Si and N K-XANES spectroscopic study of novel Si–C–N ceramics

Abstract

Abstract X-ray absorption near edge structure (XANES) measurements at the Si and N K-edges of ternary Si–C–N compounds are applied to analyze the changes of structural units owing to the thermally induced ceramization of silicon dicarbodiimide Si(NCN) 2 at temperatures up to 1600°C. Samples synthesized below 800°C show an environment of silicon consisting of carbodiimide (NCN) groups. Further annealing leads to a crystalline phase, Si 2 CN 4 , which combines the structural units (Si–N–Si) and (Si–NCN). Recorded spectra of samples annealed at temperatures higher than 1200°C show the decomposition of Si 2 CN 4 . The material then transforms to a Si 3 N 4 –SiC composite material through an intermediate amorphous Si–C–N phase.