Size and shape matters
The article “Effect of size and shape on the elastic modulus of metal nanowires” by Lilian Vogl, Peter Schweizer, Gunther Richter and Erdmann Spiecker has recently been published in MRS Advances. Congratulations, Lili and Peter! The CENEM/IMN researchers make use of the resonance vibration of metal nanowires, which were provided by Gunther Richter from Max Planck Institute for Intelligent Systems in Stuttgart, to conclude on the changing elastic behavior on small scales.
Similar to the sound generation of a stringed instrument, nanowires can also be brought into vibration. The characteristic resonance frequency of the one-dimensional nanostructure depends on the material specific properties and dimensions as well as on the elastic bending behaviour. By means of in situ electron microscopy, the dynamic oscillation can be directly observed. The defined resonance measurements give novel insights about the characteristic vibration directions, which are directly linked to the cross-sectional shape of the nanowire. In combination with correlative tensile testing, a dependency of the nanowire size and shape to the elastic modulus can be revealed: Unlike the well-known behaviour on macroscopic scales, the elastic behaviour changes with decreasing size and additionally depends on the cross-sectional shape of the nanostructure. The observed size effect refers to the relative size scale of the nanowire and results in a softening, bulk-like or stiffening regime. Moreover, the impact of the nanowire shape can not be further neglected. Taking a closer look on nanowires with rectangular cross-section, this “shape effect” constitutes itself in two different Young’s moduli extracted from measurements of nanowire resonances. In accordance with that, corresponding tensile tests on the same nanowires reveal an average “mixed” Young’s modulus.
Following their concise statement “Shape and Size matters !”, the authors want to draw the attention to their novel experimental data in the field nanomechanics and like to encourage discussion about the elastic material behavior on small scales.
Size and Shape effect of the elastic modulus of metal nanowires. The cross-sections (STEM) are grouped by their size and shape.
Lilian Maria Vogl, Peter Schweizer, Gunther Richter & Erdmann Spiecker
„Effect of size and shape on the elastic modulus of metal nanowires”
MRS Advances (2021)