Droplets go skiing – at surprisingly high temperatures, we just published Physical Review Letters.
The droplets in this case are eutectic droplets. An eutectic is a mixture of two components that individually would both be solids, but the mixture is a liquid. Our droplets, composed of platinum and germanium, move on a heated substrate in the direction of the heat source. When we lower the temperature, they change their direction and start to ski: the droplets elongate and a solid layer is formed at the droplet – substrate interface. This solid is aligned with the substrate and determines the direction. Remarkably, this happens at a high temperature, 90 degrees above the eutectic point, where the whole droplet solidifies. Imagine skiing on ice skis at 90 °C! Below we show a video of the skiing (photo-emission electron microscopy, total duration is 2000 seconds, the field of view is 150 μm)
Currently, many (nano)structures are grown in very similar conditions to the ones studied here. Our work contributes toward understanding the underlying mechanisms leading to more perfect materials for use in nanotechnology and materials science.
Interested in reading more? Here's the link to our research paper: https://doi.org/10.1103/PhysRevLett.131.106201