Diffusion in aqueous copper sulfate and copper sulfate-sulfuric acid solutions

Noulty, Robert A.; Leaist, Derek G.

doi:10.1007/bf00650751

Cited by 19 publications

(18 citation statements)

References 31 publications

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“…The fitted I lim (Figure 5d) verifies this scaling at low concentration and deviates to lower values at high concentration, consistent with reduced Cu 2+ activity and diffusivity. 62 A simple estimate (red curve), using free-solution values 63 Consistent with our analysis of OLC below, the leading cause of the enhanced dispersion inferred from I lim may be electro-osmotic convection in the glass frit. Electro-osmotic flow toward the impermeable membrane/cathode structure is balanced by a pressure-driven back flow that produces dispersion.…”

Section: Limiting Currentsupporting

confidence: 69%

Overlimiting Current and Shock Electrodialysis in Porous Media

et al. 2013

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Most electrochemical processes, such as electrodialysis, are limited by diffusion, but in porous media, surface conduction and electroosmotic flow also contribute to ionic flux. In this article, we report experimental evidence for surface-driven overlimiting current (faster than diffusion) and deionization shocks (propagating salt removal) in a porous medium. The apparatus consists of a silica glass frit (1 mm thick with a 500 nm mean pore size) in an aqueous electrolyte (CuSO4 or AgNO3) passing ionic current from a reservoir to a cation-selective membrane (Nafion). The current-voltage relation of the whole system is consistent with a proposed theory based on the electroosmotic flow mechanism over a broad range of reservoir salt concentrations (0.1 mM to 1.0 M) after accounting for (Cu) electrode polarization and pH-regulated silica charge. Above the limiting current, deionized water (≈10 μM) can be continuously extracted from the frit, which implies the existence of a stable shock propagating against the flow, bordering a depleted region that extends more than 0.5 mm across the outlet. The results suggest the feasibility of shock electrodialysis as a new approach to water desalination and other electrochemical separations.

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Section: Limiting Currentsupporting

confidence: 69%

Overlimiting Current and Shock Electrodialysis in Porous Media

et al. 2013

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“…Many chemical, geochemical, and industrial processes involve diffusive transport of aqueous electrolytes (Anderson and Graf, 1978;Felmy and Weare, 1991;Noulty and Leaist, 1987;Steefel and Lichtner, 1994). Diffusion coefficients are also part of the transport data required for calculation of various types of generalized transport coefficients (Miller, 1966(Miller, , 1967a(Miller, ,b, 1981Zhong and Friedman, 1988).…”

Section: Introductionmentioning

confidence: 99%

Ternary Solution Mutual Diffusion Coefficients and Densities of Aqueous Mixtures of NaCl and Na₂SO₄ at 298.15 K for Six Different Solute Fractions at a Total Molarity of 1.000 mol·dm^-³

and¹,

Gillespie²,

and³

et al. 1998

J. Chem. Eng. Data

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Isothermal mutual diffusion coefficients (interdiffusion coefficients) were measured for ternary aqueous mixtures of NaCl and Na2SO4 at a constant total molarity of 1.000 mol·dm-3 and 298.15 K. Measurements were performed using Rayleigh interferometry with computerized data acquisition at NaCl molarity fractions of z 1 = 1, 0.90, 0.75, 0.50, 0.25, and 0. Densities of the solutions were measured with a vibrating tube densimeter. At all ternary solution compositions, one cross-term diffusion coefficient has negative values whereas the other has positive values. These measurements supplement our earlier results at 0.500 mol·dm-3. Both main-term diffusion coefficients are significantly smaller at 1.000 mol·dm-3 than at 0.500 mol·dm-3 at any fixed value of z 1, whereas both cross-term coefficients are shifted in a positive direction. Trace diffusion coefficients D*(Cl-) and D*(S ) were extrapolated from these results for the Cl-(aq) ion in 1.0 mol·dm-3 Na2SO4(aq) and for the S (aq) ion in 1.0 mol·dm-3 NaCl(aq). Values of D*(Cl-) in Na2SO4(aq) and in NaCl(aq) were found to be essentially identical, as were D*(S ) in these same two electrolytes, provided the comparisons were made at the same volumetric ionic strengths.

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“…The diffusion layer thickness δ diff can be defined by equation 9, where ν is a kinematic viscosity, is a rotation rate, and D Cu + = 0.43×10 −5 cm 2 s −1 (D Cu + was assumed to be equal to the D Cu 2+ reported by Noulty et al). 38 …”

Section: Resultsmentioning

confidence: 99%

Pulse-Plating of Copper-Silver Alloys for Interconnect Applications

Volov

Swanson

O'Brien

et al. 2012

J. Electrochem. Soc.

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The electrodeposition of Cu-Ag alloys was studied as a possible application for interconnect technology, where Cu-Ag alloys may be less susceptible to electromigration than Cu alone. The presence of chloride in state-of-the-art copper plating electrolytes limited the solubility of Ag. However, pulse-plating approach enabled a wide range of Cu-Ag alloy compositions at substantial chloride concentration levels. The deposition of Ag was driven by the displacement reactions between the metallic copper and ionic silver during the off-time. Measured alloy compositions were consistent with theoretical estimates at various electrolyte concentrations, electrode rotation speeds, pulse frequencies and duty cycles. However, organic additives decreased incorporation of Ag into the alloy. It was also discovered that CuSO 4 · 5H 2 O from a number of major chemical suppliers contained Ag as an impurity. The roughness of the films was significant when produced by pulsed plating, but was shown to be substantially reduced in the presence of a leveling agent. Additionally, the concentration of chloride in the electrolyte was shown to significantly affect surface quality of the deposited Cu-Ag thin films. With the continuing miniaturization of microelectronics, electromigration effects in copper interconnect systems are becoming a major factor in determining device lifetime and reliability.1-3 Accordingly, there is a need for interconnect materials with improved electromigration resistance, while maintaining adequate electrical resistivity. It has been shown that co-deposits of Cu with small amount of other metals (such as Ag, Sn, Co, and Mg) can potentially mitigate both electro-and stress-migration.4-8 However, the resistivity of the interconnect increases with the addition of foreign metals. The International Technology Roadmap of Semiconductors (ITRS) has set the resistivity criterion at ρ < 2.2 μ · cm, 9 only slightly above the bulk resistivity of pure copper at 1.68 μ · cm. Alloying copper with silver (ρ Ag = 1.59 μ · cm) was shown to increase the resistivity of electrochemically deposited Cu-Ag films the least when compared to other copper alloys.10 For Ag content between 0.17 and 3.2 wt% the resistivity ranges 1.8 to 3.1 μ · cm.10 For this reason Cu-Ag alloys, especially at the lower Ag weight percentages, are potential candidates for the fabrication of interconnects in microelectronic devices.Acidic copper-sulfate electrolytes containing chloride have been successfully applied for many years to the electrochemical fabrication of copper interconnects. [11][12][13] Chloride in these electrolytes is known to be one of the critical constituents enabling defect-free filling of surface features.14-20 The main challenge for depositing silver from copper-plating electrolytes, which contain about 50 ppm of chloride, is the low solubility of silver in the presence of chloride ions (the solubility product of AgCl in water at 25• C is 1.8×10 We demonstrate that the application of a pulsating current instead of a direct current permits ...

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Diffusion in aqueous copper sulfate and copper sulfate-sulfuric acid solutions

Cited by 19 publications

References 31 publications

Overlimiting Current and Shock Electrodialysis in Porous Media

Overlimiting Current and Shock Electrodialysis in Porous Media

Ternary Solution Mutual Diffusion Coefficients and Densities of Aqueous Mixtures of NaCl and Na₂SO₄ at 298.15 K for Six Different Solute Fractions at a Total Molarity of 1.000 mol·dm^-³

Pulse-Plating of Copper-Silver Alloys for Interconnect Applications

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Diffusion in aqueous copper sulfate and copper sulfate-sulfuric acid solutions

Cited by 19 publications

References 31 publications

Overlimiting Current and Shock Electrodialysis in Porous Media

Overlimiting Current and Shock Electrodialysis in Porous Media

Ternary Solution Mutual Diffusion Coefficients and Densities of Aqueous Mixtures of NaCl and Na2SO4 at 298.15 K for Six Different Solute Fractions at a Total Molarity of 1.000 mol·dm-3

Pulse-Plating of Copper-Silver Alloys for Interconnect Applications

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Product

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About

Ternary Solution Mutual Diffusion Coefficients and Densities of Aqueous Mixtures of NaCl and Na₂SO₄ at 298.15 K for Six Different Solute Fractions at a Total Molarity of 1.000 mol·dm^-³