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Sample records for cu ag ni

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

    NASA Astrophysics Data System (ADS)

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

    1996-04-01

    Negative ion photoelectron spectra of NiCu-, NiAg-, NiAg-2, and Ni2Ag- are presented for electron binding energies up to 3.5 eV. The metal cluster anions were prepared in a cold cathode dc discharge flowing afterglow source. The dimer spectra exhibit three low lying electronic states; the ground electronic states are vibrationally resolved. The dimer electron affinities are determined to be EA(NiCu)=0.8890.010 eV and EA(NiAg)=0.9790.010 eV. Two excited state electron configurations are assigned as (d8Nid10Cu?2?*1) and as 4? (d9Nid10Cu?1?*1). The NiCu- ground state is assigned as 3? (d9Nid10Cu?2?*1), and has a vibrational frequency of 23525 cm-1. The photoelectron spectrum of NiAg- strongly suggests that the electronic configurations of the three observed states are the same as those of NiCu-. The NiAg ground state vibrational frequency is 23525 cm-1 and the NiAg- frequency is 18525 cm-1. The chemical bonding in both NiCu and NiAg dimers is dominated by a s? molecular orbital, and the extra electron in the anions has primarily s?* character. The photoelectron spectra of the trimers, NiAg-2 and Ni2Ag-, are remarkably similar to those obtained for the coinage metal trimers, and are consistent with a transition between a linear anion ground state and a linear excited state of the neutral.

  2. Growth Behavior of Intermetallic Compounds at SnAgCu/Ni and Cu Interfaces

    NASA Astrophysics Data System (ADS)

    Qi, Lihua; Huang, Jihua; Zhang, Hua; Zhao, Xingke; Wang, Haitao; Cheng, Donghai

    2010-02-01

    The growth behavior of reaction-formed intermetallic compounds (IMCs) at Sn3.5Ag0.5Cu/Ni and Cu interfaces under thermal-shear cycling conditions was investigated. The results show that the morphology of (Cu x Ni1- x )6Sn5 and Cu6Sn5 IMCs formed both at Sn3.5Ag0.5Cu/Ni and Cu interfaces gradually changed from scallop-like to chunk-like, and different IMC thicknesses developed with increasing thermal-shear cycling time. Furthermore, Cu6Sn5 IMC growth rate at the Sn3.5Ag0.5Cu/Cu interface was higher than that of (Cu x Ni1- x )6Sn5 IMC under thermal-shear cycling. Compared to isothermal aging, thermal-shear cycling led to only one Cu6Sn5 layer at the interface between SnAgCu solder and Cu substrate after 720 cycles. Moreover, Ag3Sn IMC was dispersed uniformly in the solder after reflow. The planar Ag3Sn formed near the interface changed remarkably and merged together to large platelets with increasing cycles. The mechanism of formation of Cu6Sn5, (Cu x Ni1- x )6Sn5 and Ag3Sn IMCs during thermal-shear cycling process was investigated.

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

    E-print Network

    Goddard III, William A.

    -Ag and Cu-Ni Yue Qi, Tahir C agin,* Yoshitaka Kimura, and William A. Goddard III* Materials and Process alloys. These studies use the quantum Sutton-Chen many-body potentials for Cu, Ni, and Ag to examine the Cu4Ag6 and CuNi alloys. Using cooling rates in the range of 2 1012 to 4 1014 K/s, we find that CuNi

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

    SciTech Connect

    Wang, Z.; Perepezko, J. H.

    2013-11-04

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

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

    ERIC Educational Resources Information Center

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

    2007-01-01

    Experiment is conducted to determine the kinetic parameters of metal-solution interfaces. During the experiment the kinetic parameters for the interfaces Cu-NH[subscript 3], Ag-NH[subscript 3] and Ni-NH[subscript 3] is easily determined.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  7. 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)

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

    2014-11-01

    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.

  8. Deformation Behavior and Microstructure Evolution of the Cu-2Ni-0.5Si-0.15Ag Alloy During Hot

    E-print Network

    Volinsky, Alex A.

    are widely used as the lead frame materials, including Cu-Ni-Si, Cu-Fe, Cu-Fe-P, Cu-Cr-Zr, and Cu-Ag alloys. Among these alloys, Cu-Ni-Si has become a research focus due to its high strength and hardness, good processing properties, and modest electrical conductivity.[213] Cu-Ni-Si alloy is one of the age

  9. Solubility and Dissolution Rate of Ni Base Alloy to Molten Ag-Cu-Pd Brazing Filler

    NASA Astrophysics Data System (ADS)

    Ikeshoji, Toshi-Taka; Watanabe, Yuki; Suzumura, Akio; Yamazaki, Takahisa

    During the brazing process of the rocket engines nozzle skirt assembly made from Fe-Ni based super alloy pipes with Pd based brazing filler, the erosion corrosion pits were sometimes engraved on those pipes surface. The corrosion is considered to be assisted by the dynamic flow of the molten brazing filler. In order to estimate the amount of erosion corrosion and to prevent it, the solubility and the dissolution rate of Ni to the molten Ag-Cu-Pd brazing filler are measured experimentally. The Ni crucible poured with the Ag-Cu-Pd brazing filler was heated up to 1320K and quenched after the various keeping time. The microstructure of the solidified brazing filler parts cross sections was observed, and the amount of the dissolved Ni was estimated using the image processing technique. The solubility was about 5.53mass%and the initial dissolution rate was 6.28 10-3mass%/s. Using these data, more elaborate dynamic flow simulation will be able to conduct.

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    SciTech Connect

    Wang Yue; Shi Yongfang; Chen Yubiao; Wu Liming

    2012-07-15

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

  14. 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)

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

    2015-02-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    The interfacial reaction between Ni and Sn-3Ag-0.5Cu- xPd alloys ( x = 0 wt.% to 1 wt.%) at 250C and the mechanical reliability of the solder joints were investigated in this study. The reaction and the resulting mechanical properties were both strongly dependent on the Pd concentration. When x was low (?0.2 wt.%), the reaction product at the Ni/Sn-Ag-Cu- xPd interface was a layer of (Cu,Ni)6Sn5. An increase of x to 0.3 wt.% produced one additional (Pd,Ni)Sn4 compound that was discontinuously scattered above the (Cu,Ni)6Sn5. When x was relatively high (0.5 wt.% to 1 wt.%), a dual layer of (Pd,Ni)Sn4-(Cu,Ni)6Sn5 developed with the reaction time. The results of the high-speed ball shear (HSBS) test showed that the mechanical strength of the Ni/Sn-3Ag-0.5Cu- xPd joints degraded with increasing x, especially when x reached a high level of ?0.3 wt.%. This degradation corresponded to the growth of (Pd,Ni)Sn4 at the interface, and joints easily failed along the boundaries of solder/(Pd,Ni)Sn4 and (Pd,Ni)Sn4/(Cu,Ni)6Sn5 in the HSBS test. The (Pd,Ni)Sn4-induced joint failure (Pd embrittlement) was alleviated by doping the solder with an appropriate amount of Cu. When the Cu concentration increased to 1 wt.% and the Pd concentration did not exceed 0.5 wt.%, the growth of (Pd,Ni)Sn4 could be thoroughly inhibited, thereby avoiding the occurrence of Pd embrittlement in the solder joints.

  16. 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)

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

    2010-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Chee, Sang-Soo; Lee, Jong-Hyun

    2014-05-01

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

  18. 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)

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

    2012-01-01

    The effect of Pd(P) thickness on the solid-solid reaction between Sn-3Ag-0.5Cu and Au/Pd(P)/Ni(P) at 180C 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.

  19. Depletion and phase transformation of a submicron Ni(P) film in the early stage of soldering reaction between Sn-Ag-Cu and Au/Pd(P)/Ni(P)/Cu

    NASA Astrophysics Data System (ADS)

    Ho, Cheng-En; Hsieh, Wan-Zhen; Yang, Tsung-Hsun

    2015-01-01

    The early stage of soldering reaction between Sn-3Ag-0.5Cu solder and ultrathin-Ni(P)-type Au/Pd(P)/Ni(P)/Cu pad was investigated by field-emission scanning electron microscopy (FE-SEM) in conjunction with field-emission electron probe microanalysis (FEEPMA) and high-resolution transmission electron microscopy (HRTEM). FE-SEM, FE-EPMA, and HRTEM investigations showed that Ni2SnP and Ni3P were the predominant P-containing intermetallic compounds (IMCs) in the soldering reaction and that their growth behaviors strongly depended on the depletion of Ni(P). The growth of Ni3P dominated over that of Ni2SnP in the early stage of soldering, whereas the Ni3P gradually transformed into Ni2SnP after Ni(P) depletion. This Ni(P)-depletion-induced Ni2SnP growth behavior is different from the reaction mechanisms reported in the literature. Detailed analyses of the microstructural evolution of the IMC during Ni(P) depletion were conducted, and a two-stage reaction mechanism was proposed to rationalize the unique IMC growth behavior.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Kyu; Duh, Jeng-Gong

    2014-11-01

    The combined effects on long-term reliability of isothermal aging and chemically balanced or unbalanced surface finish have been investigated for fine-pitch ball grid array packages with Sn-3.0Ag-0.5Cu (SAC305) (wt.%) and Sn-3.5Ag (SnAg) (wt.%) solder ball interconnects. Two different printed circuit board surface finishes were selected to compare the effects of chemically balanced and unbalanced structure interconnects with and without board-side Ni surface finish. NiAu/solder/Cu and NiAu/solder/NiAu interconnects were isothermally aged and thermally cycled to evaluate long-term thermal fatigue reliability. Weibull plots of the combined effects of each aging condition and each surface finish revealed lifetime for NiAu/SAC305/Cu was reduced by approximately 40% by aging at 150C; 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.

  2. Microstructures and Mechanical Properties of Sn-0.1Ag-0.7Cu-(Co, Ni, and Nd) Lead-Free Solders

    NASA Astrophysics Data System (ADS)

    Chen, Xu; Zhou, Jian; Xue, Feng; Bai, Jing; Yao, Yao

    2015-02-01

    The influences of minor alloying elements Co, Ni, and Nd on the microstructures and mechanical properties of Sn-0.1Ag-0.7Cu (SAC0107) solder were investigated. The results show that the microstructures of SAC0107 alloy mainly consisted of primary Sn-rich phases and eutectic phases composed of Ag3Sn and Cu6Sn5 phases dispersed in a Sn matrix. With Co or Ni additions, the amount of primary Sn-rich phase reduced and IMCs dispersed more uniformly in the Sn matrix. The elements of Co and Ni were concentrated in (Co x Cu1- x )6Sn5 and (Ni x Cu1- x )6Sn5 intermetallic compounds (IMCs), respectively, and they also entered the IMC layer between solder alloys and Cu substrate during soldering. Shear strength of the joints all increased by adding Co, Ni, and Nd elements. Different from the Co and Nd additions, the addition of the Ni element also markedly improved the tensile strength and elongation of SAC0107 alloys.

  3. Proposed power-function N-body potential for the fcc structured metals Ag, Au, Cu, Ni, Pd, and Pt

    SciTech Connect

    Li, J. H.; Kong, Y.; Guo, H. B.; Liang, S. H.; Liu, B. X.

    2007-09-01

    We propose, for the fcc structured Ag, Au, Cu, Ni, Pd, and Pt metals, an N-body potential with a simple power-function form, which significantly simplifies the fitting procedure and computation. The proposed potentials are able to correctly reproduce the lattice constants, cohesion energies, elastic constants, relative stabilities of different structures, formation energies of vacancy, and surface energies. In addition, the thermal properties, such as melting points and heat capacities, etc., are also satisfactorily determined from the proposed potentials. Moreover, the proposed potential is applied to calculate the trigonal and tetragonal paths between the fcc and bcc structures, and the calculated paths match well with those obtained from the first principles calculations.

  4. Deformation Behavior and Microstructure Evolution of the Cu-2Ni-0.5Si-0.15Ag Alloy During Hot Compression

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Volinsky, Alex A.; Xu, Qian-Qian; Chai, Zhe; Tian, Baohong; Liu, Ping; Tran, Hai T.

    2015-12-01

    Hot deformation behavior of the Cu-2Ni-0.5Si-0.15Ag alloy was investigated by hot compression tests using the Gleeble-1500D thermo-simulator in the 873 K to 1073 K (600 C to 800 C) temperatures range with the 0.01 to 5 s-1 strain rate. The flow stress strongly depends on the deformation parameters, including temperature and strain rate. The flow stress decreases with the deformation temperature and increases with the strain rate. The constitutive relationship between the peak stress, the strain rate, and the deformation temperature can be described by the Zener-Hollomon Z parameter in the hyperbolic sine function with the hot deformation activation energy of 316 kJ/mol. The dynamic recrystallization (DRX) is one of the important softening mechanisms of the Cu-2Ni-0.5Si-0.15Ag alloy during hot deformation. The DRX behavior of the Cu-2Ni-0.5Si-0.15Ag alloy is strongly affected by the Z parameter. Lower Z parameter leads to more adequate DRX proceeding.

  5. Deformation Behavior and Microstructure Evolution of the Cu-2Ni-0.5Si-0.15Ag Alloy During Hot Compression

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Volinsky, Alex A.; Xu, Qian-Qian; Chai, Zhe; Tian, Baohong; Liu, Ping; Tran, Hai T.

    2015-09-01

    Hot deformation behavior of the Cu-2Ni-0.5Si-0.15Ag alloy was investigated by hot compression tests using the Gleeble-1500D thermo-simulator in the 873 K to 1073 K (600 C to 800 C) temperatures range with the 0.01 to 5 s-1 strain rate. The flow stress strongly depends on the deformation parameters, including temperature and strain rate. The flow stress decreases with the deformation temperature and increases with the strain rate. The constitutive relationship between the peak stress, the strain rate, and the deformation temperature can be described by the Zener-Hollomon Z parameter in the hyperbolic sine function with the hot deformation activation energy of 316 kJ/mol. The dynamic recrystallization (DRX) is one of the important softening mechanisms of the Cu-2Ni-0.5Si-0.15Ag alloy during hot deformation. The DRX behavior of the Cu-2Ni-0.5Si-0.15Ag alloy is strongly affected by the Z parameter. Lower Z parameter leads to more adequate DRX proceeding.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  8. Dispersed fluorescence spectroscopy of AlNi, NiAu, and PtCu Jacqueline C. Fabbi

    E-print Network

    Morse, Michael D.

    have been rather well studied.2,1518,2127 In the coinage metals Cu, Ag, Au , the d orbitals are bothDispersed fluorescence spectroscopy of AlNi, NiAu, and PtCu Jacqueline C. Fabbi Department; accepted 24 February 2003 Dispersed fluorescence studies of AlNi, NiAu, and PtCu have been performed

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

    PubMed

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

    2014-10-01

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

  10. 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)

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

    2012-12-01

    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 260C. 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.

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

    SciTech Connect

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

    2014-12-01

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

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

    PubMed

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

    2014-11-01

    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

  13. Investigation of electrochemical migration on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy in HNO3 solution

    NASA Astrophysics Data System (ADS)

    Sarveswaran, C.; Othman, N. K.; Ali, M. Yusuf Tura; Ani, F. Che; Samsudin, Z.

    2015-09-01

    Current issue in lead-free solder in term of its reliability is still under investigation. This high impact research attempts to investigate the electrochemical migration (ECM) on Sn-0.7Cu-0.3Ag-0.03P-0.005Ni solder alloy by Water Drop Test (WDT) in different concentration of HNO3 solution. The concentration of HNO3 solution used in this research was 0.05, 0.10, 0.50 and 1M. Optical Microscope (OM), Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-Ray Analysis (EDX) were carried out in order to analysis the ECM behavior based on the growth of dendrite formation after WDT. In general, the results demonstrated that dendrite growth is faster in higher concentration compared with low concentration of HNO3. The concentration of HNO3 solution used has a strong correlation with Mean-Time-To-Failure (MTTF). As the concentration of HNO3 increases, the MTTF value decreases. Based on the MTTF results the solder alloy in 1M HNO3 solution is most susceptible to ECM. SnO2 forms as a corrosion by-product in the samples proved by EDX analysis. The solder alloy poses a high reliability risk in microelectronic devices during operation in 1M HNO3 solution.

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

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audtat, Andreas

    2012-11-01

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

  15. Resonant two-photon ionization spectroscopy of coinage metal trimers: Cu,Ag, Cu,Au, and CuAgAu

    E-print Network

    Morse, Michael D.

    Resonant two-photon ionization spectroscopy of coinage metal trimers: Cu,Ag, Cu,Au, and Cu-cooled coinage metal triatomic molecules Cu, Ag, Cu, Au, and CuAgAu have been investigated using resonant two. For Cu, Ag, 47 vibrational bands have been assigned within the `2-2 system. The upper states

  16. DSPRU Project at NSU: Evolution of Basic, Mantle-crust Granitoid Ore-magmatic Systems Resulting in Pt-Cu-Ni, Cu-Mo-porphiric and Epithermal Au-Ag Ore-bearing Mineralization.

    NASA Astrophysics Data System (ADS)

    Rakhmenkulova, I.; Sharapov, V.; Zhitova, L.

    2006-05-01

    Education and Human Resources are one of the most important priorities of the Russian Government policy nowadays. This work covers the principally new Project of the Ministry for Russian Science and Education: 'Development of Scientific Potential for Russian Universities' (DSPRU). The purposes of the Project are: 1) to involve university students to research in most urgent problems of fundamental science; 2) to enhance the professional development of Russian educators; 3) to interest the most perspective researches in education process at Russian universities; 4) to broaden the educational process involving to the Project foreign students, educators and researchers. All the State Universities in Russia could participate in the Project (with the exception of Moscow State University, whose employees were the Project experts). At Novosibirsk State University (NSU) research teams of 13 Departments applied for the Project. Only 5 Projects turned out to be successful. From the Department of Geology and Geophysics 9 Projects were applied and the only one won: 'Evolution of Basic, Mantle-crust Granitoid Ore-magmatic Systems Resulting in Pt-Cu-Ni, Cu-Mo-porphiric and Epithermal Au-Ag Ore-bearing Mineralization'. The team of the above-mentioned Project includes: - nine university educators - five researchers from the Institutes of Siberian Branch of Russian Academy of Sciences - four PhD students - eight undergraduate students. The expecting results of the Project are: 1) obtaining new data for natural objects covered by the Project (Siberia, Mongolia, China, South Africa, Morocco); 2) creation of mathematical models of evolution for fluid ore-magmatic systems of various geochemical character and productivity; 3) improving the education process at the Department of Geology and Geophysics of NSU (creation of new courses and publications, professional development of the educators, participation of students and young researchers in scientific conferences). The work was supported by the Ministry for Russian Science and Education, Grant DSP.2.1.1.702.

  17. Direct measurements of irradiation-induced creep in micropillars of amorphous Cu{sub 56}Ti{sub 38}Ag{sub 6}, Zr{sub 52}Ni{sub 48}, Si, and SiO{sub 2}

    SciTech Connect

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

    2015-01-14

    We report in situ measurements of irradiation-induced creep on amorphous (a-) Cu{sub 56}Ti{sub 38}Ag{sub 6}, Zr{sub 52}Ni{sub 48}, Si, and SiO{sub 2}. Micropillars 1??m in diameter and 2??m in height were irradiated with ?2?MeV heavy ions during uniaxial compression at room temperature. The creep measurements were performed using a custom mechanical testing apparatus utilizing a nanopositioner, a silicon beam transducer, and an interferometric laser displacement sensor. We observed Newtonian flow in all tested materials. For a-Cu{sub 56}Ti{sub 38}Ag{sub 6}, a-Zr{sub 52}Ni{sub 48}, a-Si, and Kr{sup +} irradiated a-SiO{sub 2} irradiation-induced fluidities were found to be nearly the same, ?3?GPa{sup ?1} dpa{sup ?1}, whereas for Ne{sup +} irradiated a-SiO{sub 2} the fluidity was much higher, 83?GPa{sup ?1} dpa{sup ?1}. A fluidity of 3?GPa{sup ?1} dpa{sup ?1} can be explained by point-defect mediated plastic flow induced by nuclear collisions. The fluidity of a-SiO{sub 2} can also be explained by this model when nuclear stopping dominates the energy loss, but when the electronic stopping exceeds 1?keV/nm, stress relaxation in thermal spikes also contributes to the fluidity.

  18. Magnetic properties of Ni and Cu-Ni nanoparticles

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    SciTech Connect

    Kim, Kwang Joo.

    1990-10-17

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

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

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Audtat, Andreas

    2015-08-01

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

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

    PubMed

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

    2012-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

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

    SciTech Connect

    Geretschlaeger, M.; Benka, O.

    1986-08-01

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

  4. Low-temperature solid state bonding method based on surface Cu-Ni alloying microcones

    NASA Astrophysics Data System (ADS)

    Lu, Qin; Chen, Zhuo; Zhang, Wenjing; Hu, Anmin; Li, Ming

    2013-03-01

    A low-temperature solid state bonding method based on surface Cu-Ni alloying microcones for potential application in 3D integration is introduced. Surface Cu-Ni alloying microcones were fabricated by electroless deposition and bonded with Sn-3.0Ag-0.5Cu (wt.%) solder at 190 C (solid state) in ambient air. Microscopic observation showed that Cu-Ni microcones inserted into the soft solder effectively and a thin intermetallic compound layer formed along the bonding interface. The bonding joint strength was measured and the result showed that it was higher than that of reflow soldering.

  5. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    SciTech Connect

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V. Stephen, A.

    2014-01-28

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  7. Intermetallic Growth Studies on Sn-Ag-Cu Lead-Free Solder Joints

    E-print Network

    Zhou, Wei

    Intermetallic Growth Studies on Sn-Ag-Cu Lead-Free Solder Joints JOHN H.L. PANG,1,2 LUHUA XU,1 X (IMC) growth behavior plays an important role in solder joint reliability of electronic packaging solders and nickel/gold (Ni/Au) surface finish on BGA solder joint specimen is reported. Digital imaging

  8. Synthesis of Cu-Ag@Ag particles using hyperbranched polyester as template

    NASA Astrophysics Data System (ADS)

    Han, Wen-Song

    2015-07-01

    In this manuscript, the third-generation hyperbranched polyester was synthesized with 2, 2-dimethylol propionic acid as AB2 monomer and pentaerythrite as core molecule by using step by step polymerization process at first. Then, the Cu-Ag particles were prepared by co-reduction of silver nitrate and copper nitrate with ascorbic acid in the aqueous solution using hyperbranched polyester as template. Finally, the Cu-Ag@Ag particles were prepared by coating silver on the surface of Cu-Ag particles by reduction of silver nitrate. The synthesized hyperbranched polyester and Cu-Ag@Ag particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-vis spectra, x-ray diffraction, Laser light scattering, thermogravimetric analysis (TGA) and SEM. UV-vis spectra results showed that the Cu-Ag@Ag particles had a strong absorption band at around 420 nm. Laser light scattering and SEM studies confirmed that the most frequent particle sizes of Cu-Ag@Ag particles were 1.2 um. TGA results indicated that the Cu-Ag@Ag particles had good thermal stability. [Figure not available: see fulltext.

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

    SciTech Connect

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

    2014-01-14

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

  10. Vibrationally resolved photoelectron imaging of Cu2H- and AgCuH- and theoretical calculations.

    PubMed

    Xie, Hua; Li, Xiaoyi; Zhao, Lijuan; Liu, Zhiling; Qin, Zhengbo; Wu, Xia; Tang, Zichao; Xing, Xiaopeng

    2013-02-28

    Vibrationally resolved photoelectron spectra have been obtained for Cu(2)H(-) and AgCuH(-) using photoelectron imaging at 355 nm. Two transition bands X and A are observed for each spectrum. The X bands in both spectra show the vibration progressions of the Cu-H stretching mode and the broad peaks of these progressions indicate significant structural changes from Cu(2)H(-) and AgCuH(-) to their neutral ground states. The A bands in the spectra of Cu(2)H(-) and CuAgH(-) show stretching progressions of Cu-Cu and Ag-Cu, respectively. The contours of these two progressions are pretty narrow, indicating relatively small structural changes from Cu(2)H(-) and AgCuH(-) to their neutral excited states. Calculations based on density functional theory indicate that the ground states of Cu(2)H(-) and AgCuH(-) and the first excited states of their neutrals are linear, whereas their neutral ground states are bent. The photoelectron detachment energies and vibrational frequencies from these calculations are in good agreement with the experimental observations. Especially, the theoretical predication of linear structures for the anions and the neutral excited states are supported by the spectral features of A bands, in which the bending modes are inactive. Comparisons among the vertical detachment energies of Cu(2)H(-), AgCuH(-), and their analogs help to elucidate electronic characteristics of coinage metal elements and hydrogen in small clusters. PMID:23388039

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  12. Synthesis and thermodynamics of Ag-Cu nanoparticles.

    PubMed

    Delsante, Simona; Borzone, Gabriella; Novakovic, Rada; Piazza, Daniele; Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Pilloni, Martina; Ennas, Guido

    2015-11-14

    Metallic silver, copper, and Ag-Cu nanoparticles (NPs) have been produced by a chemical reduction method. The obtained nanoparticles were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). A side-segregated configuration was observed for the one-pot synthesized Ag-Cu NPs, and the melting temperature depression of about 14 C was found by differential scanning calorimetry (DSC). A comparison between the new experimental data, the literature data on Ag-Cu bimetallic NPs and the corresponding theoretical values obtained from the Ag-Cu nano-sized phase diagram was done, whereas the melting behaviour of Ag and Cu metal nanoparticles was discussed in the framework of the liquid layer model (LLM). PMID:26112754

  13. Cu and Ni solubility in high-temperature aqueous fluids

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  14. Surface Segregation in Cu-Ni Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

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

  15. Infrared Brazing Ti50Ni50 and Invar Using Ag-Based Filler Foils

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

  16. Origin of transverse magnetization in epitaxial Cu/Ni/Cu nanowire arrays

    E-print Network

    Ciria, M.

    The patterning-induced changes in the magnetic anisotropy and hysteresis of epitaxial (100)-oriented Cu/Ni(9, 10, 15 nm)/Cu planar nanowires have been quantified. When the Ni films are patterned into lines, strain relaxation ...

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  18. Effect of Process and Service Conditions on TLP-Bonded Components with (Ag,Ni-)Sn Interlayer Combinations

    NASA Astrophysics Data System (ADS)

    Lis, Adrian; Leinenbach, Christian

    2015-11-01

    Transient liquid phase (TLP) bonding of Cu substrates was conducted with interlayer systems with the stacking sequences Ag-Sn-Ag (samples A), Ni-Sn-Ni (samples B), and combined Ag-Sn-Ni (samples C). Because of the low mismatch of the coefficients of thermal expansion, characteristics of the TLP process and mechanical and thermal behavior of TLP-bonded samples could be investigated without interference from thermally induced residual stresses. An ideal process temperature of 300C, at which the number of pores was lowest, was identified for all three layer systems. It was verified experimentally that formation of pores resulted from volume contraction during isothermal solidification of liquid Sn into intermetallic compounds (IMC). Temperature and interlayer-dependent growth characteristics of IMC accounted for the increasing size and number of defects with increasing process temperature and for different defect positions. The shear strength was measured to be 60.4 MPa, 27.4 MPa, and 40.7 MPa for samples A, B, and C, respectively, and ductile fracture features were observed for Ag3Sn IMC compared with the purely brittle behavior of Ni3Sn4 IMC. Excellent thermal stability for all three layer systems was confirmed during long-term annealing at 200C for up to 1200 h, whereas at 300C the microstructure was driven toward Ag-Sn solid solution, accompanied by Cu diffusion from the substrate along grain boundaries and Cu3Sn IMC formation (A), and toward Ni-rich IMC phases (B). Combined IMC interlayers (C) tended to be transformed into Ni-based IMC when held at 300C; intermixing into (Ni,Cu)3Sn was accompanied by pore formation.

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

    NASA Astrophysics Data System (ADS)

    Saalmann, Kerstin; Laine, Eevaliisa

    2015-04-01

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

  20. Magnetic anisotropy of epitaxial Cu/Ni/Cu nanolines

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

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

  1. Les minralisations Cu_(Ni_Bi_U_Au_Ag) d'Ifri (district du Haut Seksaoua, Maroc) : apport de l'tude texturale au dbat syngense versus pigenseThe Cu_(Ni_Bi_U_Au_Ag) mineralization of Ifri ('Haut Seksaoua' district, Morocco): contribution of a textural study to the discussion syngenetic versus epigenetic

    NASA Astrophysics Data System (ADS)

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

    2003-11-01

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

  2. Preparation of Ni/Cu composite nanowires

    PubMed Central

    Wang, Hu; Li, Xiaoyu; Li, Ming; Xie, Kenan

    2015-01-01

    Summary Ni/Cu composite nanowires were synthesized in an aqueous solution for the first time. The synthetic process consisted of two steps. Firstly, pure nickel nanowires were prepared through chemical reduction in solution under a magnetic field. Secondly, copper was reduced on the surface of the nickel nanowires, during which Ni/Cu composite nanowires with an average length of 80 m and diameter of about 200 nm were synthesized. The products were characterized by XRD, SEM and TEM. The method has notable advantages: It is template-free, inexpensive, easy-to-operate, and it only needs a short reaction time, which makes it suitable for large-scale preparation. PMID:26171302

  3. Perpendicularly magnetized spin filtering Cu/Ni multilayers

    SciTech Connect

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

    2014-01-20

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

  4. Growth of Cu-Ni Nanostructures on Cu(111): A Molecular Dynamic Study

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2014-03-01

    We have studied energetics and growth mechanisms on nanostructures both using molecular dynamic simulations and total energy calculations to understand the nature of Ni and Cu growth on Cu(111) surface. The interactions between the atoms in the systems are defined using a many-body type potential developed for Cu-Ni alloys within the EAM formalism. Our simulations on Cu-Ni systems with mono/double-layer Ni islands on Cu(111) show that Cu atoms could migrate to Ni islands and decorate the bottom and even the upper layer of Ni islands. Furthermore, we find that the formation of the islands is governed by the nature of the decoration process. From total energy calculations we also discuss the governing diffusion mechanisms for the formation of Cu-Ni islands on Cu(111).

  5. Unusual site preference of Cu in Ni2-based Heusler alloys Ni2CuSb and Ni2CuSn

    NASA Astrophysics Data System (ADS)

    Liu, Bohua; Luo, Hongzhi; Xin, Yuepeng; Zhang, Yujie; Meng, Fanbin; Liu, Heyan; Liu, Enke; Wang, Wenhong; Wu, Guangheng

    2015-11-01

    The site preference of Cu does not follow the usual valence electrons rule in Ni2-based Heusler alloys Ni2CuSn and Ni2CuSb. The phase stabilities of three possible structures, namely L21, XA and L21B, have been compared. Among them L21 has the lowest total energy and is preferable, while L21B has the highest energy. The energy differences between L21 and the other two structures are quite large. The high phase stability of the L21 structure is mainly related to the strong hybridization between the d states of Cu, Ni and the low N(EF). Single phase, highly-ordered Ni2CuSn and Ni2CuSb samples have been prepared experimentally. The XRD patterns suggest that Ni2CuSn and Ni2CuSb do crystallize in the L21 structure, agreeing with the theoretical prediction. Finally, both of them have a paramagnetic ground state.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  7. Heat-induced spinodal decomposition of Ag-Cu nanoparticles.

    PubMed

    Sopouek, Ji?; Zoba?, Ond?ej; Burk, Ji?; Roupcov, Pavla; Vykoukal, Vt; Bro, Pavel; Pinkas, Ji?; V?et'l, Jan

    2015-11-14

    Solvothermal synthesis was used for Ag-Cu nanoparticle (NP) preparation from metallo-organic precursors. The detailed NP characterization was performed to obtain information about nanoparticle microstructure and both phase and chemical compositions. The resulting nanoparticles exhibited chemical composition inside a FCC_Ag + FCC_Cu two-phase region. The microstructure study was performed by various methods of electron microscopy including high-resolution transmission electron microscopy (HRTEM) at an atomic scale. The HRTEM and X-ray diffraction studies showed that the prepared nanoparticles form the face centred cubic (FCC) crystal lattice where the silver atoms are randomly mixed with copper. The CALPHAD approach was used for predicting the phase diagram of the Ag-Cu system in both macro- and nano-scales. The predicted spinodal decomposition of the metastable Ag-Cu nanoparticles was experimentally induced by heating on an X-ray powder diffractometer (HT XRD). The nucleation of the Cu-rich phase was detected and its growth was studied. Changes in the Ag-rich phase were observed in situ by X-ray diffraction under vacuum. The heat treatment was conducted at different maximum temperatures up to 450 C and the resulting particle product was analysed. The experiments were complemented by differential scanning calorimetry (DSC) measurements up to liquidus temperature. The start temperatures of the spinodal phase transformation and particle aggregation were evaluated. PMID:25929324

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

    DOEpatents

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

    1996-06-18

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

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

    DOEpatents

    Anderson, Iver E. (Ames, IA); Yost, Frederick G. (Cedar Crest, NM); Smith, John F. (Ames, IA); Miller, Chad M. (Ames, IA); Terpstra, Robert L. (Ames, IA)

    1996-06-18

    A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217.degree. 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.degree. C. above the eutectic melting temperature).

  10. DFT study of Cu and Ag clusters inside C60

    NASA Astrophysics Data System (ADS)

    Dhiman, Shobhna; Kumar, Ranjan; Dharamvir, Keya

    2015-11-01

    Using density functional theory an attempt has been made to explore the possibility of trapping Cu and Ag clusters inside C60. We found that a maximum of 9 Cu atoms and 8 Ag atoms can be encapsulated in a C60 molecule without distorting the cage. The parameters like BE/dopant atom, ionization potential, electron affinity, average diameter, HOMO-LUMO gap and potential barrier were calculated for both endohedral fullerenes and comparison was made with C60 molecule. Mulliken charge analysis shows a charge transfer from metal atoms to the cage. Indeed the physical properties of C60 are modified with doping.

  11. Synthesis of Cu core Ag shell nanoparticles using chemical reduction method

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2014-10-29

    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

  13. Facile Preparation of Ag/NiO Composite Nanosheets and Their Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Shi, Cui-E.; Pan, Lu; Wang, Cheng-Run; He, Yi; Wu, Yong-Feng; Xue, Sai-Sai

    2015-08-01

    Sheet-like precursors of NiO and Ag/NiO with different Ag contents were synthesized by a facile and easily controlled hydrothermal method. The NiO and Ag/NiO composite nanosheets were prepared by calcination of the corresponding precursors at 400C for 3 h. The as-synthesized samples were characterized by thermogravimetric analysis, x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The antibacterial activity of NiO and Ag/NiO composites to several gram-positive and gram-negative bacteria was examined. Results showed that NiO nanosheets hardly exhibited antibacterial activity; however, Ag/NiO composites displayed higher activity even with low Ag content.

  14. Interfacial reactions between sapphire and Ag-Cu-Ti-based active braze alloy

    E-print Network

    Ali, Majed; Knowles, Kevin M.; Mallinson, Phillip M.; Fernie, John A.

    2015-01-01

    The interfacial reactions between two commercially available AgCuTi-based active braze alloys and sapphire have been studied. In separate experiments, Ag 35.3Cu1.8Ti wt.% and Ag26.7Cu4.5Ti wt.% alloys have been sandwiched between pieces of R...

  15. Tensile properties and thermal shock reliability of Sn-Ag-Cu solder joint with indium addition.

    PubMed

    Yu, A-Mi; Jang, Jae-Won; Lee, Jong-Hyun; Kim, Jun-Ki; Kim, Mok-Soon

    2012-04-01

    The thermal shock reliability and tensile properties of a newly developed quaternary Sn-1.2Ag-0.5Cu-0.4In (wt%) solder alloy were investigated and compared to those of ternary Sn-Ag-Cu based Pb-free solder alloys. It was revealed that the Sn-1.2Ag-0.5Cu-0.4In solder alloy shows better thermal shock reliability compared to the Sn-1.0Ag-0.5Cu and Sn-3.0Ag-0.5Cu solder alloys. The quaternary alloy has higher strength than Sn-1.0Ag-0.5Cu alloy, and higher elongation than Sn-3.0Ag-0.5Cu alloy. It was also revealed that the addition of indium promotes the formation of Ag3(Sn, In) phase in the solder joint during reflow process. PMID:22849189

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  17. Co Effects upon Intermetallics Growth Kinetics in Sn-Cu-Co/Ni and Sn-Cu-Co/Cu Couples

    NASA Astrophysics Data System (ADS)

    Tseng, Yan-lun; Chang, Ya-chun; Chen, Chih-chi

    2015-01-01

    The effects of minor Co additions in Sn-Cu solders on their interfacial reactions with Ni and Cu substrates were investigated. The growth rate constants and activation energy obtained in aging tests of Sn-0.7wt.%Cu- xCo/Ni and Sn-0.7wt.%Cu- xCo/Cu with x = 0.01, 0.04, 0.1, 0.5, and 1 wt.% have been determined. In Sn-0.7wt.%Cu- xCo/Cu couples, the intermetallics are the Cu6Sn5 and Cu3Sn phases. The total thickness of the reaction phase increases with the amount of Co added. Co facilitates the growth of the Cu6Sn5 phase. In Sn-0.7wt.%Cu- xCo/Ni couples, the intermetallics are either the Cu6Sn5 phase ( x = 0.01 wt.%) or both the Cu6Sn5 and Ni3Sn4 phases ( x = 0.04-1 wt.%). The total thickness of the reaction phase decreases as the amount of added Co increases. Co facilitates the growth of the Ni3Sn4 phase and thus inhibits formation of the Cu6Sn5 phase. Sn-Cu/Ni and Sn-Cu/Cu are very important soldering joints in electronic packaging, and Co is a widely-used additive in the solders. The kinetic data determined in this study are needed to assess the reliability of Sn-Cu/Ni and Sn-Cu/Cu soldering joints.

  18. Diffusion of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces

    NASA Astrophysics Data System (ADS)

    Mi?kowski, Marcin; Za?uska-Kotur, Magdalena A.

    2015-12-01

    Diffusion of Cu adatoms and dimers on Cu(111) and Ag(111) surfaces is analyzed based on ab initio surface potentials. Single adatom diffusion is compared with dimer diffusion on both surfaces. Surface geometry makes the adatoms jump alternately between two states in the same way in both systems, whereas dimers undergo more complex diffusion process that combines translational and rotational motion. Small difference in the surface lattice constant between Cu and Ag crystals results in a completely different energy landscape for dimer jumps. As an effect the character of diffusion process changes. Homogeneous Cu dimer diffusion is more difficult and dimers rather rotate within single surface cell, whereas diffusion over Ag surface is faster and happens more smoothly. The temperature dependence of diffusion coefficient and its parameters: energy barrier and prefactor is calculated and compared for both surfaces.

  19. Characterization of Electrodeposited Nanoporous Ni and NiCu Films

    NASA Astrophysics Data System (ADS)

    Koboski, Kyla; Hampton, Jennifer

    2013-03-01

    Nanoporous thin films are interesting candidates to catalyze certain reactions because of their large surface areas. This project focuses on the deposition of Ni and NiCu thin films on a Au substrate and further explores the catalysis of the hydrogen evolution reaction (HER). Depositions are created using controlled potential electrolysis. Samples are then dealloyed using linear sweep voltammetry. Before and after the dealloying, all the samples are characterized using multiple techniques. Electrochemical capacitance measurements allow comparisons of sample roughness. HER measurements characterize the reactivity of the sample with respect to the specific catalytic reaction. The Tafel equation is fit to the data to obtain information about the kinetics of the HER of the samples. Other methods for characterizing the samples include scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The use of SEM allows images to be taken of the deposition to determine the change in the structure pre- and post- dealloy of the sample. EDS allows the elemental composition of the deposition to be determined before and after the dealloy stage. This material is based upon work supported by the National Science Foundation under RUI Grant DMR-1104725, MRI Grant CHE-1126462, MRI Grant CHE-0959282, and ARI grant PHY-0963317.

  20. Atomistic simulation of Cu-Ni precipitates hardening in ?-iron

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

    Li, Xiaona Ding, Jianxin; Wang, Miao; Dong, Chuang; Chu, Jinn P.

    2014-11-01

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

  2. Epitaxial growth of Cu on Ag(1 1 1) studied with angle-resolved photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Luh, Dah-An; Huang, Chih-Hao; Cheng, Cheng-Maw; Tsuei, Ku-Ding

    2015-11-01

    The growth of Cu on Ag(1 1 1) under varied growth conditions was investigated with angle-resolved photoemission spectra. The evolution of Cu/Ag(1 1 1) during annealing was characterized on monitoring its surface states. The surface morphology of a Cu film on Ag(1 1 1) depends on the temperature and the Cu coverage. Islands or crystalline films develop when Cu is deposited at ?300 K. Defects in the Cu films penetrate deeply into the Ag(1 1 1) substrate and expose the Ag(1 1 1) surface. The deposition of Cu at a low temperature results in disordered films. On annealing, the films become ordered with defects. Our results show the segregation of Ag on the Cu surface, which occurs at 300 K and becomes accelerated significantly at ?380 K. After being annealed above 430 K, all islands and films of Cu are fully covered with Ag, showing a (9 9) reconstruction. Our results indicate also that the segregation of Ag on the Cu surface occurs only after the Ag(1 1 1) surface is exposed, indicating that Ag atoms migrate to the Cu(1 1 1) surface, not through bulk Cu, but along the walls of the islands and the defects in the films.

  3. Ab initio vibrational dynamics of Ag27Cu7 nanoalloy.

    NASA Astrophysics Data System (ADS)

    Alcantara Ortigoza, Marisol; Heid, Rolf; Bohnen, Klaus P.; Rahman, Talat S.

    2009-03-01

    We have carried out calculations of the vibrational dynamics of the 34-atom nanoalloy, Ag27Cu7, using density functional perturbation theory, which furnishes a powerful and reliable method to asses the linear response of the charge density to ionic perturbations. We find that the D5h core-shell structure of Ag27Cu7 [1,2] is dynamically stable, since all modes have non-zero frequencies affirming that the structure does not surrender itself to structural transitions as a result of the small perturbations in the charge density led by vibrations. The phonons of Ag27Cu7 range from 2.6 to 28.5 meV and are relatively evenly distributed. There are, however, three 3.0 meV gaps between 2.8-5.6, 15.0-18.7, and 23.6-26.8 meV. In modes whose frequency is below 7.0 meV, Ag atoms participate the most while Cu atoms show a very small displacement. The opposite is true for four modes whose frequency is above 24 meV. We present the displacement patterns of the main modes and find the mode with highest energy to be a radial breathing mode of Cu atoms with respect to the center of the cluster. [1] G. Rossi et al., PRL. 93, 105503 (2004), [2] M. Alc'antara Ortigoza and T. S. Rahman, PRB 77, 195404 (2008). Work supported in part by U.S. DOE under Grant DE-FG02-07ER46354.

  4. Core level spectra of disordered Cu-Ni alloys

    NASA Astrophysics Data System (ADS)

    Medicherla, V. R. R.; Parida, S. K.; Bag, Pallab; Rawat, Rajeev; Shripathi, T.; Sahadev, Nishaina; Biswas, Deepnarayan; Adhikary, Ganesh; Maiti, K.

    2012-07-01

    We investigate the core levels of Cu1-xNix (x=0, 0.1, 0.3, 0.5, 0.7, 0.9, 1.0) alloys using high resolution photoemission spectroscopy. The Cu 2p core level exhibits a gradual shift to lower binding energy with increase in Ni concentration. The maximum core level shift (CLS) observed for x=0.9 is about 0.35 eV. The observed CLS show a linear dependence on Ni concentration and are in qualitative agreement with the non-magnetic calculations performed on Cu-Ni alloy system under complete screening picture by Olovsson et. al.

  5. MD simulation of nanoindentation on (001) and (111) surfaces of Ag-Ni multilayers

    NASA Astrophysics Data System (ADS)

    Zhao, Yinbo; Peng, Xianghe; Fu, Tao; Sun, Rong; Feng, Chao; Wang, Zhongchang

    2015-11-01

    We perform MD simulations of the nanoindentation on (001) and (111) surfaces of Ag-Ni multilayers with different modulation periods, and find that both the hardness and maximum force increase with the increase of modulation period, in agreement with the inverse Hall-Petch relation. A prismatic partial dislocation loop is observed in the Ni(111)/Ag(111) sample when the modulation period is relatively large. We also find that misfit dislocation network shows a square shape for the Ni(111)/Ag(111) interface, while a triangle shape for the Ni(001)/Ag(001) interface. The pyramidal defect zones are also observed in Ni(001)/Ag(001) sample, while the intersecting stacking faults are observed in Ni(111)/Ag(111) sample after dislocation traversing interface. The results offer insights into the nanoindentation behaviors in metallic multilayers, which should be important for clarifying strengthening mechanism in many other multilayers.

  6. Quaternary PtMnCuX/C (X = Fe, Co, Ni, and Sn) and PtMnMoX/C (X = Fe, Co, Ni, Cu and Sn) alloys catalysts: Synthesis, characterization and activity towards ethanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Ammam, Malika; Easton, E. Bradley

    2012-10-01

    In this account, two series of quaternary PtMnCuX/C (X = Fe, Co, Ni, and Sn) and PtMnMoX/C (X = Fe, Co, Ni, Cu and Sn) alloys catalysts have been synthesized and characterized by ICP, XRD, XPS, TEM and cyclic voltammetry. XRD spectra of each series illustrated that PtMnCuX/C (X = Fe, Co and Ni) and PtMnMoX/C (X = Fe, Co, Ni and Cu) alloys have been formed without significant free Mn, Cu, Mo or X co-catalysts. For PtMnCuSn/C and PtMnMoSn/C, in addition to alloy formation, significant free Sn-oxides are present in each catalyst. Cyclic voltammetry and chronoamperometry revealed that all quaternary showed superior electrocatalytic activity towards ethanol oxidation compared to the ternary precursor. Also, shift of the onset potential of ethanol oxidation towards less positive values were also recorded with the quaternary alloys, demonstrating a facilitated oxidation with the quaternary alloys compared to ternary alloy precursor. The magnitude of the gain in potential depend on the alloy composition and PtMnMoSn/C was found to be the best of all synthetized quaternary alloys with an onset potential of ethanol oxidation of only 0.059 V vs. Ag/AgCl.

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

    SciTech Connect

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

    2010-06-09

    Magnetic domain evolution at the spin reorientation transition (SRT) of (Fe/Ni)/Cu/Ni/Cu(001) is investigated using photoemission electron microscopy. While the (Fe/Ni) layer exhibits the SRT, the interlayer coupling of the perpendicularly magnetized Ni layer to the (Fe/Ni) layer serves as a virtual perpendicular magnetic field exerted on the (Fe/Ni) layer. We find that the perpendicular virtual magnetic field breaks the up-down symmetry of the (Fe/Ni) stripe domains to induce a net magnetization in the normal direction of the film. Moreover, as the virtual magnetic field increases to exceed a critical field, the stripe domain phase evolves into a bubble domain phase. Although the critical field depends on the Fe film thickness, we show that the area fraction of the minority domain exhibits a universal value that determines the stripe-to-bubble phase transition.

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

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

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

  9. Preparation of high-permeability NiCuZn ferrite*

    PubMed Central

    Hu, Jun; Yan, Mi

    2005-01-01

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

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

    SciTech Connect

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

    2015-05-07

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

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

    SciTech Connect

    Mukherjee, S. K.; Sinha, M. K.; Pathak, B.; Rout, S. K.; Barhai, P. K.

    2009-12-01

    This paper deals with the development of nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples (TFTCs) by using ion-assisted anodic vacuum arc deposition technique. The crystallographic structure and surface morphology of individual layer films have been studied by x-ray diffraction and scanning electron microscopy, respectively. The resistivity, temperature coefficient of resistance, and thermoelectric power of as deposited and annealed films have been measured. The observed departure of these transport parameters from their respective bulk values can be understood in terms of intrinsic scattering due to enhanced crystallite boundaries. From the measured values of thermoelectric power and the corresponding temperature coefficient of resistance of annealed Cu, Ni, and Fe films, the calculated values of log derivative of the mean free path of conduction electrons at the Fermi surface with respect to energy (U) are found to be -0.51, 3.22, and -8.39, respectively. The thermoelectric response of annealed Cu-Ni and Fe-Ni TFTCs has been studied up to a maximum temperature difference of 300 deg. C. Reproducibility of TFTCs has been examined in terms of the standard deviation in thermoelectric response of 16 test samples for each pair. Cu-Ni and Fe-Ni TFTCs agree well with their wire thermocouple equivalents. The thermoelectric power values of Cu-Ni and Fe-Ni TFTCs at 300 deg. C are found to be 0.0178 and 0.0279 mV/ deg. C, respectively.

  12. A novel multifunctional NiTi/Ag hierarchical composite

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  14. Carboxylic acid reduction over silica supported Cu, Ni and Cu2In, Ni2In catalysts.

    PubMed

    Onyestyk, Gyrgy; Harnos, Szabolcs

    2014-01-01

    Hydroconversion of caprylic acid as model compound was studied in a flow-through fixed-bed reactor at 21 bar total pressure and 240-360 C reaction temperature over various hydrogenating active phases: pure metal (Cu, Ni) and intermetallic compound (Cu(2)In, Ni(2)In) nanoparticles. Different silicas produced by dissimilar methods and a commercial gama-alumina were compared as appropriate supports. Catalyst precursors were activated in reducing H(2) flow at 21 bar and 450 C as routine pretreatment. Catalysts of high activity and selectivity for alcohol production can be obtained by varying the supports, the main metals and their indium modified bimetallic forms. Diversity of catalytic behavior reflects the complexity of the surface reactions. Caprylic alcohol formation was substantiated to proceed through caprylic aldehyde intermediates, however it can be also dehydrated to dicaprylic ether or octenes over alumina support. Silica supports, especially a less compact variant seem to be more inert for side reactions than alumina. Different morphology of studied silicas can highly influence the catalytic performances taking place over different metal particles. PMID:25551722

  15. Modified Ni-Cu catalysts for ethanol steam reforming

    SciTech Connect

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

    2013-11-13

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

  16. Diffusion bonding of commercially pure Ni using Cu interlayer

    SciTech Connect

    Rahman, A.H.M.E. Cavalli, M.N.

    2012-07-15

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

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

    SciTech Connect

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

    2009-06-08

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

  18. Interplay between structural symmetry and magnetism in Ag-Cu

    NASA Astrophysics Data System (ADS)

    Yen, Tsung-Wen; Lai, S. K.

    2016-01-01

    We present first-principles theoretical calculations of the magnetic properties of bimetallic clusters Ag-Cu. The calculations proceeded by combining a previously developed state-of-the-art optimization algorithm (P.J. Hsu, S.K. Lai, J. Chem. Phys. 124 (2006) 0447110) with an empirical potential and applied this numerical scheme to determine first the lowest energy structures of pure clusters Ag38 and Cu38, and also their different atomic compositions AgnCu38-n for n=1,2,,37. Then, we carried out the Kohn-Sham spin unrestricted density functional theory calculations on the optimized atomic structures obtained in the preceding step. Given the minimized structures from the first step as input configurations, the results of these re-optimized structures by full density functional theory calculations yield more refined electronic and atomic structures. A thorough comparison of the structural differences between these two sets of atomic geometries, one from using an empirical potential in which the electronic degrees of freedom were included approximately and another from subsequent minimization using the spin unrestricted density functional theory, sheds light on how the electronic charges disperse near atoms in clusters AgnCu38-n, and hence the distributions of electronic spin and charge densities at re-optimized sites of the cluster. These data of the electronic dispersion and the ionic configuration give clue to the mystery of the unexpected net magnetic moments which were found in some of the clusters AgnCu38-n at n=1-4, 24 as well as the two pure clusters. Possible origins for this unanticipated magnetism were explained in the context of the point group theory in much the same idea as the Clemenger-Nilsson model applied to simple metal clusters except that we draw particular attention to the atomic topologies and stress the bearing that they have on valence electrons in inducing them to disperse and occupy different molecular orbital energy levels.

  19. ROTMOKE study of step-induced magnetic anisotropy in vicinal Cu/Py/Ni/Cu(001)

    NASA Astrophysics Data System (ADS)

    Deng, J. X.; Ma, Song; Tan, A.; Li, J.; Zhang, Z. D.; Hwang, C.; Qiu, Z. Q.

    2015-03-01

    Py/Ni films were epitaxially grown on a 6o vicinal Cu(001) substrate with steps parallel to the [110] axis. The addition of Py film increases the Ni film spin reorientation transition (SRT) thickness to permit a study of the step-induced in-plane magnetic anisotropy in a wider Ni thickness range. Rotation MOKE (ROTMOKE) was applied to determine the step-induced magnetic anisotropy in the vicinal Cu/Py/Ni/Cu(001) as a function of both the Py and Ni film thicknesses. We found that the atomic steps from the vicinal Cu(001) induce an in-plane uniaxial magnetic anisotropy that favors both Py and Ni magnetizations perpendicular to the steps. In addition, thickness-dependent ROTMOKE measurement allows a separation of the Py and Ni volume-type step-induced magnetic anisotropies. We show that Ni films exhibit different step-induced magnetic anisotropies below and above ~ 5-6ML Ni thickness. visiting scholar at University of California at Berkeley.

  20. Magnetic stripe domains in Fe/Ni/Cu(001) system

    NASA Astrophysics Data System (ADS)

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

    2004-03-01

    Magnetic stripe domains associated with spin reorientation transition (SRT) of magnetic ultrathin films have been studied intensely due to its importance in 2D magnetic long range order. For the model system of Fe/Cu(100), Allenspach and Bischof observed irregular magnetic stripe domains at SRT for low temperature growth film [1]. Vaterlaus et al [2] found that room temperature growth Fe/Cu(100) displays a much more regular shape of magnetic stripes, but there is no SRT because of the paramagnetic and antiferromagnetic phases of the fcc Fe. To elucidate the nature of magnetic stripe domains associated with the SRT, we studied Fe/Ni/Cu(001) using the photoemission electron microscopy technique. The thin Ni film makes the Fe/Ni/Cu(100) SRT occur at a thinner Fe thickness than Fe/Cu(100) so that the complexity of the Fe fct-to-fcc structural transition can be eliminated. We unambiguously identified the stripe domains associated with the SRT of Fe/Ni/Cu(100). The thickness-dependence of the stripe domain width was obtained systematically using wedged samples, and can be well explained by theory. [1] R. Allenspach and A. Bischof, Phys. Rev. Lett. 69, 3385(1992) [2] A. Vaterlaus, C. Stamm, U. Maier, M.G. Pini, P. Politi, and D. Pescia, Phys. Rev. Lett. 84, 2247(2000)

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

    NASA Astrophysics Data System (ADS)

    Hong, Seongik; Kim, Namsoo

    2015-03-01

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

  2. Novel electrochemi-/photo-luminescence of Ag3Cu5 heterometallic alkynyl clusters.

    PubMed

    Jiang, Yi; Guo, Wen-Jing; Kong, De-Xian; Wang, Yong-Tao; Wang, Jin-Yun; Wei, Qiao-Hua

    2015-03-01

    Two windmill-like Ag3Cu5 alkynyl clusters were synthesized and characterized. They display novel PL and ECL properties, which could be modified by changing the substituent on the alkynyl ligands. According to the study of electrochemical behaviours, ECL behaviours and ECL emission spectra of the Ag3Cu5 clusters, a possible ECL mechanism was proposed. PMID:25641344

  3. Simulations of dynamical stabilization of AgCu nanocomposites by ion-beam processing

    E-print Network

    Nordlund, Kai

    Simulations of dynamical stabilization of AgCu nanocomposites by ion-beam processing R. A. Enrique nanocomposite structures from immiscible elements, relying on a self-organization phenomenon at steady state the formation of nanocomposites by this mechanism has been found in the immiscible system AgCu irradiated

  4. 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)

    Soria, F.; Poppa, H.

    1980-01-01

    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.

  5. Solute pairing in solution-hardened Cu-Ni, Cu-Pd binary, and Cu-Ni-Pd ternary fcc alloys

    NASA Astrophysics Data System (ADS)

    Wong, Joe; Nixon, W. E.; Mitchell, J. W.; Laderman, S. S.

    1992-01-01

    The pairing of solute atoms in solution-hardened binary and ternary face-centered cubic (fcc) binary and ternary Cu alloys has been investigated with the EXAFS (extended x-ray-absorption fine structure) technique using synchrotron radiation. Two binary Cu alloys, one containing 6 at. % Ni and the other 6 at. % Pd and a ternary Cu alloy containing 3 at. % Ni and 3 at. % Pd alloy were studied. The solute concentration in each system was chosen below that (8.33 at. %) required for finding one solute-solute pair in the first coordination sphere in the fcc structure. Detailed simulations of the experimental EXAFS signal arising from the first coordination shell of the Ni and Pd solute atoms in these alloys give the following results: (i) In both binary and ternary alloys, Ni is coordinated by 12 Cu host atoms at a distance equal to sum of the Goldschmidt radii. There is little evidence for Ni-Ni pairing. (ii) On the other hand, Pd-Pd pairing is found in both the binary and ternary systems. In addition, chemical interaction with the Cu matrix is evident from the Pd-Cu separation of 2.60 which is 0.05 shorter than the sum of their Goldschmidt radii. (iii) Finally, there is no pairing of Ni-Pd solute atoms in the ternary alloy.

  6. Cu-Ni nanoparticle-decorated graphene based photodetector.

    PubMed

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

    2014-07-21

    We report a simple and straight forward approach for the synthesis of Cu-Ni graphene hybrid nano-composites. These nano-composites have been characterized using AFM, XRD, FTIR spectroscopy and HRTEM. The characterization data clearly shows uniform decoration of Cu-Ni nanoparticles on graphene layers. A thin film of these nano-composites was found to exhibit unique electrical and photoresponse properties, which may be attributed to photothermoelectric and photovoltaic effects. The photocurrent measurements indicate superior light absorption and long lifetime of this device. PMID:24926960

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

    SciTech Connect

    Zhao Jun; Zhang Dongming; Zhao Jie

    2011-09-15

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

  8. Dependence of alloying and island composition on terrace width: Growth of Cu on Ag(100)

    NASA Astrophysics Data System (ADS)

    Beichert, Agnes; Zaum, Christopher; Morgenstern, Karina

    2015-07-01

    The growth of Cu on Ag(100) is investigated by low-temperature scanning tunneling microscopy. Exchange diffusion of Cu deposited onto Ag(100) leads to small pure Cu islands and larger islands consisting of a CuAg alloy in room temperature growth. The ratio of the different types of islands depends on terrace widths up to 100 nm. This surprisingly long-range dependence is correlated to the density of the surface alloy. We thus reveal that the exchange diffusion barrier is influenced by terrace widths far beyond quantum size confinement.

  9. Electromigration of composite Sn-Ag-Cu solder bumps

    NASA Astrophysics Data System (ADS)

    Sharma, Ashutosh; Xu, Di Erick; Chow, Jasper; Mayer, Michael; Sohn, Heung-Rak; Jung, Jae Pil

    2015-10-01

    This study investigates the electromigration (EM) behavior of lead free Sn-Ag-Cu (SAC) solder alloys that were reinforced with different types of nanoparticles [Copper-coated carbon nanotubes (Cu/CNT), La2O3, Graphene, SiC, and ZrO2]. The composite solders were bumped on a Cu substrate at 220C, and the resistance of the bumped solders was measured using a four wire setup. Current aging was carried out for 4 hours at a temperature of 160C, and an increase in resistance was noted during this time. Of all the composite solders that were studied, La2O3 and SiC reinforced SAC solders exhibited the smallest resistances after current aging. However, the rate of change in the resistance at room temperature was lower for the SiC-reinforced SAC solder. The SAC and Graphene reinforced SAC solder bumps completely failed within 15 - 20 min of these tests. The SiC nanoparticles were reported to possibly entrap the SAC atoms better than other nanoparticles with a lower rate of EM.

  10. Determination of Anand parameters for SnAgCuCe solder

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

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

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

    PubMed

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

    2014-08-25

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

  12. Enhanced low temperature thermoelectric performance of Ag-doped BiCuSeO

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed

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

    2014-10-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-06-01

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

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

    PubMed

    Huang, M L; Yang, F

    2014-01-01

    The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu(6)Sn(5) grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu(6)Sn(5) obeys a t(1/3) law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed. PMID:25408359

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

    PubMed Central

    Huang, M. L.; Yang, F.

    2014-01-01

    The downsizing of solder balls results in larger interfacial intermetallic compound (IMC) grains and less Cu substrate consumption in lead-free soldering on Cu substrates. This size effect on the interfacial reaction is experimentally demonstrated and theoretically analyzed using Sn-3.0Ag-0.5Cu and Sn-3.5Ag solder balls. The interfacial reaction between the Sn-xAg-yCu solders and Cu substrates is a dynamic response to a combination of effects of interfacial IMC growth, Cu substrate consumption and composition variation in the interface zone. A concentration gradient controlled (CGC) kinetics model is proposed to explain the combined effects. The concentration gradient of Cu at the interface, which is a function of solder volume, initial Cu concentration and reaction time, is the root cause of the size effect. We found that a larger Cu concentration gradient results in smaller Cu6Sn5 grains and more consumption of Cu substrate. According to our model, the growth kinetics of interfacial Cu6Sn5 obeys a t1/3 law when the molten solder has approached the solution saturation, and will be slower otherwise due to the interfering dissolution mechanism. The size effect introduced in this model is supported by a good agreement between theoretical and experimental results. Finally, the scope of application of this model is discussed. PMID:25408359

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

    NASA Astrophysics Data System (ADS)

    Huang, M. L.; Yang, F.

    2014-11-01

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

  19. The effect of Ag content on the formation of Ag3Sn plates in Sn-Ag-Cu lead-free solder

    NASA Astrophysics Data System (ADS)

    Chiang, Huann-Wu; Chang, Kenndy; Chen, Jun-Yuan

    2006-12-01

    The formation of Ag3Sn plates in the Sn-Ag-Cu lead-free solder joints for two different Ag content solder balls was investigated in wafer level chip scale packages (WLCSPs). After an appropriate surface mount technology reflow process on a printed circuit board, samples were subjected to 150C high-temperature storage (HTS), 1,000 h aging, or 1,000 cycles thermal cycling test (TCT). Sequentially, the cross-sectional analysis was scrutinized using a scanning electron microscope/energy dispersive spectrometer (SEM/EDX) to observe the metallurgical evolution of the amount of the Ag3Sn plates at the interface and the solder bulk itself. Pull and shear tests were also performed on samples. It was found that the interfacial intermetallic compound (IMC) thickness, the overall IMC area, and the numbers of Ag3Sn plates increase with increasing HTS and TCT cycles. The amount of large Ag3Sn plates found in the Sn-4.0Ag-0.5 Cu solder balls is much greater than that found in the Sn-2.6Ag-0.5Cu solder balls; however, no significant difference was found in the joint strength between two different Ag content solder joints.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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 150C 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.

  1. Cu-Ni nanoparticle-decorated graphene based photodetector

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  2. Abnormal resistivity behavior of Cu-Ni and Cu-Co alloys in undercooled liquid state

    NASA Astrophysics Data System (ADS)

    Guo, Fengxiang; Lu, Ting; Qin, Jingyu; Zheng, Hongliang; Tian, Xuelei

    2012-11-01

    The resistivity behavior of undercooled liquid Cu-Ni and Cu-Co alloys had been studied in the contactless method, to probe the structure transition in undercooled melts during the cooling process. Over the entire concentration range, linear behavior of resistivity with temperature was obtained in liquid and undercooled liquid Cu-Ni system. It implied that the formation of icosahedral order might not influence the electron scattering in undercooled liquid Cu-Ni alloys. Similar results were obtained in Cu-Co system in the vicinity of liquidus temperature. A turning point was obvious in temperature coefficient of resistivity for undercooled liquid Cu-Co alloys around the bimodal line, which was interpreted to be responsible for metastable liquid-liquid phase separation. During liquid phase separation process, resistivity decreased and the temperature coefficient of resistivity was larger than that of homogeneous melts. In combination with transmission electron microscopy and scanning electron microscope studies on the as-solidified microstructure, this was interpreted as the formation of egg-type structure and concentration change in Cu-rich and Co-rich phases. The mechanism controlling the separation and droplets motion was also discussed in undercooled liquid Cu-Co system.

  3. Growth and characterization of graphene on CuNi substrates

    NASA Astrophysics Data System (ADS)

    Tyagi, Parul

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

  4. Ni doping on Cu surfaces: Reduced copper resistivity

    SciTech Connect

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

    2014-09-29

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

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

    PubMed

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

    2011-01-01

    The corrosion resistance of nine experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.9% NaCl solution was investigated using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). CV measurements revealed that the breakdown potential (E(bd)) and zero current potential (E(zc)) increased with increasing Au/(Au+Ag) atomic ratio. Thus, the Au/(Au+Ag) atomic ratio, but not the Cu content, influenced the corrosion resistance of Ag-Au-Pt-Cu alloys. After the forward scan of CV, both optical and scanning electron microscope images showed that in all the experimental alloys, the matrix phase was corroded but not the second phase. From corrosion resistance viewpoint, the Ag-Au-Pt-Cu alloys seemed to be suitable for clinical application. PMID:21415553

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

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

    PubMed

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

    2014-09-24

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    SciTech Connect

    Lee, Kiju; Kim, Keun-Soo; Tsukada, Yutaka; Suganuma, Katsuaki; Yamanaka, Kimihiro; Kuritani, Soichi; Ueshima, Minoru

    2011-11-17

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

  11. Bidirectional threshold switching in engineered multilayer (Cu2O/Ag:Cu2O/Cu2O) stack for cross-point selector application

    NASA Astrophysics Data System (ADS)

    Song, Jeonghwan; Prakash, Amit; Lee, Daeseok; Woo, Jiyong; Cha, Euijun; Lee, Sangheon; Hwang, Hyunsang

    2015-09-01

    In this study, we achieved bidirectional threshold switching (TS) for selector applications in a Ag-Cu2O-based programmable-metallization-cell device by engineering the stack wherein Ag was intentionally incorporated in the oxide (Cu2O) layer by a simple approach comprising co-sputtering and subsequent optimized annealing. The distribution of the Ag was directly confirmed by transmission electron microscopy and energy dispersive spectroscopy line profiling. The observed TS occurred because of the spontaneous self-rupturing of the unstable Ag filament that formed in the oxide layer.

  12. Inhibiting the growth of Cu3Sn and Kirkendall voids in the Cu/Sn-Ag-Cu system by minor Pd alloying

    NASA Astrophysics Data System (ADS)

    Ho, Cheng En; Kuo, Tsai Tung; Wang, Chun Chien; Wu, Wei Hsiang

    2012-10-01

    In this study, the metallurgical reaction between Cu substrates (electrolytic type) and a Sn3Ag0.5Cu-xPd alloy at 180C was examined using a scanning electron microscope (SEM), electron probe microanalyzer (EPMA), focused ion beam (FIB) microscope, and transmission electron microscope (TEM). The results showed that the growth of Cu3Sn in the Cu/Sn-Ag-Cu solder joints was substantially suppressed by doping with a minor quantity of Pd (0.1-0.7 wt. %) in the solder alloy. The sluggish growth of Cu3Sn reduced the formation of Kirkendall voids at the Cu/Cu3Sn interface and significantly improved the mechanical reliability of the joint interface. It was argued that a minor addition of Pd into the solder stabilized the Cu6Sn5 phase and enlarged the interdiffusion coefficient of Cu6Sn5 but diminished that of the neighboring phase (Cu3Sn), thereby decreasing the Kirkendall effect in the Cu/Sn-Ag-Cu reactive system.

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

    SciTech Connect

    Udayabhaskar, R.; Karthikeyan, B.; Ollakkan, Muhamed Shafi

    2014-01-06

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

  14. Cu-Ag core-shell nanoparticles with enhanced oxidation stability for printed electronics.

    PubMed

    Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Lee, Yung Jong; Lee, Hyuck Mo

    2015-11-13

    In this work, we synthesized uniform Cu-Ag core-shell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The core-shell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the Cu-Ag core-shell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the Cu-Ag core-shell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the Cu-Ag core-shell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the Cu-Ag core-shell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties. PMID:26489391

  15. Cu-Ag coreshell nanoparticles with enhanced oxidation stability for printed electronics

    NASA Astrophysics Data System (ADS)

    Lee, Changsoo; Kim, Na Rae; Koo, Jahyun; Jong Lee, Yung; Lee, Hyuck Mo

    2015-11-01

    In this work, we synthesized uniform CuAg coreshell nanoparticles using a facile two-step process that consists of thermal decomposition and galvanic displacement methods. The coreshell structure of these nanoparticles was confirmed through characterization using transmission electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Furthermore, we investigated the oxidation stability of the CuAg coreshell nanoparticles in detail. Both qualitative and quantitative x-ray photoelectron spectroscopy analyses confirm that the CuAg coreshell nanoparticles have considerably higher oxidation stability than Cu nanoparticles. Finally, we formulated a conductive ink using the synthesized nanoparticles and coated it onto glass substrates. Following the sintering process, we compared the resistivity of the CuAg coreshell nanoparticles with that of the Cu nanoparticles. The results of this study clearly show that the CuAg coreshell nanoparticles can potentially be used as an alternative to Ag nanoparticles because of their superior oxidation stability and electrical properties.

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

    SciTech Connect

    Boyle, Jonathan; Hanket, Gregory; Shafarman, William

    2009-06-09

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

  17. Modulation effects of Cu doping on magnetic properties of Zn(Ni)O: First-principle calculations

    NASA Astrophysics Data System (ADS)

    Li, W. Q.; Cao, J. X.; Zhang, J. H.; Ding, J. W.

    2011-12-01

    Based on the density functional theory, we explore the electronic and magnetic properties of (Ni,Cu)-codoped ZnO systems (Zn(Ni,Cu)O). It is shown that dopant Cu has a long-range modulation for the Ni-Ni ferromagnetic coupling and enhances the stability of ferromagnetism. Furthermore, we demonstrate that the path of Cu modulation is through the Cu-Ni magnetic interaction.

  18. Prediction of Phase Formation in Nanoscale Sn-Ag-Cu Solder Alloy

    NASA Astrophysics Data System (ADS)

    Wu, Min; Lv, Bailin

    2015-09-01

    In a dynamic nonequilibrium process, the effective heat of formation allows the heat of formation to be calculated as a function of concentrations of the reacting atoms. In this work, we used the effective heat of formation rule to predict the formation and size of compound phases in a nanoscale Sn-Ag-Cu lead-free solder. We calculated the formation enthalpy and effective formation enthalpy of compounds in the Sn-Ag, Sn-Cu, and Ag-Cu systems by using the Miedema model and effective heat of formation. Our results show that, considering the surface effect of the nanoparticle, the effective heat of formation rule successfully predicts the phase formation and sizes of Ag3Sn and Cu6Sn5 compounds, which agrees well with experimental data.

  19. Photoelectron spectroscopic and computational study of (M-CO2)- anions, M = Cu, Ag, Au

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Lim, Eunhak; Kim, Seong K.; Bowen, Kit H.

    2015-11-01

    In a combined photoelectron spectroscopic and computational study of (M-CO2)-, M = Au, Ag, Cu, anionic complexes, we show that (Au-CO2)- forms both the chemisorbed and physisorbed isomers, AuCO 2- and Au-(CO2), respectively; that (Ag-CO2)- forms only the physisorbed isomer, Ag-(CO2); and that (Cu-CO2)- forms only the chemisorbed isomer, CuCO 2- . The two chemisorbed complexes, AuCO 2- and CuCO 2- , are covalently bound, formate-like anions, in which their CO2 moieties are significantly reduced. These two species are examples of electron-induced CO2 activation. The two physisorbed complexes, Au-(CO2) and Ag-(CO2), are electrostatically and thus weakly bound.

  20. Hydrogen evolution reaction measurements of dealloyed porous NiCu

    PubMed Central

    2013-01-01

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

  1. The Effect of Cu On The Magnetic Properties Of Cu-Substituted Ni-Zn Ferrites

    NASA Astrophysics Data System (ADS)

    Saiduzzaman, Hossain, Md. Abul; Hakim, M. A.; Hoque, Sheikh Manjura; Noor, Saroaut

    2011-06-01

    The samples Ni0.26Cu0.10+xZn0.64-xFe2O4 were investigated for their structural properties such as lattice parameter and density as a function of Cu content. The magnetic properties were determined. The SEM micrographs of the samples revealed that the average grain size increased with increasing Cu content. The value of Curie temperature significantly increased with copper content. The results are interpreted on the basis of microstructure and cation distribution.

  2. Crystalline monolayer surface of liquid AuCuSiAgPd: Metallic glass former

    E-print Network

    Pershan, Peter S.

    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 of Ge are the only metallic liquids to exhibit surface freezing well above the melting temperature

  3. Spectroscopy of microcrystals in the CuI-AgI system

    SciTech Connect

    Voll, V.A.; Barmasov, A.V.; Struts, A.V.

    1994-06-01

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

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

    PubMed

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

    2014-02-28

    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

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

    SciTech Connect

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

    2015-04-28

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  7. Structural and permeation kinetic correlations in PdCuAg membranes.

    PubMed

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

    2014-12-24

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

  8. Vibration-rotation emission spectra and combined isotopomer analyses for the coinage metal hydrides: CuH & CuD, AgH & AgD, and AuH

    E-print Network

    Le Roy, Robert J.

    emission studies of the spectra of the coinage metal hydrides. Since the first laboratory study of CuVibration-rotation emission spectra and combined isotopomer analyses for the coinage metal hydrides: CuH & CuD, AgH & AgD, and AuH & AuD Jenning Y. Seto, Zulfikar Morbi,a) Frank Charron, Sang K. Lee

  9. Impact of Electrical Current on the Long-Term Reliability of Fine-Pitch Ball Grid Array Packages with Sn-Ag-Cu Solder Interconnects

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Kyu

    2013-04-01

    The interaction between electrical current and the long-term reliability of fine-pitch ball grid array packages with Sn-3.0Ag-0.5Cu (wt.%) solder ball interconnects is investigated. In this study, 0.4-mm fine-pitch packages with 300- ?m-diameter Sn-Ag-Cu solder balls are used. Electrical current was applied under various conditions to two different package substrate surface finishes to compare the effects of chemically unmixed and mixed joint structures: a Cu/SAC305/Cu structure and a NiAu/SAC305/Cu structure, respectively. To study the thermal impact on the thermal fatigue performance and long-term reliability, the samples were thermally cycled from 0C to 100C with and without current stressing. Based on Weibull plots, the characteristic lifetime was degraded for the mixed joint structure, but little degradation was observed for the unmixed joint structure. The microstructure evolution was observed during constant current stressing and current stressing during thermal cycling. Accelerated intermetallic precipitation depletion at the package-side interface was observed in NiAu/SAC305/Cu structures due to current stressing, which was identified as the potential reason for the degradation in the thermal cycling performance.

  10. Effect of Heat Treatment Temperature on the Spectral Properties of Cu-Ni Coating.

    PubMed

    Liu, Xiao-zhen; Shen, Qin-weii; Liu, Xiao-zhou; Chen, Jie; Zhu, Liang-wei; Qi, Jie

    2015-04-01

    Cu-Ni coatings were prepared on the surface of nickel by electrodeposition method, and Cu-Ni coatings were heat-treated in 25-900 C. Heat-treated Cu-Ni coatings were characterized with scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX) and X-ray diffraction (XRD) techniques, respectively. Effects of heat treatment temperature on the spectral properties of Cu-Ni coatings were studied. The surface of Cu-Ni coating is composed of the nodules. The nodules of Cu-Ni coating surface become smaller with the increase in heat treatment temperature in 25-600 C. The nodules of Cu-Ni coating surface become smaller and the dividing line between the nodules becomes more blurred with the increase in heat treatment temperature in 600-900 C. The contents of copper in Cu-Ni coating decrease from 82.52 at % to 78.30 at % with the increase in heat treatment temperature in the range of 25-900 C; the contents of nickel in Cu-Ni coating increase from 17.48 at % to 21.70 at % with the increase in heat treatment temperature in the range of 25-900 C. The crystal structure of Cu-Ni coating is Cu0:8lNi0.19 cubic crystal structure. The crystal structure of the CuO0.81Ni0.19 becomes more complete with the increase in heat treatment temperature in 25- 300 C. Part of crystal structure of the Cu0.81AlNi0.19 can turn Cu0.8lNi0.19 cubic crystal structure into Cu3.8Ni cubic crystal structure, and is advantageous to Cu3.8Ni (311) and Cu0.81Ni0.19 (311) growth with the increase in heat treatment temperature in 600-900 C. PMID:26197608

  11. Effect of Surplus Phase on the Microstructure and Mechanical Properties in Al-Cu-Mg-Ag Alloys with High Cu/Mg Ratio

    NASA Astrophysics Data System (ADS)

    Xu, Xiaofeng; Zhao, Yuguang; Wang, Xudong; Zhang, Ming; Ning, Yuheng

    2015-11-01

    In order to examine the effect of surplus phase on the microstructure and mechanical properties, different compositions with high Cu/Mg ratio of the T6-temper extruded Al-Cu-Mg-Ag alloys were studied in this investigation. The results show that the Al-5.6Cu-0.56Mg-0.4Ag alloy obtains superior mechanical properties at room temperature, while the yield strength of Al-6.3Cu-0.48Mg-0.4Ag alloy is 378 MPa at 200 C, which is 200 MPa higher than that of Al-5.6Cu-0.56Mg-0.4Ag alloy. Although the excessive Cu content causes the slight strength loss and elongation decrease in the Al-6.3Cu-0.48Mg-0.4Ag alloy at room temperature, the surplus phases and recrystallized microstructure will play an effective role in strengthening the alloy at elevated temperature.

  12. Atmospheric Corrosion of Ag and Cu with Ozone, UV and NaCl

    NASA Astrophysics Data System (ADS)

    Lin, Huang

    Ag and Cu are both used for electronics and are susceptible to atmospheric corrosion. They are also good corrosivity monitors used to evaluate aggressiveness of the environment. Unfortunately, laboratory exposure testing does not always represent field environments very well. Discrepancies between lab and field exposure tests are not uncommon. For example, Ag does not corrode in salt spray exposure during ASTM B117 test, while it corrodes everywhere outdoor. This suggests that new laboratory exposure test for Ag needs to be designed and studied. A full factorial experiment was carried out with three factors: ozone, UV intensity and relative humidity (RH). NaCl was loaded by fast evaporation of NaCl/ethanol solution before exposure. After exposure, corrosion products were identified by XRD and quantified by galvanostatic reduction technique. For lab exposure samples, AgCl was identified as the only corrosion product in high RH (87%) environments, while Ag2O and AgO formed as well during exposures at low RH. This result derived a qualitative prediction on corrosion behavior of Ag in field. It predicts that less stable silver compounds such as oxide and sulfate are possible corrosion products in field even silver chloride is the dominant corrosion product forming in field. This prediction was confirmed by analysis of field exposed Ag samples. By quantification of corrosion products, it is determined that UV has two contravening effects on atmospheric corrosion of Ag: photolysis of ozone to generate stronger oxidizing species such as atomic O and photodecomposition of Ag corrosion products by UV radiation. Following its success in Ag corrosion research, the environment of UV, ozone and NaCl was extended to study Cu corrosion. It is determined that UV alone can double Cu corrosion rate by generation of electron-hole pairs in n-type cuprous oxide. It is also found that ozone alone is not as aggressive on Ag as on Cu because protection of naturally formed cuprous oxide. With the addition of NaCl, corrosion rate of Cu increases dramatically because of the breakdown of the naturally formed cuprous oxide by NaCl. To mimic corrosion behavior of metals in real field, a new environment chamber that generated constant deposition of NaCl was invented. With this novel environment chamber, the kinetics of Cu corrosion with constant deposition of NaCl in synthetic air with high and low CO2 and UV was studied. Cu2O and Cu2(OH)3Cl were both dominant corrosion products after exposure. 0.1 M Na2CO3 instead of 0.1M KCl was used as supporting electrolyte for reduction of Cu2O and Cu2(OH)3Cl, because it can clearly differentiate reduction of Cu2O and Cu2(OH)3Cl. With quantification of Cu2O and Cu2(OH)3Cl respectively, it is found UV has strong effect on formation of Cu2O but little on Cu2(OH)3Cl. It is also determined that localized corrosion of Cu dominates at the beginning of Cu corrosion and then uniform corrosion takes over.

  13. Synthesis and anti-bacterial activity of Cu, Ag and Cu-Ag alloy nanoparticles: A green approach

    SciTech Connect

    Valodkar, Mayur; Modi, Shefaly; Pal, Angshuman; Thakore, Sonal

    2011-03-15

    Research highlights: {yields} Synthesis of novel nanosized copper-silver alloys of different compositions. {yields} Completely green approach for synthesis of water soluble bimetallic nanoparticle. {yields} Interesting anti-bacterial activity of as synthesized metal and alloy nanoparticle. -- Abstract: Metallic and bimetallic nanoparticles of copper and silver in various proportions were prepared by microwave assisted chemical reduction in aqueous medium using the biopolymer, starch as a stabilizing agent. Ascorbic acid was used as the reducing agent. The silver and copper nanoparticles exhibited surface plasmon absorption resonance maxima (SPR) at 416 and 584 nm, respectively; while SPR for the Cu-Ag alloys appeared in between depending on the alloy composition. The SPR maxima for bimetallic nanoparticles changes linearly with increasing copper content in the alloy. Transmission electron micrograph (TEM) showed monodispersed particles in the range of 20 {+-} 5 nm size. Both silver and copper nanoparticles exhibited emission band at 485 and 645 nm, respectively. The starch-stabilized nanoparticles exhibited interesting antibacterial activity with both gram positive and gram negative bacteria at micromolar concentrations.

  14. Fabrication of Cu@AgCl nanocables for their enhanced activity toward the catalytic degradation of 4-chlorophenol.

    PubMed

    Huang, Zaidi; Wen, Ming; Wu, Qingsheng; Zhang, Yanqiao; Fang, Hao; Chen, Hanxing

    2015-12-15

    Partial and full AgCl nanoparticles (NPs) covered Cu@AgCl nanocables were fabricated based on Cu nanowires (NWs) through structure-director-induced assembly process in this work. The full covered Cu@AgCl nanocables, with the average diameter of ?50nm, consist of Cu NWs core at diameter of ?20nm and outer AgCl NPs shells with thickness of ?15nm. Using as UV-driven photocatalysts, as-designed Cu@AgCl nanocables exhibit high performance and stability for the catalytic degradation of 4-chlorophenol pollutants. Compared with the as-prepared Cu NWs, AgCl NPs, partial AgCl NPs covered Cu@AgCl nanocables and the reference photocatalysts P25-TiO2, full AgCl NPs covered Cu@AgCl nanocables exhibit much higher photocatalytic activity (nearly 91% conversion) toward the degradation of 4-chlorophenol with the reaction rate constant (k) of 0.026min(-1). Cu NWs are found to play important roles in quickly transferring photoelectrons, facilitating more effective separation of photoinduced electrons and holes and reducing the charge recombination due to their the high conductivity. PMID:26342972

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

    SciTech Connect

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

    2014-02-01

    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 (150300?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.

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

    SciTech Connect

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

    2010-01-22

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

  17. Interactions of oxygen and ethylenewith submonolayer Ag filmssupported on Ni(111)

    SciTech Connect

    Rettew, Robert; Meyer, Axel; Senanayake, Sanjaya D; Chen, Tsung-Liang; Petersburg, Cole; Flege, J. Ingo; Falta, Jens; Alamgir, Faisal

    2011-01-01

    We investigate the oxidation of, and the reaction of ethylene with, Ni(111) with and without sub-monolayer Ag adlayers as a function of temperature. The addition of Ag to Ni(111) is shown to enhance the activity towards the ethylene epoxidation reaction, and increase the temperature at which ethylene oxide is stable on the surface. We present a systematic study of the formation of chemisorbed oxygen on the Ag Ni(111) surfaces and correlate the presence and absence of O1 and O2 surface species with the reactivity towards ethylene. By characterizing the samples with low-energy electron microscopy (LEEM) in combination with X-ray photoelectron spectroscopy (XPS), we have identified specific growth of silver on step-edge sites and successfully increased the temperature at which the produced ethylene oxide remains stable, a trait which is desirable for catalysis.

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

    NASA Astrophysics Data System (ADS)

    Pstru?, Janusz; Gancarz, Tomasz

    2014-05-01

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

  19. Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  20. Microstructure and Grain Orientation Evolution in Sn-3.0Ag-0.5Cu Solder Interconnects Under Electrical Current Stressing

    NASA Astrophysics Data System (ADS)

    Chen, Hongtao; Hang, Chunjin; Fu, Xing; Li, Mingyu

    2015-10-01

    In situ observation was performed on cross-sections of Sn-3.0Ag-0.5Cu solder interconnects to track the evolution of microstructure and grain orientation under electrical current stressing. Cross-sections of Cu/Ni-Sn-3.0Ag-0.5Cu-Ni/Cu sandwich-structured solder interconnects were prepared by the standard metallographic method and subjected to electrical current stressing for different times. The electron backscatter diffraction technique was adopted to characterize the grain orientation and structure of the solder interconnects. The results show that metallization dissolution and intermetallic compound (IMC) migration have close relationships with the grain orientation and structure of the solder interconnects. Ni metallization dissolution at the cathode interface and IMC migration in the solder bulk can be accelerated when the c-axis of the grain is parallel to the electron flow direction, while no observable change was found when the c-axis of the grain was perpendicular to the electron flow direction. IMC can migrate along or be blocked at the grain boundary, depending on the misorientation between the current flow direction and grain boundary.

  1. Sputtering and secondary ion emission from Cu/Ni(1 0 0)

    NASA Astrophysics Data System (ADS)

    Karolewski, M. A.; Cavell, R. G.

    2001-05-01

    The growth and sputtering of Cu/Ni(1 0 0) in the Cu coverage range 0-2 monolayers (ML) have been studied using secondary ion mass spectrometry. Relative secondary ion (SI) yield data derived from these measurements have been compared with ballistic sputter yields predicted by molecular dynamics computer simulations. From the comparison, it is suggested that ionisation probabilities for atoms and dimers sputtered from Cu/Ni(1 0 0) are attenuated by a factor of 2-3 with respect to clean Ni(1 0 0), probably due to the work function shift accompanying Cu deposition. Two simple models of the ionisation process for sputtered atoms have been implemented. The electron tunnelling model proved to be more successful at predicting the variation of relative SI yields with Cu coverage than the thermalisation model. The mean information depth for atomic secondary ions (Ni +, Cu +) is found to be 0.390.15 ML beneath the surface layer of a 1 ML Cu/Ni(1 0 0) target. The surface layer of Cu/Ni(1 0 0) contributes 69% of atomic secondary ions, and 81% of the atomic constituents of dimer secondary ions (Ni 2+, NiCu +, Cu 2+).

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

    NASA Astrophysics Data System (ADS)

    Kozub, Gabriela A.

    2014-05-01

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

  3. (Ag,Cu)-Ta-O ternaries as high-temperature solid-lubricant coatings.

    PubMed

    Gao, Hongyu; Otero-de-la-Roza, Alberto; Gu, Jingjing; Stone, D'Arcy; Aouadi, Samir M; Johnson, Erin R; Martini, Ashlie

    2015-07-22

    Ternary oxides have gained increasing attention due to their potential use as solid lubricants at elevated temperatures. In this work, the tribological properties of three ternary oxides-AgTaO3, CuTaO3, and CuTa2O6-were studied using a combination of density-functional theory (DFT), molecular dynamics (MD) simulations with newly developed empirical potential parameters, and experimental measurements (AgTaO3 and CuTa2O6 only). Our results show that the MD-predicted friction force follows the trend AgTaO3 < CuTaO3 < CuTa2O6, which is consistent with the experimentally measured coefficients of friction. The wear performance from both MD and experiment exhibits the opposite trend, with CuTa2O6 providing the best resistance to wear. The sliding mechanisms are investigated using experimental characterization of the film composition after sliding, quantification of Ag or Cu cluster formation at the interface during the evolution of the film in MD, and DFT energy barriers for atom migration on the material surface. All our observations are consistent with the hypothesis that the formation of metal (or metal oxide) clusters on the surface are responsible for the friction and wear behavior of these materials. PMID:26106877

  4. Breakdown of magnetism in sub-nanometric Ni clusters embedded in Ag

    NASA Astrophysics Data System (ADS)

    Garca-Prieto, A.; Arteche, A.; Aguilera-Granja, F.; Torres, M. B.; Orue, I.; Alonso, J.; Fernndez Barqun, L.; Fernndez-Gubieda, M. L.

    2015-11-01

    Downsizing to the nanoscale has opened up a spectrum of new magnetic phenomena yet to be discovered. In this context, we investigate the magnetic properties of Ni clusters embedded in a metallic Ag matrix. Unlike in Ni free-standing clusters, where the magnetic moment increases towards the atomic value when decreasing the cluster size, we show, by tuning the Ni cluster size down to the sub-nanoscale, that there is a size limit below which the clusters become non-magnetic when embedded in Ag. To this end, we have fabricated by DC-sputtering a system composed of sub-nanometer sized and non interacting Ni clusters embedded into a Ag matrix. A thorough experimental characterization by means of structural techniques (x-ray diffraction, x-ray absorption spectroscopy) and DC-magnetization confirms that the cluster size is in the sub-nanometric range and shows that the magnetization of the system is dramatically reduced, reaching only 38% of the bulk value. The experimental system has been reproduced by density functional theory calculations on Ni m clusters (m = 16, 10 and 13) embedded in Ag. The combination of the experimental and theoretical analysis points out that there is a breakdown of magnetism occurring below a cluster size of six atoms. According to our results, the loss of magnetic moment is not due to AgNi hybridization but to charge transfer between the Ni sp and d orbitals, and the reduced magnetization observed experimentally is explained on the basis of the presence of a narrow cluster size-distribution where magnetic and non-magnetic clusters coexist.

  5. Breakdown of magnetism in sub-nanometric Ni clusters embedded in Ag.

    PubMed

    Garca-Prieto, A; Arteche, A; Aguilera-Granja, F; Torres, M B; Orue, I; Alonso, J; Barqun, L Fernndez; Fernndez-Gubieda, M L

    2015-11-13

    Downsizing to the nanoscale has opened up a spectrum of new magnetic phenomena yet to be discovered. In this context, we investigate the magnetic properties of Ni clusters embedded in a metallic Ag matrix. Unlike in Ni free-standing clusters, where the magnetic moment increases towards the atomic value when decreasing the cluster size, we show, by tuning the Ni cluster size down to the sub-nanoscale, that there is a size limit below which the clusters become non-magnetic when embedded in Ag. To this end, we have fabricated by DC-sputtering a system composed of sub-nanometer sized and non interacting Ni clusters embedded into a Ag matrix. A thorough experimental characterization by means of structural techniques (x-ray diffraction, x-ray absorption spectroscopy) and DC-magnetization confirms that the cluster size is in the sub-nanometric range and shows that the magnetization of the system is dramatically reduced, reaching only 38% of the bulk value. The experimental system has been reproduced by density functional theory calculations on Ni m clusters (m = 1-6, 10 and 13) embedded in Ag. The combination of the experimental and theoretical analysis points out that there is a breakdown of magnetism occurring below a cluster size of six atoms. According to our results, the loss of magnetic moment is not due to Ag-Ni hybridization but to charge transfer between the Ni sp and d orbitals, and the reduced magnetization observed experimentally is explained on the basis of the presence of a narrow cluster size-distribution where magnetic and non-magnetic clusters coexist. PMID:26487422

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

    E-print Network

    Zheng, Yufeng

    indicated a significantly reduced number of bacteria (S. aureus, S. epidermidis and P. gin- givalis by the introduction of pure Ag precipitates into the TiNi matrix phase. The microstructure, mechanical property antibacterial mechanism for the TiNiAg alloy is discussed. 2011 Acta Materialia Inc. Published by Elsevier Ltd

  7. Nano PtCu binary and PtCuAg ternary alloy catalysts for oxygen reduction reaction in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Zhou, Yanmei; Zhang, Dongming

    2015-03-01

    In order to decrease the cost and enhance the performance of the cathode catalyst for PEMFC, carbon supported PtCu and PtCuAg alloys with differential Ag content are synthesized by a borohydride chemical reduction. The oxygen reduction reaction (ORR) activity are tested by cyclic voltammetry (CV?and linear sweep voltammograms (LSV) in 0.5 M H2SO4. By comparison with the ORR activities of PtCu/C and a series of PtCuAg/C catalysts with differential metal atomic ratios of Pt:Cu:Ag, the PtCuAg/C catalyst with the atomic ratio on 3:10:1 (marked as PtCuAg/C(3:10:1)) shows the best catalytic activity. For the 200th cycles, the limited current reaches to 3.85 mA cm-2 for PtCuAg/C(3:10:1) with Pt-loading of 9.29 ?gPt cm-2. The CV curves of the PtCuAg/C catalysts show one more pair of redox peaks of Ag compared with PtCu/C catalyst, which is much different from Pt-M alloy catalysts reported in other literature. The TEM and XRD as well as XPS results indicate that the enhanced ORR activity is the result of the smaller particle size, the crystal distortion and the more exposure of Pt atoms with the introduction of Ag for PtCuAg/C(3:10:1) catalyst.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

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

    SciTech Connect

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

    2005-01-31

    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}.

  11. In vitro cytotoxicity of Ag-Pd-Cu-based casting alloys.

    PubMed

    Niemi, L; Hensten-Pettersen, A

    1985-01-01

    The cytotoxicity and its correlation to alloy composition, structure, corrosion, as well as galvanic coupling was studied with 12 Ag-Pd-Cu-type alloys, one conventional type III gold alloy and pure Ag, Cu, and Pd. The agar overlay cell culture technique was used. Single phase binary CuPd alloys were only slightly cytotoxic below a Cu content of 30 wt%. The tested multiphase alloys were all toxic, but no correlation between toxicity and Cu content could be observed. Solid solution annealing increased the cytotoxicity of a multiphase alloy. Exposure of a single phase alloy to an artificial saliva for 1 week prior to the test decreased its cytotoxicity significantly. Galvanic coupling of the alloys through an outer copper wire decreased their cytotoxicity. PMID:4066728

  12. Magnetic Properties of Evaporated Ni Thin Films: Effect of Substrates, Thickness, and Cu Underlayer

    NASA Astrophysics Data System (ADS)

    Hemmous, M.; Layadi, A.; Kerkache, L.; Tiercelin, N.; Preobrazhensky, V.; Pernod, P.

    2015-09-01

    Ni thin films have been deposited by thermal evaporation onto glass, Si, Cu, mica, and Al2O3 substrates with and without a Cu underlayer. The Ni thicknesses, t, are in the 4 to 163 nm range. The Cu underlayer has also been evaporated with a Cu thickness equal to 27, 52, and 90 nm. The effects of substrate, Ni thickness, and the Cu underlayer on the magnetic properties of Ni are investigated. Magnetic properties were inferred from the vibrating sample magnetometer (VSM) set-up. The substrates induce not only different coercive field H C values but also the origins of the H C values are different. The squareness S depends on substrate and t and seems to be relatively large in Ni/glass and Ni/Cu, and small in Ni/Si and Ni/mica. The Cu underlayer leads to an overall increase of H C and the saturation H sat and to a decrease in the remnant magnetization; the increase in H sat may be related to a stress-induced anisotropy in Ni/Cu/substrates.

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

    SciTech Connect

    Silva, R.A.G.; Paganotti, A.; Gama, S.; Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A.

    2013-01-15

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  15. Cu-Ni-Fe anodes having improved microstructure

    DOEpatents

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

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

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

    SciTech Connect

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

    2002-01-15

    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.

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

    NASA Astrophysics Data System (ADS)

    Jabbar, Abdul; Mumtaz, Muhammad; Nadeem, Kashif

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 ? sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under an AC voltage of 200 V and frequency of 1300 Hz, the ACEL device emitted blue light at 496 nm with a brightness of 103 cd m-2.Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 ? sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under an AC voltage of 200 V and frequency of 1300 Hz, the ACEL device emitted blue light at 496 nm with a brightness of 103 cd m-2. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr06246e

  19. Electromigration Behavior in Sn-37Pb and Sn-3.0Ag-0.5Cu Flip-Chip Solder Joints under High Current Density

    NASA Astrophysics Data System (ADS)

    Ha, Sang-Su; Kim, Jong-Woong; Yoon, Jeong-Won; Ha, Sang-Ok; Jung, Seung-Boo

    2009-01-01

    The electromigration of conventional Sn-37Pb and Pb-free Sn-3.0Ag-0.5Cu (in wt.%) solder bumps was investigated with a high current density of 2.5 104 A/cm2 at 423 K using flip-chip specimens comprised of an upper Si chip and a lower bismaleimide triazine (BT) substrate. Electromigration failure of the Sn-37Pb and Sn-3.0Ag-0.5Cu solder bumps occurred with complete consumption of electroless Ni immersion Au (ENIG) underbump metallization (UBM) and void formation at the cathode side of the solder bump. Finite element analysis and computational simulations indicated high current crowding of electrons in the patterned Cu on the Si chip side, whereas the solder bumps and Cu line of the BT substrate had a relatively low density of flowing electrons. These findings were confirmed by the experimental results. The electromigration reliability of the Sn-3.0Ag-0.5Cu solder joint was superior to that of Sn-37Pb.

  20. Interaction of an edge dislocation with Cu-Ni-vacancy clusters in bcc iron

    NASA Astrophysics Data System (ADS)

    Terentyev, Dmitry; Malerba, Lorenzo; Bonny, Giovanni; Al-Motasem, A. T.; Posselt, M.

    2011-12-01

    In this work we studied the interaction of a <1 1 1>{1 1 0} edge dislocation with Cu-rich precipitates, mimicking those that are known to form in RPV steels. We have applied a combination of Monte Carlo and molecular dynamics techniques to explore the structure and obstacle strength of Cu-Ni-vacancy clusters of nanometric size below the resolution limit of transmission electron microscopy. The results show that the strength of Cu-vacancy, Cu-Ni and Cu-Ni-vacancy clusters is comparable or even smaller than that of pure Cu clusters, but considerably smaller than the strength of pure vacancy clusters or nanovoids. Thus, the enrichment of small Cu precipitates by Ni atoms and/or a small amount of vacancies does not increase their obstacle strength, at least in the case of edge dislocations.

  1. Effect of tensile misfit dislocation on diffusion of Ni adatom on Ni/Cu(111): a Molecular Dynamics study

    NASA Astrophysics Data System (ADS)

    Trushin, Oleg; Aminpour, Maral; Rahman, Talat S.

    2012-02-01

    We apply molecular dynamics and molecular static methods to calculate the effect of tensile misfit dislocation on Ni adatom diffusion for Ni/Cu(111) system and compare the results with those calculated previously for Cu adatom on the Cu/Ni(111) system [1] which has compressive dislocation. Our Ni/Cu(111) substrate model system consists of 5 layers of Ni on top of a 7-layer Cu(111) slab which after energy minimization displays an isolated misfit dislocation buried at the Cu-Ni interface, causing the Ni film to be under tensile stress. In contrast to the isotropic trajectory that emerges on a defect-free surface, in this tensile stressed system we find that presence of the defect under the surface strongly affects the adatom trajectory, introducing anisotropy in atomic diffusion similar to compressive system, but with the difference: tensile misfit dislocation enhances diffusion in the direction perpendicular to the misfit dislocation line and decreases it in the direction parallel to it, whereas compressive dislocation induces the opposite behavior. We present the calculated energy barriers for the adatom and compare them with adatom diffusion on defect -- free and on the surface containing compressive dislocation. [4pt] [1] M. Aminpour, O. Trushin, and T. S. Rahman, Physical Review B, 84, 035455 (2011).

  2. Tribological properties of self-lubricating NiAl/Mo-based composites containing AgVO{sub 3} nanowires

    SciTech Connect

    Liu, Eryong; Gao, Yimin; Bai, Yaping; Yi, Gewen; Wang, Wenzhen; Zeng, Zhixiang; Jia, Junhong

    2014-11-15

    Silver vanadate (AgVO{sub 3}) nanowires were synthesized by hydrothermal method and self-lubricating NiAl/Mo-AgVO{sub 3} composites were fabricated by powder metallurgy technique. The composition and microstructure of NiAl/Mo-based composites were characterized and the tribological properties were investigated from room temperature to 900 C. The results showed that NiAl/Mo-based composites were consisted of nanocrystalline B2 ordered NiAl matrix, Al{sub 2}O{sub 3}, Mo{sub 2}C, metallic Ag and vanadium oxide phase. The appearance of metallic Ag and vanadium oxide phase can be attributed to the decomposition of AgVO{sub 3} during sintering. Wear testing results confirmed that NiAl/Mo-based composites have excellent tribological properties over a wide temperature range. For example, the friction coefficient and wear rate of NiAl/Mo-based composites containing AgVO{sub 3} were significantly lower than the composites containing only metallic Mo or AgVO{sub 3} lubricant when the temperature is above 300 C, which can be attributed to the synergistic lubricating action of metallic Mo and AgVO{sub 3} lubricants. Furthermore, Raman results indicated that the composition on the worn surface of NiAl-based composites was self-adjusted after wear testing at different temperatures. For example, Ag{sub 3}VO{sub 4} and Fe{sub 3}O{sub 4} lubricants were responsible for the improvement of tribological properties at 500 C, AgVO{sub 3}, Ag{sub 3}VO{sub 4} and molybdate for 700 C, and AgVO{sub 3} and molybdate for 900 C of NiAl-based composites with the addition of metallic Mo and AgVO{sub 3}. - Highlights: NiAl/Mo-AgVO{sub 3} nanocomposites were prepared by mechanical alloying and sintering. AgVO{sub 3} decomposed to metallic Ag and vanadium oxide during the sintering process. NiAl/Mo-AgVO{sub 3} exhibited superior tribological properties at a board temperature range. Phase composition on the worn surface was varied with temperatures. Self-adjusted action was responsible for the improvement of tribological properties.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  4. ELECTRODEPOSITION OF AG ALLOYS WITH NI AND W FROM A THIOUREA-CITRATE ELECTROLYTE

    E-print Network

    of binary alloys of silver, such as tin-silver, silver-nickel and electroless deposition of silver-4 and was negligible over pH 4. Ag-Ni-W nanowire deposition was attempted in polycarbonate templates with 50 nm diameter and length of 6 um. The nanowires we released by dissolution of the membrane in dichloromethane

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

    NASA Astrophysics Data System (ADS)

    Jiang, ShuMin; Xie, QiuYue; Wu, DaJian

    2015-05-01

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

  6. Nanostructured YbAgCu4 for potential cryogenic thermoelectric cooling

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  7. Preparation of Ag/Cu Janus nanowires: Electrodeposition in track-etched polymer templates

    NASA Astrophysics Data System (ADS)

    Zhu, X. R.; Wang, C. M.; Fu, Q. B.; Jiao, Z.; Wang, W. D.; Qin, G. Y.; Xue, J. M.

    2015-08-01

    Bimetal (Janus) nanowire has been widely used as a promising nanoscale motor. In this paper we present a highly controllable method to fabricate Ag/Cu Janus nanowires using track-etched polymer templates. Ag/Cu Janus nanowires with uniform size and stabilized structure have been successfully fabricated by electrodepositing Ag nanowires, and subsequently Cu nanowires in track-etched polymer templates. The pore size of nanopores prepared by this template is uniform and continuously controlled, so aperture of achieved nanowires are uniform and can be regulated. This polymer template can dissolve inorganic solvents that do not react with the nanowires, making it is easy to release the nanowires into solution. The nanopore shape in the track-etched templates is adjustable (e.g. conical), nanowires with more special shapes could be fabricated. Thus, these features make this simple and inexpensive method very suitable for the preparation of Janus nanowire.

  8. Evolution of the Intermetallic Compounds in Ni/Sn-2.5Ag/Ni Microbumps for Three-Dimensional Integrated Circuits

    NASA Astrophysics Data System (ADS)

    Hsu, H. H.; Huang, Y. T.; Huang, S. Y.; Chang, T. C.; Wu, Albert T.

    2015-10-01

    Ni/Sn-2.5Ag/Ni samples were used to simulate the microbumps in three-dimensional (3D) packaging. The annealed test was adopted to observe the microstructure of intermetallic compound formation at 100C, 125C, and 150C up to 1000 h. In the Ni/Sn-2.5Ag/Ni, predominant phases of layer-type Ni3Sn4 and Ag3Sn particles could be seen under the thermal treatment. The formation of Ni3Sn4 followed a parabolic rate law at each aging temperature. Due to the limited solder volume, the remaining solder of the microbump was completely exhausted after long-time annealing at 150C. The activation energy for Ni3Sn4 formation in the Ni/Sn-2.5Ag/Ni microbump was 171.8 kJ/mol. Furthermore, the consumption of the Ni under bump metallization (UBM) was estimated based on the mass balance of Ni atoms during the interfacial reaction.

  9. Electromigration Study on Sn(Cu) Solder/Ni(P) Joint Interfaces

    NASA Astrophysics Data System (ADS)

    Wu, S. H.; Hu, Y. J.; Lu, C. T.; Huang, T. S.; Chang, Y. H.; Liu, C. Y.

    2012-12-01

    This study investigates the electromigration (EM) effect under a high current density (104 A/cm2) on the different interfacial compound phases at Sn(Cu) solder/electroless nickel immersion gold (ENIG) interfaces. The interfacial Ni3Sn4 phase at the Sn-0.7 wt.%Cu/ENIG joint interface was quickly depleted after a short period (50 h) of current stressing. The inference drawn is that the Ni atoms in the Ni3Sn4 phase at the joint interface are likely forced out under current stressing; however, the ternary (Cu,Ni)6Sn5 compound effectively reduces the EM-driven Ni flux into the Sn bump; thus, a significantly lower Ni(P) consumption was observed at the Sn-1 wt.%Cu/ENIG interface. The EM-induced Ni(P) dissolution rates in the Sn-0.2 wt.%Cu/ENIG and Sn-1 wt.%Cu/ENIG cases were calculated to be 0.028 ?m/h and 0.018 ?m/h, respectively. In addition, significant EM-assisted Ni3P formation was observed for the current-stressed Sn-0.2 wt.%Cu/ENIG and Sn-0.7 wt.%Cu/ENIG cases; however, for the Sn-1 wt.%Cu/ENIG case, formation of a Ni3P layer was scarcely observed. Moreover, the initial (Cu,Ni)6Sn5 that formed at the interface appeared compact with a layer-type structure, which reduced the EM-driven Ni diffusion.

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

    E-print Network

    Zhang, Yong

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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 C, 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 C 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.

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

    SciTech Connect

    Rapp, R.A.

    1981-02-01

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

  13. Three-dimensionally ordered macroporous Cu2O/Ni inverse opal electrodes for electrochemical supercapacitors.

    PubMed

    Deng, Ming-Jay; Song, Cheng-Zhao; Ho, Pei-Jung; Wang, Cheng-Chia; Chen, Jin-Ming; Lu, Kueih-Tzu

    2013-05-28

    With an ordered polystyrene (PS) template-assisted electrochemical approach we synthesized three-dimensional ordered macroporous (3DOM) Cu2O/Ni inverse opals as electrodes for supercapacitors. The 3DOM Cu2O/Ni electrodes display superior kinetic performance, and satisfactory rate capability and cycling performance. PMID:23608896

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

    PubMed

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

    2008-11-01

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

  15. Cluster reaction of [Ag8]-/[Cu8]- with chlorine: Evidence for the harpoon mechanism?

    NASA Astrophysics Data System (ADS)

    Luo, Zhixun; Berkdemir, Cneyt; Smith, Jordan C.; Castleman, A. W.

    2013-09-01

    To examine the question whether the harpoon mechanism can account for the reactive behavior of microscopic charged systems, we have investigated the reactivity of coinage metal clusters in gas phase. Our studies reveal that the reactivity between [Cu8]-/[Ag8]- and chlorine gas is consistent with the harpoon mechanism. An increased reactive cross section is noted through our theoretical estimation based on two methods, ascribed to a long-range transfer of valence electrons from the [Cu8]-/[Ag8]- cluster to chlorine. Insights into this reactivity will be of interest to other researchers working on obtaining a better understanding of the reaction mechanisms of such superatomic species.

  16. Interface stress development in the Cu/Ag nanostructured multilayered film during the tensile deformation

    SciTech Connect

    Su, R.; Nie, Z. H.; Zhang, Q. H.; Li, X. J.; Li, L. E-mail: ydwang@mail.neu.edu.cn; Zhou, X. T.; Wang, Y. D. E-mail: ydwang@mail.neu.edu.cn; Wu, Y. D.; Hui, X. D.; Wang, M. G.

    2014-12-01

    Cu/Ag nanostructured multilayered films (NMFs) with different stacking sequences were investigated by synchrotron X-ray diffraction during the tensile deformations for interface stress study. The lattice strains were carefully traced and the stress partition, which usually occurs in the multiphase bulk metallic materials during plastic deformations, was first quantitatively analyzed in the NMFs here. The interface stress of the Cu/Ag NMFs was carefully analyzed during the tensile deformation and the results revealed that the interface stress was along the loading direction and exhibited three-stage evolution. This tensile interface stress has a detrimental effect on the deformation, leading to the early fracture of the NMFs.

  17. An optimized interatomic potential for Cu-Ni alloys with the embedded-atom method.

    PubMed

    Onat, Berk; Durukano?lu, Sondan

    2014-01-22

    We have developed a semi-empirical and many-body type model potential using a modified charge density profile for Cu-Ni alloys based on the embedded-atom method (EAM) formalism with an improved optimization technique. The potential is determined by fitting to experimental and first-principles data for Cu, Ni and Cu-Ni binary compounds, such as lattice constants, cohesive energies, bulk modulus, elastic constants, diatomic bond lengths and bond energies. The generated potentials were tested by computing a variety of properties of pure elements and the alloy of Cu, Ni: the melting points, alloy mixing enthalpy, lattice specific heat, equilibrium lattice structures, vacancy formation and interstitial formation energies, and various diffusion barriers on the (100) and (111) surfaces of Cu and Ni. PMID:24351396

  18. Performance of ethanol electro-oxidation on Ni-Cu alloy nanowires through composition modulation.

    PubMed

    Tian, Xi-Ke; Zhao, Xiao-Yu; Zhang, Li-de; Yang, Chao; Pi, Zhen-Bang; Zhang, Su-Xin

    2008-05-28

    To reduce the cost of the catalyst for direct ethanol fuel cells and improve its catalytic activity, highly ordered Ni-Cu alloy nanowire arrays have been fabricated successfully by differential pulse current electro-deposition into the pores of a porous anodic alumina membrane (AAMs). The energy dispersion spectrum, scanning and transmission electron microscopy were utilized to characterize the composition and morphology of the Ni-Cu alloy nanowire arrays. The results reveal that the nanowires in the array are uniform, well isolated and parallel to each other. The catalytic activity of the nanowire electrode arrays for ethanol oxidation was tested and the binary alloy nanowire array possesses good catalytic activity for the electro-oxidation of ethanol. The performance of ethanol electro-oxidation was controlled by varying the Cu content in the Ni-Cu alloy and the Ni-Cu alloy nanowire electrode shows much better stability than the pure Ni one. PMID:21730590

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

    SciTech Connect

    Jang, Jai-young; Chun, Su-jin; Kim, Nam-suk; Cho, Jeung-won; Kim, Jae-hyun; Yeom, Jong-taek; Kim, Jae-il; Nam, Tae-hyun

    2013-12-15

    Graphical abstract: - Highlights: Ag, In and Sn were soluble in TiNi matrix, while Sb, Te, Tl, Pb and Bi were not. The B2-R-B19?transformation occurred in Ti-Ni-(Ag, In, Sn) alloys. Solid solution hardening was essential for inducing the B2-R transformation. - Abstract: The microstructures and transformation behaviors of TiNiX (Ag, In, Sn, Sb, Te, Tl, Pb, Bi) ternary alloys were investigated using electron probe micro-analysis (EPMA), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Micro Vickers hardness tests. All specimens consisted of TiNi matrices and second phase particles. Ag, In and Sn were soluble in TiNi matrices with a limited solubility (?1.0 at%), while Sb, Te, Tl, Pb and Bi were not soluble. Two-stage B2-R-B19? transformation occurred in Ti48.8Ni1.2Ag, Ti49.0Ni1.0In and Ti49.0Ni1.0Sn alloys, while one-stage B2-B19? transformation occurred in Ti49.0Ni1.0Ag, Ti49.0Ni1.0Sb, Ti49.0Ni1.0Te, Ti49.0Ni1.0Pb and Ti49.0Ni1.0Bi alloys. Micro Vickers hardness of the alloys displaying the B2-R-B19? transformation (Hv 250368) was much larger than that (NiX (X = non-transition elements) alloys.

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    E-print Network

    Morse, Michael D.

    Spectroscopic studies of jet-cooled NiAu and PtCu Eileen M. Spain and Michael D. Morse Department) Spectroscopic investigations of NiAu and PtCu have revealed that both molecules possess 2Asi2 ground electronic states, and are in this respect analogous to the isovalent molecule NiCu. The ground-state bond lengths

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

    NASA Astrophysics Data System (ADS)

    Fang, Gu; Chen, Chih-chi

    2015-07-01

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

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

    PubMed

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

    2014-05-21

    Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ?10 ? sq(-1)) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS?:?Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under an AC voltage of 200 V and frequency of 1300 Hz, the ACEL device emitted blue light at 496 nm with a brightness of 103 cd m(-2). PMID:24733262

  6. Structures and electronic properties of Cu 20, Ag 20, and Au 20 clusters with density functional method

    NASA Astrophysics Data System (ADS)

    Wang, Jinlan; Wang, Guanghou; Zhao, Jijun

    2003-10-01

    We have investigated the lowest-energy structures and electronic properties of the 20-atoms coinage metal clusters (Cu 20, Ag 20, and Au 20) using density functional theory (DFT) within generalized gradient approximation. The most stable configurations obtained for Ag 20 and Au 20 clusters are tetrahedral structures T d symmetry), while compact structure with C s symmetry is preferred for Cu 20. Large HOMO-LUMO gap is found for Au 20 and Ag 20 with tetrahedral structures, while it is much small in the Cu 20 isomer with tetrahedral structures. The compact C s structure of Cu 20 has large gap comparable to that of Au 20 with tetrahedral structure.

  7. First principles investigation of the diffusion of interstitial Cu, Ag and Au in ZnTe

    NASA Astrophysics Data System (ADS)

    Chen, Li An; Zhu, Xing Feng; Chen, Ling Fu

    2015-07-01

    The diffusion is of great significance in many applications when the impurities are employed to tune the semiconductor's electrical or optical properties. It is necessary to understand how dopant defects diffuse in semiconductors. Using first-principles calculations, we consider interstitial diffusion mechanisms and calculate the migration barrier energies of interstitial Cu, Ag and Au atoms in II-VI compounds ZnTe. We find that the relative size of dopant and bulk atoms is an important factor which affects the diffusion behavior. The high symmetry Tc site, which is tetrahedrally coordinated by four cation atoms, is the global minimum energy location for Ag and Au interstitials. The size of Cu adatom is small, so Cu is more stable when it locates at the Ta site which is tetrahedrally coordinated by four anion atoms. But the global minimum energy location for Cu interstitials is M site which is of smaller space than Ta. Cu adatoms show an asymmetric curve of energy diffusion barrier with two energetically distinct extremum in the pathway. Ag diffuses along nearly straight line paths along [111] or equivalent directions. Diffusion for Cu or Au deviates from the straight line paths along <111> avoiding high symmetric sites.

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

    PubMed Central

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

    2015-01-01

    The surface chemistry of methane on NiZrO2 and bimetallic CuNiZrO2 catalysts and the stability of the CuNi alloy under reaction conditions of methane decomposition were investigated by combining reactivity measurements and in situ synchrotron-based near-ambient pressure XPS. Cu was selected as an exemplary promoter for modifying the reactivity of Ni and enhancing the resistance against coke formation. We observed an activation process occurring in methane between 650 and 735 K with the exact temperature depending on the composition which resulted in an irreversible modification of the catalytic performance of the bimetallic catalysts towards a Ni-like behaviour. The sudden increase in catalytic activity could be explained by an increase in the concentration of reduced Ni atoms at the catalyst surface in the active state, likely as a consequence of the interaction with methane. Cu addition to Ni improved the desired resistance against carbon deposition by lowering the amount of coke formed. As a key conclusion, the CuNi alloy shows limited stability under relevant reaction conditions. This system is stable only in a limited range of temperature up to ~700 K in methane. Beyond this temperature, segregation of Ni species causes a fast increase in methane decomposition rate. In view of the applicability of this system, a detailed understanding of the stability and surface composition of the bimetallic phases present and the influence of the Cu promoter on the surface chemistry under relevant reaction conditions are essential. PMID:25815163

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

    PubMed

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

    2014-07-01

    Ag-Pd-Au-Cu alloys have been used widely for dental prosthetic applications. Significant enhancement of the mechanical properties of the Ag-20Pd-12Au-14.5Cu alloy as a result of the precipitation of the ?' phase through high-temperature solution treatment (ST), which is different from conventional aging treatment in these alloys, has been reported. The relationship between the unique hardening behavior and precipitation of the ?' phase in Ag-20Pd-12Au-xCu alloys (x=6.5, 13, 14.5, 17, and 20mass%) subjected to the high-temperature ST at 1123K for 3.6ks was investigated in this study. Unique hardening behavior after the high-temperature ST also occurs in Ag-20Pd-12Au-xCu alloys (x=13, 17, and 20) with precipitation of the ?' phase. However, hardening is not observed and the ?' phase does not precipitate in the Ag-20Pd-12Au-6.5Cu alloy after the same ST. The tensile strength and 0.2% proof stress also increase in Ag-20Pd-12Au-xCu alloys (x=13, 14.5, 17, and 20) after the high-temperature ST. In addition, these values after the high-temperature ST increase with increasing Cu content in Ag-20Pd-12Au-xCu alloys (x=14.5, 17, and 20). The formation process of the ?' phase can be explained in terms of diffusion of Ag and Cu atoms and precipitation of the ?' phase. Clarification of the relationship between hardening and precipitation of the ?' phase via high-temperature ST is expected to help the development of more effective heat treatments for hardening in Ag-20Pd-12Au-xCu alloys. PMID:24769914

  10. Z .Applied Surface Science 142 1999 1822 z /Electronic properties of a pseudomorphic Cu-layer on Ni 111

    E-print Network

    Birkenheuer, Uwe

    of Ni and Cu are very different: Cu being a coinage metal has a completely filled 3d-shell and thereforeZ .Applied Surface Science 142 1999 1822 z /Electronic properties of a pseudomorphic Cuersitat Munchen, D-85747 Garching, Germany Abstract Z .The band structure of a monolayer Cu on Ni 111

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

    SciTech Connect

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

    2010-02-10

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

  12. Growth Behavior of Intermetallic Compounds in Cu/Sn3.0Ag0.5Cu Solder Joints with Different Rates of Cooling

    NASA Astrophysics Data System (ADS)

    Yang, Linmei; Zhang, Z. F.

    2015-01-01

    The growth behavior of intermetallic compounds (IMC) in Cu/Sn3.0Ag0.5Cu solder joints, including the interfacial Cu6Sn5 layer and Ag3Sn, and Cu6Sn5 in the solder, were investigated when different cooling methodsquenched water, cooling in air, and cooling in a furnace after reflowwere used. For the solder joint quenched in water, no obvious Cu6Sn5 or Ag3Sn was detected in the solder, and the thickness of interfacial Cu6Sn5 layer was slightly thinner than that of the joint cooled in air. On the basis of results from scanning electron microscopy and energy-dispersive spectrometry, a mechanism is proposed for growth of IMC in Sn3.0Ag0.5Cu solder during solidification. The rate of cooling has a substantial effect on the morphology and size of Ag3Sn, which evolved into large plate-like shapes when the joint was cooled slowly in a furnace. However, the morphology of Ag3Sn was branch-like or particle-like when the joint was cooled in air. This is attributed to re-growth of Ag3Sn grains via substantial atomic diffusion during the high-temperature stage of furnace cooling.

  13. Ohmic Contacts of AuGeNi and Ag/AuGeNi to n-GaSb with Various Sintering Temperatures

    NASA Astrophysics Data System (ADS)

    Su, Yan Kuin; Juang, Fuh Shyang; Gan, Kuang Jou

    1991-05-01

    The ohmic contact properties of Ag/AuGeNi/n-GaSb and AuGeNi/n-GaSb systems were investigated in this paper by measuring the barrier height and specific contact resistance with various sintering temperatures. The lowest specific contact resistance was about 8 10-3--8 10-4 ?{\\cdot}cm2 for the Ag/AuGeNi/n-GaSb contact system when the sintering temperature was 400C for 2 min. This is better than that of the AuGeNi/n-GaSb contact system. Rutherford backscattering spectroscopy (RBS) was also used to study the interface between Ag/AuGeNi and GaSb during heat treatment. The Au peak in RBS spectra disappeared and the spectra became smooth when the ohmic contact was formed.

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

    SciTech Connect

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

    2005-03-19

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

  15. Amorphous structures of Cu, Ag, and Au nanoclusters from first principles calculations

    NASA Astrophysics Data System (ADS)

    Oviedo, J.; Palmer, R. E.

    2002-12-01

    We have carried out first-principles density functional calculations for clusters of the coinage metals containing thirteen atoms (M13, where M=Cu, Ag, or Au). We find that for this geometric "magic number" the low energy isomers are actually disordered, forming almost a continuous distribution as a function of energy.

  16. Magnetic properties of CeTxGa4-x (T=Cu, Ag) single crystals

    NASA Astrophysics Data System (ADS)

    Oe, Kenta; Kawamura, Yukihiro; Nishioka, Takashi; Kato, Harukazu; Matsumura, Masahiro; Kodama, Kazuto

    2010-01-01

    We have succeeded in growing single crystals of BaAl4-type CeTGa3 (T = Cu, Ag) by Ga self-flux method for the first time. In spite of several starting compositions, the resulting single crystals have partial replacement of T sites (2a sites) with Ga and their compositions are always the same, i.e., CeCu0.8Ga3.2 and CeAg0.7Ga3.3. For both compounds, a step like increase is observed at the low field in M(H) of a-axis at 1.8 K in addition to the strong enhancement below 5 K in M(T). The magnetic susceptibilities can be well explained by the crystalline electric field model. On the other hand, in p(T), distinct kinks are shown at 4.8 K for CeCu0.8Ga3.2 and at 3.9 K for CeAg0.7Ga3.3, but no clear -logT term are shown for both compounds. These results indicate that CeCu0.8Ga3.2 and CeAg0.7Ga3.3 are localized ferromagnets, which have easy axes of magnetization along a-axes, with the Curie temperature being 4.8 K and 3.9 K, respectively.

  17. Single naphthalene and anthracene molecular junctions using Ag and Cu electrodes in ultra high vacuum

    NASA Astrophysics Data System (ADS)

    Fujii, Shintaro; Kaneko, Satoshi; Chenyang, Liu; Kiguchi, Manabu

    2015-11-01

    We present a charge transport study on single naphthalene and anthracene molecular junctions wired into Ag and Cu electrodes using mechanically controllable break junction technique at 100 K under ultra-high vacuum condition. In particular we focus on effect of metal-? interaction on the formation probability of the molecular junctions. We found that the single molecular junctions of the acene molecules (e.g. naphthalene and anthracene) exhibit highly conductive character below 0.2 G0 (G0 = 2e2/h). The acene molecular junctions displayed formation probability of ca. 20% for Ag system and >40% for Cu system. The high formation probability of the molecular junctions with respect to benzene/Au junctions can be qualitatively explained by size effect, in which larger molecules of the naphthalene and anthracene can effectively bridge the gap between metal electrodes compared with small molecule such as benzene. The acene/Cu junctions displayed higher formation probability than the acene/Ag junctions. This result demonstrated that not only the size effect but the degree of the metal-? interaction have to be taken into account to quantitatively evaluate the formation probability of the molecular junctions for Ag and Cu system.

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

    PubMed Central

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Zaicong; Becker, Harry

    2015-07-01

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

  20. Subsurface growth of ultrathin Ni films on Cu(001) surfaces: Photoemission singularity index study

    NASA Astrophysics Data System (ADS)

    Guan, Lixiu; Tao, Junguang

    2016-01-01

    Using photoemission singularity index, we show that interface growth mode can be explored at atomic level for the epitaxial interface. The initial growth of Ni on Cu(001) surface has been demonstrated to be a segregated subsurface Ni layer growth below one Cu capping layer which behaves as a promoter. The observations are interpreted as evidence for interface exchange processes between Cu and Ni atoms. Based on the change of singularity index which is sensitive to the atomic environment, the interfacial density of states (DOS) at the Fermi level responsible for the screening is decreasing with increasing the Ni coverage. The Cu 4s/Ni 3d interfacial hybridization is enhanced on the disordered surface which is attributed to the increased step edge. The interfacial electronic structure change is also explained within the subsurface growth mode.

  1. Giant magnetoresistance in heterogeneous Cu--Co and Ag--Co alloy films (invited)

    SciTech Connect

    Berkowitz, A.E.; Mitchell, J.R.; Carey, M.J.; Young, A.P. Center for Magnetic Recording Research, University of California at San Diego, La Jolla, California 92093 ); Rao, D. ); Starr, A. ); Zhang, S. ); Spada, F.E.; Parker, F.T. ); Hutten, A.; Thomas, G. (Department of Materials Science and Mineral Engineering and National Center for Electron Microscopy, Lawrence Berkeley Laboratory, University of California at Berk

    1993-05-15

    Giant magnetoresistance in sputtered single films of Cu--Co and Ag--Co heterogeneous alloys is discussed. The films consist of Co-rich precipitates in a nonferromagnetic matrix. The Ag--Co films have higher [Delta][rho]/[rho] and [Delta][rho] values than the Cu--Co films, possibly due to less Co dissolved in the Ag matrix. [Delta][rho] scales inversely with precipitate particle size, implying that Co-rich clusters [le]20 A diameter may be most effective for spin dependent scattering. This trend of the data and a phenomenological model suggest that interfacial spin dependent scattering is significantly stronger than the scattering within the Co-rich particles.

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

    SciTech Connect

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

    2014-09-01

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

  3. A Study on the Breakdown Mechanism of an Electroless-Plated Ni(P) Diffusion Barrier for Cu/Sn/Cu 3D Interconnect Bonding Structures

    NASA Astrophysics Data System (ADS)

    Lee, Byunghoon; Jeon, Haseok; Jeon, Seong-Jae; Kwon, Kee-Won; Lee, Hoo-Jeong

    2012-01-01

    This study examined the thermal stability of an electroless-plated Ni(P) barrier layer inserted between Sn and Cu in the bonding structure of Cu/Sn/Cu for three-dimensional (3D) interconnect applications. A combination of transmission electron microscopy (TEM) and scanning electron microscopy allowed us to fully characterize the bonding morphology of the Cu/Ni(P)/Sn/Ni(P)/Cu joints bonded at various temperatures. The barrier suppressed Cu and Sn interdiffusion very effectively up to 300C; however, an interfacial reaction between Ni(P) and Sn led to gradual decomposition into Ni3P and Ni3Sn4. Upon 350C bonding, the interfacial reaction brought about complete disintegration of the barrier in local areas, which allowed unhindered interdiffusion between Cu and Sn.

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

    SciTech Connect

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

    2015-01-01

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

  5. Cu-Ni composition gradient for the catalytic synthesis of vertically aligned carbon nanofibers

    SciTech Connect

    Klein, Kate L; Melechko, Anatoli Vasilievich; Rack, Philip D; Fowlkes, Jason Davidson; Meyer III, Harry M; Simpson, Michael L

    2005-01-01

    The influence of catalyst alloy composition on the growth of vertically aligned carbon nanofibers was studied using Cu-Ni thin films. Metals were co-sputtered onto a substrate to form a thin film alloy with a wide compositional gradient, as determined by Auger analysis. Carbon nanofibers were then grown from the gradient catalyst film by plasma enhanced chemical vapor deposition. The alloy composition produced substantial differences in the resulting nanofibers, which varied from branched structures at 81%Ni-19%Cu to high aspect ratio nanocones at 80%Cu-20%Ni. Electron microscopy and spectroscopy techniques also revealed segregation of the initial alloy catalyst particles at certain concentrations.

  6. Effect of Cu addition on the martensitic transformation of powder metallurgy processed TiNi alloys

    SciTech Connect

    Kim, Yeon-wook; Choi, Eunsoo

    2014-10-15

    Highlights: M{sub s} of Ti{sub 50}Ni{sub 50} powders is 22 C, while M{sub s} of SPS-sintered porous bulk increases up to 50 C. M{sub s} of Ti{sub 50}Ni{sub 40}Cu{sub 20} porous bulk is only 2 C higher than that of the powders. Recovered stain of porous TiNi and TiNiCu alloy is more than 1.5%. - Abstract: Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 30}Cu{sub 20} powders were prepared by gas atomization and their transformation behaviors were examined by means of differential scanning calorimetry and X-ray diffraction. One-step B2B19 transformation occurred in Ti{sub 50}Ni{sub 50} powders, while Ti{sub 50}Ni{sub 30}Cu{sub 20} powders showed B2B19 transformation behavior. Porous bulks with 24% porosity were fabricated by spark plasma sintering. The martensitic transformation start temperature (50 C) of Ti{sub 50}Ni{sub 50} porous bulk is much higher than that (22 C) of the as-solidified powders. However, the martensitic transformation start temperature (35 C) of Ti{sub 50}Ni{sub 30}Cu{sub 20} porous bulk is almost the same as that (33 C) of the powders. When the specimens were compressed to the strain of 8% and then unloaded, the residual strains of Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 30}Cu{sub 20} alloy bulks were 3.95 and 3.7%, respectively. However, these residual strains were recovered up to 1.7% after heating by the shape memory phenomenon.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  8. Influence of Ni and Cu contamination on the superconducting properties of MgB2 filaments

    NASA Astrophysics Data System (ADS)

    Jung, A.; Schlachter, S. I.; Runtsch, B.; Ringsdorf, B.; Fillinger, H.; Orschulko, H.; Drechsler, A.; Goldacker, W.

    2010-09-01

    Technical MgB2 wires usually have a sheath composite consisting of different metals. For the inner sheath with direct contact to the superconducting filament, chemically inert Nb may be used as a reaction barrier and thermal stabilization is provided by a highly conductive metal like Cu. A mechanical reinforcement can be achieved by the addition of stainless steel. In order to illuminate the influence of defects in the reaction barrier, monofilament in situ wires with direct contact between the MgB2 filament and frequently applied reactive sheath metals like Cu, Ni or Monel are studied. Reactions of Mg and B with a Cu-containing sheath lead to Cu-based by-products penetrating the whole filament. Reactions with Ni-containing sheaths lead to Ni-based by-products which tend to remain at the filament-sheath interface. Cu and/or Ni contamination of the filament lowers the MgB2-forming temperature due to the eutectic reaction between Mg, Ni and Cu. Thus, for the samples heat-treated at low temperatures JC and (partly) TC are increased compared to stainless-steel-sheathed wires. At high heat treatment temperatures uncontaminated filaments lead to the highest JC values. From the point of view of broken reaction barriers in real wires, the contamination of the filament with Cu and/or Ni does not necessarily constrain the superconductivity; it may even improve the properties of the wire, depending on the desired application.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    This research analyzed the influence of the electrodeposition ratio of Cu-Ni on the creation of microstructure in Cu-Ni composite electrodeposition, and identified the microstructure generation mechanism with respect to the Cu-Ni electrodeposition ratio. The concentration of CuSO4 in the electrodeposition solution was varied to 0.00, 0.02, 0.04 M to control the electrodeposition ratio of Cu, and the applied voltage was varied to voltages of -0.9, -1.2, -1.5 V, which were applied to control the electrodeposition ratio of Ni. In the composite electrodeposition, Cu ions precipitated intensively at the top of the structure with a short ion diffusion length, and the Ni ions precipitated regularly throughout the entire area charge transferred. Therefore, the structure showed vertically oriented growth when Cu electrodeposition was dominant, and the structure showed isotropic growth when Ni electrodeposition was dominant. On the other hand, Cu ions precipitation concentration at the tip of the grown structure intensified as the height of the structure increased. Therefore, when a structure grows above a certain height, the excess Cu ions precipitate at the top of the grown structure and a cluster structure composed of spherical Cu particles develops. The microstructure produced in the electrodeposition solution with the CuSO4 concentration of 0.04 M had such a high structure generation density and aspect ratio that it was modified to a superhydrophobic surface with a contact angle higher than 150, and it manifested an excellent self-cleaning ability.

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

    PubMed

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

    2013-07-01

    Air-stable bimetallic Cu-Ag nanoparticles in the range of 12-30nm have been synthesized at gram scale by a facile alcohol reduction in the absence of surfactants with the assistance of microwave irradiation. The synthesized nanoparticles were analyzed by x-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning TEM, ultraviolet-visible spectroscopy, x-ray photoelectron spectroscopy and thermogravimetry (TG). The stability of the bimetallic nanoparticles against oxidation was examined by TG and in situ temperature-programmed XRD analyses in the atmosphere. No oxidation of copper was confirmed by XRD after storing for longer than 6 months in the atmosphere at room temperature. No oxidation took place below 118? C and the Cu(200) diffraction peak decreased by only 7% after heating at 100? C for 30min. The oxidation resistance has been ascribed to a Cu core-Ag shell structure, probably owing to the suppressive effect of Ag on the surface through the electronic interaction with Cu and a physical barrier of oxygen. PMID:23732107

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  13. The Role of Lattice Dynamics on The Thermal Properties of Cu-Ni Alloys

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2014-03-01

    We have investigated Cu-Ni alloys with both disorder and order phases in fcc structures to analyze the effect of temperature dependent vibrational thermodynamical properties. The interactions between the atoms in the model systems are defined using an EAM type potential, specifically developed for Cu-Ni alloys. Vibrational thermodynamic functions are determined within the harmonic approximation of lattice dynamics and the vibrational densities of states are calculated using real space Green's function technique. In addition, through ab-initio calculations we have estimated the electronic contributions to set the ground for a comparative discussion. Our results show that the overall characteristics of thermodynamic functions of Cu-Ni alloys of varying concentrations are governed by the lattice vibrations. We will present our results for free energy, heat capacity and entropy of ordered/disordered Cu-Ni alloys with the experimental findings and discuss the electronic, anharmonic and lattice dynamic contributions.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    In this study, the ultrafine structures in Cu-P and Cu-Ni-P alloys have been characterized using a three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM), and the stress relaxation behavior of these alloys has been explored. The results show that low-temperature annealing greatly improved the stress relaxation performance, especially in the Cu-Ni-P alloys. The presence of Ni-P clusters in the Cu-Ni-P alloys has been revealed. The overall improvement in properties has been analyzed in terms of variations in the dislocation density and solute atom cluster density within these materials. It is shown that clusters with small average spacing give rise to significant improvements in the stress relaxation performance, without requiring significant change in the dislocation density.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  17. Laser Controllable Growth of Graphene via Ni-Cu Alloy Composition Modulation

    NASA Astrophysics Data System (ADS)

    Ye, Xiaohui; Lin, Zhe; Zhang, Hongjun; Zhu, Hongwei; Zhong, Minlin

    2015-12-01

    Graphene has many unique properties, most of them strongly depend on the number of layers. It is significant to develop a facile approach to realize the controllable growth of graphene with specific number of layers. We ever reported an efficient approach to grow graphene rapidly and locally by laser irradiation. In this work, we offers yet another important feature, to control the number of layers of graphene. Ni-Cu alloy has been reported to be used successfully as the catalyst for graphene growth with controllable number of layers. In that case, the Ni-Cu alloys with different compositions were normally formed by thermal evaporation. Here we provide an efficient way to fabricate the Ni-Cu alloy catalysts by laser cladding. Then the high power laser was employed to melt the Ni and Cu mixed powders. Different Ni-Cu alloy catalysts were formed in a high rate of 720 mm2/min with a thickness of 1.2 mm. Then the graphene with controllable layers was rapidly and locally grown on the Ni-Cu catalysts by laser irradiation at a high rate (18 cm2/min) at room temperature. We found that the Ni-Cu catalyst with 15 % Cu could be helpful to grow single layer graphene, which occupied 92.4 % of the entire film. Higher Cu content didn't promote the growth due to the oxygen involved during the growth process. The controllable growth mechanism of graphene by laser processing was discussed. Combining the rapid catalyst fabrication and graphene synthesis make it a cost- and time-efficient method to produce the controllable graphene films.

  18. High resolution electron microscopy study of a high Cu variant of Weldalite (tm) 049 and a high strength Al-Cu-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Herring, R. A.; Gayle, Frank W.; Pickens, Joseph R.

    1991-01-01

    Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy that is strengthened in artificially aged tempers primarily by very thin plate-like precipitates lying on the set of (111) matrix planes. This precipitate might be expected to be the T(sub 1) phase, Al2CuLi, which has been observed in Al-Cu-Li alloys. However, in several ways this precipitate is similar to the omega phase which also appears as the set of (111) planes plates and is found in Al-Cu-Ag-Mg alloys. The study was undertaken to identify the set of (111) planes precipitate or precipitates in Weldalite (trademark) 049 in the T8 (stretched and artificially aged) temper, and to determine whether T(sub 1), omega, or some other phase is primarily responsible for the high strength (i.e., 700 MPa tensile strength) in this Al-Cu-Li-Ag-Mg alloy.

  19. Facile synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires in hydrophobic solution in the presence of nickel and chloride ions

    NASA Astrophysics Data System (ADS)

    Guo, Huizhang; Chen, Yuanzhi; Ping, Hemei; Jin, Jiarui; Peng, Dong-Liang

    2013-02-01

    A highly shape selective synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires has been developed by modulating the coordination chemistry of transition metal ions with a trioctylphosphine (TOP)-Cl- ligand pair in oleylamine under mild organic solvent conditions. The as-prepared nanocubes have a face-centered cubic (fcc) phase and are covered by six {100} facets, whereas the as-prepared nanowires have a multi-twinned structure and grow along the [110] direction. Both the Ni2+ and Cl- ions, along with TOP, play vital roles in determining the final morphology of the as-prepared nanocrystals (NCs). TOP can be used to selectively generate single-crystal seeds at the initial stage, which then grow into nanocubes in the presence of Cl- ions, while the absence of TOP leads to the formation of multi-twined crystal seeds that finally develop into nanowires. Moreover, Ni can be incorporated to form a Cu-Ni alloy shell over a Cu core at higher temperatures in a one-pot process, which makes diamagnetic Cu NCs magnetically responsive and has a significant influence on their optical properties.A highly shape selective synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires has been developed by modulating the coordination chemistry of transition metal ions with a trioctylphosphine (TOP)-Cl- ligand pair in oleylamine under mild organic solvent conditions. The as-prepared nanocubes have a face-centered cubic (fcc) phase and are covered by six {100} facets, whereas the as-prepared nanowires have a multi-twinned structure and grow along the [110] direction. Both the Ni2+ and Cl- ions, along with TOP, play vital roles in determining the final morphology of the as-prepared nanocrystals (NCs). TOP can be used to selectively generate single-crystal seeds at the initial stage, which then grow into nanocubes in the presence of Cl- ions, while the absence of TOP leads to the formation of multi-twined crystal seeds that finally develop into nanowires. Moreover, Ni can be incorporated to form a Cu-Ni alloy shell over a Cu core at higher temperatures in a one-pot process, which makes diamagnetic Cu NCs magnetically responsive and has a significant influence on their optical properties. Electronic supplementary information (ESI) available: Related synthetic details, SEM images, TEM images, EDS spectra, size-distribution histogram, color photos at different reaction stages, UV-Vis spectra, Auger spectra and magnetic measurement results. See DOI: 10.1039/c3nr33142c

  20. Improved Wetting Characteristics in TiO2Modified Ag-CuO Air Braze Filler Metals

    SciTech Connect

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

    2006-01-01

    In this paper we report on the results of a series of sessile drop experiments designed to examine the effect of TiO2 on the wetting behavior of Ag-CuO air braze filler metals. It was found that TiO2 concentrations as small as 0.5 mol% can significantly decrease the contact angle of Ag-CuO on alumina over a compositional range of 1 34mol% CuO. The effect appears to maximize at a copper oxide concentration of ~4 mol% CuO regardless of the titania content.

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

    PubMed

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

    2016-01-01

    Structural design and catalyst screening are two most important factors for achieving exceptional electrocatalytic performance. Herein we demonstrate that constructing a three-dimensional (3D) porous Ni-Cu alloy film is greatly beneficial for improving the hydrazine oxidation reaction (HzOR) performance. A facile electrodeposition process is employed to synthesize a Ni-Cu alloy film with a 3D hierarchical porous structure. As an integrated electrode for HzOR, the Ni-Cu alloy film exhibits superior catalytic activity and stability to the Ni or Cu counterparts. The synthesis parameters are also systematically tuned for optimizing the HzOR performance. The excellent HzOR performance of the Ni-Cu alloy film is attributed to its high intrinsic activity, large electrochemical specific surface area, and 3D porous architecture which offers a "superaerophobic" surface to effectively remove the gas product in a small volume. It is believed that the Ni-Cu alloy film electrode has potential application in direct hydrazine fuel cells as well as other catalytic fields. PMID:26676885

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  3. Interfaces in La2NiO4- La2CuO4 superlattices

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

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

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

    PubMed

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

    2014-02-14

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

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

    SciTech Connect

    Fiddy, Steven; Petranovskii, Vitalii; Ogden, Steve; Iznaga, Inocente Rodriguez

    2007-02-02

    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.

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

    SciTech Connect

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

    2014-03-28

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

  7. The biocompatibility of a dental Ag-Pd-Cu-Au-based casting alloy and its structural components.

    PubMed

    Niemi, L; Syrjnen, S; Hensten-Pettersen, A

    1985-01-01

    The biocompatibility of type III casting gold alloy, an Ag-Pd-Cu-Au-based dental casting alloy and its two main structural components, a CuPd-rich and an Ag-rich phase, was studied after subcutaneous implantation for 7 weeks in 20 guinea pigs. The Ag-Pd-Cu-Au alloy was surrounded by a capsule of immature collagen with fibroblasts and an increased vascular supply. The CuPd-rich component induced and maintained an acute inflammation with highly vascularized granulation tissue. The tissue reaction to the Ag-rich component and the Au-based alloy was slight. Ten of the guinea pigs were sensitized to PdCl2 prior to the implantation period, but this caused no enhanced tissue reaction, except for an increase in the number of mast cells around three of the alloys. PMID:4066727

  8. Ag-Cu nanoalloyed film as a high-performance cathode electrocatalytic material for zinc-air battery

    NASA Astrophysics Data System (ADS)

    Lei, Yimin; Chen, Fuyi; Jin, Yachao; Liu, Zongwen

    2015-04-01

    A novel Ag50Cu50 film electrocatalyst for oxygen reduction reaction (ORR) was prepared by pulsed laser deposition (PLD) method. The electrocatalyst actually is Ag-Cu alloyed nanoparticles embedded in amorphous Cu film, based on transmission electron microscopy (TEM) characterization. The rotating disk electrode (RDE) measurements provide evidence that the ORR proceed via a four-electron pathway on the electrocatalysts in alkaline solution. And it is much more efficient than pure Ag catalyst. The catalytic layer has maximum power density of 67 mW cm-2 and an acceptable cell voltage at 0.863 V when current densities increased up to 100 mA cm-2 in the Ag50Cu50-based primary zinc-air battery. The resulting rechargeable zinc-air battery exhibits low charge-discharge voltage polarization of 1.1 V at 20 mAcm-2 and high durability over 100 cycles in natural air.

  9. Ag-Cu nanoalloyed film as a high-performance cathode electrocatalytic material for zinc-air battery.

    PubMed

    Lei, Yimin; Chen, Fuyi; Jin, Yachao; Liu, Zongwen

    2015-01-01

    A novel Ag50Cu50 film electrocatalyst for oxygen reduction reaction (ORR) was prepared by pulsed laser deposition (PLD) method. The electrocatalyst actually is Ag-Cu alloyed nanoparticles embedded in amorphous Cu film, based on transmission electron microscopy (TEM) characterization. The rotating disk electrode (RDE) measurements provide evidence that the ORR proceed via a four-electron pathway on the electrocatalysts in alkaline solution. And it is much more efficient than pure Ag catalyst. The catalytic layer has maximum power density of 67mWcm(-2) and an acceptable cell voltage at 0.863V when current densities increased up to 100mAcm(-2) in the Ag50Cu50-based primary zinc-air battery. The resulting rechargeable zinc-air battery exhibits low charge-discharge voltage polarization of 1.1V at 20 mAcm(-2) and high durability over 100cycles in natural air. PMID:25977668

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  11. Phase evolution in an Al?.?CrFeCoNiCu High Entropy Alloy

    E-print Network

    Jones, N. G.; Izzo, R.; Mignanelli, P. M.; Christofidou, K. A.; Stone, H. J.

    2015-01-01

    The phase evolution of an Al?.?CrFeCoNiCu High Entropy Alloy has been characterised following isothermal exposures between 0.1 and 1000 hours at temperatures of 700, 800 and 900?C. The NiAl based B2 phase formed extremely quickly, within 0.1 hours...

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

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    The role of "deuteric" fluids (exsolved magmatic volatile phases) in the development of Ni-Cu-PGE (platinum group element) deposits in mafic-ultramafic igneous systems is poorly understood. Although considerable field evidence demonstrates unambiguously that fluids modified most large primary Ni-Cu-PGE concentrations, models which hypothesize that fluids alone were largely responsible for the economic concentration of the base and precious metals are not widely accepted. Determination of the trace element composition of magmatic volatile phases in such ore-forming systems can offer considerable insight into the origin of potentially mineralizing fluids in such igneous environments. Laser ablation ICP-MS microanalysis allows researchers to confirm the original metal budget of magmatic volatile phases and quantify the behavior of trace ore metals in the fluid phase in the absence of well-constrained theoretical or experimental predictions of ore metal solubility. In this study, we present new evidence from major deposits (Sudbury, Ontario, Canada; Stillwater Complex, Montana, U.S.A.) that compositionally distinct magmatic brines and halide melt phases were exsolved from crystallizing residual silicate melt and trapped within high-T fluid conduits now comprised of evolved rock compositions (albite-quartz graphic granite, orthoclase-quartz granophyre). Petrographic evidence demonstrates that brines and halide melts coexisted with immiscible carbonic phases at the time of entrapment (light aliphatic hydrocarbons, CO2). Brine and halide melt inclusions are rich in Na, Fe, Mn, K, Pb, Zn, Ba, Sr, Al and Cl, and homogenize by either halite dissolution at high T ( 450-700 C) or by melting of the salt phase (700-800 C). LA-ICPMS analyses of single inclusions demonstrate that high salinity volatile phases contained abundant base metals (Cu, Fe, Sn, Bi) and precious metals (Pt, Pd, Au, Ag) at the time of entrapment. Notably, precious metal concentrations in the inclusions are comparable to and often exceed the economic concentrations of the metals within the ores themselves. As a consequence of these results, current genetic models must be revised to consider the role played by hydrous saline melts and magmatic brines in deposit development, and the potential for interaction and competition between sulfide liquids (or PGE-bearing sulfide minerals) and hydrosaline volatiles for available PGE and Au in a crystallizing mafic igneous system must be critically evaluated.

  13. Formation of M-C?C-Cl (m = ag or Cu) and Characterization by Rotational Spectroscopy

    NASA Astrophysics Data System (ADS)

    Zaleski, Daniel P.; Tew, David Peter; Walker, Nick; Legon, Anthony

    2015-06-01

    The new linear molecule Ag-C?C-Cl has been detected and characterized by means of rotational spectroscopy. It was synthesized by laser ablation of a slver rod in the presence of a gaseous sample containing a low concentration of CCl4 in argon, cooled to a rotational temperature approaching 2 K through supersonic expansion and analyzed by chirped pulse Fourier transform microwave spectroscopy. Substitution coordinates are available for the silver and chlorine positions and will be compared to ab initio calculations at the CCSD(T)/aug-cc-pV5Z level of theory. The Ag-13C?13C-Cl isotopologue was also observed using a similar gas mixture containing 13CCl4. The Cu analogue Cu-C?C-Cl was similarly identified and characterized.

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

    USGS Publications Warehouse

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

    1994-01-01

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

  15. Structure and bonding of isoleptic coinage metal (Cu, Ag, Au) dimethylaminonitrenes in the gas phase.

    PubMed

    Fedorov, Alexey; Couzijn, Erik P A; Nagornova, Natalia S; Boyarkin, Oleg V; Rizzo, Thomas R; Chen, Peter

    2010-10-01

    Dimethylaminonitrene complexes of IMesM(+) (IMes =1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene; M = Cu, Ag, Au) were prepared in the gas phase and structurally characterized by high-resolution infrared spectroscopy of the cold species, ion-molecule reactions, and DFT computations. We measured the binding energies of the nitrene fragment to the IMesM(+) moiety by energy-resolved collision-induced dissociation experiments in the gas phase, affording a trend in bond strength of M = Cu ? Au > Ag. This trend is explained in terms of a detailed metal-nitrogen bonding analysis, from which relativistic effects on the bonding were assessed. Various density functionals were evaluated for reproducing the observed thermochemical data and Truhlar's M06 functional was found to give the best agreement. PMID:20843043

  16. Bonding in Cu, Ag, and Au Clusters: Relativistic Effects, Trends, and Surprises

    NASA Astrophysics Data System (ADS)

    Hkkinen, Hannu; Moseler, Michael; Landman, Uzi

    2002-06-01

    Electronic structure and bonding in anionic coinage metal clusters are investigated via density-functional calculations, focusing on an extensive set of isomers of Cu-7, Ag-7, and Au-7. While the ground states of Cu-7 and Ag-7 are three dimensional (3D), that of Au-7 is planar, separated from the optimal 3D isomer by 0.5 eV. The simulated thermally weighted photoabsorption spectrum of Au-7 is dominated by planar structures, and it agrees well with the measured one. The propensity of Au-N clusters to favor planar structures (with N as large as 13) is correlated with strong hybridization of the atomic 5d and 6s orbitals due to relativistic effects.

  17. Nanostructured YbAgCu4 for potentially cryogenic thermoelectric cooling.

    PubMed

    Koirala, Machhindra; Wang, Hui; Pokharel, Mani; Lan, Yucheng; Guo, Chuanfei; Opeil, Cyril; Ren, Zhifeng

    2014-09-10

    We have studied the thermoelectric properties of nanostructured YbAgCu4 materials. A high power factor of ?131 ?W cm(-1) K(-2) has been obtained at 22 K for nanostructured samples prepared by ball milling the arc melted ingot into nanopowder and hot pressing the nanopowder. The implementation of nanostructuring method decreased the thermal conductivity at 42 K by 30-50% through boundary scattering comparing with the previously reported value of polycrystalline YbAgCu4. A peak dimensionless thermoelectric figure-of-merit, ZT, of 0.11 has been achieved at 42 K, which may find potential applications for cryogenic cooling below 77 K. The nanostructuring approach can be extended to other heavy Fermion materials to achieve high power factor and low thermal conductivity and ultimately higher ZT. PMID:25079115

  18. Achieving high strength and high electrical conductivity in Ag/Cu multilayers

    NASA Astrophysics Data System (ADS)

    Wei, M. Z.; Xu, L. J.; Shi, J.; Pan, G. J.; Cao, Z. H.; Meng, X. K.

    2015-01-01

    In this work, we investigated the microstructure evolution of Ag/Cu multilayers and its influences on the hardness and electric resistivity with individual layer thickness (h) ranging from 3 to 50 nm. The hardness increases with the decreasing h in the range of 5-20 nm. The barrier to dislocation transmission by stacking faults, twin boundaries, and interfaces leads to hardness enhancement. Simultaneously, in order to get high conductivity, the strong textures in-layers were induced to form for reducing the amount of grain boundaries. The resistivity keeps low even when h decreases to 10 nm. Furthermore, we developed a facile model to evaluate the comprehensive property of Ag/Cu multilayersthe results indicate that the best combination of strength and conductivity occurs when h = 10 nm.

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

    DOEpatents

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

    1997-01-01

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

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

    PubMed Central

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

    2014-01-01

    Oxidation of phenols by heterodinuclear CuIII(?-O)2NiIII complexes containing nucleophilic oxo groups occurs by both proton coupled electron transfer (PCET) and hydrogen atom transfer (HAT) mechanisms; the exact mechanism depends on the nature of the phenol as well as the substitution pattern of the ligand bound to Cu. PMID:24362244

  1. Effect of Ni on the Formation and Growth of Primary Cu6Sn5 Intermetallics in Sn-0.7 wt.%Cu Solder Pastes on Cu Substrates During the Soldering Process

    NASA Astrophysics Data System (ADS)

    Mohd Salleh, M. A. A.; McDonald, S. D.; Gourlay, C. M.; Belyakov, S. A.; Yasuda, H.; Nogita, K.

    2015-10-01

    This paper investigates the effect of 0.05 wt.% Ni on the formation and growth of primary Cu6Sn5 in Sn-0.7 wt.%Cu solder paste soldered on a Cu substrate, using a real-time synchrotron imaging technique. It was found that small additions of Ni significantly alter the formation and growth of the primary Cu6Sn5 intermetallics, making them small. In contrast, without Ni, primary Cu6Sn5 intermetallics tend to continue growth throughout solidification and end up much larger and coarser. The primary effect of the Ni addition appears to be in promoting the nucleation of a larger amount of small Cu6Sn5. The results provide direct evidence of the sequence of events in the reaction of Ni-containing Sn-0.7 wt.%Cu solder paste with a Cu substrate, and in particular the formation and growth of the primary Cu6Sn5 intermetallic.

  2. Electromigration induced Kirkendall void growth in Sn-3.5Ag/Cu solder joints

    SciTech Connect

    Jung, Yong; Yu, Jin

    2014-02-28

    Effects of electric current flow on the Kirkendall void formation at solder joints were investigated using Sn-3.5Ag/Cu joints specially designed to have localized nucleation of Kirkendall voids at the Cu{sub 3}Sn/Cu interface. Under the current density of 1??10{sup 4}?A/cm{sup 2}, kinetics of Kirkendall void growth and intermetallic compound thickening were affected by the electromigration (EM), and both showed the polarity effect. Cu{sub 6}Sn{sub 5} showed a strong susceptibility to the polarity effect, while Cu{sub 3}Sn did not. The electromigration force induced additional tensile (or compressive) stress at the cathode (or anode), which accelerated (or decelerated) the void growth. From the measurements of the fraction of void at the Cu{sub 3}Sn/Cu interface on SEM micrographs and analysis of the kinetics of void growth, the magnitude of the local stress induced by EM was estimated to be 9?MPa at the anode and ?7 MPa at the cathode.

  3. [Determination of Ag, Cu, Zn and Cd in silver brazing filler metals by ICP-AES].

    PubMed

    Yang, X

    1997-06-01

    A method of simultaneous and direct determination for Ag, Cu, Zn and Cd in silver brazing filler metals by ICP-AES is reported. The spectral interferences and effect of acidity have been investigated. Working conditions were optimized. The method has been applied to the analysis of silver brazing filler metals with RSD of 4-7% and recovery of 94-105%. This method was accurate, simple and rapid. PMID:15810223

  4. Enhancement of anammox performance by Cu(II), Ni(II) and Fe(III) supplementation.

    PubMed

    Chen, Hui; Yu, Jin-Jin; Jia, Xiu-Ying; Jin, Ren-Cun

    2014-12-01

    This study explored the influence of metal ion addition on specific anaerobic ammonium oxidation activity (SAA). Batch assays were used to demonstrate the enhancement of the SAA upon the addition of Cu2+, Ni2+ and Fe3+. The SAA was enhanced by 41.0% when the Cu2+ concentration was below 1 mg L?1, while it was improved by 63.5% at Ni2+ concentrations below 1.74 mg L?1. An enhancement of 533.2% was obtained when 3.68 mg L?1 Fe3+ was supplied. The effects of Fe3+, Cu2+ and Ni2+ on the SAA were analyzed and optimized by a response surface methodology, which demonstrated that the interaction between Fe3+ and Cu2+ was significant and that 6.61 mg Fe3+ L?1, 1.18 mg Cu2+ L?1 and 1.11 mg Ni2+ L?1 were the optimal values for metal dosing. Subsequently, an Fe3+Cu2+Ni2+ continuous test was carried out under optimal conditions and revealed that the addition of Fe3+, Cu2+ and Ni2+ could stimulate the reactor potential at ambient temperature. The maximum nitrogen removal rate (NRR) of the test reactor was 52.8% higher than that of the control reactor (8.1 versus 5.3 kg N m?3 d?1). Moreover, a continuous test conducted by adding Fe3+ achieved an average nitrogen removal efficiency and maximum NRR of 67.4% and 4.9 kg N m?3 d?1, respectively, while the corresponding values of the control test were 64.7% and 4.1 kg N m?3 d?1, respectively. Altogether, appropriate dosages of Cu2+, Ni2+ and Fe3+ can significantly enhance the SAA and improve the reactor capacity at ambient temperature. PMID:25461925

  5. Structural evolution of Ag-Cu nano-alloys confined between AlN nano-layers upon fast heating.

    PubMed

    Janczak-Rusch, J; Chiodi, M; Cancellieri, C; Moszner, F; Hauert, R; Pigozzi, G; Jeurgens, L P H

    2015-11-14

    The structural evolution of a Ag-Cu/AlN nano-multilayer (NML), as prepared by magnetron-sputtering on a ?-Al2O3 substrate, was monitored during fast heating by real-time in situ XRD analysis (at the synchrotron), as well as by ex situ microstructural analysis using SEM, XPS and in-house XRD. The as-deposited NML is constituted of alternating nano-layers (thickness ? 10 nm) of a chemically inert AlN barrier and a eutectic Ag-Cu40at% nano-alloy. The nano-alloy in the as-deposited state is composed of a fcc matrix of Ag nano-grains (?6 nm), which are supersaturated by Cu, and some smaller embedded Cu rich nano-grains (?4 nm). Heating up to 265 C activates segregation of Cu out of the supersaturated Ag nano-grains phase, thus initiating phase separation. At T > 265 C, the phase-separated Cu metal partially migrates to the top NML surface, thereby relaxing thermally-accumulated compressive stresses in the confined alloy nano-layers and facilitating grain coarsening of (still confined) phase-separated nano-crystallites. Further heating and annealing up to 420 C results in complete phase separation, forming extended Ag and Cu domains with well-defined coherent Ag/AlN interfaces. The observed outflow of Cu well below the eutectic melting point of the bulk Ag-Cu alloy might provide new pathways for designing low-temperature nano-structured brazing materials. PMID:25914094

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

    SciTech Connect

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

    2006-01-01

    This paper reports on the effects of palladium on the liquidus/solidus temperatures and wetting behavior of a series of Ag-CuOx air braze filler metals. Currently, the maximum operating temperature of the Ag-CuOx system is limited by its eutectic temperature of ~935C. 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.

  7. Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial AgCu nanoparticles

    SciTech Connect

    Taner-Camc?, Merve; Suzer, Sefik

    2014-03-15

    Ultrathin films consisting of polyelectrolyte layers prepared by layer-by-layer deposition technique and containing also Ag and Cu nanoparticles exhibit superior antibacterial activity toward Escherichia coli. These films have been investigated with XPS measurements under square wave excitation at two different frequencies, in order to further our understanding about the chemical/physical nature of the nanoparticles. Dubbed as dynamical XPS, such measurements bring out similarities and differences among the surface structures by correlating the binding energy shifts of the corresponding XPS peaks. Accordingly, it is observed that the Cu2p, Ag3d of the metal nanoparticles, and S2p of cysteine, the stabilizer and the capping agent, exhibit similar shifts. On the other hand, the C1s, N1s, and S2p peaks of the polyelectrolyte layers shift differently. This finding leads us the claim that the Ag and Cu atoms are in a nanoalloy structure, capped with cystein, as opposed to phase separated entities.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Kumar, Aditya; Chen, Zhong

    2011-02-01

    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.

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

    SciTech Connect

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

    2013-05-21

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

  12. Photocatalytic performances and activities of Ag-doped CuFe{sub 2}O{sub 4} nanoparticles

    SciTech Connect

    Zhu, Zhengru; Li, Xinyong; Zhao, Qidong; Li, Yonghua; Sun, Caizhi; Cao, Yongqiang

    2013-08-01

    Graphical abstract: - Highlights: CuFe{sub 2}O{sub 4} nanocrystals were synthesized by a co-precipitation method. Ag/CuFe{sub 2}O{sub 4} catalyst was prepared by the wetness impregnation strategy. The structural properties of Ag/CuFe{sub 2}O{sub 4} were investigated by XRD, TEM, DRS, and XPS techniques. Ag/CuFe{sub 2}O{sub 4} has higher photocatalytic activity. - Abstract: In this work, CuFe{sub 2}O{sub 4} nanoparticles were synthesized by a chemical co-precipitation route. The Ag/CuFe{sub 2}O{sub 4} catalyst was prepared based on the CuFe{sub 2}O{sub 4} nanoparticles by the incipient wetness impregnation strategy, which showed excellent photoelectric property and catalytic activity. The structural properties of these samples were systematically investigated by X-ray powder diffraction (XRD), transmission electronic microscopy (TEM), UVvis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) techniques. The photo-induced charge separation in the samples was demonstrated by surface photovoltage (SPV) measurement. The photocatalytic degradation of 4-CP by the Ag/CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4} samples were comparatively studied under xenon lamp irradiation. The results indicate that the Ag/CuFe{sub 2}O{sub 4} sample exhibited the higher efficiency for the degradation of 4-CP.

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

    NASA Technical Reports Server (NTRS)

    Lach, Cynthia L.; Domack, Marcia S.

    2003-01-01

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

  14. A density functional global optimisation study of neutral 8-atom Cu-Ag and Cu-Au clusters

    NASA Astrophysics Data System (ADS)

    Heard, Christopher J.; Johnston, Roy L.

    2013-02-01

    The effect of doping on the energetics and dimensionality of eight atom coinage metal subnanometre particles is fully resolved using a genetic algorithm in tandem with on the fly density functional theory calculations to determine the global minima (GM) for Cu n Ag(8- n) and Cu n Au(8- n) clusters. Comparisons are made to previous ab initio work on mono- and bimetallic clusters, with excellent agreement found. Charge transfer and geometric arguments are considered to rationalise the stability of the particular permutational isomers found. An interesting transition between three dimensional and two dimensional GM structures is observed for copper-gold clusters, which is sharper and appears earlier in the doping series than is known for gold-silver particles.

  15. Electrochemical performance and carbon deposition resistance of M-BaZr?.?Ce?.?Y?.?Yb?.?O??? (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells.

    PubMed

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

    2015-01-01

    Pd-, Cu-, Ni- and NiCu-BaZr?.?Ce?.?Y?.?Yb?.?O??? anodes, designated as M-BZCYYb, were prepared by impregnating M-containing solution into BZCYYb scaffold, and investigated in the aspects of electrocatalytic activity for the reactions of H? and CH? oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (R?) and polarization (RP) losses of BZCYYb anode exposed to H? or CH?, while Cu impregnation decreased only R? in H? and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3?mol. % H?O) CH? at 750C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750C for 12?h, and not observed in NiCu-BZCYYb exposed to dry CH? at 750C for 24?h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La?.?Sr?.?Co?.?Fe?.?O???-Gd doped CeO? (LSCF-GDC) cathode was stable at 750C in wet CH? for 130?h, indicating that NiCu-BZCYYb is a promising anode for direct CH? solid oxide fuel cells (SOFCs). PMID:25563843

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

    SciTech Connect

    Ranganatha, S.; Venkatesha, T.V.; Vathsala, K.

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The Ni-P and Ni-P-Cu-ZrO{sub 2} coatings were produced by electroless technique. Black-Right-Pointing-Pointer The influence of copper and ZrO{sub 2} nanoparticles on Ni-P was studied. Black-Right-Pointing-Pointer Surface morphology, structure and electrochemical behavior were evaluated. Black-Right-Pointing-Pointer The Ni-Cu-P-ZrO{sub 2} and Ni-P-ZrO{sub 2} coatings are more resistant to corrosion than Ni-P. Black-Right-Pointing-Pointer Introduction of Cu and ZrO{sub 2} in the matrix aids to the enhancement of microhardness. -- Abstract: Electroless Ni-Cu-P-ZrO{sub 2} composite coating was successfully obtained on low carbon steel matrix by electroless plating technique. Coatings with different compositions were obtained by varying copper as ternary metal and nano sized zirconium oxide particles so as to obtain elevated corrosion resistant Ni-P coating. Microstructure, crystal structure and composition of deposits were analyzed by SEM, EDX and XRD techniques. The corrosion behavior of the deposits was studied by anodic polarization, Tafel plots and electrochemical impedance spectroscopy (EIS) in 3.5% sodium chloride solution. The ZrO{sub 2} incorporated Ni-P coating showed higher corrosion resistance than plain Ni-P. The introduction of copper metal into Ni-P-ZrO{sub 2} enhanced the protection ability against corrosion. The influence of copper metal and nanoparticles on microhardness of coatings was evaluated.

  17. Crystallization of amorphous Ni?Cu?B alloys obtained by electroless plating

    NASA Astrophysics Data System (ADS)

    Hu, Wangyu; Wu, Lijun; Wang, Lingling; Zhang, Bangwei; Guan, Hengrong

    Ni 78- xCu xB 22( x = 0-8.0 at%) amorphous alloys are prepared by electroless plating. The microstructure and kinetics of the crystallization are discussed. The phase transition of Ni 72.9Cu 5.1B 22 amorphous alloy includes a two-step process of crystallization and decomposition process of metastable phase. With increase of copper content, the single large granula in lower copper content alloy changes to a cluster of small granulas; the crystallization temperature and activation energy for crystallization obtained from the first DTA exothermic peak increase first and decrease later. The substitution of Ni by Cu can improve the thermal stability to a certain extent, but the improvement is much less than the replacement of Ni by Si and Al.

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

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukano?lu, Sondan

    2014-11-01

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

  19. Facile synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires in hydrophobic solution in the presence of nickel and chloride ions.

    PubMed

    Guo, Huizhang; Chen, Yuanzhi; Ping, Hemei; Jin, Jiarui; Peng, Dong-Liang

    2013-03-21

    A highly shape selective synthesis of Cu and Cu@Cu-Ni nanocubes and nanowires has been developed by modulating the coordination chemistry of transition metal ions with a trioctylphosphine (TOP)-Cl(-) ligand pair in oleylamine under mild organic solvent conditions. The as-prepared nanocubes have a face-centered cubic (fcc) phase and are covered by six {100} facets, whereas the as-prepared nanowires have a multi-twinned structure and grow along the [110] direction. Both the Ni(2+) and Cl(-) ions, along with TOP, play vital roles in determining the final morphology of the as-prepared nanocrystals (NCs). TOP can be used to selectively generate single-crystal seeds at the initial stage, which then grow into nanocubes in the presence of Cl(-) ions, while the absence of TOP leads to the formation of multi-twined crystal seeds that finally develop into nanowires. Moreover, Ni can be incorporated to form a Cu-Ni alloy shell over a Cu core at higher temperatures in a one-pot process, which makes diamagnetic Cu NCs magnetically responsive and has a significant influence on their optical properties. PMID:23400550

  20. Microstructural development and solidification cracking susceptibility of Cu deposits on steel: Part II--use of a Ni

    E-print Network

    DuPont, John N.

    to 75 wt% Ni, and NiCu deposits were fabricated using the Gas Tungsten Arc Welding (GTAW) process times and increased mold productivity. However, copper has been shown by several researchers to promote

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

    SciTech Connect

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

    2012-06-15

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

  2. Effect of chemical fertilizers on the fractionation of Cu, Cr and Ni in contaminated soil

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Duan, Chang-Qun; Zhu, Yi-Nian; Zhang, Xue-Hong; Wang, Cheng-Xian

    2007-08-01

    Effect of chemical fertilizers (urea, NH4Cl, Ca(NO3)2, KCl and KH2PO4) on the fractionation of Cu, Cr and Ni was studied by a 4-month incubation experiment. Using sequential extraction procedure, it was found that the application of fertilizers could change the distribution of Cu, Cr and Ni in the fractions of soil. Applying urea (CO(NH2)2) significantly decreased the concentrations of Cu, Cr and Ni in water soluble plus exchangeable (WE) fraction, but increased those in Fe-Mn oxides bound (FM) fraction ( p < 0.01). However, application of NH4Cl caused an increase in the WE fraction by 27.7% for Cu, 111.5% for Cr and 20.4% for Ni. The CO(NH2)2 raised the soil pH from 4.51 to 4.96, whereas NH4Cl lowered the pH of soil by 0.44 units. The WE fraction of the three heavy metals was significantly increased, while the FM fraction was significantly decreased by adding KCl ( p < 0.01). Moreover, the supply of KH2PO4 reduced the WE and carbonate bound (CB) fractions of Cu, Cr and Ni in the soil, however, it raised Cu and Ni in the residual (RS) fraction and Cr in the FM fraction. In addition, the mobility index indicated that KCl and NH4Cl increased the mobility of Cu, Cr and Ni in the soil, whereas urea and KH2PO4 decreased the mobility of the three metals in the soil. These results suggest that applying chemical fertilizers does not only provide plant nutrients, but may also change the speciation and mobility of heavy metals in the soil.

  3. Dissociative chemisorption dynamics of H2 on Ni and Cu surfaces: Morphology and surface temperature effects

    NASA Astrophysics Data System (ADS)

    Lee, Chyuan-Yih; DePristo, Andrew E.

    1986-10-01

    A new representation of the potential energy surface (PES) for diatomic molecule-solid surface interactions is presented. It is based upon a delocalized effective medium form (i.e., homogeneous gas analogy) plus empirical two-body terms and is transferable from face to face of a crystal. We have determined the parameters for H2-Cu and H2-Ni from experimental measurements of H-Cu and H-Ni adsorption energy, frequency, and height and from limited molecular beam scattering data. The PES for H2-Ni(100), Ni(110), Ni(111), and H2-Cu(110), Cu(100) are presented. A dynamical simulation using the classical trajectory-generalized Langevin equation ``ghost'' atom formalism is implemented in order to calculate the dissociative sticking probability as a function of incident kinetic energy and surface temperature. The calculated probabilities are in general qualitative agreement with those measured experimentally, and are superior to those based upon the previous many-body expansion approach [J. Chem. Phys. 84, 485 (1986)] in the following features: (1) the angular distribution of reflected molecules is more specular, (2) Ni(100) has a barrier for dissociation so that the dissociation probability depends on the translational energy, and (3) the many body expansion approach requires very high order terms for H2-Cu systems. Quantitative agreement is not obtained especially for the surfaces which exhibit barriers to dissociation. The PES for H2-Ni(111) is different from the previous one and suggests an interesting dissociation mechanism. It was also found that the participation of d electrons is essential for the structure sensitivity of the H2 dissociative chemisorption on Ni surfaces. On Cu with a 3d10 4s1 configuration, no promotion of 4s to 3d electrons is possible and much less structure sensitivity is shown.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  5. An Anomalous Internal Oxidation of Dilute Cu-Ni Alloys at 800 C under 1 atm O2

    NASA Astrophysics Data System (ADS)

    Lu, L. Y.; Liu, L. L.; Wang, S.; Niu, Y.

    2012-04-01

    The oxidation of six Cu-xNi alloys (x = 0.2, 0.6, 1, 2, 3, 4 at.%) was studied at 800 C under 1 atm O2. All of the binary Cu-Ni alloys underwent an internal oxidation of Ni in the presence of an external scale of Cu2O and CuO, in agreement with the theoretical expectations for a finite range of Ni contents. However, the behavior of internal oxidation deviates significantly from the classical behavior of internal oxidation described by Wagner, in particular for the absence of a well-defined front of internal oxidation.

  6. Shape coexistence in 67Co, 66,68,70,72Ni, and 71Cu

    NASA Astrophysics Data System (ADS)

    Walters, W. B.; Chiara, C. J.; Janssens, R. V. F.; Weisshaar, D.; Otsuka, T.; Tsunoda, Y.; Recchia, F.; Gade, A.; Harker, J. L.; Albers, M.; Alcorta, M.; Bader, V. M.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bertone, P. F.; Campbell, C. M.; Carpenter, M. P.; Chen, J.; Crawford, H. L.; David, H. M.; Doherty, D. T.; Hoffman, C. R.; Honma, M.; Kondev, F. G.; Korichi, A.; Langer, C.; Larson, N.; Lauritsen, T.; Liddick, S. N.; Lunderberg, E.; Macchiavelli, A. O.; Noji, S.; Prokop, C.; Rogers, A. M.; Seweryniak, D.; Shimizu, N.; Stroberg, S. R.; Suchyta, S.; Utsuno, Y.; Williams, S. J.; Wimmer, K.; Zhu, S.

    2015-10-01

    Analyses of data from both deep inelastic reactions at Argonne National Laboratory and single- and multiple-particle knockout reactions at Michigan State University revealed new ?-ray transitions in even-even 66,68,70,72Ni38,40,42,44 and in 67Co40 that provide strong evidence for multiple shape coexistence at N = 38 and 40 and deep prolate minima in 70Ni42 and isotonic 71Cu42. A new transition at 642 keV is proposed for 66Ni as the prolate 2+ to 0+ transition. Two new transitions in 72Ni at 915 and 1225 keV were identified in the knock-out reaction study and could represent de-population of prolate states. Taken together with recent theoretical work using the Monte Carlo shell model, a well defined region of shape coexistence can be seen existing precisely between 38 ? N ?44 for Co, Ni, and Cu nuclei.

  7. Temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites

    NASA Astrophysics Data System (ADS)

    Lucas, A.; Lebourgeois, R.; Mazaleyrat, F.; Laboure, E.

    2011-03-01

    The temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead to a compensation of the magneto-crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on the cobalt content and the Ni/Zn ratio. We observed similar behaviour in Ni-Zn-Cu and it was found that the core loss goes through a minimum around this magneto-crystalline anisotropy compensation. Moreover, the anisotropy induced by the cobalt allowed a strong decrease of core loss, a ferrite having a core loss of 350 mW/cm3 at 80 C was then developed (measured at 1.5 MHz and 25 mT). This result represents an improvement of a factor 4 compared to the state of art Ni-Zn ferrites.

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

    DOEpatents

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

    1997-04-08

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

  9. Undercooling Behavior and Intermetallic Compound Coalescence in Microscale Sn-3.0Ag-0.5Cu Solder Balls and Sn-3.0Ag-0.5Cu/Cu Joints

    NASA Astrophysics Data System (ADS)

    Zhou, M. B.; Ma, X.; Zhang, X. P.

    2012-11-01

    The microstructure of microscale solder interconnects and soldering defects have long been known to have a significant influence on the reliability of electronic packaging, and both are directly related to the solidification behavior of the undercooled solder. In this study, the undercooling behavior and solidification microstructural evolution of Sn-3.0Ag-0.5Cu solder balls with different diameters (0.76 mm, 0.50 mm, and 0.30 mm) and the joints formed by soldering these balls on Cu open pads of two diameters (0.48 mm and 0.32 mm) on a printed circuit board (PCB) substrate were characterized by differential scanning calorimetry (DSC) incorporated into the reflow process. Results show that the decrease in diameter of the solder balls leads to an obvious increase in the undercooling of the balls, while the undercooling of the solder joints shows a dependence on both the diameter of the solder balls and the diameter ratio of solder ball to Cu pad (i.e., D s/ D p), and the diameter of the solder balls has a stronger influence on the undercooling of the joints than the dimension of the Cu pad. Coarse primary intermetallic compound (IMC) solidification phases were formed in the smaller solder balls and joints. The bulk Ag3Sn IMC is the primary solidification phase in the as-reflowed solder balls. Due to the interfacial reaction and dissolution of Cu atoms into the solder matrix, the primary Ag3Sn phase can be suppressed and the bulk Cu6Sn5 IMC is the only primary solidification phase in the as-reflowed solder joints.

  10. Optimization of Bulk Thermoelectrics: Influence of Cu Insertion in Ag3.6Mo9Se11

    NASA Astrophysics Data System (ADS)

    Colin, Malika; Zhou, Tong; Lenoir, Bertrand; Dauscher, Anne; Al Rahal Al Orabi, Rabih; Gougeon, Patrick; Potel, Michel; Baranek, Philippe; Semprimoschnig, Christopher

    2012-06-01

    Currently, there is a resurgence of interest in thermoelectric materials with enhanced efficiency. Among investigated classes of bulk thermoelectrics such as partially filled skutterudites, Zn4Sb3-based materials, and clathrates, novel polycrystalline Mo9 cluster-based chalcogenides were reported recently. Among those, Chevrel phase-derived Ag y Mo9Se11 (with 3.4 ? y ? 3.9) compounds have shown interesting thermoelectric properties, in particular extremely low thermal conductivity allowing improved thermoelectric efficiency compared with reported Chevrel phases. They also possess a complex crystallographic structure where stacked Mo9Se11 units leave channels occupied by Ag atoms. Analysis of the structural determinants of the thermoelectric properties of Ag y Mo9Se11 suggested that performance improvements could result from further Cu insertion. In this paper, we describe the synthesis route we used for preparing quaternary Ag-Cu-Mo-Se compositions by a combination of powder metallurgy and spark plasma sintering techniques. Characterization by x-ray diffraction, scanning electron microscopy, and electrical and thermal measurements has been performed. The results obtained for two compounds (Ag3.6Cu0.2Mo9Se11 and Ag3.6Cu0.4Mo9Se11) are discussed and compared with those of the parent ternary compound Ag3.6Mo9Se11.

  11. Characterizing the wetting process of Ag films on Cu(111) with the angle-resolved photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Luh, Dah-An; Liu, Kuan-Chun; Cheng, Cheng-Maw; Tsuei, Ku-Ding

    2010-03-01

    Electronic states of a metallic thin film are closely related to its surface morphology. The dynamics in the change of the surface morphology of a metallic thin film can become explored if its electronics states are measured. In this study, we demonstrate that the wetting process of a Ag film on Cu(111) is characterized by monitoring the evolution of its surface states with the angle-resolved photoelectron spectroscopy (ARPES). A Ag film on Cu(111) is disordered when Ag is deposited at low temperature, but it wets on Cu(111) for up to 2 ML when Ag is deposited at and above room temperature. To study the wetting of a Ag film on Cu(111), we constructed a special disordered Ag film, and monitored its layer-resolved surface states with the real-time ARPES during the wetting of the Ag film. The result shows that there exists a transitional state before the wetting is complete, and suggests a two-process model of wetting.

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

    NASA Astrophysics Data System (ADS)

    Pigozzi, Giancarlo; Antuek, Andrej; Janczak-Rusch, Jolanta; Parlinska-Wojtan, Magdalena; Passerone, Daniele; Antonio Pignedoli, Carlo; Bissig, Vinzenz; Patscheider, Jrg; Jeurgens, Lars P. H.

    2012-10-01

    Nano-sized Ag-Cu8nm/AlN10nm multilayers were deposited by reactive DC sputtering on ?-Al2O3(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.

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

    SciTech Connect

    Pigozzi, Giancarlo; Janczak-Rusch, Jolanta; Passerone, Daniele; Antonio Pignedoli, Carlo; Patscheider, Joerg; Jeurgens, Lars P. H.; Antusek, Andrej; Parlinska-Wojtan, Magdalena; Bissig, Vinzenz

    2012-10-29

    Nano-sized Ag-Cu{sub 8nm}/AlN{sub 10nm} multilayers were deposited by reactive DC sputtering on {alpha}-Al{sub 2}O{sub 3}(0001) substrates. Investigation of the phase constitution and interface structure of the multilayers evidences a phase separation of the alloy sublayers into nanosized grains of Ag and Cu. The interfaces between the Ag grains and the quasi-single-crystalline AlN sublayers are semi-coherent, whereas the corresponding Cu/AlN interfaces are incoherent. The orientation relationship between Ag and AlN is constant throughout the entire multilayer stack. These observations are consistent with atomistic models of the interfaces as obtained by ab initio calculations.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    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 Nel 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.

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

    USGS Publications Warehouse

    Alminas, Henry V.

    1975-01-01

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

  16. Resistance to sulfur poisoning of Ni-based alloy with coinage (IB) metals

    NASA Astrophysics Data System (ADS)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2015-12-01

    The poisoning effects of S atom on the (1 0 0), (1 1 0) and (1 1 1) metal surfaces of pure Ni and Ni-based alloy with IB (coinage) metals (Cu, Ag, Au) are systematically studied. The effects of IB metal dopants on the S poisoning features are analyzed combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that introducing IB doping metals into Ni surface can shift the d-band center downward from the Fermi level and weaken the adsorption of S on the (1 0 0) and (1 1 0) surfaces, and the S tolerance ability increases in the order of Ni, Cu/Ni, Ag/Ni and Au/Ni. Nevertheless, on the (1 1 1) surface, the S tolerance ability increases in the order of Ag/Ni (or Cu/Ni), Ni, and Au/Ni. When we increase the coverage of the IB metal dopants, we found that not only Au, but Cu and Ag can increase its S tolerance. We therefore propose that alloying can increase its S tolerance and alloying with Au would be a better way to increase the resistance to sulfur poisoning of the Ni anode as compared with the pure Ni and the Ag- or, Cu-doped Ni materials.

  17. NiCu Alloy Nanoparticle-Loaded Carbon Nanofibers for Phenolic Biosensor Applications.

    PubMed

    Li, Dawei; Lv, Pengfei; Zhu, Jiadeng; Lu, Yao; Chen, Chen; Zhang, Xiangwu; Wei, Qufu

    2015-01-01

    NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs) were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac) and Nafion to form a novel biosensor. NiCuCNFs successfully achieved the direct electron transfer of Lac. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical properties of the biosensor. The finally prepared biosensor showed favorable electrocatalytic effects toward hydroquinone. The detection limit was 90 nM (S/N = 3), the sensitivity was 1.5 A M(-1), the detection linear range was 4 10(-7)-2.37 10(-6) M. In addition, this biosensor exhibited satisfactory repeatability, reproducibility, anti-interference properties and stability. Besides, the sensor achieved the detection of hydroquinone in lake water. PMID:26610505

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  19. Formation of Yb nBa 2 nCu 3 n+1 O x ( n=3, 4) by oxidation of Yb?Ba?Cu?Ag metallic precursors

    NASA Astrophysics Data System (ADS)

    Kogure, T.; Otto, A.; Vander Sande, J. B.

    1989-01-01

    New structural variations on the 1-2-3 type high- Tc superconducting phase have been identified in oxidized Yb?Ba?Cu?Ag metallic precursors in which Yb 2Ba 4Cu 7O x (2-4-7) and Ag are the dominant phases. These new structures are generated by the placement of the copper oxide double layer in every three unit cells of the 1-2-3 structure yielding the chemical composition Yb 3Ba 6Cu 10O x or in every four unit cells yielding Yb 4Ba 8Cu 13O x. These discoveries lead to the conclusion that a large family of superconductors exists whose generic formula is Re nBa 2 nCu 3 n+1 O x, where Re represents rare-earth elements and n is between 1 and ? ( n=? generates the 1-2-3 phase).

  20. Photocatalytic comparison of Cu- and Ag-doped TiO2/GF for bioaerosol disinfection under visible light

    NASA Astrophysics Data System (ADS)

    Pham, Thanh-Dong; Lee, Byeong-Kyu

    2015-12-01

    Photocatalysts, TiO2/glass fiber (TiO2/GF), Cu-doped TiO2/glass fiber (Cu-TiO2/GF) and Ag-doped TiO2/glass fiber (Ag-TiO2/GF), were synthesized by a sol-gel method. They were then used to disinfect Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in bioaerosols under visible light irradiation. TiO2/GF did not show any significant disinfection effect. Both Cu and Ag acted as intermediate agents to enhance separation efficiency of electron-hole pairs of TiO2, leading to improved photocatalytic activity of Cu-TiO2/GF and Ag-TiO2/GF under visible light. Cu in Cu-TiO2/GF acted as a defective agent, increasing the internal quantum efficiency of TiO2, while Ag in Ag-TiO2/GF acted as a sensitive agent, enhancing the transfer efficiency of the electrons generated. The highest disinfection efficiencies of E. coli and S. aureus by Cu-TiO2/GF were 84.85% and 65.21%, respectively. The highest disinfection efficiencies of E. coli and S. aureus by Ag-TiO2/GF were 94.46% and 73.12%, respectively. Among three humidity conditions - 405% (dry), 605% (moderate), and 805% (humid) - the moderate humidity condition showed the highest disinfection efficiency for both E. coli and S. aureus. This study also showed that a Gram-negative bacterium (E. coli) were more readily disinfected by the photocatalysts than a Gram-positive bacterium (S. aureus).

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

    SciTech Connect

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

    2009-11-02

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed

    Yao, Yunxi; Goodman, D Wayne

    2014-02-28

    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

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

    NASA Astrophysics Data System (ADS)

    Piyawit, Waraporn

    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.

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

    SciTech Connect

    Palmero, E. M. Bran, C.; Real, R. P. del; Vzquez, M.; Magn, C.

    2014-07-21

    Arrays of Ni{sub 100?x}Cu{sub x} nanowires ranging in composition 0???x???75, diameter from 35 to 80?nm, and length from 150?nm to 28??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.

  6. Preparation and dispersion of NiCu composite nanoparticles Yu-Guo Guo,y Li-Jun Wan,* Jian-Ru Gong and Chun-Li Bai*

    E-print Network

    Gong, Jian Ru

    to produce highly crystalline sand- wich CuNiCu composite nanoparticles. 2. Experimental Fabrication of the sandwich cylinder-shaped CuNiCu nano- particles was carried out by using the process shown schemati L1 CuCl2 mixed solution. Then, the barrier layer was dissolved in 5% H3PO4 . Finally, a silver film

  7. Interphase boundary precipitation in liquid phase sintered W-Ni-Fe and W-Ni-Cu alloys

    NASA Astrophysics Data System (ADS)

    Muddle, B. C.

    1984-06-01

    The microstructure of liquid-phase sintered, tungsten-based heavy alloys comprises a continuous network of spheroidal tungsten single crystals embedded in a ductile, fcc matrix phase, and the integrity of the tungsten-matrix interphase boundaries established during processing is of major importance in determining the resultant mechanical properties. A serious potential source of embrittlement in these systems involves the precipitation of a brittle third phase along these boundaries. In the present work the techniques of selected area and convergent beam electron diffraction, energy dispersive X-ray microanalysis, and scanning Auger electron spectroscopy have been used to identify the embrittling interphase boundary precipitate formed in a commercial W-4.5 wt pct Ni-4.5 wt pct Fe alloy. The interphase boundary precipitation of an intermetallic phase in a W-7.2 wt pct Ni-2.4 wt pct Cu alloy under controlled conditions of heat treatment has also been confirmed. The precipitate phase observed in the W-Ni-Fe alloy in the as-sintered furnace-cooled condition has been found to be an eta carbide with a diamond cubic crystal structure (space group Fd3m, a 0 = 1.092 0.005 nm) and a tentative composition of the form (Ni,Fe)6W6C, where the Ni:Fe atom ratio is approximately 2:3. Neither the carbide nor any evidence of an intermetallic phase was observed in the as-sintered, furnace-cooled W-Ni-Cu alloy, but a continuous interphase boundary film of intermetallic precipitate could be induced in specimens solution treated at 1350C, water quenched, and aged isothermally in the temperature range 600 to 900C. Selected area electron diffraction indicated that the phase was isomorphous with the intermetallic Ni4W of the binary Ni-W system.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Alumina ceramic (?-Al2O3) was brazed to stainless steel (SUS304) using an Ag-Cu-Ti + W composite filler and a traditional active brazing filler alloy (CuSil-ABA). Then, the effects of the presence of W particles and of the brazing parameters on the microstructures and mechanical properties of the brazed joints were investigated. The maximum tensile strength of the joints obtained using Ag-Cu-Ti + W composite filler was 13.2 MPa, which is similar to that obtained using CuSil-ABA filler (13.5 MPa). When the joint was brazed at 930 C for 30 min, the tensile strengths decreased for both kinds of fillers, although the strength was slightly higher for the Ag-Cu-Ti + W composite filler than for the Ag-Cu-Ti filler. The interfacial microstructure results show that the Ti reacts with W to form a Ti-W-O compound in the brazing alloy. When there are more W particles in the brazing alloy, the thickness of the Ti X O Y reaction layer near the alumina ceramic decreases. Moreover, W particles added to the brazing alloy can reduce the coefficient of thermal expansion of the brazing alloy, which results in lower residual stress between the Al2O3 and SUS304 in the brazing joints and thus yields higher tensile strengths as compared to those obtained using the CuSil-ABA brazing alloy.

  9. Topographic Characterization of Cu-Ni NPs @ a-C:H Films by AFM and Multifractal Analysis.

    PubMed

    ??lu, ?tefan; Stach, Sebastian; Ghodselahi, Tayebeh; Ghaderi, Atefeh; Solaymani, Shahram; Boochani, Arash; Garczyk, ?aneta

    2015-04-30

    In the present work three-dimensional (3-D) surface topography of Cu-Ni nanoparticles in hydrogenated amorphous carbon (Cu-Ni NPs @ a-C:H) with constant thickness of Cu and three thicknesses of Ni prepared by RF-Plasma Enhanced Chemical Vapor Deposition (RF-PECVD) system were investigated. The thin films of Cu-Ni NPs @ a-C:H with constant thickness of Cu and three thicknesses of Ni deposited by radio frequency (RF)-sputtering and RF-PECVD systems, were characterized. To determine the mass thickness and atomic structure of the films, the Rutherford backscattering spectroscopy (RBS) spectra was applied. The absorption spectra were applied to study localized surface plasmon resonance (LSPR) peaks of Cu-Ni NPs (observed around 608 nm in visible spectra), which is widened and shifted to lower wavelengths as the thickness of Ni over layer increases, and their changes are also evaluated by the 3-D surface topography. These nanostructures were investigated over square areas of 1 ?m 1 ?m using atomic force microscopy (AFM) and multifractal analysis. Topographic characterization of surface samples (in amplitude, spatial distribution, and pattern of surface characteristics) highlighted 3-D surfaces with multifractal features which can be quantitatively estimated by the multifractal measures. The 3-D surface topography Cu-Ni NPs @ a-C:H with constant thickness of Cu and three thicknesses of Ni prepared by RF-PECVD system can be characterized using the multifractal geometry in correlation with the surface statistical parameters. PMID:25839675

  10. Competitive removal of Cu-EDTA and Ni-EDTA via microwave-enhanced Fenton oxidation with hydroxide precipitation.

    PubMed

    Lin, Qintie; Pan, Hanping; Yao, Kun; Pan, Yonggang; Long, Wei

    2015-01-01

    Ethylenediaminetetraacetic acid (EDTA) can form very stable complexes with heavy metal ions, greatly inhibiting conventional metal-removal technologies used in water treatment. Both the oxidation of EDTA and the reduction of metal ions in metal-EDTA systems via the microwave-enhanced Fenton reaction followed by hydroxide precipitation were investigated. The Cu(II)-Ni(II)-EDTA, Cu(II)-EDTA and Ni(II)-EDTA exhibited widely different decomplexation efficiencies under equivalent conditions. When the reaction reached equilibrium, the chemical oxygen demand was reduced by a microwave-enhanced Fenton reaction in different systems and the reduction order from high to low was Cu(II)-Ni(II)-EDTA ? Cu(II)-EDTA > Ni(II)-EDTA. The removal efficiencies of both Cu(2+) and Ni(2+) in Cu-Ni-EDTA wastewaters were much higher than those in a single heavy metal system. The degradation efficiency of EDTA in Cu-Ni-EDTA was lower than that in a single metal system. In the Cu-Ni-EDTA system, the microwave thermal degradation and the Fenton-like reaction created by Cu catalyzed H2O2 altered the EDTA degradation pathway and increased the pH of the wastewater system, conversely inhibiting residual EDTA degradation. PMID:26398034

  11. First principles determination of magnetic anisotropy for Ni/Cu(001).

    NASA Astrophysics Data System (ADS)

    Wu, Ruqian; Chen, Lujun; Freeman, A. J.

    1997-03-01

    The magnetostriction and its inverse effect, namely the strain induced uniaxial magneto-crystalline anisotropy (MCA) in magnetic transition metals, has been a major challenge for modern first principles theory. We calculated the MCA energy of Ni films grown on the Cu(001) substrate using the full potential linearized augmented plane wave (FLAPW) method with the state tracking and torque approaches for the determination of the MCA energy [1]. For the fct bulk Ni, the MCA energy is a linear function of the length of the c axis. In the geometry corresponding to the experiment, the calculated MCA energy is 65x10-6 eV/atom, which is very close to the experimental value 70x10-6 eV/atom [2]. For the Ni/Cu(001) thin films, the MCA energies are negative for systems with one and four Ni monolayers whereas they are positive for those with two and three Ni monolayers. The strain-induced magnetic anisotropy in the fct bulk Ni and the oscillatory behavior of the MCA energy in the Ni/Cu(001) thin films are explained from fundamental electronic properties. [1] D.S. Wang, R.Q. Wu and A.J. Freeman, Phys. Rev. Lett. 70, 869 (1993); X.D. Wang, R.Q. Wu, D.S. Wang and A.J. Freeman, Phys. Rev. B 54, 61 (1996). [2] K. Baberschke, Appl. Phys. A, 399 (1996).

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

    SciTech Connect

    Liu, Y.; Blandin, J.J.; Suery, M.; Kapelski, G.

    2012-08-15

    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.

  13. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

    2015-04-01

    We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 C, 700 C, and 800 C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 ?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.

  14. Pressure-Free Bonding of Metallic Plates with Ni Affinity Layers Using Cu Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ishizaki, Toshitaka; Akedo, Kunio; Satoh, Toshikazu; Watanabe, Ryota

    2014-01-01

    This study investigated the pressure-free bonding of metallic plates using Cu nanoparticles capped by fatty acid and amine as the bonding material. The application of Ni layers to Cu plates prior to bonding significantly improved their adhesion to sintered Cu nanoparticles, resulting in higher strengths even without pressure compared to samples bonded using an ordinary Pb-rich solder at a similar temperature. The shear strength could be enhanced if the thickness of Ni layers was larger than 1 nm. The same effect was also observed when Al plates with Ni layers were bonded by Cu nanoparticles. In contrast, Ti, Mn, and Cr layers were found to be ineffective with regard to improving bond strength. Cu plates bonded by Cu nanoparticles capped by fatty acid and amine with different alkyl chain lengths from 6 to 18 showed an optimal strength with a length of 10, where the Cu particles were small enough to sinter effectively but not so small as to oxidize.

  15. Molecular self-assembly at nanometer scale modulated surfaces: trimesic acid on Ag(111), Cu(111) and Ag/Cu(111).

    PubMed

    Baviloliaei, Mahdi Sadeghzadeh; Diekhner, Lars

    2014-06-21

    The balance between molecule-molecule and molecule-surface interactions is a determining factor in the creation of well-ordered organic networks formed by self-assembly on crystalline metal surfaces. We have used a scanning tunneling microscope under ultrahigh vacuum conditions to study the molecular self-assembly of trimesic acid on a surface that is modulated on a comparable nanometer scale as the size of the molecules. This is made of one layer of silver grown on a Cu(111) surface where it forms a periodic reconstruction. It is shown that the self-assembly of trimesic acid at room temperature, where intermolecular interactions are taking place via hydrogen bonds, is strongly disturbed due to the modulated substrate and the spatially varying potential imposed on the molecules. Annealing to 350 K partly deprotonates the molecules and changes the intermolecular interactions to stronger ionic hydrogen bonds. This reduces the influence of the modulated substrate and allows the molecules to self-assemble into long-range ordered networks on the surface. Comparisons are made to self-assembly on the flat surfaces of Ag(111) and Cu(111), where we always find well-ordered molecular networks. PMID:24776919

  16. Relationship between morphologies and orientations of Cu{sub 6}Sn{sub 5} grains in Sn3.0Ag0.5Cu solder joints on different Cu pads

    SciTech Connect

    Tian, Yanhong Zhang, Rui; Hang, Chunjin; Niu, Lina; Wang, Chunqing

    2014-02-15

    The morphologies and orientations of Cu{sub 6}Sn{sub 5} intermetallic compounds in the Sn3.0Ag0.5Cu solder joints both on polycrystalline and single crystal Cu pads under different peak reflow temperatures and times above liquids were investigated. The relationship between Cu{sub 6}Sn{sub 5} grain orientations and morphologies was clarified. At the interface of Sn3.0Ag0.5Cu/polycrystalline Cu pad, scalloped Cu{sub 6}Sn{sub 5} intermetallic compounds formed at 250 C and roof shape Cu{sub 6}Sn{sub 5} formed at 300 C. Both scalloped Cu{sub 6}Sn{sub 5} and roof shape Cu{sub 6}Sn{sub 5} had a preferred orientation of (0001) plane being parallel to polycrystalline Cu pad surface. Besides, the percentage of large angle grain boundaries increased as the peak reflow temperature rose. At the interface of Sn3.0Ag0.5Cu/(111) single crystal Cu pad, the Cu{sub 6}Sn{sub 5} intermetallic compounds were mainly scallop-type at 250 C and were prism type at 300 C. The prismatic Cu{sub 6}Sn{sub 5} grains grew along the three preferred directions with the inter-angles of 60 on (111) single crystal Cu pad while along two perpendicular directions on (100) single crystal Cu pad. The orientation relationship between Cu{sub 6}Sn{sub 5} grains and the single crystal Cu pads was investigated by electron backscatter diffraction technology. In addition, two types of hollowed Cu{sub 6}Sn{sub 5} intermetallic compounds were found inside the joints of polycrystalline Cu pads. The long hexagonal Cu{sub 6}Sn{sub 5} strips were observed in the joints reflowing at 250 C while the hollowed Cu{sub 6}Sn{sub 5} strips with the ? shape cross-sections appeared at 300 C, which was attributed to the different grain growth rates of different Cu{sub 6}Sn{sub 5} crystal faces. - Highlights: The orientation of interfacial Cu{sub 6}Sn{sub 5} grains was obtained by EBSD technology. Two types of hollowed Cu{sub 6}Sn{sub 5} strips were found at different temperatures. The formation mechanism of hollowed Cu{sub 6}Sn{sub 5} was elaborated based on Bravais law. The relationship between Cu{sub 6}Sn{sub 5} grain orientations and morphologies was clarified.

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

    PubMed

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

    2014-12-21

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

  18. The As-Cu-Ni System: A Chemical Thermodynamic Model for Ancient Recycling

    NASA Astrophysics Data System (ADS)

    Sabatini, Benjamin J.

    2015-08-01

    This article is the first thermodynamically reasoned ancient metal system assessment intended for use by archaeologists and archaeometallurgists to aid in the interpretation of remelted/recycled copper alloys composed of arsenic and copper, and arsenic, copper, and nickel. These models are meant to fulfill two main purposes: first, to be applied toward the identification of progressive and regressive temporal changes in artifact chemistry that would have occurred due to recycling, and second, to provide thermodynamic insight into why such metal combinations existed in antiquity. Built on well-established thermodynamics, these models were created using a combination of custom-written software and published binary thermodynamic systems data adjusted to within the boundary conditions of 1200C and 1 atm. Using these parameters, the behavior of each element and their likelihood of loss in the binaries As-Cu, As-Ni, Cu-Ni, and ternary As-Cu-Ni, systems, under assumed ancient furnace conditions, was determined.

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

    SciTech Connect

    Boyle, J. H.; Shafarman, W. N.; Birkmire, R. W.; McCandless, B. E.

    2014-06-14

    The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin films were characterized over the entire compositional range at a fixed (Cu?+?Ag)/(In?+?Ga) ratio. Films deposited at 550?C on bare and molybdenum coated soda-lime glass by elemental co-evaporation in a single-stage process with constant incident fluxes exhibit single phase chalcopyrite structure, corresponding to 122 spacegroup (I-42d) over the entire compositional space. Unit cell refinement of the diffraction patterns show that increasing Ag substitution for Cu, the refined a{sub o} lattice constant, (Ag,Cu)-Se bond length, and anion displacement increase in accordance with the theoretical model proposed by Jaffe, Wei, and Zunger. However, the refined c{sub o} lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.

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

    NASA Astrophysics Data System (ADS)

    Guisbiers, Grgory; Khanal, Subarna; Ruiz-Zepeda, Francisco; Roque de La Puente, Jorge; Jos-Yacaman, Miguel

    2014-11-01

    Bimetallic nanoparticles like Cu-Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core-shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu-Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu-Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists.Bimetallic nanoparticles like Cu-Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core-shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu-Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu-Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05739b

  1. Black Pad Susceptibility of the Electroless Ni Films on the Cu UBM

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Yu, Jin

    2014-11-01

    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.

  2. Dirac and Weyl Semimetal in XYBi (X?=?Ba, Eu; Y?=?Cu, Ag and Au)

    PubMed Central

    Du, Yongping; Wan, Bo; Wang, Di; Sheng, Li; Duan, Chun-Gang; Wan, Xiangang

    2015-01-01

    Weyl and Dirac semimetals recently stimulate intense research activities due to their novel properties. Combining first-principles calculations and effective model analysis, we predict that nonmagnetic compounds BaYBi (Y?=?Au, Ag and Cu) are Dirac semimetals. As for the magnetic compound EuYBi, although the time reversal symmetry is broken, their long-range magnetic ordering cannot split the Dirac point into pairs of Weyl points. However, we propose that partially substitute Eu ions by Ba ions will realize the Weyl semimetal. PMID:26399742

  3. Dirac and Weyl Semimetal in XYBi (X?=?Ba, Eu; Y?=?Cu, Ag and Au)

    NASA Astrophysics Data System (ADS)

    Du, Yongping; Wan, Bo; Wang, Di; Sheng, Li; Duan, Chun-Gang; Wan, Xiangang

    2015-09-01

    Weyl and Dirac semimetals recently stimulate intense research activities due to their novel properties. Combining first-principles calculations and effective model analysis, we predict that nonmagnetic compounds BaYBi (Y?=?Au, Ag and Cu) are Dirac semimetals. As for the magnetic compound EuYBi, although the time reversal symmetry is broken, their long-range magnetic ordering cannot split the Dirac point into pairs of Weyl points. However, we propose that partially substitute Eu ions by Ba ions will realize the Weyl semimetal.

  4. Ag and Cu doped colloidal CdSe nanocrystals: partial cation exchange and luminescence

    NASA Astrophysics Data System (ADS)

    Bala Gopal, M.

    2015-08-01

    Partial cation exchange was employed to dope pre-formed colloidal CdSe nanocrystals with Ag+ and Cu2+ ions. Unusual photoluminescence (PL) properties were observed after these partial cation exchange reactions. Intensity of excitonic PL increases by ?4 times at low level of doping (1.3 dopant per nanocrystal). However, systematic study shows that the dopant ions do not enhance the excitonic emission. Instead, better surface passivation by trioctylphosphine used during the cation exchange is responsible for enhancement of excitonic PL. As doping concentration increases, intensity of excitonic PL decreases, and a new dopant-related emission emerges.

  5. Solid-state growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface

    SciTech Connect

    Alam, M.O.; Chan, Y.C.

    2005-12-15

    Systematic experimental work was carried out to understand the growth kinetics of Ni{sub 3}Sn{sub 4} at the Sn-3.5Ag solder/Ni interface. Sn-3.5%Ag solder was reflowed over Ni metallization at 240 deg. C for 0.5 min and solid-state aging was carried out at 150-200 deg. C, for different times ranging from 0 to 400 h. Cross-sectional studies of interfaces have been conducted by scanning electron microscopy and energy dispersive x ray. The growth exponent n for Ni{sub 3}Sn{sub 4} was found to be about 0.5, which indicates that it grows by a diffusion-controlled process even at a very high temperature near to the melting point of the SnAg solder. The activation energy for the growth of Ni{sub 3}Sn{sub 4} was determined to be 16 kJ/mol.

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

    SciTech Connect

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

    2014-04-28

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

  7. Fracture behavior and structural transition of Ni46Mn33Ga17Cu4xZrx alloys

    E-print Network

    Zheng, Yufeng

    Fracture behavior and structural transition of Ni46Mn33Ga17Cu4xZrx alloys Bing Tian a,n , Feng 5 April 2014 Keywords: NiMnGa alloys Intermetallics Mechanical properties Microstructure Phase33Ga17Cu4xZrx (x0, 2, 4) alloys after undergoing quasi-static compression and ball milling

  8. Equation of State of an AlCoCrCuFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Li, Gong; Xiao, Daihong; Yu, Pengfei; Zhang, Lijun; Liaw, Peter K.; Li, Yanchun; Liu, Riping

    2015-08-01

    The pressure-volume (P-V) relationship of the AlCoCrCuFeNi high-entropy alloy (HEA) at room temperature has been studied using in situ high-pressure energy-dispersive x-ray diffraction with synchrotron radiation at high pressures. The equation of state of the AlCoCrCuFeNi HEA is determined by the calculation of the radial distribution function. The experimental results indicate that the HEA keeps a stable face-centered-cubic + body-centered-cubic structure in the experimental pressure range from 0 GPa to 24 GPa.

  9. Theoretical study of carbon dioxide activation by metals (Co, Cu, Ni) supported on activated carbon.

    PubMed

    Ha, Nguyen Ngoc; Ha, Nguyen Thi Thu; Van Khu, Le; Cam, Le Minh

    2015-12-01

    The activation of carbon dioxide (CO2) by catalytic systems comprising a transition metal (Co, Cu,Ni) on an activated carbon (AC) support was investigated using a combination of different theoretical calculation methods: Monte Carlo simulation, DFT and DFT-D, molecular dynamics (MD), and a climbing image nudged elastic band (CI-NEB) method. The results obtained indicate that CO2 is easily adsorbed by AC or MAC (M: Cu, Co, Ni). The results also showed that the process of adsorbing CO2 does not involve a transition state, and that NiAC and CoAC are the most effective of the MAC catalysts at adsorbing CO2. Adsorption on NiAC led to the strongest activation of the C-O bond, while adsorption on CuAC led to the weakest activation. Graphical Abstract Models of CO2 activation on: a)- activated carbon; b)- metal supported activated carbon (M-AC), where M: Co, Cu, Ni. PMID:26637187

  10. A series of M(II)Cu(II)3 stars (M = Mn, Ni, Cu, Zn) exhibiting unusual magnetic properties.

    PubMed

    Mondal, Suraj; Mandal, Shuvankar; Carrella, Luca; Jana, Arpita; Fleck, Michel; Khn, Andreas; Rentschler, Eva; Mohanta, Sasankasekhar

    2015-01-01

    The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two ?2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. The title compounds are rare or sole examples of stars having these metal-ion combinations. In the cases of 1, 3, and 4, the four metal ions form a centered isosceles triangle, while the four metal ions in 2 form a centered equilateral triangle. Both the variable-temperature magnetic susceptibility and variable-field magnetization (at 2-10 K) of 1-3 have been measured and simulated contemporaneously. While the Mn(II)Cu(II)3 compound 1 exhibits ferromagnetic interaction with J = 1.02 cm(-1), the Ni(II)Cu(II)3 compound 2 and Cu(II)Cu(II)3 compound 3 exhibit antiferromagnetic interaction with J = -3.53 and -35.5 cm(-1), respectively. Variable-temperature magnetic susceptibility data of the Zn(II)Cu(II)3 compound 4 indicate very weak antiferromagnetic interaction of -1.4 cm(-1), as expected. On the basis of known correlations, the magnetic properties of 1-3 are unusual; it seems that ferromagnetic interaction in 1 and weak/moderate antiferromagnetic interaction in 2 and 3 are possibly related to the distorted coordination environment of the peripheral copper(II) centers (intermediate between square-planar and tetrahedral). DFT calculations have been done to elucidate the magnetic properties. The DFT-computed J values are quantitatively (for 1) or qualitatively (for 2 and 3) matched well with the experimental values. Spin densities and magnetic orbitals (natural bond orbitals) correspond well with the trend of observed/computed magnetic exchange interactions. PMID:25496240

  11. Structures and Binding Enthalpies of M+(H20)(n) Clusters, M = Cu, Ag, Au.

    SciTech Connect

    Feller, David F.; Glendening, Eric D.; De Jong, Wibe A.

    1999-01-15

    Structures and incremental binding enthalpies were determined for the M+(H2O)n ionic clusters, M=Cu, Ag, Au; n=14 (5 for Cu) using correlated ab initio electronic structure methods. The effects of basis set expansion and high-level correlation recovery were found to be significant, in contrast to alkali and alkaline earth cation/water complexes, where correlation of the d electrons is unimportant. The use of a systematic sequence of one-particle basis sets permitted binding enthalpies in the complete basis set limit to be estimated. Overall, the best theoretical binding enthalpies compared favorably with the available experimental data for copper and silver. No experimental data is available for gold/water clusters.

  12. Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics

    PubMed Central

    Gravina, Marco Abdo; Canavarro, Cristiane; Elias, Carlos Nelson; Chaves, Maria das Graas Afonso Miranda; Brunharo, Ione Helena Vieira Portella; Quinto, Ctia Cardoso Abdo

    2014-01-01

    Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27C and 35C, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27C and 35C ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27C and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35C wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35C wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region. PMID:24713562

  13. Fabrication of PtCu and PtNiCu multi-nanorods with enhanced catalytic oxygen reduction activities

    NASA Astrophysics Data System (ADS)

    Liu, Licheng; Samjesk, Gabor; Takao, Shinobu; Nagasawa, Kensaku; Iwasawa, Yasuhiro

    2014-05-01

    1-D metallic nanomaterials have received much attention from the viewpoints of material functions of shape-controlled nanocrystals and applications to a variety of technologies. Metallic PtCu and PtNiCu multi-nanorods with diameter of about 5 nm and average length of around 10 nm were fabricated by polyol reduction method and characterized by TEM/EDS, XRD, XRF and electrochemical techniques. The multi-nanorods were successfully synthesized with CuCl2, Cu(CH3COO)2 and CuSO4 as Cu precursors but not with Cu(NO3)2, showing precursor dependency on the nanorod fabrication. The fcc alloy-crystal structures were observed with these multi-nanorods, which showed much more enhanced electrocatalytic activities with good stability for oxygen reduction reaction (ORR) than a conventional Pt/C catalyst. The results demonstrate that Pt-based multimetallic nanocrystals are promising candidates for cathode catalysts to develop next-generation polymer electrolyte fuel cells.

  14. Morphology and composition of chalcopyrite, chromite, Cu, Ni-Fe, pentlandite, and troilite in vugs of 76015 and 76215

    NASA Technical Reports Server (NTRS)

    Carter, J. L.; Clanton, U. S.; Laughon, R. B.; Mckay, D. S.; Usselman, T. M.; Fuhrman, R.

    1975-01-01

    Vugs from 76015 and 76215 are lined with euhedral crystals of plagioclase, pyroxene, ilmenite, Ni-Fe, and troilite. Smaller crystals of chromite, pentlandite, and chalcopyrite occur on the surface of the troilite in 76015. Wire Cu and dendritic-metallic Cu occurs with metallic Ni-Fe and troilite in some vugs of 76215. Troilite in both samples may have crystallized from an immiscible sulfide liquid. With falling temperature, chalcopyrite, and pentlandite may have exsolved from the troilite in 76015. By contrast, metallic Cu may have formed in 76215 by thermal breakdown of a bornite, troilite, and Ni-Fe assemblage which originally crystallized from a low-Ni immiscible sulfide liquid.

  15. Superconducting and ferromagnetic properties of NbN/NiCu and NbTiN/NiCu bilayer nanostructures for photon detection

    NASA Astrophysics Data System (ADS)

    Klimov, A.; Pu?niak, R.; Aichner, B.; Lang, W.; Joon, E.; Stern, R.; S?ysz, W.; Guziewicz, M.; Juchniewicz, M.; Borysiewicz, M. A.; Kruszka, R.; Wegrzecki, M.; ?aszcz, A.; Czerwinski, A.; Sobolewski, Roman

    2015-05-01

    Performance of superconducting single-photon detectors based on resistive hotspot formation in nanostripes upon optical photon absorption depends strongly on the critical current density JC of the fabricated nanostructure. Utilization of an ultrathin, weak-ferromagnet cap layer on the top of a superconducting film enhances of the structure's JC due to an extra flux pinning. We have fabricated a number of both NbN/NiCu and NbTiN/NiCu superconductor/ferromagnet (S/F) ultrathin bilayers and microbridges. NbN and NbTiN underlayers with thicknesses varying from 4 to 7 nm were grown using dc-magnetron sputtering on chemically cleaned sapphire single-crystal substrates. After rapid thermal annealing at high temperatures, the S films were coated with Ni0.54Cu0.46 overlayers with thicknesses of about 6 nm, using cosputtering. Compositions of the deposited films were confirmed by EDX spectroscopy analysis, while TEM studies demonstrated excellent epitaxial quality of our S layers with ~2-nm-thick F/S transition layer and atomically-sharp S/substrate interface. Magnetic properties of bilayers were studied using both the SQUID and Vibrating Sample Magnetometer techniques in low and high magnetic fields. Low-temperature tests confirmed that in all cases NiCu films were ferromagnetic with the Curie temperature of above 30 K. Below the bilayer critical temperature of approx. 12-13 K, the structures were fully proximitized with the strong superconducting signal. For superconducting transport properties characterization, we used bilayers patterned into 40-?m-long microbridges with the width varying from 0.4 ?m to 2 ?m. The same S/F nanostructures were also used to study their superconducting fluctuations. The temperature dependence of magnetoresistance demonstrated highly 2-dimensional character with an unusual negative region that extended almost to room temperature. In the S/F sample, the fluctuations were observed to be substantially below theoretical expectations.

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

    SciTech Connect

    Reda, M.R.; Al-Hajji, J.N. )

    1993-05-01

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

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

    SciTech Connect

    Xiang Jun; Shen Xiangqian; Song Fuzhan; Liu Mingquan

    2010-06-15

    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.

  18. Thermomechanical training and characterization of Ni-Ti-Hf and Ni-Ti-Hf-Cu high temperature shape memory alloys

    NASA Astrophysics Data System (ADS)

    Denowh, Chantz M.; Miller, David A.

    2012-06-01

    Nickel-titanium (NiTi) is the most commonly used shape memory alloy (SMA) for actuator applications, though its usefulness is limited to temperature ranges below 100?C. High temperature SMAs are formed by adding ternary elements to NiTi, but their usefulness as actuators is still in question. The purpose of this research was to characterize and train two high temperature SMAs, NiTi29.7Hf20 and NiCu5Ti29.7Hf20, to determine their effectiveness as linear actuators. Low temperature martensitic phase and high temperature austenitic phase stress-strain tests were performed to characterize the materials behavior followed by temperature cycling under constant stress. Temperature cycling under constant stress is known as thermomechanical training and resulted in small amounts of plastic strain growth and the development of two-way shape memory (TWSM). The results from these tests support the conclusion that hafnium distorts slip planes within the martensitic material phase, and that (Ti,Hf)2Ni and (Ti,Hf)3Ni4 particulates form during aging and annealing. The distorted slip planes cause slip and martensite reorientation to occur simultaneously, which develops a strong internal stress field during training within the first few cycles. The internal stress field develops TWSM, but limits further plastic growth. The particulate formation also embrittles the material. The transformation temperatures of both alloys were below creep and annealing temperatures making them ideally suited for high temperature actuators.

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

    SciTech Connect

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

    2013-10-21

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

  20. Effect of filler metal composition on the strength of yttria stabilized zirconia joints brazed with Pd-Ag-CuOx

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2008-09-08

    The Ag-CuOx system is of interest to be used to be used as an air braze filler metal for joining high temperature electrochemical devices. Previous work has shown that the melting temperatures can be increased by adding palladium to Ag-CuOx and it is expected that this may aid high temperature stability. This work compares the room temperature bend strength of joints made between yttria-stabilized zirconia (YSZ) air brazed using Ag-CuOx without palladium and with 5 and 15mol% palladium additions. It has been found that in general palladium decreases joint strength, especially in low copper oxide compositions filler metals. At high copper oxide contents, brittle fracture through both copper oxide rich phases and the YSZ limits joint strength.

  1. Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy

    SciTech Connect

    Asghar, Z.

    2014-02-15

    The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an ?-Al matrix. The strength at room temperature and at 300C is studied as a function of solution treatment time at 490C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300C. - Highlights: The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. An imaging analysis procedure to segment phases with similar contrasts is presented. 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.

  2. Mechanical Characterization of Lead-Free Sn-Ag-Cu Solder Joints by High-Temperature Nanoindentation

    NASA Astrophysics Data System (ADS)

    Lotfian, S.; Molina-Aldareguia, J. M.; Yazzie, K. E.; Llorca, J.; Chawla, N.

    2013-06-01

    The reliability of Pb-free solder joints is controlled by their microstructural constituents. Therefore, knowledge of the solder microconstituents' mechanical properties as a function of temperature is required. Sn-Ag-Cu lead-free solder alloy contains three phases: a Sn-rich phase, and the intermetallic compounds (IMCs) Cu6Sn5 and Ag3Sn. Typically, the Sn-rich phase is surrounded by a eutectic mixture of ?-Sn, Cu6Sn5, and Ag3Sn. In this paper, we report on the Young's modulus and hardness of the Cu6Sn5 and Cu3Sn IMCs, the ?-Sn phase, and the eutectic compound, as measured by nanoindentation at elevated temperatures. For both the ?-Sn phase and the eutectic compound, the hardness and Young's modulus exhibited strong temperature dependence. In the case of the intermetallics, this temperature dependence is observed for Cu6Sn5, but the mechanical properties of Cu3Sn are more stable up to 200C.

  3. Synthesis of NiCuZn-ferrite powders by means of mechanochemical treatment

    SciTech Connect

    Luo, Juhua

    2013-09-01

    Graphical abstract: The peak intensity for the product calcined at 500 C is relatively weak, but it gradually increases with increasing the temperature. This implies that the temperature up to 700 C leads to well crystallization of the spinel type of Ni{sub 0.45}Cu{sub 0.05}Zn{sub 0.5}Fe{sub 2}O{sub 4} phase. - Highlights: NiCuZn-ferrite powders were obtained at a low temperature by mechanochemical activation. The effects of the mechanical and thermal treatments on the mixtures were analyzed. The mechanochemical method benefited achieving the lower M{sub s} and ?{sub i}. - Abstract: NiCuZn-ferrite powders were synthesized by mechanochemical treatments using NiCO{sub 3}?2Ni(OH){sub 2}?4H{sub 2}O, CuO, ZnO and Fe{sub 2}O{sub 3} as raw materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM) were employed to evaluate the morphologies and structures of samples. The results indicated that the mechanochemical treatment produced several structural and chemical effects on reactants of the powder mixtures, and single phase Ni{sub 0.45}Cu{sub 0.05}Zn{sub 0.5}Fe{sub 2}O{sub 4} could be obtained after annealed at 700 C for 2 h. In comparison with the traditional firing method, the mechanochemical method benefited achieving the lower M{sub s} and ?{sub i}, which indicated that the sample had better magnetic properties.

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

    SciTech Connect

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

    2014-02-15

    Four new homochiral metalorganic frameworks (MOFs) based on S-malate anions and N-donor linkers of different length have been prepared under solvothermal conditions. [Cu(mal)(bpy)]H{sub 2}O (1), [Cu(mal)(bpe)]2H{sub 2}O (2), [Ni(mal)(bpy)]1.3CH{sub 3}OH (3) and [Ni(mal)(bpe)]4H{sub 2}O (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 13 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 %. - Graphical abstract: Four new homochiral metalorganic frameworks are built from Ni{sup 2+} or Cu{sup 2+} cations, S-malate anions and N-donor linkers of different length, which controls the size of pores and guest accessible volume of the homochiral structure. Display Omitted - Highlights: Four new homohiral metalorganic frameworks based on Ni{sup 2+} and Cu{sup 2+}. Cu(II)malate layers and Ni(II)malate chains are connected by N-donor linkers. N-donor linkers of different length control the size of pores.

  5. Microstructure and phase transformation of Ni46Mn33Ga17Cu4xZrx alloys

    E-print Network

    Zheng, Yufeng

    Microstructure and phase transformation of Ni46Mn33Ga17Cu4xZrx alloys B. Tian a , F. Chen a , Y October 2013 Accepted 12 November 2013 Available online 20 November 2013 Keywords: Metals and alloys transformation of Ni46Mn33Ga17Cu4xZrx (x0, 2, and 4) alloys. The substitution of Cu by Zr changed the alloy

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

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2006-08-01

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

  7. Electrochemical depositions of fluorohydroxyapatite doped by Cu2+, Zn2+, Ag+ on stainless steel substrates

    NASA Astrophysics Data System (ADS)

    Bir, F.; Khireddine, H.; Touati, A.; Sidane, D.; Yala, S.; Oudadesse, H.

    2012-07-01

    Fluoridated hydroxyapatite (FHA, Ca10(PO4)6(OH)2-xFx where 0 < x < 2 is the degree of fluoridation) and inorganic ions (Zn2+, Cu2+, Ag+) substituted fluoridated hydroxyapatite coatings (M-FHA) were deposited on the surface of medical grade 316L stainless steel samples by electrochemical deposition technique. The FHA coatings were co-substituted with antibacterial ions (Zn2+, Cu2+ or Ag+) by co-precipitation and ion-exchange methods. Characterization studies of coatings from X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) showed that the obtained layers are monophase crystals FHA and did not contain any discernible crystalline impurity. The particles of all samples are of nano size that gives thin layers. The surface morphology, microstructure and Ca/P atomic ratio of the FHA coatings can be regulated by varying electrolyte temperature. This later affects the porosity of the coating surface and the chemical compositions of the deposits. Quantitative elemental analysis indicates that the copper, zinc and silver ions are incorporated into the Fluorohydroxyapatite. The antimicrobial effects of doped fluorohydroxyapatite coatings against pathogen bacterial strains Staphylococcus aureus were tested in liquid media. The results are promising and demonstrated that all doped FHA samples exhibit excellent antimicrobial activity "in vitro" against the microorganism, so the antimicrobial properties of the coatings developed are improved.

  8. Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Shan; Cao, Fahe; Chang, Linrong; Zheng, JunJun; Zhang, Zhao; Zhang, Jianqing; Cao, Chunan

    2011-08-01

    High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density ( Icorr) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated.

  9. ac susceptibility of thermally annealed and neutron irradiated Cu-Ni alloys

    NASA Technical Reports Server (NTRS)

    Catchings, R. M., III; Borg, R. J.; Violet, C. E.

    1985-01-01

    Thermal annealing and high-flux neutron irradiation are used to vary the degree of short-range atomic order in Cu-Ni alloys of composition 40, 50, and 60 at. pct Ni. The magnetic state is measured by ac magnetic susceptibility measurements. It is shown that annealing at 350 C causes significant changes in the susceptibility of all the samples. In the 50 and 60 at. pct Ni samples, the transition is broadened and extended to higher temperatures, while the 40 at. pct Ni sample changes from a paramagnetic system to a weakly ferromagnetic system. The neutron irradiation, in contrast to the thermal treatment, causes the development of smaller size cluster formations. The irradiated 60 at. pct Ni sample exhibits no change in the shape of its susceptibility curve from that of the quenched sample, whereas, the 40 pct alloy is changed, by irradiation, from a paramagnetic system to a spin-glass system.

  10. Synthesis, Grain Growth, Cu-DOPING, and Magnetic Properties of Nanocrystalline Ni-Zn Ferrite

    NASA Astrophysics Data System (ADS)

    Jalaly, Maisam; Enayati, Mohammad-Hosein; Kameli, Parviz; Karimzadeh, Fathollah

    Nanostructured powder of Ni-Zn ferrite was directly produced by high-energy ball milling of stoichiometric mixture of ZnO, NiO, and Fe2O3 powders. X-ray powder diffractometry, scanning electron microscopy, annealing, treatment, and vibrating sample magnetometer were used to investigate the structural, chemical, and magnetic aspects of Ni0.5Zn0.5Fe2O4 compound. The crystallite size of final product after 60 h of ball milling time was estimated to be 17 nm. Heat treatment of ball-milled Ni-Zn ferrite was performed to study the thermal behavior of ferrite. The effect of copper doping on structure and magnetic properties of Ni-Zn ferrite was also studied. The results showed that the Zn replacement with Cu led to a decrease of magnetization.

  11. Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

    2015-02-01

    Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

  12. Tuning of Ag doped core-shell ZnO NWs/Cu2O grown by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Makhlouf, Houssin; Messaoudi, Olfa; Souissi, Ahmed; Ben Assaker, Ibtissem; Oueslati, Mihrez; Bechelany, Mikhael; Chtourou, Radhouane

    2015-09-01

    ZnO nanowires (NWs)/Cu2O-Ag core-shell nanostructures (NSs) have been synthesized by electrochemical deposition method on ITO-coated glass substrates in order to improve the efficiency of the type-II transition of core-shell ZnO NWs/Cu2O-Ag NSs. The morphologies of the obtained NSs were studied by scanning electron microscopy confirming the presence of core-shell NSs. The crystalline proprieties were analyzed by x-ray diffraction and micro-Raman measurement: wurtzite ZnO and cuprit Cu2O phase were founded. The presence of Ag content in core-shell NS was detected by EDX. Optical measurement reveals an additional contribution ?E at about 1.72 eV attributed to the type-II interfacial transition between the valance band of cuprit-Cu2O and the conduction band of W-ZnO. The effect of the Ag doping into the type-II transition was investigated. A red shift of the type-II transition was detected according to the Ag concentration. These materials could have potential applications in photocatalytic and photovoltaic fields.

  13. Novel PdAgCu ternary alloy as promising materials for hydrogen separation membranes: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Tarditi, Ana M.; Cornaglia, Laura M.

    2011-01-01

    The use of the sequential electroless plating method allowed us to obtain the PdAgCu ternary alloy on top of dense stainless steel (SS) 316 L disks. The XRD analysis indicated that initially the nucleation of the two phases of the alloy (FCC and BCC) takes place, but the FCC/BCC ratio increases with the annealing time at 500 C in H 2 stream. After 162 h, the film contained only the FCC phase, which presents promising properties to be applied in the synthesis of hydrogen selective membranes. SEM cross-section results showed that a dense, continuous, defect-free film was deposited on top of the SS support, and the EDS data indicated that no significant gradient was present on the thickness of the film. XPS and LEIS allowed us to determine that Cu and Ag surface segregation takes place after annealing up to 500 C/5 days. In the top-most surface layer, Ag enrichment takes place as determined by ARXPS experiments which can be the result of the lower surface tension of Ag compared to that of Cu and Pd. Increasing the annealing temperature results in an increase of the Ag surface segregation while the Cu concentration in the top-most surface layer decreases.

  14. Spreading of Sn-Ag solders on FeNi alloys

    SciTech Connect

    Saiz, Eduardo; Hwang, C-W.; Suganuma, Katsuaki; Tomsia, Antoni P.

    2003-02-28

    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.

  15. A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar fiber

    NASA Astrophysics Data System (ADS)

    Pang, Hongwei; Bai, Ruicheng; Shao, Qinsi; Gao, Yufang; Li, Aijun; Tang, Zhiyong

    2015-12-01

    A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

  16. Coating geometry of Ag, Ti, Co, Ni, and Al nanoparticles on carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Barberio, M.; Stranges, F.; Xu, F.

    2015-04-01

    We present a morphology study on laser ablation produced metal nanoparticles (NPs) deposited on carbon nanotube (CNT) substrates. We analyzed the coating geometry and topography by processing AFM and SEM images. Our results show that Ag NPs aggregate together to form large agglomerates, that Ti NPs are well dispersed on the substrate surface forming a quasi-continuous layer, and that Co, Ni, and Al NPs coat quite uniformly CNTs and locally grow in a layer like fashion. We interpret the coating and clustering geometries in terms of cohesion, surface, and interfacial energies and diffusion barriers. Fractal analysis of composites morphology suggests the formation of structures with a smoother topography relative to pure carbon nanotubes for reactive metal nanoparticles.

  17. Processing and fabrication of YBa2Cu3O(x)/Ag composite wires and coils

    NASA Astrophysics Data System (ADS)

    Ferrando, W. A.; Divecha, A. P.; Mansour, A. N.; Karmarkar, S. D.; Balachandran, U.; Dorris, S. E.; Dusek, J. T.; Picciolo, J. J.; Singh, J. P.; Poeppel, R. B.

    1990-11-01

    Silver was added to YBa2Cu3O(x) (123) powder by a melt technique using AgNO3 and heated to approx. 600 C to decompose the nitrate. This process yields 123 powder that is uniformly coated with Ag, as indicated by optical and scanning electron microscopy (SEM). The composite power is formed into rods (approx. 4 mm diameter) via drawing and swaging through conical converging dies. Wires of finer diameter (approx. 1 mm) and substantially greater linear uniformity were produced by slurry extrusion of the composite powder in a polymeric vehicle. Transport critical current density, J sub c, of these wires at present is about 750 A/sq cm. This value may be expected to rise due to further reduction of second phase impurities localized at grain boundaries and better understanding of the Ag/superconductor interface. The wire fabrication is described in some detail and discusses the results of microscopic analyses by scanning electron microscopy (SEM), x ray photoemission spectroscopy (XPS), and x ray diffraction (XRD).

  18. Low-temperature creep of SnPb and SnAgCu solder alloys and reliability prediction in electronic packaging modules

    E-print Network

    Dao, Ming

    Low-temperature creep of SnPb and SnAgCu solder alloys and reliability prediction in electronic solder alloys. Experimental results showed that both solder alloys creep significantly within for the lead-free solder alloy Sn3Ag0.5Cu. 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights

  19. Comparison of Extensive Thermal Cycling Effects on Microstructure Development in Micro-alloyed Sn-Ag-Cu Solder Joints

    SciTech Connect

    Anderson, Iver E.; Boesenberg, Adam; Harringa, Joel; Riegner, David; Steinmetz, Andrew; Hillman, David

    2011-09-28

    Pb-free solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic have promise for widespread adoption across assembly conditions and operating environments, but enhanced microstructural control is needed. Micro-alloying with elements such as Zn was demonstrated for promoting a preferred solidification path and joint microstructure earlier in simple (Cu/Cu) solder joints studies for different cooling rates. This beneficial behavior now has been verified in reworked ball grid array (BGA) joints, using dissimilar SAC305 (Sn-3.0Ag-0.5Cu, wt.%) solder paste. After industrial assembly, BGA components joined with Sn-3.5Ag-0.74Cu-0.21Zn solder were tested in thermal cycling (-55 C/+125 C) along with baseline SAC305 BGA joints beyond 3000 cycles with continuous failure monitoring. Weibull analysis of the results demonstrated that BGA components joined with SAC + Zn/SAC305 have less joint integrity than SAC305 joints, but their lifetime is sufficient for severe applications in consumer, defense, and avionics electronic product field environments. Failure analysis of the BGA joints revealed that cracking did not deviate from the typical top area (BGA component side) of each joint, in spite of different Ag3Sn blade content. Thus, SAC + Zn solder has not shown any advantage over SAC305 solder in these thermal cycling trials, but other characteristics of SAC + Zn solder may make it more attractive for use across the full range of harsh conditions of avionics or defense applications.

  20. A TEM and STEM investigation of Cu-Ag nanomaterials synthesized by temperature controlled high-energy ball-milling

    NASA Astrophysics Data System (ADS)

    Zghal, Slim; Twesten, Ray; Wu, Fang; Bellon, Pascal

    2000-03-01

    It is well documented that low-temperature ball-milling can force immiscible elements, e.g., Cu and Ag, into solid solution. A slight increase of the milling temperature however results in a two- or even three-phase coexistence [1]. This coexistence is likely to take place at a nanometric scale since ball-milling results in the formation of grains with a size in the 10 nm range. This could open a new pathway for the synthesis of nanocomposites. The microstructure of Cu-Ag powder milled at temperature ranging from 80 to 504 K has been investigated by TEM and STEM, combining annular dark field technique (Z-contrast), EDS mapping and nanodiffraction. At the lower temperature the microstructure consists of a solid solution matrix with the nominal composition and a homogeneous distribution of Cu-rich precipitates of average size 6 nm. In the matrix a strong texture is frequently observed. An intragranular distorsion, 3 nm in size, is identified by nanodiffraction. At higher milling temperatures, Z-contrast image and nanoscale EDS prove that indeed phase separation takes place at a nanometric scale. The resulting distribution of Cu and Ag grains is however not random: Cu-rich precipitates are formed inside a percolated Ag-rich matrix, with wavy interfaces. These microstructures are contrasted with the ones obtained by purely thermal decomposition of a solid solution.

  1. Dendritic Ni(Cu)-polypyrrole hybrid films for a pseudo-capacitor.

    PubMed

    Choi, Bit Na; Chun, Woo Won; Qian, Aniu; Lee, So Jeong; Chung, Chan-Hwa

    2015-11-28

    Dendritic Ni(Cu)-polypyrrole hybrid films are fabricated for a pseudo-capacitor in a unique morphology using two simple methods: electro-deposition and electrochemical de-alloying. Three-dimensional structures of porous dendrites are prepared by electro-deposition within the hydrogen evolution reaction (HER) at a high cathodic potential; the high-surface-area structure provides sufficient redox reactions between the electrodes and the electrolyte. The dependence of the active-layer thickness on the super-capacitor performance is also investigated, and the 60 ?m-thick Ni(Cu)PPy hybrid electrode presents the highest performance of 659.52 F g(-1) at the scan rate of 5 mV s(-1). In the thicker layers, the specific capacitance became smaller due to the diffusion limitation of the ions in an electrolyte. The polypyrrole-hybridization on the porous dendritic Ni(Cu) electrode provides superior specific capacitance and excellent cycling stability due to the improvement in electric conductivity by the addition of conducting polypyrrole in the matrices of the dendritic nano-porous Ni(Cu) layer and the synergistic effect of composite materials. PMID:26509406

  2. Ratio-Controlled Synthesis of CuNi Octahedra and Nanocubes with Enhanced Catalytic Activity.

    PubMed

    Wang, Menglin; Wang, Liangbing; Li, Hongliang; Du, Wenpeng; Khan, Munir Ullah; Zhao, Songtao; Ma, Chao; Li, Zhenyu; Zeng, Jie

    2015-11-11

    Non-noble bimetallic nanocrystals (NCs) have been widely explored due to not only their low cost and abundant content in the Earth's crust but also their outstanding performance in catalytic reactions. However, controllable synthesis of non-noble alloys remains a significant challenge. Here we report a facile synthesis of CuNi octahedra and nanocubes with controllable shapes and tunable compositions. Its success relies on the use of borane morpholine as a reducing agent, which upon decomposition generates a burst of H2 molecules to induce rapid formation of the nuclei. Specifically, octahedra switched to nanocubes with an increased amount of borane morpholine. In addition, the ratio of CuNi NCs could be facilely tuned by changing the molar ratio of both precursors. The obtained CuNi NCs exhibited high activity in aldehyde-alkyne-amine coupling reactions, and their performance is strongly facet- and composition-dependent due to the competition of the surface energy (enhanced by increasing the percent of Ni) and active sites (derived from Cu atoms). PMID:26498199

  3. Magnetic properties of the Ni-Cu-Zn system doped with magnesium oxide

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    A series of ferrite samples, Ni0.1Cu0.2MgxZn0.7-x Fe2O4, (x=0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) has been prepared by the standard ceramic technique, sintered at 1200 C for 2 h, and their crystalline structures were investigated by using X-ray diffraction. The IR spectra and the ESR spectra analysis have been studied. DC electrical resistivity, thermoelectric power, charge carriers concentration and charge carrier mobility have been calculated at different temperatures. The value of dc electrical resistivity reach minimum at x=0.35 and above this value the electrical resistivity start to increase. It is noticed that thermoelectric power ? for the "Ni-Cu-Zn" system exhibits a positive sign indicating the majority carriers are holes without excluding the presence of electrons. Saturation magnetization Ms for the "Ni-Cu-Zn" system was calculated from M-H loop. It is noted that Ms decreases with Mg content up to x=0.55 and rapidly decrease above x>0.55 for the "Ni-Cu-Zn" system.

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

    SciTech Connect

    Goegebakan, Musa; Soguksu, Ali Kemal; Uzun, Orhan; Dogan, Ali

    2007-04-23

    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.

  5. Dendritic Ni(Cu)-polypyrrole hybrid films for a pseudo-capacitor

    NASA Astrophysics Data System (ADS)

    Choi, Bit Na; Chun, Woo Won; Qian, Aniu; Lee, So Jeong; Chung, Chan-Hwa

    2015-11-01

    Dendritic Ni(Cu)-polypyrrole hybrid films are fabricated for a pseudo-capacitor in a unique morphology using two simple methods: electro-deposition and electrochemical de-alloying. Three-dimensional structures of porous dendrites are prepared by electro-deposition within the hydrogen evolution reaction (HER) at a high cathodic potential; the high-surface-area structure provides sufficient redox reactions between the electrodes and the electrolyte. The dependence of the active-layer thickness on the super-capacitor performance is also investigated, and the 60 ?m-thick Ni(Cu)PPy hybrid electrode presents the highest performance of 659.52 F g-1 at the scan rate of 5 mV s-1. In the thicker layers, the specific capacitance became smaller due to the diffusion limitation of the ions in an electrolyte. The polypyrrole-hybridization on the porous dendritic Ni(Cu) electrode provides superior specific capacitance and excellent cycling stability due to the improvement in electric conductivity by the addition of conducting polypyrrole in the matrices of the dendritic nano-porous Ni(Cu) layer and the synergistic effect of composite materials.

  6. The Primary Magma of Jinchuan Cu-Ni (PGE) Sulfide Deposits

    NASA Astrophysics Data System (ADS)

    Su, S.; Lesher, M.

    2012-12-01

    Jinchuan mafic - ultramafic rocks host the third largest Cu-Ni sulfide deposits in the world. There are many new developments about the origin of Jinchuan Cu-Ni (PGE) deposit. But there are still debates about the primary magma of Jinchuan mafic-ultramafic rocks now. Li (2011) think high-magnesium basalt is the primary magma of Jinchuan mafic-ultramafic rocks. However, Lesher M (2012) think Ferro-picrite maybe the primary magma. We will discuss this scientific question through thestudy of dikes in Jinchuan Cu-Ni (PGE) deposit in this paper. The zircon SHRIMP U-Pb dating show that these dikes have the same ages with mafic-ultramafic rocks. The geochemisty of dikes' show that SiO2=43.58%-54.14%, MgO=12-14%, FeO=11-14%, It belongs to Ferro-picrite. the Rare Elements and PGE pattern of these dikes are the same with the pattern of Jinchuan mafic-ultramafic rocks. So we think that the primary magma of Jinchuan mafic-ultramafic rocks maybe the Ferro-picrites.; Fig.1 Geological map of Mining area No.1 and Mining area No.4 in Jinchuan Cu-Ni sulfide deposit 1.ferro-picrites, 2.peridotite, 3.schist, 4.migmatite, 5.marble, 6. lamprophyre, 7.pyroxenite, 8.granite , 9. gneiss, 10.fault

  7. Transition metal interaction and Ni-Fe-Cu-Si phases in silicon T. Buonassisi,b

    E-print Network

    Transition metal interaction and Ni-Fe-Cu-Si phases in silicon M. Heuer,a T. Buonassisi,b A. A into the observed phases. Our results indicate that chemical reactions between metals and silicon during precipitation may reduce the lattice mismatch compared to single-metal precipitates, rendering mixed-metal

  8. Elevated Temperature Creep Properties of Conventional 50Au-50Cu and 47Au 50Cu-3Ni Braze Alloys

    SciTech Connect

    STEPHENS JR.,JOHN J.; SCHMALE,DAVID T.

    2000-12-18

    The elevated temperature creep properties of the 50Au-50Cu wt% and 47Au-50Cu-3Ni braze alloys have been evaluated over the temperature range 250-850 C. At elevated temperatures, i.e., 450-850 C, both alloys were tested in the annealed condition (2 hrs. 750 C/water quenched). The minimum strain rate properties over this temperature range are well fit by the Garofalo sinh equation. At lower temperatures (250 and 350 C), power law equations were found to characterize the data for both alloys. For samples held long periods of time at 375 C (96 hrs.) and slowly cooled to room temperature, an ordering reaction was observed. For the case of the 50Au-50Cu braze alloy, the stress necessary to reach the same, strain rate increased by about 15% above the baseline data. The limited data for ordered 47Au-50Cu-3Ni alloy reflected a,smaller strength increase. However, the sluggishness of this ordering reaction in both alloys does not appear to pose a problem for braze joints cooled at reasonable rates following brazing.

  9. Bioaccessibility of As, Cd, Cu, Ni, Pb, and Sb in toys and low-cost jewelry.

    PubMed

    Guney, Mert; Zagury, Gerald J

    2014-01-21

    Children can be exposed to toxic elements in toys and jewelry following ingestion. As, Cd, Cu, Ni, Pb, and Sb bioavailability was assessed (n = 24) via the in vitro gastrointestinal protocol (IVG), the physiologically based extraction test (PBET), and the European Toy Safety Standard protocol (EN 71-3), and health risks were characterized. Cd, Cu, Ni, and Pb were mobilized from 19 metallic toys and jewelry (MJ) and one crayon set. Bioaccessible Cd, Ni, or Pb exceeded EU migratable concentration limits in four to six MJ, depending on the protocol. Using two-phase (gastric + intestinal) IVG or PBET might be preferable over EN 71-3 since they better represent gastrointestinal physiology. Bioaccessible and total metal concentrations were different and not always correlated, indicating that bioaccessibility measurement may provide more accurate risk characterization. More information on impacts of multiple factors affecting metals mobilization from toys and jewelry is needed before recommending specific tests. Hazard index (HI) for Cd, Ni, or Pb were >1 for all six MJ exceeding the EU limits. For infants (6-12 mo old), 10 MJ had HI > 1 for Cd, Cu, Ni, or Pb (up to 75 for Cd and 43 for Pb). Research on prolonged exposure to MJ and comprehensive risk characterization for toys and jewelry exposure is recommended. PMID:24345102

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

    SciTech Connect

    Zinkle, Steven J

    2014-06-01

    The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HPTM CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ~0.7 displacements per atom (dpa) at temperatures between 100 and 240 C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation increased with increasing irradiation temperature, with a uniform elongation of ~3.3% observed at 240 C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 C, and may be an attractive 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.

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

    NASA Astrophysics Data System (ADS)

    Zinkle, S. J.

    2014-06-01

    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.

  12. Ion irradiation induced nanocrystal formation in amorphous Zr 55Cu 30Al 10Ni 5 alloy

    NASA Astrophysics Data System (ADS)

    Carter, Jesse; Fu, E. G.; Martin, Michael; Xie, Guoqiang; Zhang, X.; Wang, Y. Q.; Wijesundera, D.; Wang, X. M.; Chu, Wei-Kan; McDeavitt, Sean M.; Shao, Lin

    2009-09-01

    Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr 55Cu 30Al 10Ni 5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 10 16 cm -2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5-10 nm and another with diameters of 50-100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings ( d-values) agree with the expectations for Cu 10Zr 7, NiZr 2 and CuZr 2 phases. We further discussed the possibility to form a substitutional intermetallic (Ni xCu 1-x)Zr 2 phase.

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

    SciTech Connect

    Ma Qiang; Zaera, Francisco

    2013-01-15

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

  14. Microstructural evolution during aging of an Al-Cu-Li-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Kumar, K. S.; Brown, S. A.; Pickens, Joseph R.

    1991-01-01

    Alloys in the Al-Cu-Li Ag-Mg subsystem were developed that exhibit desirable combinations of strength and ductility. These Weldalite (trademark) alloys, are unique for Al-Cu-Li alloys in that with or without a prior cold stretching operation, they obtain excellent strength-ductility combinations upon natural and artificial aging. This is significant because it enables complex, near-net shape products such as forgings and super plastically formed parts to be heat treated to ultra-high strengths. On the other hand, commercial extrusions, rolled plates and sheets of other Al-Cu-Li alloys are typically subjected to a cold stretching operation before artificial aging to the highest strength tempers to introduce dislocations that provide low-energy nucleation sites for strengthening precipitates such as the T(sub 1) phase. The variation in yield strength (YS) with Li content in the near-peak aged condition for these Weldalite (trademark) alloys and the associated microstructures were examined, and the results are discussed.

  15. Chemical Stability of (Ag,Cu)2Se: a Historical Overview

    NASA Astrophysics Data System (ADS)

    Brown, David R.; Day, Tristan; Caillat, Thierry; Snyder, G. JeffREY

    2013-07-01

    Recent work on Cu2- x Se has caused strong interest in this material due to its high reported peak zT (1.5) and the reduction of thermal conductivity through the mechanism of liquid-like suppression of heat capacity. In the 1960s, 3M patented Cu1.97Ag0.03Se as "TPM-217." Over the following decade it was tested and developed by the 3M Corporation, at the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory, Teledyne Energy Systems, and the General Atomics Corporation for use as a next-generation thermoelectric material. During these tests, extreme problems with material loss through Se vaporization and chemical reactions between the material and the device contacts were found. These problems were especially severe while operating under conditions of high iL/A. As a result, the material system was abandoned. The results of these reports are discussed. A simple test of degradation of Cu2Se under conditions of applied current and thermal gradient was performed and showed results compatible with the work done by General Atomics.

  16. Effects of pre-annealed ITO film on the electrical characteristics of high-reflectance Ni/Ag/Ni/Au contacts to p-type GaN

    NASA Astrophysics Data System (ADS)

    Hu, Xiao-Long; Liu, Li; Wang, Hong; Zhang, Xi-Chun

    2015-12-01

    In this study, a Ni/Ag/Ni/Au multilayer with first Ni layer of 0.5 nm was first optimized for high reflectivity (92.3%), low specific contact resistance (2.1 10-3 ? cm2) and good attachment strength to p-type GaN. To further decrease the contact resistance, the p-type GaN surface was previously treated with pre-annealed indium-tin-oxide (ITO) film before deposition of the Ni/Ag/Ni/Au multilayer, and resulted in a lower specific contact resistance of 1.9 10-4 ? cm2. The X-ray photoelectron spectroscopy results indicated that Ga 2p core level of the p-type GaN surface with the pre-annealed ITO film had a lower binding energy, leading to a reduction in the contact resistance. Furthermore, GaN-based flip-chip light-emitting diodes (LEDs) with and without the pre-annealed ITO film were fabricated. The average forward voltage of the flip-chip LEDs fabricated with the pre-annealed ITO film is 3.22 V at an injection current density of 35 A/cm2, which is much lower than that (3.49 V) of flip-chip LEDs without the pre-annealed ITO film. These results reveal that the proposed approach is effectively to fabricate high quality p-type contacts toward high power GaN-based LEDs.

  17. Performance of the nano-structured Cu-Ni (alloy) -CeO2 anode for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Minquan; Wang, Shaolan; Chen, Ting; Yuan, Chun; Zhou, Yucun; Wang, Shaorong; Huang, Jun

    2015-01-01

    In this work, copper and nickel oxides (CuO-NiO) powders with various mole ratios were synthesized by the glycine nitrate process (GNP) and the Cu-Ni alloy was obtained by reducing the CuO-NiO powders at 600 C for 0.75 h. Furthermore, Cu1-xNix (alloy) -CeO2 impregnated YSZ anodes were fabricated by the impregnation method and the optimized anode composition was evaluated. It was found that the optimized mole ratio of Cu:Ni was 5:5, while the weight ratio of Cu-Ni alloy to CeO2 was 3:1. Additionally, impregnated anode with 40 wt % loading of Cu0.5Ni0.5 (alloy)-CeO2 exhibited the best performance and the polarization resistance of such anode was only 0.097, 0.115, 0.145 and 0.212 ? cm2 at 750, 700, 650 and 600 C, respectively. Finally, the performance of the optimized anode in methane (CH4) was investigated and the carbon deposition is greatly suppressed compared to the Ni-based anode.

  18. Stability constants of Ni(II)- and Cu(II)-N-heterocycle complexes according to spectrophotometric data

    NASA Astrophysics Data System (ADS)

    Badhe, Samata; Tekade, Pradip; Bajaj, Sonal; Thakare, Shrikant

    2015-12-01

    The interaction of Ni(II) and Cu(II) with ethyl 4-(4-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine- 5-carboxylate [Ligand 1], 4-(1H-benzimidazol-2-yl)phenol [Ligand 2], and 2-(3-phenylamino- 4,5-dihydro-1,2-oxazol-5-yl)phenol [Ligand 3] have been studied by spectrophotometric technique at 0.01 M ionic strength and 28C in 70% dioxanewater mixture. The data obtained were used to estimate the stability constant of these ligands. Spectrophotometric investigation of Ni(II) and Cu(II) complexes with these ligands shows 1: 1 complex formation. The formation of complexes has been studied by Job's variation method. The values of conditional stability constants of Cu(II) complexes are greater than the corresponding Ni(II) complexes. The greater value of stability constant of Cu(II) complexes may be due to the fact of more stable nature of Cu(II). The value of stability constant of Cu(II)Ligand 2 complex is greater than that of Cu(II)-Ligand 1 and Cu(II)-Ligand 3. The same of Ni(II)-Ligand 3 complex is greater than that of Ni(II)-Ligand 1 and Ni(II)-Ligand 2.

  19. Sulfides from Martian and Lunar Basalts: Comparative Chemistry for Ni Co Cu and Se

    SciTech Connect

    J Papike; P Burger; C Shearer; S Sutton; M Newville; Y Choi; A Lanzirotti

    2011-12-31

    Here Mars and Moon are used as 'natural laboratories' with Moon displaying lower oxygen fugacities ({approx}IW-1) than Mars ({approx}IW to FMQ). Moon has lower concentrations of Ni and Co in basaltic melts than does Mars. The major sulfides are troilite (FeS) in lunar basalts and pyrrhotite (Fe{sub 1-x}S) in martian basalts. This study focuses on the concentrations of Ni, Co, Cu, and Se. We chose these elements because of their geochemical importance and the feasibility of analyzing them with a combination of synchrotron X-ray fluorescence (SXRF) and electron microprobe (EPMA) techniques. The selenium concentrations could only be analyzed, at high precision, with SXRF techniques as they are <150 ppm, similar to concentrations seen in carbonaceous chondrites and interplanetary dust particles (IDPs). Nickel and Co are in higher concentrations in martian sulfides than lunar and are higher in martian olivine-bearing lithologies than olivine-free varieties. The sulfides in individual samples show very large ranges in concentration (e.g., Ni ranges from 50 000 ppm to <5 ppm). These large ranges are mainly due to compositional heterogeneities within individual grains due to diffusion and phase separation. Electron microprobe wavelength-dispersive (WDS) mapping of Ni, Co, and Cu show the diffusion trajectories. Nickel and Co have almost identical diffusion trajectories leading to the likely nucleation of pentlandite (Ni,Co,Fe){sub 9}S{sub 8}, and copper diffuses along separate pathways likely toward chalcopyrite nucleation sites (CuFeS{sub 2}). The systematics of Ni and Co in lunar and martian sulfides clearly distinguish the two parent bodies, with martian sulfides displaced to higher Ni and Co values.

  20. Sn-Ag-Cu to Cu joint current aging test and evolution of resistance and microstructure

    NASA Astrophysics Data System (ADS)

    Xu, Di Erick; Chow, Jasper; Mayer, Michael; Jung, Jae Pil; Yoon, Jong Hyun

    2015-10-01

    SAC 305 solder bump with 800 ?m diameter were produced and soldered to a custom substrate with Cu lines as leads that allow for resistance measurement during current aging. The measured joint resistance values (leads plus solder bump) before aging are 7.7 1.8 m? and 11.8 2.8 m? at room temperature and 160C, respectively. In general, the resistance of the solder joint increases instantly by about 1 m?, when subjected to a 2.2 A aging current at 160C. The increase is gradual in the following hours of aging and more drastic as it approaches the final failure. Four stages are identified in the resistance signal curve and compared with observations from cross sections. The stages are IMC growth, crack formation and propagation, intermittent crack healing-forming, and final failure resulting in an open connection at the cathode. Recently a periodical drop and rise behavior was reported for the resistance signal. This behavior is reproduced and attributed to the intermittent crack healing-forming stage. The healing events observed are faster than the sampling time. Possibly, as current is concentrated when bypassing interfacial cracks, local melting occurs partially filling cracks before resolidifying.

  1. Geometrically unprecedented 3-, 5- and 7-membered Hg(II)-Cu(I) and Hg(II)-Ag(I) thiolate clusters: precursors to intermetallics.

    PubMed

    Gupta, Geetika; Chaturvedi, Jyotsna; Bhattacharya, Subrato

    2015-05-21

    The syntheses of three polynuclear heterobimetallic complexes through the use of a homoleptic mercuric thiolate anion as a template for the assembly of coinage metal are presented. The complexes, [(PPh3)3Ag3(?-SPh)7Hg2] (1), [Hg(?-SPh)4{Cu(PPh3)2}2] (2) and [(dppe)2Cu5(?-SPh)7Hg2(SPh)2] (3) were utilized as precursors for the fabrication of Hg-Ag and Hg-Cu intermetallics. PMID:25873179

  2. Elemental distribution, solute solubility and defect free volume in nanocrystalline restricted-equilibrium Cu-Ag alloys.

    PubMed

    Riedl, T; Kirchner, A; Eymann, K; Shariq, A; Schlesiger, R; Schmitz, G; Ruhnow, M; Kieback, B

    2013-03-20

    In this article we study the elemental distribution and solute solubility in nanocrystalline alloys of immiscible components near restricted equilibrium for the case of the binary Cu-Ag system. As predicted from thermodynamic considerations, a grain boundary segregated monophase alloy is observed in the annealed mechanically alloyed state for low Ag content by using atom probe tomography. From the detected Ag solute grain boundary enrichment the segregation free enthalpy is estimated to range between -25 and -49 kJ mol(-1) following the McLean equation, in agreement with values reported for coarse-grained Cu-Ag. The extension of the alloying range is described by a two-domain thermodynamic model that considers the excess free volume in the grain boundaries and the strain in the grain interior on the basis of the universal equation of state at negative pressure. To access the grain boundary volumetric strain experimentally, a method based on a combination of density measurements and microscopical quantification of closed pore areas is presented. Moreover, we apply x-ray diffraction line broadening analysis to determine the local strain amplitude, which yields a root-mean-square microstrain of ~0.3% for a grain size of ~30 nm. It is shown that the grain boundary free volume represents the major origin for the global solubility enhancement in nanocrystalline Cu-Ag at 503 K. PMID:23407023

  3. Localized surface plasmon behavior of Ag-Cu alloy nanoparticles stabilized by rice-starch and gelatin

    NASA Astrophysics Data System (ADS)

    Singh, Manish Kumar; Manda, Premkumar; Singh, A. K.; Mandal, R. K.

    2015-10-01

    The purpose of this communication was to understand localized surface plasmon behavior of a series of Ag-Cu alloy nanoparticles capped by rice-starch and gelatin. The structures of dried powders were investigated with the help of X-ray diffraction. The analysis revealed Ag-rich and Cu-rich phases with maximum solid solubility of Cu 9 atom per cent; 8 atom per cent and Ag 16 atom per cent; 14 atom per cent in rice-starch and gelatin capped samples respectively. Transmission electron microscope was used for knowing the particle size as well as to supplement FCC phase formations of Ag-rich and Cu-rich solid phases arrived at based on X-ray diffraction studies. The UV-Vis spectra of sols were examined for the formation and stability of alloy nanoparticles. The temporal evolution of LSPR curves gave us to assert that the sol is stable for more than two months. Small angle X-ray scattering in the sol state was extensively utilized to understand nature of suspensions in terms of fractals. Such a study is important for having a correlation between LSPR behaviors with those of nanoparticle dispersion in aqueous media. It is believed that this work will be a contribution to the emerging field of plasmonics that include applications in the area of photophysical processes and photochemical reactions.

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

    PubMed Central

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

    Ghanaatshoar, Majid; Moradi, Mehrdad; Tohidi, Parsis

    2014-10-01

    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.

  6. Temperature Dependence of Creep and Hardness of Sn-Ag-Cu Lead-Free Solder

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    The creep behavior and hardness of Sn-3.5Ag-0.7Cu solder were studied using Berkovich depth-sensing indentation at temperatures of 25C to 125C. Assuming a power-law relationship between the creep strain rate and stress, an activation energy of 40 kJ/mol and stress exponents of 7.4, 5.5, and 3.7 at 25C, 75C, and 125C, respectively, were obtained. The results revealed that, with increasing temperature, the creep penetration and steady-state creep strain rate increased whereas the stress exponent decreased. The stress exponent and activation energy results also suggested that the creep mechanism is dislocation climb, assisted by diffusion through dislocation cores in Sn. Furthermore, the hardness results exhibited a decreasing trend with increasing temperature, which is attributed to softening at high temperature.

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

    SciTech Connect

    Darsell, Jens T.; Weil, K. Scott

    2006-02-01

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

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

    SciTech Connect

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

    2004-05-01

    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 ~935C, 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

  9. Isotopic AgCuPb record of silver circulation through 16th18th century Spain

    PubMed Central

    Desaulty, Anne-Marie; Telouk, Philippe; Albalat, Emmanuelle; Albarde, Francis

    2011-01-01

    Estimating global fluxes of precious metals is key to understanding early monetary systems. This work adds silver (Ag) to the metals (Pb and Cu) used so far to trace the provenance of coinage through variations in isotopic abundances. Silver, copper, and lead isotopes were measured in 91 coins from the East Mediterranean Antiquity and Roman world, medieval western Europe, 16th18th century Spain, Mexico, and the Andes and show a great potential for provenance studies. Pre-1492 European silver can be distinguished from Mexican and Andean metal. European silver dominated Spanish coinage until Philip III, but had, 80 y later after the reign of Philip V, been flushed from the monetary mass and replaced by Mexican silver. PMID:21606351

  10. Isotopic Ag-Cu-Pb record of silver circulation through 16th-18th century Spain.

    PubMed

    Desaulty, Anne-Marie; Telouk, Philippe; Albalat, Emmanuelle; Albarde, Francis

    2011-05-31

    Estimating global fluxes of precious metals is key to understanding early monetary systems. This work adds silver (Ag) to the metals (Pb and Cu) used so far to trace the provenance of coinage through variations in isotopic abundances. Silver, copper, and lead isotopes were measured in 91 coins from the East Mediterranean Antiquity and Roman world, medieval western Europe, 16th-18th century Spain, Mexico, and the Andes and show a great potential for provenance studies. Pre-1492 European silver can be distinguished from Mexican and Andean metal. European silver dominated Spanish coinage until Philip III, but had, 80 y later after the reign of Philip V, been flushed from the monetary mass and replaced by Mexican silver. PMID:21606351

  11. Hydrogen mimicking the properties of coinage metal atoms in Cu and Ag monohydride clusters.

    PubMed

    Vetter, Karsten; Proch, Sebastian; Gantefr, Gerd F; Behera, Swayamprabha; Jena, Puru

    2013-12-28

    A systematic study of the electronic structure and equilibrium geometries of Cun, Cun-1H, Agn, and Agn-1H; n = 2-5 clusters is carried out using photoelectron spectroscopy (PES) experiments and density functional theory based calculations. Our objective is to see if the substitution of a coinage metal atom by hydrogen would retain the electronic structure of the parent metal cluster since both systems are isoelectronic. For clusters with n ? 3, we find that the measured PES and vertical detachment energies (VDEs) (i.e. energies necessary to remove an electron from the anionic Mn(-) (M = Cu, Ag) clusters without changing their geometries) are close to those of Mn-1H(-) clusters, suggesting that substitution of a metal atom with hydrogen does not perturb the electronic structure of the parent cluster anion significantly. Calculated VDEs agree very well with experiment validating the theoretical methods used as well as the geometries of the neutral and anionic clusters. PMID:24217243

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

    SciTech Connect

    Mechler, S.; Yahel, E.; Pershan, P.S.; Meron, M.; Lin, B.

    2012-02-06

    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.

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

    NASA Astrophysics Data System (ADS)

    Zhai, Wei; Hong, Zhenyu; Wei, Bingbo

    2007-08-01

    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 eutecticmixture of anomalous and regular structuresregular 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.

  14. Development of a new Pb-free solder: Sn-Ag-Cu

    SciTech Connect

    Miller, C.M.

    1995-02-10

    With the ever increasing awareness of the toxicity of Pb, significant pressure has been put on the electronics industry to get the Pb out of solder. This work pertains to the development and characterization of an alloy which is Pb-free, yet retains the proven positive qualities of current Sn-Pb solders while enhancing the shortcomings of Sn-Pb solder. The solder studied is the Sn-4.7Ag-1.7Cu wt% alloy. By utilizing a variety of experimental techniques the alloy was characterized. The alloy has a melting temperature of 217{degrees}C and exhibits eutectic melting behavior. The solder was examined by subjecting to different annealing schedules and examining the microstructural stability. The effect of cooling rate on the microstructure of the solder was also examined. Overall, this solder alloy shows great promise as a viable alternative to Pb-bearing solders and, as such, an application for a patent has been filed.

  15. Calculated surface, image and quantum well states in Ag/Cu(111) system

    NASA Astrophysics Data System (ADS)

    Bejan, Doina

    2013-09-01

    The energy spectrum and the probability densities of the surface, the image and the quantum well (QW) states of the Ag/Cu(111) system have been calculated function of the thickness of the silver film. The layer by layer energy spectrum and probability densities of this system are obtained as a solution of the Schrdinger equation using the discrete variable representation (DVR). In this equation we have used an analytical one-dimensional model potential derived from the potential of Chulkov et al. [1]. Our calculated energy spectrum and probability densities of the surface, image and QW states present coverage dependence in agreement with the experiments and other calculations of the surface states.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  17. Molecular dynamics simulation of Ni/Cu-Ni nanoparticles sintering under various crystallographic, thermodynamic and multi-nanoparticles conditions

    NASA Astrophysics Data System (ADS)

    Yousefi, Mehrdad; Khoie, Mohammad Mousavi

    2015-03-01

    Molecular dynamics simulation has been used to investigate the sintering process of Ni/Cu-Ni nanoparticles systems. In this regard, at first, the sintering process of two nanoparticles is studied. Then, a multi-nanoparticles system was chosen to investigate the stimulated real sintering process. Crystallographic orientation, temperature and element dissimilarity effects on the final morphology and mechanisms of two nanoparticles sintering are discussed as key physical factors. The results show that high sintering temperatures can lead to the plastic deformation domination on sintering mechanism in spite of the surface diffusion and co-crystallographic orientation nanoparticles have a great opportunity to shrink by plastic deformation. Dissimilar element nanoparticles sintering investigation shows that, the elements with lower melting point have a significant portion in diffusion and final morphology will be specified by these elements due to the higher diffusion rate of them.

  18. Low temperature spin dynamics in Cr{sub 7}Ni-Cu-Cr{sub 7}Ni coupled molecular rings

    SciTech Connect

    Bordonali, L.; Furukawa, Y.; Mariani, M.; Sabareesh, K. P. V.; Garlatti, E.; Borsa, F.

    2014-05-07

    Proton Nuclear Magnetic Resonance (NMR) relaxation measurements have been performed down to very low temperature (50?mK) to determine the effect of coupling two Cr{sub 7}Ni molecular rings via a Cu{sup 2+} ion. No difference in the spin dynamics was found from nuclear spin lattice relaxation down to 1.5?K. At lower temperature, the {sup 1}H-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 Cr{sub 7}Ni ring (140?mK)

  19. Hg(0) oxidative absorption by K(2)S(2)O(8) solution catalyzed by Ag(+) and Cu(2+).

    PubMed

    Xu, Xinhua; Ye, Qunfeng; Tang, Tingmei; Wang, Dahui

    2008-10-30

    The aqueous phase oxidation of gaseous elemental mercury (Hg(0)) by potassium persulfate (K(2)S(2)O(8), KPS) catalyzed by Ag(+) and Cu(2+) was investigated using a glass bubble column reactor. Concentrations of gaseous Hg(0) and aqueous Hg(2+) were measured by cold vapor generation atomic absorption spectrometry (CVAAS). The effects of several experimental parameters on the oxidation were studied; these include different types of catalysts, pHs and concentrations of potassium persulfate, temperatures, Hg(0) inlet concentrations and tertiary butanol (TBA). The results showed that the removal efficiency of Hg(0) increased with increasing concentration of potassium persulfate and catalysts Ag(+), Cu(2+) and Ag(+) provided better catalytic effect than Cu(2+). For example, in the presence of 5.0 mmol l(-1) KPS, the mercury removal efficiency could reach 75.4 and 97.0% for an Ag(+) concentration of 0.1 and 0.3 mmol l(-1), respectively, and 69.8 and 81.9% for 0.1 and 0.3 mmol l(-1) Cu(2+). On the other hand, high temperature and the introduction of TBA negatively affect the oxidation. Furthermore, the removal efficiency of Hg(0) was much greater in neutral solution than in either acidic or alkaline solution. But the influence of pH was almost eliminated upon the addition of Ag(+) and Cu(2+), and high Hg(0) inlet concentration also has positive impact on the removal efficiency of Hg(0). The possible catalytic oxidation mechanism of gaseous mercury by KPS was also proposed. PMID:18353543

  20. Mechanical properties of FeCo magnetic particles-based Sn-Ag-Cu solder composites

    NASA Astrophysics Data System (ADS)

    Xu, Siyang; Prasitthipayong, Anya; Pickel, Andrea D.; Habib, Ashfaque H.; McHenry, Michael E.

    2013-06-01

    We demonstrate magnetic nanoparticles (MNPs) in enabling lead-free solder reflow in RF fields and improved mechanical properties that impact solder joint reliability. Here, we report on Sn-Ag-Cu (SAC) alloys. SAC solder-FeCo MNP composites with 0, 1, 2, 3, and 4 wt. % FeCo MNP and the use of AC magnetic fields to achieve localized reflow. Electron microscopy of the as-reflowed samples show a decrease in the volume of Sn dendrite regions as well as smaller and more homogeneously dispersed Ag3Sn intermetallic compounds (IMCs) with increasing MNP concentrations. Mechanical properties of the composites were measured by nanoindentation. In pure solder samples and solder composites with 4 wt. % MNP, hardness values increased from 0.18 GPa to 0.20 GPa and the modulus increased from 39.22 GPa to 71.22 GPa. The stress exponent, reflecting creep resistance, increased from 12.85 of pure solder to 16.47 for solder composites with 4 wt. % MNP. Enhanced mechanical properties as compared with the as-prepared solder joints are explained in terms of grain boundary and dispersion strengthening resulting from the microstructural refinement.

  1. First-principles investigation of Ag-Cu alloy surfaces in an oxidizing environment

    SciTech Connect

    Piccinin, Simone; Stampfl, Catherine; Scheffler, Matthias

    2008-02-15

    In this paper, we investigate by means of first-principles density functional theory calculations the (111) surface of the Ag-Cu alloy under varying conditions of pressure of the surrounding oxygen atmosphere and temperature. This alloy has been recently proposed as a catalyst with improved selectivity for ethylene epoxidation with respect to pure silver, the catalyst commonly used in industrial applications. Here, we show that the presence of oxygen leads to copper segregation to the surface. Considering the surface free energy as a function of the surface composition, we construct the convex hull to investigate the stability of various surface structures. By including the dependence of the free surface energy on the oxygen chemical potential, we are able compute the phase diagram of the alloy as a function of temperature, pressure, and surface composition. We find that, at temperature and pressure, typically used in ethylene epoxidation, a number of structures can be present on the surface of the alloy, including clean Ag(111), thin layers of copper oxide, and thick oxidelike structures. These results are consistent with, and help explain, recent experimental results.

  2. Influence of nanoparticle addition on the formation and growth of intermetallic compounds (IMCs) in Cu/Sn-Ag-Cu/Cu solder joint during different thermal conditions

    NASA Astrophysics Data System (ADS)

    Tan, Ai Ting; Tan, Ai Wen; Yusof, Farazila

    2015-06-01

    Nanocomposite lead-free solders are gaining prominence as replacements for conventional lead-free solders such as Sn-Ag-Cu solder in the electronic packaging industry. They are fabricated by adding nanoparticles such as metallic and ceramic particles into conventional lead-free solder. It is reported that the addition of such nanoparticles could strengthen the solder matrix, refine the intermetallic compounds (IMCs) formed and suppress the growth of IMCs when the joint is subjected to different thermal conditions such as thermal aging and thermal cycling. In this paper, we first review the fundamental studies on the formation and growth of IMCs in lead-free solder joints. Subsequently, we discuss the effect of the addition of nanoparticles on IMC formation and their growth under several thermal conditions. Finally, an outlook on the future growth of research in the fabrication of nanocomposite solder is provided.

  3. In vitro chemical and biological effects of Ag, Cu and Cu + Zn adjunction in 46S6 bioactive glasses

    NASA Astrophysics Data System (ADS)

    Bunetel, L.; Wers, E.; Novella, A.; Bodin, A.; Pellen-Mussi, P.; Oudadesse, H.

    2015-09-01

    Three bioactive glasses belonging to the system SiO2-CaO- Na2O-P2O5 elaborated by conventional melt-quenching techniques were doped with silver, copper and copper + zinc. They were characterized using the usual physical methods. Human osteoblast cells Saos-2 and human endothelial cells EAhy926 were used for viability assays and to assess the metallic ions, self toxicity. Human monocyte cells THP-1 were used to measure interleukins IL1? and IL6 release. Glass chemical structures did not vary much on introduction of metal ions. A layer of hydroxyapatite was observed on every glass after 30 days of SBF immersion. A proliferative action was seen on Saos-2 after 24 h of incubation, EAhy926 growth was not affected. For both cell lines, a moderate cytotoxicity was found after 72 h. Dose-dependent toxic effects of Ag, Cu and Zn ions were observed on Saos-2 and EAhy926 cells. Measured CD50 of silver against these two cell lines were 8 to 20 fold lower than copper and zincs. Except undoped control glass, all doped glasses tested showed anti-inflammatory properties by preventing IL1? and IL6 excretion by differentiated THP-1. In conclusion, strictly monitored adjunction of metal ions to bioglasses ensures good anti-inflammatory properties without altering their biocompatibility.

  4. Improvement in Superconducting Properties of Air Processed SmBa2Cu3Oy with Ag2O Addition

    NASA Astrophysics Data System (ADS)

    Hashimoto, Y.; Muralidhar, M.; Koshizuka, N.; Inoue, K.; Murakami, M.

    We have investigated the influence of combined additions of Ag2O and BaO2 with the aim of producing good- quality single-grain SmBa2Cu3Oy 'Sm-123' material in air, and have characterized its superconducting performance with a SQUID magnetometer. The quality of the Sm-123 material was improved with increasing the Ag2O content from 0 wt% to 20 wt%. Magnetization measurements indicated that the Tc (onset) increases with Ag2O concentration i.e. from 86 K to 92 K for Ag2O addition of 10 wt% to 20 wt%. At 77 K, the critical current density of 10 kA/cm2 was achieved at 0 T (self-field). These results indicate that high-performance bulk Sm-123 materials can be fabricated even in air when optimum quantity of BaO2 and silver is added.

  5. Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers

    SciTech Connect

    Wei, Yajun Akansel, Serkan; Thersleff, Thomas; Brucas, Rimantas; Lansaker, Pia; Leifer, Klaus; Svedlindh, Peter; Harward, Ian; Celinski, Zbigniew; Ranjbar, Mojtaba; Dumas, Randy K.; Jana, Somnath; Pogoryelov, Yevgen; Karis, Olof; kerman, Johan

    2015-01-26

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO{sub 2} substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100?, the thickness of the Cu spacer was varied from 5 to 50?. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3?erg/cm{sup 2} for the sample with a 5? Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications.

  6. Tailoring of UV/violet plasmonic properties in Ag, and Cu coated Al concaves arrays

    NASA Astrophysics Data System (ADS)

    Norek, Ma?gorzata; W?odarski, Maksymilian; St?pniowski, Wojciech J.

    2014-09-01

    UV plasmonics is of particular interest because of large variety of applications, where the higher energy plasmon resonances would advance scientific achievements, including surface-enhanced Raman scattering (SERS) with UV excitation, ultrasensitive label-free detection of important biomolecules absorbing light in the UV, or the possibility for exerting control over photochemical reactions. Despite its potential, UV plasmonics is still in its infancy, mostly due to difficulties in fabrication of reproducible nanostructured materials operating in this high energy range. Here, we present a simple electrochemical method to fabricate regular arrays of aluminum concaves demonstrating plasmonic properties in UV/violet region. The method enables the preparation of concaves with well-controlled geometrical parameters such as interpore distance (Dc), and therefore, well controllable plasmon resonances. Moreover, the patterning is suitable for large scale production. The UV/violet properties of Al concaves can be further fine-tuned by Ag and Cu metals. The refractive index sensitivity (RIS) increases after the metals deposition as compared to RIS of pure Al nanohole arrays. The highest RIS of 404 nm/RIU was obtained for Cu coated Al nanoconcaves with the Dc = 460.8 nm, which is similar or better than the RIS values previously reported for other nanohole arrays, operating in visible/near IR range.

  7. K-shell ionization cross section for Ti, Fe, Cu, Zr, and Ag

    SciTech Connect

    Benka, O.; Geretschlager, M.

    1981-04-01

    Absolute K-shell ionisation cross sections have been measured for thin targets of Ti, Fe, Cu, Zr and Ag for protons in the energy range 85-790 keV and for thin targets of Ti, Fe and Cu for He ions in the energy range 190-750 keV. In addition the relative variation of the cross sections with energy has been determined with high accuracy. The experimental values are compared to the perturbed stationary state approximation (CPSSR) and the semiclassical approximation (SCA). The CPSSR theory provides the best overall agreement with experimental cross sections. For higher scaled energies the CPSSR theory predicts the energy dependence of the cross sections very well but in the lower energy range it overpredicts the cross sections by as much as a factor of two and this overprediction seems to increase with Z/sub 2/ at a fixed scaled energy y. The SCA theory predicts slightly too large ionisation cross sections except for the lowest pounds values. The relative variation of the cross sections with energy is not well described in either energy range.

  8. Modification of interface magnetic anisotropy by ion irradiation on epitaxial Cu/Ni/Cu(002)/ Si(100) films

    NASA Astrophysics Data System (ADS)

    Lee, J.-S.; Lee, K.-B.; Park, Y. J.; Kim, T. G.; Song, J. H.; Chae, K. H.; Lee, J.; Whang, C. N.; Jeong, K.; Kim, D.-H.; Shin, S.-C.

    2004-05-01

    Various x-ray scattering and magnetic measurements were employed to reveal changes in intrinsic structural and magnetic properties on epitaxial Cu/Ni(t)/Cu(002)/Si(100) thin films (t=20, 30, 60, and 90 ) before and after 1 MeV C+ ion irradiation. Torque magnetometer and grazing incidence x-ray diffraction measurements were carried out to understand relation between magnetic and structural properties, respectively. X-ray reflectivity measurements were performed to characterize interface roughness and intermixing. It is observed that effective magnetic anisotropy values of ion-irradiated films are negative over the entire nickel thickness range and the dominant factor of the reorientation of magnetic easy axis from surface normal to surface parallel is reduction of the interface magnetic anisotropy coefficient in spite of decreased interface mixing after ion irradiation.

  9. Bi2Sr2CaCu2O8 + x round wires with Ag/Al oxide dispersion strengthened sheaths: microstructure-properties relationships, enhanced mechanical behavior and reduced Cu depletion

    NASA Astrophysics Data System (ADS)

    Kajbafvala, Amir; Nachtrab, William; Wong, Terence; Schwartz, Justin

    2014-09-01

    Ag/Al alloys with various Al content (0.50 wt%, 0.75 wt%, 1.00 wt%, and 1.25 wt%) are made by powder metallurgy and used as the outer sheath material for Bi2Sr2CaCu2O8 + x (Bi2212)/Ag/AgAl multifilamentary round wires (RW). Bi2212/Ag/AgAl RW microstructural, mechanical and electrical properties are studied in various conditions, including as-drawn, after internal oxidation, and after partial melt processing (PMP). The results are compared with the behavior of a Bi2212/Ag/Ag0.20Mg wire of the same geometry. The grains in as-drawn Ag/Al alloys are found to be 25% smaller than those in the corresponding Ag/0.20 wt%Mg, but after PMP, the Ag/Al and Ag/0.20 wt%Mg grain sizes are comparable. Tensile tests show that Bi2212/Ag/AgAl green wires have yield strength (YS) of 115 MPa, nearly 65% higher than that of Bi2212/Ag/Ag0.20Mg. After PMP, the Bi2212/Ag/AgAl YS is about 35% greater than that of Bi2212/Ag/Ag0.20Mg. Furthermore, Bi2212/Ag/AgAl wires exhibit higher ultimate tensile strength and modulus and twice the elongation-to-failure. Atomic resolution high-angle annular dark-field scanning transmission electron microscopy, high resolution transmission electron microscopy and energy dispersive spectroscopy demonstrate the formation of nanosize MgO and Al2O3 precipitates via internal oxidation. Large spherical MgO precipitates are observed on the Ag grain boundaries of Ag/0.20 wt%Mg alloy, whereas the Al2O3 precipitates are distributed homogenously in the dispersion-strengthened (DS) Ag/Al alloy. Furthermore, it is found that less Cu diffused from the Bi2212 filaments in the Bi2212/Ag/Ag0.75Al wire during PMP than from the filaments in the Bi2212/Ag/Ag0.20Mg wire. These results show that DS Ag/Al alloy is a strong candidate for improved Bi2212 wire.

  10. Nonlocal Superelastic Model of Size-Dependent Hardening and Dissipation in Single Crystal Cu-Al-Ni Shape Memory Alloys

    E-print Network

    Qiao, Lei

    We propose a nonlocal continuum model to describe the size-dependent superelastic effect observed in recent experiments of single crystal Cu-Al-Ni shape memory alloys. The model introduces two length scales, one in the ...

  11. Study of fatigue behavior of Ti-Ni-Cu5% wires for different heat treatments

    NASA Astrophysics Data System (ADS)

    Lopez-Cullar, E.; Gunin, G.; Morin, M.

    2003-10-01

    Changes of memory properties and fatigue life of the Shape Memory Alloys (SMA) are very important for practical applications. In this work, several heat treatments have been done on a Ti-Ni-Cu5% wire. The thermomechanical properties during the fatigue life have been analyzed at several stress levels for each heat treatment. Ti-Ni-Cu wires were loaded by a static uniaxial tensile stress and submitted to thermal cycling. The wires were cycled until failure in an oil bath, cooled by this one and heated by electrical current. One modified Whier curve bas been obtained, the influence of the heat treatment temperature, applied stress and cycle number are analyzed. Finally, this work allows to select a heat treatment as a function of the application.

  12. Crystallization of amorphous ribbon in NiTi-Cu shape memory alloy

    SciTech Connect

    Yang, F.; Ma, J.L.; Pu, Z.J.; Wu, K.H.

    1998-12-31

    The objective of this work is to study the crystallization process of the amorphous ribbon of NiTi-Cu based shape memory alloys. An amorphous material with a composition of Ti{sub 50}Ni{sub 25}Cu{sub 25} was used to conduct this study. First, a study was conducted to understand the crystallization kinetics of this amorphous material at the isothermal model and continuous heating mode, respectively. The characteristic parameters associated with the crystallization process, such as the start and finish time for isothermal crystallization, the peak temperature for continuous heating crystallization, and activation energy, are obtained. Based on the study of experimental data of crystallization kinetics, a series of isothermal annealing experiments was conducted to study the crystallization process and microstructure of fully crystallized materials. The TEM micrograph shows the crystal phase growths in the amorphous matrix as a perfect geometric sphere. A system analysis was conducted to explain the crystallization micro-mechanism.

  13. Calculation of Phonon Conductivity and Seebeck Coefficient in Cu-Ni Alloy

    NASA Astrophysics Data System (ADS)

    Konishi, Yusuke; Asai, Yoshihiro

    2015-03-01

    In recent years, thermoelectric materials have been attracting a lot of attention because they are expected to be applied for utilization of waste heat. Many kinds of materials are studied for this purpose; semiconductors, alloys, organic materials, etc. In 2010, a giant Peltier effect was observed in a Cu-Ni/Au junction. It is considered that this giant Peltier effect is caused by nano-scale phase separation formed in the sputtering process. Although this material is a great candidate for a thermoelectric material, we need to find the condition for a large thermoelectric coefficient that requires a large Seebeck coefficient, large electric conductivity, and small phonon conductivity. We calculated phonon conductivity in Cu-Ni alloy by using nonequilibrium molecular dynamics simulation and calculated Seebeck coefficients via ab-initio methods.

  14. Oxidation parameters determination of Cu-Al-Ni-Fe shape-memory alloy at high temperatures

    NASA Astrophysics Data System (ADS)

    Kk, Mediha; Yildiz, Koksal

    2014-09-01

    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.

  15. Structure and energetics of high index Fe, Al, Cu and Ni surfaces using equivalent crystal theory

    NASA Technical Reports Server (NTRS)

    Rodriguez, Agustin M.; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

    Equivalent crystal theory (ECT) is applied to the study of multilayer relaxations and surface energies of high-index faces of Fe, Al, Ni, and Cu. Changes in interplanar spacing as well as registry of planes close to the surface and the ensuing surface energies changes are discussed in reference to available experimental data and other theoretical calculations. Since ECT is a semiempirical method, the dependence of the results on the variation of the input used was investigated.

  16. Bulk Properties of Ni3Al(gamma') With Cu and Au Additions

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ferrante, John

    1995-01-01

    The BFS method for alloys is applied to the study of 200 alloys obtained from adding Cu and Au impurities to a Ni3Al matrix. We analyze the trends in the bulk properties of these alloys (heat of formation, lattice parameter, and bulk modulus) and detect specific alloy compositions for which these quantities have particular values. A detailed analysis of the atomic interactions that lead to the preferred ordering patterns is presented.

  17. Magmatic Controls on the Genesis of Ni-Cu-PGE Sulphide Mineralisation on Mars

    NASA Astrophysics Data System (ADS)

    Baumgartner, R. J.; Fiorentini, M.; Baratoux, D.; Micklethwaite, S.; Sener, K.; McCuaig, C.

    2014-12-01

    Widespread igneous activity, which shows striking mineralogical, petrographical and chemical similarities with terrestrial komatiites and ferropicrites, intensely affected, reshaped and buried the primordial Martian crust. This study evaluates for the first time whether the broad igneous activity on Mars may have led to the formation of orthomagmatic Ni-Cu-PGE sulphide mineralisation similar to that associated with terrestrial komatiites and ferropicrites. Particular focus is laid on two different components of the Martian Ni-Cu-PGE sulphide mineral system: 1) the potential metal and sulphur fertility of source regions, and 2) the physical/chemical processes that enable sulphide supersaturation and metal concentration into an immiscible sulphide liquid. We show that potentially metal-rich Martian mantle melts likely reach sulphide saturation within 20-35 wt% of simple silicate fractionation; a value that is comparable to that of the terrestrial equivalents (i.e. ferropicrites and komatiites). However, the majority of terrestrial world-class Ni-Cu-PGE sulphide deposits originated by the assimilation of crustal sulphur-rich country rocks, allowing the attainment of sulphide supersaturation and liquid segregation during early stages of magma evolution. The high sulphur content in Martian crustal lithologies, ranging from sulphide bearing magmatic rocks to sulphate-rich regoliths and sedimentary deposits, imply that mantle melts potentially assimilated significant amounts of crustal sulphur during their ascent and emplacement. As a main outcome we show that channelled and fluid lava flows, which potentially emplaced and incised into these sulphur-rich crustal lithologies, are the most promising systems that may have led to the formation of Ni-Cu-PGE sulphide mineralisation on Mars.

  18. Low energy ($p,?$) reactions in Ni and Cu nuclei using microscopic optical model

    E-print Network

    G. Gangopadhyay

    2010-08-05

    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.

  19. Duplex Oxide Formation during Transient Oxidation of Cu-5%Ni(001) Investigated by In situ UHV-TEM and XPS

    SciTech Connect

    Yang, J.C.; Starr, D.; Kang, Y.; Luo, L.; Tong, X.; Zhou, G.

    2012-05-20

    The transient oxidation stage of a model metal alloy thin film was characterized with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and analytic high-resolution TEM. We observed the formations of nanosized NiO and Cu{sub 2}O islands when Cu-5a5%Ni(100) was exposed to oxygen partial pressure, pO{sub 2} = 1 x 10{sup -4} Torr and various temperatures in situ. At 350 C epitaxial Cu{sub 2}O islands formed initially and then NiO islands appeared on the surface of the Cu{sub 2}O island, whereas at 750 C NiO appeared first. XPS and TEM was used to reveal a sequential formation of NiO and then Cu{sub 2}O islands at 550 C. The temperature-dependant oxide selection may be due to an increase of the diffusivity of Ni in Cu with increasing temperature.

  20. Removal of Cu(II) and Ni(II) from aqueous solution by lignite-based humic acids

    SciTech Connect

    Arslan, G.; Cetin, S.; Pehlivan, E.

    2007-07-01

    The removal of Cu(II) and Ni(II) metal ions from an aqueous solution were investigated by using humic acids (HAs) in a batch arrangement. HAs were prepared by using alkaline extraction, following sedimentation and acidic precipitation from three Turkish lignites: Ilgin, Beysehir, and Ermenek. The interactions of Cu(II) and Ni(II) with solid HAs and influence of three parameters (initial metal concentration, solution pH and temperature) on the removal of metals were studied. Adsorption equilibrium was achieved in about 120 min for Cu(II) and Ni(II) ions. The sorption of Cu(II) and Ni(II) on the surface of HAs depended strongly on the pH, and increased with increasing pH and the initial concentration of metal. The sorption of Cu(II) was higher than that of Ni(II) for HAs. The equilibrium relationship between adsorbent and adsorbate is described by adsorption isotherms at a fixed temperature 35 {sup o}C, at pH about 4.0. The Langmuir adsorption isotherm was used to describe observed sorption phenomena. Adsorption isotherms and kinetics data of Cu(II) and Ni(II) ions removed by HAs are presented and discussed.

  1. Adsorption of Cu(2+), Cd(2+) and Ni(2+) from aqueous single metal solutions on graphene oxide membranes.

    PubMed

    Tan, Ping; Sun, Jian; Hu, Yongyou; Fang, Zheng; Bi, Qi; Chen, Yuancai; Cheng, Jianhua

    2015-10-30

    Novel, highly ordered layered graphene oxide (GO) membranes with larger interlayer spacing were prepared by induced directional flow and were used as adsorbents for the removal of Cu(2+), Cd(2+) and Ni(2+) from aqueous solutions. The effects of pH, ionic strength, contact time, metal ion concentration and cycle time on Cu(2+), Cd(2+) and Ni(2+) sorption were investigated. The results indicated that the adsorption of Cu(2+), Cd(2+) and Ni(2+) onto GO membranes was greatly influenced by the pH and weakly affected by the ionic strength. The adsorption isotherms for Cu(2+), Cd(2+) and Ni(2+) were well fitted by the Langmuir model. The maximum adsorption capacities of the GO membranes for Cu(2+), Cd(2+) and Ni(2+) were approximately 72.6, 83.8 and 62.3 mg/g, respectively. The adsorption kinetics of Cu(2+), Cd(2+) and Ni(2+) onto GO membranes followed the pseudo-second-order model. The adsorption equilibrium was reached in a shorter time. The GO membranes can be regenerated more than six times based on their adsorption/desorption cycles, with a slight loss in the adsorption capacity. The results demonstrated that the GO membranes can be used as effective adsorbents for heavy metal removal from water. PMID:25978188

  2. Nanocelluloses and their phosphorylated derivatives for selective adsorption of Ag(+), Cu(2+) and Fe(3+) from industrial effluents.

    PubMed

    Liu, Peng; Borrell, Pere Ferrer; Boi?, Mojca; Kokol, Vanja; Oksman, Kristiina; Mathew, Aji P

    2015-08-30

    The potential of nanoscaled cellulose and enzymatically phosphorylated derivatives as bio-adsorbents to remove metal ions (Ag(+), Cu(2+) and Fe(3+)) from model water and industrial effluents is demonstrated. Introduction of phosphate groups onto nanocelluloses significantly improved the metal sorption velocity and sorption capacity. The removal efficiency was considered to be driven by the high surface area of these nanomaterials as well as the nature and density of functional groups on the nanocellulose surface. Generally, in the solutions containing only single types of metal ions, the metal ion selectivity was in the order Ag(+)>Cu(2+)>Fe(3+), while in the case of mixtures of ions, the order changed to Ag(+)>Fe(3+)>Cu(2+), irrespective of the surface functionality of the nanocellulose. In the case of industrial effluent from the mirror making industry, 99% removal of Cu(2+) and Fe(3+) by phosphorylated nanocellulose was observed. The study showed that phosphorylated nanocelluloses are highly efficient biomaterials for scavenging multiple metal ions, simultaneously, from industrial effluents. PMID:25867590

  3. Hydrogen evolution from water using Ag(x)Cu(1-x)GaSe2 photocathodes under visible light.

    PubMed

    Zhang, Li; Minegishi, Tsutomu; Kubota, Jun; Domen, Kazunari

    2014-04-01

    Photoelectrochemical (PEC) water splitting using CuGaSe2 (CGSe) thin film photocathodes modified by partial substitution of Cu with Ag was investigated. The AgxCu1-xGaSe2 (ACGSe) thin films were deposited onto Mo-coated soda-lime glass substrates by means of co-evaporation using a molecular beam epitaxy (MBE) system. The valence band maximum (VBM) potential of ACGSe is deeper than that of CGSe, and its grain size is greatly increased compared to that of CGSe. A Pt and CdS modified ACGSe electrode (Pt/CdS/ACGSe) with a Ag/(Cu + Ag) ratio of about 5% showed a cathodic photocurrent of 8.1 mA cm(-2) at 0 VRHE and an onset potential of 0.70 VRHE (defined as a cathodic photocurrent of 0.05 mA cm(-2)) under simulated sunlight in a 0.1 M Na2SO4 solution (pH 9.5). Moreover, Pt/CdS/ACGSe exhibited a stable cathodic photocurrent for over 55 h, with no clear decrease. PMID:24562096

  4. Enhanced oxidation-resistant Cu-Ni core-shell nanowires: controllable one-pot synthesis and solution processing to transparent flexible heaters.

    PubMed

    Chen, Jianyu; Chen, Jun; Li, Yi; Zhou, Weixin; Feng, Xiaomiao; Huang, Qingli; Zheng, Jian-Guo; Liu, Ruiqing; Ma, Yanwen; Huang, Wei

    2015-10-28

    Coating nickel onto copper nanowires (Cu NWs) by one-pot synthesis is an efficient approach to improving the oxidation resistance of the nanowires. Because Ni is much less conductive than Cu, it is of great importance to understand the relationship between the thickness of the Ni coating layer and the properties of NWs. Here we demonstrate one-pot synthesis of Cu-Ni core-shell NWs with a tunable Ni thickness by simply varying the Cu and Ni mole ratio in the precursor. We have observed that an increase in Ni thickness decreases the aspect ratio, surface smoothness and network conductivity of the resulting NWs. However, Cu-Ni NWs with a thicker Ni layer display higher oxidation temperature. The optimal Cu-Ni NWs, which were prepared using a Cu(2+)/Ni(2+) molar ratio of 1/1, have a Ni-layer thickness of about 10 nm and the onset oxidation temperature of 270 C. The derived transparent conductive films present a transmittance of 76% and a sheet resistance of 300 ? sq(-1). The flexible heater constructed from such high quality Cu-Ni NW films demonstrates effective performance in heating and defrosting. PMID:26411899

  5. Strengthening of CuNiSi alloy using high-pressure torsion and aging

    SciTech Connect

    Lee, Seungwon; Matsunaga, Hirotaka; Sauvage, Xavier; Horita, Zenji

    2014-04-01

    An age-hardenable Cu2.9%Ni0.6%Si alloy was subjected to high-pressure torsion. Aging behavior was investigated in terms of hardness, electrical conductivity and microstructural features. Transmission electron microscopy showed that the grain size is refined to ? 150 nm and the Vickers microhardness was significantly increased through the HPT processing. Aging treatment of the HPT-processed alloy led to a further increase in the hardness. Electrical conductivity is also improved with the aging treatment. It was confirmed that the simultaneous strengthening by grain refinement and fine precipitation is achieved while maintaining high electrical conductivity. Three dimensional atom probe analysis including high-resolution transmission electron microscopy revealed that nanosized precipitates having compositions of a metastable Cu{sub 3}Ni{sub 5}Si{sub 2} phase and a stable NiSi phase were formed in the Cu matrix by aging of the HPT-processed samples and these particles are responsible for the additional increase in strength after the HPT processing. - Highlights: Grain refinement is achieved in Corson alloy the size of ?150nm by HPT. Aging at 300C after HPT leads to further increase in the mechanical property. Electrical conductivity reaches 40% IACS after aging for 100 h. 3D-APT revealed the formation of nanosized-precipitates during aging treatment. Simultaneous hardening in both grain refinement and precipitation is achieved.

  6. L -shell Coster-Kronig transition probabilities in Ni, Cu, and Mo measured with synchrotron radiation

    SciTech Connect

    Sorensen, S.L.; Schaphorst, S.J.; Whitfield, S.B.; Crasemann, B. ); Carr, R. )

    1991-07-01

    A recent technique, based on differential subshell ionization by tuned synchrotron radiation, has been applied to measurements of {ital L}-subshell Coster-Kronig yields of Ni, Cu, and Mo from {ital L}{sub 2} and {ital L}{sub 3} Auger spectra. Results for Ni are {ital f}{sub 23}=0.6+0.2, {ital f}{sub 12}=0.4+0.2, and {ital f}{sub 13}=0.5+0.2; for Cu, {ital f}{sub 23}=0.8+0.1, {ital f}{sub 12}=0.44+0.06, and {ital f}{sub 13}=0.3+0.2; for Mo, {ital f}{sub 23}=0.15+0.02, {ital f}{sub 12}=0.15+0.02, and {ital f}{sub 13}=0.61+0.06. Measured transition probabilities are compared with previously available information. The results are generally consistent with the body of theoretical and experimental data. For Ni and Cu, the present measurements of {ital f}{sub 23} confirm that the {ital L}{sub 2}-{ital L}{sub 3}{ital M4,5} Coster-Kronig channel is accessible in the metals, even though it is energetically cut off in free atoms. Further improvements in synchrotron-radiation sources are likely to make it possible to throw light on several critical questions by means of the present method.

  7. Effect of Y2O3 nanoparticles addition on the microstructure and tensile strength of Cu/Sn3.0Ag0.5Cu solder joint

    NASA Astrophysics Data System (ADS)

    Yang, L. M.; Zhang, Z. F.

    2015-01-01

    A sort of composite solder was produced by adding Y2O3 nanoparticles in Sn3.0Ag0.5Cu solder. The microstructure and tensile strength of solder joint were investigated. It was found that the size of intermetallic compounds and tensile strength of solder joint were notably influenced by the nanoparticles. The growth behaviors of intermetallic compounds Ag3Sn and Cu6Sn5 were suppressed due to the addition of Y2O3 nanoparticles. The tensile test results revealed that the strength of composite solder joint was higher than that of solder joint without nanoparticles addition. It is indicated that Y2O3 nanoparticles should play important roles in strengthening of joint by hampering dislocation movement.

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

    SciTech Connect

    Yin Wenlong; Feng Kai; Hao Wenyu; Yao Jiyong; Wu Yicheng

    2012-08-15

    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.

  9. The nature of chemisorbed oxygen on Ni(100) and Cu(100)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.; Walch, S. P.; Bagus, P. S.; Brundle, C. R.

    1984-01-01

    Model calculations indicate two low-lying states for the interaction of O with Ni and Cu(100). The oxide state is approximately 1 eV more stable and its R(perpendicular) for Ni(100) is consistent with the experimental value for Ni(100), indicating only one type of stable chemisorption bond. This agrees with XPS (X-ray photoemission spectroscopy) and EXAFS (extended X-ray absorption fine structure) data for the observed LEED (low energy electron diffraction) structures. Interpretations of EELS (electron energy loss spectroscopy) data in terms of a radical state forthe p(2x2) and the oxide state for the c(2x2) structure must be seriously questioned.

  10. Engineering a Cu2O/NiO/Cu2MoS4 hybrid photocathode for H2 generation in water.

    PubMed

    Yang, Chen; Tran, Phong D; Boix, Pablo P; Bassi, Prince S; Yantara, Natalia; Wong, Lydia H; Barber, James

    2014-06-21

    We report a scalable process for fabricating a multiple-layer hybrid photocathode, namely Cu2O/NiO/Cu2MoS4, for H2 generation in water. In pH 5 solution and under 1 sun illumination, the photocathode showed interesting photocatalytic properties. The onset photocurrent was recorded at +0.45 V vs. RHE, while at 0 V vs. RHE, a photocurrent density of 1.25 mA cm(-2) was obtained. It was found that the NiO interlayer enhances charge transfer from the Cu2O light harvester to the Cu2MoS4 hydrogen evolution reaction electrocatalyst which in turn accelerates charge transfer at the electrode/electrolyte interface, and therefore improves the photocatalytic properties of the Cu2O photocathode. PMID:24838221

  11. Vibrational spectra of Cu(II), Cu(I), Ni(II), Pd(II), Pt(II) and Hg(II) complexes with dithizone

    NASA Astrophysics Data System (ADS)

    Michalska, Danuta; Kowal, Andrzei T.

    1985-01-01

    The far i.r. spectra of Cu(II), Cu(I) and Ni(II) complexes with dithizone are presented. The assignment of the metalligand vibrations was carried out by 63Cu/ 65Cu and 58Ni/ 62Ni isotopic substitution. Resonance Raman spectra of Hg(II), Pd(II), Pt(II), Cu(II) and Cu(I) complexes were measured. Excitation profiles of the enhanced Raman modes of Hg(II) dithizonate allowed us to identify vibrations associated with the chromophoric azo group. It is concluded that Pd(II) dithizonate and Pt(II) dithizonate are N, S coordinated and form a trans square-planar structure, whereas in Cu(I) dithizonate the Cu(I) ion forms a strong bond with the sulfur atom and a weak secondary bond with the azo nitrogen as well as with sulfur atoms from the neighboring molecules conferring a tetrahedral configuration on the coordination sphere and polymeric structure of the complex.

  12. NaNiO2 480 K Cu3V2O7(OH)22H2O

    E-print Network

    Goda, Keisuke

    1) 2) 3) NaNiO2 480 K 4) 5) 6) 7) Cu3V2O7(OH)22H2O 8) 9)10) 11) 1/2 Nature Communications #12;2 1/2 Cu3V2O7(OH)22H2O 0.7 mm 1 a 1;3 1 K 13) ) 14) 1 Cu3V2O7(OH)22H2O (a) (b) b (c) c 2 Cu3V2O7(OH)22H2O Cu1 d TS = 310 K x2

  13. Phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy

    E-print Network

    Jones, N. G.; Frezza, A.; Stone, H. J.

    2014-07-27

    The phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy has been studied following 1000 h exposures at 700, 850 and 1000 C. Above1000 C, the material comprised of two fcc solid solutions, one a multi-element phase and the other a Cu rich...

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

    PubMed

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

    2014-10-14

    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

  15. Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

    NASA Astrophysics Data System (ADS)

    Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

    2014-10-01

    Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

  16. Electroless Ni-Cu-P/nano-graphite composite coatings for bipolar plates of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Lee, Cheng-Kuo

    2012-12-01

    This study evaluates the effects of an electroless Ni-Cu-P/nano-graphite composite coating on the surface characteristics of anodized 5083 aluminum alloy, including electrical resistivity, corrosion resistance of the alloy in a simulated solution of 0.5 M H2SO4 + 2 ppm NaF in polymer electrolyte membrane fuel cells (PEMFCs). The co-deposition and adhesion of the composite coatings on a 5083 substrate are enhanced by an anodizing process. The electroless Ni-Cu-P plating solution is prepared by adding different CuSO45H2O concentrations into the electroless Ni-P plating solution and adding nano-graphite (15-40 nm) particles to form the Ni-Cu-P/nano-graphite composite coatings. Experimental results indicate that the electroless Ni-Cu-P/nano-graphite composite coating enhances the hardness, conductivity, corrosion resistance of the 5083 substrate in the corrosive solution. The anodizing treatment enhances the electroless composite coatings by providing better uniformity, density, and adhesion compared to substrate without anodizing treatment. The electroless Ni-Cu-P/nano-graphite composite coating deposited on the optimal anodized 5083 substrate at a low CuSO45H2O concentration of 0.25 g l-1 with 20 g l-1 nano-graphite added have the best surface structure, highest hardness, electrical conductivity and corrosion resistance. Therefore, this novel electroless Ni-Cu-P/nano-graphite composite-coated 5083 aluminum alloy has potential applications in bipolar plates of PEM fuel cells.

  17. Secondary ion emission matrix effects in a metal overlayer system: CO and O 2 adsorption on Cu/Ni(1 0 0)

    NASA Astrophysics Data System (ADS)

    Karolewski, M. A.; Cavell, R. G.

    2002-06-01

    The enhancement of secondary ion (SI) yields (Cu +, Ni +) by CO and O 2 adsorption on Cu/Ni(1 0 0) surfaces has been studied as a function of Cu coverage (0-1 monolayers (ML)) using secondary ion mass spectrometry (SIMS). The experiments measure an enhancement factor (EF), which is the ratio between the SI yield (for Cu + or Ni +) measured after CO (or O 2) exposure, to the corresponding SI yield measured for the clean surface prior to the exposure. Typical EFs for both Cu + and Ni + are found to be 100 for CO/Cu/Ni(1 0 0) and 15 for O/Cu/Ni(1 0 0). A simple tunnelling model, with parameters tested previously for clean Cu/Ni(1 0 0) surfaces, was used to estimate the influence of work function variations on the magnitudes of EFs produced by CO and O 2 adsorption. The predictions of this model are smaller (by an order of magnitude) than the observed EFs, which suggests that the EFs are too large to be attributed to work function variations alone. EFs produced by CO adsorption (10 L exposure) depend exponentially on the CO uptake by the Cu/Ni(1 0 0) surfaces. However, Ni atoms, to which CO bonds exclusively, show a greater propensity than Cu atoms to form SIs. The observation of an EF of 100 for Cu + emitted from 0.1 ML Cu/ Ni(1 0 0)+ CO, and of 5 for Ni + emitted from 1 ML Cu/ Ni(1 0 0)+ O2, implies the operation of non-local SI enhancement mechanisms, since in neither case does the SI precursor atom bond directly to the adsorbate species. However, for both CO and O 2 adsorption, the highest EFs seem to be associated with structural situations which favour direct bonding between metal and adsorbate atoms.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  19. Enhanced oxidation-resistant Cu-Ni core-shell nanowires: controllable one-pot synthesis and solution processing to transparent flexible heaters

    NASA Astrophysics Data System (ADS)

    Chen, Jianyu; Chen, Jun; Li, Yi; Zhou, Weixin; Feng, Xiaomiao; Huang, Qingli; Zheng, Jian-Guo; Liu, Ruiqing; Ma, Yanwen; Huang, Wei

    2015-10-01

    Coating nickel onto copper nanowires (Cu NWs) by one-pot synthesis is an efficient approach to improving the oxidation resistance of the nanowires. Because Ni is much less conductive than Cu, it is of great importance to understand the relationship between the thickness of the Ni coating layer and the properties of NWs. Here we demonstrate one-pot synthesis of Cu-Ni core-shell NWs with a tunable Ni thickness by simply varying the Cu and Ni mole ratio in the precursor. We have observed that an increase in Ni thickness decreases the aspect ratio, surface smoothness and network conductivity of the resulting NWs. However, Cu-Ni NWs with a thicker Ni layer display higher oxidation temperature. The optimal Cu-Ni NWs, which were prepared using a Cu2+/Ni2+ molar ratio of 1/1, have a Ni-layer thickness of about 10 nm and the onset oxidation temperature of 270 C. The derived transparent conductive films present a transmittance of 76% and a sheet resistance of 300 ? sq-1. The flexible heater constructed from such high quality Cu-Ni NW films demonstrates effective performance in heating and defrosting.Coating nickel onto copper nanowires (Cu NWs) by one-pot synthesis is an efficient approach to improving the oxidation resistance of the nanowires. Because Ni is much less conductive than Cu, it is of great importance to understand the relationship between the thickness of the Ni coating layer and the properties of NWs. Here we demonstrate one-pot synthesis of Cu-Ni core-shell NWs with a tunable Ni thickness by simply varying the Cu and Ni mole ratio in the precursor. We have observed that an increase in Ni thickness decreases the aspect ratio, surface smoothness and network conductivity of the resulting NWs. However, Cu-Ni NWs with a thicker Ni layer display higher oxidation temperature. The optimal Cu-Ni NWs, which were prepared using a Cu2+/Ni2+ molar ratio of 1/1, have a Ni-layer thickness of about 10 nm and the onset oxidation temperature of 270 C. The derived transparent conductive films present a transmittance of 76% and a sheet resistance of 300 ? sq-1. The flexible heater constructed from such high quality Cu-Ni NW films demonstrates effective performance in heating and defrosting. Electronic supplementary information (ESI) available: Detailed experimental conditions, SEM images and EDS elemental maps of other Cu-Ni NWs, schematic of the neat Cu and Cu-Ni NW growth process, TG and DTG curves of other Cu-Ni NWs, flexibility tests, photographs and SEM images of other Cu-Ni TCFs, and infrared thermal images of flexible heaters. See DOI: 10.1039/c5nr04930j

  20. AC losses in Ag-sheathed Bi2223 tapes with Ca 2CuO 3 as interfilamentary resistive barriers

    NASA Astrophysics Data System (ADS)

    Inada, R.; Iwata, Y.; Tateyama, K.; Nakamura, Y.; Oota, A.; Zhang, P. X.

    2006-10-01

    In this study, we prepared the Bi2223 multifilamentary tapes with Ca2CuO3 as interfilamentary resistive barriers and evaluated their AC magnetization loss properties at 77 K. The Bi2223 tapes with thin barrier layers of Ca2CuO3 around the filaments were prepared by using a standard powder-in-tube (PIT) method. To fabricate the Ca2CuO3 layers around each filament, the outside surface of monocore Ag-sheathed wires was coated by Ca2CuO3 with the slurry. After the heat treatment to decompose and evaporate the organic binder in the slurry, the several coated monocore wires were stacked and packed into another Ag-tube. Then, the packed tube was drawn and rolled into tape shape. The tape was subsequently sintered to form Bi2223 phase inside filaments. The AC magnetization losses in an AC transverse magnetic field were measured by a pick-up coil method. The loss properties in the barrier tape were compared with those in the tape without barriers. The results indicated that introducing Ca2CuO3 barriers is very effective to suppress the electromagnetic coupling among the filaments and also to reduce the magnetization losses under parallel transverse field.

  1. Magnetic properties and magnetocaloric effect at room temperature of Ni50- x Ag x Mn37Sn13 alloys

    NASA Astrophysics Data System (ADS)

    Thanh, Tran Dang; Mai, Nguyen Thi; Dan, Nguyen Huy; Phan, The-Long; Yu, Seong-Cho

    2014-11-01

    In this work, we present a detailed study of the magnetic properties and the magnetocaloric effect at room temperature of Ni50- x Ag x Mn37Sn13 alloys with x = 1, 2, and 4, which were prepared by using an arc-melting method. Experimental results reveal that a partial replacement of Ag for Ni leads to a decrease in the anti-FM phase in the alloys. In addition, the martensitic-austenitic phase transition shifts towards lower temperature and is broaded. The Curie temperature ( T C A ) for the austenitic phase also shifts toward to lower temperature, but not by much. The Curie temperature was found to be 308, 305, and 298 K for x = 1, 2, and 4, respectively. The magnetic entropy change (? S m ) of the samples was calculated by using isothermal magnetization data. Under an applied magnetic field change of 10 kOe, the maximum value of ? S m (|? S max |) was achieved at around room temperature and did not change much (~0.8 Jkg-1K-1) with increasing Ag-doping concentration. Particularly, the M 2 vs. H/ M curves prove that all the samples exhibited a second-order magnetic phase transition. Based on Landau's phase-transition theory and careful analyses of the magnetic data around the T C A , we have determined the critical parameters ?, ?, ?, and T C . The results show that the ? values are located between those expected for the 3D-Heisenberg model ( ? = 0.365) and mean-field theory ( ? = 0.5). Such a result proves the coexistence of short-range and long-range ferromagnetic interactions in Ni50- x Ag x Mn37Sn13 alloys. The nature of the changes in the critical parameters and the |? S max | is thoroughly discussed by means of structural analyses.

  2. Efficient enhancement of hydrogen production by Ag/Cu{sub 2}O/ZnO tandem triple-junction photoelectrochemical cell

    SciTech Connect

    Liu, Ying; Ren, Feng Chen, Chao; Liu, Chang; Xing, Zhuo; Liu, Dan; Xiao, Xiangheng; Wu, Wei; Zheng, Xudong; Liu, Yichao; Jiang, Changzhong; Shen, Shaohua; Fu, Yanming

    2015-03-23

    Highly efficient semiconductor photoelectrodes for solar hydrogen production through photocatalytic water splitting are a promising and challenge solution to solve the energy problems. In this work, Ag/Cu{sub 2}O/ZnO tandem triple-junction photoelectrode was designed and prepared. An increase of 11 times of photocurrent is achieved in the Ag/Cu{sub 2}O/ZnO photoelectrode comparing to that of the Cu{sub 2}O film. The high performance of the Ag/Cu{sub 2}O/ZnO film is due to the optimized design of the tandem triple-junction structure, where the localized surface Plasmon resonance of Ag and the hetero-junctions efficiently absorb solar energy, produce, and separate electron-hole pairs in the photocathode.

  3. Texture improvements in the high-temperature superconducting Bi?Sr?Ca?Cu?Ox̳/Ag system via surface energy driven grain alignment

    E-print Network

    Vodhanel, Mark E

    2005-01-01

    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 ...

  4. Characterization of Few Layer Graphene films Grown on Cu, Cu-Ni and SiC Substrates

    NASA Astrophysics Data System (ADS)

    Tyagi, P.; McNeilan, J. D.; Abel, J.; Nelson, F. J.; Robinson, Z. R.; Moore, R. L.; Diebold, A. C.; Labella, V. P.; Ventrice, C. A., Jr.; Sandin, A.; Dougherty, D. B.; Rowe, J. E.; Dimitrakopoulos, C.; Grill, A.; Sung, C. Y.; Chen, S.; Munson, A.; Magnuson, C. W.; Ruoff, R. S.

    2012-02-01

    The electronic structure of graphene depends on the number of graphene layers and the stacking sequence between the layers. Therefore, it is important to have a non-destructive technique for analyzing the overlayer coverage of graphene directly on the growth substrate. We have developed a technique using angle-resolved XPS to determine the average graphene thickness directly on metal foil substrates and SiC substrates. Since monolayer graphene films can be grown on Cu substrates, these samples are used as a standard reference for a monolayer of graphene. HOPG is used as a standard reference for bulk graphite. The electron mean free path of the C-1s photoelectron can be determined by analyzing the areas under the C-1s peaks of monolayer graphene/Cu and bulk graphite. With the electron mean free path, the graphene coverage of a film of arbitrary thickness can be determined by analyzing the area under the C-1s of that sample. Analysis of graphene coverages for graphene films grown on Cu-Ni substrates and of the thickness of both the graphene overlayer and intermediate buffer layer on SiC will be presented.

  5. Thermodynamic properties and equations of state for Ag, Al, Au, Cu and MgO using a lattice vibrational method

    NASA Astrophysics Data System (ADS)

    Jacobs, M.; Schmid-Fetzer, R.

    2012-04-01

    A prerequisite for the determination of pressure in static high pressure measurements, such as in diamond anvil cells is the availability of accurate equations of state for reference materials. These materials serve as luminescence gauges or as X-ray gauges and equations of state for these materials serve as secondary pressure scales. Recently, successful progress has been made in the development of consistency between static, dynamic shock-wave and ultrasonic measurements of equations of state (e.g. Dewaele et al. Phys. Rev. B70, 094112, 2004, Dorogokupets and Oganov, Doklady Earth Sciences, 410, 1091-1095, 2006, Holzapfel, High Pressure Research 30, 372-394, 2010) allowing testing models to arrive at consistent thermodynamic descriptions for X-ray gauges. Apart from applications of metallic elements in high-pressure work, thermodynamic properties of metallic elements are also of mandatory interest in the field of metallurgy for studying phase equilibria of alloys, kinetics of phase transformation and diffusion related problems, requiring accurate thermodynamic properties in the low pressure regime. Our aim is to develop a thermodynamic data base for metallic alloy systems containing Ag, Al, Au, Cu, Fe, Ni, Pt, from which volume properties in P-T space can be predicted when it is coupled to vibrational models. This mandates the description of metallic elements as a first step aiming not only at consistency in the pressure scales for the elements, but also at accurate representations of thermodynamic properties in the low pressure regime commonly addressed in metallurgical applications. In previous works (e.g. Jacobs and de Jong, Geochim. Cosmochim. Acta, 71, 3630-3655, 2007, Jacobs and van den Berg, Phys. Earth Planet. Inter., 186, 36-48, 2011) it was demonstrated that a lattice vibrational framework based on Kieffer's model for the vibrational density of states, is suitable to construct a thermodynamic database for Earth mantle materials. Such a database aims at, when coupled to a thermodynamic computation program, the calculation and prediction of phase equilibria and thermo-physical properties of phase equilibrium assemblages in pressure-temperature-composition space. In Jacobs and van den Berg (2011) the vibrational method, together with a thermodynamic data base, was successfully applied to mantle convection of materials in the Earth. These works demonstrate that the vibrational method has the advantages of (1) computational speed, (2) coupling or making comparisons with ab initio methods and (3) making reliable extrapolations to extreme conditions. We present results of thermodynamic analyses, using lattice vibrational methods, of Ag, Al, Au, Cu and MgO covering the pressure and temperature regime of the Earth's interior. We show results on consistency of the pressure scales for these materials using different equations of state, under the constraint that thermodynamic properties in the low-pressure regime are accurately represented.

  6. Structural and magnetic properties of a new and ordered quaternary alloy MnNiCuSb (SG: F 4 bar 3m)

    NASA Astrophysics Data System (ADS)

    Haque, Zeba; Thakur, Gohil S.; Ghara, Somnath; Gupta, L. C.; Sundaresan, A.; Ganguli, A. K.

    2016-01-01

    We have synthesized a new crystallographically ordered quaternary Heusler alloy, MnNiCuSb. The crystal structure of the alloy has been determined by Rietveld refinement of the powder X-ray diffraction data. This alloy crystallizes in the LiMgPdSb type structure with F 4 bar 3m space group. MnNiCuSb is a ferromagnet with a high TC~690 K and magnetic moment of 3.85 ?B/f.u. Besides this we have also studied two other off-stoichiometric compositions; one Cu rich and the other Ni rich (MnNi0.9Cu1.1Sb and MnNi1.1Cu0.9Sb) which are also ferromagnets. It must be stressed that MnNiCuSb is one of the very few known, non-Fe containing quaternary Heusler alloys with 1:1:1:1 composition.

  7. Fano effect in the angle-integrated valence band photoemission of the noble metals Cu, Ag, and Au

    SciTech Connect

    De Nadaie, C.; Brookes, N.B.; Minar, J.; Ebert, H.; Ghiringhelli, G.; Tagliaferri, A.

    2004-10-01

    Results of a combined experimental and theoretical investigation on the Fano-effect in the angle-integrated valence band photoemission of the noble metals are presented. In line with the fact that the Fano-effect is caused by the spin-orbit-coupling, the observed spin polarization of the photocurrent was found to be the more pronounced the higher the atomic number of the element investigated. The ratio of the normalized spin difference curves, however, agreed only for Cu and Ag with the ratio of the corresponding spin-orbit coupling strength parameters. The deviation from this expected behavior in the case of Au could be explained by the properties of individual d-p- and d-f-contributions to the total spin difference curves, that were found to be quite different for Au compared to Cu and Ag.

  8. Solvent effects on geometrical structures and electronic properties of metal Au, Ag, and Cu nanoparticles of different sizes.

    PubMed

    Hou, Mingqiang; Mei, Qingqing; Han, Buxing

    2015-07-01

    Study of the geometrical structures and electronic properties of metal nanoparticles is a very interesting topic. In this work we studied the effects of cyclohexane, benzene, ethanol, and water on bond lengths, Mulliken charge distributions, binding energy (BE), energy gap between highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) (?(HL)), ionization potential (IP) and electron affinity (EA) of Au20, Ag20, Cu20, Au38, Ag38, and Cu38 nanoparticles by using density functional theory (DFT). The results indicated that the properties of the solvents influence the geometrical structures and electronic properties of the metallic nanoparticles considerably, and the solvent effect depends on the properties of the solvents, the size of the metal particles, and the category of the metals. Generally, the properties of smaller particles are more sensitive to the change of the solvents, and the polar solvents have larger effect on the properties. PMID:25648110

  9. Dual atmosphere tolerance of Ag-CuO based air braze

    SciTech Connect

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

    2007-11-01

    Recently, a new braze filler metal based on the silver-copper oxide system was developed for use in sealing high-temperature, solid-state electrochemical devices such as solid oxide fuel cells. One of the concerns regarding the viability of this joining technique is the long-term stability of silver-based alloys under a high-temperature, dual oxidizing/reducing gas environment. This paper reports on an initial series of exposure experiments that were conducted to characterize the effects of (1) filler metal composition, (2) brazing temperature, and (3) exposure time on the microstructural stability of Ag-CuO brazed Al2O3/Al2O3 joints under a prototypic operating environment for an intermediate temperature solid oxide fuel cell stack. In general joints exposed simultaneously to air on one side and hydrogen on the other for short periods of time at 800C (100 hrs) showed no signs of degradation with respect to hermeticity or joint microstructure. Samples exposed for longer periods of time (1000 hrs) displayed some internal porosity, which extends approximately halfway across the joint and is not interconnected. Little effect of the filler metals composition on its tolerance to dual atmosphere exposure was observed. However brazing temperature was found to have a measurable effect. Higher brazing temperature leads to a more extensive formation of an interfacial reaction phase, copper aluminate, which tends to tie up some of the free CuO in the filler metal and minimize the formation of porosity in the air brazed joints during long-term, dual-atmosphere exposure. The effect is due to the greater chemical stability of the copper aluminate relative to copper oxide.

  10. Hydrogen production via supercritical water gasification of bagasse using Ni-Cu/?-Al2O3 nano-catalysts.

    PubMed

    Mehrani, Reza; Barati, Mohammad; Tavasoli, Ahmad; Karimi, Ali

    2015-01-01

    Biomass gasification in supercritical water media is a promising method for the production of hydrogen. In this research, Cu-promoted Ni/?-Al2O3 nano-catalysts were prepared with 2.5-30?wt% Ni and 0.6-7.5?wt% Cu loadings via the microemulsion method. Nano-catalysts were characterized by inductively coupled plasma (ICP), Brunauer Emmett Teller (BET) technique, X-Ray Diffraction (XRD), H2 chemisorption and Transmission Electron Microscopy (TEM) technique, as well as Carbon-Hydrogen-Nitrogen-Sulfur (CHNS) analysis was carried out for elemental analysis of bagasse. Nano-catalysts were assessed in a batch micro-reactor under 400C and 240?bar. The microemulsion method decreased the catalyst average particle size and increased the percentage dispersion and reduction of the catalysts. The total gas yield increased with an increase in Ni and Cu loadings up to 20?wt% Ni and 5?wt% Cu and then started to decrease. Using the microemulsion technique for the preparation of Ni-Cu/?-Al2O3 nano-catalyst, increased the hydrogen yield to 11.76 (mmol of H2/g of bagasse), CO yield to 2.67 (mmol of CO/g of bagasse) and light gaseous hydrocarbons to 0.6 (mmol of light gaseous hydrocarbons/g of bagasse). Promotion of Ni/?-Al2O3 with copper increased the mole fraction of hydrogen in the final gasification products to 58.1?mol%. PMID:25387488

  11. Effects of Current Stressing on Formation and Evolution of Kirkendall Voids at Sn-3.5Ag/Cu Interface

    NASA Astrophysics Data System (ADS)

    Yu, C.; Yang, Y.; Lu, H.; Chen, J. M.

    2010-08-01

    Kirkendall voids (KVs) are known to be formed at the Cu/Cu3Sn interface, which can remarkably weaken solder joints. In this paper, the formation and evolution processes of KVs at Sn-3.5Ag/Cu joints were systematically investigated under isothermal aging and current stressing. It was found that the processes develop faster when joints are subjected to current stressing as opposed to thermal aging. This can be illuminated by the high KV densities caused by current stressing at both cathode and anode Cu/Cu3Sn interfaces. Moreover, KVs formed under current stressing showed some polarity characteristics, namely that higher KV density was observed on the anode side compared with the cathode side. The interfacial reaction generated at the Cu3Sn/Cu6Sn5 interface, which was partly affected by current stressing, contributed to this polarity effect. As the holding time was prolonged, microvoids coalesced into larger porosities and microcracks. These defects will greatly threaten the reliability of the interface.

  12. Constitutive Behavior of Mixed Sn-Pb/Sn-3.0Ag-0.5Cu Solder Alloys

    NASA Astrophysics Data System (ADS)

    Tucker, J. P.; Chan, D. K.; Subbarayan, G.; Handwerker, C. A.

    2012-03-01

    During the transition from Pb-containing solders to Pb-free solders, joints composed of a mixture of Sn-Pb and Sn-Ag-Cu often result from either mixed assemblies or rework. Comprehensive characterization of the mechanical behavior of these mixed solder alloys resulting in a deformationally complete constitutive description is necessary to predict failure of mixed alloy solder joints. Three alloys with 1 wt.%, 5 wt.%, and 20 wt.% Pb were selected so as to represent reasonable ranges of Pb contamination expected from different 63Sn-37Pb components mixed with Sn-3.0Ag-0.5Cu. Creep and displacement-controlled tests were performed on specially designed assemblies at temperatures of 25C, 75C, and 125C using a double lap shear test setup that ensures a nearly homogeneous state of plastic strain at the joint interface. The observed changes in creep and tensile behavior with Pb additions were related to phase equilibria and microstructure differences observed through differential scanning calorimetric and scanning electron microscopic cross-sectional analysis. As Pb content increased, the steady-state creep strain rates increased, and primary creep decreased. Even 1 wt.% Pb addition was sufficient to induce substantially large creep strains relative to the Sn-3.0Ag-0.5Cu alloy. We describe rate-dependent constitutive models for Pb-contaminated Sn-Ag-Cu solder alloys, ranging from the traditional time-hardening creep model to the viscoplastic Anand model. We illustrate the utility of these constitutive models by examining the inelastic response of a chip-scale package (CSP) under thermomechanical loading through finite-element analysis. The models predict that, as Pb content increases, total inelastic dissipation decreases.

  13. Measurement of Cu K-shell and Ag L-shell ionization cross sections by low-energy positron impact.

    PubMed

    Nagashima, Yasuyuki; Saito, Fuminori; Itoh, Yoshiko; Goto, Akira; Hyodo, Toshio

    2004-06-01

    Inner shell ionization cross sections by low-energy positron impact have been measured. Development of an x-ray detector with thin Si(Li) crystals has enabled the first measurements of the absolute cross sections for the positron impacts in the energy range below 30 keV. Threshold behavior of the measured cross sections for the Cu K shell and Ag L shell are compared with the theoretical results of Gryzinski and Kowalski [Phys. Lett. A 183, 196 (1993)

  14. Growth of periodic nano-layers of nano-crystals of Au, Ag, Cu by ion beam

    NASA Technical Reports Server (NTRS)

    Smith, Cydale C.; Zheng, B.; Muntele, C. I.; Muntele, I. C.; Ila, D.

    2005-01-01

    Multilayered thin films of SiO2/AU+ SiO2/, SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/, were grown by deposition. We have previously shown that MeV ion Bombardment of multi-nano-layers of SiO2/AU+ SiO2/ produces Au nanocrystals in the AU+ SiO2 layers. An increased number of nano-layers followed by MeV ion bombardment produces a wide optical absorption band, of which its FWHM depends on the number of nano-layers of SiO2/AU+ SiO2/. We have successfully repeated this process for nano-layers of SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/. In this work we used 5 MeV Si as the post deposition bombardment ion and monitored the location as well as the optical absorption's FWHM for each layered structure using Optical Absorption Photospectrometry. The concentration and location of the metal nano-crystals were measured by Rutherford Backscattering Spectrometry. We will report on the results obtained for nano-layered structures produced by post deposition bombardment of SiO2/AU+ SiO2/, SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/ layered systems as well as the results obtained from a system containing a periodic combination of SiO2/AU+ SiO2/, SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/.

  15. ?-Decay half-lives of 76,77Co, 79,80Ni, and 81Cu: experimental indication of a doubly magic 78Ni.

    PubMed

    Xu, Z Y; Nishimura, S; Lorusso, G; Browne, F; Doornenbal, P; Gey, G; Jung, H-S; Li, Z; Niikura, M; Sderstrm, P-A; Sumikama, T; Taprogge, J; Vajta, Zs; Watanabe, H; Wu, J; Yagi, A; Yoshinaga, K; Baba, H; Franchoo, S; Isobe, T; John, P R; Kojouharov, I; Kubono, S; Kurz, N; Matea, I; Matsui, K; Mengoni, D; Morfouace, P; Napoli, D R; Naqvi, F; Nishibata, H; Odahara, A; Sahin, E; Sakurai, H; Schaffner, H; Stefan, I G; Suzuki, D; Taniuchi, R; Werner, V

    2014-07-18

    The half-lives of 20 neutron-rich nuclei with Z=27-30 have been measured at the RIBF, including five new half-lives of (76)Co(21.7(-4.9)(+6.5) ms), (77)Co(13.0(-4.3)(+7.2) ms), (79)Ni(43.0(-7.5)(+8.6) ms), (80)Ni(23.9(-17.2)(+26.0) ms), and (81)Cu(73.2 6.8 ms). In addition, the half-lives of (73-75)Co, (74-78)Ni, (78-80)Cu, and (80-82)Zn were determined with higher precision than previous works. Based on these new results, a systematic study of the ?-decay half-lives has been carried out, which suggests a sizable magicity for both the proton number Z = 28 and the neutron number N=50 in (78)Ni. PMID:25083639

  16. THE ELECTRONIC STRUCTURE OF AG/CU(100) SURFACE ALLOYS STUDIES BY AUGER-PHOTOELECTRON COINCIDENCE SPECTROSCOPY.

    SciTech Connect

    ARENA,D.A.; BARTYNSKI,R.A.; HULBERT,S.L.

    2001-10-08

    We have measured the Ag and Pd M{sub 5}VV Auger spectrum in coincidence with Ag and Pd 4d{sub 5/2} photoelectrons for the Ag/Cu(100) and Pd/Cu(100) systems, respectively, as a function of admetal coverage. These systems form surface alloys (i.e. random substitutional alloys in the first atomic layer) for impurity concentrations in the 0.1 monolayer range. For these systems, the centroid of the impurity 4d levels is expected to shift away from the Fermi level by {approx}1 eV [Ruban et al., Journal of Molecular Catalysis. A 115 (1997) 421], an effect that should be easily seen in coincidence core-valence-valence Auger spectra. We find that the impurity Auger spectra of both systems shift in a manner that is consistent with d-band moving away from EF. However, the shift for Pd is considerably smaller than expected, and a shift almost absent for Ag. The disagreement between theory and experiment is most likely caused by the neglect of lattice relaxations in the calculations.

  17. Grain boundary junctions with Ag-doped YBa 2Cu 3O 7-x epitaxial thin films

    NASA Astrophysics Data System (ADS)

    Bolanos, G.; den Ouden, G.; Chacn, M.; Lopera, W.; Gmez, M. E.; Pulzara, A.; Heiras, J.; Prieto, P.

    1997-08-01

    Using a dc sputtering method at high oxygen pressures we have deposited epitaxial Ag-doped YBa2Cu3O7-x thin films on SrTiO3 bicrystals with missorientation angle of 36.8. A 15 % Ag-doped YBa2Cu3O7-x sintered target was used to sputter the films. Critical current of 4-5 106 A/cm2 at 77 K were measured in doped films. When compared with 1 106 A/cm2 for undoped films, indicated an improvement of the superconducting properties by Ag doping. 200-300 nm thick Ag-doped films were patterned across the bicrystal line to form 5-20 ?m-wide junctions. Current-voltage characteristics of the grain boundary junctions at temperatures from 10 K to TC showed a resistively shunted junction (RSJ) behavior with ICRN values of 160-170 ?V at 77 K which are higher than the measured values for undoped junctions.

  18. Wet chemical synthesis, structural and spectroscopic studies of CuSe-Ag hierarchical sphere and drum-like microporous structure.

    PubMed

    Kumar, Pushpendra; Singh, Jai; Pandey, Mukesh Kumar

    2013-06-01

    Nanostructural self-assembly has become field of intense research activities from both fundamental and technological standpoints to understanding the mechanism of driving forces and finding artificial methods of assembling them into continuous structures without any obstructions. Various exciting and refined examples of nanostructured self-assembly are well documented. In the present manuscript the crystallization process and optical properties of self assembled CuSe-Ag hierarchical microporous sphere and drum-like structures, synthesized by wet chemical method has been investigated. Thus formed structures are accumulated by numerous polyhedral rod-like subunits, and each unit seems to be an incomplete structure of a randomly grown rod. Phase analysis, purity and morphology of the product have been well studied by X-ray diffraction (XRD), photo-luminescent spectroscopy (PL), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). Due to their microporous structures CuSe-Ag could be potential building blocks to construct functional devices like sensing and several other applications. A possible reaction mechanism for the formation of CuSe-Ag has also been proposed. PMID:23557774

  19. Ag{sub 2}CuMnO{sub 4}: A new silver copper oxide with delafossite structure

    SciTech Connect

    Munoz-Rojas, David; Subias, Gloria; Fraxedas, Jordi; Martinez, Benjamin; Casas-Cabanas, Montse; Canales-Vazquez, Jesus; Gonzalez-Calbet, Jose; Garcia-Gonzalez, Ester; Walton, Richard I.; Casan-Pastor, Nieves . E-mail: nieves@icmab.es

    2006-12-15

    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.

  20. The structures expected in a simple ternary eutectic system: Part II. The Al-Ag-Cu ternary system

    NASA Astrophysics Data System (ADS)

    McCartney, D. G.; Jordan, R. M.; Hunt, J. D.

    1980-08-01

    Ternary alloys of various compositions from the aluminum rich corner of the Al-Ag-Cu system were directionally solidified at several different growth rates ranging from 6.4 10-1 mmS-1 to 5.6 10-3 mm s-1. The region of two phase coupled growth between ?-Al and CuAl2 was determined at a growth rate of 6.4 10-1 mm s-1. The composition range over which a fully ternary eutectic structure formed was investigated for several different growth rates. The results are found to be consistent with the predictions of the competitive growth model set out in Part I,1 and it would seem that the ternary eutectic composition of the published phase diagram may be incorrect. Scanning electron microscopy, using the backscattered electron signal, was used, together with optical microscopy, to study the microstructures formed. The ternary eutectic between ?-Al, Ag2Al, and CuAl2 was found to be semiregular, and the unusual morphology of the two phase dendrites between ?-Al and Ag2Al is explained.

  1. Theoretical study of cytosine-Al, cytosine-Cu and cytosine-Ag (neutral, anionic and cationic).

    PubMed

    Vazquez, Marco-Vinicio; Martnez, Ana

    2008-02-01

    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

  2. Microstructural Evolution of the Interface Between Pure Titanium and Low Melting Point Zr-Ti-Ni(Cu) Filler Metals

    NASA Astrophysics Data System (ADS)

    Lee, Dongmyoung; Sun, Juhyun; Kang, Donghan; Shin, Seungyoung; Hong, Juhwa

    2014-12-01

    Low melting point Zr-based filler metals with melting point depressants (MPDs) such as Cu and Ni elements are used for titanium brazing. However, the phase transition of the filler metals in the titanium joint needs to be explained, since the main element of Zr in the filler metals differs from that of the parent titanium alloys. In addition, since the MPDs easily form brittle intermetallics, that deteriorate joint properties, the phase evolution they cause needs to be studied. Zr-based filler metals having Cu content from 0 to 12 at. pct and Ni content from 12 to 24 at. pct with a melting temperature range of 1062 K to 1082 K (789 C to 809 C) were wetting-tested on a titanium plate to investigate the phase transformation and evolution at the interface between the titanium plate and the filler metals. In the interface, the alloys system with Zr, Zr2Ni, and (Ti,Zr)2Ni phases was easily changed to a Ti-based alloy system with Ti, Ti2Ni, and (Ti,Zr)2Ni phases, by the local melting of parent titanium. The dissolution depths of the parent metal were increased with increasing Ni content in the filler metals because Ni has a faster diffusion rate than Cu. Instead, slow diffusion of Cu into titanium substrate leads to the accumulation of Cu at the molten zone of the interface, which could form undesirable Ti x Cu y intermetallics. This study confirmed that Zr-based filler metals are compatible with the parent titanium metal with the minimum content of MPDs.

  3. Effect of Graphene Nanoplatelets on Wetting, Microstructure, and Tensile Characteristics of Sn-3.0Ag-0.5Cu (SAC) Alloy

    NASA Astrophysics Data System (ADS)

    Sharma, Ashutosh; Sohn, Heung-Rak; Jung, Jae Pil

    2015-10-01

    The effect of graphene nanoplatelets (GNPs) on the wettability, microstructure, and tensile properties of Sn-3.0Ag-0.5Cu (SAC 305) was studied using melting and casting route. The microstructure of the bulk solder is observed with a scanning electron microscope and transmission electron microscope, and the intermetallic compound (IMC) phases are identified by electron probe micro-analyzer. The solderability of the samples is assessed by spreading and wetting tests on a Cu substrate. The experimental results indicate that an addition of 0.05 wt pct GNPs in Sn-3Ag-0.5Cu solder improves the spreading and wettability significantly compared to monolithic SAC. It is also revealed that the thickness of the Ag3Sn IMCs is reduced as compared to the monolithic SAC alloy. Tensile results show that the composite solder exhibits the 13.9 pct elongation and 17 pct increase in the ultimate tensile strength when 0.05 wt pct GNPs in Sn-3Ag-0.5Cu alloy are added. This may be due to the refinement of the IMCs in composite solders compared to the same in Sn-3Ag-0.5Cu alloy brought about by the uniform dispersion of graphene nanoplatelets. It is suggested in this study that the amount of GNPs in Sn-3Ag-0.5Cu alloy should not exceed 0.05 wt pct as it may degrade the desired properties due to the agglomeration of GNPs.

  4. In-Situ Generation of Oxide Nanowire Arrays from AgCuZn Alloy Sulfide with Enhanced Electrochemical Oxygen-Evolving Performance.

    PubMed

    Xie, Minghao; Ai, Shiqi; Yang, Jian; Yang, Yudi; Chen, Yihan; Jin, Yong

    2015-08-12

    In this study, AgCuZn sulfide is fabricated on the surface of AgCuZn alloys by hydrothermal sulfuration. This ternary metal sulfide is equipped with enhanced activity toward oxygen evolution reaction (OER) in an alkaline electrolyte. Through comparison of the alloys with diverse compositions, we find out the best electrochemical property of a particular alloy sulfide forming on a AgCuZn substrate (Ag:Cu:Zn=43:49:8). The alloy sulfide exhibits an onset overpotential (?) of 0.27 V with a Tafel slope of 952 mV dec(-1) and a current density of 130 mA cm(-2) at ? of 0.57 V. Moreover, the obtained AgCuZn sulfide displays excellent stability, where the current density can increase to 130% of the initial value after a water electrolysis test for 100,000 s (27.7 h). Through investigating the electrode before and after the electrocatalysis, we find a remarkable activated process during which self-supported copper-silver oxide nanowire (CuO-Ag2O NW) arrays in situ form on the surface of the electrode. This work provides a feasible strategy for synthesis of high performance nonprecious metal electrocatalysts for water splitting. PMID:26181359

  5. Effect of Board Thickness on Sn-Ag-Cu Joint Interconnect Mechanical Shock Performance

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Kyu; Xie, Weidong

    2014-12-01

    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.

  6. Development of Sn-Ag-Cu-X Solders for Electronic Assembly by Micro-Alloying with Al

    SciTech Connect

    Boesenberg, Adam; Anderson, Iver; Harringa, Joel

    2012-03-10

    Of Pb-free solder choices, an array of solder alloys based on the Sn-Ag-Cu (SAC) ternary eutectic (T eut = 217C) 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.

  7. Three-dimensional rigid multiphase networks providing high-temperature strength to cast AlSi10Cu5Ni1-2 piston alloys

    PubMed Central

    Asghar, Z.; Requena, G.; Boller, E.

    2011-01-01

    The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of ?-Al matrix and a rigid long-range 3-D network of Al7Cu4Ni, Al4Cu2Mg8Si7, Al2Cu, Al15Si2(FeMn)3 and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ?15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si. PMID:21977004

  8. Three-dimensional rigid multiphase networks providing high-temperature strength to cast AlSi10Cu5Ni1-2 piston alloys.

    PubMed

    Asghar, Z; Requena, G; Boller, E

    2011-09-01

    The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of ?-Al matrix and a rigid long-range 3-D network of Al(7)Cu(4)Ni, Al(4)Cu(2)Mg(8)Si(7), Al(2)Cu, Al(15)Si(2)(FeMn)(3) and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ?15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si. PMID:21977004

  9. Microalloying of Sc, Ni, and Ce in an advanced Al-Zn-Mg-Cu alloy

    SciTech Connect

    Wu, Y.L.; Li, C.; Froes, F.H.; Alvarez, A.

    1999-04-01

    Using transmission electron microscopy (TEM), scanning electron microscopy, X-ray diffraction (XRD), and optical microscopy, the effects of microalloying elements of Sc, Ni, and Ce on the microstructure of a new super-high-strength ingot metallurgy (IM)/Al-Zn-Mg-Cu alloy (C912) have been correlated with mechanical properties and stress corrosion cracking (SCC) behavior. Using microalloying with Sc, Ni, and Ce, the C912 alloy can exhibit very high strength and good SCC resistance. Compared to the baseline C912 alloy, Sc refines the microstructure and retards recrystallization, Ni promotes the development of matrix precipitates, which enhance the strength and SCC resistance, and Ce has little effect on alloy strengthening in the three microalloying additions studied. The Sc-containing alloy (C912S) is the most attractive and even exhibits higher strength (ultimate tensile strength (UTS) greater than 660 MPa) than the new Alcoa aluminum alloy 7055 and the Russian alloy B96f, which have the highest strengths of the commercial IM/Al-Zn-Mg-Cu alloys.

  10. Gold and silver in PGE-Cu-Ni and PGE ores of the Noril'sk deposits, Russia

    NASA Astrophysics Data System (ADS)

    Sluzhenikin, Sergey F.; Mokhov, Andrey V.

    2015-04-01

    Gold and silver contents in Noril'sk ore are controlled by the amount of sulphides and bulk Cu grade. Relative concentrations, re-calculated to 100 % sulphide, depend on type of ore: they are higher for disseminated ore than for massive ore and are the highest for low-sulphide platinum ore. Gold occurs mainly as high-fineness Au-Ag alloy in pyrrhotite-rich ore, whereas silver enters chalcopyrite mainly as solid solution. Increase in Cu grade correlates with an increase in the concentration of silver in chalcopyrite. Gold and silver form discrete minerals such as Au-Cu alloys, Au-Ag alloys, tellurides, sulphides, selenides, sulphobismuthides, Ag and Ag-Pd chlorides in Cu-rich ores; they also enter the structures of complex platinum-group minerals. The Au-Ag mineralisation is related to the post-magmatic hydrothermal stage under temperature conditions of 350-50 C. Silver entered crystallizing chalcopyrite in solid solution in the late-magmatic stage, while all of the gold and the remainder of the silver and some platinum-group elements were transported predominantly as chloride and hydrosulphide complexes in hydrothermal fluids.

  11. Epitaxial (111) films of Cu, Ni, and Cu{sub x}Ni{sub y} on {alpha}-Al{sub 2}O{sub 3} (0001) for graphene growth by chemical vapor deposition

    SciTech Connect

    Miller, David L.; Keller, Mark W.; Shaw, Justin M.; Chiaramonti, Ann N.; Keller, Robert R.

    2012-09-15

    Films of (111)-textured Cu, Ni, and Cu{sub x}Ni{sub y} were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of {alpha}-Al{sub 2}O{sub 3}(0001) at temperatures of 250 Degree-Sign C to 650 Degree-Sign C. The films were then annealed at 1000 Degree-Sign C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by 60 Degree-Sign . The in-plane epitaxial relationship for all films was [110]{sub metal}||[1010]{sub Al{sub 2O{sub 3}}}. Reactive sputtering of Al in O{sub 2} before metal deposition resulted in a single in-plane orientation over 97% of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al{sub 2}O{sub 3} interface, confirmed the epitaxial relationship, and showed that formation of the 60 Degree-Sign twin grains was associated with features on the Al{sub 2}O{sub 3} surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and Cu{sub x}Ni{sub y} films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO{sub 2} films, but still showed thickness variations on a much smaller length scale than the distance between grains.

  12. Comparisons of grain refinement and recalescence behavior during the rapid solidification of undercooled Cu-Co and Cu-Ni alloys

    NASA Astrophysics Data System (ADS)

    Yang, W.; Xu, Z. F.; Li, W. J.; Cai, C. C.; Li, S.; Liu, F.; Yang, G. C.

    2011-10-01

    Applying the melt-fluxing method, rapid solidifications of undercooled Cu 50Co 50 immiscible and Cu 70Ni 30 solid solution alloys were performed to investigate the grain refinement regularity at moderate undercooling. Due to the essential distinction of physical properties between these alloys, grain refinement phenomenon was detected in Cu 50Co 50 alloy with a tendency of liquid separation, while dendrite structure appears for Cu 70Ni 30 alloy. The association of microstructure morphology to non-equilibrium solidification process was constructed with the description of recalescence degree as a function of undercooling. Quantitative thermodynamic calculation for the undercooled liquid of the researched systems was carried out to elucidate the influence of liquid separation on the variation of Gibbs free energy for the subsequent rapid solidification, which gives a better understanding of the as-observed experimental results.

  13. Determining parameters of the local atomic structure of Cu-Ni and Cu-Mn alloys by the method of extended electron-loss fine structure spectroscopy

    NASA Astrophysics Data System (ADS)

    Bakieva, O. R.; Nemtsova, O. M.; Gai, D. E.

    2015-01-01

    In this work, we consider the possibility of analyzing local atomic structure based on strongly overlapping experimental extended electron-energy-loss fine structure (EELFS) spectra of two different chemical elements. M 2,3 EELFS spectra have been obtained from the surface of Cu x Ni1 - x and Cu x Mn1 - x ( x = 0.5) alloys. The method of determining the parameters of the local atomic structure (coordination numbers, lengths of the chemical bonds, and the parameters of their dispersion) of the nearest atomic surroundings in ultrathin (1-5 nm) surface layers of two-component alloys of 3 d metals has been suggested based on the overlapping extended fine structures of the electron-energy-loss spectra. The method was tested on experimental M 2,3 EELFS spectra of the surface of testing alloys Cu50Ni50 and Cu50Mn50.

  14. Effect of a prior stretch on the aging response of an Al-Cu-Li-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Kumar, K. S.; Brown, S. A.; Pickens, Joseph R.

    1991-01-01

    Recently, a family of Al-Cu-Li alloys containing minor amounts of Ag, Mg, and Zr and having desirable combinations of strength and toughness were developed. The Weldalite (trademark) alloys exhibit a unique characteristic in that with or without a prior stretch, they obtain significant strength-ductility combinations upon natural and artificial aging. The ultra-high strength (approximately 690 MPa yield strength) in the peak-aged tempers (T6 and T8) were primarily attributed to the extremely fine T(sub 1) (Al2CuLi) or T(sub 1)-type precipitates that occur in these alloys during artificial aging, whereas the significant natural aging response observed is attributed to strengthening from delta prime (Al3Li) and GP zones. In recent work, the aging behavior of an Al-Cu-Li-Ag-Mg alloy without a prior stretch was followed microstructurally from the T4 to the T6 condition. Commercial extrusions, rolled plates, and sheets of Al-Cu-Li alloys are typically subjected to a stretching operation before artificial aging to straighten the extrusions and, more importantly, introduce dislocations to simulate precipitation of strengthening phases such as T(sub 1) by providing relatively low-energy nucleation sites. The goals of this study are to examine the microstructure that evolves during aging of an alloy that was stretch after solution treatment and to compare the observations with those for the unstretched alloy.

  15. Synthesis of {beta}-phase Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions nanocrystals

    SciTech Connect

    Liu, Xianli; Jilin Weather Modification Office, Changchun 130062 ; Zhang, Jinghong; Jilin Weather Modification Office, Changchun 130062 ; Zhang, Guilan; Jiang, Zhonghao; Jin, Dezhen

    2011-06-15

    Research highlights: {yields} Wet-chemical-chelating reaction processing has been used to synthesized A series of single {beta}-phase nano-Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions powders. {yields} Citric acid as complexing agent takes part in the process of chemical reaction and the chemical reactions can be described in this paper. {yields} The lattice parameters have been ascertained by the results of XRD. {yields} Crystalline sizes, which decrease with copper iodide concentration increasing, have been demonstrated by XRD and TEM. -- Abstract: A series of single {beta}-phase nano-Ag{sub 1-x}Cu{sub x}I (x = 0-0.5) solid solutions powders were synthesized by wet-chemical-chelating reaction processing and citric acid used as complexing agent. The Ag{sub 1-x}Cu{sub x}I powders were determined by X-ray diffraction and transmission electron microscopy. It was demonstrated that the crystalline size and lattice parameter of the Ag{sub 1-x}Cu{sub x}I powders decrease with an increase in the amount of CuI substitution. The copper in the lattice of the Ag{sub 1-x}Cu{sub x}I can effectively prevent the crystalline growth of the Ag{sub 1-x}Cu{sub x}I powders and citrate used in the Ag{sub 1-x}Cu{sub x}I powders synthesized process can accelerate single {beta}-phase crystalline structure formation.

  16. Brazing microstructure of Ti-6Al-6V-2Sn with Ti-Zr-Cu-Ni filler metal

    SciTech Connect

    Hsieh, K.C.; Kao, P.W.; Shu, M.F.

    1994-12-31

    Titanium and its alloys have been widely used in the aerospace industry since they have high specific strength and high corrosion resistance. The brazing of titanium is beneficial to join many contact areas simultaneously without severe distortion. The purpose of this study is to investigate the brazing microstructures under different brazing conditions with several Ti-Zr-Cu-Ni filler alloys. In our previous studies, the brazing microstructure of Ti-6Al-4V with Ti-Cu-Ni filler metal have been reported. Since Ti-6Al-6V-2Sn alloy has lower b-transus, the Ti-Cu-Ni filler alloy cannot successfully apply the brazing work. Several Ti-Zr-Cu-Ni alloys were prepared in powder form and pre-alloy form to perform the brazing of Ti-6Al-6V-2Sn at 870{degrees}C. The brazing microstructures are examined under optical metallograph, scanning electron microscopy (SEM), and X-ray analysis. The contents of this report include (1) DTA and phase analysis of Ti-Zr-Cu-Ni filler metals, (2) the brazing microstructure, and (3) the shear test result.

  17. Fe self-diffusion and Cu and Ni diffusion in bulk and grain boundary of Fe: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Shu, Xiaolin; Li, Xiaochun; Yu, Yi; Liu, Yinan; Wu, Tiefeng; Shuo, Yuan; Lu, Guanghong

    2013-07-01

    Segregation of solute elements or impurities to the grain boundary (GB) may be impeding the dislocation movement to cause the embrittlement of materials. The diffusion behaviour of elements in alloy, especially in GB, has a crucial effect on the segregation of impurities. We calculated the migration energy of Fe, Cu and Ni atom in Fe by the molecular dynamics method with the Nudged Elastic Band (NEB) method. The self-diffusion migration energy of Fe is 0.628 eV. The migration energies of Cu and Ni in Fe crystal are 0.592 eV and 0.608 eV, respectively. These results are good agreement with other calculations. The migration energies of Fe atom, Cu and Ni solute diffusion in [0 0 1] and [3 1 0] direction in GB ?5 [3 1 0] and diffusion out GB ?5 [3 1 0] in [1 1 1] direction are calculated. The Cu solute is segregate easier to GB and more difficult diffusion out of GB than the Ni solute. The Fe atom, Cu and Ni solute are very difficult to diffuse in [0 0 1] and [3 1 0] in ?5 [3 1 0] because of their large migration energies, respectively. They can jump out of GB in [1 1 1] and back to GB in other [1 1 1] to diffuse near GB.

  18. Approach to study of Cu, Ni and Zn content in soil for ecotoxicological risk assessment

    NASA Astrophysics Data System (ADS)

    Boluda, R.; Marimon, L.; Gil, C.; Roca-Prez, L.

    2009-04-01

    Current Spanish legislation on contaminated soils defines contaminated soil as "that whose characteristics have been negatively altered by the presence of dangerous human-derived chemical components whose concentration is such that it is an unacceptable risk for human health or the environment and has been expressly declared as such by legal ruling". Regarding heavy metals, the Spanish Autonomous Communities will promote measures to obtain generic reference values to declare a soil to be contaminated. In the Valencian Community, these reference values still do not exist. So if the protection of ecosystems is considered a priority to declare a soil to be contaminated and to assess the level of risk, emergency toxicity tests and seed growth in land plants are resorted to, or tests with aquatic organisms or other experiments with leached soils obtained by standard procedures are carried out. We studied the toxic effects of calcareous contaminated soils by Cu, Ni and Zn on marine bacterium Vibrio fisheri (MicrotoxR test assay) (1) and on barley (Hordeum vulgare L.) in plate (germination index) (2) and pot (UNE 77301) (3) experiments for the purpose of establishing the Cu, Ni and Zn concentrations in soil which may lead to toxicity in order to observe, therefore, whether there is any likelihood of these pollutants coming into contact with any receptor and if adverse effects exist for living beings and the environment. The results showed significant differences among the three types of tests done but, in all cases, the concentrations needed to reflect toxicity effect on organisms were around 20 -70 (Cu and Ni) to 1000 (Zn) times higher than the levels of the control soils. The sensitivity order of the bio-assay was: (1) < (3) < (2). We would like to thank Spanish government-MICINN for partial funding and support (MICINN, project CGL2006-09776).

  19. Influence of an electric field on the spin-reorientation transition in Ni/Cu(100)

    SciTech Connect

    Gerhard, Lukas; Bonell, Frdric; Suzuki, Yoshishige; Wulfhekel, Wulf

    2014-10-13

    Magnetoelectric coupling offers the possibility to change the magnetic state of a material by an applied electric field. Over the last few years, metallic systems have come up as simple prototypes for this interaction. While the previous studies focused on Fe and Co thin films or their alloys, here we demonstrate magnetoelectric coupling in a Ni thin film which is close to a spin-reorientation transition. Our magneto-optic Kerr effect measurements on 10 ML of Ni/Cu(100) show a considerable influence of the applied electric field on the magnetism. This rounds off the range of magnetic metals that exhibit magnetoelectric coupling, and it reveals the possibility of an electric field control of a spin-reorientation transition.

  20. Atomistic Modeling of Quaternary Alloys: Ti and Cu in NiAl

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Mosca, Hugo O.; Wilson, Allen W.; Noebe, Ronald D.; Garces, Jorge E.

    2002-01-01

    The change in site preference in NiAl(Ti,Cu) alloys with concentration is examined experimentally via ALCHEMI and theoretically using the Bozzolo-Ferrante-Smith (BFS) method for alloys. Results for the site occupancy of Ti and Cu additions as a function of concentration are determined experimentally for five alloys. These results are reproduced with large-scale BFS-based Monte Carlo atomistic simulations. The original set of five alloys is extended to 25 concentrations, which are modeled by means of the BFS method for alloys, showing in more detail the compositional range over which major changes in behavior occur. A simple but powerful approach based on the definition of atomic local environments also is introduced to describe energetically the interactions between the various elements and therefore to explain the observed behavior.

  1. Effect of Ni substitution for Cu in the vortex state of (Bi,Pb):2223 superconductor

    SciTech Connect

    Pop, A.V.

    1999-09-10

    The influence of the partial substitution of x = 0.02 Ni for Cu on the magnetoresistivity in the (Bi,Pb):2223 superconductor has been investigated. The resistive transitions were studied under magnetic fields up to 0.7 Tesla by using the dp/dT versus T curves. The Arrhenius plots shows that the dissipation processes are induced by two distinct regimes. In the high temperature regime the activation energy is proportional to lnB and to B{sup {minus}1} in low temperature regime. The main dissipation processes in these regimes are discussed.

  2. Spin pseudogap in Ni-doped SrCuO2

    SciTech Connect

    Simutis, Gediminas; Gvasaliya, S. N.; Mansson, Martin; Chernyshev, Alexander L; Mohan, Ananthanarayanan; Singh, S; Hess, C; Savici, Andrei T; Kolesnikov, Alexander I; Piovano, A; Perring, Toby G; Zaliznyak, Igor; Buchner, B; Zheludev, A

    2013-01-01

    The S = 1/2 spin chain material SrCuO2 doped with 1% S = 1 Ni-impurities is studied by inelastic neutron scattering. At low temperatures, the spectrum shows a pseudogap 8 meV, absent in the parent compound, and not related to any structural phase transition. The pseudogap is shown to be a generic feature of quantum spin chains with dilute defects. A simple model based on this idea quantitatively accounts for the exprimental data measured in the temperature range 2-300 K, and allows to represent the momentum-integrated dynamic structure factor in a universal scaling form.

  3. Influence of pump pulse structure on a transient collisionally pumped Ni -like Ag x-ray laser

    NASA Astrophysics Data System (ADS)

    Janulewicz, K. A.; Nickles, P. V.; King, R. E.; Pert, G. J.

    2004-07-01

    Results of numerical simulations on a Ni -like silver x-ray laser pumped by a single picosecond laser pulse are presented. Since the mechanisms responsible for the significant reduction in the pump energy are not well understood, the results of theoretical simulations with emphasis on the plasma kinetics and dynamics in a Ni -like Ag x-ray laser are presented and referred to the experimental data. Special attention has been paid to the influence of the pump pulse shape and length on the gain and its duration. It was found that a low-level pulse pedestal being an integral part of the leading edge of the pump pulse is very beneficial to the pump energy reduction. The thermal cooling process has been identified as the mechanism strongly contributing to gain termination if a low-energy single-profile laser pulse with the width of a few picoseconds is used in the pump process.

  4. Origin of ultrafast Ag radiotracer diffusion in shear bands of deformed bulk metallic glass Pd40Ni40P20

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.; Bin Yu, Hai

    2013-03-01

    Measurements of Ag radiotracer diffusion in shear bands of deformed bulk metallic glass, Pd40Ni40P20 [Bokeloh et al., Phys. Rev. Lett. 107, 235503 (2011)], have found a colossal enhancement of diffusion coefficient by more than eight orders of magnitude than in undeformed Pd40Ni40P20. Suggestion was made by Bokeloh et al. that enhanced diffusion occurs in high-mobility pathways originating from some excess free volume distribution inside the shear bands. Although plausible, this qualitative suggestion does not allow quantitative calculation of the enhancement. The impasse is avoided by using the coupling model to calculate the maximum of the enhancement of diffusivity possible in high-mobility pathways of the shear bands. Within the range of eight to ten orders of magnitude, the calculated maximum enhancement is capable to account for the experimental observation.

  5. Synthesis and thermal behavior of tin-based alloy (Sn-Ag-Cu) nanoparticles

    NASA Astrophysics Data System (ADS)

    Roshanghias, Ali; Yakymovych, Andriy; Bernardi, Johannes; Ipser, Herbert

    2015-03-01

    The prominent melting point depression of nanoparticles has been the subject of a considerable amount of research. For their promising applications in electronics, tin-based nano-alloys such as near-eutectic Sn-Ag-Cu (SAC) alloys have been synthesized via various techniques. However, due to issues such as particle aggregation and oxidation or introduced impurities, the application of these nano-size particles has been confined or aborted. For instance, thermal investigations by DTA/DSC in a large number of studies revealed exothermic peaks in the range of 240-500 C, i.e. above the melting point of SAC nanoparticles, with different and quite controversial explanations for this unclear phenomenon. This represents a considerable drawback for the application of nanoparticles. Correspondingly, in the current study, the thermal stability of SAC nanoparticles has been investigated via electron microscopy, XRD, FTIR, and DSC/TG analysis. It was found that the nanoparticles consist mainly of a metallic ?-Sn core and an amorphous tin hydroxide shell structure. The SnO crystalline phase formation from this amorphous shell has been associated with the exothermic peaks on the first heating cycle of the nanoparticles, followed by a disproportionation reaction into metallic Sn and SnO2.The results also revealed that the surfactant and reducing agent cannot only affect the size and size distribution of the nanoparticles, they might also alter the ratio between the amorphous shell and the crystalline core in the structure of particles.The prominent melting point depression of nanoparticles has been the subject of a considerable amount of research. For their promising applications in electronics, tin-based nano-alloys such as near-eutectic Sn-Ag-Cu (SAC) alloys have been synthesized via various techniques. However, due to issues such as particle aggregation and oxidation or introduced impurities, the application of these nano-size particles has been confined or aborted. For instance, thermal investigations by DTA/DSC in a large number of studies revealed exothermic peaks in the range of 240-500 C, i.e. above the melting point of SAC nanoparticles, with different and quite controversial explanations for this unclear phenomenon. This represents a considerable drawback for the application of nanoparticles. Correspondingly, in the current study, the thermal stability of SAC nanoparticles has been investigated via electron microscopy, XRD, FTIR, and DSC/TG analysis. It was found that the nanoparticles consist mainly of a metallic ?-Sn core and an amorphous tin hydroxide shell structure. The SnO crystalline phase formation from this amorphous shell has been associated with the exothermic peaks on the first heating cycle of the nanoparticles, followed by a disproportionation reaction into metallic Sn and SnO2.The results also revealed that the surfactant and reducing agent cannot only affect the size and size distribution of the nanoparticles, they might also alter the ratio between the amorphous shell and the crystalline core in the structure of particles. Dedicated to Prof. Brigitte Weiss.

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

    E-print Network

    Garmestani, Hamid

    ; Fe; Pb; Ni; NiO, Ni2O3; Sn; SnO2; Ti; Zn Hydrofluoric Acid (HF): GaAs; Ni; SiO2; Ti Nitric Acid (HNO3 : hydrofluoric acid (49%, aq) HNO3 : nitric acid (70%, aq) H2SO4 : sulfuric acid (96%, aq) H3PO4 : phosphoricAcetic Acid (H3COOH): GaAs; Pb; Ti Hydrochloric Acid (HCl): Al; Cr; Cu; Fe2O3; Ga; GaAs; GaN; In

  7. Technology, science, and environtmental impact of a novel Cu-Ag core-shell solderless interconnect system

    NASA Astrophysics Data System (ADS)

    Kammer, Milea Joy

    Tin-based solder is ubiquitous in microelectronics manufacturing and plays a critical role in electronic packaging and attachment. While manufacturers of consumer electronics have made the transition to the use of lead-free solder, there are still a variety of reliability issues associated with these lead-free alternatives, particularly for high performance, high reliability applications. Because of these performance short-comings, researchers are still searching for a material, an alloy, or a unique alternative that can meet the thermal, mechanical, and electrical requirements for conventional reflow solder applications. In an effort to produce a more reliable alternative, Kim et al. proposed the low-temperature (200C) sintering of copper-silver core-shell particles as a viable solderless interconnect technology. This technology is based on the silver atoms from the shell diffusing by surface diffusion to form sintered necks between copper particles, and therefore dewetting most of the copper surfaces. This study presents a 3-fold, in-depth evaluation of this Cu-Ag core-shell lead-free solderless interconnect technology focusing on solder paste development and prototyping, silver thin film stress relaxation and dewetting kinetics, and the environmental impacts associated with this new technology. First, an evaluation of the starting particle consistency and sintered compact mechanical properties determined that a specific core-shell particle geometry (1microm average core diameter and 10nm shell thickness) outperformed other combinations, exhibiting the highest modulus and yield strengths in sintered compacts, of 620 MPa and 40-60 MPa respectively. In particular, yield strengths for sintered compacts are similar to those reported for Sn-3.5Ag-0.75Cu (a commonly used lead-free solder) for the same strain rate. Following particle evaluations, the development of a functioning flux formulation was a key factor in the creation of a viable drop-in replacement. The processing of the final flux/particle paste combination was optimized at a commercial test facility for printing on test boards containing a wide variety of pad shapes, sizes, and pitches and thus, validated the ability of the Cu-Ag core-shell paste to be a drop-in replacement for traditional solder paste using conventional manufacturing techniques. The second study addresses the fundamental mechanisms behind interconnect formation. An assessment of the kinetics and microstructure evolution during silver thin film dewetting and defect formation provides essential materials science knowledge to understand and control the functionality of the Cu-Ag core-shell system. From an interrupted annealing study used to quantify dewetting kinetics, a range of surface diffusion coefficients were calculated from the experimental results, assuming that surface diffusion controlled dewetting. The two order of magnitude range in calculated diffusion coefficient demonstrates that the diffusion-limited kinetic models traditionally used to quantify hillock and hole growth kinetics during thin film relaxation and dewetting do not apply to the dewetting of Ag films. The presence of interface-limited kinetics was then validated through the non-uniform growth of individual hillocks over time. Lastly, an environmental assessment compares the impacts associated with the manufacturing and materials for the Cu-Ag core-shell particle system and SAC 305, the most commonly used lead-free solder alloy that contains 96.5% tin, 3% silver, and 0.5% copper. By comparing the impacts on global warming, acidification, eutrophication, ozone depletion, ecotoxicity, smog, carcinogenics, non-carcinogenics, and respiratory effects associated with each technology, the environmental advantages and disadvantages of each system are clearly communicated. By utilizing this information and the versatility of the core-shell system, possible methods for reducing impacts of the Cu-Ag core-shell system are addressed in order to reduce its environmental footprint. This multidimensional assessment provides a comprehensi

  8. Aluminum Matrix Composites Strengthened with CuZrAgAl Amorphous Atomized Powder Particles

    NASA Astrophysics Data System (ADS)

    Dutkiewicz, Jan; Rogal, ?ukasz; Wajda, Wojciech; Kuku?a-Kurzyniec, Agata; Coddet, Christian; Dembinski, Lucas

    2015-06-01

    The Al-matrix composites were prepared by hot pressing in vacuum of an aluminum powder with 20 and 40 wt.% addition of the amorphous Cu43Zr43Ag7Al7 alloy (numbers indicate at.%) obtained using gas atomization method. The amorphous structure of the powder was confirmed using x-ray diffraction, DSC, and TEM. The average size of mostly spherical particles was 100 ?m, so the powder was sieved to obtain maximum size of 60 ?m. The composites were prepared using uniaxial cold pressing in vacuum and at a temperature of 400 C. The composites of hardness from 43 to 53 HV were obtained for both additions of the amorphous phase. They reached compression strength of 150 MPa for 20% of amorphous phase and 250 MPa for the higher content. The modest hardening effect was caused by crack initiation at Al/amorphous interfaces. The amorphous phase was only partially crystallized in the hot-pressed composites, what did not cause hardness decrease. The application of nanocrystalline aluminum powders obtained by high-energy ball milling for the matrix of composites allowed obtaining nanocrystalline aluminum matrix composites of size near 150 nm, strengthened with the amorphous powders, whose compression strength was near 550 MPa for the composite containing 40% of the amorphous phase and slightly lower for the composite containing 20% of the phase. They showed much higher ductility of 23% in comparison with 7% for the composite containing 40% amorphous phase. The distribution of the strengthening phase in the nanocrystalline matrix was not homogeneous; the amorphous particles formed bands, where majority of cracks nucleated during compression test.

  9. Effect of electronic structures on catalytic properties of CuNi alloy and Pd in MeOH-related reactions

    SciTech Connect

    Tsai, An-Pang; Kimura, Tomofumi; Suzuki, Yukinori; Kameoka, Satoshi; Shimoda, Masahiko; Ishii, Yasushi

    2013-04-14

    We investigated the catalytic properties of a CuNi solid solution and Pd for methanol-related reactions and associated valence electronic structures. Calculations and X-ray photoelectron spectroscopy measurements revealed that the CuNi alloy has a similar valence electronic structure to Pd and hence they exhibited similar CO selectivities in steam reforming of methanol and decomposition of methanol. Samples prepared by various processes were found to have similar CO selectivities. We conjecture that alloying of Cu and Ni dramatically alters the valence electronic structures, making it similar to that of Pd so that the alloy exhibits similar catalytic properties to Pd. First-principles slab calculations of surface electronic structures support this conjecture.

  10. Experimental Investigation and Thermodynamic Calculation of the Phase Equilibria in the Cu-Ni-Sb Ternary System

    NASA Astrophysics Data System (ADS)

    Wang, C. P.; Huang, F.; Lu, Y.; Yang, S.; Yang, M. J.; Liu, X. J.

    2013-10-01

    We investigated the phase equilibria in the Cu-Ni-Sb ternary system at 800C, 900C, 1000C, and 1100C using equilibrated ternary alloys by optical microscopy, electron probe microanalysis, energy-dispersive spectroscopy, and x-ray diffraction analysis. Based on the experimental phase equilibria data, the Cu-Ni-Sb ternary system was thermodynamically optimized by calculating phase diagrams using the CALPHAD method. Substitutional solution and sublattice models were used to describe the solution and intermediate phases, respectively. The self-consistent parameters describing the Gibbs energy of each phase in the Cu-Ni-Sb system were optimized, obtaining reasonable agreement between the calculated results and most of the experimental data.

  11. Optimization of the Ni(P) Thickness for an Ultrathin Ni(P)-Based Surface Finish in Soldering Applications

    NASA Astrophysics Data System (ADS)

    Ho, C. E.; Wang, S. J.; Fan, C. W.; Wu, W. H.

    2014-01-01

    The effects of the Ni(P) thickness ? Ni(P) on the interfacial reaction between an Sn-3Ag-0.5Cu solder and an Au/Pd(P)/Ni(P)/Cu pad (thickness: 0.05/0.05/0.1-0.3/20 ?m) and the resulting mechanical properties were investigated using scanning electron microscopy equipped with an electron backscatter diffraction system, a focused ion beam system, electron probe microanalysis, and high-speed ball shear (HSBS) testing. Regardless of ? Ni(P), all of the Au/Pd(P)/Ni(P) surface finishes examined were completely exhausted in one reflow, exposing the Cu pad underneath the solder. Cu6Sn5 dissolved with various Ni contents, termed (Cu,Ni)6Sn5, was the dominant intermetallic compound (IMC) species at the solder/Cu interface. Additionally, Ni2SnP and Ni3P IMCs might form with the (Cu,Ni)6Sn5 in the thick Ni(P) case, i.e., ? Ni(P) = 0.3 ?m, and the two IMCs (Ni2SnP and Ni3P) were gradually eliminated from the interface after multiple reflows. A mass balance analysis indicated that the growth of the Ni-containing IMCs, rather than the dissolution of the metallization pad, played a key role in the Ni(P) exhaustion. The HSBS test results indicated that the mechanical strength of the solder joints was also ? Ni(P) dependent. The combined results of the interfacial reaction and the mechanical evaluation provided the optimal ? Ni(P) value for soldering applications.

  12. Orbital engineering near La2 NiO 4- La2 CuO 4 superlattice interfaces

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    Orbital states of transition metal oxides present the opportunity of adjusting material properties to a specific purpose (orbital engineering). A comparison of the resonant soft x-ray reflectivity of La 2 Ni O4 - La 2 Cu O4 superlattices at Ni L and Cu L edges shows different spatial distributions of the occupation of Ni d x 2 -y 2 and d 3z 2 -r 2 orbitals in the LNO layers. This modulation of the Ni valence is possible through a pronounced modulation of the density of oxygen interstitial dopants within the structure which does not follow exactly the structure itself. This is the first observation of orbital engineering in a 214 oxide. This work was supported by Grants DE-FG02-06ER46285, DE-AC02-98CH10886, MA-509-MACA, DE-FG02-07ER46453 and DE-FG02-07ER46471.

  13. Conversion of cyclohexane on Ni-(Sb, Pb, Cu)/Al sub 2 O sub 3 bimetallic catalysts

    SciTech Connect

    Lanh, H. D.; Khoai, Ng.; Thoang, H. S. ); Voelter, J. )

    1991-05-01

    Alumina-supported Ni catalysts, containing Sb, Pb, or Cu as a second metal (termed here the 'bimetal'), were studied in the conversion of cyclohexane. Activity and selectivity strongly depend on the reaction conditions as well as on the composition and the pretreatment of the catalysts. Each of the three second metals caused very similar positive effects, namely suppressed hydrogenolysis, enhanced dehydrogenation, and prolonged lifetime, as far as the cinversion at 500{degree}C is concerned, but at 300{degree}C only a negative, poisoning effect was observed. The conditions for maximum positive 'bimetal effect' are restricted to a Ni:second metal ratio of 9:1 and to calcination and reduction temperatures each of 500{degree}C. TPR experiments displayed interactions of Cu and Sb with Ni. The positive bimetal effect is explained by an ensemble effect due to a suggested dilution of Ni clusters by the second metals.

  14. Formation of honeycomb ordered monoclinic Li2M2TeO6 (M = Cu, Ni) and disordered orthorhombic Li2Ni2TeO6 oxides.

    PubMed

    Kumar, Vinod; Gupta, Akanksha; Uma, S

    2013-11-14

    Ion-exchange reactions of Na2Cu2TeO6 with excess of lithium nitrate at low temperature (300 C) readily resulted in an isostructural honeycomb ordered monoclinic layered structure Li2Cu2TeO6, otherwise inaccessible by direct solid state high temperature reactions. Similarly, Li2Ni2TeO6(I) stabilized approximately in equal amounts in both of the known P2-type polymorphs (P6(3)/mcm and P6(3)22) was synthesized as an ion-exchange reaction product from Na2Ni2TeO6 using a melt of lithium nitrate. Additionally, a unique tellurium containing oxide Li2Ni2TeO6(II) without the honeycomb ordering of Ni(2+)/Te(6+) ions has been obtained for the first time by the direct high temperature (800-900 C) synthesis. The oxides were investigated by refinement of powder X-ray diffraction patterns, room temperature magnetization experiments along with Raman spectroscopy and photoluminescence measurements. A structural model has been suggested for the metastable Li2Ni2TeO6(II) and the presence of structural disorder was evidenced in the broadening of the Raman bands and the intense broad photoluminescence (PL) spectra obtained for Li2Ni2TeO6(II). PMID:23995241

  15. Testing WHAM-FTOX with laboratory toxicity data for mixtures of metals (Cu, Zn, Cd, Ag, Pb).

    PubMed

    Tipping, Edward; Lofts, Stephen

    2015-04-01

    The Windermere humic aqueous model using the toxicity function (WHAM-FTOX ) describes cation toxicity to aquatic organisms in terms of 1) accumulation by the organism of metabolically active protons and metals at reversible binding sites, and 2) differing toxic potencies of the bound cations. Cation accumulation (?i , in mol g(-1) ) is estimated through calculations with the WHAM chemical speciation model by assuming that organism binding sites can be represented by those of humic acid. Toxicity coefficients (?i ) are combined with ?i to obtain the variable FTOX (= ? ?i ?i ) which, between lower and upper thresholds (FTOX,LT , FTOX,UT ), is linearly related to toxic effect. Values of ?i , FTOX,LT , and FTOX,LT are obtained by fitting toxicity data. Reasonable fits (72% of variance in toxic effect explained overall) were obtained for 4 large metal mixture acute toxicity experiments involving daphnids (Cu, Zn, Cd), lettuce (Cu, Zn, Ag), and trout (Zn, Cd, Pb). Strong nonadditive effects, most apparent in results for tests involving Cd, could be explained approximately by purely chemical competition for metal accumulation. Tentative interpretation of parameter values obtained from these and other experimental data suggests the following order of bound cation toxicity: H?Cu Zn Pb UO2 )?Ag). Another trend is a strong increase in Cd toxicity relative to that of Zn as organism complexity increases (from bacteria to fish). PMID:25318827

  16. Magnetically separable Ag3PO4/NiFe2O4 composites with enhanced photocatalytic activity.

    PubMed

    Patil, Santosh S; Tamboli, Mohaseen S; Deonikar, Virendrakumar G; Umarji, Govind G; Ambekar, Jalindar D; Kulkarni, Milind V; Kolekar, Sanjay S; Kale, Bharat B; Patil, Deepak R

    2015-12-21

    Magnetically separable Ag3PO4/NiFe2O4 (APO/NFO) composites were prepared by an in situ precipitation method. The photocatalytic activity of photocatalysts consisting of different APO/NFO mass ratios was evaluated by degradation of methylene blue (MB) under visible light irradiation. The excellent photocatalytic activity was observed using APO/NFO5 (5% NFO) composites with good cycling stability which is higher than that of pure Ag3PO4 and NiFe2O4. All the APO/NFO composites showed good magnetic behavior, which makes them magnetically separable after reaction and reusable for several experiments. Photoconductivities of pure and composite samples were examined to study the photoresponse characteristics. The current intensity greatly enhanced by loading NFO to APO. Furthermore, the photocatalytic performance of the samples is correlated with the conductivity of the samples. The enhancement in the photocatalytic activity of APO/NFO composites for MB degradation is attributed to the excellent conductivity of APO/NFO composites through the co-catalytic effect of NFO by providing accelerated charge separation through the n-n interface. PMID:26508302

  17. In situ growth of hollow CuNi alloy nanoparticles on reduced graphene oxide nanosheets and their magnetic and catalytic properties

    NASA Astrophysics Data System (ADS)

    Yang, Jinglei; Shen, Xiaoping; Ji, Zhenyuan; Zhou, Hu; Zhu, Guoxing; Chen, Kangmin

    2014-10-01

    Hollow CuNi nanocrystals supported on reduced graphene oxide (RGO-CuNi) are synthesized by in situ co-reduction of Cu2+, Ni2+ and graphene oxide (GO) in a one-pot reaction. The as-synthesized RGO-CuNi nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry, inductively coupled plasma optical emission spectrometry, Raman spectroscopy, and magnetic measurement. It is revealed that hollow CuNi nanocrystals with an average size of about 35.1 nm are uniformly deposited on the surface of RGO nanosheets. The formation mechanism of the hollow CuNi nanostructures is also proposed based on the galvanic displacement reaction. The as-synthesized RGO-CuNi nanocomposite exhibits excellent electrocatalytic performance toward the oxidation of glucose in alkaline media, and also shows superior catalytic activity and recycling stability toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Moreover, the RGO-CuNi catalysts can be easily recollected from the reaction system by an external magnetic field due to their considerable saturation magnetization. It is anticipated that loading hollow nanostructures on RGO sheets would open up a new avenue for developing multifunctional catalysts with low cost and high catalytic performance.

  18. Long-term superelastic cycling at nano-scale in Cu-Al-Ni shape memory alloy micropillars

    SciTech Connect

    San Juan, J. Gmez-Corts, J. F.

    2014-01-06

    Superelastic behavior at nano-scale has been studied along cycling in Cu-Al-Ni shape memory alloy micropillars. Arrays of square micropillars were produced by focused ion beam milling, on slides of [001] oriented Cu-Al-Ni single crystals. Superelastic behavior of micropillars, due to the stress-induced martensitic transformation, has been studied by nano-compression tests during thousand cycles, and its evolution has been followed along cycling. Each pillar has undergone more than thousand cycles without any detrimental evolution. Moreover, we demonstrate that after thousand cycles they exhibit a perfectly reproducible and completely recoverable superelastic behavior.

  19. Viscous flow of the Pd43Ni10Cu27P20 bulk metallic glass-forming liquid

    NASA Astrophysics Data System (ADS)

    Fan, G. J.; Fecht, H.-J.; Lavernia, E. J.

    2004-01-01

    The equilibrium viscosity of the Pd43Ni10Cu27P20 bulk metallic glass-forming liquid was measured over a wide temperature range from the equilibrium supercooled liquid state to the glass transition region using parallel-plate rheometry and three-point beam bending. Based on the measured viscosity data, the fragility of this liquid was quantitatively determined. The Pd43Ni10Cu27P20 alloy, despite exhibiting the best glass-forming ability reported thus far, is relatively fragile compared with other bulk glass-forming liquids, such as Vit 1 and Vit 4.

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

    SciTech Connect

    Zhang, Yawen; Huang, Wenyu; Habas, Susan E.; Kuhn, John N.; Grass, Michael E.; Yamada, Yusuke; Yang, Peidong; Somorjai, Gabor A.

    2008-07-22

    Near-monodisperse Ni{sub 1-x}Cu{sub x} (x = 0.2-0.8) bimetallic nanocrystals were synthesized by a one-pot thermolysis approach in oleylamine/1-octadecene, using metal acetylacetonates as precursors. The nanocrystals form large-area 2D superlattices, and display a catalytic synergistic effect in the hydrolysis of NaBH{sub 4} to generate H{sub 2} at x = 0.5 in a strongly basic medium. The Ni{sub 0.5}Cu{sub 0.5} nanocrystals show the lowest activation energy, and also exhibit the highest H{sub 2} generation rate at 298 K.