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1

Photoelectron spectroscopy of mixed metal cluster anions: NiCu , NiAg , NiAg2 , and Ni2Ag  

E-print Network

Negative ion photoelectron spectra of NiCu , NiAg , NiAg2 , and Ni2Ag are presented for electron binding s * character. The photoelectron spectra of the trimers, NiAg2 and Ni2Ag , are remarkably similar to those. The photoelectron spectra of the coinage metal clusters have been studied6,7 for Cun and Agn (n 1­10) and Aum (m 1

Lineberger, W. Carl

2

Theoretical explanation of Ag\\/Cu and Cu\\/Ni nanoscale multilayers softening  

Microsoft Academic Search

Relationship between metallic multilayers hardness and monolayer thickness has been investigated and explained for electroplated Ag\\/Cu and Cu\\/Ni multilayers using a modified Thomas–Fermi–Dirac electron theory. Experiments reveal that the peak hardness of Ag\\/Cu multilayers occurs at the monolayer thickness of about 25nm, while the peak hardness of Cu\\/Ni multilayers occurs at about 50nm. Critical monolayer thickness corresponding to the peak

Fengzhang Ren; Shiyang Zhao; Wuhui Li; Baohong Tian; Litao Yin; Alex A. Volinsky

2011-01-01

3

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

4

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.

5

Primary solidification phases of the Sn-rich Sn-Ag-Cu-Ni quaternary system  

NASA Astrophysics Data System (ADS)

The eutectic and near-eutectic Sn-Ag-Cu solders are the most promising lead-free solders, and nickel is frequently used as the barrier layer material. Nickel dissolves into the molten Sn-Ag-Ni alloy during the soldering process, and the ternary solder becomes a Sn-Ag-Cu-Ni quaternary melt near the nickel substrate. Liquidus projection is the projection of the liquidus trough and it delineates the boundaries of various primary solidification phases. Information of liquidus projection is helpful for understanding the alloys’ solidification behavior. This study prepared the Sn-Ag-Cu-Ni alloys of various compositions at the Sn-rich corner. The alloys were melted at higher temperatures and solidified in air. The solidified alloys were metallographically examined to determine the phases formed, especially the primary solidification phases. No ternary or quaternary compounds were found. The knowledge of the primary solidification phases, phase formation sequences, and reaction temperatures determined in this study were put together with all of the available liquidus projections of the constituent ternary systems to determine the primary solidification phases of the quaternary Sn-Ag-Cu-Ni system at the Sn-rich corner.

Chang, Cheng-An; Chen, Sinn-Wen; Chiu, Chen-Nan; Huang, Yu-Chih

2005-08-01

6

Effect of Ni Layer Thickness on Intermetallic Formation and Mechanical Strength of Sn-Ag-Cu Solder Joint  

Microsoft Academic Search

Au\\/Ni\\/Cu under bump metallization (UBM) in tape ball grid array (TBGA) package with Sn-Ag-Cu solder is commonly used for electronic IC packaging due to environmental and business concerns. The drawback of Sn-Ag-Cu solder on selective Ni\\/Au plating (SMOBC) TBGA is a weakened solder joint, which provides the embrittlement and affects long-terms reliability. The ability of electronic packages and assemblies to

Kelvin Pun; Poh Leng Eu; M. N. Islam; C. Q. Cui

2008-01-01

7

Thermodynamic Calculation of Phase Equilibria in the Sn-Ag-Cu-Ni-Au System  

NASA Astrophysics Data System (ADS)

Sn-Ag-Cu base solders are the most promising candidates to substitute for Sn-Pb eutectic solder. Gold (Au) coatings are used to protect conductor surfaces from oxidation and thereby to promote solderability, and Ni is often used as a diffusion barrier layer between lead-free solders and substrates to restrict the growth of intermetallic compound layers. In the present work, thermodynamic calculations of phase equilibria in the Sn-Ag-Cu-Ni-Au system, which is of importance for developing lead-free solders, are carried out using the calculation of phase diagrams (CALPHAD) method. Substitutional solution and sublattice models are used to describe the solution and intermediate phases, respectively. Some examples of thermodynamic calculation are presented, and it is shown that the phase diagrams, liquidus projection, and thermodynamic properties can be predicted based on the present calculations.

Liu, X. J.; Wang, C. P.; Gao, F.; Ohnuma, I.; Ishida, K.

2007-11-01

8

IMC Growth at the Interface of Sn-2.0Ag-2.5Zn Solder Joints with Cu, Ni, and Ni-W Substrates  

NASA Astrophysics Data System (ADS)

Growth of intermetallic compounds (IMC) at the interface of Sn-2.0Ag-2.5Zn solder joints with Cu, Ni, and Ni-W substrates have been investigated. For the Cu substrate, a Cu5Zn8 IMC layer with Ag3Sn particles on top was observed at the interface; this acted as a barrier layer preventing further growth of Cu-Sn IMC. For the Ni substrate, a thin Ni3Sn4 film was observed between the solder and the Ni layer; the thickness of the film increased slowly and steadily with aging. For the Ni-W substrate, a thin Ni3Sn4 film was observed between the solder and Ni-W layer. During the aging process a thin layer of the Ni-W substrate was transformed into a bright layer, and the thickness of bright layer increased with aging.

Liang, Jiaxing; Wang, Haozhe; Hu, Anmin; Li, Ming

2014-11-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

10

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

11

Reactions of Sn-4.0Ag-0.5Cu on Cu and Electroless Ni Substrate in Premelting Soldering Process  

NASA Astrophysics Data System (ADS)

Early formation of Cu6Sn5 and (Ni,Cu)6Sn5 during soldering was investigated. Sn4.0Ag0.5Cu solder on Cu and electroless Ni-Au substrate was quenched in ice water after the initial stage of melting, and the solder-substrate interface was analyzed by transmission electron microscopy and energy-dispersive x-ray spectroscopy. At the contacting point, Cu3Sn and Cu6Sn5 were found at the solder-Cu substrate interface, while (Ni,Cu)6Sn5 and Ni2SnP were identified at the solder-electroless Ni interface. The contacting points were confirmed as the sites of heterogeneous nucleation. TEM analysis suggested that the nucleation of both intermetallic compounds can be attributed to diffusion-induced crystallization. Details of the early interfacial reactions are discussed.

Chung, C. Key; Chen, Y. J.; Yang, T. L.; Kao, C. R.

2013-06-01

12

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

13

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

NASA Astrophysics Data System (ADS)

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

Peng, Chung-Nan; Duh, Jenq-Gong

2009-12-01

14

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

15

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

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

2007-01-01

16

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

17

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

2014-11-01

18

Adsorption of Ni, Pd, Pt, Cu, Ag and Au on the Fe3O4(111) surface  

NASA Astrophysics Data System (ADS)

The interaction of Group 10 and 11 transition metals with the magnetite (111) surface has been investigated using the GGA + U density functional theory and periodic slab surface models. It was found that these transition metals adsorb stronger on an oxygen-terminated magnetite (111) surface than on an iron-terminated surface. On an oxygen-terminated surface, the adsorption strength is in the order of Ni > Pt ~ Cu > Pd > Ag ~ Au. In contrast, the order on an iron-terminated surface is Ni > Pt ~ Cu > Au > Pd ~ Ag. The adsorption strength was found to correlate well with the average lengths of metal-oxygen bonds. The magnetite (111) surfaces largely modify the electronic structures of the transition metals. Compared to their density of states in bulk structures, the atomically adsorbed transition metals have narrower d bands, and their d-band centers are closer to the Fermi levels. This implies the higher activities of the atomically adsorbed transition metals.

Yu, Xiaohu; Tian, Xinxin; Wang, Shengguang

2014-10-01

19

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

20

Photocatalytic removal of M 2+ ( Ni 2+, Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Ag +) over new catalyst CuCrO 2  

Microsoft Academic Search

The metal ions M2+ (Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Ag+) are potentially toxic. Their electro deposition has been carried out in aqueous air-equilibrated CuCrO2 suspension upon visible illumination. The delafossite CuCrO2 is p-type semiconductor characterized by a low band gap (1.28eV) and a long-term chemical stability. The corrosion rate is found to be 10?2?molm?2month?1 in aqua regia. The oxide

W. Ketir; A. Bouguelia; M. Trari

2008-01-01

21

Influence of Palladium Thickness on the Soldering Reactions Between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) Surface Finish  

NASA Astrophysics Data System (ADS)

This study provides a comparison of the influence of Pd(P) thickness on reactions during soldering with the Sn-3Ag-0.5Cu alloy. Soldering was carried out in an infrared-enhanced conventional reflow oven, and a multiple reflow test method (up to ten cycles) was performed. With increasing Pd(P) thickness, the (Cu,Ni)6Sn5 grew more slowly at the solder/Ni(P) interface, while the Ni2SnP/Ni3P bilayer became predominant after the first reflow. These three intermetallics, i.e., (Cu,Ni)6Sn5, Ni2SnP, and Ni3P, gradually coarsened as the number of reflow cycles increased. Furthermore, an additional (Ni,Cu)3Sn4 layer appeared between (Cu,Ni)6Sn5 and Ni2SnP, especially for the case of a thicker Pd(P) layer (0.2 ?m). The attachment of the (Ni,Cu)3Sn4 to the Ni2SnP, however, was fairly poor, and a series of microcracks formed along the (Ni,Cu)3Sn4/Ni2SnP interface. To quantify the mechanical response of the interfacial microstructures, shear testing was conducted at two different shear speeds (0.0007 m/s and 2 m/s). The results indicated that the interfacial strength and the Pd(P) thickness were strongly correlated.

Wu, W. H.; Lin, C. S.; Huang, S. H.; Ho, C. E.

2010-11-01

22

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

23

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

NASA Astrophysics Data System (ADS)

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.

Asta, Mark; Foiles, Stephen M.

1996-02-01

24

Glass formation in a (Ti,Zr,Hf)-(Cu,Ni,Ag)Al high-order alloy system by mechanical alloying  

Microsoft Academic Search

In this work, glass formation under high-energy ball milling was investigated for a (Ti0.33Zr0.33Hf0.33)50(Ni0.33Cu0.33Ag0.33)40Al10 high-order alloy system with equiatomic substitution for early and late transition-metal contents. For comparison, an amorphous alloy ribbon with the same composition was prepared using the melt-spinning method as well. Structural features of the samples were characterized using x-ray diffraction, transmission electron microscopy, and differential scanning

L. C. Zhang; Z. Q. Shen; J. Xua

2003-01-01

25

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

NASA Astrophysics Data System (ADS)

Ternary compounds CeMSb 2 and CeM'Bi 2 have been synthesized by arc melting followed by a heat treatment at 400, 600 or 800°C for 300 h. Bismuth-containing compounds have been observed for the first time. From X-ray powder diffractometry all compounds were found to be isotypic with ZrCuSi 2-type. In CeMn 0.9Sb 2, the manganese sublattice orders ferromagnetically at T˜130 K, and the cerium sublattice shows additional ordering at ˜20 K. CeMSb 2 (M=Fe, Ni, Pd, Cu, Ag, Au, Zn) are antiferromagnets below T=12 K. In the paramagnetic regime, the cerium atom adopts the Ce- 2F {5}/{2} tripositive groundstate. CeCu 0.9Bi 2 is also an antiferromagnet, whereas for Ce(Ag,Zn)Bi 2 no magnetic order was encountered. X-Ray absorption spectroscopy shows that Ce in all compounds CeMSb 2 and CeMBi 2 is in the trivalent, or nearly trivalent, state.

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

1996-02-01

26

Solid-Solid Reaction Between Sn-3Ag-0.5Cu Alloy and Au/Pd(P)/Ni(P) Metallization Pad with Various Pd(P) Thicknesses  

NASA Astrophysics Data System (ADS)

The effect of Pd(P) thickness on the solid-solid reaction between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) at 180°C was investigated in this study. The reaction was conducted after reflow, thereby removing the Au/Pd finish before the solid-state reaction. The reaction products included (Cu,Ni)6Sn5, Ni2SnP, and Ni3P, and their growth strongly depended on the Pd(P) thickness, especially for the former phases [i.e., (Cu,Ni)6Sn5 and Ni2SnP]. As the Pd(P) thickness increased from 0 ?m, to 0.1 ?m, to 0.22 ?m, the (Cu,Ni)6Sn5 exhibited a needle-like dense layer, chunk-like morphology, and discontinuous morphology, respectively. The alternative phase (Ni2SnP) behaved in a manner opposite to that of (Cu,Ni)6Sn5, growing with a discontinuous morphology to a dense layer with increasing Pd(P) thickness. However, this strong dependence disappeared when the solder joints were subsequently subjected to solid-state aging. The (Cu,Ni)6Sn5 and Ni2SnP both became layered structures for all cases examined. A high-speed ball shear (HSBS) test was conducted to quantify the mechanical response of the interfacial microstructures. The HSBS test results showed that any initial difference in shear strength caused by the various Pd(P) thicknesses could be reduced after the solid-state aging, which is consistent with the microstructural evolution observed. The mechanical strength of the solder joints was decreased due to the presence of a bi-intermetallic structure of (Cu,Ni)6Sn5/Ni2SnP at the interface. Detailed analysis of the growth of (Cu,Ni)6Sn5 and Ni2SnP is also provided.

Ho, C. E.; Wu, W. H.; Hsu, L. H.; Lin, C. S.

2012-01-01

27

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

NASA Astrophysics Data System (ADS)

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

Lee, Tae-Kyu; Duh, Jeng-Gong

2014-07-01

28

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

NASA Astrophysics Data System (ADS)

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

Lee, Tae-Kyu; Duh, Jeng-Gong

2014-11-01

29

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. 300°C and exhibited similar H2 yield. It is found that the severe coking problem for the Ni-loaded PCO catalyst was alleviated significantly if Ag, Cu or Mn is co-loaded. Among them, the addition of Mn is the most effective in reducing carbon formation.

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

2011-06-01

30

A study on interfacial reactions between electroless NiP under bump metallization and 95.5Sn4.0Ag0.5Cu alloy  

Microsoft Academic Search

Even though electroless Ni-P and Sn-Ag-Cu solders are widely used materials in flip-chip bumping technologies, interfacial\\u000a reactions of the ternary Cu-Ni-Sn system are not well understood. The growth of intermetallic compounds (IMCs) at the under\\u000a bump metallization (UBM)\\/solder interface can affect solder-joint reliability, so analysis of IMC phases and understanding\\u000a their growth kinetics are important. In this study, interfacial reactions

Young-Doo Jeon; Sabine Nieland; Andreas Ostmann; Herbert Reichl; Kyung-Wook Paik

2003-01-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

32

Microstructural evolution of intermetallic compounds in Sn–3.5Ag–X (X = 0, 0.75Ni, 1.0Zn and 1.5In)\\/Cu solder joints during liquid aging  

Microsoft Academic Search

In this paper, the microstructural evolution of IMCs in Sn–3.5Ag–X (X=0, 0.75Ni, 1.0Zn, 1.5In)\\/Cu solder joints and their growth mechanisms during liquid aging were investigated by microstructural observations and phase analysis. The results show that two-phase (Ni3Sn4 and Cu6Sn) IMC layers formed in Sn–3.5Ag–0.75Ni\\/Cu solder joints during their initial liquid aging stage (in the first 8min). While after a long

Jie Chen; Jun Shen; Shiqiang Lai; Dong Min; Xiaochuan Wang

2010-01-01

33

Molecular-dynamics simulations of glass formation and crystallization in binary liquid metals: Cu-Ag and Cu-Ni  

E-print Network

Molecular-dynamics simulations of glass formation and crystallization in binary liquid metals: Cu to obtain an atomistic description of the melting, glass formation, and crystallization processes in metal glass formation. S0163-1829 99 05205-4 I. INTRODUCTION Metal glasses were prepared1 by the Duwez group

Goddard III, William A.

34

Effects of Pd(P) Thickness on the Microstructural Evolution Between Sn-3Ag-0.5Cu and Ni(P)/Pd(P)/Au Surface Finish During the Reflow Process  

NASA Astrophysics Data System (ADS)

The microstructural evolution between Sn-3Ag-0.5Cu (SAC305) solder and Ni(P)/Pd(P)/Au finish during the reflow process was investigated for various Pd(P) thicknesses (0 ?m to 0.6 ?m). The reflow process was carried out in a belt-conveying reflow oven with peak temperature of 260°C. In the early stages of the reflow process, the Pd(P) layer either dissolved or spalled in the form of (Pd,Ni)Sn4 into the molten solder, leaving behind an Ni2SnP/Ni3P bilayer on the Ni(P) layer. From the dissolution of the spalled (Pd,Ni)Sn4 particles during the reflow process, the solubility of Pd in the molten SAC305 solder in the reflow process was estimated to be 0.18 wt.% to 0.25 wt.%. Regardless of the ratio of solder volume to pad opening size, the Ni2SnP layer that formed in the early stage of reflow had a significant influence on the subsequent formation and growth of (Cu,Ni)6Sn5 at the solder interface. As the Ni2SnP layer became thicker with increasing Pd(P) thickness, the formation of (Cu,Ni)6Sn5 became increasingly sluggish and occurred only at locations where the Ni2SnP layer was locally thin or discontinuous, leading to a discontinuous morphology of (Cu,Ni)6Sn5. This was attributed to the Ni2SnP layer that became an increasingly effective barrier to Ni diffusion with increasing thickness. Based on the experimental results, this study suggests detailed mechanisms underlying the effects of the Pd(P) thickness on the morphology and growth of the (Cu,Ni)6Sn5 formed during the reflow process.

Chung, Bo-Mook; Baek, Yong-Ho; Choi, Jaeho; Huh, Joo-Youl

2012-12-01

35

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

36

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

37

Ag-Cu-Pb System  

NSDL National Science Digital Library

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

Kattner, Ursula

2003-01-01

38

Ag-Cu-Sn System  

NSDL National Science Digital Library

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

Kattner, Ursula

2003-01-01

39

The SnAgCu solder joint integrity in WLCSP for green conversion  

Microsoft Academic Search

WLCSP with Ni\\/Cu UBM and SnAgCu solder interconnect comply completely with European ROHS regulation. SnAgCu solder exhibits best solder joint thermal fatigue life in organic laminate BGA type package to organic PCB during gentle TCT condition, but whether means it can also work well in silicone die level package to organic PCB due to larger CTE mismatch during temperature cycling,

Jeffrey C. B. Lee; Chi-sheng Chung; Chin-Chiang Liu; Ho-Ming Tong

2005-01-01

40

Fabrication of Bi 2Sr 2Ca 1Cu 2O x superconductor using metallic substrate tape clad with Ag  

NASA Astrophysics Data System (ADS)

With the intentions of the reduction of material cost and the improvement of mechanical properties, Ag/Ni and Ag/Stainless Steel (SUS) clad tapes were prepared as substrate materials for the fabrication of Bi 2Sr 2Ca 1Cu 2O x (Bi-2212) superconducting tape. Bi-2212 formed on the Ag/Ni clad tape with a 10 ?m Ag layer thickness showed good superconducting properties of Tc=88 K and Jc (4.2 K, 10 T)=1.7×10 5 A/cm 2, comparable to those of Bi-2212 tape fabricated using pure Ag tape. However, Bi-2212 formed on the Ag/Ni clad tape with a 5 ?m Ag layer thickness showed deteriorated properties due to the transfer of Cu and Ni across the Ag layer. The Ag/SUS clad tape did not work as a substrate material, because the Ag layer was eroded, forming many holes, and hence could not prevent a severe reaction between Bi-2212 and SUS. The Jc of the Bi-2212/Ag/Ni tape started to degrade at ?=0.2-0.3% in the bending test. A tensile test indicated that the Ag/Ni clad tape had about three times larger yield strength than pure Ag tape. From these results, it is expected that the Bi-2212/Ag/Ni tape has a much improved stress tolerance over the conventional Bi-2212/Ag tape.

Nemoto, Y.; Fujii, H.; Kitaguchi, H.; Kumakura, H.; Togano, K.; Shima, K.

2001-02-01

41

Electromigration failure mechanisms for SnAg3.5 solder bumps on Ti /Cr-Cu/Cu and Ni(P )/Au metallization pads  

NASA Astrophysics Data System (ADS)

The electromigration behavior of SnAg3.5 solder bumps is investigated under the current densities of 1×104A /cm2 and 5×103A /cm2 at 150°C. Different failure modes were observed for the two stressing conditions. When stressed at 1×104A /cm2, damage occurred in both the anode/chip side and the cathode/chip side. However, failure happened only in the cathode/chip side under the stressing of 5×103A /cm2. A three-dimensional simulation of the current-density distribution was performed to provide a better understanding of the current-crowding behavior in the solder bump. The current-crowding effect was found to account for the failure in the cathode/chip side. In addition, both the temperature increase and the thermal gradients were measured during the two stressing conditions. The measured temperature increase due to Joule heating was as high as 54.5°C, and the thermal gradient reached 365°C /cm when stressed by 1×104A/cm2. This induced thermal gradient may cause atoms to migrate from the chip side to the substrate side, contributing to the failure in the anode/chip side. Moreover, the formation of intermetallic compounds in the anode/chip side may also be responsible for the failure in the anode/chip side.

Shao, T. L.; Chen, Y. H.; Chiu, S. H.; Chen, Chih

2004-10-01

42

Electromigration failure mechanisms for SnAg3.5 solder bumps on Ti/Cr-Cu/Cu and Ni(P)/Au metallization pads  

SciTech Connect

The electromigration behavior of SnAg3.5 solder bumps is investigated under the current densities of 1x10{sup 4} A/cm{sup 2} and 5x10{sup 3} A/cm{sup 2} at 150 deg. C. Different failure modes were observed for the two stressing conditions. When stressed at 1x10{sup 4} A/cm{sup 2}, damage occurred in both the anode/chip side and the cathode/chip side. However, failure happened only in the cathode/chip side under the stressing of 5x10{sup 3}A/cm{sup 2}. A three-dimensional simulation of the current-density distribution was performed to provide a better understanding of the current-crowding behavior in the solder bump. The current-crowding effect was found to account for the failure in the cathode/chip side. In addition, both the temperature increase and the thermal gradients were measured during the two stressing conditions. The measured temperature increase due to Joule heating was as high as 54.5 deg. C, and the thermal gradient reached 365 deg. C/cm when stressed by 1x10{sup 4}A/cm{sup 2}. This induced thermal gradient may cause atoms to migrate from the chip side to the substrate side, contributing to the failure in the anode/chip side. Moreover, the formation of intermetallic compounds in the anode/chip side may also be responsible for the failure in the anode/chip side.

Shao, T.L.; Chen, Y.H.; Chiu, S.H.; Chen Chih [Department of Material Science and Engineering, National Chiao Tung University, Hsin-chu 300, Taiwan (China)

2004-10-15

43

The Reliability of Microalloyed Sn-Ag-Cu Solder Interconnections Under Cyclic Thermal and Mechanical Shock Loading  

NASA Astrophysics Data System (ADS)

In this study, the performance of three microalloyed Sn-Ag-Cu solder interconnection compositions (Sn-3.1Ag-0.52Cu, Sn-3.0Ag-0.52Cu-0.24Bi, and Sn-1.1Ag-0.52Cu-0.1Ni) was compared under mechanical shock loading (JESD22-B111 standard) and cyclic thermal loading (40 ± 125°C, 42 min cycle) conditions. In the drop tests, the component boards with the low-silver nickel-containing composition (Sn-Ag-Cu-Ni) showed the highest average number of drops-to-failure, while those with the bismuth-containing alloy (Sn-Ag-Cu-Bi) showed the lowest. Results of the thermal cycling tests showed that boards with Sn-Ag-Cu-Bi interconnections performed the best, while those with Sn-Ag-Cu-Ni performed the worst. Sn-Ag-Cu was placed in the middle in both tests. In this paper, we demonstrate that solder strength is an essential reliability factor and that higher strength can be beneficial for thermal cycling reliability but detrimental to drop reliability. We discuss these findings from the perspective of the microstructures and mechanical properties of the three solder interconnection compositions and, based on a comprehensive literature review, investigate how the differences in the solder compositions influence the mechanical properties of the interconnections and discuss how the differences are reflected in the failure mechanisms under both loading conditions.

Mattila, Toni T.; Hokka, Jussi; Paulasto-Kröckel, Mervi

2014-11-01

44

Stress evolution during annealing of Cu/Au, Cu/Ag and Au/Ag bilayers.  

PubMed

Experimental observations of the measurements of the average force F per width (i.e., F/w) during annealing of Au/Cu, Cu/Au, Ag/Cu, Cu/Ag, Au/Ag and Ag/Au bilayers attached to silicon substrate are reported. Systems with total thickness of 12 nm and thicknesses of films of 6 nm are investigated. The total force per width in a system was determined in-situ by the substrate curvature measurement method with the laser scanning technique during deposition and annealing. Significant stress evolution during the first cycle of heating was observed for all samples. It was found that during the first annealing cycle, irreversible changes occur in layers and increases the interface roughness. An increase in the interface roughness modifies the coefficients of elastic deformation of layers. Subsequent annealing cycles do not cause major changes in the stress in a bilayer. PMID:23421258

Chocyk, D; Proszynski, A; Gladyszewski, G

2012-11-01

45

Elastic properties of antiperovskite-type Ni-rich nitrides MNNi 3 (M=Zn, Cd, Mg, Al, Ga, In, Sn, Sb, Pd, Cu, Ag and Pt) as predicted from first-principles calculations  

NASA Astrophysics Data System (ADS)

We have performed accurate ab initio total energy calculations using the full-potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA) for the exchange-correlation potential to systematically investigate elastic properties of 12 synthesized and hypothetical cubic antiperovskite-type Ni-rich nitrides MNNi 3, where M are Zn, Cd, Mg, Al, Ga, In, Sn, Sb, Pd, Cu, Ag and Pt. As a result, the optimized lattice parameters, independent elastic constants ( Cij), bulk-, shear- and tetragonal shear moduli, Cauchy’s pressure and some indexes of elastic anisotropy, as well as the numerical estimations of Young’s modulus, Poisson’s ratio and Pugh's indicator of brittle/ductile behavior for the corresponding polycrystalline MNNi 3 (in the Voigt-Reuss-Hill approximation) were obtained and analyzed in comparison with the available theoretical and experimental data.

Bannikov, V. V.; Shein, I. R.; Ivanovskii, A. L.

2010-11-01

46

Effect of Reflow Profiles on the Board Level Drop Reliability of Pb-Free (SnAgCu) BGA Assemblies  

Microsoft Academic Search

The mechanical reliability of BGA assemblies is sensitive to the intermetallic compounds that are formed at the solder\\/base metal interfaces. With Pb-free assembly using SnAgCu solder alloys, the reflow temperatures are higher and may degrade the performance of the BGA assemblies compared to tin-lead. In this study, BGA packages with Sn3.8Ag0.7Cu solder balls and either Ni\\/Au or Cu substrates were

Anand Lal; Edwin Bradley; Jignesh Sharda

2005-01-01

47

Fabrication of conductive interconnects by Ag migration in Cu-Ag core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

Fabrication of conductive nanoparticle films is observed in Cu-Ag core-shell nanoparticles by fast diffusion of Ag at 220 °C from particle surfaces, leading to the formation of sintered necks of Ag at the initial particle-particle contacts. Transmission electron microscopy showed that the necks were pure Ag and that particle surfaces away from the contacts were nearly Ag-free. The extent of neck formation is controllable by the choice of initial Ag thickness. Analysis of the thermodynamics of the Ag-Cu system and the relative diffusivities of Ag and Cu provide criteria for fabrication of other core-shell two-phase systems by the same mechanism.

Kim, Suk Jun; Stach, Eric A.; Handwerker, Carol A.

2010-04-01

48

Nanoindentation of Ag/Ni multilayered thin films  

NASA Astrophysics Data System (ADS)

Nanoindentation was used to study the mechanical properties of Ag/Ni multilayered thin films. Both the hardness and the elastic modulus of the multilayered thin films had values between those for homogeneous Ag and Ni thin films. The trend in the hardness with layer repeat length can be explained by the effects of both the stress and the microstructure. No evidence for interfacial effects on hardness was found. A decrease in modulus at the smallest repeat lengths was compared with literature data on the elastic constants of Ag/Ni multilayers.

Ruud, J. A.; Jervis, T. R.; Spaepen, F.

1994-05-01

49

Formation of an unconventional Ag valence state in Ag2NiO2  

NASA Astrophysics Data System (ADS)

The Ag ion in the recently synthesized novel material Ag2NiO2 adopts an extremely unusual valency of (1)/(2) , leaving the Ni ion as 3+ , rather than the expected 2+ . Using first-principles calculations, we show that this mysterious subvalent state emerges due to a strong bonding-antibonding interaction between the two Ag layers that drives the lower band beneath the O p complex, eliminating the possibility of a conventional Ag 1+ valence state. The strong renormalization of the specific heat coefficient ? is likely due to strong spin fluctuations that stem from nearly complete compensation of the ferromagnetic (metallic double exchange and 90° superexchange) and antiferromagnetic (conventional superexchange via Ni-O-Ag-O-Ni path) interactions.

Johannes, M. D.; Streltsov, S.; Mazin, I. I.; Khomskii, D. I.

2007-05-01

50

Formation of Intermetallic Compounds Between Liquid Sn and Various CuNi x Metallizations  

NASA Astrophysics Data System (ADS)

Interfacial reactions between liquid Sn and various Cu-Ni alloy metallizations as well as the subsequent phase transformations during the cooling were investigated with an emphasis on the microstructures of the reaction zones. It was found that the extent of the microstructurally complex reaction layer (during reflow at 240°C) does not depend linearly on the Ni content of the alloy metallization. On the contrary, when Cu is alloyed with Ni, the rate of thickness change of the total reaction layer first increases and reaches a maximum at a composition of about 10 at.% Ni. The reaction layer is composed of a relatively uniform continuous (Cu,Ni)6Sn5 reaction layer (a uniphase layer) next to the NiCu metallizations and is followed by the two-phase solidification structures between the single-phase layer and Sn matrix. The thickness of the two-phase layer, where the intermetallic tubes and fibers have grown from the continuous interfacial (Cu,Ni)6Sn5 layer, varies with the Ni-to-Cu ratio of the alloy metallization. In order to explain the formation mechanism of the reaction layers and their observed kinetics, the phase equilibria in the Sn-rich side of the SnCuNi system at 240°C were evaluated thermodynamically utilizing the available data, and the results of the Sn/Cu x Ni1- x diffusion couple experiments. With the help of the assessed data, one can also evaluate the minimum Cu content of Sn-(Ag)-Cu solder, at which (Ni,Cu)3Sn4 transforms into (Cu,Ni)6Sn5, as a function of temperature and the composition of the liquid solders.

Vuorinen, V.; Yu, H.; Laurila, T.; Kivilahti, J. K.

2008-06-01

51

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

52

Interfacial Reactions Between Pb-Free Solders and In/Ni/Cu Multilayer Substrates  

NASA Astrophysics Data System (ADS)

This study investigates the interfacial reactions between Sn-3.0wt.% Ag-0.5wt.%Cu (SAC) and Sn-0.7wt.%Cu (SC) on In/Ni/Cu multilayer substrates using the solid-liquid interdiffusion bonding technique. Samples were reflowed first at 160°C, 180°C, and 200°C for various periods, and then aged at 100°C for 100 h to 500 h. The scalloped Cu6Sn5 phase was formed at the SAC/In/Ni/Cu and SC/In/Ni/Cu interfaces. When the reflowing temperatures were 160°C and 180°C, a ternary Ni-In-Sn intermetallic compound (IMC) was formed when the samples were further aged at 100°C. This ternary Ni-In-Sn IMC could be the binary Ni3Sn4 phase with extensive Cu and In solubilities, or the ternary Sn-In-Ni compound with Cu solubility, or even a quaternary compound. As the reflow temperature was increased to 200°C, only one Cu6Sn5 phase was formed at the solder/substrate interface with the heat treatment at 100°C for 500 h. Mechanical test results indicated that the formation of the Ni-In-Sn ternary IMC weakened the mechanical strength of the solder joints. Furthermore, the solid-liquid interdiffusion (SLID) technique in this work effectively reduced the reflow temperature.

Yen, Yee-Wen; Liou, Wei-Kai; Wei, Hong-Yao; Lee, Chiapyng

2009-01-01

53

Monoligated Monovalent Ni: the 3dNi 9 Manifold of States of NiCu and Comparison to the  

E-print Network

Monoligated Monovalent Ni: the 3dNi 9 Manifold of States of NiCu and Comparison to the 3d9 States fluorescence investigation of the low-lying electronic states of NiCu has allowed the observation of four out include NiH,1-9 NiCu,10,11 NiAu,12,13 AlNi,13,14 NiF,15-20 NiCl,21-26 NiBr,27,28 NiI,29,30 and NiCN.31

Morse, Michael D.

54

Metamorphosis of ultrathin Ni oxide nanostructures on Ag(100)  

NASA Astrophysics Data System (ADS)

The evolution of the morphology of Ni-oxide nanostructures on Ag(100) as a function of temperature has been followed experimentally by scanning tunneling microscopy (STM) and theoretically by density-functional theory (DFT) calculations. After reactive deposition at room temperature and annealing at 450 K, the NiO(2 × 1) phase embedded into the Ag substrate is formed due to kinetic stabilization during growth. The (2 × 1) structure is replaced by the thermodynamically more stable NiO(100)(1 × 1) phase, also embedded into the Ag substrate, for annealing at T > 500 K. As shown by DFT modeling and in agreement with experimental STM contrast, the formation of second-layer NiO patches below the NiO(1 × 1) monolayer is an effective means of strain relief in the NiO(1 × 1) monolayer islands. For T > 600 K, the increased possibilities of mass transport lead to an intriguing surface morphology called “labyrinth” phase, with narrow high-aspect ratio embedded NiO(1 × 1)-type islands. The latter are stabilized by the interaction of the NiO borders with the Ag(100) substrate via double-layer boundary lines, which according to the DFT calculations provide the essential elements of this thermodynamic ground state.

Steurer, W.; Allegretti, F.; Surnev, S.; Barcaro, G.; Sementa, L.; Negreiros, F.; Fortunelli, A.; Netzer, F. P.

2011-09-01

55

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

56

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

57

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

58

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

59

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

60

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

NASA Astrophysics Data System (ADS)

The early aging Cu precipitations in Fe—3%Cu and Fe—3%Cu—4%Ni ternary alloys are investigated by molecular dynamics (MD) simulations. The results show that the average size of Cu clusters in Fe—3%Cu—4%Ni alloy is larger than that in Fe—3%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 Cu—Ni interactions, which is verified by first-principles calculations based on density functional theory (DFT).

Zhu, Lu-Shan; Zhao, Shi-Jin

2014-06-01

61

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

62

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

Microsoft Academic Search

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

Luhua Xu; John H. L. Pang

2006-01-01

63

Analysis of front metal contact for plated Ni/Cu silicon solar cell  

NASA Astrophysics Data System (ADS)

Commercial solar cells with screen printed front contacts are formed by using Ag paste. This has caused high shading loss and low conductivity because of high contact resistance. One of the front metal contact solar cells is Ni/Cu metal contact, made by using plating that is easily available so as to allow simple and inexpensive production techniques to be applied to mass production. Ni has been shown to be a suitable barrier to Cu diffusion into the silicon. Also, it is possible to use Ni silicide for the sintering process. Ni silicide has been reported have compositions of Ni2Si (200°C ˜ 300°C), NiSi (300°C ˜ 700°C), and NiSi2 (700°C ˜ 900°C). Especially, NiSi has been shown to have low contact resistance (14 ˜ 16 mW·cm) between surface and electrode. Finally, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) analysis show experimental results in which electroless plating of Ni and Ni silicide can be seen. The efficiency of plated Ni/Cu contact solar cells was improved by 0.8% over that of screen printed solar cells.

Lee, Jae Doo; Kwon, Hyuk Yong; Lee, Soo Hong

2011-12-01

64

Ion-exchange synthesis of Ag/Ag2S/Ag3CuS2 ternary hollow microspheres with efficient visible-light photocatalytic activity.  

PubMed

Ternary Ag/Ag2S/Ag3CuS2 hollow microspheres were synthesized via an in situ ion-exchange method using Cu7S4 hollow submicrospheres as the template. The as-obtained Ag/Ag2S/Ag3CuS2 composite exhibited a well-defined uniform hollow microsphere morphology with an average diameter of about 1.3 ?m. The photocatalytic property of the as-prepared Ag/Ag2S/Ag3CuS2 hollow microsphere composite was investigated by the decomposition of methyl orange (MO) under visible light irradiation (? > 420 nm). It was shown that the photocatalytic activity of the Ag/Ag2S/Ag3CuS2 hollow microsphere was higher than those of Ag/Ag2S, Cu2O, Cu7S4 and P25 for the photodegradation of MO under visible light irradiation. Radical scavenger experiments demonstrated that superoxide radicals and holes were the main reactive species for MO degradation. PMID:24336962

Xing, Chaosheng; Zhang, Yuan; Wu, Zhudong; Jiang, Deli; Chen, Min

2014-02-21

65

STUDIES ON THE THERMIONIC VACUUM ARC DISCHARGES IN THE VAPORS OF Cu-Ag AND Cu-Sn ALLOYS  

Microsoft Academic Search

The thermionic vacuum arc (TVA) discharges were studied in the vapors of various metals (Zn, Pb, Ag, Sn, Cu, Au, Co, Ti) and Cu-Ag and Cu-Sn alloys. Cu-Ag and Cu-Sn alloys in various mass ratios were prepared by using the TVA, and the TVA discharges were generated in the vapors of these alloys. The volt-ampere characteristics of the TVA discharges

T. Akan; N. Ekem; S. Pat; R. Vladoiua; G. Musab

66

Pb-free Sn-Ag-Cu ternary eutectic solder  

DOEpatents

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

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

1996-06-18

67

Extended fine Auger structure spectroscopy of Ag and Cu  

NASA Astrophysics Data System (ADS)

The extended fine Auger structure (EXFAS) spectra of Ag(111) and polycrystalline Cu have been recorded by use of both angle-resolved and angle-integrated electron spectrometers. Extended fine Auger structure associated with both the Ag N23 and Ag M45 core-hole states is observed. The temperature variation (between 150 and 600 K) of both Ag extended fine-structure spectra is reported. The Cu M23?V EXFAS of polycrystalline Cu is compared to the Cu M23 electron-energy-loss fine structure and to calculated Cu L2 extended x-ray-absorption fine structure (EXAFS). The angle-integrated results are interpreted in terms of an EXAFS-like origin of the extended fine Auger structure, although strong contributions from various diffraction processes may also be contributing. The extended fine Auger structure is found to depend on the extent of angular integration used in the data collection. This is tentatively explained in terms of changes in the relative contributions of EXAFS-like and diffraction mechanisms. Further experimental tests of the origin of this signal are proposed.

de Crescenzi, M.; Hitchcock, A. P.; Tyliszczak, T.

1989-05-01

68

The constitution and phase stability of overlapping melt trails in Ag Cu alloys produced by continuous laser melt quenching  

Microsoft Academic Search

Coatings consisting of overlapping trails melted with a scanning CW CO2 laser have been produced on Ag-Cu alloys with the following compositions: Cu 17 at. pct Ag; Cu 37 at. pct Ag; Cu 61.7 at.\\u000a pct Ag; Cu 71.8 at. pct Ag; and Cu 82 at. pct Ag. The laser beam was scanned at a velocity of 34 cm s1

David G. Beck; Stephen M. Copley; Michael Bass

1982-01-01

69

The constitution and phase stability of overlapping melt trails in Ag Cu alloys produced by continuous laser melt quenching  

Microsoft Academic Search

Coatings consisting of overlapping trails melted with a scanning CW CO2 laser have been produced on Ag-Cu alloys with the following compositions: Cu 17 at. pct Ag; Cu 37 at. pct Ag; Cu 61.7 at. pct Ag; Cu 71.8 at. pct Ag; and Cu 82 at. pct Ag. The laser beam was scanned at a velocity of 34 cm s1

David G. Beck; Stephen M. Copley; Michael Bass

1982-01-01

70

Ag@Ni core-shell nanowire network for robust transparent electrodes against oxidation and sulfurization.  

PubMed

Silver nanowire (Ag NW) based transparent electrodes are inherently unstable to moist and chemically reactive environment. A remarkable stability improvement of the Ag NW network film against oxidizing and sulfurizing environment by local electrodeposition of Ni along Ag NWs is reported. The optical transmittance and electrical resistance of the Ni deposited Ag NW network film can be easily controlled by adjusting the morphology and thickness of the Ni shell layer. The electrical conductivity of the Ag NW network film is increased by the Ni coating via welding between Ag NWs as well as additional conductive area for the electron transport by electrodeposited Ni layer. Moreover, the chemical resistance of Ag NWs against oxidation and sulfurization can be dramatically enhanced by the Ni shell layer electrodeposited along the Ag NWs, which provides the physical barrier against chemical reaction and diffusion as well as the cathodic protection from galvanic corrosion. PMID:24961495

Eom, Hyeonjin; Lee, Jaemin; Pichitpajongkit, Aekachan; Amjadi, Morteza; Jeong, Jun-Ho; Lee, Eungsug; Lee, Jung-Yong; Park, Inkyu

2014-10-01

71

Effects of rare-earth additions on the microstructure and strength of Cu–Ag composites  

Microsoft Academic Search

The filamentary composites of Cu–6wt.% Ag and Cu–12wt.% Ag containing rare-earth elements with different contents were prepared by casting and cold drawing. The microstructure was observed and the tensile strength determined for the composites at different draw ratios. The rare-earth elements of 0.05–0.15wt.% in Cu–6wt.% Ag and 0.1–0.3wt.% in Cu–12wt.% Ag result in large spacing or low density of the

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

2008-01-01

72

Electrochemical Ag doping into YBa 2Cu 3O y , ceramics using Ag-??Al 2O 3 ionic conductor  

Microsoft Academic Search

The electrochemical Ag doping into YBa2Cu3Oy ceramics was carried out at 400–600 °C using a Ag-??-Al2O3 (ionic conductor)\\/YBa2Cu3Oy\\/Ag-??-Al2O3 sandwich electrolysis system. Ag was doped into the grain boundaries of the superconducting oxide ceramics, and Ba2+ was released. The electrochemical doping resulted in some destruction in the grain boundaries of the YBa2Cu3Oy and the production of Ag metal, when the doping

Yasumichi Matsumoto; Micho Koinuma; Hideki Yamamoto; Teruaki Nishimori

1997-01-01

73

Ag3Sn plate formation in the solidification of near-ternary eutectic Sn-Ag-Cu  

NASA Astrophysics Data System (ADS)

Near-ternary eutectic Sn-Ag-Cu alloys are leading lead-free candidate solders for various applications. These alloys yield three phases upon solidification: ?-Sn,Ag3Sn, and Cu6Sn5. Large, plate-like, pro-eutectic Ag3Sn structures can grow rapidly within the liquid phase, potentially adversely affecting the mechanical behavior and reducing the fatigue life of solder joints. This article reports on the formation of such plates in Sn-Ag-Cu solder balls and joints and demonstrates how large Ag3Sn plate formation can be minimized.

Kang, Sung K.; Shih, Da-Yuan; Donald, Ny.; Henderson, W.; Gosselin, Timothy; Sarkhel, Amit; Charles Goldsmith, Ny.; Puttlitz, Karl J.; Choi, Won Kyoung

2003-06-01

74

Resistance switching properties of planner Ag\\/Li:NiO\\/Ag structures induced by swift heavy ion irradiation  

Microsoft Academic Search

We report on the resistance switching induced by swift heavy ion (SHI) irradiation in lithium doped nanostructured NiO thin films grown on MgO (100) substrates by chemical solution deposition. Hysteresis in current-voltage curves were observed for the Ag\\/Li:NiO\\/Ag planner structures irradiated with 100 MeV Ag+14 ions, whereas pristine samples showed only linear I-V characteristics. No preferential oxygen loss from the

S. J. Trivedi; K. H. Bhavsar; U. N. Trivedi; S. A. Khan; D. K. Avasthi

2009-01-01

75

Wetting of Cu Pads by Bi-2.6Ag-xCu Alloys and Phase Equilibria in the Ag-Bi-Cu System  

NASA Astrophysics Data System (ADS)

The phase equilibrium in the Ag-Bi-Cu system was experimentally determined at 573 K, 773 K, and 973 K by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) on annealed alloys and liquid/solid couples. The experimental results indicate that the mutual solubility of the components is limited. Based on the present results and literature data, phase equilibria in the Ag-Bi-Cu system were thermodynamically assessed. Wetting of Bi-2.6Ag-xCu alloys on Cu substrates was studied with the sessile drop method in the presence of flux at 573 K and 623 K. It was found that the wetting to non-wetting transition corresponds to the solubility limit of Cu in liquid. Selected solidified solder-substrate couples were cross-sectioned and their interfacial microstructure examined with SEM-EDS. There are no reaction products at the interface, but the copper surface becomes rough because of dissolution by liquid solder.

Fima, Przemyslaw; Garzel, Grzegorz; Sypie?, Anna

2014-07-01

76

Electromagnetic shielding and corrosion resistance of electroless Ni–P\\/Cu–Ni multilayer plated polyester fabric  

Microsoft Academic Search

Nickel–phosphorus\\/copper–nickel (Ni–P\\/Cu–Ni) multilayers are electroless deposited onto polyester fabric as a function of the deposition time of Ni–P and compared with Ni–P and Cu–Ni deposits. Their surface morphology, microstructure and composition are analyzed by using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive X-ray (EDX). Their electromagnetic interference (EMI) shielding effectiveness (SE) is evaluated and corrosion resistance is characterized

S. X. Jiang; R. H. Guo

2011-01-01

77

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

Microsoft Academic Search

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

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

2002-01-01

78

Ag 3 Sn plate formation in the solidification of near-ternary eutectic Sn-Ag-Cu  

Microsoft Academic Search

Near-ternary eutectic Sn-Ag-Cu alloys are leading lead-free candidate solders for various applications. These alloys yield\\u000a three phases upon solidification: ?-Sn,Ag3Sn, and Cu6Sn5. Large, plate-like, pro-eutectic Ag3Sn structures can grow rapidly within the liquid phase, potentially adversely affecting the mechanical behavior and reducing\\u000a the fatigue life of solder joints. This article reports on the formation of such plates in Sn-Ag-Cu solder

Sung K. Kang; Da-Yuan Shih; Ny. Donald; W. Henderson; Timothy Gosselin; Amit Sarkhel; N. Y. Charles Goldsmith; Karl J. Puttlitz; Won Kyoung Choi

2003-01-01

79

LEEM study of nucleation, growth, and decay of Ag nanowires on Cu(110)  

Microsoft Academic Search

Low energy electron microscopy (LEEM) has been used to study the nucleation, growth, and ripening of Ag nanowires on Cu(110). Previous STM and LEED studies of Ag on the Cu(110) surface have shown that for a Ag coverage of below 0.3 ML, Ag forms a surface alloy, followed by the formation of a 2D Ag(111) flat superstructure through dealloying at

Indrajith Senevirathne; Ezra Bussmann; Gary Kellogg; Richard Kurtz; Phillip Sprunger

2007-01-01

80

Recrystallization of Cu-poor CuInS{sub 2} assisted by metallic Cu or Ag  

SciTech Connect

We monitor the recrystallization of Cu-poor CuInS{sub 2} thin films assisted by pure Cu or pure Ag by means of real-time synchrotron-based polychromatic X-ray diffraction. In both cases a new microstructure is formed accompanied by an increase in grain size. In the case of Cu, the onset temperature of the thin-film recrystallization is higher than 370 deg. C. In the case of Ag, the thin-film recrystallization comes to an end at 270 deg. C. The Ag-assisted recrystallization occurs in the presence of the body-centered cubic beta-Ag{sub 2}S phase. We find that domain growth and diffusion of silver into the film occur simultaneously. - Graphical abstract Keywords: Recrystallization; Thin-film solar cells; Energy-dispersive x-ray diffraction: In-situ monitoring by means of energy-dispersive X-ray diffraction of the thin-film recrystallization of Cu-poor CuInS{sub 2} assisted by metallic Ag.

Rodriguez-Alvarez, Humberto, E-mail: Humberto.rodriguez@helmholtz-berlin.d [Helmholtz Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Mainz, Roland; Marsen, Bjoern; Schock, Hans-Werner [Helmholtz Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

2010-04-15

81

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

Microsoft Academic Search

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

Charles Zhang; Jong-Kai Lin; Li Li

2001-01-01

82

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

Microsoft Academic Search

Magnetic interlayer coupling between two Co layers across Cu\\/Ni 30 Cu 70 \\/Cu(100) was investigated by the surface magneto-optic Kerr effect. The Ni 30 Cu 70 layer at the center of the Cu layer was shown to shift the peak positions, rather than to change the strength, of the magnetic interlayer coupling. The density of states near the Fermi level

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

1999-01-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

84

Enhanced Cu Concentration in Ge Containing Ni at 500°C  

Microsoft Academic Search

Penning has shown that at 500°C, Cu penetrates into Ni-doped Ge (containing ?1016 Ni atoms cm?3) to a concentration more than 10 times its thermal equilibrium value. We have confirmed this observation and extended the experiments with the following results. At 500°C the rate of Cu64 penetration (in Ni saturated samples) indicates an effective diffusion coefficient Deff of ?2×10?8 cm2?sec

A. G. Tweet; W. W. Tyler

1958-01-01

85

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

86

Corrosion of Ti-STS dissimilar joints brazed by a Ag interlayer and Ag-Cu-(Pd) alloy fillers  

NASA Astrophysics Data System (ADS)

Corrosion behavior of dissimilar brazed joints between titanium Gr. 2 (Ti) and S31254 stainless steel (STS) was investigated. For the study, a Ag interlayer and two Ag-base eutectic alloys, 72Ag-28Cu and 66.2Ag-25.8Cu-8Pd (wt.%), were introduced as a diffusion control layer and fillers, respectively, between the base materials. The joints commonly had a layered structure of Ti(base)/TiAg/Ag solid solution/STS(base), but the one brazed by the Ag-Cu-Pd filler was slightly alloyed with the noble Pd elements over the Ag-rich solid solution region. A series of corrosion test experiments in a sea water revealed that a corrosion of TiAg layer and a stress-induced cracking at the TiAg/Ag solid solution interface were dominant due to a galvanic attack, but notably the Ti-STS dissimilar joint's resistance to corrosion was significantly improved by alloying the Pd in the joint. The corrosion behavior of such dissimilar metal joints was discussed based on galvanic corrosion effect.

Lee, M. K.; Park, J. J.; Lee, G. J.; Lee, J. G.; Kim, D. W.; Lim, C. H.; Rhee, C. K.; Lee, Y. B.; Lee, J. K.; Hong, S. J.

2011-02-01

87

Core-shell structure disclosed in self-assembled Cu-Ag nanoalloy particles  

NASA Astrophysics Data System (ADS)

Core-shell segregation of copper and silver in self-assembled, free nanoparticles is established by means of photoelectron spectroscopy in a wide range of relative Cu-Ag concentrations. These conclusions are based on the analysis of the photon-energy-dependent changes of the Cu 3d and Ag 4d photoelectron spectra. The nanoparticles are formed from mixed Cu-Ag atomic vapor created by magnetron sputtering of a bimetallic sample in a gas-aggregation cluster source. Even at similar Cu and Ag fractions in the primary vapor the surface of the nanoparticles is dominated by silver. Only at low Ag concentration copper appears on the surface of nanoparticles. For the latter case, a threefold decrease in the Ag 4d spin-orbit splitting has been detected. The specific component distribution and electronic structure changes are discussed in connection with the earlier results on Cu-Ag macroscopic and surface alloys.

Tchaplyguine, M.; Andersson, T.; Zhang, Ch.; Björneholm, O.

2013-03-01

88

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

89

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

Microsoft Academic Search

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

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

2008-01-01

90

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

91

High-durable AgNi nanomesh film for a transparent conducting electrode.  

PubMed

Uniform metal nanomesh structures are promising candidates that may replace of indium-tin oxide (ITO) in transparent conducting electrodes (TCEs). However, the durability of the uniform metal mesh has not yet been studied. For this reason, a comparative analysis of the durability of TCEs based on pure Ag and AgNi nanomesh, which are fabricated by using simple transfer printing, is performed. The AgNi nanomesh shows high long-term stability to oxidation, heat, and chemicals compared with that of pure Ag nanomesh. This is because of nickel in the AgNi nanomesh. Furthermore, the AgNi nanomesh shows strong adhesion to a transparent substrate and good stability after repeated bending. PMID:24840606

Kim, Han-Jung; Lee, Su-Han; Lee, Jihye; Lee, Eung-Sug; Choi, Jun-Hyuk; Jung, Jun-Ho; Jung, Joo-Yun; Choi, Dae-Geun

2014-09-24

92

Rapid Expansion Rates of 25? m Ag, Au, and Cu Wires Driven by a Current Rise Rate of 10^10 A/s for <100 ns  

NASA Astrophysics Data System (ADS)

We present data from wire explosion experiments driven by a current pulse with a rate of rise of 10^10 A/s per wire. This is similar to prepulse conditions in wire-array z-pinches on Z at Sandia National Laboratories, Albuquerque. Materials investigated include Ag, Al, Au, Cu, Mo, Ni, Pt, Ti, W, Zn, and others. Of these materials, Ag, Au, and Cu wire explosions are among the most uniform and rapid, with diameter expansion rates of 1-4.5 ? m/ns. The characteristics of Ag, Au, and Cu wire explosions will be discussed in detail, including the effects of insulating coatings^1, which increased the expansion rates by factors of 2-5. Comparisons will be made to other materials, with an emphasis on neighboring periodic table elements Ni and Pt, which expand much more slowly and non-uniformly. ^1D.B. Sinars et al., Phys. Plasmas 7, 429 (2000).

Chandler, K. M.; Hu, Min; Sinars, D. B.; Shelkovenko, T. A.; Pikuz, S. A.; Duselis, P. U.; Greenly, J. B.; Hammer, D. A.; Kusse, B. R.

2000-10-01

93

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

Microsoft Academic Search

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

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

2008-01-01

94

Surface relief of TiNiCu thin films  

Microsoft Academic Search

TiNiCu thin film shape memory alloys are potential materials for microactuator. In our previous research, the various natural surface relief of crystallized TiNiCu thin film was observed, and it was related with compositions and the sputtering deposition conditions. In order to understand the origin and nature of the surface relief, the temperature-resistance measurement, X-ray diffraction and atomic fore microscopic study

Xiulan Cheng; Dong Xu; Bingchu Cai; Li Wang; Jian Chen; Gang Li; Shi Xu

2001-01-01

95

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

96

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

SciTech Connect

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

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

1996-12-31

97

Giant magnetoimpedance effect in sputtered single layered NiFe film and meander NiFe/Cu/NiFe film  

NASA Astrophysics Data System (ADS)

Giant magnetoimpedance (GMI) effect on NiFe thin film is very promising due to its application in developing the magnetic field sensors with highly sensitivity and low cost. In this paper, the single layered NiFe thin film and NiFe/Cu/NiFe thin film with a meander structure are prepared by the MEMS technology. The influences of sputtering parameters, film structure and conductor layer width on GMI effect in NiFe single layer and meander NiFe/Cu/NiFe film are investigated. Maximum of the GMI ratio in single layer and sandwich film is 5% and 64%, respectively. The results obtained are useful for developing the high-performance magnetic sensors based on NiFe thin film.

Chen, L.; Zhou, Y.; Lei, C.; Zhou, Z. M.; Ding, W.

2010-10-01

98

Irradiation induced dissolution of Cu and growth of Ag nanoclusters in Cu\\/Ag ion-exchanged soda-lime glass  

Microsoft Academic Search

Complex metal nanoclusters of Cu\\/Ag are formed in a soda-lime glass matrix by sequential copper and silver ion-exchange followed by ion irradiation. Optical absorption measurements showed signature of copper clusters alone in the Cu\\/Ag ion-exchanged sample. Irradiation of the ion-exchanged sample with He+ ions of energy 100 keV of different fluences resulted in the growth of the silver clusters with,

D. Manikandan; S. Mohan; P. Magudapathy; K. G. M Nair

2002-01-01

99

Comparison of the early stages of condensation of Cu and Ag on Mo/100/ with Cu and Ag on W/100/  

NASA Technical Reports Server (NTRS)

The adsorption and condensation of Cu and Ag, up to several monolayers in thickness, onto Mo(100) has been observed at pressures below 2 times 10 to the -10th torr in a study that used combined LEED, Auger, TDS (Thermal Desorption Spectroscopy), and work function measurements in a single experimental setup. The results show that Cu behaves similarly on Mo(100) and W(100) substrates, while some differences are found for Ag adsorption.

Soria, F.; Poppa, H.

1980-01-01

100

Influence of Chemical Modifiers on Ag, Cu, and Si Atomic Absorption Signals  

NASA Astrophysics Data System (ADS)

The influence of tungsten, zirconium, and palladium compounds used as chemical modifiers on the configuration of Ag, Cu, and Si analytical signals was studied. It was suggested that the analyte atomization curve parameters change as a result of matrix effects of the selected modifiers. The prospects of using these modifiers in work with Ag, Cu, and Si were discussed

Kulik, A. N.; Buhay, A. N.; Illiashenko, V. Yu.

2014-03-01

101

Experimental and thermodynamic assessment of Sn-Ag-Cu solder alloys  

Microsoft Academic Search

Sn-rich alloys in the Sn-Ag-Cu system are being studied for their potential as Pb-free solders. Thus, the location of the\\u000a ternary eutectic involving L, (Sn), Ag3Sn and Cu6Sn5 phases is of critical interest. Phase diagram data in the Sn-rich corner of the Sn-Ag-Cu system are measured. The ternary\\u000a eutectic is confirmed to be at a composition of 3.5 wt.% Ag,

K.-W. Moon; W. J. Boettinger; U. R. Kattner; F. S. Biancaniello; C. A. Handwerker

2000-01-01

102

Resistance switching properties of planner Ag/Li:NiO/Ag structures induced by swift heavy ion irradiation  

SciTech Connect

We report on the resistance switching induced by swift heavy ion (SHI) irradiation in lithium doped nanostructured NiO thin films grown on MgO (100) substrates by chemical solution deposition. Hysteresis in current-voltage curves were observed for the Ag/Li:NiO/Ag planner structures irradiated with 100 MeV Ag{sup +14} ions, whereas pristine samples showed only linear I-V characteristics. No preferential oxygen loss from the film surface has been detected in on-line elastic recoil detection analysis. This suggests that change in the defect density created by SHI irradiation that may contribute to the metallic filaments play a major role as compared to the interfacial oxygen vacancies in resistance switching of NiO.

Joshi, U. S.; Trivedi, S. J.; Bhavsar, K. H. [Department of Physics, School of Sciences, Gujarat University, Ahmedabad 380 009 (India); Trivedi, U. N. [Department of Instruments and Control Engineering, Vishwakarma Government Engineering College, Chandkheda, Gandhinagar 382 424 (India); Khan, S. A.; Avasthi, D. K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

2009-04-01

103

Resistance switching properties of planner Ag/Li:NiO/Ag structures induced by swift heavy ion irradiation  

NASA Astrophysics Data System (ADS)

We report on the resistance switching induced by swift heavy ion (SHI) irradiation in lithium doped nanostructured NiO thin films grown on MgO (100) substrates by chemical solution deposition. Hysteresis in current-voltage curves were observed for the Ag/Li:NiO/Ag planner structures irradiated with 100 MeV Ag+14 ions, whereas pristine samples showed only linear I-V characteristics. No preferential oxygen loss from the film surface has been detected in on-line elastic recoil detection analysis. This suggests that change in the defect density created by SHI irradiation that may contribute to the metallic filaments play a major role as compared to the interfacial oxygen vacancies in resistance switching of NiO.

Joshi, U. S.; Trivedi, S. J.; Bhavsar, K. H.; Trivedi, U. N.; Khan, S. A.; Avasthi, D. K.

2009-04-01

104

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

105

Study of Interfacial Reactions Between Sn(Cu) Solders and Ni-Co Alloy Layers  

NASA Astrophysics Data System (ADS)

The interfacial reactions between electroplated Ni- yCo alloy layers and Sn(Cu) solders at 250°C are studied. For pure Co layers, CoSn3 is the only interfacial compound phase formed at the Sn(Cu)/Co interfaces regardless of the Cu concentration. Also, the addition of Cu to Sn(Cu) solders has no obvious influence on the CoSn3 compound growth at the Sn(Cu)/Co interfaces. For Ni-63Co layers, (Co,Ni,Cu)Sn3 is the only interfacial compound phase formed at the Sn(Cu)/Ni-63Co interfaces. Unlike in the pure Co layer cases, the Cu additives in the Sn(Cu) solders clearly suppress the growth rate of the interfacial (Co,Ni,Cu)Sn3 compound layer. For Ni-20Co layers, the interfacial compound formation at the Sn(Cu)/Ni-20Co interfaces depends on the Cu content in the Sn(Cu) solders and the reflow time. In the case of high Cu content in the Sn(Cu) solders (Sn-0.7Cu and Sn-1.2Cu), an additional needle-like interfacial (Ni x ,Co y ,Cu1- x- y )3Sn4 phase forms above the continuous (Ni x ,Cu y ,Co1- x- y )Sn2 compound layer. The Ni content in the Ni- yCo layer can indeed reduce the interfacial compound formation at the Sn(Cu)/Ni- yCo interfaces. With pure Sn solders, the thickness of the compound layer monotonically decreases with the Ni content in the Ni- yCo layer. As for reactions with the Sn(Cu) solders, as the compound thickness decreases, the Ni content in the Ni- yCo layers increases.

Huang, K. C.; Shieu, F. S.; Huang, T. S.; Lu, C. T.; Chen, C. W.; Tseng, H. W.; Cheng, S. L.; Liu, C. Y.

2010-11-01

106

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 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

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

2013-11-01

107

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 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

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

108

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

109

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

SciTech Connect

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

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

2011-09-15

110

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

111

Surface relief of TiNiCu thin films  

NASA Astrophysics Data System (ADS)

TiNiCu thin film shape memory alloys are potential materials for microactuator. In our previous research, the various natural surface relief of crystallized TiNiCu thin film was observed, and it was related with compositions and the sputtering deposition conditions. In order to understand the origin and nature of the surface relief, the temperature-resistance measurement, X-ray diffraction and atomic fore microscopic study were performed. For Ti48.4Ni46.3Cu5.3 thin films, the transformation temperatures are below 0 degree(s)C, and the natural surface is smooth at 12 degree(s)C since the microstructure is austenite. For Ti51Ni44Cu5 thin films, two typical kinds of surface relief, e.g., chrysanthemum and rock candy, were observed at 12 degree(s)C. The chrysanthemum on the martensitic block relief is Ti-rich G.P. zone and will not disappear in thermal cycles later. It is also found that the Ti-rich G.P. zone is related with the thin films formed under lower sputtering Ar pressure. The rock candy relief is a typical martensite surface relief and will disappear when heating to the austenite phase. During crystallization process, the inherent compressive stress introduced under the condition of higher sputtering pressure is helpful to the transition from G.P. zones to Ti2(NiCu) precipitates and the increase of the transformation temperatures.

Cheng, Xiulan; Xu, Dong; Cai, Bingchu; Wang, Li; Chen, Jian; Li, Gang; Xu, Shi

2001-10-01

112

Dispersed fluorescence spectroscopy of AlNi, NiAu, and PtCu  

Microsoft Academic Search

Dispersed fluorescence studies of AlNi, NiAu, and PtCu have been performed, providing spectroscopic information about the ground and low-lying excited electronic states. Vibrational frequencies are reported for the ground X 2?5\\/2 state of all three molecules. In the case of AlNi, fluorescence to all five of the states originating from the 3dNi93sAl2?2 manifold has been observed. For both NiAu and

Jacqueline C. Fabbi; Lars Karlsson; Jon D. Langenberg; Quinton D. Costello; Michael D. Morse

2003-01-01

113

Dispersed fluorescence spectroscopy of AlNi, NiAu, and PtCu  

Microsoft Academic Search

Dispersed fluorescence studies of AlNi, NiAu, and PtCu have been performed, providing spectroscopic information about the ground and low-lying excited electronic states. Vibrational frequencies are reported for the ground X 2Delta5\\/2 state of all three molecules. In the case of AlNi, fluorescence to all five of the states originating from the 3dNi93sAl2sigma2 manifold has been observed. For both NiAu and

Jacqueline C. Fabbi; Lars Karlsson; Jon D. Langenberg; Quinton D. Costello; Michael D. Morse

2003-01-01

114

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

115

Phase-dependent corrosion of titanium-to-stainless steel joints brazed by Ag-Cu eutectic alloy filler and Ag interlayer  

NASA Astrophysics Data System (ADS)

The electrochemical corrosion properties of Ti-STS dissimilar joints brazed by a 72Ag-28Cu alloy filler and an Ag interlayer were studied in a 3.5% NaCl solution using potentiodynamic polarization and ac impedance spectroscopy. For a joint with a layered structure of Ti(base)/TiAg/Ag solid solution/Ag-Cu eutectic/STS(base), galvanic corrosion mostly occurred in the TiAg phase with a severe material loss, indicating that the TiAg layer acted as an anode in the galvanic couple in the layered joint. The Ag-rich solid solution layer was also corroded to a certain extent, but the corrosion in this layer was dominated by the selective pitting corrosion of the eutectic Cu-rich phase. With an increase in the brazing temperature, the Cu-rich phases disappeared owing to the enhanced isothermal solidification effect, leading to an improvement of the corrosion resistance.

Lee, M. K.; Park, J. J.; Lee, J. G.; Rhee, C. K.

2013-08-01

116

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 ?·s·q(-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

117

LEEM study of nucleation, growth, and decay of Ag nanowires on Cu(110)  

NASA Astrophysics Data System (ADS)

Low energy electron microscopy (LEEM) has been used to study the nucleation, growth, and ripening of Ag nanowires on Cu(110). Previous STM and LEED studies of Ag on the Cu(110) surface have shown that for a Ag coverage of below 0.3 ML, Ag forms a surface alloy, followed by the formation of a 2D Ag(111) flat superstructure through dealloying at one monolayer. For Ag coverages above 1.3 ML , nanowires of Ag(110), with widths/heights of 12 nm / 2nm, grow along the [110] crystallographic direction with highly anisotropic aspect ratios. LEEM reveals that Ag initially alloys at Cu/Ag step edges producing a distortion of the steps. Upon deposition above 1 ML, nucleation of Ag nanowires was observed across terraces, however nucleation still occurred at defect and step edges. LEEM showed that the nanowires grow to micron lengths and have highly anisotropic aspect ratios. Annealing above 573K resulted in rapid Oswald ripening of nanowires to Ag clusters of several micron dimensions. Quantitative details of the growth and decay mechanisms will be discussed. Sandia Corporation is a Lockheed Martin Company, for the US DOE's NNSA under Contract DE-AC04-94AL85000. Work was supported CINT-U2006A123 and NSF-DMR-0504654.

Senevirathne, Indrajith; Bussmann, Ezra; Kellogg, Gary; Kurtz, Richard; Sprunger, Phillip

2007-03-01

118

Structural Study of Zr-Cu-Ag Bulk Metallic Glasses Using the Anomalous X-ray Scattering Method  

NASA Astrophysics Data System (ADS)

The structures of Zr45Cu45Ag10 and Zr40Cu40Ag20 bulk metallic glasses (BMGs) were investigated using the anomalous x-ray scattering and reverse Monte Carlo simulation (AXS-RMC) method. The fundamental structural features of Zr45Cu45Ag10 and Zr40Cu40Ag20 can be properly demonstrated through the common dense random packing of the hard spheres, and the addition of Ag appeared to result in no prominent formation of the particular chemical ordering units. A Voronoi analysis indicated that the fraction of the icosahedron-like coordination was the largest around the Cu in Zr45Cu45Ag10 BMG, where the best glass-forming ability was realized. The improvement in the glass-forming ability in a Zr-Cu-Ag system appears to be associated with the icosahedron-like local coordination.

Kawamata, T.; Sugiyama, K.; Yokoyama, Y.; Fujita, T.

2014-04-01

119

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

120

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

121

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

122

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

123

Phase equilibria studies of SnAgCu eutectic solder using differential cooling of Sn3.8Ag0.7Cu alloys  

Microsoft Academic Search

This paper is a study of the phase equilibria of the Sn-3.8Ag-0.7Cu alloy investigated by a differential cooling method. The\\u000a difficulty in assessing phase equilibria of the Sn-Ag-Cu (SAC) system because of the insufficient resolution of conventional\\u000a characterization techniques is solved by inducing preferential growth of a solid phase in a melt by holding the alloy at the\\u000a solid-liquid phase-equilibrium

Jae-Yong Park; Choong-Un Kim; Ted Carper; Viswanadham Puligandla

2003-01-01

124

Atom probe study of the precipitation process in Al-Cu-Mg-Ag alloys  

Microsoft Academic Search

The compositions of the G.P. zones, [theta][double prime], [theta][prime], and [Omega] phases in alloys based on the Al-Cu-Mg-Ag system aged under various conditions have been examined by atom probe field ion microscopy. At the peak hardness condition, the composition of [theta][prime] was determined to be of Al[sub 2]Cu without any partitioning of Ag and Mg. Under the same aging condition,

K. Hono; N. Sano; S. S. Babu; R. Okano; T. Sakurai

1993-01-01

125

Large domain growth of Ag-doped YBaCuO-system superconductor  

Microsoft Academic Search

The effect of Ag addition on the phase diagram, solidification conditions and fabrication of large domain YBaCuO-system has been studied. Calcined powder of composition Y1.8Ba2.4Cu3.4O9-x with 0.5 wt.% Pt and 0, 1, 5, 10, 20 and 30 wt.% Ag was prepared. The melting point of each powder was measured by differential thermal analysis (DTA). A large domain (45 mm diameter

S. Kohayashi; S. Yoshizawa; H. Miyairi; H. Nakane; S. Nagaya

1998-01-01

126

Crystalline monolayer surface of liquid AuCuSiAgPd: Metallic glass former  

E-print Network

Crystalline monolayer surface of liquid Au­Cu­Si­Ag­Pd: Metallic glass former S. Mechler,1,a E that the surface of the liquid phase of the bulk metallic glass forming alloy Au49Cu26.9Si16.3Ag5.5Pd2.3 consists. This suggests that the phenomena of surface freezing in metallic liquids and glass forming ability are related

Pershan, Peter S.

127

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

128

Surfactant Assisted Electrodeposition of Nanostructured CoNiCu Alloys  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

129

Electromigration-Induced Interfacial Reactions in Cu/Sn/Electroless Ni-P Solder Interconnects  

NASA Astrophysics Data System (ADS)

The effect of electromigration (EM) on the interfacial reaction in a line-type Cu/Sn/Ni-P/Al/Ni-P/Sn/Cu interconnect was investigated at 150°C under 5.0 × 103 A/cm2. When Cu atoms were under downwind diffusion, EM enhanced the cross-solder diffusion of Cu atoms to the opposite Ni-P/Sn (anode) interface compared with the aging case, resulting in the transformation of interfacial intermetallic compound (IMC) from Ni3Sn4 into (Cu,Ni)6Sn5. However, at the Sn/Cu (cathode) interface, the interfacial IMCs remained as Cu6Sn5 (containing less than 0.2 wt.% Ni) and Cu3Sn. When Ni atoms were under downwind diffusion, only a very small quantity of Ni atoms diffused to the opposite Cu/Sn (anode) interface and the interfacial IMCs remained as Cu6Sn5 (containing less than 0.6 wt.% Ni) and Cu3Sn. EM significantly accelerated the dissolution of Ni atoms from the Ni-P and the interfacial Ni3Sn4 compared with the aging case, resulting in fast growth of Ni3P and Ni2SnP, disappearance of interfacial Ni3Sn4, and congregation of large (Ni,Cu)3Sn4 particles in the Sn solder matrix. The growth kinetics of Ni3P and Ni2SnP were significantly accelerated after the interfacial Ni3Sn4 IMC completely dissolved into the solder, but still followed the t 1/2 law.

Huang, M. L.; Zhou, S. M.; Chen, L. D.

2012-04-01

130

Faceting of Cu(210) and Ni(210) by activated nitrogen  

NASA Astrophysics Data System (ADS)

The interactions of activated nitrogen (AN) with Cu(210) and Ni(210) and of O 2 with Ni(210) have been studied using LEED, RHEED and AES. Exposure to AN at 290 K produces (100) facets with a c(11 ?2 × ?2)R45°-N overlayer; on warming (520 K) in vacuum, (110) facets with a p(2 × 3)-N overlayer appear. Heating to 600 K causes desorption of N 2 and regeneration of the (210) surface. With O 2 on Ni(210) complicated facet patterns are observed. Facet orientations have been identified by a simple method involving rotation of the crystal. The results are discussed in relation to the stabilities of various Cu surfaces, particularly (410) and (530), in the presence of AN and O 2.

Kirby, R. E.; McKee, C. S.; Renny, L. V.

1980-07-01

131

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

132

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

133

Liganci-field theory applied to diatomic transition metals. Results for the &A&d states of Ni2, the &Nid$a states of NiCu,  

E-print Network

, the &Nid$a states of NiCu, and the &Ni(3F)dL\\02cr*' excited states of NiCu Eileen M. Spain and Michael D$d manifold of states in NiCu, and on the &2`&? manifold of states in Ni2. This demonstrates that the ligand-field model less favorable in these examples. The dhi(3F)dga"dr1 excited electronic states of NiCu, which

Morse, Michael D.

134

Interfacial Reactions of Sn-3.5Ag- xZn Solders and Cu Substrate During Liquid-State Aging  

NASA Astrophysics Data System (ADS)

The effects of Zn (1 wt.%, 3 wt.%, and 7 wt.%) additions to Sn-3.5Ag solder and various reaction times on the interfacial reactions between Sn-3.5Ag- xZn solders and Cu substrates a during liquid-state aging were investigated in this study. The composition and morphological evolution of interfacial intermetallic compounds (IMCs) changed significantly with the Zn concentration and reaction time. For the Sn-3.5Ag-1Zn/Cu couple, CuZn and Cu6Sn5 phases formed at the interface. With increasing aging time, the Cu6Sn5 IMC layer grew thicker, while the CuZn IMC layer drifted into the solder and decomposed gradually. Cu5Zn8 and Ag5Zn8 phases formed at the interfaces of Sn-3.5Ag-3Zn/Cu and Sn-3.5Ag-7Zn/Cu couples. With increasing reaction time, the Cu5Zn8 layer grew and Cu atoms diffused from the substrate to the solder, which transformed the Ag5Zn8 to (Cu,Ag)5Zn8. The Cu6Sn5 layer that formed between the Cu5Zn8 layer and Cu was much thinner at the Sn-3.5Ag-7Zn/Cu interface than at the Sn-3.5Ag-3Zn/Cu interface. Additionally, we measured the thickness of interfacial IMC layers and found that 3 wt.% Zn addition to the solder was the most effective for suppressing IMC growth at the interfaces.

Liu, Lijuan; Zhou, Wei; Mu, Wenkai; Wu, Ping

2011-03-01

135

Electrical conductivity of Cu\\/(10NiO-NiFe 2 O 4 ) cermet inert anode for aluminum electrolysis  

Microsoft Academic Search

Cu\\/(10NiO-NiFe2O4) cermets containing mass fractions of Cu of 5%, 10%, 15% and 20% were prepared, and their electrical conductivities were\\u000a measured at different temperatures. The effects of temperature and content of metal Cu on the electrical conductivity were\\u000a investigated especially. The results indicate that the metallic phase Cu distributes evenly in 10NiO-NiFe2O4 ceramic matrix. The mechanism of electrical conductivity of

Zhong-liang Tian; Yan-qing Lai; Jie Li; Ye-xiang Liu

2007-01-01

136

Effect of Ag or Cu doping on erasable phase-change Sb-Te thin films  

Microsoft Academic Search

The crystallization process of the Ag or Cu doped Sb2Te 3 amorphous film was investigated by isothermal treatment for one hour at 100°C, 200°C and 300°C respectively. The crystallization temperatures of Ag8.3Sb34.9Te56.8 and Cu8.4Sb35.1Te56.5 films determined by DSC analysis were more than 125°C and 120°C respectively, while that of the undoped Sb2Te3 film was 97°C. It indicates that doping Ag

Yi-Ming Chen; P. C. Kuo

1998-01-01

137

Irradiation induced dissolution of Cu and growth of Ag nanoclusters in Cu/Ag ion-exchanged soda-lime glass  

NASA Astrophysics Data System (ADS)

Complex metal nanoclusters of Cu/Ag are formed in a soda-lime glass matrix by sequential copper and silver ion-exchange followed by ion irradiation. Optical absorption measurements showed signature of copper clusters alone in the Cu/Ag ion-exchanged sample. Irradiation of the ion-exchanged sample with He + ions of energy 100 keV of different fluences resulted in the growth of the silver clusters with, the optical absorption spectrum exhibiting two peaks corresponding to the surface plasmon resonance of copper and silver in the same matrix. It was found that with increase in fluence the silver clusters begin to grow while the already formed copper clusters segregate, which can be visualized from the absorption spectra, where the copper band disappears while the silver band grows with the increase in dose. Vacuum annealing of the Cu/Ag ion-exchanged samples resulted in complete disappearance of copper clusters while the silver clusters grew till they attained saturation. The glancing incidence X-ray diffraction study of the Cu/Ag ion-exchanged and irradiated sample showed silver peaks alone with no information of alloying between the two species.

Manikandan, D.; Mohan, S.; Magudapathy, P.; Nair, K. G. M.

2002-12-01

138

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

NASA Astrophysics Data System (ADS)

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

Chandross, Michael

2014-10-01

139

Nanoindentation of Ag/Ni multilayered thin films J. A. Ruud"  

E-print Network

-displacementcurve upon unloadingwhen the material recoverselastically.An elastic modulus can be determined*7The hardnessand elastic modulus of some metal/metalmultilayeredthin films havebeenmeasuredwith (Cu/Ni),8to decrease(MO/V,Nb/T'a),9andto remainconstant (Au/Ni)." In all of thesecasesthe elastic

Spaepen, Frans A.

140

Phase Transitions of AgI-CuI Nanosystem in the Aniya-Ichihara Theory  

NASA Astrophysics Data System (ADS)

AgI-CuI `solid-solution' nanoparticles prepared by mechanochemical reaction at ambient temperature show a progressive linear increase in the zincblende-bcc phase transition temperature upon increase of Cu concentration. Aniya-Ichihara model has been invoked to qualitatively account for the experimental observations adopting the linear model for the concentration dependence of defect-defect interaction. The specific role played by Cu namely occupation of lattice Ag+ sites and depletion of Frenkel defects probably justifies the use of the linear model.

Mohan, D. Bharathi; Sunandana, C. S.

2011-07-01

141

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

142

Equilibrium Cu-Ag nanoalloy structure formation revealed by in situ scanning transmission electron microscopy heating experiments  

NASA Astrophysics Data System (ADS)

Using in situ scanning transmission electron microscopy heating experiments, we observed the formation of a 3-dimensional (3D) epitaxial Cu-core and Ag-shell equilibrium structure of a Cu-Ag nanoalloy. The structure was formed during the thermal interaction of Cu(˜12 nm) and Ag NPs(˜6 nm) at elevated temperatures (150-300 °C) by the Ag NPs initially wetting the Cu NP along its {111} surfaces at one or multiple locations forming epitaxial Ag/Cu (111) interfaces, followed by Ag atoms diffusing along the Cu surface. This phenomenon was confirmed through Monte Carlo simulations to be a nanoscale effect related to the large surface-to-volume ratio of the NPs.

Lu, Ping; Chandross, Michael; Boyle, Timothy J.; Clark, Blythe G.; Vianco, Paul

2014-02-01

143

Effect of Zr Addition on Microstructure and Properties of Cu-Ag-Ti Alloys  

NASA Astrophysics Data System (ADS)

Effects of small addition of Zr on the microstructures and properties of as-cast Cu50Ag46-xZrxTi4 alloys were investigated by differential scanning calorimeter (DSC), x-ray diffraction, microscope, and property testings. The results show that the melting point of the Cu50Ag46Ti4 alloys does not change obviously with the addition of Zr at the melting points of about 779 °C. Adding Zr reduces the volume fraction and size of the board strips of Cu3Ti phase, promotes the uniform distribution of the new phase Cu4AgZr, and improves the Vickers hardness and shear strength of the based alloys. Moreover, increasing the Zr content can improve the high-temperature oxidation resistance of alloys.

Xiao, D. H.; Li, X. X.; Zhang, F. Q.; Zhang, Y. S.

2014-05-01

144

BRAZING OF POROUS ALUMINA TO MONOLITHIC ALUMINA WITH Ag-CuO and Ag-V2O5 ALLOYS  

SciTech Connect

The feasibility of joining porous alumina (Al{sub 2}O{sub 3}) bodies to monolithic Al{sub 2}O{sub 3} using Ag-CuO and Ag-V{sub 2}O{sub 5} alloys via reactive air brazing (RAB) was examined for a nanoporous filter application. Brazing for these systems is complicated by the conflicting requirements of satisfactory wetting to fill the braze gap, while minimizing the infiltration of the porous body. By varying the firing time, temperature, and initial powder size, porous bodies with a range of pore microstructures were fabricated. The wettability was evaluated via sessile drop testing on monolithic substrates and porous body infiltration. Porous Al{sub 2}O{sub 3}/monolithic Al{sub 2}O{sub 3} brazed samples were fabricated, and the microstructures were evaluated. Both systems exhibited satisfactory wetting for brazing, but two unique types of brazing behavior were observed. In the Ag-CuO system, the braze alloy infiltrated a short distance into the porous body. For these systems, the microstructures indicated satisfactory filling of the brazed gap and a sound joint regardless of the processing conditions. The Ag-V{sub 2}O{sub 5} alloys brazed joints exhibited a strong dependence on the amount of V{sub 2}O{sub 5} available. For Ag-V{sub 2}O{sub 5} alloys with large V{sub 2}O{sub 5} additions, the braze alloy aggressively infiltrated the porous body and significantly depleted the Ag from the braze region resulting in poor bonding and large gaps within the joint. With small additions of V{sub 2}O{sub 5}, the Ag infiltrated the porous body until the V{sub 2}O{sub 5} was exhausted and the Ag remaining at the braze interlayer bonded with the Al{sub 2}O{sub 3}. Based on these results, the Ag-CuO alloys have the best potential for brazing porous Al{sub 2}O{sub 3} to monolithic Al{sub 2}O{sub 3}.

Lamb, M. C.; Camardello, Sam J.; Meier, Alan; Weil, K. Scott; Hardy, John S.

2005-01-31

145

Mechanical strength of thermally aged Sn3.5Ag\\/NiP solder joints  

Microsoft Academic Search

This work presents an investigation on the influence of the solder\\/under bump metallization (UBM) interfacial reaction to\\u000a the tensile strength and fracture behavior of Sn-3.5Ag\\/Ni-P solder joints under different thermal aging conditions. The tensile\\u000a strength of Sn-3.5Ag\\/Ni-P solder joints decreases with aging temperature and duration. Four types of failure modes have been\\u000a identified. The failure modes shift from the bulk

Min He; Zhong Chen; Guojun Qi

2005-01-01

146

Structure and chemistry of Ag?Cu nanoclusters in a silica matrix by the sol-gel process  

Microsoft Academic Search

Mixed Ag?Cu nanoclusters with doped silica coatings were prepared by the sol-gel process and characterized by conventional transmission electron microscopy, nanodiffraction, energy-dispersive X-ray spectrometry, high-resolution transmission electron microscopy and related Fourier transforms and optical absorption spectroscopy. This study reports on the results of two samples with Cu-to-Ag molar ratios of 1 and 3 respectively. A constant (Ag + Cu)-to-SiO2 molar

M. Catalano; E. Carlino; G. De; L. Tapfer; F. Gonella; P. Mazzoldi; G. Battaglin

1997-01-01

147

Photocatalytic performance of Cu2O and Ag/Cu2O composite octahedra prepared by a propanetriol-reduced process  

NASA Astrophysics Data System (ADS)

Cu2O and Ag/Cu2O composite octahedra were synthesized via a hydrothermal reaction of CuAc2 with urea in H2O-propanetriol binary solution by adjusting the quantity of AgNO3 at 180 °C for 10 h. The influence of reaction temperature and time on the morphology and phase of the products was investigated, and a possible growth mechanism of Cu2O octahedron was also proposed. The photocatalytic activities of the as-prepared Cu2O and Ag/Cu2O octahedra for the degradation of methyl orange aqueous solution were studied. The results show that they are effective photocatalysts for the degradation of methyl orange, and the photocatalytic ability of Ag/Cu2O composite is stronger than that of Cu2O octahedra, which are expected to be useful in the treatment of wastewaters.

Zhang, Lihui; Wang, Xiangfu

2014-08-01

148

Microstructures and fatigue life of SnAgCu solder joints bearing Nano-Al particles in QFP devices  

NASA Astrophysics Data System (ADS)

Microstructures and fatigue life of SnAgCu and SnAgCu bearing nano-Al particles in QFP (Quad flat package) devices were investigated, respectively. Results show that the addition of nano-Al particles into SnAgCu solder can refine the microstructures of matrix microstructure. Moreover, the nano-Al particles present in the solder matrix, act as obstacles which can create a back stress, resisting the motion of dislocations. In QFP device, it is found that the addition of nano-Al particles can increase the fatigue life by 32% compared with the SnAgCu solder joints during thermal cycling loading.

Zhang, Liang; Fan, Xi-ying; Guo, Yong-huan; He, Cheng-wen

2014-05-01

149

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

NASA Astrophysics Data System (ADS)

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

Pstru?, Janusz; Gancarz, Tomasz

2014-05-01

150

Projectile fragmentation of radioactive beams of Ni, Cu, and ²Zn  

Microsoft Academic Search

The fragment production cross sections of secondary neutron-rich beams of Ni, Cu, and ²Zn isotopes at energies of about 95A MeV have been measured. We compare the measured cross sections to EPAX, an empirical parametrization of fragmentation cross sections. A reasonable agreement of the experimental data and EPAX predictions suggests that an EPAX parametrization used for stable beams seems to

S. Lukyanov; S. P. Lobastov; O. B. Tarasov; M. Mocko; L. Andronenko; M. Andronenko; D. Bazin; A. Gade; M. A. Famiano; W. G. Lynch; A. M. Rogers; M. B. Tsang; R. G. T. Zegers; G. Verde; M. S. Wallace

2009-01-01

151

Heterogeneous nucleation of gamma prime in Al-Ag and Al-Ag /Cd or Cu/ alloys.  

NASA Technical Reports Server (NTRS)

Results of transmission electron microscopy studies of heterogeneous nucleation of the metastable gamma prime phase were made in binary and ternary alloys of Al-5 at. % Ag, Al-4.8 at. % Ag-0.15 at. % Cd, and Al-4.8 at. % Ag-0.2 at. % Cu. Heterogeneous nucleation of gamma prime was found to be associated with four types of dislocations, regardless of the quenching treatment or alloy additions which were used. Nucleation was found to occur on: (a) jogged dislocations; (b) helical dislocations; (c) dislocation loops; (d) heterogeneous climb sources. Only one nucleation mechanism was found to be unique to the ternary alloys: that of nucleation on heterogeneous climb sources.

Passoja, D. E.; Ansell, G. S.

1971-01-01

152

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

153

A cervelleite-like mineral and other Ag-Cu-Te-S minerals [Ag2CuTeS and (Ag,Cu)2TeS] in gold-bearing veins in metamorphic rocks of the Cycladic Blueschist Unit, Kallianou, Evia Island, Greece  

Microsoft Academic Search

A cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [Ag2CuTeS, (Ag,Cu)2TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults are discordant to syn-metamorphic structures and formed during ductile to brittle deformation

Panagiotis Christos Voudouris; Paul G. Spry; Gregory Aarne Sakellaris; Constantinos Mavrogonatos

2011-01-01

154

Wetting and interface integrity of Sn-Ag-Bi solder/Fe-42 percent Ni alloy system  

SciTech Connect

The wetting and interfacial integrity of lead-free Sn-Ag and Sn-Ag-Bi solders with 42 alloy (Fe-42wt percent Ni) were investigated. A tin-iron intermetallic layer formed at the interface and, during cooling, Ni3Sn4 platelets precipitated in the solder. After bonding, the Sn-3Ag joints have a eutectic microstructure, with a fine network of Ag3Sn particles surrounding large primary -Sn grains. Bismuth addition to Sn-3Ag improved wettability, but decreased the joint strength, owing to Bi segregation to the interface.

Hwang, C.-W.; Suganuma, K.; Saiz, E.; Tomsia, A.P.

2002-01-15

155

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

156

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

157

Fabrication of (Bi,Pb)-2223/Ag-Cu alloy sheathed tapes: optimization of Cu composition in the sheath with respect to the Cu stoichiometry in the system  

NASA Astrophysics Data System (ADS)

(Bi,Pb)-2223/Ag-Cu alloy sheathed tapes with varying Cu compositions (3, 6, 9 and 12 at.%) in the sheath have been fabricated by powder in tube (PIT) technique using rolling as the deformation step. Two precursor powders with Cu stoichiometries of 3.0 and 3.2 were used to prepare (Bi,Pb)-2223/Ag-Cu alloy sheathed tapes. Phase evolution study by means of XRD and critical current density ( Jc) measurements at 77 K, 0 T have been used to elucidate the performance of the tapes and to determine the optimum Cu doping level in the sheath with respect to the Cu stoichiometry in the system. It was found that the level of Cu doping in the sheath is dependent on the Cu stoichiometry in the system. A doping level of 6 at.% is found to be the optimum for the Cu stoichiometry of 3.0 in the system with regard to the Bi-2223 phase growth, the ultimate Bi-2223 phase fraction and the critical current density ( Jc). Alloy sheathed tapes using the precursor with a Cu stoichiometry of 3.2 is found to yield inferior superconducting properties especially when the doping level of Cu exceeds 3 at.%.

Aloysius, R. P.; Sobha, A.; Guruswamy, P.; Warrier, K. G. K.; Syamaprasad, U.

1999-12-01

158

Reduction of charge fluctuation energies in ultrathin NiO films on Ag(001)  

NASA Astrophysics Data System (ADS)

As the film becomes atomically thin, the on-site Coulomb interaction energy between two 3p holes of the NiO films on Ag(001) U (Ni 3p) significantly decreases as revealed by both X-ray photoelectron and Auger electron spectroscopies. The reduction of U (Ni 3p) for the ultrathin films is well accounted for by varied image potentials and polarization energies in the films from their bulk values. The present results confirm a previous model predicting the reduction of charge fluctuation energies in ultrathin oxide films on highly polarizable substrates due to the extra-atomic relaxations.

Yang, Seolun; Park, H.-K.; Kim, J.-S.; Phark, S.-H.; Chang, Young Jun; Noh, T. W.; Hwang, H.-N.; Hwang, C.-C.; Kim, H.-D.

2013-10-01

159

Accurately determining eutectic compositions: The Sn-Ag-Cu ternary eutectic  

NASA Astrophysics Data System (ADS)

Determining an accurate eutectic composition is more difficult than determining the corresponding eutectic temperature, a fact that was demonstrated in this study using a lead-free solder: the tin-rich Sn-Ag-Cu ternary eutectic. The solidification of this ternary eutectic involves the solid phases (Sn), Ag3Sn, and Cu6Sn5. The liquid is prone to supercooling, the intermetallics have steep liquidus surfaces (small phase fractions), and the coupled zone of eutectic microstructure formation is shifted toward silver-rich and copper-rich compositions. These issues were overcome by a combination of methods: preliminary thermodynamic calculation of the ternary phase diagram to anticipate difficulties, increased sensitivity of the thermal analysis, and a cycled heating and cooling method. The experimentally determined composition of the ternary eutectic is Sn-3.58±0.05Ag-0.96±0.04Cu at 217.2±0.2°C.

Moon, K.-W.; Boettinger, W. J.

2004-04-01

160

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

161

Creep properties of eutectic Sn3.5Ag solder joints reinforced with mechanically incorporated Ni particles  

Microsoft Academic Search

The creep deformation behavior of eutectic Sn-3.5Ag based Ni particle rein forced composite solder joints was investigated.\\u000a The Ni particle reinforced composite solder was prepared by mechanically dispersing 15 vol.% of Ni particles into eutectic\\u000a Sn-3.5Ag solder paste. Static-loading creep tests were carried out on solder joint specimens at 25 C, 65 C, and 105 C, representing\\u000a homologous temperatures ranging

F. Guo; J. Lee; J. P. Lucas; K. N. Subramanian; T. R. Bieler

2001-01-01

162

Ag-Cu-Ni (Silver-Copper-Nickel)  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume C3 'Non-Ferrous Metal Systems. Part 3: Selected Soldering and Brazing Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Silver-Copper-Nickel.

Materials Science International Team MSIT

163

Demonstration of Saturation in a Ni-like Ag X-Ray Laser at 14 nm  

SciTech Connect

We report the first demonstration of saturation in a Ni-like x-ray laser, specifically Ni-like Ag x-ray laser at 14nm. Using high-resolution spatial imaging and angularly resolved streaking techniques, the output source size as well as the time history, divergence, energy, and spatial profile of the output beam have been fully characterized. The output intensity of the Ag laser was measured to be about 70 GW cm {sup -2}. The narrow divergence, short pulse duration, high efficiency, and high brightness of the Ag laser make it an ideal candidate for many x-ray laser applications. {copyright} {ital 1997} {ital The American Physical Society}

Zhang, J.; Wark, J.S.; Wolfrum, E. [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU (United Kingdom)] [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, OX1 3PU (United Kingdom); MacPhee, A.G.; Lewis, C.L.; ORourke, R.M. [School of Mathematics and Physics, Queen`s University of Belfast, Belfast, BT7 1NN (United Kingdom)] [School of Mathematics and Physics, Queen`s University of Belfast, Belfast, BT7 1NN (United Kingdom); Nilsen, J.; Barbee, T.W., Jr.; Key, M.H. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Lin, J.; Smith, R.; Tallents, G.J. [Department of Physics, University of Essex, Colchester, CO4 3SQ (United Kingdom)] [Department of Physics, University of Essex, Colchester, CO4 3SQ (United Kingdom); Danson, C.; Neely, D. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX (United Kingdom)] [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX (United Kingdom); Pert, G.J. [Department of Physics, University of York, York, YO1 5DD (United Kingdom)] [Department of Physics, University of York, York, YO1 5DD (United Kingdom)

1997-05-01

164

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 3×3 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.; Sörgel, T.; Jansen, M.; Ibberson, R. M.; Radaelli, P. G.

2007-10-01

165

Orbital Degeneracy Removed by Charge Order in Triangular Antiferromagnet AgNiO{sub 2}  

SciTech Connect

We report a high-resolution neutron diffraction study on the orbitally degenerate spin-1/2 hexagonal metallic antiferromagnet AgNiO{sub 2}. A structural transition to a tripled unit cell with expanded and contracted NiO{sub 6} octahedra indicates {radical}(3)x{radical}(3) 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.

Wawrzynska, E.; Coldea, R. [H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Wheeler, E. M. [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Institute Laue-Langevin, B.P. 156, 38042 Grenoble Cedex 9 (France); Mazin, I. I.; Johannes, M. D. [Code 6393, Naval Research Laboratory, Washington, D.C. 20375 (United States); Soergel, T.; Jansen, M. [Max-Planck Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Ibberson, R. M.; Radaelli, P. G. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom)

2007-10-12

166

Structural and optical properties of Cu-, Ag, and Al-doped zinc oxide nanorods  

NASA Astrophysics Data System (ADS)

We investigated structural and optical properties of Cu-, Ag-, and Al-doped zinc oxide (ZnO) nanorods grown on ZnO seed layers. Cu-doped ZnO (ZnO:Cu) nanorods showed increased length and improved crystallinity, compared to undoped ZnO nanorods, where the average transmittance in the visible region is lower than that of ZnO nanorods. Meanwhile, the Ag incorporation led to quite opposite behaviors: decreased length and crystallinity of nanorods. It was also found that Ag-doped ZnO (ZnO:Ag) nanorods exhibited high transparency. The incorporation of Al dopant led to a marked morphological variation, with randomly oriented microrods grown on the surface of the ZnO seed layer, instead of nanorods. Al-doped ZnO (ZnO:Al) microrods exhibited excellent transparency over the visible region. The present results thus show that incorporation of Cu, Ag, and Al dopants has a critical effect on structural and optical properties of ZnO nanorods.

Kim, Kyung Ho; Jin, Zhuguang; Abe, Yoshio; Kawamura, Midori

2014-11-01

167

Nearly Constant Electrical Resistance over Large Temperature Range in Cu3NMx (M = Cu, Ag, Au) Compounds  

NASA Astrophysics Data System (ADS)

Electrical resistance is a material property that usually varies enormously with temperature. Constant electrical resistivity over large temperature range has been rarely measured in a single solid. Here we report the growth of Cu3NMx (M = Cu, Ag, Au) compound films by magnetron sputtering, aiming at obtaining single solids of nearly constant electrical resistance in some temperature ranges. The increasing interstitial doping of cubic Cu3N lattice by extra metal atoms induces the semiconductor-to-metal transition in all the three systems. Nearly constant electrical resistance over 200 K, from room temperature downward, was measured in some semimetallic Cu3NMx samples, resulting from opposite temperature dependence of carrier density and carrier mobility, as revealed by Hall measurement. Cu3NAgx samples have the best performance with regard to the range of both temperature and doping level wherein a nearly constant electrical resistance can be realized. This work can inspire the search of other materials of such a quality.

Lu, Nianpeng; Ji, Ailing; Cao, Zexian

2013-10-01

168

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

NASA Astrophysics Data System (ADS)

Proton Nuclear Magnetic Resonance (NMR) relaxation measurements have been performed down to very low temperature (50 mK) to determine the effect of coupling two Cr7Ni molecular rings via a Cu2+ 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 Cr7Ni ring (140 mK).

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

2014-05-01

169

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

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

170

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

SciTech Connect

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

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

2005-01-15

171

Giant Magnetoresistance In Ni/Cu Multilayers Fabricated By Electron-Beam Evaporation  

NASA Astrophysics Data System (ADS)

Electron beam evaporation technique has been used to deposit the multilayers of Ni-Cu, represented by Si[BLt/[Ni(tFM)/Cu(tNM)]×n] where Si is used as a substrate and BL is buffer layer, n is the number of bilayers, t, tFM and tNM are thicknesses of buffer layer, ferromagnetic (Ni) and nonmagnetic (Cu) layers, respectively. We characterize the multilayers using M-H curves, magnetoresistance measurement (at room temperature).

Vikram, V.; Rahman, Md. Rizwanur; Katiyar, Monica

2008-04-01

172

Fabrication and properties of ZnO:Cu and ZnO:Ag thin films  

Microsoft Academic Search

Thin films of ZnS and ZnO:Cu were grown by an original metal–organic chemical vapour deposition (MOCVD) method under atmospheric pressure onto glass substrates. Pulse photo-assisted rapid thermal annealing of ZnO:Cu films in ambient air and at the temperature of 700–800 ?C was used instead of the common long-duration annealing in a vacuum furnace. ZnO:Ag thin films were prepared by oxidation and

V. S. Khomchenko; T. G. Kryshtab; A. K. Savin; L. V. Zavyalova; N. N. Roshchina; V. E. Rodionov; O. S. Lytvyn; V. I. Kushnirenko; V. B. Khachatryan; J. A. Andraca-Adame

2007-01-01

173

Independent and combined roles of trace Mg and Ag additions in properties precipitation process and precipitation kinetics of Al–Cu–Li–(Mg)–(Ag)–Zr–Ti alloys  

Microsoft Academic Search

The independent and combined roles of trace Mg and Ag additions in properties and precipitation of Al–Cu–Li–(Mg)–(Ag)–Zr–Ti alloys were studied. The independent roles of Mg additions are to promote the T1 precipitation, decrease activation energy for the growth of ?? plates and reduce lengthening rates of T1 and ?? plates. The independent roles of Ag additions are to retard GP-zone

B.-P. Huang; Z.-Q. Zheng

1998-01-01

174

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

175

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

176

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

PubMed

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 (2)S(Cu) + (2)S(Ag) and (2)D(Cu) + (2)S(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. PMID:25338890

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-21

177

Microstructure, Melting and Wetting Properties of Pd-Ag-CuO Air Braze on Alumina  

SciTech Connect

A reactive air brazing (RAB) technique utilizing silver-copper oxide (Ag-CuO) alloys has previously been developed for joining ceramics components used in high temperature devices ranging from oxygen separation membranes, gas turbines and combustion engines. The application of the Ag-CuO system as a brazing material is limited by its solidus and liquidus temperatures, which are known to be in the range of 935 C and 967 C. Some joined ceramic components may be used in devices, which require further processing steps, or may be used in applications, that exceed these temperatures. It has been found that the addition of palladium to the silver copper oxide system will increase solidus and liquidus temperatures of the resulting alloy. In our work, we are studying the effects of palladium addition on the wetting properties of Ag-CuO braze system on alumina. Quality of brazing is evaluated through microstructural analysis and bending strength of brazed joints created with alumina. The presentation will include processing, and characterization of Ag-CuO brazed system with and without palladium addition on alumina.

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

2005-03-19

178

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

179

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

PubMed Central

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

2013-01-01

180

Effect of 0.5 wt?% Cu addition in Sn-3.5%Ag solder on the dissolution rate of Cu metallization  

NASA Astrophysics Data System (ADS)

The dissolution of thin film under-bump-metallization (UBM) by molten solder has been one of the most serious processing problems in electronic packaging technology. Due to a higher melting temperature and a greater Sn content, a molten lead-free solder such as eutectic SnAg has a faster dissolution rate of thin film UBM than the eutectic SnPb. The work presented in this paper focuses on the role of 0.5 wt % Cu in the base Sn-3.5%Ag solder to reduce the dissolution of the Cu bond pad in ball grid array applications. We found that after 0.5 wt % Cu addition, the rate of dissolution of Cu in the molten Sn-3.5%Ag solder slows down dramatically. Systematic experimental work was carried out to understand the dissolution behavior of Cu by the molten Sn-3.5%Ag and Sn-3.5%Ag-0.5%Cu solders at 230-250 °C, for different time periods ranging from 1 to 10 min. From the curves of consumed Cu thickness, it was concluded that 0.5 wt % Cu addition actually reduces the concentration gradient at the Cu metallization/molten solder interface which reduces the driving force of dissolution. During the dissolution, excess Cu was found to precipitate out due to heterogeneous nucleation and growth of Cu6Sn5 at the solder melt/oxide interface. In turn, more Cu can be dissolved again. This process continues with time and leads to more dissolution of Cu from the bond pad than the amount expected from the solubility limit, but it occurs at a slower rate for the molten Sn-3.5%Ag-0.5%Cu solder.

Alam, M. O.; Chan, Y. C.; Tu, K. N.

2003-12-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2001-05-01

182

Adaptive composites with embedded NiTiCu wires  

NASA Astrophysics Data System (ADS)

Adaptive composites have been produced by embedding prestrained shape memory alloy (SMA) wires into an epoxy matrix, reinforced with aramid fibers. These materials demonstrate attractive effects such as shape change or a shift in the vibration frequency upon activation. When heated above their transformation temperature, the wires' strain recovery is confined, and recovery stresses are generated. As a result, if the wires are placed along the neutral axis of a composite beam, a shift in resonance vibration frequency can be observed. To optimize the design of such composites, the matrix - SMA wire interfacial shear strength has been analyzed with the pull out testing technique. It is shown that the nature of the wire surface influences the interfacial shear strength, and that satisfactory results are obtained for SMA wires with a thin oxide layer. Composite samples consisting of two different types of pre- strained NiTiCu wires embedded in either pure epoxy matrix or Kevlar-epoxy matrix were produced. The recovery force and vibration response of composites were measured in a clamped-clamped configuration, to assess the effect of wire type and volume fraction. The results are highly reproducible in all cases with a narrow hysteresis loop, which makes NiTiCu wires good candidates for adaptive composites. The recovery forces increase with the volume fraction of the embedded wires, are higher when the wires are embedded in a low CTE matrix and, at a given temperature, are higher when the wire transformation temperature is lower.

Balta-Neumann, J. Antonio; Michaud, Veronique J.; Parlinska, Magdelena; Gotthardt, Rolf; Manson, Jan-Anders E.

2001-07-01

183

Phase equilibria in the system Ag–Ni–Sn: Thermal behavior  

Microsoft Academic Search

The phase equilibria in the ternary Ag–Ni–Sn 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

184

Nature and mechanism of diffusion in deformed Ni?Fe and Al?Ag alloys  

Microsoft Academic Search

AI-Ag and Ni-Fe alloys subjected to deformation at rates of ~ = 10°-102 sec -1 at temperatures Te = (0.4-0.9)Tf. Based on this work a systemization of the mechanisms (models) of diffusional mass transfer in deformed alloys has been carried out, by means of which real industrial processes of metal working by compression may be analyzed. Binary alloys were studied

Yu. S. Nechaev; S. A. Vladimirov; N. A. Ol'shevkii; D. G. Mukhambetov

1992-01-01

185

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

186

Solid-State Diffusional Mixing in Cu Core/Ni Shell Nanoparticles  

NASA Astrophysics Data System (ADS)

Cu core/Ni shell nanoparticles have been prepared in a polyol process using ethylene glycol as the solvent /reducing agent solution and Cu and Ni acetates as the metal sources. The more positive reduction potential of Cu(II) relative to Ni(II) lead to the formation of Cu core/Ni shell nanoparticles. The structural evolution of these core/shell diffusion couples was studied by high temperature x-ray diffraction measurements. Between room temperature and 350 ^oC, the evolution in the diffraction pattern was only due to lattice expansion. At higher temperatures, the elemental Cu and Ni diffraction peaks began to merge until, at a temperature of 600 ^oC only a single set of diffraction peaks remained, indicating the formation of a single homogeneous Cu-Ni alloy. These diffraction patterns have been decomposed into a set of 11 individual subpeaks corresponding to 9 intermediate Cu-Ni compositions in addition to subpeaks corresponding to pure Cu and Ni. The angular positions of each subpeak were fixed to the values appropriate for their composition and the best fit peak areas determined. These data were then used to reconstruct the radial composition profiles of the diffusion couples as a function of the reaction temperature and time.

Unruh, Karl; Kelly, Brian; Klodnicki, John; Poirier, Gerald

2013-03-01

187

Resistive switching mechanism of Ag/ZrO2:Cu/Pt memory cell  

NASA Astrophysics Data System (ADS)

Resistive switching mechanism of zirconium oxide-based resistive random access memory (RRAM) devices composed of Cu-doped ZrO2 film sandwiched between an oxidizable electrode and an inert electrode was investigated. The Ag/ZrO2:Cu/Pt RRAM devices with crosspoint structure fabricated by e-beam evaporation and e-beam lithography show reproducible bipolar resistive switching. The linear I- V relationship of low resistance state (LRS) and the dependence of LRS resistance ( R ON) and reset current ( I reset) on the set current compliance ( I comp) indicate that the observed resistive switching characteristics of the Ag/ZrO2:Cu/Pt device should be ascribed to the formation and annihilation of localized conductive filaments (CFs). The physical origin of CF was further analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). CFs were directly observed by cross-sectional TEM. According to EDS and elemental mapping analysis, the main chemical composition of CF is determined by Ag atoms, coming from the Ag top electrode. On the basis of these experiments, we propose that the set and reset process of the device stem from the electrochemical reactions in the zirconium oxide under different external electrical stimuli.

Long, Shibing; Liu, Qi; Lv, Hangbing; Li, Yingtao; Wang, Yan; Zhang, Sen; Lian, Wentai; Zhang, Kangwei; Wang, Ming; Xie, Hongwei; Liu, Ming

2011-03-01

188

Cu wire bonding on Cu-Ni-Pd bond pad and leads: From development to robust production  

Microsoft Academic Search

Summary form only given. This paper will describe copper wirebonding on Cu-Ni-Pd bond-pad and leadframe in QFN packages using thicker wires i.e 1.3 & 2.0mil wires. The paper introduces bonding and reliability challenges with Copper wire on Al bond pads as experienced by many Process Development Engineers. TI analog devices which mainly used BOAC dies using Cu-Ni-Pd bond-pads and copper-wire

H. Said

2010-01-01

189

High temperature phase equilibria studies in the Bi-Sr-Ca-Cu-O-Ag system  

SciTech Connect

A variety of experimental techniques were utilized to examine the high temperature phase equilibria in the Bi-Sr-Ca-Cu-O-Ag system. Quenching studies were used to determine the liquid solubility of Ag in the Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} (Bi2212) melt and the details of the peritectic decomposition pathway of Bi2212 as a function on Ag content and oxygen partial pressure (PO{sub 2}). A liquid immiscibility region between oxide and Ag liquids in the 8--98 at% range was found above 900 C. Two eutectics were found in the Bi2212-Ag pseudobinary. On the oxide rich side, a eutectic exists at approximately 4 at% Ag. On the Ag rich side, a eutectic exists at approximately 98 at% Ag at a temperature of 15 C below the melting point of pure Ag. Six distinct solid phases were found to be in equilibrium with the partial melt within the Ag content and PO{sub 2} range studied. The stability of these solid phases were found to be highly sensitive to PO{sub 2}, and to a much lesser extent Ag content. High temperature x-ray diffraction (HTXRD) studies of this system are in conflict with these results. It is suggested that these discrepancies are due to experimental artifacts caused by the significant thermal gradients and lack of full bulk sampling which is inherent in conventional HTXRD designs. In part 2, a new furnace design compatible with synchrotron radiation sources is introduced to address these problems. This design allows for full bulk sampling in a low thermal gradient environment using Debye-Scherrer transmission geometry. Sample spinning is also introduced in the design to eliminate preferred orientation and incomplete powder averaging and allow for quantitative phase analysis and structural refinement. Studies on model systems are presented to demonstrate the capabilities for high resolution structural studies (Al{sub 2}O{sub 3}) and time resolved phase transformation studies (SrCO{sub 3}). Finally, the Bi2212 system is examined to confirm the quenching results of part 1, and to demonstrate the degree to which this new HTXRD design solves the problems associated with conventional designs.

Margulies, Lawrence

1999-11-08

190

Spectroscopic studies of jet-cooled NiAu and PtCu Eileen M. Spain and Michael D. Morse  

E-print Network

states, and are in this respect analogous to the isovalent molecule NiCu. The ground-state bond lengths diatomics NiPt,' PdPt,6 and NiPd,6 and a heteronuclear mixed nickel/ copper group diatomic, NiCu.7$c?, diatomic NiCu exhibits a ground configuration of d&j;;2 7-9~13~14 The presence of only one d hole

Morse, Michael D.

191

Enhanced magnetic and ferroelectric properties of multiferroic CuCrO 2 by Ni-doping  

Microsoft Academic Search

We prepare polycrystalline CuCrO2 and CuCr0.98Ni0.02O2 samples by solid state reaction and investigate their multiferroicity. It is revealed that the Ni-doping can not only enhance slightly magnetization but also improve ferroelectricity. It is argued that the Ni3+-doping destabilizes the antiferromagnetic order of Cr3+ ions and modulates the spin configuration, leading to the weak ferromagnetism and enhanced ferroelectric polarization. The coupling

Shijun Luo; L. Li; K. F. Wang; S. Z. Li; X. W. Dong; Z. B. Yan; J.-M. Liu

2010-01-01

192

Third-order elastic constants of bcc Cu-Al-Ni  

Microsoft Academic Search

We have measured the changes in the ultrasonic wave velocity, induced by the application of uniaxial stresses in a Cu-Al-Ni single crystal. From these measurements, the complete set of third-order elastic constants has been obtained. The comparison of results for Cu-Al-Ni with available data for other Cu-based alloys has shown that all these alloys exhibit similar anharmonic behavior. By using

Alfons Gonzàlez-Comas; Lluís Mañosa

1996-01-01

193

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

NASA Astrophysics Data System (ADS)

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

Jiao, Jun; Seraphin, Supapan

1998-03-01

194

Evaluation of the microstructure of Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 4  

NASA Technical Reports Server (NTRS)

Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy designed to have ultrahigh strength and to serve in aerospace applications. The alloy displays significantly higher strength than competitive alloys in both naturally aged and artificially aged tempers. The strengthening phases in such tempers have been identified to, in part, explain the mechanical properties attained. In general, the alloy is strengthened by delta prime Al3Li and Guinier-Preston (GP) zones in the naturally aged tempers. In artificially aged tempers in slightly underaged conditions, strengthening is provided by several phases including GP zones, theta prime Al2Cu, S prime Al2CuMg, T(sub 1) Al2CuLi, and possibly a new phase. In the peak strength artificially aged tempers, T(sub 1) is the predominant strengthening phase.

Pickens, Joseph R.; Kumar, K. S.; Brown, S. A.; Gayle, Frank W.

1991-01-01

195

A cervelleite-like mineral and other Ag-Cu-Te-S minerals [Ag 2 CuTeS and (Ag,Cu) 2 TeS] in gold-bearing veins in metamorphic rocks of the Cycladic Blueschist Unit, Kallianou, Evia Island, Greece  

Microsoft Academic Search

A cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [Ag2CuTeS, (Ag,Cu)2TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated\\u000a marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults\\u000a are discordant to syn-metamorphic structures and formed during ductile to brittle deformation

Panagiotis Christos Voudouris; Paul G. Spry; Gregory Aarne Sakellaris; Constantinos Mavrogonatos

2011-01-01

196

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

197

Surface nanostructuring of Ni/Cu foilsby femtosecond laser pulses  

NASA Astrophysics Data System (ADS)

This work examines the effect of high-power femtosecond laser pulses on Ni/Cu bilayer foils produced by electrodeposition. We consider nanostructures formed at different laser beam parameters and under different ambient conditions. The surface nanostructures obtained in air and water have mostly the form of quasi-periodic ripples with a characteristic period of 400 — 450 and 370 — 390 nm, respectively, at a laser wavelength of 744 nm, whereas the nanostructures produced in ethanol and benzine have the form of spikes, typically spaced 400 — 700 nm apart. Femtosecond laser nanostructuring of metals is for the first time proposed, and experimentally tested, as a viable approach to producing anti-reflective coatings on the surface of polymer replicas.

Korol'kov, V. P.; Ionin, Andrei A.; Kudryashov, Sergei I.; Seleznev, L. V.; Sinitsyn, D. V.; Samsonov, R. V.; Maslii, A. I.; Medvedev, A. Zh; Gol'denberg, B. G.

2011-04-01

198

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

USGS Publications Warehouse

Ore textures, epithermal open-space filling of Permian structures of the Alleghanian orogeny, and largely postorogenic mineralization of the Ellenville, New York, composite Zn-Pb-Cu(Ag) vein system, provide permissive evidence for post-Permian mineralization. Isochron ages determined by 40Ar/39Ar laser-fusion techniques for K-bearing liquid inclusions in main-stage quartz from the Ellenville deposit additionally suggest a Mesozoic time of mineralization, associated with extensional formation of the Newark basin. The best 40Ar/39Ar total-fusion age range is 165 ?? 30 to 193 ?? 35 Ma. The Mesozoic 40Ar/39Ar age agrees with that of many other dated northern Appalachian Zn-Pb-Cu(Ag) deposits with near-matching lead isotope ratios, and adds new evidence of Jurassic tectonism and mineralization as an overprint to Late Paleozoic tectonism at least as far north as Ellenville (lat. 41??43???N). ?? 1994 Springer-Verlag.

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

1994-01-01

199

Inside a superatom: the M7q (M=Cu, Ag, q=1+, 0, 1-) case.  

PubMed

All-electron relativistic density functional calculations are performed to obtain the electronic structure and nucleus-independent chemical shifts (NICS) of D(5h) pentagonal-bipyramidal (PBP) Cu(7)(q) and Ag(7)(q) (q=1+,0,1-) clusters. Scalar and spin-orbit relativistic effects are taken into account at two levels: the two-component zero-order regular approximation (ZORA) Hamiltonian and fully relativistic four-component calculations via the Dirac equation. These clusters are treated by including the spin-orbit effect in the jellium model, within the double-valued point group (D(5h)*) establishing the symmetry correlations between the molecular and the atomic spinors given by the full rotation group. These clusters show highly spherical aromaticity, which is suggested to increase the hardness of the superatom. Thus, the calculations suggest that the paramagnetic Cu(7) and Ag(7) clusters can be regarded as pseudohalogens. PMID:20077458

Muñoz-Castro, Alvaro; Mac-Leod Carey, Desmond; Arratia-Pérez, Ramiro

2010-02-22

200

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

201

[Dissolution of silver and copper from Ag-Cu binary alloys under dynamic conditions].  

PubMed

Ag-Cu binary alloys containing 5-30% copper were subjected to dynamic extraction at 200 rpm and 37 degrees C to simulate the functional movement in the oral environment. Extraction was carried out in Eagle's minimum essential medium every two weeks for 18 weeks. The corrosion products were examined by the separation of extracts with a 0.22 micron filter. Significant dissolution of copper occurred with increasing copper content, but the increase in silver dissolution was slight. The amount of copper in the filtrate was the same as that in the extract, but no silver was detected in the filtrate. Therefore, dynamic extraction accelerated the dissolution of copper from the Ag-Cu binary alloys and thus lowered the corrosion resistance. PMID:2134821

Takeda, S; Sano, Y; Takimoto, T; Tsutsumi, N; Nakamura, M

1990-07-01

202

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

203

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

204

Facile synthesis of core-shell CuO/Ag nanowires with enhanced photocatalytic and enhancement in photocurrent.  

PubMed

CuO nanowires were grown on Cu foil via a simple cost-effective wet-chemical route in large scales and used as templates for making silver-coated CuO (CuO/Ag) core-shell nanowires. The coverage of Ag shells on CuO nanowires was controlled by varying the concentration of Ag precursor. The structure, composition, morphology and optical properties of the synthesized core-shell CuO/Ag nanowires (CACs) were considered. The discussion on the growth process of CACs revealed the important role of Sn(2+). And, the novel structure enlarged the range of absorbed light and enhanced the absorption intensity of light. The CACs were evaluated for their ability to degrade methyl orange (MeO) solution under visible-light irradiation. The rate of degradation of the as-prepared CACs was more than 7 times faster than that of using pure CuO nanowires under solar light irradiation. Moreover, the incorporation of Ag shells at the surface causes a quenching of PL emissions and enhanced photocurrent of CuO nanowires. The mechanisms of enhanced photocatalytic activity, luminescence emission quenching, and photocurrent multiplication of the core-shell nanowires have been discussed. PMID:24491323

Liu, Xueqin; Li, Zhen; Zhao, CaiXin; Zhao, Wen; Yang, Jianbo; Wang, Yang; Li, Fei

2014-04-01

205

Microstructure and creep properties of Sn-Ag-Cu lead-free solders bearing minor amounts of the rare earth cerium  

Microsoft Academic Search

Purpose – The purpose of this paper is to investigate the effects of minor addition of the rare earth (RE) element cerium, Ce, on the microstructures and creep properties of Sn-Ag-Cu solder alloys. Design\\/methodology\\/approach – The pure Sn, Sn-Cu alloy, Sn-Ag alloy and Cu-Ce alloy were used as raw materials. Sn-Ag-Cu alloys with different contents of RE Ce were chosen

Liang Zhang; Song-bai Xue; Li-li Gao; Yan Chen; Sheng-lin Yu; Zhong Sheng; Guang Zeng

2010-01-01

206

Cu and Ag-Modified Cerium Oxide Catalysts for Methane Oxidation  

Microsoft Academic Search

The catalytic activity of nanocrystalline doped ceria and Cu- and Ag-modified ceria for the complete oxidation of methane was studied in this work. The catalyst structure was studied by X-ray diffraction (XRD) and related to the availability of low-temperature oxygen species. Selected samples were also analyzed by STEM\\/EDX, HRTEM, and XPS. Temperature-programmed reduction (TPR) by H2and CH4, as well as

Lj. Kundakovic; M. Flytzani-Stephanopoulos

1998-01-01

207

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

208

Antimicrobial effects of metal ions (Ag+, Cu2+, Zn2+) in hydroxyapatite  

Microsoft Academic Search

The antimicrobial ceramics (AC) based on hydroxyapatite (HA) were made in a wet chemical process with additions of AgNO3, Cu(NO3)2 · 3H2O and Zn(NO3)2 · 6H2O. The ACs were composed of metal-ion substituted hydroxyapatite and nitrate–apatite, which was identified by X-ray diffraction. The viable count and turbidity measurement was adopted to observe the antimicrobial effects of the various ACs. The

T. N Kim; Q. L Feng; J. O Kim; J Wu; H Wang; G. C Chen; F. Z Cui

1998-01-01

209

Surface dynamics of Cu and Ag atoms on hydroxylated MgO(001) surfaces  

NASA Astrophysics Data System (ADS)

Density-functional theory calculations were performed to investigate the surface dynamics of Cu and Ag ( X M) atoms on MgO(001) surfaces with surface-functional hydroxyl groups. The adsorption, diffusion, bonding, and electronic structure of X M on these surfaces are presented. The results indicate a large energy gain in the adsorption of X M on MgOhdr(001) with respect to X M on MgO(001). This suggests that the adsorption of X M is stronger on MgOhdr(001). Further analysis shows that in the presence of surface hydroxyl groups, X M atoms preferentially form X MOH complexes instead of X M dimers. The surface diffusion barriers of X MOH on MgO(001) [ X M on MgOhdr(001)] are calculated. CuOH is found to have a higher surface diffusion energy barrier than AgOH, but a slightly lower energy barrier to diffusion than AuOH. Therefore, sintering of Ag on MgOhdr(001) surfaces is expected to be different from that of Cu or Au. Finally, the electronic structures and charge rearrangements of X M on MgOhdr(001) are presented and compared with those of Au on MgOhdr(001).

Jeon, Junjin; Yu, Byung Deok

2013-01-01

210

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.

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

2014-01-01

211

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 150-400°C is examined. After UV irradiation, the yields of acetaldehyde and ethylene increase for TiO2 and Ag/TiO2 samples, while the activity of Cu2+/TiO2 decreases. The activation energy of ethanol dehydration declines in the order TiO2 > Au3+ > Cu2+ > Ag+ and correlates linearly with a reduction in the radius of M z+ in crystal. The number of acidic sites on a M/TiO2 surface titrated via pyridine adsorption grows upon the introduction of M. Unlike Cu2+/TiO2, these sites are not activated after the irradiation of TiO2, Ag+/TiO2, and Au3+/TiO2. According to IR spectral data on adsorbed pyridine, all samples contain Lewis and Brönsted acidic sites.

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

2014-10-01

212

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

SciTech Connect

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

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

2006-01-01

213

Electrotribological property of the Cu?Ag?Cr alloy with high-strength and high-conductivity  

Microsoft Academic Search

By means of a vacuum induction furnace, a Cu?Ag?Cr alloy was produced. The electrotribological property and mechanism of the\\u000a Cu?Ag?Cr alloy wear studied via wear property tests, scanning electron microscope (SEM), energy dispersive X-ray spectrum\\u000a (EDS) and transmission electron microscopy (TEM). Wear tests were conducted with a specially designed sliding wear tester,\\u000a which simulated the tribological conditions of sliding current

S. G. Jia; P. Liu; F. Z. Ren; B. H. Tian; M. S. Zheng; G. S. Zhou

2007-01-01

214

TL and EPR studies of Cu, Ag and P doped Li2B4O7 phosphor  

Microsoft Academic Search

Key characteristics of a newly prepared tissue-equivalent, highly sensitive thermoluminescence dosimeter, Li2B4O7:Cu,Ag,P, are presented. The material was developed at the Institute of Nuclear Sciences, Belgrade, in the form of sintered pellets. A new preparation procedure has greatly increased the sensitivity of the basic copper activated lithium borate and the glow curve of Li2B4O7 : Cu,Ag,P consists of a well-defined main

N. Can; T. Karali; P. D. Townsend; F. Yildiz

2006-01-01

215

Effects of trace amount addition of rare earth on properties and microstructure of Sn–Ag–Cu alloys  

Microsoft Academic Search

Ternary lead free solder alloys Sn–Ag–Cu were considered as the promising alternatives to conventional SnPb alloys comparing\\u000a with other solders. In the present work, effects of trace amounts of rare earth Ce on the wettability, mechanical properties\\u000a and microstructure of Sn–Ag–Cu solder have been investigated by means of scanning electron microscopy and energy dispersive\\u000a X-ray analysis systematically. The results indicate

Liang Zhang; Song-bai Xue; Li-li Gao; Yan Chen; Sheng-lin Yu; Zhong Sheng; Guang Zeng

2009-01-01

216

Influence of contact geometry and current on effective erosion of Cu-Cr, Ag-WC, and Ag-Cr vacuum contact materials  

Microsoft Academic Search

Effective ac erosion rates were measured for Cu-Cr, Ag-WC, and Ag-Cr butt-type contacts in vacuum contactors, using half-cycle current pulses of 450-600 A rms. The polarity was changed for each operation to ensure uniform effects for both contacts. The contacts parted during the rising current, with the full gap set to 10-30% of the contact diameter. The effective linear volume

Michael Bruce Schulman; Paul G. Slade; Leslie D. Loud; Wangpei Li

1999-01-01

217

Changes in serum biochemical parameters of freshwater fish Oreochromis niloticus following prolonged metal (Ag, Cd, Cr, Cu, Zn) exposures.  

PubMed

Fish serum may reflect status of many biochemical processes in the metabolism. Heavy metals, as environmental stressors, may alter serum biochemical parameters in fishes. Thus, freshwater fish, Oreochromis niloticus, were exposed to low levels (0.05 mg/L) of metals (silver [Ag], cadmium [Cd], copper [Cu], chromium [Cr], zinc [Zn]) to investigate responses of serum biochemical parameters over different exposure periods (0, 5, 10, 20, 30 d). Fish mortality occurred only in Ag exposure, as all fish died between days 12 to 16. Activities of alkaline phosphatase (ALP), alanine transaminase (ALT), and aspartate transaminase (AST) were altered only in Cu- and Cd-exposed fish. Both Cd and Cu exposures decreased the activity of ALP, although they increased the activities of ALT and AST. Glucose concentrations increased in Ag-, Cd-, and Cu-exposed fish, with a sharp increase occurring in Ag-exposed fish before mortality began. Total protein and triglyceride concentrations increased in Ag-exposed fish, although they decreased in Cu-exposed ones. However, all metal exposures increased cholesterol concentration in the serum. Concentration of blood urea nitrogen increased in Ag-, Cd-, and Cu-exposed fish, although it decreased in Cr-exposed ones. Calcium level decreased only in Cu-exposed fish, and Cl(-) level decreased in Ag-exposed fish. Silver and Cu exposures also decreased Na(+) level in the serum. Cadmium and Cu exposures increased serum K(+) levels. The present study, investigating the effects of environmentally realistic metal exposures on serum biochemical parameters, demonstrated that fish serum could sensitively reflect environmental metal stress. Thus, it suggests that serum biochemical parameters could be used as important and sensitive biomarkers in ecotoxicological studies concerning the effects of metal contamination and fish health. PMID:18348636

Oner, Muazzez; Atli, Gülüzar; Canli, Mustafa

2008-02-01

218

Activation energy and excess conductivity analysis of (Ag)x/CuTl-1223 nano-superconductor composites  

NASA Astrophysics Data System (ADS)

Silver (Ag) nanoparticles were added into (Cu0.5Tl0.5)Ba2Ca2Cu3O10-? (CuTl-1223) high Tc superconducting matrix to get (Ag)x/CuTl-1223, x = 0, 0.5, 1.0, 2.0, and 4 wt. %, nano-superconductor composites. The activation energy {U (eV)} and zero resistivity critical temperature {Tc (0)} were increased with increasing contents of Ag nanoparticles in (CuTl-1223) phase up to x = 2.0 wt. %. The increase of activation energy is most probably due to interaction of carriers with the metallic Ag nanoparticles present at grain boundaries of the host CuTl-1223 superconducting matrix. The systematic increase in Tc (0) and gradual decrease in normal state resistivity {?300 K (? cm)} may be due to improved inter-grains coupling by filling up the voids and pores with the inclusion of metallic Ag nanoparticles at the grain-boundaries. There are two possible mechanisms associated with the inclusion of Ag nanoparticles, one is the formation of non-superconducting regions causing the increase of activation energy and other (dominating) is the improved inter-grains connectivity promoting Tc (0). The microscopic parameters (i.e., zero temperature coherence length along c-axis {?c (0)}, inter-layer coupling (J), inter-grain coupling (?), etc.) deduced from the fluctuation induced conductivity analysis reasonably explained the experimental findings.

Hussain, Ghulam; Jabbar, Abdul; Qasim, Irfan; Mumtaz, M.; Nadeem, K.; Zubair, M.; Abbas, S. Qamar; Khurram, A. A.

2014-09-01

219

Interdependent Intermetallic Compound Growth in an Electroless Ni-P/Sn-3.5Ag Reaction Couple  

NASA Astrophysics Data System (ADS)

The interfacial microstructure of electroless Ni-P/Sn-3.5Ag solder joints was investigated after reflow and high-temperature solid-state aging to understand its interdependent growth mechanism and related kinetics of intermetallic compounds (IMCs) at the interface. The reflow and aging results showed that mainly three IMC layers, Ni3Sn4, Ni2SnP, and Ni3P, formed during the soldering reaction. It was found that the Ni3Sn4 and Ni3P layers grow predominantly as long as the electroless Ni-P layer is present; however, once the Ni-P layer is fully consumed, the Ni2SnP layer grows rapidly at the expense of the Ni3P layer. A transition in the Ni3Sn4 morphology from needle and chunky shape to scallop shape was observed after the solid-state aging of reflowed samples. The kinetics data obtained from the growth of compound layers in the aged samples revealed that initially the growth of the Ni2SnP layer is controlled by diffusion, and subsequently by the rate of reaction after the Ni-P metallization is fully consumed. It was found that complete transformation of the electroless Ni-P layer into a Ni3P layer results in the rapid growth of the Ni2SnP layer due to the dominating reaction of Sn with Ni3P. The apparent activation energies for the growth of Ni3Sn4, Ni2SnP, and Ni3P compound layers were found to be 98.9 kJ/mol, 42.2 kJ/mol, and 94.3 kJ/mol, respectively.

Kumar, Aditya; Chen, Zhong

2011-02-01

220

The Influence of Ag and Ag(In) Alloy on Y–Ba–Cu–O Equilibrium Diagram Around the Y-123 Superconducting Phase  

Microsoft Academic Search

We studied the chemical compatibility of Ag, Ag(In)alloy, Y2BaCuO5 (the so-called Y-211 green phase) and YBa2Cu3O7–? (Y-123) phase in order to check if better grain growth and alignment with minimum contamination were possible during the\\u000a Y-123melt texturing. We demonstrate that the addition of silver to Y-123 always led to an enhanced texture. The typical microstructure\\u000a of the composite Y-123 plus

G. A. Costa; E. A. Franceschi; P. Mele

2000-01-01

221

The Electronic Structure and Formation Energies of Ni-doped CuAlO2 by Density Functional Theory Calculation  

NASA Astrophysics Data System (ADS)

The electronic structure and formation energies of Ni-doped CuAlO2 are calculated by first-principles calculations. Our results show that Ni is good for p-type doping in CuAlO2. When Ni is doped into CuAlO2, it prefers to substitute Al-site. NiAl is a shallow acceptor, while NiCu is a deep acceptor and its formation energy is high. Further electronic structure calculations show that strong hybridization happens between Ni-3d and O-2p states for Ni substituting Al-site, while localized Ni-3d states are found for Ni substituting Cu-site.

Xu, Ying; Li, Fei; Sheng, Wei; Nie, Guo-Zheng; Yuan, Ding-Wang

2014-03-01

222

Element-specific study of epitaxial NiO/Ag/CoO/Fe films grown on vicinal Ag(001) using photoemission electron microscopy  

SciTech Connect

NiO/Ag/CoO/Fe single crystalline films are grown epitaxially on a vicinal Ag(001) substrate using molecular beam epitaxy and investigated by photoemission electron microscopy. We find that after zero-field cooling, the in-plane Fe magnetization switches from parallel to perpendicular direction of the atomic steps of the vicinal surface at thinner CoO thickness but remains in its original direction parallel to the steps at thicker CoO thickness. CoO and NiO domain imaging result shows that both CoO/Fe and NiO/CoO spins are perpendicularly coupled, suggesting that the Fe magnetization switching may be associated with the rotatable-frozen spin transition of the CoO film.

Meng, Y.; Li, J.; Tan, A.; Jin, E.; Son, J.; Park, J. S.; Doran, A.; Young, A. T.; Scholl, A.; Arenholz, E.; Wu, J.; Hwang, C.; Zhao, H. W.; Qiu, Z. Q.

2011-01-10

223

Theoretical Research on Ni-like Ag X-ray Laser by Grazing Incidence Pumping  

NASA Astrophysics Data System (ADS)

LLNL proposed a conception of grazing incidence technique using short pulse and realized saturated output of Ni-like Pd x-ray laser using only 450 mJ driving energy. We think that this kind of technique may be adapted to quasisteady state (QSS) collisional scheme with 100ps driving laser. In this paper using our series code Ni-like Ag 13.9 nm XRL driven by laser two 100 ps pulses with grazing incidence was studied. Two different main pulses with intensity of respectively 1.2x1013 Wcm-2 and 4.3x1013 Wcm-2 were considered and optimization to grazing incidence angle ? and time interval t12 was made. And comparisons were made with models with the same pumping conditions except rthat the main pulse came normally with varying t12.

Zhang, G.; Zhang, T.; Zheng, W.; Qiao, X.

224

Mechanical properties and microstructure investigation of Sn-Ag-Cu lead free solder for electronic package applications  

NASA Astrophysics Data System (ADS)

While the electronics industry appears to be focusing on Sn-Ag-Cu as the alloy of choice for lead free electronics assembly, the exact composition varies by geographic region, supplier and user. Add to that dissolved copper and silver from the printed circuit board traces and surface finish, and there can be significant variation in the final solder joint composition. A systematic study of the mechanical and microstructural properties of Sn-Ag-Cu alloys with Ag varying from 2wt% to 4wt% and Cu varying from 0.5wt% to 1.5wt%, was investigated in this research study. Different sample preparation techniques (water quenched, oil quenched and water quenched followed by reflow) were explored and the resulting microstructure compared to that of a typical reflowed lead free chip scale package (CSP) solder joint. Tensile properties such as tensile strength, 0.2% yield strength and the ultimate tensile strength and creep behavior of selected alloy compositions (Sn-4Ag-1.5Cu, Sn-4Ag-0.5Cu, Sn-2Ag-1.5Cu, Sn-2Ag-0.5Cu, Sn-3.5Ag-0.8Cu) were performed for three conditions: as-cast; aged for 100 hours at 125°C; and aged for 250 hours at 125°C. The microstructures of these alloys were examined using light and scanning electron microscopy (LM and SEM) respectively and SEM based energy dispersive x-ray spectroscopy (EDS). Fracture surface and cross-section analysis were performed on the specimens after creep testing. The creep testing results and the effect of high temperature aging on mechanical properties will also be presented for the oil quenched samples. A hyperbolic-sine creep model was adopted and used to fit the creep experiment data. The effect of adding the quaternary element bismuth to the Sn-3.5Ag-0.8Cu alloy on the mechanical properties was measured and compared with the mechanical properties of the ternary alloys. The results of this research study provide necessary data for the modeling of solder joint reliability for a range of Sn-Ag-Cu compositions and a baseline for evaluating the effects of subsequent quaternary additions.

Wang, Qing

225

The Influence of Sn Orientation on Intermetallic Compound Evolution in Idealized Sn-Ag-Cu 305 Interconnects: an Electron Backscatter Diffraction Study of Electromigration  

NASA Astrophysics Data System (ADS)

Previous research showed the relationship between Sn grain orientation and the intermetallic growth rate in Sn-Ag-Cu (SAC)305 interconnects. Samples with the Sn c-axis aligned parallel to the current flow have an intermetallic compound growth rate significantly faster than samples with the c-axis perpendicular to the current flow. This study continues the previous research by investigating intermetallic growth in polygranular joints and in joints that have a thin Ni layer at the cathodic or anodic interface of the interconnect. Planar SAC305 interconnects were sandwiched between two Cu pads (sometimes incorporating a thin Ni layer at the interface) and subjected to uniaxial current. The crystallographic orientation of Sn in these samples was characterized with electron backscatter diffraction before and after electromigration testing. The results show that polycrystalline joints have relatively slow intermetallic growth rates, close to those found in single-crystal joints with the c-axis perpendicular to the current. When a Ni layer was present on the anode side, the intermetallic grew at a rate comparable to that in samples without a Ni layer. However, when the Ni layer was on the cathode side, the intermetallic growth was significantly retarded. The measured growth rates of the intermetallic, combined with literature values for the diffusion of Cu in Sn, were used to calculate values for the effective charge, z *, which is significantly smaller for samples with current parallel to the c-axis than for either polycrystalline samples or samples with the c-axis perpendicular to the electron flow.

Linares, Xioranny; Kinney, Chris; Lee, Kyu-Oh; Morris, J. W.

2014-01-01

226

Electron configuration and charge state of electrically active Cu, Ag and Au ions in ZnSe  

Microsoft Academic Search

The Hall effect, electrical conductivity and electron mobility are investigated at temperatures between 55 and 500 K in n-ZnSe crystals doped with Cu, Ag or Au. The presence of a small amount of Cu atoms leads to an inversion of the sign of the Hall coefficient at temperatures above 300 K. Anomalous temperature dependence of the electron mobility is observed

N. D. Nedeoglo; V. P. Sirkeli; D. D. Nedeoglo; R. Laiho; E. Lähderanta

2006-01-01

227

Exploring highly correlated materials via electron pair emission: the case of NiO/Ag(100)  

NASA Astrophysics Data System (ADS)

Metal oxides like NiO are usually termed ‘highly correlated’, because the material properties are decisively determined by the electron-electron interaction. This makes them interesting candidates for electron pair spectroscopy which is particularly sensitive to the electron correlation. We have prepared ultrathin NiO/Ag(100) films and studied the electron pair emission upon electron impact. Compared to the metal substrate we observe an increase of the coincidence intensity by a factor of 8 for NiO. Thickness dependent measurements prove that this enhancement is an intrinsic effect rather than due to a mean free path increase of the oxide. The Néel temperature TN of NiO films displays a thickness dependence which allows us to tune TN. We performed temperature dependent measurements and observed no temperature dependence of the coincidence spectra. This proves that the electron pair emission probes the local correlation rather than long range order. An enhanced coincidence intensity was also found for other oxide phases compared to their corresponding metal phases.

Schumann, F. O.; Behnke, L.; Li, C. H.; Kirschner, J.

2013-03-01

228

Brazing of hot isostatically pressed-Al 2 O 3 to stainless steel (AlSl 304L) by Mo-Mn route using 72Ag28Cu braze  

Microsoft Academic Search

Joining of stainless steel (AISI 304L) to hot isostatically pressed alumina (HIP-Al2O3) using the brazing alloy 72Ag-28Cu was investigated. The microstructural characterization at various stages of joining, including\\u000a metallization, annealing of overlaid Ni coating, and brazing, was comprehensively evaluated. The interface structure and the\\u000a growth of phases were analyzed with optical microscope, scanning electron microscope, and electron probe microanalyzer (EPMA).

P. Mishra; S. N. Athavale; A. L. Pappachan; A. K. Grover; A. K. Suri; P. Sengupta; G. B. Kale; K. Bhanumurthy; P. K. De

2005-01-01

229

Formation of the Intermetallic Compounds Between Liquid Sn Different Cu-Ni Metalization.  

National Technical Information Service (NTIS)

Interfacial reactions between liquid tin and different Cu-Ni alloy metallizations as well as the subsequent phase transformations during the cooling were investigated with the emphasis on microstructures of the reaction zones. It was found out that the ex...

V. Vuorinen, T. M. Kohonen, J. K. Kivilahti

2001-01-01

230

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

231

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

232

Study of the liquidus and solidus surfaces of the quaternary Fe-Ni-Cu-S system: V. Refinement and addition of the data on the ternary Fe-Ni-S and Fe-Ni-Cu phase diagrams  

NASA Astrophysics Data System (ADS)

A deep analysis and mutual fitting of the data on all ternary boundary systems have resulted in obtaining information about the phase transformations in high-sulfur Fe-Ni-S compositions and in augmentation of data on the projections of the solidus surfaces in the Fe-Ni-Cu and Fe-Ni-S systems. The studies are performed using differential thermal analysis, scanning electron microscopy, and electron-probe microanalysis. The investigation carried out is a continuation of the cycle of studies dealing with an experimental construction of the phase diagrams of the ternary systems bounding the quaternary Fe-Ni-Cu-S system.

Starykh, R. V.; Sineva, S. I.

2012-03-01

233

Cast-Replicated NiTiCu Foams with Superelastic Properties  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

234

The thermal cycling effect on Ti-Ni-Cu shape memory alloy  

SciTech Connect

Nearly equiatomic Ni-Ti alloys are known as the best shape memory alloys for their outstanding shape memory characteristics including shape memory effect and transformation pseudoelasticity. The present study was conducted to compare the transformation behaviors of Ni-Ti and Ti-Ni-Cu alloys during cycling. The samples were first subjected to one of the following 3 treatments: solution treatment; annealing after cold working; aging after solution treatment and then were thermal cycled under exactly the same conditions before they were examined by means of electrical resistivity measurements. One of the strengths of Ni-Ti alloy systems, besides good shape memory properties, has always been their high resistance to corrosion. This has made much practical use possible. Naturally, when the authors adopt the Cu-replacement approach in establishing with the new Ti-Ni-Cu systems, they want to make sure this resistance to corrosion will not be sacrificed. Tests to this effect were included in the experiment.

Jean, R.D.; Duh, J.B. [Industrial Technology Research Inst., Hsinchu (Taiwan, Province of China). Materials Research Lab.] [Industrial Technology Research Inst., Hsinchu (Taiwan, Province of China). Materials Research Lab.

1995-03-15

235

Effect of substrate temperature on structural, optical and electrical properties of sputtered NiO-Ag nanocrystalline thin films  

NASA Astrophysics Data System (ADS)

NiO-Ag thin films were deposited on Corning 7059 glass substrates by DC reactive magnetron sputtering technique and investigated the substrate temperature ( T s ) dependent properties of NiO-Ag thin films. X-ray diffraction results showed that crystalline films can be obtained at high T s and all films have a preferred crystal growth texture with face centered cubic ( f cc ) structure and was also confirmed by Raman studies. The grain size, transmittance, band gap, mobility and carrier concentrations were increased with T s . Room temperature deposited films have an average roughness around 6.9 nm where as increment of T s resulted in increased roughness up to 14 nm with nanocrystalline morphology. The optimum substrate temperature to obtain NiO-Ag films was found to be 200°C. It was found that with increasing the T s , resistivity of the films was significantly decreased.

Ashok Kumar Reddy, Y.; Ajitha, B.; Sreedhara Reddy, P.; Siva Pratap Reddy, M.; Lee, Jung-Hee

2014-09-01

236

Cu - Ni oxides obtained by laser and thermal processing of mixed salts  

Microsoft Academic Search

This work presents new results on Cu - Ni oxides obtained by IR thermochemical laser processing of controlled mixtures of metal salts. The CuO and NiO oxides were characterized by several analytical methods, such as x-ray photoelectron spectroscopy, x-ray diffraction and IR spectrometry. Compared with the reaction products obtained in classical thermal decomposition, as well as with mixtures of the

R. Alexandrescu; I. Morjan; I. Voicu; G. Pugna; S. Petcu; A. Crunteanu; C. Popescu; D. Fatu

1997-01-01

237

Cyclic stress-strain characteristics of Ti?Ni and Ti?Ni?Cu shape memory alloys  

Microsoft Academic Search

The authors have examined the responses of three types of Ti?Ni and three types of Ti?Ni?Cu shape memory alloys in a pseudoelastic state to mechanical cycling in hard cycles with a constant emax and in soft cycles with a constant ?max. It was found that the transformation stress of the B2 parent phase into martensite and the hysteresis (or the

B. Strnadel; S. Ohashi; H. Ohtsuka; T. Ishihara; S. Miyazaki

1995-01-01

238

Comparative internal friction and modulus evolutions in Ni-Ti and Ni-Ti-Cu shape memory alloys  

Microsoft Academic Search

Internal friction and modulus measurements are performed for the purpose of a comparative study between the structural evolutions occurring, under the effect of the temperature, in two kinds of shape memory alloys: Ni-Ti and Ni-Ti-Cu. Modulus evolutions giving information about the changes in the relative percentages of martensitic and B2 high temperature phases, are useful for the determination of ``start''

K. Goubaa; M. Masse; G. Bouquet

1992-01-01

239

Thermodynamic properties in the clathrate-type silver- and copper-oxide: Ag6 O8MX and Cu6O8MX (M = cation, X = anion)  

NASA Astrophysics Data System (ADS)

We present the thermodynamic properties in the clathrate-type silver- and copper-oxides Ag6O8MX and Cu6O8MX (M = cation, X = anion) compounds, having Ag6O8 (or Cu6O8)-cage in their crystal structure. Ag6O8MX and Cu6O8MX are crystallized in a cubic structure with a space group of Fm3¯m. We synthesized high quality samples of Ag6O8MX and Cu6O8MX and examined the electrical resistivity, magnetic susceptibility, and specific heat measurements. The superconductivity in Ag6O8AgX (X = NO3- and HF2- have an isotropic gap symmetry by means of the specific heat data. In Cu6O8MCl, the ground sata of Cu6O8MCl compounds changed metallic to semiconducting by changing the valence state of M site ion.

Kawashima, K.; Tozawa, H.; Maruyama, M.; Ichinokawa, R.; Sugiyama, T.; Akimitsu, J.

2010-12-01

240

Thermodynamic properties in the clathrate-type silver- and copper-oxide: Ag 6 O 8MX and Cu 6O 8MX (M = cation, X = anion)  

NASA Astrophysics Data System (ADS)

We present the thermodynamic properties in the clathrate-type silver- and copper-oxides Ag 6O 8MX and Cu 6O 8MX (M = cation, X = anion) compounds, having Ag 6O 8 (or Cu 6O 8)-cage in their crystal structure. Ag 6O 8MX and Cu 6O 8MX are crystallized in a cubic structure with a space group of Fm3barm. We synthesized high quality samples of Ag 6O 8MX and Cu 6O 8MX and examined the electrical resistivity, magnetic susceptibility, and specific heat measurements. The superconductivity in Ag 6O 8AgX (X = NO3- and HF2- have an isotropic gap symmetry by means of the specific heat data. In Cu 6O 8MCl, the ground sata of Cu 6O 8MCl compounds changed metallic to semiconducting by changing the valence state of M site ion.

Kawashima, K.; Tozawa, H.; Maruyama, M.; Ichinokawa, R.; Sugiyama, T.; Akimitsu, J.

241

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

242

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 100 h 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

243

Intermetallic Formation and Fluidity in Sn-Rich Sn-Cu-Ni Alloys  

NASA Astrophysics Data System (ADS)

This paper investigates the phase equilibria and solidification behavior of Sn-Cu-Ni alloys with compositions in the range of 0 wt.% to 1.5 wt.% Cu and 0 wt.% to 0.3 wt.% Ni. The isothermal section at 268°C in the Sn-rich corner was determined. No evidence for a ternary phase was found, and the section is in good agreement with past experimental studies that report wide solubility ranges for (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4. The vacuum fluidity test was applied to compositions that are liquid at 268°C to map the variation in microstructure and flow behavior with composition in this system. Significant variations in fluidity length were measured among the Sn-Cu-Ni alloys, and the variations correlate with the microstructure that develops during solidification. The generated fluidity map enables the selection of Sn-Cu-Ni solder compositions that exhibit good fluidity behavior during solidification and form near-eutectic microstructures.

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

2010-01-01

244

AgCuVO4 : A quasi-one-dimensional S=(1)/(2) chain compound  

NASA Astrophysics Data System (ADS)

We present a joint experimental and computational study of the recently synthesized spin 1/2 system silver-copper-orthovanadate AgCuVO4 [A. Möller and J. Jainski, Z. Anorg. Allg. Chem. 634, 1669 (2008)] exhibiting chains of trans corner-sharing [CuO4] plaquettes. The static magnetic susceptibility and specific heat measurements of AgCuVO4 can be described to a good approximation by the Bonner-Fisher spin-chain model with Jintra?330K . Evidence for a Néel-type of order at ˜2.5K is obtained from the specific heat and corroborated by ESR studies. To independently obtain a microscopically based magnetic model, density functional electronic structure calculations were performed. In good agreement with the experimental data, we find pronounced one-dimensional magnetic exchange along the corner-sharing chains with small interchain couplings. The difference between the experimentally observed and the calculated ordering temperature can be assigned to a sizable interchain frustration derived from the calculations.

Möller, A.; Schmitt, M.; Schnelle, W.; Förster, T.; Rosner, H.

2009-09-01

245

Granularity controlled percolative current conduction in YBa2Cu3O7/Ag composite thick films  

NASA Astrophysics Data System (ADS)

Temperature-dependent electrical resistivity in a set of YBa2Cu3O7/Ag thick films prepared by reaction diffusion technique is analysed to estimate the extent of granularity in them. Percolative nature of charge transfer in the films was examined by studying the excess conductivity in the superconducting order parameter fluctuation (SCOPF) region (T ? Tc), the approach to zero-resistance state in the tail region, the current-controlled tailing of the resistivity transition near Tc0(Tc0 < T < Tc0) and the current-voltage characteristics in the paracoherent regime (T < Tc0) with their associated exponents. The percolative current model was thus utilized to quantify granularity in the films of such parameters like the weak link resistivity across grain boundaries, current path lengthening factor arising due to grain misalignment, and due to voids and cracks. Evolution of these parameters with Ag content in the films indicates reduced structural defects (voids and cracks) at higher Ag concentrations. The result points to a mechanism of grain growth in the composites, which accounts for the improved grain growth with narrower grain size distribution in these systems as compared to that in Ag-free YBCO sintered material. These microstructural modifications cause lowering of percolation threshold from the value expected in a granular system where the grain size approaches to one of the system dimensions (the film thickness) making the conduction through grain boundary essentially two-dimensional.

Behera, D.; Mishra, N. C.

2002-01-01

246

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

247

Optical and electrochemical properties of Cu-doped NiO films prepared by electrochemical deposition  

NASA Astrophysics Data System (ADS)

Cu-doped nickel oxide (NiO) thin films were prepared by electrochemial deposition (cathodic deposition) technique onto the fluorine doped tin oxide (F: SnO 2; FTO) coated glass substrates from organic solutions. Effects of Cu content on the morphology, structure, optical and electrochromic properties of NiO films were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible spectrophotometer (UV-vis) and cyclic voltammetry (CV), respectively. SEM images indicated the formation of nanorods after Cu was added. The films were formed with amorphous or short-range ordered NiO grains and a trace of face-centered cubic Ni xCu 1- xO confirmed by XRD. The transmittances of both bleached state and colored state were significantly lowered when Cu was added. The NiO films doped with Cu (the molar ratio was 1/8) exhibited the optimum electrochromic behavior with a variation of transmittance (? T) up to ˜80% at the wavelength range of 350-600 nm. Cu doping reduces the response time for both the coloring and bleaching states, and the reversibility of the redox reaction was increased as well.

Zhao, Lili; Su, Ge; Liu, Wei; Cao, Lixin; Wang, Jing; Dong, Zheng; Song, Meiqin

2011-02-01

248

Spin alignment of surface oxidized CoxNi1-x/Cu(001)  

NASA Astrophysics Data System (ADS)

We investigated the ferromagnetic (FM)/antiferromagnetic (AF) spin alignment of a 13 monolayer oxidized CoxNi1-x/Cu(001) (x = 0 or 0.05) surface by X-ray magnetic circular dichroism and X-ray magnetic linear dichroism photoemission electron microscopy (XMCD-PEEM and XMLD-PEEM). Surface NiO and the underlying Ni (CoxNi1-x) were found to be AF and FM by analyzing the gray scale of XMLD-PEEM and XMCD-PEEM images; this indicates the spin orientation with respect to the polarization of the incident X-ray. We found both collinear and perpendicular alignment of the FM and AF spins. This suggests that the AF NiO is magnetically random, resulting in coercivity enhancement without exchange bias in the surface-oxidized CoxNi1-x/Cu(001) films.

Shih, Ying-Ta; Tsai, Chung-Wei; Su, Chien-Yu; Pan, Wei; Wei, Der-Hsin; Chan, Yuet-Loy; Chang, Hui-Ching

2013-05-01

249

Microstructure and thermal fatigue life of BGAs with eutectic Sn-Ag-Cu balls assembled at 210\\/spl deg\\/C with eutectic Sn-Pb solder paste  

Microsoft Academic Search

Conventionally, it has been understood that in order to assemble BGAs with eutectic Sn-Ag-Cu solder balls in eutectic Sn-Pb solder paste, a reflow profile having a peak temperature higher than 217degC, which is the melting point of eutectic Sn-Ag-Cu, would be required to achieve complete mixing of the Sn-Pb paste and the Sn-Ag-Cu ball. Nevertheless, it was observed in this

N. Nandagopal; Zequn Mei; Sue Teng

2006-01-01

250

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

251

Thermoelectric Characteristics of a Commercialized Mg2Si Source Doped with Al, Bi, Ag, and Cu  

NASA Astrophysics Data System (ADS)

The thermoelectric characteristics of commercial polycrystalline Mg2Si doped with Bi, Al + Bi, Ag, and Cu were examined. The samples for the thermoelectric measurements were prepared using the plasma-activated sintering (PAS) technique. The measured values of the Seebeck coefficient were compared with values calculated using the all-electron band-structure calculation package (ABCAP) based on a full-potential augmented-plane-wave (FLAPW) band-structure calculation in a local density approximation (LDA). For the Bi + Al-co-doped samples, the observed values of the dimensionless figure of merit, ZT, were higher than those of solely Bi-doped samples. The maximum value obtained for Bi + Al-doped Mg2Si was 0.77 at 862 K. For the Ag-doped samples, ZT was significantly lower than that of the Bi + Al-doped samples, with the maximum value being about 0.11 at 873 K.

Sakamoto, Tatsuya; Iida, Tsutomu; Matsumoto, Atsunobu; Honda, Yasuhiko; Nemoto, Takashi; Sato, Junichi; Nakajima, Tadao; Taguchi, Hirohisa; Takanashi, Yoshifumi

2010-09-01

252

Bonding of Cf/SiC composite to Invar alloy using an active cement, Ag-Cu eutectic and Cu interlayer  

NASA Astrophysics Data System (ADS)

The interfacial microstructures and mechanical properties of the joints formed by active cement added brazing in vacuum of Cf/SiC composite to Invar alloy, using Ag-Cu eutectic alloy and pure copper foil as braze alloy and interlayer respectively, were investigated. CuTi, Cu4Ti3, Fe2Ti and the reaction layer of TiC and Si were the predominant components at the joint interface. The maximum shear strength of the joint was 77 MPa for brazing at 850 °C for 15 min. The results show that active cement added brazing in vacuum using Ag-Cu eutectic alloy and Cu interlayer can be used successfully for joining Cf/SiC composites to Invar alloy.

Lei, Zhao; Xiaohong, Li; Jinbao, Hou; Qiang, Sun; Fuli, Zhang

2012-10-01

253

Comparative internal friction and modulus evolutions in Ni-Ti and Ni-Ti-Cu shape memory alloys  

NASA Astrophysics Data System (ADS)

Internal friction and modulus measurements are performed for the purpose of a comparative study between the structural evolutions occurring, under the effect of the temperature, in two kinds of shape memory alloys: Ni-Ti and Ni-Ti-Cu. Modulus evolutions giving information about the changes in the relative percentages of martensitic and B2 high temperature phases, are useful for the determination of “start” and “finish” transformation temperatures. Internal friction measurements, specially sensitive to structural changes occurring on atomic scale, allow the detection of atomic reorganizations preceding or following the transformation: the R-phase occurrence, on cooling or on heating, the reorientation of martensitic variants on heating. The comparison between the internal friction background levels of each alloy reveals the effect of structural instabilities, specific of Ni-Ti-Cu alloys, and which can be associated with the Cu content. Des mesures de frottement intérieur et de module ont été utilisées en vue de comparer les évolutions structurales intervenant, en fonction de la température, dans deux familles d'alliages à mémoire de forme: Ni-Ti et Ni-Ti-Cu. Les variations de module, sensibles aux proportions relatives des phases martensitique et B2 de haute température, s'avèrent très adaptées à la détermination précise des températures de début et de fin de transformation. Le frottement intérieur, quant à lui, donne des renseignements sur des réorganisations se produisant, à l'échelle atomique, avant ou après la transformation martensitique: apparition de la phase-R, réorientation de variantes de martensite, par exemple,. La comparaison des niveaux du fond de frottement intérieur, relatifs à chaque alliage, montre des différences qui peuvent être associées à des instabilités structurales spécifiques de la présence de cuivre dans les allianges Ni-Ti-Cu.

Goubaa, K.; Masse, M.; Bouquet, G.

1992-08-01

254

Effect of cooling rate on the microstructure and microhardness of the CuZrAgAl alloy  

SciTech Connect

The effect of cooling rate on the microstructure and microhardness of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} (at.%) alloy has been studied. The crystalline phases were characterized by X-ray diffraction, optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy, and identified as AlCu{sub 2}Zr, Cu{sub 10}Zr{sub 7} and CuZr{sub 2}. The solidification sequence was established as following: the Cu{sub 10}Zr{sub 7} phase forms first in the periphery of the rod, then following with AlCu{sub 2}Zr phase in the rod center and finally CuZr{sub 2} crystals in Cu-depleted areas. The effect of crystals on the mechanical properties of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was also estimated through the microhardness. According to the value of microhardness, inhomogeneous structure of the amorphous matrix is more easily formed for the alloy in the low cooling rate (i.e., 9 mm) as compared with the alloy with fully amorphous state in the large cooling rate (i.e., 3 mm). This inhomogeneous structure was attributed to the composition change of amorphous matrix arising from the forming of crystalline phases due to the low cooling rate. - Highlights: Black-Right-Pointing-Pointer The crystalline phases in the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy were identified. Black-Right-Pointing-Pointer The solidification sequence of Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was verified. Black-Right-Pointing-Pointer The softening and hardening of alloy could be observed due to the crystallization.

Liu, Y., E-mail: liuyonggreg@yahoo.com.cn [Department of Mechanical Engineering, Nanchang University, 330031 Nanchang (China); Blandin, J.J.; Suery, M.; Kapelski, G. [SIMAP/GPM2, Grenoble-INP, CNRS, UJF, 38402 Saint-Martin d'Heres Cedex (France)

2012-08-15

255

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

256

Interfacial structure of Si3N4 brazed with an Ag-Cu-Ti alloy  

NASA Astrophysics Data System (ADS)

Single crystal Si3N4 was brazed using a Ag-Cu eutectic alloy containing 2 percent Ti at 950 C for 30 min and the interface was observed by high resolution electron microscopy. A layer of reaction products is formed between the Si3N4 and the brazed metal. TiN and Ti2N are formed near the interface; however, only TiN is found at the interface in contact with the Si3N4. A crystallographic orientation relationship was found between the TiN and Si3N4 in which the N atoms are shared between the two structures with little distortion.

Suematsu, H.; Petrovic, J. J.; Mitchell, T. E.; Yano, T.

257

Communication: Striking dependence of diffusion kinetics in Ag-Cu nanoalloys upon composition and quantum effects  

NASA Astrophysics Data System (ADS)

The kinetics of elemental inter-diffusion in Ag-Cu nanoalloys of 32-34 atoms around 80:20 composition is theoretically investigated by combining analytic-potential and first-principles calculations. An extremely varied behavior is found, with transformation times ranging from tens of nanoseconds to weeks at room temperature in a narrow interval of size and composition, also depending on quantum effects in magic clusters. Predictions are consistent with time-of-flight experiments and suggest their interpretation in a new light.

Asgari, Mehdi; Negreiros, Fabio R.; Sementa, Luca; Barcaro, Giovanni; Behnejad, Hassan; Fortunelli, Alessandro

2014-07-01

258

Study of anti-clockwise bipolar resistive switching in Ag/NiO/ITO heterojunction assembly  

NASA Astrophysics Data System (ADS)

The anti-clockwise bipolar resistive switching in Ag/NiO/ITO (Indium-Tin-Oxide) heterojunctional thin film assembly is investigated. A sequential voltage sweep in 0 ? V max ? 0 ? - V min ? 0 order shows intrinsic hysteresis behaviour and resistive switching in current density ( J)-voltage ( V) measurements at room temperature. Switching is induced by possible rupture and recovery of the conducting filaments in NiO layer mediated by oxygen ion migration and interfacial effects at NiO/ITO junction. In the high-resistance OFF-state space charge limited current passes through the filamentary path created by oxygen ion vacancies. In OFF-state, the resistive switching behaviour is attributed to trapping and detrapping processes in shallow trap states mostly consisting of oxygen vacancies. The slope of Log I vs Log V plots, in shallow trap region of space charge limited conduction is ~2 ( I ? V 2) followed by trap-filled and trap-free conduction. In the low-resistance ON-state, the observed electrical features are governed by the ohmic conduction.

Mitra, Subarna; Chakraborty, Suvankar; Menon, Krishnakumar S. R.

2014-06-01

259

Removal of Cu2+ and Ag+ from aqueous solution on a chemically-carbonized sorbent from date palm leaflets.  

PubMed

A chemically-carbonized sorbent was prepared from date palm leaflets by sulphuric acid treatment at 170 degrees C. Carbonization took place via the dehydration effect of the hot sulphuric acid producing a carbon with reduction property. Sorption of Cu2+ and Ag+ from aqueous solution was investigated in terms of pH, contact time, metal concentration and temperature. A peculiar behaviour was found for the sorption of the two metals on the produced carbon. Sorption of Cu2+ was fast, reaching equilibrium within -2 h, whilst Ag+ sorption was slow and required -60 h to reach equilibrium. Activation energy (E(a)) for Cu2+ sorption was -16.1 kJ/mol indicating a diffusion-controlled ion exchange process; however, E(a) for Ag+ sorption was -44.3 kJ/mol indicating a chemically controlled process. Equilibrium sorption data were tested for the Langmuir and Freundlich equations. Sorption capacity appears to be much higher for Ag+ than for Cu2+ with increased uptake, for both metals, when increasing the temperature (25-45 degrees C). Ag+ was reduced to elemental silver on the sorbent surface and this was confirmed using scanning electron microscopy and x-ray powder diffraction; however, no reduction processes were involved in Cu2+ sorption. This paper discusses the sorption mechanism. PMID:23530353

El-Shafey, El-Said Ibrahim; Al-Kindy, Salma Muhammed Zahran

2013-01-01

260

Phonons, nature of bonding, and their relation to anomalous thermal expansion behavior of M2O (M = Au, Ag, Cu)  

NASA Astrophysics Data System (ADS)

We report a comparative study of the dynamics of Cu2O, Ag2O, and Au2O (i.e., M2O with M = Au, Ag, and Cu) using first principle calculations based on the density functional theory. Here, for the first time, we show that the nature of chemical bonding and open space in the unit cell are directly related to the magnitude of thermal expansion coefficient. A good match between the calculated phonon density of states and that derived from inelastic neutron scattering measurements is obtained for Cu2O and Ag2O. The calculated thermal expansions of Ag2O and Cu2O are negative, in agreement with available experimental data, while it is found to be positive for Au2O. We identify the low energy phonon modes responsible for this anomalous thermal expansion. We further calculate the charge density in the three compounds and find that the magnitude of the ionic character of the Ag2O, Cu2O, and Au2O crystals is in decreasing order, with an Au-O bond of covalent nature strongly rigidifying the Au4O tetrahedral units. The nature of the chemical bonding is also found to be an important ingredient to understand the large shift of the phonon frequencies of these solids with pressure and temperature. In particular, the quartic component of the anharmonic term in the crystal potential is able to account for the temperature dependence of the phonon modes.

Gupta, M. K.; Mittal, R.; Chaplot, S. L.; Rols, S.

2014-03-01

261

Crystallization studies on amorphous AI-Y-Ni and AI-Y-Cu alloys  

Microsoft Academic Search

AI83Y10Ni7, AI80Y10Ni10 and AI80Y10Cu10 alloys were studied by the rapid solidification processing route. The glass-forming ability was found to decrease in the order of alloys mentioned above. Differential scanning calorimetry (DSC) of these amorphous alloys showed that the amorphous phase in AI-Y-Ni alloys has a higher thermal stability when compared to that in AI-Y-Cu alloys. A four-stage crystallization sequence could

A. Goyal; B. S. Murty; S. Ranganathan

1993-01-01

262

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

263

Hydrothermal synthesis and optical characterization of Ni-doped CuCrO2 nanocrystals  

NASA Astrophysics Data System (ADS)

We first synthesized the Ni2+ doped CuCrO2 compound using the hydrothermal method at 420 °C and 150 MPa. Hydrothermal experiments were performed in steel autoclaves based on a 12NiCr250 alloy. The structure of CuCr1-xNixO2 (0 ? x ? 0.04) belonging to the rhombohedral space group R3m was confirmed using x-ray diffraction; along the rhombohedral phase for x = 0, a small amount of 2H-CuCrO2 (crystallizing in the hexagonal system) was observed. By increasing doping from x = 0 to 0.04, an increase of the elementary volume of the cell is emphasized by shifting the diffraction maxims in the x-ray diffraction spectrum. If the Ni amount in the CuCr1-xNixO2 compound increases, the grain size decreases from 36 nm (x = 0) to 10 nm (x = 0.04). Scanning electron microscope images highlight the nanocrystalline nature of the obtained product. Element distributionmapping shows that Ni2+ is uniformly distributed in a homogeneous sample. The band gap energy (Eg) of undoped and Ni-doped CuCrO2 was calculated from the diffuse spectral reflectance. Increasing the Ni2+ amount from x = 0 to 0.04 led to band gap increases from Eg = 3.04 to 3.1 eV.

Ursu, D. H.; Micl?u, M.; B?nic?, R.; Grozescu, I.

2013-11-01

264

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

265

A cervelleite-like mineral and other Ag-Cu-Te-S minerals [Ag2CuTeS and (Ag,Cu)2TeS] in gold-bearing veins in metamorphic rocks of the Cycladic Blueschist Unit, Kallianou, Evia Island, Greece  

NASA Astrophysics Data System (ADS)

A cervelleite-like mineral, two unnamed silver sulfotellurides in the system Ag-Cu-Te-S [Ag2CuTeS, (Ag,Cu)2TeS], Te-rich polybasite and cadmian tetrahedrite occur in gold-bearing quartz veins in metapelites and faults within brecciated marbles of the Cycladic Blueschist Unit in the Kallianou area (southern Evia Island, Greece). The quartz veins and faults are discordant to syn-metamorphic structures and formed during ductile to brittle deformation in the final stages of exhumation of the Styra Nappe extrusion wedge (~21 Ma). Te-rich polybasite (up to 7.4 wt. % Te), cadmian tetrahedrite (up to 12.4 wt. % Cd), together with electrum (23-54 wt. % Ag) and the sulfotellurides, are the main silver carriers in the mineralization. The two unnamed sulfotellurides, Ag2CuTeS and (Ag,Cu)2TeS are believed to be new quaternary minerals in the system Ag-Cu-Te-S. These minerals and the cervelleite-like phase could have exsolved from galena during cooling (below 200°C). Initial temperatures for the formation of the sulfotellurides, in the form of hessite-intermediate solid solution, at Kallianou may be up to 300°C under log fS2 values between ~ -11.5 to -8.3, and log fTe2 from ~ -14.8 to -7.8. The values of log fTe2 and log fS2 during re-equilibration (at ~200°C) were constrained to -19.5 to -15.2 and to -15.8 to -11.5 respectively.

Voudouris, Panagiotis Christos; Spry, Paul G.; Sakellaris, Gregory Aarne; Mavrogonatos, Constantinos

2011-03-01

266

Cast bulk Zr 57Ti 5Al 10Cu 20Ni 8 amorphous alloy with tendency of phase separation  

Microsoft Academic Search

Zr-Ti-Al-Cu-Ni alloys show excellent glass forming ability (GFA), Amorphous cylindrical samples of diameter from 8 to 20 mm were produced by casting the Zr57Cu20Al10Ni8Ti5 alloy melt into a copper mould. The Zr57Cu20Al10Ni8Ti5 amorphous alloy shows some particular crystallization characteristics: measurements by differential scanning calorimetry (DSC) reveal three exothermic peaks in the DSC traces at continuous heating. The third peak of

L. Q. Xing; G. P. Gorier; D. M. Herlach

1997-01-01

267

The cycling of Ni, Zn, Cu in the system “mine tailings–ground water–plants”: A case study  

Microsoft Academic Search

The comparative behaviour of Ni, Cu and Zn in the system “mine tailings–ground water–plants” has been investigated at the Ni–Cu mine site operated by INCO Ltd. Thompson Operations, Thompson, Manitoba. Oxidation of sulphide minerals causes the release of metals from exposed tailings containing Ni ?2000ppm, Cu ?150ppm and Zn ?100ppm to the ground water, which contains 350mg\\/LNi, 0.007mg\\/LCu, and 1.6mg\\/LZn.

Nikolay V. Sidenko; Elena I. Khozhina; Barbara L. Sherriff

2007-01-01

268

Microstructure evolution of Al12SiCuNiMg alloy under high temperature low cycle fatigue  

E-print Network

Microstructure evolution of Al­12Si­CuNiMg alloy under high temperature low cycle fatigue Jinxiang March 2013 Keywords: Al­12Si­CuNiMg alloy Microstructure evolution Fatigue Cyclic softening a b s t r a c t Microstructure evolution of the Al­12Si­CuNiMg alloy under high temperature low cycle fatigue

Volinsky, Alex A.

269

Effects of Dy 2BaCuO 5 contents on microstructure and mechanical strength of Ag-added Dy–Ba–Cu–O bulk superconductors  

Microsoft Academic Search

We investigated the microstructure and mechanical strength of Ag-added DyBa2Cu3Oy (Dy123) bulk superconductors with various Dy2BaCuO5 (Dy211) contents. Single-grain Dy123 bulk samples 32 mm in diameter with the addition of 5-40 mol% of Dy211 and 10 wt.% of Ag2O were fabricated in air. The sample with 5 mol% Dy211 contained many macro-cracks in the ab-plane. The amount of cracks decreased

S. Nariki; N. Sakai; M. Murakami; I. Hirabayashi

2004-01-01

270

Structure and electrical properties of liquid Sn, Sn 0.962 Ag 0.038 , Sn 0.987 Cu 0.013 , and Sn 0.949 Ag 0.038 Cu 0.013  

Microsoft Academic Search

We have studied the structure, electrical conductivity, and thermopower of liquid Sn, Sn0.962Ag0.038, Sn0.987Cu0.013, and Sn0.949Ag0.038Cu0.013 alloys, which are used as lead-free solders. Diffraction data have been used to develop structural models of the melts. The\\u000a conductivity and thermopower data have been interpreted in terms of the proposed structural models and resonance s-d scattering.

S. I. Mudry; V. M. Sklyarchuk; Yu. O. Plevachuk; I. I. Shtablavyi

2008-01-01

271

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

SciTech Connect

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

Sengar, Saurabh K.; Mehta, B. R. [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)] [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Kulriya, P. K.; Khan, S. A. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)] [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

2013-10-21

272

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

273

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 Fd3barc, with cell parameters: a = 12.1987(5) Å, and V = 1815.3(2) Å3. 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

274

Electrochemical Behavior of Sintered CuAg4 at. pct Alloy  

NASA Astrophysics Data System (ADS)

The electrochemical characteristics of sintered CuAg4 at. pct alloy in different stages of synthesis and thermomechanical treatment were examined by cyclic voltammetry in a NaOH medium. On the voltammograms recorded at the sintered alloy, six current waves can be noticed at the anodic part, and six corresponding current waves are observed at the cathodic part. A possible electrochemical reaction is attributed to each wave. The effect of the potential reversing limit was used to distinguish the correlation between the anodic and cathodic peaks. After the deformation with 60 pct deformation degree, the alloy becomes more corrosion resistant, whereas the corrosion mechanism remains the same as before mechanical treatment. Subsequent anneal of the deformed alloy at 533 K (260 °C) for 150 minutes leads to the hardening effect. At the same time, the alloy remains corrosion stable, and some of the current waves present at the other voltammograms are hardly noticeable here. Also, we propose our own model of oxide layer formation on the surface of a Cu-Ag alloy.

Raj?i?-Vujasinovi?, Mirjana; Nestorovi?, Svetlana; Grekulovi?, Vesna; Markovi?, Ivana; Stevi?, Zoran

2010-10-01

275

Adsorption of Ag, Cu and Hg from aqueous solutions using expanded perlite.  

PubMed

The aim of the present work was to investigate the ability of expanded perlite (EP) to remove of silver, copper and mercury ions from aqueous solutions. Batch adsorption experiments were carried out and the effect of pH, adsorbent dosage, contact time and temperature of solution on the removal process has been investigated. The optimum pH for the adsorption was found to be 6.5. Adsorption of these metal ions reached their equilibrium concentration in 120, 240 and 180 min for Ag (I), Cu (II) and Hg (II) ions, respectively. Experimental data were also evaluated in terms of kinetic characteristics of adsorption and it was found that adsorption process for these metal ions followed well pseudo-second-order kinetics. Using Langmuir isotherm model, maximum adsorption capacity of EP was found to be 8.46, 1.95 and 0.35 mg/g for Ag (I), Cu (II) and Hg (II) ions, respectively. Finally, the thermodynamic parameters including, the change of free energy (DeltaG degrees ), enthalpy (DeltaH degrees ) and entropy (DeltaS degrees ) of adsorption were calculated for each metal ion. The results showed that the adsorption of these metal ions on EP was feasible and exothermic at 20-50 degrees C. PMID:20096505

Ghassabzadeh, Hamid; Mohadespour, Ahmad; Torab-Mostaedi, Meisam; Zaheri, Parisa; Maragheh, Mohammad Ghannadi; Taheri, Hossein

2010-05-15

276

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

SciTech Connect

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

Darsell, Jens T.; Weil, K. Scott

2006-08-01

277

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

278

Precipitation processes in an Al2.5Cu1.5Mg (wt. %) alloy microalloyed with Ag and Si  

Microsoft Academic Search

We have produced precipitation on and along both the ? and the {111}? crystal systems by microalloying an Al-2.5Cu-1.5Mg (wt. %) base alloy with Ag and Si. Using electron microscopy and atom probe field ion microscopy, we have demonstrated that Ag+Si additions produce multi-component clustering reactions. When compared to comparable quaternary compositions, the quinary alloy exhibits a higher hardness. The

K Raviprasad; C. R Hutchinson; T Sakurai; S. P Ringer

2003-01-01

279

Investigation of the variation in weak-link profile of YBa 2Cu 3? x Ag x O 7? ? superconductors by Ag doping concentration  

Microsoft Academic Search

The effect of Ag doping concentration on the microstructure, transport properties and weak-link profile of YBa2Cu3?xAgxO7?? bulk superconducting compound was investigated through resistance–temperature (R–T), ac magnetic susceptibility (??T), scanning electron microscope (SEM), X-ray diffraction (XRD) and the critical current density (Jc) versus applied magnetic field (Jc?B) measurements. We used the additive method with cationic ratio of x=0.1?0.4 for the YBCO-Ag

M. Tepe; I Avci; H Kocoglu; D Abukay

2004-01-01

280

119Sn Mössbauer spectroscopy investigation of Nd3Cu4Sn4, Nd3Ag4Sn4, and Ho3Cu4Sn4  

NASA Astrophysics Data System (ADS)

Nd3Cu4Sn4, Nd3Ag4Sn4, and Ho3Cu4Sn4 have been studied using S119n Mössbauer spectroscopy. Contrary to recent neutron diffraction data, Nd3Cu4Sn4 shows a clear magnetic signal at 1.6 K and has an ordering temperature of 2.0(1) K. Nd3Ag4Sn4 orders at 4.8(1) K, in agreement with neutron diffraction measurements. We observe the ordering of the Ho 2d sublattice in Ho3Cu4Sn4 at 8.2(1) K but we also see some residual magnetic splitting up to 10.5(2) K, which was not previously detected by neutron scattering.

Voyer, C. J.; Ryan, D. H.; Cadogan, J. M.

2009-04-01

281

Perpendicular magnetic anisotropy of Ni/Cu(001) films with surface passivation  

NASA Astrophysics Data System (ADS)

A 13 monolayer Ni film was deposited on Cu(001) and followed by oxygen exposure at 300 K. It was confirmed that the surface contained Ni oxide with an amorphous atomic arrangement. The magnetization is perpendicular after surface oxidation. The coercivity is substantially enhanced without shifting of the hysteresis loop after field cooling. This could indicate that the NiO is randomly antiferromagnetic or that the Neél temperature of the NiO is above 300 K. This surface oxide leads to surface passivation so that the film is magnetically alive under ambient conditions, which could have useful applications in the future.

Pan, Wei; Shih, Ying-Ta; Lee, Kuo-Long; Shen, Wen-He; Tsai, Chung-Wei; Wei, Der-Hsin; Chan, Yuet-Loy; Chang, Hui-Ching

2012-04-01

282

Effects of deposition and annealing temperatures on the electrical and optical properties of Ag{sub 2}O and Cu{sub 2}O-Ag{sub 2}O thin films  

SciTech Connect

Ag{sub 2}O and Ag{sub 2}O-Cu{sub 2}O films were deposited on glass substrates by magnetron sputtering of Ag and Cu targets at various substrate temperatures. After deposition, some of these films were annealed using a rapid thermal annealing system, with the variation of temperature. An UV-VIS-NIR photometer and a Hall measurement system were used to characterize the optical and electrical properties of these films. On annealing, Ag{sub 2}O (hexagonal) phase would slowly change to Ag+Ag{sub 2}O (cubic) phases when the annealing temperature is greater than 200 deg. C When the annealing temperature was higher than 450 deg. C, the Ag{sub 2}O phase would transform into a metallic Ag phase completely. Accordingly, the band gap of these films will change, along with the optical and electrical properties. In the study of Ag{sub 2}O-Cu{sub 2}O films, it is found that these two-phase composite films could exist obviously when deposited at room temperature. The photoinduced current of these composite films could be increased significantly, compared with that of a single Cu{sub 2}O phase. This is most likely due to that a large band gap semiconductor (Cu{sub 2}O) is coupled with a small band gap semiconductor (Ag{sub 2}O).

Tseng, C. C.; Hsieh, J. H.; Lin, C. H.; Wu, W. [Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China); Department of Materials Engineering, Mingchi University of Technology, 84 Gungjuan Rd., Taishan, Taipei 24301, Taiwan (China); Department of Materials Science and Engineering, National Chung Hsing University, Taichung 402, Taiwan (China)

2010-07-15

283

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

PubMed

We report the results from a (63)Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4). We find that Ni induces a magnetic broadening of the (63)Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from (63)Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the (63)Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni. PMID:21411886

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

2011-02-23

284

The influence of silver and Ag(In) alloy on Y-Ba-Cu-O equilibria around the YBa2Cu3O7-? superconducting phase  

Microsoft Academic Search

We investigated the effect of silver, Ag(In) alloy and Y2BaCuO5 (the so-called Y-211 green phase) on melt-textured samples of YBa2Cu3O7-? (Y-123) phase in order to check whether better grain growth and alignment were possible. We demonstrate that the addition of silver to Y-123 always led to an enhanced texture. The typical microstructure of the composite Y-123 plus Y-211 (that is

G. A. Costa; E. A. Franceschi; P. Mele

2000-01-01

285

Graphitic carbon nitride solid nanofilms for selective and recyclable sensing of Cu(2+) and Ag(+) in water and serum.  

PubMed

Herein we report the fabrication of g-C3N4 nanofilms and their application as a solid fluorescence sensor. The as-prepared films are capable of convenient, sensitive, selective, rapid and recyclable sensing of Cu(2+) and Ag(+) in water and serum, indicating the sensor's potential application in disease diagnosis. Attractively, our sensor is able to differentiate Cu(2+) and Ag(+) by making use of their different adsorption and desorption kinetics during the interaction with g-C3N4 nanofilms. PMID:25350907

Huang, Heqin; Chen, Rui; Ma, Jiale; Yan, Li; Zhao, Yingqi; Wang, Yu; Zhang, Wenjun; Fan, Jun; Chen, Xianfeng

2014-12-18

286

Corrosion resistance of new copper alloy containing 29Zn, 10Ni and up to 5Mn vis-a-vis Cu10Ni in sulphide polluted synthetic seawater  

Microsoft Academic Search

Cu-10 Ni alloy suffers from accelerated corrosion in sulphide-polluted seawater. New copper alloys containing 29% Zn, 10Ni\\u000a and 3 or 5% Mn have been found to be more corrosion resistant than Cu-10Ni alloys in sulphide polluted synthetic seawater.\\u000a The studies were carried out in synthetic seawater (ASTM D 114–75) and sulphide was added through Na2S (1 gpl ? 41ppm S2?).

A. P. Patil; R. H. Tupkary

2009-01-01

287

Precipitation in -Fe based Fe-Cu-Ni-Mn-alloys: behaviour of Ni and Mn modelled by ab initio and kinetic Monte Carlo simulations  

NASA Astrophysics Data System (ADS)

A kinetic Monte Carlo approach is used to study the behaviour of Ni and Mn solutes in -Fe containing Cu, Ni and Mn foreign atoms. The simulation method is based on a vacancy diffusion model. Regarding precipitation, the crucial parameters of this method are the mixing energies of all contained elements. These are determined using ab initio calculations taking into account temperature by varying the lattice constant. It is found that the behaviour of Ni and Mn solutes which can form NiMn-precipitates, NiMn-shells around Cu precipitates or stay in solution changes significantly with small changes in the mixing energies.

Hocker, Stephen; Binkele, Peter; Schmauder, Siegfried

2014-05-01

288

Ni-B amorphous alloy nanoparticles modified nanoporous Cu toward ethanol oxidation in alkaline medium  

NASA Astrophysics Data System (ADS)

Nanoporous Cu (NPC) prepared by dealloying CuZn alloy is used as an economic substrate for the fabrication of Ni-B alloy (Ni-B/NPC) by ultrasonic-assisted electroless technique. The results of scanning electron microscopy (SEM) and X-ray diffraction (XRD) demonstrate the NPC has a bicontinuous network structure and the Ni-B/NPC alloy is amorphous structure with highly dispersed nanoparticles. Electrochemical performances are measured by cyclic voltammetry (CV), chronoamperometry (CA) and linear sweep voltammetry (LSV). The results suggest that the Ni-B/NPC electrode prepared for 5 min shows the highest electrochemical activity and its redox species coverage and proton diffusion coefficient are remarkably improved compared with the bulk Ni. Ethanol oxidation at the Ni-B/NPC electrode suggests the onset oxidation potential has a negative shift of 52 mV and the oxidation peak current increases by 19.4 times, and apparent activation energy decreases 4.75-30.60 kJ mol-1 at the same potential, in comparison with the bulk Ni. Additionally, the reaction rate constant for ethanol oxidation at the Ni-B/NPC electrode is improved by about one order of magnitude relative to the reported value. Finally, the Ni-B/NPC electrode has a stable redox behavior after complete activation and superior catalytic stability for ethanol oxidation.

Zhang, Shu-Jin; Zheng, Yi-Xiong; Yuan, Lin-Shan; Zhao, Li-Hua

2014-02-01

289

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

290

In situ IR spectroscopic studies of Ni surface segregation induced by CO adsorption on Cu-Ni/SiO2 bimetallic catalysts.  

PubMed

It is of great importance to study the catalytic structures under real reaction conditions especially for the bimetallic catalysts, where facile surface restructure or surface segregation can be driven by adsorbate adsorption. Here, we report CO interaction with Cu-Ni/SiO2 bimetallic model catalysts studied by CO temperature programmed desorption (TPD) and in situ CO polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) under CO pressures varying from ultrahigh vacuum (UHV) to near ambient pressure. Under UHV conditions, Cu is enriched on the surface of Cu-Ni/SiO2 bimetallic catalysts. CO spillover from Cu to Ni on Cu-Ni/SiO2 bimetallic catalysts has been observed at about 200 K under UHV conditions. In situ CO PM-IRRAS shows surface segregation of Ni on the Cu-Ni/SiO2 bimetallic catalysts induced by CO adsorption at ambient pressure CO. The behavior of CO induced surface segregation can lead to severe errors in Ni active site measurements by the selective CO chemisorption on Cu-Ni/SiO2 bimetallic catalysts. PMID:24435048

Yao, Yunxi; Goodman, D Wayne

2014-02-28

291

Theoretical explanation of Ag/Cu and Cu/Ni nanoscale multilayers softening Fengzhang Ren a,  

E-print Network

Keywords: Multilayer structure Hardness Mechanical properties Metals and alloys Thin films Relationship consists of the same thickness multiple monolayers. Each monolayer thickness was controlled and the pressure exerted by Fermi electrons, which supports electron shells expansion at the expense of decreasing

Volinsky, Alex A.

292

X-Ray Photoelectron Spectroscopy of Ag and Cu-Doped Amorphous As2Se3 and GeSe2  

Microsoft Academic Search

Ag- and Cu-doped amorphous As2Se3 and GeSe2 were studied by XPS. The binding energies and\\/or Auger kinetic energies were determined for films of Ag and Cu, and amorphous films of Ge, As, Se, GeSe2, As2Se3, Ag-doped GeSe2, Ag- and Cu-doped As2Se3. The chemical shifts revealed that electrons are transferred from doped metal atoms to As and Se for As2Se3, and

Tokihiro Ueno; Akira Odajima

1982-01-01

293

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

294

Magnetic map of Mn-based thin films on Ni/Cu  

NASA Astrophysics Data System (ADS)

Ab initio density-functional theory in generalized gradient approximation is used to perform calculations on the magnetic structure of Mn thin films and Mn-Ni ordered surface alloys on Ni/Cu. For the Mn monolayer on Ni(001), Ni(011), and Ni(111), we found that the ground state corresponds to an antiferromagnetic coupling between Mn atoms. Ni subsurface atoms adjacent to Mn surface display two different values ( 0.26?B and 0.13?B ) of the magnetic moment in the (111) crystallographic face. For the ordered Mn0.5Ni0.5 monolayer on Ni a ferromagnetic configuration has been obtained. At variance, for the ordered Mn0.5Ni0.5 two-layers thick on Ni an antiferromagnetic coupling between Mn atom nearest-neighboring positions are depicted for the (001) and (011) crystallographic faces whereas it is ferromagnetic for (111) one. Ni magnetic moments at surface alloy are killed (-0.04?B) . Mn overlayer and 1-2 ML surface alloy always present a large rippling, in qualitative agreement with experimental measurements [M. Wuttig and C. C. Knight, Phys. Rev. B 48, 12130 (1993); M. De Santis, V. Abad-Langlais, Y. Gautier, and P. Dolle, Phys. Rev. B 69, 115430 (2004)].

Malonda-Boungou, B. R.; M'Passi-Mabiala, B.; Debernardi, A.; Meza-Aguilar, S.; Demangeat, C.

2010-01-01

295

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

2014-10-01

296

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

297

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

298

Ab Initio Study of Cyclohexane Dehydrogenation with a Transition Metal (Pt, Pd, Ni and Cu) Atom  

NASA Astrophysics Data System (ADS)

To investigate cyclohexane dehydrogenation by a transition metal M (M: Pt, Pd, Ni and Cu) atom, we perform total energy calculations, based on the density functional theory. We consider the process where cyclohexane approaches the M atom. Upon interacting with the M atom, the M atom draws an H atom from the cyclohexane, forming an H-M bond. With a broken C-H bond, the dehydrogenated cyclohexane separates from the M atom. Of the M elements we investigated, a Pt atom exhibited the highest reactivity. In breaking the C-H bond of the cyclohexane, the ? donation dominates for a Pd and Cu atom as compared with the Pt atom, and the ? back-donation dominates for a Ni atom as compared with the Pt atom. The results indicate that the excess charge transfer requires more energy for breaking the C-H bond of the cyclohexane with the Pd, Ni and Cu atom.

Tsuda, Muneyuki; Diño, Wilson Agerico; Nakanishi, Hiroshi; Kasai, Hideaki

2004-05-01

299

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, Mónica J B

2014-03-01

300

Cu-Ni nano-alloy: mixed, core-shell or Janus nano-particle?  

PubMed

Bimetallic nanoparticles like Cu-Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core-shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu-Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu-Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists. PMID:25360574

Guisbiers, Grégory; Khanal, Subarna; Ruiz-Zepeda, Francisco; Roque de la Puente, Jorge; José-Yacaman, Miguel

2014-12-21

301

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

302

Synthesis of triple-layered Ag@Co@Ni core-shell nanoparticles for the catalytic dehydrogenation of ammonia borane.  

PubMed

Triple-layered Ag@Co@Ni core-shell nanoparticles (NPs) containing a silver core, a cobalt inner shell, and a nickel outer shell were formed by an in situ chemical reduction method. The thickness of the double shells varied with different cobalt and nickel contents. Ag0.04 @Co0.48 @Ni0.48 showed the most distinct core-shell structure. Compared with its bimetallic core-shell counterparts, this catalyst showed higher catalytic activity for the hydrolysis of NH3 BH3 (AB). The synergetic interaction between Co and Ni in Ag0.04 @Co0.48 @Ni0.48 NPs may play a critical role in the enhanced catalytic activity. Furthermore, cobalt-nickel double shells surrounding the silver core in the special triple-layered core-shell structure provided increasing amounts of active sites on the surface to facilitate the catalytic reaction. These promising catalysts may lead to applications for AB in the field of fuel cells. PMID:24302541

Qiu, Fangyuan; Liu, Guang; Li, Li; Wang, Ying; Xu, Changchang; An, Cuihua; Chen, Chengcheng; Xu, Yanan; Huang, Yanan; Wang, Yijing; Jiao, Lifang; Yuan, Huatang

2014-01-01

303

Effect of Cu doping on the resistive switching of NiO thin films  

NASA Astrophysics Data System (ADS)

Bipolar resistive switching is observed in the GaIn/Cu:NiO film/ITO device with active layer deposited by sol-gel spin-coating. The first-principles calculations indicate that Cu dopants with valence of +1 are located at the substitutional Ni sites rather than the interstitial ones. Cu doping introduces more oxygen vacancies in the film and increases the carrier mobility, however, excessive Cu dopants may assemble at the grain boundary resulting in larger set voltage. Current-voltage measurements indicate that the trap charge limited and space charge limited conduction dominate the high resistance state, while the low resistance state follows the Ohmic mechanism. The switching is attributed to the formation/rupture of oxygen vacancy filaments.

Li, Jian-Chang; Hou, Xue-Yan; Cao, Qing

2014-04-01

304

Coarsening kinetics of Ni3Sn4 scallops during interfacial reaction between liquid eutectic solders and Cu\\/Ni\\/Pd metallization  

Microsoft Academic Search

The thickening and radial growth kinetics of Ni3Sn4 scallops formed during interfacial reaction between liquid eutectic solders and electroplated Ni\\/Pd metallization scheme on Cu substrate is studied. Selective etching of solder revealed three-dimensional morphology, and the dynamical phenomena, such as faceting, competitive growth, and coalescence of Ni3Sn4 scallops during interfacial reaction. The growth kinetics of the Ni3Sn4 scallops in the

G. Ghosh; Robert R. McCormick

2000-01-01

305

Electrodeposition of CuNiW alloys: thin films, nanostructured multilayers and nanowires  

Microsoft Academic Search

Electrodeposition operating conditions were determined for the deposition of copper–nickel–tungsten alloys and compositionally,\\u000a multilayered deposits. Multilayered alloys with one layer rich in Cu and the other layer rich in NiW were fabricated as both\\u000a thin films and nanowires. The electrolyte contained 0.6 M Na3C6H5O7, 0.2 M Na2WO4, 0.3 M NiSO4 and variable CuSO4 concentration at a pH of 8 adjusted with ammonium hydroxide

M. Gupta; E. J. Podlaha

2010-01-01

306

Diffusion in ZrTiCuNiBe bulk glasses at temperatures around the glass transition  

Microsoft Academic Search

The diffusion coefficients of impurities in two glasses, Zr41Ti14Cu12.5Ni10Be22.5 and Zr46.75Ti8.25Cu7.5Ni10Be27.5 were measured at temperatures around the caloric glass transition temperature. They were determined for annealing times during which there was no decomposition in either of the alloys. For Co, Fe and B the data could not be reasonably fitted by a single Arrhenius relation. A larger effective activation energy

P. Fielitz; M.-P Macht; V Naundorf; G Frohberg

1999-01-01

307

Magnetic behavior of NiCu nanowire arrays: Compositional, geometry and temperature dependence  

NASA Astrophysics Data System (ADS)

Arrays of Ni100-xCux nanowires ranging in composition 0 ? x ? 75, diameter from 35 to 80 nm, and length from 150 nm to 28 ?m have been fabricated by electrochemical co-deposition of Ni and Cu into self-ordered anodic aluminum oxide membranes. As determined by X-ray diffraction and Transmission Electron Microscopy, the crystalline structure shows fcc cubic symmetry with [111] preferred texture and preferential Ni or Cu lattice depending on the composition. Their magnetic properties such as coercivity and squareness have been determined as a function of composition and geometry in a Vibrating Sample Magnetometer in the temperature range from 10 to 290 K for applied magnetic fields parallel and perpendicular to the nanowires axis. Addition of Cu into the NiCu alloy up to 50% enhances both parallel coercivity and squareness. For the higher Cu content, these properties decrease and the magnetization easy axis becomes oriented perpendicular to the wires. In addition, coercivity and squareness increase by decreasing the diameter of nanowires which is ascribed to the increase of shape anisotropy. The temperature dependent measurements reflect a complex behavior of the magnetic anisotropy as a result of energy contributions with different evolution with temperature.

Palmero, E. M.; Bran, C.; del Real, R. P.; Magén, C.; Vázquez, M.

2014-07-01

308

Homochiral Cu(II) and Ni(II) malates with tunable structural features  

NASA Astrophysics Data System (ADS)

Four new homochiral metal-organic frameworks (MOFs) based on S-malate anions and N-donor linkers of different length have been prepared under solvothermal conditions. [Cu(mal)(bpy)]·H2O (1), [Cu(mal)(bpe)]·2H2O (2), [Ni(mal)(bpy)]·1.3CH3OH (3) and [Ni(mal)(bpe)]·4H2O (4) (mal=S-malate, bpy=4,4?-bipyridil, bpe=trans-1,2-bis(4-pyridyl)ethylene) were characterized by a number of analytical methods including powder X-ray diffraction, elemental, thermogravimetric analyses, IR spectroscopy. Compounds 1-3 were structurally characterized by X-ray crystallography. The absence of the chiral ligand racemization under synthetic conditions was unambiguously confirmed by polarimetry experiments. Compounds 1 and 2 contain metal-malate layered motives, connected by N-donor linkers and contribute to the family of isoreticular Cu(II) malates and tartrates [Cu(mal)L] and [Cu(tart)L], (tart=tartrate; L=ditopic rigid organic ligand). The Ni-based compounds 3 and 4 share 1D chiral {Ni(mal)} motives and possess novel type of the chiral framework, previously unknown for chiral carboxylates. The linear N-donor linkers connect these chiral chains, thus controlling the channel diameter and guest accessible volume of the homochiral structure, which exceeds 60 %.

Zavakhina, Marina S.; Samsonenko, Denis G.; Virovets, Alexander V.; Dybtsev, Danil N.; Fedin, Vladimir P.

2014-02-01

309

INFLUÊNCIA DE TRATAMENTOS TERMOMECÂNICOS NAS PROPRIEDADES MECÂNICAS E ELÉTRICAS DE LIGAS Cu-Ni-Pt e Cu-Ni-Sn  

Microsoft Academic Search

RESUMO O cobre e suas ligas têm diferentes aplicações na sociedade moderna devido as excelentes propriedades elétricas, condutividade térmica, resistência à corrosão e outras propriedades. Estas aplicações podem ser em válvulas, tubulações, sistemas para absorção de energia solar, radiadores para automóveis, condutor de corrente, condutor eletrônico, elementos de termostatos. Dentre estas ligas utilizadas podemos destacar Cu-Be, Cu-Sn e Cu-Pt. O

Elias da Silva; W. A. Monteiro; Lineu Prestes

310

Reactive wetting of AgCuTi filler metal on the TiAl-based alloy substrate  

NASA Astrophysics Data System (ADS)

Reactive wetting of the AgCuTi over a TiAl substrate was investigated by hot stage microscopy in real-time in situ, under a high purity argon atmosphere at an elevated temperature (?1270 K level). The results show: wetting process of the AgCuTi alloy on both polished and rough surfaces feature similar kinetics. Three stages were identified, (i) initial stage upon the onset of melting characterized with triple line essentially stationary or contracting, (ii) middle stage featuring almost linear spreading kinetics, and (iii) asymptotic stage with kinetics with diminishing spreading rate. Wetting kinetics within the main spreading stage features the power law of Rn ? t (n = 1). During spreading, Ag-based solid solution and Al-Cu-Ti ternary intermetallics were formed along the interface within the joint zone. Therefore, the spreading of AgCuTi filler over TiAl is highly reactive and the topographical modification of the base metal surface may have a minimal impact on wetting process.

Li, Yulong; Liu, Wen; Sekulic, Dusan P.; He, Peng

2012-10-01

311

The effects of adding elements of zinc and magnesium on ag-cu eutectic alloy for warming acupuncture.  

PubMed

The warming acupuncture for hyperthermia therapy is made of STS304. However, its needle point cannot be reached to a desirable temperature due to heat loss caused by low thermal conductivity, and the quantification of stimulation condition and the effective standard establishment of warming acupuncture are required as a heat source. Accordingly, in this study, after Ag-Cu alloys with different composition ratios were casted and then mixed with additives to improve their physical and mechanical properties, the thermal conductivity and biocompatibility of the alloy specimens were evaluated for selecting suitable material. Ag-Cu binary alloys and ternary alloys added 5?wt% Zn or 2?wt% Mg were casted and then cold drawn to manufacture needles for acupuncture, and their physical properties, thermal conductivity, and biocompatibility were evaluated for their potential use in warming acupuncture. The results of this study showed that the physical and mechanical properties of the Ag-Cu alloys were improved by additives and that the thermal conductivity, machinability, and biocompatibility of the Ag-Cu alloys were improved by Mg addition. PMID:24078827

Kim, Yu Kyoung; Park, Il Song; Kim, Keun Sik; Lee, Min Ho

2013-01-01

312

The Effects of Adding Elements of Zinc and Magnesium on Ag-Cu Eutectic Alloy for Warming Acupuncture  

PubMed Central

The warming acupuncture for hyperthermia therapy is made of STS304. However, its needle point cannot be reached to a desirable temperature due to heat loss caused by low thermal conductivity, and the quantification of stimulation condition and the effective standard establishment of warming acupuncture are required as a heat source. Accordingly, in this study, after Ag-Cu alloys with different composition ratios were casted and then mixed with additives to improve their physical and mechanical properties, the thermal conductivity and biocompatibility of the alloy specimens were evaluated for selecting suitable material. Ag-Cu binary alloys and ternary alloys added 5?wt% Zn or 2?wt% Mg were casted and then cold drawn to manufacture needles for acupuncture, and their physical properties, thermal conductivity, and biocompatibility were evaluated for their potential use in warming acupuncture. The results of this study showed that the physical and mechanical properties of the Ag-Cu alloys were improved by additives and that the thermal conductivity, machinability, and biocompatibility of the Ag-Cu alloys were improved by Mg addition. PMID:24078827

Park, Il Song; Kim, Keun Sik; Lee, Min Ho

2013-01-01

313

EFFECT OF Ag+, Cu2+ AND Zn2+ CONTAINING HYBRID NANOMATRIXES ON THE GREEN ALGAE CHLORELLA KEISSLERI  

Microsoft Academic Search

Summary. In the present work the algicidal effect of hybrid nanocomposites based on silicon precursor tetraethylortosilicate on the microalgae Chlorella keissleri was investigated. The inorganic-organic hybrid materials have been prepared by substituting part of the inorganic precursor with Ca alginate (5, 10, %). The antibacterial elements Ag, Cu or Zn was also included as nitrides (5 wt. %). Hybrid nanomatrix

J. Ivanov; T. Toncheva-Panova; G. Chernev; B. Samuneva

314

Chemical speciation and phytoavailability of Zn, Cu, Ni and Cd in soil amended with fly ash-stabilized sewage sludge  

Microsoft Academic Search

A sequential extraction method was used to determine chemical forms of Cu, Zn, Ni and Cd in fly ash-stabilized sludge. A loamy acid soil amended with fly ash-stabilized sludge was used to grow corn under greenhouse conditions. Sewage sludge amended with coal fly ash can reduce the availability of Cu, Zn, Ni and Cd in the sludge. Increasing fly ash

D. C. Su; J. W. C. Wong

2004-01-01

315

Effect of atomic under-coordination on the properties of Ag and Cu nanoclusters  

NASA Astrophysics Data System (ADS)

Density functional theory calculations have been carried out to investigate the effect of the atomic under-coordination on the bond contraction, lattice strain, and electron configuration of Cuboctahedral and Marks decahedral structures of silver and copper nanoclusters. Our calculated results are consistent in trend with experimental measurements including extended X-ray-absorption fine structure (EXAFS), scanning tunneling microscope/spectroscopy (STM/S), X-ray photoelectron spectroscopy (XPS), and ultraviolet photoelectron spectra (UPS). This agreement approved the prognostications made on the bond-order-length-strength (BOLS) correlation and nonbonding electron polarization (NEP), suggesting that atomic under-coordination at the surface of nanoclusters cause bond contraction, which then leads to lattice strain, charge densification, core electron entrapment, as well as polarization of valence charge. The results of this work will contribute to the understanding of the intriguing properties of Ag and Cu nanoclusters.

Ahmadi, Shideh; Zhang, Xi; Gong, Yinyan; Sun, Chang Q.

2014-09-01

316

Molecular dynamics simulation of polyhedron analysis of Cu-Ag alloy under rapid quenching conditions  

NASA Astrophysics Data System (ADS)

In this study, the formation mechanism of polyhedron clusters in Cu50Ag50 binary alloy system consisting of 50 000 atoms has been investigated by using molecular dynamics simulations based on embedded atom method (EAM) during the rapid cooling processes. The cluster-type index method (CTIM) has been used to describe the evaluation properties of clusters and the structural development has been investigated by using radial distribution function (RDF). The simulation results show that the amorphous phase is formed by the main bonded pairs of 1551, 1541 and 1431 in the system, and ideal icosahedral (icos) cluster (12 0 12 0) and other basic polyhedron clusters, such as defective icos, Frank-Kasper, Bernal polyhedron, play a critical role under the rapid cooling conditions. The results of our simulations that have been disclosed show that high cooling rate favors the icos and defective icos clusters for model alloy system.

Celik, Fatih Ahmet

2014-06-01

317

Microstructure, Melting and Wetting Properties of Pd-Ag-CuO Air Braze on Alumina  

SciTech Connect

A new ceramic brazing technique, referred to as reactive air brazing (RAB), has recently been developed for potential applications in high temperature devices such as gas concentrators, solid oxide fuel cells, gas turbines, and combustion engines. At present, the technique utilizing a silver-copper oxide system is of great interest. The maximum operating temperature of this system, however, is limited by its eutectic temperature of ~935°C, although in practice the operating temperature should be limited to be even lower. An obvious strategy that can be employed to increase the maximum operating temperature of the braze material is to add a higher melting noble alloying element. In this paper, we report the effects of palladium addition on the thermodynamics of the Ag-CuO system and on the wetting properties of the resulting braze with respect to alumina

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

2004-05-01

318

Ternary eutectic growth of Ag-Cu-Sb alloy within ultrasonic field  

NASA Astrophysics Data System (ADS)

The liquid to solid transformation of ternary Ag42.4Cu21.6Sb36 eutectic alloy was accomplished in an ultrasonic field with a frequency of 35 kHz, and the growth mechanism of this ternary eutectic was examined. Theoretical calculations predict that the sound intensity in the liquid phase at the solidification interface increases gradually as the interface moves up from the sample bottom to its top. The growth mode of ( ? + ? + Sb) ternary eutectic exhibits a transition of “divorced eutectic—mixture of anomalous and regular structures—regular eutectic” along the sample axis due to the inhomogeneity of sound field distribution. In the top zone with the highest sound intensity, the cavitation effect promotes the three eutectic phases to nucleate independently, while the acoustic streaming efficiently suppresses the coupled growth of eutectic phases. In the meantime, the ultrasonic field accelerates the solute transportation at the solid-liquid interface, which reduces the solute solubility of eutectic phases.

Zhai, Wei; Hong, Zhenyu; Wei, Bingbo

2007-08-01

319

Crystalline monolayer surface of liquid Au?Cu?Si?Ag?Pd: Metallic glass former  

SciTech Connect

It is demonstrated by means of x-ray synchrotron reflectivity and diffraction that the surface of the liquid phase of the bulk metallic glass forming alloy Au{sub 49}Cu{sub 26.9}Si{sub 16.3}Ag{sub 5.5}Pd{sub 2.3} consists of a two-dimensional crystalline monolayer phase for temperatures of up to about 50 K above the eutectic temperature. The present alloy as well as glass forming Au{sub 82}Si{sub 18} and Au-Si-Ge alloys containing small amounts of Ge are the only metallic liquids to exhibit surface freezing well above the melting temperature. This suggests that the phenomena of surface freezing in metallic liquids and glass forming ability are related and probably governed by similar physical properties.

Mechler, S.; Yahel, E.; Pershan, P.S.; Meron, M.; Lin, B. (Harvard); (UC)

2012-02-06

320

Surface plasmon resonance enhancement of the magneto-optical Kerr effect in Cu/Co/Ag/SnO2 structure  

NASA Astrophysics Data System (ADS)

In this paper, an Ag ultra thin layer was deposited on the Cu/Co film by thermal evaporation technique in the vacuum. The atomic force microscopy confirms that nanoparticles of Ag were formed on the Co magnetic layer, and subsequently, the longitudinal Kerr signal of Cu/Co/Ag was amplified more than 2 times. This enhancement is resulting from the overlap of the surface plasmon resonance in the silver with the electronic transition in the Co layer. Furthermore, we investigated the effect of transparent semiconductor SnO2 as a cap layer on the magnitude of longitudinal Kerr signal. To obtain the optimal thickness of cap layer, a numerical analysis was carried out using a 4 × 4 characteristic matrix, which takes into account multiple reflections from interfaces within the medium and light transmission through the layers.

Ghanaatshoar, Majid; Moradi, Mehrdad; Tohidi, Parsis

2014-10-01

321

Liquid-Phase Separation in the Interdendritic Region After Growth of Primary ?-Sn in Undercooled Sn-2.8Ag-0.3Cu Melt  

NASA Astrophysics Data System (ADS)

An unusual microstructure consisting of both Sn-Ag3Sn and Sn-Cu6Sn5 binary eutectic structures is observed in actual solder balls. In this study, the solidification process of the Sn-Ag3Sn binary eutectic structure after the growth of primary ?-Sn in an undercooled Sn-2.8Ag-0.3Cu alloy was investigated by using thermal analysis and interruption tests to understand the formation of the unusual microstructure. First, fine Ag-enriched liquid zones formed around ?-Sn after the growth of primary ?-Sn. The Ag-enriched zones then gradually enlarged with the accumulation of Ag from the remnant liquid with a decrease in temperature. This indicated that the liquid-phase separation occurred in the remnant liquid after the nucleation of ?-Sn. Eventually, when the temperature of the specimen decreased to approximately the binary eutectic temperature, eutectic Ag3Sn nucleated in the Ag-enriched zones. From interruption tests, we determined the precursor of the Sn-Ag3Sn binary eutectic structure before the beginning of Sn-Ag3Sn binary eutectic solidification. This finding corresponds to the precursor of the Sn-Cu6Sn5 binary eutectic structure observed in the Sn-1.0Ag-0.5Cu alloy.

Takamatsu, Yoshiko; Esaka, Hisao; Shinozuka, Kei

2012-08-01

322

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

323

The Low-Lying States of AlCu and AlAg  

NASA Technical Reports Server (NTRS)

The singlet and triplet states of AlCu and AlAg below about 32 000/cm are studied using the internally contracted multireference configuration-interaction method. A more elaborate study of the X(sup 1)Sum(sup +) ground state of AlCu is undertaken using extended Gaussian basis sets, including the effect of inner-shell correlation and including a perturbational estimate of relativistic effects. Our best estimate of the spectroscopic constants (r(sub 0), DeltaG(sub 1/2), and D(sub 0)) for the X(sup 1)Sum(sup+) state with the experimental values in parentheses are: 4.416(4.420) a(sub 0), 295 (294) /cm, and 2.318 (2.315) eV. The calculations definitively assign the upper state in the observed transition at 14 892/cm to the lowest (sup 1)Prod state. The calculated spectroscopic constants and radiative lifetime for the (sup 1)Prod state are in good agreement with experiment. The calculations support the tentative assignments of Behm et al. for three band systems observed in the visible region between 25 000 and 28 000 / cm. However, the computed spectroscopic constants are in very poor agreement with those deduced from an analysis of the spectra. Analogous theoretical results for AlAg suggest that the (2)(sup 3)Prod, (3)(sup 3)Prod, and (3)(sup 1)Sum(sup +) states account for the bands observed, but not assigned, by Duncan and co-workers.

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

1994-01-01

324

The composition of magmatic NiCu(PGE) sulfide deposits in the Tati and Selebi-Phikwe belts of eastern Botswana  

E-print Network

rocks. The implication is that orogenic belts may have a higher prospectivity for magmatic Ni­Cu ores The area to the east and south of Francistown, eastern Botswana hosts a number of intrusive magmatic Ni­Cu

Patterson, William P.

325

Morphological stability of Ag reflector for high-power GaN-based vertical light-emitting diode by addition of Ni layer  

NASA Astrophysics Data System (ADS)

We investigated the reasons why Ag reflectors in vertical light-emitting diodes showed much better morphological stability with the addition of an intermediate Ni layer by means of X-ray pole figures, scanning electron microscopy (SEM), and SEM electron backscatter diffraction (EBSD) techniques. The SEM results showed that, unlike the pitted Ag-only contacts, the Ni-combined Ag contacts annealed at 300 °C contained only hillocks, even after annealing for 60 min. The EBSD results demonstrated that the Ag-only samples were more strongly <1 1 1>-textured than the Ni-combined Ag samples after annealing for 60 min. The pole-figure results also indicated that, for both the samples, the {1 1 1} texture was enhanced by annealing, although the Ag-only samples were more highly <1 1 1>-textured than the Ni-combined Ag samples. On the basis of the SEM, EBSD, and pole-figure results, we interpret and discuss the possible mechanisms underlying the improved morphological stability of the Ni-combined Ag reflectors.

Choi, Young-Yun; Seong, Tae-Yeon

2014-09-01

326

One-dimensional NiCuZn ferrite nanostructures: Fabrication, structure, and magnetic properties  

SciTech Connect

Ni{sub 0.5-x}Cu{sub x}Zn{sub 0.5}Fe{sub 2}O{sub 4} (0.0{<=}x{<=}0.5) ferrite nanofibers with diameters of 80-160 nm have been prepared by electrospinning and subsequent heat treatment. Both the average grain size and lattice parameter are found to increase with the addition of copper. Fourier transform infrared spectra indicate that the portion of Fe{sup 3+} ions at the tetrahedral sites move to the octahedral sites as some of the substituted Cu{sup 2+} ions get into the tetrahedral sites. Vibrating sample magnetometer measurements show that the coercivity of these ferrite nanofibers decreases with increasing Cu concentration, whereas the specific saturation magnetization initially increases, reaches a maximum value at x=0.2 and then decreases with the Cu content further increase. Notable differences in magnetic properties at room temperature (298 K) and 77 K for the Ni{sub 0.3}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanofibers and corresponding powders are observed and mainly arise from the grain size and morphological variations between these two materials. - Graphical abstract: NiCuZn ferrite nanofibers with diameters of 80-160 nm have been prepared by electrospinning technique and their magnetic behavior is different from that of the corresponding powder sample.

Xiang Jun [School of Mathematics and Physics, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Shen Xiangqian, E-mail: shenxq@ujs.edu.c [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Song Fuzhan; Liu Mingquan [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

2010-06-15

327

Effect of trace organic compounds on the corrosion of Cu/Ni alloys in sulfide polluted seawater  

SciTech Connect

Trace organic complexing agents were investigated to check their ability to reduce the relatively high corrosion rates of Cu/Ni alloys in sulfide polluted seawater. It is found that an organic complexing agent such as fuchsin in the concentration range of 5 ppm is an excellent inhibitor against uniform and localized attack for 70/30 Cu/Ni alloy in 2 ppm sulfide polluted seawater. Another metal complexing agent, SSA (5-sulfosalicylic acid), was found to be effective for the 90/10 Cu/Ni alloy against enhanced attack by sulfide polluted seawater while it was ineffective for 70/30 Cu/Ni alloy. EDTA (ethylene diaminetetraacetic acid disodium salt) was found to be ineffective for both Cu/Ni alloys when used by itself in the concentration range of 5 ppm. A mechanism is proposed to explain the effectiveness of the various selected trace organic complexing agents on the corrosiveness of sulfide polluted seawater.

Reda, M.R.; Al-Hajji, J.N. (Kuwait Univ., Sufat (Kuwait))

1993-05-01

328

The observation and explanation of the spontaneous nucleation behavior in SmBaCuO-Ag solution  

NASA Astrophysics Data System (ADS)

LReBaCuO (LRe=Nd, Sm, Gd) single domains possess a superior superconducting performance and have exhibited potential applications in the fields of superconducting bearings and permanent magnets. Therefore, the requirement of a large size for LReBaCuO single domains with high values of TC and JC is desirable. However, it has been found that some unexpected spontaneous nucleation actions always take place, which interrupt the growing process of the single domains. In this paper, the behavior of spontaneous nucleation in SmBaCuO-Ag solution has been investigated systematically. Experimental results reveal that the spontaneous nucleation that frequently takes place during the growing process could be eliminated greatly by reducing the cooling rate to a proper level. Based on the framework of the constitutional super-cooling theory, combined with the results obtained in experiments, we discuss the possible explanations for the spontaneous nucleation behavior in SmBaCuO-Ag solution. An assumption that the distribution of solute concentration CL, as well as the solid-liquid phase transition temperature TL, in SmBaCuO-Ag solution might be of a time-dependent nature is put forward. A graph of temperature versus time has been worked out based on the assumption, which matches the growth process behavior satisfactorily with the experimental results.

Xu, Ke-xi; Zuo, Peng-xiang; Cao, Yue; Hu, Shun-bo; Lian, Bo-wen; Jiao, Yu-Lei; Xiao, Ling; Zheng, Ming-Hui; Wu, Xing-Da

2012-07-01

329

Effects of milling and Ag doping on the fabrication of LaBa2Cu3O(y) superconductor  

NASA Astrophysics Data System (ADS)

The effects of milling and Ag addition on the decomposition of single-phase LaBa2Cu3O(y) have been evaluated. It was found that the decomposition of milled single-phase LaBa2Cu3O(y) powders when sintered in pure N2 is attributed to the introduction of strain in the lattice which causes the instability of the structure. The possible reasons why single-phase LaBa2 Cu3O(y) could be synthesized by sintering in pure N2 at high temperatures and its transition width is always broadened are proposed. The decomposition of compacts of unmilled powders of single-phase LaBa2Cu3O(y) when sintered in pure N2 for a long time is due to the fact that oxygen diffuses along the grain boundaries and evolves through the surface of the specimens. Silver might segregate to the grain boundaries and prevent decomposition. It is suggested that to obtain a high-quality LaBa2Cu3O(y), sintering in the reduced atmosphere to achieve a proper oxygen content is required. Reduced atmosphere and Ag addition could enhance the densification rate. For Ag-doped specimens, T(sub c) is highest for x = 0.0001, but decreases for x greater than 0.0001.

Fang, Tsang-Tse; Huang, Jao-Wei; Wu, Ma-Shine

1994-06-01

330

Synthesis and characterization of bimetallic Cu–Ni\\/ZrO 2 nanocatalysts: H 2 production by oxidative steam reforming of methanol  

Microsoft Academic Search

Cu\\/ZrO2, Ni\\/ZrO2 and bimetallic Cu–Ni\\/ZrO2 catalysts were prepared by deposition–precipitation method to produce hydrogen by oxidative steam reforming of methanol (OSRM) reaction in the range of 250–360°C. TPR analysis of the Cu–Ni\\/ZrO2 catalyst showed that the presence of Cu facilitates the reduction of the Ni at lower temperatures. In addition, this sample showed two reduction peaks, the former peak was

R. Pérez-Hernández; G. Mondragón Galicia; D. Mendoza Anaya; J. Palacios; C. Angeles-Chavez; J. Arenas-Alatorre

2008-01-01

331

Interpenetrating coordination polymers from Cu(I) or Ag(I) and flexible ligands: 2D polyrotaxanes and interpenetrating grids.  

PubMed

The reaction of [Cu(CH3CN)4]NO3 or AgNO3 with flexible ligands 1,4-bis(4-pyridylmethyl)-2,3,5,6-tetrafluorobenzene (bpf) or 4,4'-bis(4-pyridylmethyl)-2,2',3,3',5,5',6,6'-octafluorobiphenyl (bpfb) afforded two types of interpenetrating coordination polymers. The structures of [Cu2(bpf)3(NO3)2]n and [Ag2(bpf)3-(NO3)2]n are 2D polyrotaxane networks in which 1D polymeric chains are aligned in a grid. The structure of {[Cu(bpfb)2]NO3}n is a 2D grid polymer with two-fold parallel interpenetration. PMID:17441069

Kasai, Kayoko; Sato, Mariko

2006-09-18

332

Research on manufacturing Cu matrix Fe-Cu-Ni-C alloy composite parts by indirect selective laser sintering  

Microsoft Academic Search

The property of alloy parts can be adjusted conveniently if alloy element powders are used for manufacturing alloy parts by\\u000a indirect selective laser sintering (SLS), but there have been no reports in this field. Fe, Cu, Ni, C composite powders of\\u000a two compositions were obtained through a 3D blending way in this paper. Green parts of above composite powder were

J. H. Liu; Y. S. Shi; K. H. Chen; S. H. Huang

2007-01-01

333

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

334

Neutron scattering study of Ag, Mg and Al substitution effects on the magnetic excitations in CuCrO2  

NASA Astrophysics Data System (ADS)

CuCrO2 is a quasi two-dimensional triangular-lattice antiferromagnet with S = 3/2. Recently, it was found that small amount of element substitution strongly affects magnetic and transport properties. In the present study, we studied magnetic excitations in powder samples of CuCrO2,Cu0.85Ag0.15CrO2,CuCr0.97Mg0.03CrO2 and CuCr0.85Al0.15O2 by inelastic neutron scattering using the chopper spectrometer AMATERAS at J-PARC. We observed a variety of the magnetic excitations induced by different types of the element substitutions, and they should be keys to understand the magnetic and transport properties.

Kajimoto, R.; Nakajima, K.; Ohira-Kawamura, S.; Inamura, Y.; Kakurai, K.; Arai, M.; Hokazono, T.; Oozono, S.; Okuda, T.

2012-12-01

335

Optical and photoelectrochemical performance study based on n-ZnO nanorod arrays/p-CuAlO2 laminar films/Ni heterojunction  

NASA Astrophysics Data System (ADS)

A novel ZnO nanorod arrays (NRs)/CuAlO2 laminar films heterojunction nanostructure was grown on the substrate of Ni plates using sol-gel synthesis for laminar films and subsequent hydrothermal reaction for nanorod arrays. The surface morphology, structure, optical and photoelectrochemical behaviors of this heterojunction were considered. Two significant absorption peaks of UV-vis spectra and a favorable forward current to reverse current ratio at applied voltage of -0.7 V to +2 V were observed in this heterojunction. Furthermore, the photoelectrochemical property was indicated that the highest photocurrent of 0.67 mA/cm2 was obtained under AM 1.5 illumination (vs Ag/AgCl). This heterojunction will play an important role in the optoelectronic fields and can be extended to other binary or ternary oxide compositions for optoelectronic applications.

Ding, Juan; Yang, Haibin; Deng, Weiwen

2014-06-01

336

Substrate Dissolution and Shear Properties of the Joints between Bi-Ag Alloys and Cu Substrates for High-Temperature Soldering Applications  

NASA Astrophysics Data System (ADS)

The present study investigated interfacial reactions between Cu substrates and Bi-Ag alloys during soldering. Without forming intermetallic compounds (IMCs), the molten solder grooved and further penetrated along the grain boundaries (GBs) of the Cu substrate. An increase in Ag content enhanced GB grooving, raised the dissolution rate and also the amount of dissolved Cu in molten Bi. A stoichiometric Cu-Bi phase formed isothermally in liquid solders and considerably affected the Cu dissolution kinetics. The results also show that Bi-Ag/Cu joints possessed a better shear strength than the Pb-Sn/Cu, which implies that mechanical bonding by grain-boundary grooves was strong enough to withstand shear deformation.

Song, Jenn-Ming; Chuang, Hsin-Yi; Wu, Zong-Mou

2007-11-01

337

The 3&&(3F)3&,a'8' manifold of excited electronic states of NiCu Eileen M. Spain and Michael D. Morse  

E-print Network

The 3&&(3F)3&,a'8' manifold of excited electronic states of NiCu Eileen M. Spain and Michael D; accepted 18 June 1992) Diatomic NiCu has been supersonically cooled in a molecular beam and investigated in this paper allows the electronic structure of NiCu to be understood in depth and provides a database

Morse, Michael D.

338

Selective determination of the C 11 elastic constant in unsupported Ag/Ni superlattices by brillouin scattering  

NASA Astrophysics Data System (ADS)

The first selective determination of the effective elastic constant c 11 in thick, unsupported metallic superlattice samples has been achieved using Brillouin light scattering. This enabled Young's modulus to be estimated. Measurements of the macroscopic Young's modulus were also performed on identical samples using a tensil micromachine. The two approaches, surface phonons and static elasticity, give results mutually consistent in the Ag/Ni superlattices studied. In addition, no significant dependence on period was found in either case.

Carlotti, G.; Fioretto, D.; Giovannini, L.; Socino, G.; Pelosin, V.; Rodmacq, B.

1992-02-01

339

Synthesis and processing of nanocrystalline Ag-Fe-Ni for low thermal expansion-high conductivity thermal management applications  

Microsoft Academic Search

Nanocrystalline Ag–Fe–Ni powders were produced by a reduction of the aqueous metal ion solutions with sodium borohydride and then converted to fine-grained silver–Invar alloys that offer attractive thermal, electrical, and mechanical properties. The samples were characterized by x-ray diffraction, scanning electron microscopy, wavelength dispersive x-ray spectrometry, thermomechanical analysis, microhardness measurements, and electrical conductivity measurements; thermal conductivity was estimated using the

Jonathan Stolk; M. Gross; D. Stolk; A. Manthiram

2001-01-01

340

Study of the dissipative binary channels in the 107Ag+58Ni reaction at 52 MeV/nucleon  

E-print Network

The binary dissipative channels are characterized by the presence of two main fragments in the exit channel. They have been studied in the 107Ag+58Ni reaction at 52 MeV/nucleon of bombarding energy. For that purpose a modified version of the INDRA multidetector has been used in conjunction with a part of the CHIMERA multidetector. Preliminary results on the excitation energy and intrinsic angular momentum of the quasi-projectile are reported and compared to a dynamical calculation.

INDRA; CHIMERA Collaborations; :; J. C. Steckmeyer; S. Aiello; A. Anzalone

2005-04-22

341

Chirality Switching and Winding or Unwinding of the Antiferromagnetic NiO Domain Walls in Fe /NiO/Fe/CoO/Ag(001)  

NASA Astrophysics Data System (ADS)

Fe /NiO/Fe/CoO/Ag(001) single crystalline films were grown epitaxially and investigated by x-ray magnetic circular dichroism and x-ray magnetic linear dichroism. The bottom Fe layer magnetization is pinned through exchange coupling to the CoO layer and the top Fe layer magnetization can be rotated by an in-plane external magnetic field. We find that the NiO spins wind up to form a domain wall due to the perpendicular NiO /Fe interfacial coupling as the top layer Fe magnetization rotates from 0° to 90°, but switch wall chirality and unwind the wall as the Fe magnetization rotates from 90° to 180°. This observation shows that Mauri's 180° domain wall does not exist in perpendicularly coupled ferromagnetic-antiferromagnetic systems in the strong coupling regime.

Li, J.; Tan, A.; Ma, S.; Yang, R. F.; Arenholz, E.; Hwang, C.; Qiu, Z. Q.

2014-10-01

342

Chirality Switching and Winding or Unwinding of the Antiferromagnetic NiO Domain Walls in Fe/NiO/Fe/CoO/Ag(001).  

PubMed

Fe/NiO/Fe/CoO/Ag(001) single crystalline films were grown epitaxially and investigated by x-ray magnetic circular dichroism and x-ray magnetic linear dichroism. The bottom Fe layer magnetization is pinned through exchange coupling to the CoO layer and the top Fe layer magnetization can be rotated by an in-plane external magnetic field. We find that the NiO spins wind up to form a domain wall due to the perpendicular NiO/Fe interfacial coupling as the top layer Fe magnetization rotates from 0° to 90°, but switch wall chirality and unwind the wall as the Fe magnetization rotates from 90° to 180°. This observation shows that Mauri's 180° domain wall does not exist in perpendicularly coupled ferromagnetic-antiferromagnetic systems in the strong coupling regime. PMID:25325659

Li, J; Tan, A; Ma, S; Yang, R F; Arenholz, E; Hwang, C; Qiu, Z Q

2014-10-01

343

Magnetic Moment of ^57Cu and shell breaking of the ^56Ni core  

Microsoft Academic Search

The nuclear magnetic moment of the ground state of ^57Cu was deduced for the first time. Together with a known magnetic moment of the mirror partner, ^57Ni, the spin expectation value, which is a contribution of nucleon spins to the magnetic moment, was extracted from the isoscaler part of magnetic moments. In the sd shell, a systematic trend of the

Kei Minamisono

2006-01-01

344

High temperature oxidation of a Cu-Ni based cermet, Kinetic and microstructural study  

E-print Network

1 High temperature oxidation of a Cu-Ni ­ based cermet, Kinetic and microstructural study Fabien atmosphere, which contains oxygen and fluorides. This study was devoted to the kinetics of oxidation in air of a cermet composed with nickel ferrite (NixFe3-xO4), nickel oxide (NiyFe1-yO) and nickel-copper alloy (Cuz

Paris-Sud XI, Université de

345

Proton-microprobe analyses of palladium and selenium in Ni-Cu-sulfides  

Microsoft Academic Search

Samples from the Ni-Cu-sulfide mineralization of the Acoje Ophiolite block (ancient oceanic crust), Zambales, Philippines were analyzed for Pd and Se using the Heidelberg proton microprobe. The background in the PIXE spectra around the Pd peaks was nearly zero, so that even small peaks were clearly revealed. Unexpected problems in the fitting of these peaks with the SESAMX program could

Beate Orberger; Kurt Traxel

1991-01-01

346

Dynamic observation of dislocation-free deformation process in Al, Cu, and Ni thin foils  

Microsoft Academic Search

Dislocation-free plastic deformation, which occurs under extraordinarily high internal stress comparable to ideal strength of metals, was discovered in thin foil portion produced by ductile fracture of fcc Au by dynamic observation of the deformation process [1–5]. In the present study, the deformation process of thin foil portion in other fcc metals (Al, Cu, Ni) was examined in the same

Y. Matsukawa; K. Yasunaga; M. Komatsu; M. Kiritani

2003-01-01

347

ELECTROCHEMICAL PERFORMANCE OF Ni\\/Cu-METALLIZED & CARBON-COATED GRAPHITES FOR LITHIUM BATTERIES  

Microsoft Academic Search

Synthetic and natural graphites were metallized with Cu or Ni using a fluidized bed coating and annealing process. With this method, crystalline nanometer-sized metal islands (~ 50 nm diameter) were deposited onto the surface of graphite. Post-metallization, the graphite materials were cycled in lithium coin cells to determine their electrochemical properties in a propylene carbonate (PC) solvent based electrolyte. Better

Christopher S. Johnson; Kevin Lauzze; Nick Kanakaris; Arthur Kahaian; Michael Thackeray; Khalil Amine; Giselle Sandí-Tapia; Stephen Hackney; Robert Rigney

348

Effect of heavy metals (Cu, Pb, and Ni) on the compositions of EPS in biofilms  

Microsoft Academic Search

A series of batch adsorption tests to estimate the biofilm capacity for removal of the heavy metals (Cu, Pb, and Ni) in wastewater were carried out. The metal sorption results were fitted to the Freundlich isotherm model to compare their sorption capacity. The change of the composition of EPSs (extracellular polymeric substances) was simultaneously represented by the ratio of carbohydrate

A. Jang; S. M. Kim; S. Y. Kim; S. G. Lee; I. S. Kim

2001-01-01

349

In-situ observation of the energy dependence of defect production in Cu and Ni  

SciTech Connect

The damage function, the average number of Frenkel pairs created as a function of lattice atom recoil energy, was investigated in Cu and Ni using in-situ electrical-resistivity damage-rate measurements in the high-voltage electron micrscope (HVEM) at T < 10K. Electron and proton irradiations were performed in-situ on the same polycrystalline specimens using the Argonne National Laboratory HVEM-Ion Beam Interface. Both Ni and Cu exhibit a sharp rise in the damage function above the minimum threshold energy (approx. 18 eV for Cu and approx. 20 eV for Ni) as displacements in the low-threshold energy regions of the threshold energy surface become possible. A plateau is observed for both materials (0.54 Frenkel pairs for Cu and 0.46 Frenkel pairs for Ni) indicating that no further directions become productive until much higher recoil energies. These damage functions show strong deviations from simple theoretical models, such as the Modified Kinchin-Pease damage function. The results are discussed in terms of the mechanisms of defect production that govern the single-displacement regime of the damage function and are compared with results from recent molecular-dynamics simulations.

King, W.E.; Merkel, K.L.; Baily, A.C.; Haga, K.; Meshii, M.

1983-01-01

350

The response of macrophages to a Cu-Al-Ni shape memory alloy.  

PubMed

Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but little is known about their biocompatibility. The aim of this work was to study the response of rat peritoneal macrophages (PMØ) to a Cu-Al-Ni SMA in vitro, by measuring the functional activity of mitochondria, necrosis, apoptosis, and production of proinflammatory cytokines. Rapidly solidified (RS) thin ribbons were used for the tests. The control alloy was a permanent mold casting of the same composition, but without the shape memory effect. Our results showed that the control alloy was severely cytotoxic, whereas RS ribbons induced neither necrosis nor apoptosis of PMØ. These findings correlated with the data that RS ribbons are significantly more resistant to corrosion compared to the control alloy, as judged by the lesser release of Cu and Ni in the conditioning medium. However, the ribbons generated intracellular reactive oxygen species and upregulated the production of IL-6 by PMØ. These effects were almost completely abolished by conditioning the RS ribbons for 5 weeks. In conclusion, RS significantly improves the corrosion stability and biocompatibility of Cu-Al-Ni SMA. The biocompatibility of this functional material could be additionally enhanced by conditioning the ribbons in cell culture medium. PMID:20008088

Coli?, Miodrag; Tomi?, Sergej; Rudolf, Rebeka; Anzel, Ivan; Lojen, Gorazd

2010-09-01

351

Production of Cu-Al-Ni Shape Memory Alloys by Mechanical Alloy  

SciTech Connect

The mechanical alloying technique has been used to produce shape memory Cu83Al13Ni4 alloy. The structure and thermal properties were examined by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The morphology of the surface suggests the presence of martensite.

Goegebakan, Musa; Soguksu, Ali Kemal; Uzun, Orhan; Dogan, Ali [Department of Physics, Faculty of Art and Science, Kahramanmaras Sutcu Imam University, Kahramanmaras, 46000 (Turkey); Department of Physics, Faculty of Art and Science, GaziOsmanpasa University, Tokat (Turkey)

2007-04-23

352

Evaluation of high strength, high conductivity CuNiBe alloys for fusion energy applications  

NASA Astrophysics Data System (ADS)

The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HP™ CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 °C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 °C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 °C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ?0.7 displacements per atom (dpa) at temperatures between 100 and 240 °C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation after irradiation increased with increasing irradiation temperature, with a uniform elongation of ?3.3% observed at 240 °C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 °C, and may be an attractive candidate for certain low-temperature fusion energy structural applications. Conversely, CuNiBe may not be preferred at intermediate temperatures of 250-500 °C due to the poor ductility and fracture toughness of CuNiBe alloys at temperatures ?250 °C. The potential deformation mechanisms responsible for the transition from transgranular to intergranular fracture are discussed. The possible implications for other precipitation-hardened alloys such as nickel based superalloys are briefly discussed.

Zinkle, S. J.

2014-06-01

353

Evaluation of high strength, high conductivity CuNiBe alloys for fusion energy applications  

SciTech Connect

The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HPTM CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ~0.7 displacements per atom (dpa) at temperatures between 100 and 240 C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation increased with increasing irradiation temperature, with a uniform elongation of ~3.3% observed at 240 C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 C, and may be an attractive candidate for certain fusion energy structural applications. Conversely, CuNiBe may not be preferred at intermediate temperatures of 250-500 C due to the poor ductility and fracture toughness of CuNiBe alloys at temperatures >250 C. The potential deformation mechanisms responsible for the transition from transgranular to intergranular fracture are discussed. The possible implications for other precipitation hardened alloys such as nickel based superalloys are briefly discussed.

Zinkle, Steven J [ORNL] [ORNL

2014-01-01

354

Nanocrystallization of Zr-Cu-Ni-Al-Au glassy alloys during severe plastic deformation  

NASA Astrophysics Data System (ADS)

A study has been carried out into the formation of nanocrystalline grains during high-pressure torsion (HPT) deformation of Zr65Cu17Ni5Al10Au3 bulk alloys prepared using tilt casting. As a preliminary to this, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses were carried out on as-cast Zr65+xCu17-xNi5Al10Au3 (x=0~5 at.%) and Zr65Cu20Ni5Al10Au3 alloys, in order to determine the effect on the microstructure of the excess Zr content x and the presence of Au. From the XRD patterns, it was determined that all of the alloys had a metallic glassy nature. For Zr65Cu17Ni5Al10Au3, the DSC results indicated the presence of a wide supercooled liquid region between the glass transition temperature (Tg) of 644 K and the crystallization temperature of 763 K, where the stable body-centered tetragonal Zr2Cu phase was formed. In contrast, for the Zr65+xCu17-xNi5Al10Au3 alloys, precipitation of an icosahedral quasicrystalline phase (I-phase) was observed in the supercooled liquid region at about 715 K. HPT deformation of the Zr65Cu17Ni5Al10Au3 alloys was carried out under a high pressure of 5 GPa. Both as-cast specimens and those annealed at Tg-50 K for 90 min were used. Following a single HPT rotation (N=1), transmission electron microscopy identified the presence of face- centered cubic Zr2Ni precipitates in the as-cast alloy, with a size of about 50 nm. For the annealed alloy, a high density of I-phase precipitates with sizes of less than 10 nm was observed following HPT with N=10, indicating that the combination of severe plastic deformation and annealing is effective at producing extremely small grains.

Yamada, Masahiro; Kamisato, Ryo; Yamasaki, Tohru; Adachi, Hiroki; Tsuchiya, Koichi; Yokoyama, Yoshihiko

2014-08-01

355

Phase Transformation Behavior of Hot Isostatically Pressed NiTi-X (X = Ag, Nb, W) Alloys for Functional Engineering Applications  

NASA Astrophysics Data System (ADS)

Owing to their unique properties, NiTi-based shape memory alloys (SMAs) are highly attractive candidates for a lot of functional engineering applications like biomedical implants (stents), actuators, or coupling elements. Adding a third element is an effective measure to adjust or stabilize the phase transformation behavior to a certain extent. In this context, addition of alloying elements, which are low soluble or almost insoluble in the NiTi matrix is a promising approach and—with the exception of adding Nb—has rarely been reported in the literature so far, especially if the manufacturing of the net-shaped parts of these alloys is aspired. In the case of addition of elemental Nb, broadening of hysteresis between austenitic and martensitic phase transformation temperatures after plastic deformation of the Nb phase is a well-known effect, which is the key of function of coupling elements already established on the market. In the present study, we replaced Nb with additions of elemental Ag and W, both of which are almost insoluble in the NiTi matrix. Compared with Nb, Ag is characterized by higher ductility in combination with lower melting point, enabling liquid phase sintering already at moderate temperatures. Vice versa, addition of W might act in opposite manner considering its inherent brittleness combined with high melting temperature. In the present study, hot isostatic pressing was used for manufacturing such alloys starting from prealloyed NiTi powder and with the additions of Nb, Ag, and W as elemental powders. Microstructures, interdiffusion phenomena, phase transformation behaviors, and impurity contents were investigated aiming to better understand the influence of insoluble phases on bulk properties of NiTi SMAs.

Bitzer, M.; Bram, M.; Buchkremer, H. P.; Stöver, D.

2012-12-01

356

Evolution of {Omega} phase in an Al-Cu-Mg-Ag alloy -- A three-dimensional atom probe study  

SciTech Connect

Evolution of plate-like precipitates of the {Omega} phase in an Al-1.9Cu-0.3Mg-0.2Ag (at.%) alloy has been investigated by three-dimensional atom probe (3DAP) and transmission electron microscope (TEM) techniques. In an as-quenched alloy, all solute atoms are uniformly dissolved. After 5 s aging at 180 C, co-clusters of Ag and Mg atoms are present. Initially, these co-clusters do not have well-defined shape, but after aging for 120 s, they are aligned on the {l_brace}111{r_brace} planes incorporating Cu atoms. Initially, they do not have the distinct structure consistent with the {Omega} phase, thus these are designated as {l_brace}111{r_brace}GP zones. The {Omega} platelet which appears after the {l_brace}111{r_brace}GP zones contain all solute elements within the precipitate having a composition of approximately 25 at.% Cu, 20 at.% Mg and 10 at.% Ag. In the well-defined {Omega} phase which appears after 2 and 10 h aging at 180 C, Ag and Mg atoms are strongly segregated to the broad face monolayer interfaces of {alpha}/{Omega}. No Mg and Ag are incorporated within the platelet, and its chemical composition is Al-33 at.% Cu. Based on these observations, it is concluded that the {Omega} phase evolves from co-clusters to plate-like precipitates continuously, rather than precipitating discretely by heterogeneous nucleation to their precursors. In a well-grown {Omega} plate, elemental mapping near a ledge was observed by 3DAP for the first time.

Reich, L.; Murayama, M.; Hono, K. [National Research Inst. for Metals, Sengen, Tsukuba (Japan)] [National Research Inst. for Metals, Sengen, Tsukuba (Japan)

1998-11-02

357

Chemistry of Cu(acac){sub 2} on Ni(110) and Cu(110) surfaces: Implications for atomic layer deposition processes  

SciTech Connect

The thermal chemistry of copper(II)acetylacetonate, Cu(acac){sub 2}, on Ni(110) and Cu(110) single-crystal surfaces was probed under vacuum by using x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Some data for acetylacetone (Hacac, CH{sub 3}COCH{sub 2}COCH{sub 3}) adsorbed on Ni(110) are also reported as reference. Chemical transformations were identified in several steps covering a temperature range from 150 K to at least 630 K. The desorption of Hacac and a 3-oxobutanal (CH{sub 3}COCH{sub 2}CHO) byproduct was observed first at 150 and 180 K on Ni(110) and at 160 and 185 K on Cu(110), respectively. Partial loss of the acetylacetonate (acac) ligands and a likely change in adsorption geometry are seen next, with the possible production of HCu(acac), which desorbs at 200 and 235 K from the nickel and copper surfaces, respectively. Molecular Cu(acac){sub 2} desorption is observed on both surfaces at approximately 300 K, probably from recombination of Cu(acac) and acac surface species. The remaining copper atoms on the surface lose their remaining acac ligands to the substrate and become reduced directly to metallic copper. At the same time, the organic ligands follow a series of subsequent surface reactions, probably involving several C-C bond-scissions, to produce other fragments, additional Hacac and HCu(acac) in the gas phase in the case of the copper surface, and acetone on nickel. A significant amount of acac must nevertheless survive on the surface to high temperatures, because Hacac peaks are seen in the TPD at about 515 and 590 K and the C 1s XPS split associated with acac is seen up to close to 500 K. In terms of atomic layer deposition processes, this suggests that cycles could be design to run at such temperatures as long as an effective hydrogenation agent is used as the second reactant to remove the surface acac as Hacac. Only a small fraction of carbon is left behind on Ni after heating to 800 K, whereas more carbon and additional oxygen remains on the surface in the case of Cu.

Ma Qiang; Zaera, Francisco [Department of Chemistry, University of California, Riverside, California 92521 (United States)

2013-01-15

358

The mechanism of N-Ag bonding determined tunability of surface-enhanced Raman scattering of pyridine on MAg (M = Cu, Ag, Au) diatomic clusters.  

PubMed

Binary coinage metal clusters can show a significantly different enhancement in surface-enhanced Raman scattering (SERS) from that of pure element clusters, owing to their tunable surface plasmon resonance energies affected by the composition and atomic ordering. Yet, the tunability by composition requires a deep understanding in order to further optimize the SERS-based detection technique. Here, to fill this deficiency, we conducted detailed analyses of the SERS of pyridine adsorbed through N-Ag bonding on the homonuclear diatomic metal cluster Ag2 and heteronuclear diatomic metal clusters of AuAg and CuAg, as well as the involved charge transfer under an intracluster excitation, based on calculations using time-dependent density functional theory with a short-time approximation for the Raman cross-section. We find that although the SERS enhancements for all complexes can reach the order of 10(3)-10(4), the corresponding wavelengths used for SERS excitation are significantly different. Our molecular orbital analysis reveals that the complexes based on heteronuclear metal clusters can produce varied electronic transitions owing to the polarization between different metal atoms, which tune the SERS enhancements with altered optical properties. Our analyses are expected to provide a theoretical basis for exploring the multi-composition SERS substrates applicable for single molecular detection, nanostructure characterization, and biological molecular identification. PMID:25157565

Chen, Lei; Gao, Yang; Xu, Haoran; Wang, Zhigang; Li, Zhengqiang; Zhang, Rui-Qin

2014-10-14

359

Preparation and electrical properties of Ni-Cu-Zn system doped with the magnesium oxide  

NASA Astrophysics Data System (ADS)

A sery of ferrite samples, Ni0.1Cu0.2MgxZn0.7-xFe2O4, (x = 0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) have been prepared by the standard ceramic techniques, sintered at 1200°C for 2 h, and their crystalline structures were investigated by using X-ray diffraction, which confirmed the formation of Ni0.1Cu0.2MgxZn0.7-xFe2O4 phase. The presence of Mg content increases the crystallinity of the given ferrite which is considered as catalyst for the accomplishment of the solid state reaction. The lattice parameter and crystallite size were calculated from XRD. The cationic distribution was estimated from the theoretical values of lattice parameters. The IR spectra analysis has been studied. The dielectric constant for the ferrite system Ni-Cu-Zn gradually increases with temperature up to nearly Curie temperature and then increase sharply beyond the Tc. The Curie temperature obtained from the ´ ?repsilon versus T is in agreement with the Curie temperature obtained from other measurements. Dielectric loss tangent (tan ?) has the same behavior as dielectric constant (´ ?repsilon). A minimum value of dielectric loss tangent (tan ?) for the system "Ni-Cu-Zn" was observed at x = 0.45. Magnetic permeability has been studied. The dependence of initial permeability on temperature exhibit a peak which is called Hopkinson peak (HP) in the vicinity of Curie temperature and confirmed the phase purity of ferrite sample. The increasing of porosity and decreasing of grain size play an important role in decreasing ?i. It is clear that the value of Tc is found to increase by increasing the concentration of diamagnetic substitution Mg for "Ni-Cu-Zn" system.

Hemeda, O. M.; Tawfik, A.; Hemeda, D. M.; Elsheekh, A. M.

2014-06-01

360

Synthesis and magnetic properties of ALnO 2 ( A=Cu or Ag; Ln=rare earths) with the delafossite structure  

Microsoft Academic Search

Synthesis, structures, and magnetic properties of ternary rare earth oxides ALnO2 (A=Cu or Ag; Ln=rare earths) have been investigated. CuLnO2 (Ln=La, Pr, Nd, Sm, Eu) were synthesized by the direct solid state reaction of Cu2O and Ln2O3, and AgLnO2 (Ln=Tm, Yb, Lu) were obtained by the cation-exchange reaction of NaLnO2 and AgNO3 in a KNO3 flux. These compounds crystallized in

Naoyuki Miyasaka; Yoshihiro Doi; Yukio Hinatsu

2009-01-01

361

Complexes with hybrid phosphorus-NHC ligands: pincer-type Ir hydrides, dinuclear Ag and Ir and tetranuclear Cu and Ag complexes.  

PubMed

Three types of hybrid phosphorus-imidazolium salts, 1-methyl-3-(3-((diphenylphosphino)methyl)benzyl)-1H-imidazol-3-ium hexafluorophosphate (2·PF6), 1-methyl-3-(3-(di-tert-butylphosphinooxy)phenyl)imidazolium iodide (8a), and 3-(3-((diphenylphosphoryl)methyl)phenyl)-1-methyl-1H-imidazol-3-ium iodide (11) have been prepared and used as precursors to phosphine-NHC, phosphinite-NHC, and phosphoryl-NHC metal complexes, respectively. The structure of 11 has been determined by X-ray diffraction. The Ag(I) and Ir(I) complexes of the phosphine-NHC ligand, [Ag(?-P-NHC,?C,?P)]2(PF6)2 (3) and [Ir(cod)(?-P-NHC,?C,?P)]2(PF6)2 (4), were obtained and characterized by NMR, ESI-MS, elemental analysis, and X-ray diffraction. Both complexes are dinuclear and dicationic, with two P-NHC ligands bridging the two metal centers. The presence of the P donor led for 3 to an unprecedented structure compared to that of related Ag(I) complexes with trans spanning bis-NHC ligands. Complex 4 is the first example of a dinuclear iridium complex with a hybrid P-NHC ligand. The new hydrido, Ir(III) pincer-type complex [IrH(CNHCCCNHC)(MeCN)]PF6 (7) is suggested to have a square-pyramidal structure. The tetranuclear Ag(I) complex with the phosphinite-NHC ligand, [Ag2(?3-I)(?-PO-NHC,?P,?CNHC)]2 (9a) has a cubane-type structure, with alternating silver and iodine apexes and two PO-NHC ligands bridging opposite edges of the Ag4 tetrahedron. The Ir(III) pincer complexes [IrH(I)(PO-NHC,?P,?C,?CNHC)(Me)] (10a) and [IrH(I)(PO-NHC,?P,?C,?CNHC)(n-Bu)] (10b), with Me or n-Bu substituents on the nitrogen atom, respectively, have been prepared and characterized. Ag(I) and Cu(I) complexes with the phosphoryl-NHC ligand are reported and the centrosymmetric structure of the latter, [Cu(OP-NHC,?CNHC)2(?-I){Cu(?-I)}]2 (13), was established by X-ray diffraction and consists of a central Cu2(?-I)2 rhombus connected by single iodide bridges to two Cu(OP-NHC,?CNHC)2 moieties. The Ir(III) hydride pincer complexes 10a,b were tested as catalyst precursors for the C-H bond activation of alkanes. Although their efficiency was significantly lower for transfer dehydrogenation from cyclooctane (coa) to t-butylethylene (tbe) than that of known PCP-Ir systems, these results represent the first attempts to study the catalytic properties of hybrid P-NHC iridium pincer complexes. PMID:23750783

Liu, Xianghao; Braunstein, Pierre

2013-07-01

362

Preparation of a Ag-doped Bi-Sr-Ca-Cu-O bulk sample by the floating-zone method  

Microsoft Academic Search

Bulk samples with nominal composition of Bi2Sr2CaCu2O(y) doped with 0, 10 and 20 wt pct Ag were prepared by the floating-zone method at growth rates of 2 mm\\/h and 5 mm\\/h. Ag-doping seems to slightly enhance J(c) while annealing is very effective for J(c) enhancement. From preliminary ac susceptibility measurements, the J(c) enhancement by annealing is considered to be due

Yukio Kubo; Kazuo Michishita; Noriyuki Shimizu; Yutaka Higashida; Hisanori Yokoyama; Yumi Hayami; Eikichi Inukai; Akira Saji; Noboru Kuroda; Hiroshi Yoshida

1989-01-01

363

Syntheses, structures, and optical properties of Ba{sub 4}MInSe{sub 6} (M=Cu, Ag)  

SciTech Connect

Two new quaternary chalcogenides, namely Ba{sub 4}MInSe{sub 6} (M=Cu, Ag), were synthesized by solid state reactions. These two isostructural compounds adopt the Ba{sub 2}MnS{sub 3} structure type in the orthorhombic space group Pnma. In the structure, the M and In atoms randomly occupy one crystallographic unique metal position with the molar ratio of 1:1 The (M/In)Se{sub 4} tetrahedra are connected to each other by corner-sharing to form one-dimensional chains along the b direction, which are separated by mono-capped trigonal prismatically coordinated Ba atoms. Based on the diffuse reflectance spectrum, the optical band gaps were determined to be 2.23(2) and 2.41(2) eV for Ba{sub 4}CuInSe{sub 6} and Ba{sub 4}AgInSe{sub 6}, respectively. - Graphical abstract: In the structure of Ba{sub 4}MInSe{sub 6} (M=Cu, Ag), the (M/In)Se{sub 4} tetrahedra are connected by corner-sharing to form chains along the b direction, which are separated by Ba atoms. Highlights: Black-Right-Pointing-Pointer Two new quaternary chalcogenides, Ba{sub 4}MInSe{sub 6} (M=Cu, Ag), were synthesized. Black-Right-Pointing-Pointer Ba{sub 4}MInSe{sub 6} (M=Cu, Ag) are isostructural and crystallize in the Ba{sub 2}MnS{sub 3} structure type Black-Right-Pointing-Pointer The (M/In)Se{sub 4} tetrahedra are connected by corner-sharing to form chains along the b direction. Black-Right-Pointing-Pointer The chains are separated by mono-capped trigonal prismatically coordinated Ba atoms. Black-Right-Pointing-Pointer The optical band gaps are 2.23(2) and 2.41(2) eV for Ba{sub 4}CuInSe{sub 6} and Ba{sub 4}AgInSe{sub 6}, respectively.

Yin Wenlong; Feng Kai; Hao Wenyu [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Yao Jiyong, E-mail: jyao@mail.ipc.ac.cn [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wu Yicheng [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2012-08-15

364

Monodisperse and 1D Cross-Linked Multi-branched Cu @ Ni Core-Shell Particles Synthesized by Chemical Reduction  

NASA Astrophysics Data System (ADS)

We report on a two-step wet chemical route for producing Cu@Ni core-shell particles with multiple needle-like branches on the surface. Using the usual synthesis process, urchin-like Ni shells were formed on the surface of spherical Cu cores and monodisperse particles were obtained. Under the direction of a static magnetic field, one-dimensional, well-aligned Cu@Ni particles were assembled through cross-linking the branched Ni shells. The monodisperse Cu@Ni particles show stable and uniform field electron emission, having a low turn-on field of 3.3 V/ ?m and a large current density of 1 mA/cm2 under an applied field of about 5.33 V/ ?m.

Hu, Hailong; Zhang, Dian; Yu, Weiming; Sugawara, Katsuyasu; Guo, Tailiang

2014-07-01

365

Microstructure and Properties of a High-Strength Cu-Ni-Si-Co-Zr Alloy  

NASA Astrophysics Data System (ADS)

A high-strength Cu-Ni-Si alloy was developed with the additions of Co and Zr. The aging curve for the alloy was generated using hardness. Electron microscopy studies were conducted to analyze the phases in the alloy. Two types of phases, one of copper matrix and the other of Ni-Si-Co-Zr intermetallic phase, could be identified using scanning electron microscopy. Transmission electron microscopy studies confirmed the presence of two types of precipitates in solution-treated and aged (STA) condition, i.e., Ni2Si and Co2Si. Mechanical properties and electrical conductivity were evaluated in solution-treated (ST) and STA conditions. Aging of the ST samples at 500 °C for 3 h has shown an increase of 72 and 15% in yield strength (YS) and electrical conductivity, respectively. This increase in YS and conductivity on aging is primarily attributed to the formation of fine Ni2Si and Co2Si precipitates.

Chenna Krishna, S.; Srinath, J.; Jha, Abhay K.; Pant, Bhanu; Sharma, S. C.; George, Koshy M.

2013-07-01

366

Temperature-dependent stability of stacking faults in Al, Cu and Ni: first-principles analysis  

NASA Astrophysics Data System (ADS)

We present comparative analysis of microscopic mechanisms relevant to plastic deformation of the face-centered cubic (FCC) metals Al, Cu, and Ni, through determination of the temperature-dependent free energies of intrinsic and unstable stacking faults along [1 \\bar{1} 0] and [1 \\bar{2} 1] on the (1?1?1) plane using first-principles density-functional-theory-based calculations. We show that vibrational contribution results in significant decrease in the free energy of barriers and intrinsic stacking faults (ISFs) of Al, Cu, and Ni with temperature, confirming an important role of thermal fluctuations in the stability of stacking faults (SFs) and deformation at elevated temperatures. In contrast to Al and Ni, the vibrational spectrum of the unstable stacking fault (USF_{[1\\,\\bar{2}\\,1]}) in Cu reveals structural instabilities, indicating that the energy barrier (?usf) along the (1?1?1)[1 \\bar{2} 1] slip system in Cu, determined by typical first-principles calculations, is an overestimate, and its commonly used interpretation as the energy release rate needed for dislocation nucleation, as proposed by Rice (1992 J. Mech. Phys. Solids 40 239), should be taken with caution.

Bhogra, Meha; Ramamurty, U.; Waghmare, Umesh V.

2014-09-01

367

Microstructure and Tensile Properties of Sn-1Ag-0.5Cu Solder Alloy Bearing Al for Electronics Applications  

NASA Astrophysics Data System (ADS)

This work investigates the effects of 0.1 wt.% and 0.5 wt.% Al additions on bulk alloy microstructure and tensile properties as well as on the thermal behavior of Sn-1Ag-0.5Cu (SAC105) lead-free solder alloy. The addition of 0.1 wt.% Al reduces the amount of Ag3Sn intermetallic compound (IMC) particles and leads to the formation of larger ternary Sn-Ag-Al IMC particles. However, the addition of 0.5 wt.% Al suppresses the formation of Ag3Sn IMC particles and leads to a large amount of fine Al-Ag IMC particles. Moreover, both 0.1 wt.% and 0.5 wt.% Al additions suppress the formation of Cu6Sn5 IMC particles and lead to the formation of larger Al-Cu IMC particles. The 0.1 wt.% Al-added solder shows a microstructure with coarse ?-Sn dendrites. However, the addition of 0.5 wt.% Al has a great effect on suppressing the undercooling and refinement of the ?-Sn dendrites. In addition to coarse ?-Sn dendrites, the formation of large Sn-Ag-Al and Al-Cu IMC particles significantly reduces the elastic modulus and yield strength for the SAC105 alloy containing 0.1 wt.% Al. On the other hand, the fine ?-Sn dendrite and the second-phase dispersion strengthening mechanism through the formation of fine Al-Ag IMC particles significantly increases the elastic modulus and yield strength of the SAC105 alloy containing 0.5 wt.% Al. Moreover, both 0.1 wt.% and 0.5 wt.% Al additions worsen the elongation. However, the reduction in elongation is much stronger, and brittle fracture occurs instead of ductile fracture, with 0.5 wt.% Al addition. The two additions of Al increase both solidus and liquidus temperatures. With 0.5 wt.% Al addition the pasty range is significantly reduced and the differential scanning calorimetry (DSC) endotherm curve gradually shifts from a dual to a single endothermic peak.

Shnawah, Dhafer Abdul-Ameer; Said, Suhana Binti Mohd; Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum; Hoe, Teh Guan; Che, Fa Xing; Abood, Adnan Naama

2012-08-01

368

Oxidation of ethyl acetate by a high performance nanostructure (Ni, Mn)-Ag/ZSM-5 bimetallic catalysts and development of an artificial neural networks predictive modeling.  

PubMed

The catalytic oxidation of ethyl acetate in low concentration was investigated over mono-metallic Ag/ZSM5 and bimetallic (Ni, Mn)-Ag/ZSM-5 catalysts. Catalytic studies were carried out in a catalytic fixed bed reactor under atmospheric pressure. The sequence of catalytic activity was as follows: Ni-Ag-ZSM-5 > Mn-Ag-ZSM-5 > Ag-ZSM-5 > H-ZSM-5. The catalysts were characterized by ICP-AES, X-ray diffraction (XRD), low temperature nitrogen adsorption, NH(3)-TPD, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and diffuse reflectance UV-vis spectra (UV-vis). An artificial neural networks (ANN) model was developed to predict the performance of catalytic oxidation process over bimetallic Ni-Ag/ZSM-5 catalyst based on experimental data. For this purpose the standard feed forward back propagation algorithm was employed to train the model by using laboratory experimental data. A good agreement was resulted between experimental results and those obtained by ANN. Following order for variables effects on conversion yield of ethyl acetate was predicted by ANN model: reaction temperature (32.99%) > Ag loading (27.38%) > initial ethyl acetate concentration (23.58%) > Ni loading (16.05%). PMID:21104495

Jodaei, Azadeh; Salari, Darush; Niaei, Ali; Khatamian, Masumeh; Hosseini, Seyed Ali

2011-01-01

369

Temperature and Ag Doping Effect on Magnetic Excitations in the Quasi-Two-Dimensional Triangular Lattice Antiferromagnet CuCrO2 Studied by Inelastic Neutron Scattering  

NASA Astrophysics Data System (ADS)

We have studied magnetic excitations in quasi-two-dimensional triangular lattice antiferromagnets CuCrO2 and Cu0.85Ag0.15CrO2 by inelastic neutron scattering. CuCrO2 has two types of magnetic excitations: one is highly dispersive, while the other is less dispersive and spreads over a wide Q range. With increasing temperature, the weight of the latter component transfers to a lower energy, and the spin dynamics becomes a mixture of a disordered spin wave and another diffuse component. Ag doping induces a similar spin dynamics even at 5 K. This manifests the impact of Ag doping on magnetic correlations and gives a clue to understanding the unconventional spin state in the Ag-doped CuCrO2.

Kajimoto, Ryoichi; Nakajima, Kenji; Ohira-Kawamura, Seiko; Inamura, Yasuhiro; Kakurai, Kazuhisa; Arai, Masatoshi; Hokazono, Takahisa; Oozono, Satoshi; Okuda, Tetsuji

2010-12-01

370

Texture improvements in the high-temperature superconducting Bi?Sr?Ca?Cu?Ox̳/Ag system via surface energy driven grain alignment  

E-print Network

The relation between processing, microstructure, and material property was investigated in the high-temperature superconducting Bi?Sr?Ca?Cu?Ox̳/Ag system. Experiments were based on a theoretical surface energy model ...

Vodhanel, Mark E

2005-01-01

371

Effect of Ag-doping on the intergranular properties of the superconducting Bi(Pb)-Sr-Ca-Cu-O system  

Microsoft Academic Search

The effect of Ag-doping and of heat treatment on the superconducting properties have been investigated for sintered Bi-(Pb)-Sr-Ca-Cu-O ceramics consisting of the high-Tc (2223) phase, where the samples were cooled at different rates immediately after the sintering. For undoped samples the impurity phases of (2212), Ca2PbO4 and (3221) were produced, while for doped samples the impurity phases were only (2201)

Katsukuni Yoshida; Yasushi Sano; Yoichi Tomii

1994-01-01

372

Enthalpy, heat of fusion and specific electrical resistivity of pure silver, pure copper and the binary Ag–28Cu alloy  

Microsoft Academic Search

Within the present work, recent investigation carried out with a fast pulse-heating technique on silver, copper and the Ag–28Cu binary alloy in the solid and the molten states are presented.Properties like enthalpy or electrical resistivity of a pulse-heated sample can be obtained for a wide temperature range (solid state up into the liquid state) from the directly measured base quantities,

C. Cagran; B. Wilthan; G. Pottlacher

2006-01-01

373

Structural properties of bulk Pd0.085Cu0.44Ag0.475 ternary alloy  

SciTech Connect

Advanced bulk properties of Pd0.085Cu0.44Ag0.475 are investigated by using MD simulation with Quantum Sutton-Chen semi-empirical inter atomic potential. The properties like enthalpy of mixing, temperature dependence of elastic constants, structure factor, cohesive energy, melting temperature, cell parameters and bulk modulus are calculated. Agreement with experimental values are presented wherever possible. Results have been discussed in detail.

Coruh, A.; Saribek, Y. [Sakarya Ueniversitesi, Fen-Edebiyat Fakueltesi, Fizik Boeluemue, Sakarya (Turkey); Tomak, M. [Ortadogu Teknik Ueniversitesi, Fen-Edebiyat Fakueltesi, Fizik Boeluemue, Ankara (Turkey); Cagin, T. [Texas A and M Univ, Dept. Chem. Engn., College Stn, TX 77845 (United States)

2007-04-23

374

Distributions of dissolved trace metals (Cd, Cu, Mn, Pb, Ag) in the southeastern Atlantic and the Southern Ocean  

NASA Astrophysics Data System (ADS)

Comprehensive synoptic datasets (surface water down to 4000 m) of dissolved cadmium (Cd), copper (Cu), manganese (Mn), lead (Pb) and silver (Ag) are presented along a section between 34° S and 57° S in the southeastern Atlantic Ocean and the Southern Ocean to the south off South Africa. The vertical distributions of Cu and Ag display nutrient-like profiles similar to silicic acid, and of Cd similar to phosphate. The distribution of Mn shows a subsurface maximum in the oxygen minimum zone, whereas Pb concentrations are rather invariable with depth. Dry deposition of aerosols is thought to be an important source of Pb to surface waters close to South Africa, and dry deposition and snowfall may have been significant sources of Cu and Mn at the higher latitudes. Furthermore, the advection of water masses enriched in trace metals following contact with continental margins appeared to be an important source of trace elements to the surface, intermediate and deep waters in the southeastern Atlantic Ocean and the Antarctic Circumpolar Current. Hydrothermal inputs may have formed a source of trace metals to the deep waters over the Bouvet Triple Junction ridge crest, as suggested by relatively enhanced dissolved Mn concentrations. The biological utilization of Cu and Ag was proportional to that of silicic acid across the section, suggesting that diatoms formed an important control over the removal of Cu and Ag from surface waters. However, uptake by dino- and nano-flagellates may have influenced the distribution of Cu and Ag in the surface waters of the subtropical Atlantic domain. Cadmium correlated strongly with phosphate (P), yielding lower Cd / P ratios in the subtropical surface waters where phosphate concentrations were below 0.95 ?M. The greater depletion of Cd relative to P observed in the Weddell Gyre compared to the Antarctic Circumpolar Current could be due to increase Cd uptake induced by iron-limiting conditions in these high-nutrient-low-chlorophyll waters. Similarly, an increase of Mn uptake under Fe-depleted conditions may have caused the highest depletion of Mn relative to P in the surface waters of the Weddell Gyre. In addition, a cellular Mn-transport channel of Cd was possibly activated in the Weddell Gyre, which in turn may have yielded depletion of both Mn and Cd in these surface waters.

Boye, M.; Wake, B. D.; Lopez Garcia, P.; Bown, J.; Baker, A. R.; Achterberg, E. P.

2012-08-01

375

Effect of the Cu thickness on the stability of a Ni\\/Cu bilayer UBM of lead free microbumps during liquid and solid state aging  

Microsoft Academic Search

The present study focuses on liquid and solid phase reactions between an electrodeposited bilayer UBM and Sn, which is chosen as worst case solder material for lead free bumping. Small sized bumps were realized by electrodeposition using one lithographic mask for electrodepositing the UBM and the solder. The bilayer UBM consists of an electrodeposited Ni and Cu layer (Nied, Cued)

C. Jurenka; Jon Yeon Kim; M. J. Wolf; G. Engelmann; O. Ehrmann; Jin Yu; H. Reichl

2005-01-01

376

Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization  

NASA Astrophysics Data System (ADS)

Electromigration of eutectic SnPb flip chip solder joints and their mean-time-to-failure (MTTF) have been studied in the temperature range of 100 to 140 °C with current densities of 1.9 to 2.75×104 A/cm2. In these joints, the under-bump-metallization (UBM) on the chip side is a multilayer thin film of Al/Ni(V)/Cu, and the metallic bond-pad on the substrate side is a very thick, electroless Ni layer covered with 30 nm of Au. When stressed at the higher current densities, the MTTF was found to decrease much faster than what is expected from the published Black's equation. The failure occurred by interfacial void propagation at the cathode side, and it is due to current crowding near the contact interface between the solder bump and the thin-film UBM. The current crowding is confirmed by a simulation of current distribution in the solder joint. Besides the interfacial void formation, the intermetallic compounds formed on the UBM as well as the Ni(V) film in the UBM have been found to dissolve completely into the solder bump during electromigration. Therefore, the electromigation failure is a combination of the interfacial void formation and the loss of UBM. Similar findings in eutectic SnAgCu flip chip solder joints have also been obtained and compared.

Choi, W. J.; Yeh, E. C. C.; Tu, K. N.

2003-11-01

377

Effect of Board Thickness on Sn-Ag-Cu Joint Interconnect Mechanical Shock Performance  

NASA Astrophysics Data System (ADS)

The mechanical stability of solder joints with Sn-Ag-Cu alloy joints on various board thicknesses was investigated with a high G level shock environment. A test vehicle with three different board thicknesses was used for board drop shock performance tests. These vehicles have three different strain and shock level condition couples per board, and are used to identify the joint stability and failure modes based on the board responses. The results revealed that joint stability is sensitive to board thickness. The board drop shock test showed that the first failure location shifts from the corner location near the standoff to the center with increased board thickness due to the shock wave response. From analysis of the thickness variation and failure cycle number, the strain rate during the pulse strain cycle is the dominant factor, which defines the life cycle number per board thickness, and not the maximum strain value. The failure location shift and the shock performance differentiation are discussed from the perspective of maximum principal strain, cycle frequency and strain rate per cycle.

Lee, Tae-Kyu; Xie, Weidong

2014-11-01

378

Effect of Aging Treatment on Fatigue Behavior of an Al-Cu-Mg-Ag Alloy  

NASA Astrophysics Data System (ADS)

An investigation of the fatigue properties of an Al-Cu-Mg-Ag alloy with two different heat treatments—peak aged (T6), and peak aged interrupted (T6I4)—has been conducted. While the strength levels resulting from the two heat treatments were similar, the main difference between the microstructures was that the peak aged interrupted material contained a higher volume fraction of the ?' precipitates. This study specifically focused on the effects of these treatments on the fatigue lifetime distribution, and the role of crack initiation vs the small crack growth behavior. Several total fatigue lifetime tests were completed at room temperature and at a given stress level to characterize the distribution in fatigue lifetimes. Fatigue results indicate that there is almost no difference in the mean lifetime for either heat treatment, but there is a significant difference in the minimum lifetimes, where the peak aged condition exhibited a higher propensity for life-limiting failure mechanisms. The small crack growth behavior of the two aging treatments was studied both at room temperature and elevated temperature by means of a standard acetate replication method. The small crack growth rates at both temperatures were largely unaffected by the different aging treatments. Based on the given number of tests, results suggest that the life-limiting fatigue failures of the two aging treatments are primarily governed by different crack initiation mechanisms due to the differences seen in the density of ?' precipitates.

Burba, M. E.; Caton, M. J.; Jha, S. K.; Szczepanski, C. J.

2013-11-01

379

Electronic structure and conductivity of nanocomposite metal (Au,Ag,Cu,Mo)-containing amorphous carbon films  

SciTech Connect

In this work, we study the influence of the incorporation of different metals (Me = Au, Ag, Cu, Mo) on the electronic structure of amorphous carbon (a-C:Me) films. The films were produced at room temperature using a novel pulsed dual-cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas X-ray diffraction was used to identify the formation of metal nanoclusters in the carbon matrix. The metal content incorporated in the nanocomposite films induces a drastic increase in the conductivity, in parallel with a decrease in the band gap corrected from Urbach energy. The electronic structure as a function of the Me content has been monitored by x-ray absorption near edge structure (XANES) at the C K-edge. XANES showed that the C host matrix has a dominant graphitic character and that it is not affected significantly by the incorporation of metal impurities, except for the case of Mo, where the modifications in the lineshape spectra indicated the formation of a carbide phase. Subtle modifications of the spectral lineshape are discussed in terms of nanocomposite formation.

Endrino, Jose L.; Horwat, David; Gago, Raul; Andersson, Joakim; Liu, Y.S.; Guo, Jinghua; Anders, Andre

2008-05-14

380

Post-irradiation annealing behavior of neutron-irradiated FeCu, FeMnNi and FeMnNiCu model alloys investigated by means of small-angle neutron scattering  

NASA Astrophysics Data System (ADS)

Neutron irradiation of reactor pressure vessel steels gives rise to the formation of thermodynamically stable and unstable nano-features. The present work is focused on the stability of Cu-, Mn- and Ni-containing solute clusters in model alloys exposed to post-irradiation annealing. Fe0.1Cu, Fe1.2Mn0.7Ni and Fe1.2Mn0.7Ni0.1Cu (wt%) model alloys irradiated up to neutron exposures of 0.1 and 0.19 dpa (displacements per atom) were annealed at stepwise increasing temperatures in the range from 300 °C (i.e. near irradiation temperature) to 500 °C and characterized by means of small-angle neutron scattering (SANS). We have found characteristic differences in the annealing behavior of the alloys. In particular, there is a non-trivial (synergistic-antagonistic) interplay of Mn/Ni and Cu.

Bergner, F.; Ulbricht, A.; Lindner, P.; Keiderling, U.; Malerba, L.

2014-11-01

381

Theoretical study of cytosine-Al, cytosine-Cu and cytosine-Ag (neutral, anionic and cationic).  

PubMed

The binding of cytosine to Al, Cu and Ag has been analyzed using the hybrid B3LYP density functional theory method. The three metals all have open shell electronic configuration, with only one unpaired valence electron. Thus it is possible to study the influence of electronic configuration on the stability of these systems. Neutral, cationic and anionic systems were analyzed, in order to assess the influence of atomic charge on bond formation. We argue that in the case of anions, nonconventional hydrogen bonds are formed. It is generally accepted that the hydrogen bond A-H...B is formed by the union of a proton donor group A-H and a proton acceptor B, which contains lone-pair electrons. In this study, we found that in the case of (Cu-cytosine)(-1) and (Ag-cytosine)(-1), N-H...Cu and N-H...Ag bonds are geometrically described as nonconventional hydrogen bonds. Their binding energies fall within the range of -20.0 to -55.4 kcal/mol (depending on the scheme of the reaction) and thus they are classified as examples of strong (>10 kcal/mol) hydrogen bonds. PMID:18193849

Vazquez, Marco-Vinicio; Martínez, Ana

2008-02-01

382

Ag{sub 2}CuMnO{sub 4}: A new silver copper oxide with delafossite structure  

SciTech Connect

The use of hydrothermal methods has allowed the synthesis of a new silver copper mixed oxide, Ag{sub 2}CuMnO{sub 4}, the first example of a quaternary oxide containing both elements. It crystallizes with the delafossite 3R structure, thus being the first delafossite to contain both Ag and Cu. Synthesis conditions affect the final particle size (30-500nm). Powder X-ray diffraction Rietveld refinement indicates a trigonal structure (R3-bar m) and cell parameters a=2.99991A and c=18.428A, where Cu and Mn are disordered within the octahedral B positions in the plane and linearly coordinated Ag occupies de A position between layers. X-ray absorption near edge spectroscopy (XANES) for copper and manganese, and XPS for silver evidence +2, +4, and +1 oxidation states. The microstructure consists of layered parts that may form large twins showing 5nm nanodomains. Finally, magnetic measurements reveal the existence of ferromagnetic coupling yielding in-plane moments that align antiferromagnetically at lower temperatures. The singularity of the new phase resides on the fact that is an example of a bidimensional arrangement of silver and copper in an oxide that also shows clear bidimensionality in its physical properties. That is of special relevance to the field of high T{sub c} superconducting oxides, while the ferromagnetic coupling in a bidimensional system deserves itself special attention.

Munoz-Rojas, David [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Subias, Gloria [Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza Pza. San Francisco s/n, 50009-Zaragoza (Spain); Oro-Sole, Judith [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Fraxedas, Jordi [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Martinez, Benjamin [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Casas-Cabanas, Montse [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Canales-Vazquez, Jesus [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Gonzalez-Calbet, Jose [UCM, Departamento de Quimica Inorganica, Facultad de Quimicas, Universidad Complutense, 28040 Madrid (Spain); Garcia-Gonzalez, Ester [UCM, Departamento de Quimica Inorganica, Facultad de Quimicas, Universidad Complutense, 28040 Madrid (Spain); Walton, Richard I. [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Casan-Pastor, Nieves [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain)]. E-mail: nieves@icmab.es

2006-12-15

383

Thermal cycling reliability of SnAgCu and SnPb solder joints: A comparison for several IC-packages  

Microsoft Academic Search

This paper deals with a comparison study between SnPb and SnAgCu solder joint reliability. The comparison is based on non-linear finite element modellin. Three packages have been selected: silicon CSP, underfilled flip chip and QFN package. Also the effect of thermal cycling conditions has been investigated. Comparing the induced inelastic strains in the solder joint, the leadfree SnAgCu generally scores

Bart Vandevelde; Mario Gonzalez; Paresh Limaye; Petar Ratchev; Eric Beyne

2007-01-01

384

{beta}-decay properties of {sup 72}Ni and {sup 72}Cu  

SciTech Connect

The {beta}-decay properties of {sub 28}{sup 72}Ni{sub 44} and {sub 29}{sup 72}Cu{sub 43} have been studied at the LISOL facility of Louvain-La-Neuve and at the CERN-ISOLDE facility, respectively. These neutron-rich nuclei have been produced in the proton-induced fission of {sup 238}U. Their decay schemes are presented and the lifetime T{sub 1/2}=6.63(3) s of {sup 72}Cu was measured. No {beta}-decaying isomeric state was found in {sup 72}Cu, in line with a suggested spin (2) for its ground state. Spin and parity assignments of the observed excited states in the odd-odd nucleus {sup 72}Cu are proposed and discussed in terms of coupling between the valence proton and neutrons. Comparison is made with a schematic shell-model picture of {sup 72}Cu and with large-scale shell-model calculations performed in the (2p{sub 3/2}1f{sub 5/2}2p{sub 1/2}1g{sub 9/2}) shell space outside the doubly magic {sub 28}{sup 56}Ni{sub 28} core.

Thomas, J.-C.; Witte, H. de; Gorska, M.; Huyse, M.; Kruglov, K.; Kudryavtsev, Y.; Pauwels, D.; Prasad, N. V. S. V.; Vel, K. van de; Duppen, P. van; Roosbroeck, J. van; Franchoo, S.; Cederkall, J.; Fynbo, H. O. U.; Georg, U.; Jonsson, O.; Koester, U.; Weissman, L.; Mueller, W. F.; Fedosseev, V. N. [Instituut voor Kern- en Stralingsfysica, University of Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); ISOLDE, CERN, CH-1211 Geneva 23 (Switzerland); National Superconducting Cyclotron Laboratory, Michigan State University, 164 S. Shaw Lane, 48824-1312 Michigan (United States); Institute of Spectroscopy, Russian Academy of Sciences, RU-142092 Troitsk (Russian Federation); St. Petersburg Nuclear Physics Institute, RU-188350 Gatchina (Russian Federation); Vakgroep Subatomaire en Stralingsfysica, Universiteit Gent, Proeftuinstraat 86, B-9000 Gent (Belgium)] (and others)

2006-11-15

385

Microstructural changes to AlCu6Ni1 alloy after prolonged annealing at elevated temperature.  

PubMed

This work presents results of microstructure examination of AlCu(6)Ni(1) aluminium alloy. The commercial AlCu(4)Ni(2)Mg(2) (M-309) alloy is widely used for elements of aircraft and automotive engines. Modification its chemical composition was aimed at improving the stability of mechanical properties of the alloy subjected to long-term exposure to high temperature. The alloy after standard T6 heat treatment (solution heat treated at 818 K/10 h/water quenched followed by ageing at 498 K/8 h/air cooled) was annealed for 150 h at elevated temperature of 573 K corresponding to the maximum value at which structural elements of jet piston engines made of aluminium alloys operate. It was found that applied heat treatment caused an increasing in the particles of hardening phase (theta'-Al(2)Cu) size. The significant growth of the length of theta'-Al(2)Cu precipitations was observed in particularly. Nevertheless, it did not strongly result in change of its shape - the 'crystallites' and 'rods' were still characteristic of hardening phase morphology. The phenomena of the growth of theta'-Al(2)Cu precipitates caused decreasing the mechanical properties of the alloy, what is the subject of further investigations by the authors. PMID:20500428

Wierzbi?ska, M; Sieniawski, J

2010-03-01

386

The microstructure and properties of single grain bulk Ag-doped Y–Ba–Cu–O fabricated by seeded infiltration and growth  

Microsoft Academic Search

Single grain, Ag-doped Y–Ba–Cu–O bulk superconductors of up to 30mm in diameter have been fabricated successfully by a seeded infiltration and growth (IG) technique. These samples exhibit low porosity compared with samples grown by conventional top seeded melt growth (TSMG). The density of voids within as-processed IG samples can be reduced further by adding metallic Ag, rather than Ag2O, to

K. Iida; N. H. Babu; Y. Shi; S. K. Pathak; W. K. Yeoh; T. Miyazaki; N. Sakai; M. Murakami; D. A. Cardwell

2008-01-01

387

Development of Sn-Ag-Cu-X Solders for Electronic Assembly by Micro-Alloying with Al  

NASA Astrophysics Data System (ADS)

Of Pb-free solder choices, an array of solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic ( T eut = 217°C) composition have emerged with potential for broad use, including ball grid array (BGA) joints that cool slowly. This work investigated minor substitutional additions of Al (<0.25 wt.%) to Sn-3.5Ag-0.95Cu (SAC3595) solders to promote more consistent solder joint microstructures and to avoid deleterious product phases, e.g., Ag3Sn "blades," for BGA cooling rates, since such Al additions to SAC had already demonstrated excellent thermal aging stability. Consistent with past work, blade formation was suppressed for increased Al content (>0.05Al), but the suppression effect faded for >0.20Al. Undercooling suppression did not correlate specifically with blade suppression since it became significant at 0.10Al and increased continuously with greater Al to 0.25Al. Surprisingly, an intermediate range of Al content (0.10 wt.% to 0.20 wt.% Al) promoted formation of significant populations of 2- ?m to 5- ?m faceted Cu-Al particles, identified as Cu33Al17, that clustered at the top of the solder joint matrix and exhibited extraordinary hardness. Clustering of Cu33Al17 was attributed to its buoyancy, from a lower density than Sn liquid, and its early position in the nucleation sequence within the solder matrix, permitting unrestricted migration to the top interface. Joint microstructures and implications for the full nucleation sequence for these SAC + Al solder joints are discussed, along with possible benefits from the clustered particles for improved thermal cycling resistance.

Boesenberg, Adam J.; Anderson, Iver E.; Harringa, Joel L.

2012-07-01

388

Frequency Dependence Modulus of Pd??Ni??Cu??P?? Amorphous Alloy around the Glass Transition by Dynamic Mechanical Analysis  

E-print Network

Dynamic Mechanical Analyzer (DMA) was used to study the frequency dependence of storage and loss modulus of amorphous Pd??Ni??Cu??P?? alloy over a broad frequency range around its glass transition temperature. The amorphous ...

Lee, M.L.

389

Oxidation parameters determination of Cu-Al-Ni-Fe shape-memory alloy at high temperatures  

NASA Astrophysics Data System (ADS)

In this study, isothermal oxidation behavior of a Cu-Al-Ni-Fe shape-memory alloy between 500 and 900 °C was investigated. Alloy samples were exposed to oxygen by TG/DTA for 1 h at a constant temperature, allowing for calculation of the oxidation constant and activation energy values of the oxidation process. The oxidation constant value increased with temperature, reaching saturation at 800 °C. The effect of oxidation on crystal structure, surface morphology and chemical composition of the Cu-Al-Ni-Fe alloy was determined by X-ray diffractometer (XRD) and scanning electron microscope (SEM)-energy-dispersive X-ray (EDX) analyses. With increasing oxidation temperature, number and intensity of the characteristic 18R martensite phase peaks were reduced while Al2O3 phase peaks were increased. In parallel to the XRD results, the same variations were also detected by SEM-EDX measurements.

Kök, Mediha; Yildiz, Koksal

2014-09-01

390

Microstructural evolution and mechanical properties of nanostructured Cu-Al-Ni shape memory alloys  

NASA Astrophysics Data System (ADS)

The melt spinning technique, with an applied cooling rate of about 106 K/s, was used to produce a nanostructured Cu+13.2Al+ 5.1Ni (in wt%) shape memory alloy. The properties of nanostructured ribbons were then compared with those of conventional coarse structure. The microstructural evolution was characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. Microhardness measurements indicate a two-fold increase in hardness because of the produced nanostructure. Comparing to its coarse structure, the nanostructured Cu-Al-Ni shape memory alloy exhibited the enhanced mechanical properties including a ductility of 6.5% and a pronounced plateau in the stress-strain curve.

Izadinia, M.; Dehghani, K.

2012-04-01

391

Effects of alternating seawater flow and stagnant layup conditions on the general and localized corrosion resistance of CuNi and NiCu alloys in marine service  

SciTech Connect

From time-to-time seawater handling systems are subjected to lay-up which can produce chemical and biological changes, and conceivably alter the corrosion resistance of metals used in piping and other equipment. In the case of reverse osmosis/membrane technology type desalination equipment, sanitizing agents may be introduced after draining. Simulation tests were conducted to determine any effect of a bisulfite sanitizing treatment when used between periods of normal seawater flow. Corresponding tests were conducted with lay-up comprising non-refreshed seawater which ultimately stagnated. Test results for CuNi alloy C71500 indicted that repeated cycling between seawater exposure and bisulfite treatments was detrimental in reducing that alloy`s resistance to general corrosion, and to a lesser degree its crevice corrosion resistance. The typical pitting and crevice corrosion behavior of NiCu alloy N04400, found upon exposure to slowly moving, aerated seawater was neither diminished or accelerated by cyclic lay-up with either stagnant seawater or the candidate bisulfite-containing solution. However, some increase in general corrosion was observed.

Kain, R.M. [LaQue Corrosion Services, Wrightsville Beach, NC (United States); Weber, B.E. [NAWC-Aircraft Div., Patuxent River, MD (United States)

1997-12-01

392

Raman scattering and IR vibrational modes of CuAlS{sub 2}, CuAlSe{sub 2}, and AgGaS{sub 2} crystals and CuAl{sub 1-x}Se{sub 2} solid solutions  

SciTech Connect

Raman scattering in CuAlS{sub 2}, CuAlSe{sub 2}, and AgGaS{sub 2} crystals and in CuAl{sub x}Ga{sub 1-x}Se{sub 2} solid solutions is studied at 300 and 77 K for the polarizations currently of interest. IR reflection spectra are studied in the one-phonon region, and the basic phonon parameters are determined, as well as the effective ion charges of anions and cations. It is shown that the electron clouds of ion cores are anisotropic. 23 refs., 12 figs., 9 tabs.

Syrbu, N.N. [Moldavian Technical Univ., Kishinev (Moldova, Republic of)

1995-08-01

393

Nonlinear optical properties and surface-plasmon enhanced optical limiting in Ag-Cu nanoclusters co-doped in SiO{sub 2} Sol-Gel films  

SciTech Connect

The nonlinear optical properties and the role of the surface-plasmon resonance (SPR) on optical limiting (OL) properties of Ag-Cu nanoclusters co-doped in SiO{sub 2} matrix prepared using the sol-gel technique with a Cu/Ag molar ratio of 1, 2 and 3, respectively, are presented. The studies were made using the second harmonic of high-power nanosecond and picosecond Nd:YAG lasers. These films show a self-defocusing nonlinearity with both nanosecond and picosecond pulses and a good nonlinear absorption behavior with the nanosecond pulse excitation. The nonlinear refractive index decreased with decreasing particle size, whereas the nonlinear absorption increased with an increase in Cu concentration. The observed nonlinear absorption is explained by taking into account the cumulative effect of both the intraband and interband mechanisms. The excitation near the SPR of Cu resulted in an enhanced OL behavior with increasing Cu concentration. No such concentration dependence is observed when the excitation is near the SPR of Ag, however, the limiting threshold is reduced approximately 10-17 times. Excitation at wavelengths far below the SPR of Ag and Cu has not shown any OL behavior. The major contribution toward OL is observed to be from the interband absorption and from a possible energy transfer within the higher unoccupied states of Cu and Ag. Although nonlinear scattering is observed at higher intensities, its contribution is found to be much less than that of the nonlinear absorption assisted by an energy transfer.

Kiran, P. Prem; Shivakiran Bhaktha, B.N.; Rao, D. Narayana; De, Goutam [School of Physics, University of Hyderabad, Hyderabad - 500 046 (India); Sol-Gel Division, Central Glass and Ceramic Research Institute, Jadavpur, Kolkata 700 032 (India)

2004-12-01

394

Ion exchange of Cu 2+, Ni 2+, Pb 2+ and Zn 2+ in analcime (ANA) synthesized from Thai perlite  

Microsoft Academic Search

This work studied the ion exchange of Cu2+, Ni2+, Pb2+ and Zn2+ into an analcime (ANA) in the temperature range 298–333K. The analcime was produced from an economically available Thai perlite. The selectivity sequence for ions entering analcime in its as-synthesized sodium form was Pb2+>Cu2+>Zn2+>Ni2+, as indicated by values of ?G0. The results demonstrated that the enthalpy of cation hydration

Sudaporn Tangkawanit; Kunwadee Rangsriwatananon; Alan Dyer

2005-01-01

395

Low-temperature water-gas shift reaction over Cu and Ni-loaded cerium oxide catalysts  

Microsoft Academic Search

In this paper we report on the activity of Cu- and Ni-containing cerium oxide catalysts for low-temperature water-gas shift (WGS). Bulk catalysts were prepared in nanocrystalline form by the urea co-precipitation–gelation method. Lanthanum dopant (10at.%) was used as a structural stabilizer of ceria, while the content of Cu or Ni was in the range of 5–15at.% (2–8wt.%). At low metal

Yue Li; Qi Fu; Maria Flytzani-Stephanopoulos

2000-01-01

396

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

E-print Network

dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead the conventional ceramic route. The raw materials (Fe2O3, NiO, ZnO, CuO) were ball milled for 24 hours in water. Co are essential materials because of their high permeability in MHz range. Moreover, their low sintering

Paris-Sud XI, Université de

397

The Kalatongke magmatic Ni–Cu deposits in the Central Asian Orogenic Belt, NW China: product of slab window magmatism?  

Microsoft Academic Search

The Permian Kalatongke Ni–Cu deposits in the Central Asian Orogenic Belt are among the most important Ni–Cu deposits in northern\\u000a Xinjiang, western China. The deposits are hosted by three small mafic intrusions comprising mainly norite and diorite. Its\\u000a tectonic context, petrogenesis, and ore genesis have been highly contested. In this paper, we present a new model involving\\u000a slab window magmatism

Chusi Li; Mingjie Zhang; Piaoer Fu; Zhuangzhi Qian; Peiqing Hu; Edward M. Ripley

2011-01-01

398

Effects of mine effluent on uptake of Co, Ni, Cu, As, Zn, Cd, Cr and Pb by aquatic macrophytes  

Microsoft Academic Search

Concentrations of Ni, Co, Cu, Pb, Zn, Cd, Cr and As were determined in aquatic sediments, water and macrophytes collected from a fluvial system, contaminated by mine effluents. Myriophyllum verticillatum collected in May below the trace element point source accumulated 169 µg\\/g of Ni, 860 µg\\/g of Co, 37 µg\\/g of Cu, 31 µg\\/g of Pb, 92 µg\\/g of Zn,

Alena Mudroch; John A. Capobianco

1979-01-01

399

Investigation of Cd, Cu, Ni and 234Th in the colloidal size range in the Gulf of Maine  

Microsoft Academic Search

Size-fractionated seawater samples were collected from the Gulf of Maine to determine the fraction (fcd) of total dissolved (< 1 ?m) Cd, Cu, Ni and 234Th in the colloidal size range (1,000 nominal molecular weight, NMW, to 1 ?m) using cross-flow filtration. Colloidal Cd, Cu and Ni represents < 1–7% of the total dissolved concentration in these shelf waters and

Jennifer M. Greenamoyer; S. Bradley Moran

1997-01-01

400

Controlled fabrication of 0 & 2D NiCu amorphous nanoalloys by the cooperation of hard–soft interfacial templates  

Microsoft Academic Search

Assembling-controlled synthesis is carried out for fabrication 0 & 2D NiCu amorphous nanoalloys through the cooperation of hard–soft interfacial templates in different template-assist routes at room temperature. The controlled fabrication of 0D nanospheres and 2D ultrathin nanofilms of NiCu amorphous alloys is attributed to the synergistic effect between structure-inducing of hard collodion membrane and the reactor volume adjusting of reverse

Ming Wen; YaFen Wang; Qingsheng Wu; Yi Jin; MingZhu Cheng

2010-01-01

401

The determination of heavy metals in the Ligurian Sea. II. The geographical and vertical distribution of Cd, Cu, and Ni  

NASA Astrophysics Data System (ADS)

Cd, Cu, and Ni were determined in surface and deep-water samples from 15 stations in the Ligurian Sea. The samples were preconcentrated in chelating resins and quantitatively determined by atomic absorption spectrophotometry. The variability of the concentrations with depth was in general not significant compared with the variability of the analytical method, except at the station nearest the shore. Statistical analyses of the mean concentrations show also no significant regional variations in Cu, Ni, and Cd.

Frache, Roberto; Baffi, Franca; Dadone, Arduino; Scarponi, Giuseppe; Dagnino, Ignazio

1980-12-01

402

Projectile fragmentation of radioactive beams of Ni68, Cu69, and Zn72  

Microsoft Academic Search

The fragment production cross sections of secondary neutron-rich beams of Ni68, Cu69, and Zn72 isotopes at energies of about 95A MeV have been measured. We compare the measured cross sections to EPAX, an empirical parametrization of fragmentation cross sections. A reasonable agreement of the experimental data and EPAX predictions suggests that an EPAX parametrization used for stable beams seems to

S. Lukyanov; M. Mocko; L. Andronenko; M. Andronenko; D. Bazin; M. A. Famiano; A. Gade; S. P. Lobastov; W. G. Lynch; A. M. Rogers; O. B. Tarasov; M. B. Tsang; G. Verde; M. S. Wallace; R. G. T. Zegers

2009-01-01

403

Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn  

SciTech Connect

This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C{sub 3}S, C{sub 2}S, C{sub 3}A and C{sub 4}AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C{sub 3}S, 18% C{sub 2}S, 8% C{sub 3}A and 8% C{sub 4}AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO{sub 2}) and Sn reacted with lime to form a calcium stannate (Ca{sub 2}SnO{sub 4}). Cu changed the crystallisation process and affected therefore the formation of C{sub 3}S. Indeed a high content of Cu in clinker led to the decomposition of C{sub 3}S into C{sub 2}S and of free lime. Zn, in turn, affected the formation of C{sub 3}A. Ca{sub 6}Zn{sub 3}Al{sub 4}O{sub 15} was formed whilst a tremendous reduction of C{sub 3}A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

Gineys, N., E-mail: nathalie.gineys@mines-douai.fr [Univ. Lille Nord de France, F-59000 Lille (France); EMDouai, LGCgE-MPE-GCE, F-59508 Douai (France); Aouad, G. [Univ. Lille Nord de France, F-59000 Lille (France); EMDouai, LGCgE-MPE-GCE, F-59508 Douai (France); Sorrentino, F. [Mineral Research Processing Company, 69330 Meyzieu (France); Damidot, D. [Univ. Lille Nord de France, F-59000 Lille (France); EMDouai, LGCgE-MPE-GCE, F-59508 Douai (France)

2011-11-15

404

Structure and strength of the age hardened Cu–Ni–Si alloy  

Microsoft Academic Search

Age hardening in Cu–3.2Ni–0.75Si (wt.%) alloy at 723K is studied. An immediate increase of the yield strength characterizes the aging of the alloy. This is followed by the regions of constant yield strength and further by a peak. The microstructure of the alloy was studied by means of transmission electron microscope (TEM) and X-ray diffraction. Spinodal decomposition takes place followed

D. M Zhao; Q. M Dong; P Liu; B. X Kang; J. L Huang; Z. H Jin

2003-01-01

405

In situ formed Ti–Cu–Ni–Sn–Ta nanostructure-dendrite composite with large plasticity  

Microsoft Academic Search

A group of Ti–Cu–Ni–Sn–Ta multicomponent alloys is prepared by copper mold casting and arc melting, respectively, in which nanostructured (or ultrafine-grained) matrix-dendrite composites can be obtained. With increasing Ti and Ta contents, the volume fraction of the dendritic phase increases. The grain size of the matrix phase depends on the preparation method, and is 30–70 nm for as-cast 2–3 mm

G He; W Löser; J Eckert

2003-01-01

406

CORROSION INHIBITION OF CuNi10Fe ALLOY WITH PHENOLIC ACIDS  

Microsoft Academic Search

The purpose of this study was to investigate the efficiency of two phenolic acids, namely p-hydroxybenzoic acid (HBA) and protocatechuic acid (PCA), as corrosion inhibitors for CuNi10Fe alloy in a 0.5 mol dm NaCl solution. In these investigations, open circuit potential measurements, potentiodynamic polarization measurements, and the linear polarization method have been used. It was found that both phenolic acids had similar

L. Vrsalovi?; E. Oguzie; M. Kliški?; S. Gudi?

2011-01-01

407

RECOVERY OF Co, Ni, AND Cu FROM THE TAILINGS OF DIVRIGI IRON ORE CONCENTRATOR  

Microsoft Academic Search

In the Sivas-Divri?i Iron Ore Concentrator, 600,000 t of tailings are discarded annually. There are already 1 million t of tailings deposited in ponds from the previous production activities. The presence of Co, Ni, and Cu in the tailings makes the beneficiation of those tailings attractive. In the experimental work, sulphide concentrates were produced from these two types of tailings by

A. A. Sirkeci; A. Gül; G. Bulut; F. Arslan; G. Onal; A. E. Yuce

2006-01-01

408

Structure and mechanical properties of Ni-Cu-Ti-Zr composite materials with amorphous phase  

NASA Astrophysics Data System (ADS)

The structure of specimens of Ni-Cu-Ti-Zr alloys with an amorphous phase has been examined by X-ray diffraction, as well as by transmission and scanning electron microscopy. Mechanical characteristics of the alloys have been determined using universal testing machines. Transformation-induced plasticity has been found to exist. The specimens demonstrate a good combination of strength and plasticity owing to both the composite effect of a heterophase structure and the dynamic martensitic transformation that develops during deformation.

Churyumov, A. Yu.; Bazlov, A. I.; Solonin, A. N.; Zadorozhnyi, V. Yu.; Xie, G. Q.; Li, S.; Louzguine-Luzgin, D. V.

2013-09-01

409

Low energy ($p,?$) reactions in Ni and Cu nuclei using microscopic optical model  

E-print Network

Radiative capture reactions for low energy protons have been theoretically studied for Ni and Cu isotopes using the microscopic optical model. The optical potential has been obtained in the folding model using different microscopic interactions with the nuclear densities from Relativistic Mean Field calculations. The calculated total cross sections as well as the cross sections for individually low lying levels have been compared with measurements involving stable nuclear targets. Rates for the rapid proton capture process have been evaluated for astrophysically important reactions.

G. Gangopadhyay

2010-08-05

410

Formation of Ni–Cu–Platinum Group Element sulfide mineralization in the Sudbury Impact Melt Sheet  

Microsoft Academic Search

Summary The Ni–Cu–Platinum Group Element (PGE) sulfide deposits of the Sudbury Structure have provided a major portion of the world’s total nickel production and their host rocks have been the subject of numerous research studies, yet a number of perplexing problems remain to be solved. On the one hand, studies seeking to explain the formation of the Sudbury Structure have

R. R. Keays; P. C. Lightfoot

2004-01-01

411

Numerical prediction of fraction of eutectic phase in Sn-Ag-Cu soldring using the phase-field method  

NASA Astrophysics Data System (ADS)

A combination of macroscale solidification simulation and phase-field calculation is employed to predict the volume fraction of the eutectic phase in Sn-4.0 mass% Ag-XCu solder alloys (X=0.5 1.1 mass%). The solidification simulation incorporates the cooling rate in the phase-field simulation. We assume the residual liquid solidifies as eutectic phase when the driving force for the nucleation of Cu6Sn5 amounts to a critical value, which is determined based on the experimental data. Though the calculation results depend on the experimental data, the obtained fractions are about 40% for 0.5 mass% Cu and more than 90% for 1.1 mass% Cu alloy, which shows good agreement with the experimental data.

Ode, Machiko; Ueshima, Minoru; Abe, Taichi; Murakami, Hideyuki; Onodera, Hidehiro

2006-11-01

412

Nanocomposite Formation in Zr-Al-Cu-Ni-Fe Amorphous Alloys by Mechanically Assisted Nitriding  

SciTech Connect

Zr-Al-Cu-Ni-Fe belongs to the best glass forming systems known. These glasses present a high thermal stability and are suitable as precursor material for nanocomposites containing a variety of particles. At this respect, the presence of a second phase embedded in the amorphous matrix improves their mechanical properties. Ball milling has already demonstrated to be a valuable processing route for producing amorphous matrix nanocomposites, allowing by passing most of the limitations inherent to the casting techniques. In this work we present results on the formation, structure and thermal stability of nanocrystalline nitride particles dispersed in a Zr-Cu-Al-Ni-Fe amorphous matrix. The nitride particles were obtained by high-energy ball milling of Zr64Al7Cu17Ni10Fe2 amorphous ribbons in nitrogen atmosphere. The resulting nanocomposite structure was studied by Moessbauer spectroscopy and x-ray diffraction. Their thermal behavior was analyzed by differential scanning calorimetry, showing an increase in the thermal stability of the amorphous matrix by the composite formation.

Bab, M.A. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC67, 1900 La Plata (Argentina); Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas, Fac. de Ciencias Exactas, Universidad Nacional de La Plata, Sucursal 4 CC16, 1900 La Plata (Argentina); Damonte, L.C.; Mendoza-Zelis, L.A. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC67, 1900 La Plata (Argentina)

2005-04-26

413

NiTiCu Shape Memory Alloy Characterization Through Microhardness Tests  

NASA Astrophysics Data System (ADS)

NiTiCu alloys are one of the most investigated shape memory alloys (SMAs) because of their better performance as SMA actuators in a variety of industrial and engineering applications. However, NiTiCu alloys are strongly influenced by thermomechanical cycling (TMC), which causes degradation depending on the stress and strain level applied. Since heat treatment (HT) and TMC are essential for NiTiCu alloys, understanding how hardness evolves at different levels of TMC and different HT temperatures is a useful tool for characterizing the material. The aim of this paper is to investigate the relationship between hardness and different HT temperatures and different TMCs. All the microhardness tests were done below martensite finish temperature (Mf) because the apparent material hardness measured below Mf fairly reflects the relative strengthening of SMAs without involving martensitic transformation artifacts. Resistivity and break tensile tests were carried out as a first step in order to understand the effect of different HT temperatures. Microstructure was also examined to provide a basis for a mechanistic understanding of the effect of different HT temperatures. Next, the degradation of mechanical properties (functional fatigue) at different levels of TMC was evaluated to assess their relationship to the evolution of hardness. Finally, an attempt was made to establish a link between the increase in hardness and different HT temperatures with different levels of TMC.

Fabregat-Sanjuan, Albert; Ferrando, Francesc; De la Flor, Silvia

2014-07-01

414

Electronic structure and bonding in metal phthalocyanines, Metal=Fe, Co, Ni, Cu, Zn, Mg  

NASA Astrophysics Data System (ADS)

Electronic structure and bonding in metal phthalocyanines (Metal=Fe, Co, Ni, Cu, Zn, Mg) is investigated in detail using a density functional method. The metal atoms are strongly bound to the phthalocyanine ring in each case, by as much as 10 eV. The calculated orbital energy levels and relative total energies of these D4h structures indicate that Fe and Co phthalocyanines have 3A2g and 2Eg ground states, respectively, but that these states are changed upon interaction with strong-field axial ligands. The valence electronic structures of Fe and Co phthalocyanines differ significantly from those of the others. The HOMOs in Fe, Co, and Cu phthalocyanine are metal 3d-like, whereas in Ni and Zn phthalocyanines, the HOMO is localized on the phthalocyanine ring. The first ionization removes an electron from the phthalocyanine a1u orbital in all cases, with very little sensitivity of the ionization energy to the identity of the metal. Whereas the first reduction in Fe and Co phthalocyanine occurs at the metal, it is the phthalocyanine that is reduced upon addition of an electron to the other systems. Fe, Ni, and Cu phthalocyanines have smaller HOMO-LUMO separations than do Zn and Co phthalocyanine. There is very little variation in atomic charges within the phthalocyanine from one metal to the next.

Liao, Meng-Sheng; Scheiner, Steve

2001-06-01

415

Nanocomposite Formation in Zr-Al-Cu-Ni-Fe Amorphous Alloys by Mechanically Assisted Nitriding  

NASA Astrophysics Data System (ADS)

Zr-Al-Cu-Ni-Fe belongs to the best glass forming systems known. These glasses present a high thermal stability and are suitable as precursor material for nanocomposites containing a variety of particles. At this respect, the presence of a second phase embedded in the amorphous matrix improves their mechanical properties. Ball milling has already demonstrated to be a valuable processing route for producing amorphous matrix nanocomposites, allowing by passing most of the limitations inherent to the casting techniques. In this work we present results on the formation, structure and thermal stability of nanocrystalline nitride particles dispersed in a Zr-Cu-Al-Ni-Fe amorphous matrix. The nitride particles were obtained by high-energy ball milling of Zr64Al7Cu17Ni10Fe2 amorphous ribbons in nitrogen atmosphere. The resulting nanocomposite structure was studied by Mössbauer spectroscopy and x-ray diffraction. Their thermal behavior was analyzed by differential scanning calorimetry, showing an increase in the thermal stability of the amorphous matrix by the composite formation.

Bab, M. A.; Damonte, L. C.; Mendoza-Zélis, L. A.

2005-04-01

416

Heavy metals (Ni, Cr, Cu) in the Karoon waterway river, Iran.  

PubMed

Environmental pollution is a world-wide problem, heavy metals belonging to the most important pollutants. The progress of industries has led to increased emission of pollutants into ecosystems. Karoon is the biggest and only navigable river in the South of Iran. Along the Karoon industrial units such as piping, steel, paint making, agriculture, paper mill, fish cultivation, abbottiors, electroplating industries drain their wastewater into the river. In this study, the concentrations of heavy metals (Ni, Cr, Cu) in the Karoon river have been determined. Samples were collected from 16 stations along the river, in winter and spring 1996. Heavy metal concentrations were measured by graphite furnace atomic absorption spectrometry. The minimal and maximal concentrations of these metals in winter were 69.3-110.7, 1.7-118.3, and 5.5-70.3 microg/l, for Ni, Cr, and Cu, respectively. The minimal and maximal concentrations of these metals in spring were 41.0-60.7, 0.7-19.8, and 0.5-28.7 microg/l, for Ni, Cr, and Cu, respectively. The results show that the pollution has increased along the river, down to the estuary at the Persian Gulf. PMID:15177641

Diagomanolin, V; Farhang, M; Ghazi-Khansari, M; Jafarzadeh, N

2004-06-15

417

Thermal behavior of Ni- and Cu-containing plasma electrolytic oxide coatings on titanium  

NASA Astrophysics Data System (ADS)

In this work the effect of thermal annealing on the surface composition, structure and catalytic activity in CO oxidation of NiO + CuO/TiO2/Ti composites is studied. The composites have been obtained by a plasma electrolytic oxidation (PEO) technique, followed by impregnation in a solution of nickel (II) and copper (II) salts and air annealing. The structures contain ˜20 at% Ni and ˜12 at% Cu. It has been shown that the additional air annealing of such structures at temperature above 750 °C results in phosphate crystallization in the coatings and decreasing of Cu concentration in the surface layers. A growth of filiform nanocrystals containing mainly oxygen compounds of nickel and titanium on the coating surface takes place at the temperatures above 700 °C. The nanocrystals have a diameter of 50-200 nm and lengths below 10 ?m. Such changes result in decreasing of catalytic activity of the composites in CO oxidation. At the same time the ascertained regularities may be of interest for obtaining the Ni-containing oxide catalysts with an extended surface, perspective for usage in organic catalysis or for preparing oxide nanofibers.

Rudnev, V. S.; Wybornov, S.; Lukiyanchuk, I. V.; Staedler, T.; Jiang, X.; Ustinov, A. Yu.; Vasilyeva, M. S.

2012-09-01

418

Stabilization of Cu?Ni/Nb-Ti superconductors by MgO powder  

NASA Astrophysics Data System (ADS)

The Cu?Ni/Nb?Ti superconductor of a persistent current switch (PCS) with high normal state resistance is very susceptible to external disturbances. To stabilize the PCS, it is necessary to improve its mean thermal conductivity. A MgO powder coating was used on the surface of the conductors as a stabilizer. The thermal conductivity of MgO is two orders of magnitude larger than that of Cu?Ni at < 10 K. Since the MgO is an insulator, it can be used at any place in the PCS. The values of minimum quench energy (MQE) for the Cu-Ni/Nb-Ti? single wire and a formed strand conductor with a rectangular shape were measured using a pulse heating technique. The results obtained show that the MQE values for the stabilized single wire and the strand conductor with MgO powder were three times larger than those of the non-stabilized single wire and strand conductor. From these results it is expected that a PCS can be stabilized by a surface coating of MgO.

Yokoyama, S.; Yamamoto, S.; Nakamura, S.; Yamada, T.

419

Multiply twinned AgNi alloy nanoparticles as highly active catalyst for multiple reduction and degradation reactions.  

PubMed

Size dependent surface characteristics of nanoparticles lead to use of these nanomaterials in many technologically important fields, including the field of catalysis. Here Ag(1-x)Ni(x) bimetallic alloy nanoparticles have been developed having a 5-fold twinned morphology, which could be considered as an important alloy because of their excellent and unique catalytic and magnetic properties. Alloying between Ag and Ni atoms on a nanoscale has been confirmed with detailed X-ray diffraction, high resolution transmission electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and magnetization measurements. Although introduced for the first time as a catalyst due to having high active surface sites, the as-synthesized nanoparticles showed one of the best multiple catalytic activity in the industrially important (electro)-catalytic reduction of 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) to corresponding amines with noticeable reduced reaction time and increased rate constant without the use of any large area support. Additionally the same catalyst showed enhanced catalytic activity in degradation of environment polluting dye molecules. The highest ever activity parameter we report here for Ag0.6Ni0.4 composition is 156 s(-1)g(-1) with an apparent rate constant of 31.1 × 10(-3) s(-1) in a 4-NP reduction reaction where the amount of catalyst used was 0.2 mg and the time taken for complete conversion of 4-NP to 4-aminophenol was 60 s. Similarly, an incredible reaction rate constant (115 s(-1)) and activity parameter (576.6 s(-1)g(-1)) were observed for the catalytic degradation of methyl orange dye where 15 s is the maximum time for complete degradation of the dye molecules. The high catalytic performance of present AgNi alloy NPs over the other catalysts has been attributed to size, structural (twinned defect) and electronic effects. This study may lead to use of these bimetallic nanostructures with excellent recyclable catalytic efficiency in many more applications. PMID:25171089

Kumar, Mukesh; Deka, Sasanka

2014-09-24

420

Influence of oxygen partial pressure on the physical properties of Ag doped NiO thin films  

NASA Astrophysics Data System (ADS)

Ag doped p-type NiO thin films were successfully deposited by DC reactive magnetron sputtering technique at different oxygen partial pressures in the range 1 × 10-4 - 9 × 10-4 mbar. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). All the deposited films were of polycrystalline nature and exhibited cubic structure with preferential growth. The morphological studies revealed that the surface roughness was increased with increasing oxygen partial pressure up to 5 × 10-4 mbar and decreased at higher oxygen partial pressures.

Reddy, Y. Ashok Kumar; Reddy, A. Sivasankar; Reddy, P. Sreedhara

2013-06-01

421

Optical, Raman and vibrational properties of closed shell Ag-Cu clusters from density functional theory: The influence of the atomic structure, exchange-correlation approximations and pseudopotentials  

NASA Astrophysics Data System (ADS)

The optical, Raman and vibrational properties of 8-atom closed shell Ag-Cu clusters are systemically investigated within the framework of density functional theory with eight kinds of exchange-correction functionals: generalized gradient approximation (GGA) and local-density approximation (LDA), as well as DFT-based semi-core pseudopotential (Dspp) and all-electron (AE). Results reveal that the optical spectra of pure Ag8 and Cu8 clusters are in excellent agreement with the experiments; moreover, both tetracapped tetrahedron (TcTd) and monocapped pentagonal bipyramid (McPb) contribute to the experimental absorption spectra. For the optical, Raman and vibrational spectra of Ag-Cu clusters, the differences between TcTd and McPb, that are intensity and position energies of the strongest peaks as well as the appearance of additional peaks, are visible obviously. Exchange-correction functionals have little effect on the optical, Raman and vibrational spectra of Ag-Cu clusters. On comparing the spectra using GGA with those using LDA, the position energies of the corresponding peaks are lower, which shows obviously in the rich Cu atoms' clusters. However, pseudopotentials have some effects on them. The intensities of absorption peaks for Ag-Cu clusters using Dspp are weaker than those using AE; in particular, this effect of rich Ag atom clusters is shown obviously. The intensities of Raman peaks for Ag-Cu clusters using Dspp are larger than those using AE. An additional peak appears in the vibrational spectra of TcTd using Dspp but not in the ones using AE for AgnCu8-n (n=2-8) clusters. The vibrational and Raman spectroscopy may be helpful in determining cluster size and structure.

Li, Weiyin; Chen, Fuyi

2014-06-01

422