  The influence of geometry on the local and global packing of particles is
important to many fundamental and applied research themes such as the structure
and stability of liquids, crystals and glasses. Here, we show by experiments
and simulations that a binary mixture of hard-sphere-like particles
crystallizing into the MgZn2 Laves phase in bulk, spontaneously forms 3D
icosahedral quasicrystals in slowly drying droplets. Moreover, the local
symmetry of 70-80% of the particles changes to that of the MgCu2 Laves phase.
Both of these findings are significant for photonic applications. If the
stoichiometry deviates from that of the Laves phase, our experiments show that
the crystallization of MgZn2 is hardly affected by the spherical confinement.
Our simulations show that the quasicrystals nucleate away from the spherical
boundary and grow along five-fold symmetric structures. Our findings not only
open the way for particle-level studies of nucleation and growth of 3D
quasicrystals, but also of binary crystallization.
