Defect-dominated diameter dependence of fracture strength in single-crystalline ZnO nanowires:In situexperiments

Diameter (D) dependence of fracture strength in [0001]-oriented single-crystalline ZnO nanowires (NWs) with D ranging from 18 to 114 nm is experimentally revealed via in situ uniaxial tension. The lower bound of the scattered strengths increases with decreasing D, following a modified power law, and critical defects that effectively dominate the strengths are attributed to the diameter-dependent quantities of discrete point defects in NWs, based on in situ cathodoluminescence spectra. As a result, the size-effect mechanism of fracture strength is well understood, accounting for a simple and basic case of single-crystalline NWs.