Incommensurate grain-boundary atomic structure.

Seki, Takehito; Futazuka, Toshihiro; Morishige, Nobusato; Matsubara, Ryo; Ikuhara, Yuichi; Shibata, Naoya · Nat Commun · 2023

basic_science · Level V

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Abstract

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 Σ9 grain-boundary atomic structure of a bcc crystal (Fe-3%Si). It is found that the Σ9 grain-boundary structure is largely reconstructed and forms a dense packing of icosahedral clusters in its core. Combining with the detailed theoretical calculations, the Σ9 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.