This video shows a representation of the hexagonal crystal pattern that naturally occurs when the crystalline structure is formed. But the regular six-sided pattern doesn't fit perfectly around the spherical droplet, so defects also appear. Researchers found that inserting an interstitial particle (black) causes rearrangements to the lattice that allow 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.
Credit: William Irvine, University of Chicago