Diamond has long been regarded as the practical and theoretical hardness champion and has found uses ranging from industrial abrasives to a girl's best friend. Cubic boron nitride, a synthetic material, comes in at second place. That is, until researchers got their hands on an alternate crystal structure of boron nitride and observed a unique atomic bond rearrangement under high stresses. These vaulted it above diamond for raw hardness, but it didn't wind up keeping the crown long.
Alternate crystal structures sharing the same chemical composition, called allotropes, are common in nature. The different atomic bond orientations and planes of symmetry within the crystal give rise to different physical properties. Researchers had investigated the Wurtzite structure of boron nitride (w-BN, a repeating array of hexagons in 3-dimensional space) in the past, but it had inferior properties to the cubic structure of boron nitride mentioned above.
Click here to read the rest of this article
Bekijk het gehele bericht
