Silicon Nitride Derived from an Organometallic Polymeric Precursor: Preparation and Characterization

Abstract

Partially crystalline Si 3 N 4 , with nanosized crystals and a specific surface area greater than 200 m 2 /g, is obtained by pyrolysis of a commercially available vinylic polysilane in a stream of anhydrous NH 3 to 1000°C. This polymer does not contain N initially. Crystallization to high‐purity α‐Si 3 N 4 proceeds with additional heating above 1400°C under N 2 . The changes in crystallinity, powder morphology, infrared spectra, and elemental compositions, for samples annealed from 1000° to 1600°C under N 2 , are consistent with an amorphous‐to‐crystalline transformation. Although macroscopic consolidation and local densification occur at 1400°C, volatilization and accompanying weight loss limit bulk densification. The effect of temperature on specific surface area is examined and related to the sintering process. These results are applicable to pyrolysis, decomposition, and crystallization studies of ceramics synthesized by polymeric precursor routes.