Nature Materials 2015-02-01

Heterogeneous nucleation and shape transformation of multicomponent metallic nanostructures.

Soon Gu Kwon, Galyna Krylova, Patrick J Phillips, Robert F Klie, Soma Chattopadhyay, Tomohiro Shibata, Emilio E Bunel, Yuzi Liu, Vitali B Prakapenka, Byeongdu Lee, Elena V Shevchenko

Index: Nat. Mater. 14(2) , 215-23, (2015)

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Abstract

To be able to control the functions of engineered multicomponent nanomaterials, a detailed understanding of heterogeneous nucleation at the nanoscale is essential. Here, by using in situ synchrotron X-ray scattering, we show that in the heterogeneous nucleation and growth of Au on Pt or Pt-alloy seeds the heteroepitaxial growth of the Au shell exerts high stress (∼2 GPa) on the seed by forming a core/shell structure in the early stage of the reaction. The development of lattice strain and subsequent strain relaxation, which we show using atomic-resolution transmission electron microscopy to occur through the slip of {111} layers, induces morphological changes from a core/shell to a dumbbell structure, and governs the nucleation and growth kinetics. We also propose a thermodynamic model for the nucleation and growth of dumbbell metallic heteronanostructures.