Nucleation of athermal hard spheres

Author :Frank Rietz, Charles Radin, Harry L. Swinney, Matthias Schröter
Year :2017
DOI: : arXiv:1705.02984

We present an experiment with packings of macroscopic spheres that model disordered and
jammed systems and provide insight into the less accessible atomistic world. Cyclically shear-
ing a packing of frictional spheres, we observe a first order phase transition from a disordered to an
ordered state. A homogeneously nucleating phase with mixed face centered cubic and hexagonally
close packed symmetry coexists with the amorphous bulk. The transition is characterized by a
nucleation barrier in the state with 64.5% space filling and manifests in predominant dissolving of
small nuclei and growth of nuclei that have reached a critical size of about ten spheres. The results
indicate that classical nucleation theory is not applicable if the nucleation barrier is identified with
a depleted region at the nucleus interfac