Dislocations and grain boundaries in two-dimensional boron nitride.
A new dislocation structure-square-octagon pair (4|8) is discovered in two-dimensional boron nitride (h-BN), via first-principles calculations. It has lower energy than corresponding pentagon-heptagon pairs (5|7), which contain unfavorable homoelemental bonds. On the basis of the structures of dislocations, grain boundaries (GB) in BN are investigated. Depending on the tilt angle of grains, GB can be either polar (B-rich or N-rich), constituted by 5|7s, or unpolar, composed of 4|8s. The polar GBs carry net charges, positive at B-rich and negative at N-rich ones. In contrast to GBs in graphene which generally impede the electronic transport, polar GBs have a smaller bandgap compared to perfect BN, which may suggest interesting electronic and optical applications.
Department of Mechanical Engineering and Materials Science, and the Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas 77005, USA.
Yuanyue
Y
Liu
Xiaolong
X
Zou
Boris I
BI
Yakobson
D001896:Boron Compounds / Q000737:chemistry*; D003198:Computer Simulation; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D013499:Surface Properties
D001896:Boron Compounds; C017282:boron nitride