Ag In Cu Research Articles

Decrease of steady-state solubility of Ag in Cu by high-pressure torsion at low temperature

Decrease of steady-state solubility of Ag in Cu by high-pressure torsion at low temperature

Effect of Ag agglomeration-driven nanovoids formation on fatigue reliability of Cu–Ag alloy flexible interconnects

Fatigue failure under cyclic deformation remains longstanding challenge in the flexible interconnect for the long term application. In this study, we design Cu–Ag alloy interconnects with excellent fatigue resistance by adopting nanovoid structures acquired by a simple post-annealing process. Nanovoids are generated during Ag agglomeration in the Cu matrix because of the low solubility of Ag in Cu, which enhances the fatigue property of a Cu–Ag alloy deposited on a polyimide film. The effect of high-density nanovoids located at the triple junction of the Cu and Ag grain boundaries on the mechanical fatigue lifetime is investigated by microstructure analysis (HAADF, HR-TEM and ASTAR™-coupled TEM). The fatigue damage of the Cu–Ag alloy has been observed to originate from grain boundary decohesion, unlike typical long fatigue cracks and extrusions. This can be attributed to the uniform distribution of nanovoids, which leads to stress concentration relief and consequently reduces the level of deformation.

The Kβ/Kα X-ray intensity ratios of Cu and Ag in Cu–Ag thin alloy films

Kβ/Kα X-ray intensity ratio values of Cu and Ag in CuxAg1-x (x = 53.5, 67.6, 76.9, 85.4, 89.6) thin alloy films produced from two different sources by the physical vapour deposition method have been determined by the Energy Dispersive X-ray Fluorescence Spectroscopy (EDXRF) method. The changes in the crystal structures of CuxAg1-x thin alloy films caused by the changes in the Cu and Ag concentrations, which affect the valence electronic structure have been investigated by the X-ray Diffraction (XRD) techniques. The obtained values were compared with the theoretical and fitted values for pure Cu and Ag elements.

Synthesis and characterization of Ag@Cu-based MOFs as efficient adsorbents for iodine anions removal from aqueous solutions

Due to the critical importance of capturing radioiodine from aquatic environments for human health and ecosystems, developing highly efficient adsorbent materials with rapid kinetics for capturing iodide ions in aqueous solutions is urgently needed. Although extensive research has been conducted on iodine adsorption in gas and organic phases, limited research has been dedicated to adsorption in aqueous solutions. An effective technique for removing iodide was proposed using Ag@Cu-based MOFs synthesized by incorporating Ag into calcined HKUST-1 with varying mass ratios of Ag/Cu–C. Extensive characterization using SEM, XRD, XPS, and nitrogen adsorption-desorption analysis confirmed successful incorporation of Ag in Cu–C. Batch adsorption experiments were conducted, demonstrating that the 5% Ag@Cu–C material exhibited a high adsorption capacity of 247.1 mg g−1 at pH 3. Mechanism investigations revealed that Cu0 and dissolved oxygen in water generate Cu2O and H2O2, while Ag and a small amount of CuO generate Ag2O and Cu2O. Furthermore, iodide ions in the solution are captured by Cu+ and Ag+ adsorption sites. These findings highlighted the potential of Ag@Cu-based MOFs as highly effective adsorbents for iodine anions removal in radioactive wastewater.

Effect of Size on the Formation of Solid Solutions in Ag-Cu Nanoparticles.

Modern technologies stimulate the quest for multicomponent nanosized materials with improved properties, which are ultimately defined by the atomic arrangement and interphase interactions in the nanomaterial. Here, we present the results of the experimental study of the formation of solid solutions in Ag-Cu nanoparticles in a wide size and temperature range using in situ TEM techniques. The Ag-Cu nanoparticles with a eutectic ratio of components were formed on an amorphous carbon film by the physical vapor deposition technique. Electron diffraction, HAADF-STEM imaging, energy-dispersive X-ray spectroscopy, chemical element mapping, and electron energy loss spectral imaging were used for the characterization of mixing patterns and composition of phases in AgCu nanoparticles down to the atomic level. As a result, we constructed the solid-state part of the Ag-Cu phase diagram for nanoparticles with a size down to 5 nm. We found a highly asymmetric behavior of the solvus lines. Thus, the content of Cu in Ag gradually increased with a size reduction and reached the ultimate value for our configuration of 27 wt % Cu at a nanoparticle size below ∼8 nm. At the same time, no Cu-rich solid solution was found in two-phase AgCu nanoparticles, irrespective of the size and temperature. Moreover, a quasi-homogeneous solid solution was revealed in AgCu nanoparticles with a size smaller than 8 nm already at room temperature. A size dependence of the terminal temperature T term, which limits the existence of AgCu alloy nanoparticles in a vacuum, was constructed. Evaporation of the AgCu phase with the composition of 86 wt % Ag was observed at temperatures above T term. We show the crucial role of the mutual solubility of components on the type of atomic mixing pattern in AgCu nanoparticles. A gradual transition from a Janus-like to a homogeneous mixing pattern was observed in Ag-Cu nanoparticles (28 wt % Cu) with a decrease in their size.

Green production of biologically active Ag and Ag–Cu nanoparticles from Prosopis cineraria pod waste extract and their application in epoxidation

The main focus of the current research is bio-nano-technologically produced nanoparticles (NPs) utilizing waste materials. There is a need for developing advanced technology to reduce waste in an eco-friendly way. Therefore, presently the discarded aqueous portion of Prosopis cineraria pod was used after boiling, to synthesize Ag and Ag–Cu NPs. FT-IR spectra illustrated the presence of phenyl propenoids and flavonoids displaying capping as well as reducing properties. TEM and SEM imaging exhibited an average size of Ag NPs (14 nm) and Ag–Cu NPs (27 nm). The crystallinity nature was confirmed by XRD, and the Cu in Ag–Cu NPs was validated through energy-dispersive X-ray analysis. According to the antimicrobial data, Saccharomyces cerevisiae displayed a zone of inhibition (ZOI) of 42.85% (Ag NPs) and 33.98% (Ag–Cu NPs) at lower concentrations (0.0321 mg/ml), while Bacillus subtilis was found most susceptible (85% ZOI) to Ag NPs at 0.5 mg/ml concentration. Further, these NPs (Ag and Ag–Cu) were utilized in the epoxidation of alkene moieties. Ag NPs showed lower conversion (65%), while Ag–Cu NPs were very active for epoxidation of linalool (93% conversion), suggesting the presence of Cu-facilitated epoxidation. To the best of our knowledge for the first time, aqueous waste is applied to prepare green NPs that can be used as antimicrobial agents and in the synthesis of platform chemicals (epoxide) for industrial aspects. These inexpensive ways of producing green NPs have been utilized several times and have found potential applications in nano-medicine, therapeutics, and modification of monoterpenoids to fine fragrance.

Enhancement of strength and electrical conductivity for hypo-eutectic Cu-12Ag alloy

A thermo-mechanical treatment was designed for a hypo-eutectic Cu-12Ag alloy in order to enhance its tensile strength, as high as 1189 MPa, at the relatively minimal cost of the electrical conductivity, as good as 71.9%IACS, the combination of strength and conductivity being far superior to other Cu-Ag alloys ever reported in the literature. To understand detailed mechanisms, a Cu-7Ag alloy and a Cu-12Ag alloy, which is beyond the maximum solubility (8 wt%) of Ag in Cu, were chosen for comparison and homogenized at 777 °C for an hour followed by aging at 400 ℃. The peak-aged alloys were then cold-rolled with a 99% reduction. Cu-7Ag showed higher hardness than that of Cu-12Ag at peak aging. However, Cu-12Ag showed higher strength and conductivity than those of Cu-7Ag after cold rolling. The elongated dispersed Ag phases in Cu-12Ag attributed extra strengthening, while keeping a minimal reduction of the conductivity after cold rolling.

Impact of Ag content on device properties of Cu(In,Ga)Se2 solar cells

Partial substitution of Cu by Ag in Cu(In,Ga)Se2 (CIGS) solar cells is advantageous as it allows lower temperature growth while maintaining high performance. To understand the role of Ag on device performance, we present a comprehensive analysis of (Ag,Cu)(In,Ga)Se2 (ACIGS) samples with an [Ag]/([Ag]+[Cu]) (AAC) ratio varying from 7% to 22%. The analysis involves a set of material and device characterization techniques as well as numerical simulations. Multiple electrical and material properties show a systematic dependence on the increased Ag content. These include a carrier-density decrease, a grain-size increase, and a flattened [Ga]/([Ga] + [In]) (GGI) profile leading to a higher minimum band gap energy and a reduced back grading. Although the best performing device (PCE = 18.0%) in this set has an AAC = 7%, cells with higher Ag contents have an advantage of a smoother absorber surface which is attractive for tandem applications, despite their slightly inferior conversion efficiencies (PCE = 16.4% for 22% Ag).

Colloidal Cu2ZnSnS4-based and Ag-doped Nanocrystals: Synthesis and Raman Spectroscopy Study

Cu2ZnSnS4 (CZTS) is one of the promising materials for absorber layers of new-generation thin film solar cells. Various synthetic routes of materials preparation and structural characterization have been explored so far. Further tuning of the CZTS properties is realized via partial substitution of the cations. Here we have used an affordable and scalable method of synthesizing colloidal CZTS nanocrystals (NC) in an aqueous solution. Variation of the synthesis parameters, in particular pH of the solution, was employed to improve the crystallinity of the NCs. Furthermore, CZTS NCs with partial substitution of Cu for Ag were also successfully synthesized. Raman spectroscopy was employed as a prime tool of structural characterization of the NCs obtained, along with optical absorption spectroscopy and ab initio DFT lattice dynamics calculations. An experimentally observed slight upward shift of the main phonon Raman peak upon increase of the Ag content in (AgxCu1-x)2ZnSnS4 NCs is in agreement with the trend predicted by DFT calculation. No pure Ag2ZnSnS4 NCs could be formed, indicating a critical role of Cu in forming the kesterite structure NCs under given synthesis conditions in an aqueous medium.

Challenges in the deposition of (Ag,Cu)(In,Ga)Se2 absorber layers for thin-film solar cells

The partial replacement of Cu by Ag in Cu(In,Ga)Se2 thin-film solar cells is strategically interesting to achieve smooth devices with high conversion efficiencies. Yet, the industrial exploitation requires further understanding of the deposition process and control of the absorber layer properties. In this study, three-stage co-evaporation of (Ag,Cu)(Ga,In)Se2 films with [Ag]/([Ag] + [Cu]) contents up to 0.2 was investigated. Deep crevices and voids, sometimes extending down to the rear contact, were found. They mainly occur for high Ag contents and excessive group-I richness during the second stage of the deposition. The formation of cavities is attributed to the segregation of Ag–Se phases and slow Ag diffusion into the chalcopyrite during the deposition. Another identified challenge is the flattening of the desired bandgap grading which is correlated with the Ag content. Optimized process conditions allow fabrication of smooth (Ag,Cu)(Ga,In)Se2 films in a manufacturing-like inline deposition with cell efficiencies up to 20.5%.

A study of diffusion, atom migration and segregation in Cu and Ag alloy bulk- and nanocrystals

Using the Sutton-Chen potential, Molecular Dynamics simulations were done of Ag and Cu bulk and nanocrystals and the vacancy formation energy, migration energy, and diffusion activation energy were calculated. Values for Cu compared very well with literature, and Ag less so. The migration energy along a diffusion path was studied for different low index surface orientations. Using the mixed form of the potential for bimetallic interactions with a slight adjustment, the interactions between Ag and Cu were also simulated. Migration energy depth profiles along with segregation energies at different depths were studied. Surface segregation of Ag in Cu was successfully simulated and the calculated segregation values of a Ag atom in Cu compared well to literature values.

Strength of Cu-28 wt%Ag composite solidified under high magnetic field followed by cold drawing

Cu-Ag composite is one of the best conductors for high-field magnets. Increasing its strength is crucial for designing newer high-field magnets. Cu-28 wt%Ag samples were solidified with and without a 12-T high magnetic field (HMF), and then cold-drawn. We investigated the influence of HMF on microstructure, hardness and strength of Cu-Ag samples both before and after cold-drawing. The introduction of external HMF during solidification increased both the dendrite arm spacing and the dissolved Ag in Cu, and it reduced the spacing between both the Ag precipitates in proeutectic Cu and the eutectic lamellae. The transversal microstructure after cold-drawing inherited the network solidification structure, but at a refined scale. The Cu dendrite spacing in the 12-T HMF samples at all deformation strain was larger than that without HMF. HMF slightly increased the intensity of fiber texture of Cu, which strengthened proeutectic Cu at the level of 3.5 deformation strain. In samples deformed to strain of 3.5, refined Ag precipitation spacing, increased Ag solubility in Cu matrix, and refined eutectic lamellar spacing by 12-T HMF increased the strength by 5% in the sample compared with that without HMF.

Microstructure, resistivity, and hardness of aged Ag-7wt.%Cu alloy

Ag-Cu alloys are used as both decorative materials because of beautiful appearance, and conductors due to excellent combinations of strength and electrical conductivity. The strength and electrical conductivity of Ag-Cu alloy are closely related to precipitation behavior of Cu-rich phase in Ag matrix. The morphology, size and volume fraction of Cu-rich phase have been highly concerned. In this work, a series of aging temperatures is used in both supersaturated solid-solution and cold-rolled Ag-7wt.%Cu samples to investigate the relationship between the precipitation behavior of Cu-rich phase and property by using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and properties measurements (hardness and resistivity). The DSC results of as-solid-solution Ag-7wt.%Cu alloy show a distinct exothermic precipitation reaction of Cu out of Ag matrix ranging from 300 C to 350 C, and the activation energy is estimated to be (1111.6) kJ/mol according to Kissinger equation. Because of the existence of deformation energy, the DSC results of cold-rolled Ag-7wt.%Cu sample show a distinct exothermic precipitation reaction of Cu from Ag matrix between 290 C and 330 C, and the activation energy is (12812) kJ/mol. XRD analysis indicates that the dissolved Cu in Ag is dependent on ageing temperature, and the change of solubility of Cu in Ag is calculated by XRD curve. Microstructural analysis demonstrates that spherical Cu-rich phases are precipitated from Ag-matrix at 450 C in both solid-solution and cold-rolled Ag-7wt.%Cu alloys. Moreover, the banded structure of Cu-rich phase is found in the solid-solution sample after being aged at 450 C. The deformation twinning Ag is found in the cold-rolled sample. The precipitation and dissolution of Cu-rich phase in Ag matrix play important roles in the resistivity and microhardness. With ageing temperature increasing (ageing temperatures range from 200 to 450 C), the electrical resistivity of as-solid-solution aged sample decreases and the microhardness increases, however, both electrical resistivity and microhardness of as-cold-rolled aged sample decrease. With ageing temperature increasing further (over 450 C), the electrical resistivity increases and the microhardness decreases in both aged samples. Because of the formations of dislocation and deformation twinning Ag, the microhardness of cold-rolled sample reaches to 217 HV, which is higher than that of solid-solution sample. Strengthening and electrical resistivity models are built based on the microstructural characterization and concentration contributions. These theoretical predictions are in good agreement with experimental values. Our model demonstrates that the precipitation and dissloution of Cu in Ag significantly affect the electrical conductivity, and dislocation and deformation twinning play important roles in microhardess in Ag-Cu alloy. This work clarifies the influencing mechanism of different microstructures on the microhardness and resistivity of Ag-Cu alloy.

Radiotracer diffusion of Ag in Cu(In,Ga)Se2 thin films

Diffusion of Ag in Cu(In,Ga)Se2 was investigated utilizing radiotracer sputter-profiling of 110mAg. After removal of the CdS capping layer the 110mAg isotope was deposited on the front-surface of the Cu(In,Ga)Se2 layer and the samples were subjected to isothermal annealing in a temperature interval ranging from 573K up to 648K. The observed Ag diffusivity can be described by the following Arrhenius equation D(T)=0.12exp(−1.29eV/kBT) cm2/s. Comparison with the diffusivities of Zn, Cd and Fe in Cu(In,Ga)Se2 in the investigated temperature regime reveals similiar activation energies, but a larger pre-exponential factor for Ag diffusion resulting in accelerated diffusion kinetics.

Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

Copper chalcopyrite is a promising candidate for a photocathode material for photoelectrochemical (PEC) water splitting because of its high half-cell solar-to-hydrogen conversion efficiency (HC-STH), relatively simple and low-cost preparation process, and chemical stability. This paper reviews recent advances in copper chalcopyrite photocathodes. The PEC properties of copper chalcopyrite photocathodes have improved fairly rapidly: HC-STH values of 0.25% and 8.5% in 2012 and 2015, respectively. On the other hand, the onset potential remains insufficient, owing to the shallow valence band maximum mainly consisting of Cu 3d orbitals. In order to improve the onset potential, we explored substituting Cu for Ag and investigate the PEC properties of silver gallium selenide (AGSe) thin film photocathodes for varying compositions, film growth atmospheres, and surfaces. The modified AGSe photocathodes showed a higher onset potential than copper chalcopyrite photocathodes. It was demonstrated that element substitution of copper chalcopyrite can help to achieve more efficient PEC water splitting.

Surface Growth and Diffusion Energetics of Ag Monolayers on Cu (001)

The growth of Ag monolayers on Cu (001) was studied by periodic Density Functional Theory (DFT). Despite the limited solid solubility of Ag in Cu, the growth of a single Ag overlayer on Cu (001) was predicted as feasible. In contrast, the growth of consecutive Ag monolayers was found to be energetically forbidden. Inter-diffusion of Ag monolayers into Cu was raised as a possibility but it was dependent on the sequence in which the Ag monolayers were introduced into the Cu bulk. The Ag layers preferred to be kept neither too far apart nor too close to each other, the optimum spacing between two Ag monolayers determined to be that of two consecutive Cu layers. Ag diffusion mediated tensile stress in the Cu cell by causing an increase of the unit cell constant by as much as 22%. Interactions between the Ag and Cu species also involved a degree of covalency. In general, progression of a surface Ag monolayer into the Cu bulk involved charge depletion over the Ag species and a simultaneous charge concentration over neighboring Cu atoms; this mechanism was found to influence Cu up to a depth of four surface layers.

Structural features of Ag-Cu alloy films produced by the codeposition of sputtered metals

Solid solutions in the form of alloy coatings are obtained in the entire concentration range of binary system using ion-plasma sputtering and the codeposition of Ag and Cu ultrafine particles. Sstudying the structure of solid solutions shows a change in the FCC-lattice parameters from silver to copper with a characteristic bend corresponding to the eutectic composition of the equilibrium phase diagram. Solid-solution decay begins at 100°C, and their complete decomposition occurs at 250°C. The surface structure of the initial solutions is presented by crystallites 20–30 nm in cross section; after decomposition, their size is less than 100 nm. For the latter, the distortions of the lattice parameters are 0.32% for a solution of Cu in Ag and 0.29% for a solution of Ag in Cu. The method of alloy production can be extended to the systems of metals immiscible in the solid phase.

Diffusion and segregation of silver in copperΣ5(310) grain boundary

Grain boundary diffusion of ${}^{110m}\phantom{\rule{-0.16em}{0ex}}$Ag in Cu $\ensuremath{\Sigma}5(310)$ bicrystal is measured along and perpendicular to the $[001]$ tilt axis in both C and B kinetic regimes after the common Harrison's classification. The grain boundary diffusion coefficients, ${D}_{\mathrm{gb}}$, of the single grain boundary in a true dilute limit of solute concentration are determined in the C kinetic regime and the values of the triple products $P=s\ifmmode\cdot\else\textperiodcentered\fi{}\ensuremath{\delta}\ifmmode\cdot\else\textperiodcentered\fi{}{D}_{\mathrm{gb}}$ are measured in the B regime (here $s$ and $\ensuremath{\delta}$ are the segregation factor and the diffusional grain boundary width, respectively). A strong anisotropy of the grain boundary diffusion is established, which disappears above 826 K. It is the point at which the triple product $P$ demonstrates a downward deviation from the otherwise linear Arrhenius dependence at lower temperatures. These results substantiate a temperature-induced disordering transition of the grain boundary structure. The anisotropy of the product $s\ifmmode\cdot\else\textperiodcentered\fi{}\ensuremath{\delta}$ for the $\ensuremath{\Sigma}5(310)$ grain boundary is estimated.

Phase stability, crystal structure and thermoelectric properties of Cu doped AgSbTe2

CuxAg1-xSbTe2 samples withx = 00.3 are prepared by a combined process of melt-quenching and spark plasma sintering (SPS). X-ray powder diffraction (XRD) analysis indicates that single phase samples with the NaCl-type structure are obtained for the Cu-doped samples before SPS treatment, whereas a small quantity of Ag2Te impurities coexist with the main cubic phase for the sample without Cu. According to our thermoanalysis and XRD results, the substitution of Cu for Ag can effectively prevent the precipitation of Ag2Te, but this also leads to the presence of a minor amorphous phase in the melt-quenched sample. The amorphous phase crystallizes into Sb7Te metastable phase at about 540 K, which finally transforms into the stable Sb2Te3 compound. After the SPS treatment of the melt-quenched sample, the sample withx=0.1 remains a single phase with the face-centered-cubic crystal structure, while Sb7Te and Sb2Te3 are precipitated as the second phases for the samples withx = 0.2 and 0.3, respectively. The electrical conductivity increases and the Seebeck coefficient decreases with the addition of Cu due to the existence of the second phase in the samples withx = 0.2 and 0.3. Accordingly, thermal conductivities also increase with the addition of Cu, leading to the reduced thermoelectric performance of thex= 0.2 and 0.3 samples. For the sample withx = 0.1, its power factor is comparable to that of the literature reported AgSbTe2 compound. As a result of so-called alloying effect, the phonon scattering effect is enhanced due to the partial replacement of Ag by Cu, leading to the reduced thermal conductivity of thex = 0.1 sample. Therefore, the Cu0.1Ag0.9SbTe2 sample exhibits the promising thermoelectric performance and a dimensionless thermoelectric figure of merit (ZT) value of 1 is achieved at 620 K.

Extremely low temperature coefficient of resistance in antiperovskite Mn3Ag1−xCuxN

Electrical resistivity is systematically investigated in Mn3AgN and related compounds with an antiperovskite structure. Despite its overall metallic character, Mn3AgN features a broad maximum in the temperature-resistivity curve in the paramagnetic state and the temperature coefficient of resistance (TCR) is negative at higher temperatures. The resistivity-peak temperature was tuned to just room temperature by the partial substitution of Cu for Ag, and a TCR as low as 10−6 K−1 was achieved over a wide temperature window including room temperature. These peculiar behaviors are possibly due to collapse of coherent quasiparticle states by strong magnetic scattering.