Quantifying the defect-dominated size effect of fracture strain in single crystalline ZnO nanowires

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The diameter (D) dependence of fracture strains in [0001]-oriented single crystalline ZnO nanowires (NWs) with D ranging from 18 to 114 nm is experimentally revealed viain situuniaxial tension and is well understood based on an analytical model developed by combining molecular dynamics simulations with fracture mechanics theories. We show that the scattered fracture strains are dominated by the effective quantities of atomic vacancies, and their lower bound follows a power-form scaling law, resembling the Griffith-type behavior of single critical defects with diameter-dependent sizes, when D is larger than a critical DC. In addition, theoretical strength is expected in NWs with D<DC. Our studies provide a simple, but basic, understanding for the size effect of strengths in single crystalline NWs.

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Theoretical or Mathematical, Experimental/ fracture mechanics fracture toughness II-VI semiconductors molecular dynamics method semiconductor quantum wires vacancies (crystal) wide band gap semiconductors zinc compounds/ fracture strength molecular dynamics simulations in situ uniaxial tension atomic vacancies power-form scaling law single critical defects Griffith-type behavior defect-dominated size effect fracture mechanics [0001]-oriented single crystalline nanowires fracture strains size 18 nm to 114 nm ZnO/ A8140N Fatigue, embrittlement, and fracture A6170B Interstitials and vacancies A6865 Low-dimensional structures: growth, structure and nonelectronic properties A6220M Fatigue, brittleness, fracture, and cracks A6185 Modelling and computer simulation of solid structure A6146 Structure of solid clusters, nanoparticles, nanotubes and nanostructured materials/ size 1.8E-08 to 1.14E-07 m/ ZnO/int Zn/int O/int ZnO/bin Zn/bin O/bin