Sommaire:

We compressed a 2D binary crystal into a glass in simulation. It exhibits a drastic structural change, in contrast to the conventional glass transition from a supercooled liquid where the structure changes little.
We identified the boundary between polycrystal and glass from various mechanical, structural, dynamic, and thermodynamic features. In addition, we identified Hall-Petch and inverse-Hall-Petch regimes in 2D polcrystals and three glass regimes. In the second part, we experimentally studied the relaxations of 2D bidispersed colloidal glasses near its surface during and after the vapor deposition. We observed the surface mobile layer at the single-particle level, and further discovered a middle layer which relaxes via large and anisotropic cooperative motions. It released free volumes towards the surface, leaving a more compact bulk glass. This novel relaxation mode in the middle layer cast light on the ultrastable glasses formed by vapor deposition.

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