Silicon nanowires were prepared by a thermal evaporation Of MoSi2 heating rods under controlled temperature and atmosphere. Transmission electron microscopy and selected area electron diffraction show that the nanowire consists of a crystalline Si core and an amorphous SiOx shell. There exist two major forms of nanowires possessing different morphologies and growth directions, which may indicate that different mechanisms predominate in the growth process. The photoluminescence of the Si/SiOx core-shell nanowires presents two emission bands, around 550 and 600 nm, respectively. (C) 2003 Elsevier B.V. All rights reserved.