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1

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

E-print Network

and the pressure exerted by Fermi electrons, which supports electron shells expansion at the expense of decreasing for electroplated Ag/Cu and Cu/Ni multilayers using a modified Thomas­Fermi­Dirac electron theory. Experiments on a modified Thomas­Fermi­Dirac electron theory. Developed relationship between the critical monolayer

Volinsky, Alex A.

2

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

E-print Network

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

Entel, P.

3

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

4

Reliability and failure analysis of Sn-Ag-Cu solder interconnections for PSGA packages on Ni\\/Au surface finish  

Microsoft Academic Search

The reliability and failure modes of eutectic Sn-Ag-Cu solder joints were studied and compared to eutectic Sn-Pb-Ag ones. Two different failure modes occur: brittle fracture and fatigue. The results show that with a Ni\\/Au surface finish the reliability of Sn-Ag-Cu solder is much better than that of Sn-Pb-Ag solder. First, when the joint is deformed at high thermomechanical strain, the

Petar Ratchev; Bart Vandevelde; Ingrid De Wolf

2004-01-01

5

Electromigration time to failure of SnAgCuNi solder joints  

Microsoft Academic Search

Electromigration time to failure and electrical resistivity of 95.5%Sn-1.5%Ag-0.5%Cu-0.03W%Ni microelectronics solder joints have been investigated experimentally. A Black-type electromigration time to failure equation is developed to describe the time to failure versus current density and temperature. It is observed that resistance of a solder joint is not just a function of the temperature but also a function of the current

Cemal Basaran; Shidong Li; Douglas C. Hopkins; Damien Veychard

2009-01-01

6

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

7

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

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

8

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

9

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

10

Joint Strength and Microstructure for Sn-Ag-(Cu) Soldering on an Electroless Ni-Au Surface Finish by Using a Flux Containing a Cu Compound  

NASA Astrophysics Data System (ADS)

The effect of a flux containing Cu(II) stearate (barrier flux) on the strength of soldered joints between an electroless Ni-Au surface finish and two Pb-free soldering systems, Sn-3Ag-0.5Cu and Sn-3.5Ag (wt.%), was examined. Pull and shock tests showed that barrier flux gave a higher joint strength for both solder compositions than did a flux containing no Cu compounds. Interface analysis revealed that a thin P-rich layer and refined Cu-Ni-Sn intermetallic compounds were formed at the joint interface when barrier flux was used. It is assumed that the supply of Cu from barrier flux suppresses diffusion of Ni into the solder.

Kumamoto, Seishi; Sakurai, Hitoshi; Kukimoto, Youichi; Suganuma, Katsuaki

2008-06-01

11

Contact epitaxy by deposition of Cu, Ag, Au, Pt, and Ni nanoclusters on (100) surfaces: Size limits and mechanisms  

E-print Network

rates at low deposition rates.2 Since the cluster size offers one more degree of freedom particle en- ergy, substrate temperature, etc. that do not exist for con- ventional deposition methodsContact epitaxy by deposition of Cu, Ag, Au, Pt, and Ni nanoclusters on (100) surfaces: Size limits

Nordlund, Kai

12

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

Microsoft Academic Search

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

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

2007-01-01

13

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

14

Thermal and Mechanical Stability of Ce-Containing Sn-3.9Ag-0.7Cu Lead-Free Solder on Cu and Electroless Ni-P Metallizations  

NASA Astrophysics Data System (ADS)

Rare earth (RE)-containing solders have been shown to exhibit improvements in both physical and mechanical properties. However, the reactive nature of RE elements with oxygen may degrade the mechanical properties even under room-temperature aging. In this article, we report on the microstructure and mechanical properties of as-processed and thermally aged Ce-containing Sn-3.9Ag-0.7Cu solder reflowed on electroless Ni-P and Cu metallizations. The microstructure of both as-reflowed and thermally aged Ce-containing Sn-3.9Ag-0.7Cu solder joints is more refined compared with conventional Sn-3.9Ag-0.7Cu solder joints. The (Cu,Ni)6Sn5 intermetallic layer formed at the Cu/Ce-containing solder interface is thinner than that of Sn-3.9Ag-0.7Cu solder. The monotonic shear behavior of as-reflowed and thermally aged Sn-3.9Ag-0.7Cu-0.5Ce/Cu and electroless Ni-P lap shear joints was studied, and compared with Sn-3.9Ag-0.7Cu. It was found that both as-reflowed and thermally aged Ce-containing Sn-3.9Ag-0.7Cu exhibit higher strain to failure compared with Sn-3.9Ag-0.7Cu solder joints.

Xie, Huxiao; Chawla, Nikhilesh; Mirpuri, Kabir

2012-12-01

15

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

16

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

NASA Astrophysics Data System (ADS)

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

Lee, Tae-Kyu; Duh, Jeng-Gong

2014-11-01

17

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

PubMed

The metal ions M(2+) (Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Ag(+)) are potentially toxic. Their electro deposition has been carried out in aqueous air-equilibrated CuCrO(2) suspension upon visible illumination. The delafossite CuCrO(2) is p-type semiconductor characterized by a low band gap (1.28 eV) and a long-term chemical stability. The corrosion rate is found to be 10(-2) micromol m(-2)month(-1) in aqua regia. The oxide has been elaborated through nitrate route where the specific surface area is increased via the surface/bulk ratio. A correlation exists between the dark M(2+) adsorption, the redox potential of M(2+/0) couple and the conduction band of CuCrO(2) positioned at -1.06 V(SCE). Ag(+) cannot be photoreduced because of its positive potential located far above the valence band. By contrast, Zn(2+) is efficiently deposited due to the large driving force at the interface. The improved photoactivity of copper with a deposition percentage (90%) is attributed to the strong dark adsorption onto the surface catalyst. The results indicate a competitive effect with the water reduction; it has been observed that the M(2+) deposition goes parallel with the hydrogen evolution. Such behavior is attributed to the low H(2) over voltage when ultra fine aggregate of M islands are photodeposited onto CuCrO(2) substrate. PMID:18384943

Ketir, W; Bouguelia, A; Trari, M

2008-10-30

18

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

19

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

20

New layered compounds with honeycomb ordering: Li3Ni2BiO6, Li3NiM'BiO6 (M' = Mg, Cu, Zn), and the delafossite Ag3Ni2BiO6.  

PubMed

The new layered compound Li(3)Ni(2)BiO(6) has been prepared by a solid-state reaction. It crystallizes in the monoclinic C2/m space group; its lamellar structure is characterized by a honeycomb ordering between Ni(2+) and Bi(5+) within the slabs, while Li(+) ions occupy octahedral sites in the interslab space. Stacking defects weakly alter the XRD pattern. By substitution of half of the nickel ions, the new phases Li(3)NiM'BiO(6) (M' = Mg, Cu, Zn) isostructural with Li(3)Ni(2)BiO(6) have been synthesized under similar conditions. All these compounds demonstrate paramagnetic behavior at high temperature, and Li(3)Ni(2)BiO(6) exhibits an antiferromagnetic ordering at 5.5 K. By topotactic molten salt ionic exchange, the new delafossite compound Ag(3)Ni(2)BiO(6) has been also obtained and characterized. PMID:22515322

Berthelot, Romain; Schmidt, Whitney; Muir, Sean; Eilertsen, James; Etienne, Laetitia; Sleight, A W; Subramanian, M A

2012-05-01

21

Adsorption of Pd, Pt, Cu, Ag, and Au monomers on NiAl(110) surface: a comparative study from DFT calculations.  

PubMed

First principles calculations based on periodic density functional theory (DFT) have been used to investigate the structural, energetic and electronic properties of different transition metal atoms (Pd, Pt, Cu, Ag, and Au) on the NiAl(110) surface at low coverages (0.08 and 0.25 monolayer). All adatoms prefer to adsorb on 4-fold coordinated sites interacting with two Al and two Ni atoms and forming polar and covalent bonds, respectively. The calculated negative work function changes are explained by the effect of positive surface image created after adsorption, which induces the polarization of the negatively charged adsorbates. Consequently, for metals with similar electronegativity as Ni (Ag and Cu), this polarization effect becomes more significant and leads to larger negative work function changes, but the charge transferred is small. PMID:24219765

San-Miguel, Miguel A; Amorim, Edgard P M; da Silva, E Z

2014-08-01

22

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

23

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

24

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

25

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

26

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

27

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

28

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

Microsoft Academic Search

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

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

1995-01-01

29

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

30

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

NASA Astrophysics Data System (ADS)

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

Hedayati, Kambiz

2014-11-01

31

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

SciTech Connect

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

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

2014-12-01

32

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

33

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

34

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

35

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

36

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

37

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

38

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

PubMed

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

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

2014-04-01

39

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

SciTech Connect

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

Geretschlaeger, M.; Benka, O.

1986-08-01

40

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

41

Double dumbbell shaped AgNi alloy by pulsed electrodeposition  

SciTech Connect

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

Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India); Narayanan, V., E-mail: stephen-arum@hotmail.com; Stephen, A., E-mail: stephen-arum@hotmail.com [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai-600 025 (India)

2014-01-28

42

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

43

Surface segregation of Ag Cu Au trimetallic clusters  

NASA Astrophysics Data System (ADS)

Segregation phenomena of Ag-Cu-Au trimetallic clusters with icosahedral structure are investigated by using a Monte Carlo method based on the second-moment approximation of the tight-binding (TB-SMA) potentials. We predict that the Ag atoms segregate to the surface of the Ag-Cu-Au trimetallic icosahedral clusters. The Ag concentrations in the surface layer of the clusters are about 11-29 at.% higher than the overall Ag concentration in all the cases studied. The simulation results also indicate that the Au atoms are mainly distributed in the middle shell and the Cu atoms are located in the center for the 147-, 309-, 561- and 923-atom clusters at 300 K. The segregation phenomena of the Ag, Au and Cu atoms in the Ag-Cu-Au trimetallic clusters are mainly due to the different surface energies of the Ag, Au and Cu atoms. It is found that the size and composition have little effect on the segregation phenomena of Ag, Au and Cu atoms in the Ag-Cu-Au trimetallic cluster.

Cheng, Daojian; Liu, Xin; Cao, Dapeng; Wang, Wenchuan; Huang, Shiping

2007-11-01

44

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

45

Enhanced Noble Gas Adsorption in Ag@MOF-74Ni  

SciTech Connect

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

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

2014-01-14

46

Effects of Ag on the Kirkendall void formation of Sn-xAg/Cu solder joints  

NASA Astrophysics Data System (ADS)

Binary Sn-Ag solders with varying amounts of Ag (0.5, 2.0, and 3.5 wt %) were reacted with Cu under bump metallurgy (UBM) which was electroplated with bis-sodium sulfopropyl-disulfide additive, and the characteristics of Kirkendall void formation at the solder joints were investigated. The results indicate that the propensity to form Kirkendall voids at the solder joint decreased with the Ag content. Subsequent Auger electron spectroscopy analyses showed that Ag dissolved in the Cu UBM reduced the segregation of S to the Cu3Sn/Cu interface, which suppressed the nucleation of Kirkendall voids at the interface.

Kim, Sunghwan; Yu, Jin

2010-10-01

47

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

48

Reactions between oxides and Ag-sheathed Bi2Sr2CaCu2Ox conductors  

NASA Astrophysics Data System (ADS)

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

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

2005-07-01

49

Synthesis and characterization of Ag-Co-Ni nanowires.  

PubMed

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

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

2014-09-01

50

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

51

Investigation on plated Ni/Cu contact for mono-crystalline silicon solar cells  

NASA Astrophysics Data System (ADS)

Silicon solar cells are required to be processed with low cost and high efficiency. Ag paste, which is frequently used for the front contact of commercial screen-printed solar cells, has high contact resistance and high cost. Therefore, it is necessary to develop an inexpensive metallization technique with improved cell performance. As an alternative, plated Ni/Cu contact was used to fabricate low cost and high efficiency solar cells in this paper. Ni/Cu metals have low cost, low contact resistance and high conductivity. Ni was formed for low contact resistance and barrier to plated Cu, which was the main contact for low cost and high conductivity. In particular, a plated Ni layer is a very crucial factor that determines performance of the contact for plated Ni/Cu solar cells. A plated Ni layer has a decisive effect on contact resistance, series resistance and fill factor. In this paper, Ni electroless plating conditions (deposition time and pH) were varied to form a well plated Ni layer. For an optimized Ni electroless plating condition (5 min of deposition time and 8.5 of pH), the efficiency of plated Ni/Cu contact solar cells recorded 18.68%.

Kim, Dong Ho; Lee, Soo Hong

2013-09-01

52

The use of shape memory alloy NiTi particles in SnPbAg matrix: interfacial chemical analysis and mechanical characterisation  

Microsoft Academic Search

Uncoated and copper electroless coated fine NiTi superelastic particles have been incorporated into a liquid SnPbAg matrix. The wettability of the Cu coating by the molten alloy was determined with a wetting balance. The composite interfaces have been investigated by Auger electron spectroscopy (AES). Uncoated NiTi reacted with the matrix to form NiSn intermetallics, whereas the Cu layer of coated

J. F Silvain; J Chazelas; M Lahaye; S Trombert

1999-01-01

53

Intermetallic compounds formed during the reflow and aging of Sn-3.8Ag-0.7Cu and Sn-20In-2Ag-0.5Cu solder ball grid array packages  

NASA Astrophysics Data System (ADS)

After reflow of Sn-3.8Ag-0.7Cu and Sn-20In-2Ag-0.5Cu solder balls on Au/Ni surface finishes in ball grid array (BGA) packages, scallop-shaped intermetallic compounds (Cu0.70Ni0.28Au0.02)6Sn5 (IM1a) and (Cu0.76Ni0.24)6(Sn0.86In0.14)5 (IM1b), respectively, appear at the interfaces. Aging at 100C and 150C for Sn-3.8Ag-0.7Cu results in the formation of a new intermetallic phase (Cu0.70Ni0.14Au0.16)6Sn5 (IM2a) ahead of the former IM1a intermetallics. The growth of the newly appeared intermetallic compound, IM2a, is governed by a parabolic relation with an increase in aging time, with a slight diminution of the former IM1a intermetallics. After prolonged aging at 150C, the IM2a intermetallics partially spall off and float into the solder matrix. Throughout the aging of Sn-20In-2Ag-.5Cu solder joints at 75C and 115C, partial spalling of the IM1b interfacial intermetallics induces a very slow increase in thickness. During aging at 115C for 700 h through 1,000 h, the spalled IM1b intermetallics in the solder matrix migrate back to the interfaces and join with the IM1b interfacial intermetallics to react with the Ni layers of the Au/Ni surface finishes, resulting in the formation and rapid growth of a new (Ni0.85Cu0.15)(Sn0.71In0.29)2 intermetallic layer (IM2b). From ball shear tests, the strengths of the Sn-3.8Ag-0.7Cu and Sn-20In-2Ag-0.5Cu solder joints after reflow are ascertained to be 10.4 N and 5.4 N, respectively, which drop to lower values after aging.

Cheng, M. D.; Chang, S. Y.; Yen, S. F.; Chuang, T. H.

2004-03-01

54

Microstructure evolution and properties of CuAg microcomposites with different Ag content  

Microsoft Academic Search

The CuAg microcomposites containing 6, 12 and 24wt.% Ag were prepared by cold drawing combined with intermediate heat treatments. The microstructure was observed and the tensile strength and electrical conductivity were determined at various draw ratios. The original ? dendrites, eutectic colonies and secondary precipitates evolve into filamentary bundles with tight arrangement of double phases during heavy cold drawing. The

J. B. Liu; L. Meng; Y. W. Zeng

2006-01-01

55

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

E-print Network

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

Ciria, M.

56

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

57

Influence of ni thickness on oscillation coupling in Cu/Ni multilayers  

NASA Astrophysics Data System (ADS)

The results of investigation of magnetic properties of [Cu/Ni]x100 were presented. Samples were deposited by face-to-face sputtering method onto the silicon substrate, the thickness of Cu layer was constant (dCu = 2 nm) and the thickness of Ni layer - variable (1 nm <= dNi <= 6 nm). In Cu/Ni multilayers, for the thickness of Ni layer bigger than 2 nm antiferromagnetic coupling (A-F) were observed, for the thickness of Ni smaller than 2 nm A-F coupling is absent.

Gagorowska, B.; Dus-Sitek, M.

2007-08-01

58

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

NASA Astrophysics Data System (ADS)

Magnetic measurements on electrodeposited Ni-Cu/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 dNi-Cu=3 nm and dCu?0.75 nm.

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

1999-06-01

59

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

60

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

PubMed

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

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

2014-10-29

61

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

NASA Astrophysics Data System (ADS)

We investigated the self-diffusion of Ni in liquid Ni, Ni80P20, Pd40Ni40P20, and Pd43Ni10Cu27P20 at temperatures up to 1795K 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.

2004-11-01

62

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

Microsoft Academic Search

Three Pb-free solders, SnCu0.7, SnAg3.8Cu0.7 and SnAg3.5 were evaluated on both electroless NiP and electroplated Cu under bump metallurgies (UBM) for flip chip applications. Eutectic SnPb37 solder was also evaluated as a baseline comparison with the Pb-free solders. Test dice with a size of 12.67.5 mm2 were direct flip chip attached to test boards with variety of solder alloy\\/UBM combinations.

Charles Zhang; Jong-Kai Lin; Li Li

2001-01-01

63

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

64

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

65

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

66

Oxidation behaviour of Cu-Ni(Mn) (constantan) films  

Microsoft Academic Search

The oxidation of constantan films has been investigated using Cu-Ni(Mn) single films and (Cu-Ni(Mn))-NiCr film configurations by measurements of electrical resistance and Auger electron spectra depth profiling, as well as by thermogravimetric and differential thermoanalytical studies. Oxidation starts under air and argon atmosphere between 300 and 350 C. Under an N2-H2 gas mixture a passivating film formed by a double

W. Brckner; S. Baunack; G. Reiss; G. Leitner; Th. Knuth

1995-01-01

67

Solubility and partitioning behavior of Au, Cu, Ag and reduced S in magmas  

NASA Astrophysics Data System (ADS)

Experiments have been conducted at 200 MPa, 800-1030 C, and fO2 0.8 log units below the Ni-NiO buffer to determine the solubility of Au, Cu and Ag in silicate melts and pyrrhotite. The metal activities were imposed by using Au965Ag020Cu015 alloy capsules. Sulfur-free and sulfur-bearing systems were studied with otherwise identical melt compositions to assess the relative effect of S on the solubility of these metals. The data show that the major element composition of the silicate melt only moderately affects the solubility of Au, Ag and Cu between basalt and dacite, yielding solubilities identical within 50% relative. In comparison, solubilities in the rhyolite melts are lower by a factor of 1.5-2.5 for Cu and higher by up to a factor of 5 for Ag, depending on the aluminum saturation index of the melt. The solubilitiy of Ag significantly increases with increasing peraluminousity above an aluminum saturation index of 1. The effect of melt composition is significant on the solubility of Au in S-bearing melts, in part due to its effect on the sulfur concentration at sulfide saturation. The effect of S is the most pronounced in peralkaline rhyolites and mafic melts, and minimal in peraluminous rhyolites. The solubilities of all three metals significantly decrease with decreasing temperature. The concentration of sulfur in the melt at sulfide saturation and its volatile/melt partition coefficient are primarily determined by the FeO activity in the melt and the activity coefficients of dissolved FeS species, which appear to correlate with the degree of melt polymerization. The volatile/melt partition coefficient of reduced S increases from 79 4 (1?) to 635 80 as the melt composition changes from basalt to slightly peraluminous rhyolite, and from 225 13 to 776 148 as the aluminium saturation index increases from 0.7 to 1.1 in rhyolites. At 1000 C, pyrrhotite/silicate melt partition coefficients for Cu increase from 540 30 (1?) to 1140 110 from basalt to dacite, whereas the partition coefficients for Ag are nearly constant at 50 10. The partition coefficients of Au increase from 180 20 to 900 210 from basalt to dacite. Pyrrhotite/rhyolite melt partition coefficients for Cu, Ag and Au increase by about an order of magnitude as temperature drops from 1000 C to 800 C. At typical S concentrations for arc magmas (500-2000 ?g/g), the budget of Ag in the magma will not be controlled by pyrrhotite, whereas primary control on the Au and Cu budget by pyrrhotite may only be relevant in intermediate to felsic magmas.

Zajacz, Zoltn; Candela, Philip A.; Piccoli, Philip M.; Sanchez-Valle, Carmen; Wlle, Markus

2013-07-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2007-01-01

69

[Synthesis of Cu2O-Ag-AgBr/MA visible photocatalyst and its performance in degradation of 2-chlorophenol].  

PubMed

Cu2O-Ag-AgBr/MA plasmon photocatalyst was prepared by the co-deposition of Cu2O and Ag-AgBr nanoparticles on mesoporous alumina (MA). The samples were characterized by means of X-ray diffraction (XRD) ,X-ray photoelectron spectroscopy (XPS) and diffuse reflectance UV-vis spectra (UV-vis DRS). The results showed that both Ag+ and Ag0 existed on the surface. The photocatalytic activity of the samples prepared were evaluated by degradation of 2-chlorophenol (2-CP) under visible light (? >420 nm) irradiation. The results showed that the catalyst had high photocatalytic activity for the degradation of 2-CP. Meanwhile, the doping of Cu2O nanoparticles significantly inhibited the release of silver ions during the photocatalytic reaction, which improved the photostability of the catalyst. Analyses on the effects of various scavengers showed that h+ , O2- and OH radicals were the primary active species. PMID:25518659

Wang, Ran; Zhou, Xue-feng; Hu, Xue-xiang; Hu, Chun

2014-09-01

70

A novel multifunctional NiTi/Ag hierarchical composite  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

71

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

72

Passivation and ClInduced Depassivation of Cu-Ag Alloys in  

Microsoft Academic Search

The electrochemical behaviour of two Cu-Ag alloys, namely (20wt%Cu + 80wt%Ag) and (80wt%Cu + 20wt%Ag) alloys, was studied in 0.15 M borax and 0.15 M boric acid buffer solution, pH =8.45, by means of cyclic voltammetry, potentiodynamic anodic polarization and current\\/ time transients techniques. SEM and XRD microanalysis were used to examine the changes caused by the electrochemical perturbations. The

73

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

74

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

75

Studies on the electronic structure of Ag 2NiO 2, an intercalated delafossite containing subvalent silver  

Microsoft Academic Search

Structural and electronic properties of Ag2NiO2 and AgNiO2 were investigated and compared. Single crystal X-ray diffraction experiments on Ag2NiO2 at 100 K provide evidence for a ferrodistortive phase below 260 K. Ni K-edge and Ag LIII-edge XANES spectra, both measured and simulated, as well as core level and valence band photoelectron spectra are analysed. They agree well with the results

Ulrich Wedig; Peter Adler; Jrgen Nuss; Hartwig Modrow; Martin Jansen

2006-01-01

76

Preparation of high-permeability NiCuZn ferrite*  

PubMed Central

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

Hu, Jun; Yan, Mi

2005-01-01

77

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

SciTech Connect

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

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

1996-12-31

78

New CuM 2\\/3Sb 1\\/3O 2 and AgM 2\\/3Sb 1\\/3O 2 compounds with the delafossite structure  

Microsoft Academic Search

Several new compounds have been prepared with the delafossite structure: CuMn2\\/3Sb1\\/3O2, CuCo2\\/3Sb1\\/3O2, CuNi2\\/3Sb1\\/3O2, CuZn2\\/3Sb1\\/3O2, CuMg2\\/3Sb1\\/3O2, AgNi2\\/3Sb1\\/3O2, and AgZn2\\/3Sb1\\/3O2. The structures of the CuM2\\/3Sb1\\/3O2 compounds are generally based on 2H stacking along the c axis, and the M2+ and Sb5+ cations can be ordered or disordered. The structures of the AgM2\\/3Sb1\\/3O2 compounds are based on 3R stacking along c with the

R. Nagarajan; S. Uma; M. K. Jayaraj; J. Tate; A. W. Sleight

2002-01-01

79

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

PubMed Central

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

2012-01-01

80

Modified Ni-Cu catalysts for ethanol steam reforming  

NASA Astrophysics Data System (ADS)

Three Ni-Cu catalysts, having different Cu content, supported on ?-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N2 adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150C amorphous carbon was evidenced, while at 350C crystalline, filamentous carbon is formed.

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

2013-11-01

81

Electronic structure studies of DyNi4Cu  

NASA Astrophysics Data System (ADS)

Electronic structure of the DyNi4Cu compound, crystallising in the hexagonal CaCu5-type of structure has been studied using the XPS method as well as the self-consistent spin-polarised TB-LMTO (tigh-binding linear muffin-tin orbital) method. Our calculations show that DyNi4Cu is ferromagnetically ordered at 0 K. The analysis of the valence band shape in vicinity of the Fermi level shows that this part of the spectrum comes mainly from 3d electrons of Ni and Cu atoms. The features of the experimental XPS valence band spectra near the Fermi level are reproduced in our calculations. Peaks below -7.5 eV are connected with the contribution of the f -electrons of Dy. The obtained peak positions in the valence band are in good agreement with the binding energies of metallic dysprosium, copper and nickel.

Pugaczowa-Michalska, M.; Chekowska, G.; Toliski, T.; Kowalczyk, A.

2006-01-01

82

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

83

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

Microsoft Academic Search

Fahlerz group sulfosalts having the general structural formula (Ag, Cu) III 6 [(Ag, Cu) 2\\/3 (Fe, Zn) 1\\/3 ] IV 6 (As, Sb) 4 S 13 have been equilibrated with the assemblage electrum + pyrite + chalocopyrite in reversed exchange experiments. Control of log ( a s ) at -6.0 was maintained by abundant FeS 2 + (Fe .05 Zn

Denton S. Ebel; Richard O. Sack

1989-01-01

84

Effect of Cu and Ag solute segregation on ?Sn grain boundary diffusivity  

Microsoft Academic Search

We investigate the effect of various amounts of Ag and Cu solute atoms on the self-diffusivity of Sn in the (101) symmetric tilt ?Sn grain boundary. Using molecular dynamics simulations over a temperature range of 300 K to 450 K, we show that both Ag and Cu decrease the grain boundary self-diffusivity of Sn as the amount of solute in

Michael S. Sellers; Andrew J. Schultz; Cemal Basaran; David A. Kofke

2011-01-01

85

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

Microsoft Academic Search

Fahlerz group sulfosalts having the general structural formula (Ag, Cu){sup III}((Ag, Cu)(Fe, Zn)){sup IV}(As, Sb)S have been equilibrated with the assemblage electrum + pyrite + chalocopyrite in reversed exchange experiments. Control of log (a{sub s}) at -6.0 was maintained by abundant FeS + (Fe{sub .05}Zn{sub .95})S and minimum vapor space. Reversal brackets demonstrate that the Ag\\/(Ag + Cu) and As\\/(As

Denton S Ebel; Richard O Sack

1989-01-01

86

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

NASA Astrophysics Data System (ADS)

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

Hong, Seongik; Kim, Namsoo

2015-01-01

87

Transient liquid-phase bonding in the NiAl/Cu/Ni system -- A microstructural investigation  

SciTech Connect

A transmission electron microscopy based investigation of microstructural development in NiAl-Ni transient liquid bonding, using commercial purity copper interlayers, is presented in this article. The article considers the mechanisms of isothermal solidification in NiAl/Cu/Ni joints and the influence of copper diffusion from the joint centerline on the microstructures of the adjacent NiAl and Ni substrates. Changes in the microstructure of the bond centerline due to entry of aluminum (from the NiAl substrate) and Ni (from both the NiAl and the Ni substrates) are discussed. Transfer of aluminum from the NiAl substrate to the Ni substrate is also examined. The precipitation of both L1{sub 2} type {gamma}{prime} and B2 type {beta} phases at the joint centerline is investigated. Precipitation of {gamma}{prime} within both the NiAl and Ni substrates is considered. The formation of Al type {gamma} phases in the NiAl substrate is also examined.

Gale, W.F.; Guan, Y. [Auburn Univ., AL (United States). Materials Research and Education Center

1996-11-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

89

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

90

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

91

Thermoelectric properties of electrodeposited CuNi alloys on Si  

NASA Astrophysics Data System (ADS)

Thin films with the composition of the constantan alloy (a solid solution with 35 to 50 wt. % of Ni in Cu) have a high-thermoelectric power, which allows the fabrication of very sensitive heat-flux sensors based on planar technology. In this article, the thermoelectric properties of CuxNi100-x thin films electrodeposited on silicon were studied as a function of the composition, temperature, and thickness. The electrodeposition of thin layers on silicon is an important step for the integration of thermal sensors with semiconductor technology. The CuxNi100-x alloys were electrodeposited potentiostatically at room temperature, from a citrate electrolyte containing both copper and nickel sulfates. The layer composition was controlled by the applied potential in the range from pure copper (at -0.4 V/SCE) up to a solid solution of about 25 wt. % Cu in Ni (at -1.2 V/SCE). Extremely high values of thermoelectric power were measured for very thin layers of Cu40Ni60 on Si, showing a strong influence of the substrate. By considering the system as a thermoelectric bilayer and extracting the contribution of the semiconductor, thermopower values for the Cu40Ni60 alloys comparable to the expected ones for constantan wires were obtained.

Delatorre, R. G.; Sartorelli, M. L.; Schervenski, A. Q.; Pasa, A. A.; Gths, S.

2003-05-01

92

ECAE-processed Cu-Nb and Cu-Ag nanocomposite wires for pulse magnet applications  

SciTech Connect

Cu-Nb and Cu-Ag nanocomposites have recently become of interest to pulse magnet designers because of their unusual combination of high strength with reasonable conductivity. In the as-cast condition, these conductors consist of two phases, one of almost pure Nb (or Ag) and the other almost pure Cu. When these castings are cold worked as in a wire-drawing operation for example, the two phases are drawn into very fine filaments which produce considerable strengthening without an unacceptable decrease in conductivity. Unfortunately, any increase in strength with operations such as wire drawing is accompanied by a reduction in the cross section of the billet, and thus far, no wires with strengths on the order of 1.5 GPa or more have been produced with cross sections large enough to be useful in magnet applications. Equal Channel Angular Extrusion (ECAE) is an innovative technique which allows for the refinement of the as-cast ingot structure without a reduction in the cross sectional dimensions. Samples processed by the ECAE technique prior to wire drawing should be stronger at a given wire diameter than those processed by wire drawing alone. The tensile properties of wire-drawn Cu-18%Nb and Cu-25%Ag both with and without prior ECAE processing were tested and compared at both room temperature and 77K. All samples were found to have resistivities consistent with their strengths, and the strengths of the ECAE-processed wires were significantly higher than their as-cast and drawn counterparts. Therefore, with ECAE processing prior to wire drawing, it appears to be possible to make high-strength conductors with adequately large cross sections for pulse magnets.

Edgecumbe Summers, T.S.; Walsh, R.P.; Pernambuco-Wise, P. [National High Magnetic Field Lab., Tallahassee, FL (United States)] [and others

1997-06-01

93

Diffusion and electromigration in lead alloys. II. Ag, Au, and Cu in lead-indium  

NASA Astrophysics Data System (ADS)

As a sequel to certain studies of ``fast diffusers'' in lead-tin alloys, we have carried out a comparable program for lead-indium alloys with silver, gold, and copper as mobile elements. It has been found that the addition of In greatly increased DAg up to 60 times, but made the electromigration parameter Z*a,Ag more negative and it eventually became zero. On the other hand, DAu drops quickly with the addition of In, indicating an Au-In binding energy of about 0.5 eV. The comparable binding energy of Ni with In was found to be 1.1 eV. For the mobile copper, DCu decreased when In was introduced at low concentration but started increasing when In concentration was 7 at. %. Measurements of electromigration of Au and Cu indicated that the added In has little influence on Z*a.

Shi, Jinghong; Mei, Shao-ning; Huntington, H. B.

1987-07-01

94

Enhanced low temperature thermoelectric performance of Ag-doped BiCuSeO  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

95

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

PubMed

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

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

2014-10-01

96

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

NASA Astrophysics Data System (ADS)

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

Huang, M. L.; Yang, F.

2014-11-01

97

Dual bonding between H2O/H2S and AgCl/CuCl: Cu/Ag bond, sister bond to Au bond.  

PubMed

Recently, Legon et al. reported the first generation and characterization of H2O/H2SAgCl complexes by rotational spectroscopy and proposed whether there is a silver bond analogous to the more familiar hydrogen and halogen bonds. In this study, a theoretical investigation was performed to answer this question and to deepen the nature of intermolecular interactions for H2O/H2SM-Cl (M = Cu, Ag, and Au) complexes. NBO analyses reveal that two types of delocalization interactions coexist in these complexes. Apart from the expected ?-donation interaction, the hyperconjugation interaction between H2O/H2S and M-Cl also takes part in the bonding. On the basis of such a dual-bonding mechanism, one class of bond, termed Cu/Ag bond, was defined in this study. In addition, the topological properties at a bond critical point, binding energies, and stretching frequency shifts studied here support that Cu/Ag bond is a sister bond to Au bond put forward previously by Sadlej et al. The Cu/Ag/Au bond is partially covalent and partially electrostatic in nature. Finally, the dual-bonding mechanism of Cu/Ag/Au bond was further discussed. This dual-bonding scheme may be considered a new synergistic bonding model for coordination compounds. PMID:24070212

Zhang, Guiqiu; Zhao, Xingjuan; Chen, Dezhan

2013-10-24

98

Intermetallic Compounds Formed in Sn-20In-2.8Ag Solder BGA Packages with Ag/Cu Pads  

NASA Astrophysics Data System (ADS)

The interfacial reactions in a Sn-20In-2.8Ag solder ball grid array (BGA) package with immersion Ag surface finish are investigated. After reflow, the Ag thin film dissolves quickly into the solder matrix, and scallop-shaped intermetallic layers, with compositions of (Cu0.98Ag0.02)6(In0.59Sn0.41)5, appear at the interfaces between Sn-20In-2.8Ag solder ball and Cu pad. No evident growth of the (Cu0.98Ag0.02)6(Sn0.59In0.41)5 intermetallic compounds was observed after prolonged aging at 100 C. However, the growth accelerated at 150 C, with more intermetallic scallops floating into the solder matrix. The intermetallic thickness versus the square root of reaction time ( t 1/2) shows a linear relation, indicating that the growth of intermetallic compounds is diffusion-controlled. Ball shear tests show that the strength of Sn-20In-2.8Ag solder joints after reflow is 4.4 N, which increases to 5.18 N and 5.14 N after aging at 100 and 150 C, respectively.

Jain, C. C.; Wang, S. S.; Huang, K. W.; Chuang, T. H.

2009-03-01

99

Infinite-layer LaNiO2:?Ni1+ is not Cu2+  

Microsoft Academic Search

The Ni ion in LaNiO$_2$ has the same formal ionic configuration $3d^9$ as\\u000adoes Cu in isostructural CaCuO$_2$, but it is reported to be nonmagnetic and\\u000aprobably metallic whereas CaCuO$_2$ is a magnetic insulator. From ab initio\\u000acalculations we trace its individualistic behavior to (1) reduced $3d-2p$\\u000amixing due to an increase of the separation of site energies ($\\\\epsilon_d -

K.-W. Lee; W. E. Pickett

2004-01-01

100

Spin trimers in Ca3Cu2Ni(PO4)4  

NASA Astrophysics Data System (ADS)

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

Ghosh, M.; Ghoshray, K.

2012-07-01

101

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

2014-07-21

102

Spin-pumping-enhanced magnetic damping in ultrathin Cu(0 0 1)/Co/Cu and Cu(0 0 1)/Ni/Cu films  

NASA Astrophysics Data System (ADS)

The influence of the Cu capping layer thickness on the spin pumping effect in ultrathin epitaxial Co and Ni films on Cu(0 0 1) was investigated by in situ ultrahigh vacuum ferromagnetic resonance. A pronounced increase in the linewidth is observed at the onset of spin pumping for capping layer thicknesses dCu larger than 5 ML, saturating at dCu = 20 ML for both systems. The spin mixing conductance for Co/Cu and Ni/Cu interfaces was evaluated.

Charilaou, M.; Lenz, K.; Kuch, W.

2010-07-01

103

Influence of Ag on the microstructure and magnetic properties of perpendicular exchange coupled composite L10-[FePt-Ag]/[Co/Ni]N films  

NASA Astrophysics Data System (ADS)

Two series of exchange coupled composite films with and without Ag interlayer, L10-[FePt-Ag]/[Co/Ni]N (FC-Ag-N) and FePt/[Co/Ni]N (FC-N), were prepared and well studied. Coercivities of both series decrease with the increase of the soft [Co/Ni]N thickness. However, well-isolated sphere grains are observed in FC-Ag-N samples, instead of a ledge-type structure in FC-N samples. The average grain size is almost constant for FC-Ag-N films, regardless of the thickness of Co/Ni multilayer. It indicates that Ag effectively suppresses the grain coarseness during the deposition of [Co/Ni]N.

Guo, H. H.; Chu, H. G.; Ma, B.; Zhang, Z. Z.; Jin, Q. Y.; Wang, H.; Wang, J. P.

2013-06-01

104

Giant magnetoresistance and magnetic properties of electrodeposited Ni-Co-Cu/Cu multilayers  

NASA Astrophysics Data System (ADS)

The room-temperature magnetoresistance (MR) and magnetization characteristics were investigated for electrodeposited Ni-Co-Cu(3 nm)/Cu( dCu) multilayers with dCu=1 and 2 nm 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=1 nm, whereas a significantly smaller GMR with no systematic dependence on Co-content was observed for dCu=2 nm. Concurrent increase of the coercive field ( Hc) and the MR peak position ( Hp) with Co-content was observed for dCu=1 nm up to a Co:Ni ratio of 1:1, beyond which Hp increased faster than Hc, with Hp?2 Hc when the ratio reached 4:1. For films containing approximately equal quantities of Co and Ni, the MR vs. H curves could be successfully fitted by a Langevin function. This was interpreted by ascribing the magnetization contribution for magnetic fields above about 2 Hc to superparamagnetic (SPM) regions which form due to the electrochemical deposition conditions between the non-magnetic Cu layer and the ferromagnetic (FM) Ni-Co-Cu layer. The formation of such intermixed interfaces is a general phenomenon in electrodeposited multilayers, leading to a strongly reduced antiferromagnetic coupling of the magnetizations of the neighbouring FM layers. In such cases, the observed GMR curves exhibit a typical concave shape and arise due to the slowly saturating SPM behaviour at the intermixed interfaces.

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

2002-12-01

105

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

E-print Network

45 (Constantan) and Cu70Ni30. Studies on surface roughness have been done. The effects of annealing of the industrial Constantan® (Cu55Ni44) alloys tapes. Result will be compared with the Cu70Ni30 alloys tape. hal. Annealing treatments were adjusted (see previous work [4]), to 950°C and 900°C for constantan and Cu70Ni30

Boyer, Edmond

106

Kinetics of facile bilayer island formation at low temperature: Ag/NiAl(110).  

PubMed

Facile nucleation and growth of bilayer Ag(110) islands on NiAl(110) is observed by STM for Ag deposition at temperatures as low as 127 K. Density functional theory analysis for supported Ag films determines adatom adsorption energies (which favor bilayer islands), interaction energies, and diffusion barriers. Analysis of an atomistic lattice-gas model incorporating these energies elucidates the role of strongly anisotropic interactions in enabling the upward mass transport needed for bilayer island formation. PMID:18517802

Han, Yong; Unal, Baris; Qin, Feili; Jing, Dapeng; Jenks, C J; Liu, Da-Jiang; Thiel, P A; Evans, J W

2008-03-21

107

Kinetics of Facile Bilayer Island Formation at Low Temperature: Ag/NiAl(110)  

SciTech Connect

Facile nucleation and growth of bilayer Ag(110) islands on NiAl(110) is observed by STM for Ag deposition at temperatures as low as 127 K. Density functional theory analysis for supported Ag films determines adatom adsorption energies (which favor bilayer islands), interaction energies, and diffusion barriers. Analysis of an atomistic lattice-gas model incorporating these energies elucidates the role of strongly anisotropic interactions in enabling the upward mass transport needed for bilayer island formation.

Han, Yong; Unal, Baris; Qin, Feili; Jing, Dapeng; Jenks, C.J.; Liu, Da-Jiang; Thiel, P.A.

2008-03-21

108

Magneto-Optical Spectra in Co/MgO, Ni/MgO, Co/Ag and Ni/Ag Multilayers  

NASA Astrophysics Data System (ADS)

We investigated magnetization and magneto-optical spectra in Co/MgO, Ni/MgO, Co/Ag and Ni/Ag multilayers. All samples were prepared by magnetron sputtering. Crystal structures were determined by a small or middle angle X-ray diffraction pattern. More than four superlattice peaks were observed in all multilayers including MgO layers. Sharp superlattice peaks were observed in all multilayers including Ag layers. Magnetization decreases with a smaller ferromagnetic layer thickness in both Ag and MgO systems at room temperature. The same tendency was observed at 5 K. However, the results in the magneto-optical spectra show a contrast between MgO systems and Ag systems. The shape of the off-diagonal element of the conductivitytensor (??xy) changes drastically with the ferromagnetic layer thickness in MgO systems. However, the shape of the tensor ??xy does not depend on the ferromagnetic layer thickness in Ag systems. This contrasting result reflects the difference of the effect of interfaces on electrons in the ferromagnetic layers between insulating MgO and metal Ag.

Sato, Hideki; Miyazaki, Terunobu

1999-12-01

109

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

PubMed

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

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

2014-09-24

110

Ni Interdiffusion Coefficient and Activation Energy in Cu6Sn5  

NASA Astrophysics Data System (ADS)

Ni diffusion in Cu6Sn5 intermetallic compound was investigated. First, we successfully fabricated preferred-orientation Cu6Sn5 crystal by liquid-phase electroepitaxy (LPEE). Then, Ni/Cu6Sn5 diffusion couples were produced by sputtering from a Ni thin film onto the Cu6Sn5 crystal. Ni/Cu6Sn5 diffusion couples were annealed at different temperatures of 120C, 160C, 200C, 255C, 290C, and 320C for 2 h in a vacuum. The Ni atomic profile across the Ni/Cu6Sn5 interface was obtained by electron spectroscopy for chemical analysis (ESCA). From the Ni atomic profiles, the Matano method was used to evaluate the Ni interdiffusion coefficients ( tilde{D}_{{Ni}} ) in the Cu6Sn5 crystal obtained with different annealing temperatures, which then yields the activation energy for Ni diffusion in the Cu6Sn5 crystal at a particular Ni content. We found that, as Ni diffuses in the ternary Cu6- x Ni x Sn5 compound phase, the activation energy of Ni interdiffusion decreases with the Ni content.

Huang, Kuan-Chih; Shieu, Fuh-Sheng; Hsiao, Y. H.; Liu, C. Y.

2012-01-01

111

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

112

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

SciTech Connect

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

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

2011-11-17

113

Growth and characterization of graphene on CuNi substrates  

NASA Astrophysics Data System (ADS)

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

Tyagi, Parul

114

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

PubMed

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

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

2011-06-01

115

Electronic structure of Zn, Cu and Ni impurities in germanium.  

PubMed

We present a density functional modelling study of Zn, Cu and Ni impurities in hydrogen-terminated germanium clusters. Their electronic structure is investigated in detail, especially their Jahn-Teller instabilities and electrical levels. Interstitial and substitutional defects were considered and the latter were found to be the most stable defect form for nearly all Fermi level positions. Relative formation energies are estimated semi-empirically with the help of the measured formation energy of the single Ge vacancy. We find that while Zn is a double shallow acceptor, Cu and Ni are deep acceptors with levels close to the available experimental data. Donor levels were only found for interstitial Cu and Zn. PMID:21406934

Silva, E L; Coutinho, J; Carvalho, A; Torres, V J B; Barroso, M; Jones, R; Briddon, P R

2011-02-16

116

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

117

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

118

Spectroscopy of microcrystals in the CuI-AgI system  

SciTech Connect

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

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

1994-06-01

119

Ag 2CuMnO 4: A new silver copper oxide with delafossite structure  

Microsoft Academic Search

The use of hydrothermal methods has allowed the synthesis of a new silver copper mixed oxide, Ag2CuMnO4, the first example of a quaternary oxide containing both elements. It crystallizes with the delafossite 3R structure, thus being the first delafossite to contain both Ag and Cu. Synthesis conditions affect the final particle size (30500nm). Powder X-ray diffraction Rietveld refinement indicates a

David Muoz-Rojas; Gloria Subas; Judith Or-Sol; Jordi Fraxedas; Benjamn Martnez; Montse Casas-Cabanas; Jess Canales-Vzquez; Jose Gonzalez-Calbet; Ester Garca-Gonzlez; Richard I. Walton; Nieves. Casan-Pastor

2006-01-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

121

Effect of Cu and Ag solute segregation on betaSn grain boundary diffusivity  

Microsoft Academic Search

We investigate the effect of various amounts of Ag and Cu solute atoms on the self-diffusivity of Sn in the (101) symmetric tilt betaSn grain boundary. Using molecular dynamics simulations over a temperature range of 300 K to 450 K, we show that both Ag and Cu decrease the grain boundary self-diffusivity of Sn as the amount of solute in

Michael S. Sellers; Andrew J. Schultz; Cemal Basaran; David A. Kofke

2011-01-01

122

Structural and Permeation Kinetic Correlations in PdCuAg Membranes.  

PubMed

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

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

2014-12-24

123

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

124

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

125

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

SciTech Connect

Epitaxially grown FeMn/Ni/Cu(001) films are investigated by Photoemission Electron Microscopy and Magneto-Optic Kerr Effect. We find that as the FeMn overlayer changes from paramagnetic to antiferromagnetic state, it could switch the ferromagnetic Ni spin direction from out-of-plane to in-plane direction of the film. This phenomenon reveals a new mechanism of creating magnetic anisotropy and is attributed to the out-of-plane spin frustration at the FeMn-Ni interface.

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

2009-03-08

126

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

NASA Astrophysics Data System (ADS)

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.

Zhao, Jun; Zhang, Dongming; Zhao, Jie

2011-09-01

127

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

Microsoft Academic Search

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

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

2011-01-01

128

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

Microsoft Academic Search

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

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

2011-01-01

129

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

NASA Astrophysics Data System (ADS)

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

Ebel, Denton S.; Sack, Richard O.

1989-09-01

130

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

SciTech Connect

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

Rettew, Robert [Georgia Institute of Technology; Meyer, Axel [ORNL; Senanayake, Sanjaya D [ORNL; Chen, Tsung-Liang [ORNL; Petersburg, Cole [Georgia Institute of Technology; Flege, J. Ingo [University of Bremen, Bremen, Germany; Falta, Jens [University of Bremen, Bremen, Germany; Alamgir, Faisal [ORNL

2011-01-01

131

Interactions of Oxygen and Ethylene with Submonolayer Ag Films Supported on Ni(111)  

SciTech Connect

We investigate the oxidation of, and the reaction of ethylene with, Ni(111) with and without sub-monolayer Ag adlayers as a function of temperature. The addition of Ag to Ni(111) is shown to enhance the activity towards the ethylene epoxidation reaction, and increase the temperature at which ethylene oxide is stable on the surface. We present a systematic study of the formation of chemisorbed oxygen on the Ag-Ni(111) surfaces and correlate the presence and absence of O{sup 1-} and O{sup 2-} surface species with the reactivity towards ethylene. By characterizing the samples with low-energy electron microscopy (LEEM) in combination with X-ray photoelectron spectroscopy (XPS), we have identified specific growth of silver on step-edge sites and successfully increased the temperature at which the produced ethylene oxide remains stable, a trait which is desirable for catalysis.

Alamgir, F.M.; Senanayake, S.; Rettew, R.E.; Meyer, A.; Chen, T.-L.; Petersburg, C.; Flege, J.I.; Falta, J.

2011-06-01

132

Interactions of Oxygen and Ethylene with Submonolayer Ag Films Supported on Ni(111)  

SciTech Connect

We investigate the oxidation of, and the reaction of ethylene with, Ni(111) with and without sub-monolayer Ag adlayers as a function of temperature. The addition of Ag to Ni(111) is shown to enhance the activity towards the ethylene epoxidation reaction, and increase the temperature at which ethylene oxide is stable on the surface. We present a systematic study of the formation of chemisorbed oxygen on the Ag-Ni(111) surfaces and correlate the presence and absence of O{sup 1-} and O{sup 2-} surface species with the reactivity towards ethylene. By characterizing the samples with low-energy electron microscopy (LEEM) in combination with X-ray photoelectron spectroscopy (XPS), we have identified specific growth of silver on step-edge sites and successfully increased the temperature at which the produced ethylene oxide remains stable, a trait which is desirable for catalysis.

R Rettew; A Meyer; S Senanayake; T Chen; C Petersburg; J Flege; J Falta; F Alamgir

2011-12-31

133

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

SciTech Connect

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

Piccinin, Simone [School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia); CNR-INFM DEMOCRITOS National Simulation Center, Theory-Elettra Group, Trieste (Italy); Zafeiratos, Spiros [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); LMSPC-UMR 7515 du CNRS, Strasbourg (France); Stampfl, Catherine [School of Physics, University of Sydney, Sydney, New South Wales 2006 (Australia); Hansen, Thomas W.; Haevecker, Michael; Teschner, Detre; Girgsdies, Frank; Knop-Gericke, Axel; Schloegl, Robert; Scheffler, Matthias [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin (Germany); Bukhtiyarov, Valerii I. [Boreskov Institute of Catalysis, SB RAS, Novosibirsk 630090 (Russian Federation)

2010-01-22

134

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

SciTech Connect

Using in situ scanning transmission electron microscopy heating experiments, we observed the formation of a 3-dimensional (3D) epitaxial Cu-core and Ag-shell equilibrium structure of a Cu-Ag nanoalloy. The structure was formed during the thermal interaction of Cu(?12 nm) and Ag NPs(?6 nm) at elevated temperatures (150300?C) by the Ag NPs initially wetting the Cu NP along its (111) surfaces at one or multiple locations forming epitaxial Ag/Cu (111) interfaces, followed by Ag atoms diffusing along the Cu surface. This phenomenon was confirmed through Monte Carlo simulations to be a nanoscale effect related to the large surface-to-volume ratio of the NPs.

Lu, Ping, E-mail: plu@sandia.gov; Chandross, Michael; Boyle, Timothy J.; Clark, Blythe G.; Vianco, Paul [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185 (United States)

2014-02-01

135

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

136

Industrial Cu-Ni alloys for HTS coated conductor tape  

NASA Astrophysics Data System (ADS)

Copper rich Cu-Ni alloys have been textured with the RABiTS method in order to get non-magnetic and cost efficient substrates for coated conductor wires. The study is focused on two industrial compositions: Cu55Ni45 (Constantan) and Cu70Ni30. Studies on surface roughness have been done. The effects of annealing conditions (temperature and atmosphere) on the grain boundaries deepness were analyzed. Electrolytic polishing was also applied to improve the surface quality. RX pole figures and micro hardness measurements have been achieved on samples annealed up to 950C. Attention has been paid to the rolling texture and to the annealing processes. The rolling texture has been found to be mainly copper-type (C, S and B contributions). Beginning of recrystallization occurred between 400C and 600C and stabilized between 900C to 950C, depending on the nickel content of the alloy. Finally both samples, rolled and annealed under the appropriate conditions, have been characterized. Pole figure measurements gave the global in plane and out of plane disorientations of our samples which are in-plane 7.4 and out-plane (RD) 4.3 for both samples. EBSD maps have shown the details of the distribution and have allowed us to quantify the ratio between cubic {100}<001> and twined {122}<21-2> orientations.

Girard, A.; Bruzek, C. E.; Jorda, J. L.; Ortega, L.; Soubeyroux, J. L.

2006-06-01

137

Probing antiferromagnetism in NiMn/Ni/(Co)/Cu3Au(001) single-crystalline epitaxial thin films  

E-print Network

grown on Ni/Cu3Au (001) is probed by means of magneto-optical Kerr effect (MOKE). Thickness://jap.aip.org/resource/1/JAPIAU/v113/i2 Published by the American Institute of Physics. Related Articles Effect of Fe (MLs) NiMn order antiferromagnetically at room temperature. It is found that NiMn can couple to out

Kuch, Wolfgang

138

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

Microsoft Academic Search

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

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

2005-01-01

139

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

SciTech Connect

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

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

2002-01-15

140

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

141

Diffusion bonding of electroless Ni plated WC composite to Cu and AISI 316 stainless steel  

Microsoft Academic Search

In this study, a composite containing WC (Tungsten Carbide) and Ni was produced by two different processing routes. Electroless\\u000a Ni coated WC powders were consolidated and sintered at 1200 C. Diffusion bonding couples of WC(Ni)-electrolytic Cu, WC(Ni)-AISI\\u000a 316 stainless steel and WC(Ni)-WC(Ni) were manufactured by using a preloaded compression system under Ar atmosphere. Diffusion\\u000a bonding was carried out at varying

Ahmet Ynetken; Mehmet akmakkaya; Ayhan Erol; ?kr Tala?

2011-01-01

142

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

143

Synthesis of carbon encapsulated metal (Ni and Cu) nano particles and applications for chiral catalysts  

Microsoft Academic Search

Carbon-encapsulated Ni and Cu nanoparticles with a core\\/shell structure were synthesized by levitational gas condensation\\u000a (LGC). Methane (CH4) gas was used to coat the surface of the Ni and Cu nanoparticles. The Ni particles had a core diameter of 10nm, and were\\u000a covered by 23nm thin carbon layers. In the case of Cu, the particles had a core diameter of

Young Rang Uhm; Hi Min Lee; Fedorova Olga; Ovchinnikova Irina; Valova Marina; Rusinov Gennady; Charushin Valery; Chang Kyu Rhee

2010-01-01

144

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

145

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

NASA Astrophysics Data System (ADS)

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

Choi, Gyung-Min; Cahill, David G.

2014-12-01

146

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

147

Origin of giant magnetoresistance contributions in electrodeposited Ni-Cu/Cu multilayers  

NASA Astrophysics Data System (ADS)

The magnetoresistance (MR) and magnetization were studied at room temperature and down to 4.2 K for Ni 81Cu 19(3 nm)/Cu( dCu) multilayers with 0.5 nm?d Cu?3 nm and for a bulk Ni 81Cu 19 alloy, all produced by electrodeposition. For most of the multilayers, giant magnetoresistance (GMR) was observed with a maximum around 1-1.5 nm Cu-layer thicknesses. The room-temperature MR curves consisted of a rapidly varying low-field component up to about 1 kOe and a slowly varying high-field component persisting beyond 18 kOe. For Cu-layer thicknesses around the maximum GMR, the low-field component dominated whereas for dCu>1.5 nm, it became comparable to or smaller than the high-field component. For the bulk alloy, anisotropic magnetoresistance was observed. According to the room-temperature magnetization curves, both the bulk alloy and the multilayers exhibited ferromagnetic (FM) behaviour with technical saturation around 1-3 kOe. For the multilayers, the low-field MR curves with a small peak splitting were characteristic of uncoupled or weakly coupled magnetic layers. Magnetic measurements from 5 to 300 K indicated that besides an FM contribution, these multilayers also exhibit a superparamagnetic (SPM) component with blocking temperature around 220 K. From an analysis of the present results, the low-field MR component could be attributed to the FM domains with their magnetizations exhibiting a random in-plane distribution in the zero-field (demagnetized) state and the high-field MR component to a contribution due to SPM regions. All these considerations are supported by the complete saturation of the MR in a magnetic field of 4 kOe at T=4.2 K.

Bakonyi, I.; Tth, J.; Kiss, L. F.; Tth-Kdr, E.; Pter, L.; Dinia, A.

2004-02-01

148

Transport properties and lithium insertion study in the p-type semi-conductors AgCuO2 and AgCu0.5Mn0.5O2  

E-print Network

12 October 2008 Available online 18 November 2008 Keywords: Lithium batteries Delafossite p-Type semi mechanism into the first mixed valence silver­copper oxide AgCuO2 and the B-site mixed magnetic delafossite reaction. During the solid solution, a rapid structure amorphization was observed. The delafossite AgCu0

Poeppelmeier, Kenneth R.

149

Thermal behavior of the Cu22.55at.%Al alloy with small Ag additions  

Microsoft Academic Search

In this study the effect of Ag additions on the thermal behavior of the Cu22.55at.%Al alloy was studied using electrical\\u000a resistivity measurements, in situ X-ray diffractometry, differential scanning calorimetry, and optical microscopy. The results\\u000a indicated that Ag additions do not change the phase transformations sequence in the studied alloys, but modify its critical\\u000a temperatures due to a change on entropy

R. A. G. Silva; A. T. Adorno; A. G. Magdalena; T. M. Carvalho; M. Stipcich; A. Cuniberti; M. L. Castro

2011-01-01

150

Kondo lattice and heavy fermions in Heusler phases: CeInAg 2?x Cu x  

Microsoft Academic Search

Magnetic properties, electrical resistivity, specific heat and magnetic excitations have been investigated in Heusler phases CeInAg2-xCux. The hybridization continuously increases from CeInAg2 (antiferromagnetic Kondo lattice) to CeInCu2 (heavy fermion compound). The specific heat coefficient for this last compound is found to reach 1.2 J\\/mole. K2 at 1.4 K, the Kondo temperature is 6 K and the Wilson ratio is close

R. Lahiouel; J. Pierre; E. Siaud; R. M. Galera; M. J. Besnus; J. P. Kappler; A. P. Murani

1987-01-01

151

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

152

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

153

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

NASA Astrophysics Data System (ADS)

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

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

2009-06-01

154

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

155

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

156

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

SciTech Connect

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

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

2005-01-15

157

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

SciTech Connect

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

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

2013-12-15

158

Microstructure and its development in Cu-Al-Ni alloys  

NASA Astrophysics Data System (ADS)

The microstructure of as-cast Cu-AI-Ni alloys, based on copper containing 9 to 10 wt pct Al and up to 5 wt pct Ni, has been examined. The development of the microstructure on continuous cooling has also been investigated. For alloys with 9.2 to 9.3 wt pct Al, and less than 1 wt pct Ni, the as-cast microstructure consists of proeutectoid ? solid solution, ? + ?2 eutectoid, and martensitic ?. If the nickel content is more than 2.5 wt pct, the ? + ?2 eutectoid is replaced by ? + ?{2/'} eutectoid, and no martensitic ? is observed in the as-cast alloys. The morphologies of the ?{2/'} and ?2 eutectoid phases are similar; both have the Kurdjumov-Sachs (K-S) orientation relationship with the a phase. Two eutectoid reactions, involving ? to ? + ?2 and ? to ? + ?'2, have been observed in an alloy containing 9.7 wt pct Al and 2.7 wt pct Ni. When both eutectoid reactions occur, the Nishiyama-Wassermann (N-W) orientation relationship exists between ?2 or ?{2/'} and the ? phase. During continuous cooling, proeutectoid ? solid solution is the first phase to precipitate from the high-temperature ? phase. The ? to ? + ?{2/'} eutectoid reaction starts at higher temperatures than the ? to ? + ?2 reaction. Tempering of the as-cast alloys results in the elimination of the martensitic ?.

Sun, Y. S.; Lorimer, G. W.; Ridley, N.

1990-02-01

159

Texture and Microstructure in High Strength Cu-Ag Conductors for DC Magnets National High Magnetic Field Laboratory  

E-print Network

conductors for a high field DC magnet is the Cu-Ag composite. After deformation to large strains, the material evolves into a nanostructured composite that leads to a high strength that is essential Cu-Ag composites that have the potential to be developed as a high strength conductor for high field

Weston, Ken

160

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

161

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

Microsoft Academic Search

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

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

1997-01-01

162

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

SciTech Connect

Fahlerz group sulfosalts having the general structural formula (Ag, Cu){sup III}{sub 6}((Ag, Cu){sub 2/3}(Fe, Zn){sub 1/3}){sup IV}{sub 6}(As, Sb){sub 4}S{sub 13} have been equilibrated with the assemblage electrum + pyrite + chalocopyrite in reversed exchange experiments. Control of log (a{sub s}) at {minus}6.0 was maintained by abundant FeS{sub 2} + (Fe{sub .05}Zn{sub .95})S and minimum vapor space. Reversal brackets demonstrate that the Ag/(Ag + Cu) and As/(As + Sb) ratios in this sulfosalt are strongly correlated, at a fixed composition of coexisting electrum. Evaluated in the context of the thermochemical model of Sack et al. (1987), these results indicate that the molar Gibbs energy of the reciprocal reaction Ag{sub 10}Fe{sub 2}Sb{sub 4}S{sub 13} + Cu{sub 10}Fe{sub 2}As{sub 4}S{sub 13} {r equilibrium} Ag{sub 10}Fe{sub 2}As{sub 4}S{sub 13} + Cu{sub 10}Fe{sub 2}Sb{sub 4}S{sub 13}, ({Delta}{bar G}{sup 0}{sub 34}) is 12.25 {plus minus} 1.92 kilocalories. This provides a crucial missing parameter for the thermodynamic calculations the authors have developed earlier. This model is applied to calculation of end-member activities; integration with studies of hydrothermal fluids in ore-forming systems is planned.

Ebel, D.S.; Sack, R.O. (Purdue Univ., West Lafayette, IN (USA))

1989-09-01

163

Effectiveness of the use of Ag, Cu and PAA to disinfect municipal wastewater.  

PubMed

The WHO defines Category A wastewater as one which does not contain more than 1000 FCU 100 ml(-1) of faecal coliforms (FC) and less than 1 helminth egg (HE) per litre. The objectives of this work were to determine: 1) the disinfectant capacity of different concentrations of silver (Ag), silver-copper (Ag-Cu) and silver-copper-peracetic acid (Ag-Cu-PAA) when added to samples of raw wastewater (RW), with a contact time of 60 minutes; 2) the optimal concentration and contact time required by the better performing disinfectant, determined from the previous stage, to obtain Category A RW; 3) the effect of the selected disinfectant when applied to RW, the effluent of activated sludge (ASE) and the effluent of sand filters (FE) for 10, 30 and 60 min duration. The Ag:Cu:PAA ratio of 0.6:6.0:100.0 mg l(-1), showed the best disinfectant capability to produce Category A wastewater. The ratio of 0.1:1.0:20.0 mg l(-1) of Ag:Cu:PAA and a contact time of 10 minutes are the optimal values to produce Category A wastewater in RW. For RW and ASE, the optimal ratios and times for Ag:Cu:PAA were: 1.2:12.0:90.0 mg l(-1) at 60 min and 0.1:1.0:20.0 for 10 min, respectively. The FE samples showed concentrations of FC and HE below the standards of the WHO; therefore, their disinfection is not necessary. PMID:19278154

Luna-Pabello, V M; Miranda Ros, M; Jimnez, B; Orta de Velasquez, M T

2009-02-01

164

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

165

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

166

Bonding relationships in some ternary and quarternary phosphide and tetrahedrite structures: (Ag6M4P12)M6', Cu12+xSb4S13 and Cu14-xSb4S13, Ln6Ni6P17  

Microsoft Academic Search

Electronic structure calculations are reported for three different, but structurally related, types of ternary or quaternary compounds that can be classified as derivatives of tetrahedral structures. The compounds (Ag6M4P12)M6' (M=Ge, Sn; M'=Ge, Si) are calculated to have semiconducting properties, with forbidden energy gaps of about 0.7-0.9 eV. It is shown that structurally there materials contain Ag6 octahedral clusters trapped in,

D. W. Bullett; W. G. Dawson

1986-01-01

167

Atomistic processes of damage evolution in neutron-irradiated Cu and Ni at high temperature  

Microsoft Academic Search

This paper consists of two parts. In part 1, the experimental results of damage evolution of neutron-irradiated Cu and Ni are described. In part 2, results of computer simulations are described with linkage of experimental data to explore the atomistic process of damage evolution. To study experimentally the atomistic processes of damage evolution in neutron-irradiated Cu and Ni in part

Yoshiharu Shimomura; Ichiro Mukouda; Kenjiro Sugio; Ping Zhao

1999-01-01

168

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

169

Analysis of Corrosion Products Formed on Cu-Ni Alloys Immersed in Sea Water  

Microsoft Academic Search

A method was developed for separation and analysis of corrosion products formed on the surface of Cu-Ni alloys immersed in sea water polluted by sulphide ions. This method is based on the selective dissolution of oxidation compounds by suitable solvents dissolving the metal matrix only to a negligeable extent.The following solvents were used: 1) methanol to dissolve Na, Cu, Ni

A. M. Beccaria

1988-01-01

170

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

PubMed

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

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

2013-05-28

171

Cu-Al-Ni-SMA-Based High-Damping Composites  

NASA Astrophysics Data System (ADS)

Recently, absorption of vibration energy by mechanical damping has attracted much attention in several fields such as vibration reduction in aircraft and automotive industries, nanoscale vibration isolations in high-precision electronics, building protection in civil engineering, etc. Typically, the most used high-damping materials are based on polymers due to their viscoelastic behavior. However, polymeric materials usually show a low elastic modulus and are not stable at relatively low temperatures (?323 K). Therefore, alternative materials for damping applications are needed. In particular, shape memory alloys (SMAs), which intrinsically present high-damping capacity thanks to the dissipative hysteretic movement of interfaces under external stresses, are very good candidates for high-damping applications. A completely new approach was applied to produce high-damping composites with relatively high stiffness. Cu-Al-Ni shape memory alloy powders were embedded with metallic matrices of pure In, a In-10wt.%Sn alloy and In-Sn eutectic alloy. The production methodology is described. The composite microstructures and damping properties were characterized. A good particle distribution of the Cu-Al-Ni particles in the matrices was observed. The composites exhibit very high damping capacities in relatively wide temperature ranges. The methodology introduced provides versatility to control the temperature of maximum damping by adjusting the shape memory alloy composition.

Lpez, Gabriel A.; Barrado, Mariano; San Juan, Jose; N, Mara Luisa

2009-08-01

172

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

NASA Astrophysics Data System (ADS)

Thin films of ZnS and ZnO:Cu were grown by an original metal-organic chemical vapour deposition (MOCVD) method under atmospheric pressure onto glass substrates. Pulse photo-assisted rapid thermal annealing of ZnO:Cu films in ambient air and at the temperature of 700-800 ?C was used instead of the common long-duration annealing in a vacuum furnace. ZnO:Ag thin films were prepared by oxidation and Ag doping of ZnS films. At first a closed space sublimation technique was used for Ag doping of ZnO films. The oxidation and Ag doping were carried out by a new non-vacuum method at a temperature >500 ?C. Crystal quality and optical properties were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence (PL). It was found that the doped films have a higher degree of crystallinity than undoped films. The spectra of as-deposited ZnO:Cu films contained the bands typical for copper, i.e. the green band and the yellow band. After pulse annealing at high temperature the 410 and 435 nm photoluminescent peaks were observed. This allows changing of the emission colour from blue to white. Flat-top ZnO:Ag films were obtained with the surface roughness of 7 nm. These samples show a strong ultraviolet (UV) emission at room temperature. The 385 nm photoluminescent peak obtained is assigned to the exciton-exciton emission.

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

2007-07-01

173

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

PubMed Central

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

2013-01-01

174

Angled High Strain Rate Shear Testing for SnAgCu Solder Balls  

Microsoft Academic Search

A high speed shear test of solder ball at different shear angles has been developed and investigated for SnAgCu solder balls. The objective of the test is to introduce vertical loading component in the high speed shear test and to study intermatallic response of different solder balls. The shear test is performed at three angles of attack e. g. 3,

John Laua

175

Angled high strain rate shear testing for SnAgCu solder balls  

Microsoft Academic Search

A high speed shear test of solder ball at different shear angles has been developed and investigated for SnAgCu solder balls. The objective of the test is to introduce vertical loading component in the high speed shear test and to study intermetallic response of different solder balls. The shear test is performed at three angles of attack e. g. 3,

T. C. Chai; D. Q. Yu; John Lau; W. H. Zhu; X. R. Zhang

2008-01-01

176

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

PubMed

The ground and low-lying excited states of heteronuclear diatomic CuAg are examined by multi-reference configuration interaction (MRCI) method. Relativistic effects were treated and probed in two steps. Scalar terms were considered using the spin-free DKH Hamiltonian as a priori and spin-orbit coupling was calculated perturbatively via the spin-orbit terms of the Breit-Pauli Hamiltonian based on MRCI wavefunctions. Potential energy curves of the spin-free states and their corresponding ? components correlating with the separated atom limits (2)S(Cu) + (2)S(Ag) and (2)D(Cu) + (2)S(Ag) are obtained. The results are in fine agreement with the experimental measurements and tentative conclusions for the ion-pair B0(+) state are confirmed by our theoretical calculations. Illustrative results are presented to reveal the relative importance and magnitude of the scalar and spin-orbit effects on the spectroscopic properties of this molecule. Time dependent density functional theory calculations, using the LDA, BLYP, B3LYP, and SAOP functionals have been carried out for CuAg and the accuracy of TD-DFT has been compared with ab initio results. PMID:25338890

Alizadeh, Davood; Jamshidi, Zahra; Shayesteh, Alireza

2014-10-21

177

Liquid metal\\/ceramic interactions in the (Cu, Ag, Au)\\/ZrB 2 systems  

Microsoft Academic Search

Wetting and spreading experiments on ZrB2 in contact with liquid Cu, Ag and Au have been performed by the sessile drop technique under a vacuum. The wetting and spreading characteristics and the interfacial reactions are discussed as a function of time and of the metal involved. The interfacial morphologies, analysed by optical microscopy, SEM and EDS show the presence of

Alberto Passerone; Maria Luigia Muolo; Rada Novakovic; Daniele Passerone

2007-01-01

178

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

179

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

Microsoft Academic Search

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

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

2002-01-01

180

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

NASA Astrophysics Data System (ADS)

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

Yang, Linmei; Zhang, Z. F.

2015-01-01

181

Positron-annihilation study of the aging kinetics of AlCu-based alloys. II. Ag microalloying  

NASA Astrophysics Data System (ADS)

Positron-annihilation spectroscopy has been applied for studying the effects of microalloying additions of Ag to Al-4%Cu and Al-4%Cu-0.3%Mg (wt %) alloys on the aging kinetics and on the association of vacancies to solute elements. The results show that: (i) in Al-Cu, the addition of Ag increases (from 0.32 to 0.61 eV) the effective activation energy that controls the formation of solute aggregates; (ii) on the contrary, in the Al-Cu-Mg alloy, the activation energy is decreased (from 0.65 to 0.22 eV); (iii) in Al-Cu and in Al-4%Cu-0.3%Ag (wt %) alloys the solute aggregates (clusters or GP zones) formed after long aging at temperatures below 70 C do not contain vacancies; (iv) in Al-Cu-Mg, the addition of Ag enhances the formation of co-clusters (or GPB zones) containing Mg and vacancies; (v) the formation of Mg-rich aggregates is enhanced by Ag also at a high aging temperature (180 C), and this leads to a better stabilization of the structure produced by artificial aging. The above effects are interpreted as due to the tendency of Ag atoms to bind vacancies in the Al-Cu and vacancy-Mg complexes in Al-Cu-Mg.

Somoza, A.; Dupasquier, A.; Polmear, I. J.; Folegati, P.; Ferragut, R.

2000-06-01

182

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

183

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

184

Neutron Time of Flight phonon spectra of Cu2O and Ag2O powders  

NASA Astrophysics Data System (ADS)

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

Winn, Barry; Hagen, Mark; Shapiro, Steve

2009-03-01

185

Thermoelectric properties of molten Bi2Te3, CuI, and AgI  

NASA Astrophysics Data System (ADS)

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

Nishikawa, Kazutaka; Takeda, Yasuhiko; Motohiro, Tomoyoshi

2013-01-01

186

Atomistic modeling of the site occupancies of Ti and Cu in NiAl  

SciTech Connect

In a recent paper by Wilson and Howe, experimental evidence, regarding the site occupancy of two simultaneous alloying additions to NiAl, points to the possibility of a change in site occupancy behavior with concentration. They analyzed five B2 structured NiAl-Ti-Cu alloys to determine, via Atom Location by Channeling Enhanced Microanalysis (ALCHEMI), the site occupancies of Ti and Cu in Al-deficient and stoichiometric NiAl alloys. Three alloys were produced with Cu replacing Al (Ni{sub 50}Al{sub (47{minus}x)}Ti{sub 3}u{sub X} with X = 1, 3, 6) and two were made with Cu added in place of Ni (Ni{sub (50{minus}x)}Al{sub 47}Ti{sub 3}Cu{sub X}, with X - 1, 3). Their results showed that for Al-deficient alloys both Ti and Cu show a strong preference for Al sites (over 80% for both types of atoms) while much lower Cu concentrations are found in Al sites for Ni-deficient alloys. From this limited set of experimental results, interesting conclusions were drawn suggesting a close relationship between the site preference of the alloying additions and the Ni:Al ratio. The purpose of this paper is to show that even a limited amount of experimental data, coupled with economical atomistic simulations, can constitute a powerful tool for examining specific details on otherwise complex systems for which an exhaustive experimental analysis is prohibitive.

Bozzolo, G.; Noebe, R.D.; Garces, J.E.

2000-01-31

187

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

PubMed

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

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

2014-05-15

188

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

189

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

Microsoft Academic Search

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

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

1992-01-01

190

Ferromagnetic resonance in 80Ni?Fe/Cu/Co multilayer films  

NASA Astrophysics Data System (ADS)

Trilayers and multilayers containing ferromagnetic 80Ni?Fe,Co layers separated by nonmagnetic Cu layers were fabricated using the magnetron sputtering method. For 80Ni?Fe(60 )/Cu (d Cu)/ Co(60 ) trilayer films, the MR ratio and the exchange coupling strength oscillated with increasing dCu. For 80Ni?Fe(60 )/Cu (d Cu)/ Co(60 )/Cu (d Cu)/ 80Ni?Fe(60 ) multilayer films, however, the exchange coupling between the bottom 80Ni?Fe and the Co layers oscillated, while that between the Co and the top 80Ni?Fe layers decreased monotonously with increasing dCu. Consequently, antiferromagnetic exchange coupling was not achieved between the Co(60 ) and the top magnetic layer. The reason for the nonexistence of antiferromagnetic exchange coupling is discussed by taking into account the rougher surface of the Co(60 ) layer caused by the growth of the different crystalline structures.

Koizumi, H.; Ando, Y.; Miyazaki, T.

1996-12-01

191

Aqueous Synthesis of Nontoxic Ag2Se/ZnSe Quantum Dots Designing as Fluorescence Sensors for Detection of Ag(I) and Cu(II) Ions.  

PubMed

We reported the synthesis of water-soluble and nontoxic Ag2Se/ZnSe Quantum Dots (QDs) using for fluorescence sensors. The influences of various experimental conditions including the synthesis pH, types of ligand, feed ratios, and the refluxed time on the growth process and fluorescence of QDs were investigated in detail. Under optimal conditions, Ag2Se/ZnSe QDs show a single emission peak around 490nm with the maximal photoluminescence (PL) quantum yield (QYs) of 13.7%. As-prepared Ag2Se/ZnSe QDs can be used for detection of Ag(II) and Cu(II). The detection limits are 1??10(-6)mol/L to 5??10(-5)mol/L for Ag (I), and 2??10(-6)mol/L to 1.10??10(-4)mol/L for Cu(II). PMID:25391903

Wang, Chunlei; Xu, Shuhong; Zhao, Zengxia; Wang, Zhuyuan; Cui, Yiping

2014-11-14

192

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

193

Syntheses, structures, physical properties, and theoretical studies of CeMxOS (M = Cu, Ag; x approximately 0.8) and CeAgOS.  

PubMed

Black single crystals of the two nonstoichiometric cerium coinage-metal oxysulfide compounds CeCu(x)OS and CeAg(x)OS (x approximately 0.8) have been prepared by the reactions of Ce2S3 and CuO or Ag2O at 1223 or 1173 K, respectively. A black powder sample of CeAgOS has been prepared by the stoichiometric reaction of Ce2S3, CeO2, Ag2S, and Ag at 1073 K. These isostructural materials crystallize in the ZrSiCuAs structure type with two formula units in the tetragonal space group P4/nmm. Refined crystal structure results and chemical analyses provide evidence that the previously known anomalously small unit-cell volume of LnCuOS for Ln = Ce (Ln = rare-earth metal) is the result of Cu vacancies and the concomitant presence of both Ce3+ and Ce4+. Both CeCu(0.8)OS and CeAgOS are paramagnetic with mu(eff) values of 2.13(6) and 2.10(1) mu(B), respectively. CeCu(0.8)OS is a p-type semiconductor with a thermal activation energy Ea = 0.22 eV, sigma(electrical) = 9.8(1) 10(-3) S/cm at 298 K, and an optical band gap Eg < 0.73 eV. CeAgOS has conductivity sigma(conductivity) = 0.16(4) S/cm and an optical band gap Eg = 0.71 eV at 298 K. Theoretical calculations with an on-site Coulomb repulsion parameter indicate that the Ce 4f states are fully spin-polarized and are not localized in CeCuOS, CeCu(0.75)OS, or CeAgOS. Calculated band gaps for CeCu(0.75)OS and CeAgOS are 0.6 and 0.8 eV, respectively. PMID:16999426

Chan, George H; Deng, Bin; Bertoni, Mariana; Ireland, John R; Hersam, Mark C; Mason, Thomas O; Van Duyne, Richard P; Ibers, James A

2006-10-01

194

Magnetoelastic coupling in epitaxial Cu/Ni90Fe10/Cu/Si(001) thin films  

NASA Astrophysics Data System (ADS)

Magnetic anisotropy energy (MAE) and magnetoelastic (ME) stress in epitaxial Cu(4 nm)/Ni90Fe10/Cu(160 nm)/Si(001) films have been studied at room temperature as a function of the permalloy film thickness (2 nm?tPm?50 nm). Magnetostatic energy keeps the magnetization within the film plane, although surface and magnetoelastic anisotropy energy favor magnetization normal to the film plane. The direct measurement of the magnetoelastic stress shows the ME coefficients to depend linearly on the strain, ?, for the ME coefficient. As a result, a second-order magnetoelastic contribution, proportional to ?2, has to be included in the MAE. Using both sets of measurement we determine two second-order ME coefficients, M1?,2=-0.3107 J/m3 and M2?,2=8.3107J/m3, and the surface magnetic anisotropy constant, Ksur=0.4 mJ/m2.

Ciria, M.; Ha, K.; Bono, D.; O'Handley, R. C.

2002-05-01

195

Static and dynamic magnetic properties of mechanically alloyed Fe9Cu5Ag86  

NASA Astrophysics Data System (ADS)

The static and dynamic magnetic behaviors of mechanically alloyed Fe9Cu5Ag86 have been investigated by field-dependent DC magnetization and frequency-dependent AC susceptibility. The results reveal the coexistence of small Fe particles and ferromagnetic particles of larger size. Rietveld refinement of the X-ray diffraction patterns confirms the existence of nanometric Fe grains (~6nm) and of Ag (~18nm). Despite the low Fe content, the existence of interactions among the magnetic particles is evident, as deduced from Henkel plots.

Garca Caldern, R.; Fernndez Barqun, L.; Pankhurst, Q. A.

2004-05-01

196

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

197

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

198

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

199

Valence and spin states in delafossite AgNiO2 and the frustrated Jahn-Teller system ANiO2 (A=Li,Na)  

Microsoft Academic Search

Electronic structures of delafossite oxides AgNi1-xCoxO2 and the frustrated Jahn-Teller (JT) system ANiO2 (A=Li,Na) have been investigated by employing soft x-ray absorption spectroscopy and photoemission spectroscopy (PES). It is found that Ni ions are in the Ni2+-Ni3+ mixed-valent states and that the low-spin (LS) Ni3+ component increases from LiNiO2 to AgNiO2 and NaNiO2 , in agreement with the presence of

J.-S. Kang; S. S. Lee; G. Kim; H. J. Lee; H. K. Song; Y. J. Shin; S. W. Han; C. Hwang; M. C. Jung; H. J. Shin; B. H. Kim; S. K. Kwon; B. I. Min

2007-01-01

200

Role of Long Range Interaction in Oxygen Superstructure Formation on Cu(001) and Ni(001)  

NASA Astrophysics Data System (ADS)

On the basis of electronic structure calculations, we show that the long range Coulomb interaction provides the driving mechanism for oxygen overlayer formation on Cu(001). We illustrate that this interaction in the precursor c(22) phase induces a missing row reconstruction of Cu(001), and leads to the (2(2)(2))R45 O structure, which has strong covalent pO-dCu coupling. For the c(22)O overlayer on Ni(001) and Cu(001), we show that pO-dNi bonding is larger than pO-dCu and serves to neutralize the perturbation of the Coulomb interaction induced by the O overlayer. Consequently, c(22)O/Ni(001)) is stable while c(22)O/Cu(001) exists only in limited environments.

Stolbov, Sergey; Rahman, Talat S.

2002-08-01

201

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

202

Transport properties and lithium insertion study in the p-type semi-conductors AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2}  

SciTech Connect

The transport properties and lithium insertion mechanism into the first mixed valence silver-copper oxide AgCuO{sub 2} and the B-site mixed magnetic delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} were investigated by means of four probes DC measurements combined with thermopower measurements and in situ XRD investigations. AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} display p-type conductivity with Seebeck coefficient of Q=+2.46 and +78.83 {mu}V/K and conductivity values of {sigma}=3.2x10{sup -1} and 1.8x10{sup -4} S/cm, respectively. The high conductivity together with the low Seebeck coefficient of AgCuO{sub 2} is explained as a result of the mixed valence state between Ag and Cu sites. The electrochemically assisted lithium insertion into AgCuO{sub 2} shows a solid solution domain between x=0 and 0.8Li{sup +} followed by a plateau nearby 1.7 V (vs. Li{sup +}/Li) entailing the reduction of silver to silver metal accordingly to a displacement reaction. During the solid solution, a rapid structure amorphization was observed. The delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} also exhibits Li{sup +}/Ag{sup +} displacement reaction in a comparable potential range than AgCuO{sub 2}; however, with a prior narrow solid solution domain and a less rapid amorphization process. AgCuO{sub 2} and AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} provide a discharge gravimetric capacity of 265 and 230 mA h/g above 1.5 V (vs. Li{sup +}/Li), respectively, with no evidence of a new defined phases. - Graphical abstract: Investigation on the transport properties of AgCuO{sub 2} and the new B-site mixed Delafossite AgCu{sub 0.5}Mn{sub 0.5}O{sub 2} shows a p-type conductivity of {sigma}=3.2x10{sup -1} and 1.8x10{sup -4} S/cm, respectively. The high conductivity, as a result from a high charge carrier density in AgCuO{sub 2} supports the existence of a mixed valence state between silver and copper. A particular emphasis is also placed on the electrochemical lithium insertion properties into these two materials by in situ XRD measurements to better insight on the Li{sup +} insertion mechanism and also scrutinize possible new compounds electrochemically accessible in the Li-Ag-Cu system.

Sauvage, F. [Department of Chemistry and Materials Research Center, Northwestern University, Evanston, IL 60208-3113 (United States)], E-mail: frederic.sauvage@u-picardie.fr; Munoz-Rojas, D. [Instituto de Ciencia de Materiales de Barcelona, CSIC, Campus UAB, 08193 Bellaterra, Barcelona (Spain)], E-mail: davidmunozrojas@gmail.com; Poeppelmeier, K.R. [Department of Chemistry and Materials Research Center, Northwestern University, Evanston, IL 60208-3113 (United States); Casan-Pastor, N. [Instituto de Ciencia de Materiales de Barcelona, CSIC, Campus UAB, 08193 Bellaterra, Barcelona (Spain)

2009-02-15

203

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

204

The structure of a commercial dental Ag-Pd-Cu-Au casting alloy.  

PubMed

The structure of a commercial dental Ag-Pd-Cu-Au casting alloy has been studied by microprobe and X-ray diffraction analyses after various heat treatments. The composition of phases in equilibrium was established. After being annealed at 400 degrees C, 500 degrees C, and 600 degrees C for seven wk, the alloy consisted of three phases: a Cu- and Pd-rich fee phase (alpha 1) with alpha = 0.372nm, a Ag-rich matrix (alpha 2) with alpha = 0.399nm, and an ordered CsCl-type bcc PdCu phase with alpha = 0.296nm. The PdCu phase was not observed above 600 degrees C, and the proportion of the alpha 1 phase decreased sharply above 700 degrees C. After being annealed at 900 degrees C, the alloy matrix was partly decomposed at the Cu-enriched grain boundaries. The decomposed areas grew into the grain interior during subsequent precipitation hardening. No segregation of Au was detected after casting, and the element was evenly distributed throughout the alloy structure after all heat treatments. PMID:6582096

Niemi, L; Her, H

1984-02-01

205

Facile synthesis of bimetal Au-Ag nanoparticles in a Cu(i) boron imidazolate framework with mechanochromic properties.  

PubMed

A Cu(i) boron imidazolate framework with 2-fold interpenetrating ths topology shows luminescent mechanochromism, and it can directly reduce bimetal Au-Ag nanoparticles into its structure, leading to catalytic applications. PMID:25486112

Wen, Tian; Zhang, De-Xiang; Liu, Juan; Zhang, Hai-Xia; Zhang, Jian

2014-12-23

206

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

PubMed

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

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

1990-07-01

207

Magnetic field effect on autocatalysis: Ag and Cu in concentrated nitric acid.  

PubMed

The partial suppression of corrosion of Ag and Cu in concentrated nitric acid solution by a magnetic field of up to 5 T was studied. The corrosion current density of these metals was found to diminish with magnetic field and rotation speed in a rotating disk electrode experiment. The suppression of corrosion is associated with removal of the catalyst HNO(2) from the electrode and passivation of the electrode surface. The Lorentz force was identified as the driving force responsible for the partial suppression of corrosion. A model based on the partial areas associated with active and passive regions on Ag and Cu electrodes is introduced to explain the dependence of the current density on the applied magnetic field. PMID:16553445

Rhen, F M F; Coey, J M D

2006-03-30

208

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

209

Nanostructured YbAgCu4 for potentially cryogenic thermoelectric cooling.  

PubMed

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

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

2014-09-10

210

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

211

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

PubMed Central

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

212

Enhanced creep performance in an AlCuMgAg alloy through underageing  

Microsoft Academic Search

Tests at 130 C and 150 C have shown that the creep resistance of an AlCuMgAg alloy is significantly increased if it is heat-treated at an elevated temperature to an underaged condition rather than the fully hardened, T6 temper. This beneficial effect of underageing is manifest in reduced rates of secondary creep. Similar results have been obtained for the commercial

R. N. Lumley; A. J. Morton; I. J. Polmear

2002-01-01

213

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

Microsoft Academic Search

A novel granular multilayer structure consisting of magnetic granular AgCo layers and non-magnetic Cu spacer layers is introduced to study their magnetotransport properties. The results are similar to those obtained from both conventional multilayers and granular single-films, but with a notable enhancement of low-field sensitivity compared to these structures. This can be attributed to a weak antiferromagnetic coupling across the

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

1997-01-01

214

A comparison of PRTs at the Cu Ag eutectic point (780 C)  

Microsoft Academic Search

Twelve platinum resistance thermometers (PRTs) were repeatedly calibrated between the triple point of water and the silver point. During each calibration their resistance was also determined at the Cu-Ag eutectic point. The temperatures indicated by the PRTs were within 1 mK, except for one that differed by 4 mK from the average, 779.6360 C, of the other eleven. Four of

J. Ancsin

2004-01-01

215

Jalpaite Ag3CuS2: a novel promising ternary sulfide absorber material for solar cells.  

PubMed

We report a novel promising semiconductor of Ag3CuS2 serving as absorber material in inorganic-organic solid-state solar cells for the first time, and the device (ITO/ZnO/Ag3CuS2/P3HT/Pt) exhibits a power conversion efficiency of 2.01%. This study opens up an available method to develop various ternary absorber materials for tertiary generation solar cells. PMID:25572525

Liu, Zhifeng; Han, Jianhua; Guo, Keying; Zhang, Xueqi; Hong, Tiantian

2015-01-29

216

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

SciTech Connect

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

Jung, Yong; Yu, Jin, E-mail: jinyu@kaist.ac.kr [Department of Materials Science and Engineering, Electronic Packaging Laboratory, KAIST, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2014-02-28

217

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

218

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

219

Effect of microstructure on thermal conductivity of Cu, Ag thin films.  

PubMed

Thin film type materials are widely used in modern industries, such as semiconductor devices, functional superconductors, machining tools, and so on. The thermal properties of material in semiconductor are very important factors for stable operation because the heat generated during device operation may increase clock frequency. Even though thermal properties of thin films may play a major role in assessing reliability of parts, the measurement methods of thin film thermal properties are generally known to be complex to devise. In this study, a temperature distribution method was applied for the measurement of thermal conductivity of Cu and Ag thin film on borosilicate glass substrate. Cu and Ag thin films were deposited on borosilicate glass using thermal evaporation processes. To measure the thermal conductivity changes according to the microstructure of metallic thin film, the processing variables for the Cu and Ag thin film deposition were changed. To minimize the effect of film thickness, the film thickness was fixed to the thickness of approximately 500 nm throughout experiments. The thermal conductivities of thin films were measured to be much lower than those of bulk materials. Thin film with larger grain size showed higher thermal conductivity probably due to the lower number density of grain boundary. Weidman-Franz law could be applied to thin films produced in this study. Thermal conductivity was also estimated from the resistivity of thin film and Lorenz number of bulk material. PMID:20358967

Ryu, Sang; Juhng, Woonam; Kim, Youngman

2010-05-01

220

Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial AgCu nanoparticles  

SciTech Connect

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

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

2014-03-15

221

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

222

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

223

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

224

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

NASA Astrophysics Data System (ADS)

A series of 125[NiFeCu(3 nm)/Cu(1 nm)] multilayers were electrodeposited on strong (110) textured Cu substrates from electrolytes containing different Fe ion concentrations under potentiostatic control. The compositional analysis by energy dispersive X-ray spectroscopy demonstrated that as the Fe ion concentration in the electrolyte is increased, the Fe content of the multilayers increased. X-ray diffraction measurements indicated that all samples exhibited a face-centred cubic structure with a strong (110) texture as their substrates. The surface images obtained by scanning electron microscopy disclosed that all films have smooth surfaces. Magnetoresistance measurements were carried out at room temperature with magnetic fields up to 12 kOe. All samples exhibited giant magnetoresistance (GMR) and the maximum GMR value of 5% was obtained in the multilayer grown from the electrolyte containing 0.0036 M Fe ion concentration. The GMR magnitude changed depending on the film contents arising from the variation of the Fe ion concentration in the electrolyte. The magnetic properties studied with the vibrating sample magnetometer showed that the saturation magnetisation changed, and the coercivities decreased with varying Fe ion concentration in the electrolyte. The changes observed in the properties were ascribed to the variations observed in the film composition caused by the Fe ion concentration of the electrolyte.

Kuru, Hilal; Kockar, Hakan; Alper, Mursel

2015-01-01

225

Temperature effect on the local order of liquid Ni, Ag, and Pb: A molecular dynamics study  

NASA Astrophysics Data System (ADS)

In this work we calculate structural properties as a function of temperature for liquid Ni, Ag, and Pb using constant-energy molecular dynamics. The metallic interaction is mimicked by a tight-binding n-body potential, based on the second-moment approximation of the density of states. The inherent structures of the liquid state are analyzed through a common-neighbor analysis to extract the microstructural order as a function of temperature. For each liquid metal, our simulations show that the icosahedral order has a significant presence, on the order of 65%, and that the crystalline order is about 25% in the range of temperatures studied here. The icosahedral order remains constant with temperature for the three liquid metals, but changes in the type of crystalline order occur for Ag and Pb at 1500 and 900 K, respectively.

Urrutia-Bauelos, Efran; Posada-Amarillas, Alvaro; Garzn, Ignacio L.

2002-10-01

226

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

Microsoft Academic Search

Sorption of Ni and Cu by Chlorella vulgaris showed the second-order rate kinetics. Change in biomass concentration altered the kinetic parameters of sorption. When biomass concentration was increased from 5 to 1000 mg l?1, the initial rates of sorption of Ni and Cu were reduced by about five- and three-times, respectively. The metal sorption capacity of the test alga was

Surya Kant Mehta; Jai Prakash Gaur

2001-01-01

227

Improvement of the fretting damage resistance of Ti811 alloy by Cu\\/Ni multilayer films  

Microsoft Academic Search

The Cu\\/Ni multilayer films were prepared on the titanium alloy surface by ion-assisted magnetron sputtering deposition (IAD) technique. The Cu\\/Ni multilayer films could significantly improve the resistance of fretting wear and fretting fatigue (FF) of Ti-811 alloy at room temperature. The FF resistance of the titanium alloy substrate did not increase monotonically with increase in the modulation period thickness of

Xiaohua Zhang; Daoxin Liu; Guohua Liu; Zhenya Wang; Bin Tang

228

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

229

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

230

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

E-print Network

1 Temperature Dependence Of Core Loss In Cobalt Substituted Ni-Zn-Cu Ferrites A. Lucas 1,2 , R dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead to a compensation of the magneto- crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on the cobalt

Paris-Sud XI, Université de

231

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

232

Thermal relaxation effects observed in the giant magnetoresistance of NiFe/Ag degraded multilayers (abstract)  

NASA Astrophysics Data System (ADS)

NiFe/Ag degraded multilayers have potential for use in sensors and data storage. The magnetoresistance (MR) observed in these materials, after thay have been optimized by postdeposition annealing, has been found to have a good field sensitivity. It is believed that the size and saturation field of the giant magnetoresistance (GMR) is a function of the size of magnetostatic interactions that occur between the magnetic layers in the system. In order to improve the field sensitivity of the GMR in these materials, the volume of the NiFe aligned antiparallel by magnetostatic coupling will have to be maximized. We have investigated time-dependent thermal relaxation effects in the GMR of these systems in an attempt to determine both the nature of the coupling and the distribution of blocking sizes. The multilayers were deposited onto glass substrates at the system ambient temperature, by dc sputtering in a sputtering pressure of 7.5 mTorr of Ar. Fifteen bilayer repeat multilayers were prepared by rotating the substrate over the NiFe and Ag targets, alternately. Both NiFe and Ta underlayers have been investigated. The postdeposition annealing strategy used was 315 C for 10 min in a vacuum of better than 10-5 Torr. We have investigated the time dependence of the GMR using a linear four point probe and measurements have been made over a temperature range 10-450 K. The blocking temperature, and the particle/platelet size distribution, of the entities that cause the GMR can be determined from these measurements. In addition, we have found a number of interesting temperature-dependent MR effects, and it is seen that the blocking temperature is below 350 K in all cases (Fig. 1).

Wiggins, J.; Gago-Sandoval, P. A.; Watson, M. L.

1997-04-01

233

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

NASA Astrophysics Data System (ADS)

La2AgxCuO4 (x=0, 0.01, 0.02, 0.05, 0.10, 0.15) polycrystalline ceramics have been synthesized using a solid state reaction method, and their thermoelectric properties measured in the temperature range 10-380 K. The resistivities and Seebeck coefficients of these samples tend to decrease, while the thermal conductivities first decrease then increase as the Ag dose rises. Consequently, the dimensionless thermoelectric figure of merit, ZT, first increases then decreases with increasing Ag content. The maximum ZT values for each sample appear at about 300 K and shift towards lower temperatures with the addition of Ag. At 308 K, the La2CuO4 ceramic with the addition of 5% molar Ag gave the maximum ZT value, 0.018, obtained in this work. This is nearly twice as large as that for pure La2CuO4.

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

2015-01-01

234

Effect of Gold Content on the Reliability of SnAgCu Solder Joints  

Microsoft Academic Search

Electroplated Ni\\/Au over Cu is a popular metal- lization for printed circuit board finish as well as for component leads, especially wire-bondable high-frequency packages, where the gold thickness requirement for wire bonding is high. The general understanding is that less than 3 wt% of Au is acceptable in SnPb solder joints. However, little is known about the effect of Au

Jianbiao Pan; Julie Silk; Mike Powers; Patrick Hyland

2011-01-01

235

A comparative study of transition metal doped tubular gold cages:MatAu24(M=Au,Cu,Ag)  

NASA Astrophysics Data System (ADS)

A comparative study of endohedral doping of Au24 tubular cage with transition metal M (M= Au, Cu, Ag) has been done using two different methodologies-the density functional theory (DFT) and semi empirical approach using the Gupta potential (GP). The GP predicts Au@Au24 to be the most stable while DFT predicts Cu@Au24 to be the most stable; the Au@Au24 and Ag@Au24 are found to be nearly isoenergetic. The Doping energy and HOMO-LUMO gap from DFT indicate that Cu@Au24-I is chemically most inert.

Sumali, Priyanka, Dharamvir, Keya

2013-02-01

236

Glass-forming ability and atomic-level structure of the ternary Ag-Ni-Zr metallic glasses studied by molecular dynamics simulations  

NASA Astrophysics Data System (ADS)

Based on the recently proposed long-range empirical potential formulism, an n-body potential is constructed for the Ag-Ni-Zr ternary metal system and verified to be realistic by reproducing some important properties of the pure metals as well as of some equilibrium compounds of the system. Applied the constructed Ag-Ni-Zr potential, molecular dynamics simulations and Voronoi tessellations are then carried out to study the effect of alloying composition on glass-forming ability and atomic-level structure of the ternary Ag-Ni-Zr metallic glasses. For the Ag50-x/2 NixZr50-x/2 alloys, with increasing Ni concentration, distortion of the crystalline structure becomes significant, implying a disordering process going on, and at the same time, the number of {0, 0, 12, 0} icosahedrons increases remarkably and the {0, 0, 12, 0} icosahedrons are almost Ni-centered. When the Ni concentration is increased up to 20 atom %, the ternary Ag-Ni-Zr solid solution collapses and turns into a disordered state, suggesting that increasing the Ni concentration could enhance the glass-forming ability of the system. For the Ag30Ni40Zr30 ternary metallic glass, it is found that most of the polyhedrons with coordinate number (CN < 13) are Ni-centered, whereas most of polyhedrons with CN > 14 are either Ag or Zr centered.

Ye, Dai; Jiahao, Li; Baixin, Liu

2011-03-01

237

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

NASA Astrophysics Data System (ADS)

Ag-Cu alloy catalysts for ethylene epoxidation have been shown to yield higher selectivity towards ethylene oxide compared to pure Ag, the unique catalyst employed in the industrial process. Previous studies showed that under oxidizing conditions Cu forms oxide layers on top of Ag. Using first-principles atomistic simulations based on density functional theory, we investigate the reaction mechanism on the thin oxide layer structures and establish the reasons for the improved selectivity. We extend the range of applicability of the selectivity descriptor proposed by Kokalj et al. [J. Catal. 254, 304 (2008)], 10.1016/j.jcat.2008.01.008, based on binding energies of reactants, intermediates, and products, by refitting its parameters so as to include thin oxide layer catalysts. We show that the selectivity is mainly controlled by the relative strength of the metal-carbon vs. metal-oxygen bonds, while the height of the reaction barriers mostly depend on the binding energy of the common oxametallacycle intermediate.

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

2013-05-01

238

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

NASA Astrophysics Data System (ADS)

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

Piyawit, Waraporn

239

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

240

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

PubMed

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

Tharmaraj, Vairaperumal; Yang, Jyisy

2014-12-01

241

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

242

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

243

Jumps and concerted moves in Cu, Ag, and Au(110) adatom self-diffusion  

NASA Astrophysics Data System (ADS)

We present a molecular-dynamics simulation of self-diffusion on the (110) surfaces of Cu, Ag, and Au. The metals are modeled by semiempirical potentials developed in the framework of the second-moment approximation to the tight-binding model. The energy barriers for the relevant diffusion processes are calculated by quenched molecular dynamics and compared with the available data in literature, obtaining a good agreement. The occurrence of long jumps is investigated in detail, showing that the three metals behave quite differently with this respect: long jumps are practically absent in Au and frequent in Cu. The effect of the specific features of the potential-energy surface and of the energy dissipation to the substrate on the probability of long jumps is investigated. The Arrhenius behavior of the jump rate is discussed, and deviations are found at high temperatures. Concerning correlated jump-exchange processes and double exchanges, we find that they are common in Cu even at rather low temperatures, whereas they are never observed in Au, Ag showing an intermediate behavior.

Montalenti, F.; Ferrando, R.

1999-02-01

244

Microstructure evolution of Al12SiCuNiMg alloy under high temperature low cycle fatigue  

E-print Network

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

Volinsky, Alex A.

245

Correlations Between Os Isotopic Composition and Trace Element Abundance in Chinese Cu-Ni Deposit Sulfides  

NASA Astrophysics Data System (ADS)

We have determined the Os isotopic composition (ID-MC-ICPMS) and trace element abundances (LA-ICPMS) in sulfide minerals from 4 Cu-Ni deposits in southern China. The samples separate into 2 groups based on Re/Os ratio. The high Re/Os deposits yield a 278 35 Ma isochron (MSWD = 3.7) and an initial ? Os of 255. The low Re/Os deposits define a 278 20 Ma isochron (MSWD = 15), and an initial ? Os of 49, showing that mineralization was contemporaneous, but the amount of crustal contamination and/or R-factor in the two groups was different. These differences and are also reflected in sulfide mineral trace element variations. Laser ablation shows that Re, Os, and Ir are in solid solution with pentlandite and pyrrhotite and Au and Pd are enriched in pentlandite over pyrrhotite. Pt was rarely observed above detection, but when present occurs as isolated Pt peaks. For the high Re/Os whole rock samples the average sulfide Re and Os concentration agree with the whole rock data, but in the low Re/Os whole rock samples the sulfide Re and Os are higher, suggesting that chalcopyrite with its Re/Os of >5 is an important mass balance component. Trace element modeling is complicated by the fact that Cu, Zn, Ga, As, Cd, Te, Ag, Au, Pb and Bi while occurring in solid solution with pentlandite and pyrrhotite are often present as sulfide mineral inclusions. Examination of ablation signals shows anti-correlation between some elements (e.g. Te and Pb) and that numerous off-set peaks also occur within single ablations. None-the-less, Ag tends to be enriched in pentlandite over pyrrhotite in the low Re/Os group and evenly distributed between the sulfides in the high Re/Os group. Cd, Pb and Bi are enriched in high Re/Os group sulfides suggesting that while the difference in initial ? Os can be modeled as variation in R-factor, the degree of radiogenicness of the initial ? Os in mafic-ultramafic ore deposits is ultimately controlled by the degree of crustal contamination.

Graham, S.; Griffin, W.; Barnes, S.; Begg, G.

2004-05-01

246

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

SciTech Connect

The structural and optical properties of pentenary alloy (Ag,Cu)(In,Ga)Se{sub 2} polycrystalline thin films were characterized over the entire compositional range at a fixed (Cu?+?Ag)/(In?+?Ga) ratio. Films deposited at 550?C on bare and molybdenum coated soda-lime glass by elemental co-evaporation in a single-stage process with constant incident fluxes exhibit single phase chalcopyrite structure, corresponding to 122 spacegroup (I-42d) over the entire compositional space. Unit cell refinement of the diffraction patterns show that increasing Ag substitution for Cu, the refined a{sub o} lattice constant, (Ag,Cu)-Se bond length, and anion displacement increase in accordance with the theoretical model proposed by Jaffe, Wei, and Zunger. However, the refined c{sub o} lattice constant and (In,Ga)-Se bond length deviated from theoretical expectations for films with mid-range Ag and Ga compositions and are attributed to influences from crystallographic bond chain ordering or cation electronegativity. The optical band gap, derived from transmission and reflection measurements, widened with increasing Ag and Ga content, due to influences from anion displacement and cation electronegativity, as expected from theoretical considerations for pseudo-binary chalcopyrite compounds.

Boyle, J. H.; Shafarman, W. N.; Birkmire, R. W. [Institute of Energy Conversion, University of Delaware, 451 Wyoming Road, Newark, Delaware 19716 (United States); Department of Materials Science and Engineering, University of Delaware, 201 DuPont Hall, Newark, Delaware 19716 (United States); McCandless, B. E. [Institute of Energy Conversion, University of Delaware, 451 Wyoming Road, Newark, Delaware 19716 (United States)

2014-06-14

247

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

SciTech Connect

Rotationally anisotropic surface second-harmonic generation (SHG) has been measured from a clean, well-ordered Cu(110) single-crystal surface as a function of both surface temperature and Ag coverage. For the clean Cu(110) surface, the temperature dependence of the SH response at a fixed azimuthal angle can be correlated with a surface phase transformation. A large decrease in the rotationally anisotropic SH response as a function of surface temperature can be related to changes in the surface disorder. The results are compared with other studies of Cu(110) surface structure using both x-ray and He-atom scattering. The rotationally anisotropic SH response has also been measured as a function of Ag coverage with the Cu(110) surface temperature fixed at 300 K. The results closely follow the formation of an ordered Ag(111)-like overlayer, the nucleation of three-dimensional Ag nanoclusters (<20 {angstrom} thick) that enhance the anisotropic SH response, and the subsequent growth of a {approximately}10 monolayer thick Ag film. Variations in the rotationally anisotropic SH response as a function of Ag coverage are used to separate the resonant surface electronic contributions to the nonlinear susceptibility of the interface. 22 refs., 4 figs.

Hoffbauer, M.A.; McVeigh, V.J.

1990-01-01

248

Density functional calculation of the electronic absorption spectrum of Cu+ and Ag+ aqua ions.  

PubMed

The UV absorption of aqueous Cu+ and Ag+ has been studied using Time Dependent Density Functional Theory (TDDFT) response techniques. The TDDFT electronic spectrum was computed from finite temperature dynamical trajectories in solution generated using the Density Functional Theory (DFT) based Ab Initio Molecular Dynamics (AIMD) method. The absorption of the two ions is shown to arise from similar excitation mechanisms, namely transitions from d orbitals localized on the metal center to a rather delocalized state originating from hybridization of the metal s orbital to the conduction band edge of the solvent. The ions differ in the way the spectral profile builds up as a consequence of solvent thermal motion. The Cu+ absorption is widely modulated, both in transition energies and intensities by fluctuations in the coordination environment which is characterized by the formation of strong coordination bonds to two water molecules in an approximately linear geometry. Though, on average, absorption intensities are typical of symmetry forbidden transitions of metal ions in the solid state, occasionally very short (<100 fs) bursts in intensity are observed, associated with anomalous Cu-H interactions. Absorption by the Ag+ complex is in comparison relatively stable in time, and can be interpreted in terms of the energy splitting of the metal 4d manifold in an average crystal field corresponding to a fourfold coordination in a distorted tetrahedral arrangement. Whereas the spectral profile of the Ag+ aqua ion is in good agreement with experiment, the overall position of the band is underestimated by 2 eV in the BLYP approximation to DFT. The discrepancy with experiment is reduced to 1.3 eV when a hybrid functional (PBE0) is used. The remaining inaccuracy of TDDFT in this situation is related to the delocalized character of the target state in d-->s transitions. PMID:15634150

Bernasconi, Leonardo; Blumberger, Jochen; Sprik, Michiel; Vuilleumier, Rodolphe

2004-12-15

249

Magnetic behavior of half-Heusler alloy Cu x Ni 1? x MnSb  

Microsoft Academic Search

We have investigated the effects on the magnetic properties of NiMnSb alloys with the substitution of Cu for Ni. The half-Heusler type alloys, CuxNi1?xMnSb compounds, are fabricated by the arc-melting method and are subsequently annealed at a temperature of 1050K for 24h. It was found that at a temperature of 4K and field of 10kOe for CuxNi1?xMnSb samples, the formula

S. K. Ren; W. Q. Zou; J. Gao; X. L. Jiang; F. M. Zhang; Y. W. Du

2005-01-01

250

Electrical Characteristics of A1/CNT/NiPc/PEPC/Ag Surface-Type Cell  

NASA Astrophysics Data System (ADS)

The blend of nickel phthalocyanine (NiPc) (2 wt. %) poly-N-epoxypropylcarbazole (PEPC), (1 wt. %) and carbon nano-tube (CNT) powder (2 wt. %) in benzole is deposited by drop-casting on glass substrates with pre-deposited metallic electrodes to fabricate Ag/CNT/NiPc/PEPC/A1 surface type cell. It is assumed that the high nonlinearity of the I V characteristics is related to deep traps in the nano-scale depletion region in NiPc that is observed experimentally. The values of ideality factor and barrier height are determined from the I V curve and they are found to be 8.4 and 1.05eV, respectively. The values of mobility and conductivity are calculated to be 7.94 10-8 cm/Vs and 3.5 10-6 ?-1 cm-1. The values of ideality factor and series resistance are also calculated by using Cheung's functions, which are in good agreement with the values calculated from the I V curve.

Mutabar, Shah; Kh., S. Karimov; Zubair, Ahmad; H. Sayyad, M.

2010-10-01

251

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

252

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

253

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

254

First-principles study of methane dehydrogenation on a bimetallic Cu/Ni(111) surface  

NASA Astrophysics Data System (ADS)

We present density-functional theory calculations of the dehydrogenation of methane and CHx (x=1-3) on a Cu/Ni(111) surface, where Cu atoms are substituted on the Ni surface at a coverage of 1/4 monolayer. As compared to the results on other metal surfaces, including Ni(111), a similar activation mechanism with different energetics is found for the successive dehydrogenation of CH4 on the Cu/Ni(111) surface. In particular, the activation energy barrier (Eact) for CH?C+H is found to be 1.8 times larger than that on Ni(111), while Eact for CH4?CH3+H is 1.3 times larger. Considering the proven beneficial effect of Cu observed in the experimental systems, our findings reveal that the relative Eact in the successive dehydrogenation of CH4 plays a key role in impeding carbon formation during the industrial steam reforming of methane. Our calculations also indicate that previous scaling relationships of the adsorption energy (Eads) for CHx (x=1-3) and carbon on pure metals also hold for several Ni(111)-based alloy systems.

An, Wei; Zeng, X. C.; Turner, C. Heath

2009-11-01

255

First-principles study of methane dehydrogenation on a bimetallic Cu/Ni(111) surface.  

PubMed

We present density-functional theory calculations of the dehydrogenation of methane and CH(x) (x=1-3) on a Cu/Ni(111) surface, where Cu atoms are substituted on the Ni surface at a coverage of 14 monolayer. As compared to the results on other metal surfaces, including Ni(111), a similar activation mechanism with different energetics is found for the successive dehydrogenation of CH(4) on the Cu/Ni(111) surface. In particular, the activation energy barrier (E(act)) for CH-->C+H is found to be 1.8 times larger than that on Ni(111), while E(act) for CH(4)-->CH(3)+H is 1.3 times larger. Considering the proven beneficial effect of Cu observed in the experimental systems, our findings reveal that the relative E(act) in the successive dehydrogenation of CH(4) plays a key role in impeding carbon formation during the industrial steam reforming of methane. Our calculations also indicate that previous scaling relationships of the adsorption energy (E(ads)) for CH(x) (x=1-3) and carbon on pure metals also hold for several Ni(111)-based alloy systems. PMID:19895030

An, Wei; Zeng, X C; Turner, C Heath

2009-11-01

256

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

257

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

PubMed

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

Yao, Yunxi; Goodman, D Wayne

2014-02-28

258

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

259

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

260

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

261

A first-principles study of vibrational modes in Cu 2 O and Ag 2 O crystals  

NASA Astrophysics Data System (ADS)

A first-principles investigation of cuprite crystals (Cu 2O and Ag 2O) has been performed. For Cu 2O, the calculated frequencies at the ? point of the Brillouin zone are in very good agreement with the experimental frequencies. For Ag 2O, the presence of Eu and F2u vibrational modes with negative frequencies indicates a low temperature phase transition, in agreement with recent high resolution X-ray and neutron diffraction measurements. The energy scanning along these two modes shows a double-well potential, within which only the Ag atoms vibrate. As a result, the origin of the phase transition can be attributed to displacive disorder of the Ag atoms.

Sanson, Andrea

2011-10-01

262

Kinetic electron emission yield induced by H + and He 2+ ions versus stopping power for Al, Cu, Ag and Au  

NASA Astrophysics Data System (ADS)

For H + and He 2+ ions impinging on Al, Cu, Ag and Au targets we measured simultaneously the yield, ?, of emitted electrons and the electronic energy loss, Se, in the energy range 0.5 to 4.8 MeV. The targets were prepared under high-vacuum conditions before they were transferred to an ultra-high-vacuum chamber without breaking the vacuum. The targets were sputter cleaned and their composition was examined by Auger electron spectrometry. The values of ? were obtained by current integration and Se was determined from the energy width of Rutherford backscattering spectra. For H + ions impinging on Cu, Ag or Au and He 2+ on Al and Cu, the expected proportionality between ? and Se was found within the experimental errors of 2%. For H + ions on Al and He 2+ ions on Ag and Au targets, significant deviations were observed.

Benka, O.; Steinbauer, E.; Bauer, P.

1994-05-01

263

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

264

Magnetic aftereffect in textured Ni/Cu compositionally modulated alloys (abstract)  

NASA Astrophysics Data System (ADS)

The existence of a magnetic aftereffect (``magnetic viscosity'') in textured Ni/Cu multilayered alloys was established1 using a vibrating sample magnetometer at room temperature and at 86 K. It was shown that the effect is strongly dependent on the step field, H2 (i.e., the value the field is reduced to after the magnetic moment has been aligned in high field), and exhibits a maximum relaxation rate for values of H2 around the reverse coercive field, Hc. Aftereffect behavior of this type has been observed in other materials, though most often for systems composed of superparamagnetic particles, where the relaxation freezes out at low temperatures. In contrast, the relaxation is enhanced at low temperature in the present situation. Several questions remain open from this earlier work. Among these are: is the effect a property of a thin Ni film or is it attributable to the compositional modulation of the alloy?; what is the exact form of the time decay and what is the mechanism that causes this effect? In order to resolve some of these issues the magnetic aftereffect has been measured in more detail and for longer periods of time at both temperatures (room and 86 K) in a new set of [111]-textured, layered Cu/Ni alloys of varying thicknesses. The slab thickness of the Ni, dNi, was varied between 6 and 30 , and the ratio dNi/(dNi+dCu) between 0.1 and 0.8.

Atzmony, U.; Swartzendruber, L. J.; Bennett, L. H.; Lashmore, D.; Watson, R. E.; Rubinstein, M.; Lubitz, P.

1988-04-01

265

Electronic structure and x-ray magnetic circular dichroism in YbAgCu4 and YbInCu4  

SciTech Connect

X-ray absorption and magnetic circular dichroism spectra at the L3 edge of Yb have been studied theoretically in the mixed-valent compounds YbAgCu4 and YbInCu4 using the fully relativistic Dirac linear muffin-tin orbital band structure method. The effect of the spin-orbit (SO) interaction and Coulomb repulsion U on the electronic structure of YbAgCu4 and YbInCu4 is examined in the frame of the local spin-density approximation (LSDA)+SO+U method. The core-hole effect in the final states as well as the effect of the electric quadrupole E2 and magnetic dipole M1 transitions have been investigated. The calculated results are compared with available experimental data.

Antonov, V. N.; Bekenov, L. V.; Antropov, V. P.

2014-04-01

266

Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy  

NASA Astrophysics Data System (ADS)

We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 C, 700 C, and 800 C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 ?m could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

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

2014-10-01

267

Effects of bump size on deformation and fracture behavior of Sn3.0Ag0.5Cu\\/Cu solder joints during shear testing  

Microsoft Academic Search

To elaborate deformation and fracture behavior of Sn3.0Ag0.5Cu\\/Cu solder joint, dynamic shear testing was designed and performed on as-reflowed and aged solder joints which contained limited numbers of grains. Polarized light microscopy (PLM) and electron backscatter diffraction (EBSD) were used to reveal the grain morphology and the grain distribution. Scanning electron Microscopy (SEM) was applied to observe the influences of

Yanhong Tian; Chunjin Hang; Chunqing Wang; Shihua Yang; Pengrong Lin

2011-01-01

268

Structural and Dynamical Properties in Liquid Ni and Ag by Computer Simulation  

NASA Astrophysics Data System (ADS)

We studied the temperature dependence of the structural and dynamical properties for liquid nickel and silver by modeling the interatomic interaction through a tight-binding n-body potential in the second-moment approximation (TB-SMA). A common-neighbor analysis was performed to explore the microstructural changes with temperature in Ni and Ag in the liquid state in terms of their inherent structures (IS). A tendency to the formation of more symmetric IS characteristic of the BCC crystalline and icosahedral order is observed as the temperature is raised. At the same time, the FCC and HCP crystalline order is reduced while the BCC-type order increases. The simulated diffusion coefficients are in reasonable agreement with the available experimental information and with other theoretical results. The simple liquid behavior is shown by an Arrhenius plot for both nickel and silver.

Urrutia-Bauelos, Efran; Posada-Amarillas, Alvaro

269

The origin of ferromagnetic ordering in PrNi 3.9Cu 1.1  

NASA Astrophysics Data System (ADS)

Although both PrNi 5 and PrCu 5 are non-magnetic, PrNi 5- xCu x alloys for 0.9? x?2.6 were recently discovered to order with Curie temperature T C?3.6 K. In order to understand the mechanism of these ferromagnetic orderings, we have carried out mean-field model calculations and obtained crystal-field parameters and anisotropic Heisenberg coupling constants for x=1.1. The effects of quadrupolar coupling and magneto-elastic interactions were also taken into account in order to better fit the magnetization along the hard [0 0 1] direction. Based on our theoretical studies, we conclude that Cu substitution for Ni strongly changes the crystal field acting on the 4f electrons, and considerably enhances the Pr-Pr exchange interaction. The onset of ferromagnetism below TC is therefore attributed to an interplay between the exchange interactions and crystalline electric field effects.

Liu, Z.-S.; Park, J.-G.

2002-09-01

270

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

PubMed

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

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

2014-12-21

271

Profiling transcriptomic response of Enchytraeus albidus to Cu and Ni: comparison with Cd and Zn.  

PubMed

Metals are among the most common contaminants in soils in Europe. Although their effects are relatively well known regarding survival and reproduction to soil invertebrates, their mode of action is poorly understood. Enchytraeus albidus is a model organism in ecotoxicology and with the development of a gene library for this species, transcriptomic studies are now possible. The main aim of this study is to understand the Cu and Ni mechanisms of response in E.albidus, in comparison with Cd and Zn (already studied). E.albidus were exposed to Cu and Ni for 4 days to the reproduction effect concentrations EC50 and EC90. Results indicate that Cu and Ni have similar mechanisms of toxicity. When comparing four elements (hierarchical clustering) it was possible to observe a clear separation of Cd from all other metals. This separation correlates with the available information from other species regarding the toxicokinetics of the tested elements. PMID:24361568

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

2014-03-01

272

Investigations on the Spin Hamiltonian Parameters for Cu2+ in NaCl and AgCl  

NASA Astrophysics Data System (ADS)

The spin Hamiltonian parameters (g factors and hyperfine structure constants) for Cu2+ in NaCl and AgCl are investigated theoretically for the case of the 3d 9 ion in tetragonally elongated octahedra using high-order perturbation formulas for these parameters. Due to the Jahn-Teller effect, the impurity Cu2+ centers are found to experience relative elongations along the four-fold axis of about 0.15 and 0.08 in NaCl and AgCl, respectively. The calculated spin Hamiltonian parameters are in good agreement with the experimental data. The local structures and EPR spectra of the systems are discussed.

Cheng, Y.-K.; Wu, S.-Y.; Ding, C.-C.; Kuang, M.-Q.

2015-01-01

273

Analysis of the reaction between 60Sn40Pb solder with a Pd-Pt-Ag-Cu-Au alloy  

Microsoft Academic Search

We present the results of a metallurgical study of a 35Pd-30Ag-14Cu-10Au10Pt-1Zn (wt. %) alloy soldered with 60Sn-40Pb for\\u000a glass-to-metal sealing applications. Mechanical tests were performed on the Pd-Ag-Cu-Au-Pt-Zn alloy and showed that it retains\\u000a ductility, with an increase in strength, after heat treatments that simulate the glass-to-metal sealing temperature profile.\\u000a Wetting characteristics of the alloy with 60Sn-40Pb solder were found

D. R. Frear; J. R. Michael; P. F. Hlava

1993-01-01

274

Substrate temperature dependence on the optical properties of Cu and Ag thin films  

NASA Astrophysics Data System (ADS)

Copper (260 nm) and Ag (1000 nm) films deposited on glass substrates, at different substrate temperatures. Their optical properties were measured by ellipsometry (single wavelength of 589.3 nm) and spectrophotometry in the spectral range of 200 2600 nm. Kramers Kronig method was used for the analysis of the reflectivity curves of Cu and Ag films to obtain the optical constants of the films, while ellipsometry measurements was carried out as an independent method. The influence of substrate temperature on the microstructure of thin metallic films [Structure Zone Model (SZM)] is well established [Movchan and Demchishin, Phys. Met. Metall. 28, 83 (1969); Thornton, J. Vac. Sci. Technol. 12, 830 (1975); Savaloni and Bagheri Najmi, Vacuum 66, 49 (2002); Savaloni and Player, Vacuum 46, 167 (1995); Savaloni et al., Vacuum 43, 965 (1992)]. The Effective Medium Approximation (EMA) analysis was used to establish the relationship between the SZM and EMA predictions. Good agreements between SZM as a function of substrate temperature and the values of volume fraction of voids obtained from EMA analysis, is achieved; by increasing the substrate temperature the separation of the metallic grains decreases, hence, the volume fraction of voids decreases and denser films formed. The predictions of the Drude free-electron theory are compared with experimental results for dielectric functions of Cu and Ag films of different substrate temperature. The real part of the dielectric constant is decreased with increasing the substrate temperature, while the imaginary part of the dielectric constant increased with temperature for both materials over the whole energy range measured, including intraband and interband regions. The increase of the imaginary part in the interband region suggests a temperature and frequency dependence of the relaxation time in the Drude model, namely ? -1?ft( ? right)=? _0-1 +? ? ^2.

Savaloni, H.; Khakpour, Ahmad Reza

2005-08-01

275

Black Pad Susceptibility of the Electroless Ni Films on the Cu UBM  

NASA Astrophysics Data System (ADS)

The occurrence of black pad in the electroless Ni film during the immersion gold process is related to the surface morphology of the Ni(P) film. A nonuniform distribution of the nodule size and curvature is the crucial factor. Large nodules with small surface curvatures had higher P concentration and did not corrode, while small nodules with large surface curvatures had lower P concentration and corroded. Experiments using different types of Cu substrates suggest that the Ni(P) film black pad susceptibility increased with the defect density and/or the residual stress in the underlying substrate. Annealing the Cu substrate before the electroless Ni plating greatly reduced the black pad formation.

Kim, J. H.; Yu, Jin

2014-11-01

276

Electronic structure modifications in Cu doped Ni2MnGa  

NASA Astrophysics Data System (ADS)

Ni2MnGa Heusler alloy is a multifunctional ferromagnetic alloy that exhibits various interesting properties. The compounds typically exhibit a high temperature magnetic and a low temperature martensitic transition. Stoichiometry changes or elemental substitution makes it possible to merge the two transitions to a unique magnetostructural one. We have used resonant inelastic x-ray scattering to study the effects of d-d interactions and charge transfer effects in 25% Cu doped Ni2MnGa. We find distinct charge transfer effects in the Ni absorption and inelastic x-ray spectrum that are significantly modified by Cu doping. Mn on the other hand shows d-d interaction effects but no charge transfer. Multiplet calculations have been performed and will be compared to the experimental data. These results provide an insight into the origin of multifunctional properties of Ni based Heusler alloys. Work at LBNL is supported by U.S DOE.

Roy, Sujoy; Qiao, R.; Glans, P.-A.; Pathak, A.; Dubenko, I. S.; Ali, N.; Blackburn, E.; Yang, W.

2011-03-01

277

Ag Doping Effects of GdBa2Cu3O7-? Films by Low Fluorine MOD Method  

NASA Astrophysics Data System (ADS)

A series of Ag-doped GdBaCuO superconducting films were prepared by low fluorine MOD process on buffered Hastelloy substrates. The effects of Ag doping on the microstructures and superconducting properties of GdBCO thin films were investigated. It was found that an optimum addition of about 5 mol % Ag lead to better c-axis orientation and surface microstructure of the resultant films. Meanwhile, the pyrolysis process shortened and the superconducting performance is improved with a wide available window.

Sun, M. J.; Qiu, W. B.; Liu, Z. Y.; Bai, C. Y.; Guo, Y. Q.; Cai, C. B.

2014-05-01

278

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

SciTech Connect

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

Li, Jian-Chang, E-mail: jcli@mail.neu.edu.cn; Hou, Xue-Yan; Cao, Qing [Vacuum and Fluid Engineering Research Center, Northeastern University, Shenyang 110819 (China)

2014-04-28

279

Layer thickness dependence of CPP giant magnetoresistance in individual CoNi/Cu multilayer nanowires grown by electrodeposition  

E-print Network

magnetoresistance GMR effect of CoNi/Cu nanowires grown by electrodeposition using an array of parallel throughLayer thickness dependence of CPP giant magnetoresistance in individual CoNi/Cu multilayer. INTRODUCTION Giant magnetoresistance GMR effect observed in mag- netic multilayer films consisting

Wang, Gwo-Ching

280

Flame Synthesis of Nanosized Cu-Ce-O, Ni-Ce-O, and Fe-Ce-O Catalysts for the  

E-print Network

with their oxide counterparts, indicating the doping materials form separate oxide phases (CuO, Fe2O3, NiO) within and transition-metal-doped ceria materials, which include coprecipitation (19-21), hydro- thermal (22 on the surface of the particles. The presence and surface enrichment of the transition-metal oxides (CuO, Ni

Frenkel, Anatoly

281

Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic glasses  

E-print Network

Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic June 2010 The corrosion properties of two Zr-based bulk metallic glass, Zr41Ti14Cu12Ni10Be23 LM1 and Zr potential, LM1b showed superior corrosion resistance to LM1. Under identical sample preparation and testing

Zheng, Yufeng

282

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

283

The Partition Coefficients of Components in Cu-Ni-Mn Alloys  

NASA Astrophysics Data System (ADS)

Dendritic microsegregation was calculated using a Scheil-based solidification model for three alloys: 50.1 pct Cu-25.8 pct Ni-24.1 pct Mn; 42.4 pct Cu-25.4 pct Ni-32.2 pct Mn; 34.3 pct Cu-26.2 pct Ni-39.5 pct Mn. The dendritic microsegregation in these alloys was investigated using energy-dispersive X-ray analysis. It was shown by calculation and experimental methods that in all three alloys, the partition coefficient ( k) of manganese passes through the value k Mn = 1. This is shown by the presence of two maxima on the manganese concentration profile in the dendritic cell. It was calculated that the copper partition coefficient in these alloys should also pass through the value k Cu = 1; however, this has not been confirmed experimentally. The possible reason for this may be because of the inaccuracies in the phase diagram of the Cu-Ni-Mn system that was used and also in the difference of the copper and manganese diffusion coefficients in the alloy.

Bazhenov, V. E.; Pikunov, M. V.; Cheverikin, V. V.

2015-02-01

284

A Series of M(II)Cu(II)3 Stars (M = Mn, Ni, Cu, Zn) Exhibiting Unusual Magnetic Properties.  

PubMed

The work in this report describes the syntheses, electrospray ionization mass spectromtery, structures, and experimental and density functional theoretical (DFT) magnetic properties of four tetrametallic stars of composition [M(II)(Cu(II)L)3](ClO4)2 (1, M = Mn; 2, M = Ni; 3, M = Cu; 4, M = Zn) derived from a single-compartment Schiff base ligand, N,N'-bis(salicylidene)-1,4-butanediamine (H2L), which is the [2 + 1] condensation product of salicylaldehyde and 1,4-diaminobutane. The central metal ion (Mn(II), Ni(II), Cu(II), or Zn(II)) is linked with two ?2-phenoxo bridges of each of the three [Cu(II)L] moieties, and thus the central metal ion is encapsulated in between three [Cu(II)L] units. The title compounds are rare or sole examples of stars having these metal-ion combinations. In the cases of 1, 3, and 4, the four metal ions form a centered isosceles triangle, while the four metal ions in 2 form a centered equilateral triangle. Both the variable-temperature magnetic susceptibility and variable-field magnetization (at 2-10 K) of 1-3 have been measured and simulated contemporaneously. While the Mn(II)Cu(II)3 compound 1 exhibits ferromagnetic interaction with J = 1.02 cm(-1), the Ni(II)Cu(II)3 compound 2 and Cu(II)Cu(II)3 compound 3 exhibit antiferromagnetic interaction with J = -3.53 and -35.5 cm(-1), respectively. Variable-temperature magnetic susceptibility data of the Zn(II)Cu(II)3 compound 4 indicate very weak antiferromagnetic interaction of -1.4 cm(-1), as expected. On the basis of known correlations, the magnetic properties of 1-3 are unusual; it seems that ferromagnetic interaction in 1 and weak/moderate antiferromagnetic interaction in 2 and 3 are possibly related to the distorted coordination environment of the peripheral copper(II) centers (intermediate between square-planar and tetrahedral). DFT calculations have been done to elucidate the magnetic properties. The DFT-computed J values are quantitatively (for 1) or qualitatively (for 2 and 3) matched well with the experimental values. Spin densities and magnetic orbitals (natural bond orbitals) correspond well with the trend of observed/computed magnetic exchange interactions. PMID:25496240

Mondal, Suraj; Mandal, Shuvankar; Carrella, Luca; Jana, Arpita; Fleck, Michel; Khn, Andreas; Rentschler, Eva; Mohanta, Sasankasekhar

2015-01-01

285

Impact-parameter dependence of K-vacancy production in Cu-Ni collisions  

Microsoft Academic Search

We have measured the impact-parameter (b) dependent probabilities (P) for the production of Ni (and Cu) K x rays in the bombardment of thin nickel foils by 50- and 65.5-MeV Cu beams. The shape of P(b) is found to be independent of nickel-foil thickness (t) and of the presence of a pre-exciting carbon layer, but the magnitude scale of both

C. H. Annett; B. Curnutte; C. L. Cocke

1979-01-01

286

Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics  

PubMed Central

Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27C and 35C, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27C and 35C ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27C and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35C wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35C wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region. PMID:24713562

Gravina, Marco Abdo; Canavarro, Cristiane; Elias, Carlos Nelson; Chaves, Maria das Graas Afonso Miranda; Brunharo, Ione Helena Vieira Portella; Quinto, Ctia Cardoso Abdo

2014-01-01

287

Morphology and composition of chalcopyrite, chromite, Cu, Ni-Fe, pentlandite, and troilite in vugs of 76015 and 76215  

NASA Technical Reports Server (NTRS)

Vugs from 76015 and 76215 are lined with euhedral crystals of plagioclase, pyroxene, ilmenite, Ni-Fe, and troilite. Smaller crystals of chromite, pentlandite, and chalcopyrite occur on the surface of the troilite in 76015. Wire Cu and dendritic-metallic Cu occurs with metallic Ni-Fe and troilite in some vugs of 76215. Troilite in both samples may have crystallized from an immiscible sulfide liquid. With falling temperature, chalcopyrite, and pentlandite may have exsolved from the troilite in 76015. By contrast, metallic Cu may have formed in 76215 by thermal breakdown of a bornite, troilite, and Ni-Fe assemblage which originally crystallized from a low-Ni immiscible sulfide liquid.

Carter, J. L.; Clanton, U. S.; Laughon, R. B.; Mckay, D. S.; Usselman, T. M.; Fuhrman, R.

1975-01-01

288

[The forming phase and various properties of Au, Ag, Cu and Ga mixture in metal fired crowns].  

PubMed

A new time-saving method has been developed to produce artificial crowns without using the casting process. Plastic mixtures of gallium and other metal particles are kneaded into desired shape and then heated for hardening. By this method, the time required for hardening and producing restorative materials has been shortened greatly. In the present experiment, gallium was triturated with powdered gold, silver and copper to make binary alloy samples. The dimensional change was measured between heat treatment. After heat treatment, the test piece was examined for compressive strength, compressive shrinkage, hardness, tarnishing and difference in phase. Non-heated and heated alloy specimens (Au-Ga, Ag-Ga, Cu-Ga) expanded to form the new phase. The ability of Au-Ga samples to bear compressive strength, when heated at 300 degrees C or more (AuGa2----AuGa), became 2.6 times greater than that of non-heat-treated specimens. The compressive strength of Ag-Ga samples dropped briefly at 350 degrees C (Ag0.72Ga0.28----Ag3Ga) but increased at 450 degrees C (Ag3Ga----AgGa). The strength of Cu-Ga pieces fell by half at 475 degrees C and upward (CuGa2----unknown phase). A compression test showed that the contraction percentage of Au and Ag specimens became large as a result of heat treatment, while that of Cu alloys remained almost unchanged. The results of a hardness test (HV) were comparable to those of the compressive strength test. The Au-Ga alloys increased in hardness after high-temperature treatment. In the Ag-Ga alloys, hardness declined at 350 degrees C and increased at 450 degrees C. There was no difference in hardness between Cu specimens after heat treatment and those allowed to stand at room temperature. A tarnishing test revealed that Au-Ga samples turned slightly yellowish. In the case of Ag-Ga samples, the reflectivity Y (%) dipped slightly but discoloration was not recognizable. However, the Cu-Ga samples which were heated at temperatures of up to 280 degrees C showed a slight drop in reflectivity, but those heated at temperatures higher than 280 degrees C decreased to 50-66% in reflectivity and turned black. PMID:2135544

Yoshida, T; Miyasaka, T; Okamura, H; Mizutani, Y; Hanaka, M; Miyake, S; Seo, I; Ito, M

1990-11-01

289

Chemical Stability of (Ag,Cu)2Se: a Historical Overview  

NASA Astrophysics Data System (ADS)

Recent work on Cu2- x Se has caused strong interest in this material due to its high reported peak zT (1.5) and the reduction of thermal conductivity through the mechanism of liquid-like suppression of heat capacity. In the 1960s, 3M patented Cu1.97Ag0.03Se as "TPM-217." Over the following decade it was tested and developed by the 3M Corporation, at the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory, Teledyne Energy Systems, and the General Atomics Corporation for use as a next-generation thermoelectric material. During these tests, extreme problems with material loss through Se vaporization and chemical reactions between the material and the device contacts were found. These problems were especially severe while operating under conditions of high iL/A. As a result, the material system was abandoned. The results of these reports are discussed. A simple test of degradation of Cu2Se under conditions of applied current and thermal gradient was performed and showed results compatible with the work done by General Atomics.

Brown, David R.; Day, Tristan; Caillat, Thierry; Snyder, G. JeffREY

2013-07-01

290

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

SciTech Connect

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

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

2010-06-15

291

HRTEM studies of NiNbZr + Ag amorphous-nanocrystalline composites.  

PubMed

Amorphous powder of composition corresponding to Ni60Ti20Zr20 (in at%) was obtained by ball milling in a high-energy mills starting from pure elements. Formation of the amorphous structure was observed already after 20 h of milling, although complete amorphization occurred after 40 h. The microhardness of powders increased from about 30 HV for pure elements to above 400 HV (1290 MPa) after 40 h of milling. Transmission electron microscopy (TEM) allowed to identify nanocrystalline inclusions of intermetallic phases of size 2-10 nm. Uniaxial hot pressing was performed in vacuum at temperature below the crystallization T(x) it is 510 degrees C and pressure of 600 MPa, Mixed amorphous powders and nanocrystalline silver powders were used to form a composite, in which microhardness was near 970 MPa HV and 400 HV for the amorphous phase and nanocrystalline silver, respectively. The compression strength of the composite containing 20 wt% of nanocrystalline Ag powder was equal to 600 MPa and plastic strain was 2%. Microstructure studies showed low porosity of composites of less than 1%, uniform distribution of the silver phase and a transition zone between both components, about 150 nm thick, where diffusion of nickel, niobium and zirconium into silver was observed. High-resolution TEM allowed identifying the structure of nanocrystalline inclusions in the amorphous matrix after hot pressing as either Ni(3)Zr or Ni(17)Nb(3). The identification was performed basing on measurements of angles and interatomic distances using inverse Fourier transformed images with enhanced contrast using Digital Micrograph computer program. PMID:19903239

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

2009-11-01

292

Cross-Interaction Study of Cu/Sn/Pd and Ni/Sn/Pd Sandwich Solder Joint Structures  

NASA Astrophysics Data System (ADS)

Cross-interactions between Cu/Sn/Pd and Ni/Sn/Pd sandwich structures were investigated in this work. For the Cu/Sn/Pd case, the growth behavior and morphology of the interfacial (Pd,Cu)Sn4 compound layer was very similar to that of the single Pd/Sn interfacial reaction. This indicates that the growth of the (Pd,Cu)Sn4 layer at the Sn/Pd interface would not be affected by the opposite Cu/Sn interfacial reaction. We can conclude that there is no cross-interaction effect between the two interfacial reactions in the Cu/Sn/Pd sandwich structure. For the Ni/Sn/Pd case, we observed that: (1) after 300 s of reflow time, the (Pd,Ni)Sn4 compound heterogeneously nucleated on the Ni3Sn4 compound layer at the Sn/Ni interface; (2) the growth of the interfacial PdSn4 compound layer was greatly suppressed by the formation of the (Pd,Ni)Sn4 compound at the Sn/Ni interface. We believe that this suppression of PdSn4 growth is caused by heterogeneous nucleation of the (Pd,Ni)Sn4 compound in the Ni3Sn4 compound layer, which decreases the free energy of the entire sandwich reaction system. The difference in the chemical potential of Pd in the PdSn4 phase at the Pd/Sn interface and in the (Pd,Ni)Sn4 phase at the Sn/Ni interface is the driving force for the Pd atomic flux across the molten Sn. The diffusion of Ni into the ternary (Pd,Ni)Sn4 compound layer controls the Pd atomic flux across the molten Sn and the growth of the ternary (Pd,Ni)Sn4 compound at the Sn/Ni interface.

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

2012-01-01

293

Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy  

SciTech Connect

The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an ?-Al matrix. The strength at room temperature and at 300C is studied as a function of solution treatment time at 490C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300C. - Highlights: The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. An imaging analysis procedure to segment phases with similar contrasts is presented. 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.

Asghar, Z., E-mail: zhdasghar@yahoo.com [Materials Division, Directorate of Technology, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Vienna University of Technology, Institute of Materials Science and Technology, Karlsplatz 13/308, A-1040 Vienna (Austria); Requena, G. [Vienna University of Technology, Institute of Materials Science and Technology, Karlsplatz 13/308, A-1040 Vienna (Austria); Zahid, G.H.; Rafi-ud-Din [Materials Division, Directorate of Technology, PINSTECH, P. O. Nilore, Islamabad (Pakistan)

2014-02-15

294

High-Pressure Cold-Sprayed Ni and Ni-Cu Coatings: Improved Structures and Corrosion Properties  

NASA Astrophysics Data System (ADS)

Cold spraying is a promising technique for the production of dense metallic coatings. In cold spraying, coating formation is through high velocity impacts of solid particles with high kinetic energy. During impact, particles deform plastically and adhere to the substrate, gradually building-up the coating. This makes it possible to form pure and dense coating structures. These impermeable coatings are advantageous in many applications such as those where corrosion protection is required. Nickel and nickel-copper alloys have good corrosion resistance and therefore, as dense coatings, have high potential for employment as corrosion barrier layers. In this study, the structural and corrosion properties of high-pressure cold-sprayed (HPCS) Ni and NiCu coatings are characterized. NiCu alloys are known to have good corrosion resistance in sulphuric and hydrochloric acids, whereas Ni is resistant to caustic soda and alkaline salt solutions. This study also shows the effect of heat treatments on coating properties. FESEM studies of cross-sectional samples reveal structural details of the HPCS coatings while corrosion properties are evaluated with polarization measurements. The corrosion behavior of both the bulk and substrate material is determined in order to assess the real corrosion protection potential of the coatings.

Koivuluoto, Heli; Milanti, Andrea; Bolelli, Giovanni; Lusvarghi, Luca; Vuoristo, Petri

2014-01-01

295

ac susceptibility of thermally annealed and neutron irradiated Cu-Ni alloys  

NASA Technical Reports Server (NTRS)

Thermal annealing and high-flux neutron irradiation are used to vary the degree of short-range atomic order in Cu-Ni alloys of composition 40, 50, and 60 at. pct Ni. The magnetic state is measured by ac magnetic susceptibility measurements. It is shown that annealing at 350 C causes significant changes in the susceptibility of all the samples. In the 50 and 60 at. pct Ni samples, the transition is broadened and extended to higher temperatures, while the 40 at. pct Ni sample changes from a paramagnetic system to a weakly ferromagnetic system. The neutron irradiation, in contrast to the thermal treatment, causes the development of smaller size cluster formations. The irradiated 60 at. pct Ni sample exhibits no change in the shape of its susceptibility curve from that of the quenched sample, whereas, the 40 pct alloy is changed, by irradiation, from a paramagnetic system to a spin-glass system.

Catchings, R. M., III; Borg, R. J.; Violet, C. E.

1985-01-01

296

Electronic, magnetic, and transport properties and magnetic phase transition in quaternary (Cu,Ni)MnSb Heusler alloys  

Microsoft Academic Search

The electronic properties, finite-temperature magnetism, and transport properties of semi-Heusler quaternary alloys (Cu,Ni)MnSb are studied theoretically by means of ab initio calculations as a function of the alloy composition. As documented by experiment, the transition from the ferromagnetic state (NiMnSb) to the antiferromagnetic state (CuMnSb) gives rise to an abrupt change in the magnetic moments and resistivities at about xCu≈0.7

J. Kudrnovsk; V. Drchal; I. Turek; P. Weinberger

2008-01-01

297

Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy  

NASA Astrophysics Data System (ADS)

Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

2014-11-01

298

Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy  

NASA Astrophysics Data System (ADS)

Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

2015-02-01

299

Electric current effects upon the Sn\\/Cu and Sn\\/Ni interfacial reactions  

Microsoft Academic Search

Electromigration-induced failures in integrated circuits have been intensively studied recently; however, electromigration\\u000a effects upon interfacial reactions have not been addressed. These electromigration effects in the Sn\\/Cu and Sn\\/Ni systems\\u000a were investigated in this study by analyzing their reaction couples annealed at 200C with and without the passage of electric\\u000a current. The intermetallics formed were ?-(Cu3Sn) and ?-(Cu6Sn5) phases in the

Sinn-Wen Chen; Chin-Ming Chen; Wen-Chyuarn Liu

1998-01-01

300

Oscillatory coupling in NiFe/Cu multilayers with low coercivity  

NASA Astrophysics Data System (ADS)

The oscillatory coupling, GMR and field sensitivity ( S) on the glass deposited Ni 83Fe 17/Cu multilayers (Mls) as a function of the Cu spacer are discussed. The oscillation period is 1 nm and the maximum of S = 0.13 [%/Oe] was obtained for Mls with dPy = 1.8 nm and dCu = 2 nm. Low temperature destroys AF coupling due to the pin-holes and a transition from partially AF to FF coupling at T = 52 K occurs.

Stobiecki, T.; Stobiecki, F.; Czapkiewicz, M.; Wrona, J.; Castao, F. J.; Muoz, J. L.

1999-05-01

301

Trends in negative thermal expansion behavior for AMO 2 ( A=Cu or Ag; M=Al, Sc, In, or La) compounds with the delafossite structure  

Microsoft Academic Search

Powder neutron diffraction data were obtained from 30 to 600K for CuAlO2, CuInO2, CuLaO2, 2H CuScO2, 3R CuScO2, and AgInO2. Rietveld refinements of these data showed negative thermal expansion (NTE) of the OCuO linkage in all cases. This behavior was especially strong for CuLaO2 and CuScO2, where it persisted up to our maximum measuring temperature of 600K. This NTE in

J. Li; A. W.. Sleight; C. Y. Jones; B. H. Toby

2005-01-01

302

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

PubMed Central

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

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

2013-01-01

303

Nitrided glass as a reaction medium: reduction of Ag and Cu within a phosphorus oxynitride glass matrix  

Microsoft Academic Search

Nitrogen incorporation as N3? into a phosphate glass network gives the oxynitride glass medium a reducing character. From a thermodynamic approach to the reduction phenomenon we predict with good approximation the reduction or not of various metal oxides. This property makes possible the in situ precipitation of metallic particles of Ag and Cu from the corresponding oxides, in particular in

Andr Le Sauze; Erwan Gueguen; Roger Marchand

1997-01-01

304

Enhancing the Ductility of Sn-Ag-Cu Lead-Free Solder Joints by Addition of Compliant Intermetallics  

NASA Astrophysics Data System (ADS)

Tin (Sn)-rich lead (Pb)-free solders containing rare-earth (RE) elements have been shown to exhibit desirable attributes of microstructural refinement and enhanced ductility relative to conventional Sn-3.9Ag-0.7Cu lead-free solder, due to the unique mechanical properties of RE-Sn intermetallics. However, the roles of soft intermetallic phase in the enhanced ductility of Pb-free solder still need to be further investigated. In this paper, Ca and Mn were selected as doping elements for Sn-Ag-Cu solder. The mechanical properties of Ca-Sn and Mn-Sn intermetallics as a function of indentation depth were measured by nanoindentation using the continuous stiffness method (CSM). The microstructure and mechanical properties of as-reflowed Ca- and Mn-containing Sn-Ag-Cu solder joints were studied and compared with those of conventional Sn-Ag-Cu and RE-containing solder joints. It is shown that soft intermetallics result in higher ductility in Pb-free solders.

Xie, H. X.; Chawla, N.

2013-03-01

305

The difference in degradation behaviour of ZnS:Cu,Al,Au and ZnS:Ag,Cl phosphor powders  

NASA Astrophysics Data System (ADS)

Auger electron spectroscopy (AES) and cathodoluminescence (CL) measurements showed that surface reactions with the consequent loss of CL intensity occur for both the ZnS:Cu,Al,Au and ZnS:Ag,Cl phosphor powders during prolonged electron bombardment. Although ZnO layers formed on both the ZnS phosphor surfaces there is a difference between the degradation behaviour of these two phosphors. Surface charging occurs during electron bombardment of the aged ZnS:Ag,Cl phosphor due to the formation of a non-conductive ZnO surface layer. Charging of the ZnS:Ag,Cl phosphor resulted in a delay in the surface reactions and to an increase in the CL degradation rate due to band-bending. A much slower degradation in CL intensity was measured for ZnS:Cu,Al,Au, where no charging occurred.

Swart, H. C.; Greeff, A. P.; Holloway, P. H.; Berning, G. L. P.

1999-02-01

306

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

NASA Astrophysics Data System (ADS)

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

Ghanaatshoar, Majid; Moradi, Mehrdad; Tohidi, Parsis

2014-10-01

307

Effects of alloying 30 at. % Ni using a Cu catalyst on the growth of bilayer graphene  

NASA Astrophysics Data System (ADS)

A small percentage graphene bilayer where the first layer was fully covered with a graphene sheet was grown on alloy foils via an inductively coupled plasma-chemical vapor deposition chamber. Compared with Cu foils, the alloy foils led to faster growth of the graphene film, while maintaining the same quality, homogeneity, and thickness uniformity over the whole area synthesized as the growth characteristics of a monolayer graphene grown on Cu. Moreover, the combined catalyst had a graphene film simultaneously grown with a metallic compound of magnesium silicate in some regions and of 200 nm Cu2.4S in other regions. Nevertheless, graphene was grown continuously and highly homogenously over the entire large area synthesized without boundaries between regions. Thus the resulting graphene growth is affected primarily by the Cu catalyst and partly by the Ni and that the quality of the graphene is dependent on the Cu catalyst.

Lee, Wan-Gyu; Kim, Eunho; Jung, Jongwan

2012-12-01

308

Aqueous phase reforming of glycerol over nanosize Cu-Ni catalysts.  

PubMed

In this work, hydrogen production from glycerol by aqueous phase reforming (APR) is studied by using nanosize Ni-Cu catalysts supported on LaAlO3 perovskite in order to investigate the effects of the copper loading amount and the reaction conditions. Nanosize copper-promoted nickel-based catalysts were prepared by the precipitation method. The structure of the nanosize catalysts is characterized by XRD analysis. The surface area, morphology, dispersion and reducibility of the nanosize catalysts is examined by BET, TEM and TPR, respectively. It was found that 15Ni-5Cu/LaAlO3 catalyst showed the highest glycerol conversion and hydrogen selectivity. The highest activity found in the 15Ni-5Cu/LaAlO3 was attributed to it having the proper copper loading amount. It also has the lowest metal crystal size and the highest surface area, which have an effect on the catalytic activity and hydrogen selectivity. The 15Ni-5Cu/LaAlO3 catalyst showed the best performance for hydrogen production at a reaction temperature of 250 degrees C, a reaction pressure of 20 bar and a feed rate of 5 ml/h. PMID:23646780

Kim, Ji Yeon; Kim, Seong Hak; Moon, Dong Ju; Kim, Jong Ho; Park, Nam Cook; Kim, Young Chul

2013-01-01

309

Solid state bonding of Al2O3 with Cu, Ni and Fe: characteristics and properties  

Microsoft Academic Search

A solid state bonding technique under hot pressing was used for joining alumina with thin metal sheets of Ni, Cu and Fe. The microstructure and microchemistry of the ceramicmetal interface and of the fracture interface were examined using scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), in order to identify the adhesion mechanisms and the nature

L. Esposito; A. Bellosi; S. Guicciardi; G De Portu

1998-01-01

310

Electroflotation Studies on Cu, Ni, Zn, and Cd with Ammonium Dodecyl Dithiocarbamate  

Microsoft Academic Search

The concentration of Cu, Ni, Zn, and Cd ions by electroflotation using the ammonium salt of dodecyl dithiocarbamic acid as an anionic collector is examined. Quantitative studies reveal better separation efficiency by this method as compared to column flotation using dodecyl dithiocarbamic acid ligand as a chelating surfactant.

V. Srinivasan; M. Subbaiyan

1989-01-01

311

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

312

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

NASA Astrophysics Data System (ADS)

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

Celik, Fatih Ahmet

2014-06-01

313

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

NASA Astrophysics Data System (ADS)

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

Zhai, Wei; Hong, Zhenyu; Wei, Bingbo

2007-08-01

314

Isotopic AgCuPb record of silver circulation through 16th18th century Spain  

PubMed Central

Estimating global fluxes of precious metals is key to understanding early monetary systems. This work adds silver (Ag) to the metals (Pb and Cu) used so far to trace the provenance of coinage through variations in isotopic abundances. Silver, copper, and lead isotopes were measured in 91 coins from the East Mediterranean Antiquity and Roman world, medieval western Europe, 16th18th century Spain, Mexico, and the Andes and show a great potential for provenance studies. Pre-1492 European silver can be distinguished from Mexican and Andean metal. European silver dominated Spanish coinage until Philip III, but had, 80 y later after the reign of Philip V, been flushed from the monetary mass and replaced by Mexican silver. PMID:21606351

Desaulty, Anne-Marie; Telouk, Philippe; Albalat, Emmanuelle; Albarde, Francis

2011-01-01

315

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

SciTech Connect

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

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

2012-02-06

316

The structure and magnetic properties of AgNiSiO2 nano-composite particles produced by pulsed laser control synthesis  

NASA Astrophysics Data System (ADS)

AgNiSiO2 nano-composite particles were produced using a pulsed laser control synthesis method comprising a gas phase evaporation and liquid phase collection method. The targets were mixtures composed of micron sized powders consisting of 4%, 7% and 10% Ni powder mixed with 20% SiO2 powder and Ag powder. The morphology, structure and synthesis mechanism of the nano-composite particles were studied by means of TEM, XRD, and IR and UV spectroscopy. The results indicate that the AgNiSiO2 nano-composite particles prepared with this method are spherical with good dispersion. The diameters of the primary particles were found to range from 5 nm to 35 nm and the AgNiSiO2 nano-composite particles were found to have a mixed composite structure. The saturation magnetization of the AgNiSiO2 nano-composite particles increased gradually with the increase of Ni content. The ethylene glycol in the liquid phase is adsorbed onto the surface of the nano-composite particles and this plays a role in the in situ dispersing of the AgNiSiO2 nano-composite particles.

Chen, Suiyuan; Wang, Ting; Li, Yunjie; Liang, Jing; Wellburn, Dan; Liu, Changsheng

2015-01-01

317

Geology, mineralogy and fluid inclusion data from the Arapucan Pb Zn Cu Ag deposit, Canakkale, Turkey  

NASA Astrophysics Data System (ADS)

The Arapucan Pb-Zn-Cu-Ag deposit occurs as hydrothermal veins in diabase and altered Triassic metasandstones adjacent to calc-alkaline intrusive igneous rocks. The deposit is an important commercial source of base metal in northwestern Turkey. Potential by-products are silver and gold. The geology of the area includes a Paleozoic metamorphic basement, Triassic sedimentary rocks with carbonate blocks, Tertiary granitoids and Neogene volcanics. The mineral assemblage includes galena, quartz, calcite, sphalerite, chalcopyrite and pyrite as well as minor bismuthinite, tetrahedrite, pyrolusite, hematite, scheelite, malachite, magnetite, limonite and rutile. Silver is associated with tetrahedrite. Early hydrothermal activity was responsible for the formation of three hypogene alteration types of decreasing intensity: silicification, sericitization and argillic alteration. These alteration styles show a rough spatial zonation. The ore stage clearly postdates hydrothermal alteration, as indicated by the occurrence of ore minerals in vuggy cavities and fractures in silica bodies. The deposit contains evidence of at least two periods of hypogene mineralization separated by a period of faulting. In addition to Pb, Zn, Cu, Ag and Au, the ores contain substantial quantities of W, Bi, Sb and Te. Average ? 34S values for galena and pyrite are -3.95 and -2.24, respectively, suggesting an igneous source for both the sulphur and metals. However, geological and geochemical interpretations suggest that at least some of the metals were leached from the metasandstones and diabases. Fluid inclusions in main-stage sphalerite homogenize at 229-384 C with salinities ranging from 1.7 to 18.5 eq.wt% NaCl. The deposits formed as the result of the interaction of two aqueous fluids: a higher-salinity fluid (probably magmatic) and a dilute meteoric fluid. The narrow range of ? 34S (galena and pyrite) values (-5.2 to -1.2 CDT) suggests that the sulphur source of the hydrothermal fluids was the same during deposition of the metals.

Orgn, Yksel; Gltekin, Ali Haydar; Onal, Ayten

2005-07-01

318

[Quantitative surface analysis of Pt-Co, Cu-Au and Cu-Ag alloy films by XPS and AES].  

PubMed

In order to improve the quantitative analysis accuracy of AES, We associated XPS with AES and studied the method to reduce the error of AES quantitative analysis, selected Pt-Co, Cu-Au and Cu-Ag binary alloy thin-films as the samples, used XPS to correct AES quantitative analysis results by changing the auger sensitivity factors to make their quantitative analysis results more similar. Then we verified the accuracy of the quantitative analysis of AES when using the revised sensitivity factors by other samples with different composition ratio, and the results showed that the corrected relative sensitivity factors can reduce the error in quantitative analysis of AES to less than 10%. Peak defining is difficult in the form of the integral spectrum of AES analysis since choosing the starting point and ending point when determining the characteristic auger peak intensity area with great uncertainty, and to make analysis easier, we also processed data in the form of the differential spectrum, made quantitative analysis on the basis of peak to peak height instead of peak area, corrected the relative sensitivity factors, and verified the accuracy of quantitative analysis by the other samples with different composition ratio. The result showed that the analytical error in quantitative analysis of AES reduced to less than 9%. It showed that the accuracy of AES quantitative analysis can be highly improved by the way of associating XPS with AES to correct the auger sensitivity factors since the matrix effects are taken into account. Good consistency was presented, proving the feasibility of this method. PMID:24555396

Li, Lian-Zhong; Zhuo, Shang-Jun; Shen, Ru-Xiang; Qian, Rong; Gao, Jie

2013-11-01

319

Ion irradiation induced nanocrystal formation in amorphous Zr 55Cu 30Al 10Ni 5 alloy  

NASA Astrophysics Data System (ADS)

Ion irradiation can be used to induce partial crystallization in metallic glasses to improve their surface properties. We investigated the microstructural changes in ribbon Zr 55Cu 30Al 10Ni 5 metallic glass after 1 MeV Cu-ion irradiation at room temperature, to a fluence of 1.0 10 16 cm -2. In contrast to a recent report by others that there was no irradiation induced crystallization in the same alloy [S. Nagata, S. Higashi, B. Tsuchiya, K. Toh, T. Shikama, K. Takahiro, K. Ozaki, K. Kawatusra, S. Yamamoto, A. Inouye, Nucl. Instr. and Meth. B 257 (2007) 420], we have observed nanocrystals in the as-irradiated samples. Two groups of nanocrystals, one with diameters of 5-10 nm and another with diameters of 50-100 nm are observed by using high resolution transmission electron microscopy. Experimentally measured planar spacings ( d-values) agree with the expectations for Cu 10Zr 7, NiZr 2 and CuZr 2 phases. We further discussed the possibility to form a substitutional intermetallic (Ni xCu 1-x)Zr 2 phase.

Carter, Jesse; Fu, E. G.; Martin, Michael; Xie, Guoqiang; Zhang, X.; Wang, Y. Q.; Wijesundera, D.; Wang, X. M.; Chu, Wei-Kan; McDeavitt, Sean M.; Shao, Lin

2009-09-01

320

Pressure effect on the phase transition temperatures of Ni2Mn1- x Cu x Ga  

NASA Astrophysics Data System (ADS)

The martensitic transition temperature T M and the Curie temperature T C of the ferromagnetic alloys Ni2Mn1- x Cu x Ga (0 ? x ? 0.40) were measured under pressure. We estimated the pressure derivatives dT M / dp and dT C / dp from the results. The values of dT M / dp and dT C / dp for Ni2MnGa ( x = 0) were -4.5 K/GPa and +3.9 K/GPa, respectively. The values of dT M / dp increased from negative to positive with increasing x in Ni2Mn1- x Cu x Ga. The values of dT C / dp approached zero with increasing x.

Miura, Tomoya; Adachi, Yoshiya; Endo, Keita; Kainuma, Ryosuke; Kanomata, Takeshi

2013-06-01

321

Structure and magnetic properties of Sm-Ni-Cu compounds after mechanical treatment  

NASA Astrophysics Data System (ADS)

We have investigated the influence of mechanical alloying on structural changes and magnetic properties of the SmNi4Cu compound. This compound crystallizes in the hexagonal structure of CaCu5, space group P6/mmm. SmNi4Cu is ferromagnetic with the Curie temperature of 34 K and the saturation magnetic moment of 0.36 ? B at 4.2 K. The decrease of intensity and broadening of the diffraction lines have been detected after milling as a consequence of the grains' size reduction. The analysis of the as-prepared sample using EDAX has revealed a stable composition without a presence of any additional phases and elements. The obtained results show that the magnetic properties significantly depend on the milling time. The temperature and magnetic field dependences of the magnetization exhibit a presence of antiferromagnetic-like behavior of the milled samples. The transition temperature does not vary as a function of the milling time.

Szlaferek, A.; Andrzejewski, B.; Toliski, T.; Kowalczyk, A.

2006-01-01

322

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

323

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

324

Performance of the nano-structured Cu-Ni (alloy) -CeO2 anode for solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

In this work, copper and nickel oxides (CuO-NiO) powders with various mole ratios were synthesized by the glycine nitrate process (GNP) and the Cu-Ni alloy was obtained by reducing the CuO-NiO powders at 600C for 0.75h. Furthermore, Cu1-xNix (alloy) -CeO2 impregnated YSZ anodes were fabricated by the impregnation method and the optimized anode composition was evaluated. It was found that the optimized mole ratio of Cu:Ni was 5:5, while the weight ratio of Cu-Ni alloy to CeO2 was 3:1. Additionally, impregnated anode with 40wt % loading of Cu0.5Ni0.5 (alloy)-CeO2 exhibited the best performance and the polarization resistance of such anode was only 0.097, 0.115, 0.145 and 0.212?cm2 at 750, 700, 650 and 600C, respectively. Finally, the performance of the optimized anode in methane (CH4) was investigated and the carbon deposition is greatly suppressed compared to the Ni-based anode.

Liu, Minquan; Wang, Shaolan; Chen, Ting; Yuan, Chun; Zhou, Yucun; Wang, Shaorong; Huang, Jun

2015-01-01

325

Effect of substitution for Ni by Co and\\/or Cu on the thermoelectric properties of half-Heusler ZrNiSn  

Microsoft Academic Search

We have synthesized the half-Heusler ZrNiSn alloys where the Ni is partially substituted by Co and\\/or Cu. Such substitution much affects the thermoelectric properties of ZrNiSn by changing the valence electron count (VEC) of the material. The behaviors in the Seebeck coefficient and electrical resistivity for ZrNi1?xCoxSn or ZrNi1?yCuySn system can be understood as the result of the increase in

S. Katsuyama; H. Matsushima; M. Ito

2004-01-01

326

Chirality switching and winding or unwinding of the antiferromagnetic NiO domain walls in Fe/NiO/Fe/CoO/Ag(001).  

PubMed

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

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

2014-10-01

327

Tailoring of UV/violet plasmonic properties in Ag, and Cu coated Al concaves arrays  

NASA Astrophysics Data System (ADS)

UV plasmonics is of particular interest because of large variety of applications, where the higher energy plasmon resonances would advance scientific achievements, including surface-enhanced Raman scattering (SERS) with UV excitation, ultrasensitive label-free detection of important biomolecules absorbing light in the UV, or the possibility for exerting control over photochemical reactions. Despite its potential, UV plasmonics is still in its infancy, mostly due to difficulties in fabrication of reproducible nanostructured materials operating in this high energy range. Here, we present a simple electrochemical method to fabricate regular arrays of aluminum concaves demonstrating plasmonic properties in UV/violet region. The method enables the preparation of concaves with well-controlled geometrical parameters such as interpore distance (Dc), and therefore, well controllable plasmon resonances. Moreover, the patterning is suitable for large scale production. The UV/violet properties of Al concaves can be further fine-tuned by Ag and Cu metals. The refractive index sensitivity (RIS) increases after the metals deposition as compared to RIS of pure Al nanohole arrays. The highest RIS of 404 nm/RIU was obtained for Cu coated Al nanoconcaves with the Dc = 460.8 nm, which is similar or better than the RIS values previously reported for other nanohole arrays, operating in visible/near IR range.

Norek, Ma?gorzata; W?odarski, Maksymilian; St?pniowski, Wojciech J.

2014-09-01

328

K-shell ionization cross section for Ti, Fe, Cu, Zr, and Ag  

SciTech Connect

Absolute K-shell ionisation cross sections have been measured for thin targets of Ti, Fe, Cu, Zr and Ag for protons in the energy range 85-790 keV and for thin targets of Ti, Fe and Cu for He ions in the energy range 190-750 keV. In addition the relative variation of the cross sections with energy has been determined with high accuracy. The experimental values are compared to the perturbed stationary state approximation (CPSSR) and the semiclassical approximation (SCA). The CPSSR theory provides the best overall agreement with experimental cross sections. For higher scaled energies the CPSSR theory predicts the energy dependence of the cross sections very well but in the lower energy range it overpredicts the cross sections by as much as a factor of two and this overprediction seems to increase with Z/sub 2/ at a fixed scaled energy y. The SCA theory predicts slightly too large ionisation cross sections except for the lowest pounds values. The relative variation of the cross sections with energy is not well described in either energy range.

Benka, O.; Geretschlager, M.

1981-04-01

329

Sulfides from Martian and Lunar Basalts: Comparative Chemistry for Ni Co Cu and Se  

SciTech Connect

Here Mars and Moon are used as 'natural laboratories' with Moon displaying lower oxygen fugacities ({approx}IW-1) than Mars ({approx}IW to FMQ). Moon has lower concentrations of Ni and Co in basaltic melts than does Mars. The major sulfides are troilite (FeS) in lunar basalts and pyrrhotite (Fe{sub 1-x}S) in martian basalts. This study focuses on the concentrations of Ni, Co, Cu, and Se. We chose these elements because of their geochemical importance and the feasibility of analyzing them with a combination of synchrotron X-ray fluorescence (SXRF) and electron microprobe (EPMA) techniques. The selenium concentrations could only be analyzed, at high precision, with SXRF techniques as they are <150 ppm, similar to concentrations seen in carbonaceous chondrites and interplanetary dust particles (IDPs). Nickel and Co are in higher concentrations in martian sulfides than lunar and are higher in martian olivine-bearing lithologies than olivine-free varieties. The sulfides in individual samples show very large ranges in concentration (e.g., Ni ranges from 50 000 ppm to <5 ppm). These large ranges are mainly due to compositional heterogeneities within individual grains due to diffusion and phase separation. Electron microprobe wavelength-dispersive (WDS) mapping of Ni, Co, and Cu show the diffusion trajectories. Nickel and Co have almost identical diffusion trajectories leading to the likely nucleation of pentlandite (Ni,Co,Fe){sub 9}S{sub 8}, and copper diffuses along separate pathways likely toward chalcopyrite nucleation sites (CuFeS{sub 2}). The systematics of Ni and Co in lunar and martian sulfides clearly distinguish the two parent bodies, with martian sulfides displaced to higher Ni and Co values.

J Papike; P Burger; C Shearer; S Sutton; M Newville; Y Choi; A Lanzirotti

2011-12-31

330

Temperature dependence of magnetic properties in epitaxial Cu\\/Ni\\/Cu\\/Si (1 1 1) measured by magneto-optical Kerr effect  

Microsoft Academic Search

We report on magneto-optical Kerr effect (MOKE) measurements performed in the range 4300K on five epitaxial Cu\\/Ni\\/Cu\\/Si (111) heterostructures, grown by UHV evaporation, with the Ni layer thickness d varying in the range between 30 and 10. In a previous work, we showed that, at room temperature, the magnetization lies preferentially in-plane for d?30 while it switches out-of-plane when 15?d?25.

F D'Orazio; F. Lucari; G. Gubbiotti; G. Carlotti; M De Crescenzi

1999-01-01

331

Structure and physical properties of the new telluride BaAg{sub 2}Te{sub 2} and its quaternary variants BaCu{sub {delta}}Ag{sub 2-{delta}}Te{sub 2}  

SciTech Connect

The new materials BaCu{sub {delta}}Ag{sub 2-{delta}}Te{sub 2} (0{<=}{delta}{<=}2) were prepared from the elements at 800 deg. C in evacuated silica tubes. BaAg{sub 2}Te{sub 2} crystallizes in the {alpha}-BaCu{sub 2}S{sub 2} type, space group Pnma, with lattice parameters a=10.8897(3) A, b=4.6084(1) A, c=11.8134(3) A (Z=4). The structure consists of a three-dimensional network of vertex- and edge-condensed AgTe{sub 4} tetrahedra, which includes the Ba{sup 2+} cations in linear channels running along the short b-axis. Half of the Ag atoms participate in an Ag atom zigzag chain extended parallel to the channels. BaAg{sub 2}Te{sub 2} is a p-type semiconductor with large Seebeck coefficient. Within the series BaCu{sub {delta}}Ag{sub 2-{delta}}Te{sub 2}, the electrical conductivity increases and the Seebeck coefficient decreases strongly with increasing Cu content. - Graphical abstract: The tellurides BaCu{sub {delta}}Ag{sub 2-{delta}}Te{sub 2} all crystallize in the {alpha}-BaCu{sub 2}S{sub 2} type. The Ag atoms prefer the M2 sites with short M-M bonds (solid lines). The materials are (degenerate) p-type semiconductors. Higher Ag content reflects itself in higher Seebeck coefficient and lower electrical conductivity.

Assoud, Abdeljalil; Cui Yanjie; Thomas, Stephanie; Sutherland, Brodie [Department of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada); Kleinke, Holger [Department of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada)], E-mail: kleinke@uwaterloo.ca

2008-08-15

332

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

Microsoft Academic Search

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

Naoyuki Miyasaka; Yoshihiro Doi; Yukio Hinatsu

2009-01-01

333

Effects of Ag content on the mechanical properties of (Nd,Eu,Gd)-Ba-Cu-O bulk superconductors  

NASA Astrophysics Data System (ADS)

In order to investigate the effects of Ag content on the mechanical properties of a high performance melt-processed (Nd,Eu,Gd)Ba 2Cu 3O y single grain bulk superconductors with 30 mol% Gd 2BaCuO 5, tensile tests of specimens cut from the bulks have been carried out at room temperature. The tensile strength in the direction perpendicular to the c-axis of the sample with 20 wt.% Ag was higher than that of the sample with 10 wt.% Ag. This is ascribed to a decrease in the void fraction and suppression of cracks by an increased Ag particles revealed by the microstructure image analysis. The almost identical value of Youngs modulus obtained for both of the samples are presumably due to the balance of the effects of the voids and soft Ag particles mentioned above. Comparing these results with that in the c-axis direction and that obtained by the compressive test, the anisotropy of the elastic behavior associated with the effect of pre-existing micro-cracks perpendicular to the c-axis was discussed.

Katagiri, K.; Murakami, A.; Kan, R.; Kasaba, K.; Noto, K.; Muralidhar, M.; Sakai, N.; Murakami, M.

2003-10-01

334

Structures and phase transitions of the A7PSe6 (A = Ag, Cu) argyrodite-type ionic conductors. II. Beta- and gamma-Cu7PSe6  

PubMed

The crystal structures of two of the three polymorphic forms of the Cu7PSe6 argyrodite compound are determined by means of single-crystal X-ray diffraction. In the high-temperature form, at 353 K, i.e. 33 K above the first phase transition, gamma-Cu7PSe6 crystallizes in cubic symmetry, space group F43m. The full-matrix least-squares refinement of the structure leads to the residual factors R = 0.0201 and wR = 0.0245 for 31 parameters and 300 observed independent reflections. In the intermediate form, at room temperature, beta-Cu7PSe6 crystallizes again in cubic symmetry, but with space group P2(1)3. Taking into account a merohedric twinning, the refinement of the beta-Cu7PSe6 structure leads to the residual factors R = 0.0297 and wR = 0.0317 for 70 parameters and 874 observed, independent reflections. The combination of a Gram-Charlier development of the Debye-Waller factor and a split model for copper cations reveals the possible diffusion paths of the d10 species in the gamma-Cu7PSe6 ionic conducting phase. The partial ordering of the Cu+ d10 element at the phase transition is found in concordance with the highest probability density sites of the high-temperature phase diffusion paths. A comparison between the two Cu7PSe6 and Ag7PSe6 analogues is carried out, stressing the different mobility of Cu+ and Ag+ and their relative stability in low-coordination chalcogenide environments. PMID:10877347

Gaudin; Boucher; Petricek; Taulelle; Evain

2000-06-01

335

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

PubMed

We present comparative analysis of microscopic mechanisms relevant to plastic deformation of the face-centered cubic (FCC) metals Al, Cu, and Ni, through determination of the temperature-dependent free energies of intrinsic and unstable stacking faults along [1 1? 0] and [1 2? 1] on the (1?1?1) plane using first-principles density-functional-theory-based calculations. We show that vibrational contribution results in significant decrease in the free energy of barriers and intrinsic stacking faults (ISFs) of Al, Cu, and Ni with temperature, confirming an important role of thermal fluctuations in the stability of stacking faults (SFs) and deformation at elevated temperatures. In contrast to Al and Ni, the vibrational spectrum of the unstable stacking fault (USF[1 2? 1]) in Cu reveals structural instabilities, indicating that the energy barrier (?usf) along the (1?1?1)[1 2? 1] slip system in Cu, determined by typical first-principles calculations, is an overestimate, and its commonly used interpretation as the energy release rate needed for dislocation nucleation, as proposed by Rice (1992 J. Mech. Phys. Solids 40 239), should be taken with caution. PMID:25185834

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

2014-09-24

336

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

337

Electrochemical Deposition of Ni on an Al-Cu Alloy  

Microsoft Academic Search

Metallic coatings can be used to improve the wear and corrosion resistance of Al alloys. In this study, Ni was used as a candidate\\u000a material for such a coating which was applied on the surface of Al 2014 alloy using electrodeposition in a standard Watts\\u000a bath. A two-step heat treatment procedure was employed that served to increase the adhesion as

A. Ul-Hamid; A. Quddus; H. Dafalla; H. Saricimen; L. Al-Hadhrami

2011-01-01

338

Study of thermomechanical treatment on mechanical-induced phase transformation of NiTi and TiNiCu wires.  

PubMed

The nickel-titanium shape memory alloys have been used in orthodontic application due to their unique properties like superelasticity and biocompatibility. The phase transformation behavior of these alloys can be changed by alloying elements and thermomechanical processing conditions. In this study, two types of NiTi and TiNiCu wires of 0.4mm diameter were produced via thermomechanical treatments with final step of 20% cold drawing followed by annealing at different temperatures of 300 and 400 C for varying times of 10, 30 and 60 min. The processed wires were characterized by oral cavity configuration three point bending (OCTPB) test at 37 C to specify the mechanical transformation features. Also, differential scanning calorimetry (DSC) was used to analyze the thermal transformation temperatures of selected wires. The results showed the thermomechanical treatment at 300 C for 30 min was the suitable process in terms of superelasticity and transformation temperatures for orthodontic application. PMID:23454366

Seyyed Aghamiri, S M; Nili Ahmadabadi, M; Shahmir, H; Naghdi, F; Raygan, Sh

2013-05-01

339

Low temperature spin dynamics in Cr{sub 7}Ni-Cu-Cr{sub 7}Ni coupled molecular rings  

SciTech Connect

Proton Nuclear Magnetic Resonance (NMR) relaxation measurements have been performed down to very low temperature (50?mK) to determine the effect of coupling two Cr{sub 7}Ni molecular rings via a Cu{sup 2+} ion. No difference in the spin dynamics was found from nuclear spin lattice relaxation down to 1.5?K. At lower temperature, the {sup 1}H-NMR line broadens dramatically indicating spin freezing. From the plot of the line width vs. magnetization, it is found that the freezing temperature is higher (260?mK) in the coupled ring with respect to the single Cr{sub 7}Ni ring (140?mK)

Bordonali, L., E-mail: lorenzo.bordonali@unipv.it [INSTM and Department of Physics, Universit di Pavia, I-27100 Pavia (Italy); Ames Laboratory, and Department of Physics and Astronomy, Iowa State University, Iowa 50011 (United States); Department of Physics E. Amaldi, Universit Uniroma TRE, Roma (Italy); Furukawa, Y. [Ames Laboratory, and Department of Physics and Astronomy, Iowa State University, Iowa 50011 (United States); Mariani, M.; Sabareesh, K. P. V. [INSTM and Department of Physics, Universit di Pavia, I-27100 Pavia (Italy); Garlatti, E. [INSTM and Department of Physics, Universit degli Studi di Milano, via Celoria 16, I-20133 Milano (Italy); Dipartimento di Fisica, Universit di Parma, Viale Usberti 7/A, I-43100 Parma (Italy); Carretta, S. [Dipartimento di Fisica, Universit di Parma, Viale Usberti 7/A, I-43100 Parma (Italy); S3-CNR, Institute of Nanosciences, via Campi 213/A, I-41125 Modena (Italy); Lascialfari, A. [INSTM and Department of Physics, Universit degli Studi di Milano, via Celoria 16, I-20133 Milano (Italy); INSTM and Department of Physics, Universit di Pavia, I-27100 Pavia (Italy); S3-CNR, Institute of Nanosciences, via Campi 213/A, I-41125 Modena (Italy); Timco, G.; Winpenny, R. E. P. [The Lewis Magnetism Laboratory, The University of Manchester, M13 9PL Manchester (United Kingdom); Borsa, F. [INSTM and Department of Physics, Universit di Pavia, I-27100 Pavia (Italy); Ames Laboratory, and Department of Physics and Astronomy, Iowa State University, Iowa 50011 (United States)

2014-05-07

340

X-ray photoemission and magnetic studies of SmNi4M ( M=Al, Cu, B)  

NASA Astrophysics Data System (ADS)

The Curie temperatures of SmNi4M are 18, 35 and 38 K for M=Al, Cu, and B, respectively. These values are enhanced compared to the RNi4M compounds with other rare earths R due to the crystal electric field effects. A strong dependence of the coercive field HC on the M element has been observed. The large value of HC=7 T for SmNi4B crystallizing in the hexagonal CeCo4B-type of structure is reduced for SmNi4Cu (2.7 T) and SmNi4Al (1.5 T) both having the hexagonal CaCu5-type of structure. Using the structural argument, this behavior can be explained by the values of the c/a ratio. The X-ray photoemission spectroscopy of the valence band region reveals that SmNi4Cu differs from the other two compounds due to the presence of the Cu(3d) peak close to the Fermi level, which is dominated by the Ni(3d) peak. These electronic structure properties can be responsible for the increased magnetic moment of SmNi4Cu being 0.37?B, compared to the value of 0.24?B for the other two compounds.

Toli?ski, T.; Che?kowska, G.; Kowalczyk, A.

2006-05-01

341

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

PubMed

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

Liu, Xianghao; Braunstein, Pierre

2013-07-01

342

Magnetic properties of Be or Cu-substituted NiZn ferrites  

NASA Astrophysics Data System (ADS)

Polycrystalline NiZn ferrites with the chemical formula (Ni0.3Zn0.7)MexFe2O4 where Me is Be or Cu and x=0.05, 0.1 and 0.25 have been prepared by a ceramic method. Selected magnetic properties such as Curie temperature Tc and saturation magnetization Ms of the ferrites have been measured and discussed. Complex initial (relative) permeability ?=?'-j?? measurements have also been performed on the samples in the frequency range from 100 kHz to 100 MHz and the contribution of magnetization mechanisms is discussed.

Slma, Jozef; Dosoudil, Rastislav; Ukov, Marianna; Uk, Elemr; Gruskov, Anna; Jan?rik, Vladimr

2006-09-01

343

Synthesis of octopus-tentacle-like Cu nanowire-Ag nanocrystals heterostructures and their enhanced electrocatalytic performance for oxygen reduction reaction.  

PubMed

In this article, the novel octopus-tentacle-like Cu nanowire-Ag nanocrystals heterostructures have been fabricated in solution phase via heterogeneous nucleation and growth of Ag nanocrystals on presynthesized Cu nanowires. The growth environment and dynamic factors of Ag nanocrystals play an important role for formation of such heterostructures. Combined the physical constants of Cu and Ag with a series of control experiments, the epitaxial growth means of Ag nanocrystals on Cu nanowire is found to abide by "layer-plus-island" (Stranski-Krastanow) mode. Because of the presence of multiple junctions and strong synergistic effect of their constituents, the obtained heterostructures exhibit greatly enhanced electrocatalytic performance toward oxygen reduction reaction compared with that of pure Ag nanocrystals, Cu nanowires, and mechanically mixed dual components as well as recently reported some non-Pt materials, which can be served as an alternative cathodic electrocatalyst to apply in alkaline fuel cells. Moreover, our method can be extended to fabricate octopus-tentacle-like Cu nanowire-Au nanocrystals and Cu nanowire-Pd nanocrystals heterostructures. PMID:23157177

Han, Min; Liu, Suli; Zhang, Linyan; Zhang, Can; Tu, Wenwen; Dai, Zhihui; Bao, Jianchun

2012-12-01

344

Cu-doped indium oxide/Ag ohmic contacts for high-power flip-chip light-emitting diodes  

NASA Astrophysics Data System (ADS)

We have investigated Cu-doped In2O3(CIO)(3nm)/Ag(250nm) schemes for forming high-quality ohmic contacts to p-type GaN for high-power flip-chip light-emitting diodes (FCLEDs). It is shown that the CIO /Ag contacts produce specific contact resistance of 1.2810-5?cm2 and reflectance of about 90% at a wavelength of 460nm when annealed at 530C for 1min in air ambient. It is also shown that unlike single Ag contacts, the CIO /Ag contacts are fairly stable without surface and interface degradation although annealed at 530C for 1min in air ambient. In addition, blue multiquantum-well InGaN /GaN LEDs fabricated with the annealed CIO /Ag contact layers give forward-bias voltages of around 3.0V at an injection current of 20mA. The results strongly indicate that the CIO /Ag scheme can be a highly promising p-type contact for high-power GaN-based FCLEDs for solid-state lighting application.

Song, June-O.; Kwak, Joon Seop; Seong, Tae-Yeon

2005-02-01

345

Synthesis of polymer-stabilized monometallic Cu and bimetallic Cu/Ag nanoparticles and their surface-enhanced Raman scattering properties  

NASA Astrophysics Data System (ADS)

The present study demonstrates a facile process for the production of spherical-shaped Cu and Ag nanoparticles synthesized and stabilized by hydrazine and gelatin, respectively. Advantages of the synthetic method include its production of water dispersible copper and copper/silver nanoparticles at room temperature under no inert atmosphere. The resulting nanoparticles (copper or copper/silver) are investigated by X-ray diffraction (XRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The nanometallic dispersions were characterized by surface plasmon absorbance measuring at 420 and 572 nm for Ag and Cu nanoparticles, respectively. Transmission electron microscopy showed the formation of nanoparticles in the range of 10 nm (silver), and 30 nm (copper). The results also demonstrate that the reducing order of Cu2+/Ag+ is important for the formation of the bimetallic nanoparticles. The surface-enhanced Raman scattering effects of copper and copper/silver nanoparticles were also displayed. It was found that the enhancement ability of copper/silver nanoparticles was little higher than the copper nanoparticles.

Zhang, Danhui; Liu, Xiaoheng

2013-03-01

346

Magnetic properties and magnetocaloric effect at room temperature of Ni50- x Ag x Mn37Sn13 alloys  

NASA Astrophysics Data System (ADS)

In this work, we present a detailed study of the magnetic properties and the magnetocaloric effect at room temperature of Ni50- x Ag x Mn37Sn13 alloys with x = 1, 2, and 4, which were prepared by using an arc-melting method. Experimental results reveal that a partial replacement of Ag for Ni leads to a decrease in the anti-FM phase in the alloys. In addition, the martensitic-austenitic phase transition shifts towards lower temperature and is broaded. The Curie temperature ( T C A ) for the austenitic phase also shifts toward to lower temperature, but not by much. The Curie temperature was found to be 308, 305, and 298 K for x = 1, 2, and 4, respectively. The magnetic entropy change (? S m ) of the samples was calculated by using isothermal magnetization data. Under an applied magnetic field change of 10 kOe, the maximum value of ? S m (|? S max |) was achieved at around room temperature and did not change much (~0.8 Jkg-1K-1) with increasing Ag-doping concentration. Particularly, the M 2 vs. H/ M curves prove that all the samples exhibited a second-order magnetic phase transition. Based on Landau's phase-transition theory and careful analyses of the magnetic data around the T C A , we have determined the critical parameters ?, ?, ?, and T C . The results show that the ? values are located between those expected for the 3D-Heisenberg model ( ? = 0.365) and mean-field theory ( ? = 0.5). Such a result proves the coexistence of short-range and long-range ferromagnetic interactions in Ni50- x Ag x Mn37Sn13 alloys. The nature of the changes in the critical parameters and the |? S max | is thoroughly discussed by means of structural analyses.

Thanh, Tran Dang; Mai, Nguyen Thi; Dan, Nguyen Huy; Phan, The-Long; Yu, Seong-Cho

2014-11-01

347

The optical and vibrational properties of the quaternary chalcopyrite semiconductor alloy Ag{sub x}Cu{sub 1-x}GaS{sub 2}  

SciTech Connect

The absorption, emission and Raman spectra of the quaternary chalcopyrite alloys Ag{sub x}Cu{sub 1-x}GaS{sub 2} have been measured as a function of the Ag concentration. We find strong and highly nonlinear dependence on the alloy concentration in the optical band gap (a large bowing parameter). On the other hand, most of the Raman peaks exhibit either small energy shifts or large broadening with alloying. We conclude that the effect of substitution of the Ag cations by Cu in AgGaS{sub 2} on its band structure cannot be predicted by the simple virtual crystal potential approximation as a result of the large difference in electronegativity and bond length between Ag and Cu. (c) 2000 American Institute of Physics.

Choi, In-Hwan [Physics Department, Chung-Ang University, Seoul, Korea (Korea, Republic of)] [Physics Department, Chung-Ang University, Seoul, Korea (Korea, Republic of); Eom, Sung-Hwan [Physics Department, Chung-Ang University, Seoul, Korea (Korea, Republic of)] [Physics Department, Chung-Ang University, Seoul, Korea (Korea, Republic of); Yu, P. Y. [Department of Physics, University of California, Berkeley (United States) [Department of Physics, University of California, Berkeley (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2000-04-15

348

Texture improvements in the high-temperature superconducting Bi?Sr?Ca?Cu?Ox̳/Ag system via surface energy driven grain alignment  

E-print Network

The relation between processing, microstructure, and material property was investigated in the high-temperature superconducting Bi?Sr?Ca?Cu?Ox̳/Ag system. Experiments were based on a theoretical surface energy model ...

Vodhanel, Mark E

2005-01-01

349

Structure and magnetism of S = 1/2 kagome antiferromagnets NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2.  

PubMed

We have successfully synthesized S = 1/2 kagome antiferromagnets MCu(3)(OH)(6)Cl(2) (M = Ni and Co) by a hydrothermal method with a rotating pressure vessel. Structural characterization shows that both compounds have similar crystal structure to ZnCu(3)(OH)(6)Cl(2) with R3m symmetry. As with ZnCu(3)(OH)(6)Cl(2), the compounds show no obvious hysteresis at 2 K. A spin-glass transition is found in both NiCu(3)(OH)(6)Cl(2) and CoCu(3)(OH)(6)Cl(2) at low temperatures (6.0 and 3.5 K respectively) by AC susceptibility measurements. This indicates no long-range magnetic order and a strong spin frustration. The substitution of Zn(2+) by magnetic ions Ni(2+) or Co(2+) effectively enhances the interlayer exchange coupling and changes the ground state of the kagome spin system. PMID:23186651

Li, Yue-sheng; Zhang, Qing-ming

2013-01-16

350

Transport and thermal properties of the solid electrolyte Ag xCu 2-xHgI 4  

NASA Astrophysics Data System (ADS)

Solid solutions Ag xCu 2-xHgI 4 prepared by a solution method were characterised by powder X-ray diffraction, differential scanning calorimetry (DSC) and electrical conductivity. X-ray diffractograms showed tetragonal phases over the whole range expept for 1.14 ? ? 1.30 where a single cubic phase was seen. DSC showed a strong compositional dependence in the order-disorder transition temperature. Temperature variation of electrical conductivity carried out for all compositions showed an increase in conductivity by two orders of magnitude at the transition temperature. The composition x=1.14 having a maximum room temperature conductivity with a minimum transition temperature has the characteristics of an eutectoid of the Ag 2Hgl 4-Cu 2HgI 4 system.

Sukeshini, A. Mary; Hariharan, K.

1991-04-01

351

Spin-driven ferroelectricity in triangular lattice antiferromagnets ACrO2 (A=Cu, Ag, Li, or Na).  

PubMed

The correlation between the dielectric and magnetic properties is investigated on the triangular-lattice antiferromagnets ACrO2 (A=Cu, Ag, Li, or Na) with a 120-degree spiral structure. For the A=Cu and Ag compounds with a delafossite structure, the ferroelectric polarization emerges with a spiral-spin order, implying strong coupling between ferroelectricity and the spiral-spin structure. For the A=Li and Na compounds with an ordered rock salt structure, on the other hand, no spontaneous polarization is discerned, while the clear anomaly in the dielectric constant can be observed upon the transition to the spiral-spin ordered state. This feature can be ascribed to the possible antiferroelectric state induced by the alternate stacking of the Cr-spin sheet with opposite vector spin chirality. PMID:18764497

Seki, S; Onose, Y; Tokura, Y

2008-08-01

352

Fano effect in the angle-integrated valence band photoemission of the noble metals Cu, Ag, and Au  

SciTech Connect

Results of a combined experimental and theoretical investigation on the Fano-effect in the angle-integrated valence band photoemission of the noble metals are presented. In line with the fact that the Fano-effect is caused by the spin-orbit-coupling, the observed spin polarization of the photocurrent was found to be the more pronounced the higher the atomic number of the element investigated. The ratio of the normalized spin difference curves, however, agreed only for Cu and Ag with the ratio of the corresponding spin-orbit coupling strength parameters. The deviation from this expected behavior in the case of Au could be explained by the properties of individual d-p- and d-f-contributions to the total spin difference curves, that were found to be quite different for Au compared to Cu and Ag.

De Nadaie, C.; Brookes, N.B. [European Synchrotron Radiation Facility, Boite Postale 220, 38043 Grenoble Cedex (France); Minar, J.; Ebert, H. [Department Chemie, Phys. Chemie, Universitaet Muenchen, Butenandtstr. 5-13, D-81377 Munich (Germany); Ghiringhelli, G.; Tagliaferri, A. [INFM-Dip. di Fisica, Politecnico di Milano, p. Leonardo da Vinci 32, 20133 Milan (Italy)

2004-10-01

353

The Permian Huangshanxi CuNi deposit in western China: intrusiveextrusive association, ore genesis, and exploration implications  

Microsoft Academic Search

The Permian Huangshanxi CuNi deposit is the second largest magmatic sulfide deposit discovered to date in a major NiCu province\\u000a related to protracted basaltic magmatism in eastern Xinjiang, China. It is hosted by a small maficultramafic intrusion comprised\\u000a predominantly of lherzolites, olivine websterites, gabbronorites, and gabbros. The Huangshanxi intrusion is coeval with Permian\\u000a basalts of tholeiitic and alkaline affinities in

Mingjie Zhang; Chusi Li; Piaoer Fu; Peiqing Hu; Edward M. Ripley

2011-01-01

354

Effects of mine effluent on uptake of Co, Ni, Cu, As, Zn, Cd, Cr and Pb by aquatic macrophytes  

Microsoft Academic Search

Concentrations of Ni, Co, Cu, Pb, Zn, Cd, Cr and As were determined in aquatic sediments, water and macrophytes collected from a fluvial system, contaminated by mine effluents. Myriophyllum verticillatum collected in May below the trace element point source accumulated 169 g\\/g of Ni, 860 g\\/g of Co, 37 g\\/g of Cu, 31 g\\/g of Pb, 92 g\\/g of Zn,

Alena Mudroch; John A. Capobianco

1979-01-01

355

Malleable hypoeutectic Zr-Ni-Cu-Al bulk glassy alloys with tensile plastic elongation at room temperature  

Microsoft Academic Search

A new bulk glassy alloy (BGA) showing macroscopic tensile plastic elongation at room temperature has been developed in the hypoeutectic ZrNiCuAl alloy system. The hypoeutectic ZrNiCuAl BGA shows a high Poisson's ratio, a low Young's modulus, and is highly malleable in compression. It exhibits a Poisson's ratio of 0.39, a Young's modulus of 73 GPa, and a distinct tensile plastic

Y. Yokoyama; K. Fujita; A. R. Yavari; A. Inoue

2009-01-01

356

First-principles study of properties of semi-Heusler (Cu,Ni)MnSb alloys  

NASA Astrophysics Data System (ADS)

Magnetic properties, Curie temperatures, and transport properties of semi-Heusler alloys CuxNi1-xMnSb are calculated as a function of the alloy composition from first-principles. The transition from the ferromagnetic state (NiMnSb) to the antiferromagnetic state (CuMnSb) gives rise to an abrupt change in the concentration dependence of magnetic moments and resistivity at about x = 0.7 while the Curie temperatures decrease monotonically with the Cu-content. Such behaviour can be understood as due to the onset of disorder in orientations of Mn-spins at x = 0.7. A simple account of magnetic disorder as based on the uncompensated disordered local moment picture provides also a good quantitative explanation of available experimental data.

Kudrnovsk, J.; Drchal, V.; Turek, I.

2010-01-01

357

Microstructural characterization of irradiated Fe-Cu-Ni-P model steels  

SciTech Connect

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 spherical or disc shaped copper clusters/precipitates were observed in the neutron irradiated alloys that contained copper. Small spherical phosphorus clusters were observed in the irradiated copper-free alloys, and copper phosphides were observed in a high phosphorus Fe-Cu-Ni-P alloy. None of these clusters/precipitates were observed in the thermally aged materials. The increases in the tensile and yield strengths that were observed after neutron irradiation resulted from these clusters and other lattice defects. 14 refs., 8 figs., 2 tabs.

Miller, M.K.; Hoelzer, D.T.; Ebrahimi, F.; Hawthorne, J.R.; Burke, M.G.

1987-01-01

358

Investigation on compressive behavior of Cu-35Ni-15Al alloy at high temperatures  

NASA Astrophysics Data System (ADS)

Microstructures and mechanical properties of Cu-35Ni-15Al alloy in cast and porous states were studied by scanning electron microscopy and compression tests. The influence of porosity, deformation temperature and loading rate on mechanical properties of the two kinds of alloys was investigated. The results show that the as cast alloy and porous alloys have almost the same phase constitution: Cu rich phase, Ni rich phase and K intermetallics. The yield strength of porous alloys increases continuously with decreasing porosity, the relationship between porosity and yield stress follows Gibson-Ashby equation. With decreasing deformation temperature, the yield strength of as cast alloy and porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend. After compression, the microstructure of as cast alloy is more uniform, and porous alloys are more prone to have localized deformations.

Li, Cong; Chen, Jian; Li, Wei; Hu, Yongle; Ren, Yanjie; Qiu, Wei; He, Jianjun; Chen, Jianlin

2014-08-01

359

Effects of alternating seawater flow and stagnant layup conditions on the general and localized corrosion resistance of CuNi and NiCu alloys in marine service  

SciTech Connect

From time-to-time seawater handling systems are subjected to lay-up which can produce chemical and biological changes, and conceivably alter the corrosion resistance of metals used in piping and other equipment. In the case of reverse osmosis/membrane technology type desalination equipment, sanitizing agents may be introduced after draining. Simulation tests were conducted to determine any effect of a bisulfite sanitizing treatment when used between periods of normal seawater flow. Corresponding tests were conducted with lay-up comprising non-refreshed seawater which ultimately stagnated. Test results for CuNi alloy C71500 indicted that repeated cycling between seawater exposure and bisulfite treatments was detrimental in reducing that alloy`s resistance to general corrosion, and to a lesser degree its crevice corrosion resistance. The typical pitting and crevice corrosion behavior of NiCu alloy N04400, found upon exposure to slowly moving, aerated seawater was neither diminished or accelerated by cyclic lay-up with either stagnant seawater or the candidate bisulfite-containing solution. However, some increase in general corrosion was observed.

Kain, R.M. [LaQue Corrosion Services, Wrightsville Beach, NC (United States); Weber, B.E. [NAWC-Aircraft Div., Patuxent River, MD (United States)

1997-12-01

360

Dynamic mechanical behavior of SnAgCu BGA solder joints determined by fast shear tests and FEM simulations  

Microsoft Academic Search

To allow realistic stress assessments of BGA modules during drop and shock events, the dynamic mechanical behavior of SAC BGA solder joints was determined by a combination of fast shear tests and FEM simulations. The goal has been the development of a validated material model for SnAg1.0Cu0.5 BGA solder joints that accounts for dynamic material hardening and the dependency of

Eberhard Kaulfersch; Sven Rzepka; Vijay Ganeshan; Axel Mller; Bernd Michel

2007-01-01

361

Constitutive Behavior of Mixed Sn-Pb/Sn-3.0Ag-0.5Cu Solder Alloys  

NASA Astrophysics Data System (ADS)

During the transition from Pb-containing solders to Pb-free solders, joints composed of a mixture of Sn-Pb and Sn-Ag-Cu often result from either mixed assemblies or rework. Comprehensive characterization of the mechanical behavior of these mixed solder alloys resulting in a deformationally complete constitutive description is necessary to predict failure of mixed alloy solder joints. Three alloys with 1 wt.%, 5 wt.%, and 20 wt.% Pb were selected so as to represent reasonable ranges of Pb contamination expected from different 63Sn-37Pb components mixed with Sn-3.0Ag-0.5Cu. Creep and displacement-controlled tests were performed on specially designed assemblies at temperatures of 25C, 75C, and 125C using a double lap shear test setup that ensures a nearly homogeneous state of plastic strain at the joint interface. The observed changes in creep and tensile behavior with Pb additions were related to phase equilibria and microstructure differences observed through differential scanning calorimetric and scanning electron microscopic cross-sectional analysis. As Pb content increased, the steady-state creep strain rates increased, and primary creep decreased. Even 1 wt.% Pb addition was sufficient to induce substantially large creep strains relative to the Sn-3.0Ag-0.5Cu alloy. We describe rate-dependent constitutive models for Pb-contaminated Sn-Ag-Cu solder alloys, ranging from the traditional time-hardening creep model to the viscoplastic Anand model. We illustrate the utility of these constitutive models by examining the inelastic response of a chip-scale package (CSP) under thermomechanical loading through finite-element analysis. The models predict that, as Pb content increases, total inelastic dissipation decreases.

Tucker, J. P.; Chan, D. K.; Subbarayan, G.; Handwerker, C. A.

2012-03-01

362

Growth of periodic nano-layers of nano-crystals of Au, Ag, Cu by ion beam  

NASA Technical Reports Server (NTRS)

Multilayered thin films of SiO2/AU+ SiO2/, SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/, were grown by deposition. We have previously shown that MeV ion Bombardment of multi-nano-layers of SiO2/AU+ SiO2/ produces Au nanocrystals in the AU+ SiO2 layers. An increased number of nano-layers followed by MeV ion bombardment produces a wide optical absorption band, of which its FWHM depends on the number of nano-layers of SiO2/AU+ SiO2/. We have successfully repeated this process for nano-layers of SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/. In this work we used 5 MeV Si as the post deposition bombardment ion and monitored the location as well as the optical absorption's FWHM for each layered structure using Optical Absorption Photospectrometry. The concentration and location of the metal nano-crystals were measured by Rutherford Backscattering Spectrometry. We will report on the results obtained for nano-layered structures produced by post deposition bombardment of SiO2/AU+ SiO2/, SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/ layered systems as well as the results obtained from a system containing a periodic combination of SiO2/AU+ SiO2/, SiO2/Ag+ SiO2/, and SiO2/Cu+ SiO2/.

Smith, Cydale C.; Zheng, B.; Muntele, C. I.; Muntele, I. C.; Ila, D.

2005-01-01

363

Structural properties of bulk Pd0.085Cu0.44Ag0.475 ternary alloy  

SciTech Connect

Advanced bulk properties of Pd0.085Cu0.44Ag0.475 are investigated by using MD simulation with Quantum Sutton-Chen semi-empirical inter atomic potential. The properties like enthalpy of mixing, temperature dependence of elastic constants, structure factor, cohesive energy, melting temperature, cell parameters and bulk modulus are calculated. Agreement with experimental values are presented wherever possible. Results have been discussed in detail.

Coruh, A.; Saribek, Y. [Sakarya Ueniversitesi, Fen-Edebiyat Fakueltesi, Fizik Boeluemue, Sakarya (Turkey); Tomak, M. [Ortadogu Teknik Ueniversitesi, Fen-Edebiyat Fakueltesi, Fizik Boeluemue, Ankara (Turkey); Cagin, T. [Texas A and M Univ, Dept. Chem. Engn., College Stn, TX 77845 (United States)

2007-04-23

364

Production of YBa2Cu3O(7-x) thick films on Ag metal substrate controlled by oxygen  

Microsoft Academic Search

YBa2Cu3O(7-x) superconducting thick films were formed on Ag substrate using the sol prepared from pertinent metal alkoxides. The firing conditions which cause incongruent melting and a peritectic reaction in the film were investigated. We call this the IMPERCO (incongruent melting and peritectic reaction controlled by oxygen) method. It has been found that films which undergo both reactions have excellent superconducting

Yoshio Masuda; Kazuo Matsubara; Rikuro Ogawa; Yoshio Kawate

1992-01-01

365

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

Microsoft Academic Search

A chemically-carbonized sorbent was prepared from date palm leaflets by sulphuric acid treatment at 170C. Carbonization took place via the dehydration effect of the hot sulphuric acid producing a carbon with reduction property. Sorption of Cu and Ag from aqueous solution was investigated in terms of pH, contact time, metal concentration and temperature. A peculiar behaviour was found for the

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

2012-01-01

366

Interpretation of neutron magnetic scattering in the Kondo lattices YbPd 2 Si 2 and YbAgCu 4  

Microsoft Academic Search

We present an interpretation of published neutron inelastic scattering spectra in the Kondo lattices YbPd2Si2 and YbAgCu4 obtained in terms of the Anderson impurity model, describing the hybridisation of the 4f Yb electrons with the band electrons, and also including the crystal electric field interaction. In YbPd2Si2, the tetragonal crystal field parameters were determined. In YbAgCu4 the crystal field interaction

G. Polatsek; P. Bonville

1992-01-01

367

The effects of aging precipitation on the recrystallization of CuNiSiCr alloy  

Microsoft Academic Search

The interaction between precipitation and recrystallization and its effect on the properties of the Cu?Ni?Si?Cr alloy during\\u000a aging were discussed. The results show that the deformation results in much more dispersed precipitation of the phases. The\\u000a precipitations have accelerating or retarding effects on the recrysiallization. On the formation and growth of recrystallization,\\u000a the precipitated phases are coarsed or dissolved in

Lei Jingguo; Huang Jinliang; Liu Ping; Jing Xiaotian; Zhao Dongmei; Zhi Xiao

2005-01-01

368

Melonite group minerals and other tellurides from three CuNiPGE prospects, Eastern Desert, Egypt  

Microsoft Academic Search

Melonite group minerals and other tellurides are described from three CuNiPGE prospects in the Eastern Desert of Egypt: Gabbro Akarem, Genina Gharbia and Abu Swayel. The prospects are hosted in late Precambrian maficultramafic rocks and have different geologic histories. The Gabbro Akarem prospect is hosted in dunite pipes where net-textured and massive sulfides are associated with spinel and Cr-magnetite. Michenerite,

Hassan M. Helmy

2005-01-01

369

Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn  

SciTech Connect

This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C{sub 3}S, C{sub 2}S, C{sub 3}A and C{sub 4}AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C{sub 3}S, 18% C{sub 2}S, 8% C{sub 3}A and 8% C{sub 4}AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO{sub 2}) and Sn reacted with lime to form a calcium stannate (Ca{sub 2}SnO{sub 4}). Cu changed the crystallisation process and affected therefore the formation of C{sub 3}S. Indeed a high content of Cu in clinker led to the decomposition of C{sub 3}S into C{sub 2}S and of free lime. Zn, in turn, affected the formation of C{sub 3}A. Ca{sub 6}Zn{sub 3}Al{sub 4}O{sub 15} was formed whilst a tremendous reduction of C{sub 3}A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

Gineys, N., E-mail: nathalie.gineys@mines-douai.fr [Univ. Lille Nord de France, F-59000 Lille (France); EMDouai, LGCgE-MPE-GCE, F-59508 Douai (France); Aouad, G. [Univ. Lille Nord de France, F-59000 Lille (France); EMDouai, LGCgE-MPE-GCE, F-59508 Douai (France); Sorrentino, F. [Mineral Research Processing Company, 69330 Meyzieu (France); Damidot, D. [Univ. Lille Nord de France, F-59000 Lille (France); EMDouai, LGCgE-MPE-GCE, F-59508 Douai (France)

2011-11-15

370

Quantum-well states and spin polarization in thin Ni films on Cu(0 0 1)  

NASA Astrophysics Data System (ADS)

The unoccupied quantum-well states in thin Ni films on Cu(0 0 1) have been studied by spin- and angle-resolved inverse photoemission. Three quantum-well features are clearly resolved with exchange splittings of up to 70 meV. As a function of the wave vector parallel to the surface, the quantum-well states follow the corresponding sp band dispersion and evolve into surface resonances upon approaching the band-gap boundary.

Renken, V.; Yu, D. H.; Donath, M.

2007-12-01

371

Low energy ($p,?$) reactions in Ni and Cu nuclei using microscopic optical model  

E-print Network

Radiative capture reactions for low energy protons have been theoretically studied for Ni and Cu isotopes using the microscopic optical model. The optical potential has been obtained in the folding model using different microscopic interactions with the nuclear densities from Relativistic Mean Field calculations. The calculated total cross sections as well as the cross sections for individually low lying levels have been compared with measurements involving stable nuclear targets. Rates for the rapid proton capture process have been evaluated for astrophysically important reactions.

G. Gangopadhyay

2010-08-05

372

RECOVERY OF Co, Ni, AND Cu FROM THE TAILINGS OF DIVRIGI IRON ORE CONCENTRATOR  

Microsoft Academic Search

In the Sivas-Divri?i Iron Ore Concentrator, 600,000t of tailings are discarded annually. There are already 1 million t of tailings deposited in ponds from the previous production activities. The presence of Co, Ni, and Cu in the tailings makes the beneficiation of those tailings attractive. In the experimental work, sulphide concentrates were produced from these two types of tailings by

A. A. Sirkeci; A. Gl; G. Bulut; F. Arslan; G. Onal; A. E. Yuce

2006-01-01

373

Structure and energetics of high index Fe, Al, Cu and Ni surfaces using equivalent crystal theory  

NASA Technical Reports Server (NTRS)

Equivalent crystal theory (ECT) is applied to the study of multilayer relaxations and surface energies of high-index faces of Fe, Al, Ni, and Cu. Changes in interplanar spacing as well as registry of planes close to the surface and the ensuing surface energies changes are discussed in reference to available experimental data and other theoretical calculations. Since ECT is a semiempirical method, the dependence of the results on the variation of the input used was investigated.

Rodriguez, Agustin M.; Bozzolo, Guillermo; Ferrante, John

1993-01-01

374

First stage of the structural evolution of austenite in Cu-Al-Ni shape memory alloys  

Microsoft Academic Search

Two shape memory Cu-Al-Ni alloys, a polycrystal and a single crystal, exhibiting a martensitic transformation close to 130 ^{circ}C (in the as-quenched state) have been studied. Specimens have been quenched after heat treatment at 850 ^{circ}C. The structural evolutions of the high temperature phase (austenite) have been studied for thermal treatments performed below 200 ^{circ}C. Investigations have been carried out

V. Pelosin; M. Gerland; A. Rivire

2001-01-01

375

Reversible colour change in Cu-Al-Ni alloy ribbon associated with phase transformation  

Microsoft Academic Search

The colour change behaviour and its relation to phase transformation of Cu-14 wt% Al-4 wt% Ni alloy ribbon produced by the twin-roller type melt-quenching method were investigated by spectral reflectivity and X-ray diffraction, respectively. This ribbon turns copper-coloured around room temperature on quenching it from a temperature above 1020 K, and turns gold-coloured on ageing it between 670 and 970

T. Minemura; H. Andoh; I. Ikuta

1987-01-01

376

Bulk Properties of Ni3Al(gamma`) With Cu and Au Additions  

SciTech Connect

The BFS method for alloys is applied to the study of 200 alloys obtained from adding Cu and Au impurities to a Ni3Al matrix. The authors analyze the trends in the bulk properties of these alloys (heat of formation, lattice parameter, and bulk modulus) and detect specific alloy compositions for which these quantities have particular values. A detailed analysis of the atomic interactions that lead to the preferred ordering patterns is presented.

Bozzolo, G.; Ferrante, J.

1995-04-01

377

Duplex Oxide Formation during Transient Oxidation of Cu-5%Ni(001) Investigated by In situ UHV-TEM and XPS  

SciTech Connect

The transient oxidation stage of a model metal alloy thin film was characterized with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and analytic high-resolution TEM. We observed the formations of nanosized NiO and Cu{sub 2}O islands when Cu-5a5%Ni(100) was exposed to oxygen partial pressure, pO{sub 2} = 1 x 10{sup -4} Torr and various temperatures in situ. At 350 C epitaxial Cu{sub 2}O islands formed initially and then NiO islands appeared on the surface of the Cu{sub 2}O island, whereas at 750 C NiO appeared first. XPS and TEM was used to reveal a sequential formation of NiO and then Cu{sub 2}O islands at 550 C. The temperature-dependant oxide selection may be due to an increase of the diffusivity of Ni in Cu with increasing temperature.

Yang, J.C.; Starr, D.; Kang, Y.; Luo, L.; Tong, X.; Zhou, G.

2012-05-20

378

Concentration-dependent oxygen diffusion in Tl1Ba2Ca2Cu3 and Ag1Tl2Ba2Ca2Cu3 superconductor precursor alloys  

NASA Astrophysics Data System (ADS)

To study the growth mechanism in growing superconducting thin films by the liquid-gas-solidification process, oxygen diffusivities in liquid Tl1Ba2Ca2Cu3 and Ag1Tl1Ba2Ca2Cu3 precursor alloys were measured by a modified coulometric titration method. The diffusivities of oxygen are very high of the order of 10-4 to 10-3 cm2/s. The logarithm of oxygen diffusivities is found to be reciprocally proportional to the logarithm of oxygen concentrations. This concentration-dependent oxygen diffusivity phenomenon has not been observed in many metallic liquids investigated previously. An interstitial diffusion mechanism may contribute to the fast oxygen diffusion. The strong bonds between Ba and O atoms are proposed to enhance the configurational structural order and hence to quicken the oxygen diffusion that varies the oxygen concentration in Tl1Ba2Ca2Cu3 and Ag1Tl1Ba2Ca2Cu3 superconductor precursor liquids.

Chou, H.; Chow, T. C.; Chen, H. S.

1995-09-01

379

THE ELECTRONIC STRUCTURE OF AG/CU(100) SURFACE ALLOYS STUDIES BY AUGER-PHOTOELECTRON COINCIDENCE SPECTROSCOPY.  

SciTech Connect

We have measured the Ag and Pd M{sub 5}VV Auger spectrum in coincidence with Ag and Pd 4d{sub 5/2} photoelectrons for the Ag/Cu(100) and Pd/Cu(100) systems, respectively, as a function of admetal coverage. These systems form surface alloys (i.e. random substitutional alloys in the first atomic layer) for impurity concentrations in the 0.1 monolayer range. For these systems, the centroid of the impurity 4d levels is expected to shift away from the Fermi level by {approx}1 eV [Ruban et al., Journal of Molecular Catalysis. A 115 (1997) 421], an effect that should be easily seen in coincidence core-valence-valence Auger spectra. We find that the impurity Auger spectra of both systems shift in a manner that is consistent with d-band moving away from EF. However, the shift for Pd is considerably smaller than expected, and a shift almost absent for Ag. The disagreement between theory and experiment is most likely caused by the neglect of lattice relaxations in the calculations.

ARENA,D.A.; BARTYNSKI,R.A.; HULBERT,S.L.

2001-10-08

380

Nanocomposite Formation in Zr-Al-Cu-Ni-Fe Amorphous Alloys by Mechanically Assisted Nitriding  

SciTech Connect

Zr-Al-Cu-Ni-Fe belongs to the best glass forming systems known. These glasses present a high thermal stability and are suitable as precursor material for nanocomposites containing a variety of particles. At this respect, the presence of a second phase embedded in the amorphous matrix improves their mechanical properties. Ball milling has already demonstrated to be a valuable processing route for producing amorphous matrix nanocomposites, allowing by passing most of the limitations inherent to the casting techniques. In this work we present results on the formation, structure and thermal stability of nanocrystalline nitride particles dispersed in a Zr-Cu-Al-Ni-Fe amorphous matrix. The nitride particles were obtained by high-energy ball milling of Zr64Al7Cu17Ni10Fe2 amorphous ribbons in nitrogen atmosphere. The resulting nanocomposite structure was studied by Moessbauer spectroscopy and x-ray diffraction. Their thermal behavior was analyzed by differential scanning calorimetry, showing an increase in the thermal stability of the amorphous matrix by the composite formation.

Bab, M.A. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC67, 1900 La Plata (Argentina); Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas, Fac. de Ciencias Exactas, Universidad Nacional de La Plata, Sucursal 4 CC16, 1900 La Plata (Argentina); Damonte, L.C.; Mendoza-Zelis, L.A. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC67, 1900 La Plata (Argentina)

2005-04-26

381

Magnetic refrigeration capabilities of magnetocaloric Ni2Mn:75Cu:25Ga  

NASA Astrophysics Data System (ADS)

Doping-driven competition between energetically similar ground states leads to many exciting materials phenomena such as the emergence of high-Tc superconductivity, diluted magnetic semiconductors, and colossal magnetoresistance. Doped Ni2MnGa Heusler alloy, which is a multifunctional ferromagnetic alloy with various exotic physical properties demonstrates this notion of rich phenomenology via modified ground spin states. Adopting this generic concept, here we will present a novel doped Ni2Mn.75Cu.25Ga alloy that offers unprecedented co-existence of the magnetocaloric effect and fully controlled ferromagnetism at room temperature. Application of site engineering enables us to manipulate the ground spin state that leads to the decrease in magnetic transition temperature and also increases the delocalization of the Mn magnetism. SQUID magnetometery suggests that Cu doping enhances the saturation magnetization, coercive field and clarity of magnetic hysteresis loops. By exploiting x-ray absorption techniques and measuring element specific magnetic hysteresis loops, here we will describe the microscopic origin of enhnaced magnetocaloric properties and d-d interaction driven charge transfer effects in Ni2Mn.75Cu.25Ga

Mishra, S. K.; Jenkins, C. A.; Dubenko, I.; Samanta, T.; Ali, N.; Roy, S.

2013-03-01

382

Effect of thione primers on adhesive bonding between an indirect composite material and Ag-Pd-Cu-Au alloy.  

PubMed

The current study evaluated the effect of primers on the shear bond strength of an indirect composite material joined to a silverpalladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell). Disk specimens were cast from the alloy and were air-abraded with alumina. Eight metal primers were applied to the alloy surface. A light-polymerized indirect composite material (Solidex) was bonded to the alloy. Shear bond strength was determined both before and after the application of thermocycling. Two groups primed with Metaltite (thione) and M. L. Primer (sulfide) showed the greatest post-thermocycling bond strength (8.8 and 6.5 MPa). The results of the X-ray photoelectron spectroscopic (XPS) analysis suggested that the thione monomer (MTU-6) in the Metaltite primer was strongly adsorbed onto the Ag-Pd-Cu-Au alloy surface even after repeated cleaning with acetone. The application of either the thione (MTU-6) or sulfide primer is effective for enhancing the bonding between a composite material and Ag-Pd-Cu-Au alloy. PMID:25273049

Imai, Hideyuki; Koizumi, Hiroyasu; Shimoe, Saiji; Hirata, Isao; Matsumura, Hideo; Nikawa, Hiroki

2014-01-01

383

Ag{sub 2}CuMnO{sub 4}: A new silver copper oxide with delafossite structure  

SciTech Connect

The use of hydrothermal methods has allowed the synthesis of a new silver copper mixed oxide, Ag{sub 2}CuMnO{sub 4}, the first example of a quaternary oxide containing both elements. It crystallizes with the delafossite 3R structure, thus being the first delafossite to contain both Ag and Cu. Synthesis conditions affect the final particle size (30-500nm). Powder X-ray diffraction Rietveld refinement indicates a trigonal structure (R3-bar m) and cell parameters a=2.99991A and c=18.428A, where Cu and Mn are disordered within the octahedral B positions in the plane and linearly coordinated Ag occupies de A position between layers. X-ray absorption near edge spectroscopy (XANES) for copper and manganese, and XPS for silver evidence +2, +4, and +1 oxidation states. The microstructure consists of layered parts that may form large twins showing 5nm nanodomains. Finally, magnetic measurements reveal the existence of ferromagnetic coupling yielding in-plane moments that align antiferromagnetically at lower temperatures. The singularity of the new phase resides on the fact that is an example of a bidimensional arrangement of silver and copper in an oxide that also shows clear bidimensionality in its physical properties. That is of special relevance to the field of high T{sub c} superconducting oxides, while the ferromagnetic coupling in a bidimensional system deserves itself special attention.

Munoz-Rojas, David [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Subias, Gloria [Instituto de Ciencia de Materiales de Aragon, CSIC-Universidad de Zaragoza Pza. San Francisco s/n, 50009-Zaragoza (Spain); Oro-Sole, Judith [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Fraxedas, Jordi [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Martinez, Benjamin [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Casas-Cabanas, Montse [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Canales-Vazquez, Jesus [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain); Gonzalez-Calbet, Jose [UCM, Departamento de Quimica Inorganica, Facultad de Quimicas, Universidad Complutense, 28040 Madrid (Spain); Garcia-Gonzalez, Ester [UCM, Departamento de Quimica Inorganica, Facultad de Quimicas, Universidad Complutense, 28040 Madrid (Spain); Walton, Richard I. [Department of Chemistry, University of Warwick, Coventry CV4 7AL (United Kingdom); Casan-Pastor, Nieves [Institut de Ciencia de Materials de Barcelona, CSIC, Campus U.A.B., Bellaterra (Spain)]. E-mail: nieves@icmab.es

2006-12-15

384

Regulation of Cu(I)/Ag(I) efflux genes in Escherichia coli by the sensor kinase CusS  

PubMed Central

Two-component systems are widely used by bacteria to mediate adaptive responses to a variety of environmental stimuli. The CusR/CusS two-component system in Escherichia coli induces expression of genes involved in metal efflux under conditions of elevated Cu(I) and Ag(I) concentrations. As seen in most prototypical two-component systems, signal recognition and transmission is expected to occur by ligand binding in the periplasmic sensor domain of the histidine kinase CusS. Although discussed in the extant literature, little experimental evidence is available to establish the role of CusS in metal homeostasis. In this study, we show that the cusS gene is required for Cu(I) and Ag(I) resistance in E. coli and that CusS is linked to the expression of the cusCFBA genes. These results show a metal dependent mechanism of CusS activation and suggest an absolute requirement for CusS in Cu(I) and Ag(I)-dependent upregulation of cusCFBA expression in E. coli. PMID:22348296

Gudipaty, Swapna Aravind; Larsen, Andrew S.; Rensing, Christopher; McEvoy, Megan M.

2012-01-01

385

High frequency magnetic behavior through the magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered ferromagnetic thin films  

NASA Astrophysics Data System (ADS)

We studied the dynamics of magnetization through an investigation of the magnetoimpedance effect in CoFeB/(Ta, Ag, Cu) multilayered thin films grown by magnetron sputtering. Impedance measurements were analyzed in terms of the mechanisms responsible for their variations at different frequency intervals and the magnetic and structural properties of the multilayers. Analysis of the mechanisms responsible for magnetoimpedance according to frequency and external magnetic field showed that for the CoFeB/Cu multilayer, ferromagnetic resonance (FMR) contributes significantly to the magnetoimpedance effect at frequencies close to 470 MHz. This frequency is low when compared to the results obtained for CoFeB/Ta and CoFeB/Ag multilayers and is a result of the anisotropy distribution and non-formation of regular bilayers in this sample. The MImax values occurred at different frequencies according to the used non-magnetic metal. Variations between 25% and 30% were seen for a localized frequency band, as in the case of CoFeB/Ta and CoFeB/Ag, as well as for a wide frequency range, in the case of CoFeB/Cu.

Marques, M. S.; Mori, T. J. A.; Schelp, L. F.; Chesman, C.; Bohn, F.; Corra, M. A.

2012-01-01

386

Effects Of Pb, Cu, Sb, In and Ag Contamination on the Proliferation of Soil Bacterial Colonies, Soil Dehydrogenase Activity, and Phospholipid Fatty Acid Profiles of Soil Microbial Communities  

Microsoft Academic Search

Because of concerns about the toxicity of lead (Pb), the use of antimony (Sb), indium (In), silver (Ag), and other heavy metals are on the increase as its replacement in many kinds of industrial products, particularly in solders. In the present study, effects of Pb, Cu, Sb, In, and Ag contamination on bacterial growth inhibition in PTYG (peptone, tryptone, yeast

Tomoyoshi Murata; Masami Kanao-Koshikawa; Takejiro Takamatsu

2005-01-01

387

The Evolution of Defects in Deformed Cu-Ni-Si Alloys during Isochronal Annealing Studied by Positron Annihilation  

NASA Astrophysics Data System (ADS)

The effect of isochronal annealing on the deformation-induced defects in pure Cu and Cu-Ni-Si alloys is studied by positron annihilation spectroscopy. For the cold-rolled Cu, annealing up to 900C causes a gradual recovery of the deformation-induced defects and monotonous decrease of the hardness. This indicates that its hardening is mainly related with defects such as dislocations. However, for the hot-rolled and quenched Cu-Ni-Si alloy, although there is a partial recovery of defects after annealing below 500C, formation of additional defects is observed after annealing above 500C. The hardness of Cu-Ni-Si alloy has a maximum value after annealing at 500C, which suggests that the hardening of Cu-Ni-Si alloy is not due to defects, but primarily due to the precipitation formed during annealing. Further annealing of the Cu-Ni-Si alloy above 500C results in over-aging effect and the precipitates lose coherence with the host matrix, which leads to positron trapping by vacancy clusters in the incoherent interface region.

Qi, Ning; Jia, Yan-Lin; Liu, Hui-Qun; Yi, Dan-Qing; Chen, Zhi-Quan

2012-12-01

388

Electronic structure and conductivity of nanocomposite metal (Au,Ag,Cu,Mo)-containing amorphous carbon films  

SciTech Connect

In this work, we study the influence of the incorporation of different metals (Me = Au, Ag, Cu, Mo) on the electronic structure of amorphous carbon (a-C:Me) films. The films were produced at room temperature using a novel pulsed dual-cathode arc deposition technique. Compositional analysis was performed with secondary neutral mass spectroscopy whereas X-ray diffraction was used to identify the formation of metal nanoclusters in the carbon matrix. The metal content incorporated in the nanocomposite films induces a drastic increase in the conductivity, in parallel with a decrease in the band gap corrected from Urbach energy. The electronic structure as a function of the Me content has been monitored by x-ray absorption near edge structure (XANES) at the C K-edge. XANES showed that the C host matrix has a dominant graphitic character and that it is not affected significantly by the incorporation of metal impurities, except for the case of Mo, where the modifications in the lineshape spectra indicated the formation of a carbide phase. Subtle modifications of the spectral lineshape are discussed in terms of nanocomposite formation.

Endrino, Jose L.; Horwat, David; Gago, Raul; Andersson, Joakim; Liu, Y.S.; Guo, Jinghua; Anders, Andre

2008-05-14

389

Fabrication of potential NiMoP diffusion barrier/seed layers for Cu interconnects via electroless deposition  

NASA Astrophysics Data System (ADS)

Potential NiMoP barrier/seed layers for Cu interconnects have been successfully formed by electroless deposition on SiO2. Four different wet processes were attempted to activate the surface before electroless deposition. Material properties including the crystal structure, deposition rate, composition, and electrical resistivity of NiMoP layers were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), Auger electron spectroscopy, x-ray diffraction (XRD), four-point probe, and surface profilometry (Alpha-step). In this study, different compositions of NiMoP films have been obtained. Ni89Mo2P9 with nanocrystalline structure has the highest resistivity due to enriched P content, while Ni88Mo9P3 has the lowest value among the compositions considered in this study. The seed layer and the barrier layer functions of NiMoP were verified by direct Cu electrodeposition and secondary ion mass spectroscopy (SIMS).

Wu, Y.; Wan, C. C.; Wang, Y. Y.

2005-05-01

390

The nature of chemisorbed oxygen on Ni(100) and Cu(100)  

NASA Technical Reports Server (NTRS)

Model calculations indicate two low-lying states for the interaction of O with Ni and Cu(100). The oxide state is approximately 1 eV more stable and its R(perpendicular) for Ni(100) is consistent with the experimental value for Ni(100), indicating only one type of stable chemisorption bond. This agrees with XPS (X-ray photoemission spectroscopy) and EXAFS (extended X-ray absorption fine structure) data for the observed LEED (low energy electron diffraction) structures. Interpretations of EELS (electron energy loss spectroscopy) data in terms of a radical state forthe p(2x2) and the oxide state for the c(2x2) structure must be seriously questioned.

Bauschlicher, C. W., Jr.; Walch, S. P.; Bagus, P. S.; Brundle, C. R.

1984-01-01

391

Microstructure, optical and FTIR studies of Ni, Cu co-doped ZnO nanoparticles by co-precipitation method  

NASA Astrophysics Data System (ADS)

Zn0.96-xCu0.04NixO (0 ? x ? 0.04) nanoparticles were synthesized by co-precipitation method. The X-ray diffraction pattern showed the crystalline nature of prepared nanoparticles with hexagonal wurtzite structure. The average crystal size is decreased from 27 to 22.7 nm when Ni concentration is increased from 0% to 2% due to the suppression of nucleation and subsequent growth of ZnO by Ni-doping. The increased crystal size from 22.7 to 25.8 nm (?D ? 3.1 nm) by Ni-doping from 2% to 4% is due to the creation of distortion centers and Zn/Ni interstitials. The cell parameters and volume of the lattice showed solubility limit at 2% of Ni doping. The energy dispersive X-ray spectra confirmed the presence of Cu and Ni in Zn-O. The optical absorption spectra showed that the absorption was increased up to Ni = 2% due to the creation of carrier concentration by Ni-doping and decreased beyond 2% due to the presence of more defects and interstitials in the Zn-Ni-Cu-O lattice. The observed red shift of energy gap from 3.65 eV (Ni = 0%) to 3.59 eV (Ni = 2%, ?Eg ? 0.06 eV) is explained by sp-d exchange interactions between the band electrons and the localized d-electrons of the Ni2+ ions. The blue shift of energy gap from 3.59 eV (Ni = 2%) to 3.67 eV (Ni = 4%, ?Eg ? 0.08 eV) is explained by Burstein-Moss effect. Presence of chemical bonding was confirmed by FTIR spectra.

Ashokkumar, M.; Muthukumaran, S.

2014-11-01

392

Phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy  

E-print Network

The phase equilibria of an Al0.5CrFeCoNiCu High Entropy Alloy has been studied following 1000 h exposures at 700, 850 and 1000 C. Above1000 C, the material comprised of two fcc solid solutions, one a multi-element phase and the other a Cu rich...

Jones, N. G.; Frezza, A.; Stone, H. J.

2014-07-27

393

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

E-print Network

CuZn Ferrites Behzad Ahmadi,1, a) Karim Zehani,1 Martino LoBue,1 Vincent Loyau,1 and Frederic Mazaleyrat1 SATIE spark plasma sintering technique, a family of very fine grained, fully dense NiCuZn ferrites have been produced which show constant permeability up to several 10 MHz. These Ferrites can be used for filtering

Boyer, Edmond

394

Exchange coupling energy determined by ferromagnetic resonance in 80Ni?Fe/Cu multilayer films  

NASA Astrophysics Data System (ADS)

Ferromagnetic resonance (FMR) experiments were carried out for [ 80Ni?Fe(60 )/Cu (d Cu)] N, ( dCu = 10-12, N = 2-5) multilayer films fabricated by a sputtering method. The main resonance peak had a broad shoulder located on the higher magnetic field side. Namely, the exchange energy between the magnetic layers was antiferromagnetic. In order to estimate the exchange energy, the FMR absorption spectrum was calculated using the Landau-Lifshitz equation of motion. The calculation model was improved so that we were able to analyze the spectrum for a multilayer with N magnetic layers. The exchange energy obtained from FMR analysis was compared with that estimated from the saturation magnetic field in the magnetoresistance (MR) curve. The positions and the intensity ratio of the resonance peaks were dependent on merely the exchange energy but not on the number of layers. The MR ratio was roughly proportional to the exchange energy.

Ando, Y.; Koizumi, H.; Miyazaki, T.

1997-02-01

395

Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil  

NASA Astrophysics Data System (ADS)

Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

2014-10-01

396

Electroless Ni-Cu-P/nano-graphite composite coatings for bipolar plates of proton exchange membrane fuel cells  

NASA Astrophysics Data System (ADS)

This study evaluates the effects of an electroless Ni-Cu-P/nano-graphite composite coating on the surface characteristics of anodized 5083 aluminum alloy, including electrical resistivity, corrosion resistance of the alloy in a simulated solution of 0.5M H2SO4+2ppm NaF in polymer electrolyte membrane fuel cells (PEMFCs). The co-deposition and adhesion of the composite coatings on a 5083 substrate are enhanced by an anodizing process. The electroless Ni-Cu-P plating solution is prepared by adding different CuSO45H2O concentrations into the electroless Ni-P plating solution and adding nano-graphite (15-40nm) particles to form the Ni-Cu-P/nano-graphite composite coatings. Experimental results indicate that the electroless Ni-Cu-P/nano-graphite composite coating enhances the hardness, conductivity, corrosion resistance of the 5083 substrate in the corrosive solution. The anodizing treatment enhances the electroless composite coatings by providing better uniformity, density, and adhesion compared to substrate without anodizing treatment. The electroless Ni-Cu-P/nano-graphite composite coating deposited on the optimal anodized 5083 substrate at a low CuSO45H2O concentration of 0.25gl-1 with 20gl-1 nano-graphite added have the best surface structure, highest hardness, electrical conductivity and corrosion resistance. Therefore, this novel electroless Ni-Cu-P/nano-graphite composite-coated 5083 aluminum alloy has potential applications in bipolar plates of PEM fuel cells.

Lee, Cheng-Kuo

2012-12-01

397

Partial structure of Pd42:5Ni7:5Cu30P20 bulk metallic glass  

NASA Astrophysics Data System (ADS)

In order to study local structure in Pd42.5Ni7.5Cu30P20 excellent bulk metallic glass-former, an anomalous x-ray scattering (AXS) experiment was performed at energies close to the Pd, Ni and Cu K absorption edges together with the reference Pd40Ni40P20 and Pd40Cu40P20 glasses at the beamline BM02 of the ESRF. The differential structure factors, ?iS(Q), were obtained with a good statistical quality. A small shoulder observed at about 19 nm-1 in S(Q) becomes prominent in ?PdS(Q), indicating a Pd-Pd atomic correlation of 0.32 nm. This pre-shoulder was not observed in Pd40Ni40P20 bulk glass having a slightly worse critical-cooling-rate, but in Pd40Cu40P20 glass ribbon available by only ultrafast quenching. It is suggested that covalently bonded Pd-P-Pd connection with an almost right bond angle would be formed by replacing the Ni with the Cu atoms. From the obtaining differential pair distribution function around the Pd K edge, ?Pdg(r), the first peak position in Pd42.5Ni7.5Cu30P20 shows a longest atomic distance among the glasses and the width of the first peak is slightly narrower than that in Pd40Cu40P20. Thus, a more uniform atomic arrangement around Pd atoms with a loose packing, i.e., a longer and uniform Pd sublattice, is expected for Pd42.5Ni7.5Cu30P20 compared to the other two reference glasses.

Hosokawa, S.; Brar, J.-F.; Boudet, N.; Ichitsubo, T.; Matsubara, E.; Nishiyama, N.

2009-01-01

398

Optical, Raman and vibrational properties of closed shell Ag-Cu clusters from density functional theory: The influence of the atomic structure, exchange-correlation approximations and pseudopotentials  

NASA Astrophysics Data System (ADS)

The optical, Raman and vibrational properties of 8-atom closed shell Ag-Cu clusters are systemically investigated within the framework of density functional theory with eight kinds of exchange-correction functionals: generalized gradient approximation (GGA) and local-density approximation (LDA), as well as DFT-based semi-core pseudopotential (Dspp) and all-electron (AE). Results reveal that the optical spectra of pure Ag8 and Cu8 clusters are in excellent agreement with the experiments; moreover, both tetracapped tetrahedron (TcTd) and monocapped pentagonal bipyramid (McPb) contribute to the experimental absorption spectra. For the optical, Raman and vibrational spectra of Ag-Cu clusters, the differences between TcTd and McPb, that are intensity and position energies of the strongest peaks as well as the appearance of additional peaks, are visible obviously. Exchange-correction functionals have little effect on the optical, Raman and vibrational spectra of Ag-Cu clusters. On comparing the spectra using GGA with those using LDA, the position energies of the corresponding peaks are lower, which shows obviously in the rich Cu atoms' clusters. However, pseudopotentials have some effects on them. The intensities of absorption peaks for Ag-Cu clusters using Dspp are weaker than those using AE; in particular, this effect of rich Ag atom clusters is shown obviously. The intensities of Raman peaks for Ag-Cu clusters using Dspp are larger than those using AE. An additional peak appears in the vibrational spectra of TcTd using Dspp but not in the ones using AE for AgnCu8-n (n=2-8) clusters. The vibrational and Raman spectroscopy may be helpful in determining cluster size and structure.

Li, Weiyin; Chen, Fuyi

2014-06-01

399

Real-time wetting dynamics and interfacial chemistry in low-melting 57Bi-42Sn-1Ag solder paste on Ni-Au  

NASA Astrophysics Data System (ADS)

We report the observation of real-time, in situ, wetting and spreading dynamics for 57Bi-42Sn-1Ag solder paste on Ni-Au surfaces during melting in a scanning electron microscope. The 57Bi-42Sn-1Ag is a low melting (139 C) Pb-free eutectic alloy currently under consideration by automobile manufacturers for use in instrument displays. We find that, while there is excellent wetting of 57Bi-42Sn-1Ag solder paste on Ni-Au, there is almost no spreading. A large amount of Bi segregates to the surface of 57Bi-42Sn-1Ag solder balls during the sintering process. At melting, excessive flux outgassing and pooling are observed, several melted solder balls float on top of the flux, and substantial elemental segregation occurs during the first minutes of wetting. Neither Ni nor Au fully intermixes throughout the alloy at the interface within seconds of wetting. Bi does not move outward with the expanding alloy front. This combination of detrimental effects forms voids in the solder paste, contributes to low reliability of solder joints, and complicates the materials science at the solder-substrate interface as shown by Auger electron spectroscopy. Reliability work in progress (3000 cycles) shows that 57Bi-42Sn-1Ag on Ni-Au is less reliable than eutectic Sn-37Pb on Ni-Au for 2512 chip resistors cycled from -40 to 125 C.

Bozack, M. J.

2004-11-01

400

Synthesis and spectroscopic characterization of complexes of Cr(III), Cr(VI), Cu(III), Zn(II), Mo(VI), Pd(II), Ag(III), Au(III) and W(VI) with telluric acid  

NASA Astrophysics Data System (ADS)

New preparative methods are reported for telluric acid complexes, Na5[Cr(TeO4(OH)2)2(H2O)2], Na6[Zn(TeO4(OH)2)2(H2O)2], Na6[Pd(TeO4(OH)2)2], Na5[M(TeO4(OH)2)2] (M(III) = Cu, Ag, Au) and KTeM6'O (M'(VI) = Cr, Mo, W). Their structures were characterized on the basis of spectroscopic, crystallographic, magnetic and thermal measurements. The deprotonation constants of telluric acid and the stability constants of the Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) complexes were determined by pH-metric measurements.

Butler, Ian S.; El-Sherbeny, Heba Allah M.; Kenawy, Ibrahim M.; Mostafa, Sahar I.

2013-03-01

401

Electronic Structure and Thermoelectric Properties of the Delafossite-Type Oxides CuFe 1 x Ni x O 2  

Microsoft Academic Search

In this study, we investigated the chemical composition and electronic structure of the delafossite-type oxides CuFeO2 (CFO) and CuFe0.98Ni0.02O2 (CFNO). The hole carrier density in the Cu and FeO2 layers of CFNO was found to be different from that of CFO, leading to the enhancement of electrical conductivity by Ni substitution.\\u000a In addition, thermoelectric properties were found to be affected

T. Nozaki; K. Hayashi; T. Kajitani

2009-01-01

402

Trends in negative thermal expansion behavior for AMO{sub 2} (A=Cu or Ag; M=Al, Sc, In, or La) compounds with the delafossite structure  

SciTech Connect

Powder neutron diffraction data were obtained from 30 to 600K for CuAlO{sub 2}, CuInO{sub 2}, CuLaO{sub 2}, 2H CuScO{sub 2}, 3R CuScO{sub 2}, and AgInO{sub 2}. Rietveld refinements of these data showed negative thermal expansion (NTE) of the O-Cu-O linkage in all cases. This behavior was especially strong for CuLaO{sub 2} and CuScO{sub 2}, where it persisted up to our maximum measuring temperature of 600K. This NTE in turn caused NTE of the c cell edge, which was moderated by the positive thermal expansion of the M-O bonds. The NTE behavior increases in the CuMO{sub 2} series as the size of M increases. No NTE behavior was found for the O-Ag-O linkage in AgInO{sub 2}; nonetheless, this compound did exhibit NTE for the c cell edge at low temperatures. For CuLaO{sub 2} there is NTE for both the a and c cell edges at low temperatures. Structural trends for compounds with the delafossite structure are discussed with respect to both composition and temperature.

Li, J. [Department of Chemistry, Oregon State University, Room 153, Gilbert Hall, Corvallis, OR 97331-4003 (United States); Sleight, A.W. [Department of Chemistry, Oregon State University, Room 153, Gilbert Hall, Corvallis, OR 97331-4003 (United States)]. E-mail: arthur.sleight@orst.edu; Jones, C.Y. [NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8562, Gaithersburg, MD 20899-8562 (United States); Toby, B.H. [NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8562, Gaithersburg, MD 20899-8562 (United States)

2005-01-15

403

Hydrogen production via supercritical water gasification of bagasse using Ni-Cu/?-Al2O3 nano-catalysts.  

PubMed

Biomass gasification in supercritical water media is a promising method for the production of hydrogen. In this research, Cu-promoted Ni/?-Al2O3 nano-catalysts were prepared with 2.5- 30?wt% Ni and 0.6- 7.5?wt% Cu loadings via the microemulsion method. Nano-catalysts were characterized by inductively coupled plasma (ICP), Brunauer Emmett Teller (BET) technique, X-Ray Diffraction (XRD), H2 chemisorption and Transmission Electron Microscopy (TEM) technique, as well as Carbon-Hydrogen-Nitrogen-Sulfur (CHNS) analysis was carried out for elemental analysis of bagasse. Nano-catalysts were assessed in a batch micro-reactor under 400C and 240?bar. The microemulsion method decreased the catalyst average particle size and increased the percentage dispersion and reduction of the catalysts. The total gas yield increased with an increase in Ni and Cu loadings up to 20?wt% Ni and 5?wt% Cu and then started to decrease. Using the microemulsion technique for the preparation of Ni-Cu/?-Al2O3 nano-catalyst, increased the hydrogen yield to 11.76 (mmol of H2/g of bagasse), CO yield to 2.67 (mmol of CO/g of bagasse) and light gaseous hydrocarbons to 0.6 (mmol of light gaseous hydrocarbons/g of bagasse). Promotion of Ni/?-Al2O3 with copper increased the mole fraction of hydrogen in the final gasification products to 58.1?mol%. PMID:25387488

Mehrani, Reza; Barati, Mohammad; Tavasoli, Ahmad; Karimi, Ali

2014-12-01

404

Origin of ultrafast Ag radiotracer diffusion in shear bands of deformed bulk metallic glass Pd40Ni40P20  

NASA Astrophysics Data System (ADS)

Measurements of Ag radiotracer diffusion in shear bands of deformed bulk metallic glass, Pd40Ni40P20 [Bokeloh et al., Phys. Rev. Lett. 107, 235503 (2011)], have found a colossal enhancement of diffusion coefficient by more than eight orders of magnitude than in undeformed Pd40Ni40P20. Suggestion was made by Bokeloh et al. that enhanced diffusion occurs in high-mobility pathways originating from some excess free volume distribution inside the shear bands. Although plausible, this qualitative suggestion does not allow quantitative calculation of the enhancement. The impasse is avoided by using the coupling model to calculate the maximum of the enhancement of diffusivity possible in high-mobility pathways of the shear bands. Within the range of eight to ten orders of magnitude, the calculated maximum enhancement is capable to account for the experimental observation.

Ngai, K. L.; Bin Yu, Hai

2013-03-01

405

?-Decay Half-Lives of Co76,77, Ni79,80, and Cu81: Experimental Indication of a Doubly Magic Ni78  

NASA Astrophysics Data System (ADS)

The half-lives of 20 neutron-rich nuclei with Z =27-30 have been measured at the RIBF, including five new half-lives of Co76(21.7-4.9+6.5 ms), Co77(13.0-4.3+7.2 ms), Ni79(43.0-7.5+8.6 ms), Ni80(23.9-17.2+26.0 ms), and Cu81(73.26.8 ms). In addition, the half-lives of Co73-75, Ni74-78, Cu78-80, and Zn80-82 were determined with higher precision than previous works. Based on these new results, a systematic study of the ?-decay half-lives has been carried out, which suggests a sizable magicity for both the proton number Z =28 and the neutron number N=50 in Ni78.

Xu, Z. Y.; Nishimura, S.; Lorusso, G.; Browne, F.; Doornenbal, P.; Gey, G.; Jung, H.-S.; Li, Z.; Niikura, M.; Sderstrm, P.-A.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Watanabe, H.; Wu, J.; Yagi, A.; Yoshinaga, K.; Baba, H.; Franchoo, S.; Isobe, T.; John, P. R.; Kojouharov, I.; Kubono, S.; Kurz, N.; Matea, I.; Matsui, K.; Mengoni, D.; Morfouace, P.; Napoli, D. R.; Naqvi, F.; Nishibata, H.; Odahara, A.; ?ahin, E.; Sakurai, H.; Schaffner, H.; Stefan, I. G.; Suzuki, D.; Taniuchi, R.; Werner, V.

2014-07-01

406

Low temperature sintering of sub-stoichiometric Ni-Cu-Zn ferrites: Shrinkage, microstructure and permeability  

NASA Astrophysics Data System (ADS)

We have studied sub-stoichiometric Ni-Cu-Zn ferrites with iron deficiency (i.e., <50mol% Fe2O3) of composition Ni0.20Cu0.20Zn0.60+zFe2-zO4-(z/2) with 0?z?0.06. The temperature of maximum shrinkage rate is shifted from T=1000 C for z=0 towards lower temperatures down to T=900 C for a sub-stoichiometric ferrite with z=0.02. Dense samples are obtained after firing at 900 C for z>0 only. Sub-stoichiometric compositions (z>0) do not form single-phase spinel ferrites after sintering at 900 C, but rather represent mixtures of CuO and a stoichiometric ferrite with slightly modified composition. The formation of small amounts of CuO at grain boundaries is demonstrated by XRD and SEM. The permeability is increased from ?=80 for stoichiometric ferrites (z=0) to ?=660 for z=0.02. The formation of CuO during sintering of sub-stoichiometric ferrites supports densification and is a prerequisite for low temperature firing of multilayer inductors. Addition of 1 wt% Bi2O3 as liquid phase sintering aid is required to provide sufficient densification of the stoichiometric ferrite (z=0) at 900 C. Addition of 0.37 wt% Bi2O3 to a sub-stoichiometric ferrite (z=0.02) results in dense samples after firing at 900 C; however, the microstructure formation is dominated by heterogeneous grain growth.

Mrbe, J.; Tpfer, J.

2012-02-01

407

Three-dimensional rigid multiphase networks providing high-temperature strength to cast AlSi10Cu5Ni1-2 piston alloys  

PubMed Central

The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4h spheroidization treatment is characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of ?-Al matrix and a rigid long-range 3-D network of Al7Cu4Ni, Al4Cu2Mg8Si7, Al2Cu, Al15Si2(FeMn)3 and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ?15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si. PMID:21977004

Asghar, Z.; Requena, G.; Boller, E.

2011-01-01

408

Positron annihilation and Moessbauer effect studies of ln-Pb and Cu-Ni binary alloys  

NASA Astrophysics Data System (ADS)

The alloy systems In(1-x)Pb(x) with x=0.00, 0.05, 0.20, 0.50, 0.80, 1.00 and Cu(1-x)Ni(x) with x=0.00, 0.10, 0.15, 0.17, 0.25, 0.30, 0.40, 0.60, 0.80 and 1.00 were studied using the positron annihilation method. Moessbauer spectroscopy was used for the In-Pb system studies. The composition dependence of the h parameter obtained from the angular distribution curves indicates a preferred annihilation of positron at the Pb atomic site in In-Pb alloys and at the Ni atomic site in Cu-Ni alloys. Additionally, temperature dependent measurements were carried out on In-20% Pb in order to evaluate the vacancy formation energy. The obtained value was 0.48 + or - 0.03 eV. The low momentum component (attributed to the contribution of the conduction electrons in the annihilation process) observed from the momentum distribution was correlated with the isomer shift obtained from the Moessbauer effect studies.

Ani, K. A.; Dezsi, I.; Balogh, A.; Kajcsos, Z.; Nagy, D. L.

1981-01-01

409

Low-Frequency Noise in NiFe/Cu Spin-Valves  

NASA Astrophysics Data System (ADS)

We have made observations of low-frequency 1/f type noise in NiFe/Cu spin valves. Our spin valves consist of 7.5 nm of Ni_81Fe_19, a spacer of 3.0 nm Cu, a 7.5 nm layer of Ni_81Fe_19 pinned by 10 nm of FeMn which is capped with 5 nm of Ta. They are sputtered on Si substrates with alumina films and patterned into stripes of 0.5 to 16 ?m widths with 11:1 aspect ratios. The observed noise is usually concentrated near the low-field linear response region. We find that the noise amplitude increases by over an order of magnitude in regions under the magnetoresistance (MR) curve where there are jumps or kinks in the R vs. H_applied trace. We shall discuss how the noise scales with device size and possible examinations of the 1/f^? slope and amplitude relationship as a function of field via a Dutta, Dimon, and Horn(P. Dutta, P. M. Horn, Rev. Mod. Phys., 53, 479 (1981).) type analysis to extract typical magnetic domain moment magnitudes.

Kirschenbaum, L. S.; Rogers, C. T.; Russek, S. E.; Kim, Y. K.

1997-03-01

410

Assembly of Cu/Ag-quinoxaline-polyoxotungstate hybrids: Influence of Keggin and Wells-Dawson polyanions on the structure  

NASA Astrophysics Data System (ADS)

In order to investigate the influence of Keggin and Wells-Dawson polyoxometalates on the resultant structure, four new organic-inorganic hybrid compounds [Cu4(qx)5(SiW12O40)] (1), [Cu6(qx)6(P2W18O62)(H2O)1.5]4.5H2O (2), [Ag4(qx)4(SiW12O40)(H2O)]H2O (3), [Ag6(qx)6(P2W18O62)]8H2O (4) (qx=quinoxaline) were synthesized and structurally characterized by single-crystal X-ray diffraction. In 1, the 2D layers are linked by the SiW12O404- (SiW12) anions to construct a 3D framework. When the Wells-Dawson type P2W18O626- (P2W18) is used, 2 is prepared, in which the 1D helical chains are connected by P2W18 to form a 3D network. In 3, two kinds of 1D metal-organic chains are connected by SiW12 clusters to construct a 3D framework. In 4, there are also two kinds of 1D chains one kind of 1D chain combines with P2W18 by the Ag?O weak interaction and the other kind is just metal-organic chain. In addition, the electrochemistry properties of compounds 1-4 have been studied.

Chi, Ying-Nan; Cui, Feng-Yun; Lin, Zheng-Guo; Xu, Yan; Ma, Xiao-Yu; Shen, Pan-Pan; Huang, Kun-Lin; Hu, Chang-Wen

2013-03-01

411

Magnetism of frustrated R2TIn3 compounds (R = Nd, Ho, Er; T = Ag,Cu) by muon spin rotation  

NASA Astrophysics Data System (ADS)

Several R2TIn3 samples (Nd2AgIn3, Ho2AgIn3, Er2AgIn3, Ho2CuIn3 and Er2CuIn3 were studied by muon spin rotation/relaxation (?SR). The R2TIn3 intermetallics are magnetically frustrated, mainly by competing ferro- and antiferromagnetic exchange. Susceptibility data suggested antiferromagnetic order with TN in the 10 K range for the materials under consideration. Later neutron diffraction studies were, however, unable to detect any magnetic Bragg peaks. The ?SR spectra of all compounds consist of two signals. One fast relaxing, reflecting strong interaction between the muon and the rare earth magnetic moments, the other slowly relaxing, arising largely from the interaction with the nuclear moments of In, its coupling to rare earth magnetism being extremely weak. Suggested origin are two different muon stopping sites in the binary layered crystal structure of the R2TIn3 series. Results on the magnetic behavior of the compounds studied are drawn from the fast relaxing signal. They show that below the susceptibility peak temperatures the systems enter into a spin-glass-type (Nd) or a spin-liquid-type (Ho,Er) short-range ordered magnetic structures, long-range order being definitely absent. Spin fluctuations persist in all cases in the limit T ? 0, a well established ?SR signature for frustrated magnetic materials.

Kalvius, G. M.; Hartmann, O.; Wppling, R.; Noakes, D. R.; Schfer, W.

2013-10-01

412

An Experimental Study of Transient Liquid Phase Bonding of the Ternary Ag-Au-Cu System Using Differential Scanning Calorimetry  

NASA Astrophysics Data System (ADS)

An experimental approach using differential scanning calorimetry (DSC) has been applied to quantify the solid/liquid interface kinetics during the isothermal solidification stage of transient liquid phase (TLP) bonding in an Ag-Au-Cu ternary alloy solid/liquid diffusion couple. Eutectic Ag-Au-Cu foil interlayers were coupled with pure Ag base metal to study the effects of two solutes on interface motion. Experimental effects involving baseline shift and primary solidification contribute to a systematic underestimation of the fraction of liquid remaining. A temperature program has been used to quantify and correct these effects. The experimental results show a linear relationship between the interface position and the square root of the isothermal hold time. The shifting tie line composition at the interface has been shown to affect the DSC results; however, the impact on the calculated interface kinetics has been shown to be minimal in this case. This work has increased the knowledge of isothermal solidification in ternary alloy systems and developed accurate experimental methods to characterize these processes, which is valuable for designing TLP bonding schedules.

Kuntz, M. L.; Panton, B.; Wasiur-Rahman, S.; Zhou, Y.; Corbin, S. F.

2013-08-01

413

Determining parameters of the local atomic structure of Cu-Ni and Cu-Mn alloys by the method of extended electron-loss fine structure spectroscopy  

NASA Astrophysics Data System (ADS)

In this work, we consider the possibility of analyzing local atomic structure based on strongly overlapping experimental extended electron-energy-loss fine structure (EELFS) spectra of two different chemical elements. M 2,3 EELFS spectra have been obtained from the surface of Cu x Ni1 - x and Cu x Mn1 - x ( x = 0.5) alloys. The method of determining the parameters of the local atomic structure (coordination numbers, lengths of the chemical bonds, and the parameters of their dispersion) of the nearest atomic surroundings in ultrathin (1-5 nm) surface layers of two-component alloys of 3 d metals has been suggested based on the overlapping extended fine structures of the electron-energy-loss spectra. The method was tested on experimental M 2,3 EELFS spectra of the surface of testing alloys Cu50Ni50 and Cu50Mn50.

Bakieva, O. R.; Nemtsova, O. M.; Gai, D. E.

2015-01-01

414

Effects of interfacial roughness on the planar Hall effect in NiFe/Cu/IrMn multilayers  

NASA Astrophysics Data System (ADS)

This paper reports that the planar Hall effect in NiFe/Cu/IrMn multilayers was strongly influenced by the Cu spacer thickness ( t Cu), which was due to the variation of interfacial roughness. With t Cu increasing, a peculiar change of planar Hall voltage was observed. The reason for the voltage behaviors was that the interfacial roughness influenced the spin-asymmetry of spin-polarized electrons in ferromagnetic metals. The diffuse scattering to the electrons turned to specular scattering when the interface became flat, leading to the variation of resistivity change (? ?). As the increase in t Cu, the extremum field was reduced because of the weaken exchange coupling between NiFe and IrMn layers.

Li, Xu-Jing; Feng, Chun; Chen, Xi; Liu, Yang; Liu, Yi-Wei; Li, Ming-Hua; Yu, Guang-Hua

2015-02-01

415

Depth-dependent fct to fcc strain relaxation in CoxNi1x/Cu3Au(100) alloy films  

E-print Network

X-ray on Cu/Ni/Cu/Si(100) [16], the measurement of total strain followed = g(tr/t)2/3 ruleDepth-dependent fct to fcc strain relaxation in CoxNi1?x/Cu3Au(100) alloy films Bo-Yao Wang a?x/Cu3Au(100) with x 6 11% was prepared at room temperature to study the strain relaxation

Lin, Minn-Tsong

416

Improved optoelectronics properties of ITO-based transparent conductive electrodes with the insertion of Ag/Ni under-layer  

NASA Astrophysics Data System (ADS)

ITO-based transparent conductive electrodes (TCE) with Ag/Ni thin metal under-layer were deposited on Si and glass substrates by thermal evaporator and RF magnetron sputtering system. Ceramic ITO with purity of 99.99% and In2O3:SnO2 weight ratio of 90:10 was used as a target at room temperature. Post-deposition annealing was performed on the TCE at moderate temperature of 500 C, 600 C and 700 C under N2 ambient. It was observed that the structural properties, optical transmittance, electrical characteristics and surface morphology were improved significantly after the post-annealing process. Post-annealed ITO/Ag/Ni at 600 C shows the best quality of TCE with figure-of-merit (FOM) of 1.5 10-2 ?-1 and high optical transmittance of 83% at 470 nm as well as very low electrical resistivity of 4.3 10-5 ?-cm. The crystalline quality and surface morphological plays an important role in determining the quality of the TCE multilayer thin films properties.

Ali, Ahmad Hadi; Abu Bakar, Ahmad Shuhaimi; Hassan, Zainuriah

2014-10-01

417

Microwave Spectra and Geometries of H2C2...AgCl and H2C2...CuCl  

NASA Astrophysics Data System (ADS)

Pure rotational spectra of the vibrational ground states of H2C2...AgCl and H2C2...CuCl have been measured by chirped-pulse FTMW spectroscopy. Each complex is generated via laser ablation of the metal in the presence of small percentages of CCl4 and C2H2 in argon. The complexes are stabilized and interrogated in the cold environment of a supersonic jet. Rotational constants ({B0, {C0) and the centrifugal distortion constant, ?J, have been measured for six isotopologues of H2C2...AgCl and three isotopologues of H2C2...CuCl with substitutions at the metal, chlorine and carbon atoms in each case. The spectrum of each complex is consistent with a C2v structure in which the metal atom is coordinated by the ?-orbital of ethyne. The measured rotational constants allow determination of the length of the bond between the metal and chlorine atoms, r(M-Cl), and the distance between the metal atom and the centre of the ethyne double bond, r(M-*). Nuclear quadrupole coupling constants have been measured for the chlorine atom in each complex and also for copper in H2C2...CuCl.

Walker, N. R.; Stephens, S. L.; Mizukami, W.; Tew, D. P.; Legon, A. C.

2012-06-01

418

Analysis of fluctuation conductivity in melt-textured YBa 2Cu 3O 7- y superconductors with Ag-doping  

NASA Astrophysics Data System (ADS)

The difference in the properties between Ag-doped and undoped YBa 2Cu 3O 7- y (YBCO) melt-textured samples was investigated by fluctuation-conductivity analysis. The temperature dependence of the resistance in those samples was measured. Data about the dimensionality and amplitude of the fluctuation were obtained by analyzing the fluctuation conductivity on the basis of the Aslamazov-Larkin theory. The fluctuation conductivity of the undoped sample shows three-dimensional behavior in the mean-field region (MFR) with a one-dimensional (1D) character at further higher temperature. The effect of a small amount of Ag addition is manifested on a fractal conduction behavior in the 1D region of the undoped sample. Upon further Ag-doping, the conduction behavior is two-dimensional in the MFR with evidence for a rapid suppression of the short-wavelength fluctuation. The conduction behavior is discussed on the relevance to structural features of melt-textured YBCO samples with and without Ag-doping.

Sato, T.; Nakane, H.; Yamazaki, S.; Mori, N.

2002-08-01

419

Atomistic processes of damage evolution in neutron-irradiated Cu and Ni at high temperature  

NASA Astrophysics Data System (ADS)

This paper consists of two parts. In part 1, the experimental results of damage evolution of neutron-irradiated Cu and Ni are described. In part 2, results of computer simulations are described with linkage of experimental data to explore the atomistic process of damage evolution. To study experimentally the atomistic processes of damage evolution in neutron-irradiated Cu and Ni in part 1, we prepare two types of specimens for both metals. One is as-received specimen from manufacturer. Another is a residual-gas-free specimen which is prepared by melting as-received metals in highly evacuated vacuum at 10-5 Pa. Specimens are irradiated with fission neutrons in the temperature-controlled-irradiation capsule at JMTR (Japan Materials Testing Reactor). TEM (Transmission Electron Microscope) observation shows that the dislocation structure is developed by the aggregation of interstitial clusters in irradiated metals. It is found that the number density of void which are observed in specimens, both as-received and residual-gas-free, that are irradiated to a low fluence such as 5.3 1018 n/cm2 at high temperature of 200C is the same. This suggests that gas atoms are not responsible for the nucleation of voids at high temperature above 200C in neutron-irradiated Cu and Ni. There are two characteristic temperatures of Tsft and Tvoid for the formation of stacking fault tetrahedra (sfts) and voids at high temperature, below Tsft only sft forms and above Tvoid only voids are observed. Tsft is 180C and 250C for Cu and Ni, respectively. Tvoid is 250C and 270C for Cu and Ni, respectively. In situ annealing experiments of neutron-irradiated specimen are carried out to examine the behavior of voids and sfts at high temperature. It is found that voids move as a cluster and that sfts coalesce and disappear spontaneously without shrinkage of their size. In part 2, Computer simulations of molecular dynamics and molecular statics are carried out to study the atomistic process of damage evolution in neutron-irradiated Cu and Ni at high temperatures. Interstitial clusters relax to a bundle of <110> crowdions and move one-dimensionally with a small activation energy such as 0.001eV. The migration of interstitial bundles reacts sensitively to strain fields. Interstitial clusters then form their grouping. The activation energy of an interstitial bundle to change their crowdion direction to another one is about 1 eV. This is an important factor for the evolution of dislocation structure. At high temperatures, a vacancy cluster of sfts and voids relaxes to a movable structure of string shape. Vacancy clusters move and coalesce with other clusters. The activation energy is as small as those that vacancy clusters move as a cluster without an evaporation as a single vacancy. Voids can nucleate at high temperature without trapping of any gas atoms in small vacancy clusters. Voids nucleate uniformly in specimens irradiated to a low fluence. Micro-voids migrate under the influence of strain fields and segregate near dislocation lies. At high temperature, vacancy clusters relax to the movable structure of string shape. This may explain the results of recent varying temperature irradiation at high temperature. At high temperature, vacancies are stored in a supersaturated state in a crystal as small vacancy clusters and clustering of vacancies proceed by cluster migration.

Shimomura, Yoshiharu; Mukouda, Ichiro; Sugio, Kenjiro; Zhao, Ping

420

Chemical interactions in the layered system BCxNy/Ni(Cu)/Si, produced by CVD at high temperature.  

PubMed

Layered samples Si(100)/C/Ni/BC(x)N(y) and Si(100)/C/Cu/BC(x)N(y) were produced by physical vapor deposition of a metal (Ni, Cu, resp.) and low-pressure chemical vapor deposition of the boron carbonitride on a Si(100) substrate. Between the Si and the Ni (Cu) and on the surface of the Ni (Cu) layer, thin carbon layers were deposited, as a diffusion barrier or as a protection against oxidation, respectively. Afterwards, the surface carbon layer was removed. As precursor, trimethylamine borane and, as an auxiliary gas, H(2) and NH(3) were used, respectively. The chemical compositions of the layers and of the interfaces in between were characterized by total-reflection X-ray fluorescence spectrometry combined with near-edge X-ray absorption fine-structure spectroscopy, X-ray photoelectron spectroscopy, and secondary ion mass spectrometry. The application of H(2) yielded the BC(x)N(y) compound whereas the use of NH(3) led to a mixture of h-BN and graphitic carbon. At the BC(x)N(y)/metal interface, metal borides could be identified. At the relatively high synthesis temperature of 700 C, broad regions of Cu or Ni and Si were observed between the metal layer and the substrate Si. PMID:22692593

Hoffmann, P S; Kosinova, M I; Flege, S; Baake, O; Pollakowski, B; Trunova, V A; Klein, A; Beckhoff, B; Kuznetsov, F A; Ensinger, W

2012-08-01

421

CuNiO nanoparticles assembled on graphene as an effective platform for enzyme-free glucose sensing.  

PubMed

We utilized CuNiO nanoparticles modified graphene sheets (CuNiO-graphene) to the application of enzymeless glucose sensing. The hydrothermal synthesized CuNiO nanoparticles were successfully assembled on graphene sheets. Distinct from general method, the high quality pristine graphene was produced by chemical vapor deposition (CVD) and bubbling transferred on the electrode. Incorporating the excellent electronic transport of graphene and high electrocatalytic activity of CuNiO nanoparticles, the CuNiO-graphene nanocomposite modified electrode possessed strong electrocatalytic ability toward glucose in alkaline media. The proposed nonenzymatic glucose sensor exhibited wide linear range up to 16mM (two parts, from 0.05 to 6.9mM and 6.9-16mM) and high sensitivity (225.75?AmM(-1)cm(-2) and 32.44?AmM(-1)cm(-2), respectively). Excellent selectivity and acceptable stability were also achieved. Such an electrode would be attractive to sensor construction for its good properties, simple operation and low expense. PMID:25597801

Zhang, Xiaohui; Liao, Qingliang; Liu, Shuo; Xu, Wei; Liu, Yichong; Zhang, Yue

2015-02-01

422

Approach to study of Cu, Ni and Zn content in soil for ecotoxicological risk assessment  

NASA Astrophysics Data System (ADS)

Current Spanish legislation on contaminated soils defines contaminated soil as "that whose characteristics have been negatively altered by the presence of dangerous human-derived chemical components whose concentration is such that it is an unacceptable risk for human health or the environment and has been expressly declared as such by legal ruling". Regarding heavy metals, the Spanish Autonomous Communities will promote measures to obtain generic reference values to declare a soil to be contaminated. In the Valencian Community, these reference values still do not exist. So if the protection of ecosystems is considered a priority to declare a soil to be contaminated and to assess the level of risk, emergency toxicity tests and seed growth in land plants are resorted to, or tests with aquatic organisms or other experiments with leached soils obtained by standard procedures are carried out. We studied the toxic effects of calcareous contaminated soils by Cu, Ni and Zn on marine bacterium Vibrio fisheri (MicrotoxR test assay) (1) and on barley (Hordeum vulgare L.) in plate (germination index) (2) and pot (UNE 77301) (3) experiments for the purpose of establishing the Cu, Ni and Zn concentrations in soil which may lead to toxicity in order to observe, therefore, whether there is any likelihood of these pollutants coming into contact with any receptor and if adverse effects exist for living beings and the environment. The results showed significant differences among the three types of tests done but, in all cases, the concentrations needed to reflect toxicity effect on organisms were around 20 -70 (Cu and Ni) to 1000 (Zn) times higher than the levels of the control soils. The sensitivity order of the bio-assay was: (1) < (3) < (2). We would like to thank Spanish government-MICINN for partial funding and support (MICINN, project CGL2006-09776).

Boluda, R.; Marimon, L.; Gil, C.; Roca-Prez, L.

2009-04-01

423

Adsorption of Cu(II) and Ni(II) on solid humic acid from the Azraq area, Jordan.  

PubMed

Isotherms of adsorption of Cu(II) and Ni(II) onto solid Azraq humic acid (AZHA) were studied at different pH (2.0-3.7) values and 0.1 M NaClO4 ionic strength. The Langmuir monolayer adsorption capacity was found to range from 0.1 to 1.0 mmol metal ion/g AZHA, where Cu(II) has higher adsorptivity than Ni(II). The previously reported NICA-Donnan parameters for sorption of Cu(II) on HA fit the amount of Cu(bound) determined in the present study at pH 3.7 but underestimates those at pH values of 3.0, 2.4, and 2.0. The contribution of low affinity sites to binding of metal ions increases with decreasing pH and increasing metal ion loading. The aggregation of HA, which is facilitated by decreasing pH and increasing metal loading, may increase the ability of low-affinity sites to encapsulate metal ions. The binding of Ni(II) to HA exhibits less heterogeneity and less multidentism than that of Cu(II). AZHA loaded with Cu(II) and Ni(II) was found to be insoluble in water with no measurable amount of desorbed metal ions. PMID:16626725

El-Eswed, Bassam; Khalili, Fawwaz

2006-07-15

424

Shedding light on the photochemistry of coinage-metal phosphorescent materials: a time-resolved Laue diffraction study of an Ag(I)-Cu(I) tetranuclear complex.  

PubMed

The triplet excited state of a new crystalline form of a tetranuclear coordination d(10)-d(10)-type complex, Ag2Cu2L4 (L = 2-diphenylphosphino-3-methylindole ligand), containing Ag(I) and Cu(I) metal centers has been explored using the Laue pump-probe technique with ?80 ps time resolution. The relatively short lifetime of 1 ?s is accompanied by significant photoinduced structural changes, as large as the Ag1Cu2 distance shortening by 0.59(3) . The results show a pronounced strengthening of the argentophilic interactions and formation of new AgCu bonds on excitation. Theoretical calculations indicate that the structural changes are due to a ligand-to-metal charge transfer (LMCT) strengthening the AgAg interaction, mainly occurring from the methylindole ligands to the silver metal centers. QM/MM optimizations of the ground and excited states of the complex support the experimental results. Comparison with isolated molecule optimizations demonstrates the restricting effect of the crystalline matrix on photoinduced distortions. The work represents the first time-resolved Laue diffraction study of a heteronuclear coordination complex and provides new information on the nature of photoresponse of coinage metal complexes, which have been the subject of extensive studies. PMID:25238405

Jarzembska, Katarzyna N; Kami?ski, Rados?aw; Fournier, Bertrand; Trzop, El?bieta; Sokolow, Jesse D; Henning, Robert; Chen, Yang; Coppens, Philip

2014-10-01

425

Tunable asymmetric magnetoimpedance effect in ferromagnetic NiFe/Cu/Co films  

NASA Astrophysics Data System (ADS)

We investigate the magnetization dynamics through the magnetoimpedance effect in ferromagnetic NiFe/Cu/Co films. We observe that the magnetoimpedance response is dependent on the thickness of the non-magnetic Cu spacer material. We verify asymmetric magnetoimpedance in films with biphase magnetic behavior and explore the possibility of tuning the linear region of the magnetoimpedance curves around zero magnetic field by varying the thickness of the spacer and probe current frequency. We discuss the experimental results in terms of the different mechanisms governing the magnetization dynamics at distinct frequency ranges, quasi-static magnetic properties, thickness of the spacer, and the kind of the magnetic interaction between the ferromagnetic layers. The results place films with biphase magnetic behavior exhibiting asymmetric magnetoimpedance effect as very attractive candidates for application as probe element in the development of auto-biased linear magnetic field sensors.

Silva, E. F.; Gamino, M.; de Andrade, A. M. H.; Corra, M. A.; Vzquez, M.; Bohn, F.

2014-09-01

426

Shape memory and superelasticity in polycrystalline Cu-Al-Ni microwires  

NASA Astrophysics Data System (ADS)

We report a strategy to significantly improve the ductility and achieve large superelastic and shape memory strains in polycrystalline Cu-Al-Ni shape memory alloys that are normally brittle. We use a liquid-phase (Taylor) wire forming process to obtain microwires of 10-150 ?m diameter with a bamboo grain structure. The reduction of grain boundary area, removal of triple junctions, and introduction of a high specific surface area in the wire decrease constraints on the martensitic transformation, and permit both superelasticity and stress-assisted two-way shape memory with recoverable strains as high as 6.8%.

Chen, Ying; Zhang, Xuexi; Dunand, David C.; Schuh, Christopher A.

2009-10-01

427

Effects of Crystallization on Boson Peak of ZrCuNiAlTi Bulk Metallic Glass  

NASA Astrophysics Data System (ADS)

The low-temperature specific heats of ZrCuNiAlTi metallic glass and its corresponding crystallized alloy are studied from 3 to 53 K. The effects of crystallization on the specific heat and boson peak of these alloys are discussed. In analyzing the experimental data, in addition to the contribution of the Debye mode and Einstein modes, the origin of the boson peak is interpreted using the harmonic localized modes based on the vibrations of loose "rattler" atoms in the oversized cage structures. The results are useful to understand the structure-property relationship of metallic glasses at low temperature.

Hou, Long; Liu, Haishun; Liu, Qingling; Dun, Chaochao; Yang, Weiming; Huo, Juntao; Dou, Linming

2015-01-01

428

Magneto impedance of electroplated NiFeMo/Cu microwires for magnetic sensors  

NASA Astrophysics Data System (ADS)

The field and frequency dependences of the magnetic permeability in soft magnetic electroplated FeNiMo/Cu microwires were studied by means of their magneto impedance response. We analysed the influence of electroplating parameters such as current density, electrolyte composition and the presence of a magnetic field. It was found that the introduction of Mo as a third non-magnetic component causes large changes in the film permeability, which are associated with compositional and morphological effects. The electrodeposition under an external magnetic field induces a unidirectional anisotropy with the appearance of a large Barkhausen effect.

Muoz, A. G.; Schiefer, C.; Nentwig, Th; Man, W.-Y.; Kisker, E.

2007-09-01

429

Fatigue behavior of ZrTiNiCuBe bulk-metallic glasses  

Microsoft Academic Search

The high-cycle fatigue (HCF) behavior of the Zr41.2Ti13.8Cu12.5Ni10Be22.5 (in at.%) bulk-metallic glass (BMG) was studied. Two batches of samples that are from different lots (Batches 59 and 94) are employed in present experiments. The HCF experiments were conducted, using an electrohydraulic machine at a frequency of 10Hz with a R ratio of 0.1 in air at room temperature and under