Research Article

Oriented attachment induces fivefold twins by forming and decomposing high-energy grain boundaries

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Science  28 Nov 2019:
eaax6511
DOI: 10.1126/science.aax6511

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Abstract

Natural and synthetic nanoparticles composed of five-fold twinned crystals domains have unique properties. The formation mechanism of these five-fold twinned nanoparticles is poorly understood. We used in situ high-resolution transmission electron microscopy combined with molecular dynamics simulations to demonstrate that five-fold twinning occurs via repeated oriented attachment of ~3 nm gold, platinum, and palladium nanoparticles. We discovered two different mechanisms for forming five-fold twinned nanoparticles that are driving by the accumulation and elimination of strain. This was accompanied by decomposition of grain boundaries and the formation of a special class of twins with a net strain of zero. These observations allowed us to develop a quantitative picture of the twinning process. The mechanisms provide guidance for controlling twin structures and morphologies across a wide range of materials.

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