Nanoindentation study of deformation-resistant Al/a-Si core–shell nanostructures

Tidwell, Whitney; Scott, David W.; Wang, Hengyu; Fleming, Robert A.; Zou, Min

doi:10.1016/j.actamat.2011.06.023

Cited by 15 publications

(9 citation statements)

References 24 publications

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“…As can be seen, the indenter displacement returns to zero (or nearly to zero) regardless of the applied maximum indenter displacement, which indicates that very little residual deformation remains after indentation. In light of the fact that for the 80 nm indents, the maximum indentation depth is 20% of the total structure height of 400 nm, this deformation resistance is especially notable and is consistent with previously reported measurements on Al/a-Si nanostructures fabricated from a nanotextured Al thin film [15,16].…”

Section: Deformation Resistant Csnssupporting

confidence: 91%

“…An electron beam writer (JBX-9300FS, JEOL Ltd.) was used to selectively expose the electron resist using 1 nA of current, a 50 kV accelerating voltage, and a beam dose of 1000 μC/cm 2 . After exposure, the sample was developed in a 1:3 mixture of methyl isobutyl ketone (MIBK) and isopropyl alcohol (IPA) for 45 s, and then rinsed in pure IPA for 15 Fig. 1; note that the specified rod length excludes the hemispherical end-caps of each rod.…”

Section: Nanostructure Fabricationmentioning

confidence: 99%

“…Al/a-Si core-shell nanostructures (CSNs), composed of a nanotextured Al thin film coated with a conformal shell of a-Si, have also been shown to have deformation resistant properties [15].…”

Section: Introductionmentioning

confidence: 99%

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Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

Fleming

Goss

Zou

2017

Applied Surface Science

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The nanoindentation behavior of hemispherical Al/a-Si core-shell nanostructures (CSNs), horizontally-aligned Al/a-Si core-shell nanorods (CSRs) with various lengths, and an Al/a-Si layered thin film has been studied to understand the effects of geometrical confinement of the Al core on the CSN deformation behavior. When loaded beyond the elastic limit, the CSNs have an unconventional load-displacement behavior with no residual displacement after unloading, resulting in no net shape change after indentation. This behavior is enabled by dislocation activities within the confined Al core, as indicated by discontinuous indentation signatures (loaddrops and load-jumps) observed in the load-displacement data. When the geometrical confinement of the core is slightly reduced, as in the case of CSRs with the shortest rod length, the discontinuous indentation signatures and deformation resistance are heavily reduced. Further decreases in core confinement result in conventional nanoindentation behavior, regardless of geometry. Supporting molecular dynamics simulations show that dislocations nucleated in the core of a CSN are more effectively removed during unloading compared to CSRs, which supports the hypothesis that the unique deformation resistance of Al/a-Si CSNs are enabled by 3dimensional confinement of the Al core.

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Section: Deformation Resistant Csnssupporting

confidence: 91%

Section: Nanostructure Fabricationmentioning

confidence: 99%

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Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

Fleming

Goss

Zou

2017

Applied Surface Science

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“…Young's modulus (a), hardness (b), and yield strength (c) of the 0.5 µm SiLi x thin films as a function of Li content in comparison to literature values of a‐S , c‐Si , Li , compacted c‐SiLi x powder , tension simulations by Zhao et al and MD simulations by Fan et al , respectively. Dotted lines were added as a guide for the eye.…”

Section: Resultsmentioning

confidence: 98%

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

Zinn

Borhani-Haghighi

Ventosa

et al. 2014

Phys. Status Solidi A

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The mechanical properties of amorphous Si thin films, lithiated electrochemically to different Si-Li compositions are studied by ex situ nanoindentation. The compositions of the films are adjusted using an electrochemical routine that corrects for the Li consumed by SEI layer growth during initial lithiation. The mechanical properties such as Young's modulus and hardness are derived from nanoindentation. For compositions between Si and SiLi 2.5 the Young's modulus decreases with increasing Li content from $160 GPa to $8 GPa and the hardness decreases from $14 GPa to $0.1 GPa. The yield strength values, as deduced from hardness measurements, decrease from $5 GPa to 0.05 GPa. AFM imaging is used on the electrochemically cycled films to assess the SEIs impact on the nanomechanical measurements. XPS depth-profiling of the electrochemically cycled sample indicated a Li concentration gradient across the film thickness.

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“…When subjected to nanoscratch testing, no plastic deformation of the surface was detected, even for contact loads as high as 8,000 μN, while still maintaining a low coefficient of friction. Nanoindentation experiments on the individual CSNs revealed that the structures possess higher yield strengths than either Al or a-Si, and can also sustain up to 23% engineering strain without fracture [21]. Furthermore, the CSNs display unusual loaddisplacement behavior with no residual deformation, indicating little or no permanent deformation after unloading.…”

Section: Introductionmentioning

confidence: 99%

The effects of confined core volume on the mechanical behavior of Al/a-Si core-shell nanostructures

Fleming

Zou

2017

Acta Materialia

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The mechanical behavior of novel Al/a-Si core-shell nanostructures (CSNs) is studied using instrumented nanoindentation to investigate the role that the confined core volume plays on the mechanical response of these structures. The CSNs are fabricated from truncated hemispherical Al nanodots with 100, 200, and 300 nm base diameters, which are then conformably coated with a-Si. CSNs with the smallest core diameter, and therefore the smallest confined core volume, have a unique load-displacement behavior characterized by nearly complete recovery of deformation beyond the elastic limit, which is enabled by dislocation activities within the confined Al core. In conjunction with this deformation recovery, discontinuous indentation signatures known as "load-drops" and "load-jumps" are observed during loading and unloading, respectively. As the size of the confined core volume increases, these indentation signatures are suppressed and the deformation-resistant properties are reduced. Supporting molecular dynamics simulations show that a smaller core volume results in a larger back-stress developed in the core during indentation, which further correlates with improved dislocation removal from the core after unloading. This complementary experimental and modeling investigation provides insight into the mechanisms that contribute to the unique mechanical properties of Al/a-Si CSNs.

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Nanoindentation study of deformation-resistant Al/a-Si core–shell nanostructures

Cited by 15 publications

References 24 publications

Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion

The effects of confined core volume on the mechanical behavior of Al/a-Si core-shell nanostructures

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Nanoindentation study of deformation-resistant Al/a-Si core–shell nanostructures

Cited by 15 publications

References 24 publications

Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

Material dimensionality effects on the nanoindentation behavior of Al/a-Si core-shell nanostructures

Mechanical properties of SiLixthin films at different stages of electrochemical Li insertion

The effects of confined core volume on the mechanical behavior of Al/a-Si core-shell nanostructures

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Mechanical properties of SiLi_xthin films at different stages of electrochemical Li insertion