Nanoparticle recrystallization: kinetics and size-dependent behavior

Recrystallization of metals plays a central role in materials processing as it represents a primary tool for manipulating material microstructure and properties. However, recrystallization has not yet been employed for the synthesis of metal nanoparticles. In this work we describe the kinetics of recrystallization and related annealing phenomena in Pt nanoparticles. We uniaxially deformed the particles and annealed them both in-situ and ex-situ while characterizing their morphology and microstructure. Our findings reveal that new grains often nucleate within the parent particle, only to be rapidly reabsorbed back into it, with a strong correlation between this phenomenon and particle size. We propose a model that combines recrystallization and recovery through dislocation annihilation at the particle surface, predicting a critical size for recrystallization in nanoparticles. Finally, we propose a set of rules for nanoparticle recrystallization, mirroring the rules of recrystallization in bulk materials.