Effects of the Reaction Conditions in Preparation of Si3N4 Nanowires

X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the effects of reaction conditions (catalysts, reaction temperature and time) on the crystalline phases and morphologies of the carbothermal reaction products in the sol-gel synthesis of Si3N4 nanowires. The results showed that Si3N4 nanowires could be obtained with high yield by using xerogel, which produced a mixture with 5% (w) Fe after carbonization, with a controlling reaction temperature and time of 1300 °C and 10 h, respectively. The products obtained by using different additives had different crystalline phases. The content of additives also influenced the morphologies of the products. With increasing the reaction temperature or extending the reaction time, the products underwent a phase transformation of SiOx→Si2N2O→Si3N4. In the presence of metals, Si3N4 nanowires were produced with the help of the vapor-liquid-solid mechanism.