Structural and morphological characterization of carbon materials by image analysis of microscopic appearances

Techniques for the structural and morphological characterization of carbon materials using microscopy and image processing are reviewed. These techniques are high resolution transmission electron microscopy (HRTEM), three dimensional transmission electron microscopy (3D-TEM) and two dimensional fast Fourier transform (2D-FFT). They are applied to the structural analysis of carbon nanotubes loaded with metal particles, activated carbon, and thin graphite. A HRTEM with Cs corrector can achieve a high resolution of less than 0.1 nm even if the acceleration voltage is 80 kV. The more precise three dimensional structure of the carbon nanotubes and activated carbon can be revealed by using 3D-TEM combined with HRTEM. The 2D-FFT of lattice images of HRTEM can analyze the structure of nano structured carbons, like selected area electron diffraction (SAED) which is difficult to apply to the microscopic area. 2D-FFT can be an alternative technique to SAED for nano-size analysis. HRTEM, 3D-TEM, and image processing thus can provide a powerful tool for the analysis of the structure and morphology of nanostructured carbons.