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1

Interfacial reaction between multicomponent lead-free solders and Ag, Cu, Ni, and Pd substrates  

Microsoft Academic Search

The interfacial reaction between two prototype multicomponent lead-free solders, Sn-3.4Ag-1Bi-0.7Cu-4In and Sn-3.4Ag-3Bi-0.7Cu-4In\\u000a (mass%), and Ag, Cu, Ni, and Pd substrates are studied at 250C and 150C. The microstructural characterization of the solder\\u000a bumps is carried out by scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis. Ambient temperature,\\u000a isotropic elastic properties (bulk, shear, and Youngs moduli and Poissons ratio)

G. Ghosh

2004-01-01

2

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

ERIC Educational Resources Information Center

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

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

2007-01-01

3

Cross-Interaction of Interfacial Reactions in Ni (Au\\/Ni\\/Cu)-SnAg-Cu Solder Joints during Reflow Soldering and Thermal Aging  

Microsoft Academic Search

Interfacial reactions in Ni-SnAg-Cu and Au\\/Ni\\/Cu-SnAg-Cu solder joints were investigated to understand the coupling effect\\u000a between different pads during soldering and thermal aging processes. Scanning electron microscopy (SEM) was used to characterize\\u000a the microstructures and phases. The element distributions in the joints were identified using the x-ray mapping technique.\\u000a The thickness variation of intermetallic compounds (IMCs) with aging time was

H. T. Chen; C. Q. Wang; C. Yan; M. Y. Li; Y. Huang

2007-01-01

4

Effect of Ag addition on the thermal characteristics and structural evolution of Ag-Cu-Ni ternary alloy nanoclusters: Atomistic simulation study  

NASA Astrophysics Data System (ADS)

Atomic-scale compositional variation in Ag contents across Ag-Cu-Ni alloy upon being subjected to repeated annealing cycles is shown to result in significant differences in the structure and the thermal stability of ternary alloy nanoclusters. Molecular dynamics (MD) simulations employing quantum Sutton-Chen potentials were used to investigate the effect of Ag addition on the thermal characteristics of Ag-Cu-Ni ternary alloy nanoclusters of 4-nm diameter. The initial configurations were generated using Monte Carlo simulations and comprise surface-segregated structures with the lowest surface energy component, Ag, occupying low coordination sites such as corners, edges, and faces. A compositional oscillation between the Cu and Ni atoms was observed for layers beneath the surface which transitions into a bulk alloy composition at the core. We find that the Cu-Ni binary alloys on being subjected to annealing schedules demonstrated an increase in thermal stability, as indicated by the increase in melting points. The annealed configurations of the Ag-Cu-Ni ternary alloy, on the other hand, showed a nonmonotonic behavior. For Ag compositions less than 20%, we observe an initial increase in melting point followed by a decrease in the third cycle. For higher Ag compositions (>20%), we observe a decrease in melting point with annealing; the rate of decrease is strongly correlated to the Ag composition in the alloy. Cu-Ni nanoclusters having 50% Cu showed a transition from an initial icosahedral to a cuboctahedron-like structure whereas Ag-rich Ag-Cu-Ni ternary alloys showed a transition from icosahedral to an amorphous structure. Compositional analysis based on radial distribution functions and density profiles indicate that these transitions were dependent on the distribution of the alloying elements in the nanocluster. Calculated root-mean-square displacements and diffusion coefficients indicate that the rate of mixing of Ag increases with Ag content in the Ag-Cu-Ni ternary alloy. Ternary alloys show heterogeneous melting during the first heating cycle followed by a bulk-like melting during the subsequent annealing cycles. The simulation results are consistent with available experimental studies.

Subbaraman, Ram; Sankaranarayanan, Subramanian K. R. S.

2011-08-01

5

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

SciTech Connect

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

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

2012-07-15

6

Clathrates with Me = Mg, Pd, Ni, Au, Ag, Cu, Zn, Al, Sn  

NASA Astrophysics Data System (ADS)

Clathrate materials of AlSi, CuSi or NiSi type consisting of abundant elements have a realistic chance of becoming useful thermoelectrics in the near future, because the rattling effect due to their crystal cage structure provides a large figure of merit ZT even in experiments measured under large temperature gradients. In the search for better thermoelectrics, new element combinations in the clathrate type I structure with cubic space group Pm3n were calculated using VASP ab initio software. Predictions of the Seebeck coefficient were made by checking the electronic band structure and density of states for a large variety of input data. For x values around 4 to 6 in the structural formula Ba8Me x Si46- x the substituents Cu, Au, and Ag are best for good thermoelectric behavior, which is discussed in this paper as a result of the low electron-phonon interaction parameter.

Wunderlich, Wilfried; Amano, Mao; Matsumura, Yoshihito

2014-06-01

7

A study of the vacancy loop formation probability in Ni-Cu and Ag-Pd alloys  

SciTech Connect

The molten-zone model of vacancy loop formation from a displacement cascade predicts that the loop formation probability should scale with the melting temperature. To investigate this possibility the vacancy loop formation probability has been determined in a series of Cu-Ni and Ag-Pd alloys. The irradiations were performed at room temperature with 50 keV Kr+ ions and the resulting damage structure was examined by using transmission electron microscopy. In the Cu-Ni alloy series, the change in loop formation probability with increasing Ni concentration was complex, and at low- and high- nickel concentrations, the defect yield did not change in the predicted manner. The defect yield was higher in the Cu-rich alloys than in the Ni-rich alloys. In the Ag-Pd alloy the change in the loop formation probability followed more closely the change in melting temperature, but no simple relationship was determined.

Smalinskas, K.; Chen, Gengsheng; Haworth, J.; Robertson, I.M. [Illinois Univ., Urbana, IL (United States). Dept. of Materials Science and Engineering; Kirk, M.A. [Argonne National Lab., IL (United States)

1992-04-01

8

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

Microsoft Academic Search

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

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

1986-01-01

9

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

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

10

Stacking-fault energies for Ag, Cu, and Ni from empirical tight-binding potentials  

NASA Astrophysics Data System (ADS)

The intrinsic stacking-fault energies and free energies for Ag, Cu, and Ni are derived from molecular-dynamics simulations using the empirical tight-binding potentials of Cleri and Rosato [Phys. Rev. B 48, 22 (1993)]. While the results show significant deviations from experimental data, the general trend between the elements remains correct. This allows one to use the potentials for qualitative comparisons between metals with high and low stacking-fault energies. Moreover, the effect of stacking faults on the local vibrational properties near the fault is examined. It turns out that the stacking fault has the strongest effect on modes in the center of the transverse peak, and its effect is localized in a region of approximately eight monolayers around the defect.

Meyer, R.; Lewis, L. J.

2002-08-01

11

Intermetallic compound formation in SnCoCu, SnAgCu and eutectic SnCu solder joints on electroless Ni(P) immersion Au surface finish after reflow soldering  

Microsoft Academic Search

The interfacial reactions between Sn0.4Co0.7Cu eutectic alloy and immersion Au\\/electroless Ni(P)\\/Cu substrate were investigated after reflow soldering at 260C for 2min. Common Sn4.0Ag0.5Cu and eutectic Sn0.7Cu solders were used as reference. Two types of intermetallic compounds (IMC) were found in the solder matrix of the Sn0.4Co0.7Cu alloy, namely coarser CoSn2 and finer Cu6Sn5 particles, while only one ternary (Cu, Ni)6Sn5

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

2006-01-01

12

Treatment of Au(II), Ag(I), Cu(II), Ni(II) from Electroplating Wastewater by Laminaria japonica: Biosorption, Desorption and Recycling  

Microsoft Academic Search

The pretreated brown algae Laminaria japonica was used to adsorb and desorb Au2+, Ag+, Cu2+ and Ni2+ ions from electroplating wastewater in this article. The results indicated that the biosorption process of Au2+, Ag+, Cu2+ and Ni2+ ions could be divided into two steps. The first step was physical adsorption and reached equilibrium quickly, in less than 15 min. This

Lin Li; He Yuan; Tian Chunyu; Wang Xian; Wang Liyi

2010-01-01

13

Struktur und Gitterdynamik Ultraduenner Epitaktischer Silber- und Eisenfilme Auf Ni(100)- und Cu(100)-Substraten (Structure and Grid Dynamics of Ultrathin Epitaxial Ag and Fe Films on Ni(100) and Cu(100) Substrates).  

National Technical Information Service (NTIS)

The surface phonon dispersions of ultrathin epitaxial Ag films on Ni(100) and Cu(100) substrates and epitaxial Fe films on a Cu(100) substrate were studied using inelastic scattering of slow electrons. The experimental data are compared with lattice dynam...

W. Daum

1988-01-01

14

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

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

15

Suppressing Sn-Patch Growth in Ti/Ni(V)/Cu Under Bump Metallization with Sn-Ag-Cu Solder After Reflow and Aging  

NASA Astrophysics Data System (ADS)

Sputtered Ti/Ni(V)/Cu under bump metallization (UBM) is widely used in flip chip technology because the metals are nonmagnetic and the consumption of the Ni(V) layer is low. It is noted that V does not react with solders and intermetallic compounds (IMC) during reflow and aging; however, a Sn-patch forms in the Ni(V) layer, and the Sn-patch growth may cause the IMCs to detach from the interface of solder joints. In this study, Sn-3.0Ag-0.5Cu solder was reflowed on Ti/Ni(V)/Cu UBM with different Cu thicknesses at 250C for 60 s, and then aged at 150C for various periods of time. It was revealed that the Sn-patch growth could be controlled by increasing the Cu thickness in the Ti/Ni(V)/Cu UBM. A feasible approach to suppress Sn-patch formation after reflow and aging is discussed.

Wang, Kai-Jheng; Duh, Jenq-Gong

2012-04-01

16

First-principles theory of short-range order in size-mismatched metal alloys: Cu-Au, Cu-Ag, and Ni-Au  

NASA Astrophysics Data System (ADS)

We describe a first-principles technique for calculating the short-range order (SRO) in disordered alloys, even in the presence of large anharmonic atomic relaxations. The technique is applied to several alloys possessing large size mismatch: Cu-Au, Cu-Ag, Ni-Au, and Cu-Pd. We find the following: (i) The calculated SRO in Cu-Au alloys peaks at (or near) the <100> point for all compositions studied, in agreement with diffuse scattering measurements. (ii) A fourfold splitting of the X-point SRO exists in both Cu0.75Au0.25 and Cu0.70Pd0.30, although qualitative differences in the calculated energetics for these two alloys demonstrate that the splitting in Cu0.70Pd0.30 may be accounted for by T=0 K energetics while T?0 K configurational entropy is necessary to account for the splitting in Cu0.75Au0.25. Cu0.75Au0.25 shows a significant temperature dependence of the splitting, in agreement with recent in situ measurements, while the splitting in Cu0.70Pd0.30 is predicted to have a much smaller temperature dependence. (iii) Although no measurements exist, the SRO of Cu-Ag alloys is predicted to be of clustering type with peaks at the <000> point. Streaking of the SRO peaks in the <100> and <1120> directions for Ag- and Cu-rich compositions, respectively, is correlated with the elastically soft directions for these compositions. (iv) Even though Ni-Au phase separates at low temperatures, the calculated SRO pattern in Ni0.4Au0.6, like the measured data, shows a peak along the direction, away from the typical clustering-type <000> point. (v) The explicit effect of atomic relaxation on SRO is investigated and it is found that atomic relaxation can produce significant qualitative changes in the SRO pattern, changing the pattern from ordering to clustering type, as in the case of Cu-Ag.

Wolverton, C.; Ozoli?, V.; Zunger, Alex

1998-02-01

17

Composition dependence of the high temperature superconductivity in (Ba,Sr)La(Hg,Ag)-Cu-O system with K2NiF4-type structure  

Microsoft Academic Search

Experimental data on the superconductivity of Ba-La-Cu-O and Sr-La-Cu-O compounds are presented. The effect of substituting Hg or Ag for Cu on the transition temperature of the Ba-La-Cu-O system is investigated. The phases of the compounds are analyzed using X-ray powder diffraction; the analysis reveals that the phase is single with a K2NiF4-type structure. Electrical resistance is measured, and the

Yoshitami Saito; Takashi Noji; Akihiko Endo; Nozomu Matsuzaki; Masao Katsumata

1987-01-01

18

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

NASA Astrophysics Data System (ADS)

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

Chee, Sang-Soo; Lee, Jong-Hyun

2014-05-01

19

On the correlation between phonon spectra and surface segregation features in Ag-Cu-Ni ternary nanoalloys  

NASA Astrophysics Data System (ADS)

Atomic scale characterization of chemical ordering, compositional distribution and microstructure is of tremendous importance for applications such as catalysis which is primarily dominated by processes occurring at surface and is strongly influenced by the subsurface layers. Phonon spectra obtained from molecular dynamics simulations of single metals as well as their bimetallic and ternary alloy nanoclusters can be used to obtain new insights into the atomic scale distribution in the nanoclusters, their microstructure and dynamical properties. Monte-Carlo (MC) simulations are used to obtain the minimum energy configurations of various Ag-Cu-Ni ternary alloys in which the Ag content is systematically varied from 0 to 50%Ag while keeping the relative composition of Cu and Ni constant. Detailed compositional analyses of the final MC configurations are carried out. The generated microstructure comprised of surface segregated structures in which Ag atoms occupy low coordination sites such as corners, edges and faces. As the Ag content in the ternary alloy is increased, the surface sites get increasingly occupied with the lowest coordination sites being populated first. The Cu and Ni compositions in the interior of the cluster show compositional oscillation. The final alloy microstructure is dictated by the competition between the various entropic and energetic factors. Our analysis of the phonon density of states identifies various surface (low frequency) and bulk (high frequency) modes which is determined by their location in the nanocluster and the local environment. Systematic trends in the observed peak intensities and frequency shifts at the low and high frequency ends of the spectrum for the various alloy compositions are explained on the basis of bond-lengths, local coordination, extent of alloying, and neighboring elemental environment. We find that the characteristic microstructural features observed at the atomic scale are strongly correlated to the vibrational densities of states of the constituent atoms in nanoalloys. Comparisons with experimental investigations are made where possible. Such a characterization method provides a predictive tool for materials which are extremely important for catalytic applications and emerging energy technologies.

Subbaraman, Ram; Sankaranarayanan, Subramanian K. R. S.

2011-08-01

20

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

21

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

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

22

A study of the vacancy loop formation probability in Ni-Cu and Ag-Pd alloys. [50-keV Kr sup + ions  

SciTech Connect

The molten-zone model of vacancy loop formation from a displacement cascade predicts that the loop formation probability should scale with the melting temperature. To investigate this possibility the vacancy loop formation probability has been determined in a series of Cu-Ni and Ag-Pd alloys. The irradiations were performed at room temperature with 50 keV Kr+ ions and the resulting damage structure was examined by using transmission electron microscopy. In the Cu-Ni alloy series, the change in loop formation probability with increasing Ni concentration was complex, and at low- and high- nickel concentrations, the defect yield did not change in the predicted manner. The defect yield was higher in the Cu-rich alloys than in the Ni-rich alloys. In the Ag-Pd alloy the change in the loop formation probability followed more closely the change in melting temperature, but no simple relationship was determined.

Smalinskas, K.; Chen, Gengsheng; Haworth, J.; Robertson, I.M. (Illinois Univ., Urbana, IL (United States). Dept. of Materials Science and Engineering); Kirk, M.A. (Argonne National Lab., IL (United States))

1992-04-01

23

Failure Morphology after the Drop Impact Test of the Ball Grid Array Package with Lead-Free Sn3.8Ag0.7Cu on Cu and Ni Under-Bump Metallurgies  

Microsoft Academic Search

High strain-rate drop impact tests were performed on ball grid array (BGA) packages with lead-free Sn-3.8Ag-0.7Cu solder (in\\u000a wt.%). Plated Ni and Cu under-bump metallurgies (UBMs) were used on the device side, and their drop test performances were\\u000a compared. Failure occurred at the device side, exhibiting brittle interfacial fracture. For Ni UBM, failure occurred along\\u000a the Ni\\/(Cu,Ni)6Sn5 interface, while the

J. W. Jang; J. K. Lin; D. R. Frear

2007-01-01

24

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

25

Dissociative adsorption of oxygen and hydrogen, and the formation of hydroxyl groups on the surface of Cu, Ag, Ni, Pd and Pt  

Microsoft Academic Search

By the semi-empirical interacting bonds method, the heats of oxygen and hydrogen adsorption in a dissociative form on the (100) face of Cu, Ag, Ni, Pd and Pt have been calculated. It has been shown that most stable are the multiply bonded adsorption forms. For the different bonding states, the heat of hydroxyl group formation from O2 and H2 varies

V. A. Sobyanin; N. N. Bulgakov; V. V. Gorodetskii

1977-01-01

26

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

SciTech Connect

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.

Li, J. H.; Kong, Y.; Guo, H. B.; Liang, S. H.; Liu, B. X. [Advanced Materials Laboratory, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

2007-09-01

27

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

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

28

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

Microsoft Academic Search

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

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

2003-01-01

29

Ag-Cu System  

NSDL National Science Digital Library

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

Kattner, Ursula

2003-01-01

30

Effects of High-Temperature Treatment on the Reaction Between Sn-3%Ag-0.5%Cu Solder and Sputtered Ni-V Film on Ferrite Substrate  

NASA Astrophysics Data System (ADS)

We have demonstrated a novel sputtering method for lead-free thin metal films on ferrite substrates for surface-mount inductor applications. In a surface-mounting process, the cladding of enameled wire needs to be burnt off at high temperature, which requires the devices to withstand a high-temperature reliability test at 420C for 10 s. There are no reports that a sputtered film of thickness less than 6 ?m can withstand this test. In this work, we used Ag/Ni-7 wt.%V double metal layers for the metallization. The dissolution of Ni-7 wt.%V in Sn-3%Ag-0.5%Cu lead-free solder at various temperatures was studied in detail. Scanning electron microscopy with energy-dispersive x-ray spectroscopy was used to investigate the interfacial reaction between the sputtered films and the solder. The intermetallic compounds are mainly (Cu,Ni)6Sn5 at 250C; however, (Ni,Cu)3Sn4 becomes the predominant composition at 420C. In addition, although outdiffusion of V atoms from the Ni-V layer was observed, its effect on the intermetallic compound (IMC) was insignificant. We further confirmed that the proposed metallization is able to pass the aforementioned high-temperature reliability test.

Shen, Xiaohu; Jin, Hao; Dong, Shurong; Wong, Hei; Zhou, Jian; Guo, Zhaodi; Wang, Demiao

2012-11-01

31

Geometric factors in f.c.c. and b.c.c. metal-on-metal epitaxy. Part I. Deposits of Cu and Ni on (001) Ag  

Microsoft Academic Search

Electron microscopy has been used to examine films of Cu and Ni (mean thickness, tm ? 100nm) vacuum-deposited (1 10?5 10 N m) at substrate temperatures, TS, in the range 93 K-700 K onto (001) Ag films.The results show that under certain conditions it is possible to prepare a metal deposit with a crystal and\\/or defect structure not

L. A. Bruce; H. Jaeger

1977-01-01

32

Density functional study of M 4 clusters (M=Cu, Ag, Ni, Pd) deposited on the regular MgO(001) surface  

Microsoft Academic Search

The interaction of square-planar M4 clusters (M=Ag, Cu, Ni, Pd) with the ideal MgO(001) surface has been investigated using a gradient-corrected density functional (DF) method and substrate model clusters for adsorption sites in the vicinity of O2? centers. Polarization of the adsorbed metal clusters due to the surface electric field provides an important contribution to metaloxide bonds. No significant elongation

Alexei V. Matveev; Konstantin M. Neyman; Gianfranco Pacchioni; Notker Rsch

1999-01-01

33

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

NASA Astrophysics Data System (ADS)

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

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

34

Effect of diode-laser parameters on shear force of micro-joints soldered with Sn-Ag-Cu lead-free solder on Au\\/Ni\\/Cu pad  

Microsoft Academic Search

Soldering experiments with Sn-3.5Ag-0.5Cu lead-free solder on Au\\/Ni\\/Cu pad were carried out by means of diode-laser and IR reflow soldering methods respectively. The influence of different heating methods as well as output power of diode-laser on shear force of micro-joints was studied and the relationship between the shear force and microstructures of micro-joints was analyzed. The results indicate that the

Jian-xin WANG; Song-bai XUE; Dian-song FANG; Jin-long JU; Zong-jie HAN; Li-hua YAO

2006-01-01

35

Glow discharge sputtering deposition of thin films of Ag, Cr, Cu, Ni, Pd, Rh and their binary alloys onto NaCl and MgO Experimental parameters and epitaxy  

Microsoft Academic Search

The experimental conditions to condense epitaxial films of Ag, Cr, Cu, Ni, Pd, Rh, AgPd, CuPd and CuRh on MgO(100) and NaCl(100) by glow discharge sputtering are reported. The films are characterized by THEED, RHEED, SAD, TEM, ICP and AES. The effect of the substrate, the temperature and the target composition on the films obtained is examined and discussed. Perfect

F. Reniers; M. P. Delplancke; A. Asskali; V. Rooryck; O. Van Sinay

1996-01-01

36

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

37

Glow discharge sputtering deposition of thin films of Ag, Cr, Cu, Ni, Pd, Rh and their binary alloys onto NaCl and MgO Experimental parameters and epitaxy  

NASA Astrophysics Data System (ADS)

The experimental conditions to condense epitaxial films of Ag, Cr, Cu, Ni, Pd, Rh, AgPd, CuPd and CuRh on MgO(100) and NaCl(100) by glow discharge sputtering are reported. The films are characterized by THEED, RHEED, SAD, TEM, ICP and AES. The effect of the substrate, the temperature and the target composition on the films obtained is examined and discussed. Perfect parallel epitaxy ((001)[110] d?(100)[110] s) was observed for all systems studied, except for Ag/MgO.

Reniers, F.; Delplancke, M. P.; Asskali, A.; Rooryck, V.; Van Sinay, O.

1996-02-01

38

An analysis of interdiffusion in finite-geometry, two-phase diffusion couples in the Ni?W and Ag?Cu systems  

Microsoft Academic Search

The progress of homogenization in finite, multilayer diffusion couples was studied experimentally using both quantitative\\u000a metallography to measure phase thicknesses and electron microprobe analysis to determine concentration-distance profiles.\\u000a Ni?W couples having mean compositions in the nickel-rich terminal solid solution range (12.1 and 15.2 at. pct W) were studied\\u000a after 4.43 to 240.7 hr interdiffusion treatments at 1156 and 1207C. Ag?Cu

R. A. Tanzilli; R. W. Heckel

1971-01-01

39

Wettability of zirconium diboride ceramics by Ag, Cu and their alloys with Zr  

Microsoft Academic Search

Sintered ZrB2 ceramics, pure and with 4 wt.% Ni as sintering aid, have been tested in contact with liquid Ag, Cu, AgCu and AgCuZr. Pure ZrB2 ceramics are wetted by AgZr alloys, and ZrB2\\/Ni ceramics also by pure Cu. The wetting behaviour is briefly discussed in terms of existing wetting theories.

M. L Muolo; E Ferrera; R Novakovic; A Passerone

2003-01-01

40

Calculation of the intrinsic coefficient of thermal expansion of spherical, coherent inclusions: Application to Al-Ag, Fe-Cu, and Ni-Al  

NASA Astrophysics Data System (ADS)

With the use of the definition of the intrinsic coefficient of thermal expansion (ICTE) ?d of a point defect, and in consideration of the Eshelby-calculated change in matrix volume caused by the appearance of an inclusion as the inclusion's volume of formation, the calculation of the ICTE of spherical, coherent inclusions is effected. It is found that ?d?, where ? is the CTE of the matrix, can grow very large (?d?>>1) as a direct result of the singular nature of the temperature derivative of the matrix-inclusion contact stress for nearly equal values of the matrix and inclusion lattice parameters. It is precisely in this domain that the tool presently used to treat the problem, linear elastic theory, has its greatest validity. The model is applied to three real alloy systems, two of which, Al-Ag, and Fe-Cu, contain Guinier-Preston zones, whereas the third, Ni-Al, contains ?' precipitates. ?d? is found to be -5.2, +150, and -18 for Al-Ag, Fe-Cu, and Ni-Al, respectively. In addition, the easily measurable predicted isothermal change in matrix volume caused by the precipitates in Al-Ag and Ni-Al indicates the important role that dilatative properties can play in the experimental determination of precipitate-growth kinetics. The present calculation shows that the absolute value of the ITCE of atomically large, spherical, Eshelby-type coherent inclusions can, as for point defects, considerably exceed that of the matrix, and under certain conditions can attain values that dwarf those of point defects.

Gilder, H. M.

1982-01-01

41

Dissolution and Interfacial Reactions of (Cu,Ni)6Sn5 Intermetallic Compound in Molten Sn-Cu-Ni Solders  

NASA Astrophysics Data System (ADS)

(Cu,Ni)6Sn5 is an important intermetallic compound (IMC) in lead-free Sn-Ag-Cu solder joints on Ni substrate. The formation, growth, and microstructural evolution of (Cu,Ni)6Sn5 are closely correlated with the concentrations of Cu and Ni in the solder. This study reports the interfacial behaviors of (Cu,Ni)6Sn5 IMC (Sn-31 at.%Cu-24 at.%Ni) with various Sn-Cu, Sn-Ni, and Sn-Cu-Ni solders at 250C. The (Cu,Ni)6Sn5 substrate remained intact for Sn-0.7 wt.%Cu solder. When the Cu concentration was decreased to 0.3 wt.%, (Cu,Ni)6Sn5 significantly dissolved into the molten solder. Moreover, (Cu,Ni)6Sn5 dissolution and (Ni,Cu)3Sn4 formation occurred simultaneously for the Sn-0.1 wt.%Ni solder. In Sn-0.5 wt.%Cu-0.2 wt.%Ni solder, many tiny (Cu,Ni)6Sn5 particulates were formed and dispersed in the solder matrix, while in Sn-0.3 wt.%Cu-0.2 wt.%Ni a lot of (Ni,Cu)3Sn4 grains were produced. Based on the local equilibrium hypothesis, these results are further discussed based on the liquid-(Cu, Ni)6Sn5-(Ni,Cu)3Sn4 tie-triangle, and the liquid apex is suggested to be very close to Sn-0.4 wt.%Cu-0.2 wt.%Ni.

Wang, Chao-hong; Lai, Wei-han; Chen, Sinn-wen

2014-01-01

42

Epitaxial growth of Ag on Ni(111)  

NASA Astrophysics Data System (ADS)

Time of flight impact-collision ion scattering spectroscopy (TOF-ICISS) have been used to investigate the heteroepitaxial growth of 3 ML of Ag on Ni(111). We found that two different of preferred epitaxial growth exist depending on the substrate temperature during Ag deposition: Ag[112]//Ni[112] and Ag[112]//Ni[112]. These experimental results strongly suggest that the growth modes can be manipulated on the heteroepitaxial system, Ag(111)/Ni(111) by controlling the substrate temperature during Ag deposition.

Ito, T.; Umezawa, K.; Nakanishi, S.

1998-06-01

43

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

NASA Astrophysics Data System (ADS)

The microstructural evolution between Sn-3Ag-0.5Cu (SAC305) solder and Ni(P)/Pd(P)/Au finish during the reflow process was investigated for various Pd(P) thicknesses (0 ?m to 0.6 ?m). The reflow process was carried out in a belt-conveying reflow oven with peak temperature of 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.

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

2012-12-01

44

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

PubMed

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

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

2014-10-01

45

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

Microsoft Academic Search

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

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

2002-01-01

46

Direct determination of Ag, Cu and Ni in solid materials by graphite furnace atomic absorption spectrometry using a specially designed graphite tube  

NASA Astrophysics Data System (ADS)

This paper presents first results of a study using a specially designed graphite tube ("ring chamber tube") for direct solid sample analysis. This tube allowed the introduction of a relatively large amount (up to 10 mg) of solid material into a separate chamber around the middle part of the atomisation volume to avoid any disturbance of the optical light path in the atomisation volume due to the solid material. Graphite tubes without and with pyrolytic coatings have been used. Best results were obtained using low and well-defined ramp rates, long integration times and integration of the absorbance (A.s) signals. The good analytical applicability of this tube is demonstrated by several examples: Ag in gold wire for microelectronics and Cu and Ni in plant material. The results obtained from three different methods of calibration are in good agreement with the certified values. The detection limits reached for the three elements are in the pg-range.

Schmidt, K. P.; Falk, H.

47

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

48

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

NASA Astrophysics Data System (ADS)

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

Li, Yuan; Audtat, Andreas

2012-11-01

49

Ag-Cu-Sn System  

NSDL National Science Digital Library

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

Kattner, Ursula

2003-01-01

50

Ag-Bi-Cu System  

NSDL National Science Digital Library

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

Kattner, Ursula

2003-01-01

51

Ag-Cu-Pb System  

NSDL National Science Digital Library

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

Kattner, Ursula

2003-01-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

53

Comparative investigation of the nucleation and growth of fcc-metal particles (Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au) on amorphous carbon and SiO 2 substrates during vapor deposition at elevated temperatures  

NASA Astrophysics Data System (ADS)

The condensation of various fcc metals (Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au) from the vapor phase on thin film substrates of amorphous carbon and SiO 2 was systematically investigated by TEM, partly in situ, as well as by EDX. At temperatures up to 723 K, condensation of the metals was generally complete, except for Au and Ag on SiO 2. On SiO 2 all metals condensed as finely dispersed particles, and their number densities saturated by coalescence in the 10 12/cm 2 range. The nucleation and growth kinetics could be well fitted by the "classical" atomistic model, with stable dimers, and surface diffusion of only monomers, with activation energies of around 1 eV. On a-C, Ir, Pt, Rh and Au assumed even higher particle number densities. In contrast, for Pd, Ag, Ni and Cu on a-C, the particle number densities were lower by more than one order of magnitude, and approached saturation long before coalescence. Moreover, in situ TEM experiments revealed a delay in nucleation, which was only slight for Au, but considerable for particles of Pd, Ag and Ni, which exhibited high growth speeds subsequently. Also, growth transients were observed upon beam interruptions. These effects could not be explained by the classical model. Rather, it seems that some material is trapped at special sites in the substrate, such that it does not contribute to nucleation and cluster growth. This was supported by Monte Carlo simulations. In addition, Pd, Ag and Ni atoms are relatively weakly bound to those sites such that they may be re-emitted in an activated process for later incorporation into nucleated clusters.

Schmidt, A. A.; Eggers, H.; Herwig, K.; Anton, R.

1996-04-01

54

Study of interfacial reactions in Sn3.5Ag3.0Bi and Sn8.0Zn3.0Bi sandwich structure solder joint with Ni(P)\\/Cu metallization on Cu substrate  

Microsoft Academic Search

In this paper, the coupling effect in Sn3.5Ag3.0Bi and Sn8.0Zn3.0Bi solder joint with sandwich structure by long time reflow soldering was studied. It was found that the interfacial compound at the Cu substrate was binary CuSn compound in SnAgBi solder joint and Cu5Zn8 phase in SnZnBi solder joint. The thickness of the CuZn compound layer formed at the Cu substrate

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

2007-01-01

55

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

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

56

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

Microsoft Academic Search

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

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

1993-01-01

57

The influence of solder volume and pad area on Sn3.8Ag0.7Cu and Ni UBM reaction in reflow soldering and isothermal aging  

Microsoft Academic Search

This paper examines various aspects of SAC (Sn3.8Ag0.7Cu wt.%) solder and UBM interactions which may impact interconnection reliability as it scales down. With different solder joint sizes, the dissolution rate of UBM and IMC growth kinetics will be different. Solder bumps on 250, 80 and 40?m diameter UBM pads were investigated. The effect of solder volume\\/pad metallization area (V\\/A) ratio

C. K. Wong; J. H. L. Pang; J. W. Tew; B. K. Lok; H. J. Lu; F. L. Ng; Y. F. Sun

2008-01-01

58

Evaluation of soldering and reliability performance of NiPdAu finished PPF with Pb-free solder alloy 95.5Sn4.0Ag0.5Cu  

Microsoft Academic Search

In this study, SO14 (14 pin small-outline package), TSSOP20 (thin shrink small-outline package) and TSSOP56 are taken as carriers to study the soldering and reliability performance of preplated NiPdAu finished components (PPF). The Pd layer is 0.5mu-inch thick and after preconditioning, the components are assembled on test boards with SAC Pb-free solder alloy (Sn4.0Ag0.5Cu). Preconditioning is aimed to simulate storage.

X. J. Zhao; J. F. J. M. Caers

2006-01-01

59

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

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

60

Electrodeposited NiCo/Cu Superlattices  

SciTech Connect

NiCo/Cu superlattices were electrodeposited on polycrystalline Cu substrates from a single electrolyte under potentiostatic control. The X-ray diffraction (XRD) patterns showed that NiCo/Cu superlattices have the same crystal structure and texture as in their substrates. The films exhibited giant magnetoresistance (GMR) or anisotropic magnetoresistance (AMR), depending on the Cu layer thicknesses.

Safak, M.; Alper, M. [Department of Physics, Faculty of Science and Literature, University of Uludag, Goeruekle, Bursa (Turkey)

2007-04-23

61

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

62

Microstructure and interfacial reactions of vacuum brazing titanium alloy to stainless steel using an AgCuTi filler metal  

Microsoft Academic Search

The microstructure and interfacial reactions of the vacuum brazed titanium alloy (TC4) to stainless steel (1Cr18Ni9Ti) using an AgCuTi filler metal at 920C and 980C have been investigated. The results show that the main interfacial microstructure of the sample brazed at 920C was 1Cr18Ni9Ti\\/CuTi\\/Ag-rich+Cu4Ti\\/Cu4Ti\\/?-Ti\\/TC4. Shear tests on brazed specimens show that the fractures occurred in the Ag-rich phase, indicating a

X. Yue; P. He; J. C. Feng; J. H. Zhang; F. Q. Zhu

2008-01-01

63

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

SciTech Connect

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

Kim, Kwang Joo.

1990-10-17

64

Transmission electron microscopy study of Ni-rich, Ag-Ni nanowires  

NASA Astrophysics Data System (ADS)

Present work provides an electrodeposition based methodology for synthesizing Ni-rich, Ag-Ni nanowires using an alumina template. Ag-Ni system shows negligible solid solubility in the bulk. Detailed structural and compositional characterization of as-synthesized nanowires using transmission electron microscopy technique revealed a two phase microstructure. Regions along and near the nanowire axis contained crystalline Ag-Ni solid solution phase with Ag-rich composition. Whereas, regions away from the axis and near the nanowire boundary predominantly contained nanocrystalline Ni-rich, Ni-Ag solid solution phase.

Srivastava, Chandan; Rai, Rajesh Kumar

2013-06-01

65

Two phase microstructure for Ag-Ni nanowires  

NASA Astrophysics Data System (ADS)

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

Srivastava, Chandan; Rai, Rajesh Kumar

2013-03-01

66

Influence of Cu content on compound formation near the chip side for the flip-chip Sn-3.0Ag-(0.5 or 1.5)Cu solder bump during aging  

NASA Astrophysics Data System (ADS)

Sn-Ag-Cu solder is a promising candidate to replace conventional Sn-Pb solder. Interfacial reactions for the flip-chip Sn-3.0Ag-(0.5 or 1.5)Cu solder joints were investigated after aging at 150C. The under bump metallization (UBM) for the Sn-3.0Ag-(0.5 or 1.5)Cu solders on the chip side was an Al/Ni(V)/Cu thin film, while the bond pad for the Sn-3.0Ag-0.5Cu solder on the plastic substrate side was Cu/electroless Ni/immersion Au. In the Sn-3.0Ag-0.5Cu joint, the Cu layer at the chip side dissolved completely into the solder, and the Ni(V) layer dissolved and reacted with the solder to form a (Cu1-y,Niy)6Sn5 intermetallic compound (IMC). For the Sn-3.0Ag-1.5Cu joint, only a portion of the Cu layer dissolved, and the remaining Cu layer reacted with solder to form Cu6Sn5 IMC. The Ni in Ni(V) layer was incorporated into the Cu6Sn5 IMC through slow solid-state diffusion, with most of the Ni(V) layer preserved. At the plastic substrate side, three interfacial products, (Cu1-y,Niy)6Sn5, (Ni1-x,Cux)3Sn4, and a P-rich layer, were observed between the solder and the EN layer in both Sn-Ag-Cu joints. The interfacial reaction near the chip side could be related to the Cu concentration in the solder joint. In addition, evolution of the diffusion path near the chip side in Sn-Ag-Cu joints during aging is also discussed herein.

Jang, Guh-Yaw; Duh, Jeng-Gong; Takahashi, Hideyuki; Lu, Szu-Wei; Chen, Jen-Chuan

2006-09-01

67

The fabrication and properties of Ag/Ni nanocomposite fluid.  

PubMed

In this article, an arc-submerged nanofluid synthesis system is proposed and developed for Ag/Ni nanocomposite fluid fabrication. In the fabrication process, the positive electrode uses an Ag rod and the negative electrode uses a Ni rod, with the two electrodes processed in the dielectric liquid. The nanocomposite fluid generated by the synthesis system is analyzed by morphological analysis, heat transfer analysis, magnetic analysis and the UV-Vis spectrophotometer optical property analysis. Experimental results show that the Ag/Ni nanocomposite fluid has a very high Zeta potential of 45 mV, so that without dispersant it can remain stabile longer than five months. Testing the Ag/Ni nancomposite fluid magnetism by SQUID, shows that paramagnetism appears in the nanocomposite fluid. Moreover, the Ag/Ni nanocomposite fluid preserves both the nickel's magnetic characteristic and silver's absorption capability to visible light. PMID:20359015

Chang, Ho; Kao, Mu-Jung; Yeh, Yu-Hsuan

2010-05-01

68

Photo-injection of hydrogen in Ag and Cu halides  

Microsoft Academic Search

For the first time photo-initiated injection of hydrogen was carried out into Ag- and Cu-halides (AgCl, AgJ, Ag4RbI5, CuCl) -- the materials which are very important for investigations of the photographic process. To carry out the photoinjection of hydrogen into the halides a double-layer structure was used. Onto a quartz substrate two thin films were evaporated one after the other:

Alexander Gavrilyuk

1997-01-01

69

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

70

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

Microsoft Academic Search

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

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

2002-01-01

71

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

72

Magnetic ordering and physical stability of X2Mn1+xSn1-x (X=Ru, Os, Co, Rh, Ni, Pd, Cu, and Ag) Heusler alloys from a first-principles study  

NASA Astrophysics Data System (ADS)

The magnetic ordering and its effect on the physical stability of X2Mn1+xSn1-x (0?x?0.5, and X=Ru, Os, Co, Rh, Ni, Pd, Cu, and Ag) Heusler alloys are investigated systematically by the use of first-principles method. It is found that the ferromagnetic (FM) coupling between Mn on Mn sublattice (Mn1) and Mn on Sn sublattice (Mn2) is favorable over the antiferromagnetic (AFM) coupling for X with the number of valence electrons [Nv(X)] of 8 and 9, and vice versa for X with Nv(X)=10 and 11, originated from the competition of the exchange interactions between X-Mn2 and Mn1-Mn2. In comparison with the FM Mn1-Mn2 coupling, the AFM coupling decreases significantly the shear elastic constant C' but increases slightly C44, which results in increasing elastic anisotropy (A=C44/C') and consequently may facilitate the tetragonal shear lattice deformation. The hybridization of the minority electronic states between X d and Sn p plays a dominant role on the orientation of the magnetic coupling. The smaller change of the density of states in the Fermi level, induced by the lattice distortion for C', corresponds to the softer C' as well as the larger A in the AFM state than the FM one.

Li, Chun-Mei; Hu, Qing-Miao; Yang, Rui; Johansson, Brje; Vitos, Levente

2013-07-01

73

Growth and Stability of Ag Layers on Cu(110).  

National Technical Information Service (NTIS)

Combined surface science and high energy ion beam techniques have been used to characterize the composition, structure and thermal stability of Ag layers < 900A thick on Cu(110). A uniform Ag/Cu surface composite is formed for one monolayer coverage. Anal...

T. N. Taylor, M. A. Hoffbauer, C. J. Maggiore, J. G. Beery

1986-01-01

74

Formation of an unconventional Ag valence state in Ag2NiO2  

NASA Astrophysics Data System (ADS)

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

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

2007-05-01

75

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

PubMed

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

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

2013-02-28

76

Magnetic properties of mechanically alloyed Fe-Ni-Ag  

SciTech Connect

The authors prepared mechanically alloyed samples of FeNi, FeNi{sub 3}, and (FeNi{sub 3}){sub 1{minus}x}Ag{sub x}. The production of nanometer size grains was confirmed by x-ray broadening and electron microscopy. X-ray measurements indicated that a small amount ({approximately}7%) of Ag could be alloyed into the Fe-Ni and that considerable lattice strain was present. Moessbauer and magnetic measurements found no evidence for superparamagnetism in these alloys.

Bennett, L.H.; Swartzendruber, L.J.; Weissmueller, J.; Bendersky, L.A.; Shapiro, A.J. [NIST, Gaithersburg, MD (United States)] [NIST, Gaithersburg, MD (United States); Takacs, L. [Univ. of Maryland Baltimore County, Catonsville, MD (United States)] [Univ. of Maryland Baltimore County, Catonsville, MD (United States)

1995-12-01

77

EAM study of surface self-diffusion of single adatoms of fcc metals Ni, Cu, Al, Ag, Au, Pd, and Pt  

NASA Astrophysics Data System (ADS)

Self-diffusion of single adatoms on the (100), (110), (111), (311), and (331) surfaces of fcc metals is investigated with the embedded atom method (EAM). The general trend of activation energies for these surfaces is consistent with experimental observations. The calculated activation energies for Ni are in excellent agreement with experimental data, but those for Al and Pt differ from experimental values by up to a factor of 3. The estimated pre-exponential factors are in the range of 10 -4-10 -2{cm 2}/{s}, in good agreement with experiment.

Liu, C. L.; Cohen, J. M.; Adams, J. B.; Voter, A. F.

1991-08-01

78

Microstructural analysis and optoelectrical properties of Cu 2O, Cu 2OAg, and Cu 2O\\/Ag 2O multilayered nanocomposite thin films  

Microsoft Academic Search

Cu2O, Cu2OAg nanocomposite, and Cu2O\\/Ag2O multilayered thin films were prepared by DC-reactive magnetron sputtering on glass substrates. After deposition, the microstructure of the films was examined using X-ray diffractometry and transmission electron microscopy (TEM). An incident-photon-conversion-efficiency (IPCE) system was used to characterize the opto-electrical properties of these films. The TEM study reveals that Cu2OAg nanocomposite consists of Cu2O, Ag2O, and

C. C. Tseng; J. H. Hsieh; W. Wu

2011-01-01

79

Chemical Preparation and Characterization of Elemental Cu, Ni, and Cu/Ni Core/Shell Nanoparticles  

NASA Astrophysics Data System (ADS)

Elemental Ni, Cu, and Cu core/Ni shell nanoparticles have been prepared in a polyol-type process. The elemental nanoparticles were prepared by dissolving NiCl2.6H2O and/or CuCl2.2H2O in ethylene glycol (EG) and heating the solution to reflux prior to the addition of NaOH. The resulting precipitate was then extracted, dried, and characterized by scanning electron microscopy (SEM) with elemental analysis, x-ray diffraction (XRD), and in the case of the elemental Ni nanoparticles, vibrating sample magnetometry (VSM) measurements. The best fit lattice parameters obtained from the elemental Ni and Cu nanoparticles were 0.35289(28) and 0.36171(23) nm, respectively, in good agreement with the corresponding bulk values. On the other hand, the measured saturation magnetization of about 49 emu/g was somewhat smaller than the bulk Ni value. In the case of the Cu/Ni nanoparticles, the best fit lattice parameters for the Ni and Cu components of the core/shell structure were 0.35299(26) and 0.36101(10) nm, indicating the formation of an essentially pure Ni shell and a slight amount of Ni incorporation in the Cu core.

Higgins, Laura; Lattanzi, Michael; Kelly, Brian; Poirier, Gerald; Unruh, Karl

2011-03-01

80

Ag/Cu(111) surface structure and metal epitaxy by impact-collision ion-scattering spectroscopy and scanning tunneling microscopy  

NASA Astrophysics Data System (ADS)

We have investigated the growth of 3 monolayers (ML) of Ag on Cu(111) for substrate temperatures from 170 through 640 K by using time of flight-impact collision ion scattering spectroscopy (TOF-ICISS). Also, scanning tunneling microscopy (STM) topographs were taken after the deposition of 0.8 ML of Ag atoms at room temperature (RT). We observed that for deposition of Ag at substrate temperatures above 300 K, two different types of epitaxial growth exist: Ag[112]?Cu[112] (type-n) and Ag[112]?Cu[112] (type-r). The growth modes of the Ag thin films on Cu(111) surfaces depend strongly on the temperature during deposition with the Ag(111) planes having a preferred orientation of either type-n growth mode or type-r growth mode as a function of the Cu substrate temperature. A part of the first-layer Cu atoms (20% of the surface) is displaced at low Ag coverage, where the stacking changes abruptly from fcc to hcp sites because of the Ag atom deposition at 603 K. The STM image of the Ag coverage of 0.8 ML showed a periodic array of triangular misfit dislocation loops at the deposition temperature of RT. The triangular shape in a localized region where the stacking \\{Ag-Cu (A)-Cu (B)-Cu (C)\\} is replaced by \\{Ag-Cu (C)-Cu (B)-Cu (C)\\} in the first substrate plane. At 603 K, surface alloying of the Ag-Cu system was confirmed for Ag coverage below 0.15 ML. The experimental results concerning Ag/Cu(111) show many similarities to those in the previous study of Au/Ni(111). This would suggest that observed oscillations in the growth mode, dependent on the substrate temperature during deposition, may be a general phenomenon on solid surfaces, in cases of large misfit since it has now been seen for both Au/Ni(111) and Ag/Cu(111) systems. Furthermore, Cu atoms deposited on the Ag/Cu(111) system form islands with the same orientation of Ag(111) planes. The Cu atoms undergo surface diffusion at room temperature in the direction of type-n domains for both type-r and type-n modes Ag substrates.

Umezawa, Kenji; Nakanishi, Shigemitsu; Yoshimura, Masamichi; Ojima, Kaoru; Ueda, Kazuyuki; Gibson, Walter M.

2001-01-01

81

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

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

82

Ag 3Ni 2O 4A new stage-2 intercalation compound of 2H-AgNiO 2 and physical properties of 2H-AgNiO 2 above ambient temperature  

NASA Astrophysics Data System (ADS)

Ag 3Ni 2O 4 was obtained as single crystals from a mixture of 2H-AgNiO 2 and Ag 2O in oxygen high-pressure autoclaves ( P6 3/ mmc (no. 194), a=2.9331(6), c=28.313(9) , Z=2). It may be regarded as a stage-2 intercalation compound of the host 2H-AgNiO 2 and is the first staging compound constituted of alternating subvalent ?2Ag2+ and Ag + sheets, inserted between NiO 2- slabs. From a structural point of view, Ag 3Ni 2O 4 represents an intermediate between AgNiO 2 and the recently reported Ag 2NiO 2. The electronic structures of 2H-AgNiO 2 and Ag 3Ni 2O 4 have been investigated based on DFT band structure calculations. The high-temperature characteristics of the starting material 2H-AgNiO 2 were investigated. The inverse magnetic susceptibility, electrical resistivity and differential scanning calorimetry (DSC) show a phase transition in the temperature range of T=320-365 K.

Srgel, Timo; Jansen, Martin

2007-01-01

83

Temperature Dependent Effects During Ag Deposition on Cu(110).  

National Technical Information Service (NTIS)

The composition, structure, and morphology of ultrathin films grown by Ag deposition on Cu(110) were monitored as a function of temperature using low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and medium energy ion scattering (...

T. N. Taylor, R. E. Muenchausen, M. A. Hoffbauer, A. W. Denier van der Gon, J. F. van der Veen

1989-01-01

84

Wetting interaction between Sn-Zn-Ag solders and Cu  

Microsoft Academic Search

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

Kwang-Lung Lin; Chia-Ling Shih

2003-01-01

85

Formation of Thermally Stable AgCu-Based Reflectors by a Two Step Alloy Method for Vertical Light-Emitting Diodes  

NASA Astrophysics Data System (ADS)

Two-step alloyed indium-tin-oxide (ITO)/Ni/AgCu/Pt reflectors for high-performance GaN-based vertical light-emitting diodes (VLEDs) were investigated. The ITO layer was first annealed at 650 C for 1 min in air to make an Ohmic contact and then the Ni/AgCu/Pt reflectors were deposited and subsequently annealed at 400 C for 1 min in air to improve their reflectance and mechanical adhesion with the ITO layer. It was shown that the reflectance of the ITO/Ni/AgCu/Pt reflectors at 460 nm was slightly increased from 82 to 87% after two-step annealing. Based on the secondary ion mass spectrometry depth profiles, this improvement was attributed to the formation of a transparent Ni-oxide and the existence of Cu atoms near ITO/AgCu/Pt interface regions suppressing the inter and out-diffusion of Ag. The VLEDs fabricated with the ITO/Ni/AgCu/Pt reflectors showed an approximately 4.4% higher output power and much better current-voltage characteristics than those with the Ag-based reflectors.

Jeong, Tak; Kim, Seung Hwan; Lee, Sang Hern; Jeong, Seong Hoon; Lee, Seung Jae; Ju, Jin Woo; Baek, Jong Hyeob; Lee, June Key

2010-11-01

86

Effect of Cu-substitution on the conductivity of Ag-rich AgICuI solid solutions  

Microsoft Academic Search

The ionic conductivity of the silver rich solid solutions Ag1?xCuxI (0AgI, two conducting regions (above and below Tc) are found in these solid solutions also. Despite the large size difference in the ionic radii of Ag+ and Cu+

P. S Kumar; P Balaya; P. S Goyal; C. S Sunandana

2003-01-01

87

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

NASA Astrophysics Data System (ADS)

New, reinforced {1 1 0} <1 1 0> textured Ag/Ni-alloys composite ribbons were developed as possible substrates for coated conductors without any buffer layer. The texture quality and tensile strength were investigated. A new technique to bond the Ag and Ni or alloy layers through a Cu foil was presented. The Ag/Ni-alloys composite ribbons were fabricated by choosing proper sintering processing to bond the different layers followed by cold rolling and recrystallization. A thin Cu foil was intercalated between the initial Ag and Ni or alloy pieces to get a tough bond. A unique and stable {1 1 0} <1 1 0> annealing texture was obtained in 300 ?m thick Ag/Ni composite ribbon after annealing. X-ray ODF analysis and EBSD measurements in the top Ag layer showed distribution of misorientation angles around 10-15. A {1 1 0} <1 1 0> texture was also found in ribbons as thin as 50 ?m, which cannot be obtained with pure Ag ribbons. A pronounced reduction of Ag amount was obtained in 60 ?m thick Ag/NiCrV ribbons, with a textured Ag top layer being as thin as 7 ?m. The amount of Ag was decreased by 75% compared to pure Ag ribbons of the same thickness. A strong enhancement of the mechanical properties was observed. The yield strength ?0.2 at 77 K was 220 MPa for Ag/NiCrV ribbons, i.e. considerably higher than the 30 MPa for pure Ag ribbons.

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

2002-08-01

88

Communication: Kinetics of chemical ordering in Ag-Au and Ag-Ni nanoalloys  

NASA Astrophysics Data System (ADS)

The energy landscape and kinetics of medium-sized Ag-Au and Ag-Ni nanoalloy particles are explored via a discrete path sampling approach, focusing on rearrangements connecting regions differing in chemical order. The highly miscible Ag27Au28 supports a large number of nearly degenerate icosahedral homotops. The transformation from reverse core-shell to core-shell involves large displacements away from the icosahedron through elementary steps corresponding to surface diffusion and vacancy formation. The immiscible Ag42Ni13 naturally forms an asymmetric core-shell structure, and about 10 eV is required to extrude the nickel core to the surface. The corresponding transformation occurs via a long and smooth sequence of surface displacements. For both systems the rearrangement kinetics exhibit Arrhenius behavior. These results are discussed in the light of experimental observations.

Calvo, F.; Fortunelli, A.; Negreiros, F.; Wales, D. J.

2013-09-01

89

Electro-Catalytic Oxidation of Methanol on a NiCu Alloy in Alkaline Medium  

Microsoft Academic Search

The electro-catalytic oxidation of methanol on a NiCu alloy (NCA) with atomic ratio of 60\\/40 having previously undergone 50 potential sweep cycles in the range 0600mV vs. (Ag\\/AgCl) in 1m NaOH was studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS). The electro-oxidation was observed as large anodic peaks both in the anodic and early stages of the

M. Jafarian; R. B. Moghaddam; M. G. Mahjani; F. Gobal

2006-01-01

90

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

NASA Astrophysics Data System (ADS)

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

Zhu, Lu-Shan; Zhao, Shi-Jin

2014-06-01

91

Effects of intermetallic compounds on properties of SnAgCu lead-free soldered joints  

Microsoft Academic Search

The effects of alloy composition on microstructural, especially the formation of large intermetallic compounds, and mechanical properties of various SnAgCu solder joints were investigated. The range of AgCu content of SnAgCu alloys was from 3.0 wt.%Ag0.5 wt.%Cu to 3.9Ag0.7 wt.%Cu. The high Ag content alloys exhibit the formation of large Ag3Sn platelets especially at the solderreaction layer interfaces, regardless of

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

2003-01-01

92

Infrared absorption of Ag and Cu-photodoped chalcogenide films  

Microsoft Academic Search

Infrared reflectance and transmittance spectra of chalcogenide glass layers (As2S3, GeS2, GeSe2), non-doped and photodoped by Ag and Cu, were measured. The spectra were analyzed in terms of a molecular model for optic-mode vibrational frequencies. With Ag photodoping of As2S3 the main band (312 cm?1) shifts to higher frequencies. The area under the ??2(?) contour is unchanged (?2-imaginary part of

A. I. Stetsun; I. Z. Indutnyi; V. G. Kravets

1996-01-01

93

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

94

Pb-free Sn-Ag-Cu ternary eutectic solder  

DOEpatents

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

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

1996-06-18

95

Pb-free Sn-Ag-Cu ternary eutectic solder  

DOEpatents

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

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

96

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

97

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

98

Photoconductive properties of organic-inorganic Ag/p-CuPc/n-GaAs/Ag cell  

NASA Astrophysics Data System (ADS)

A thin film of copper phthalocyanine (CuPc), a p-type semiconductor, was deposited by thermal evaporation in vacuum on an n-type gallium arsenide (GaAs) single-crystal semiconductor substrate. Then semi-transparent Ag thin film was deposited onto the CuPc film also by thermal evaporation to fabricate the Ag/p-CuPc/n-GaAs/Ag cell. Photoconduction of the cell was measured in photoresistive and photodiode modes of operation. It was observed that with an increase in illumination, the photoresistance decreased in reverse bias while it increased in forward bias. The photocurrent was increased in reverse bias operation. In forward bias operation with an increase in illumination, the photocurrent showed a different behavior depending on the voltage applied.

Sanginovich Karimov, Khasan; Tariq Saeed, Muhammad; Khalid, Fazal Ahmad; Mirzoevna Karieva, Zioda

2011-07-01

99

Structures and stability of Ag clusters on Ag(1 1 1) and Ni(1 1 1) surfaces  

NASA Astrophysics Data System (ADS)

The structures of the lowest total energy for small =?iN Ei with Ei consisting of two parts, i.e., an embedding energy (which is obtained by considering the ith atom as an impurity embedded into the host provided by the rest of the atoms) and a pair-potential interaction with all other atoms. Accordingly, Ei=Fi(?ih)+{1}/{2}?j ? i ?ij(rij), where ?ih is the local electron density at site i,Fi is the embedding energy, and ?ij is a short-ranged repulsive potential between atoms i and j separated by distance rij. The local density at site i is assumed being a superposition of atomic electron densities, ?ih=?j(?i) ?ia(rij), where ?ia(rij) is the spherically averaged atomic electron density provided by atom j at the distance rij. For homoatomic systems, the values of the parameters entering the model are determined by fitting to experimental information on the extended systems (crystals, surfaces, etc.). As in Ref. [17] the A-B/B-A heterointeractions can be approximated in the EAM by the geometric mean of the pair interaction for the individual species, ?AB(r)=?{?AA(r)?BB(r)}. Daw, Baskes and Foiles determined the embedding functions for the Ag-Ni system empirically by fitting to experimental data for the bulk sublimation energy, the elastic constant, and the heat of solution of binary alloys [17]. Finally, ?ia,Fi and ?ij are available in numerical form for Ni, Cu and Ag [18]. The validity of the embedding functions for the Ag-Ni system has been tested by computing a wide range of properties including the segregation energy of substitutional impurities to the (1 0 0) surface [17]. The EAM has been successfully applied to many bulk and low-symmetric problems in transition metals such as defects, surface structures, and segregation [19]. Furthermore, in our previous studies [20-23] we have found that this approach provides accurate information on pure nickel and silver clusters, which is our main reason for choosing this potential for studying the structures of Ag clusters on Ag(1 1 1) and Ni(1 1 1) surfaces.

Hristova, Elisaveta; Grigoryan, Valeri G.; Springborg, Michael

100

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

Microsoft Academic Search

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

Min Pei; Jianmin Qu

2006-01-01

101

Far-from-equilibrium Ag-Cu thin-films on Cu(100) and Ag(100) substrates  

NASA Astrophysics Data System (ADS)

We study the dynamics of multilayer, heteroepitaxial deposition of mixed incoming fluxes of Ag and Cu atoms and the corresponding post-deposition relaxation on Ag (100) and Cu (100) substrates. To this end, we carried out extensive temperature accelerated dynamics (TAD) simulations at different substrate temperatures to characterize the morphology of the resulting films. Depending on the flux of impinging atoms, the number of layers, and the substrate temperature, the system can exhibit kinetically trapped, far-from-equilibrium configurations. Complex multi-adatom moves, not usually accounted for in regular Monte Carlo simulations, have a non-trivial relevance in the dynamics.

Cadilhe, Antonio; Araujo, Nuno A. M.; Voter, A. F.

2008-03-01

102

Improvement of wettability and drop impact reliability by Al addition in SnAgCu solder  

Microsoft Academic Search

SnAgCu solder is most popular solder composition system in the package industry. Therefore, SnAgCu solder has been studied by many researchers to improve its properties. In this study, we ran tests to verify the effect of Al additive metal in SnAgCu solder in term of wettability and drop impact reliability. The test solder compositions were Sn1.0Ag0.5Cu solder (Ref. solder) and

Y. W. Lee; I. H. Kim; E. S. Kim; J. H. Lee; J. T. Moon

2010-01-01

103

Giant magnetoresistance and magnetic properties of electrodeposited NiCoCu\\/Cu multilayers  

Microsoft Academic Search

The room-temperature magnetoresistance (MR) and magnetization characteristics were investigated for electrodeposited NiCoCu(3nm)\\/Cu(dCu) multilayers with dCu=1 and 2nm as a function of the ratio of Co to Ni in the magnetic layer. The maximum giant magnetoresistance (GMR) was obtained when the Co- and Ni-contents of the magnetic layer were approximately equal for dCu=1nm, whereas a significantly smaller GMR with no systematic

G. Nabiyouni; W. Schwarzacher; Z. Rolik; I. Bakonyi

2002-01-01

104

Microsegregation in rapidly solidified Ag-15 wt pct Cu alloys  

NASA Astrophysics Data System (ADS)

Spacings and composition profiles of cellular structures formed in Ag-15 wt pct. Cu alloys at growth rates between 0.1 and 18 cm/s are measured. Cells of the Ag-rich phase occur with intercellular regions composed of eutectic or the Cu-rich phase. At the highest rates the cell spacings exceed the characteristic diffusion length D/V (ratio of liquid diffusion coefficient to growth rate) by a factor of ten. The rate of increase of the average cell composition with growth velocity is larger than predicted by existing diffusion models of the cell tip. Increases in cell compositions beyond the Ag metastable solidus retrograde are accounted for quantitatively by the use of non-equilibrium interface conditions (solute trapping).

Boettinger, W. J.; Bendersky, L. A.; Coriell, S. R.; Schaefer, R. J.; Biancaniello, F. S.

1987-01-01

105

Properties of Ag-Cu-Pd dispersed phase amalgams: microstructures.  

PubMed

A 62% Ag-28% Cu-10% Pd lathe-cut alloy was successfully blended with conventional lathe-cut and spherical amalgam alloy. The resulting alloy showed little gamma 2 after one wk at 37 degrees C and a phase structure resembling commercial amalgam. In addition, the Cu3Pd phase present in the dispersant appears to participate in the amalgam reaction and, as a result, Pd may be found in the reaction zone around the dispersants in gamma 1 and/or Cu6Sn5 phases. PMID:6953117

Marshall, G W; Marshall, S J; Szurgot, K; Greener, E H

1982-06-01

106

Giant magnetoresistance and magnetic properties of electrodeposited Ni 81Cu 19\\/Cu multilayers  

Microsoft Academic Search

Magnetic measurements on electrodeposited NiCu\\/Cu multilayers indicated a continuous composition change at the magnetic-nonmagnetic interfaces. This is confirmed by the observation of a giant magnetoresistance (GMR) component due to a superparamagnetic region of these interfaces in the GMR curves for multilayers with dNiCu=3nm and dCu?0.75nm.

J. Tth; L. F. Kiss; E. Tth-Kdr; A. Dinia; V. Pierron-Bohnes; I. Bakonyi

1999-01-01

107

Development of texture and morphology in Cu-Ag thin nanocomposite films on Si  

NASA Astrophysics Data System (ADS)

Cu-Ag films were deposited in vacuum of 10-5-10-6 mbar onto freshly cleaned Si wafers. The composition of the films corresponded to Cu, Cu9Ag1, Cu4Ag6 and Ag. The films were investigated by X-ray diffraction and pole figures of <111> and <100> directions were recorded. TEM and XTEM were used to determine the morphological properties of the films. We found that Ag modifies the interaction of Cu with the Si substrate. Low amounts of Ag are enhancing the formation of the biaxial <100> texture of Cu. Larger amounts of Ag result in the formation of <111> wire texture of both Ag and Cu components.

Misjk, F.; Horvth, Z. E.; Barna, P. B.; Radnczi, G.

2008-03-01

108

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

PubMed

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

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

2012-04-01

109

A comparative study of the kinetics of interfacial reaction between eutectic solders and Cu\\/Ni\\/Pd metallization  

Microsoft Academic Search

A comparative study of the kinetics of interfacial reaction between the eutectic solders (Sn-3.5Ag, Sn-57Bi, and Sn-38Pb)\\u000a and electroplated Ni\\/Pd on Cu substrate (Cu\\/Ni\\/NiPd\\/Ni\\/Pd) was performed. The interfacial microstructure was characterized\\u000a by imaging and energy dispersive x-ray analysis in scanning electron microscope (SEM). For a Pd-layer thickness of less than\\u000a 75 nm, the presence or the absence of Pd-bearing intermetallic

G. Ghosh

2000-01-01

110

Effects of adding some elements on solderability of Sn0.7Ag0.5Cu solder  

Microsoft Academic Search

Some alloy elements were added to Sn-0.7Ag-0.5Cu solder, to fabricate two new solders, Sn-0.7Ag-0.5Cu-0.05Ni-XBi(X=0, 2.0, 2.5, 3.0, 3.5, 4.0 wt%) and Sn-0.7Ag-0.5Cu-XIn(X=0, 0.2, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8 and 2.0 wt %). The solderability tests of the two solder alloys have been conducted to study effect of bismuth, nickel and indium content on melting temperature and wettability of solder

Zhang Hongwu; Sun Fenglian; Liu Yang

2010-01-01

111

Graphene-induced unusual microstructural evolution in Ag plated Cu foils.  

PubMed

Graphene-induced abnormal grain growth of Cu with a grain size of more than 1 mm(2) was observed on Cu-Ag alloy foil, and this phenomenon occurred only with graphene synthesis and only on the Cu-Ag alloy among various types of Cu foils. PMID:24879370

Shin, Hae-A-Seul; Ryu, Jaechul; Cho, Seungmin; Hong, Byung Hee; Joo, Young-Chang

2014-06-12

112

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

Microsoft Academic Search

The microstructures and tensile properties of three typical SnAgCu alloys, Sn3.0wt.%Ag0.5wt.%Cu, Sn3.5wt.%Ag0.7wt.%Cu and Sn3.9wt.%Ag0.6wt.%Cu, prepared under three different cooling conditions were evaluated after casting. The microstructures of all rapidly cooled specimens consisted of the eutectic phase of ?-Sn with fine fibrous Ag3Sn dispersion surrounding primary ?-Sn grains. The slowly cooled Sn3.5Ag0.7Cu and Sn3.9Ag0.6Cu alloys exhibited additional large primary Ag3Sn platelets,

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

2002-01-01

113

Growth Mechanism of a Ternary (Cu,Ni)6Sn5 Compound at the Sn(Cu)/Ni(P) Interface  

NASA Astrophysics Data System (ADS)

The growth mechanism of an interfacial (Cu,Ni)6Sn5 compound at the Sn(Cu) solder/Ni(P) interface under thermal aging has been studied in this work. The activation energy for the formation of the (Cu,Ni)6Sn5 compound for cases of Sn-3Cu/Ni(P), Sn-1.8Cu/Ni(P), and Sn-0.7Cu/Ni(P) was calculated to be 28.02 kJ/mol, 28.64 kJ/mol, and 29.97 kJ/mol, respectively. The obtained activation energy for the growth of the (Cu,Ni)6Sn5 compound layer was found to be close to the activation energy for Cu diffusion in Sn (33.02 kJ/mol). Therefore, the controlling step for formation of the ternary (Cu,Ni)6Sn5 layer could be Cu diffusion in the Sn(Cu) solder matrix.

Huang, T. S.; Tseng, H. W.; Lu, C. T.; Hsiao, Y. H.; Chuang, Y. C.; Liu, C. Y.

2010-11-01

114

Giant magnetoresistance in self-supporting electrodeposited Ni?Cu\\/Cu multilayers  

Microsoft Academic Search

A sulphate bath was used to produce typically 5 ?m thick electrodeposited Ni?Cu\\/Cu multilayer foils with up to several thousand repeats. After removing the Ti substrate, the room-temperature magnetoresistance was studied as a function of the ferromagnetic Ni?Cu layer thickness. Giant magnetoresistance was observed, which peaked at about 2% for a Ni?Cu layer thicknesses around 2 to 3 nm.

I. Bakonyi; E. Tth-Kdr; T. Becsei; J. Tth; T. Tarnczi; . Czirki; I. Gercs; G. Nabiyouni; W. Schwarzacher

1996-01-01

115

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

116

Comparative Study of ENIG and ENEPIG as Surface Finishes for a Sn-Ag-Cu Solder Joint  

NASA Astrophysics Data System (ADS)

Interfacial reactions and joint reliability of Sn-3.0Ag-0.5Cu solder with two different surface finishes, electroless nickel-immersion gold (ENIG) and electroless nickel-electroless palladium-immersion gold (ENEPIG), were evaluated during a reflow process. We first compared the interfacial reactions of the two solder joints and also successfully revealed a connection between the interfacial reaction behavior and mechanical reliability. The Sn-Ag-Cu/ENIG joint exhibited a higher intermetallic compound (IMC) growth rate and a higher consumption rate of the Ni(P) layer than the Sn-Ag-Cu/ENEPIG joint. The presence of the Pd layer in the ENEPIG suppressed the growth of the interfacial IMC layer and the consumption of the Ni(P) layer, resulting in the superior interfacial stability of the solder joint. The shear test results show that the ENIG joint fractured along the interface, exhibiting indications of brittle failure possibly due to the brittle IMC layer. In contrast, the failure of the ENEPIG joint only went through the bulk solder, supporting the idea that the interface is mechanically reliable. The results from this study confirm that the Sn-Ag-Cu/ENEPIG solder joint is mechanically robust and, thus, the combination is a viable option for a Pb-free package system.

Yoon, Jeong-Won; Noh, Bo-In; Jung, Seung-Boo

2011-09-01

117

Photoemission from Ag, Cu, and CsI  

NASA Astrophysics Data System (ADS)

Photoemission characteristics of three different cathodes, CsI, Ag film, and Cu were investigated. CsI, upon irradiation by 213 nm, 10ps laser pulse yields a quantum efficiency of 4 percent at O.2 micro-J input energy. The saturation mechanism observed at higher input energies require further investigation. Ag film, upon irradiation by 630 nm, 300 fs laser emit prompt photoelectrons after absorbing 2 photons. There was no evidence of optical damage of the film up to 10(exp 11) W/sq cm. At low intensities, photoemission from Cu is a simple nu-e(exp -1) interaction, the nonlinearity of the process depending strongly on trace impurities. At higher intensities, there appears to be a change in the emission mechanism.

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

1992-06-01

118

Thermal stability of barrierless Cu-Ni-Sn films  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

119

Study of Undercooling and Recalescence During Solidification of Sn62.5Pb36.5Ag1 and Sn96.5Ag3Cu0.5 Solders in Real Electronic Joints  

NASA Astrophysics Data System (ADS)

Undercooling and recalescence were studied using the differential scanning calorimetry (DSC) method on real electronic systems. Two solder pastes, Sn62.5Pb36.5Ag1 and Sn96.5Ag3Cu0.5, were used for preparation of electronic joints. Various combinations of these solders and soldering pads with different surface finishes such as Cu, Cu-Ni-Au, Cu-Sn, and Cu-Sn99Cu1 were used. During melting of both pastes, the Sn and Sn99Cu1 surface finishes immediately dissolved in the solder and the Cu surface coating was exposed to the melt. Therefore, practically the same undercooling was found for the Cu, Cu-Sn, and Cu-Sn99Cu1 coatings. The lowest undercooling was found for the Cu-Ni-Au surface finish for both solder pastes. If two separated electronic joints were made on the sample, two separate peaks were found in the DSC signal during solidification. In the sample with only one joint, only one exothermic peak was found. These findings were observed for all paste/surface finish combinations. These data were analyzed, showing that this effect is a consequence of undercooling and recalescence: Latent heat released during solidification of the joint increases the surrounding temperature and influences all the processes taking place.

Rudajevov, A.; Duek, K.

2014-04-01

120

Photo-injection of hydrogen in Ag and Cu halides  

NASA Astrophysics Data System (ADS)

For the first time photo-initiated injection of hydrogen was carried out into Ag- and Cu-halides (AgCl, AgJ, Ag4RbI5, CuCl) -- the materials which are very important for investigations of the photographic process. To carry out the photoinjection of hydrogen into the halides a double-layer structure was used. Onto a quartz substrate two thin films were evaporated one after the other: the first one -- a silver or copper halide film, and the second one -- an amorphous WO3 thin film. The film double-layer structure was illuminated by UV-light from the side of the WO3 film. The role of a hydrogen source was played by specially selected organic molecules previously adsorbed on the WO3 surface. Hydrogen atoms detached from the adsorbed molecules under light illumination, diffused first into the WO3 film and then, afterwards, migrated into the halide layer. Hence, illumination of the halide surface was accompanied by injection of hydrogen atoms released from the organic molecules adsorbed on the WO3 surface.

Gavrilyuk, Alexander

1997-02-01

121

Formation of metal nanoparticles in silica by the sequential implantation of Ag and Cu  

NASA Astrophysics Data System (ADS)

Spherical-like nanoparticles have been formed by sequentially ion-implanting Ag/Cu into silica glasses. During sequential Ag/Cu ion implantation, the diameter of Cu nanoparticles is increased and the average Ag nanoparticle diameter is decreased with increasing Cu ion dose. The evolution of nanoparticles is characterized by grazing incidence X-ray diffraction, extended X-ray absorption fine structure spectroscopy and transmission electron microscopy. Nanovoids in the nanoparticles are formed by sequential ion implantation.

Xiao, X. H.; Guo, L. P.; Ren, F.; Wang, J. B.; Fu, D. J.; Chen, D. L.; Wu, Z. Y.; Jia, Q. J.; Liu, C.; Jiang, C. Z.

2007-11-01

122

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

SciTech Connect

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

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

2010-04-15

123

Optoelectronic properties of sputter-deposited Cu 2O-Ag-Cu 2O treated with rapid thermal annealing  

Microsoft Academic Search

Cu2O and two types of Cu2OAgCu2O (CAC) multilayered thin films were deposited on glass substrates using DC-magnetron sputtering. For CAC films, the mass thickness of Ag layer was controlled at 3nm. After deposition, some of these films were annealed using a rapid thermal annealing (RTA) system at 650C, in order to create embedded Ag particles. AC films were used to

P. W. Kuo; J. H. Hsieh; W. T. Wu; C. H. Wu

2009-01-01

124

Comparative study of corrosion and structural properties of FeCoNiCu alloys and FeCoNiCu/Cu multilayers  

NASA Astrophysics Data System (ADS)

FeCoNiCu alloy is a soft magnetic alloy with very low HC and high Bs. In this study, experiments were done to deposit FeCoNiCu alloys by DC as well as pulse current technique and FeCoNiCu/Cu multilayers from a single electrolyte and effort has been made to compare their variation in composition, corrosion, and structural properties.

Rajak, Syed; Srivastava, C.; Bidaye, A. C.; Ghosh, S. K.

2014-04-01

125

Effect of transition metal (Fe, Cu, Ni, Rh)-doped small silver chains on optics of plasmon resonances  

NASA Astrophysics Data System (ADS)

Doping can control and tune the optical properties of current nanoalloys. In this study, the optical generation of plasmon resonance mode in pure-Ag and transition metal (Fe, Cu, Ni, Rh) single-doped Ag chains is investigated using time-dependent density functional theory. Results show that the redshift of plasmon energy appears and intensity of longitudinal mode enhances with increasing the number of Ag atoms in pure silver chains. The Ag chains doped with transition metal (TM) atom create an additional peak with a local plasmon resonance mode which is related to charge redistribution in the chain around TM atom.

Li, Weiyin; Chen, Fuyi

2013-11-01

126

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

SciTech Connect

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

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

2007-01-08

127

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

128

A novel multifunctional NiTi/Ag hierarchical composite  

PubMed Central

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

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

129

A novel multifunctional NiTi/Ag hierarchical composite.  

PubMed

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

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

2014-01-01

130

Increase of the thermoelectric power factor in Cu/Bi/Cu,Ni/Bi/Ni, and Cu/Bi/Ni composite materials  

NASA Astrophysics Data System (ADS)

The resultant thermoelectric power factors P of three types of Cu/Bi/Cu,Ni/Bi/Ni, and Cu/Bi/Ni composite materials welded with Bi were measured at 298 K as a function of relative thickness of Bi and compared with P values calculated by treating these devices as an electrical and thermal circuit. It was first demonstrated experimentally that the observed P values of composite devices have a local maximum at an optimum volume fraction (corresponding to the thickness) of Bi, as predicted theoretically. The maximum P values of composite materials were several times higher than those of pure Ni and Bi and were about 100 times larger than that of pure Cu. The dependence of P on the thickness of Bi was found to be explained roughly by introducing the modified thermal conductivity and an enhancement factor in the Seebeck coefficient to our simple model in which a device was treated as an electrical and thermal circuit.

Odahara, Hirotaka; Yamashita, Osamu; Satou, Kouji; Tomiyoshi, Shoichi; Tani, Jun-Ichi; Kido, Hiroyasu

2005-05-01

131

The structure of NiTiCu shape memory alloys  

Microsoft Academic Search

A combined electron microscopy and X-ray diffraction study has been made of NiTiCu shape memory alloys where Cu is substituted\\u000a for Ni in binary? NiTi. It is shown that the high temperature phase with the CsCl structure is retained for copper contents of up to 30 wt\\u000a pct, and that this phase transforms on cooling to a monoclinic martensite with

R. H. Bricknell; K. N. Melton; O. Mercier

1979-01-01

132

The structure of NiTiCu shape memory alloys  

Microsoft Academic Search

A combined electron microscopy and X-ray diffraction study has been made of NiTiCu shape memory alloys where Cu is substituted for Ni in binary beta NiTi. It is shown that the high temperature phase with the CsCl structure is retained for copper contents of up to 30 wt pct, and that this phase transforms on cooling to a monoclinic martensite

R. H. Bricknell; K. N. Melton; O. Mercier

1979-01-01

133

Failure Morphology After Drop Impact Test of Ball Grid Array (BGA) Package With Lead-Free Sn3.8Ag0.7Cu and Eutectic SnPb Solders  

Microsoft Academic Search

High strain-rate drop impact tests were performed on ball grid array (BGA) packages with solder compositions of (in wt%) Sn-3.8Ag-0.7Cu (SnAgCu) and eutectic Sn-37Pb (SnPb). Solder balls were joined to the metallizations of plated Ni on the device side and plated Cu on the board side. The BGA packages were tested at 1500 g within 0.5 ms, resulting in an

Jin-Wook Jang; Ananda P. De Silva; James E. Drye; Steve L. Post; Norman L. Owens; Jong-Kai Lin; Darrel R. Frear

2007-01-01

134

Microstructure development in Al-Cu-Ag-Mg quaternary alloy  

NASA Astrophysics Data System (ADS)

The solidification behaviour of multi-component and multi-phase systems has been largely investigated in binary and ternary alloys. In the present study, a quaternary model system is proposed based on the well known Al-Cu-Ag and Al-Cu-Mg ternary eutectic alloys. The quaternary eutectic composition and temperature were determined by EDS (Energy Dispersive Spectrometry) and DSC (Differential Scanning Calorimetry) analysis, respectively. The microstructure was then characterised by SEM (Scanning Electron Microscope). In the DSC experiments, two types of quaternary eutectics were determined according to their phase composition. For each type of eutectic, various microstructures were observed, which result in different eutectic compositions. Only one of the determined eutectic compositions was further studied by the controlled growth technique in a vertical Bridgeman type furnace. In the initial part of the directionally solidified sample, competing growth between two-phase dendrites and three-phase eutectics was obtained, which was later transformed to competing growth between three-phase and four-phase eutectics. Moreover, silver enrichment was measured at the solidification front, which is possibly caused by Ag sedimentation due to gravity and Ag rejection from dendritic and three-phase eutectic growth, and its accumulation at the solidification front.

Zhou, Bin; Froyen, L.

2012-01-01

135

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

136

Origin of Novel Diffusions of Cu and Ag in Semiconductors: The Case of CdTe  

NASA Astrophysics Data System (ADS)

It is well known in experimental studies that Cu is usually a fast diffuser in semiconductors. In some semiconductors (e.g., CdTe), Ag is also a fast diffuser. The diffusion plays an important role in many applications when Cu (Ag) is employed to tune the semiconductors electrical or optical properties. However, the origin of why Cu (Ag) shows different diffusion behavior compared to group-IA elements is still unclear. Using first-principles method, we compare the diffusion behaviors between Cu (Ag) and group-IA elements in CdTe, and find that the novel diffusion is due to the strong coupling between Cu (Ag) d levels and unoccupied host s levels. This coupling alters the stable doping site, diffusion pathway, and diffusion energy curve from those of group-IA elements, which have no active d levels, thus making the Cu (Ag) diffusion faster in many semiconductors.

Ma, Jie; Wei, Su-Huai

2013-06-01

137

Graphene-induced unusual microstructural evolution in Ag plated Cu foils  

NASA Astrophysics Data System (ADS)

Graphene-induced abnormal grain growth of Cu with a grain size of more than 1 mm2 was observed on Cu-Ag alloy foil, and this phenomenon occurred only with graphene synthesis and only on the Cu-Ag alloy among various types of Cu foils.Graphene-induced abnormal grain growth of Cu with a grain size of more than 1 mm2 was observed on Cu-Ag alloy foil, and this phenomenon occurred only with graphene synthesis and only on the Cu-Ag alloy among various types of Cu foils. Electronic supplementary information (ESI) available: A detailed texture analysis of Cu EBSD orientation maps and grain size calculation. See DOI: 10.1039/c4nr01163e

Shin, Hae-A.-Seul; Ryu, Jaechul; Cho, Seungmin; Hong, Byung Hee; Joo, Young-Chang

2014-06-01

138

Mechanochemical synthesis, thermal stability and selective electrochemical dissolution of CuAg solid solutions  

Microsoft Academic Search

Supersaturated nanocrystalline (1619nm) Cu50Ag50 and Cu70Ag30 solid solutions are synthesized by high-energy ball milling. Varying the milling time fcc solid solutions with different lattice parameters are obtained. Thus an increase of the lattice constant that levels off after 20h of milling is registered for the Cu50Ag50 solid solution. At the same time broad overlapped exothermic effects in the temperature range

T. Spassov; L. Lyubenova; Y. Liu; S. Bliznakov; M. Spassova; N. Dimitrov

2009-01-01

139

Ag and Cu doping and their effects on the thermoelectric properties of ?-Zn4Sb3  

NASA Astrophysics Data System (ADS)

The measurements of electrical resistivity and Seebeck coefficients of Ag- and Cu-doped compounds ?-(Zn1-xMx)4Sb3 (M=Ag,Cu;x=0,0.0025,0.005,0.01) were carried out, and the results indicated that both their resistivity and Seebeck coefficients increase first ( x?0.0025 for Ag and x?0.005 for Cu) and then decrease obviously with further increase in their doping content. Correspondingly, hole concentration behaviors in the opposite way. In terms of the one vacancy-two interstitial Zn atom model: A11BCSb10 and two-vacancy-three-interstitial Zn atom model: A10BCDSb10 (here A is normal Zn atom and B, C, and D interstitial Zn atoms) proposed by Cargnoni [Chem. Eur. J. 10, 3861 (2004)]10.1002/chem.200400327, first-principles calculations were performed on the occupation options of Ag and Cu atoms in disordered ?-Zn4Sb3 . The results indicated that both Ag and Cu atoms occupy preferentially the Zn vacancies in normal sites. Subsequently, Ag and Cu atoms will substitute for interstitial atoms D (for Ag) and B (for Cu). The calculations also showed that as Ag and Cu atoms fill Zn vacancies they play the role of donors, leading to a decrease in hole concentration; while Ag and Cu atoms replace the interstitial atoms they act as acceptors resulting in an increase in hole concentration, which are in good agreement with the nonmonotonous change behavior in the transport properties and Hall carrier concentrations observed experimentally. In addition, calculations revealed that Cu instead of Ag can also fill the Zn vacancies with smaller volumes and Cu doping nearly always has lower formation energies than Ag, which could give a reasonable explanation for the higher solubility of Cu than that of Ag in ?-Zn4Sb3 .

Liu, Mian; Qin, Xiaoying; Liu, Changsong; Pan, Lin; Xin, Hongxing

2010-06-01

140

Large magnetocaloric effect, moment, and coercivity enhancement after coating Ni nanoparticles with Ag.  

PubMed

We observe a large magnetocaloric effect in monodisperse Ni and Ni(core)Ag(shell) nanoparticles in the superparamagnetic region. The organically passivated Ni nanospheres show a large magnetic entropy change of 0.9 J?kg(-1) ?K for a 3 T magnetic field change. In comparison to the surfactant-coated Ni nanoparticles, the Ni(core)Ag(shell) nanoparticles show an enhanced coercivity, magnetization, and magnetocaloric effect (1.3 kg?K for a 3 T magnetic field change). The coercivity at 10 K increases from 360 Oe for Ni nanoparticles to nearly 610 Oe for Ni(core)Ag(shell) particles. This large enhancement is attributed to the enhanced inter-particle interaction, which is mediated by the metallic shell, over the relatively weaker dipolar interaction in the surfactant-coated Ni nanoparticles, and to modification of the surface spin structure. PMID:24615843

Srinath, Sanyadanam; Poddar, Pankaj; Das, Raja; Sidhaye, Deepti; Prasad, Bhagavatula Lakshmi Vara; Gass, James; Srikanth, Hariharan

2014-06-01

141

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

SciTech Connect

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

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

2009-06-08

142

Structural, electronic and optical properties of 7-atom Ag-Cu nanoclusters from density functional theory  

NASA Astrophysics Data System (ADS)

The structures and electronic properties of 7-atom silver and copper bimetallic clusters are systematically investigated by density functional theory (DFT) in the theoretical frame of the generalised gradient approximation (GGA) exchange-correlation functional. Optical absorption, Raman spectra, as well as vibrational spectra are calculated by DFT/GGA and semi-core pseudopotentials. The lowest-energy stable motifs are primarily related to the quantity of Cu-Cu bonds and Ag-Cu bonds. The Ag5Cu2 2-I with D 5 h symmetry cluster is the lowest energy cluster in the family of the 7-atom Ag-Cu nanoclusters, but has the lowest electronic stability. The Ag5Cu2 2-I, Ag4Cu3 3-I and Ag3Cu4 4-I clusters with mixed motifs indicate that silver and copper may be miscible on the nanoscale but not in bulk. Overall, with increasing Cu atoms, for the lowest energy nanoclusters, blue-shift of the maximum absorption peaks presents in the UV-Vis wavelength range, the intensities of the maximum peak of the Raman spectra weaken, the Cu atom(s) introduced make the vibrational spectra complex, and the intensities of the vibrational spectra strengthen. The calculated vibrational and Raman spectroscopy of 7-atom Ag-Cu clusters may be helpful in determining the size and structure of the experimental cluster.

Li, Weiyin; Chen, Fuyi

2014-04-01

143

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

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (5070nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83emu\\/g (NiZn) to 91emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in the frequency range

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

2009-01-01

144

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

Microsoft Academic Search

NiZn- and NiCuZn-ferrite nanoparticles (50-70 nm) with the chemical formula Ni0.5 Zn0.5Fe2O4 (NiZn) and Ni0.35Cu0.15Zn0.5Fe2O4 (NiCuZn) were synthesized by a combustion synthesis method. The nanocrystallite of these materials was characterized by structural and magnetic methods. Saturation magnetization increases from 83 emu\\/g (NiZn) to 91 emu\\/g (NiCuZn). Magnetic permeability and dielectric permittivity were measured on sintered samples (pellets and toroids) in

J. C. Aphesteguy; Abel Damiani; Dalmas Digiovanni; S. E. Jacobo

2009-01-01

145

Anelasticity of B19? martensitic phase in Ni Ti and Ni Ti Cu alloys  

Microsoft Academic Search

Anelastic properties of the B19? martensitic phase have been studied in two polycrystalline alloys: NiTi with nearly equiatomic composition and NiTiCu (about 49at.% Ti, 46at.% Ni, and 5at.% Cu). Internal friction, dynamic shear modulus and torsional strain at zero applied stress were measured in a forced torsion pendulum for strain amplitudes of 210?5 to 210?4, temperatures of 6300K, temperature change

K. Sapozhnikov; S. Golyandin; S. Kustov; R. Schaller; J. Van Humbeeck

2006-01-01

146

Single step synthesis and optical limiting properties of Ni-Ag and Fe-Ag bimetallic nanoparticles  

NASA Astrophysics Data System (ADS)

Magnetic nanoparticles have several applications in biology and medicine, and recently, their use for optical applications is gaining substantial attention. In this paper we report a single step solution based synthesis of Ni-Ag and Fe-Ag bimetallic nanoparticles using hydrazine hydrate as the reducing agent. Structural, plasmonic, and nonlinear optical properties of the prepared nanoparticles are investigated using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-Vis absorption spectroscopy and Z-scan. UV-Vis absorption studies reveal surface plasmon resonance (SPR) absorption at 400 nm which exhibits a small red shift with particle size due to scattering. XRD, EDS, HRTEM and SPR absorption confirm the presence of Ni-Ag and Fe-Ag nanoparticles. Nonlinear optical studies are carried out using the open aperture Z-scan technique employing 5 ns as well as 100 fs laser pulses. The nonlinearity is found to have contributions from absorption saturation, two-photon absorption, excited state absorption and induced thermal scattering of light. The effective nonlinear absorption in Ni-Ag and Fe-Ag nanoparticles is found to be higher than that of pristine Ag nanoparticles. The potential of these materials for optical limiting and photonic applications is discussed.

Sridharan, Kishore; Endo, Tamio; Cho, Sang-Geun; Kim, Jongryoul; Park, Tae Joo; Philip, Reji

2013-03-01

147

Effects of bulk Cu6Sn5 intermetallic compounds on the properties of Sn-Ag-Cu-Ce soldered joints  

Microsoft Academic Search

Purpose The purpose of this paper is to explore the formation and growth mechanism of bulk Cu6Sn5 intermetallic compounds, selecting Sn-Ag-Cu-Ce solders as specimens. Design\\/methodology\\/approach In order to further enhance the properties of SnAgCu solder, trace amount of rare earth Ce was selected as alloying addition into the alloy; in previous investigations, the enhancements include better wettability, physical

Liang Zhang; Song-bai Xue; Li-li Gao; Zhong Sheng; Wei Dai; Feng Ji; Huan Ye; Yan Chen; Sheng-lin Yu

2011-01-01

148

Thin-film interdiffusions in Cu\\/Pd, Cu\\/Pt, Cu\\/Ni, Cu\\/NiB, Cu\\/Co, Cu\\/Cr, Cu\\/Ti, and Cu\\/TiN bilayer films: Correlations of sheet resistance with Rutherford backscattering spectrometries  

Microsoft Academic Search

Interdiffusion in the Cu-based Cu\\/Pd, Cu\\/Pt, Cu\\/Ni, Cu\\/NiB, Cu\\/Co, Cu\\/Cr, Cu\\/Ti, and Cu\\/TiN bilayer films has been investigated for anneal temperatures ranging from 150 to 400 C in forming gas (N2-10%H2). The diffusion of Pd, Pt, and Ni into Cu has resulted in a significant increase in the sheet resistance of the film, which is correlated with the concentration profiles

D.-Y. Shih; C.-A. Chang; J. Paraszczak; S. Nunes; J. Cataldo

1991-01-01

149

Giant magnetoresistance of electrodeposited Cu-Co-Ni alloy films  

Microsoft Academic Search

Electrodeposition of CuCoNi alloys was performed in an acid-citrate medium. Nickel density parameter was varied in order to\\u000a analyse its influence on the magnetoresistance. The structure and giant magneto-resistance (GMR) effect of CuCoNi alloys have\\u000a been investigated. The maximum value for GMR ratio, at room temperature is 1% at a field of 12 kOe, and at 20 K is 2.1%

?. H. Karahan; . F. Bakkalo?lu; M. Bedir

2007-01-01

150

Giant magnetoresistance of electrodeposited Cu-Co-Ni alloy films  

Microsoft Academic Search

Electrodeposition of CuCoNi alloys was performed in an acid-citrate medium. Nickel density parameter was varied in order to analyse its influence on the magnetoresistance. The structure and giant magneto- resistance (GMR) effect of CuCoNi alloys have been investigated. The maximum value for GMR ratio, at room temperature is 1% at a field of 12 kOe, and at 20 K is

I. H. Karahan; . F. Bakkaloglu; M. Bedir

2007-01-01

151

Nucleation rates of Sn in undercooled Sn-Ag-Cu flip-chip solder joints  

NASA Astrophysics Data System (ADS)

The nucleation of Sn from the melt in commercial SnAgCu flip chip solder joints was monitored at a number of different temperatures. Nucleation rates were estimated from measurements of nucleation times for 440 solder balls after one reflow and were found to be well epitomized by the expression I = 2 109 exp[(-1.6 105)/(T (?T)2)] m-3 s-1, as per classical nucleation theory. After an additional reflow, the nucleation rates of the same 440 samples were observed to increase to I = 2 109 exp[(-8.9 104)/(T (?T)2)] m-3 s-1. Thus it was shown that the expressions of classical nucleation theory well characterize nucleation kinetics for this system. These changes in nucleation kinetics were correlated with continued dissolution of Al and Ni in to the SnAgCu melt. Such increases in nucleation rates meant increases in the average solidification temperatures of the solder balls after reflow. Variations in the Sn grain morphology of the solder joints were correlated with these changes in solidification temperature, with larger Sn grains (beach ball Sn grain morphology) observed at higher solidification temperatures.

Arfaei, B.; Benedict, M.; Cotts, E. J.

2013-11-01

152

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

NASA Technical Reports Server (NTRS)

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

Soria, F.; Poppa, H.

1980-01-01

153

Distal Magmatic-Hydrothermal Origin for the Camaqu Cu (Au-Ag) and Santa Maria Pb, Zn (Cu-Ag) Deposits, Southern Brazil  

Microsoft Academic Search

The Camaqu Cu (Au, Ag) and Santa Maria Pb-Zn (Cu, Ag) deposits are the largest base-metal deposits discovered so far in the sedimentary clastic sequences of the Neoproterozoic-age Camaqu Basin. The origin of the Camaqu-Santa Maria deposits has been the centre of dispute, with three alternative genetic hypotheses proposed: a syngenetic model, a diagenetic model, and a magmatic hydrothermal model.

M. V. D. Remus; L. A. Hartmann; N. J. McNaughton; D. I. Groves; J. L. Reischl

2000-01-01

154

Atomic diffusion in liquid Ni, NiP, PdNiP, and PdNiCuP alloys  

SciTech Connect

We investigated the self-diffusion of Ni in liquid Ni, Ni{sub 80}P{sub 20}, Pd{sub 40}Ni{sub 40}P{sub 20}, and Pd{sub 43}Ni{sub 10}Cu{sub 27}P{sub 20} at temperatures up to 1795 K with incoherent, quasielastic neutron scattering. Values of measured self-diffusion coefficients vary over the accessible temperature ranges as a function of composition only within 10%. Although mixing has a drastic effect on the liquidus temperature and the undercooling capabilities, a relation between these properties and the atomic diffusion in the liquid is not observed. Apparently, diffusive motion is governed by the packing fraction of the atoms, that is very similar in these dense liquids.

Chathoth, S. Mavila; Meyer, A.; Koza, M.M.; Juranyi, F. [Physik Department E13, Technische Universitaet Muenchen, 85747 Garching (Germany); Institut Laue-Langevin, 38042 Grenoble (France); Physikalische Chemie, Universitaet des Saarlandes, 66123 Saarbruecken (Germany); Paul Scherrer Institut, 5232 Villigen (Switzerland)

2004-11-22

155

Improved surface morphology and texture of Ag films on indium tin oxide via Cu additions  

Microsoft Academic Search

The surface and texture properties of Ag(Cu) alloy thin films on indium tin oxide (ITO) has been investigated and compared to pure Ag thin films on ITO. Atomic force microscopy (AFM) and x-ray diffraction results of annealed films show differences in the evolution of surface morphology and texture with annealing. The presence of Cu atoms in the silver alters the

H. Han; Yeongseok Zoo; J. W. Mayer; T. L. Alford

2007-01-01

156

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

Microsoft Academic Search

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

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

2000-01-01

157

X-ray absorption spectroscopy study of the chemical ordering in UCu5-xMx (M = Ni, Ag) compounds  

NASA Astrophysics Data System (ADS)

This work reports the x-ray absorption spectroscopy study of the chemical ordering in UCu5-xMx (M = Ni, Ag) compounds. The comparison between the experimental Cu K-edge XANES spectra and theoretical computations based on multiple-scattering theory shows that standard single-channel calculations are capable of reproducing the experimental spectra. On this subject, an extensive discussion is presented concerning the role of both the cluster size and the final state potential in obtaining a good reproduction of the experimental XANES spectra of these UCu5-based alloys. The agreement between the theoretical and experimental spectra points to the existence of crystallographic disorder in both UCu4Ag and UCu4Ni systems. Possessing the distinct low temperature electrical, magnetic and thermal properties exhibited by UCu4Ni, our results suggest that Ni doping must induce dramatic changes in the electronic structure, as confirmed by the thermopower measurements. These results point to the imbalance between the RKKY and Kondo interactions as the source of the NFL behaviour observed in UCu4Ni, thus supporting an interpretation of the NFL behaviour in terms of the Griffiths phase model.

Chaboy, J.; Boada, R.; Dur, O. J.; Lpez de la Torre, M. A.

2008-10-01

158

Structure and Phase Separation in Ultrathin Ag/Cu Amorphous Alloy System  

NASA Astrophysics Data System (ADS)

The structure of disordered metallic alloys is an important but unsolved problem. Previous studies on Ag-Cu system showed that relatively homogeneous solid solutions formed at liquid nitrogen temperature decompose into separate phases or evolve into crystalline structure at a higher temperature. In this research project, we prepared ultra-thin Ag-Cu films on amorphous carbon support by HV magnetron sputtering with both targets. With high energy Ag and Cu atoms bombarding on the carbon substrate, they are forced to form amorphous alloy or nano-crystalline thin film at room temperature. We have investigated the structure of ultra-thin Ag-Cu films by examining their pair distribution function (PDF) using electron diffraction and observed phase separation process directly in STEM images. In the STEM Z-contrast images, since the contrast is directly related to the atomic number (Z) of the components, we can see clearly the phase separation process. Experimental results show that the sample morphology evolutions are different in samples with different thickness, and the phase separation depends on various Ag/Cu atomic ratios. In Ag50Cu50 sample, early stage phase separation is associated with increasing Cu crystallite size, indicates that Cu diffuse out of Ag-Cu solid solution phase.

Chen, Hao

2005-03-01

159

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

PubMed

Corrosion of a multi-phase Ag-Pd-Cu-Au-based commercial dental casting alloy and a Cu-Pd-rich and Ag-rich single-phase alloy was studied by open-circuit potential measurements, atomic absorption spectrometry, and electron spectroscopy. The alloys were immersed in an artificial saliva solution for 24 hr while the open-circuit potentials of the alloys were measured. The potentials were found to stabilize at certain levels after a steep rise during the first hours of the experiment. Cu was found to dissolve considerably from the Cu-Pd-rich alloy, with simultaneous enrichment of Pd in the surface layer of the alloy. Ag dissolved slightly from the Ag-rich alloy, but both Cu and Ag were found to dissolve from the multi-phase alloy. Neither Pd nor Au dissolved from any of the alloys studied. PMID:3458739

Niemi, L; Minni, E; Ivaska, A

1986-06-01

160

High temperature XRD studies of nanoscale AgI CuI solid solutions  

NASA Astrophysics Data System (ADS)

A preliminary high-temperature X-ray diffraction (HT-XRD) study of the nanometer-sized solid solution phases in the AgI CuI system is reported through an extended range of temperatures (300 723K) covering phase transitions in both AgI and CuI. A major feature of this work is the observation of the coexistence of the zincblende and base-centred cubic phases of AgI over an extended range of temperatures the temperature width being a function of Cu content in the binary. The lattice parameters derived from HT-XRD data reflect systematics of phase transitions with progressive Cu substitution of AgI. The present results are discussed together with our earlier ionic conductivity, dilatometry and DSC data which have helped deduce phase diagrams for both the Ag-rich and Cu-rich regions of the binary.

Senthil Kumar, P.; Tyagi, A. K.; Sunandana, C. S.

2006-08-01

161

Determination of Anand parameters for SnAgCuCe solder  

NASA Astrophysics Data System (ADS)

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.

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

2009-10-01

162

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

SciTech Connect

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

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

2011-09-15

163

Structure and solid solution properties ofCuAg nanoalloys  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

164

Structure and solid solution properties ofCu-Ag nanoalloys.  

PubMed

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

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

2014-07-01

165

Ag{sub 3}Ni{sub 2}O{sub 4}-A new stage-2 intercalation compound of 2H-AgNiO{sub 2} and physical properties of 2H-AgNiO{sub 2} above ambient temperature  

SciTech Connect

Ag{sub 3}Ni{sub 2}O{sub 4} was obtained as single crystals from a mixture of 2H-AgNiO{sub 2} and Ag{sub 2}O in oxygen high-pressure autoclaves (P6{sub 3}/mmc (no. 194), a=2.9331(6), c=28.313(9)A, Z=2). It may be regarded as a stage-2 intercalation compound of the host 2H-AgNiO{sub 2} and is the first staging compound constituted of alternating subvalent {approx}2Ag{sub 2}{sup +} and Ag{sup +} sheets, inserted between NiO{sub 2}{sup -} slabs. From a structural point of view, Ag{sub 3}Ni{sub 2}O{sub 4} represents an intermediate between AgNiO{sub 2} and the recently reported Ag{sub 2}NiO{sub 2}. The electronic structures of 2H-AgNiO{sub 2} and Ag{sub 3}Ni{sub 2}O{sub 4} have been investigated based on DFT band structure calculations. The high-temperature characteristics of the starting material 2H-AgNiO{sub 2} were investigated. The inverse magnetic susceptibility, electrical resistivity and differential scanning calorimetry (DSC) show a phase transition in the temperature range of T=320-365K.

Soergel, Timo [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, 70569 Stuttgart (Germany); Jansen, Martin [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstr. 1, 70569 Stuttgart (Germany)], E-mail: m.jansen@fkf.mpg.de

2007-01-15

166

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

Microsoft Academic Search

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

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

2009-01-01

167

Modified Ni-Cu catalysts for ethanol steam reforming  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

168

Development of Cu-Ag alloys conductor for high field magnet  

Microsoft Academic Search

Highly conductive materials with high strength have been required for the development of high field magnets such as the pulsed magnet. Compared with Cu-Al2O3, Cu-Be, Cu-Cr and Cu-Nb alloys, Cu-Ag alloys are very useful because of easiness in melting and casting. In addition, the alloys exhibit high strength, high conductivity and uniform characteristics by the proper combination of cold-working and

Tooru Hirota; Akira Imai; Tomoyuki Kumano; Masamitsu Ichihara; Yoshikazu Sakai; Kiyoshi Inoue; Hiroshi Maeda

1994-01-01

169

Improvement of anti-oxidation capability and tribological property of arc ion plated Ag film by alloying with Cu  

NASA Astrophysics Data System (ADS)

Ag-Cu alloy film was deposited by arc ion plating (AIP). Atomic oxygen (AO) irradiation experiments were conducted using a ground AO simulation facility. The structure, morphology, composition and tribological property of the Ag-Cu alloy film before and after AO irradiation were investigated and compared with Ag film using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), X-ray photoelectron spectroscope (XPS) and ball-on-disk tribometer, respectively. In depth XPS analysis clearly shows that the affected thickness of Ag-Cu alloy film was greatly reduced and the oxidation product was mainly Ag 2O, but AgO and Ag 2O in case of pure Ag film. As a result, the Ag-Cu alloy film exhibited better AO resistant behaviors, and showed a stable friction and low wear after the AO irradiation. The AO resistant behaviors of the Ag-Cu alloy film were discussed in terms of the film microstructure.

Gao, Xiaoming; Sun, Jiayi; Hu, Ming; Weng, Lijun; Zhou, Feng; Liu, Weimin

2011-06-01

170

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

SciTech Connect

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

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

2011-12-15

171

Texture and surface morphology evolution of Ag(Cu) layers on indium tin oxide thin films  

NASA Astrophysics Data System (ADS)

The evolution of surface morphology and (1 1 1) texture of Ag metallization on indium tin oxide (ITO) were improved by Cu additions to the Ag layer. X-ray diffraction (XRD) and atomic force microscopy (AFM) were used to characterize the surface morphology and the texture evolution of Ag(Cu). These results were compared with those obtained from pure Ag on ITO. After thermal annealing, AFM and XRD data show different modes of surface morphology evolution and crystallographic texture evolution with thermal annealing temperature. Differences in surface and texture between Ag(Cu) and Ag films were explained in terms of surface energy and grain boundary grooving as a function of annealing temperatures. The addition of Cu atoms into the silver thin films influenced the grain growth by modification of surface energy and/or adatom mobility. Rutherford backscattering spectrometry (RBS) and electrical resistivity measurements showed good thermal stability of Ag(Cu) in vacuum at temperatures varying from 300 to 600 C for 1 h. AFM, RBS and electrical resistivity data also confirmed the absence of agglomeration occurrence during the annealing process. The enhanced texture and thermal stability indicated that Ag(Cu) alloy films constitute potential contact materials for MOSFET for better electromigration resistance and for optical devices such as flip-chip light-emitting diodes.

Han, H.; Alford, T. L.

2008-08-01

172

Nanoscale characterization and magnetic property of NiCoCu/Cu multilayer nanowires.  

PubMed

NiCo/Cu multilayer nanowires have been successfully fabricated by a pulse electrodeposition technique using anodic aluminum oxide templates, and their chemistry, crystal structure and magnetic properties characterized at the nanoscale. It was found that each individual nanowire had a regular periodic structure. The NiCo/Cu nanowires also displayed a continuous morphology, smooth surface and polycrystalline fcc structure. EDX elemental mappings confirmed the presence of nickel, cobalt and copper, which appear clearly with a periodic distribution throughout the samples. Both the NiCo and Cu layers were polycrystalline and the average length of the interlayers between NiCo and Cu layers was approximately 3-4 nm. The NiCo/Cu nanowire arrays had an easy axis parallel to the length of wire and exhibited a curling magnetization reversal mechanism. This study highlights the basis morphological, structural and chemical information for NiCoCu/Cu multilayer nanowires, which is critical for their applications in nanodevices and nanoelectronics. PMID:23183276

Qi, Kuo; Li, Xinghua; Zhang, Hong; Wang, Li; Xue, Desheng; Zhang, Haoli; Zhou, Baofan; Mellors, Nigel J; Peng, Yong

2012-12-21

173

Molecular dynamics simulation of Cu-Ni and Cu-Pd binary clusters  

NASA Astrophysics Data System (ADS)

This paper reports on the results of the molecular dynamics simulation of isothermal and isochronous annealings of binary clusters in the Cu-Ni and Cu-Pd systems. The specific features of the formation of the structure are investigated as a function of the component ratio and the cluster size. It is revealed that the Cu-Ni and Cu-Pd clusters have low and high tendencies toward amorphization, respectively. This is explained by different ratios between the atomic sizes in compositionally ordered systems.

Kosilov, A. T.; Malivanchuk, A. A.; Mikha?lov, E. A.

2008-07-01

174

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

Microsoft Academic Search

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

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

1988-01-01

175

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

National Technical Information Service (NTIS)

Measurements of tensile strength and creep resistance have been made on bulk samples of nanocrystalline Cu, Pd and Ag consolidated from powders by cold compaction. Samples of Cu-Cu(sub 2)O have also been tested. Yield strength for samples with mean grains...

G. W. Nieman J. R. Weertman R. W. Siegel

1990-01-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2013-08-01

177

Electrodeposition of CoNi and CoNiCu systems in sulphatecitrate medium  

Microsoft Academic Search

Electrodeposition of CoNi and CoNiCu alloys was performed in a sulphatecitrate medium. Experimental electrodeposition parameters (pH, cobalt(II), nickel(II) and citrate concentrations) were varied in order to analyse their influence on the deposition. Anomalous CoNi codeposition occured in the citrate medium. High [Ni(II)]\\/[Co(II)] ratios (above 5) were suitable for the preparation of homogeneous magnetic Co-rich CoNi deposits of hexagonal close-packed (hcp)

Elvira Gmez; Salvador Pan; Elisa Valls

2005-01-01

178

Microstructural aspects of Cu-Ag produced by the Taylor wire method  

SciTech Connect

The microstructure and phase transformations of Cu-16 at.% Ag fabricated by the Taylor wire technique of drawing molten metals in a glass tube have been studied. As the diameter of the wire becomes smaller and the cooling rate increases, the scale of the microstructure is refined. Nano-crystals of supersaturated solid solution with a 10 nm grain size were observed when the wire diameter was less than 10{micro}m. When the diameter of the wire was larger than 20 {micro}m, proeutectic Cu and the Cu + Ag eutectic were found. In the region where the Cu-Ag eutectic was formed, a (111) twin orientation relationship was found between Cu and Ag.

Han, K.; Embury, J.D.; Petrovic, J.J. [Los Alamos National Lab., NM (United States). Center for Materials Science] [Los Alamos National Lab., NM (United States). Center for Materials Science; Weatherly, G.C. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering] [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

1998-08-10

179

Effects of Ag contents and deposition temperatures on the electrical and optical behaviors of Ag-doped Cu 2O thin films  

Microsoft Academic Search

Cu2OAg thin films were co-deposited by reactive sputtering on glass substrates. During deposition, Ag contents and deposited temperatures were varied. After deposition, a UVVISNIR photometer and a Hall measurement system were used to characterize the optical and electrical properties of these films. The results showed that the Cu2OAg thin films had a decreased optical transmittance with the increase of Ag

C. C. Tseng; J. H. Hsieh; S. J. Liu; W. Wu

2009-01-01

180

Diffusivities of Ni, Zr, Au, and Cu in amorphous Ni-Zr alloys  

NASA Astrophysics Data System (ADS)

The chemical interdiffusion coefficient was measured in an amorphous Ni33Zr67Ni61Zr39 bilayer sample with the use of an ``inert'' marker layer of Au at the interface, and the regular solution approximation, tracer diffusivities for the constituent elements of the alloy were determined. In addition, tracer diffusivities of Au in this alloy, and of Au and Cu in homogeneous Ni50Zr50 amorphous alloys, were measured. The tracer diffusivities of Cu and Ni were much greater than those of Zr and Au suggesting that atomic radii strongly influence diffusion in this alloy. A preliminary value of ~=105 kJ/mol for the activation enthalpy of Ni diffusion was deduced. Similarities between diffusion in a-NiZr alloy and ?-Zr are discussed.

Hahn, H.; Averback, R. S.; Rothman, S. J.

1986-06-01

181

MATLAB-based experimental analysis of optical limiting properties of Cu/Ag mixture nanoparticles  

NASA Astrophysics Data System (ADS)

The evolution of nanoclusters in sequentially ion-implanted Cu/Ag into silica glasses has been studied. Third-order nonlinear optical properties of the nanoclusters were measured at 1064 nm excitations using the Z-scan technique. Results of the investigation of nonlinear refraction by the off-axis Z-scan configuration were presented and the mechanisms responsible for the nonlinear response were discussed. The innovative point of this paper is that we carried out curve fitting analysis, which is based on MATLAB features, for Cu/Ag optical limiting experiment. Our results showed that Cu/Ag mixture nanoclusters have refractive optical limiting effect at 1064 nm.

Wang, Y. H.; Wang, Y. M.; Han, C. J.; Lu, J. D.; Ji, L. L.; Wang, R. W.

2010-07-01

182

Synthesis and structural properties of pure and co-doped (Cu, Ag) ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

Pure ZnO and co-doped (Cu, Ag) ZnO nanoparticles (Zn0.90Cu0.05Ag0.05O) are synthesized by chemical co-precipitation method in the presence of capping agent polyethylene glycol 600 (PEG 600) and annealed at 500 C for 1h. The XRD measurements indicate that the samples show hexagonal structure without any change and the nanocrystalline size decreased from 12 to 5 nm. SEM images are of hexagonal structure of the ZnO and co-doped ZnO samples, and EDAX spectra reveals that the successful doping concentration of Cu and Ag.

Reddy, B. Sankara; Reddy, S. Venkatramana; Reddy, N. Koteeswara

2013-02-01

183

Dilatometric study of martensitic transformation in NiTiCu and NiTi shape memory alloys  

Microsoft Academic Search

Dilatometric measurements have been carried out for the study of nature of martensitic transformation in the NiTiCu and NiTi shape memory alloy wire samples. Investigation has been done in the heat-treat temperature range 300800C. NiTiCu exhibits only single stage A ? M martensitic transformation in the entire heat-treat temperature range indicating the suppression of R-phase by Cu substitution. NiTi shows

J. Uchil; K. K. Mahesh; K. Ganesh Kumara

2001-01-01

184

Ti(Ni,Cu) pseudobinary compounds as efficient negative electrodes for Ni-MH batteries  

NASA Astrophysics Data System (ADS)

The effect of Ni by Cu substitution on the structural, solid-gas and electrochemical hydrogenation properties of TiNi has been investigated. Pseudo-binary TiNi1-xCux (x?0.5) compounds have been synthesized by induction melting. They crystallize in B2 structure above 350K and either in B19? (x<0.1) or B19 (0.2?x?0.5) at room temperature (RT). For all compounds, Pressure-Composition Isotherms at 423K exhibit a single slopping plateau pressure within the range 10-3-1MPa of hydrogen pressure revealing a metal to hydride transformation. Both the hydrogenation capacity and the hydride stability decrease with Cu-content. The hydrided pseudobinary compounds crystallize in the tetragonal S.G. I4/mmm structure as for TiNi hydride. The electrochemical discharge capacity increases with Cu content from 150mAhg-1 for TiNi up to 300mAhg-1 for TiNi0.8Cu0.2 and then decreases again for larger Cu amounts. Electrochemical isotherms and in-situ neutron diffraction measurements at RT demonstrate that such a capacity increase results from a metal to hydride phase transformation in which the hydride phase is destabilized by Cu substitution. The TiNi0.8Cu0.2 compound exhibits interesting cycling stability for 30 cycles and good high-rate capability at D/2 rate. This compound has promising electrochemical properties as compared to commercial LaNi5-type alloys with the advantage of being rare-earth metal free.

Emami, Hoda; Cuevas, Fermin; Latroche, Michel

2014-11-01

185

Reflectance Spectroscopy of Functional Ag-Cu Thin Films: Correlation of Reflectivity with Cu Content  

NASA Astrophysics Data System (ADS)

We have investigated the optical properties of sputter-deposited silver-copper alloy thin films on silicon substrates at room temperature. We found that alloying copper with silver can significantly improve the metal's surface morphology, keeping its infrared reflectivity same as that of pure silver film. However at the same time, it worsens in the blue parts of the spectrum. The reflection in Ag-Cu thin films is interpreted in terms of a simple model describing its trend due to alloying. The experimental results and the speculations reveal a prospect for the improvement and optimization of solar reflectors.

Das, Sayantan; Alford, T. L.

2013-04-01

186

Cu-Ni nanoparticle-decorated graphene based photodetector.  

PubMed

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

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

2014-06-26

187

Wetting and Microstructure Evolution of the Sn-Zn-Ag/Cu Interface  

NASA Astrophysics Data System (ADS)

Wetting of Cu substrates by Sn-Zn eutectic-based alloys with 0.5, 1, and 1.5 wt.% of Ag was studied. Wetting tests were performed at 523 K, in the presence of ALU33 flux, for 15, 30 and 60 s, respectively. The results indicated that the content of Ag in the alloys does not have significant effect on the contact angle. Selected, solidified Sn-8.8Zn- xAg/Cu couples were cross-sectioned and subjected to SEM-EDS study of the interfacial microstructure. The results revealed that the microstructure of the Sn-Zn-Ag/Cu interface evolves with time and is different from Sn-Zn/Cu interface. The continuous interlayers are observed at the interface. Composition of the interlayers was analyzed with EDS and their thickness measured.

Berent, Katarzyna; Fima, Przemys?aw; Ganacarz, Tomasz; Pstru?, Janusz

2014-05-01

188

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

Microsoft Academic Search

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

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

2005-01-01

189

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

Microsoft Academic Search

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

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

1996-01-01

190

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

Microsoft Academic Search

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

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

1996-01-01

191

Sn2.5Ag0.5Cu lead free solder balls with \\  

Microsoft Academic Search

Recently, environmental-friendly products have significantly increased the development of lead free solder material. Some products are already in production and most of semiconductors will be released lead-freely. Among the various lead-free solders, the SnAgCu family of solders has been known as one of the leading candidates for high volume mass-production. However, SnAgCu still has a discoloration issue during ir-reflow and

R. Lee; Wha Soo Sin; Jong Keun Jeon; Heui Seog Kim

2005-01-01

192

Age-hardening by metastable phases in an experimental AuAgCuPd alloy  

Microsoft Academic Search

The age-hardening mechanism and phase transformation during the age-hardening process were examined for a low carat gold alloy with a composition of 30wt.% Au30wt.% Ag20wt.% Cu20wt.% Pd. By aging the solution-treated specimen, the fcc ?0 phase was transformed into the Au-containing Ag-rich phase and the Pd-containing AuCu I phase through the metastable state. The phase transformation of the ?0 phase

Jae-Ho Lee; Sang-Joon Yi; Hyo-Joung Seol; Yong Hoon Kwon; Jai-Bong Lee; Hyung-Il Kim

2006-01-01

193

Initial mercury evaporation from experimental AgSnCu amalgams containing Pd  

Microsoft Academic Search

This study examined the Hg evaporation during setting from experimental AgSnCu alloy powders with and without Pd. Four series of alloy powders were fabricated to examine the effect on the Hg evaporation of the alloy compositions (all percentages in this report are weight percents): Pd (01.5), Cu (9.014.0), Ag (57.063.7), and Sn (24.929.5). These variations in composition produced alloy powders

M. Koike; J. L. Ferracane; J. D. Adey; H. Fujii; T. Okabe

2004-01-01

194

Structure and bonding of the MCN molecules, M=Cu,Ag,Au,Rg  

Microsoft Academic Search

High-precision calculations are reported for the title series with M=Cu, Ag, Au, using CCSD(T) with the latest pseudopotentials and basis sets up to cc-pVQZ. The bond lengths for M=Cu, Ag, Au agree with experiment within better than 1 pm. The role of deep-core excitations is studied. The second-order spin-orbit effects are evaluated at the density functional theory level, including M=Rg.

Patryk Zaleski-Ejgierd; Michael Patzschke; Pekka Pyykk

2008-01-01

195

P-type semiconducting Cu 2 ONiO thin films prepared by magnetron sputtering  

Microsoft Academic Search

P-type semiconducting thin films consisting of a new multicomponent oxide composed of Cu2O and NiO were deposited on glass substrates by r.f. magnetron sputtering using Cu2ONiO mixed powder targets. The multicomponent oxide thin films deposited in an Ar atmosphere with a Ni content (Ni\\/(Cu+Ni) atomic ratio) in the range from 0 to 100at.% were found to be p-type semiconductors. As

Toshihiro Miyata; Hideki Tanaka; Hirotoshi Sato; Tadatsugu Minami

2006-01-01

196

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

197

Effect of plant-based phenol derivatives on the formation of Cu and Ag nanoparticles.  

PubMed

The complexes formed on the reaction of various metal ions viz., Cu(II) and Cu(I) with phenol derivatives viz. catechol, chlorogenic acid (CGA), hydroquinone and n-propyl gallate (nPG) were established by UV-visible spectroscopy. The metal/ligand complexing ratio and complexation constants have been determined. Further, we showed that nanoparticles of Cu can be prepared from metal-phenol complexes in the presence of a protein (gelatin) by ?-irradiation showing that the reduction is metal ion centered. Formation of Ag nanoparticles was also observed on photo-irradiation with xenon lamp in the presence of dihydroxy benzene. The Ag and Cu nanoparticles were characterized by transmission electron microscopy (TEM) and UV-visible absorption spectroscopy. TEM technique showed the presence of Cu and Ag nanoparticles with average size of 20 and 30 nm, respectively. PMID:21621984

Jacob, Jasmine A; Biswas, Nandita; Mukherjee, Tulsi; Kapoor, Sudhir

2011-10-01

198

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

PubMed

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

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

2014-02-28

199

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

SciTech Connect

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.

Valodkar, Mayur; Modi, Shefaly; Pal, Angshuman [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390002, Gujarat (India)] [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390002, Gujarat (India); Thakore, Sonal, E-mail: drsonalit@gmail.com [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390002, Gujarat (India)] [Department of Chemistry, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara 390002, Gujarat (India)

2011-03-15

200

Surfactant Assisted Electrodeposition of Nanostructured CoNiCu Alloys  

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

201

Surface nanostructuring of Ni\\/Cu foilsby femtosecond laser pulses  

Microsoft Academic Search

This work examines the effect of high-power femtosecond laser pulses on Ni\\/Cu bilayer foils produced by electrodeposition. We consider nanostructures formed at different laser beam parameters and under different ambient conditions. The surface nanostructures obtained in air and water have mostly the form of quasi-periodic ripples with a characteristic period of 400 --- 450 and 370 --- 390 nm, respectively,

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

2011-01-01

202

Ni62 Levels and the Decay of Cu62.  

National Technical Information Service (NTIS)

The intensities and energies of gamma-rays following the decay of 62Cu have been measured using a Ge(Li)-NaI(T1) spectrometer operated in the Compton suppression mode. Upper limits for unobserved decays to known low spin states in 62Ni have been establish...

C. Moazed D. Neuffer D. M. Van Patter H. L. Scott P. F. Hinrichsen

1970-01-01

203

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

204

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

NASA Astrophysics Data System (ADS)

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

Mohanty, Udit Surya; Lin, Kwang-Lung

2013-04-01

205

Magnetoresistance in glass-coated Fe-Ni-Cu microwires  

NASA Astrophysics Data System (ADS)

Glass-coated Fe-Ni-Cu microwires were prepared by Taylor's technique. X-ray diffraction data show patterns corresponding to fcc Cu. Negative magnetoresistance has been observed, which reaches 8.15% at 77 K and 6.35% at 300 K in magnetic field of 9.0 T. There is no significant difference between I?H and I?H configurations. Both dc and low frequency ac (f<1 kHz) measurements exhibit essentially the same values of magnetoresistance. The observed magnetoresistance in the Fe-Ni-Cu microwires is of the same origin found in the granular giant magnetoresistance materials and is distinguishable from the giant magnetoimpedance commonly seen in soft magnetic microwires.

Wang, K.-Y.; Feng, L.; O'Connor, C. J.; Tang, J.; Chen, D.-X.; Vazquez, M.; Hernando, A.

1999-04-01

206

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

SciTech Connect

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

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

2009-10-01

207

Hot tensile properties and microstructural evolution of as cast NiTi and NiTiCu shape memory alloys  

Microsoft Academic Search

Hot tensile properties of as cast NiTi and NiTiCu shape memory alloys were investigated by hot tensile test at temperature range of 7001100C using the strain rate of 0.1s?1. The NiTi alloy exhibited a maximum hot ductility at temperature range of 7501000C, while the NiTiCu alloy showed it at temperature range of 8001000C. It was found that at temperatures less

M. Morakabati; M. Aboutalebi; Sh. Kheirandish; A. Karimi Taheri; S. M. Abbasi

2011-01-01

208

Development of Cu-Ag alloys conductor for high field magnet  

SciTech Connect

Highly conductive materials with high strength have been required for the development of high field magnets such as pulsed magnet. Compared with Cu-Al{sub 2}O{sub 3}, Cu-Be, Cu-Cr and Cu-Nb alloys, Cu-Ag alloys are very useful because of easiness in melting and casting. In addition, the alloys exhibit high strength, high conductivity and uniform characteristics by the proper combination of cold-working and heat-treatment. The authors manufactured the Cu-Ag alloys conductor (4 x 6mm in cross section). The conductor has a tensile strength of 1,000MPA and an electrical conductivity of 80%IACS at room temperature, and this conductor is suitable for high field pulsed magnet. It is also easy to handle the conductor in making coil with diameter of about {phi}20mm.

Hirota, Tooru; Imai, Akira; Kumano, Tomoyuki; Ichihara, Masamitsu [Showa Electric Wire and Cable Co. Ltd., Kanagawa (Japan)] [Showa Electric Wire and Cable Co. Ltd., Kanagawa (Japan); Sakai, Yoshikazu; Inoue, Kiyoshi; Maeda, Hiroshi [National Research Inst. for Metals, Ibaraki (Japan)] [National Research Inst. for Metals, Ibaraki (Japan)

1994-07-01

209

Ag- and Cu-doped multifunctional bioactive nanostructured TiCaPCON films  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

210

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

SciTech Connect

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

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

2005-01-31

211

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

212

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

NASA Astrophysics Data System (ADS)

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

Kozub, Gabriela A.

2014-05-01

213

Luminescent Ag i-Cu i heterometallic hexa-, octa-, and hexadecanuclear alkynyl complexes.  

PubMed

A series of Ag(I)-Cu(I) heteronuclear alkynyl complexes were prepared by reaction of polymeric (MCCC(6)H(4)R-4)(n)() (M = Cu(I) or Ag(I); R = H, CH(3), OCH(3), NO(2), COCH(3)) with [M'(2)(mu-Ph(2)PXPPh(2))(2)(MeCN)(2)](ClO(4))(2) (M' = Ag(I) or Cu(I); X = NH or CH(2)). Heterohexanuclear complexes [Ag(4)Cu(2)(mu-Ph(2)PNHPPh(2))(4)(CCC(6)H(4)R-4)(4)](ClO(4))(2) (R = H, 1; CH(3), 2) were afforded when X = NH, and heterooctanuclear complexes [Ag(6)Cu(2)(micro-Ph(2)PCH(2)PPh(2))(3)(CCC(6)H(4)R-4)(6)(MeCN)](ClO(4))(2) (R = H, 3; CH(3), 4; OCH(3), 5; NO(2), 6) were isolated when X = CH(2). Self-assembly reaction between (MCCC(6)H(4)COCH(3)-4)(n) and [M'(2)(mu-Ph(2)PCH(2)PPh(2))(2)(MeCN)(2)](ClO(4))(2), however, gave heterohexadecanuclear complex [Ag(6)Cu(2)(micro-Ph(2)PCH(2)PPh(2))(3)(CCC(6)H(4)COCH(3)-4)(6)](2)(ClO(4))(4) (7). The heterohexanuclear complexes 1 and 2 show a bicapped cubic skeleton (Ag(4)Cu(2)C(4)) consisting of four Ag(I) and two Cu(I) atoms and four acetylide C donors. The heterooctanuclear complexes 3-6 exhibit a waterwheel-like structure that can be regarded as two Ag(3)Cu(CCC(6)H(5))(3) components put together by three bridging Ph(2)PCH(2)PPh(2) ligands. The heterohexadecanuclear complex 7 can be viewed as a dimer of heterooctanuclear complex [Ag(6)Cu(2)(micro-Ph(2)PCH(2)PPh(2))(3)(CCC(6)H(4)COCH(3)-4)(6)](ClO(4))(2) through the silver and acetyl oxygen (Ag-O = 2.534 (4) A) linkage between two waterwheel-like Ag(6)Cu(2) units. All of the complexes show intense luminescence in the solid states and in fluid solutions. The microsecond scale of lifetimes in the solid state at 298 K reveals that the emission is phosphorescent in nature. The emissive state in compounds 1-5 is likely derived from a (3)LMCT (CCC(6)H(4)R-4 --> Ag(4)Cu(2) or Ag(6)Cu(2)) transition, mixed with a metal cluster-centered (d --> s) excited state. The lowest lying excited state in compounds 6 and 7 containing electron-deficient 4-nitrophenylacetylide and 4-acetylphenylacetylide, respectively, however, is likely dominated by an intraligand (3)[pi --> pi] character. PMID:15154812

Wei, Qiao-Hua; Yin, Gang-Qiang; Zhang, Li-Yi; Shi, Lin-Xi; Mao, Zong-Wan; Chen, Zhong-Ning

2004-05-31

214

Mineralization and fluid evolution of the Jiyuan polymetallic CuAgPbZnAu deposit, eastern Tianshan, NW China  

Microsoft Academic Search

The newly discovered Jiyuan CuAg(PbZnAu) deposit is located in the southern section of the eastern Tianshan orogenic belt, Xinjiang, northwestern China. It is the first documented deposit in the large Aqikekuduke AgCuAu belt in the eastern Tianshan orogen. Detailed field observations, parageneses, and fluid inclusion studies suggest an epithermal ore genesis for the main CuAg mineralization, accompanied by a complicated

Huayong Chen; Juntao Yang; Michael Baker

2012-01-01

215

Mineralization and fluid evolution of the Jiyuan polymetallic CuAgPbZnAu deposit, eastern Tianshan, NW China  

Microsoft Academic Search

The newly discovered Jiyuan CuAg(PbZnAu) deposit is located in the southern section of the eastern Tianshan orogenic belt, Xinjiang, northwestern China. It is the first documented deposit in the large Aqikekuduke AgCuAu belt in the eastern Tianshan orogen. Detailed field observations, parageneses, and fluid inclusion studies suggest an epithermal ore genesis for the main CuAg mineralization, accompanied by a complicated

Huayong Chen; Juntao Yang; Michael Baker

2011-01-01

216

Physical properties and photoresponse of CuAgInS semiconductor electrodes created using chemical bath deposition  

Microsoft Academic Search

CuAgInS solid solution semiconductor films were grown on indiumtin oxide-coated glass substrates using chemical bath deposition. New procedures for the growth of CuAgInS semiconductor films are presented. The optical, electrical, and photoelectrochemical performances of the ternary CuInS2, AgIn5S8, and their solid solutions are investigated. The X-ray diffraction patterns of samples reveal a change in the crystal phase of the samples

Chia-Chun Chang; Chia-Jui Liang; Kong-Wei Cheng

2009-01-01

217

Structural and optical properties of (Ag,Cu)(In,Ga)Se2 polycrystalline thin film alloys  

NASA Astrophysics Data System (ADS)

The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se2 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 ao 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 co lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.

Boyle, J. H.; McCandless, B. E.; Shafarman, W. N.; Birkmire, R. W.

2014-06-01

218

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

219

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

220

Correlation effects in Auger spectra of Ni and Cu nanoclusters  

NASA Astrophysics Data System (ADS)

Results of experimental research of exciton-like two-hole states in nanoclusters of narrow-band metals (Ni, Cu) on surface of high-oriented pyrolitic graphite by X-ray photoelectron and Auger electron spectroscopy are presented. It was found that the evolution of the electronic structure in Ni nanoclusters with the decreasing of their sizes can lead to appearance of long-living two-hole states in the valence band. One-particle and two-particle density of states are analyzed, and the Auger-electron spectra confirming the presence of the bound and localized states are obtained.

Troyan, V. I.; Borisyuk, P. V.; Kashurnikov, V. A.; Krasavin, A. V.; Borman, V. D.; Tronin, V. I.

2013-01-01

221

Preparation and characterization of dendrimer-templated Ag-Cu bimetallic nanoclusters.  

PubMed

Ag-Cu bimetallic nanoclusters with different shapes were prepared by a co-complexation method in the presence of PAMAM dendrimers. Small and evenly sized spherical Ag-Cu bimetallic nanoparticles were obtained with N2H4.H2O as the reducing agent, and long rod-shaped bimetallic nanoclusters were prepared with NaBH4 as the reducing agent. The mechanisms of formation of Ag-Cu bimetallic nanolusters with different shapes were discussed. The different shapes of the cluster were likely caused by the differences in the reduction rate of metal ions with NaBH4 and N2H4.H2O. Structure characterization by TEM, UV-vis spectra, EDX, and TGA showed that, in the presence of PAMAM dendrimers, Ag-Cu alloy bimetallic nanorods were obtained with NaBH4 reduction, and Ag-Cu bimetallic nanoparticles were prepared with N2H4.H2O as the reducing agent. PMID:18076157

Li, Guoping; Luo, Yunjun

2008-01-01

222

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

NASA Astrophysics Data System (ADS)

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

Pstru?, Janusz; Gancarz, Tomasz

2014-03-01

223

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

NASA Astrophysics Data System (ADS)

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

Pstru?, Janusz; Gancarz, Tomasz

2014-05-01

224

Phase-Field Modeling and Experimental Observation of Microstructures in Solidifying Sn-Ag-Cu Solders  

NASA Astrophysics Data System (ADS)

A multiphase-field model coupled to a thermodynamic database has been successfully applied to model the microstructure evolution during solidification of ternary Sn-Ag-Cu solders, revealing up to five different phases. Simulations were performed in two dimensions (2D) in the bulk volume of the solder as well as at the interface with a copper substrate, addressing the length scales of both dendritic and eutectic structures. Primary dendrite spacing and secondary arm spacing of Sn dendrites in the bulk solder volume match well with experimental observations. The eutectic spacing of Ag3Sn lamellae and their thickness also match experimental data, while the thickness of the Cu6Sn5 lamellae is slightly larger than found by experiment. Nucleation and growth of Cu6Sn5 on a Cu substrate lead to superficial dissolution and roughening of the substrate, with the size of the Cu6Sn5 largely determined by its nucleation conditions.

Schmitz, G. J.; Zhou, B.; Bttger, B.; Klima, S.; Villain, J.

2013-08-01

225

Comparative study of interfacial reactions of SnAg-Cu and SnAg solders on Cu pads during reflow soldering  

Microsoft Academic Search

The interfacial reaction in soldering is a crucial subject for the solder-joint integrity and reliability in electronic packaging\\u000a technology. However, electronic industries are moving toward lead-free alloys because of environmental concerns. This drive\\u000a has highlighted the fact that the industry has not yet arrived at a decision for lead-free solders. Among the lead-free alloys,\\u000a Sn-3.5Ag and Sn-3.5Ag-0.5Cu are the two

Ahmed Sharif; Y. C. Chan

2005-01-01

226

Study of spin-flip scattering in CuNi by measuring CPP magnetoresistance of Co/CuNi multilayers^*  

NASA Astrophysics Data System (ADS)

For ferromagnetic(F)/noble metal(N) multilayers in which the spin-diffusion length ls >> the F/N unit cell thickness, the two spin-current model predicts that the quantity, ?R^AP(R^AP-R^P) (where R^AP and R^P are CPP resistances of the antiparallel and parallel states), varies linearly with the number of bilayers with a slope independent of ?_N. If ls becomes <= N-layer thickness, there are deviations from linearity from which a finite ls may be derived.(T.Valet et al., Phys. Rev. B48), 7099 (1993); ibid.52, 6513 (1995). Spin-flip scattering arising from spin-orbit interactions (as is observed in CuPt alloys) or from exchange interactions (as is observed in CuMn alloys) can reduce l_s. We have measured the CPP-MR of Co/CuNi multilayers with Ni concentrations ranging from 6% to 20%. Fits of the square root quantity to Valet-Fert theory give values of ls in good agreement with theoretical calculations assuming spin-orbit scattering. We will discuss the effect on CPP-MR of similar spin-flip scattering occuring at the interfaces in NiFe/Cu multilayers. ^*This work was supported by NSF DMR 9423795 & 9400417(MRSEC), the MSU CFMR, and Ford Scientific Laboratory.

Hsu, Shih-Ying; Holody, P.; Loloee Pratt, R., Jr.; Rittner, J. M.; Schroeder, P. A.

1996-03-01

227

The evolution of interface microstructure in a ZrO[sub 2]/Ag-Cu-Al-Ti system  

SciTech Connect

Among ceramic/metal (C/M) joining technologies, the active filler metal method has been studied extensively due to the simple brazing process and excellent joint strength. Active metal elements, typically Ti, are intentionally added to braze alloys to enhance the formation of reaction products between the ceramic and the braze metal at the C/M interface. In the brazing of Al[sub 2]O[sub 3] with the Ag-Cu-Ti filler metal, reaction products such as [gamma]-TiO, Cu[sub 2](Ti, Al)[sub 4]O, Ti[sub 3](Cu[sub 0.76]Al[sub 0.18]Sn[sub 0.06])[sub 3]O were found, while products such as Ti[sub 5]Si[sub 3] and TiN formed in the brazing of Si[sub 3]N[sub 4]. The presence of reaction layers at the C/M interface influences the interface strength in a complex way. In Cu/Al[sub 2]O[sub 3], Co/Al[sub 2]O[sub 3], Ni/Al[sub 2]O[sub 3], and Cu/diamond systems, maxima of joint strength were observed at some intermediate Ti addition, while the flexural strength decreased substantially with the thickening of the TiO layer in a ZrO[sub 2]/Ag-Cu-Sn-Ti system. Thus, composition of the braze alloy (particularly, the content of the active metal), process conditions such as brazing temperature and time, microstructure and mechanical properties of reaction products at the C/M interfaces, interfacial chemistry, and residual stress are primary factors to be studied in order to understand the strengths of the C/M interfaces systematically. In the present and the following papers, evolutions of interfacial microstructures at various brazing conditions, and corresponding interface strengths are reported, respectively, for a ZrO[sub 2]/Ag-Cu-Al-Ti system.

Lee, Youngmin; Yu, Jin (KAIST, Taejon (Korea, Republic of))

1993-08-01

228

Preparation and Structure of FeNi nanoparticles coated with Ag and its Microwave-Absorption Properties  

Microsoft Academic Search

Microwave-absorption materials that have a good magnetic permeability and electrical conductivity are attracting more attentions in the EMI shielding field. This manuscript reported a kind of microwave-absorption FeNi@Ag nanoparticles fabricated through silver mirror reaction, i.e. silver was coated onto the surface of FeNi nanoparticles. The results showed that monodisperse spherical FeNi@Ag nanoparticles had been successfully prepared and exhibited ferromagnetic behavior

Shaofeng Zhou; Qiaoxin Zhang; Jingsong Zhou; Guojin Shen; Jin Huang

2012-01-01

229

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

Microsoft Academic Search

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

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

2001-01-01

230

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

SciTech Connect

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

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

2013-01-15

231

Hydrogen evolution reaction measurements of dealloyed porous NiCu  

PubMed Central

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

2013-01-01

232

Hydrogen evolution reaction measurements of dealloyed porous NiCu  

NASA Astrophysics Data System (ADS)

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.

Koboski, Kyla R.; Nelsen, Evan F.; Hampton, Jennifer R.

2013-12-01

233

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

NASA Astrophysics Data System (ADS)

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.

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

2011-06-01

234

Aging characteristics and precipitate analysis of CuNiMnP alloy  

Microsoft Academic Search

A copper-rich CuNiMnP alloy was designed to have high strength along with good electrical conductivity. Mechanical properties and electrical conductivities of three different CuNiMnP alloys and of the Cu0.89%Ni0.22%P and Cu1.11%Mn0.28%P alloys were measured as a function of aging time at 723K. The aging characteristics of the CuNiMnP alloys showed that the optimum combination of mechanical and electrical properties was

Joon Hwan Choi; Dong Nyung Lee

2007-01-01

235

Orbital Degeneracy Removed by Charge Order in Triangular Antiferromagnet AgNiO2  

NASA Astrophysics Data System (ADS)

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

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

2007-10-01

236

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

SciTech Connect

We report a high-resolution neutron diffraction study on the orbitally degenerate spin-1/2 hexagonal metallic antiferromagnet AgNiO{sub 2}. A structural transition to a tripled unit cell with expanded and contracted NiO{sub 6} octahedra indicates {radical}(3)x{radical}(3) charge order on the Ni triangular lattice. This suggests charge order as a possible mechanism of lifting the orbital degeneracy in the presence of charge fluctuations, as an alternative to the more usual Jahn-Teller distortions. A novel magnetic ground state is observed at low temperatures with the electron-rich S=1 Ni sites arranged in alternating ferromagnetic rows on a triangular lattice, surrounded by a honeycomb network of nonmagnetic and metallic Ni ions. We also report first-principles band-structure calculations that explain microscopically the origin of these phenomena.

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

2007-10-12

237

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

NASA Astrophysics Data System (ADS)

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 Cu3Sn/Cu interface. Under the current density of 1 104 A/cm2, kinetics of Kirkendall void growth and intermetallic compound thickening were affected by the electromigration (EM), and both showed the polarity effect. Cu6Sn5 showed a strong susceptibility to the polarity effect, while Cu3Sn 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 Cu3Sn/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.

Jung, Yong; Yu, Jin

2014-02-01

238

NiZnCu ferrite applied for LTCC microinductor  

NASA Astrophysics Data System (ADS)

This paper describes the fabrication of thin magnetic layers for an LTCC planar-type inductor with a 0.11 mm thickness. The thin ferrite layers were fabricated by tape casting method. Synthesis conditions and X-ray analysis (300 K) of the Ni 0.3Zn 0.62Cu 0.08Fe 2O 4 ferrite are presented. A pure cubic, Fd 3 m crystal structure was observed for the Ni 0.3Zn 0.62Cu 0.08Fe 2O 4 ferrite. The complex impedance and dielectric permittivity of Ni 0.3Zn 0.62Cu 0.08Fe 2O 4 ferrite were determined as a function of temperature (from -55 to 170 C) and frequency (from 10 Hz to 2 MHz). Dc resistivity was measured in a temperature range from -55 to 170 C. Magnetization and magnetic hysteresis were measured by a vibrating sample magnetometer (VSM) in an applied magnetic field up to 60 kOe. The inductance and quality factor were measured in a frequency range 0.1-120 MHz. With the help of finite elements method (FEM) simulation it is possible to calculate the elements electrical parameters and optimize the design. This paper presents a magnetic field modelling of an inductor structure.

Guzdek, P.; Kulawik, J.; Zaraska, K.; Bie?kowski, A.

2010-10-01

239

An embedded-atom potential for the CuAg system  

Microsoft Academic Search

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

P L Williams; Y Mishin; J C Hamilton

2006-01-01

240

Ag-Cu-Ni (Silver-Copper-Nickel)  

NASA Astrophysics Data System (ADS)

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

Materials Science International Team MSIT

241

Ag-Cu-Ni (Silver-Copper-Nickel)  

Microsoft Academic Search

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

2007-01-01

242

Plasmon-exciton transition in iodized Ag-Cu nanostructured films  

NASA Astrophysics Data System (ADS)

Ag1-xCuxI (x= 0.10, 0.20, and 0.50) thin films with thicknesses upto15 nm produced by thermal co-evaporation onto glass substrates were systematically iodized and carefully characterized. Optical absorption spectra of uniodized Ag-Cu films show intense surface plasmon resonance (SPR) features with maxima at 430, 445 and 445 nm for the films of thickness 5, 10 and 15 nm respectively and a gradual transition to zincblende AgI exciton with optical signatures at 425 nm. Delayed evolution and inhomogeneous broadening of the exciton absorption at 425 nm of the spatially confined ?- AgI nanoparticles were clearly seen by the development of Z1,2 and Z3 exciton peaks iodization kinetics being controlled by the as-quenched Ag-Cu clusters. Cu addition not only restricts the particle size, but also favors the island type growth mode. PL observed at 428 nm shows a thickness and Cu-composition dependent intensity suggesting the involvement of Frenkel defects in non-radiative recombination.

Gnanavel, M.; Sunandana, C. S.

2009-08-01

243

Synthetic control of FePtM nanorods (M = Cu, Ni) to enhance the oxygen reduction reaction.  

PubMed

To further enhance the catalytic activity and durability of nanocatalysts for the oxygen reduction reaction (ORR), we synthesized a new class of 20 nm 2 nm ternary alloy FePtM (M = Cu, Ni) nanorods (NRs) with controlled compositions. Supported on carbon support and treated with acetic acid as well as electrochemical etching, these FePtM NRs were converted into core/shell FePtM/Pt NRs. These core/shell NRs, especially FePtCu/Pt NRs, exhibited much improved ORR activity and durability. The Fe10Pt75Cu15 NRs showed a mass current densities of 1.034 A/mgPt at 512 mV vs Ag/AgCl and 0.222 A/mgPt at 557 mV vs Ag/AgCl, which are much higher than those for a commercial Pt catalyst (0.138 and 0.035 A/mgPt, respectively). Our controlled synthesis provides a general approach to core/shell NRs with enhanced catalysis for the ORR or other chemical reactions. PMID:23634823

Zhu, Huiyuan; Zhang, Sen; Guo, Shaojun; Su, Dong; Sun, Shouheng

2013-05-15

244

Martensitic transformation of Cu on Ag(001) and Cu on Au(001) studied with classical molecular dynamics  

NASA Astrophysics Data System (ADS)

The growth of Cu thin films on Ag(001) and Au(001) substrates was modeled using molecular dynamics with classical potentials. We observed that deposited atoms formed an unstable bcc or bcc/body-centered-tetragonal structure, in agreement with previous experiments. We show that the formation of such structures is related to film thickness and temperature that was analyzed in the interval from 200 to 600 K. bcc nucleation was measured by observing the relation between thickness and temperature of the deposited thin film. The martensitic transformation accompanied by a stripe pattern occurred as a consequence of the distortions caused by the underlying substrate lattice. The stripe patterns were measured as 57 and 61 for Cu on Ag and Cu on Au, respectively. Monolayer spacing and coordination number of atoms were calculated, clearly evidencing the formed structures. Local structures were studied using the Ackland-Jones method, to determine the phases of the deposited films.

Pereira, Z. S.; da Silva, E. Z.

2009-03-01

245

Thermal Analysis of the Sn-Ag-Cu-In Solder Alloy  

Microsoft Academic Search

The tin-based alloy Sn-1.5Ag-0.7Cu-9.5In (composition in wt.%) is a potential candidate for lead-free soldering at temperatures\\u000a close to 200C due to the significant amount of indium. Samples of Sn-1.5Ag-0.7Cu-9.5In were prepared by controlled melting\\u000a of the pure elements, followed by quenching to room temperature. The samples were analyzed by scanning electron microscopy\\/energy-dispersive\\u000a x-ray spectroscopy (SEM\\/EDS) and electron backscatter diffraction. The

Marin Palcut; Erika Hodlov; Jozef Janovec

2010-01-01

246

Growth analysis of (Ag,Cu)InSe2 thin films via real time spectroscopic ellipsometry  

NASA Astrophysics Data System (ADS)

In situ and ex situ characterization methods have been applied to investigate the properties of (Ag,Cu)InSe2 (ACIS) thin films. Data acquired from real time spectroscopic ellipsometry (RTSE) experiments were analyzed to extract the evolution of the nucleating, bulk, and surface roughness layer thicknesses. The evolution of these layer thicknesses suggests a transition from Volmer-Weber to Stranski-Krastanov type behavior when Cu is replaced by Ag. The complex dielectric functions of ACIS at both deposition and room temperature as a function of film composition were also extracted from the RTSE data, enabling parameterization of the alloy optical properties.

Little, S. A.; Ranjan, V.; Collins, R. W.; Marsillac, S.

2012-12-01

247

Impedance and photoelectrochemical study of surface layers on Cu and Cu10Ni in acetate solution containing benzotriazole  

Microsoft Academic Search

The electrochemical behaviour of Cu and Cu10Ni alloy in 1 M sodium acetate solution, pH 5.8 without and in the presence of benzotriazole (BTAH) was investigated by cyclic voltammetry, photopotential measurements and impedance spectroscopy. Both polarization and impedance studies clearly show that BTAH forms the multilayer structure Cu\\/Cu2O-Cu(I)BTA on the electrode surface at a higher concentration of the inhibitor (cBTAH?1

R. Babi?; M. Metiko-Hukovi?; M. Lon?ar

1999-01-01

248

Simulation of growth of Cu on Ag(001) at experimental deposition rates  

NASA Astrophysics Data System (ADS)

The initial stages of growth of (001)Cu films on (001)Ag substrates have been investigated using the temperature-accelerated dynamics (TAD) simulation method. The acceleration provided by TAD made it possible to simulate the deposition of Cu on (001)Ag at 77 K using a deposition rate of 0.04 ML/s, which matched previously reported experiments. This simulation was achieved without a priori knowledge of the significant atomic processes. The results showed that the increased in-plane lattice parameter of the pseudomorphic Cu reduces the activation energy for the exchange mode of surface diffusion, allowing short-range terrace diffusion and the formation of compact Cu islands on the second film layer at 77 K. Some unexpected complex surface diffusion processes and off-lattice atomic configurations were also observed.

Sprague, J. A.; Montalenti, F.; Uberuaga, B. P.; Kress, J. D.; Voter, A. F.

2002-11-01

249

First principles study of Ag, Au, and Cu surface segregation in FePt-L10  

Microsoft Academic Search

Doping FePt nanoparticles could be a possible approach to achieve high L10 order and magnetic anisotropy. To address stability, first-principles studies of surface segregation of dilute Ag\\/Au\\/Cu solutes at and near the (001)\\/(100)\\/(111) surfaces of FePt-L10 are performed. It is found that a strong surface segregation tendency at first outer layer is present in all the cases. For Cu, segregation

Roman V. Chepulskii; Stefano Curtarolo

2010-01-01

250

Guinier-Preston zones in Al-rich Al?Cu and Al?Ag single crystals  

NASA Astrophysics Data System (ADS)

Guinier-Preston zones in Al?Ag and Al?Cu were investigated by diffuse X-ray and neutron scattering. In Al-3 at % Ag no differences are found between zones formed above and below 500 K (?- and ?-zones, respectively). Their average Ag concentration is (80 10) at %, and the Ag concentration decreases by 10-15% from shell to core of the zones. In Al-1.75 at % Cu, Guinier-Preston I zones are dominantly monolayers with a Cu fraction of (84 2) at %.

Schnfeld, Bernd; Malik, Alexander; Kostorz, Gernot; Bhrer, Willy; Skov Pedersen, Jan

1997-02-01

251

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

Microsoft Academic Search

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

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

2008-01-01

252

Effects on Undercooling and Interfacial Reactions with Cu Substrates of Adding Bi and In to Sn-3Ag Solder  

NASA Astrophysics Data System (ADS)

This study investigated the effects of adding Bi and In to Sn-3Ag Pb-free solder on undercooling, interfacial reactions with Cu substrates, and the growth kinetics of intermetallic compounds (IMCs). The amount of Sn dominates the undercooling, regardless of the amount or species of further additives. The interfacial IMC that formed in Sn-Ag-Bi-In and Sn-In-Bi solders is Cu6Sn5, while that in Sn-Ag-In solders is Cu6(Sn,In)5, since Bi enhances the solubility of In in Sn matrices. The activation energy for the growth of IMCs in Sn-Ag-Bi-In is nearly double that in Sn-Ag-In solders, because Bi in the solder promotes Cu dissolution. The bright particles that form inside the Sn-Ag-In bulk solders are the ?-phase.

Chiang, Yu-Yan; Cheng, Robbin; Wu, Albert T.

2010-11-01

253

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

NASA Astrophysics Data System (ADS)

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

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

2004-09-01

254

Sensitive and selective detection of Hg2+ and Cu2+ ions by fluorescent Ag nanoclusters synthesized via a hydrothermal method  

NASA Astrophysics Data System (ADS)

An easily prepared fluorescent Ag nanoclusters (Ag NCs) probe for the sensitive and selective detection of Hg2+ and Cu2+ ions was developed here. The Ag NCs were synthesized by using polymethacrylic acid sodium salt as a template via a convenient hydrothermal process. The as-prepared fluorescent Ag NCs were monodispersed, uniform and less than 2 nm in diameter, and can be quenched in the presence of mercury (Hg2+) or copper (Cu2+) ions. Excellent linear relationships existed between the quenching degree of the Ag NCs and the concentrations of Hg2+ or Cu2+ ions in the range of 10 nM to 20 ?M or 10 nM to 30 ?M, respectively. By using ethylenediaminetetraacetate (EDTA) as the masking agent of Cu2+, Hg2+ was exclusively detected in coexistence with Cu2+ with high sensitivity (LOD = 10 nM), which also provided a reusable detection method for Cu2+. Furthermore, the different quenching phenomena caused by the two metals ions such as changes in visible colour, shifts of UV absorbance peaks and changes in size of Ag NCs make it easy to distinguish between them. Therefore the easily synthesized fluorescent Ag NCs may have great potential as Hg2+ and Cu2+ ions sensors.An easily prepared fluorescent Ag nanoclusters (Ag NCs) probe for the sensitive and selective detection of Hg2+ and Cu2+ ions was developed here. The Ag NCs were synthesized by using polymethacrylic acid sodium salt as a template via a convenient hydrothermal process. The as-prepared fluorescent Ag NCs were monodispersed, uniform and less than 2 nm in diameter, and can be quenched in the presence of mercury (Hg2+) or copper (Cu2+) ions. Excellent linear relationships existed between the quenching degree of the Ag NCs and the concentrations of Hg2+ or Cu2+ ions in the range of 10 nM to 20 ?M or 10 nM to 30 ?M, respectively. By using ethylenediaminetetraacetate (EDTA) as the masking agent of Cu2+, Hg2+ was exclusively detected in coexistence with Cu2+ with high sensitivity (LOD = 10 nM), which also provided a reusable detection method for Cu2+. Furthermore, the different quenching phenomena caused by the two metals ions such as changes in visible colour, shifts of UV absorbance peaks and changes in size of Ag NCs make it easy to distinguish between them. Therefore the easily synthesized fluorescent Ag NCs may have great potential as Hg2+ and Cu2+ ions sensors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03329e

Liu, Jing; Ren, Xiangling; Meng, Xianwei; Fang, Zheng; Tang, Fangqiong

2013-09-01

255

Effect of Ni Layer Thickness on Cu-Based \\\\{100\\\\} Textured Substrate for Coated Conductor  

Microsoft Academic Search

We prepared substrates with the structure electroplated Ni\\/textured Cu\\/stainless steel (SS) and clarified the effect of the electroplated Ni layer thickness on the substrate performance by investigating the dependences of the degree of crystal orientation and the surface roughness on the Ni layer thickness. It was confirmed that the orientation of the Ni layer did not significantly change up to

Naoji Kashima; Shuichi Kubota; Kunihiro Shima; Toshiya Doi; Shigeo Nagaya; Masayoshi Inoue; Takanobu Kiss

2011-01-01

256

Ostwald ripening of decomposed phases in CuNiCr alloys  

Microsoft Academic Search

A study of the coarsening process of the decomposed phases was carried out in the Cu34wt.% Ni4wt.% Cr and Cu45wt.% Ni10wt.% Cr alloys using transmission electron microscopy. As aging progressed, the morphology of the coherent decomposed Ni-rich phase changed from cuboids to platelets aligned in the ?100? Cu-rich matrix directions. Prolonged aging caused the loss of coherency between the decomposed

Felipe Hernandez-Santiago; Victor Lopez-Hirata; Hector J. Dorantes-Rosales; Maribel L. Saucedo-Muoz; Jorge L. Gonzalez-Velazquez; Ana Ma. Paniagua-Mercado

2008-01-01

257

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

NASA Astrophysics Data System (ADS)

Proton Nuclear Magnetic Resonance (NMR) relaxation measurements have been performed down to very low temperature (50 mK) to determine the effect of coupling two Cr7Ni molecular rings via a Cu2+ ion. No difference in the spin dynamics was found from nuclear spin lattice relaxation down to 1.5 K. At lower temperature, the 1H-NMR line broadens dramatically indicating spin freezing. From the plot of the line width vs. magnetization, it is found that the freezing temperature is higher (260 mK) in the coupled ring with respect to the single Cr7Ni ring (140 mK).

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

2014-05-01

258

Thermoelectric power study of Ag 7C 6H 14NI 8 material  

NASA Astrophysics Data System (ADS)

Thermoelectric power of the material Ag 7C 6H 14NI 8 has been studied for the first time in the temperature range 20-l00C. Thermopower versus 1/ T plot comes out to be a straight line and can be represented by the equation -?=0.15 {10 3}/{T}+0.06 for the material. Heat of transport of Ag + ion in the material is very nearly equal to the activation energy. The work points towards the correctness of the Rice and Roth model. It also shows that the material is ordered.

Khalifa, M. M.; EL-Mashri, S. M.; Avasthi, M. N.

2002-08-01

259

Embedded-atom method applied to bimetallic clusters: The Cu-Ni and Cu-Pd systems  

NASA Astrophysics Data System (ADS)

A study of ordering and segregation in bimetallic clusters has been carried out using the embedded-atom method. Icosahedral and cuboctahedral clusters with up to 147 atoms have been considered. The model has been applied to the Cu-Ni and Cu-Pd systems and we have found that the icosahedral structure is favored over the cuboctahedral one. Cu segregates to the surface in the Cu-Ni clusters, and a subtle interplay between ordering and segregation is observed in the Cu-Pd clusters.

Montejano-Carrizales, J. M.; Iiguez, M. P.; Alonso, J. A.

1994-06-01

260

Auger electron spectroscopy investigations of the effect of degradation of depth resolution and its influence on the interdiffusion data in thin film Au\\/Ag, Cu\\/Ag, Pd\\/Au and Pd\\/Cu multilayer structures  

Microsoft Academic Search

Auger depth profile investigations of interdiffusion in the bilayer and multilayer Au\\/Ag, Cu\\/Ag, Pd\\/Au and Pd\\/Cu thin film structures in the temperature range 423573K have been reported. Bilayers and multilayers have been obtained by successive evaporation onto the SiO2 and Cu substrates with different surface topographies. The thickness of bilayers was changed from 50 to 200nm, whereas the thickness of

A. Bukaluk

2001-01-01

261

Vacuum degassing behavior of Zr, Ni and Cu-based metallic glass powders  

Microsoft Academic Search

The vacuum degassing behavior of Zr55Al10Ni5Cu30, Ni59Zr15Ti13Si3Sn2Nb7Al1, and Cu54Ni6Zr22Ti18 (numbers indicate at.%) metallic glass powders has been investigated and compared with that of Al alloy powder. It was found that the alloy composition influenced the gas desorption behavior with heating in vacuo. Zr55Al10Ni5Cu30 and Ni59Zr15Ti13Si3Sn2Nb7Al1 metallic glass powders exhibited little H2 gas desorption from powder surfaces during vacuum degassing. Because

Michiaki Yamasaki; Kotaro Iwamoto; Hirokazu Tamagawa; Yoshihito Kawamura; Jin-Kyu Lee; Hwi-Jun Kim; Jung-Chan Bae

2007-01-01

262

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

PubMed

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

Salmani, Mohammad Hossein; Ehrampoush, Mohammad Hassan; Aboueian-Jahromi, Mohaddeseh; Askarishahi, Mohsen

2013-01-01

263

Effects of additional elements (Fe, Co, Al) on SnAgCu solder joints  

Microsoft Academic Search

The electronics industry has successfully transitioned to lead free soldering for computer and consumer products while in the automotive industry due to the very high reliability requirements this step is still in an ongoing process. In order to ensure or even to enhance the reliability of electronics the improvement of lead free solder joints based on Sn-Ag-Cu (SAC) solder has

Matthias Hutter; Ralf Schmidt; Patrick Zerrer; Steffen Rauschenbach; Klaus Wittke; Wolfgang Scheel; Herbert Reichl

2009-01-01

264

Spin-Diffusion Lengths in Ag(4%Sn) and Cu(2%Ge) alloys  

NASA Astrophysics Data System (ADS)

Alloying Ag with a little Sn, or Cu with a little Ge, greatly increases elastic scattering of electrons---i.e., greatly decreases the electron mean-free-path (mfp), but does not produce much spin-flipping---i.e., leaves the electron spin-diffusion length, l, relatively long. Thus, dilute AgSn and CuGe alloys were used to study effects of changing the mfp on current-perpendicular-to-plane (CPP) magnetoresistance [1] and current-induced magnetization switching (CIMS) [2], while leaving spin-flipping weak. Published transport data in dilute AgSn and CuGe alloys give only lower bounds for l [3-5]. We find l = 34 4 nm for Ag(4%Sn) and l = 125 10 nm for Cu(2%Ge). [1] K. Eid et al., J. Magn. Magn. Mat. 224, L205 (2001). [2] N. Theodoropoulou et al., Phys. Rev. B (rapid comm.) in press. [3] S.-F.Lee et al., J. Magn. Magn. Mat. 118, L1 (993). [4] J. Bass et al, Mat. Sci. and Eng. B31, 77 (1995). [5] J. Bass and W.P. Pratt Jr., J. Phys. Cond. Matt. 19, 183201 (2007).

Sharma, Amit; Richard, Brandon; Fowler, Quinton; Loloee, Reza; Pratt, William, Jr.; Bass, Jack

2008-03-01

265

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

266

Ablation characteristics of Au, Ag, and Cu metals using a femtosecond Ti:sapphire laser  

Microsoft Academic Search

Femtosecond laser ablation of metallic bulk crystals of Au, Ag and Cu was experimentally studied with laser pulse widths ranging from 120 fs through 800 fs at a center wavelength of 780 nm for micro-machining applications. Two different ablation regimes were found in terms of the laser fluence. The characteristic length of different ablation regimes was explained in terms of

K. Furusawa; K. Takahashi; H. Kumagai; K. Midorikawa; M. Obara

1999-01-01

267

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

Microsoft Academic Search

We present the calculation of vibrational modes and lattice relaxation for the (110), (211), (311), (511), (331) and (221) surfaces of Al, Ag, Cu and Pd. The surface phonon frequencies and polarizations are obtained for relaxed and unrelaxed surfaces using embedded atom model potentials. On all surfaces studied step-localized vibrational modes and surface states localized on terrace atoms are found.

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

1998-01-01

268

Toxicity interaction of metals (Ag, Cu, Hg, Zn) to urease and dehydrogenase activities in soils  

Microsoft Academic Search

A study of the individual and mixture toxicities of the trace metals Ag, Cu, Hg, Zn to the soil enzymes dehydrogenase and urease was undertaken. An agricultural soil and a sandy forest soil were spiked with metal salts, individually and in combinations. The anion additions to the various treatments and controls were normalized for added anions using Ca salts. The

Sophie Chaperon; Sbastien Sauv

2007-01-01

269

Enhanced thermomechanical functionality of a laser processed hybrid NiTi-NiTiCu shape memory alloy  

NASA Astrophysics Data System (ADS)

The exciting thermomechanical behavior of NiTi shape memory alloys (SMAs) has sparked significant research effort seeking to exploit their exotic properties. The performance capabilities of conventional NiTi offerings are limited, however, by current fabrication technologies. In this study, a high power density laser source was implemented to locally alloy Cu into a conventional NiTi material. The effects of laser processing created a localized NiTiCu ternary material domain which possessed a set of unique thermomechanical properties. The combined active responses of the laser processed hybrid NiTi-NiTiCu SMA represent an enhanced material functionality, which permits a multi-stage thermomechanical recovery and allows for unprecedented novel applications to be realized.

Daly, M.; Pequegnat, A.; Zhou, Y.; Khan, M. I.

2012-04-01

270

Cryogenic treatment induced hardening of Cu45Zr45Ag7Al3 bulk metallic glass  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

271

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

PubMed

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

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

2014-07-01

272

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

NASA Astrophysics Data System (ADS)

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.

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

1991-05-01

273

Guinier-Preston zones in Al-rich Al?Cu and Al?Ag single crystals  

Microsoft Academic Search

Guinier-Preston zones in Al?Ag and Al?Cu were investigated by diffuse X-ray and neutron scattering. In Al-3 at % Ag no differences are found between zones formed above and below 500 K (?- and ?-zones, respectively). Their average Ag concentration is (80 10) at %, and the Ag concentration decreases by 1015% from shell to core of the zones. In

Bernd Schnfeld; Alexander Malik; Gernot Kostorz; Willy Bhrer; Jan Skov Pedersen

1997-01-01

274

Thermal cycling reliability of Cu\\/SnAg double-bump flip-chip assemblies for 100um pitch applications  

Microsoft Academic Search

Thick Cu column based double-bump flip-chip structure is one of the promising alternatives for fine pitch flip-chip applications. In this study, the thermal cycling (T\\/C) reliability of Cu\\/SnAg double-bump flip-chip assemblies was mainly investigated and the failure mechanism was analyzed through the correlation of T\\/C test results and the finite element analysis (FEA). T\\/C failures occurred from the outmost Cu\\/SnAg

Ho-Young Son; Il-Ho Kim; Soon-Bok Lee; Gi-Jo Jung; Byung-Jin Park; Kyung-Wook Paik

2007-01-01

275

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

276

Effect of Ni Layer Thickness on Cu-Based \\{100\\}< 001 > Textured Substrate for Coated Conductor  

NASA Astrophysics Data System (ADS)

We prepared substrates with the structure electroplated Ni/textured Cu/stainless steel (SS) and clarified the effect of the electroplated Ni layer thickness on the substrate performance by investigating the dependences of the degree of crystal orientation and the surface roughness on the Ni layer thickness. It was confirmed that the orientation of the Ni layer did not significantly change up to a thickness of 10 ?m; however, the surface roughness of the Ni layer decreased when the layer thickness exceeded 3 ?m. From these results, in order to achieve a high critical current density (Jc) on a Cu substrate, it is suggested that the preferred maximum thickness of the Ni layer on the textured Cu should be approximately 3 ?m. In addition, the possibility of broad availability for the coating process was investigated by estimating the Cu concentration on the surface of a 3-?m-thick Ni layer.

Kashima, Naoji; Kubota, Shuichi; Shima, Kunihiro; Doi, Toshiya; Nagaya, Shigeo; Inoue, Masayoshi; Kiss, Takanobu

2011-06-01

277

Adaptive crystal structures: CuAu and NiPt.  

PubMed

We discover that Au-rich Cu1-xAux and Pt-rich Ni1-xPtx contain a composition range in which there is a quasicontinuum of stable, ordered "adaptive structures" made of (001) repeat units of simple structural motifs. This is found by searching approximately 3x10(6) different fcc configurations whose energies are parametrized via a "cluster expansion" of first-principles-calculated total energies of just a few structures. This structural adaptivity is explained in terms of an anisotropic, long-range strain energy. PMID:12570430

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

2003-01-31

278

Mechanical properties of AgNi super-laminates produced by rolling  

Microsoft Academic Search

Multilayer materials which have the layer thickness with nano-scale or meso-scopic scale have been produced by the repeated process of diffusion bonding and rolling. We call these multilayers super-laminates. The strength of Ag-Ni super-laminates increases with the decreasing layer thickness. The ultimate tensile strength reached 1000 MPa for the laminates which have a layer thickness 673 K due to the

Shiomi Kikuchi; Hideyuki Kuwahara; Naoko Mazaki; Shunji Urai; Hiroshi Miyamura

1997-01-01

279

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

280

Microstructures and degradation of heat sink very-thin quad flat package no-leads Pb-free Sn-Ag-Cu solder joints after thermal aging  

NASA Astrophysics Data System (ADS)

Heat sink very-thin quad flat package no-leads (HVQFN) packages soldered with Sn-3.8Ag-0.7Cu on metallized laminate substrates have been put to thermal aging. Temperatures from 140C to 200C for times up to 30 weeks were applied. The solder joint microstructure develops intermetallic compound layers and voids within the solder. Due to this, the mechanical reliability of the HVQFN inner lead solder joints is degraded. The intermetallic layers are of the type (Cu, Y)6Sn5, with Y=Ni, Au or Ni+Au, as well as Cu3Sn, and follow a power law with aging time: X=Ctn, where n=0.4 to 1.9 depending on temperature. The voids within the solder are attributed to Sn depletion of the solder in favor of the growth of (Cu,Ni)6Sn5. They are more pronounced the less the solder volume is in proportion to the intermetallic diffusion area. The amount of voids is quantified as a percentage of the residual solder. The time to reach the failure criterion of 50%, i.e., t50%, is related to the absolute temperature according to an Arrhenius equation with an activation energy Ea=0.95 eV. This equation is used for determination of the maximum allowable temperature at a certain required operating lifetime.

Fredriksz, W.

2005-09-01

281

Effect of Pd Thickness on the Interfacial Reaction and Shear Strength in Solder Joints Between Sn-3.0Ag-0.5Cu Solder and Electroless Nickel/Electroless Palladium/Immersion Gold (ENEPIG) Surface Finish  

NASA Astrophysics Data System (ADS)

Intermetallic compound formation at the interface between Sn-3.0Ag-0.5Cu (SAC) solders and electroless nickel/electroless palladium/immersion gold (ENEPIG) surface finish and the mechanical strength of the solder joints were investigated at various Pd thicknesses (0 ?m to 0.5 ?m). The solder joints were fabricated on the ENEPIG surface finish with SAC solder via reflow soldering under various conditions. The (Cu,Ni)6Sn5 phase formed at the SAC/ENEPIG interface after reflow in all samples. When samples were reflowed at 260C for 5 s, only (Cu,Ni)6Sn5 was observed at the solder interfaces in samples with Pd thicknesses of 0.05 ?m or less. However, the (Pd,Ni)Sn4 phase formed on (Cu,Ni)6Sn5 when the Pd thickness increased to 0.1 ?m or greater. A thick and continuous (Pd,Ni)Sn4 layer formed over the (Cu,Ni)6Sn5 layer, especially when the Pd thickness was 0.3 ?m or greater. High-speed ball shear test results showed that the interfacial strengths of the SAC/ENEPIG solder joints decreased under high strain rate due to weak interfacial fracture between (Pd,Ni)Sn4 and (Cu,Ni)6Sn5 interfaces when the Pd thickness was greater than 0.3 ?m. In the samples reflowed at 260C for 20 s, only (Cu,Ni)6Sn5 formed at the solder interfaces and the (Pd,Ni)Sn4 phase was not observed in the solder interfaces, regardless of Pd thickness. The shear strength of the SAC/ENIG solder joints was the lowest of the joints, and the mechanical strength of the SAC/ENEPIG solder joints was enhanced as the Pd thickness increased to 0.1 ?m and maintained a nearly constant value when the Pd thickness was greater than 0.1 ?m. No adverse effect on the shear strength values was observed due to the interfacial fracture between (Pd,Ni)Sn4 and (Cu,Ni)6Sn5 since the (Pd,Ni)Sn4 phase was already separated from the (Cu,Ni)6Sn5 interface. These results indicate that the interfacial microstructures and mechanical strength of solder joints strongly depend on the Pd thickness and reflow conditions.

Kim, Young Min; Park, Jin-Young; Kim, Young-Ho

2012-04-01

282

Modeling toxicity of binary metal mixtures (Cu(2+) -Ag(+) , Cu(2+) -Zn(2+) ) to lettuce, Lactuca sativa, with the biotic ligand model.  

PubMed

The biotic ligand model (BLM) was applied to predict metal toxicity to lettuce, Lactuca sativa. Cu(2+) had the lowest median effective activity (EA50(M) ), compared with Ag(+) and Zn(2+) (EA50(Cu) ?= 2.60 10(-8) M, EA50(Ag) = 1.34 10(-7) ?M, EA50(Zn) = 1.06 10(-4) ?M). At the 50% response level, the fraction of the total number of biotic ligands occupied by ions (f50(M) ) was lowest for Ag(+) among the metals (f50(Ag) = 0.22, f50(Cu) = 0.36, f50(Zn) = 0.42). Cu(2+) had the highest affinity for biotic ligands compared with Ag(+) and Zn(2+) , as shown by stability constants of the cation-biotic ligand binding, expressed as log K(MBL) (log K(CuBL) = 7.40, log K(AgBL) = 6.39, log K(ZnBL) = 4.00). Furthermore, the BLM was combined with the toxic equivalency factor approach in predicting toxicity of mixtures of Cu(2+) -Zn(2+) and Cu(2+) -Ag(+) . The fraction of biotic ligands occupied by ions was used to determine the relative toxic potency of metals and the toxic equivalency quotient (TEQ) of mixtures. This approach allowed for including interactions in estimating mixture toxicity and showed good predictive power (r(2) = 0.64-0.84). The TEQ at the 50% response level (TEQ50, Cu(2+) equivalents) for Cu(2+) -Zn(2+) mixtures was significantly lower than the value for Cu(2+) -Ag(+) mixtures. Joint toxicity depended on both TEQ and specific composition of the mixture. The present study supports the use of the accumulation of metal ions at the biotic ligands as a predictor of toxicity of single metals and mixtures. PMID:23109233

Yen Le, T T; Vijver, Martina G; Jan Hendriks, A; Peijnenburg, Willie J G M

2013-01-01

283

Sensitive and selective detection of Hg2+ and Cu2+ ions by fluorescent Ag nanoclusters synthesized via a hydrothermal method.  

PubMed

An easily prepared fluorescent Ag nanoclusters (Ag NCs) probe for the sensitive and selective detection of Hg(2+) and Cu(2+) ions was developed here. The Ag NCs were synthesized by using polymethacrylic acid sodium salt as a template via a convenient hydrothermal process. The as-prepared fluorescent Ag NCs were monodispersed, uniform and less than 2 nm in diameter, and can be quenched in the presence of mercury (Hg(2+)) or copper (Cu(2+)) ions. Excellent linear relationships existed between the quenching degree of the Ag NCs and the concentrations of Hg(2+) or Cu(2+) ions in the range of 10 nM to 20 ?M or 10 nM to 30 ?M, respectively. By using ethylenediaminetetraacetate (EDTA) as the masking agent of Cu(2+), Hg(2+) was exclusively detected in coexistence with Cu(2+) with high sensitivity (LOD = 10 nM), which also provided a reusable detection method for Cu(2+). Furthermore, the different quenching phenomena caused by the two metals ions such as changes in visible colour, shifts of UV absorbance peaks and changes in size of Ag NCs make it easy to distinguish between them. Therefore the easily synthesized fluorescent Ag NCs may have great potential as Hg(2+) and Cu(2+) ions sensors. PMID:24056730

Liu, Jing; Ren, Xiangling; Meng, Xianwei; Fang, Zheng; Tang, Fangqiong

2013-10-21

284

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

285

Kinetics of intermetallic phase formation at the interface of SnAgCuX (X = Bi, In) solders with Cu substrate  

Microsoft Academic Search

The effects of Bi and In additions on intermetallic phase formation in lead-free solder joints of Sn3.7Ag0.7Cu; Sn1.0Ag0.5Cu1.0Bi and Sn1.5Ag0.7Cu9.5In (composition given in weight %) with copper substrate are studied. Soldering of copper plate was conducted at 250C for 5s. The joints were subsequently aged at temperatures of 130170C for 216 days in a convection oven. The aged interfaces were

Erika Hodlov; Marin Palcut; Emil Lechovi?; Beta imekov; Koloman Ulrich

2011-01-01

286

Influence of minor Ag nano-particles additions on the microstructure of Sn30Bi0.5Cu solder reacted with a Cu substrate  

Microsoft Academic Search

The objective of this paper is to study the influence of minor Ag nano-particles additions on the microstructural evolution\\u000a of Sn30Bi0.5Cu lead-free solder matrices and the interfacial reactions. Ag nano-particle reinforced SnBiCuxAg (x=1, 2,\\u000a 5) composite solder pastes were prepared by a mechanical mixing method and then were reflowed on Cu substrates. Three cooling\\u000a methods (furnace cooling, air cooling and

Changfei PengJun; Jun Shen; Weidong Xie; Jie Chen; Cuiping Wu; Xiaochuan Wang

2011-01-01

287

Early Interfacial Reaction and Formation of Intermetallic Compounds in the Sn-3.5Ag/Cu Soldering System  

NASA Astrophysics Data System (ADS)

The early interfacial reaction in the Sn-3.5Ag/Cu soldering system and the system's premelting behavior were found and characterized by differential scanning calorimetry incorporated into the reflow process. The results show that the early interfacial reaction occurs by way of melting and wetting of the solder layer adjacent to the Cu substrate at a temperature nearly 4C below the actual melting point of Sn-3.5Ag solder due to solid-state diffusion of Cu atoms into the Sn-3.5Ag binary solder. Consequently, the early interfacial reaction brings about formation of Cu-Sn intermetallic compounds (IMCs) at a temperature below the melting point of Sn-3.5Ag, and a prolonged early interfacial reaction can lead to change of the Cu-Sn IMC morphology from planar-like to scallop-like and promote excessive growth of IMCs at the interface.

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

2011-02-01

288

Adaptive composites with embedded NiTiCu wires  

NASA Astrophysics Data System (ADS)

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

Balta, J. Antonio; Michaud, Veronique; Parlinska, Magdelena; Gotthardt, Rolf; Manson, J.-A. E.

2001-07-01

289

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

SciTech Connect

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

Rapp, R.A.

1981-02-01

290

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

PubMed

In Korea, the heavy metal pollution from about 1,000 abandoned mines has been a serious environmental issue. Especially, the surface waters, groundwaters, and soils around mines have been contaminated by heavy metals originating from acid mine drainage (AMD) and mine tailings. So far, AMD was considered as a waste stream to be treated to prevent environmental pollutions; however, the stream contains mainly Fe and Al and valuable metals such as Ni, Zn, and Cu. In this study, Visual MINTEQ simulation was carried out to investigate the speciation of heavy metals as functions of pH and neutralizing agents. Based on the simulation, selective pH values were determined to form hydroxide or carbonate precipitates of Cu, Zn, and Ni. Experiments based on the simulation results show that the recovery yield of Zn and Cu were 91 and 94 %, respectively, in a binary mixture of Cu and Zn, while 95 % of Cu and 94 % of Ni were recovered in a binary mixture of Cu and Ni. However, the recovery yield and purity of Zn and Ni were very low because of similar characteristics of Zn and Ni. Therefore, the mixture of Cu and Zn or Cu and Ni could be recovered by selective precipitation via pH adjustment; however, it is impossible to recover selectively Zn and Ni in the mixture of them. PMID:23754100

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

2013-12-01

291

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

SciTech Connect

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

Margulies, Lawrence

1999-11-08

292

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

PubMed

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

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

2013-07-01

293

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

294

Fabrication and Optical Properties of Low-Emissivity Coatings of AlSiN and AgCuNd-Alloy Multilayer Films on Glass  

NASA Astrophysics Data System (ADS)

Transparent low-emissivity coatings comprised of AlSiN and Ag-alloy multilayer films were investigated. All films were prepared by dc magnetron sputtering. AlSiN/Ag-alloy/AlSiN/Ag-alloy/AlSiN multilayer films were prepared on glass substrates. Three types of Ag-alloys were used: Ag87.5Cu12.5, Ag88Au4.6Cu7.3Ti0.1, and Ag95.8Cu2.2Nd2 films. Thicknesses of the Ag-alloy films were controlled to be in the range of 10-12 nm thick. Compared to the AgCu- and AgAuCuTi-alloys, the AgCuNd-alloy films showed superior optical properties. The maximum transmittance (Tmax) was 85.6% for multilayer coatings with 10-nm-thick Ag95.8Cu2.2Nd2-alloy films. The maximum transmittance is 4 and 7% higher than for the coatings with Ag89.5Au7Cu3Ti0.5- and Ag87.5Cu12.5-alloy films, respectively. In the case of AlSiN (43 nm)/Ag95.8Cu2.2Nd2 (11 nm)/AlSiN (86 nm)/Ag95.8Cu2.2Nd2 (11 nm)/AlSiN (43 nm) multilayer coatings, 79.7% visible light transmission (Tvis) and a shading coefficient of 0.50 were obtained. This indicates that well-balanced transparent low-emissivity coatings with both high visible transparency and good solar infrared shading can be produced for multilayer coatings with the AgCuNd-alloy films.

Chiba, Kiyoshi; Kaminishi, Shota

2008-01-01

295

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

PubMed

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

Onat, Berk; Durukano?lu, Sondan

2014-01-22

296

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

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

297

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

Microsoft Academic Search

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

H. Said

2010-01-01

298

NiFe\\/INSULATOR\\/Cu Composite Wires and Their Giant Magneto-Impedance Effects  

Microsoft Academic Search

In this work, two types of electrodeposited Ni-Fe\\/insulator\\/Cu composite wires, namely Ni-Fe\\/seed layer\\/glass coated copper wire (Composite Wire A), and Ni-Fe\\/seed layer\\/sputtered SiO2\\/Cu (Composite Wire B), have been fabricated and their giant magneto-impedance effects have been investigated. With different implementations of the insulator layer, the magneto-impedance effect of Composite Wire A, whose insulator layer is cast from the melt Pyrex,

N. Ning; J. Fan; J. Wu; H. Chiriac; X. P. Li

2010-01-01

299

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

NASA Astrophysics Data System (ADS)

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

Lin, Yu-Wei; Lin, Kwang-Lung

2010-09-01

300

Enhanced thermomechanical functionality of a laser processed hybrid NiTiNiTiCu shape memory alloy  

Microsoft Academic Search

The exciting thermomechanical behavior of NiTi shape memory alloys (SMAs) has sparked significant research effort seeking to exploit their exotic properties. The performance capabilities of conventional NiTi offerings are limited, however, by current fabrication technologies. In this study, a high power density laser source was implemented to locally alloy Cu into a conventional NiTi material. The effects of laser processing

M Daly; A Pequegnat; Y Zhou; M I Khan

2012-01-01

301

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

Microsoft Academic Search

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

Wendy L. Woods

1997-01-01

302

On the role of Ag in enhancement of Jc in YBa 2Cu 3O 7-? thin films  

NASA Astrophysics Data System (ADS)

The role of Ag in the enhancement of Jc in YBa 2Cu 3O 7-? (YBCO) thin films is investigated. Studies show that the concentration of Ag in laser-ablated films made from YBCO targets containing 1-20 wt.% Ag, is less than 0.1%. Jc has been found to improve with Ag doping by a factor of 8 in the films which were prepared from targets containing 5 wt.% Ag. A theoretical model based on the reduction in the resistive grain-boundary size is proposed to explain the observed enhancement of Jc.

Misra, D. S.; John, Binto; Pinto, R.; Mombasawala, L. S.; Palmer, S. B.

1995-02-01

303

Tribological behaviour and residual stress of electrodeposited Ni\\/Cu multilayer films on stainless steel substrate  

Microsoft Academic Search

In the present study, [Ni (4.5nm)\\/Cu (tCu=2, 4 and 8nm)] multilayers were pulse electrodeposited on stainless steel (AISI SS 304) substrate from sulphate based single bath technique. X-ray diffraction (XRD) was used to investigate the structure and stress of the Ni\\/Cu multilayer. The results from XRD analysis indicated that the deposited multilayers had a preferred crystal orientation of [111] and

S. K. Ghosh; P. K. Limaye; B. P. Swain; N. L. Soni; R. G. Agrawal; R. O. Dusane; A. K. Grover

2007-01-01

304

Effect of the oxygen flow rate on the structure and the properties of AgCuO sputtered films deposited using a Ag\\/Cu target with eutectic composition  

Microsoft Academic Search

AgCuO films were deposited on glass substrates by reactive sputtering of a composite Ag60Cu40 target in various ArO2 mixtures. The films were characterised by energy dispersive X-ray analysis, X-ray diffraction, UVvisible spectroscopy and using the four point probe method. The structure of the films is strongly dependent on the oxygen flow rate introduced in the deposition chamber. The variation of

J. F. Pierson; E. Rolin; C. Clment-Gendarme; C. Petitjean; D. Horwat

2008-01-01

305

Internal stresses induced by plastic shear deformation of Zr(Cu,Ag)Al bulk metallic glasses  

Microsoft Academic Search

Effective internal shear stress ?i induced by torsional deformation of Zr46(Cu4\\/5Ag1\\/5)46Al8 and Zr46Cu46Al8 bulk metallic glasses different by the glass-forming ability of the maternal melts has been determined by measurements of stress relaxation upon stepwise unloading. It has been found that the ratio ?i\\/?0 (?0 is the initially applied shear stress) decreases upon increasing the temperature from ?0.8 at T=450K

G. V. Afonin; S. V. Khonik; R. A. Konchakov; N. P. Kobelev; A. A. Kaloyan; V. A. Khonik

306

Resistive switching mechanism of Ag\\/ZrO 2 :Cu\\/Pt memory cell  

Microsoft Academic Search

Resistive switching mechanism of zirconium oxide-based resistive random access memory (RRAM) devices composed of Cu-doped\\u000a ZrO2 film sandwiched between an oxidizable electrode and an inert electrode was investigated. The Ag\\/ZrO2:Cu\\/Pt RRAM devices with crosspoint structure fabricated by e-beam evaporation and e-beam lithography show reproducible bipolar\\u000a resistive switching. The linear IV relationship of low resistance state (LRS) and the dependence of

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

2011-01-01

307

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

PubMed

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

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

2014-05-21

308

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

309

Thermodynamic Description of the Quaternary Ag-Cu-In-Sn System  

NASA Astrophysics Data System (ADS)

Due to new regulations, the classic Sn-37Pb (wt.%) solder must be replaced by lead-free material. There are many alloys that could be used instead of this classic lead solder, including quaternary Ag-Cu-In-Sn alloy. The CALPHAD method was used for thermodynamic description of this quaternary system. Good agreement between calculation and available experimental information was found. Solidification of the promising lead-free solder Sn-1.5Ag-0.7Cu-9.5In (wt.%) was performed using the Scheil approach, and good agreement between this calculation and differential thermal analysis results was found. The obtained set of Gibbs energy functions can be used in the future for expanding the quaternary system to high-order ones.

Gierlotka, Wojciech

2012-01-01

310

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

USGS Publications Warehouse

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

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

1994-01-01

311

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

PubMed

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

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

2014-02-14

312

Current-driven differential resistance phase diagram in nanopillars of NiFe/Cu/NiFe  

NASA Astrophysics Data System (ADS)

In 1996, Slonczewski [J. Magn. Magn. Mater. 159 (1996) 1] and Berger [Phys. Rev. B 54 (1996) 9353] predicted that the magnetization of a thin film can be reversed by spin transfer from a spin-polarized current injected into the film. This effect can be experimentally observed by magnetoresistive measurements. In this work we present a current-driven differential resistance phase diagram for nanopillars of NiFe/Cu/NiFe prepared by e-beam lithography, with lateral dimensions 50 nm125 nm. This diagram is obtained by measuring the resistance versus current at constant applied field. We estimated several distinguishable magnetic states as function of both current and magnetic field. Switchings, valleys and peaks can be observed in dV/dI experiments. This behavior is related to the change of the magnetic states induced by a spin-polarized current.

Pereira, L. G.; Boulle, O.; Sanchez, M. M.; Cros, V.; Petroff, F.; Fert, A.

2006-10-01

313

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

NASA Technical Reports Server (NTRS)

The microstructure and mechanical properties of the ultrahigh strength Al-Cu-Li-Ag-Mg alloy, Weldalite (tm) 049, were studied. Specifically, the microstructural features along with tensile strength, weldability, Young's modulus and fracture toughness were studied for Weldalite (tm) 049 type alloys with Li contents ranging from 1.3 to 1.9 wt. pct. The tensile properties of Weldalite 049 and Weldalite 049 reinforced with TiB2 particles fabricated using the XD (tm) process were also evaluated at cryogenic, room, and elevated temperatures. In addition, an experimental alloy, similar in composition to Weldalite 049 but without the Ag+Mg, was fabricated. The microstructure of this alloy was compared with that of Weldalite 049 in the T6 condition to assess the effect of Ag+Mg on nucleation of strengthening phases in the absence of cold work.

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

1991-01-01

314

Investigation of the effect of indium addition on wettability of Sn-Ag-Cu solders  

Microsoft Academic Search

Purpose The purpose of this paper is to investigate the influence of In additions on the wetting properties of the Sn2.86Ag0.40Cu (in wt%) eutectic-based alloys, on a copper substrate, in the presence of a flux. The main goal was to find correlations between the results of the wetting balance (WB) and the sessile drop (SD) method, in relation to

Z. Moser; P. Fima; K. Bukat; J. Sitek; J. Pstru?; W. G?sior; M. Ko?cielski; T. Gancarz

2011-01-01

315

Effect of indium on wettability of SnAgCu solders. Experiment vs. modeling, Part I  

Microsoft Academic Search

The density and surface tension measurements of the Sn3.13Ag0.74Cu liquid alloys with 2, 3, 4, 15, 30, 50 and 75 at.% In additions were conducted in the temperature range from 431 K up to 1209K by dilatometric technique and the maximum bubble pressure method, respectively. The results obtained in both techniques exhibited 2%3% scattering of experimental errors, similarly to the

Zbigniew Moser; Pavol Sebo; W?adys?aw G?sior; Peter Svec; Janusz Pstru?

2009-01-01

316

Stress-induced and atomic ordering in 18-carat AuCuAg alloys  

Microsoft Academic Search

Atomic ordering and stress-induced ordering (Zener relaxation) were studied in a series of 18-carat (75wt%) yellow gold alloys (AuCuAg) by means of isothermal mechanical spectroscopy with a forced torsion pendulum at low frequencies. In the high-temperature solid solution, the Zener peak increases critically according to a CurieWeiss type law when approaching the transition temperature to the ordered phase from above,

John Hennig; Daniele Mari; Robert Schaller

2009-01-01

317

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

Microsoft Academic Search

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

Jens T. Darsell; K. Scott Weil

2006-01-01

318

Microstructural evolution of lead-free Sn-Bi-Ag-Cu SMT joints during aging  

Microsoft Academic Search

It was reported in a previous study that the Sn-6Bi-2Ag-0.5Cu solder alloy had great potential to replace leaded alloys. This alloy was prepared by mechanical alloying, and had the advantage of providing a high percentage of supersaturate solution of bismuth in tin. In the present paper, the microstructural evolution of surface-mount joints during aging was examined. In the as-soldered joints,

C. M. Lawrence Wu; Mingliang L. Huang

2005-01-01

319

Temperature dependence of the electron and ion induced electron emission yield of Al, Cu and Ag  

Microsoft Academic Search

The electron emission yield was measured for impact of 3 keV electrons, 2 MeV H+, 4 MeV He2+ and 6 MeV O3+ ions on polycrystalline Al, Cu and Ag samples as a function of sample temperature in the temperature range of 25450 C. A significant influence of the surface morphology was found. For annealed samples, a linear decrease of the

O. Benka; M. Steinbatz

2003-01-01

320

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

PubMed

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

Yang, X

1997-06-01

321

Photo and electroluminescence properties in Zns: (Cu, La) and Zns: (Ag, La) phosphors  

Microsoft Academic Search

A method for preparation of ZnS: (Cu, La) and ZnS: (Ag, La) phosphors is described. Photo and electroluminescence of these\\u000a phosphors have been studied. The voltage and frequency variation of EL brightness have also been reported. The results agree\\u000a with the collision-excitation mechanism in the Schottky barrier. The emission of blue, green and yellow bands has been interpreted\\u000a in terms

L N Tripathi; B R Chaubey; C P Mishra

1981-01-01

322

Linear and nonlinear optical properties of metal nanocluster-silica composites formed by sequential implantation of Ag and Cu  

SciTech Connect

Nanometer dimension metal colloids were formed in silica by sequential implantation of Ag and Cu ions. The Ag and Cu were implanted with relative ratios of Ag to Cu of 9:3, 6:6, and 3:9. The total nominal dose was 12 {times} 10{sup 16} ions/cm{sup 2}. TEM techniques were used to examine colloid size and size distributions. The linear optical response was measured from 200 to 900 nm. The nonlinear optical properties were measured using the z-scan technique at a wavelength of 570 nm. The linear and nonlinear optical properties were found to be dependent upon the relative ratio of sequentially implanted Ag to Cu. The results are consistent with effective medium theory.

Zuhr, R.A. [Oak Ridge National Lab., TN (United States); Magruder, R.H. III; Anderson, T.A.; Osborne, D.O. Jr. [Vanderbilt Univ., Nashville, TN (United States)

1994-12-01

323

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

324

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

SciTech Connect

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

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

2007-02-02

325

Facile synthesis of bimetallic Ag/Ni core/sheath nanowires and their magnetic and electrical properties.  

PubMed

This paper describes a facile method for coating Ag nanowires with uniform, ferromagnetic sheaths made of polycrystalline Ni. A typical sample of these core/sheath nanowires had a saturation magnetization around 33 emu g(-1). We also demonstrated the use of this magnetic property to align the nanowires by simply placing a suspension of the nanowires on a substrate in a magnetic field and allowing the solvent to evaporate. The electrical conductivity of these core/sheath nanowires (2 10(3) S cm(-1)) was two orders of magnitude lower than that of bulk Ag (6.3 10(5) S cm(-1)) and Ni (1.4 10(5) S cm(-1)). This is likely caused by the transfer of electrons from the Ag core to the Ni sheath due to the difference in work function between the two metals. The electrons are expected to experience an increased resistance due to spin-dependent scattering caused by the randomized magnetic domains in the polycrystalline, ferromagnetic Ni sheath. Studies on the structural changes to the Ni coating over time under different storage conditions show that storage of the nanowires on a substrate under ambient conditions leads to very little Ni oxidation after 6 months. These Ag/Ni core/sheath nanowires show promise in areas such as electronics, spintronics, and displays. PMID:20677185

McKiernan, Maureen; Zeng, Jie; Ferdous, Sunzida; Verhaverbeke, Steven; Leschkies, Kurtis S; Gouk, Roman; Lazik, Christopher; Jin, Miao; Briseno, Alejandro L; Xia, Younan

2010-09-01

326

Effect of additive metals, Sn, Ga, and In in Ag-Pd-Au-Cu alloys on initial bond strength of 4META adhesive cement to these alloys  

Microsoft Academic Search

The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au- Cu alloys consisted of 20%, 30% or 40%Pd, and 10%, 15% or 20%Cu, 20%Au, and Ag as

Shin-ichi GOTO; Pornkiat CHURNJITAPIROM; Yukio MIYAGAWA; Hideo OGURA

2008-01-01

327

Corrosion behaviour assessment of lead-free SnAgM (M = In, Bi, Cu) solder alloys  

Microsoft Academic Search

The corrosion behaviour of lead-free Sn88.7Ag2.3In9.0, Sn86.6Ag3.0Bi10.4, Sn96.1Ag3.1Cu0.8 and Sn90.4Ag2.9Cu6.7 solder alloys was investigated in 0.1M NaCl solution and compared with that of the conventional eutectic Sn73.9Pb26.1 solder. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) were used to characterize the samples prior and after the electrochemical tests. Potentiodynamic polarization curves show that Sn88.7Ag2.3In9.0 and Sn86.6Ag3.0Bi10.4 solders exhibit poor

F. Rosalbino; E. Angelini; G. Zanicchi; R. Marazza

2008-01-01

328

Preferential nucleation and high mobility of linear Cu trimers on Ag(111)  

NASA Astrophysics Data System (ADS)

Using scanning tunneling microscopy, we studied the formation of dimers, trimers, and other clusters of Cu on Ag(111) at low temperature. We show that trimers, once formed, have significantly higher mobilities than either atoms or dimers. While transient, this mobility makes linear trimers a major contributor to mass transport. Using the scanning tunneling microscopy tip, we constructed linear and compact trimers at 5 K and investigated their stabilities and diffusion parameters as a function of temperature. Analysis shows that the diffusion barrier for linear trimers is very low, 13.6 meV, compared to 65 meV for atoms, while the compact trimer is stable and immobile. Thus, significant diffusion of this nonequilibrium cluster can occur before the equilibrium compact trimer is reached. The details of trimer diffusion and rotation provide insights into the intermediate diffusion steps and indicate that the large lattice mismatch plays an important role. The properties of Cu trimers on Ag(111) contrast with those reported for homoepitaxial trimers on fcc(111) surfaces. Because the diffusion phenomena for Cu trimers and other clusters on Ag(111) are largely a result of lattice mismatch, similar phenomena may exist in the early stages of nucleation and growth of other heteroepitaxial systems.

Signor, A. W.; Weaver, J. H.

2011-10-01

329

Energetics of small clusters of group IB metals (Cu, Ag, and Au) adsorbed on graphene  

NASA Astrophysics Data System (ADS)

The 2D structure of graphene maximizes the interaction of adsorbate on the layer. Many experiments have been devised to form stable metallic clusters of different sizes. We study the structure and binding energies of group IB clusters Mn (M=Au, Ag, Cu n=1, 3) adsorbed on graphene using Gupta potential [1] (for M-M interaction) and Lennard-Jones potential [2] (for metal-carbon interaction). The total energy of the system has been obtained by placing each of Mn cluster a certain distance above the graphene sheet at various positions and in various orientations. The minimized energy configurations, for all Mn clusters, lie above the center of a hexagon and parallel to the graphene sheet. Binding energy per atom for Ag and Cu metal clusters are less than those of respective Au indicating the lower stability of Ag/Cu metal-graphene system. Using various energy barriers, we can calculate the energy required to move small cluster from one position of minimum energy to another on graphene.

Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

2013-06-01

330

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

PubMed

In this study, the corrosion resistance of Ag-Au-Cu-Pd system alloys consisting of 5 or 10 mass% indium was evaluated. Levels of element release and tarnish were determined and electrochemical measurements performed. Results were compared with those for commercial silver-palladium-gold alloy. In terms of electrochemical behavior, the transpassive potential of these experimental alloys was 168-248mV. Experimental alloys with 25 mass% Au showed similar corrosion resistance to control gold-silver-palladium alloy. Amount of released elements was 14-130microg/cm(2) at 7 days, which is in the allowable range for dental alloys. Addition of indium to Ag-Au-Cu-10mass%Pd system alloys was effective in increasing resistance to tarnish and alloys containing 10 mass% of indium showed a minimal decrease in L(*) values after immersion. These findings indicate that 25Au-37.5Ag-15Cu-10Pd-2Zn-10In-0.5Ir alloy is applicable in dental practice. PMID:20574129

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

2010-01-01

331

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

NASA Astrophysics Data System (ADS)

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

Kumar, Aditya; Chen, Zhong

2011-02-01

332

Nearly constant electrical resistance over large temperature range in Cu3NMx (M = Cu, Ag, Au) compounds.  

PubMed

Electrical resistance is a material property that usually varies enormously with temperature. Constant electrical resistivity over large temperature range has been rarely measured in a single solid. Here we report the growth of Cu3NMx (M = Cu, Ag, Au) compound films by magnetron sputtering, aiming at obtaining single solids of nearly constant electrical resistance in some temperature ranges. The increasing interstitial doping of cubic Cu3N lattice by extra metal atoms induces the semiconductor-to-metal transition in all the three systems. Nearly constant electrical resistance over 200?K, from room temperature downward, was measured in some semimetallic Cu3NMx samples, resulting from opposite temperature dependence of carrier density and carrier mobility, as revealed by Hall measurement. Cu3NAgx samples have the best performance with regard to the range of both temperature and doping level wherein a nearly constant electrical resistance can be realized. This work can inspire the search of other materials of such a quality. PMID:24169599

Lu, Nianpeng; Ji, Ailing; Cao, Zexian

2013-01-01

333

Template synthesis of M\\/M 2S (M = Ag, Cu) hetero-nanowires by electrochemical technique  

Microsoft Academic Search

Metal chalcogenide-based mixed ionicelectronic conductors such as Ag2S and Cu2S can be specifically architected for application in nanoelectronic devices. We present a template-confined synthesis of metal chalcogenide (e.g., Ag2S, Cu2S) nanowires for mixed conductor-based nanoelectronics. First, the metal nanowire array was electroplated into pores of a porous alumina membrane. Anodic polarization was then used to transform the metal into the

Changhao Liang; Kazuya Terabe; Tsuyoshi Hasegawa; Masakazu Aono

2006-01-01

334

Skin-resolved local bond contraction, core electron entrapment, and valence charge polarization of Ag and Cu nanoclusters.  

PubMed

Consistency between density functional theory (DFT) calculations and experimental observations confirmed our predictions on the behaviour of local bonds, and the electron binding energy of cuboctahedral and Marks decahedral structures of Ag and Cu nanoclusters. The shorter and stronger bonds between under-coordinated atoms cause local densification and quantum entrapment of the core electrons, which polarize the otherwise conducting electrons (valence electrons). Such strong localization may result in extraordinary catalytic and plasmonic properties in Ag and Cu nanoclusters. PMID:24691894

Ahmadi, Shideh; Zhang, Xi; Gong, Yinyan; Chia, Chin Hua; Sun, Chang Q

2014-05-21

335

Shear deformation in Sn3.5Ag and Sn3.6Ag1.0Cu solder joints subjected to asymmetric four-point bend tests  

Microsoft Academic Search

The shear deformation behavior of two lead-free solder compositions, Sn-3.5Ag (wt.%) and Sn-3.6Ag-1.0Cu (wt.%), both on copper substrates, was studied using an asymmetric four point bend technique. Four test joints were obtained from one master specimen of each composition, and each joint was subject to progressive loading, up to the maximum shear strength of the joint. One unstressed bar from

B. A. Cook; I. E. Anderson; J. L. Harringa; R. L. Terpstra; J. C. Foley; . nal; F. C. Laabs

2001-01-01

336

Complete oxidation of methane over Ag- and Cu-modified cerium and zirconium oxides  

NASA Astrophysics Data System (ADS)

Low temperature oxidation of methane is an area in catalysis that, despite the large number of catalytic systems studied, does not yet have an adequate solution. The exhaust gas from natural gas burning devices (gas turbines and natural gas vehicles), contains unconverted methane which is emitted into the atmosphere (currently unregulated). Methane is the most refractory of all hydrocarbons, and its activation requires temperatures higher than the typical exhaust temperatures (350-400spC). In this work, ceria- and zirconia-supported Ag and CuO catalysts were studied for the complete oxidation of methane. Catalysts were typically tested under excess oxygen and high space velocity (72,000 hsp{-1}). The reaction kinetics were measured over selected catalysts. Hsb2- and CHsb4- TPR and oxygen uptake measurements were used to characterize the catalyst reduction properties. XRD, STEM/EDX and HRTEM were used to characterize the catalyst structure. The oxidation state of various active species present was identified by XPS and UV-VIS DR spectrometry. Ceria- and zirconia-supported Ag and CuO catalysts are very active and stable catalysts for the complete oxidation of carbon monoxide and methane. When ceria is used as an active catalyst support, its activity depends strongly on its structure. Nanocrystalline ceria, stabilized by dopants such as La or Zr, is highly reducible and structurally defective. Our results indicate that surface oxygen species present under reaction conditions are the active sites for methane activation. Activity in the complete oxidation of methane is related to ceria crystal size and reducibility of surface oxygen species. The addition of a transition metal (Ag) or a metal oxide (CuO) in low amounts increases the low temperature reducibility of ceria and enhances the catalyst oxidation activity. On the other hand, both Ag and CuO are active catalysts for the complete oxidation of methane. These were studied separately on inert zirconia support. A strong correlation of the transition metal/metal oxide state and dispersion with the catalyst activity was observed. Isolated Ag ions and small Ag nanoparticles (<5 nm) are both poor catalysts for the complete oxidation of methane. The turnover frequency for methane oxidation was increased by an order of magnitude as the Ag particle size increased from 5 to 10 nm, as seen by HRTEM. Similar catalytic behavior was found in copper oxide-containing zirconia. Small copper clusters (few nm) which are highly defective and do not have the identity of CuO are less active than larger CuO particles for the complete oxidation of methane. In view of the importance of surface oxygen species in methane activation, the observed structure sensitivity of methane oxidation in both the supported metal (Ag) and metal oxide (CuOx) systems is discussed in terms of oxygen adsorption on the metal and reduction properties of the metal oxide, respectively.

Kundakovic, Ljiljana

337

Ni+7 Ion Beam Effect on Ag Doped ZnS Nanocrystals Embedded in PMMA Matrix  

NASA Astrophysics Data System (ADS)

Semiconductor nanocrystals (NCs) have received much interest for their optical and electronic properties. When these NCs dispersed in polymer matrix, brightness of the light emission is enhanced due to their quantum dot size. Silver doped Zinc Sulphide NCs were synthesized through chemical route method. The synthesized NCs are characterized by XRD. The effect of Ag doping and Swift heavy ion irradiation on optical properties of nanocomposite polymer films is analyzed by Photoluminescence (PL) and UV measurements. The XRD results show that Ag doped ZnS was grown in the hexagonal phase of about 10 nm size as calculated by Scherer formula. These NCs were dispersed in PMMA matrix by solution cast method and irradiated by swift heavy ion (SHI) (Ni+7 ion beam, 100 MeV). The UV-Vis measurement show a red shift in optical absorption and band gap decreases after irradiation with respect to pristine nanocomposite polymer film. Photoluminescence shows the enhancement in luminescence intensity after irradiation.

Agrawal, Shweta; Tripathi, Balram; Kumar, Sumit; Jain, Vipin; Srivastava, Subodh; Vijay, Y. K.

2011-07-01

338

Secondary ion emission from Ti, V, Cu, Ag and Au surfaces under KeV Cs + irradiation  

Microsoft Academic Search

Low energy mono-atomic singly charged secondary ion emissions from Ti, V, Cu, Ag and Au substrates during the initial stages of sputtering with Cs+ primary ions have been studied. With the exception of the Ag? secondary ions, all exhibited exponential like correlations with the Cs induced work function changes. This, along with the lack of variations in the valence band

P. A. W. van der Heide

2005-01-01

339

Hyperfine nuclear interaction at copper lattice sites of high-temperature superconductors studied by 61 Cu( 61 Ni) Mssbauer emission spectroscopy  

Microsoft Academic Search

Mssbauer emission spectroscopy on the 61Cu(61Ni) isotope has been used to determine the quadrupole coupling constant C(Ni) and magnetic induction B(Ni) for the 61Ni2+ probe at copper sites in Cu2O, CuO, La2 ?x\\u000a BaxCuO4, Nd2?x\\u000a CexCuO4, RBa2Cu3O6, and RBa2Cu3O7 (R=Y, Nd, Gd, Yb). The compounds containing divalent copper were found to exhibit linear C(Ni) vs. C(Cu) and B(Ni) vs. B(Cu)

S. A. Nemov; P. P. Seregin; N. P. Seregin; A. V. Davydov

2004-01-01

340

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

NASA Technical Reports Server (NTRS)

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

Lach, Cynthia L.; Domack, Marcia S.

2003-01-01

341

Characteristic of TiNi(Cu) shape memory thin film based on micropump  

NASA Astrophysics Data System (ADS)

Shape memory thin films offer a unique combination of novel properties and have the potential to become a primary actuating mechanism for micropumps. In this study, a micropump driven by TiNiCu shape memory thin film is designed and fabricated. The micropump is composed of a TiNiCu/Si bimorph driving membrane, a pump chamber and two inlet and outlet check valves. The property of TiNiCu films and driving capacity of TiNiCu/Si bimorph driving membrane are investigated. By using the recoverable force of TiNiCu thin film and biasing force of silicon membrane, the actuation diaphragm realizes reciprocating motion effectively. Experimental results show that the film surface appears a smooth and featureless morphology without any cracks, and the hysteresis width ?T of TiNiCu film is about 2-3C, the micropump driving by TiNiCu film has good performance, such as high pumping yield, high working frequency, stable driving capacity, and long fatigue life time.

Zhang, Huijun; Qiu, Chengjun

2009-07-01

342

Effects of Surface Finishes and Current Stressing on Interfacial Reaction Characteristics of Sn-3.0Ag-0.5Cu Solder Bumps  

NASA Astrophysics Data System (ADS)

The effects of surface finishes on the in situ interfacial reaction characteristics of ball grid array (BGA) Sn-3.0Ag-0.5Cu lead-free solder bumps were investigated under annealing and electromigration (EM) test conditions of 130C to 175C with 5.0 103 A/cm2. During reflow and annealing, (Cu,Ni)6Sn5 intermetallic compound (IMC) formed at the interface of electroless nickel immersion gold (ENIG) finish. In the case of both immersion Sn and organic solderability preservative (OSP) finishes, Cu6Sn5 and Cu3Sn IMCs formed. Overall, the IMC growth velocity of ENIG was much lower than that of the other finishes. The activation energies of total IMCs were found to be 0.52 eV for ENIG, 0.78 eV for immersion Sn, and 0.72 eV for OSP. The ENIG finish appeared to present an effective diffusion barrier between the Cu substrate and the solder, which leads to better EM reliability in comparison with Cu-based pad systems. The failure mechanisms were explored in detail via in situ EM tests.

Kim, Jae-Myeong; Jeong, Myeong-Hyeok; Yoo, Sehoon; Park, Young-Bae

2012-04-01

343

Comparing the magnetic property of shell thickness controlled of Ag-Ni core-shell nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, we studied the critical diameter of superparamagnetic core-shell particles. One pot method and microwave-assisted technique were used to synthesize Ag-Ni core-shell nanoparticles with diameters of 10 nm and 30 nm. From the experimental results of hysteresis (M-H curves) and temperature dependent magnetization (M-T curves), the theoretical critical diameter does not agree with the experimental observation of the core-shell structure. Furthermore, the blocking temperature equation should be reconsidered.

Ger, Tzong-Rong; Huang, Hao-Ting; Huang, Chen-Yu; Liu, Wan-Chih; Lai, Jun-Yang; Liu, Bo-Tau; Chen, Jiann-Yeu; Hong, Che-Wun; Chen, Pao-Jen; Lai, Mei-Feng

2014-05-01

344

Evidence of Mobile Ag and Growth Mechanism of YBa2Cu3O7-y Films Deposited on Cube Textured Ag Tape by Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

YBa2Cu3O7-y (YBCO) films were prepared on {100}< 001> cube textured Ag tape (CUTE-Ag tape) by metal organic chemical vapor deposition (MOCVD) using a liquid state metal organic (MO) source. Numerous spiral steps accompanied by screw dislocations were observed and many particles were observed on the terrace surface of the spiral steps by atomic force microscopy (AFM). We observed a change in surface morphology before and after heat treatment in vacuum at 550C. After heat treatment, these particles became smaller and concentrated at the edge of the spiral steps. We confirmed by scanning Auger microscopy that the main composition of these particles was Ag. We propose a growth mechanism on a Ag substrate in which Ag segregates to the surface and acts as surfactant for YBCO growth.

Hasegawa, Masato; Yoshida, Yutaka; Iwata, Morihiro; Akata, Hiroyuki; Higashiyama, Kazutoshi; Takai, Yoshiaki; Hirabayashi, Izumi

2000-04-01

345

Magnetic structure of the metallic triangular antiferromagnet Ag2NiO2.  

PubMed

The magnetic structure of the metallic antiferromagnet Ag2NiO2 with the Nel temperature TN=56K has been investigated by means of a neutron diffraction technique using a powder sample in the temperature range between 5 and 65K. The antiferromagnetic (AF) diffraction peaks are clearly observed below TN and can be indexed with the propagation vector [Formula: see text]. Based on the results of both a representational analysis and a Rietveld refinement of the magnetic peaks, the AF spin structure is determined as an A-type AF structure with ml=m0cos(2?k ?l), where ml is the moment at the lth Ni(3+) site and m0=(0.31,0,0.65)?B at 5K. PMID:23793164

Nozaki, Hiroshi; Mnsson, Martin; Roessli, Bertrand; Pomjakushin, Vladimir; Kamazawa, Kazuya; Ikedo, Yutaka; Fischer, Henry E; Hansen, Thomas C; Yoshida, Hiroyuki; Hiroi, Zenji; Sugiyama, Jun

2013-07-17

346

High-pressure synthesis of novel hydride in MgNiH and MgNiCuH systems  

Microsoft Academic Search

Novel hydrides were synthesized in MgNiH and MgNiCuH systems by high-pressure technique using a cubic-anvil-type apparatus. Crystal structure and thermal stability of the hydrides were studied. The novel hydride with a composition of MgNi2Hy was synthesized at 973K for 2h under the pressure of over 2GPa. This hydride could be synthesized from each starting material, such as MgNi2(C36) and mixture

Riki Kataoka; Yasuyuki Goto; Atsunori Kamegawa; Hitoshi Takamura; Masuo Okada

2007-01-01

347

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

SciTech Connect

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

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

1990-01-01

348

Thermal behavior and microstructure of the intermetallic compounds formed at the Sn 3Ag 0.5Cu/Cu interface after soldering and isothermal aging  

NASA Astrophysics Data System (ADS)

The thermal behavior and microstructure of the intermetallic compounds formed at the Sn-3Ag-0.5Cu/Cu interface after soldering at 250 C for 60 s and aging at 150 C for various times have been investigated by using differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and pull-off testing. The DSC result shows that the solidus and liquidus temperatures of the Sn-3Ag-0.5Cu solder alloy are 217 and 221 C, respectively. The melting range of the Sn-3Ag-0.5Cu is 4 C smaller than 8.5 C for the Sn-37Pb solder alloy. The major intermetallic compounds are monoclinic ?'-Cu 6Sn 5, hexagonal ?-Cu 6Sn 5 and Ag 3Sn when aged at 150 C for 0-300 h. When aged for 100-300 h, the morphology of Cu 6Sn 5 transforms from scallop-shaped to planar. The thickness of Cu 6Sn 5 increases from 4.10.4 to 7.80.3 ?m when aging time increases from 0 to 300 h. The maximum and minimum adhesion strengths are 12.440.53 and 2.220.46 MPa, respectively, for as-soldered and aged (150 C for 300 h) ones.

Liu, Chih-Yao; Lai, Chien-Hong; Wang, Moo-Chin; Hon, Min-Hsiung

2006-04-01

349

Electrical characterization of the organic semiconductor Ag/CuPc/Au Schottky diode  

NASA Astrophysics Data System (ADS)

This paper reports on the fabrication and investigation of a surface-type organic semiconductor copper phthalocyanine (CuPc) based diode. A thin film of CuPc of thickness 100 nm was thermally sublimed onto a glass substrate with preliminary deposited metallic electrodes to form a surface-type Ag/CuPc/Au Schottky diode. The current-voltage characteristics were measured at room temperature under dark conditions. The barrier height was calculated as 1.05 eV The values of mobility and conductivity was found to be 1.74 10-9 cm2 (V s) and 5.5 10-6 ?-1 cm-1, respectively. At low voltages the device showed ohmic conduction and the space charge limited current conduction mechanisms were dominated at higher voltages.

Shah, Mutabar; Sayyad, M. H.; Karimov, Kh. S.

2011-04-01

350

Effect of substrate temperature on the structural, electrical and optical behaviour of reactively sputtered Ag-Cu-O films  

NASA Astrophysics Data System (ADS)

Thin films of Ag-Cu-O were deposited on glass substrates by radio frequency magnetron sputtering of an Ag70Cu30 target at an oxygen partial pressure of 210-2 Pa, a sputter pressure of 4 Pa and at different substrate temperatures in the range 303-548 K. The deposited films were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, atomic force microscopy, ultraviolet-visible-infrared spectroscopy and four-probe techniques. The effect of substrate temperature on the core-level binding energies, crystallographic structure, surface morphology and electrical and optical properties of the deposited films was systematically studied. The films formed at room temperature (303 K) showed a core-level binding energy of Ag 3d5/2 of 367.9 eV due to the growth of single-phase Ag2Cu2O3 films, whereas those deposited at 523 K exhibited a lower energy value of 367.2 eV due to the presence of silver, silver oxides and copper oxide. The films formed at room temperature were nanocrystalline Ag2Cu2O3. The substrate temperature induced growth of a mixed phase of Ag2Cu2O3 and Ag2Cu2O4 in the temperature range 348-473 K. At higher temperatures the films were decomposed into silver and silver oxide. The electrical resistivity of the films decreased from 8.2 to 0.6 ? cm with an increase in substrate temperature from 303 to 548 K due to an improvement in crystallinity and structural changes in the films. The optical band gap of the Ag-Cu-O films increased from 1.95 to 2.15 eV with an increase in substrate temperature from 303 to 523 K, whereas at a higher temperature of 548 K it decreased to 2.11 eV.

Prasad Reddy, M. Hari; Narayana Reddy, P.; Sreedhar, B.; Pierson, J. F.; Uthanna, S.

2011-10-01

351

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

NASA Astrophysics Data System (ADS)

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

Varalaxmi, N.; Sivakumar, K. V.

2013-10-01

352

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

353

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

SciTech Connect

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.

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

2005-01-01

354

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

Microsoft Academic Search

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

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

1997-01-01

355

Pulsed laser deposition of the NiTiCu thin film alloy  

NASA Astrophysics Data System (ADS)

Ni-Ti-Cu alloy present different properties: shape memory effect, super-elasticity and biocompatibility which allow it to be used in different fields: from biomedical to micro electro mechanical systems. It is complex to obtain these properties in thin films of Ni-Ti-Cu alloy deposited on Si substrates. In this work preliminary results, in situ X-ray fluorescence data, ex situ X-ray diffraction data of Ni-Ti-Cu thin film will be reported. These measurements will allow to control the correct growth of the thin film alloy produced by laser deposition.

Morone, A.

2007-07-01

356

Effects of heating temperature and atmosphere on critical current density of Bi2Sr2Ca1Cu2Ag 0.8Oy Ag-sheathed tapes  

Microsoft Academic Search

In partial melt processing of Bi2Sr2Ca1 Cu2Ag0.8Oy silver sheathed tapes, the effects of heating temperature and atmosphere on the critical current density, Jc, were studied. It was found that Jc is higher for the samples treated in pure oxygen than those in air and has the maximum value at a heating temperature of 885C. During partial melting, nonsuperconducting Sr-Ca-Cu-O precipitates

A. Endo; S. Nishikida

1993-01-01

357

Structure and mechanical properties of Cu-X (X = Nb,Cr,Ni) nanolayered composites  

Microsoft Academic Search

Sputtered Cu\\/Cr and Cu\\/Nb multilayers have polycrystalline microstructures with nanometer scale grain sizes, while Cu\\/Ni multilayers evaporated on single crystal Cu or NaCl were single crystalline. The hardness of the multilayers for layer thicknesses (h) > 50 nm is explained by Hall-Petch model with grain boundaries and interfaces as barriers. At h < 50 nm, a deviation from the Hall-Petch

A. Misra; M. Verdier; Y. C. Lu; H. Kung; T. E. Mitchell; M. Nastasi; J. D. Embury

1998-01-01

358

Increased critical current density and pinning in thick Ag/YBa 2Cu 3O 7-x multilayers  

NASA Astrophysics Data System (ADS)

We have investigated the superconducting properties of Ag/YBa 2Cu 3O 7-x thick multilayers grown by Pulsed Laser Deposition, and found that the artificial pinning centres induced by Ag nanodots lead to a significant increase in critical current, especially in high applied magnetic fields. Transmission Electron Microscopy showed a columnar growth of YBa 2Cu 3O 7-x induced by Ag nanodots, while angle-dependent transport measurements revealed the existence of strong, both isotropic and c-axis correlated, artificial pinning centres.

Dang, V. S.; Mikheenko, P.; Sarkar, A.; Awang Kechik, M. M.; Abell, J. S.; Crisan, A.

2010-11-01

359

The effect of Ag and Cu underlayer on the L1 0 ordering FePt thin films  

Microsoft Academic Search

The magnetic properties and structure of FePt, FePt\\/Ag and FePt\\/Cu thin films have been studied. After annealed at 350C for 1h, the FePt and FePt\\/Cu films are FCC disordered, and FePt\\/Ag thin film has a high in-plane coercivity (6236Oe). It is indicated that Ag underlayer is able to reduce the ordering temperature of FePt films. After annealed at 550C for

Xiao-Hong Xu; Hai-Shun Wu; Fang Wang; Xiao-Li Li

2004-01-01

360

Kinetics of interfacial reaction between eutectic Sn-Pb solder and Cu\\/Ni\\/Pd metallizations  

Microsoft Academic Search

The interfacial microstructure and the kinetics of interfacial reaction between the eutectic Sn-Pb solder and electroplated\\u000a Ni\\/Pd on Cu substrate (Cu\\/Ni\\/NiPd\\/Ni\\/Pd) were studied both in the liquid- and solid-state of the solder. The liquidstate reaction\\u000a was carried out at 200C, 225C, and 250C for 30 s, 60 s, 150 s, and 300 s at each temperature. The solid-state aging was

G. Ghosh

1999-01-01

361

Electromigration-induced cracks in Cu/Sn3.5Ag/Cu solder reaction couple at room temperature  

NASA Astrophysics Data System (ADS)

Electromigration (EM) behavior of Cu/Sn3.5Ag/Cu solder reaction couple was investigated with a high current density of 5 103 A/cm2 at room temperature. One dimensional structure, copper wire/solder ball/copper wire SRC was designed and fabricated to dissipate the Joule heating induced by the current flow. In addition, thermomigration effect was excluded due to the symmetrical structure of the SRC. The experimental results indicated that micro-cracks initially appeared near the cathode interface between solder matrix and copper substrate after 474 h current stressing. With current stressing time increased, the cracks propagated and extended along the cathode interface. It should be noted that the continuous Cu6Sn5 intermetallic compounds (IMCs) layer both at the anode and at the cathode remained their sizes. Interestingly, tiny cracks appeared at the root of some long column-type Cu6Sn5 at the cathode interface due to the thermal stress.

Hongwen, He; Guangchen, Xu; Fu, Guo

2009-03-01

362

Performance of density functional methods. Some difficult cases for small systems containing Cu, Ag, or Au.  

PubMed

Twenty-six density functional theory (DFT) methods were tested in conjunction with three different effective core potentials (ECPs) and their corresponding valence basis sets, for studying the behavior of DFT methods in small systems containing Cu, Ag, or Au where it is well-known that some functionals fail. The DFT results were compared with those obtained with post Hartree-Fock methods: second-order many-body perturbation theory (MP2), coupled cluster singles-doubles (CCSD), and coupled cluster singles-doubles with perturbative triples, CCSD(T). Calculations were carried for M3 (M = Cu, Ag, Au); M4(-), (M = Cu, Ag) and [H2O-Cu](+2). The comparison of the DFT calculated values with the Post Hartree-Fock values showed that, in general, all generalized gradient approximation (GGA) type functionals fail to describe these systems. The hybrid GGA functionals (H-GGA) showed a better behavior; however, when the Lee-Yang-Parr (LYP) exchange-correlation functional was used, wrong results were obtained. The results with the hybrid meta (HM-GGA) functionals, as in the case of H-GGAs, showed that, to obtain similar results to MP2 or CCSD(T), it is necessary to have a high Hartree-Fock exchange percentage. Spurious results obtained with the H-GGA or HM-GGA methods can be eliminated increasing the Hartree-Fock exchange percentage in the H-GGA or HM-GGA type functionals. Among the different functionals tested, the BB1K and MPWB1K functionals showed the best agreement with the MP2 and CCSD(T) results. PMID:23465056

Sierraalta, Anibal; Aez, Rafael; Alejos, Paola

2013-03-28

363

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

364

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)

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.

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

2012-11-01

365

Corrosion of Cu-Ni alloys in sulfide-polluted seawater  

SciTech Connect

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

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

1993-10-01

366

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

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

367

Lateral band formation and hybridization in molecular monolayers: NTCDA on Ag(110) and Cu(100)  

NASA Astrophysics Data System (ADS)

The adsorption of aromatic molecules on metal surfaces leads to a complex reorganization of the molecular and metal wave functions. Various processes such as charge transfer, hybridization between molecular and metallic states, and the formation of dispersing bands within the interface have been demonstrated for organometallic interface systems. For the model molecule 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), we compare highly ordered monolayers on Ag(110) and Cu(100), which allows us to identify changes of the interfacial electronic structure when altering the coupling strength with the substrate by means of angle-resolved photoelectron spectroscopy. The stronger coupling to the Ag(110) substrate goes along with a shorter photohole lifetime and a stronger hybridization of the NTCDA lowest unoccupied molecular orbital with metal states. Supported by ab initio calculations, we show that the observed band dispersion is greatly enhanced due to the interaction with Ag(110) while the laterally denser adsorption geometry of NTCDA on Cu(100) entails a larger intermolecular wave-function overlap, and the presence of the substrate results in no further bandwidth enhancement.

Wiener, M.; Kbert, J.; Feyer, V.; Puschnig, P.; Schll, A.; Reinert, F.

2013-08-01

368

Studies of the Ag/Cu(110) bimetallic interface using optical second-harmonic generation  

SciTech Connect

Optical second harmonic generation (SHG) has recently been shown to be a sensitive, real-time, in situ probe for studying interfaces under many different environments. With regard to atomically clean well-characterized surfaces, SHG has been shown to be sensitive to submonolayer coverages of adsorbates, the structural symmetry or molecular arrangement on the surface, and the surface reordering observed during laser induced melting and recrystallization. Previous SHG studies of bimetallic systems have focused on alkali metal adsorption onto transition metal substrates. In these systems the observed SH response is enhanced by a factor of one thousand upon alkali adsorption, due to the large charge transfer to the substrate. We have chosen to study the growth of Ag overlayers on an atomically clean and well-characterized Cu(110) surface. The Ag overlayer growth on this substrate is known to have some interesting temperature dependent behavior that is typical for systems in which significant three-dimensional clustering is known to be important. Cu and Ag, while electronically similar, are immiscible near room temperature, hence there is no significant surface or bulk alloy formation. 16 refs., 4 figs., 1 tab.

Muenchausen, R.E.; Hoffbauer, M.A.; Taylor, T.N.

1989-01-01

369

Thermal expansion behavior of FeNi alloy layers in Fe 1- xNi x/Cu superlattices  

NASA Astrophysics Data System (ADS)

Thermal expansion behaviors of FeNi alloy layers in Fe 1- xNi x/Cu superlattices were investigated by means of X-ray diffraction technique in the temperature range of 10-300 K. It was found that with the Invar composition ( x=0.35), FeNi alloy layers showed low thermal expansions. But for alloy layers with either lower or higher Ni concentrations, thermal expansion coefficients were larger. It was inferred from results of magnetic measurements that FeNi alloy layers with Ni concentrations lower than the Invar composition were in a superparamagnetic state which could explain both a low spontaneous magnetization and a high thermal expansion rate of the alloy layers.

Tang, W.; Gerhards, Ch.; Heise, J.; Zabel, H.

1999-01-01

370

Modelling metal-metal interactions and metal toxicity to lettuce Lactuca sativa following mixture exposure (Cu?-Zn? and Cu?-Ag?).  

PubMed

Metal toxicity to lettuce Lactuca sativa was determined following mixture exposure based on the concepts of concentration addition (CA) and response addition (RA). On the basis of conventional models assuming no interaction between mixture components, Ag(+) was the most toxic, followed by Cu(2+) and Zn(2+). Furthermore, ion-ion interactions were included in quantitatively estimating toxicity of interactive mixtures of Cu(2+)-Zn(2+) and Cu(2+)-Ag(+) by linearly expanding the CA and RA models. About 80-92% ofthe variability in the root growth could be explained by this approach. Estimates by the extended models indicate significant alleviative effects of Zn(2+) on Cu(2+) toxicity whereas Cu(2+) did not significantly affect Zn(2+) toxicity. According to the extended CA model, Cu(2+) significantly reduced Ag(+) toxicity while Ag(+) enhanced Cu(2+) toxicity. Similar effects were not found by the extended RA model. These interactions might result from their individual uptake mechanisms and toxic actions as published in literature. PMID:23429096

Le, T T Yen; Vijver, Martina G; Kinraide, Thomas B; Peijnenburg, Willie J G M; Hendriks, A Jan

2013-05-01

371

Electroless Ni-Cu-P plating onto open cell stainless steel foam  

NASA Astrophysics Data System (ADS)

Metallic foams with a high fraction of porosity, low density and high energy absorption capacity, are a rapidly emerging class of novel ultralightweight materials for various engineering applications. Development of these materials with Ni-Cu-P coatings is expected to widespread their industrial utilizations. This article aims to apply Ni-Cu-P coatings onto open cell stainless steel foams from Ni-P bath containing CuSO 45H 2O as a source of Cu ions. Scanning electron microscopy and energy dispersive analysis were used to investigate the microstructure and chemical composition of the deposited coatings, respectively. The influence of CuSO 45H 2O addition on the deposition rate, chemical composition and surface morphology of coatings was studied. The corrosion performance of coated foam was examined in 1 M HCl using weight loss technique. The results revealed that wt.% of Cu in deposit increases with CuSO 45H 2O concentration, while wt.% of Ni and P is reduced. Better corrosion resistance, finer-grained deposit and lower deposition rate were observed by increasing Cu content into Ni-P matrix.

Abdel Aal, A.; Shehata Aly, M.

2009-04-01

372

Electronic Properties of Liquid CuTe, Ag-Te, Au-Te and Pd-Te Binary Alloys  

Microsoft Academic Search

Liquid Ag-Te and Cu-Te systems exhibited sharp minima in the conductivity and the susceptibility at the stoichiometric composition M2Te. Furthermore, liquid Cu-Te system exhibited a weak maximum in the conductivity near 15 at%Cu concentration. For liquid Au-Te system, the concentration dependence of conductivity increases gradually with increasing Au concentration and that of susceptibility has a smooth variation with Au concentration.

Tatsuya Okada; Fujio Kakinuma; Satoru Ohno

1983-01-01

373

Nucleation Control and Thermal Aging Resistance of Near-Eutectic Sn-Ag-Cu-X Solder Joints by Alloy Design  

NASA Astrophysics Data System (ADS)

Elemental (X) additions to Sn-3.5Ag-0.95Cu (SAC3595) solder were developed with minimal (<0.25 wt.%) concentration to avoid pro-eutectic Ag3Sn blades by reducing undercooling (? T) and to eliminate thermal-aging-induced embrittlement. Calorimetry and microstructure results on simple Cu/Cu joints identified 0.21Zn, 0.10Mn, and 0.05Al as sufficient to reduce undercooling below that for SAC3595 and to eliminate Ag3Sn blades. A 211C melting onset for the X = Mn alloys also suggested the discovery of a new quaternary eutectic. Shear testing and microstructure analysis of larger joints showed that 0.05Al and 0.21Zn additions resulted in reduced as-soldered strength (30 MPa), like Sn-0.95Cu, but all joints showed ductile failure at about 30 MPa after 1000 h at 150C.

Anderson, Iver E.; Walleser, Jason W.; Harringa, Joel L.; Laabs, Fran; Kracher, Alfred

2009-12-01

374

Cosintering of Ni-Zn-Cu Ferrite with Low-Temperature Cofired Ceramic Substrates  

NASA Astrophysics Data System (ADS)

Inserting a ferrite layer into a low-temperature cofired ceramic substrate offers the potential of burying inductors in multilayer ceramic substrates. To cofire a ceramic substrate at low temperatures, ferrite must be densified at a low temperature. With the addition of 6 wt%Bi2O3, Ni-Zn-Cu ferrite can be densified at 900C. The doped Bi2O3 not only lowers the sintering temperature but also increases the permeability of Ni-Zn-Cu ferrite. The cordierite + borosilicate glass system is very compatible with Ni-Zn-Cu ferrite after cofiring, but the calcium borosilicate crystallizable glass system is incompatible with Ni-Zn-Cu ferrite. However, with the addition of 10 wt%SiO2 into the calcium borosilicate crystallizable glass system, the incompatibility was resolved.

Chen, Lih-Shan; Hsi, Chi-Shiung; Fu, Shen-Li; Lin, Jiuun-Yih

2000-01-01

375

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

376

Microstructural Characterization of Irradiated Fe-Cu-Ni-P Model Steels.  

National Technical Information Service (NTIS)

The microstructure of Fe-Cu-Ni-P model pressure vessel steels after neutron irradiation and thermal aging has been characterized by atom probe field-ion microscopy and augmented by transmission electron microscopy. High densities of small, roughly spheric...

M. K. Miller D. T. Hoelzer F. Ebrahimi J. R. Hawthorne M. G. Burke

1987-01-01

377

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

NASA Astrophysics Data System (ADS)

There are TWO different types of impact-related, magmatic Ni-Cu (-PGE) deposits: the upper-crustal Sudbury type exsolved from the impact melt sheet, and the lower-crustal Maniitsoq type exsolved from contaminated mantle melts.

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

2013-09-01

378

Cast-Replicated NiTiCu Foams with Superelastic Properties  

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

379

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

PubMed

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

Baviloliaei, Mahdi Sadeghzadeh; Diekhner, Lars

2014-05-21

380

A comparative study of NiTi and NiTiCu shape memory alloy processed by plasma melting and injection molding  

Microsoft Academic Search

Shape memory alloys (SMA) are smart materials that present potential applications in such diverse areas as aeronautics, automotive, electronics, biomedicine and others. This work aimed at comparing some physical and functional properties of a NiTiCu and equiatomic NiTi SMA. Therefore, Ni50Ti and Ni50Ti5Cu (at.%) were manufactured using plasma melting followed by injection in metallic mold, named Plasma Skull PushPull (PSPP)

C. J. de Arajo; N. J. da Silva; M. M. da Silva; C. H. Gonzalez

2011-01-01

381

Effects of FeCo magnetic nanoparticles on microstructure of Sn-Ag-Cu alloys  

NASA Astrophysics Data System (ADS)

Sn-Ag-Cu (SAC) alloys have been regarded as the most promising candidates for lead-free solders in the electronic packaging industry. We prepared SAC solder-FeCo magnetic nanoparticles (MNPs) composite paste with different MNP concentration and used AC magnetic fields localized heating to cause their reflow. Differential scanning calorimetry results show a reduced undercooling of the composite paste with the addition of MNPs. Transmission electron microscope prove that the FeCo MNPs are distributed in Sn matrix of the reflowed solder composites. Optical micrographs show a decrease in the amount of primary Ag3Sn and ?-Sn dendrites, and an increase in the amount of eutectic microconstituents with increasing MNPs. The addition of FeCo MNPs is considered to promote the solidification of ?-Sn by providing more heterogeneous nucleation sites at a relatively low undercooling, which results in the microstructural refinement in the as-prepared solder joints.

Xu, Siyang; Habib, Ashfaque H.; Prasitthipayong, Anya; McHenry, Michael E.

2013-05-01

382

Effective electrodeposition of CoNiCu alloys nanoparticles in the presence of alkyl polyglucoside surfactant  

Microsoft Academic Search

The effect of alkyl polyglucoside (APG) surfactant on the electrodeposition CoNiCu alloys nanoparticles has been investigated. In a typical electrodeposition experiment, it was found that as prepared CoNiCu alloys nanoparticles characteristics, such as size homogeneity, density, dispersion on the electrode substrate and the chemicals composition, depended strongly on the concentration of APG used in the reaction as well as the

Setia Budi; A. R. Daud; S. Radiman; Akrajas Ali Umar

2010-01-01

383

Thermomechanical properties of TiNiCu 12 wire reinforced Kevlar\\/epoxy composites  

Microsoft Academic Search

TiNi12wt%Cu shape memory alloy wire reinforced Kevlar\\/epoxy composites were produced and the thermomechanical behaviors of the composites were studied. Results showed that the prestrain level does not affect significantly the stressstrain and stresstemperature behaviors of the TiNiCu composites. Only the straintemperature behavior of the composites is sensitive to the prestrain level. Composites with a small prestrain level show a larger

Yanjun Zheng; Jan Schrooten; Lishan Cui

2005-01-01

384

First-principles study of surface segregation in Cu-Ni alloys  

Microsoft Academic Search

A method coupling electronic structure calculations with Monte Carlo simulations has been developed to determine surface compositions in Cu-Ni alloys. The calculations are based on an effective Ising model with parameters as defined within the framework of the generalized perturbation method and as calculated by means of the tight-binding version of the linear-muffin-tin-orbital method. Properties of Cu-Ni bulk alloys are

A. Pasturel; V. Drchal; J. Kudrnovsk; P. Weinberger

1993-01-01

385

Straintemperature behavior of NiTiCu shape memory single crystals  

Microsoft Academic Search

Single crystal specimens of NiTi10Cu alloys were subjected to temperature cycling conditions under constant tensile and compressive stresses and the transformation strains were monitored. The [111] orientation exhibited the highest experimental transformation strains (6.64%) in tension while the [001] provides the highest transformation strains in compression (5.34%). These transformation strain levels are significantly higher than previously reported values on NiTiCu

H Sehitoglu; I Karaman; X Zhang; A Viswanath; Y Chumlyakov; H. J Maier

2001-01-01

386

Pulsed laser deposition of the NiTiCu thin film alloy  

Microsoft Academic Search

NiTiCu alloy present different properties: shape memory effect, super-elasticity and biocompatibility which allow it to be used in different fields: from biomedical to micro electro mechanical systems. It is complex to obtain these properties in thin films of NiTiCu alloy deposited on Si substrates. In this work preliminary results, in situ X-ray fluorescence data, ex situ X-ray diffraction data of

A. Morone

2007-01-01

387

Shrinking of hollow Cu 2O and NiO nanoparticles at high temperatures  

Microsoft Academic Search

The structural stability of hollow Cu2O and NiO nanoparticles associated with reduction and oxidation reactions at high temperatures was studied by transmission electron microscopy (TEM). Hollow Cu2O and NiO in annealing under 5.010?5Pa was observed to have shrunk at 473 and 623K, respectively, where the reduction reactions from oxides to metals started. As a result of shrinking associated with reduction,

R. Nakamura; D. Tokozakura; J.-G. Lee; H. Mori; H. Nakajima

2008-01-01

388

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

Microsoft Academic Search

Cu-doped nickel oxide (NiO) thin films were prepared by electrochemial deposition (cathodic deposition) technique onto the fluorine doped tin oxide (F: SnO2; FTO) coated glass substrates from organic solutions. Effects of Cu content on the morphology, structure, optical and electrochromic properties of NiO films were investigated by means of scanning electron microscope (SEM), X-ray diffraction (XRD), ultravioletvisible spectrophotometer (UVvis) and

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

2011-01-01

389

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

Microsoft Academic Search

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

N. Nandagopal; Zequn Mei; Sue Teng

2006-01-01

390

Microstructural, mechanical and citotoxicity evaluation of different NiTi and NiTiCu shape memory alloys  

Microsoft Academic Search

Transformation temperatures and mechanical properties such as transformation stresses at different temperatures and the superelasticity have been investigated in NiTiCu alloys with various Copper concentrations. The results have been compared with the conventional NiTi alloys. The addition of copper was effective to narrow the stress hysteresis and to stabilize the superelasticity characteristics. Moreover, it produced greater stability on both the

F. J. Gil; E. Solano; J. Pea; E. Engel; A. Mendoza; J. A. Planell

2004-01-01

391

Thermomechanical characterization of NiTiCu and NiTi SMA actuators: influence of plastic strains  

Microsoft Academic Search

The focus of this study is the thermomechanical characterization and comparison between two different shape memory alloys (SMAs) quantifying the effect of plastic strain on the transformation characteristics of SMA actuators. In this study, the thermomechanical response and transformation characteristics of a NiTiCu and a NiTi SMA are studied as a function of the induced plastic strain for four different

David A. Miller; Dimitris C. Lagoudas

2000-01-01

392

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

Microsoft Academic Search

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

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

1995-01-01

393

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

394

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

395

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

396

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

PubMed

The microbial ecology of the bioleaching of Ni-Cu sulfide is poorly understood and little effort has been made to handle the microbiological components of these processes. In this study, denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA genes fragments from bacteria was used to evaluate the changes of the bacterial community in the process of Ni-Cu sulfide bioleaching in a shaken flask system. The results revealed that the bacterial community was disturbed after the addition of Ni-Cu sulfide. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved sequences clustered together with the genera Acidithiobacillus and Leptospirillum. Multidimensional scaling (MDS) and cluster analysis of DGGE-banding patterns revealed that the process of Ni-Cu sulfide bioleaching in 46days was divided into three stages. During the bioleaching process of Ni-Cu sulfide, Leptospirillum was always dominant. The genera Acidithiobacillus was only detected at early and later stages of the bioleaching process. These results extend our knowledge on microbial dynamics in Ni-Cu sulfide bioleaching, a key issue required to improve commercial applications. PMID:20624605

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

2010-11-01

397

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

NASA Astrophysics Data System (ADS)

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

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

398

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

NASA Astrophysics Data System (ADS)

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

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

399

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

NASA Astrophysics Data System (ADS)

We perform isothermal Brownian-type molecular dynamics simulations with the Gupta potential for bimetallic cluster Ag17Cu2 from T=0 to 1500K, across the temperature range associated with the melting behaviour determined by the specific heat of the cluster. We also use the instantaneous normal mode (INM) analysis to dissect dynamics of the cluster. In terms of the projected density of states of the vibrational INMs, we propose a new order parameter that specifically describes the melting behaviour of the cluster. The calculated result of our order parameter is consistent with the information inferred from the specific heat data.

Tang, Pin-Han; Wu, Ten-Ming; Lai, S. K.

2013-08-01

400

Spasmodic growth during the rapid solidification of undercooled Ag-Cu eutectic melts  

NASA Astrophysics Data System (ADS)

A melt fluxing technique has been used to undercool Ag-Cu eutectic alloy by 10-70 K and the subsequent recalescence has been studied using high speed imaging. Spasmodic growth of the solidification front was observed, in which the growth front would make a series of quasi-periodic jumps separated by extended periods during which time growth appeared to arrest. Evidence of this previously unreported mode of growth is presented. The high speed images and microstructural evidence support the theory that anomalous eutectics form by the growth and subsequent remelting of eutectic dendrites.

Clopet, C. R.; Cochrane, R. F.; Mullis, A. M.

2013-01-01

401

Dissolution of Cu, Co and Ni from ocean nodules by l-ascorbic acid  

Microsoft Academic Search

Ferromanganese ocean nodules contain important transition metals like Cu, Co and Ni. They serve as an alternate source of these metals especially in countries like India, which does not have land-based resources of Co and Ni. The existing methods for metal dissolution from the nodules use highly acidic or alkaline media accompanied by strong organic or inorganic reducing agents at

Amitava Mukherjee; Ashok M. Raichur; Jayant M. Modak; K. A. Natarajan

2005-01-01

402

Thin foil electron microscope observations on NiTiCu shape memory alloys  

Microsoft Academic Search

The results are reported of a transmission electron microscope study on foils of a series of shape memory alloys, based on NiTi in which up to half the Ni has been substituted for by Cu. It is shown that the unusual thin foil effects previously noted in the austenitic phase of the binary alloy, such as mottled images, ``ghost'' martensite,

R. H. Bricknell; K. N. Melton

1980-01-01

403

Isotopic Composition as a Signature for Different Processes Leading to Fragment Production in Midperipheral Ni+Al, Ni, Ag Collisions at 30 MeV/Nucleon  

NASA Astrophysics Data System (ADS)

The results of experiments performed to investigate the Ni+Al, Ni+Ni, Ni+Ag reactions at 30 MeV/nucleon are presented. From the study of dissipative midperipheral collisions, it has been possible to detect events in which Intermediate Mass Fragments (IMF) production takes place. The decay of a quasi-projectile has been identified; its excitation energy leads to a multifragmentation totally described in terms of a statistical disassembly of a thermalized system (T?4 MeV, E* ?4 MeV/nucleon). Moreover, for the systems Ni+Ni, Ni+Ag, in the same nuclear reaction, a source with velocity intermediate between that of the quasi-projectile and that of the quasi-target, emitting IMF, is observed. The fragments produced by this source are more neutron rich than the average matter of the overall system, and have a charge distribution different, with respect to those statistically emitted from the quasi-projectile. The above features suggest that this production comes from material which is "surface-like" (since it originates from the overlap of the two nuclei). To investigate the neutron content in both processes the 4He and 6He experimental yields were studied.

Milazzo, P. M.; Margagliotti, G. V.; Rui, R.; Vannini, G.; Colonna, N.; Gramegna, F.; Mastinu, P. F.; Agodi, C.; Alba, R.; Bellia, G.; Coniglione, R.; Del Zoppo, A.; Finocchiaro, P.; Maiolino, C.; Migneco, E.; Piattelli, P.; Santonocito, D.; Sapienza, P.; Iori, I.; Moroni, A.

2007-01-01

404

Analysis of the reaction between 60Sn-40Pb solder with a Pd-Pt-Ag-Cu-Au alloy  

SciTech Connect

We present the results of a metallurgical study of a 35Pd-30Ag-14Cu-10Au10Pt-1Zn (wt. %) alloy soldered with 60Sn-40Pb for glass-to-metal sealing applications. Mechanical tests were performed on the Pd-Ag-Cu-Au-Pt-Zn alloy and showed that it retains ductility, with an increase in strength, after heat treatments that simulate the glass-to-metal sealing temperature profile. Wetting characteristics of the alloy with 60Sn-40Pb solder were found to be adequate for pin joining applications. The formation and growth of the interfacial intermetallic between 60Sn-40Pb and the Pd-Ag-Cu-Au-Pt-Zn alloy were characterized. The matrix of the intermetallic layer consists of PdSn[sub 4] with platinum and gold substituting for the palladium in the crystal structure. Also present were precipitates of Cu[sub 3]Sn and Ag[sub 3]Sn. Nano-indentation hardness tests showed that the intermetallic layer has mechanical properties similar to the base metal while retaining good ductility. The intermetallic was also found to have good wettability under solder reflow conditions. We conclude from these tests that the Pd-Ag-Cu-Au-Pt-Zn alloy is a suitable option as a pin material for glass-to-metal sealing applications. 20 refs., 11 figs., 3 tabs.

Frear, D.R.; Michael, J.R.; Hlava, P.F. (Sandia National Lab., Albuquerque, NM (United States))

1993-02-01

405

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

406

Diffusion of small Ni and Cu clusters on Ni (111): Application of SLKMC-II*  

NASA Astrophysics Data System (ADS)

We have examined the diffusion of small Ni and Cu islands (consisting of up to 10 atoms) on the Ni(111) surface using a self-learning kinetic Monte Carlo (SLKMC-II) [1] method with an improved pattern-recognition scheme that allows inclusion of both fcc and hcp sites in the simulations. In an SLKMC simulation [2] a database holds information about the local neighborhood of an atom and associated processes that is accumulated on-the-fly, as the simulation proceeds. The activation energy barriers for the identified diffusion processes were calculated using semi-empirical interaction potential based on the embedded-atom method. Although a variety of concerted, multi-atom and single-atom processes were automatically revealed in our simulations, we found that these small islands diffuse primarily via concerted motion. We report diffusion coefficients for each island size at several temperatures, and from the Arrhenius plot extract the size-dependent effective diffusion barrier for these islands. Our evaluation of the occurrence frequency of processes most responsible for the diffusion of island of a specific size reveal several that are not accessible in SLKMC-I [2] or in short time-scale MD simulations. We also provide results of extending SLKMC-II to examine epitaxial growth in these systems. [1] S. Islamuddin Shah, et al., J. Phys.: Condens. Matter 24, 354004 (2012). [2] O. Trushin, et al., Phys. Rev. B 72, 115401 (2005).

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

2013-03-01

407

Physically synthesized Ni-Cu nanoparticles for magnetic hyperthermia  

PubMed Central

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

Bettge, Martin; Chatterjee, Jhunu; Haik, Yousef

2004-01-01

408

Metallic glass alloys of Zr, Ti, Cu and Ni  

DOEpatents

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

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

1997-01-01

409

Preliminary atom probe studies of PdNi(Cu)P supercooled liquids  

Microsoft Academic Search

The microstructural development during annealing in the supercooled liquid region of amorphous Pd46Ni36P18, which is supposedly of phase-separating composition, is compared and contrasted with those of Pd48Ni32P20 and Pd40Ni10Cu30P20. High resolution electron microscopy showed that the as-quenched alloys were fully amorphous while atom probe field ion microscopy (APFIM) showed random solute distributions, typical of amorphous materials. Annealing in their respective

H. G. Read; K. Mono; A. P. Tsai; A. Inoue

1997-01-01

410

Multilayer polymer structures containing Ni\\/Cu nanoclusters as prepared by selective laser sintering  

Microsoft Academic Search

Selective laser sintering (SLS) process was used to prepare nanostructured porous 3D items consisting of Ni or\\/and Cu nanoclusters\\u000a embedded into a polycarbonate (PC) matrix for potential use in nanoelectromechanical systems (NEMS). Liquid-phase SLS was\\u000a performed (in air or Ar) with the Ni-PC powder mixtures taken in proportions of 1 : 1, 1 : 2 (Ni particle size 27184 nm)

I. V. Shishkovsky; Yu. G. Morozov

2011-01-01

411

Microstructure and reactions of SiC{sub w}-reinforced alumina with Ag-Cu-In-Ti  

SciTech Connect

Brazing experiments were performed at 750 C for 2 h between Ag-Cu-In-Ti alloy and SiC{sub w}/Al{sub 2}O{sub 3}. The first clearly nonbraze layer consists of an oxide layer of metallic composition 33Ti-31Al-22Cu-14S. Areas adjacent to the SiC whiskers were of different composition. A thin, continuous layer on the alumina portion of the composite appears to be {gamma}-TiO. The SiC whiskers are preferentially consumed and undergo reductions in diameter of approximately 40%. Observed knobby whisker morphologies may be related to SiC stacking faults. {eta}-type phases detected near the Ag-Cu eutectic portion of the joint appear to consist of Ti-Cu-Al-Si-O and Ti{sub 3}Cu{sub 3}O.

Park, E.S.; Lannutti, J.J. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science; Cawley, J.D. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science

1995-01-01

412

Microstructure at the interface between AlN and a Ag-Cu-Ti braze alloy  

SciTech Connect

The joining of aluminum nitride by active metal brazing with a Ag-Cu-Ti foil has been investigated in cross-section by transmission electron microscopy. The reaction of AlN with the braze alloy results in the formation of continuous TiN and (Ti,Cu,Al){sub 6}N ({eta}-phase) layers at the interface. AlN grains at the interface often display arrays of dislocations, presumably arising from thermal expansion mismatch between the AlN and the TiN (the coefficients of thermal expansion are 43{times}10{sup {minus}7}/{degree}C and 80{times}10{sup {minus}7}/{degree}C, respectively). The adjoining TiN contains small Cu precipitates and may also contain numerous defects. Titanium preferentially penetrates the AlN grain boundaries, resulting in finger-like TiN intrusions into the substrate, which sometimes cover entire AlN grains in a TiN shell. On the other side of the TiN, a continuous layer of equiaxed, defect-free {eta}-nitride grains is found. Beyond this {eta}-nitride layer is the remaining mixture of metallic Ag and Cu. High-resolution electron microscopy demonstrates that the AlN-TiN and TiN-{eta} boundaries are abrupt and contain no additional crystalline or amorphous intervening phases. Particular orientation relationships are occasionally observed at the AlN-TiN interface; these are not always the ones that produce the minimum lattice mismatch.The implications of the observed morphology with respect to the reaction sequence, transitional phases, and structural integrity of the joint are discussed.

Carim, A.H. (Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, NM (USA) Center for Micro-Engineered Ceramics, University of New Mexico, Albuquerque, NM (USA)); Loehman, R.E. (Dept. 1840, Sandia National Laboratories, Albuquerque, NM (USA))

1990-07-01

413

Coprecipitation of ? and ? phases in Al-Cu-Mg-Mn alloys containing Ag and Si  

NASA Astrophysics Data System (ADS)

The individual influence of small additions of Ag and Si on the nucleation of the ? ( i.e., a chemically modified coherent form of ?-Al2Cu) and ? (Al5Cu6Mg2) phases, respectively, in Al-Cu-Mg alloys has been known. These phases nucleate directly and exhibit reduced rates of coarsening at the commercial aging temperatures. Alloys containing a uniform and fine distribution of these phases may, therefore, be of interest for further investigation for applications at temperatures below 200 C. In a recent study, using an Al-Cu-Mg-Mn-Ag-Si alloy aged at 180 C, it was shown that the ? phase formed as a major precipitate nucleated predominantly upon the Mn-bearing dispersoids, while the ? phase was present as a minor one. This article describes the conditions under which widespread nucleation of ? phase may occur at unidentified sites in the matrix as well as upon the Mn-bearing dispersoids in the alloy. Widespread nucleation of ? phase begins in the alloy following the onset of dissolution of Guinier-Preston-Bagaryatski (G-P-B) zones that form early in the aging cycle as the major precipitate. It is established that nucleation of ? as a major phase precipitate requires a critical minimum supersaturation of Si in the solid solution. This article further points out that several constituent phases (implying those which form as solidification products and survive the homogenization treatment) together with the Mn-bearing dispersoids dissolve Si, thereby considerably reducing the Si supersaturation in the solid solution. The implications of these observations are discussed in view of the available data on the nucleation of ? phase in such alloys.

Mukhopadhyay, A. K.

2002-12-01

414

A cross-sectional high-resolution transmission electron microscopy study of electrodeposited NiCu\\/Cu multilayers  

Microsoft Academic Search

This work is an extension of our previous structural study performed by conventional transmission electron microscopy (TEM) on electrodeposited NiCu\\/Cu multilayers exhibiting giant magnetoresistance (GMR). It could be established from the present atomic-resolution structural studies that (i) the layered structure found by conventional TEM to be flat and smooth shows an interface roughness spread over a few atomic monolayers; (ii)

. Czirki; V. Pierron-Bohnes; C. Ulhaq-Bouillet; E. Tth-Kdr; I. Bakonyi

1998-01-01

415

An analytical electron microscopic investigation of precipitation in an Al-Cu-Zn-Mg-Ag alloy.  

PubMed

The distribution, morphology, chemistry, and crystallography of the precipitates formed during aging of an Al-Cu-Zn-Mg-Ag alloy have been studied using analytical transmission electron microscopy. The first precipitates to appear during aging at 150 degrees C were thin hexagonal-shaped plate-like precipitates which formed on the (111)Al planes. These precipitates had a face-centred orthorhombic crystal structure and their composition was essentially CuAl2 although they contained a trace of silver. At peak hardness the microstructure consisted of the plate-like precipitates on (111)Al planes and theta' precipitates on (100)Al planes. Overaging resulted in the precipitation of equilibrium theta, CuAl2, which exhibited a lath morphology and an orientation-relationship with the matrix (210)Al magnitude of (110)gamma; (001)Al misoriented from (001)gamma by approximately 6 degrees. Prolonged overaging at 250 degrees C resulted in the formation of cuboid-shaped Al5(Cu,Zn)6Mg2 precipitates which had a cubic crystal structure and a cube:cube orientation-relationship with the matrix. PMID:8513176

Hasan, F; Lorimer, G W

1993-03-01

416

Facile synthesis of near-monodisperse Ag@Ni core-shell nanoparticles and their application for catalytic generation of hydrogen  

NASA Astrophysics Data System (ADS)

Magnetically recyclable Ag-Ni core-shell nanoparticles have been fabricated via a simple one-pot synthetic route using oleylamine both as solvent and reducing agent and triphenylphosphine as a surfactant. As characterized by transmission electron microscopy (TEM), the as-synthesized Ag-Ni core-shell nanoparticles exhibit a very narrow size distribution with a typical size of 14.9 1.2 nm and a tunable shell thickness. UV-vis absorption spectroscopy study shows that the formation of a Ni shell on Ag core can damp the surface plasmon resonance (SPR) of the Ag core and lead to a red-shifted SPR absorption peak. Magnetic measurement indicates that all the as-synthesized Ag-Ni core-shell nanoparticles are superparamagnetic at room temperature, and their blocking temperatures can be controlled by modulating the shell thickness. The as-synthesized Ag-Ni core-shell nanoparticles exhibit excellent catalytic properties for the generation of H2 from dehydrogenation of sodium borohydride in aqueous solutions. The hydrogen generation rate of Ag-Ni core-shell nanoparticles is found to be much higher than that of Ag and Ni nanoparticles of a similar size, and the calculated activation energy for hydrogen generation is lower than that of many bimetallic catalysts. The strategy employed here can also be extended to other noble-magnetic metal systems.

Guo, Huizhang; Chen, Yuanzhi; Chen, Xiaozhen; Wen, Ruitao; Yue, Guang-Hui; Peng, Dong-Liang

2011-05-01

417

Magnetically Assembled Ni@Ag Urchin-Like Ensembles with Ultra-Sharp Tips and Numerous Gaps for SERS Applications.  

PubMed

Ni@Ag urchin-like assemblies are synthesized. The tips of these products are as tiny as 10 nm, arm apex angles are 39, and a large amount of "crossing areas" between urchin-like particles are produced due to peculiar magnetically induced assembling. These advantages make them powerful SERS probes for chemical and biological analyses. PMID:24644040

Liu, Dequan; Wang, Xi; He, Deyan; Dao, Thang Duy; Nagao, Tadaaki; Weng, Qunhong; Tang, Daiming; Wang, Xuebin; Tian, Wei; Golberg, Dmitri; Bando, Yoshio

2014-07-01

418

Spreading of Sn-Ag solders on FeNi alloys  

SciTech Connect

The spreading of Sn-3Ag-xBi solders on Fe-42Ni has been studied using a drop transfer setup. Initial spreading velocities as fast as {approx}0.5 m/s have been recorded. The results are consistent with a liquid front moving on a metastable, flat, unreacted substrate and can be described by using a modified molecular-kinetic model for which the rate controlling step is the movement of one atom from the liquid to the surface of the solid substrate. Although the phase diagram predicts the formation of two Fe-Sn intermetallics at the solder/substrate interface in samples heated at temperatures lower than 513 C, after spreading at 250 C only a thin FeSn reaction layer could be observed. Two interfacial layers (FeSn and FeSn2) were found after spreading at 450 C.

Saiz, Eduardo; Hwang, C-W.; Suganuma, Katsuaki; Tomsia, Antoni P.

2003-02-28

419

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

Microsoft Academic Search

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,\\u000a it was found that the application of fertilizers could change the distribution of Cu, Cr and Ni in the fractions of soil.\\u000a Applying urea (CO(NH2)2) significantly decreased the concentrations of Cu,

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

2007-01-01

420

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

421

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

SciTech Connect

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

Tai, Kaiping; Feng, Lin; Dillon, Shen J. [Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States)] [Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801 (United States)

2013-05-21

422

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

SciTech Connect

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

Ranganatha, S. [Department of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta 577451, Shimoga, Karnataka (India)] [Department of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta 577451, Shimoga, Karnataka (India); Venkatesha, T.V., E-mail: drtvvenkatesha@yahoo.co.uk [Department of Studies in Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta 577451, Shimoga, Karnataka (India); Vathsala, K. [Nanotribology Laboratory, Mechanical engineering department, Indian Institute of Science, Bangalore (India)] [Nanotribology Laboratory, Mechanical engineering department, Indian Institute of Science, Bangalore (India)

2012-03-15

423

Effect of filler metal composition on the strength of yttria stabilized zirconia joints brazed with Pd-Ag-CuOx  

SciTech Connect

The Ag-CuOx system is of interest to be used to be used as an air braze filler metal for joining high temperature electrochemical devices. Previous work has shown that the melting temperatures can be increased by adding palladium to Ag-CuOx and it is expected that this may aid high temperature stability. This work compares the room temperature bend strength of joints made between yttria-stabilized zirconia (YSZ) air brazed using Ag-CuOx without palladium and with 5 and 15mol% palladium additions. It has been found that in general palladium decreases joint strength, especially in low copper oxide compositions filler metals. At high copper oxide contents, brittle fracture through both copper oxide rich phases and the YSZ limits joint strength.

Darsell, Jens T.; Weil, K. Scott

2008-09-08

424

The Role of Pd in Sn-Ag-Cu Solder Interconnect Mechanical Shock Performance  

NASA Astrophysics Data System (ADS)

The mechanical stability of solder joints with Pd added to Sn-Ag-Cu alloy with different aging conditions was investigated in a high- G level shock environment. A test vehicle with three different strain and shock level conditions in one board was used to identify the joint stability and failure modes. The results revealed that Pd provided stability at the package-side interface with an overall shock performance improvement of over 65% compared with the Sn-Ag-Cu alloy without Pd. A dependency on the pad structure was also identified. However, the strengthening mechanism was only observed in the non-solder mask defined (NSMD) pad design, whereas the solder mask defined (SMD) pad design boards showed no improvement in shock performance with Pd-added solders. The effects of Sn grain orientation on shock performance, interconnect stability, and crack propagation path with and without Pd are discussed. The SAC305 + Pd solder joints showed more grain refinements, recrystallization, and especially mechanical twin deformation during the shock test, which provides a partial explanation for the ability of SAC305 + Pd to absorb more shock-induced energy through active deformation compared with SAC305.

Lee, Tae-Kyu; Zhou, Bite; Bieler, Thomas R.; Tseng, Chien-Fu; Duh, Jeng-Gong

2013-02-01

425

Magnetic and Thermal Properties of Cubic Single-Crystal PrCu4Ag  

NASA Astrophysics Data System (ADS)

We succeeded in synthesizing a new cubic intermetallic compound PrCu4Ag in a fcc structure. Measurements of X-ray diffraction, magnetic susceptibility, magnetization, specific heat, electrical resistivity, thermal expansion, and elastic constants have been performed on single crystals of PrCu4Ag. A maximum value of ?(T) with a corresponding peak in C(T) suggests that an antiferromagnetic phase transition occurs at TN = 2.4 K, where a sudden decrease in ?4f(T) and a sharp peak in the thermal expansion coefficient ?(T) were observed. Characteristic Curie-type softening was observed in the temperature dependence of the transverse mode for (C11 - C12)/2 and C44 from 70 K down to TN, which implies that the crystalline electric field (CEF) ground state is the magnetic triplet ?5. The anisotropic properties in M(T,H) and C(T,H) are studied when the external magnetic field is applied in the < 100>, < 110>, and < 111> directions. Another anomaly observed at approximately 10 K in ?(T) is considered to be related to possible disorder behavior. The low-T behavior and the possibility of quadrupole fluctuation are discussed with respect to the CEF effect. All the experimental results in the present study are summarized in a magnetic phase diagram.

Zhang, Shuai; Isikawa, Yosikazu; Tayama, Takashi; Kuwai, Tomohiko; Mizushima, Toshio; Akatsu, Mitsuhiro; Nemoto, Yuichi; Goto, Terutaka

2010-11-01

426

Dynamic structure factors of Cu, Ag, and Au: Comparative study from first principles  

NASA Astrophysics Data System (ADS)

We present a comparative theoretical and experimental study of dynamic structure factors (momentum-dependent loss functions) of the noble metals Cu, Ag, and Au in the energy range of 0-60 eV. The emphasis is on theoretical results that are compared with new as well as available experimental data. Dynamic structure factors are calculated within the linear-response formalism of time-dependent density-functional theory, using the full-potential linearized augmented plane-wave method. For the studied energy range, local-field effects are found to be very important for Ag and Au and only marginally relevant for Cu. We present an explanation for this surprising behavior. Loss functions of all three metals possess a complex multipeak structure. We classify the features in the loss function as being related to collective excitations, interband transitions, or mixed modes. The impact of short-range correlations on the dynamic response functions is evaluated by comparing the results of the random-phase approximation to those of the time-dependent local density approximation. Exchange-correlation effects are found to be weak for small momentum transfers, but increasingly important for larger momenta. The calculated structure factors agree well with experiments.

Alkauskas, Audrius; Schneider, Simon D.; Hbert, Ccile; Sagmeister, Stephan; Draxl, Claudia

2013-11-01

427

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

SciTech Connect

The electronic-energy-straggling values for 50--250-keV H{sup +} beams penetrating Cu, Ag, and Pt have been measured using backscattering. The Cu, Ag, and Pt layers with a thickness of about 30 nm were deposited onto Si, SiO{sub 2}, Al{sub 2}O{sub 3}, and ZrO{sub 2} substrates with electron beams or by sputtering. The uniformity and grain growth of the thin films were observed by cross-section transmission electron microscopy (TEM) and diffraction. The thickness fluctuation determined by TEM is less than 2 nm. The backscattering spectra were obtained with an electrostatic toroidal analyzer with an energy resolution (standard deviation) of 150--200 eV, and the computer-simulated spectrum analysis has given the best-fit values of the energy straggling. The derived straggling values are compared with the theoretical values calculated from the extended Lindhard-Winther theory using the local electron density of the Hartree-Fock-Slater atomic model. Discussion is also made in terms of the short-range correlation effect proposed by Sigmund (Phys. Rev. A 26, 2497 (1982)).

Kido, Y. (Department of Physics, Ritsumeikan University, Toji-in, Kita-ku, Kyoto 603, Japan (JP)); Koshikawa, T. (Osaka Electro-Communication University, Hatsu-cho, Neyagawa, Osaka 572, Japan (JP))

1991-08-01

428

Global minimum Pt(13)M(20) (M = Ag, Au, Cu, Pd) dodecahedral core-shell clusters.  

PubMed

In this work, we report finding dodecahedral core-shell structures as the putative global minima of Pt13M20 (M = Ag, Au, Cu, Pd) clusters by using the basin hopping method and the many-body Gupta model potential to model interatomic interactions. These nanoparticles consist of an icosahedral 13-atom platinum core encapsulated by a 20 metal-atom shell exhibiting a dodecahedral geometry (and Ih symmetry). The interaction between the icosahedral platinum core and the dodecahedral shell is analyzed in terms of the increase in volume of the icosahedral core, and the strength and stickiness of M-Pt and M-M interactions. Low-lying metastable isomers are also obtained. Local relaxations at the DFT level are performed to verify the energetic ordering and stability of the structures predicted by the Gupta potential finding that dodecahedral core-shell structures are indeed the putative global minima for Pt13Ag20 and Pt13Pd20, whereas decahedral structures are obtained as the minimum energy configurations for Pt13Au20 and Pt13Cu20 clusters. PMID:24303915

Borbn-Gonzlez, Dora J; Fortunelli, Alessandro; Barcaro, Giovanni; Sementa, Luca; Johnston, Roy L; Posada-Amarillas, Alvaro

2013-12-27

429

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

SciTech Connect

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

Darsell, Jens T.; Weil, K. Scott

2006-08-01

430

Electrochemical Behavior of Sintered CuAg4 at. pct Alloy  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

431

Electrochemical depositions of fluorohydroxyapatite doped by Cu2+, Zn2+, Ag+ on stainless steel substrates  

NASA Astrophysics Data System (ADS)

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.

Bir, F.; Khireddine, H.; Touati, A.; Sidane, D.; Yala, S.; Oudadesse, H.

2012-07-01

432

Shear deformation in Sn3.5Ag and Sn3.6Ag1.0Cu solder joints subjected to asymmetric four-point bend tests  

Microsoft Academic Search

The shear deformation behavior of two lead-free solder compositions, Sn-3.5Ag (wt.%) and Sn-3.6Ag-1.0Cu (wt.%), both on copper\\u000a substrates, was studied using an asymmetric four point bend technique. Four test joints were obtained from one master specimen\\u000a of each composition, and each joint was subject to progressive loading, up to the maximum shear strength of the joint. One\\u000a unstressed bar from

B. A. Cook; I. E. Anderson; J. L. Harringa; R. L. Terpstra; J. C. Foley; . nal; F. C. Laabs

2001-01-01

433

Solid-State Homogenization Reactions in Cu Core/Ni shell Nanoparticles  

NASA Astrophysics Data System (ADS)

Air stable Cu core/Ni shell nanoparticles have been prepared in a polyol-type process by heating an ethylene glycol (EG) solution containing CuCl2.2H2O and NiCl2.6H2O to its boiling temperature, adding an appropriate amount of NaOH, and allowing the reaction to proceed at reflux for 30 minutes prior to cooling. The as-prepared nanoparticles were characterized by scanning electron microscopy (SEM) with elemental mapping, x-ray diffraction (XRD), and vibrating sample magnetometry (VSM) measurements. Chemical composition maps of the particles revealed a well-defined core/shell structure consisting of a Cu core about 100-150 nm in diameter surrounded by a Ni shell about 30-40 nm in thickness. XRD measurements indicated that while the Cu core contained a small amount of incorporated Ni, the shell was essentially pure Ni. The solid-state transformation from the as-prepared core/shell structure to an essentially homogeneous Cu-Ni alloy was studied by high temperature VSM and XRD measurements as a function of annealing temperature and time. These measurements reveal that the core/shell structure remains largely intact to temperatures above 400 C and that complete homogenization occurs at temperatures above about 600 C.

Lattanzi, Michael; Higgins, Laura; Kelly, Brian; Poirier, Gerald; Unruh, Karl

2011-03-01

434

Experimental Partitioning of Elements Related to Iron Meteorite Chronologies -- Ag, Au, Mo, Ni, Pb, Pd, and TL  

NASA Astrophysics Data System (ADS)

To better understand the Pd-Ag and Pb-Tl chronometer systems of iron meteorites, we have performed a series of experiments to evaluate the distribution of Pb, Ag, Pd, and Tl in iron meteorites. Much of the data summarized here has been presented before (Jones and Hart, 1984; Jones et al., 1986; Jones, 1989). However, we have expanded our partitioning data for schreibersite (Fe(sub)3P) and have added Ni, Au, and Mo data for comparison to Ag, Pb, Pd, and Tl. Our experimental and analytical techniques have been described in detail elsewhere (Jones and Drake, 1983; Jones and Hart, 1984; Jones et al., 1986). Table 1 summarizes the results of our experiments near the Fe-FeS euctectic (1000- 900 degrees C). We find that the chalcophile elements Pb, Ag, and Tl are not only extremely incompatible in iron metal, they are also very incompatible in troilite (FeS) and schreibersite. In many cases, we can only give upper limits for the partition coefficients (D). We have compared our experimental D+s for (troilite/Fe-Ni metal) and (schreibersite/Fe-Ni metal) to those inferred for separated phases from iron meteorites. We find that metal- compatible elements (Au, Mo, Ni, Pd) in our experiments generally behave much as would be expected from the analysis of iron meteorites, whereas incompatible elements (Ag, Pb, Tl) do not. We have speculated previously that this discordance between experimentally determined D+s and those inferred from iron meteorites is due to incompatible-element-rich impurities in "metal" and "sulfide" separates (e.g., Jones, 1989). The general concordance of experimentally determined D+s and D+s inferred from natural assemblages further reinforces this view. Bulk "metal" analyses of Ag and Pb indicate that ~0.1-1 wt% of sulfide inclusions within the metal could account for the bulk "metal" Ag and Pb concentrations. If this trace impurity model is correct, we believe that we have a natural explanation for the discrepancy in (i) cooling rates calculated using Ni diffusion profiles (~1-10 degrees C/my; Wood, 1967) and (ii) those calculated using the constraint that Ag isotopic equilibration not occur (>>100 degrees C/my; Kaiser and Wasserburg, 1983). Ag solubility in Fe-Ni metal is very low. If radiogenic Ag in metal encounters small (<100 micrometer) troilite inclusions and finds a phase in which Ag is compatible, then the low solubility of Ag in metal will effectively prohibit further isotopic equilibration. In this model, diffusion rates could be very rapid, but isotopic equilibration could still be very slow. Upon later analysis of inclusion-bearing metal, the radiogenic Ag will be assumed to have been in the metal, the Pd/Ag ratio will still be high, and fast cooling rates will be invoked. Thus, it may be that the isotopic cooling rates of Kaiser and Wasserburg (1983) should be viewed as upper limits to the true cooling rate. References: Jones J.H. (1989) Lunar Planet. Sci. (abstract) 20, 478. Jones J.H. and Drake M.J. (1983) Geochim. Cosmochim. Acta 47, 1199-1209. Jones J.H. and Hart S.R. (1984) Meteoritics (abstract) 19, 248. Jones J.H. et al. (1986) Lunar Planet. Sci. (abstract) 17, 400. Kaiser T. and Wasserburg G.J. (1983) Geochim. Cosmochim. Acta 47, 43-58. Wood J.A. (1967) Icarus 6, 1-49. Table 1, which in the hard copy appears here, shows analytical results.

Jones, J. H.; Hart, S. R.; Benjamin, T. M.

1992-07-01