Well-crystallized straight Si nanowires (SiNWs) were successfully prepared in large scale via a facile reaction between NaN3 and Na2SiF6 at 600 degrees C without using any catalyst Characterization by X-ray powder diffraction and transmission electron microscopy demonstrates that the as-obtained product is pure-phase cubic SiNWs with diameters of 40 nm or so and lengths of several micrometers And the SiNWs with spherical tips can be obtained at a temperature as low as 300 degrees C Heating temperature and holding time have crucial influence on the synthesis and morphology of the SiNWs An oxide-assisted growth mechanism is responsible for the formation of the SiNWs (C) 2010 Elsevier B V All rights reserved