Diffusion Coefficient Of Copper Research Articles

Determination of phase boundaries and diffusion coefficients of copper in spinel CuCr2Se4 and delafossite CuCrSe2 by galvanostatic intermittent titration technique (GITT)

Determination of phase boundaries and diffusion coefficients of copper in spinel CuCr2Se4 and delafossite CuCrSe2 by galvanostatic intermittent titration technique (GITT)

Hydrogen delaying the formation of Guinier-Preston zones in aluminium alloys

The consequences of hydrogen on the formation and growth of GP zones during natural ageing in an Al-5Cu alloy is investigated experimentally down to the atomic scale and numerically using ab initio calculations. As observed through scanning/transmission electron microscopy, the hardening kinetic is delayed due to a slower growth of GP zones during natural ageing when hydrogen is incorporated. According to ab initio calculations, the delayed hardening results from hydrogen trapped in vacancies that reduces significantly the diffusion coefficient of copper and the self diffusion of aluminium. This reduction of the diffusion coefficient is either due to hydrogen being in the path of the atom that exchanges with the vacancy (and increasing the energy barrier) or due to hydrogen being dissociated from the vacancy (and leading to a less stable state).

The Effect of Supramolecular Humic Acids on the Diffusivity of Metal Ions in Agarose Hydrogel.

Humic acids are known as natural substances of a supramolecular nature. Their self-assembly ability can affect the migration of heavy metals and other pollutants in nature. The formation of metal-humic complexes can decrease their mobility and bioavailability. This study focuses on metal ions diffusion and immobilization in humic hydrogels. Humic acids were purchased from International Humic Substances Society (isolated from different matrices—peat, soil, leonardite, water) and extracted from lignite mined in Czech Republic. Copper(II) ions were chosen as a model example of reactive metals for the diffusion experiments. The model of instantaneous planar source was used for experimental data obtained from monitoring the time development of copper(II) ions distribution in hydrogel. The effective diffusion coefficients of copper(II) ions showed the significant dependence on reaction ability of humic hydrogels. Lower amounts of the acidic functional groups caused an increase in the effective diffusion coefficient. In general, diffusion experiments seem to act as a valuable method for reactivity mapping studies on humic substances.

Effect of zinc ions on copper electrodeposition in the context of metal recovery from waste printed circuit boards

This paper evaluates the effect of zinc ions on copper electrodeposition. Although zincis not found at significant concentrations in conventional industrial copper electrolytes, in copper-concentrated sulfate leach liquors produced in the treatment of waste printed circuit boards (WPCB) its concentration may reach high levels. In this context, the effect of zinc on physical-chemical properties of copper sulfate electrolyte, performance indicators of copper electrowinning, and morphology and crystal structure of copper deposits were investigated. Copper electrowinning tests indicated that the current efficiency was negligibly affected by adding zinc (up to 75 g L−1) to synthetic copper sulfate electrolyte (30 g L−1 Cu2+ and 110 g L−1 H2SO4) at two levels of current density (250 A m−2 and 450 A m−2) and fixed temperature (35 °C). The energy consumption slightly increased: up to 4% at 250 A m−2 and up to 3% at 450 A m−2, both effects at 75 g L−1 Zn2+. This behavior was ascribed to decreases in the electrical conductivity of the electrolyte by adding zinc (up to 35% at 75 g L−1) and consequent increases in the ohmic drop and cell voltage. Electrochemical measurements by cyclic voltammetry and linear sweep voltammetry (LSV) indicated no cathode polarization by adding this impurity to the electrolyte, even at the highest level. In turn, the addition of zinc caused significant drops in the limiting current for copper deposition (e.g., the values recorded at 100 min−1 decreased about 60% when 75 g L−1 Zn2+ was added to the electrolyte). This effect was explained by the measured increases of electrolyte viscosity and calculated decreases of copper diffusion coefficient. The addition of 75 g L−1 Zn2+ to the electrolyte increased its viscosity in the order of 76%, and decreased the diffusion coefficient in the order of 45%. Regarding the effect of zinc on product quality, SEM analysis revealed negative effects on the morphology of the deposits (i.e., higher roughness and nodulation), mainly at the highest concentration of zinc and highest current density. XRD analysis showed modifications in the growth pattern of copper crystals under some conditions. For example, the addition of 30–75 g L−1 Zn2+ to the electrolyte led to the formation of (220) textured deposits at 250 A m−2. The findings of this work may be helpful to define proper operating conditions for copper electrowinning in order to produce high quality products, thus maximizing the recycling of copper from the selected secondary source.

The structure and properties of the coating based on particles of copper and zinc deposited by gas-dynamic spraying

The results of the study of the structure and properties of the coating based on a particulate mixture of Cu and Zn deposited by the method of cold gas-dynamic spraying are presented. The presence of diffusion during the deposition of a coating with the formation of a solid solution of copper in zinc is shown. The process of predominant diffusion of copper into zinc with a slight exposure time in the furnace with the formation of intermetallic compounds Cu5 Zn8 and CuZn, the mass fraction of which reaches 44% and 28%, respectively, is revealed. The diffusion coefficient of copper to zinc is not less than 1.56×10−13 m2·s−1. An increase in the exposure time leads to a decrease in the content of beta (β ′ ) and gamma (γ) phases to ≈ 15% and the formation of a solid solution of zinc in copper (α phase, 58%) with a different ratio of initial components. The formation of electronic compounds reduces the cohesive strength of the coating metal by almost two times, and an increase in the proportion of the phase leads to an increase in the cohesion above the initial value.

Electrodeposition Process and Performance of CuIn(Se x S1−x )2 Film for Absorption Layer of Thin-Film Solar Cells

CuIn(Se x S1−x )2 thin film is prepared by the electrodeposition method for the absorption layer of the solar cell. The CuIn(Se x S1−x )2 films are characterized by cyclic voltammetry measurement for the reduction of copper, indium, selenium and sulfur in selenium and sulfur in aqueous solutions with sodium citrate and without sodium citrate. In the four cases, the defined reduction process for every single element is obtained and it is observed that sodium citrate changes the reduction potentials. A linear relationship between the current density of the reduction peak and (scan rate v)1/2 for copper and indium is achieved, indicating that the process is diffusion controlled. The diffusion coefficients of copper and indium ions are calculated. The diffusional coefficient D value of copper is higher than that of indium, and this is the reason why the deposition rate of copper is higher. When four elements are co-deposited in the aqueous solution with sodium citrate, the quaternary compound of CuIn(Se x S1−x )2 is deposited together with Cu3Se2 impure phases after annealing, as found by XRD spectra. Morphology is observed by SEM and AFM. The chemical state of the films components is analyzed by XPS. The UV-Visible spectrophotometer and electrochemistry workstation are employed to measure the photoelectric properties. The results show that the smooth, uniform and compact CuIn(Se x S1−x )2 film is a semiconductor with a band gap of 1.49 eV and a photovoltaic conversion efficiency of 0.45%.

Cyclic Voltammetry of Metallic Acetylacetonate Salts in Quaternary Ammonium and Phosphonium Based Deep Eutectic Solvents

Seven commercially sourced acetylacetonate salts were investigated in deep eutectic solvents (DESs that were prepared from ethylene glycol and trifluoroacetamide hydrogen bond donors) by cyclic voltammetry, to identify electrolytes suitable for future applications in electrochemical energy storage devices. Although the solubilities are low and on the order of 0.02 mol·L−1 for the most soluble salts, some were found to display encouraging quasi-reversible electrochemical kinetics. For instance, the diffusion coefficients of copper(II) acetylacetonate and iron(III) acetylacetonate in the trifluoroacetamide based DES are 1.14 × 10−8 and 5.12 × 10−9 cm2·s−1, which yields rate constants of 3.16 × 10−3 and 8.43 × 10−6 cm·s−1, respectively. These results are better than those obtained with the DESs prepared from ethylene glycol. The poor kinetics of the iron(III) acetylacetonate system was possibly due to the hygroscopic nature of the DESs that resulted in a continuous build-up of moisture in the system in spite of the maintenance of an inert atmosphere by means of a plastic glove bag. Further work is thus envisaged in an inert dry box that could lead to H-type glass cell charge/discharge experiments in the future.

Study on Diffusion of Copper of SOFC Cu-Based Anodes in Co-Sintering with Electrolyte

Cu-based anode has no or little catalytic activity to reaction of precipitating carbon during using carbon-hydrogen fuel, which can avoid failure or disintegration of SOFC caused by catalytically precipitating carbon resulting from Ni-based anode. However, the melting point of CuO, that is 1148°C, is far below the sintering temperature of electrolyte which limits the use of Cu-based anode. So the property of sintering of Cu-based anode between 1050°C and 1150°C was studied by co-pressing and co-sintering Cu-based anode with electrolyte. The result shows that the diffusion of copper in the electrolyte is not apparent when the co-sintering temperature is below 1130°C. At 1140°C, the Matano plane moved to anode side and the diffusion coefficient of copper in the electrolyte is relevant to concentration of copper which is 0.543×10-8-1.74×10-8(cm2•s-1) when the content of copper is 1.51%~18.7%.

Effect of carbusintering on densification behavior and mechanical properties of Fe–2%Ni– x%Cu alloys

Densification behavior and mechanical properties of Fe–Ni–Cu alloys prepared by carbusintering (CBS) and conventional sintering (CS) were studied. Carbusintering process showed the improved properties and high density compared with conventional sintering process. These differences can be explained by the microstructure and the diffusion of copper in iron powder. Microstructure observations indicated that the carbusintering process favored to refine grain size. Diffusion model analysis indicated that the diffusion coefficient of copper in iron was up to 0.63 × 10 −14 m 2/s during carbusintering process. After heat treatment, the hardness, impact energy and ultimate fracture strength of carbusintered compact are increased to 48HRC (484 HV), 13 J and 531 MPa, respectively. The use of CBS process was able to make process simple by taking sintering and carburizing as one step. The higher carbon content of the surface in P/M parts can be easily achieved compared to conventional carburizing.

Continuous Flow Stirred Cell Microfiltration of Ion Exchange Media to Determine Mass Transfer Kinetics and Equilibrium Data

Sorption of copper ions from aqueous feed streams on to polystyrene divinylbenzene Dowex 50W-X8 resins was studied. The experimental work was performed in a continuous flow stirred cell that had a slotted (8 μm × 400 μm) metal microfiltration membrane fitted to the bottom of the cell. The equilibrium parameters for a Langmuir isotherm (qm = 0.116 g g−1, b = 0.003 m3 g−1) were determined from both the batch and the continuous flow experiments, and good agreement between the two different approaches was obtained. Experiments were performed at constant pH (4.5) and ionic strength (0.2 M), using a background sodium nitrate matrix, at feed concentrations of copper up to 636 g m−3. The filtration flux was 582 L m−2 h−1. Increase of the NaNO3 decreased the amount of sorbed copper significantly. The effective diffusion coefficient of copper inside the resin was found to be 7 × 10−11 m2 s−1. The continuous flow stirred cell is shown to be an effective technique for both mass transfer kinetics as well as equilibrium data acquisition, combining both into a single step, and simplifying ion exchange analysis. Once determined, the design parameters can readily be used to model ion exchange contacting in well mixed and column operations.

Diffusion coefficient of copper, tin and copper tin alloy

Pseudopotential formalism is used to construct an ionic effective potential (ion-ion potential screened by electrons). Molecular Dynamics is used in conjunction with the constructed effective potential to get the atomic structure factor of the pure components copper and tin which are compared to the experimental ones. We selected the Shaw Optimized Model Potential having proved that it adequately describes the atomic structure, we used it to calculate the velocity autocorrelation function and to deduce the self diffusion of pure metals: copper, tin and the diffusion coefficient of copper in the Sn95,6% Cu4,4% .

Diffusion coefficient of copper, tin and copper tin alloy

Pseudopotential formalism is used to construct an ionic effective potential (ion-ion potential screened by electrons). Molecular Dynamics is used in conjunction with the constructed effective potential to get the atomic structure factor of the pure components copper and tin which are compared to the experimental ones. We selected the Shaw Optimized Model Potential having proved that it adequately describes the atomic structure, we used it to calculate the velocity autocorrelation function and to deduce the self diffusion of pure metals: copper, tin and the diffusion coefficient of copper in the Sn95,6% Cu4,4% .

Cu 22Bi 12S 21Cl 16—A mixed conductor with fast one-dimensional copper(I) ion transport

Melting reactions of Cu, CuCl, S, and Bi 2S 3 yield black, shiny needles of Cu 22(1)Bi 12S 21(1)Cl 16(1). The compound decomposes peritectically at 649(5) K. Oxidation state +I of the copper atoms is supported by Cu– K-XANES. The compound crystallizes in the hexagonal space group P6/ m with a=2116.7(7) pm and c=395.17(5) pm. Seven anions coordinate each of the two independent bismuth cations in the shape of mono-capped trigonal prisms. These polyhedra share edges and faces to form trigonal and hexagonal tubes running along [0 0 1]. The hexagonal tubes are centered by chloride ions, which are surrounded by disordered copper cations. The majority of copper cations are distributed over numerous sites between the tubes. The Joint Probability Density Function (JPDF) reveals a continuous pathway along [0 0 1]. The high mobility of the copper cations along [0 0 1] was demonstrated by impedance spectroscopy and DC polarization measurements on single crystals. The ionic conductivity at 450 K is about σ ion=0.06 S cm −1, and the activation energy for Cu + ion conduction is E a=0.44 eV. The chemical diffusion coefficient of copper is in the order of D cu δ =10 19 cm −3 at 420 K. The electronic band gap (p-type conductor) was determined as E g=0.06 eV. At room temperature the thermal conductivity of a pressed pellet is about κ=0.3 W K −1 m −1 and the Seebeck coefficient is S=43 μV K −1.

The adsorption of copper in a packed-bed of chitosan beads: Modeling, multiple adsorption and regeneration

In this study, exoskeletons of Cape rock lobsters were used as raw material in the preparation of chitin that was successively deacetylated to chitosan flakes. The chitosan flakes were modified into chitosan beads and the beads were cross-linked with glutaraldehyde in order to study copper adsorption and regeneration in a packed-bed column. Five consecutive adsorption and desorption cycles were carried out and a chitosan mass loss of 25% was observed, after the last cycle. Despite the loss of chitosan material, an improved efficiency in the second and third cycles was observed with the adsorbent utilizing 97 and 74% of its adsorbent capacity in the second and third cycles, respectively. The fourth and fifth cycles, however, showed a decreased efficiency, and breakage of the beads was observed after the fifth cycle. In the desorption experiments, 91–99% of the adsorbed copper was regenerated in the first three cycles. It was also observed that the copper can be regenerated at a concentration of about a thousand fold the initial concentration. The first cycle of adsorption could be accurately described with a shrinking core particle model combined with a plug flow column model. The input parameters for this model were determined by batch characterization methods, with as only fitting parameter, the effective diffusion coefficient of copper in the bead.

Modeling the diffusion of solid copper into liquid solder alloys

During the soldering process, the copper atoms diffuse into liquid solders. The diffusion process determines integrity and the reworking possibility of a solder joint. In order to capture the diffusion scenarios of solid copper into liquid Sn–Pb and Sn–Cu solders, a computer modeling has been performed for 10 s. An analytical model has also been proposed for calculating the diffusion coefficient of copper into liquid solders. It is found that the diffusion coefficient for Sn–Pb solder is 2.74 × 10 − 10 m 2/s and for Sn–Cu solder is 6.44 × 10 − 9 m 2/s. The modeling results reveal that the diffusion coefficient is one of the major factors that govern the rate at which solid Cu dissolve in the molten solder. The predicted dissolved amounts of copper into solders have been validated with the help of scanning electron microscopic analysis.

Solid-Phase Diffusion Interaction in Multilayer Thin-Film System Cr/Cu/Ni at Pulse Laser Heating

The laser-induced mass transfer in thin-film substrate /Cr/Cu/Ni system is studied by means of Auger Electron Spectroscopy (AES). For the laser-pulse energy values, E = 100-170mJ, the diffusion of Cu atoms into Ni layer and their accumulation within this layer are observed, whereas at E > 170mJ the same is true for Cr atoms. The observed phenomena are explained on the basis of calculated temperature distribution in the system at issue during lased action. Enhanced transfer of Cr atoms towards external surface is observed under the irradiation regimes leading to the melting of intermediate copper layer. Diffusion coefficients of copper and chromium calculated from their surface accumulation show an exponential dependence on the laser-pulse energy. Under laser heating, the diffusion processes are more manifested as compared with those under conventional thermal annealing. This is bound up with higher concentration of nonequilibrium defects generated within the irradiation zone.

Plasma electrochemistry: Absorption of flame borne species in platinum electrodes

Electrochemical potentiometric measurements have been shown to be possible in flame plasma using solid electrodes. The properties of the solid metal electrodes can effect the magnitude of the potential measured, due to the material's capacity to absorb flame borne species. Through this process, a surface alloy is formed and so alters the work function of the electrode. The study presented in this paper is concerned with understanding the mechanism by which copper, present in the flame, can absorb into platinum (Pt) electrodes at 1880 K. Electrodes were sectioned and the weight percent of copper was measured using an electron probe, to a distance of 100 μm from the surface. The distribution profiles of copper (Cu) measured for electrodes held in a flame doped with a solution containing copper chloride (5 × 10 −2 M) for 1, 5, 10 and 30 min modelled using finite element modelling. The predominant mechanism of absorption was unambiguously found to be instantaneous pulse, where a thin layer of copper was first deposited on the electrode surface by condensation followed by absorption. The layer was found to be 240 ± 30 nm and the copper diffusion coefficient was 8.0 ± 0.6 × 10 −13 m 2 s −1 in Pt at 1880 K.

Influence of concentrations of copper, levelling agents and temperature on the diffusion coefficient of cupric ions in industrial electro-refining electrolytes

Few data are available for diffusion coefficients measured in industrial copper electrolytes. In the present work the influence of copper concentration (19.9–58.1 g dm−3), temperature (20–60°C) and concentrations levelling agents i.e. animal glue (0–5 mg dm−3) and thiourea (0–5 mg dm−3) on diffusion coefficients of copper was studied in industrial copper refinery electrolytes. Chronoamperometry at ultramicroelectrodes was used as an electrochemical technique. Apparent bulk diffusion coefficients were calculated on the basis of the theory of electrochemical nucleation on disc-shaped ultramicroelectrodes. Increasing copper concentration decreased the apparent bulk diffusion coefficient of copper and diffusion coefficients followed the Arrhenius temperature relationship. The experimental activation energy was 26.8 kJ mol−1. The influence of levelling agents on diffusion coefficients was not strong in the studied concentration range of animal glue and thiourea.

Grain Boundary Surface Tension, Segregation and Diffusion in Cu-Sn System

Grain boundary and free surface tension for pure copper and copper-tin alloys are measured. On the base of these data isothermes of grain boundary tension, free surface tension and isothermes of adsorption are constructed in assumption of a dilute solution. Grain boundary diffusion coefficients of copper were calculated by using the relation of Borisov et. al. for copper and copper-tin alloys.

Surface diffusion of copper on tantalum substrates by Ostwald ripening

In this work, we report on the determination of surface diffusion coefficient of copper on tantalum substrates by Ostwald ripening. It is shown that impurities, such as oxygen, strongly influence the kinetics of dewetting of copper films on tantalum substrates. Two technologically important interfaces with copper were investigated: Cu/β-Ta and Cu/α-Ta. For copper surface diffusion on β-Ta surface, a surface diffusion coefficient of D S betaTa = 2.6 1.0 3.7 · 10 - 11 ( cm 2 / s ) was measured at 550 °C. The temperature dependence of surface diffusion was investigated between 400 °C and 550 °C. Using an Arrhenius relationship, an activation energy of 0.83 ± 0.1 eV and a pre-exponential factor of D S 0 betaTa = 2.8 0.2 7.5 · 10 - 6 ( cm 2 / s ) were calculated. For copper surface diffusion on α-Ta surface, a diffusion coefficient of D S alphaTa = 2.0 1.5 3.1 · 10 - 12 ( cm 2 / s ) was measured at 550 °C. We discuss the diffusion mechanism involved during the cluster growth and the origin of the faster surface diffusion of copper on the β-Ta substrate as compared to the α-Ta phase.