Strain-Induced asymmetry and on-site dynamics of silicon defects in graphene
Ondrej Dyck,
Feng Bao,
Maxim Ziatdinov,
Ali Yousefzadi Nobakht,
Kody Law,
Artem Maksov,
Bobby G. Sumpter,
Richard Archibald,
Stephen Jesse,
Sergei V. Kalinin,
David B. Lingerfelt
Affiliations
Ondrej Dyck
Corresponding authors.; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Feng Bao
Department of Mathematics, Florida State University, Tallahassee, FL 32304, USA
Maxim Ziatdinov
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Ali Yousefzadi Nobakht
Department of Mechanical, Aerospace, and Biomedical Engineering, The University of Tennessee, Knoxville, TN 37996, USA
Kody Law
School of Mathematics, University of Manchester, Manchester, M13 9PL, UK
Artem Maksov
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA; Bredesen Center for Interdisciplinary Research and Education, The University of Tennessee, Knoxville, TN 37996, USA
Bobby G. Sumpter
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Richard Archibald
Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Stephen Jesse
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
Sergei V. Kalinin
Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, USA
David B. Lingerfelt
Corresponding authors.; Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
In the last decade, the atomically-focused electron beams utilized in scanning transmission electron microscopes (STEMs) have been shown to induce a broad set of local structural transformations in materials, opening pathways for directing material synthesis and modification atom-by-atom. The mechanisms underlying these transformations remain largely unknown, due to the intractability of modeling the myriad of reaction pathways that can be accessed through high-energy electron scattering. The information on materials’ structure and dynamics that can be extracted from STEM images is similarly left underexplored. Here, we report the observation of anomalous on-site dynamics of individual silicon impurity atoms in graphene during STEM imaging. Density functional theory-based structural optimizations of anisotropically-strained molecular nanographenes reveal two distinct (but nearly degenerate) stable structures for four-fold coordinated silicon impurities, where interconversion between the two structures manifests slight changes of the silicon position within the lattice site. Implications for defect-based strain engineering in graphene are discussed.
