Diffraction from twisted nanowires: helicity revealed by anisotropy

Gailhanou, M.; Roussel, Jean-Marc

doi:10.1107/s1600576718013493

Cited by 4 publications

(6 citation statements)

References 24 publications

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“…where α denotes the twist per unit undeformed length, R 0 is the radius of the wire, u 0 and w 0 set the relaxed state before torsion, and u w Z = αR 0 g(R, ) is the warp displacement field to be determined. Its form proportional to α is similar to the one generally encountered if the wire direction is anisotropic (e.g., [011] for Cu) or if the cross section is noncircular [15]. We will show in this work that our model in Eq.…”

Section: A Torsion Of a Circular Cylinder Of Cusupporting

confidence: 58%

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Warping caused by surface elasticity in a nanowire under torsion

Roussel

Gailhanou

2023

Phys. Rev. B

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By combining molecular statics simulations and continuum mechanics-based modeling, we show in this paper that the torsion of a 001 single-crystal copper nanowire with a circular cross section gives rise to a warp, i.e., to a displacement field along the wire axis that renders the cross section nonplanar. This behavior, which is in apparent contradiction with what is predicted by continuum mechanics for an isotropic cylinder, can be well explained if we take into account the elastic response of the wire lateral surface. The latter is characterized by the anisotropy of the surface elastic constants and, more specifically in the case of torsion, by the surface shear constant C S 44 whose strength as a function of the local orientation of the lateral surface is estimated independently from atomistic calculations on slabs presenting different vicinal surfaces. The solution of the torsion problem is then obtained by adopting a semi-inverse method in the framework of the finite strain theory in linear elasticity with Gurtin-Murdoch boundary conditions linking surface stress and bulk stress. It is shown that such an approach is well suited to explain quantitatively the warp obtained in our atomistic simulations and to prove the preponderant role played by the surface elastic constant C S 44 .

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Section: A Torsion Of a Circular Cylinder Of Cusupporting

confidence: 58%

“…We will show, however, that it has interesting implications since it is responsible of a warp in the bulk of the wire via the Gurtin-Murdoch condition of Eq. (15). For this purpose, we also need to write the first Piola-Kirchhoff surface stress P S = F S S S .…”

Section: A Torsion Of a Circular Cylinder Of Cumentioning

confidence: 99%

Warping caused by surface elasticity in a nanowire under torsion

Roussel

Gailhanou

2023

Phys. Rev. B

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“…Upon heating to 100 °C, this particular chain appears disordered (located between parallel green lines in Figure B) and may be in a transitional state from twisted to untwisted. Furthermore, FFT analysis shows a well-defined NbS 3 pattern (straight chain) versus a smeared pattern (twisted chain) at RT, as well as a well-defined NbS 3 pattern at 100 °C that corresponds to the now untwisted straight chain (Supporting Information Figure S6) . This observation suggests that annealing, even at such a low temperature, can allow twisted chains to relax into a more stable, straight alignment.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, FFT analysis shows a well-defined NbS 3 pattern (straight chain) versus a smeared pattern (twisted chain) at RT, as well as a well-defined NbS 3 pattern at 100 °C that corresponds to the now untwisted straight chain (Supporting Information Figure S6). 32 This observation suggests that annealing, even at such a low temperature, can allow twisted chains to relax into a more stable, straight alignment. Further investigations are needed to identify the prevalence of chain twisting in NbS 3 samples and the impact of this novel defect on electronic properties, including charge density wave behavior.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Thermal Stability of Quasi-1D NbS₃ Nanoribbons and Their Transformation to 2D NbS₂: Insights from in Situ Electron Microscopy and Spectroscopy

et al. 2021

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In situ electron microscopy imaging and spectroscopy enabled us to study the evolution of quasi-1D NbS3-IV nanoribbons with respect to morphology and chemical structure at temperatures between room temperature and 1000 °C. Scanning transmission electron microscopy (STEM) experiments included imaging in the secondary electron, (transmitted) bright field, and high-angle annular dark-field modes while operating in the low kV regime. The results showed that NbS3-IV samples transform dramatically from smooth nanoribbons into highly textured configurations featuring polyhedral divots and steps. Similar in situ heating experiments conducted with aberration-corrected STEM revealed that bilayers of NbS3-IV chains convert topotactically into aligned 2H-NbS2 sheets upon loss of sulfur. Atomic resolution imaging, fast Fourier transform analysis, and electron energy loss spectroscopy confirmed these chemical changes, from which we propose an atomistic mechanism for the NbS3-IV → 2H-NbS2 conversion.

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“…It is well-known that diffraction of ideal helical structures results in X-shaped patterns (36,37). Therefore, we applied fast Fourier transformations (FFT) to our 3D reconstructions.…”

Section: Introductionmentioning

confidence: 99%

Micelle-directed chiral seeded growth on anisotropic gold nanocrystals

González‐Rubio

Mosquera

Kumar

et al. 2020

Science

232

305

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Surfactant-assisted seeded growth of metal nanoparticles (NPs) can be engineered to produce anisotropic gold nanocrystals with high chiroptical activity through the templating effect of chiral micelles formed in the presence of dissymmetric cosurfactants. Mixed micelles adsorb on gold nanorods, forming quasihelical patterns that direct seeded growth into NPs with pronounced morphological and optical handedness. Sharp chiral wrinkles lead to chiral plasmon modes with high dissymmetry factors (~0.20). Through variation of the dimensions of chiral wrinkles, the chiroptical properties can be tuned within the visible and near-infrared electromagnetic spectrum. The micelle-directed mechanism allows extension to other systems, such as the seeded growth of chiral platinum shells on gold nanorods. This approach provides a reproducible, simple, and scalable method toward the fabrication of NPs with high chiral optical activity.

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Diffraction from twisted nanowires: helicity revealed by anisotropy

Cited by 4 publications

References 24 publications

Warping caused by surface elasticity in a nanowire under torsion

Warping caused by surface elasticity in a nanowire under torsion

Thermal Stability of Quasi-1D NbS₃ Nanoribbons and Their Transformation to 2D NbS₂: Insights from in Situ Electron Microscopy and Spectroscopy

Micelle-directed chiral seeded growth on anisotropic gold nanocrystals

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Diffraction from twisted nanowires: helicity revealed by anisotropy

Cited by 4 publications

References 24 publications

Warping caused by surface elasticity in a nanowire under torsion

Warping caused by surface elasticity in a nanowire under torsion

Thermal Stability of Quasi-1D NbS3 Nanoribbons and Their Transformation to 2D NbS2: Insights from in Situ Electron Microscopy and Spectroscopy

Micelle-directed chiral seeded growth on anisotropic gold nanocrystals

Contact Info

Product

Resources

About

Thermal Stability of Quasi-1D NbS₃ Nanoribbons and Their Transformation to 2D NbS₂: Insights from in Situ Electron Microscopy and Spectroscopy