Multi-wall carbon nanotubes with uniform chirality: evidence for scroll structures

Multi-wall carbon nanotubes (MWCNT) obtained by catalytic decomposition of iron phthalocyanine are investigated by high resolution electron microscopy and electron diffraction (ED). The evaluation of the ED patterns shows that all MWCNTs studied have a uniform chirality, i.e. all tubes of a given MWCNT show the same chiral angle. The conditions for the formation of nested tubes are discussed. A comparison of the values of the chiral angles with those of the corresponding interwall spacings, both obtained from the ED patterns, leads to the conclusion that these MWCNTs have a scroll structure, very probably consisting of one single rolled-up graphene sheet.