Si3N4 single-crystal nanowires grown from silicon micro and   nanoparticles near the threshold of passive oxidation
  A simple and most promising oxide-assisted catalyst-free method is used to prepare silicon nitride nanowires that give rise to high yield in a short time. After a brief analysis of the state of the art, we reveal the crucial role played by the oxygen partial pressure: when oxygen partial pressure is slightly below the threshold of passive oxidation, a high yield inhibiting the formation of any silica layer covering the nanowires occurs and thanks to the synthesis temperature one can control nanowire dimensions. 
J. Farjas, C. Rath, A. Pinyol, P. Roura, E. Bertran