LASER-DRIVEN SYNTHESIS OF NANOCRYSTALLINE ALUMINA POWDERS FROM GAS-PHASE PRECURSORS

Carbon dioxide laser synthesis from gaseous precursors has been successfully applied to produce nanosized Al2O3 particles. Trimethylaluminum [Al(CH3)3] and nitrous-oxide (N2O) were used as gas phase reactants. Ethylene (C2H4) was added as sensitizer gas. The as-synthesized powder particles showed considerable carbon contamination and an amorphouslike structure. After thermal treatment at 1200-1400-degrees-C, the powder transformed to hexagonal alpha-Al2O3 With very low carbon contamination, confirmed by x-ray diffraction, x-ray photoelectron spectroscopy, and chemical analysis. The thermally treated powder was composed of spherical single-crystal nanoparticles with a mean size [D] of 15-20 nm, as determined by x-ray diffraction, electron microscopy, and Brunauer-Emmett-Teller specific surface measurements. The laser synthesized Al2O3 particles are suitable dispersoids for intermetallic alloy technology.