Sol–gel synthesis of Si 3N 4 nanowires and nanotubes

Abstract

Silicon nitride nanowires and nanotudes were synthesized from a binary sol–gel route, in which tetraethoxysilane (TEOS) and phenolic resin were used to prepare a carbonaceous silica xerogel and ferric nitrate was employed as additive. Raw Si 3N 4 product was obtained by heating the xerogel at 1300 °C for 10 h in nitrogen flow (200 ml/min). The Si 3N 4 sample after purification was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersion X-ray (EDX) spectrum and selected area electron diffraction (SEAD). The results showed that the sample mainly consisted of α-Si 3N 4 nanowires with a few of nanotubes. Both the nanowires and nanotubes have a diameter of 30–100 nm and a length of hundreds microns. Liquid droplets were also found at the tip of the nanowires, and this indicated that the growth of the nanowires and nanotubes followed the vapor–liquid–solid (VLS) mechanism.