In situ Microscopy Studies of Liquid Gallium Droplet Dynamics

Liquid metals such as gallium and related alloys are promising as hydrogenand energy-storage materials [1], for battery electrodes [2], in mercury-free thermometry [3], as plasmonic coupling materials [4], in electrical switches [5], as conductors in ultra-stretchable wires [6], and as catalysts for the growth of nanowires [7–8], and graphene [9–10]. This is largely due to their low vapor pressure, high wettability, and good thermal and electrical conductivities. All of these applications rely on understanding the thermochemical stability of liquid-metal/solid interfaces, since it affects adhesion, wettability, chemical reactivity, and optoelectronic properties. Here, we present results from in situ variable-temperature transmission electron microscopy (TEM) investigations of the thermal stability of liquid gallium on solid surfaces. From timeand temperature-dependent measurements of the observed droplet size changes, we can describe the mass transport mechanisms controlling the Ga droplet dynamics.