This video shows colloidal beads (bright dots) that have assembled themselves on a liquid droplet to form a three-dimensional curved crystalline structure. The positive electric charges cause the beads to repel each other, leading them to arrange themselves naturally in a honeycomb pattern with each particle equally distant from six others.
(Photo Credit: William Irvine, University of Chicago)
This video shows the hexagonal crystal pattern that naturally occurs when the crystalline structure is formed. The regular six-sided pattern imperfectly fits around the spherical droplet, so defects appear. Inserting an interstitial particle (black) allows the defect to "heal." The stresses caused by the extra particle can be seen in the creation of yellow and red shapes, which indicate particles coordinated with either five or seven others, as opposed to the normal six others.
(Photo Credit: William Irvine, University of Chicago)
Source: University of Chicago