Phase selection behavior of nanosized GaIn liquid alloys governed by mixing enthalpy

The properties of Ga-In-based liquid metal nanoparticles (NPs) are closely related to their microstructure. However, it remains a challenge to realize the controllable gas-phase preparation of such nanoparticles with a wide range of compositions and refined structures. In this study, a synergistic regulation strategy of the source state and deposition pathway during physical vapor deposition was proposed, enabling the preparation of Ga-In NPs over a wide composition range (In content from ∼13 wt% to ∼90 wt%) and with structures ranging from In-rich core-shell particles to homogeneous amorphous particles. The NP structure is strongly correlated with the In content, with a transition region centered near 55 wt% In. A Gibbs free-energy framework calibrated by this experimental critical composition rationalizes the phase-selection behavior: at high In contents, positive mixing enthalpy favours phase separation and core-shell formation, whereas in near-eutectic/Ga-rich compositions, the increasing interfacial-energy penalty inhibits phase separation and promotes homogeneous amorphous structures. This work provides an experimental route and a semi-empirical thermodynamic basis for designing Ga-In nanoparticles with targeted internal structures.