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

Carbon dioxide laser synthesis from gaseous precursors has been succes sfully 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 amorphousli ke structure. After thermal treatment at 1200-1400-degrees-C, the powd er transformed to hexagonal alpha-Al2O3 With very low carbon contamina tion, 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 n m, as determined by x-ray diffraction, electron microscopy, and Brunau er-Emmett-Teller specific surface measurements. The laser synthesized Al2O3 particles are suitable dispersoids for intermetallic alloy techn ology.