Two international teams of researchers have reached different conclusions about whether or not boron can form planar sheets similar to graphene. One team worked in the lab to identify hexagonal clusters of 36 boron atoms with a central hole. If joined together, the researchers believe that such structures could form a perfectly flat, atom-thick sheet that they have dubbed "borophene" – however, they have yet to see sheets. The second team used electronic-structure theory to calculate that such boron monolayers would spontaneously break down into bilayer structures. One of these bilayers would, the calculations suggest, have electronic properties similar to graphene, despite having a completely different atomic structure.
Graphene is a sheet of carbon just one atom thick that has attracted great interest because of its remarkable electronic and mechanical properties. Since graphene was first isolated in 2004, researchers have sought similar 2D materials, particularly those with different or complementary properties. One atom of interest is boron, which is the only non-metal in group three of the periodic table. Boron–boron bonds are not truly ionic, covalent or metallic. Instead, the bonds are both strong and highly delocalized. Like carbon, calculations suggest that boron should be able to form giant planar structures and fullerenes – structures such as buckyballs and nanotubes that have atom-thick skins. Indeed, boron nanotubes have been observed – although their precise structure remains uncertain. In 2007 Hui Tang and Sohrab Ismail-Beigi of Yale University predicted a stable planar boron structure containing regular hexagonal holes, which they called the α-sheet.To read more, click here.