Using X-ray powder diffraction and principal component analysis to determine structural properties for bulk samples of multiwall carbon nanotubes

Abstract

It has been attempted to derive the structural properties of bulk multiwall carbon nanotubes (MWCNTs) from a combination of powder diffraction and principal component analysis (PCA). By a transformation of the direct PCA basis functions to a structural parameter set it was possible to obtain average values of inner radius, number of turns and d-spacing. The true tube lengths cannot be correctly estimated due to correlations to other properties, tube bending and defects in the tubes. Improvements can be expected by including distributions of the structural properties, further developing the functional relationships between the PCA and parameter functions and including the chiral angle (rolling direction) as a separate parameter.