# Binary icosahedral quasicrystals of hard spheres in spherical confinement

## TL;DR

This study demonstrates that binary hard-sphere particles in spherical confinement can spontaneously form 3D icosahedral quasicrystals and modify local symmetry, with implications for photonic materials and understanding crystallization processes.

## Contribution

It provides experimental and simulation evidence of 3D icosahedral quasicrystal formation in binary hard-sphere mixtures under spherical confinement, revealing nucleation and growth mechanisms.

## Key findings

- Binary mixtures form 3D icosahedral quasicrystals in droplets.
- Local symmetry shifts to MgCu2 Laves phase in most particles.
- Crystallization is robust to deviations in stoichiometry.

## Abstract

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.