Fracture strength and Young's modulus of ZnO nanowires

TL;DR

This study measures the fracture strength and Young's modulus of ZnO nanowires, revealing their mechanical properties are comparable to bulk ZnO and providing insights into their fracture behavior at nanoscale.

Contribution

It provides new experimental data on the fracture strength and Young's modulus of ZnO nanowires, using in-situ manipulation inside SEM, and compares these properties to bulk material.

Findings

Fracture strain close to 10%, indicating near-theoretical strength.

Young's modulus within 30% of bulk ZnO, higher than previous reports.

Fracture strength approximately twice as high in bending as in tension.

Abstract

The fracture strength of ZnO nanowires vertically grown on sapphire substrates was measured in tensile and bending experiments. Nanowires with diameters between 60 and 310 nm and a typical length of 2 um were manipulated with an atomic force microscopy tip mounted on a nanomanipulator inside a scanning electron microscope. The fracture strain of (7.7 +- 0.8)% measured in the bending test was found close to the theoretical limit of 10% and revealed a strength about twice as high as in the tensile test. From the tensile experiments the Young's modulus could be measured to be within 30% of that of bulk ZnO, contrary to the lower values found in literature.