Incommensurate grain-boundary atomic structure

T Seki and T Futazuka and N Morishige and R Matsubara and Y Ikuhara and N Shibata, NATURE COMMUNICATIONS, 14, 7806 (2023).

DOI: 10.1038/s41467-023-43536-0

Grain-boundary atomic structures of crystalline materials have long been believed to be commensurate with the crystal periodicity of the adjacent crystals. In the present study, we experimentally observed a Sigma 9 grain-boundary atomic structure of a bcc crystal (Fe-3%Si). It is found that the Sigma 9 grain-boundary structure is largely reconstructed and forms a dense packing of icosahedral clusters in its core. Combining with the detailed theoretical calculations, the Sigma 9 grain-boundary atomic structure is discovered to be incommensurate with the adjacent crystal structures. The present findings shed new light on the study of stable grain-boundary atomic structures in crystalline materials. Grain boundary atomic structures of crystalline materials have long been believed to be commensurate with the crystal periodicity of the adjacent crystals. Here, the authors discover an incommensurate grain boundary structure based on direct observations and theoretical calculations.

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