Taha Doaa, Mkhonta S K, Elder K R, Huang Zhi-Feng
Department of Physics and Astronomy, Wayne State University, Detroit, Michigan 48201, USA.
Department of Physics, University of Swaziland, Private Bag 4, Kwaluseni M201, Swaziland.
Phys Rev Lett. 2017 Jun 23;118(25):255501. doi: 10.1103/PhysRevLett.118.255501. Epub 2017 Jun 20.
Understanding and controlling the properties and dynamics of topological defects is a lasting challenge in the study of two-dimensional materials, and is crucial to achieve high-quality films required for technological applications. Here grain boundary structures, energies, and dynamics of binary two-dimensional materials are investigated through the development of a phase field crystal model that is parametrized to match the ordering, symmetry, energy, and length scales of hexagonal boron nitride. Our studies reveal some new dislocation core structures for various symmetrically and asymmetrically tilted grain boundaries, in addition to those obtained in previous experiments and first-principles calculations. We also identify a defect-mediated growth dynamics for inversion domains governed by the collective atomic migration and defect core transformation at grain boundaries and junctions, a process that is related to inversion symmetry breaking in binary lattice.
理解和控制拓扑缺陷的性质与动力学是二维材料研究中一项长期的挑战，对于实现技术应用所需的高质量薄膜至关重要。在此，通过开发一种相场晶体模型来研究二元二维材料的晶界结构、能量和动力学，该模型经过参数化以匹配六方氮化硼的有序性、对称性、能量和长度尺度。我们的研究揭示了各种对称和非对称倾斜晶界的一些新的位错核心结构，这是此前实验和第一性原理计算中未获得的。我们还确定了由晶界和结处的集体原子迁移和缺陷核心转变所控制的反演畴的缺陷介导生长动力学，这一过程与二元晶格中的反演对称性破缺有关。
