Figure 1: (a) Schematic diagonal junction between zigzag (8,0) and (14,0) nanotubes. The shaded region is the wedge (W) part between the two straight-cut tubes. The circles mark the positions of the octagonal defects 8R and 8N. Their atomic structure is also shown. (b) The junction showing all the edge atoms in the wedge and the unrolled unit cells of the (8,0) and (14,0) tubes. Filled and empty circles mark atoms of different sublattices. Dotted lines indicate the connections between the edge atoms of the nanotubes and the wedge. Short bold, red line in the right apex of the wedge marks the connection which reconstructs the 8N octagon into a pair of two pentagons. (c) Schematic unit cell of the (8,0)/(14,0) superlattice, with the two complementary wedges inside.