Mechanisms and Morphology Evolution in Dealloying

Chen, Qing; Sieradzki, Karl

doi:10.1149/2.064306jes

Cited by 78 publications

(66 citation statements)

References 32 publications

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“…21 Depending on Sn particle size and dealloying rate, they observed Kirkendall voids in dealloyed Sn particles as well as bi-continuous structures. Chen and Sieradzki also examined the dealloying behavior of Mg from Mg-Cd alloys at homologous temperatures in the range of 0.53-0.69 containing 65, 45 and 10 at.% Mg. 32 Dealloying of the 45 and 65 at.% alloys yielded bi-continuous structures while negative dendrites were reported for dealloying the 10 at.% Mg-Cd alloy.…”

Section: Previous Work Examining Morphology Evolution At High T Hmentioning

confidence: 95%

Dealloying at High Homologous Temperature: Morphology Diagrams

Geng

Sieradzki

2017

J. Electrochem. Soc.

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Dealloying under conditions of high homologous temperature, T H , (or high intrinsic diffusivity of the more electrochemically reactive component) is considerably more complicated than at low T H since solid-state mass transport is available to support this process. At low T H the only mechanism available for dealloying a solid is percolation dissolution, which results in a bicontinuous solid-void morphology for which nanoporous gold serves as the prototypical example. At high T H , there is a rich set of morphologies that can evolve depending on alloy composition and the imposed electrochemical conditions, including negative or void dendrites, Kirkendall voids and bi-continuous porous structures. We report on a study of morphology evolution upon delithiation of Li-Sn alloys, produced by the electrochemical lithiation of Sn sheets. Electrochemical titration and time of flight measurements were performed in order to determine the intrinsic diffusivity of Li,D Li , as a function of alloy composition, which ranged from ∼5 × 10 −8 -4 × 10 −12 cm 2 s −1 . The activation energy forD Li was measured in the temperature range 30-140 • C and found to be 37.4, 37.9 and 22.5 kJ/mole, respectively for the phases Li 2 Sn 5 , LiSn and Li 7 Sn 3 . Morphology evolution was studied under conditions of fixed dealloying potential and fixed current density and our results are summarized by the introduction of dealloying morphology diagrams that reveal the electrochemical conditions for the evolution of the various morphologies. Today electrochemical dealloying processes are used to design nanostructures for a variety of functions encompassing electrocatalysis 1-3 and biosensors 4-7 with additional applications being explored such as actuation [8][9][10][11] and structural composites. 12-14 To date, the targeted nanoscale morphologies include bi-continuous structures such as nanoporous gold (NPG) formed by a percolation dissolution mechanism 15-18 and so-called skin or core-shell nanoparticle structures, formed by a passivation-like process.2 Several of these architectures are employed in the fabrication of Pt-based alloy nanoparticle electrocatalysts for fuel cell applications, 1,3,19 Since the solid-state transport processes available to support selective dissolution are temperature dependent one should expect the resulting morphologies to be similarly dependent on temperature. For example, in a noble metal alloy such as Ag-Au at 300 K (i.e., low homologous temperature) the diffusivity of each of the components is of order 10 −32 cm 2 s −120 which is about 20 orders of magnitude too low to contribute to dealloying processes over technologically relevant time scales. Consequently, percolation dissolution is the only mechanism available for dealloying resulting in the well-studied morphology of NPG. However, at higher homologous temperature, T H , we should expect additional sets of dealloying morphologies to evolve. Here our use of the term high T H is meant to designate that the solid-state mobility of the component that is selecti...

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Section: Previous Work Examining Morphology Evolution At High T Hmentioning

confidence: 95%

Dealloying at High Homologous Temperature: Morphology Diagrams

Geng

Sieradzki

2017

J. Electrochem. Soc.

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“….) depend mainly on the initial chemical composition of the alloy, the concentration of the nitric acid, the dealloying time as well as the dealloying temperature [9,51,58,59].…”

Section: Introductionmentioning

confidence: 99%

Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

Bouts

Mel

Angleraud

2015

Carbon

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“…Sieradzki et al proposed a percolation mechanism of dealloying based on the concept that above a critical concentration there exist continuous atomic scale conduits of the more reactive component allowing selective dissolution to happen. [31][32][33][34] It could be assumed here that, due to the simultaneous dissolution processes that had occurred for β phase before t c , the percolation threshold had been reached. Furthermore, Sieradzki et al showed that the transition from simultaneous dissolution to selective dissolution corresponded to the growth of a macroscopic three-dimensional dealloyed structure which defined a roughening transition with a competition between dissolution of the more active component leading to surface roughening and the curvature-driven surface diffusion of the more noble component.…”

Section: Discussionmentioning

confidence: 99%

“…The discussion focuses on the dissolution mechanism with reference to the α-brass dissolution processes proposed in the literature. [1][2][26][27][28][29][30][31][32][33][34][35]…”

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confidence: 99%

Dissolution Kinetics of α,β^′-Brass in Basic NaNO₃Solutions

Berne

Andrieu

Reby

et al. 2015

J. Electrochem. Soc.

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Corrosion tests at a constant anodic potential, referred to as dissolution tests, were performed to determine the dissolution kinetics of an α,β′-brass CuZn40Pb2 (CW617N) in a basic nitrate solution with and without mechanical loading. The corrosion behavior of the α,β′-brass was characterized by a two-step mechanism, with an initiation step for which the simultaneous dissolution of all the alloying elements of the β′ phase occurred only and a propagation step including at first, the afore-mentioned simultaneous dissolution process before a critical time tc and then, both simultaneous dissolution and dezincification of the β′ phase after tc. The pH and Cu concentration of the electrolyte near the brass surface were determined to be two of the major factors influencing the occurrence of the dezincification process. The dezincification of the β′ phase extended in depth by a percolation dissolution mechanism. Mechanical loading during the dissolution tests was observed to largely influence the dezincification process. It was assumed to open or close the pores present in the dezincified β′ phase, which promoted or slowed down the dezincification mechanism depending on the sign of the stress.

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Mechanisms and Morphology Evolution in Dealloying

Cited by 78 publications

References 32 publications

Dealloying at High Homologous Temperature: Morphology Diagrams

Dealloying at High Homologous Temperature: Morphology Diagrams

Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

Dissolution Kinetics of α,β^′-Brass in Basic NaNO₃Solutions

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Mechanisms and Morphology Evolution in Dealloying

Cited by 78 publications

References 32 publications

Dealloying at High Homologous Temperature: Morphology Diagrams

Dealloying at High Homologous Temperature: Morphology Diagrams

Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

Dissolution Kinetics of α,β′-Brass in Basic NaNO3Solutions

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Dissolution Kinetics of α,β^′-Brass in Basic NaNO₃Solutions