Correlation between surface topological defects and fracture mechanism of γ-graphyne-like boron nitride nanosheets

The fracture mechanism of gamma-graphyne-like boron nitride (GYBNN) and its analogous nanosheets, sp-GYBNNS (sp-C atoms situated at acetylenic linkages) and sp(2)-GYBNNS (sp(2)-C atoms situated in hexagonal rings) was patterned as a function of temperature in both the zigzag and armchair directions via Molecular Dynamic Simulation. Next, the effect of acetylenic chain length on the Young's modulus and failure stress was studied. The applied stress was distributed on both hexagonal rings and acetylenic chains in the zigzag direction. However, in the direction of armchair the stress was mainly concentrated on the acetylenic chains. The failure stress varied less considerably by increasing the acetylenic chains' length in zigzag direction than in armchair. The sp(2)-GYBNNS and GYBNNS had the highest and lowest tensile strength in both zigzag and armchair directions, respectively. The crack length increase from L/12 (25 angstrom) to L/2 (150 angstrom) led to a significant reduction in the Young's modulus of sp(2)-GYBNNS from 270.05 to 177.25 GPa. The stress intensity factor for crack-contained sp(2)-GYBNNS (length = L/12) was declined from the value of 2.622 to 2.212 by increasing the temperature from 200 to 900 K.

Automated summary

The fracture mechanism and mechanical properties of gamma-graphyne-like boron nitride nanosheets were studied using Molecular Dynamic Simulation at different temperatures. The stress distribution varied in different directions, with crack length having a significant impact on Young's modulus.