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Quasi-Two-Dimensional Gold Nanosheets with Ultrahigh Strength

Tong Zhang¹, Binglun Yin^1,2, Pan Wang³, Yang Gao^1,2,*

1 Department of Engineering Mechanics, Zhejiang University, No. 38 Zheda Road, Hangzhou, 310027, China
2 Center for X-Mechanics, Zhejiang University, No. 38 Zheda Road, Hangzhou, 310027, China
3 College of Optical Science and Engineering, Zhejiang University, No. 38 Zheda Road, Hangzhou, 310027, China

* Corresponding Author: Yang Gao. Email:

The International Conference on Computational & Experimental Engineering and Sciences 2023, 25(3), 1-2. https://doi.org/10.32604/icces.2023.010131

Abstract

Solid gold usually holds face-centered-cubic structure and relatively low strength of 102 MPa. When the dimension is reduced to the nanoscale, the strength of metal should increase accordingly, due to size effect or complex nanostructures [1-3]. However, reported maximum strength in gold nanostructures is yet considerably lower than the ideal strength (~6 GPa), referring to the stress at elastic instability in a defectfree crystal with infinite dimensions [3-5]. Herein, the ideal strength of gold is experimentally achieved in a quasi-two-dimensional defect-free single crystalline nanosheet with hexagonal-close-packed (HCP) structure. Ultrathin gold nanosheets with a high aspect ratio (lateral size >101 μm, thickness <10 nm) were synthesized using a wet-chemical method [6]. The HCP structure of the ultrathin nanosheets was confirmed by high resolution transmission electron microscopy. Nanoindentation measurements were performed on suspended gold nanosheets with various thicknesses using an atomic force microscope. The mechanical behavior exhibits strong thickness dependence, reaching a remarkable maximum strength of 6.0 GPa, when the thickness is less than 10 nm. First-principle calculations based on density functional theory were carried out to support the experiments. We attribute the ultrahigh strength to the unique defect-free HCP structure and strong surface effect.

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Keywords

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