Bioinspired nanoporous silicon provides great toughness at great deformability

Garcia, Andre P.; Buehler, Markus J.

doi:10.1016/j.commatsci.2010.01.011

Cited by 56 publications

(48 citation statements)

References 29 publications

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“…The observation that a weakness is turned into strength is also reminiscent of recent findings of similar behaviors of H bonds, which are by themselves also highly brittle, weak elements but reach Data for the nanoporous silicon is retrieved from Ref. 22. Both the maximum stress and modulus are found to increase with the wall width.…”

Section: Discussionsupporting

confidence: 48%

“…The key contribution of this work is that, by introducing structural hierarchies, a weakness can be turned to strength, that is, an intrinsically strong but brittle material becomes exceedingly tough, strong, and ductile. The fact that a similar behavior was found in silicon [22] suggests that this may indeed be a generic design concept that could be used for many materials. The observation that a weakness is turned into strength is also reminiscent of recent findings of similar behaviors of H bonds, which are by themselves also highly brittle, weak elements but reach Data for the nanoporous silicon is retrieved from Ref.…”

Section: Discussionmentioning

confidence: 70%

“…Indeed, the effects of geometric confinement on some mechanical properties have been discussed in numerous earlier studies. For example, in a previous study focused on crystalline silicon, [22] we found that by creating an ordered nanoporous silicon structure, the material properties were significantly altered compared to the bulk silicon; specifically, a greater deformability was observed. We found that by varying the widths of the silicon structure, a broad range of toughness could be achieved, with a size-dependent peak in performance.…”

Section: Introductionmentioning

confidence: 99%

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Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength

Garcia

Sen

Buehler

2011

Metall Mater Trans A

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A universal design paradigm in biology is the use of hierarchies, which is evident in the structure of proteins, cells, tissues, and organisms, as well as outside the material realm in the design of signaling networks in complex organs such as the brain. A fascinating example of a biological structure is that of diatoms, a microscopic mineralized algae that is mainly composed of amorphous silica, which features a hierarchical structure that ranges from the nano-to the macroscale. Here, we use the porous structure found at submicron length scales in diatom algae as a basis to study a bioinspired nanoporous material implemented in crystalline silica. We consider the mechanical performance of two nanoscale levels of hierarchy, studying an array of thin-walled foil silica structures and a hierarchical arrangement of foil elements into a porous silica mesh structure. By comparing their elastic, plastic, and failure mechanisms under tensile deformation, we elucidate the impact of hierarchies and the wall width of constituting silica foils on the mechanical properties, by carrying out a series of large-scale molecular dynamics (MD) simulations with the first principles based reactive force field ReaxFF. We find that by controlling the wall width and by increasing the level of hierarchy of the nanostructure from a foil to a mesh, it is possible to significantly enhance the mechanical response of the material, creating a highly deformable, strong, and extremely tough material that can be stretched in excess of 100 pct strain, in stark contrast to the characteristic brittle performance of bulk silica. We find that concurrent mechanisms of shearing and crack arrest lead to an enhanced toughness and are enabled through the hierarchical assembly of foil elements into a mesh structure, which could not be achieved in foil structures alone. Our results demonstrate that including higher levels of hierarchy are beneficial in improving the mechanical properties and deformability of intrinsically brittle materials. The findings reported here provide insight into general material design approaches that may enable us to transform a brittle material such as silicon or silica into a ductile, yet strong and tough material, solely through alterations of its structural arrangement at the nanoscale.

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Section: Discussionsupporting

confidence: 48%

Section: Discussionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

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Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength

Garcia

Sen

Buehler

2011

Metall Mater Trans A

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“…A timestep of 0.05 f s was used together with a constant strain rate of 10 −6 / f s. The increased stretching is maintained until complete rupture of the membranes, which means tipical simulation times of the order of 10 6 f s. The methodology used in this work has been succeffully applied in the study of the mechanical properties of many other structures. [40][41][42][43][44][45] From the simulated stretching processes we can obtain the stress-strain curves. In the linear region of the stress-strain curve we have calculated the Young's modulus, which can be defined as…”

Section: Methodsmentioning

confidence: 99%

Mechanical and structural properties of graphene-like carbon nitride sheets

et al. 2016

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Carbon nitride-based nanostructures have attracted special attention (from theory and experiments) due to their remarkable electromechanical properties. In this work we have investigated the mechanical properties of some graphene-like carbon nitride membranes through fully atomistic reactive molecular dynamics simulations. We have analyzed three different structures of these CN families, the so-called graphene-based g-CN, triazine-based g-C 3 N 4 and * To whom correspondence should be addressed †1 1 heptazine-based g-C 3 N 4 . The stretching dynamics of these membranes was studied for deformations along their two main axes and at three different temperatures: 10K, 300K and 600K.We show that g − CN membranes have the lowest ultimate fracture strain value, followed by heptazine-based and triazine-based ones, respectively. This behavior can be explained in terms of their differences in terms of density values, topologies and types of chemical bonds. The dependency of the fracture patterns on the stretching directions is also discussed.

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“…The field of biomimetics has already led to brighter LCD screens, more efficient solar panels, more protective body armour, and more agile robots [1][2][3]. By studying structural designs found in Nature, it may be possible to develop novel materials and devices that would otherwise have gone undiscovered [4,5]. A field that has shown extensive promise is that of nanomaterials.…”

Section: Introductionmentioning

confidence: 99%

Nanomechanics of biologically inspired helical silica nanostructures

Mohedas

Garcia²,

Buehler³

2010

Proceedings of the Institution of Mechanical Engineers, Part N:

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Diatoms are unicellular algae that exhibit highly intricate, silicified cell walls called frustules. Frustules consist of hierarchical nanostructures composed of amorphous silica and organic protein. Earlier work has suggested diatoms as inspiration for novel molecular sieves, resins, and optical coatings because of their unique mechanical, structural, and optical properties. Here the present authors report studies of the mechanics of helical silica structures inspired by the geometry found in diatom frustules consisting of both crystalline and amorphous silica. Molecular dynamics simulations are reported with the reactive force field ReaxFF, which is a powerful model to describe interatomic interactions derived directly from first principles quantum mechanics. It is found that introducing a helical nanostructural geometry gives the typically brittle silica a highly ductile, yet softer, mechanical behaviour: extensions of 100 per cent to roughly 300 per cent are observed for varying helical geometries. The present authors show that hydroxide termination markedly affects the mechanical properties of the silica, lowering both the Young's modulus and the ultimate strength of the structures.The results reported here demonstrate the potential to drastically alter, and possibly improve, the properties of an inherently brittle material by confining structural features to the nanoscale and by altering its hierarchical geometry without introducing any additional material components, solely relying on geometrical changes.

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Bioinspired nanoporous silicon provides great toughness at great deformability

Cited by 56 publications

References 29 publications

Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength

Hierarchical Silica Nanostructures Inspired by Diatom Algae Yield Superior Deformability, Toughness, and Strength

Mechanical and structural properties of graphene-like carbon nitride sheets

Nanomechanics of biologically inspired helical silica nanostructures

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