search

Lead free SnAgCu solder joints used in surface mount packages like Ball Grid Array (BGA) have a great impact on the reliability of the end product. The mechanical properties of the solder are important factors. By changing the concentration of silver and copper, or by doping a very low portion of the fourth element (e.g. Ni), the strength of solder

W. H. Zhu; Luhua Xu; John HL Pang; X. R. Zhang; Edith Poh; Y. F. Sun; Anthony Y. S. Sun; C. K. Wang; H. B. Tan

2008-01-01

260

Near-Monodisperse Ni-Cu Bimetallic Nanocrystals of Variable Composition: Controlled Synthesis and Catalytic Activity for H2 Generation  

E-print Network

Near-Monodisperse Ni-Cu Bimetallic Nanocrystals of Variable Composition: Controlled Synthesis monodisperse and compositionally homogeneous NCs. Ni-Cu alloys are efficient catalysts for some important to prepare Ni-Cu nanocrystalline particles.4 However, the synthesis of mono- disperse, faceted, and phase

Yang, Peidong

261

Cd, Cr, Cu, Ni and Pb in the water column and sediments of the Ob-Irtysh Rivers, Russia  

Microsoft Academic Search

Concentrations of Cd, Cr, Cu, Ni and Pb were determined in filtered water, suspended particulate matter, and bottom sediments from a ?2000 km section of the Ob and Irtysh Rivers. Dissolved Cd, Cr, Cu and Ni concentrations are similar to, or higher than, results from other Russian Arctic and large world river-estuaries. Concentrations of Cd, Cr, Cu, Ni and Pb

Wendy L. Woods

1997-01-01

262

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

Microsoft Academic Search

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 4151 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

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

1996-01-01

263

Amorphization and thermal stability of Cu 68.5Ni 12P 19.5 alloy  

Microsoft Academic Search

Three-component Cu68.5Ni12P19.5 alloy was prepared using 99.95wt.% Cu, CuP and NiP master alloys. The precursors were encapsulated in quartz tubes under vacuum (10?2bar) and melted in a resistance furnace. The microstructure of the alloy was investigated using a light microscope and a scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS). An analysis of the morphology was carried out and

Krzysztof Ziewiec; Piotr Olszewski; Ryszard Gajerski; Jakub Michalski; Katarzyna Konopka

2004-01-01

264

Potential energy curves for the ground and low-lying excited states of CuAg  

NASA Astrophysics Data System (ADS)

The ground and low-lying excited states of heteronuclear diatomic CuAg are examined by multi-reference configuration interaction (MRCI) method. Relativistic effects were treated and probed in two steps. Scalar terms were considered using the spin-free DKH Hamiltonian as a priori and spin-orbit coupling was calculated perturbatively via the spin-orbit terms of the Breit-Pauli Hamiltonian based on MRCI wavefunctions. Potential energy curves of the spin-free states and their corresponding ? components correlating with the separated atom limits 2S(Cu) + 2S(Ag) and 2D(Cu) + 2S(Ag) are obtained. The results are in fine agreement with the experimental measurements and tentative conclusions for the ion-pair B0+ state are confirmed by our theoretical calculations. Illustrative results are presented to reveal the relative importance and magnitude of the scalar and spin-orbit effects on the spectroscopic properties of this molecule. Time dependent density functional theory calculations, using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for CuAg and the accuracy of TD-DFT has been compared with ab initio results.

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-01

265

Kerr rotation in Cu, Ag, and Au driven by spin accumulation and spin-orbit coupling  

E-print Network

FM/NM structure of sapphire substrate/ Pt (20)/ FM (6)/ NM (h) (unit in nm). The FM is a [Co prepared samples (sapphire/ Pt (100), sapphire/ Pt (2)/ [Co (0.4)/ Pt (1)]15/ Pt (1), sapphire/ Cu (100), sapphire/ Ag (100), and sapphire/ Au (100)) and are

Cahill, David G.

266

Cyclic fluid infiltration in structurally controlled AgPbCu occurrences (Schladming, Eastern Alps)  

E-print Network

Cyclic fluid infiltration in structurally controlled Ag­Pb­Cu occurrences (Schladming, Eastern Alps to the center. These observations are best interpreted by an external acidic fluid infiltrating these structures complexes became unstable as a result of fluid neutralisation. The origin of this carbonate is linked

Fritz, Harald

267

Effect of silver content and nickel dopant on mechanical properties of Sn-Ag-based solders  

Microsoft Academic Search

In this work, five solder materials of Sn-3.0Ag-0.5Cu (SAC305), Sn-2.0Ag-0.5Cu (SAC205), Sn-1.0Ag-0.5Cu (SAC105), Sn-1.0Ag-0.5Cu-0.05Ni (SAC105Ni0.05) and Sn-1.0Ag-0.5Cu-0.02Ni (SAC105M0.02) were tested using tensile loading at room temperature to investigate the Ag content and Ni dopant effect on solder mechanical properties, respectively. In addition, different testing temperature conditions including -35 deg.C, 25 deg.C, 75 deg.C and 125 deg.C were used for SAC105M0.02

F. X. Che; J. E. Luan; X. Baraton

2008-01-01

268

Cryogenic treatment induced hardening of Cu45Zr45Ag7Al3 bulk metallic glass  

NASA Astrophysics Data System (ADS)

Little is known about the mechanical properties of bulk metallic glassy alloys (BMGs) after cryogenic treatment (CT). Cu45Zr45Ag7Al3 BMGs were treated in cryogenic temperatures for four chosen holding times. Compared with the as-cast sample, the compressive fracture strength of this BMG increased with increasing CT time. Furthermore, the CT changes the fracture mode from the ductile to the brittle. And CT brought about the precipitation of the AlCu2Zr and Cu5Zr phases which were accompanying with the morphology modification and contributed to the mechanical properties improvement of this BMG.

Zhang, L. K.; Chen, Z. H.; Chen, D.; Zheng, Q.

2014-01-01

269

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

PubMed

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

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

2014-05-21

270

Surface modification processes during methane decomposition on Cu-promoted NiZrO2 catalysts  

PubMed Central

The surface chemistry of methane on NiZrO2 and bimetallic CuNiZrO2 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.

Wolfbeisser, Astrid; Kltzer, Bernhard; Mayr, Lukas; Rameshan, Raffael; Zemlyanov, Dmitry; Bernardi, Johannes; Rupprechter, Gnther

2015-01-01

271

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

SciTech Connect

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.

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

272

Resistive switching behavior in a Ni-Ag2Se-Ni nanowire  

NASA Astrophysics Data System (ADS)

Hysteretic resistive switching behavior in a silver selenide (Ag2Se) nanowire, which had a diameter of about 200 nm and a length of about 10 ?m, was studied using scanning probe microscopy. Electrical current measurements were carried out in a range from 0 to -10 V and in temperatures below and above the phase transition of Ag2Se. ON/OFF switching times were measured with pulsed voltages. They displayed different characteristics at low and high temperatures. The results confirm that Ag2Se nanowires have applications in nanoscale switching devices.

Lee, N. J.; An, B. H.; Koo, A. Y.; Ji, H. M.; Cho, J. W.; Choi, Y. J.; Kim, Y. K.; Kang, C. J.

2011-03-01

273

The early stage dissolution of Ni and the nucleation of Ni-Sn intermetallic compound at the interface during the soldering of Sn3.5Ag on a Ni substrate  

Microsoft Academic Search

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

Yu-Wei Lin; Kwang-Lung Lin

2010-01-01

274

Stress sensitivity of inductance in NiCuZn ferrites  

NASA Astrophysics Data System (ADS)

Iron rich, stoichiometric iron and iron deficient samples of NiCuZn ferrite were prepared by conventional ceramic double sintering process. The formation of single phase was confirmed by X-ray diffraction. Initial permeability measurements on these samples were carried out in the temperature range of 30-400 C. The effect of external applied stress on the open magnetic circuit type coil with these ferrites was studied by applying uniaxial compressive stress parallel to the magnetising direction and the change in the inductance was measured. These studies show that stress sensitivity is more in the case of iron rich and stoichiometric iron samples while in the case of iron deficient samples the stress sensitivity was found to be less.

Ramamanohar Reddy, N.; Venkata Ramana, M.; Rajitha, G.; Rajagopal, E.; Sivakumar, K. V.; Murthy, V. R. K.

2005-04-01

275

Electronic structure of benzene adsorbed on Ni and Cu surfaces  

SciTech Connect

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

Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

1997-04-01

276

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

PubMed

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

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

2014-05-15

277

Phase equilibria in the system AgNiSn: Thermal behavior  

Microsoft Academic Search

The phase equilibria in the ternary AgNiSn system, which has high relevance in lead-free soldering, were investigated by means of thermoanalytical methods. Together with the results of an earlier investigation by X-ray powder diffraction and electron probe microanalysis (Schmetterer et al., J Electron Mater, 2007), a complete and consistent ternary phase diagram was derived. Nine isopleths, a full liquidus projection

Clemens Schmetterer; Hans Flandorfer; Herbert Ipser

2008-01-01

278

Phase formation in the Ag 2 MoO 4 -CuO-MoO 3 system and the crystal structure of the new double molybdate Ag 2 Cu 2 (MoO 4 ) 3  

Microsoft Academic Search

Subsolidus phase relations in the Ag2MoO4-CuO-MoO3 oxide-salt ternary system were determined. T-x diagram was plotted for the Ag2MoO4-CuMoO4 quasi-binary join. Double molybdate Ag2Cu2(MoO4)3 was found to exist on this join. This compound is a superstructure derived from orthorhombic Li3Fe(MoO4)3. Its structure was solved in terms of a subcell (a = 5.0749(3), b = 11.300(2), c = 18.127(3) , space group

G. D. Tsyrenova; S. F. Solodovnikov; E. T. Pavlova; E. G. Khaikina; Z. A. Solodovnikova

2009-01-01

279

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

PubMed

The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. In particular, graphene prevents the formation of any oxide on the protected metal surfaces, thus allowing pure metal surfaces only one atom away from reactive environments. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 C in air for up to 4 h. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth. PMID:21275384

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

2011-02-22

280

The effect of Mn substitution on the properties of NiCuZn ferrites  

NASA Astrophysics Data System (ADS)

The properties of Mn-substituted NiCuZn ferrites, (Ni0.2Cu0.2Zn0.6O)1.03(Fe2-xMnxO3)0.97 and (Ni0.2-xMnxCu0.2Zn0.6O)1.03(Fe2O3)0.97 sintered at a low temperature, were investigated in this study. When Mn was substituted for Fe ranging from 0 to 0.04 and for Ni ranging from 0 to 0.01, initial permeability and bulk density increased within these substitution ranges. At the same time, these two NiCuZn ferrites have the larger grain size. In these two compositions, resistivity was decreased with Mn content but coercivity tended to vary sensitively with increasing Mn content.

Nam, J.-H.; Hur, W.-G.; Oh, J.-H.

1997-04-01

281

Biopsy applications of Ti50Ni41Cu9 shape memory films for wireless capsule endoscope  

NASA Astrophysics Data System (ADS)

Wireless capsule endoscopy (WCE) is a new technology to evaluate the patient with obscure gastrointestinal bleeding. However, there is still some deficiency existing in the current WCE, for example, lack of ability to biopsy and precisely locate the pathology. This study aimed to prepare and characterize TiNiCu shape memory alloy thin films for developing microgripper for biopsy (tissue sampling and tagging) applications. Ti50Ni41Cu9 thin films were prepared by co-sputtering of TiNi and Cu targets, and their transformation temperatures were slightly above that of human body. Results from differential scanning calorimetry, in-situ X-ray diffraction, curvature and electrical resistance measurement revealed clearly martensitic transformation of the deposited TiNiCu films upon heating and cooling. The biocompatibility of the TiNiCu films in the simulated gastric and intestinal solutions was also studied. Results showed the release of Ni and Cu ions is much less than the toxic level and the film did not lose shape memory effect even after 10-day immersion in the simulated solutions. TiNiCu/Si micro-cantilevers with and without electrodes were fabricated using the conventional micromachining methods and apparent shape memory effect upon heating and cooling was demonstrated.

Du, Hejun; Fu, Yongqing; Zhang, S.; Luo, Jack K.; Flewitt, Andrew J.; Milne, William I.

2004-02-01

282

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

Microsoft Academic Search

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

S. W. Ip; J. M. Toguri

1993-01-01

283

Studies on Structural and Electrical Properties of Ball-Milled NiCuZn-MgCuZn Nanocomposites Ferrites  

NASA Astrophysics Data System (ADS)

Multilayer chip inductors (MLCIs) have been rapidly developed for electromagnetic applications. NiCuZn ferrites are the most preferred ferrite materials to produce MLCIs, and MgCuZn ferrites have similar electromagnetic properties to those of NiCuZn ferrites. In view of this, ferrite composites with ferromagnetic phase (X) Ni0.35Cu0.05 Zn0.6Fe2O4 + (1 - X) Mg0.25Cu0.25Zn0.5Fe2O4, in which X varies from 0.0 to 1.0, were prepared by the conventional ceramic double-sintering process. The sintered ferrite was characterized for direct current (DC) and alternating current (AC) electrical conductivities, and thermoelectric effect studies. The X-ray diffraction pattern confirms the formation of single-phase spinel structure; the grain size was estimated using an scanning electron micrograph (SEM). The electrical properties were studied as a function of temperature and composition. The temperature variations of these samples were carried out from 303 K to 523 K (30 C to 250 C) within the frequency range 100 Hz to 1 MHz. The sintered NiCuZn-MgCuZn ferrites prepared possess good electromagnetic properties and good structure, thus making them suitable materials for MLCIs due to its high resistivity.

Varalaxmi, N.; Sivakumar, K. V.

2013-10-01

284

The microstructure of eutectic Au-Sn solder bumps on Cu\\/electroless Ni\\/Au  

Microsoft Academic Search

In this work we studied the initial microstructure and microstructural evolution of eutectic Au-Sn solder bumps on Cu\\/electroless\\u000a Ni\\/Au. The solder bumps were 150160 m in diameter and 4550 m tall, reflowed on Cu\\/electroless Ni\\/Au, and then aged at 200C\\u000a for up to 365 days. In addition, Au-Ni-Sn-alloys were made and analyzed to help identify the phases that appear at

H. G. Song; J. P. Ahn

2001-01-01

285

Hall effect in Zr-Ni and Zr-Cu metallic glasses doped with hydrogen  

NASA Astrophysics Data System (ADS)

We have studied the effect of hydrogen doping on the Hall resistivity of paramagnetic Zr76Ni24, Zr40Ni60, Zr70Cu30, and Zr60Cu40 metallic glasses. All the alloys have positive Hall coefficients except the Zr40Ni60. The hydrogen dopant increases the absolute value of the Hall coefficient irrespective of its sign, except in the case of (Zr70Cu30)1-xHx, where the Hall coefficient decreases for low hydrogen concentrations (x<0.04) and increases at higher ones, while staying positive all the time. The results are explained as being due to the enhanced s-d hybridization.

Kokanovi?, I.; Leonti?, B.; Lukatela, J.; Ivkov, J.

1990-12-01

286

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

NASA Astrophysics Data System (ADS)

The structural evolution of Ti50Cu43Ni7 and Ti55Cu35Ni10 metallic glasses during heating was investigated by in-situ synchrotron X-ray diffraction. The width of the most intense diffraction maximum of the glassy phase decreases slightly during relaxation below the glass transition temperature. Significant structural changes only occur above the glass transition manifesting in a change in the respective peak positions. At even higher temperatures, nanocrystals of the shape memory B2-Ti(Cu,Ni) phase precipitate, and their small size hampers the occurrence of a martensitic transformation.

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

2015-01-01

287

Crystallographic and magnetic properties of Cu2X, Co2X, and Ni2X hexaferrites  

Microsoft Academic Search

We have investigated the synthesis conditions and the magnetic properties of X-type hexagonal ferrites. It is found that Ba2Cu2Fe28O46 (Cu2X), Ba2Co2Fe28O46 (Co2X), and Ba2Ni2Fe28O46 (Ni2X) ferrites can be synthesized at a sintering temperature of 1250 C. The x-ray diffraction patterns for Cu2X, Co2X, and Ni2X samples are in good agreement with the pattern calculated from the atomic coordinates for Ba2Fe30O46

Kenji Kamishima; Nobuyuki Hosaka; Koichi Kakizaki; Nobuyuki Hiratsuka

2011-01-01

288

Facile synthesis of bimetallic Cu-Ag nanoparticles under microwave irradiation and their oxidation resistance  

NASA Astrophysics Data System (ADS)

Air-stable bimetallic Cu-Ag nanoparticles in the range of 12-30 nm have been synthesized at gram scale by a facile alcohol reduction in the absence of surfactants with the assistance of microwave irradiation. The synthesized nanoparticles were analyzed by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning TEM, ultraviolet-visible spectroscopy, x-ray photoelectron spectroscopy and thermogravimetry (TG). The stability of the bimetallic nanoparticles against oxidation was examined by TG and in situ temperature-programmed XRD analyses in the atmosphere. No oxidation of copper was confirmed by XRD after storing for longer than 6 months in the atmosphere at room temperature. No oxidation took place below 118? C and the Cu(200) diffraction peak decreased by only 7% after heating at 100? C for 30 min. The oxidation resistance has been ascribed to a Cu core-Ag shell structure, probably owing to the suppressive effect of Ag on the surface through the electronic interaction with Cu and a physical barrier of oxygen.

Chen, Zhi; Mochizuki, Dai; Maitani, Masato M.; Wada, Yuji

2013-07-01

289

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)

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.

Lin, Yu-Wei; Lin, Kwang-Lung

2010-09-01

290

Agglomeration in core-shell structure of CuAg nanoparticles synthesized by the laser ablation of Cu target in aqueous solutions  

NASA Astrophysics Data System (ADS)

Metallic copper Cu and bimetallic coppersilver CuAg nanoparticles (NPs) are generated by the ablation of copper bulk target in water and aqueous Ag colloidal solution, respectively. The experiments were performed using nanosecond Nd:YAG laser operating at 1064 nm. The generated NPs are characterized by UVvis absorption spectroscopy, laser-induced breakdown spectroscopy, dynamic light scattering and scanning electron microscopy. The conducted investigations can be summarized as follows: (i) CuAg NPs colloidal solution possess the absorption in UVvis spectral region, which can be attributed to the Cu-component; (ii) the primary bimetallic CuAg NPs have near uniform dimensions with diameter of about 15 nm, and as a rule, they are grouped into larger agglomerates without defined morphology; (iii) the obtained Cu NPs have mainly spherical form with average diameters up to 20 nm. Both types of NPs show a tendency towards the formation of large agglomerates with different morphology. Bimetallic NPs show the plasmon resonance in the vicinity of 640 nm with a good coincidence with formation of the colloidal solution of pure Cu NPs. The results also demonstrate that the coreshell structure (Ag-rich core/Cu-rich shell) is important for the formation of the bimetallic NPs, also agreeing very well with theory.

Petrovi?, S.; Salati?, B.; Milovanovi?, D.; Lazovi?, V.; ivkovi?, Lj; Trtica, M.; Jelenkovi?, B.

2015-02-01

291

Wetting interactions between the Ni-Cu-P deposit and In-Sn solders  

Microsoft Academic Search

The interactions during wetting between an electroless Ni-Cu-P deposit and molten InSn solders were investigated with the aid of scanning electron microscope (SEM), X-ray diffractometer (XRD), and Auger electron spectroscope (AES). The intermetallics In3Ni 2 and In27Ni10 were formed at the interlayer for the Ni-Cu-P with 51In-49Sn and 80In-20Sn systems, in the temperature range of 250-300C. In addition to these

Chun-Jen Chen; Kwang-Lung Lin

1997-01-01

292

First principles study of magnetic properties of Co1ML/Ni2ML/Cu(111) multilayer structure  

NASA Astrophysics Data System (ADS)

We carry out first principles calculations to study the magnetic properties of a multilayer structure consisting of one monolayer (ML) of Co (Co1ML) on top of two ML of Ni (Ni2ML) deposited on top of Cu(111), i.e., Co1ML/Ni2ML/Cu(111). We found that the magnetic anisotropy of the Co1ML/Ni2ML multilayer does not change much with variation in the in-plane and inter-layer structures of the Co/Ni multilayer. On the other hand, interaction with the Cu(111) plays an important role. As a result of the electron transfer from the Cu(111) substrate to the first deposited Ni-layer, i.e., Ni(1), there is a reduction in the magnetic moment of Ni(1) and an increase in the magnetic crystalline anisotropy energy of Co1ML/Ni2ML/Cu(111) multilayer structure.

Kojima, Kazuki; Dio, Wilson Agerico; Koshikawa, Takanori; Kasai, Hideaki

2015-04-01

293

Corrosion of Cu-Ni alloys in sulfide-polluted seawater  

SciTech Connect

A study of the corrosion of copper-nickel (Cu-Ni) alloys showed hydrodynamic conditions increased the corrosion rate (I[sub corr]) significantly by reducing the sulfide concentration polarization. Pre-exposure to oxidation products of dissolved sulfide and elemental sulfur (S) increased I[sub corr] of the alloys in seawater significantly. Pre-exposure to nitrite and chromate decreased I[sub corr] by almost 2 orders of magnitude for alloys of 90% Cu-10% Ni and 70% Cu-30% Ni. However, cyclic polarization curves for both alloys pre-exposed to chromate and nitrite showed the passivators caused severe localized corrosion for the 70% Cu-30% Ni alloy only by transition from the active to passive state. The corrosion mechanism of the 90% Cu-10% Ni alloy differed from that of the 70% Cu-30% Ni alloy in quiescent sulfide-polluted seawater. A four-part corrosion mechanism was proposed. The rate of sulfide ion diffusion to the alloy-solution interface always was the rate determining step for corrosion of the alloy of higher Ni content, whereas different kinetics of the reaction determined I[sub corr] of the second alloy.

Al-Hajji, J.N. (Kuwait Univ., Safat (Kuwait). Mechanical Engineering Dept.); Reda, M.R. (Kuwait Univ., Safat (Kuwait). Chemical Engineering Dept.)

1993-10-01

294

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

SciTech Connect

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

Nieman, G.W.; Weertman, J.R. (Northwestern Univ., Evanston, IL (USA). Dept. of Materials Science and Engineering); Siegel, R.W. (Argonne National Lab., IL (USA))

1990-12-01

295

Nanocatalyst superior to Pt for oxygen reduction reactions: the case of core/shell Ag(Au)/CuPd nanoparticles.  

PubMed

Controlling the electronic structure and surface strain of a nanoparticle catalyst has become an important strategy to tune and to optimize its catalytic efficiency for a chemical reaction. Using density functional theory (DFT) calculations, we predicted that core/shell M/CuPd (M = Ag, Au) NPs with a 0.8 or 1.2 nm CuPd2 shell have similar but optimal surface strain and composition and may surpass Pt in catalyzing oxygen reduction reactions. We synthesized monodisperse M/CuPd NPs by the coreduction of palladium acetylacetonate and copper acetylacetonate in the presence of Ag (or Au) nanoparticles with controlled shell thicknesses of 0.4, 0.75, and 1.1 nm and CuPd compositions and evaluated their catalysis for the oxygen reduction reaction in 0.1 M KOH solution. As predicted, our Ag/Cu37Pd63 and Au/Cu40Pd60 catalysts with 0.75 and 1.1 nm shells were more efficient catalysts than the commercial Pt catalyst (Fuel Cells Store), with their mass activity reaching 0.20 A/mg of noble metal at -0.1 V vs Ag/AgCl (4 M KCl); this was over 3 times higher than that (0.06 A/mg Pt) from the commercial Pt. These Ag(Au)/CuPd nanoparticles are promising non-Pt catalysts for oxygen reduction reactions. PMID:25279704

Guo, Shaojun; Zhang, Xu; Zhu, Wenlei; He, Kai; Su, Dong; Mendoza-Garcia, Adriana; Ho, Sally Fae; Lu, Gang; Sun, Shouheng

2014-10-22

296

Ligand-field theory applied to diatomic transition metals. Results for the dA9dB9?2 states of Ni2, the dNi9dCu10?2 states of NiCu, and the dNi8(3F)dCu10?2?*1 excited states of NiCu  

NASA Astrophysics Data System (ADS)

A ligand-field theory has been developed for transition-metal diatomics having electronic configurations of dA9dB10?2, dA9dB9?2, and dA8(3F)dB10?2?*1. The theory treats each atom as a point charge and includes spin-orbit interactions. No contributions due to d-orbital chemical bonding are included. Since the d orbitals are quite small compared to the bond lengths in these molecules, the only inputs to the theory are the ligand charges (ZA and ZB), the radial expectation values Ni9dCu10?2 manifold of states in NiCu, and on the dA9dB9?2 manifold of states in Ni2. This demonstrates that the ligand-field model has some validity for metal molecules containing nickel, primarily because of the compact nature of the 3d orbitals in this element. Similar calculations of the dA9dB9?2 manifold of states in Pt2 and the dNi9dPt9?2 manifold of states in NiPt are presented for comparison to future ab initio or experimental measurements, although the possibility of d-orbital contributions to the bonding in these species makes the ligand-field model less favorable in these examples. The dNi8(3F)dCu10?2?*1 excited electronic states of NiCu, which are well known from resonant two-photon ionization spectroscopy, are also investigated in the ligand-field model. As a final example, the dNi8(3F)?2?*1 excited electronic states of NiH are also examined using the same treatment as that employed for the dNi8(3F)dCu10?2?*1 excited manifold of NiCu.

Spain, Eileen M.; Morse, Michael D.

1992-10-01

297

Effects of Cu and Ag as ternary and quaternary additions on some physical properties of SnSb7 bearing alloy  

Microsoft Academic Search

The structure, electrical resistivity, and elastic modulus of SnSb7 and SnSb7X (X?=?Cu, Ag, or Cu and Ag) rapidly solidified alloys have been investigated using X-ray diffractometer, double bridge, and dynamic resonance techniques. Copper and silver additions to SnSb result in the formation of a eutectic matrix containing embedded crystals (intermetallic phases) of SnCu, SnAg, and SnSb. The hard crystals SnCu,

Abu Bakr El-Bediwi

2004-01-01

298

Creation of microstructured surfaces using Cu-Ni composite electrodeposition and their application to superhydrophobic surfaces  

NASA Astrophysics Data System (ADS)

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.

Lee, Jae Min; Bae, Kong Myeong; Jung, Kyung Kuk; Jeong, Ji Hwan; Ko, Jong Soo

2014-01-01

299

Spectroscopic observation of photo-induced metastable linkage isomers of coinage metal (Cu, Ag, Au) sulfur dioxide complexes.  

PubMed

Coinage metal atom (Cu, Ag, Au) reactions with SO2 were investigated by matrix isolation infrared absorption spectroscopy and density functional theory electronic structure calculations. Both mononuclear complexes M(?(1)-SO2) (M = Ag, Au) and M(?(2)-O2S) (M = Ag, Cu) were observed during condensation in solid argon or neon. Interestingly, the silver containing mononuclear complexes are interconvertible; that is, visible light induces the isomerization of Ag(?(1)-SO2) to Ag(?(2)-O2S) and vice versa on annealing. However, there is no evidence of similar interconvertibility for the Cu(?(2)-O2S) and Au(?(1)-SO2) molecules. These different behaviors are discussed within the bonding considerations for all of the obtained products. PMID:24382425

Liu, Xing; Wang, Xuefeng; Xu, Bing; Andrews, Lester

2014-02-14

300

Electrodeposited NiFeCu/Cu multilayers: Effect of Fe ion concentration on properties  

NASA Astrophysics Data System (ADS)

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.

Kuru, Hilal; Kockar, Hakan; Alper, Mursel

2015-01-01

301

Characterization of Binary Ag-Cu Ion Mixtures in Zeolites: Their Reduction Products and Stability to Air Oxidation  

SciTech Connect

A series of Ag+-Cu2+ binary mixtures with different Ag/Cu ratios were supported on mordenite with different Si/Al ratios and were subsequently reduced under hydrogen in the temperature range 323K - 473K. Ag and Cu K-edge X-ray Absorption Spectroscopy (XAS) was conducted on these systems in-situ to monitor the reduction species formed and the kinetics of their reduction. In-situ XANES clearly demonstrates that the formation of silver particles is severely impeded by the addition of copper and that the copper is converted from Cu(II) to Cu(I) during reduction and completely reverts back to Cu(II) during cooling. There are no indications at any stage of the formation of bimetallic Ag-Cu clusters. Interestingly, the Ag/Cu ratio appears to have no influence of the reduction kinetics and reduction products formed with only the highest Si/Al ratio (MR = 128) investigated during this study having an influence on the reduction and stability to air oxidation.

Fiddy, Steven [CCLRC Daresbury Laboratory, Daresbury, Warrington, UK, WA4 4AD (United Kingdom); Petranovskii, Vitalii [CCMC-UNAM, Apdo Postal 2681, 22800 Ensenada. B.C., (Mexico); Ogden, Steve [Department of Chemistry, University of Southampton, Southampton (United Kingdom); Iznaga, Inocente Rodriguez [Laboratorio Ingenieria de Zeolitas, Instituto de Materiales y Reactivos (IMRE) - Universidad de la Habana. Zapata y G. s/n. Havana0400 (Cuba)

2007-02-02

302

Impact-Triggered, Conduit-Type Ni-Cu Mineralisation, Norite Belt, Maniitsoq Structure, West Greenland  

NASA Astrophysics Data System (ADS)

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.

Garde, A. A.; Pattison, J.; Kokfelt, T.; McDonald, I.; Secher, K.

2013-09-01

303

High frequency magnetic properties of Bi and Si oxides-doped NiCuZn ferrite  

NASA Astrophysics Data System (ADS)

We developed Bi2O3 and SiO2-doped NiCuZn ferrite for noise-suppression parts or near-field wireless communication parts. Bi and Si reacted selectively by means of sintering at approximately 900 C, which created the Bi4(SiO4)3 phase. It consisted of two-phase structure of NiCuZn ferrite and Bi4(SiO4)3, which was sintered densely while suppressing the grain growth of NiCuZn ferrite. As a result, this ferrite had a high saturation magnetization and showed excellent frequency response. This paper shows, furthermore, that the experimental spin resonance frequency was in good agreement with the theoretical ones, whereby the density of NiCuZn ferrite approached the theoretical bulk density.

Kato, J.; Ono, K.; Matsuo, Y.

2011-10-01

304

Effect of Solute Clusters on Stress Relaxation Behavior in Cu-Ni-P Alloys  

NASA Astrophysics Data System (ADS)

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.

Aruga, Yasuhiro; Saxey, David W.; Marquis, Emmanuelle A.; Shishido, Hisao; Sumino, Yuya; Cerezo, Alfred; Smith, George D. W.

2009-12-01

305

Efficient enhancement of hydrogen production by Ag/Cu2O/ZnO tandem triple-junction photoelectrochemical cell  

NASA Astrophysics Data System (ADS)

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.

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

306

Microstructure, solderability, and growth of intermetallic compounds of Sn-Ag-Cu-RE lead-free solder alloys  

Microsoft Academic Search

The near-eutectic Sn-3.5 wt.% Ag-0.7 wt.% Cu (Sn-3.5Ag-0.7Cu) alloy was doped with rare earth (RE) elements of primarily Ce\\u000a and La of 0.050.25 wt.% to form Sn-3.5Ag-0.7Cu-xRE solder alloys. The aim of this research was to investigate the effect\\u000a of the addition of RE elements on the microstructure and solderability of this alloy. Sn-3.5Ag-0.7Cu-xRE solders were soldered\\u000a on copper coupons.

C. M. T. Law; C. M. L. Wu; D. Q. Yu; L. Wang; J. K. L. Lai

2006-01-01

307

Nonlinear Viscoelastic Characteristics of Sn-Ag-Cu Solder Pastes Used in Electronics Assembly Applications  

NASA Astrophysics Data System (ADS)

Sn-Ag-Cu solder pastes are widely used as the joining material in the electronic assembly process. The aim of this work was to evaluate the nonlinear viscoelastic behaviors of three different Sn-Ag-Cu solder pastes. Three novel rheological test methods were developed for this purpose. These include viscosity, thixotropic loop, and oscillatory amplitude sweep tests. The nonlinear flow curves obtained from the viscosity tests revealed the "shear-thinning" behavior of solder paste samples. Thixotropic loop test results explain the time-dependent structural breakdown and recovery of solder pastes. The viscoelastic properties of solder pastes were interpreted through oscillatory test parameters: storage modulus ( G'), loss modulus ( G?), and phase angle (?). The discrepancies observed in the rheological behaviors of the paste samples were found to be related with flux composition (liquid phase in the solder paste) and particle size distribution.

Mallik, Sabuj; Chan, Erica Hiu Laam; Ekere, Ndy

2013-04-01

308

Creep and Mechanical Properties of Cu6Sn5 and (Cu,Ni)6Sn5 at Elevated Temperatures  

NASA Astrophysics Data System (ADS)

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 25C to 150C. 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.

Mu, Dekui; Huang, Han; McDonald, Stuart D.; Nogita, Kazuhiro

2013-02-01

309

Microstructure-property relationships in Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 2  

NASA Technical Reports Server (NTRS)

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.

Langan, T. J.; Pickens, J. R.

1991-01-01

310

Characterization and optimization of Ni and Cu sorption from aqueous solution by Chlorella vulgaris  

Microsoft Academic Search

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

Surya Kant Mehta; Jai Prakash Gaur

2001-01-01

311

Crossover from in-plane to perpendicular magnetization in ultrathin Ni\\/Cu(001) films  

Microsoft Academic Search

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

B. Schulz; K. Baberschke

1994-01-01

312

A Study of the Adsorption of Ni(II) and Cu(II) by Clay Minerals  

Microsoft Academic Search

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

M. H. Koppelman; J. G. DILLARD

1977-01-01

313

Failure analysis techniques for Cu-Ni-Sn solder joint separations on mounted PBGA devices  

Microsoft Academic Search

There have been several papers published on PBGA Cu-Ni-Sn joint separations in which the phenomena has yet to be fully understood. Failure analysis on an open solder joint indicating the separation occurred at the intermetallic layer is not sufficient to warrant a corrective action or a fix as the root cause is not known. The Cu-Ni-Sn joint separations reported normally

G. H. G. Chan

2005-01-01

314

High-frequency micro-inductor fabricated on NiCuZn ferrite substrates  

NASA Astrophysics Data System (ADS)

We have fabricated the planar micro-inductors directly on a NiCuZn ferrite substrate. Due to NiCuZn's high resistivity, no insulator is required between the coil and the magnetic film; an advantage in terms of ease fabricated and stray capacitance reduction. Sandwiched inductors show improvement of inductance from 16 to 80 nH at 1 MHz compared with the coreless inductors, and the increment of inductance is larger than the sandwiched thin film inductor.

Tang, X. L.; Zhang, H. W.; Su, H.; Shi, Y.; Jiang, X. D.

2005-05-01

315

Electronic structure of bulk metallic glass Zr 55Al 10Cu 30Ni 5  

Microsoft Academic Search

The electronic structure of a bulk metallic glass Zr55Al10Cu30Ni5 has been studied by means of photoelectron spectroscopy in order to understand the origins of its large glass formation ability and unique mechanical properties from the microscopic point of view. The valence-band photoelectron spectra show three bands ascribed to the Zr 4d, Ni 3d, and Cu 3d states. A remarkable feature

K. Soda; K. Shimba; S. Yagi; M. Kato; T. Takeuchi; U. Mizutani; T. Zhang; M. Hasegawa; A. Inoue; T. Ito; S. Kimura

2005-01-01

316

Structural simulation of super-cooled liquid AuCu, AuAg alloys  

Microsoft Academic Search

The structure and thermodynamics of liquid AuCu and AuAg alloys have been simulated using molecular dynamics method based upon the EAM interatomic potential to reveal influence of the mismatch in atomic size on the glass-forming ability. Under the cooling rate in the range of 41012 to 11011K\\/s, the system undergoes the liquid, super-cooled liquid and solid state. Liquid Au and

Li Wang; Yanning Zhang; Hua Yang; Ying Chen

2003-01-01

317

Synthesis and characterization of Ag\\/Cu\\/HAP with platelet morphology  

Microsoft Academic Search

As a useful starting material in coating technology and preparation of HAP\\/polymers composites the platelet Ag\\/Cu\\/HAP was\\u000a prepared using the solid solution of HAP reacting with the mix-solution of silver and copper nitrate. Its composition, microstructure\\u000a and properties were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform\\u000a infrared spectroscopy (FTIR) and anti-bacterial or bacteriostatic tests.

Hui Yang; Bingjuan Xiao; Ke-Wei Xu

2009-01-01

318

Possible Mesozoic age of Ellenville Zn-Pb-Cu(Ag) deposit, Shawangunk Mountains, New York  

Microsoft Academic Search

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

J. D. Friedman; J. E. Conrad; E. H. McKee; F. E. Mutschler; R. E. Zartman

1994-01-01

319

Structure and age of the Cerro de Pasco Cu-Zn-Pb-Ag deposit, Peru  

Microsoft Academic Search

The world-famous Cu-Zn-Pb-Ag deposit at Cerro de Pasco, Peru, consists of texturally massive pyrite, texturally massive sphalerite-galena-pyrite, and veins containing pyrite and enargite. Historically the deposit has been considered to be the hydrothermal product of the adjacent Miocene volcanic and intrusive complex (locally known as the Vent). However, both the texturally massive sulfides of the deposit and the pre-Miocene strata

E. S. Cheney

1991-01-01

320

Structure and age of the Cerro de Pasco Cu-Zn-Pb-Ag deposit, Peru  

Microsoft Academic Search

The world-famous Cu-Zn-Pb-Ag deposit at Cerro de Pasco, Peru, consists of texturally massive pyrite, texturally massive sphalerite-galena-pyrite, and veins containing pyrite and enargite. Historically the deposit has been considered to be the hydrothermal product of the adjacent Miocene volcanic and intrusive complex (locally known as the ``Vent''). However, both the texturally massive sulfides of the deposit and the pre-Miocene strata

E. S. Cheney

1991-01-01

321

Morphology and coercivity of FePt thin films sputter deposited on Cu and Ag underlayers  

Microsoft Academic Search

In this study, we have found that Cu and Ag underlayers grow with the Volmer-Weber growth mode on MgO(OOl) substrates at relatively low temperature of around 400 degC. Using these island-like grown films as templates, we have successfully fabricated magnetically decoupled L10-FePt particulate films with the perpendicular anisotropy at 520 degC.

C. You; K. Hono; Y. Takahashi

2006-01-01

322

Oscillations of giant magnetoresistance in Cu\\/AgCo granular multilayers  

Microsoft Academic Search

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

Y. Luo; M. Moske; A. Kufler; T. Lorenz; K. Samwer

1997-01-01

323

Intermetallic growth on PWBs soldered with Sn3.8Ag0.7Cu  

Microsoft Academic Search

This paper describes the nature of the intermetallic phases observed at the interface and in the bulk of Sn3.8Ag0.7Cu solder immediately after reflow on PWBs coated with a variety of commercial plating systems. It also discusses the growth of these intermetallic phases after aging at homologous temperatures of 0.8Tm, 0.85Tm and 0.9Tm for 10, 100 and 1000 hours. The following

Y. Zheng; C. Hillman; P. McCluskey

2002-01-01

324

Growth of Sn and intermetallic compounds in Sn-Ag-Cu solder  

Microsoft Academic Search

The microstructure of the Sn-Ag-Cu solder is examined by optical microscopy and scanning electron microscopy (SEM) for various\\u000a compositions near the ternary eutectic for different cooling rates from the solder melt. Focus is on the size and orientation\\u000a of Sn grains as indicated by cross-polarized, light optical microscopy, and pole figures from x-ray diffraction. We find that\\u000a both composition and

L. P. Lehman; S. N. Athavale; T. Z. Fullem; A. C. Giamis; R. K. Kinyanjui; M. Lowenstein; K. Mather; R. Patel; D. Rae; J. Wang; Y. Xing; L. Zavalij; P. Borgesen; E. J. Cotts

2004-01-01

325

Itinerant-Electron Theory of Pressure Effects on Ferromagnetic Transition Temperatures: Ni and Ni-Cu Alloys  

Microsoft Academic Search

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

N. D. Lang; H. Ehrenreich

1968-01-01

326

Structure and texture of filamentous carbons produced by methane decomposition on NI and NI-CU catalysts  

Microsoft Academic Search

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

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

327

Nucleation and Growth of Cu-Al Intermetallics in Al-Modified Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys  

NASA Astrophysics Data System (ADS)

Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200C was recorded. During cooling from 1200C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary ? and Cu-Al ? phases at 450-550C; this was followed by ?-Sn, and, finally, Cu6Sn5 and Cu-Al ?1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200C to 800C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

Reeve, Kathlene N.; Anderson, Iver E.; Handwerker, Carol A.

2015-03-01

328

Insight into CH4 dissociation on NiCu catalyst: A first-principles study  

NASA Astrophysics Data System (ADS)

A density-functional theory method has been conducted to investigate the dissociation of CH4 on NiCu (1 1 1) surface. Two models: uniform surface slab model (Model A) and Cu-rich surface slab model (Model B) have been constructed to represent the NiCu (1 1 1) surface, in which the ratio of Ni/Cu is unit. The obtained results on the two models have been compared with those obtained on pure Ni (1 1 1) and Cu (1 1 1). It is found that the adsorption of CHx(x = 1-3) on Model B are weaker than on Model A. The rate-determining steps of CH4 dissociation on Model A and B both are the dissociation of CH, and the corresponding activation barriers are 1.37 and 1.63 eV, respectively. Obviously, it is approximately equal on Model A to that on pure Ni (1 1 1) [H. Liu, R. Zhang, R. Yan, B. Wang, K. Xie, Applied Surface Science 257 (2011) 8955], while it is lower by 0.58 eV on Model B compared to that on pure Cu (1 1 1). Therefore, the Cu-rich surface has better carbon-resistance ability than the uniform one. Those results well explain the experimental facts that NiCu/SiO2 has excellent catalytic performance and long-term stability [H.-W. Chen, C.-Y. Wang, C.-H. Yu, L.-T. Tseng, P.-H. Liao, Catalysis Today 97 (2004) 173], however, there is serious carbon deposition on NiCu/MgO-Al2O3 in CO2 reforming of methane [J. Zhang, H. Wang, A. K. Dalai, Journal of Catalysis 249 (2007) 300].

Liu, Hongyan; Zhang, Riguang; Yan, Ruixia; Li, Jingrui; Wang, Baojun; Xie, Kechang

2012-08-01

329

Effect of Cr additions on interfacial reaction between the Sn-Zn-Bi solder and Cu\\/electroplated Ni substrates  

Microsoft Academic Search

Intermetallic compounds (IMCs) growth on the Sn8Zn3Bi (Cr) solder joints with Cu and electroplated Ni substrates was investigated after aging at 150C. It was found that the IMCs were the Cu5Zn8 and Ni5Zn21 at the solder\\/Cu and solder\\/Ni interface, respectively. The IMCs growth rate at the Sn8Zn3BiCr\\/Cu and Ni interface was slower than that at Sn8Zn3Bi\\/Cu interface (about 1\\/2times) and

Jinglin Bi; Anmin Hu; Jing Hu; Tingbi Luo; Ming Li; Dali Mao

2011-01-01

330

Magnetism of Fe clusters embedded in Cu, Ag, and Au fcc matrices: density functional calculations  

NASA Astrophysics Data System (ADS)

We present extensive first principles density functional theory (DFT) calculations dedicated to analyze the magnetic properties of small Fen clusters (n = 2,3) embedded in Cu fcc, Ag fcc and Au fcc matrices. We consider several dimers and trimers having different interatomic distances. In all cases the Fe atoms are embedded as substitutional impurities in the metallic network. For the case of the Fe dimers we have considered two magnetic configurations: ferromagnetic (antiferromagnetic), when the atomic magnetic moment of the Fe atoms are parallel (antiparallel) each other. For the case of dimers immersed in Cu and Ag matrices, the ground state corresponds to the ferromagnetic Fe dimer whose interatomic distance is a/?2. For Fe dimer immersed in the Au matrix the ground state corresponds to a ferromagnetic coupling when the interatomic distance is a?(3/2). In the case of the Fe trimers we have considered three or four magnetic configurations, depending on the Fe cluster geometry. For the case of Fe trimer immersed in Cu and Ag matrices we have found that the ground state corresponds to the ferromagnetic trimer forming an equilateral triangle with an interatomic distance equal to a/?2. The ground state for the Fe trimer immersed in the Au matrix corresponds to the ferromagnetic Fe trimer forming a right angle triangle.

Flix-Medina, R. E.; Leyva-Lucero, M. A.; Meza-Aguilar, S.; Demangeat, C.

2014-01-01

331

Hydrothermal ethanol conversion on Ag, Cu, Au/TiO2  

NASA Astrophysics Data System (ADS)

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 150-400C 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 Brnsted acidic sites.

Mai, Do Tkhyui; Mikhalenko, I. I.; Pylinina, A. I.

2014-10-01

332

Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial AgCu nanoparticles  

SciTech Connect

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.

Taner-Camc?, Merve; Suzer, Sefik, E-mail: suzer@fen.bilkent.edu.tr [Department of Chemistry, Bilkent University, 06800 Ankara (Turkey)

2014-03-15

333

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

NASA Astrophysics Data System (ADS)

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 100h without any signs of decay. In summary, this work provides new alternative anode catalytic materials to accelerate the commercialization of SOFC technology.

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

2014-07-01

334

Temperature Dependence Of Core Loss In Cobalt Substituted Ni-Zn-Cu A. Lucas 1,2  

E-print Network

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

Paris-Sud XI, Universit de

335

High salinity volatile phases in magmatic Ni-Cu-platinum group element deposits  

NASA Astrophysics Data System (ADS)

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.

Hanley, J. J.; Mungall, J. E.

2004-12-01

336

Metallic glass alloys of Zr, Ti, Cu and Ni  

DOEpatents

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.

Lin, Xianghong (Pasadena, CA); Peker, Atakan (Pasadena, CA); Johnson, William L. (Pasadena, CA)

1997-01-01

337

Characterization of Al-Cu-Mg-Ag Alloy RX226-T8 Plate  

NASA Technical Reports Server (NTRS)

Aluminum-copper-magnesium-silver (Al-Cu-Mg-Ag) alloys that were developed for thermal stability also offer attractive ambient temperature strength-toughness combinations, and therefore, can be considered for a broad range of airframe structural applications. The current study evaluated Al-Cu-Mg-Ag alloy RX226-T8 in plate gages and compared performance with sheet gage alloys of similar composition. Uniaxial tensile properties, plane strain initiation fracture toughness, and plane stress tearing resistance of RX226-T8 were examined at ambient temperature as a function of orientation and thickness location in the plate. Properties were measured near the surface and at the mid-plane of the plate. Tensile strengths were essentially isotropic, with variations in yield and ultimate tensile strengths of less than 2% as a function of orientation and through-thickness location. However, ductility varied by more than 15% with orientation. Fracture toughness was generally higher at the mid-plane and greater for the L-T orientation, although the differences were small near the surface of the plate. Metallurgical analysis indicated that the microstructure was primarily recrystallized with weak texture and was uniform through the plate with the exception of a fine-grained layer near the surface of the plate. Scanning electron microscope analysis revealed Al-Cu-Mg second phase particles which varied in composition and were primarily located on grain boundaries parallel to the rolling direction. Fractography of toughness specimens for both plate locations and orientations revealed that fracture occurred predominantly by transgranular microvoid coalescence. Introduction High-strength, low-density Al-Cu-Mg-Ag alloys were initially developed to replace conventional 2000 (Al-Cu-Mg) and 7000 (Al-Zn-Cu-Mg) series aluminum alloys for aircraft structural applications [1]. During the High Speed Civil Transport (HSCT) program, improvements in thermal stability were demonstrated for candidate aircraft wing and fuselage skin materials through the addition of silver to Al-Cu-Mg alloys based on Al 2519 chemistry [2]. Thermal stability of the resulting Al-Cu-Mg-Ag alloys, C415-T8 and C416-T8, was due to co-precipitation of the thermally stable . (AlCu) and ' (Al2Cu) strengthening phases [1-4]. The strength and toughness behavior was investigated for these alloys produced as 0.090-inch thick rolled sheet in the T8 condition and after various thermal exposures. The mechanical properties were shown to be competitive with conventional aircraft alloys, 2519-T8 and 2618-T8 [2]. During the Integral Airframe Structure (IAS) program, advanced aluminum alloys were examined for use in an integrally stiffened airframe structure where the skin and stiffeners would be machined from plate and extruded frames would be mechanically attached (see Figure 1) [5]. Advantages of integrally stiffened structure include reduced part count, and reduced assembly times compared to conventional built-up airframe structure. The near-surface properties of a thick plate are of significance for a machined integrally stiffened airframe structure since this represents the skin location. Properties measured at the mid-plane of the plate are more representative of the stiffener web. RX226 was developed to exploit strength-toughness improvements and thermal stability benefits of Al-Cu-Mg-Ag alloys in plate gages. This study evaluated the microstructure and properties of three gages of plate produced in the T8 condition.

Lach, Cynthia L.; Domack, Marcia S.

2003-01-01

338

Mechanism of phenol oxidation by heterodinuclear Ni Cu bis(?-oxo) complexes involving nucleophilic oxo groups.  

PubMed

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

Kundu, Subrata; Miceli, Enrico; Farquhar, Erik R; Ray, Kallol

2014-03-21

339

Mechanism of phenol oxidation by heterodinuclear Ni Cu bis(?-oxo) complexes involving nucleophilic oxo groups  

PubMed Central

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

Kundu, Subrata; Miceli, Enrico; Farquhar, Erik R.

2014-01-01

340

Oxidation of carbon monoxide over Cu- and Ag-NaY catalysts with aqueous hydrogen peroxide  

SciTech Connect

A novel oxidation reaction of CO with aqueous H{sub 2}O{sub 2} over Cu-NaY (2-15 wt%) and Ag-NaY (5-15 wt%) catalysts has been achieved at low temperatures (55-70 deg. 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 = 910 m{sup 2}/g) with an aqueous solution of known concentrations of copper acetate and silver nitrate. Solids were subjected to thermal treatment at 300-450 deg. C prior to catalytic measurements unless subjected to subsequent reduction with hydrogen at 350 deg. C. The physicochemical characterization of the catalysts was probed using X-ray diffraction (XRD), FT-IR and combined thermal analyses TGA-DrTGA. The XRD data indicated that, the Ag particles have an ordered location in the sodalite cavity and the center of a single six-ring. The FT-IR data also proved the presence of a new peak at 1385 cm{sup -1} that is assigned to Ag-coordinated with the framework. A slow induced oxidation of CO (induction period, t{sub ind}) took place at the initial stage of the CO oxidation reaction after which the reaction obeyed first-order kinetics. The utilized metal ions are proposed to be reduced to lower oxidation states such as Cu{sup +} and Ag{sup 0} during the first period of reaction, t{sub ind}, where the reaction proceeded favorably on such sites. Such argument was evidenced by carrying out the oxidation reaction over H{sub 2}-reduced Cu10-NaY and Ag10-NaY catalysts. The reduction caused a decrease in the t{sub ind}, giving an evidence that the lower oxidation states Cu{sup +} and Ag{sup 0} are the active sites in the studied oxidation reaction. The enhancement in catalytic activity was interpreted in terms of the facile adsorption of CO on the low oxidation state species.

El-Bahy, Zeinhom Mohamed [Chemistry Department, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo (Egypt)], E-mail: zeinelbahy2020@yahoo.com

2007-12-04

341

Effect of metal substrate (Al, Cu, Ag, and Au) on the photodegradation of polymers: Polyacrylonitrile  

SciTech Connect

Al-backed PVF film shows more photodegradation than does the nonmetalized PVF film. The effect of several metal substrates (Al, Cu, Ag, and Au) on the photodegradation of polyacrylonitrile (PAN) has been examined. Under oxidative conditions, the order of PAN photodegradation in M/PAN films is shown to be Cu/PAN>>PAN>>Al/PAN>Au/PAN>Ag/PAN. Formation of carbonyl group during the photodegradation is predominant in the cases of Al and Au. Under nonoxidative conditions there is no evidence of carbonyl group formation, but the photodegradation of Cu/PAN is still substantial. Under oxidative conditions the Cu/PAN film begins the char after approximately one hour, compared with four and a half hours under nonoxidative conditions. The photodegradation mechanism in the range of 250 less than or equal to lambda less than or equal to 400 nm suggests the formation of M(CN)/sub x/ species, but no such species are detected spectroscopically at the energy employed. A catalytic effect of metal films on the photodegradation of PAN is observed.

Welch, W.F.; Graham, S.M.; Chughatai, A.R.; Smith, D.M.; Schissel, P.

1987-07-01

342

Phase composition of aluminium oxides promoted by Cr, Cu and Ni additives  

Microsoft Academic Search

X-ray diffraction analysis of aluminium oxides promoted by Cr3+, Cu2+ and Ni2+ additives has been carried out in a high-temperature X-ray chamber. It has been revealed that at T=8231473 K in inert media, solid solutions are formed and transformation to ?-Al2O3 takes place differently. Mineralizing action of Cu cations is suggested to be due to the decomposition of Cu2+-containing aluminate

E. M. Moroz; O. A. Kirichenko; A. V. Ushakov; E. A. Levitskii

1985-01-01

343

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

SciTech Connect

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.

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

344

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

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

345

Process and properties of electroless Ni-Cu-P-ZrO{sub 2} nanocomposite coatings  

SciTech Connect

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.

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

346

Formation behaviour of reaction layer in Sn-3.0Ag-0.5Cu solder joint with addition of porous Cu interlayer  

NASA Astrophysics Data System (ADS)

The morphology and growth of interfacial intermetallic compound (IMC) between Sn-3.0Ag-0.5Cu solder alloy and Cu substrate metal of solder joint is reported. The IMC morphology and IMC thickness layer were observed at three different porosities of porous Cu interlayer. The results revealed that during soldering process, Cu6Sn5 compound with scallop like morphology was formed at the interface of both the solder alloy and Cu substrate and at solder alloy and porous Cu interlayer. By adding porous Cu interlayer at the solder joint, the IMC thickness increased with increasing soldering temperature and the number of pores in porous Cu interlayer. The effect of porosity on increasing the IMC layer was also due to the slower cooling rate during solidification of molten solder.

Hani Jamadon, Nashrah; Miyashita, Yukio; Yusof, Farazila; Hamdi, Mohd; Otsuka, Yuichi; Ariga, Tadashi

2014-08-01

347

The role of vibrations in thermodynamic properties of Cu-Ni alloys  

NASA Astrophysics Data System (ADS)

We report results of a systematic study for vibrational thermodynamic functions of Cu-Ni alloys, in the harmonic approximation, using interaction potentials based on the embedded atom method with improved optimization techniques. The vibrational density of states of the systems is calculated using real space Green's function method. From an investigation of local force fields we found that increasing Ni concentration in the alloy substantially stiffens the force experienced by Cu atoms compared to that of Ni atoms. Our calculations also reveal that vibrational entropy change between ordered and disordered crystals of Cu-Ni is negligible. However, the mixing entropy of the phonons and electronic states is found to be negative and favors un-mixing, and thus contributes to the miscibility gap.

Onat, Berk; Durukano?lu, Sondan

2014-11-01

348

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

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 750C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750C for 12?h, and not observed in NiCu-BZCYYb exposed to dry CH? at 750C 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 750C in wet CH? for 130?h, indicating that NiCu-BZCYYb is a promising anode for direct CH? solid oxide fuel cells (SOFCs). PMID:25563843

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

2015-01-01

349

Phase constitution and interface structure of nano-sized Ag-Cu/AlN multilayers: Experiment and ab initio modeling  

SciTech Connect

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.

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

350

Investigation of the thermoelectric properties of La2CuO4 ceramics with the addition of Ag  

NASA Astrophysics Data System (ADS)

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.

Zhu, Chunhui; Gong, Jing; Li, Zhuangzhi; Zhou, Hongjuan; Tang, Guide

2015-01-01

351

Periplasmic domain of CusA in an Escherichia coli Cu+/Ag+ transporter has metal binding sites.  

PubMed

The resistance nodulation division (RND)-type efflux systems are utilized in Gram-negative bacteria to export a variety of substrates. The CusCFBA system is the Cu(+) and Ag(+) efflux system in Escherichia coli, conferring resistance to lethal concentrations of Cu(+) and Ag(+). The periplasmic component, CusB, which is essential for the assembly of the protein complex, has Cu(+) or Ag(+) binding sites. The twelve-span membrane protein CusA is a homotrimeric transporter, and has a relatively large periplasmic domain. Here, we constructed the periplasmic domain of CusA by joining two DNA segments and then successfully expressed and purified the protein. Isothermal titration calorimetry experiments revealed Ag(+) binding sites with Kds of 10(-6)-10(-5) M. Our findings suggest that the metal binding in the periplasmic domain of CusA might play an important role in the function of the efflux pump. PMID:21221942

Yun, Bo-Young; Xu, Yongbin; Piao, Shunfu; Kim, Nahee; Yoon, Jeong-Hyun; Cho, Hyun-Soo; Lee, Kangseok; Ha, Nam-Chul

2010-12-01

352

Polycrystalline oxides formation during transient oxidation of (001) Cu-Ni binary alloys studied by in situ TEM and XRD.  

SciTech Connect

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.

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

353

Effect of Gold Content on the Reliability of SnAgCu Solder Joints  

Microsoft Academic Search

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

Jianbiao Pan; Julie Silk; Mike Powers; Patrick Hyland

2011-01-01

354

Influence of carbon nanotube on the structure evolution of Ni-Cu alloy nanorod  

NASA Astrophysics Data System (ADS)

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.

Guo, J.-Y.; Xu, C.-X.; Yang, C.; Dai, J.; Li, Z.-H.

2011-02-01

355

Intermetallic compounds formed at the interface between Cu substrate and an Sn-9Zn-0.5Ag lead-free solder  

SciTech Connect

The intermetallic compounds (IMCs) formed at the interface between Cu substrate and an Sn-9Zn-0.5Ag lead-free solder alloy have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron diffraction (ED). The XRD patterns show that the main IMCs formed at the interface of Sn-9Zn-0.5Ag/Cu are {gamma}-Cu{sub 5}Zn{sub 8} and {eta}'-Cu{sub 6}Sn{sub 5}. The Ag{sub 3}Sn IMC with orthorhombic structure was also observed at the Sn-9Zn-0.5Ag/Cu interface by TEM and ED analyses. The interfacial adhesion strength between the Cu substrate and Sn-9Zn-0.5Ag lead-free solder alloy is higher than that of the Sn-9Zn alloy due to the formation of Ag{sub 3}Sn IMC at the interface.

Chang, T.-C.; Hon, M.-H.; Wang, M.-C

2003-04-30

356

Effect of Mechanical Alloying Parameters on the Formation of Ni-Cu Solid Solution Coating on the Ni Balls  

NASA Astrophysics Data System (ADS)

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.

Farahbakhsh, Iman; Zakeri, Alireza; Manikandan, Palavesamuthu; Tanaka, Shigeru; Hokamoto, Kazuyuki

2011-01-01

357

Fractional crystallization of anhydrous sulfide liquid in the system Fe-Ni-Cu-S, with application to magmatic sulfide deposits  

Microsoft Academic Search

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, 850-1050C 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,

Michael E. Fleet; Yuanming Pan

1994-01-01

358

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

SciTech Connect

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.

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

359

Metallic glass alloys of Zr, Ti, Cu and Ni  

DOEpatents

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.

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

1997-04-08

360

Ag-Cu catalysts for ethylene epoxidation: Selectivity and activity descriptors  

NASA Astrophysics Data System (ADS)

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.

Nguyen, Ngoc Linh; de Gironcoli, Stefano; Piccinin, Simone

2013-05-01

361

Structure evolution, magnetic properties and giant magnetoresistance of granular NiFeCo-Ag films  

NASA Astrophysics Data System (ADS)

The structure evolution of granular (NiFeCo)xAg(1-x) (x = 9-41 at%) films was characterized by x-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, x-ray diffraction, atomic force microscopy and magnetic force microscopy. The giant magnetoresistance of the films was measured as a function of temperature between 20 and 300 K using a conventional four-point probe dc technique in the presence of a magnetic field up to 7.6 kOe. The temperature dependence of magnetization and magnetic hysteresis loops for the films were measured by a SQUID magnetometer. It was found that the optimum concentration and annealing temperature for the maximum giant magnetoresistance was associated with the crystalline structure and the magnetic domain structure of the film. A clear flat-top parabola and a significant deviation from the quadratic law expected for equal-size, non-interacting superparamagnetic particles in the magnetoresistance (??/?) against magnetization (M/Ms) curve were observed for the 500 C annealed (NiFeCo)20Ag80 sample in a wide field region. The curves of ??/? against M/Ms were well described by a function of the form c(M/Ms)10. This behaviour was explained by combining the characteristics of the microstructure, magnetic domain structure and magnetic properties of the sample.

Wang, Hao; Wong, S. P.; Lu, Xiang; Yan, Xin; Cheung, W. Y.; Ke, N.; Hu, Shejun; Zeng, Dechang; Liu, Zhenyi

2000-06-01

362

Effect of Processing Scheme on Precipitation Mechanisms and Evolution of Microstructures and Properties of CuAgZr alloy  

NASA Astrophysics Data System (ADS)

CuAgZr alloy is a variant of the CuAg alloy that is developed for high strength and high conductivity applications. With Zr addition, the discontinuous precipitation at the grain boundaries is decreased due to slower Ag diffusion rate. Mechanical and electrical properties of copper alloys can be influenced by many factors including alloying elements, mechanical processing, heat treatment and their microstructures. For high strength and high conductivity applications, Cu-Ag alloys are one of the good candidate materials for these used because of their excellent combinations of high strength and high electrical conductivity. The primary strengthening mechanism is precipitation hardening due to the formation of Ag precipitates during the heat treatment process. Its strengthening is accomplished mainly by the precipitation of Ag precipitates, which tend to align on the {111} planes in the Cu matrix. The evolutions of hardness and electrical conductivity of the aged samples showed that the Ag particles precipitated out from the Cu matrix in the early stage of aging. The hardness of the aged samples is significantly increased from 95 HV0.1 to the maximum at 193 HV0.1 after 2 hours of aging. The density of Ag precipitates is increased with increased aging time. Ag precipitation occurs in particular Cu matrix planes due to the minimization of elastic energy. The Ag precipitates were formed by clustering of Ag atoms while maintaining the fcc crystal structure of the matrix. They have faceted {111} interfaces with the matrix. The thickening of the precipitates appears to be by the ledge growth mechanism, which is promoted by misfit dislocation networks on the interface. The ledge movement and growth were compensated with the existence of interfacial misfit dislocations. During diffusional growth, misfit dislocation arrays along the precipitate/matrix interface accommodated the lattice mismatch. Therefore, precipitate growth involves the formation and migration of ledges. Precipitate growth by ledge motion was necessary due to partial coherency of the interfaces. Effects of plastic deformation on mechanical property and electrical conductivity of CuAgZr alloy are presented. The main strengthening effects in plastically deformed CuAgZr are contributed by precipitation mechanism combined with work hardening. Electrical conductivity is strongly affected by precipitation reactions during high temperature annealing. Therefore, the properties of hot rolled CuAgZr exhibit good combination of strength and electrical conductivity. A combination of severe plastic deformation by high pressure torsion (HPT) followed by long term annealing at low temperature allows CuAgZr to obtain a high hardness (more than 300 HV0.1) that is comparable to as-processed HPT CuAgZr. The microstructure of annealed HPT samples exhibits a small grain size and low dislocation density.

Piyawit, Waraporn

363

Effects of Cu and Ag as ternary and quaternary additions on some physical properties of SnSb7 bearing alloy  

Microsoft Academic Search

The structure, electrical resistivity, and elastic modulus of SnSb7 and SnSb7X (X = Cu , Ag, or Cu and Ag) rapidly solidified alloys have been investigated using X-ray diffractometer, double bridge, and dynamic resonance techniques. Copper and silver additions to SnSb result in the formation of a eutectic matrix containing embedded crystals (intermetallic phases) of SnCu, SnAg, and SnSb. The

A. B. El-Bediwi

2004-01-01

364

The reactions between electroless Ni-Cu-P Deposit and 63Sn37Pb flip chip solder bumps during reflow  

Microsoft Academic Search

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

Chun-Jen Chen; Kwang-Lung Lin

2000-01-01

365

Sensitive and selective colorimetric detection of Cu(2+) in aqueous medium via aggregation of thiomalic acid functionalized Ag nanoparticles.  

PubMed

A simple and effective colorimetric method for determination of Cu(2+) in real samples was developed. In this method, thiomalic acid functionalized silver nanoparticles (TMA-AgNPs) were prepared and changes in solution color, induced by the aggregation of TMA-AgNPs in the presence of Cu(2+), were employed for quantitative analysis. The surface plasmon resonance (SPR) band of our synthesized TMA-AgNPs was located at 392 nm and shifted to a longer wavelength after aggregation due to the interactions between carboxylate and Cu(2+). A band intensity ratio of A455/(A392-A455) was constructed and used to correlate with the concentration of Cu(2+). A linear relationship was found with a linear response up to 50 nM of Cu(2+). Due to the formation of a stable carboxylate Cu(2+) complex, highly sensitive detection of Cu(2+) was achieved with the estimated detection limit approaching 1 nM. Moreover, the formation of the stable complex leads to high selectivity in the detection of Cu(2+), which was verified by examination of 12 other metal ions. In the detection of Cu(2+) in real samples, results indicated that our proposed method is simple, sensitive and selective for application in such measurements. PMID:25316548

Tharmaraj, Vairaperumal; Yang, Jyisy

2014-12-01

366

Soil anomalies associated with Cu-Ni mineralization in the South Kawishiwi area, northern Lake County, Minnesota  

USGS Publications Warehouse

Geochemical sampling in the contact zone between the Giants Range Granite and the Duluth Gabbro Complex along the South Kawishiwi River indicates the presence of extensive soil anomalies associated with the known Cu-Ni-Co-Ag mineralization in the basal part of the Duluth Gabbro Complex. A close spatial relationship was found between the ore bodies and associated anomalies, despite the fact that the parent material of the sampled soils was glacial overburden that mantles the area to a depth of 0-50 feet. The <74 mesh fraction of B-horizon soils was found to be an effective sample type for geochemical exploration in this area. Trace metals are believed to be held primarily by the clay-size hydrated iron oxides and manganese oxide, which are somewhat enriched in the fine fraction of the B-horizon soils.

Alminas, Henry V.

1975-01-01

367

Al2O3/SUS304 Brazing via AgCuTi-W Composite as Active Filler  

NASA Astrophysics Data System (ADS)

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.

Su, Cherng-Yuh; Zhuang, Xie-Zongyang; Pan, Cheng-Tang

2014-03-01

368

Cytotoxicity Evaluation and Magnetic Characteristics of Mechano-thermally Synthesized CuNi Nanoparticles for Hyperthermia  

NASA Astrophysics Data System (ADS)

CuNi alloys are very well known, both in academia and industry, based on their wide range of applications. In the present investigation, the previously synthesized Cu0.5Ni0.5 nanoparticles (NPs) by mechano-thermal method were studied more extensively. Phase composition and morphology of the samples were studied by employing x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The Curie temperature ( T c) was determined by differential scanning calorimetry (DSC). In vitro cytotoxicity was studied through methyl-thiazolyl-tetrazolium (MTT) assay. XRD and FESEM results indicated the formation of single-phase Cu0.5Ni0.5. TEM micrographs showed that the mean particle size of powders is 20 nm. DSC results revealed that T c of mechano-thermally synthesized Cu0.5Ni0.5 is 44 C. The MTT assay results confirmed the viability and proliferation of human bone marrow stem cells in contact with Cu0.5Ni0.5 NPs. In summary, the fabricated particles were demonstrated to have potential in low concentrations for cancer treatment applications.

Amrollahi, P.; Ataie, A.; Nozari, A.; Seyedjafari, E.; Shafiee, A.

2015-03-01

369

Structural and magnetic properties of NiCuZn ferrite/SiO 2 nanocomposites  

NASA Astrophysics Data System (ADS)

Ni0.53Cu0.12Zn0.35Fe2O4/SiO2 nanocomposites with different weight percentages of NiCuZn ferrite dispersed in silica matrix were prepared by microwave-hydrothermal method using tetraethylorthosilicate as a precursor of silica, and metal nitrates as precursors of NiCuZn ferrite. The structure and morphology of the composites were studied using X-ray diffraction and scanning electron microscopy. The structural changes in these samples were characterized using Fourier Transform Infrared Spectrometer in the range of 400-1500 cm-1. The bands in the range of 580-880 cm-1 show a slight increase in intensity, which could be ascribed to the enhanced interactions between the NiCuZnFe2O4 clusters and silica matrix. The effects of silica content and sintering temperature on the magnetic properties of Ni0.53Cu0.12Zn0.35Fe2O4/SiO2 nanocomposites have been studied using electron spin resonance and vibrating sample magnetometer.

Praveena, K.; Sadhana, K.; Ramana Murthy, S.

2011-08-01

370

Cytotoxicity Evaluation and Magnetic Characteristics of Mechano-thermally Synthesized CuNi Nanoparticles for Hyperthermia  

NASA Astrophysics Data System (ADS)

CuNi alloys are very well known, both in academia and industry, based on their wide range of applications. In the present investigation, the previously synthesized Cu0.5Ni0.5 nanoparticles (NPs) by mechano-thermal method were studied more extensively. Phase composition and morphology of the samples were studied by employing x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) techniques. The Curie temperature (T c) was determined by differential scanning calorimetry (DSC). In vitro cytotoxicity was studied through methyl-thiazolyl-tetrazolium (MTT) assay. XRD and FESEM results indicated the formation of single-phase Cu0.5Ni0.5. TEM micrographs showed that the mean particle size of powders is 20 nm. DSC results revealed that T c of mechano-thermally synthesized Cu0.5Ni0.5 is 44 C. The MTT assay results confirmed the viability and proliferation of human bone marrow stem cells in contact with Cu0.5Ni0.5 NPs. In summary, the fabricated particles were demonstrated to have potential in low concentrations for cancer treatment applications.

Amrollahi, P.; Ataie, A.; Nozari, A.; Seyedjafari, E.; Shafiee, A.

2015-01-01

371

RF magnetron sputtered crystalline TiNiCu shape memory alloy thin film  

NASA Astrophysics Data System (ADS)

Shape memory alloys (SMAs) offer a unique combination of novel properties, such as shape memory effect, super- elasticity, biocompatibility and high damping capacity, and thin film SMAs have the potential to become a primary actuating mechanism for micro-actuators. In this study, TiNiCu films were successfully prepared by mix sputtering of a Ti55Ni45 target with a separated Cu target. Crystalline structure, residual stress and phase transformation properties of the TiNiCu films were investigated using X-ray diffraction (XRD), differential scanning calorimeter (DSC), and curvature measurement methods. Effects of the processing parameters on the film composition, phase transformation and shape-memory effects were analyzed. Effects of the processing parameters on the film composition, phase transformation and shape-memory effects were analyzed. Results showed that films prepared at high Ar gas pressure exhibited a columnar structure, while films deposited at a low Ar gas pressure showed smooth and featureless structure. Chemical composition of TiNiCu thin films was dependent on the DC power of copper target. DSC, XRD and curvature measurement revealed clearly the martensitic transformation of the deposited TiNiCu films. When the freestanding film was heated and cooled, a two-way shape memory effect can be clearly observed.

Fu, Yongqing; Huang, Xu; Du, Hejun; Liu, Yong

2001-07-01

372

First-principles Study of Methane Dehydrogenation on a Bimetallic Cu/Ni(111) Surface  

SciTech Connect

We present density-functional theory calculations of the dehydrogenation of methane and CHx (x =13) on a Cu/Ni(111) surface, where Cu atoms are substituted on the Ni surface at a coverage of 1/4 monolayer. As compared to the results on other metal surfaces, including Ni(111), a similar activation mechanism with different energetics is found for the successive dehydrogenation of CH4 on the Cu/Ni(111) surface. In particular, the activation energy barrier (Eact) for CH?C+H is found to be 1.8 times larger than that on Ni(111), while Eact for CH4?CH3+H is 1.3 times larger. Considering the proven beneficial effect of Cu observed in the experimental systems, our findings reveal that the relative Eact in the successive dehydrogenation of CH4 plays a key role in impeding carbon formation during the industrial steam reforming of methane. Our calculations also indicate that previous scaling relationships of the adsorption energy (Eads) for CHx (x=13) and carbon on pure metals also hold for several Ni(111)-based alloy systems.

An, Wei; Zeng, Xiao Cheng; Turner, C. H.

2009-11-02

373

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)

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.

Tatem, Elroy

374

Structural and optical properties of (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin film alloys  

SciTech Connect

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.

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

375

Rotationally anisotropic second-harmonic generation studies of the structure and electronic properties of bimetallic interfaces, Ag on Cu(110)  

SciTech Connect

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.

Hoffbauer, M.A.; McVeigh, V.J.

1990-01-01

376

Annealing dependence of giant magnetoresistance in CuFeNi alloys  

NASA Astrophysics Data System (ADS)

Giant magnetoresistance (GMR) in granular CuFeNi alloys is comparable in magnitude to that observed in CuCo. Here we study magnetization M and GMR (0Cu80Fe20-xNix (x=0, 2.5, 5, 10, and 15) as a function of annealing temperature Tan<500 C, using a superconducting quantum interference device (SQUID) magnetometer. A wide variety of granular structures characterized by different average values of the particle sizes is obtained for different Fe/Ni ratios and annealing conditions. For Cu80Fe10Ni10, neither M nor GMR exhibit static hysteresis for T>50 K. At this temperature, the largest GMR value (19%) was obtained for a sample annealed at 400 C for 2 h. In Cu80Fe5Ni15, on the other hand, the microstructure and magnetic properties of the alloy are much more sensitive to annealing. The magnetoresistence is strongly dependent upon both the annealing and the measuring temperatures. For Fe-rich Cu80Fe20-xNix, the magnetic properties other alloys show a weak dependence upon annealing temperature. Magnetization curves for both as-cast and annealed alloys indicate many large particles which saturate at low magnetic fields. GMR versus alloy composition is presented for two annealing temperatures.

Martins, C. S.; Missell, F. P.

2000-05-01

377

Magnetic behavior of NiCu nanowire arrays: Compositional, geometry and temperature dependence  

SciTech Connect

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.

Palmero, E. M., E-mail: epalmero@icmm.csic.es; Bran, C.; Real, R. P. del; Vzquez, M. [Institute of Materials Science of Madrid, CSIC, Madrid 28049 (Spain); Magn, C. [Advanced Microscopy Laboratory (LMA), Institute of Nanoscience of Aragn (INA)-ARAID and Department of Condensed Matter Physics, University of Zaragoza, Zaragoza 50018 (Spain)

2014-07-21

378

Chapter 13 Electronic Structure and Bonding in Amorphous Zr67Ni33 and Zr67Cu33  

NASA Astrophysics Data System (ADS)

The electronic structures and the bonding properties in amorphous Zr67Ni33 and Zr67Cu33 alloys have been calculated by the discrete variational (DV)-X[alpha] molecular orbital method to investigate the chemical bonding in the amorphous structures. The calculations about Zr2Ni and Zr2Cu and [beta]-Zr crystals were also performed for comparison. The broad agreement between the DOSs for the amorphous Zr67Ni33 alloy and the Zr2Ni crystal implies the structure similarity. The calculated DOSs and the bond overlap population analyses suggest that the amorphous structures are significantly influenced by the tight binding pair (Zr-Ni in the Zr-Ni systems and Cu-Cu in the Zr-Cu systems). The glass-formation abilities reflect the bonding properties in the amorphous and crystal structures.

Sugita, Kazuki; Mizuno, Masataka; Araki, Hideki; Shirai, Yasuharu

379

Analysis of the reaction between 60Sn-40Pb solder with a Pd-Pt-Ag-Cu-Au alloy  

NASA Astrophysics Data System (ADS)

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.

Frear, D. R.; Michael, J. R.; Hlava, P. F.

1993-02-01

380

Growth of single-walled Ag and Cu nanotubes confined in carbon nanotubes, studied by molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

Growth of single-walled silver and copper nanotubes (Ag- and Cu-SWNTs), confined in carbon nanotubes (CNTs), has been studied by using the classical molecular dynamics method. It is found that: (1) Four kinds of Ag-SWNTs, i.e., (3, 2), (4, 2), (4, 3), and (5, 3) ones, and five kinds of Cu-SWNTs, i.e., (3, 2), (4, 2), (4, 3), (4, 4), and (5, 3) ones, could be formed when the diameters of outside CNT containers are changed from 6.78 to 10.86 . (2) The formation of the Ag- and Cu-SWNTs in confined CNTs is less sensitive to the CNTs' tube indices, but heavily influenced by the CNTs' diameters. And the Ag- and Cu-SWNTs, formed in confined CNTs, are radially compressed, when the CNTs' diameters are small. (3) The frequencies of the radial breathing modes of Ag- and Cu-SWNTs are approximately to vary linearly with the inverse tube diameters.

Han, Yang; Li, Rui; Ge, Yong; Dong, Jinming

2013-06-01

381

Analysis of the reaction between 60Sn-40Pb solder with a Pd-Pt-Ag-Cu-Au alloy  

SciTech Connect

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 intermetallic between 60Sn-40Pb and the Pd-Ag-Cu-Au-Pt-Zn alloy were characterized. The matrix of the intermetallic layer consists of PdSn[sub 4] with platinum and gold substituting for the palladium in the crystal structure. Also present were precipitates of Cu[sub 3]Sn and Ag[sub 3]Sn. 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. 20 refs., 11 figs., 3 tabs.

Frear, D.R.; Michael, J.R.; Hlava, P.F. (Sandia National Lab., Albuquerque, NM (United States))

1993-02-01

382

Thermal and structural characterization of Cu-Al-Mn-X (Ti, Ni) shape memory alloys  

NASA Astrophysics Data System (ADS)

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.

Canbay, C. Aksu; Genc, Z. Karagoz; Sekerci, M.

2014-05-01

383

Microstructure and reactions of SiC{sub w}-reinforced alumina with Ag-Cu-In-Ti  

SciTech Connect

Brazing experiments were performed at 750 C for 2 h between Ag-Cu-In-Ti alloy and SiC{sub w}/Al{sub 2}O{sub 3}. The first clearly nonbraze layer consists of an oxide layer of metallic composition 33Ti-31Al-22Cu-14S. Areas adjacent to the SiC whiskers were of different composition. A thin, continuous layer on the alumina portion of the composite appears to be {gamma}-TiO. The SiC whiskers are preferentially consumed and undergo reductions in diameter of approximately 40%. Observed knobby whisker morphologies may be related to SiC stacking faults. {eta}-type phases detected near the Ag-Cu eutectic portion of the joint appear to consist of Ti-Cu-Al-Si-O and Ti{sub 3}Cu{sub 3}O.

Park, E.S.; Lannutti, J.J. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science; Cawley, J.D. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science

1995-01-01

384

Five-Fold Twinned Pd2NiAg Nanocrystals with Increased Surface Ni Site Availability to Improve Oxygen Reduction Activity.  

PubMed

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

Liu, Suli; Zhang, Qinghua; Li, Yafei; Han, Min; Gu, Lin; Nan, Cewen; Bao, Jianchun; Dai, Zhihui

2015-03-01

385

Electrical transport and structural investigations in Cu2O substituted AgI-Ag2O-V2O5 glass-ceramic nanocomposites  

NASA Astrophysics Data System (ADS)

Glass-ceramic nanocomposites in Cu2O substituted AgI-(Ag2O)1-x-(Cu2O)x-V2O5 superionic system are prepared by annealing the melt-quenched glasses above the crystallization temperatures. Structural and electrical properties have been investigated. Scanning electron microscopy suggests the existence of fine particles of size 20-200 nm dispersed in the annealed glass matrix. Samples are essentially ionic and stable under conductivity-temperature cycles upto 160 C. It is found that the conductivity in the nanocomposites increases with Cu2O substitution and highest conductivity is found to be 2 10-3 ?-1cm-1 for x = 0.3 at room temperature. Differential scanning calorimetry scans confirm the existence of silver iodide crystallites in all the glass-ceramic compositions.

Gupta, Neha; Dalvi, Anshuman; Awasthi, Barkha; Deva, Dinesh

2012-06-01

386

Oxidation of carbon monoxide over Cu and Ag-NaY catalysts with aqueous hydrogen peroxide  

Microsoft Academic Search

A novel oxidation reaction of CO with aqueous H2O2 over Cu-NaY (215wt%) and Ag-NaY (515wt%) catalysts has been achieved at low temperatures (5570C) 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

Zeinhom Mohamed El-Bahy; Zeinhom Mohamed

2007-01-01

387

Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy  

NASA Astrophysics Data System (ADS)

We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 C, 700 C, and 800 C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 ?m could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

2015-04-01

388

Intermetallic compounds formation and interfacial adhesion strength of Sn9Zn0.5Ag solder alloy hot-dipped on Cu substrate  

Microsoft Academic Search

The intermetallic compounds formation and interfacial adhesion strength of the Sn9Zn0.5Ag lead-free solder alloy hot-dipped on Cu substrate have been investigated by pull-off test, X-ray diffractometry, optical microscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive spectrometry. The intermetallic compounds of Ag3Sn, Cu6Sn5 and Cu5Zn8 were identified for Sn9Zn0.5Ag solder alloyCu, in which the thickness of Cu6Sn5 increased from

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

2003-01-01

389

Pressure-Free Bonding of Metallic Plates with Ni Affinity Layers Using Cu Nanoparticles  

NASA Astrophysics Data System (ADS)

This study investigated the pressure-free bonding of metallic plates using Cu nanoparticles capped by fatty acid and amine as the bonding material. The application of Ni layers to Cu plates prior to bonding significantly improved their adhesion to sintered Cu nanoparticles, resulting in higher strengths even without pressure compared to samples bonded using an ordinary Pb-rich solder at a similar temperature. The shear strength could be enhanced if the thickness of Ni layers was larger than 1 nm. The same effect was also observed when Al plates with Ni layers were bonded by Cu nanoparticles. In contrast, Ti, Mn, and Cr layers were found to be ineffective with regard to improving bond strength. Cu plates bonded by Cu nanoparticles capped by fatty acid and amine with different alkyl chain lengths from 6 to 18 showed an optimal strength with a length of 10, where the Cu particles were small enough to sinter effectively but not so small as to oxidize.

Ishizaki, Toshitaka; Akedo, Kunio; Satoh, Toshikazu; Watanabe, Ryota

2014-01-01

390

Nucleation behavior of bulk Ni-Cu alloy and pure Sb in High magnetic fields  

NASA Astrophysics Data System (ADS)

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.

Liu, Tie; Wang, Qiang; Liu, Feng; Li, Guojian; He, Jicheng

2011-04-01

391

Profiling transcriptomic response of Enchytraeus albidus to Cu and Ni: comparison with Cd and Zn.  

PubMed

Metals are among the most common contaminants in soils in Europe. Although their effects are relatively well known regarding survival and reproduction to soil invertebrates, their mode of action is poorly understood. Enchytraeus albidus is a model organism in ecotoxicology and with the development of a gene library for this species, transcriptomic studies are now possible. The main aim of this study is to understand the Cu and Ni mechanisms of response in E.albidus, in comparison with Cd and Zn (already studied). E.albidus were exposed to Cu and Ni for 4 days to the reproduction effect concentrations EC50 and EC90. Results indicate that Cu and Ni have similar mechanisms of toxicity. When comparing four elements (hierarchical clustering) it was possible to observe a clear separation of Cd from all other metals. This separation correlates with the available information from other species regarding the toxicokinetics of the tested elements. PMID:24361568

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

2014-03-01

392

Electrochemical Deposition of Ni on an Al-Cu Alloy  

NASA Astrophysics Data System (ADS)

Metallic coatings can be used to improve the wear and corrosion resistance of Al alloys. In this study, Ni was used as a candidate material for such a coating which was applied on the surface of Al 2014 alloy using electrodeposition in a standard Watt's bath. A two-step heat treatment procedure was employed that served to increase the adhesion as well as hardness of Ni. Deposition was undertaken for different durations using both galvanostatic and potentiostatic techniques. The effect of deposition parameters such as surface finish, current, potential, temperature, pH level and duration on the microstructure, adhesion, and surface properties of the Ni deposit was studied. Materials characterization was performed using scanning electron microscopy, atomic force microscopy, and x-ray diffraction. Cross-sectional scanning transmission electron microscope images revealed the fine-grained (10 nm) structure of Ni initially deposited at the Ni-Al alloy substrate. Microhardness, adhesion, and corrosion behavior of the Ni deposit were evaluated. Experimental results indicate that deposition by galvanostatic technique on 1 ?m surface finish at 45 C with a pH level maintained at 3.6 represented the optimum conditions to generate a uniform Ni deposit on Al 2014. It was concluded that Ni deposition can be used to improve the surface properties of Al alloys.

Ul-Hamid, A.; Quddus, A.; Dafalla, H.; Saricimen, H.; Al-Hadhrami, L.

2012-02-01

393

Tensile strength of thermomechanically processed Cu-9Ni-6Sn alloys  

SciTech Connect

The tensile properties of Cu-9Ni-6Sn alloys with different swaging amounts of 64, 77, and 95 pct, either solutionized and aged (S/A), were examined as a function of aging time. It was found that the aging response of Cu-9Ni-6Sn alloys varied greatly depending on the prior solution heat treatment before aging and/or different swaging amounts. The swaged S/A Cu-9Ni-6Sn alloys showed a multistage increase in tensile strength with respect to aging time, probably due to the sequential occurrence of spinodal decomposition, formation of metastable {gamma}{center{underscore}dot} precipitates, and recrystallization. The effect of different swaging amounts, ranging from 64 to 95 pct, was minimal on the aging response of S/A specimens. The prior cold working, however, appeared to favor the spinodal strengthening, comparing unswaged and swaged S/A Cu-9Ni-6Sn alloys. In 95 pct swaged D/A Cu-9Ni-6Sn alloys, the level of hardening was much less sensitive to aging time. A complex interaction between the reduction in dislocation density, the formation of equilibrium precipitates, and the reduction of Sn content in the Sn-rich segregates during an aging process is believed to be responsible for such a lean sensitivity. The increases in tensile strength of 64 and 77 pct swaged D/A Cu-9Ni-6Sn alloys were found to be much steeper than that in the 95 pct counterparts in the early and intermediate stages of aging, which is believed to be related to the relative contribution from work hardening and precipitation hardening to the strength level of D/A specimens.

Rhu, J.C.; Kim, S.S.; Jung, Y.C.; Han, S.Z.; Kim, C.J.

1999-10-01

394

Study of NiCuZn ferrite powders and films prepared by solgel method  

NASA Astrophysics Data System (ADS)

This paper reports that a series of NiCuZn ferrite powders and films are prepared by using solgel method. The effects of raw material composition and the calcinate temperature on magnetic properties of them are investigated. The NiCuZn ferrite powders are prepared by the self-propagating high-temperature synthesis method and subsequently heated at 700 C~1000 C. The results show that NiCuZn ferrite powders with single spinel phase can be formed after heat-treating at 750 C. Powders obtained from Ni0.4Cu0.2Zn0.4Fe1.9O4 gel have better magnetic properties than those from gels with other composition. After heat-treating at 900 C for 3 h, coercivity Hc and saturation magnetization Ms are 9.7 Oe (1 Oe = 80 A/m) and 72.4 emu/g, respectively. Different from the powders, NiCuZn films produced on Si (100) from the Ni0.4Cu0.2Zn0.4Fe2O4 gel formed at room temperature possess high properties. When heat-treating condition is around 600 C for 6 min, samples with low Hc and high Ms will be obtained. The minimal Hc is 16.7 Oe and Ms is about 300 emu/cm3. In comparison with the films prepared through long-time heat treating, the films prepared through short heat-treating time exhibits better soft magnetic properties.

Gao, Liang-Qiu; Yu, Guo-Jian; Wang, Ying; Wei, Fu-Lin

2011-02-01

395

Cu-Ni nano-alloy: mixed, core-shell or Janus nano-particle?  

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05739b

Guisbiers, Grgory; Khanal, Subarna; Ruiz-Zepeda, Francisco; Roque de La Puente, Jorge; Jos-Yacaman, Miguel

2014-11-01

396

Black Pad Susceptibility of the Electroless Ni Films on the Cu UBM  

NASA Astrophysics Data System (ADS)

The occurrence of black pad in the electroless Ni film during the immersion gold process is related to the surface morphology of the Ni(P) film. A nonuniform distribution of the nodule size and curvature is the crucial factor. Large nodules with small surface curvatures had higher P concentration and did not corrode, while small nodules with large surface curvatures had lower P concentration and corroded. Experiments using different types of Cu substrates suggest that the Ni(P) film black pad susceptibility increased with the defect density and/or the residual stress in the underlying substrate. Annealing the Cu substrate before the electroless Ni plating greatly reduced the black pad formation.

Kim, J. H.; Yu, Jin

2014-11-01

397

Effect of filler metal composition on the strength of yttria stabilized zirconia joints brazed with Pd-Ag-CuOx  

SciTech Connect

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.

Darsell, Jens T.; Weil, K. Scott

2008-09-08

398

Ni-Cu tetracarbide carbonyls with vacant Ni(CO) fragments as borderline compounds between molecular and quasi-molecular clusters.  

PubMed

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

Bernardi, Alessandro; Ciabatti, Iacopo; Femoni, Cristina; Iapalucci, Maria Carmela; Longoni, Giuliano; Zacchini, Stefano

2013-01-14

399

Strong work-hardening effect in a multiphase ZrCuAlNiO alloy  

NASA Astrophysics Data System (ADS)

A bulk as-cast ZrCuAlNiO alloy consisting of Zr2Cu, B2-type ZrCu, and a small quantity of ZrCu martensite phase was prepared by copper mold casting. The multiphase alloy exhibits a remarkable work-hardening effect (??y=1196MPa, ?E =5.6GPa, and ??e=2.11%) in the cycle loading-unloading compression test and possesses the high work-hardening capacity (Hc) of 1.66 and 1.58 at strain rates of 110-4 and 110-3s-1, respectively, under continuous deformation. The strong work-hardening effect of the alloy results from the continuous transformation of the ZrCu (B2, austenite) phase into the ZrCu martensite.

Qiu, Feng; Shen, Ping; Jiang, Zhonghao; Liu, Tao; Jiang, Qichuan

2008-04-01

400

Chemical and structural characterization of henryite, (Cu,Ag)3+xTe2 (x?0.40): A new structure type in the (Ag)-Cu-Te system  

NASA Astrophysics Data System (ADS)

The crystal structure of the mineral henryite, a rare copper-silver telluride, was solved using intensity data collected using a crystal from the type locality, the Campbell orebody, Bisbee, Arizona (U.S.A.). The study revealed that the structure is cubic, space group Fd 3 bar c, with cell parameters: a=12.1987(5), and V=1815.3(2)3. The refinement of an anisotropic model led to an R index of 0.0301 for 168 independent reflections. The structure consists of a face-centered cubic close-packing of Te atoms with a disordered distribution of Cu and Ag atoms in the partially-occupied tetrahedral interstices. It represents a new structure type in the Cu-Te system closely resembling the cubic structure of the well known phase A. Electron microprobe analyses of the crystal used for the structural study led to the formula (Cu1.91Ag1.47Fe0.02)?=3.40Te2, on the basis of 2 Te atoms per formula unit. On the basis of information gained from the structural and chemical characterization, the crystal-chemical formula was revised yielding (Cu,Ag)3+xTe2 (Z=16) with x?0.40 instead of [Cu3.77Ag3.01Te4] (Z=8) as previously reported.

Bindi, Luca

2014-12-01

401

Current-Induced Interfacial Reactions in Sn Solder Joints with Electroplated FeNi/Cu Substrate  

NASA Astrophysics Data System (ADS)

The effect of polarity on interfacial reactions under high-density electric current was investigated in Cu/FeNi/Sn/FeNi/Cu solder interconnects. A reverse polarity effect was found where the FeSn2 intermetallic compound (IMC) layer at the cathode grew significantly thicker than that at the anode under electric loading. Such an abnormal polarity effect was shown to result from electromigration of Fe in the direction opposite to the electron flow. At the same time, a Cu-rich layer developed next to the FeSn2 layer at the anode side. Kinetic analysis of Fe and Cu mass transport explained the differential growth of the IMCs at the two electrodes, in good agreement with the experimental data.

Zhang, X. F.; Guo, J. D.; Shang, J. K.

2010-03-01

402

Effect of Cu doping on the resistive switching of NiO thin films  

SciTech Connect

Bipolar resistive switching is observed in the GaIn/Cu:NiO film/ITO device with active layer deposited by sol-gel spin-coating. The first-principles calculations indicate that Cu dopants with valence of +1 are located at the substitutional Ni sites rather than the interstitial ones. Cu doping introduces more oxygen vacancies in the film and increases the carrier mobility, however, excessive Cu dopants may assemble at the grain boundary resulting in larger set voltage. Currentvoltage measurements indicate that the trap charge limited and space charge limited conduction dominate the high resistance state, while the low resistance state follows the Ohmic mechanism. The switching is attributed to the formation/rupture of oxygen vacancy filaments.

Li, Jian-Chang, E-mail: jcli@mail.neu.edu.cn; Hou, Xue-Yan; Cao, Qing [Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang 110819 (China)

2014-04-28

403

Solid-state intermetallic compound layer growth between copper and 95.5Sn3.9Ag0.6Cu solder  

Microsoft Academic Search

Long-term, solid-state intermetallic compound (IMC) layer growth was examined in 95.5Sn-3.9Ag-0.6Cu (wt.%)\\/copper (Cu) couples.\\u000a Aging temperatures and times ranged from 70C to 205C and from 1 day to 400 days, respectively. The IMC layer thicknesses\\u000a and compositions were compared to those investigated in 96.5Sn-3.5Ag\\/Cu, 95.5Sn-0.5Ag-4.0Cu\\/Cu, and 100Sn\\/Cu couples. The\\u000a nominal Cu3Sn and Cu6Sn5 stoichiometries were observed. The Cu3Sn layer accounted

Paul T. Vianco; Jerome A. Rejent; Paul F. Hlava

2004-01-01

404

Anisotropic permeability in ultrasoft electroplated NiFeMo/Cu microwires: The Procopiu effect  

NASA Astrophysics Data System (ADS)

The complex magnetoelastic behavior of electroplated NiFeMo/Cu microwires was analyzed by means of the magnetoimpedance and the Procopiu effects. Both phenomena are related through the circular magnetization generated by the ac and were modeled by assuming a magnetic domain and a magnetic relaxation model. From this analysis, information about the frequency and field dependencies of the circular and axial permeabilities was obtained. These results show that the magnetic anisotropy of Cu microwires galvanically coated with a NiFeMo film of 7 ?m in thickness is characterized by two circular permeability functions that are ascribed to different types of magnetic domains.

Muoz, A. G.; Schiefer, C.; Kisker, E.

2008-04-01

405

Effects of WO 3 substitution on electromagnetic properties of NiCuZn ferrite  

NASA Astrophysics Data System (ADS)

The effects of WO 3 addition on the electromagnetic properties of NiCuZn ferrite prepared by usual ceramic technology were investigated. Experimental results show that the substitution of W 6+ ions in NiCuZn ferrite can improve not only electromagnetic properties but also microstructures of sintered ceramic. Along with the reduction of average grain size, pores at grain boundaries decrease with the increasing WO 3 contents. The real part of complex permittivity ?' and the bulk density increase with the increasing amount of W 6+ ions. Meanwhile, the resonance frequency increases on the condition of deterioration of the real part of complex permeability ?'.

Zhong, Hui; Wu Zhang, Huai; Tao Zhou, Hai; Jun Jia, Li

2006-05-01

406

Exchange bias in Fe and Ni codoped CuO nanocomposites  

NASA Astrophysics Data System (ADS)

Exchange bias nanocomposites were obtained by the chemical concentration precipitation method, in which the ferrimagnetic MFe2O4 (M=Cu,Ni) particles were embedded in the antiferromagnetic (AFM) CuO matrix. The dependence of magnetization on temperature measurements show that the exchange bias effect in these composites is ascribed to the exchange coupling at the interface between the ferrimagnetic particles and spin-glass-like phase. With continuous introduction of magnetic Ni ions, the existence of domain state structure and the formation of soft magnetic phase in AFM matrix are responsible for the different behaviors of the exchange bias field and coercivity in these nanocomposites.

Liu, K. L.; Yuan, S. L.; Duan, H. N.; Zheng, X. F.; Yin, S. Y.; Tian, Z. M.; Wang, C. H.; Huo, S. X.

2010-01-01

407

Dating of Mesoproterozoic metamorphism in the Mount Isa and George Fisher Zn-Pb-Cu-Ag deposits, Australia, by paleomagnetism  

Microsoft Academic Search

The Mount Isa Zn-Pb-Cu-Ag and George Fisher Zn-Pb-Ag black-shale-hosted deposits in Queensland, Australia, are in carbonaceous and dolomitic shales of the ~1655 Ma Urquhart Formation of the Mount Isa Group that exhibit greenschist facies metamorphism. Both deposits give lead model ages of ~1655 Ma. Ar-Ar biotite and Re-Os ages for the Mount Isa copper ore are 15233 and 13724 Ma,

K. Kawasaki; D. T. Symons

2010-01-01

408

A series of M(II)Cu(II)3 stars (M = Mn, Ni, Cu, Zn) exhibiting unusual magnetic properties.  

PubMed

The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two ?2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. The title compounds are rare or sole examples of stars having these metal-ion combinations. In the cases of 1, 3, and 4, the four metal ions form a centered isosceles triangle, while the four metal ions in 2 form a centered equilateral triangle. Both the variable-temperature magnetic susceptibility and variable-field magnetization (at 2-10 K) of 1-3 have been measured and simulated contemporaneously. While the Mn(II)Cu(II)3 compound 1 exhibits ferromagnetic interaction with J = 1.02 cm(-1), the Ni(II)Cu(II)3 compound 2 and Cu(II)Cu(II)3 compound 3 exhibit antiferromagnetic interaction with J = -3.53 and -35.5 cm(-1), respectively. Variable-temperature magnetic susceptibility data of the Zn(II)Cu(II)3 compound 4 indicate very weak antiferromagnetic interaction of -1.4 cm(-1), as expected. On the basis of known correlations, the magnetic properties of 1-3 are unusual; it seems that ferromagnetic interaction in 1 and weak/moderate antiferromagnetic interaction in 2 and 3 are possibly related to the distorted coordination environment of the peripheral copper(II) centers (intermediate between square-planar and tetrahedral). DFT calculations have been done to elucidate the magnetic properties. The DFT-computed J values are quantitatively (for 1) or qualitatively (for 2 and 3) matched well with the experimental values. Spin densities and magnetic orbitals (natural bond orbitals) correspond well with the trend of observed/computed magnetic exchange interactions. PMID:25496240

Mondal, Suraj; Mandal, Shuvankar; Carrella, Luca; Jana, Arpita; Fleck, Michel; Khn, Andreas; Rentschler, Eva; Mohanta, Sasankasekhar

2015-01-01

409

The Partition Coefficients of Components in Cu-Ni-Mn Alloys  

NASA Astrophysics Data System (ADS)

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.

Bazhenov, V. E.; Pikunov, M. V.; Cheverikin, V. V.

2015-02-01

410

The Adsorption Properties of Agricultural and Forest Soils Towards Heavy Metal Ions (Ni, Cu, Zn, and Cd)  

Microsoft Academic Search

Adsorption of Cu, Cd, Ni, and Zn in single and multi-metal solutions by agricultural and forest soils was investigated in batch sorption experiments. The results showed significant differences in sorption capacities of the studied soils. The selectivity order was as follows: agricultural soil? top forest soil > bottom forest soil. The adsorption sequence Cu > Zn > Ni > Cd

Myroslav Sprynskyy; Tomasz Kowalkowski; Hlanganani Tutu; Leonard Mihaly Cozmuta; Ewa M. Cukrowska; Boguslaw Buszewski

2011-01-01

411

Effect of temperature and time on properties of Spark Plasma Sintered NiCuZn: Co ferrite  

E-print Network

process2 on structural, dielectric and magnetic properties of NiCuZn ferrite doped with cobalt. IIEffect of temperature and time on properties of Spark Plasma Sintered NiCuZn: Co ferrite K. Zehani Plasma Sintering is a powerfal method to produce fine grain dense ferrite at low temperature. However

412

Comparisons of radiation damage in He ion and proton irradiated immiscible Ag/Ni nanolayers  

NASA Astrophysics Data System (ADS)

We compare the evolution of microstructure and mechanical properties of Ag/Ni multilayers of varying layer thickness (1-200 nm) subjected to helium ion and proton irradiation at room temperature to similar dose, 2 displacements-per-atom on average. Layer structure remained intact after both types of irradiation although defects accumulated in the layers are different. Helium bubbles were the major defects in helium ion irradiated films, while dislocation loops were ubiquitous in proton irradiated multilayers. In He ion irradiated multilayers, radiation hardening was greater than that in proton irradiated specimens, and the magnitude of hardening decreased with decreasing individual layer thickness. In comparison no size dependent hardening was observed in proton irradiated films. Mechanisms of irradiation induced hardening were discussed.

Yu, K. Y.; Liu, Y.; Fu, E. G.; Wang, Y. Q.; Myers, M. T.; Wang, H.; Shao, L.; Zhang, X.

2013-09-01

413

Spreading of Sn-Ag solders on FeNi alloys  

SciTech Connect

The spreading of Sn-3Ag-xBi solders on Fe-42Ni has been studied using a drop transfer setup. Initial spreading velocities as fast as {approx}0.5 m/s have been recorded. The results are consistent with a liquid front moving on a metastable, flat, unreacted substrate and can be described by using a modified molecular-kinetic model for which the rate controlling step is the movement of one atom from the liquid to the surface of the solid substrate. Although the phase diagram predicts the formation of two Fe-Sn intermetallics at the solder/substrate interface in samples heated at temperatures lower than 513 C, after spreading at 250 C only a thin FeSn reaction layer could be observed. Two interfacial layers (FeSn and FeSn2) were found after spreading at 450 C.

Saiz, Eduardo; Hwang, C-W.; Suganuma, Katsuaki; Tomsia, Antoni P.

2003-02-28

414

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

SciTech Connect

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, SiO{sub 2}, Al{sub 2}O{sub 3}, and ZrO{sub 2} substrates with electron beams or by sputtering. The uniformity and grain growth of the thin films were observed by cross-section transmission electron microscopy (TEM) and diffraction. The thickness fluctuation determined by TEM is less than 2 nm. The backscattering spectra were obtained with an electrostatic toroidal analyzer with an energy resolution (standard deviation) of 150--200 eV, and the computer-simulated spectrum analysis has given the best-fit values of the energy straggling. The derived straggling values are compared with the theoretical values calculated from the extended Lindhard-Winther theory using the local electron density of the Hartree-Fock-Slater atomic model. Discussion is also made in terms of the short-range correlation effect proposed by Sigmund (Phys. Rev. A 26, 2497 (1982)).

Kido, Y. (Department of Physics, Ritsumeikan University, Toji-in, Kita-ku, Kyoto 603, Japan (JP)); Koshikawa, T. (Osaka Electro-Communication University, Hatsu-cho, Neyagawa, Osaka 572, Japan (JP))

1991-08-01

415

Electrodeposition mechanism and characterization of Ni-Cu alloy coatings from a eutectic-based ionic liquid  

NASA Astrophysics Data System (ADS)

The electrodeposition mechanism, microstructures and corrosion resistances of Ni-Cu alloy coatings on Cu substrate were investigated in a choline chloride-urea (1:2 molar ratio) eutectic-based ionic liquid (1:2 ChCl-urea IL) containing nickel and copper chlorides. Cyclic voltammetry showed that the onset reduction potentials for Cu (-0.32 V) and for Ni (-0.47 V) were close to each other, indicating that Ni-Cu co-deposition could be easily achieved in the absence of complexing agent which was indispensable in aqueous plating electrolyte. Chronoamperometric investigations revealed that Ni-Cu deposits followed the three-dimensional instantaneous nucleation/growth mechanism, thus producing a solid solution. The compositions, microstructures and corrosion resistances of Ni-Cu alloy coatings were significantly dependent on the deposition current densities. Ni-Cu alloy coatings were ?-Ni(Cu) solid solutions, and the coating containing 17.6 at.% Cu exhibited the best corrosion resistance because of its dense and crack-free structure.

Wang, Shaohua; Guo, Xingwu; Yang, Haiyan; Dai, JiChun; Zhu, Rongyu; Gong, Jia; Peng, Liming; Ding, Wenjiang

2014-01-01

416

Sintering studies on NiCuYSZ SOFC anode cermet processed by mechanical alloying  

Microsoft Academic Search

New 40vol%[(Cu)Ni]YSZ cermet materials processed by mechanical alloying (MA) of the row powders are prepared. The powder\\u000a compacts are sintered in air, hydrogen and inert (argon) atmospheres at a dilatometer and tubular furnace up to 1,350C.\\u000a Sintering by activated surface concept (SAS) can anticipate and enhance the densification in such powders. Stepwise isothermal\\u000a dilatometry (SID) sintering kinetics study is performed

Thomaz Augusto Guisard Restivo; Sonia Regina Homem Mello-Castanho

2009-01-01

417

Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics  

PubMed Central

Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27C and 35C, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27C and 35C ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27C and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35C wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35C wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region. PMID:24713562

Gravina, Marco Abdo; Canavarro, Cristiane; Elias, Carlos Nelson; Chaves, Maria das Graas Afonso Miranda; Brunharo, Ione Helena Vieira Portella; Quinto, Ctia Cardoso Abdo

2014-01-01

418

Correlation between glass-forming ability, thermal stability, and crystallization kinetics of Cu-Zr-Ag metallic glasses  

NASA Astrophysics Data System (ADS)

The glass-forming ability (GFA) of the Cu-Zr-Ag system is evaluated based on the large amount of literature data available and discussed in the frame of a predictive amorphization criterion which combines topological instability and electronic criteria. The correlation between GFA, thermal stability, and crystallization kinetics of (Cu0.5Zr0.5)100-xAgx (x = 0, 2, 6, and 10) metallic glasses is further investigated. The enhancement of the GFA of the alloys and the thermal stability/fragility of the supercooled liquid can be traced back to a large size effect/volume mismatch and electronic effects. However, the apparent activation energy of crystallization decreases with increasing Ag content in the alloys which may be due to a nanoscale microstructural heterogeneity induced by the Ag addition. At a certain Ag content, a small amount of AgZr crystals precipitate together with Cu10Zr7 and CuZr2 and the crystallization mechanism changes from interface-controlled one-dimensional growth to three-dimensional growth with different nucleation rates.

Song, K. K.; Gargarella, P.; Pauly, S.; Ma, G. Z.; Khn, U.; Eckert, J.

2012-09-01

419

The role of subsurface oxygen in the selectivity enhancement of ethylene epoxidation on Ag-Cu Catalysts  

NASA Astrophysics Data System (ADS)

The role of subsurface oxygen on the Ag-Cu alloy catalysts for the ethylene epoxidation reaction has been studied by means of first principles Density Functional Theory (DFT) calculations. We find that in presence of oxygen and ethylene reactants, the subsurface oxygen adsorption is energetically favorable on fcc sites under the thin oxide-like CuO layer formed at the catalyst surface. On this substrate the reaction proceeds via the formation of a common oxametallacycle precursor. The calculated activation energies show favorable energetics for the pathway leading to the formation of the desired product, ethylene oxide, with respect to the one leading to the formation of the undesired product, acetaldehyde, while the opposite order is obtained on pure Ag catalyst. These findings provide an understanding, at the atomistic level, of the selectivity enhancement of Ag-Cu alloy with respect to pure Ag catalysts. Furthermore, we find that under temperature and partial pressure conditions close to the experimental ones, the ethylenedioxy intermediate is present on the phase diagram of Ag-Cu (111) surface. Our calculations indicate, however, that the formation of this structure could poison the catalyst surface.

Linh Nguyen, Ngoc; de Gironcoli, Stefano; Piccinin, Simone

2011-03-01

420

Morphology of alloy catalysts in an oxidizing environment: Structure-sensitivity of ethylene epoxidation over Ag-Cu particles  

NASA Astrophysics Data System (ADS)

Ag-Cu alloys have been proposed as catalysts for ethylene epoxidation due to their superior selectivity compared to pure silver, the predominant catalyst for this reaction [1]. By means of density-functional theory and atomistic thermodynamics, we study the surface structure and morphology of Ag-Cu particles in thermodynamic equilibrium with an oxygen atmosphere. Contrary to the common assumption of the formation of a 2D surface alloy, we find that at temperatures and pressures of interest for practical applications the particles can display a variety of structures, including thin Cu-surface-oxides in coexistence with clean Ag. At variance with pure Ag in UHV, we find that under reactive conditions the (111) facet is not dominant. We identify different reaction pathways that will compete and/or synergetically interplay in the catalysis. In general, the reaction mechanism is structure-dependent and often the reaction does not proceed through the formation of stable intermediates, in contrast to clean Ag and the 2D alloy. Analyzing the competing reactions, we discuss how the addition of Cu improves the selectivity and stress the overall importance of accounting for the effect of ambient conditions. [1] S. Linic et al. J. Catal. 224, 148 (2004)

Piccinin, Simone; Stampfl, Catherine; Scheffler, Matthias

2009-03-01

421

Silver tracer diffusion in oriented Ag/Cu interphase boundaries and correlation to the boundary structure  

SciTech Connect

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.

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

422

Studies on Compton scattering of the Fe-C, Fe-Cu and Ni-Cu binary powder mixtures.  

PubMed

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

Luo, Guang; Hu, Xianquan

2013-09-01

423

Morphology and composition of chalcopyrite, chromite, Cu, Ni-Fe, pentlandite, and troilite in vugs of 76015 and 76215  

NASA Technical Reports Server (NTRS)

Vugs from 76015 and 76215 are lined with euhedral crystals of plagioclase, pyroxene, ilmenite, Ni-Fe, and troilite. Smaller crystals of chromite, pentlandite, and chalcopyrite occur on the surface of the troilite in 76015. Wire Cu and dendritic-metallic Cu occurs with metallic Ni-Fe and troilite in some vugs of 76215. Troilite in both samples may have crystallized from an immiscible sulfide liquid. With falling temperature, chalcopyrite, and pentlandite may have exsolved from the troilite in 76015. By contrast, metallic Cu may have formed in 76215 by thermal breakdown of a bornite, troilite, and Ni-Fe assemblage which originally crystallized from a low-Ni immiscible sulfide liquid.

Carter, J. L.; Clanton, U. S.; Laughon, R. B.; Mckay, D. S.; Usselman, T. M.; Fuhrman, R.

1975-01-01

424

Influence of sputtering pressure on the giant magnetoresistance and structure in FeCuNi granular thin films  

Microsoft Academic Search

Composition, structure and giant magnetoresistance in FexCuyNiz films prepared at different sputtering pressures were investigated. X-ray diffraction studies showed only Cu (111) peak from the Cu grain. The shifts in the d-spacing d111 of Cu indicates a progressive substitution of Ni in the Cu lattice. Similar trends in d111 of Cu observed for the samples prepared at different sputtering pressures

Ajay Tiwari; M. Senthil Kumar

2006-01-01

425

Analysis of the reaction between 60Sn40Pb solder with a Pd-Pt-Ag-Cu-Au alloy  

Microsoft Academic Search

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

D. R. Frear; J. R. Michael; P. F. Hlava

1993-01-01

426

Analysis of the reaction between 60Sn40Pb solder with a Pd-Pt-Ag-Cu-Au alloy  

Microsoft Academic Search

We present the results of a metallurgical study of a 35Pd-30Ag-14Cu-10Au10Pt-1Zn (wt. %) alloy soldered with 60Sn-40Pb for\\u000a glass-to-metal sealing applications. Mechanical tests were performed on the Pd-Ag-Cu-Au-Pt-Zn alloy and showed that it retains\\u000a ductility, with an increase in strength, after heat treatments that simulate the glass-to-metal sealing temperature profile.\\u000a Wetting characteristics of the alloy with 60Sn-40Pb solder were found

D. R. Frear; J. R. Michael; P. F. Hlava

1993-01-01

427

Specific Heat Capacities of Sn-Zn-Based Solders and Sn-Ag-Cu Solders Measured Using Differential Scanning Calorimetry  

Microsoft Academic Search

The specific heat capacities (C\\u000a p) of Sn-Zn-based solders and Sn-Ag-Cu solders have been studied using differential scanning calorimetry. The procedure of\\u000a measuring the specific heat capacity followed the standard test method designed by the American Society for Testing and Materials\\u000a (ASTM) E1269-05. The results of this work are lists of specific heat capacities of Sn-9Zn, Sn-9Zn-xAg (x=0.1, 0.5, 1,

Y. K. Wu; K. L. Lin; B. Salam

2009-01-01

428

Low-Temperature Sintering and Electromagnetic Properties of NiCuZn/CaTiO3 Composites  

NASA Astrophysics Data System (ADS)

Dense CaTiO3/Ni0.37Cu0.20Zn0.43Fe1.92O3.88 (CTO/NiCuZn) composites were prepared by the conventional solid-state reaction method and sintered at 950C. The phase compositions and surface morphologies of the composites were investigated using x-ray diffraction and scanning electron microscopy, respectively. The dielectric and magnetic properties of the composites were also investigated. The results show that the CTO/NiCuZn composites possess high dielectric constants and permeabilities, which can be used in high-frequency communications for capacitor-inductor integrating devices such as electromagnetic interference filters and antennas. With increasing NiCuZn concentration, the permeabilities of the CTO/NiCuZn composites increase, while the dielectric constants and cutoff frequencies decrease.

Yang, Haibo; Yang, Yanyan; Lin, Ying; Zhu, Jianfeng; Wang, Fen

2012-04-01

429

Ag induced photo-generated charge trapping in nanostructured CdS/Cu2S thin film for photovoltaic applications  

NASA Astrophysics Data System (ADS)

Here we report about Ag induced photo-generated charge-trapping centers in nanostructured CdS/Cu2S thin film. The nanostructured CdS/Cu2S thin films prepared by chemical route while Ag incorporation achieved by cost effective chemical ion exchange route at room temperature. The obtained thin films were annealed at 250C in air and later characterized for structural, optical and I-V characteristics. X-ray diffraction pattern confirms Ag incorporation in CdS/Cu2S heterojunction with increase in crystallite size from 32 to 50 nm. Scanning electron microscopy shows closed mouth structure of the CdS: Ag/Cu2S than CdS/Cu2S thin films. Blue shift in optical absorbance strength and energy band gap value from Eg = 2.27 to 2.10 eV is observed. Improvement in solar energy conversions efficiency from ? = 0.24 % to 0.92 % is obtained upon doping.

Taur, Vidya S.; Joshi, Rajesh A.; Sharma, Ramphal

2012-06-01

430

Spin density distribution and electronic states in ,,DMe-DCNQI...2M ,,M=Li,Ag,Cu... from high-resolution solid-state NMR  

E-print Network

Spin density distribution and electronic states in ,,DMe-DCNQI...2M ,,M=Li,Ag,Cu... from high to investigate the electronic states of the DMe-DCNQI 2M systems, where M is Li, Ag, and Cu. The Knight shift 15 N data. The Knight shift data at each atom of the DMe-DCNQI molecule give the -electron spin

Mizoguchi, Kenji

431

High-Pressure Cold-Sprayed Ni and Ni-Cu Coatings: Improved Structures and Corrosion Properties  

NASA Astrophysics Data System (ADS)

Cold spraying is a promising technique for the production of dense metallic coatings. In cold spraying, coating formation is through high velocity impacts of solid particles with high kinetic energy. During impact, particles deform plastically and adhere to the substrate, gradually building-up the coating. This makes it possible to form pure and dense coating structures. These impermeable coatings are advantageous in many applications such as those where corrosion protection is required. Nickel and nickel-copper alloys have good corrosion resistance and therefore, as dense coatings, have high potential for employment as corrosion barrier layers. In this study, the structural and corrosion properties of high-pressure cold-sprayed (HPCS) Ni and NiCu coatings are characterized. NiCu alloys are known to have good corrosion resistance in sulphuric and hydrochloric acids, whereas Ni is resistant to caustic soda and alkaline salt solutions. This study also shows the effect of heat treatments on coating properties. FESEM studies of cross-sectional samples reveal structural details of the HPCS coatings while corrosion properties are evaluated with polarization measurements. The corrosion behavior of both the bulk and substrate material is determined in order to assess the real corrosion protection potential of the coatings.

Koivuluoto, Heli; Milanti, Andrea; Bolelli, Giovanni; Lusvarghi, Luca; Vuoristo, Petri

2014-01-01

432

Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy  

SciTech Connect

The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an ?-Al matrix. The strength at room temperature and at 300C is studied as a function of solution treatment time at 490C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300C. - Highlights: The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. An imaging analysis procedure to segment phases with similar contrasts is presented. 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.

Asghar, Z., E-mail: zhdasghar@yahoo.com [Materials Division, Directorate of Technology, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Vienna University of Technology, Institute of Materials Science and Technology, Karlsplatz 13/308, A-1040 Vienna (Austria); Requena, G. [Vienna University of Technology, Institute of Materials Science and Technology, Karlsplatz 13/308, A-1040 Vienna (Austria); Zahid, G.H.; Rafi-ud-Din [Materials Division, Directorate of Technology, PINSTECH, P. O. Nilore, Islamabad (Pakistan)

2014-02-15

433

The Stellar Commodity Market: Cu, Ag, And Au In The Sun And Solar-type Stars  

NASA Astrophysics Data System (ADS)

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.

Wahlgren, Glenn Michael; Carpenter, K. G.; Nave, G.

2010-01-01

434

Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.  

PubMed

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

Coli?, Miodrag; Rudolf, Rebeka; Stamenkovi?, Dragoslav; Anzel, Ivan; Vucevi?, Dragana; Jenko, Monika; Lazi?, Vojkan; Lojen, Gorazd

2010-01-01

435

252Cf spectrum-averaged cross section for the 63Cu(n, p)63Ni reaction  

NASA Astrophysics Data System (ADS)

The 63Ni produced by the 63Cu(n, p)63Ni reaction provides a unique measure to estimate the fast-neutron fluence of the Hiroshima/Nagasaki atomic bomb. In the similarity of the fission neutron spectrum of 252Cf to that of 235U, we have measured activation cross sections of the 63Cu(n, p)63Ni reaction averaged for the 252Cf fission spectrum.

Imamura, M.; Shibata, T.; Shibata, S.; Ohkubo, T.; Satoh, S.; Nogawa, N.

1999-01-01

436

Aqueous transition-metal cations as impurities in a wide gap oxide: the Cu(2+)/Cu(+) and Ag(2+)/Ag(+) redox couples revisited.  

PubMed

The interactions of the d electrons of transition-metal aqua ions with the solvent are usually divided in short-range electronic interactions with ligand water molecules and long-range electrostatic interactions with molecules beyond the first coordination shell. This is the rationale behind the cluster continuum and QM/MM methods developed for the computation of the redox potentials. In the density functional theory based molecular dynamics (DFTMD) method, the electronic states of the complex are also allowed to mix with the extended band states of the solvent. Returning to the Cu(+) and Ag(+) oxidation reaction, which has been the subject of DFTMD simulation before, we show that coupling to the valence band states of water is greatly enhanced by the band gap error in the density functional approximation commonly used in DFTMD (the generalized gradient approximation). This effect is analyzed by viewing the solvent as a wide gap oxide and the redox active ions as electronic defects. The errors can be reduced significantly by application of hybrid functionals containing a fraction of Hartree-Fock exchange. These calculations make use of recent progress in DFTMD technology, enabling us to include sp core polarization and Hartree-Fock exchange in condensed-phase model systems. PMID:25386900

Liu, Xiandong; Cheng, Jun; Sprik, Michiel

2015-01-22

437

Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy  

NASA Astrophysics Data System (ADS)

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.

Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

2015-02-01

438

Microstructure and phase transformation of Ni46Mn33Ga17Cu4xZrx alloys  

E-print Network

Microstructure and phase transformation of Ni46Mn33Ga17Cu4xZrx 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 Ni46Mn33Ga17Cu4xZrx (x0, 2, and 4) alloys. The substitution of Cu by Zr changed the alloy

Zheng, Yufeng

439

Chemical Stability of (Ag,Cu)2Se: a Historical Overview  

NASA Astrophysics Data System (ADS)

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.

Brown, David R.; Day, Tristan; Caillat, Thierry; Snyder, G. JeffREY

2013-07-01

440

Ag-Cu alloy surfaces in an oxidizing environment: A first-principles study  

NASA Astrophysics Data System (ADS)

Recent experiments on model catalysts have shown that Ag-Cu alloys have improved selectivity with respect to pure silver for ethylene epoxidation. In this paper, we review our first-principles investigations on the (1 1 1) surface of this alloy and present new findings on other low index surfaces. We find that, for every surface orientation, the presence of oxygen leads to copper segregation to the surface. Considering the alloy to be in equilibrium with an oxygen atmosphere and accounting for the effect of temperature and pressure, we compute the surface free energy and study the stability of several surface structures. Investigating the dependence of the surface free energy on the surface composition, we construct the phase diagram of the alloy for every surface orientation. Around the temperature, pressure and composition of interest for practical applications, we find that a limited number of structures can be present, including a thin layer of copper oxide on top of the silver surface and copper-free structures. Different surface orientations show a very similar behavior and in particular a single layer with CuO stoichiometry, significantly distorted when compared to a layer of bulk CuO, has a wide range of stability for all orientations. Our results are consistent with, and help explain, recent experimental measurements.

Piccinin, Simone; Stampfl, Catherine; Scheffler, Matthias

2009-06-01

441

First-principles investigation of Ag-Cu alloy surfaces in an oxidizing environment  

NASA Astrophysics Data System (ADS)

By means of density-functional theory, together with concepts from atomistic thermodynamics, we present a theoretical procedure for describing the structure and stoichiometry of a binary alloy in contact with a surrounding gas phase environment. We apply the approach to the Ag-Cu alloy in an oxygen atmosphere, for which recent results report a superior selectivity for ethylene epoxidation compared to pure silver, the predominant catalyst for this reaction. We first show that the presence of oxygen leads to copper segregation to the surface. Then, considering the surface free energy as a function of the surface Cu composition, we construct the ``convex hull''. By including the dependence of the surface free energy of the oxygen chemical potential, we determine the phase diagram of the alloy as a function of temperature, pressure, and Cu surface content. We predict that for conditions typical of the epoxidation reaction, a number of structures can be present on the surface of the alloy including the clean silver surface, thin copper-oxide-like structures, and thick copper oxides. These findings are consistent with, and help explain the recent experimental results. We envisage this approach will be useful and generally applicable for the study of other alloys in contact with a gas or liquid phase.

Piccinin, Simone; Stampfl, Catherine; Scheffler, Matthias

2008-03-01

442

Microstructural evolution during aging of an Al-Cu-Li-Ag-Mg-Zr alloy  

NASA Technical Reports Server (NTRS)

Alloys in the Al-Cu-Li Ag-Mg subsystem were developed that exhibit desirable combinations of strength and ductility. These Weldalite (trademark) alloys, are unique for Al-Cu-Li alloys in that with or without a prior cold stretching operation, they obtain excellent strength-ductility combinations upon natural and artificial aging. This is significant because it enables complex, near-net shape products such as forgings and super plastically formed parts to be heat treated to ultra-high strengths. On the other hand, commercial extrusions, rolled plates and sheets of other Al-Cu-Li alloys are typically subjected to a cold stretching operation before artificial aging to the highest strength tempers to introduce dislocations that provide low-energy nucleation sites for strengthening precipitates such as the T(sub 1) phase. Th