Synthesis of a Polyborosilazane and Its Conversion into Inorganic Compounds

A novel polyborosilazane was synthesized by reacting per‐hydropolysilazane with trimethyl borate. The chemical structure of this polymer was investigated by the techniques of infrared spectroscopy and nuclear magnetic resonance measurements. Amorphous silicon nitride was obtained by pyrolysis of this polymer in a stream of anhydrous ammonia to 1000°C with high ceramic yield. The pyrolysis product remained amorphous after additional heating to 1700°C under N 2 . Crystallization to α‐Si 3 N 4 and β‐Si 3 N 4 proceeded with heat treatment at 1800°C under N 2 . These results indicate that polyborosilazane is a good precursor for amorphous silicon nitride based materials.