Pure Copper Metal Research Articles

A Study on the Metal Organic CVD of Pure Copper Films from Low Cost Copper(II) Dialkylamino‐2‐propoxides: Tuning the Thermal Properties of the Precursor by Small Variations of the Ligand

AbstractPure copper metal thin films were grown on SiO2/Si(100) substrates by metal–organic (MO) CVD in a horizontal cold‐wall reactor employing the two metal–organic compounds, Cu(OCHMeCH2NR2)2, where R = Et (1) and R = Me (2) as precursors. Thermogravimetric analyses proved them to be convenient compounds for the deposition of copper without a reducing agent. Depositions were carried out at various substrate temperatures in the range 230–350 °C. X‐ray diffraction (XRD) indicated that the resulting films were highly crystalline and showed a strong (111) preferred orientation, which increased with increasing deposition temperature. Photoelectron spectroscopy (XPS) revealed that copper films deposited at 230 °C and 260 °C consisted solely of metallic copper with no detectable carbon, nitrogen, or oxygen contamination. Copper films obtained from 1 at 260 °C had a resistivity of 2.16 μΩ cm.

Recovery of copper, tin and lead from the spent nitric etching solutions of printed circuit board and regeneration of the etching solution

In order to recover valuable metals and regenerate the etching solution from the spent nitric etching solutions of printed circuit board (PCB), solvent extraction, stripping, electrowinning, precipitation and cementation experiments have been performed. Nitric acid was selectively extracted by TBP from the spent etching solution and pure nitric acid solution was stripped by distilled water. After extracting nitric acid, pure copper metal was obtained by electrowinning and tin ions were precipitated by adjusting the pH of solution with Pb(OH) 2. Lead metal with purity of 99% was obtained by cementation with iron powder.

High Purity Metals as Primary Calibration Materials for Elemental Analysis-Their Importance and Their Certification

The Bundesanstalt fur Materialforschung und -prufung, BAM (Federal Institute for Materials Research and Testing) continues to establish a system of primary reference materials to meet the demands of metrological traceability. The materials act as national standards in the field of elemental analysis. For all elements of the periodic table-excepting those that are gases or radioactive-two different kinds of reference materials are being certified. The substances are of very high purity and of defined stoichiometry. Pure elements and metals are used as far as possible. They are certified by determining the trace contents of most elements of the periodic table at very low levels using different trace element analysis methods. Recent application of these methods is described and examples of the certification of some pure metals (copper, iron and lead) are given.

Studies in hydride generation atomic fluorescence determination of selenium and tellurium. Part 2 — effect of thiourea and thiols

In determination of selenium and tellurium by continuous flow hydride generation atomic fluorescence spectrometry, the effect of thiourea and thiols was investigated in view of their potential to achieve mild reaction conditions and as masking agents of interference from foreign elements. The effect of thiourea and thiols was first tested in the absence of interfering species and using different addition modes to reaction system. In the absence of interfering species, thiols negatively influenced the hydride evolution of both selenium and tellurium and, in general, they did not produce the desired effects. Thiourea was well tolerated in the determination of both elements by appropriate choice of experimental conditions. Possible mechanisms producing the depressive effect of thiourea and thiols were also investigated and are discussed later. Compromise reaction conditions were identified by using on-line addition of a neutral thiourea solution to acidified sample, combined with KI addition to NaBH 4. Mild reaction conditions can be achieved by decreasing the NaBH 4 concentration but at the expense of a reduced linear dynamic range. In the presence of foreign elements, thiourea allowed good control of interferences generated by Cu(II), Co(II), Ni(II), Au(III), Ag(I) and Bi(III). Tolerance limits could be improved by factors in the range of 7–2000, for both selenium and tellurium determination. The method has been successfully applied in the determination of traces of tellurium and selenium in copper, lead and molybdenum ores, stainless steel and pure copper metal without any additional steps other than sample dissolution.

Deformation and texture of copper–manganese alloys

Manganese is the only element that can be dissolved in copper up to 12% without markedly changing the stacking fault energy (SFE). Hence, investigation of the deformation behaviour of Cu–Mn alloys may yield insight into the influence of alloying elements apart from the (usual) decrease in SFE. The development of the crystallographic texture is analysed in various Cu–Mn alloys that were deformed either in compression or by cold rolling. The texture development is simulated by means of a novel materials-dependent Taylor-deformation model. The spatial arrangement of the rolling texture orientations in the as-deformed microstructure is studied by an orientation-sensitive etching technique. Despite the constant SFE, with increasing Mn content the rolling textures change from the pure metal (copper) type towards the alloys (brass) type. This effect is attributed to the altered deformation behaviour as well as the increased tendency to form shear bands due to the large increase in strength of the Cu–Mn alloys.

The Sulfidation of Two-Phase Fe-Cu Alloys in H2-H2S Mixtures at 500-700°C

The sulfidation behavior of three two-phaseFe-Cu alloys containing 25, 50, and 75 wt.% copper hasbeen investigated in H2-H2Smixtures at 500-700°C under gas-phase sulfur pressures, which is significantly abovethose for the dissociation of both FeS andCu2S. In all cases, the three alloyssulfidized more slowly than both pure metals under thesame conditions. At all temperatures, Fe-25Cu showed the slowestgrowth rates, whereas Fe-50Cu sulfidized more rapidlythan the other two alloys. However, the kinetics curvesfor the three alloys tended to overlap, particularly at the higher temperatures. The scales werecomplex and contained an outer layer composed of amixture of two different Cu-Fe double sulfides,Cu5FeS4 and CuFeS2,plus an inner zone containing a mixture of metalliciron with the double sulfideCu5FeS4formed by completesulfidation of the copper-rich phase and partialsulfidation of the iron-rich phase. This region also contained large voids,possibly because of outward diffusion of metal cations,whereas the iron-rich islands were mainly unattacked.The depth of internal attack increased with increasing temperature and/or iron content. Finally,particles of almost pure copper metal, probably formedduring cooling from the reaction temperature, werepresent at the scale-subscale interface, as inclusions in the scale and as whiskers protruding out ofthe external scale surface.

Effect of chloride concentration range on the corrosion resistance of Cu–xNi alloys

The anodic behaviour of Cu–xNi alloys and Cu and Ni metals was studied in slightly alkaline solutions containing Cl−-ions in the concentration range from 0.01 to 2.0moldm−3. The morphology and composition of the surface films formed by anodic polarization were analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). On the basis of quasi-potentiodynamic polarization data, Ec against cNaCl diagrams were constructed, where Ec is the critical pitting potential. These diagrams allow the determination of areas where the materials are susceptible to localized pitting attack. A critical chloride concentration (ccrit) exists below which the resistance to localized corrosion increases with decreasing nickel content and above which it increases with increasing nickel content. This effect is connected with the change in the corrosion resistance observed for the pure metal constituents, i.e., copper and nickel as a function of chloride concentration. The kinetic parameters of pitting corrosion of Cu–xNi alloys reflect the specific properties of both elements and suggest that an increase in Ni content above 40% would not have a significant effect on the corrosion resistance of Cu–xNi alloys.

Electrodeposition of Copper and Copper‐Aluminum Alloys from a Room‐Temperature Chloroaluminate Molten Salt

The electrodeposition of copper and copper‐aluminum alloys was investigated in the Lewis acidic aluminum chloride‐1‐methyl‐3‐ethylimidazolium chloride (60.0–40.0 mol %) molten salt containing electrogenerated Cu(I) at 40 ± 1°C. Sampled current and rotating ring‐disk electrode voltammetry experiments indicated that it was possible to produce Cu‐Al alloy deposits at potentials positive of that corresponding to the electrodeposition of bulk aluminum (∼0 V). For a solution of Cu(I), the onset of the aluminum codeposition process was found to occur at around 0.30 V vs. the Al(III)/Al couple; however, a limiting current for the reduction of Cu(I) to pure copper metal can be observed in the 0.60–0.30 V potential interval in this solution. The Cu‐Al alloy composition was found to be independent of the Cu(I) concentration, reaching a maximum value of 43 percent atomic fraction aluminum at 0 V. The surface morphology of bulk Cu‐Al alloy electrodeposits was highly dependent on the aluminum content; pure copper deposits had a dense, nodular appearance, whereas deposits containing appreciable amounts of aluminum consisted of fragile dendrites. X‐ray diffraction studies indicated that Cu‐Al deposits containing about 7.2 percenter atomic fraction Al retained the face‐centered cubic (fcc) copper structure; however, deposits containing 12.8 percent atomic fraction Al were two‐phase with the second phase tentatively identified as martensitic . This phase appears to form before fcc copper becomes saturated with aluminum.

Synthesis, Characterization, and Properties of Metallic Copper Nanoparticles

Nanoscale particles of metallic copper clusters have been prepared by two methods, namely the thermal reduction and sonochemical reduction of copper(II) hydrazine carboxylate Cu(N2H3COO)2·2H2O complex in an aqueous medium. Both reduction processes take place under an argon atmosphere over a period of 2−3 h. The FT-IR, powder X-ray diffraction, and UV−visible studies support the reduction products of Cu2+ ions as metallic copper nanocrystallites. The powder X-ray analysis of the thermally derived products show the formation of pure metallic copper, while the sonochemical method yields a mixture of metallic copper and copper oxide (Cu2O). The formation of Cu2O along with the copper nanoparticles in the sonochemical process can be attributed to the partial oxidation of copper by in situ generated H2O2 under the sonochemical conditions. However, the presence of a mixture of an argon/hydrogen (95:5) atmosphere yields pure copper metallic nanoparticles, which could be due to the scavenging action of the hydroge...

Syntheses of copper nanoparticles in gelified microemulsion and in reverse micelles

Syntheses of nanosized copper crystallites have been carried out in reverse micelles and in gelified microemulsion. The self assemblies have been prepared by using a mixture of sodium and copper di(2-ethylhexyl) sulphosuccinate as surfactants. In reverse micelles, at low water content (w=[H 2O]/[AOT]<6), pure metallic copper particles are observed whereas at relatively high water content (w>6) the oxidation of metallic particles cannot be prevented. At w=10, pure copper oxide nanoparticles are observed. In gelified microemulsion (w=70), metallic nanoparticles are obtained. Their stability with time is rather long. Oxidation occurs after several days. This indicates a drastic change in the mechanism and rate of particle growth in the gelled systems as compared with those in reverse micelles.

Deposition rate and morphology of electroless copper film from solutions containing 2,2′-dipyridyl

Crystal structure and surface morphology of electroless copper films deposited from solutions containing 2,2′-dipyridyl were investigated by X-ray diffraction and electron microscopic observations. The deposition rate of copper was remarkably affected by bath temperature and 2,2′-dipyridyl concentration. Although Cu 2O was codeposited in the copper film prepared at 30 °C, pure metallic copper was obtained at 70 °C regardless of dissolved O 2. The surface morphology of the copper deposit plated at 30 °C exhibited a fine grain structure, while a coarse grain structure was observed for the copper deposit plated at 70 °C. Changes in crystal structure and surface morphology of the copper films are discussed as a function of deposition rate.

Nucleation and growth mechanisms of copper MOCVD film on Au/Si substrates

Low pressure chemical vapor deposition of copper from copper(II) hexafluoroacetylacetonate [Cu(hfa) 2] on different thicknesses of pre-deposited gold on a silicon substrate has been studied to determine the initial deposition mechanisms of nucleation and growth. The surface morphology changes of pre-deposited 30 Å thick gold films were observed during heat treatment under hydrogen; fine, uniform close packed gold particle changed into agglomerated island formations on the surface leading to dinscontinuities covering only 20% of the overall Si surface as a result of surface diffusion. Pure metallic copper films were obtained on the agglomerated substrate. When pre-deposited 1500 Å thick gold film was used as a substrate, the deposited film on the gold substrate was not a pure copper but consisted of a CuAu compound at the interface as a result of strong interdiffusion from the gold and copper atomic interaction. Thermally-induced interdiffusion may thus change the film properties and the microstructure of the deposited film under the experimental conditions.

Effect of the mode of plastic deformation on the formation of the alloy-type texture

The aim of this work was to explore the role of heterogeneous deformation in the formation of the alloy-type texture. Recent works on the role of the deformation mode in evolution of the deformation texture seem to shed new light on the problem of texture formation. In particular it has been shown, that the texture typical for pure fcc metals (copper type texture), may be easily converted into the B-component of the alloy type texture (brass texture) due to shear banding induced during cross-rolling. It was proved that deformation in shear bands is a simple transgranular shear (micro-shearband) which makes the polycrystalline metal behave like a single crystal oriented for the single system slip. In view of these results, it seems necessary to re-examine the problem of the formation of the brass type texture during monotonic rolling. In particular, there is no experimental information about the spatial orientation of shear bands in the test piece of brass, except that they occurs on average on lateral face of sample, at 35{degree} with respect to the rolling direction. This does not suffice yet to conclude whether the position of shear in brass is the same as in copper. It may as wellmore » be expected, that if the deformation in shear bands in brass is not a plane strain deformation with respect to the sample reference system or, in other words, the sample transverse direction does not lie in the plane of shear, the formation of shear bands may systematically lead to splitting of the metal type texture (resulting from homogeneous deformation) according to the geometry of shear bands. The problem of the spatial orientation of shear bands in monotonically rolled brass and of the evolution of the texture pattern is discussed in this work.« less

Extended x-ray-absorption fine-structure studies on ball-milled powders of the immiscible system Cu-V.

The extended x-ray-absorption fine structure (EXAFS) of mechanically alloyed ${\mathrm{Cu}}_{50}$${\mathrm{V}}_{50}$ and ${\mathrm{Cu}}_{30}$${\mathrm{V}}_{70}$, which were obtained from ball milling of a mixture of pure metallic copper and vanadium powders, has been studied. A significant change in the copper K x-ray-absorption spectra was observed as the milling time increased, while the basic oscillation pattern of the vanadium K EXAFS did not change so much. This indicates that a supersaturated solid solution is formed such that copper atoms enter into the bcc vanadium lattice in spite of their extremely limited dissolubility in the phase diagram. It was also observed that the destruction of the fcc structure of copper proceeds prior to the formation of the solid solution in the early stage of mechanical alloying.

Contribution of thermal conductivity to the crystal-regrowth velocity of embedded-atom-method-modeled metals and metal alloys.

The regrowth velocity of a crystal from a melt depends on contributions from the thermal conductivity, heat gradient, and latent heat. The relative contributions of these terms to the regrowth velocity of the pure metals copper and gold during liquid-phase epitaxy are evaluated. These results are used to explain how results from previous nonequilibrium molecular-dynamics simulations using classical potentials are able to predict regrowth velocities that are close to the experimental values. Results from equilibrium molecular dynamics showing the nature of the solid-vapor interface of an embedded-atom-method-modeled ${\mathrm{Cu}}_{57}$${\mathrm{Ni}}_{43}$ alloy at a temperature corresponding to 62% of the melting point are presented. The regrowth of this alloy following a simulation of a laser-processing experiment is also given, with use of nonequilibrium molecular-dynamics techniques. The thermal conductivity and temperature gradient in the simulation of the alloy are compared to those for the pure metals.

A study of the chemical shift of the x-ray absorption K-edge of copper in some Cu(II) systems

We have recorded X-ray absorption K-edge spectra of Cu in some copper (II) compounds (NH 4) 2SO 4·CuSO 4·6H 2O, CuCl 2·2H 2O, CuSO 4·5H 2O,CuO, Cu(OH) 2, La 2CuO 4, CuWO 4 and CuCO 3·Cu(OH) 2, including pure copper metal using a Cauchois-type bent-crystal X-ray spectrograph. We have also measured the X-ray absorption chemical shift, Δ E, in each of the above Cu(II) compounds and have correlated the chemical-shift, Δ E, with its two governing factors the effective charge, q, and the bond length, R, on the basis of the least-squares regression analysis. The same correlation has been used to determine the bond lengths in some other Cu(II) compounds. The values of the bond length so obtained agree fairly well with those of their crystallographic values.

Sliding friction and wear of metals in vacuum

Sliding friction and wear in vacuum were studied for 16 combinations of four pure metals (copper, nickel, iron and molybdenum) from the points of view of adhesion energy and hardness ratio H d / H p (ratio of hardness of disk to hardness of pin) before and after the test. It was found that severe wear usually occurred when the range of hardness ratio H d / H p after the test included values below about 1.0. Mild wear typically occured when this ratio included only values above about 1.0. It was also found that friction and wear behaviour were dependent on the adhesion energy and the crystal structure. Mutual transfer was observed in both wear modes for every combination of different metals. Transfer ranged from widely scattered local transfer to relatively uniform transfer. Three types of wear debris were observed in severe wear: plate-like, wedge-like and cylindrical-spherical debris. Although wear debris consisted mainly of disk material, it also commonly contained pin material existing as small scattered pieces. The size of wear debris was strongly dependent on the hardness of the disk material and the adhesion energy. The data from self-mated tests were consistent with those using two different metals.

Native copper included by anorthite from the island of Miyakejima: implications for arc magmatism.

Dark-brown micro-minerals scattering in the wine red part of lava-coated anorthite megacryst, from the island of Miyakejima, were identified as native copper by using the conventional EPMA equipment and the enhanced X-ray microdiffractometer of a new type developed by the authors. Tiny lamellae of these native coppers are distributed on ( ?? 04) of anorthite. Their chemical compositions are near pure copper metal, whereas the anorthite around their coppers is slightly rich in silica and contains a small amount of chlorine. Comparison with the X-ray CuLα and CuLβ spectra, measured by EPMA, of native and metallic coppers, and cuprite and tenorite, brings out that the peak shift and band shape of CuLα radiation from this Cu inclusion agree well with those of native and metallic coppers. The present microscopical investigation implies that after exsolution of the H3CuSi3O8 feldspar endmember possibly forming a solid solution of the primary anorthite, decomposition of this Cu-bearing feldspar in the process of descent temperature conduces to yielding native coppers and the anorthite slightly rich in SiO2. The present paragenesis of euhedral anorthite megacrysts including native coppers with fused olivines asserts that there is some high temperature region (>1400°C) underneath Miyakejima, namely beneath a volcanic front and over the subduction zone, where such an idiosyncratic anorthite can crystallize.

Standardization of dilute solutions of EDTA by photometric titration with standard tetraamminecopper(II) titrant

Direct photometric titration (without an added indicator) using a standard ammoniacal solution of copper(II) prepared from pure copper metal asa primary standard is recommended as a reliable method for the standardization of Na2H2(edta) in 10-3 -5 . 10-4M solutions. The technique of photometric microtitration (720 nm, 50 mm cell) with an increased precision of transmittance reading (s ~10-2%, n &gt; 7) and in optimum medium of pH 4.7 ± 0.4 (acetate buffer) can yield precise results in assays of EDTA (sr ⪬ 10-1%, n = 6-9).

Displacement reactions during mechanical alloying

The occurrence of simple solid-state displacement reactions during mechanical alloying has been investigated. The reduction of cupric oxide to pure copper metal by a variety of metallic reducing agents was studied, and the powders were examined by X-ray diffractometry and electron microscopy. When milled with a liquid process control agent, the reaction progressed gradually with time, whereas an unstable combustion reaction occurred when no such control agent was employed. A minimum adiabatic temperature of 1300 K is necessary for combustion to occur in these systems. The reaction enthalpy is an important factor in determining the precombustion period. The as-milled powders consisted of finely divided, nanometer-sized crystallites with an extremely high defect density. It is proposed that the increased reactivity of the system arises through the unique conditions prevailing during mechanical alloying.