Formation of metallic nano-crystals from gel-like precursor films for CVD nanotube growth: An in-situ TEM characterization

The evolution of a continuous Fe(NO3)3 catalyst film was observed by in-situ annealing in a Transmission Electron Microscope (TEM). Such catalysts are routinely used in the catalytic growth of carbon nanotubes. The experiments reveal that crystalline particles form from the gel-like film already around 300C. At usual carbon nanotube growth temperatures of 700C, the particles are single-crystalline with a log-normal size distribution. The observations furthermore show that in spite of the crystalline structure of the particles there is a high mobility. The experiments allow to obtain detailed information about the chemistry and the crystallinity of the catalyst film, which provides valuable information for the interpretation of the carbon nanotube growth by chemical vapor deposition.