Nanocolloidal Chemistry in Liquid Metal Media

Liquid metals (LMs) combine metallic conductivity with fluidic behaviour, enabling solvation and reactivity unattainable in conventional solvents. Yet, the atomic-scale chemistry governing solvation, dissolution, and crystallisation in these systems remains poorly understood. This thesis develops experimental and analytical methods to directly observe these processes in Ga-based LM alloys. A high-temperature sonication method using molten sodium acetate (NaOAc) was devised to synthesise homogeneous Ga-alloy nanodroplets. This approach enables controlled formation of transition-metal colloids (Cu, Ag, Au, Pd, Bi, Zn) suspended in Ga with tunable composition and nanometric droplet size. The resulting nanodroplets with solid intermetallic cores encapsulated by liquid Ga provide a platform for real-time studies of dissolution and crystallisation. In-situ transmission electron microscopy (TEM) revealed sequential dissolution and re-precipitation of intermetallic phases (e.g., CuGa₂) in the Cu–Ga system, confirming nanoscale solvation consistent with bulk phase diagrams. A key discovery made in this work is surface liquefaction, wherein the intermetallic–liquid interface for different alloys spontaneously forms a semi-liquid layer. For Cu-Ga specifically, surface liquefaction was exaggerated and demonstrated that several nanometres at room temperature fluctuated between a solid and liquid state. Molecular dynamics (MD) simulations attribute this to facet-specific atomic binding differences that induce localised melting, enhancing solubility and diffusivity. Size-dependent thermal behaviour, including suppressed melting points occur due to temperature depreciation induced by size effects. However, competing Laplacian pressures also stabilises the temperature variations, thereby affecting solubility effects. Extending to solubility–temperature relationships, a few systems were looked at i.e., Cu–Ga, Ag–Ga, Au–Ga, and Pd–Ga systems including a multicomponent liquid metal alloy (MCLMA). Ag₇Ga₃ from the MCLMA demonstrated segregation, whereas Au, Pd, and Cu shared a crystal structure. The combination of in-situ TEM, and simulations established a unified framework for diffusion and crystallisation in LM solvation. This work introduced a transferable methodology and provides a foundation for characterising LM systems.