The Ultimate Strength of Glass Silica Nanowires

Brambilla, Gilberto; Payne, D.N.

doi:10.1021/nl803581r

Cited by 165 publications

(140 citation statements)

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“…In our previous investigations, silica NWs were found to exhibit a super plasticity as high as approximately 200% [33], and an elasticity of approximately 10% [25]. A strong size effect on the ultimate strength of silica NWs was also reported [20]. Our systematic experiments in which the elastic strain limit of silica glass NWs was approached confirmed an approximately 13% elastic strain limit for silica NWs with diameters around 50 nm (see Fig.…”

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confidence: 76%

“…The ultimate strength of silica NWs is higher than 10 GPa and increases with decreasing NW diameter. The reduced possibility of having large cracks in small samples is the main reason for their high strength [20]. Molecular dynamic simulations also indicate such a size-dependent elasticity for amorphous silica NWs originating from coupling between core softening and surface stiffening of each NW the structure of which is different from its bulk counterpart [21].…”

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Origin of high elastic strain in amorphous silica nanowires

et al. 2015

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An understanding of the origin of elastic strain is extremely important for both crystalline materials and amorphous materials. Owing to the lack of a long range order in their structure, it is arduous to dynamically study the elastic mechanism of amorphous materials experimentally at atomic scale compared with their crystalline counterparts. Here, the elastic deformation mechanism of amorphous silica nanowires (NWs) has been studied for the first time via in situ elastic tensile tests in a transmission electron microscope. Radial distribution functions (RDFs) calculated from the corresponding selected area electron diffraction patterns (SAEDPs) at different strains were used to reconstruct a structural model based on the reverse Monte-Carlo (RMC) method. The result interestingly indicates that the elastic strain of silica glass NWs can be mainly attributed to the elastic elongation of the bond length accompanied by a change in the bond angle distribution. This work is useful for understanding the high strength of amorphous materials.The two most crucial properties of a structural material are its elastic strain limit and plasticity. Plasticity is the property indicating the flexibility of a material, while the elastic strain limit represents the maximum stress that the material can withstand before yielding. The development of materials with high elastic strain limit and excellent plasticity is an urgent target for researchers [1−4]. Amorphous materials such as oxide glasses and metallic glasses are widely used in military applications. Unlike for their crystalline counterparts, there is still inadequate comprehension of the extraordinary behaviors of such glasses [5−10]. In nano-sized objects, smaller is stronger, owing to the combination of their decreased defect density and increased strength and elastic strain. Experimental elastic strain limits of more than 7.8% for ZnO nanowires (NWs) [11,12] the size of such glasses minimizes flaw size and maximizes their strength (i.e., elastic strain). Elimination of extrinsic flaws and decreased internal structural defects can lead to an outstanding large elastic strain limit of more than 3-6% for submicro-sized glasses [16−19], in which shear bands are suppressed owing to the reduction in size [16]. The ultimate strength of silica NWs is higher than 10 GPa and increases with decreasing NW diameter. The reduced possibility of having large cracks in small samples is the main reason for their high strength [20]. Molecular dynamic simulations also indicate such a size-dependent elasticity for amorphous silica NWs originating from coupling between core softening and surface stiffening of each NW the structure of which is different from its bulk counterpart [21]. In our systematic studies, an approximately 13% elastic strain limit for silica NWs with diameters around 50 nm was confirmed. The uniaxial tensile stress corresponding to such an elastic strain limit would be 9.5 GPa (assuming a Young's modulus of 73 GPa for silica NWs [22]). Recent results have revealed that the...

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confidence: 99%

Origin of high elastic strain in amorphous silica nanowires

et al. 2015

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“…This strength is still well below theoretical, in contrast to the strengths of synthesized high-purity silica nanowires that attain near-theoretical tensile strengths between [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. This is likely because the frustule is a silica composite rather than pure silica.…”

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confidence: 89%

Microstructure provides insights into evolutionary design and resilience of Coscinodiscus sp. frustule

Aitken

Luo

Reynolds

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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We conducted in situ three-point bending experiments on beams with roughly square cross-sections, which we fabricated from the frustule of Coscinodiscus sp. We observe failure by brittle fracture at an average stress of 1.1 GPa. Analysis of crack propagation and shell morphology reveals a differentiation in the function of the frustule layers with the basal layer pores, which deflect crack propagation. We calculated the relative density of the frustule to be ∼30% and show that at this density the frustule has the highest strength-to-density ratio of 1,702 kN·m/kg, a significant departure from all reported biologic materials. We also performed nanoindentation on both the single basal layer of the frustule as well as the girdle band and show that these components display similar mechanical properties that also agree well with bending tests. Transmission electron microscopy analysis reveals that the frustule is made almost entirely of amorphous silica with a nanocrystalline proximal layer. No flaws are observed within the frustule material down to 2 nm. Finite element simulations of the threepoint bending experiments show that the basal layer carries most of the applied load whereas stresses within the cribrum and areolae layer are an order of magnitude lower. These results demonstrate the natural development of architecture in live organisms to simultaneously achieve light weight, strength, and exceptional structural integrity and may provide insight into evolutionary design.iatoms are single-cell algae that form a hard cell wall made of a silica/organic composite. The ability to produce a functional biosilica shell presents several natural precedents that fascinate and inspire scientists and engineers. One fascinating aspect of such silica glass shells is their intricate, varied, and detailed architecture. Diatoms are generally classified based on the symmetry of their shells: Centric diatoms display radial symmetry whereas pennate diatoms have bilateral symmetry. Fig. 1A shows a schematic of a typical centric diatom and reveals that the shells are composed of two halves, called frustules, that fit together in a Petri-dish configuration. The frustules are attached to each other around the perimeter of the shell by one or several girdle bands. The frustules are usually porous with pore size and density varying between species. The frustule shell can also be composed of multiple layers with a cellular structure within the shell.The proposed evolutionary functions for these intricate shell designs include nutrient acquisition, control of diatom sinking rate, control of turbulent flow around the cell, and protection from grazing and viral attack (1). Evidence in favor of a protective function is that the degree of shell silification depends on the environment, with greater amounts of silica found in shells grown in a predatory environment (2). As a deterrent to predation, the frustule makes use of an inherently brittle glass as a structurally protective material while balancing other evolutionary pressures. A denser ...

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“…[1][2][3][4] Of these forms, silica nanowires have a unique one-dimensional structure and properties with potential applications in nano-electromechanical systems, such as sensors and optical devices. [5][6][7] To facilitate the use of silica NWs in these devices, the mechanical properties and the associated phenomena which govern such nanostructures need to be well understood.…”

Section: Introductionmentioning

confidence: 99%

Size dependence of elastic mechanical properties of nanocrystalline aluminum

Dávila

2017

Materials Science and Engineering: A

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Shape memory effects and pseudoelasticity in bcc metallic nanowires J. Appl. Phys. 108, 113531 (2010) This study investigates the structural transformations and properties of silica glass nanowires under tensile loading via molecular dynamics simulations using the BKS (Beest-Kramer-Santen) interatomic potential. Surface states of the elongated nanowires were quantified using radial density distributions, while structural transformations were evaluated via ring size distribution analysis. The radial density distributions indicate that the surface states of these silica nanowires are significantly different than those of their interior. Ring size analysis shows that the ring size distributions remain mainly unchanged within the elastic region during tensile deformation, however they vary drastically beyond the onset of plastic behavior and reach plateaus when the nanowires break. The silica nanowires undergo structural changes which correlate with strain energy and ring size distribution variations. It is also found that the ring size distribution (and strain energy) variations are dependent on the diameter of the silica nanowires. Interestingly, for ultrathin nanowires (diameters < 5 .0 nm), the variation of ring size distributions shows a distinct trend with respect to tensile strain, indicating that the surface states play a key role in both modifying the mechanical properties and structural characteristics. These results for ultrathin nanowires are consistent with prior theoretical and simulation predictions. The overall findings in this study provide key insights into the novel properties of nano-sized amorphous materials, and are aimed to inspire further experiments. V C 2015 AIP Publishing LLC.

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The Ultimate Strength of Glass Silica Nanowires

Cited by 165 publications

References 24 publications

Origin of high elastic strain in amorphous silica nanowires

Origin of high elastic strain in amorphous silica nanowires

Microstructure provides insights into evolutionary design and resilience of Coscinodiscus sp. frustule

Size dependence of elastic mechanical properties of nanocrystalline aluminum

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