LAUSR

Abstract The fracture of nanoscale notched brittle materials is investigated using the multi-scale analysis of cohesive zone modeling and first-principles calculations based on the notched nano-cantilever bending experiment. The fracture of nanoscale single-crystal silicon is achieved at the nano-notch tip, and the load-deflection curve is obtained during in situ TEM experiment. On the other hand, a bilinear CZM is adopted to simulate the observed fracture from the notch tip due to the stress concentration of less than 1 nm. The CZM parameters determined from one specimen, ϕn=9.78 J/m2, σmax = 13.04 GPa, and Δ n c =1.5 nm, accurately predict the fracture behaviors of all other specimens regardless of specimen sizes, indicating the robust applicability of CZM for describing the fracture of nanoscale brittle materials. In addition, first-principles calculations are performed to investigate the inherent fracture properties of single-crystal silicon from atomic and electronic viewpoints. The fracture surface energy and critical bond length for the break of atomic bonds during the fracture are compared with the cohesive energy and failure length parameter, respectively, which provides the atomistic interpretation of CZM validity for the fracture of brittle materials by the extremely small stress concentration. Finally, the comparison of cohesive energy with the fracture energy obtained by fracture mechanics of nanoscale and bulk single-crystal silicon indicates that the consumed energy is an effective linkage to quantify the fracture of brittle materials at different scales.