Dresden 2014 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 18: Granular Matter / Contact Dynamics
DY 18.7: Talk
Wednesday, April 2, 2014, 11:15–11:30, ZEU 118
Observation of homogeneous crystallization in sphere packings — •Frank Rietz1, Charles Radin2, Harry L. Swinney3, and Matthias Schröter1 — 1Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Goettingen, Germany — 2University of Texas at Austin, Department of Mathematics — 3University of Texas at Austin, Center for Nonlinear Dynamics
Sphere packings serve as a model for the microscopic structure of matter. Similar to atoms, spheres arrange in disordered and ordered phases. The densest disordered packing that is achievable for many experimental protocols is known as Random Close Packing. Frustration inhibits further increase of the density by crystallization. The theoretical picture of this barrier is still unclear.
In our experiment the sphere packing is driven by periodical tilting of the container side walls. Three-dimensional information is obtained by an index matching technique [1]. The initial disordered packing compacts and above the Random Close Packing density we observe homogenous crystallization of the interior spheres. We characterize this first order phase transition by measurement of local volumes, crystal growth rates and critical nucleus size. Investigation of local structural changes allows us to better understand the jamming at the Random Close Packing density.
[1] J. A. Dijksman et al., Rev. Sci. Instrum. 83, 011301 (2012).