Aerosol Synthesis of Spherical Morphology Boron Nitride Powders from Organoborate Precursors

Abstract

The reaction of aerosol droplets of the organoborate reagent (MeO)3B, suspended in nitrogen, with gaseous ammonia in a flight tube heated to 800−1500 °C was used to produce, in high yield, spherical morphology precursor powders BNxOyCz that contain decreasing amounts of oxygen and carbon as the process temperature and mole fraction of ammonia increased. Subsequent static nitridation of the precursor powder under ammonia gave spherical morphology BN powders with low (<1 wt %) oxygen and carbon contents. The powders were characterized by elemental analysis, DRIFT-IR, XRD, SEM, and TEM methods. A weak molecular complex (MeO)3B·NH3 has been previously reported to exist, and this species was isolated and structurally characterized by single-crystal X-ray diffraction methods. Aerosol conversions using (MeO)3B/MeOH, H3BO3/MeOH, and B2O3/MeOH solutions were also examined, and the results are briefly described.