Structural studies of multiwall carbon nanotubes by neutron diffraction

We report on structural studies of multiwall carbon nanotubes by wide-angle neutron scattering up to a maximum scattering vector Q(max) = 166 nm(-1). The derived reduced radial distribution functions of the nanotubes are compared to those determined for graphite and turbostratic carbon, providing evidence that the stacking pattern of graphene tubules in multiwall carbon nanotubes is intermediate between those of the other two carbon forms. The (002) and (004) peaks of the nanotubes appear at smaller angles than graphite, yielding the intertubule spacing of 0.341 nm. At small length scales (less than or similar to 0.5 nm) the nanotube structure resembles that of graphite, including graphitelike interlayer correlations for at least a few adjacent layers. Beyond this range, a systematic decrease in peak amplitudes and deviation from the graphite structure is observed. [S0163-1829(99)06903-9].