The increasing importance of crystalline nanomaterials in nanotechnology has sparked much research towards controlling their structures and morphologies — which in turn determine their properties. Chromium silicide, a narrow-bandgap semiconductor with high melting point and resistance to oxidation, has attracted interest in a wide range of areas, including electronics and energy materials. Now, Tom Wu and co-workers from Nanyang Technological University in Singapore have prepared a chromium silicide single crystal that adopts an unusual hexagonal structure resembling a spider-web (pictured; J. Am. Chem. Soc. 132, 15875–15877; 2010).
Opposite sides of the nanowire segments are oppositely charged, which the researchers suggest is what induces the nanowebs' formation. This would also mean that the walls of the nanowires form charged planes perpendicular to that of the nanoweb, which is in good agreement with the structures observed, and is supported by calculations of the electrostatic energies for different bending possibilities. At most corners, depending on the distance between the walls, the nanowires either grow into a continuous nanoweb or reverse their direction — linear or zig-zag nanowires are only rarely observed.
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