Atomic-Level Exploration of Local Structural Heterogeneity in Liquid Ga–In Alloys Using a Machine Learning Potential

Liquid gallium–indium (Ga–In) alloys have emerged as an intriguing class of materials that combine the advantages of both metals and liquids. Their unique properties enable a range of potential applications in chemistry, physics, materials, and engineering. Thus, elucidating the local structural properties of liquid Ga–In alloys at the nanoscale is essential for understanding the processes occurring within them and for advancing new applications. Here, we performed an atomic-level investigation of local coordination behavior and structural ordering around Ga and In atoms in five liquid Ga–In alloys (i.e., Ga79.3In20.7, Ga83.2In16.8, Ga85.8In14.2, Ga91.8In8.2, and Ga96.9In3.1) using machine learning force field molecular dynamics simulations. Our findings reveal that the Ga79.3In20.7, Ga83.2In16.8, and Ga85.8In14.2 alloys exhibit a continuous and predominant Ga–In phase, which is characterized by a spatial distribution of clustered In atoms. In stark contrast, the Ga91.8In8.2 and Ga96.9In3.1 alloys demonstrate the coexistence of pure Ga and Ga–In alloy phases, with In atoms forming dimers in the former and being atomically dispersed in the latter. More importantly, it is shown that there is a prominent difference in the local structural ordering surrounding Ga and In atoms in the first three Ga–In alloys, following a specific order of In–In > Ga–In > Ga–Ga, which is ascribed to the differences in interaction strengths. Overall, this study presents the first theoretical evidence of local structural heterogeneity in liquid Ga–In alloys and offers new insights into the nanoscale structural details in liquid Ga-based alloys.