A SYNTHESIS OF MONO-CRYSTALLINE SILICON-NITRIDE FILAMENTS

A catalytic process for synthesis of pure, mono-crystalline alpha-Si3N 4 filaments, with iron particles of some micrometres in diameter as ca talyst, was investigated. Silicon subhydrides, produced in situ by rea ction of silicon powder with hydrogen at 1300-degrees-C, were used as the silicon source. Experiments with molecular nitrogen as the nitroge n source failed, but the use of ammonia was successful. At 1300-degree s-C mono-crystalline alpha-Si3N4 filaments up to some micrometres in d iameter and some centimetres in length were successfully produced. The se filaments exhibit tensile strength values between 30 and 50 GPa, an d Young's modulus values between 550 and 750 GPa.