Long Si nanowires were tried to form using a thermal gradient evaporation method. Amorphous SiO2/Si nanowires longer than 6 mm were formed at 1403-1433 K. The long nanowires consist of a silicon single core of 50-100 nm in diameter and an amorphous SiO2 outer layer of 10-15 nm in thickness. The growth direction of the long Si nanowires was (I 1 1). The nanowires showed IR absorption peaks at 1130, 1160 and 1200 cm(-1) due to the disordered structure of SiO2/Si nanowires. (C) 2004 Published by Elsevier B.V.