Carbon microtubes: tuning internal diameters and conical angles.

In this paper, we report a synthesis strategy for a new class of hollow, curved carbon morphologies, 'carbon microtubes' (CMTs), with absolute control over their conical angles and internal diameters. Our synthesis methodology employs nitrogen or oxygen dosing to change the wetting behaviour of gallium metal with the growing carbon walls to tune the conical angles. Increasing N(2) concentrations in the gas phase during growth increases the conical angles of CMTs from +25° to about -20°.

Crystalline boron nanowires.

Ideal nanowire interconnects for nanoelectronics will be refractory, covalently bonded, and highly conductive, irrespective of crystallographic orientation. Theoretical studies suggest that boron nanotubes should be stable and exhibit higher electrical conductivities than those of carbon nanotubes. We describe CVD growth of elemental boron nanowires, which are found to be dense nanowhiskers rather than nanotubes.