Novel technique for synthesis of silicon nitride nanowires

Silicon nitride nanowires have been prepared by carbothermal reduction followed by nitridation of silica gel by in situ generation of ultrafine carbon as well as nitrogen over a temperature range of 1200–1350°C. Before the heat treatment dry silica gel is subjected to repeated evacuation followed by purging with ammonia. Ammonia is adsorbed on the silica gel surface and forms a ≡Si–NH2 bond which acts as a source of in situ generation of nitrogen and decomposition of dextrose provides ultrafine carbon respectively at the reaction temperature. During a high temperature heat treatment ultrafine carbon reduces the partial pressure of oxygen required for the generation and stabilisation of silicon nitride nanowires. The nanowires synthesised by this process are of 20–40 nm diameter and ∼1 μm length. The nanowires are characterised by XRD and filed emission SEM and EDAX.