Dense arrays of well-aligned carbon nanotubes completely filled with single crystalline titanium carbide wires on titanium substrates

We report the synthesis of dense and uniform arrays of well-aligned carbon nanotubes on titanium substrates over large areas, in which all the tubes are simultaneously and completely filled with single crystals of titanium carbide. The carbon nanotubes were synthesized by thermal chemical vapor deposition of ethylene on iron-coated substrates, while the titanium carbide was simultaneously formed inside the nanotubes through a simultaneous solid state reaction. We propose a base dissolution and precipitation mechanism for the growth of titanium carbide filled carbon nanotubes. The same method can be used to fabricate oriented nanotube arrays filled with other carbides on a variety of substrates over large scale. Such well-aligned and densely packed uniform carbon nanotubes, completely filled with nanowires on conducting substrates, will have great potential in many applications. (c) 1999 American Institute of Physics. [S0003-6951(99)01924-5].