A comparision of the structures for C, CN x and BCN nanotubes indicates that a pentagonal structure hybridized with both B and N has lower formation energy than with only N.

• B和N的同时掺杂 ；所形成的五边形结构比单独N掺杂时具有更低的形成能 ；是竹节状结构形成的主要原因 .