A method for structural characterization of the range of cylindrical nanocarbons: Nanotubes to nanofibers

Given the wealth of carbon multi-walled carbon nanotubes (MWNTs) and nanofiber synthesis strategies and resulting forms, there is an increasing need to better classify these materials in terms of their nanostructure. Apart from distinguishing the different nanoforms, such classification may be particularly useful for relating MWNT or nanofiber performance within various applications to their nanostructure. Demonstrated here is the use of image analysis algorithms applied to high resolution transmission electron microscopy (HRTEM) images of MWNTs and nanofibers. The analysis of the HRTEM images allowed for four separate measurements to quantify the graphitic content of the nanotube and nanofiber samples. Each measurement was based upon the features of individual carbon layer plane segments, which appear as fringes in HRTEM images. These measures included fringe length, separation, tortuosity and orientation. Distributions in the form of histograms serve to quantify data contained in the HRTEM images as represented by these parameters. Such information can serve as a measure of the physical characteristics and resulting chemical and mechanical properties of the nanotubes, nanofibers and their utility in applications.