Formation of Curved Micron-Sized Single Crystals

TL;DR

This paper demonstrates a novel method for growing curved micron-sized gold single crystals directly from eutectic melt droplets, with control over their curvature through environmental parameters, supported by an energetic growth model.

Contribution

It introduces a new fabrication technique for curved single crystals and provides an energetic model explaining their formation without additional processing.

Findings

Curved gold single crystals can be grown from eutectic melt droplets.

Crystals' curvature is controllable via environmental parameters.

The energetic model predicts conditions favoring curved crystal growth.

Abstract

Crystals in nature often demonstrate curved morphologies rather than classical faceted surfaces. Inspired by biogenic curved single crystals, we demonstrate that gold single crystals exhibiting curved surfaces can be grown with no need of any fabrication steps. These single crystals grow from the confined volume of a droplet of a eutectic composition melt which forms via the dewetting of nanometric thin films. We can control their curvature by controlling the environment in which the process is carried out, including several parameters, such as the contact angle and the curvature of the drops by changing the surface tension of the liquid drop during crystal growth. Here we present an energetic model that explains this phenomenon and predicts why and under what conditions crystals will be forced to grow with the curvature of the micro droplet even though the energetic state of a curved single crystal is very high.