title: Nucleation and crystal growth in sheared granular sphere packings.
abstract: We investigate the nucleation of ordered phases, their symmetries, and distributions in dense frictional hard sphere packings as a function of particle volume fraction ϕ, by imposing cyclic shear and constant applied pressure conditions. We show, with internal imaging, that the nucleating crystallites in the bulk consist of 10-60 spheres with hexagonal close packed (hcp) order and nonspherical shape, that are oriented preferentially along the shear axis. Above ϕ=0.62±0.005, crystallites with face centered cubic (fcc) order are observed with increasing probability, and ordered domains grow rapidly. A polycrystalline phase with domains of fcc and hcp order is observed after hundreds of thousands of shear cycles.
authors.affiliation: Department of Physics, Clark University, Worcester, Massachusetts 01610, USA.
authors.forename: Andreea
authors.initials: A
authors.lastname: Panaitescu
authors.forename: K Anki
authors.initials: KA
authors.lastname: Reddy
authors.forename: Arshad
authors.initials: A
authors.lastname: Kudrolli