MULTIPLY TWINNED ALUMINUM NANOPARTICLES

Multiply twinned oxide-free Al nanoparticles, with diameters of 2 nm t o 50 nm, were obtained from metastable theta-Al2O3 particles by an ele ctron beam irradiation technique using a high-resolution transmission electron microscope on a room-temperature stage. The phenomenon of for mation, the morphology and the multiply twinned structures of the Al n anoparticles were investigated by the in situ observation method. It i s clear that the morphology of polyhedral multiple twinned Al nanopart icles were mostly decahedra, and that the decahedra were categorized i nto pentagonal, spherical, ellipsoidal, and lamellar morphology. (C) 1 998 Acta Metallurgica Inc.