  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 parameterized 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.
