PHASTRACK

In order to unlock specific technological applications, a complete control over the structure of a nanoparticle has become essential. For that purpose, temperature is a decisive external parameter driving the structure both during synthesis and during many practical uses, including cancer treatment and catalysis. While at bulk freezing and melting are already highly complex mechanisms of phase transitions, at the nanoscale, traditional thermodynamic considerations are challenged by the preponderance of surface and finite size effects. In this project, we will dynamically track temperature-induced phase transitions at the nanoscale using state of the art methods. We will use a threefold approach: (1) The synthesis of nanoalloys using pulsed laser ablation in liquids, allowing us to obtain diverse chemical compositions and morphologies; (2) The in-situ observation of melting processes using high-resolution transmission electron microscopy (TEM); (3) Machine-learning-assisted molecular dynamics simulations to complement experimental data, providing atomic-level insights into nucleation mechanisms. This proposal focuses on nanoalloys of gold with silver and iron, selected for their technological significance and distinct mixing properties (from highly miscible to partially miscible). The results will significantly advance our understanding of phase transitions and segregation in nanoalloys, contributing to the design of advanced nanomaterials with tailored properties.