Phase diagram and structural diversity of the densest binary sphere   packings
  The densest binary sphere packings have historically been very difficult to determine. The only rigorously known packings in the alpha-x plane of sphere radius ratio alpha and relative concentration x are at the Kepler limit alpha = 1, where packings are monodisperse. Utilizing an implementation of the Torquato-Jiao sphere-packing algorithm [S. Torquato and Y. Jiao, Phys. Rev. E 82, 061302 (2010)], we present the most comprehensive determination to date of the phase diagram in (alpha,x) for the densest binary sphere packings. Unexpectedly, we find many distinct new densest packings. 
Adam B. Hopkins, Yang Jiao, Frank H. Stillinger, and Salvatore   Torquato
cond-mat.stat-mech cond-mat.soft physics.atm-clus