Rare diamond with unique hexagonal structure is harder than natural counterpart

The first bulk synthesis of a carbon allotrope known as hexagonal diamond has been achieved, allowing extensive analysis of this unique and unusual material.

Diamond is one of the hardest materials known to exist in nature, arising from its structure in which carbon atoms covalently bond together in a perfect tetrahedral arrangement. Nearly 60 years ago, scientists predicted a harder, alternative form known as hexagonal diamond, which has a hexagonal lattice, rather than the cubic lattice adopted by conventional diamond.