Carbon nanocapsules and single-wall nanotubes formed by arc evaporation

Iron nanocrystals wrapped in graphitic carbon were produced by are evaporation of iron-carbon composites, and an excellent protective nature of the outer graphitic carbon against oxidation of the core crystallites was revealed by an environmental test (80 degrees C, 85% R.H., 7 days). Single-wall (SW) tubes were also produced by the are method with various catalysts, Fe, Co, Ni, F/Ni, La, and Ce. Growth patterns and morphology of SW tubes were classified into three groups: (i) tubes tangled with each other to form ''highway junction'' pattern for Co and Fe/Ni, (ii) long and thin tubes radially growing from Ni particles, and (iii) short and thick tubes growing from lanthanide compound particles.