A radio-frequency glow discharge is used for the synthesis of submicron, amorphous, silicon nitride precursor powders from silanc and ammonia. Powders are produced with a range of Si/N ratios, including stoichiometric, Si-rich, and N-rich, and contain substantial amounts of hydrogen. The powders appear to be similar to silicon diimide and are easily converted to oxide by water vapor. The powders lose weight and crystallize to a mixture of α and β–Si3N4 after prolonged heating at 1600 °C. Studies of spectrally and spatially resolved optical emission from the plasma are reported.