Elastic properties of nanowires

Abstract

The elastic properties of metallic and semiconducting nanowires were analyzed by different techniques employing static and dynamic loads. The reliability of the methods is verified by analyzing well defined microstructures and a good agreement for the values of the Young's modulus determined by the different methods was achieved. For the investigated materials systems (Au, W, Si, InN), basically no differences in the Young's moduli were observed between microstructures, bulk material, and nanowires with radii of 20-300 nm. Microstructure, morphological undulation, defects, and contaminations,however, can drastically change the apparent Young's moduli of nanowires. Examples are given, where an apparent increasing or decreasing of the Young's modulus with decreasing diameter is caused by such effects. The same effects have also influence on the fracture strength in nanowires. While perfect Au nanowires exhibit fracture strengths exceeding the bulk values up to two orders of magnitude, any anomaly causes earlier failure. In addition, failure mechanisms are observed to be dependent on themicrostructure. While single crystallineAu nanowires have shown a pure elastic deformation upon load, polycrystalline nanowires show a remarkable plastic deformation before breaking

Acoustic vibrations of metal nano-objects: Time-domain investigations

“…These results contrast with the different conclusions drawn on the impact of size reduction on Young's modulus of metals or semiconductors from mechanical or electromechanical studies performed on nanowires of relatively large size (larger than 20 nm) [3,[182][183][184][185]. Depending on the experimental conditions, these nanomanipulation-based methods suggested either stiffening, or softening or no modification of the material elasticity below few tens of nanometers.…”

“…Depending on the experimental conditions, these nanomanipulation-based methods suggested either stiffening, or softening or no modification of the material elasticity below few tens of nanometers. The dispersion of the conclusions suggests a large influence of the measurement method, probably due to mechanical interaction with the nano-objects, and possible artifacts due to crystallinity defects or surface contamination or oxidation [185,186]. The former problem is avoided in non-contact optical techniques, while the latter stresses the importance of controlling the particle surface [71].…”

Electrospun metallic nanowires: Synthesis, characterization, and applications

“…In future, we can expect some non-destructive testing (NDT) techniques for mechanical testing of these nanostructures. An interested reader may go through a comprehensive review article by Rohlig et al 130 where different techniques for evaluating elastic properties of NWs have been covered.…”

Effects of oxidation on tensile deformation of iron nanowires: Insights from reactive molecular dynamics simulations

“…More recently, both experimental and theoretical investigations specifically indicated that the oxide-coated NWs exhibit different mechanical properties than their pure (unoxidized) counterparts. For example, oxide-coated tungsten NWs exhibit increased Young's modulus, 22 whereas it decreases in oxide-covered silicon 23 and copper NWs. 24 Sen et al have also studied oxide shell layer dependent deformation mechanisms of metallic aluminum NWs by using the ReaxFF model.…”

“…24 Sen et al have also studied oxide shell layer dependent deformation mechanisms of metallic aluminum NWs by using the ReaxFF model. 21,22 The authors observed that the oxide amorphous shell layer on the Al NW free surface enhances dislocation processes, as well as the Al core's dislocation nucleation stress. Most importantly, the presence of native amorphous oxide shell layers on Al NWs was shown to play a significant role in the change in the elastic mechanical response from brittle to ductile transition behavior.…”