Low-Temperature Preparation of Single Crystal Titanium Carbide Nanofibers in Molten Salts

The synthesis of single crystal titanium carbide (TiC) nanofibers has been investigated by the reaction of carbon sources of various sizes and microstructures with an equimolar mixture of titanium dioxide (TiO2) and titanium metal powders, in a molten salt medium. The carbon sources included carbon lamp black, thermal carbon black, pyrolytic carbon black, and multiwalled carbon nanotubes (MWCNTs). The reaction of titanium with TiO2 in molten salt to form titanium monoxide and the absence of reaction of titanium oxides with carbon nanotubes in molten salt is also reported. A reasonable yield of single crystal TiC nanofibers can only be achieved with the pyrolytic carbon black and MWCNT carbon sources. The product needs purification in hydrofluoric acid to remove TiO2 surface contamination. Four-point electrical measurement of a purified nanofiber in a dual scanning electron microscope-scanning tunneling microscope (SEM-STM) nanoprober confirms the stoichiometry TiCx to be x = 0.95. The results suggest that critical factors in the formation of single crystal TiC nanofibers in molten salts are that the carbon source should contain graphitic material and possess a length-scale in the nanometer range and that a near equimolar mixture of TiO2 and Ti is used.