Tubular configurations and structure-dependent anisotropic strains in GaS multi-walled sub-microtubes.

Bending strains and bonding structures of GaS multiwalled submicrotubes have been examined by transmission electron microscopy. Experimental observations reveal that the strain involved in building the GaS tubes is more complicated than the theoretical prediction and appears anisotropic and dependent on the tubular configurations. The armchair tube bears a larger lattice compression than the zigzag tube. The hexagonal GaS semiconducting compound degrades its crystal symmetry upon bending, leading to the anisotropy of the bonding structures. Curving of GaS sheets to form tubes is found to be dominated by the structures and electrostatic fields on the sheet surface, which eventually gives a well-controlled tubular structure showing preferred zigzag and close-to-zigzag configurations. Finally, interlayer packing structures of multiwalled tubes are examined.