Infusing “life” into crystals: Scientists progressing towards self-repairing materials

Without the specialized light, the particles pretty much vibrated in place like so many tiny idling engines. When the scientists turned on the light, the hydrogen peroxide and hematite began a chemical reaction that propelled the particles forward.

The scientists watched under a microscope as, at first, the particles moved about at random. Then, about 25 seconds into the chaos, the limited space and directionless driving produced a traffic jam of particles, said study leader Jeremie Palacci, a postdoctoral fellow at NYU.

The jammed particles forced themselves against each other in the pattern of a crystal, each dot surrounded by six others in a hexagonal shape. When they reached a certain size, some of the particles on the edge broke off and grew into other crystals, which slowly moved about.