Compression of freestanding gold nanostructures: from stochastic yield to predictable flow

Abstract

Characterizing the mechanical response of isolated nanostructures is vitally important to fields such as microelectromechanical systems (MEMS) where the behaviour of nanoscale contacts can in large part determine system reliability and lifetime. To address this challenge directly, single crystal gold nanodots are compressed inside a high resolution scanning electron microscope (SEM) using a nanoindenter equipped with a flat punch tip. These structures load elastically, and then yield in a stochastic manner, at loads ranging from 16 to 110 microN, which is up to five times higher than the load necessary for flow after yield. Yielding is immediately followed by displacement bursts equivalent to 1-50% of the initial height, depending on the yield point. During the largest displacement bursts, strain energy within the structure is released while new surface area is created in the form of localized slip bands, which are evident in both the SEM movies and still-images. A first order estimate of the apparent energy release rate, in terms of fracture mechanics concepts, for bursts representing 5-50% of the structure's initial height is on the order of 10-100 J m(-2), which is approximately two orders of magnitude lower than bulk values. Once this initial strain burst during yielding has occurred, the structures flow in a ductile way. The implications of this behaviour, which is analogous to a brittle to ductile transition, are discussed with respect to mechanical reliability at the micro- and nanoscales.

Reducing the Adhesion between Surfaces Using Surface Structuring with PS Latex Particle

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Compression Experiments on γ′-Nanoparticles

“…The utilization of microscopically small components in mechanically loaded microsystems requires (i) development of suitable fabrication processes on the micro-and nanoscale, see, for example, Hoxhold and Büttgenbach [1] and Landefeld and Rösler [2] as well as (ii) understanding of the mechanical behavior at reduced dimensions, see for example, [3][4][5][6][7]. One way to obtain freestanding metallic components on the nanoscale is to extract precipitates from alloys and deform them between microhammer and microanvil in the scanning electron microscope (SEM).…”

Adhesion Control for Micro- and Nanomanipulation

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