a1 Department of Chemistry Washington University, St. Louis, Missouri 63130-4899
a2 Department of Mechanical Engineering, Washington University, St. Louis, Missouri 63130-4899
a3 Department of Physics, Washington University, St. Louis, Missouri 63130-4899
Nanocrystalline TiB2 is prepared by reaction of NaBH4 and TiCl4. The initial solution-phase reaction affords an amorphous precursor powder from which 5-100 nm TiB2 crystallites are obtained upon annealing at 900-1100 °C. Crystallite sizes depend on the annealing temperature and other processing parameters. Crystallite morphology is size dependent; crystallites smaller than 12-15 nm are cuboidal, whereas crystallites larger than 12-15 nm are hexagonal platelets. The procedure affords gram quantities of the smallest available TiB2 nanocrystallites.
(Received April 10 1995)
(Accepted June 30 1995)