PXRD pattern. The main disagreement can be seen on the
peak at about 2θ = 40°. This could be caused by neglecting
possible preferred orientations of nanotubes in the calculations.
Our specimens for PXRD in reflection mode were
prepared on glass substrate. It is very probable that the
nanotubes were lying on the holder so that in symmetrical
Bragg–Brentano diffraction they can be hardly seen along
the b axis. Preliminary studies of preferred orientation with
the aid of the Eulerian cradle showed significant changes
of the diffraction pattern with the specimen inclination and
the narrow diffraction peak 020 increased with the sample inclination.