Grain Boundary Scars and Spherical Crystallography

TL;DR

This paper investigates the structure of spherical crystals formed by beads on water droplets, revealing universal high-angle grain boundary scars that grow linearly with system size, advancing understanding of particle arrangements on curved surfaces.

Contribution

It provides experimental evidence of universal grain boundary scars in spherical crystals and quantifies their defect growth relative to system size.

Findings

High-angle grain boundary scars form above a critical size.

Number of defects in scars grows linearly with system size.

The defect growth rate is expected to be universal.

Abstract

We describe experimental investigations of the structure of two-dimensional spherical crystals. The crystals, formed by beads self-assembled on water droplets in oil, serve as model systems for exploring very general theories about the minimum energy configurations of particles with arbitrary repulsive interactions on curved surfaces. Above a critical system size we find that crystals develop distinctive high-angle grain boundaries, or scars, not found in planar crystals. The number of excess defects in a scar is shown to grow linearly with the dimensionless system size. The observed slope is expected to be universal, independent of the microscopic potential.