Aligned CNx nanotubes by pyrolysis of ferrocene/C-60 under NH3 atmosphere

Aligned CNx (x < 0.1) nanotubes have been generated by pyrolyzing ferrocene /C-60 mixtures at 1050 degrees C in an ammonia atmosphere. The structure an d composition of the product were determined by high-resolution transmissio n electron microscopy and high spatial resolution electron energy-loss spec troscopy. The CNx tubes (15-70 nm diameter, < 50 mu m length) grown in larg e flakes (< 3 mm(2)) consist of a reduced number of "graphitic" layers (< 1 5 on either side) arranged in a bamboo-like structure. Areas of high nitrog en concentration were found within curved or corrugated "graphite-like" dom ains. The observation of a well-developed double peak in the sigma* feature of the N K-edge suggests that the material has not undergone the transitio n to the fullerene-like phase known for nitrogenated carbons. Incorporation of nitrogen from the gas phase (NH3) into CNx nanotubes therefore leads to improved and more efficient N substitution into the network as compared to the synthesis with solid nitrogen-containing precursors reported earlier. (C) 2000 American Institute of Physics. [S0003-6951(00)04638-6].