Initiation and stagnation of room temperature grain coarsening in cyclically strained gold films

Глушко, Олександр; Dehm, Gerhard

doi:10.1016/j.actamat.2019.03.004

Cited by 20 publications

(11 citation statements)

References 42 publications

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“…Images of rapidly grown grains near stagnant grains are shown in Figures 1 and 2. The secondary grain growth is also associated with the development of the sample texture [31][32][33] due to the selective rapid grain growth of certain orientations as mentioned earlier. This is also demonstrated in Figure 2b for the thin area heated in-situ when compared to the ex-situ bulk material results (Figure 2c) or the thick region of the in-situ results (Figure 2d).…”

Section: Discussionmentioning

confidence: 71%

Limitations of Thermal Stability Analysis via In-Situ TEM/Heating Experiments

et al. 2021

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This work highlights some limitations of thermal stability analysis via in-situ transmission electron microscopy (TEM)-annealing experiments on ultrafine and nanocrystalline materials. We provide two examples, one on nanocrystalline pure copper and one on nanocrystalline HT-9 steel, where in-situ TEM-annealing experiments are compared to bulk material annealing experiments. The in-situ TEM and bulk annealing experiments demonstrated different results on pure copper but similar output in the HT-9 steel. The work entails discussion of the results based on literature theoretical concepts, and expound on the inevitability of comparing in-situ TEM annealing experimental results to bulk annealing when used for material thermal stability assessment.

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Section: Discussionmentioning

confidence: 71%

Limitations of Thermal Stability Analysis via In-Situ TEM/Heating Experiments

et al. 2021

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“…The room temperature deposition yields alignment of the (111) plane in Cu parallel to the (0001) sapphire planes, while Cu might get random in-plane orientations. − Upon annealing, the microstructure evolves with grain growth with several tilt GB types. The driving force for the abnormal grain growth mechanism is not fully understood yet, since it is affected by several factors, for example, local curvature of GBs, mobility of triple points, surface steps of the substrate, and misorientation-dependent in-plane coherency stress. − …”

Section: Resultsmentioning

confidence: 99%

Understanding Grain Boundary Electrical Resistivity in Cu: The Effect of Boundary Structure

et al. 2021

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Grain boundaries (GBs) in metals usually increase electrical resistivity due to their distinct atomic arrangement compared to the grain interior. While the GB structure has a crucial influence on the electrical properties, its relationship with resistivity is poorly understood. Here, we perform a systematic study on the resistivity–structure relationship in Cu tilt GBs, employing high-resolution in situ electrical measurements coupled with atomic structure analysis of the GBs. Excess volume and energies of selected GBs are calculated using molecular dynamics simulations. We find a consistent relation between the coincidence site lattice (CSL) type of the GB and its resistivity. The most resistive GBs are in the high range of low-angle GBs (14°–18°) with twice the resistivity of high angle tilt GBs, due to the high dislocation density and corresponding strain fields. Regarding the atomistic structure, GB resistivity approximately correlates with the GB excess volume. Moreover, we show that GB curvature increases resistivity by ∼80%, while phase variations and defects within the same CSL type do not considerably change it.

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“…This is consistent with previous studies on cyclic plastic deformation of Au thin films that indicate that mechanical deformation can alter grain energetics and drive grain coarsening. 35,36,38,39 Also, the electron diffraction analysis indicates that the compression did not introduce new crystal planes in Au-70 ( Figure 2c).…”

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confidence: 92%

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

Kwok¹,

Wang²,

Cao³

et al. 2019

Preprint

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The local structure and geometry of catalytic interfaces can influence the selectivity of chemical reactions. Here, using a pre-strained polymer, we uniaxially compress a thin gold film to form a nano-folded catalyst. We observe two kinds of folds and can tune the ratio of loose to tight folds by varying the extent of pre-strain in the polymer. We characterize the nano-folded catalysts using x-ray diffraction, scanning, and transmission electron microscopy. We observe grain reorientation and coarsening in the nano-folded gold catalysts. Electroreduction of carbon dioxide with these nano-folded catalysts reveals an enhancement of Faradaic efficiency for carbon monoxide formation by a factor of about four. This result suggests that electrolyte mass transport limitations and an increase of the local pH in the tight folds of the catalyst outweigh the effects of alterations in grain characteristics. Together, our studies demonstrate that nano-folded geometries can significantly alter grain characteristics, mass transport, and catalytic selectivity.Electroreduction of carbon dioxide (CO2) to valuable carbon-rich products is a potential solution to end the anthropogenic carbon cycle. 1,2 However, slow kinetics and reduced control over product yield and selectivity have hindered widespread commercial viability. 3,4 Nanostructured catalysts offer the potential to address these limitations. 5 Indeed, a variety of nanoparticles, 6-9 thin films, 10-14 and nanoporous materials 15-18 have been explored, but there are still challenges with scalability, reproducibility, extreme reaction conditions, and cost. 6,10,12,15 Mechanical wrinkling of metallic thin films using pre-strained polystyrene (PS) substrates offers a reproducible strategy to create nanostructured interfaces. This approach is compatible with nanoparticles, 19 nanoporous, 20 thin films, 21,22 and twodimensional (2D) materials (e.g. graphene and MoS2), 23-28 and the morphology can be controlled using lithography. 24,25,29,30 Previous studies with wrinkled catalysts show improvement in different electrochemical reactions including hydrogen evolution reaction (HER), 25,27,28,30 glucose sensing, 31 and DNA detection. 32 For example, wrinkled platinum (Pt) arrays electrodes improved the performance of HER from ~70 mA/cm 2 to ~ 120 mA/cm 2 at 0.1 V as compared to conventional Pt on carbon. This improvement was attributed to weak adhesion of hydrogen (H2) gas bubbles, resulting in a lower overpotential.Here, for the first time, we present evidence that a nano-folded gold (Au) catalyst can improve the selectivity of CO2 reduction. We utilized a pre-strained PS substrate to uniaxially compress and create a novel Au catalyst with a combination of loose (>200

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Initiation and stagnation of room temperature grain coarsening in cyclically strained gold films

Cited by 20 publications

References 42 publications

Limitations of Thermal Stability Analysis via In-Situ TEM/Heating Experiments

Limitations of Thermal Stability Analysis via In-Situ TEM/Heating Experiments

Understanding Grain Boundary Electrical Resistivity in Cu: The Effect of Boundary Structure

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

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