Ostwald Ripening of Liquid-Metal-Grown Micropattern-Confined Crystals by Solid-Phase Diffusion

The application spectrum of liquid metals as solvents in crystal synthesis is fast expanding. Harnessing liquid metal-mediated crystal growth with high spatial resolution is essential for the precise micro/nanopatterning of functional crystals. However, crystal growth under boundary confinement and postgrowth crystal evolution driven by solid-phase diffusion remains underexplored. Here, we investigate the evolution of AuGa₂ intermetallic crystals formed by touch transfer of a liquid Ga layer onto lithography-patterned Au thin films. We demonstrate postgrowth coarsening of the as-grown AuGa₂ crystals via Ostwald ripening, sustained by mass transport through a solid Ga phase. Three-month observations reveal that this ripening is a long-term effect that progressively diminishes over time. Pattern width and edge features are found to modify the local Ga/Au thickness, shifting phase equilibrium and thereby tuning crystal size and spatial distribution. These findings provide mechanistic insight for the precise control of crystal growth and patterning in liquid metal synthesis systems.