Evidence for Active Atomic Defects in Monolayer Hexagonal Boron Nitride: A New Mechanism of Plasticity in Two-Dimensional Materials

We report the formation and motion Of 4 vertical bar 8 (square-octagon) defects in monolayer hexagonal boron nitride (h-BN). The 418 defects, involving less-favorable B-B and N-N bonds, are mobile within the monolayer at high sample temperature (similar to 1000 K) under electron beam irradiation. Gliding of one or two atomic rows along the armchair direction is suggested to be the origin of the defect motion. This represents a completely new mechanism of plasticity in two-dimensional materials.