Study of the Coarsening of Nanoporous Gold Nanowires by In Situ Scanning Transmission Electron Microscopy During Annealing

Chauvin, Adrien; Molina‐Luna, Leopoldo; Ding, Junjun; Choi, Changhwan; Mel, Abdel‐Aziz El

doi:10.1002/pssr.201900376

Cited by 7 publications

(9 citation statements)

References 44 publications

(107 reference statements)

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“…Recent kinetic Monte Carlo and molecular dynamics simulations also revealed that structures with a low relative density exhibited a surface stress-driven dislocation movement leading to coarsening by ligament collapse 22 . This mechanism was also further supported by observation via in situ transmission electron microscopy in 2D 76 .…”

Section: Resultssupporting

confidence: 57%

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

Liu

Ronne

et al. 2021

Nat Commun

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Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.

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Section: Resultssupporting

confidence: 57%

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

Liu

Ronne

et al. 2021

Nat Commun

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“…The majority of thin-film studies on NPG’s morphology evolution have been focused on near room temperature dealloying (i.e., 20–90 °C) at large time scales (i.e., when the residual Ag content is negligible, typically between 0 and 5 at. %), and on annealing post-treatments of dealloyed samples. − At large dealloying time scales, pore coarsening is driven by thermally activated surface diffusion to minimize curvature and surface energy of the metastable nanoporous structure . This is the case because Ag is generally assumed to be depleted and to have a minimal effect on the coarsening process. , However, at short dealloying time scales (i.e., when the residual Ag content is greater than 5 at.…”

Section: Resultsmentioning

confidence: 99%

Electroless Dealloying of Thin-Film Nanocrystalline Au–Ag Alloys: Mechanisms of Ligament Nucleation and Sources of Its Synthesis Variability

Niauzorau

Sharstniou

Sampath

et al. 2022

ACS Appl. Mater. Interfaces

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Control of ligament size in nanoporous gold through process inputs in chemical dealloying holds the potential to exploit its size dependent properties in applications in energy and biomedicine. While its morphology evolution is regulated by the kinetics of coarsening, recent studies are focused on the early stage of dealloying (e.g., ∼ 5−42 at. % in residual alloy content) to understand mechanisms of ligament nucleation and its role in altering process−structure relationships. This paper examines this stage in chemical dealloying of nanocrystalline Au 49 Ag 51 thin films and finds that ligaments are nucleated uniformly through its thickness due to the dealloying front rapidly propagating through the thickness of the film. Further, through the establishment of process−structure relationships with large data sets (i.e., 80 samples), this paper quantifies sources of variability that alter the kinetics of ligament growth such as aging of the precursor (e.g., grain growth) and solution evaporation. It is found that ligament diameter is better predicted by the residual silver content rather than by the dealloying time even amidst both effects and independent control of ligament diameter and solid area fraction is demonstrated within a limited window.

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“…The SEM images were collected and analyzed from our measurements and the literature [ 19 , 20 , 21 , 22 , 23 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ] with Fiji [ 42 ]. Binary images were obtained by converting solid and voids into 1 and 0 values, and then different procedures were applied to obtain the microstructural information:…”

Section: Methodsmentioning

confidence: 99%

Effects of the Parent Alloy Microstructure on the Thermal Stability of Nanoporous Au

et al. 2022

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Nanoporous (NP) metals represent a unique class of materials with promising properties for a wide set of applications in advanced technology, from catalysis and sensing to lightweight structural materials. However, they typically suffer from low thermal stability, which results in a coarsening behavior not yet fully understood. In this work, we focused precisely on the coarsening process undergone by NP Au, starting from the analysis of data available in the literature and addressing specific issues with suitably designed experiments. We observe that annealing more easily induces densification in systems with short characteristic lengths. The NP Au structures obtained by dealloying of mechanically alloyed AuAg precursors exhibit lower thermal stability than several NP Au samples discussed in the literature. Similarly, NP Au samples prepared by annealing the precursor alloy before dealloying display enhanced resistance to coarsening. We suggest that the microstructure of the precursor alloy, and, in particular, the grain size of the metal phases, can significantly affect the thermal stability of the NP metal. Specifically, the smaller the grain size of the parent alloy, the lower the thermal stability.

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Study of the Coarsening of Nanoporous Gold Nanowires by In Situ Scanning Transmission Electron Microscopy During Annealing

Cited by 7 publications

References 44 publications

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography

Electroless Dealloying of Thin-Film Nanocrystalline Au–Ag Alloys: Mechanisms of Ligament Nucleation and Sources of Its Synthesis Variability

Effects of the Parent Alloy Microstructure on the Thermal Stability of Nanoporous Au

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