Microstructure and high temperature oxidation resistance of mixed long Si₃N₄ nanowires with wide diameter distribution

Herein, the mixed α-Si₃N₄ nanowires with large diameter differences (35–400 nm) were prepared by repeated re-filling of nitrogen gas during high temperature nitridation, and the length thereof was substantially above 500 μm (the longest length even could reach centimeter level). And there were significant differences in the interplanar spacing and growth direction of α-Si₃N₄ nanowires with different diameters. Moreover, the high temperature oxidation resistance of nanowires were systematically analyzed and obtained the following results: the oxidation reaction of Si₃N₄ nanowires became intensified significantly at about 1100 °C, and the diffraction intensity of Si₃N₄ in XRD patterns decreased with the increase of oxidation temperature until it was substantially oxidized to SiO₂ at about 1400 °C; and the changes in the microstructure of Si₃N₄ nanowires became more intense as the oxidation temperature increased until a significant shrinkage occurred at about 1400 °C, at which point it no longer exhibited a distinct nanowire morphology. The above studies may provide a reference for the further research and application of α-Si₃N₄ nanowires in the high temperature field. (paper)