Effects of local gas-flow field on synthesis of oxide nanowires during thermal oxidation

Ω-shaped copper specimens are oxidized in wet air. The results show that totally no-wire structure, CuO whiskers, and the high density of well-aligned CuO nanowires can be formed simultaneously on the different positions of the specimen. A three-dimensional flow simulation results indicate that the direction of velocity vectors of local gas flow affects the alignment of nanowires during oxidation while the shear stress of flowing gas near the surface of a Ω-shaped specimen controls the density of nanowires.