In situ observation of stress induced grain boundary migration in nanocrystalline gold

Wang, Li Hua; Xin, Tianjiao; Kong, Deli; Shu, Xinyu; Chen, Yanhui; Zhou, Hao; Teng, Jun; Zhang, Ze; Zou, Jin; Han, Xiao

doi:10.1016/j.scriptamat.2017.03.003

Cited by 69 publications

(20 citation statements)

References 39 publications

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“…For example, pure grain rotation mechanism has been confirmed by Shan et al 58 in d~10nm nc-Ni, pure stress-driven GB migration mechanism has been confirmed by Wang et al 59 in d~18 nm nc-Au and pure GB sliding mechanism has been confirmed by Kumar et al 68 in d~30 nm. In the aspect of cooperative mechanisms, limited studies such as by Wang et al 35,59 confirm that grain rotation can cooperate and accommodate with stress-driven grain growth during the tensile deformation processes of nc-Pt and nc-Au, consistent with the previous results of computer simulations and theoretical predictions. However, so far cooperative GB sliding mechanism proposed from computer simulations and theoretical predictions is yet to be confirmed by direct experimental observations.…”

Section: Introductionsupporting

confidence: 80%

“…Thus, metallic nanofilms are ideal materials for in-situ observations of stress-driven GB migration because GB diffusional processes can be greatly enhanced in 2D-nanofilms. For example, Wang et al 59 This Au nanoparticle spontaneous coalescence process was accomplished by the rapid GB diffusional migration processes.…”

Section: Stress-driven Grain Growthmentioning

confidence: 99%

“…Basically, grain rotation 36,40,42,45,[47][48][49][50][51][56][57][58][59][60] , stress-driven grain growth 31,32,[37][38][39][40]42,43,46,47,49,50,53,55,56,59,[61][62][63][64] and GB sliding 17,41,44,55,[65][66][67][68][69][70] are mainly investigated in the of GBsmediated mechanisms regime. Computer simulation studies and theoretical calculation prediction studies suggested that GBs-mediated deformation mechanisms are able to perform individually, or alternatively cooperate and accommodate with each other in the deformation processes of nc-metals.…”

Section: Introductionmentioning

confidence: 99%

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In-situ nanoscale TEM observation of cooperative deformation mechanisms in nanocrystalline-Au films

Li¹

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Grain boundaries activities are important for the deformation of nanocrystalline metals.Studies revealed that deformation mechanisms of nanocrystalline metals switch from dislocation-mediated regime to grain-boundary-mediated regime as approaching the "strongest" grain size. Basically, stress-driven grain growth, grain rotation and grain boundary sliding have been widely studied and discussed in the aspect of grain-boundary-mediated deformation mechanisms in nanocrystalline metals. Based on the previous studies, these grain-boundarymediated deformation mechanisms could perform in either individual forms or cooperative forms. However, limited studies have been focused on the cooperative form mechanisms for the grain-boundary-mediated deformation mechanism, especially for the cooperative grain boundary sliding mechanisms which could lead to more ductile performance than the pure grain boundary sliding. Particularly, only a few molecular dynamic simulation studies and theoretical prediction studies investigated the cooperative grain boundary sliding mechanism in nanocrystalline metals. Therefore, it is necessary to practically examine the true deformation behaviours in straining nanocrystalline metals.In this MPhil project, with utilising the homemade tensile device equipped with a transmission electron microscopy heating holder, in-situ transmission electron microscopy tensile tests are conducted for the magnetic-sputtering-fabricated nanocrystalline Au thin films (thickness ~ 15nm, average grain size ~ 16nm). In the in-situ experiments, the dynamic crack propagation processes of strained nanocrystalline Au films are clearly recorded under nanoscale bright-field TEM mode. It has been found that grain boundary sliding and stress-driven grain boundary migration are prevalent during the deformation processes. As cooperative deformation mechanism, stress-driven grain boundary migration assisted grain boundary sliding is confirmed experimentally. It is also found that cooperative grain boundary sliding mechanism

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Section: Introductionsupporting

confidence: 80%

Section: Stress-driven Grain Growthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In-situ nanoscale TEM observation of cooperative deformation mechanisms in nanocrystalline-Au films

Li¹

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“…Previously, it has been observed that the grain structures of polycrystalline Au films can be altered dramatically when the deformation exceeds the elastic limit of Au, 35 and Au nanostructures undergo plastic deformation when the compressive strain is larger than 5%. 36 We attribute the increased XRD intensities of Au-30 and Au-70 to preferred grain orientation, which was introduced by compression. 37 We performed two control experiments to investigate if the heating temperature and the orientation of the folds with respect to the x-ray beam would affect the intensity of the XRD patterns ( Figure S3) and we did not observe any obvious changes in both cases.…”

mentioning

confidence: 90%

“…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).…”

mentioning

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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In-Situ Nanomechanical TEM

Zhong¹,

Wang²,

Wang³

et al. 2023

In-Situ Transmission Electron Microscopy

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In situ observation of stress induced grain boundary migration in nanocrystalline gold

Cited by 69 publications

References 39 publications

In-situ nanoscale TEM observation of cooperative deformation mechanisms in nanocrystalline-Au films

In-situ nanoscale TEM observation of cooperative deformation mechanisms in nanocrystalline-Au films

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

In-Situ Nanomechanical TEM

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