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Issue 30, 2019
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Designing active particles for colloidal microstructure manipulation via strain field alchemy

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Abstract

Defects in a crystal can exert forces on each other via strain field interactions. Here we explore the strain-field-mediated interaction between an anisotropic interstitial probe particle and dislocation microstructures in a colloidal crystal composed of particles interacting via steep repulsive isotropic potentials. We optimize the interaction between probe particle and dislocation with the anisotropic shape of the probe as a free parameter. Such alchemical optimization is typically carried out upon the explicitly defined interaction potential parameters; instead, we optimize the strain field of the probe and then map back to particle shape. We distinguish this tactic from other alchemical methods as ‘strain alchemy’. We report several findings: (1) a robust mapping exists between strain field calculation methods (the method of eigenstrains) and strains produced by an anisotropic interstitial, (2) optimization of strain field interactions in the strain domain permits rapid evaluation of candidate shapes for interstitials, (3) interstitial mobility barriers can be estimated from the strain field, and (4) strongly interacting and highly mobile interstitial particles can be found that are capable of driving dislocation glide with applied force. Active particle-induced dislocation glide is examined for the cases of edge dislocation arrays and extrinsic dislocation loops. For edge dislocations, particle geometries of alternating large and small diameter segments were found to interact most strongly. For dislocation loops, interstitials with a single small radius segment surrounded by large radius segments are best.

Graphical abstract: Designing active particles for colloidal microstructure manipulation via strain field alchemy

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Publication details

The article was received on 02 May 2019, accepted on 27 Jun 2019 and first published on 18 Jul 2019


Article type: Paper
DOI: 10.1039/C9SM00896A
Soft Matter, 2019,15, 6086-6096

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    Designing active particles for colloidal microstructure manipulation via strain field alchemy

    B. VanSaders and S. C. Glotzer, Soft Matter, 2019, 15, 6086
    DOI: 10.1039/C9SM00896A

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